Showing 1–50 of 83 results for author: Lin, C

Determination of Tritium Content in D2 Gas and Heavy Water

Authors: Sandeep Puri, Noah D'Amico, Ian Jones, Sonny Alaniz, Andrew Gillespie, Cuikun Lin, R. V. Duncan

Abstract: A simple experimental method for the determination of tritium concentration in natural hydrogen and deuterium gas down to the femtomole level is described. Palladium and platinum catalysts were used to react hydrogen and oxygen, creating water that could be analyzed in a Revvity Quantulus GCT 6220. This analysis produced sub-femtomole detection limits of tritium present in hydrogen gas or heavy wa… ▽ More A simple experimental method for the determination of tritium concentration in natural hydrogen and deuterium gas down to the femtomole level is described. Palladium and platinum catalysts were used to react hydrogen and oxygen, creating water that could be analyzed in a Revvity Quantulus GCT 6220. This analysis produced sub-femtomole detection limits of tritium present in hydrogen gas or heavy water. A contamination level of $\sim 1\text{ femtomole/SL}$ was found in the $\text{D}_2$ gas sample that was analyzed. A contamination level of $\sim 0.025\text{ femtomole/SL}$, which is below the noise level of the Quantulus, was found in the standard hydrogen gas sample that was analyzed. The choice of palladium or platinum catalyst did not significantly affect the resulting tritium measurement. By showing that common $\text{D}_2$ samples can be contaminated with trace amounts of tritium orders of magnitude above natural abundance, this test demonstrates that a baseline tritium measurement for deuterium samples is highly important for determining the validity of results in nuclear fusion yield experiments. △ Less

Submitted 17 August, 2026; originally announced August 2026.

Comments: 7 pages, 1 figure, and 2 tables

Alpha Particle Induced Collision Cascade Fusion

Authors: Sandeep Puri, Noah D'Amico, Andrew Gillespie, Ian Jones, Cuikun Lin, Bo Zhao, R. V. Duncan

Abstract: We report experimental and computational investigations of a collision-cascade mechanism to induce deuterium-deuterium (D-D) fusion. Evidence of neutron production was observed from a pressurized deuterium target exposed to energetic alpha particles emitted by a $^{210}\text{Po}$ source. A 5-mCi $^{210}\text{Po}$ alpha source was placed within a chamber containing pressurized deuterium gas, and ne… ▽ More We report experimental and computational investigations of a collision-cascade mechanism to induce deuterium-deuterium (D-D) fusion. Evidence of neutron production was observed from a pressurized deuterium target exposed to energetic alpha particles emitted by a $^{210}\text{Po}$ source. A 5-mCi $^{210}\text{Po}$ alpha source was placed within a chamber containing pressurized deuterium gas, and neutron emission was monitored for 18 h using two Mirion SN-S $^{3}\text{He}$ neutron detectors. Alpha particles incident on pressurized deuterium gas produced an average excess of $\sim$74 neutrons after background subtraction, corresponding to a fusion neutron rate of $\sim$2.24 n/s. With LiD in the pressurized deuterium, the average excess increased to 268 neutrons, corresponding to 8.1 n/s. Since D-D fusion branches into two equally likely pathways, these correspond to a fusion rate near 4.5 and 16.2 fusions per second, respectively. MCNP simulations incorporating experimental geometry, source activity, and detector configuration predicted neutron yields within 5.4% of the measured values and reproduced the detector response within experimental uncertainty. The tight agreement between measured and simulated neutron counts suggests that energetic alpha-particle interactions within the deuterium may contribute to measurable D-D fusion reactions through the D(d,n)$^{3}\text{He}$ channel. △ Less

Submitted 10 August, 2026; originally announced August 2026.

Comments: 10 pages, 4 figures

Hyperon-Nucleon Spectrometer

Authors: Xiaozhi Bai, Xu Cao, Zhe Cao, Jinhui Chen, Kai Chen, Qibo Chen, Shi Chen, Xin Chen, Yuquan Chen, Zhenyu Chen, Jianping Dai, Heng-Tong Ding, Dongshuo Du, Shuxian Du, Limin Duan, Zhe Duan, Anhui Feng, Jie Feng, Yicheng Feng, Jinlin Fu, Xiaofeng Fu, Chaosong Gao, Liang Ge, Wenwen Ge, Lisheng Geng , et al. (215 additional authors not shown)

Abstract: Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $Λ$ polarization puzzle, in which $Λ$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse pola… ▽ More Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $Λ$ polarization puzzle, in which $Λ$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ($pp$), proton-nucleus ($pA$), and nucleus-nucleus ($AA$) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $pA$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China. △ Less

Submitted 4 June, 2026; originally announced June 2026.

Comments: 69 pages, Hyperon-Nucleon Spectrometer (H-NS) white paper

A cryogenic gas target for high-intensity radioactive ion beam production at HIRFL-RIBLL

Authors: Xiao Fang, Shiwei Xu, Longhui Ru, Ruiqi Chen, Bingshui Gao, Song Guo, Jun Hu, Huiming Jia, Xinyue Li, Chengjian Lin, Enqiang Liu, Chengui Lu, Junbing Ma, Jun Su, Xiaodong Tang, Jiansong Wang, Shengquan Yan, Lei Yang, Ruojun Yang, Yanyun Yang, Gaolong Zhang, Liyong Zhang, Ningtao Zhang, Zhichao Zhang

Abstract: A liquid-nitrogen-cooled cryogenic gas target system has been developed and installed for radioactive ion beam (RIB) production at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Light-element gases ($\mathrm{H}_2$, $\mathrm{D}_2$, and $^4\mathrm{He}$) filled in the target cell were cooled to cryogenic temperatures, with the gas-cell outlet temperature typically monitored at 82--86 K during beam… ▽ More A liquid-nitrogen-cooled cryogenic gas target system has been developed and installed for radioactive ion beam (RIB) production at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Light-element gases ($\mathrm{H}_2$, $\mathrm{D}_2$, and $^4\mathrm{He}$) filled in the target cell were cooled to cryogenic temperatures, with the gas-cell outlet temperature typically monitored at 82--86 K during beam irradiation and operating pressures up to 1000 mbar. The system was used to produce $^{7}\mathrm{Be}$, $^{16}\mathrm{N}$, and $^{15}\mathrm{O}$ RIBs via the $^{1}\mathrm{H}(^{7}\mathrm{Li}, ^{7}\mathrm{Be})n$, $^{2}\mathrm{H}(^{15}\mathrm{N}, ^{16}\mathrm{N})p$, and $^{1}\mathrm{H}(^{15}\mathrm{N}, ^{15}\mathrm{O})n$ inverse kinematics reactions, yielding purities of 85\%, 99\%, and 95\%, with intensities of $1.02\times10^{6}$, $2.7\times10^{5}$, and $1.0\times10^{5}$ pps, respectively. A $^{93m}\mathrm{Mo}$ isomer beam was also produced via the $\mathrm{^4He(^{94}Zr,} 5n)^{93m}\mathrm{Mo}$ reaction, achieving an intensity of $5.38\times10^{3}$ pps and a purity of 20\% (which can be further improved to $\sim$50\% with offline time-of-flight gating). By delivering a broader range of high-intensity secondary RIBs, this setup establishes a robust platform at RIBLL for low- and medium-energy nuclear astrophysics and reaction studies. △ Less

Submitted 28 June, 2026; v1 submitted 2 June, 2026; originally announced June 2026.

Production of Low-Density Aerogel Nuclear Fuels for Use in Fission Fragment Rockets and Novel Reactor Design

Authors: Noah D'Amico, Sandeep Puri, Ian Jones, Andrew Gillespie, Cuikun Lin, Bo Zhao, R. V. Duncan

Abstract: Graphene hydrogels were created and loaded with uranyl nitrate or thorium nitrate and freeze-dried to produce graphene aerogel nuclear fuels. These aerogels had densities between 0.018-0.035 g/cm3 and consisted of ~7.3 +- 0.5% uranium/thorium by mass. The ultra-low density of the aerogels allows for high energy ions to escape the fuel particles without depositing all their energy as heat, as is ty… ▽ More Graphene hydrogels were created and loaded with uranyl nitrate or thorium nitrate and freeze-dried to produce graphene aerogel nuclear fuels. These aerogels had densities between 0.018-0.035 g/cm3 and consisted of ~7.3 +- 0.5% uranium/thorium by mass. The ultra-low density of the aerogels allows for high energy ions to escape the fuel particles without depositing all their energy as heat, as is typical in nuclear fuels. Their measured alpha activity was ~16 pCi/mg, which could be enhanced up to ~49 pCi/mg by decreasing the thickness of aerogel samples to allow all alpha particles to escape. Additionally, high energy neutrons were used to induce fission to provide a source of fission fragments from the aerogel fuels. This novel form of nuclear fuel has potential applications in space propulsion such as fission fragment rocket engines, as well as in terrestrial applications for modular reactors, direct conversion methods, and in medical radiotherapeutics. △ Less

Submitted 13 March, 2026; originally announced March 2026.

Study of $\barΛ$-$p$ Annihilation into Light Mesons

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, Q. An, Y. H. An, Y. Bai, O. Bakina, H. -R. Bao, X. L. Bao, M. Barbagiovanni, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko , et al. (736 additional authors not shown)

Abstract: The annihilation of $\barΛ$-$p$ into light mesons is studied using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring. The $\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and interact with the protons in the hydrogen nuclei in the cooling oil of the beam pipe. The reactions $\barΛp\rightarrow K^+π^+π^-$ and $K^+2π^+2π^-$ are… ▽ More The annihilation of $\barΛ$-$p$ into light mesons is studied using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring. The $\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and interact with the protons in the hydrogen nuclei in the cooling oil of the beam pipe. The reactions $\barΛp\rightarrow K^+π^+π^-$ and $K^+2π^+2π^-$ are observed for the first time, evidence for the reaction $\barΛp\rightarrow K^0_S2π^+π^-$ is found, and no significant signals are seen for the reactions $\barΛp\rightarrow K^0_Sπ^+$, $K^+3π^+3π^-$ and $2K^+K^-$. The cross sections of these reactions are also measured at $P_{\barΛ}\approx 1.074$ GeV/$c$. Furthermore, no significant structures are observed in the combinations of the final state particles for these reactions. The annihilation of $\barΛ$-$p$ into light mesons presents the similar behavior as $\bar{n}$-$p$ reactions in this energy region. These new measurements will serve as important inputs for the theoretical understanding of the antihyperon-nucleon interaction, and further contribute to understanding antibaryon-baryon interaction in a unified perspective. △ Less

Submitted 4 February, 2026; originally announced February 2026.

Comments: 9 pages, 2 figures

Observation of $\barΛp\to K^{+}π^{+}π^{-}π^{0}$ and $\barΛp\to K^{+}π^{+}π^{-}2π^{0}$

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, C. S. Akondi, R. Aliberti, A. Amoroso, Q. An, Y. H. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, X. L. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. B. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko , et al. (728 additional authors not shown)

Abstract: Using $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.097$ GeV, the antihyperon-nucleon annihilation processes $\barΛ p \to K^+ π^+ π^- + kπ^0$ ($k=1,2,3$) are studied at an incident $\barΛ$ momentum of approximately 1.074 GeV/$c$. The reactions $\barΛ p \to K^+ π^+ π^- π^0$ and $\barΛ p \to K^+ π^+ π^- 2π^0$ are observed for t… ▽ More Using $(10087 \pm 44) \times 10^6$ $J/ψ$ events collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.097$ GeV, the antihyperon-nucleon annihilation processes $\barΛ p \to K^+ π^+ π^- + kπ^0$ ($k=1,2,3$) are studied at an incident $\barΛ$ momentum of approximately 1.074 GeV/$c$. The reactions $\barΛ p \to K^+ π^+ π^- π^0$ and $\barΛ p \to K^+ π^+ π^- 2π^0$ are observed for the first time, with corresponding cross sections $σ_{\barΛ p \to K^+ π^+ π^- π^0} = 8.5^{+1.2}_{-1.1} (\rm{stat.}) \pm 0.4 (\rm {syst.})$ mb and $σ_{\barΛ p \to K^+ π^+ π^- 2π^0} = 7.9^{+1.9}_{-1.7} \pm 0.4$ mb. No significant signal is found for $\barΛ p \to K^+ π^+ π^- 3π^0$, and an upper limit of 7.2 mb is set at a 90\% confidence level. An evidence for the $K^{*}(892)^+$ resonance is seen in the $K^+π^0$ invariant mass spectrum $M_{K^+π^0}$ for $k=1$, and the corresponding cross section for $\barΛ p \to K^{*}(892)^+ π^+ π^-$ is measured to be $σ_{\barΛ p \to K^{*}(892)^+ π^+ π^-} = 12.5^{+3.8}_{-3.4} \pm 1.2$ mb. Owing to the limited statistics, possible interference effects are not considered. These findings offer crucial input to deepen our understanding of the antihyperon-nucleon interactions. △ Less

Submitted 15 April, 2026; v1 submitted 1 February, 2026; originally announced February 2026.

Journal ref: Phys. Rev. Lett. 136, 171904 (2026)

Experimental study of the reaction $Ξ^{0}n\rightarrowΛΛX$ using $Ξ^{0}$-nucleus scattering

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (707 additional authors not shown)

Abstract: Using $(10087\pm44)\times10^{6}$$J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring in $2009$, $2012$, $2018$, and $2019$, we perform a search for the reaction $Ξ^0n\rightarrowΛΛX$, where $X$ denotes any additional final particles. Given the highly suppressed phase space for producing extra pions, the $X$ consists of either nothing or a photon, corresponding to the… ▽ More Using $(10087\pm44)\times10^{6}$$J/ψ$ events collected with the BESIII detector operating at the BEPCII storage ring in $2009$, $2012$, $2018$, and $2019$, we perform a search for the reaction $Ξ^0n\rightarrowΛΛX$, where $X$ denotes any additional final particles. Given the highly suppressed phase space for producing extra pions, the $X$ consists of either nothing or a photon, corresponding to the processes $Ξ^0 n \rightarrow ΛΛ$ and $Ξ^{0}n\rightarrowΛΣ^0\rightarrowΛΛγ$. The $Ξ^0$ comes from the decay of $J/ψ\rightarrowΞ^0\barΞ^0$, while the neutron originates from material of the beam pipe. A signal is observed for the first time with a statistical significance of 6.4$σ$. The cross section for the reaction $Ξ^0+{^9\rm{Be}}\rightarrowΛ+Λ+X$ is measured to be $(43.6\pm10.5_{\text{stat}}\pm11.1_{\text{syst}})$ mb at $P_{Ξ^0}\approx0.818$ GeV/$c$, where the first uncertainty is statistical and the second systematic. No significant $H$-dibaryon signal is observed in the $ΛΛ$ final state. △ Less

Submitted 26 February, 2026; v1 submitted 4 December, 2025; originally announced December 2025.

Comments: 9 pages, 3 figures

First Measurement of $π^+$-Ar and $p$-Ar Total Inelastic Cross Sections in the Sub-GeV Energy Regime with ProtoDUNE-SP Data

Authors: DUNE Collaboration, S. Abbaslu, F. Abd Alrahman, A. Abed Abud, R. Acciarri, L. P. Accorsi, M. A. Acero, M. R. Adames, G. Adamov, M. Adamowski, C. Adriano, F. Akbar, F. Alemanno, N. S. Alex, L. Aliaga Soplin, K. Allison, M. Alrashed, A. Alton, R. Alvarez, T. Alves, A. Aman, H. Amar, P. Amedo, J. Anderson, D. A. Andrade , et al. (1328 additional authors not shown)

Abstract: The ProtoDUNE-SP detector, a kiloton-scale prototype for the Deep Underground Neutrino Experiment (DUNE) far detector, is the largest liquid argon time projection chamber built to date. Operated at CERN from 2018 to 2020, it collected both cosmic-ray data and a beam consisting of positively-charged particles with discrete momentum settings across a range of 0.3 GeV/$c$ to 7 GeV/$c$. In this letter… ▽ More The ProtoDUNE-SP detector, a kiloton-scale prototype for the Deep Underground Neutrino Experiment (DUNE) far detector, is the largest liquid argon time projection chamber built to date. Operated at CERN from 2018 to 2020, it collected both cosmic-ray data and a beam consisting of positively-charged particles with discrete momentum settings across a range of 0.3 GeV/$c$ to 7 GeV/$c$. In this letter, we report the total inelastic cross section measurements for $π^+$--Ar and $p$--Ar interactions using selected $π^+$ and proton samples from the 1 GeV/$c$ beam data, spanning kinetic energies of 500--900~MeV and below 450~MeV, respectively. These energy ranges are directly relevant to hadrons produced in DUNE. The measured cross sections are consistent with predictions and provide a dataset that was previously unavailable for argon targets. These measurements are essential for constraining neutrino-argon interaction models and achieving the precision physics goals of the upcoming DUNE experiment. △ Less

Submitted 26 May, 2026; v1 submitted 14 November, 2025; originally announced November 2025.

Report number: FERMILAB-PUB-25-0814-LBNF, CERN-EP-2025-266

Threshold $J/ψ$ Photoproduction as a Probe of Nuclear Gluon Structure

Authors: J. R. Pybus, D. Dutta, H. Gao, O. Hen, I. Korover, T. Kolar, A. Schmidt, A. Somov, H. Szumila-Vance, D. Androić, C. Ayerbe Gayoso, X. Bai, V. V. Berdnikov, S. Bhattarai, Z. Chen, E. O. Cohen, O. Cortes Becerra, K. Dehmelt, A. Deur, B. R. Devkota, L. Ehinger, L. El Fassi, S. Fang, P. Gautam, J. -O. Hansen , et al. (62 additional authors not shown)

Abstract: The nuclear EMC effect is the observation that quark distributions in bound nucleons experience significant modification at large $x$ relative to free nucleons. Despite decades of measurements verifying the presence of this effect in quarks across a wide range of nuclei, behavior of large-$x$ gluons in nuclei remains almost completely unknown. As the nuclear physics community seeks out new observa… ▽ More The nuclear EMC effect is the observation that quark distributions in bound nucleons experience significant modification at large $x$ relative to free nucleons. Despite decades of measurements verifying the presence of this effect in quarks across a wide range of nuclei, behavior of large-$x$ gluons in nuclei remains almost completely unknown. As the nuclear physics community seeks out new observables to try to elucidate the mechanisms behind the EMC effect, it becomes striking that we remain ignorant regarding the impact of nuclear effects on gluonic behavior. Recent photonuclear data using the Hall D photon beam have enabled the first measurement of $J/ψ$ photoproduction from nuclei near and below the energy threshold, with the results highlighted in Physical Review Letters as an Editors' Suggestion. These data have placed the first, and currently only, constraints on the behavior of large-$x$ gluons within bound nucleons. However, compared to the quantity of data which currently informs our knowledge of the quark-sector EMC effect, these data are extremely limited, and remain unable to conclusively observe or exclude large modification of gluon distributions. A high-luminosity photonuclear experiment will enable a precision measurement of incoherent $J/ψ$ photoproduction at and below the threshold region. This data will provide the first stringent constraints on nuclear modification of gluon structure or other exotic effects which could impact the production of $J/ψ$ from nuclei. We request 85 PAC days at Hall D using the GlueX detector with a 12 GeV electron beam energy and a coherent photon peak energy of $8$ GeV, split into 80 days using a $^4$He target and 5 calibration days using a $^2$H target. △ Less

Submitted 24 October, 2025; originally announced October 2025.

Comments: 26 pages, 12 figures, porposal for Jefferson Lab Experiment E12-25-002, submitted to Jefferson Lab PAC 53 (2025)

Boron Nitride Coatings for the Enhanced Detection of Neutrons in CR-39

Authors: Noah DAmico, Sandeep Puri, Ian Jones, Andrew Gillespie, Cuikun Lin, Bo Zhao, R. V. Duncan

Abstract: The neutron detection efficiency of Columbia Resin 39 (CR-39) nuclear track detectors was assessed for AmBe, 252Cf, and D-T (14 MeV) neutron source spectra. A boron nitride (BN) coating for CR-39 was developed to enhance the neutron detection efficiency by converting neutrons into energetic alpha particles through the well-known 10B(n,a)7Li reaction. Separate partially coated CR-39 pieces were exp… ▽ More The neutron detection efficiency of Columbia Resin 39 (CR-39) nuclear track detectors was assessed for AmBe, 252Cf, and D-T (14 MeV) neutron source spectra. A boron nitride (BN) coating for CR-39 was developed to enhance the neutron detection efficiency by converting neutrons into energetic alpha particles through the well-known 10B(n,a)7Li reaction. Separate partially coated CR-39 pieces were exposed to each neutron source and subsequently analyzed under optical microscope and through large-area Scanning Electron Microscopy (SEM) imaging over the irradiated area. The detection efficiency (tracks per neutron) was evaluated for each source spectra under optical and scanning electron microscopes and with or without BN coating. This resulted in a comprehensive guide to neutron detection with various sources using CR-39. △ Less

Submitted 23 October, 2025; originally announced October 2025.

Comments: 16 pages, 7 figures

Enhanced Tritium Production in Irradiated TiD2 from Collisional Fusion in the Solid-State

Authors: Andrew K. Gillespie, Cuikun Lin, Ian Jones, Brad Jeffries, Joseph Caleb Philipps, Sandeep Puri, John Gahl, John Brockman, R. V. Duncan

Abstract: Ongoing research in new nuclear mechanisms hold the potential for beneficial developments in nuclear power cycle designs. Recent reports investigated the possibility of lattice dynamics to influence nuclear processes in metals. Results from Steinetz et al., at the NASA Glenn Research Center indicated that it may be feasible to initiate deuterium deuterium fusion reactions that are enhanced using e… ▽ More Ongoing research in new nuclear mechanisms hold the potential for beneficial developments in nuclear power cycle designs. Recent reports investigated the possibility of lattice dynamics to influence nuclear processes in metals. Results from Steinetz et al., at the NASA Glenn Research Center indicated that it may be feasible to initiate deuterium deuterium fusion reactions that are enhanced using electron screening to reduce the deuterium deuterium fusion barrier. This article presents tritium production results from both simulations and experiments targeting specific nuclear processes in an effort to identify the source of higher energy neutrons observed in those results. We explore two pathways of tritium generation in TiD2 through this fusion cycle. Tritium production from TiD2 in the University of Missouri Research Reactor, where the neutron spectrum was approximately 90 percent thermal, was within 25 percent of the predicted amount from simulations, and well explained by known nuclear reactions without invoking screening enhanced recoil-induced fusion. Tritium production from TiD2 in the cyclotron vault at MURR, where the neutron spectrum was completely energetic with almost no thermal neutrons, was a factor of 2.9 to 5.1 times higher than predicted from simulations using known nuclear reactions. This indicates the likelihood of an additional mechanism, such as collision-induced fusion in the solid state, increasing the credibility in the results from Steinetz et al. △ Less

Submitted 25 August, 2025; originally announced August 2025.

Comments: 18 pages, 8 figures, 2 tables

Measurement of transverse $Λ$ and $\barΛ$ hyperon polarization in $p$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An , et al. (1128 additional authors not shown)

Abstract: The transverse polarization of $Λ$ and $\barΛ$ hyperons is measured in $p$Pb collisions collected by the LHCb experiment at a nucleon-nucleon center-of-mass energy of $5.02$ TeV. The polarization is averaged over hyperon transverse momentum in the ranges $0.15 < p_{T} < 6.00 $ GeV/$c$, and Feynman-$x$ in the ranges $0.005 < x_{F} < 0.040$ (forward region) and $-0.10 < x_{F} < -0.01$ (backward regi… ▽ More The transverse polarization of $Λ$ and $\barΛ$ hyperons is measured in $p$Pb collisions collected by the LHCb experiment at a nucleon-nucleon center-of-mass energy of $5.02$ TeV. The polarization is averaged over hyperon transverse momentum in the ranges $0.15 < p_{T} < 6.00 $ GeV/$c$, and Feynman-$x$ in the ranges $0.005 < x_{F} < 0.040$ (forward region) and $-0.10 < x_{F} < -0.01$ (backward region) defined relative to the proton beam direction. The transverse polarization is found to be compatible with zero for both $Λ$ and $\barΛ$ hyperons. The results are also measured as a function of $p_{T}$ and $x_{F}$ with no significant dependence on these variables observed. The results are compared with previous experimental measurements at different center-of-mass energies and collision environments. △ Less

Submitted 5 January, 2026; v1 submitted 3 August, 2025; originally announced August 2025.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3242 (LHCb public pages)

Report number: LHCb-PAPER-2025-004, CERN-EP-2025-153

Journal ref: Phys. Rev. D112 (2025) 112022

Measurement of $ψ(2S)$ to $J/ψ$ cross-section ratio as function of multiplicity in $p$Pb collisions at$\sqrt{s_{NN}} = 8.16$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An , et al. (1137 additional authors not shown)

Abstract: The production ratio of $ψ(2S)$ to $J/ψ$ charmonium states is presented as a function of multiplicity in proton-lead collisions at a centre-of-mass energy of $\sqrt{s_{NN}}=8.16$ TeV, for both prompt and nonprompt sources. The total luminosity recorded by the LHCb experiment corresponds to 13.6 $pb^{-1}$ for $p$Pb collisions and 20.8 $pb^{-1}$ for Pb$p$ collisions, where the first particle indicat… ▽ More The production ratio of $ψ(2S)$ to $J/ψ$ charmonium states is presented as a function of multiplicity in proton-lead collisions at a centre-of-mass energy of $\sqrt{s_{NN}}=8.16$ TeV, for both prompt and nonprompt sources. The total luminosity recorded by the LHCb experiment corresponds to 13.6 $pb^{-1}$ for $p$Pb collisions and 20.8 $pb^{-1}$ for Pb$p$ collisions, where the first particle indicates the forward direction of the detector. Measurements are performed in the dimuon final state at forward (backward) centre-of-mass rapidity $1.5<y^*<4.0$ ($-5.0<y^*<-2.5$) for $p$Pb (Pb$p$) collisions.A multiplicity dependence of the prompt production ratio is observed in $p$Pb collisions, whereas no dependence is found in nonprompt production, nor in either prompt or nonprompt production in Pb$p$ collisions. These results suggest that in the Pb-going direction additional suppression mechanisms beyond comover effects may be present, possibly related to the formation of quark-gluon plasma. This highlights a transition from small to large collision systems and provides important insight into the suppression of charmonia in proton-nucleus collisions. △ Less

Submitted 17 February, 2026; v1 submitted 10 June, 2025; originally announced June 2025.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/4177/ (LHCb public pages)

Report number: LHCb-PAPER-2025-011, CERN-EP-2025-114

Journal ref: JHEP11(2025)169

Coherent photoproduction of $ρ^0, ω$ and excited vector mesons in ultraperipheral PbPb collisions

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An , et al. (1127 additional authors not shown)

Abstract: The invariant-mass distribution for the coherent photoproduction of dipions in ultraperipheral PbPb collisions is measured using data, corresponding to an integrated luminosity of $224.6 \pm 9.6 μ$b$^{-1}$, collected by the LHCb experiment in 2018 at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\rm NN}}=5.02$ TeV. In the mass range from 400 to 1200 MeV, the results are consistent with previou… ▽ More The invariant-mass distribution for the coherent photoproduction of dipions in ultraperipheral PbPb collisions is measured using data, corresponding to an integrated luminosity of $224.6 \pm 9.6 μ$b$^{-1}$, collected by the LHCb experiment in 2018 at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\rm NN}}=5.02$ TeV. In the mass range from 400 to 1200 MeV, the results are consistent with previous experiments, with the spectrum dominated by the $ρ^0$ meson, which interferes with a nonresonant component, together with a smaller $ω$ meson contribution. In an extended mass range up to 2300 MeV, models previously used do not fit the data and a consistent description requires the introduction of two resonances at masses of $1350\pm20$ MeV and $1790\pm20$ MeV with widths of about 300 MeV. The cross-section for each meson is measured differentially in twelve bins of rapidity from 2.05 to 4.90. The $ρ^0$ cross-section increases with rapidity from about 400 to 600 mb and is measured with a typical precision of 8\%, while the cross-section times branching fraction for the $ω,ρ^\prime$ and $ρ^{\prime\prime}$, with the statistical precision of the data, do not have a pronounced rapidity dependence and are between 0.5 and 1.5 mb, with uncertainties up to 30\%. A large nuclear suppression is observed for the $ρ^0$ meson compared to expectations based on photoproduction on the proton that use the impulse approximation. Significant suppression is also observed compared to that predicted by elastic scattering described in the Glauber approach, or with the addition of inelastic scattering in a Gribov--Glauber model. △ Less

Submitted 31 December, 2025; v1 submitted 6 June, 2025; originally announced June 2025.

Comments: 31 pages, 7 figures, as published in JHEP 11 (2025) 103. All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3795 (LHCb public pages)

Report number: CERN-EP-2025-106, LHCb-PAPER-2024-042

Journal ref: JHEP 11 (2025) 103

First measurement of $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ cross sections via $Σ^+$-nucleus scattering at an electron-positron collider

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai , et al. (680 additional authors not shown)

Abstract: Using $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the reactions $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ are studied, where the $Σ^{+}$ baryon is produced in the process $J/ψ\rightarrowΣ^{+}\barΣ^-$ and the neutron is a component of the $^9\rm{Be}$, $^{12}\rm{C}$ and $^{197}\rm{Au}$ nuclei in the beam pipe. Clear signals o… ▽ More Using $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the reactions $Σ^{+}n\rightarrowΛp$ and $Σ^{+}n\rightarrowΣ^{0}p$ are studied, where the $Σ^{+}$ baryon is produced in the process $J/ψ\rightarrowΣ^{+}\barΣ^-$ and the neutron is a component of the $^9\rm{Be}$, $^{12}\rm{C}$ and $^{197}\rm{Au}$ nuclei in the beam pipe. Clear signals of these two reactions are observed for the first time. Their cross sections are measured to be $σ(Σ^{+}+{^9\rm{Be}}\rightarrowΛ+p+X)=(45.2\pm12.1_{\rm{stat}}\pm7.2_{\rm{sys}})$ mb and $σ(Σ^{+}+{^9\rm{Be}}\rightarrowΣ^{0}+p+X)=(29.8\pm9.7_{\rm{stat}}\pm6.9_{\rm{sys}})$ mb for a $Σ^{+}$ average momentum of $0.992$ GeV/$c$, within a range of $\pm0.015$ GeV/$c$, where $X$ represents the residual nucleus. This is the first study of $Σ^{+}$-nucleon scattering at an electron-positron collider. △ Less

Submitted 24 March, 2026; v1 submitted 26 May, 2025; originally announced May 2025.

Comments: 9 pages, 2 figures

Journal ref: Physical Review C 113, L032201 (2026)

Rapidity and multiplicity dependence of charged-particle flow in $p$Pb collisions at $\sqrt{s_{NN}} = 8.16$ TeV

Authors: R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis, L. An, L. Anderlini , et al. (1126 additional authors not shown)

Abstract: The elliptic and triangular flow of charged particles are measured using two-particle angular correlations in $p$Pb collisions in the pseudorapidity range \cal{2.0 $< |η| <$ 4.8}. The data sample was collected by the LHCb experiment in 2016 at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}} = 8.16$ TeV, containing in total approximately 1.5 billion collision events. Non-flow contributio… ▽ More The elliptic and triangular flow of charged particles are measured using two-particle angular correlations in $p$Pb collisions in the pseudorapidity range \cal{2.0 $< |η| <$ 4.8}. The data sample was collected by the LHCb experiment in 2016 at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}} = 8.16$ TeV, containing in total approximately 1.5 billion collision events. Non-flow contributions are obtained in low-multiplicity collisions and subtracted to extract the flow harmonics. The results are presented as a function of event multiplicity and hadron transverse momentum. Comparisons with a full (3+1)D dynamic model indicate that it overestimates the measured elliptic flow. A comparison between the forward and backward regions reveals no significant differences in flow parameters, suggesting that final-state effects may dominate over initial-state effects in the origin of flow in small systems. △ Less

Submitted 30 October, 2025; v1 submitted 14 May, 2025; originally announced May 2025.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3799 (LHCb public pages)

Report number: CERN-EP-2025-090, LHCb-PAPER-2025-003

Journal ref: JHEP 10 (2025) 124

Nuclear Physics at BRIF

Authors: Wei Nan, Bing Guo, Jie Chen, Baoqun Cui, Wei Fu, Xianlu Jia, Chaoxin Kan, Jiayinghao Li, Yunju Li, Chengjian Lin, Yihui Liu, Nanru Ma, Zhaohua Peng, Yangping Shen, Guofang Song, Jun Su, Bing Tang, Haorui Wang, Youbao Wang, Lei Yang, Xiaofei Yang, Zhiguo Yin, Yun Zheng, Tianjue Zhang, Weiping Liu

Abstract: The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60… ▽ More The Beijing Radioactive Ion-beam Facility (BRIF), which is based on Isotope Separation On-Line (ISOL) technique, consists of a 100 MeV proton cyclotron as the driving accelerator, a two-stage ISOL system for ion separation, a 13-MV tandem accelerator for post-acceleration, a superconducting linac for further boosting beam energies. It is capable of providing ISOL beams in the energy range from 60 to 300 keV, and post-accelerated beams in the energy range from 3 to 10 MeV/u for nuclei with mass numbers of A < 80 by Isotope Separation On-Line (ISOL) technique. For nuclei with A up to 170, energies are still able to reach 3 MeV/u. This facility offers opportunities to address key questions of current interest in nuclear astrophysics, nuclear structure and reactions of unstable nuclei. In this review we present a comprehensive introduction to the BRIF and the typical experimental instruments installed on it, and then summarize current experimental results on unstable Na and Rb isotopes and future plan for further development of the BRIF to improve its performance. △ Less

Submitted 27 June, 2025; v1 submitted 16 March, 2025; originally announced March 2025.

Comments: 82 pages, 77 figures

Measurement of the multiplicity dependence of $\mitΥ$ production ratios in $pp$ collisions at $\sqrt{s}=13$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1127 additional authors not shown)

Abstract: The $\mitΥ(\mathrm{2}S)$ and $\mitΥ(\mathrm{3}S)$ production cross-sections are measured relative to that of the $\mitΥ(\mathrm{1}S)$ meson, as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy of $13$ TeV. The measurement uses data collected by the LHCb experiment in 2018 corresponding to an integrated luminosity of 2 $\text{fb}^{-1}$. Both the… ▽ More The $\mitΥ(\mathrm{2}S)$ and $\mitΥ(\mathrm{3}S)$ production cross-sections are measured relative to that of the $\mitΥ(\mathrm{1}S)$ meson, as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy of $13$ TeV. The measurement uses data collected by the LHCb experiment in 2018 corresponding to an integrated luminosity of 2 $\text{fb}^{-1}$. Both the $\mitΥ(\mathrm{2}S)$-to-$\mitΥ(\mathrm{1}S)$ and $\mitΥ(\mathrm{3}S)$-to-$\mitΥ(\mathrm{1}S)$ cross-section ratios are found to decrease significantly as a function of event multiplicity, with the $\mitΥ(\mathrm{3}S)$-to-$\mitΥ(\mathrm{1}S)$ ratio showing a steeper decline towards high multiplicity. This hierarchy is qualitatively consistent with the comover model predictions, indicating that final-state interactions play an important role in bottomonia production in high-multiplicity events. △ Less

Submitted 16 May, 2025; v1 submitted 21 January, 2025; originally announced January 2025.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/1782/ (LHCb public pages)

Report number: LHCb-PAPER-2024-038, CERN-EP-2024-318

Journal ref: JHEP 05 (2025) 011

Comprehensive Measurement of the Reactor Antineutrino Spectrum and Flux at Daya Bay

Authors: F. P. An, W. D. Bai, A. B. Balantekin, M. Bishai, S. Blyth, G. F. Cao, J. Cao, J. F. Chang, Y. Chang, H. S. Chen, H. Y. Chen, S. M. Chen, Y. Chen, Y. X. Chen, Z. Y. Chen, J. Cheng, J. Cheng, Y. -C. Cheng, Z. K. Cheng, J. J. Cherwinka, M. C. Chu, J. P. Cummings, O. Dalager, F. S. Deng, X. Y. Ding , et al. (177 additional authors not shown)

Abstract: This Letter reports the precise measurement of reactor antineutrino spectrum and flux based on the full data set of 4.7 million inverse-beta-decay (IBD) candidates collected at Daya Bay near detectors. Expressed in terms of the IBD yield per fission, the antineutrino spectra from all reactor fissile isotopes and the specific $\mathrm{^{235}U}$ and $\mathrm{^{239}Pu}$ isotopes are measured with 1.3… ▽ More This Letter reports the precise measurement of reactor antineutrino spectrum and flux based on the full data set of 4.7 million inverse-beta-decay (IBD) candidates collected at Daya Bay near detectors. Expressed in terms of the IBD yield per fission, the antineutrino spectra from all reactor fissile isotopes and the specific $\mathrm{^{235}U}$ and $\mathrm{^{239}Pu}$ isotopes are measured with 1.3$\%$, 3$\%$ and 8$\%$ uncertainties respectively near the 3 MeV spectrum peak in reconstructed energy, reaching the best precision in the world. The total antineutrino flux and isotopic $\mathrm{^{235}U}$ and $\mathrm{^{239}Pu}$ fluxes are precisely measured to be $5.84\pm0.07$, $6.16\pm0.12$ and $4.16\pm0.21$ in units of $10^{-43} \mathrm{cm^2/fission}$. These measurements are compared with the Huber-Mueller (HM) model, the reevaluated conversion model based on the Kurchatov Institute (KI) measurement and the latest Summation Model (SM2023). The Daya Bay flux shows good consistency with KI and SM2023 models, but disagrees with HM model. The Daya Bay spectrum, however, disagrees with all model predictions. △ Less

Submitted 22 May, 2025; v1 submitted 1 January, 2025; originally announced January 2025.

Measurement of $φ(1020)$ meson production in fixed-target $\textit{p}$Ne collisions at $\sqrt{s_{NN}}$ = 68.5 GeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1127 additional authors not shown)

Abstract: The first measurement of $φ(1020)$ meson production in fixed-target $p$Ne collisions at $\sqrt{s_{NN}}=68.5$ GeV is presented. The $φ(1020)$ mesons are reconstructed in their $K^{+}K^{-}$ decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of $21.7 \pm 1.4$ nb$^{-1}$, collected by the LHCb detector at CERN. The $φ(1020)$ producti… ▽ More The first measurement of $φ(1020)$ meson production in fixed-target $p$Ne collisions at $\sqrt{s_{NN}}=68.5$ GeV is presented. The $φ(1020)$ mesons are reconstructed in their $K^{+}K^{-}$ decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of $21.7 \pm 1.4$ nb$^{-1}$, collected by the LHCb detector at CERN. The $φ(1020)$ production cross-section in the centre-of-mass rapidity range of $-1.8<y^*<0$ and transverse momentum range of $800<p_{T}<6500$ MeV/c is found to be $σ=182.7\pm2.7~\text{(stat.)}\pm14.1~\text{(syst)}~μ$b/nucleon. A double-differential measurement of the cross-section is also provided in four regions of rapidity and six regions of transverse momentum of the $φ(1020)$ meson and compared with the predictions from Pythia and EPOS4, which are found to underestimate the experimental values. △ Less

Submitted 24 March, 2025; v1 submitted 14 November, 2024; originally announced November 2024.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3673 (LHCb public pages)

Report number: LHCb-PAPER-2024-036, CERN-EP-2024-274

Journal ref: JHEP 03 (2025) 151

Measurement of the $ψ(2S)$ to $J/ψ$ cross-section ratio as a function of centrality in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, A. A. Adefisoye, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1128 additional authors not shown)

Abstract: The dissociation of quarkonium states with different binding energies produced in heavy-ion collisions is a powerful probe for investigating the formation and properties of the quark-gluon plasma. The ratio of production cross-sections of $ψ(2S)$ and $J/ψ$ mesons times the ratio of their branching fractions into the dimuon final state is measured as a function of centrality using data collected by… ▽ More The dissociation of quarkonium states with different binding energies produced in heavy-ion collisions is a powerful probe for investigating the formation and properties of the quark-gluon plasma. The ratio of production cross-sections of $ψ(2S)$ and $J/ψ$ mesons times the ratio of their branching fractions into the dimuon final state is measured as a function of centrality using data collected by the LHCb detector in PbPb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV. The measured ratio shows no dependence on the collision centrality, and is compared to the latest theory predictions and to the recent measurements in literature. △ Less

Submitted 13 November, 2025; v1 submitted 8 November, 2024; originally announced November 2024.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://lbfence.cern.ch/alcm/public/analysis/full-details/3695 (LHCb public pages)

Report number: CERN-EP-2024-272, LHCb-PAPER-2024-041

Journal ref: JHEP07(2025)235

Observation of a rare beta decay of the charmed baryon with a Graph Neural Network

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere , et al. (637 additional authors not shown)

Abstract: The beta decay of the lightest charmed baryon $Λ_c^+$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay… ▽ More The beta decay of the lightest charmed baryon $Λ_c^+$ provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay $Λ_c^+ \rightarrow n e^+ ν_{e}$, utilizing $4.5~\mathrm{fb}^{-1}$ of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably $Λ_c^+ \rightarrow Λe^+ ν_{e}$, achieving a statistical significance exceeding $10σ$. The absolute branching fraction is measured to be $(3.57\pm0.34_{\mathrm{stat.}}\pm0.14_{\mathrm{syst.}})\times 10^{-3}$. For the first time, the CKM matrix element $\left|V_{cd}\right|$ is extracted via a charmed baryon decay as $0.208\pm0.011_{\rm exp.}\pm0.007_{\rm LQCD}\pm0.001_{τ_{Λ_c^+}}$. This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power of modern machine learning techniques in experimental high-energy physics. △ Less

Submitted 15 January, 2025; v1 submitted 17 October, 2024; originally announced October 2024.

Comments: 27 pages, 5 figures

Journal ref: Nature Commun. 16, 681 (2025)

Supernova Pointing Capabilities of DUNE

Authors: DUNE Collaboration, A. Abed Abud, B. Abi, R. Acciarri, M. A. Acero, M. R. Adames, G. Adamov, M. Adamowski, D. Adams, M. Adinolfi, C. Adriano, A. Aduszkiewicz, J. Aguilar, B. Aimard, F. Akbar, K. Allison, S. Alonso Monsalve, M. Alrashed, A. Alton, R. Alvarez, T. Alves, H. Amar, P. Amedo, J. Anderson, D. A. Andrade , et al. (1340 additional authors not shown)

Abstract: The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electr… ▽ More The determination of the direction of a stellar core collapse via its neutrino emission is crucial for the identification of the progenitor for a multimessenger follow-up. A highly effective method of reconstructing supernova directions within the Deep Underground Neutrino Experiment (DUNE) is introduced. The supernova neutrino pointing resolution is studied by simulating and reconstructing electron-neutrino charged-current absorption on 40Ar and elastic scattering of neutrinos on electrons. Procedures to reconstruct individual interactions, including a newly developed technique called ``brems flipping'', as well as the burst direction from an ensemble of interactions are described. Performance of the burst direction reconstruction is evaluated for supernovae happening at a distance of 10 kpc for a specific supernova burst flux model. The pointing resolution is found to be 3.4 degrees at 68% coverage for a perfect interaction-channel classification and a fiducial mass of 40 kton, and 6.6 degrees for a 10 kton fiducial mass respectively. Assuming a 4% rate of charged-current interactions being misidentified as elastic scattering, DUNE's burst pointing resolution is found to be 4.3 degrees (8.7 degrees) at 68% coverage. △ Less

Submitted 24 December, 2025; v1 submitted 14 July, 2024; originally announced July 2024.

Comments: 26 pages, 17 figures

Report number: FERMILAB-PUB-24-0319-LBNF

Journal ref: Phys. Rev. D 111, 092006 (Published 12 May, 2025)

Ultra-short lifetime isomer studies from photonuclear reactions using laser-driven ultra-intense γ-ray

Authors: Di Wu, Haoyang Lan, Jiaxing Liu, Huangang Lu, Jianyao Zhang, Jianfeng Lv, Xuezhi Wu, Hui Zhang, Yadong Xia, Qiangyou He, Jie Cai, Qianyi Ma, Yuhui Xia, Zhenan Wang, Meizhi Wang, Zhiyan Yang, Xinlu Xu, Yixing Geng, Chen Lin, Wenjun Ma, Yanying Zhao, Haoran Wang, Fulong Liu, Chuangye He, Jinqing Yu , et al. (7 additional authors not shown)

Abstract: Isomers, ubiquitous populations of relatively long-lived nuclear excited states, play a crucial role in nuclear physics. However, isomers with half-life times of several seconds or less barely had experimental cross section data due to the lack of a suitable measuring method. We report a method of online γ spectroscopy for ultra-short-lived isomers from photonuclear reactions using laser-driven ul… ▽ More Isomers, ubiquitous populations of relatively long-lived nuclear excited states, play a crucial role in nuclear physics. However, isomers with half-life times of several seconds or less barely had experimental cross section data due to the lack of a suitable measuring method. We report a method of online γ spectroscopy for ultra-short-lived isomers from photonuclear reactions using laser-driven ultra-intense γ-rays. The fastest time resolution can reach sub-ps level with γ-ray intensities >10^{19}/s ({\geqslant} 8 MeV). The ^{115}In(γ, n)^{114m2}In reaction (T_{1/2} = 43.1 ms) was first measured in the high-energy region which shed light on the nuclear structure studies of In element. Simulations showed it would be an efficient way to study ^{229m}Th (T_{1/2} = 7 μs), which is believed to be the next generation of nuclear clock. This work offered a unique way of gaining insight into ultra-short lifetimes and promised an effective way to fill the gap in relevant experimental data. △ Less

Submitted 23 February, 2024; originally announced February 2024.

Modification of $χ_{c1}$(3872) and $ψ$(2$S$) production in $p$Pb collisions at $\sqrt{s_{NN}} = 8.16$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1082 additional authors not shown)

Abstract: The LHCb collaboration measures production of the exotic hadron $χ_{c1}$(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state $ψ$(2$S$) suggests that the exotic $χ_{c1}$(3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may mod… ▽ More The LHCb collaboration measures production of the exotic hadron $χ_{c1}$(3872) in proton-nucleus collisions for the first time. Comparison with the charmonium state $ψ$(2$S$) suggests that the exotic $χ_{c1}$(3872) experiences different dynamics in the nuclear medium than conventional hadrons, and comparison with data from proton-proton collisions indicates that the presence of the nucleus may modify $χ_{c1}$(3872) production rates. This is the first measurement of the nuclear modification factor of an exotic hadron. △ Less

Submitted 19 June, 2024; v1 submitted 22 February, 2024; originally announced February 2024.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-026.html (LHCb public pages)

Report number: LHCb-PAPER-2023-026, CERN-EP-2024-033

Journal ref: Phys. Rev. Lett. 132 (2024) 242301

First measurement of the yield of $^8$He isotopes produced in liquid scintillator by cosmic-ray muons at Daya Bay

Authors: Daya Bay Collaboration, F. P. An, W. D. Bai, A. B. Balantekin, M. Bishai, S. Blyth, G. F. Cao, J. Cao, J. F. Chang, Y. Chang, H. S. Chen, H. Y. Chen, S. M. Chen, Y. Chen, Y. X. Chen, Z. Y. Chen, J. Cheng, Y. C. Cheng, Z. K. Cheng, J. J. Cherwinka, M. C. Chu, J. P. Cummings, O. Dalager, F. S. Deng, X. Y. Ding , et al. (177 additional authors not shown)

Abstract: Daya Bay presents the first measurement of cosmogenic $^8$He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of $^8$He and its child isotope, $^8$Li. We also measure the production yield of $^9$Li isotopes using well-established methodology. The results, in units of 10$^{-8}μ^{-1}$g$^{-1}$cm$^{2}$, are 0.307$\pm$0.042, 0.341$\pm$0.040, and 0.546… ▽ More Daya Bay presents the first measurement of cosmogenic $^8$He isotope production in liquid scintillator, using an innovative method for identifying cascade decays of $^8$He and its child isotope, $^8$Li. We also measure the production yield of $^9$Li isotopes using well-established methodology. The results, in units of 10$^{-8}μ^{-1}$g$^{-1}$cm$^{2}$, are 0.307$\pm$0.042, 0.341$\pm$0.040, and 0.546$\pm$0.076 for $^8$He, and 6.73$\pm$0.73, 6.75$\pm$0.70, and 13.74$\pm$0.82 for $^9$Li at average muon energies of 63.9~GeV, 64.7~GeV, and 143.0~GeV, respectively. The measured production rate of $^8$He isotopes is more than an order of magnitude lower than any other measurement of cosmogenic isotope production. It replaces the results of previous attempts to determine the ratio of $^8$He to $^9$Li production that yielded a wide range of limits from 0 to 30\%. The results provide future liquid-scintillator-based experiments with improved ability to predict cosmogenic backgrounds. △ Less

Submitted 7 February, 2024; originally announced February 2024.

Prompt and nonprompt $ψ(2S)$ production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey , et al. (1079 additional authors not shown)

Abstract: The production of $ψ(2S)$ mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}}=8.16$ TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb$^{-1}$. The prompt and nonprompt $ψ(2S)$ production cross-sections and the ratio of the $ψ(2S)$ to $J/ψ$ cross-section are measured as a function of the meson transverse mom… ▽ More The production of $ψ(2S)$ mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}}=8.16$ TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb$^{-1}$. The prompt and nonprompt $ψ(2S)$ production cross-sections and the ratio of the $ψ(2S)$ to $J/ψ$ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt $ψ(2S)$ is observed to be more suppressed compared to $pp$ collisions than the prompt $J/ψ$ production, while the nonprompt productions have similar suppression factors. △ Less

Submitted 22 April, 2024; v1 submitted 20 January, 2024; originally announced January 2024.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-024.html (LHCb public pages)

Report number: LHCb-PAPER-2023-024, CERN-EP-2023-293

Journal ref: JHEP 04 (2024) 111

First study of antihyperon-nucleon scattering $\barΛp\rightarrow\barΛp$ and measurement of $Λp\rightarrowΛp$ cross section

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, O. Afedulidis, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, I. Balossino, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere , et al. (634 additional authors not shown)

Abstract: Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cr… ▽ More Using $(10.087\pm0.044)\times10^{9}$ $J/ψ$ events collected with the BESIII detector at the BEPCII storage ring, the processes $Λp\rightarrowΛp$ and $\barΛp\rightarrow\barΛp$ are studied, where the $Λ/\barΛ$ baryons are produced in the process $J/ψ\rightarrowΛ\barΛ$ and the protons are the hydrogen nuclei in the cooling oil of the beam pipe. Clear signals are observed for the two reactions. The cross sections in $-0.9\leq\rm{cos}θ_{Λ/\barΛ}\leq0.9$ are measured to be $σ(Λp\rightarrowΛp)=(12.2\pm1.6_{\rm{stat}}\pm1.1_{\rm{sys}})$ mb and $σ(\barΛ p\rightarrow\barΛ p)=(17.5\pm2.1_{\rm{stat}}\pm1.6_{\rm{sys}})$ mb at the $Λ/\barΛ$ momentum of $1.074$ GeV/$c$ within a range of $\pm0.017$ GeV/$c$, where the $θ_{Λ/\barΛ}$ are the scattering angles of the $Λ/\barΛ$ in the $Λp/\barΛp$ rest frames. Furthermore, the differential cross sections of the two reactions are also measured, where there is a slight tendency of forward scattering for $Λp\rightarrowΛp$, and a strong forward peak for $\barΛp\rightarrow\barΛp$. We present an approach to extract the total elastic cross sections by extrapolation. The study of $\barΛp\rightarrow\barΛp$ represents the first study of antihyperon-nucleon scattering, and these new measurements will serve as important inputs for the theoretical understanding of the (anti)hyperon-nucleon interaction. △ Less

Submitted 18 May, 2024; v1 submitted 17 January, 2024; originally announced January 2024.

Comments: 9 pages, 5 figures

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV with the LHCb detector

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1079 additional authors not shown)

Abstract: Flow harmonic coefficients, $v_n$, which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosit… ▽ More Flow harmonic coefficients, $v_n$, which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of $5.02$ TeV. The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features. △ Less

Submitted 16 May, 2024; v1 submitted 16 November, 2023; originally announced November 2023.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-031.html (LHCb public pages)

Report number: LHCb-PAPER-2023-031, CERN-EP-2023-240

Journal ref: Phys. Rev. C 109 (2024) 054908

Observation of strangeness enhancement with charmed mesons in high-multiplicity $p\mathrm{Pb}$ collisions at $\sqrt {s_{\mathrm{NN}}}=8.16\,$TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey , et al. (1085 additional authors not shown)

Abstract: The production of prompt $D^+_{s}$ and $D^+$ mesons is measured by the LHCb experiment in proton-lead ($p\mathrm{Pb}$) collisions in both the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions at a nucleon-nucleon center-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=8.16\,$TeV. The nuclear modification factors of both $D^+_{s}$ and $D^+$ mesons are determined as a function of tra… ▽ More The production of prompt $D^+_{s}$ and $D^+$ mesons is measured by the LHCb experiment in proton-lead ($p\mathrm{Pb}$) collisions in both the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions at a nucleon-nucleon center-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=8.16\,$TeV. The nuclear modification factors of both $D^+_{s}$ and $D^+$ mesons are determined as a function of transverse momentum, $p_{\mathrm{T}}$, and rapidity. In addition, the $D^+_{s}$ to $D^+$ cross-section ratio is measured as a function of the charged particle multiplicity in the event. An enhanced $D^+_{s}$ to $D^+$ production in high-multiplicity events is observed for the whole measured $p_{\mathrm{T}}$ range, in particular at low $p_{\mathrm{T}}$ and backward rapidity, where the significance exceeds six standard deviations. This constitutes the first observation of strangeness enhancement in charm quark hadronization in high-multiplicity $p\mathrm{Pb}$ collisions. The results are also qualitatively consistent with the presence of quark coalescence as an additional charm quark hadronization mechanism in high-multiplicity proton-lead collisions. △ Less

Submitted 4 September, 2024; v1 submitted 14 November, 2023; originally announced November 2023.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-021.html (LHCb public pages)

Report number: LHCb-PAPER-2023-021, CERN-EP-2023-236

Journal ref: Phys. Rev. D 110, L031105 (2024)

Fraction of $χ_c$ decays in prompt $J/ψ$ production measured in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1078 additional authors not shown)

Abstract: The fraction of $χ_{c1}$ and $χ_{c2}$ decays in the prompt $J/ψ$ yield, $F_{χc}=σ_{χ_c \to J/ψ}/σ_{J/ψ}$, is measured by the LHCb detector in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV. The study covers the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions, where $y^*$ is the $J/ψ$ rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples co… ▽ More The fraction of $χ_{c1}$ and $χ_{c2}$ decays in the prompt $J/ψ$ yield, $F_{χc}=σ_{χ_c \to J/ψ}/σ_{J/ψ}$, is measured by the LHCb detector in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV. The study covers the forward ($1.5<y^*<4.0$) and backward ($-5.0<y^*<-2.5$) rapidity regions, where $y^*$ is the $J/ψ$ rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples correspond to integrated luminosities of 13.6 $\pm$ 0.3 nb$^{-1}$ and 20.8 $\pm$ 0.5 nb$^{-1}$, respectively. The result is presented as a function of the $J/ψ$ transverse momentum $p_{T,J/ψ}$ in the range 1$<p_{T, J/ψ}<20$ GeV/$c$. The $F_{χc}$ fraction at forward rapidity is compatible with the LHCb measurement performed in $pp$ collisions at $\sqrt{s}=7$ TeV, whereas the result at backward rapidity is 2.4 $σ$ larger than in the forward region for $1<p_{T, J/ψ}<3$ GeV/$c$. The increase of $F_{χc}$ at low $p_{T, J/ψ}$ at backward rapidity is compatible with the suppression of the $ψ$(2S) contribution to the prompt $J/ψ$ yield. The lack of in-medium dissociation of $χ_c$ states observed in this study sets an upper limit of 180 MeV on the free energy available in these pPb collisions to dissociate or inhibit charmonium state formation. △ Less

Submitted 2 November, 2023; originally announced November 2023.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-028.html (LHCb public pages)

Report number: LHCb-PAPER-2023-028, CERN-EP-2023-224

Journal ref: Phys. Rev. Lett. 132 (2024) 102302

Production of $η$ and $η'$ mesons in $pp$ and $p$Pb collisions

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey, Y. Amhis , et al. (1080 additional authors not shown)

Abstract: The production of $η$ and $η'$ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of $5.02$ and $13~{\rm TeV}$, and proton-lead collisions are studied at a center-of-mass energy per nucleon of $8.16~{\rm TeV}$. The studies are performed in center-of-mass rapidity regions… ▽ More The production of $η$ and $η'$ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of $5.02$ and $13~{\rm TeV}$, and proton-lead collisions are studied at a center-of-mass energy per nucleon of $8.16~{\rm TeV}$. The studies are performed in center-of-mass rapidity regions $2.5<y_{\rm c.m.}<3.5$ (forward rapidity) and $-4.0<y_{\rm c.m.}<-3.0$ (backward rapidity) defined relative to the proton beam direction. The $η$ and $η'$ production cross sections are measured differentially as a function of transverse momentum for $1.5<p_{\rm T}<10~{\rm GeV}$ and $3<p_{\rm T}<10~{\rm GeV}$, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for $η$ and $η'$ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of $η$ mesons are also used to calculate $η/π^0$ cross section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as $η$ and $η'$ meson fragmentation. △ Less

Submitted 13 February, 2025; v1 submitted 26 October, 2023; originally announced October 2023.

Comments: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/Publications/p/LHCb-PAPER-2023-030.html (LHCb public pages)

Report number: LHCb-PAPER-2023-030, CERN-EP-2023-228

Journal ref: Phys. Rev. C109 (2024), 024907

Multi-alpha Boson Gas state in Fusion Evaporation Reaction and Three-body Force

Authors: Taofeng Wang, Ziming Li, R. B. Wiringa, Minliang Liu, Jiansong Wang, Yanyun Yang, Qinghua He, Zhiyu Sun, Chengjian Lin, M. Assié, Y. Ayyad, D. Beaumel, Zhen Bai, Fangfang Duan, Zhihao Gao, Song Guo, Yue Hu, Wei Jiang, F. Kobayashi, Chengui Lu, Junbing Ma, Peng Ma, P. Napolitani, G. Verde, Jianguo Wang , et al. (11 additional authors not shown)

Abstract: The experimental evidence for the $α$ Boson gas state in the $^{11}$C+$^{12}$C$\rightarrow$$^{23}$Mg$^{\ast}$ fusion evaporation reaction is presented. By measuring the $α$ emission spectrum with multiplicity 2 and 3, we provide insight into the existence of a three-body force among $α$ particles. The observed spectrum exhibited distinct tails corresponding to $α$ particles emitted in pairs and tr… ▽ More The experimental evidence for the $α$ Boson gas state in the $^{11}$C+$^{12}$C$\rightarrow$$^{23}$Mg$^{\ast}$ fusion evaporation reaction is presented. By measuring the $α$ emission spectrum with multiplicity 2 and 3, we provide insight into the existence of a three-body force among $α$ particles. The observed spectrum exhibited distinct tails corresponding to $α$ particles emitted in pairs and triplets consistent well with the model-calculations of AV18-UX and chiral effective field theory of NV2-3-la*, indicating the formation of $α$ clusters with three-body force in the Boson gas state. △ Less

Submitted 6 October, 2023; originally announced October 2023.

Comments: 7 pages, 6 figures

Aspect of Clusters Correlation at Light Nuclei Excited State

Authors: Ziming Li, Jie Zhu, Taofeng Wang, Minliang Liu, Jiansong Wang, Yanyun Yang, Chengjian Lin, Zhiyu Sun, Qinghua He, M. Assié, Y. Ayyad, D. Beaumel, Zhen Bai, Fangfang Duan, Zhihao Gao, Song Guo, Yue Hu, Wei Jiang, F. Kobayashi, Chengui Lu, Junbing Ma, Peng Ma, P. Napolitani, G. Verde, Jianguo Wang , et al. (11 additional authors not shown)

Abstract: The correlation of $αα$ was probed via measuring the transverse momentum $p_{T}$ and width $δp_{T}$ of one $α$, for the first time, which represents the spatial and dynamical essentialities of the initial coupling state in $^{8}$Be nucleus. The weighted interaction vertex of 3$α$ reflected by the magnitudes of their relative momentums and relative emission angles proves the isosceles triangle conf… ▽ More The correlation of $αα$ was probed via measuring the transverse momentum $p_{T}$ and width $δp_{T}$ of one $α$, for the first time, which represents the spatial and dynamical essentialities of the initial coupling state in $^{8}$Be nucleus. The weighted interaction vertex of 3$α$ reflected by the magnitudes of their relative momentums and relative emission angles proves the isosceles triangle configuration for 3$α$ at the high excited energy analogous Hoyle states. △ Less

Submitted 6 October, 2023; originally announced October 2023.

Comments: 8 pages, 9 figures

Variation of Tensor Force due to Nuclear Medium Effect

Authors: Ziming Li, Jie Zhu, Taofeng Wang, Minliang Liu, Jiansong Wang, Yanyun Yang, Chengjian Lin, Zhiyu Sun, Qinghua He, M. Assié, Y. Ayyad, D. Beaumel, Zhen Bai, Fangfang Duan, Zhihao Gao, Song Guo, Yue Hu, Wei Jiang, F. Kobayashi, Chengui Lu, Junbing Ma, Peng Ma, P. Napolitani, G. Verde, Jianguo Wang , et al. (11 additional authors not shown)

Abstract: The enhancement of $J^π(T)$=3$^{+}$(0) state with isospin $T=0$ excited by the tensor force in the free $^{6}$Li nucleus has been observed, for the first time, relative to a shrinkable excitation in the $^{6}$Li cluster component inside its host nucleus. Comparatively, the excitation of $J^π(T)$=0$^{+}$(1) state with isospin $T=1$ for these two $^{6}$Li formations take on an approximately equal ex… ▽ More The enhancement of $J^π(T)$=3$^{+}$(0) state with isospin $T=0$ excited by the tensor force in the free $^{6}$Li nucleus has been observed, for the first time, relative to a shrinkable excitation in the $^{6}$Li cluster component inside its host nucleus. Comparatively, the excitation of $J^π(T)$=0$^{+}$(1) state with isospin $T=1$ for these two $^{6}$Li formations take on an approximately equal excitation strength. The mechanism of such tensor force effect was proposed due to the intensive nuclear medium role on isospin $T$=0 state. △ Less

Submitted 6 October, 2023; originally announced October 2023.

Comments: 6 pages, 4 figures

Measurement of prompt $D^+$ and $D^+_{s}$ production in $p\mathrm{Pb}$ collisions at $\sqrt {s_{\mathrm{NN}}}=5.02\,$TeV

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey , et al. (1039 additional authors not shown)

Abstract: The production of prompt $D^+$ and $D^+_{s}$ mesons is studied in proton-lead collisions at a centre-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=5.02\,$TeV. The data sample corresponding to an integrated luminosity of $(1.58\pm0.02)\mathrm{nb}^{-1}$ is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using $D^+$ and $D^+_{s}$ candidates with trans… ▽ More The production of prompt $D^+$ and $D^+_{s}$ mesons is studied in proton-lead collisions at a centre-of-mass energy of $\sqrt {s_{\mathrm{NN}}}=5.02\,$TeV. The data sample corresponding to an integrated luminosity of $(1.58\pm0.02)\mathrm{nb}^{-1}$ is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using $D^+$ and $D^+_{s}$ candidates with transverse momentum in the range of $0<p_{\mathrm{T}} <14\,\mathrm{GeV}/c$ and rapidities in the ranges of $1.5<y^*<4.0$ and $-5.0<y^*<-2.5$ in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between $D^+$, $D^+_{s}$ and $D^0$ mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies. △ Less

Submitted 25 January, 2024; v1 submitted 25 September, 2023; originally announced September 2023.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-006.html (LHCb public pages). arXiv admin note: text overlap with arXiv:1707.02750

Report number: CERN-EP-2023-142, LHCb-PAPER-2023-006

Journal ref: JHEP 01 (2024) 070

Measurement of $Ξ_{c}^{+}$ production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV at LHCb

Authors: LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb, C. Abellan Beteta, F. Abudinén, T. Ackernley, B. Adeva, M. Adinolfi, P. Adlarson, H. Afsharnia, C. Agapopoulou, C. A. Aidala, Z. Ajaltouni, S. Akar, K. Akiba, P. Albicocco, J. Albrecht, F. Alessio, M. Alexander, A. Alfonso Albero, Z. Aliouche, P. Alvarez Cartelle, R. Amalric, S. Amato, J. L. Amey , et al. (1040 additional authors not shown)

Abstract: A study of prompt $Ξ_{c}^{+}$ production in proton-lead collisions is performed with the LHCb experiment at a centre-of-mass energy per nucleon pair of 8.16 TeV in 2016 in $p$Pb and Pb$p$ collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb$^{-1}$, respectively. The $Ξ_{c}^{+}$ production cross-section, as well as the $Ξ_{c}^{+}$ to $Λ_{c}^{+}$ production cross-sect… ▽ More A study of prompt $Ξ_{c}^{+}$ production in proton-lead collisions is performed with the LHCb experiment at a centre-of-mass energy per nucleon pair of 8.16 TeV in 2016 in $p$Pb and Pb$p$ collisions with an estimated integrated luminosity of approximately 12.5 and 17.4 nb$^{-1}$, respectively. The $Ξ_{c}^{+}$ production cross-section, as well as the $Ξ_{c}^{+}$ to $Λ_{c}^{+}$ production cross-section ratio, are measured as a function of the transverse momentum and rapidity and compared to latest theory predictions. The forward-backward asymmetry is also measured as a function of the $Ξ_{c}^{+}$ transverse momentum. △ Less

Submitted 23 September, 2024; v1 submitted 11 May, 2023; originally announced May 2023.

Comments: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-041.html (LHCb public pages)

Report number: LHCb-PAPER-2022-041, CERN-EP-2023-057

Journal ref: Physical Review C 109, 044901 (2024)

$α$-cluster decay from $^{24}$Mg resonances produced in $^{12}$C($^{16}$O,$^{24}$Mg)$α$ reaction

Authors: Dong-Xi Wang, Yan-Lin Ye, Cheng-Jian Lin, Jia-Hao Chen, Kai Ma, Jia-Xing Han, Hui-Ming Jia, Lei Yang, Li-Sheng Yang, Zi-Yao Hu, Ying Chen, Wei-Liang Pu, Gen Li, Zhi-Wei Tan, Hong-Yu Zhu, Tian-Peng Luo, Shan-Hao Zhong, Da-Hu Huang, Jian-Ling Lou, Xiao-Fei Yang, Qi-Te Li, Jin-Yan Xu, Zai-Hong Yang, Kang Wei

Abstract: A transfer reaction and cluster-decay experiment, $^{12}$C($^{16}$O,$^{24}$Mg$\rightarrow$$α$+$^{20}$Ne)$α$, was performed at a beam energy of 96 MeV. Both recoil and decay $α$ particles were detected in coincidence, allowing us to deduce the energy-momentum of a $^{20}$Ne fragment. A number of resonant states of $^{24}$Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owin… ▽ More A transfer reaction and cluster-decay experiment, $^{12}$C($^{16}$O,$^{24}$Mg$\rightarrow$$α$+$^{20}$Ne)$α$, was performed at a beam energy of 96 MeV. Both recoil and decay $α$ particles were detected in coincidence, allowing us to deduce the energy-momentum of a $^{20}$Ne fragment. A number of resonant states of $^{24}$Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the $Q$-value and excitation-energy spectra, the relative decay widths for each resonant state in $^{24}$Mg to various final states of $^{20}$Ne were extracted, alone with the total decay width. The obtained results provide good testing ground for theoretical descriptions of the multiple clustering configurations in $^{24}$Mg. △ Less

Submitted 8 December, 2022; originally announced December 2022.

$^{197}$Au($γ,\,xn;\,x\,=\,1\thicksim9$) Reaction Cross Section Measurements using Laser-Driven Ultra-Intense $γ$-Ray Source

Authors: D. Wu, H. Y. Lan, J. Y. Zhang, J. X. Liu, H. G. Lu, J. F. Lv, X. Z. Wu, H. Zhang, J. Cai, Q. Y. Ma, Y. H. Xia, Z. N. Wang, M. Z. Wang, Z. Y. Yang, X. L. Xu, Y. X. Geng, Y. Y. Zhao, C. Lin, W. J. Ma, J. Q. Yu, H. R. Wang, F. L. Liu, C. Y. He, B. Guo, P. Zhu , et al. (4 additional authors not shown)

Abstract: We present a new method for the measurements of photonuclear reaction flux-weighted average cross sections and isomeric ratios using a laser-driven bremsstrahlung $γ$-ray source. An ultra-bright ultra-fast 60$\,\thicksim\,$250 MeV bremsstrahlung $γ$-ray source was established using the 200 TW laser facility in the Compact Laser Plasma Accelerator Laboratory, Peking University, which could cover th… ▽ More We present a new method for the measurements of photonuclear reaction flux-weighted average cross sections and isomeric ratios using a laser-driven bremsstrahlung $γ$-ray source. An ultra-bright ultra-fast 60$\,\thicksim\,$250 MeV bremsstrahlung $γ$-ray source was established using the 200 TW laser facility in the Compact Laser Plasma Accelerator Laboratory, Peking University, which could cover the energy range from knocking out neutrons to producing pions. Stable quasi-monoenergetic electron beams were generated via laser wakefield acceleration with a charge of 300$\,\thicksim\,$600 pC per shot. The averaged $γ$-ray intensities ($\geqslant$8 MeV) were higher than 10$^{8}$ per shot and the instantaneous intensities can reach above 10$^{19}$ s$^{-1}$ with a duration time about 6.7 ps. $^{65}$Cu($γ,\,n$)$^{64}$Cu and $^{27}$Al($γ,\,x$)$^{24}$Na reactions were used as $γ$-ray flux monitors in the experiments. The flux-weighted average cross sections and isomeric ratios of $^{197}$Au($γ,\,xn;\,x\,=\,1\thicksim9$) reactions were analyzed through activation measurements. The results showed good agreement with previous works and proved this method to be accurate. The $^{197}$Au($γ,\,xn;\,x\,=\,7\thicksim\,9$) reaction cross sections were first achieved with the highest threshold energy of 71.410 MeV. Theoretical cross sections of TALYS 1.9 were calculated to compare with experiment results. This method offered a unique way of gaining insight into photonuclear reaction research, especially for short-lived isomers which extremely lack experimental data. △ Less

Submitted 23 November, 2023; v1 submitted 28 September, 2022; originally announced September 2022.

Detector Requirements and Simulation Results for the EIC Exclusive, Diffractive and Tagging Physics Program using the ECCE Detector Concept

Authors: A. Bylinkin, C. T. Dean, S. Fegan, D. Gangadharan, K. Gates, S. J. D. Kay, I. Korover, W. B. Li, X. Li, R. Montgomery, D. Nguyen, G. Penman, J. R. Pybus, N. Santiesteban, R. Trotta, A. Usman, M. D. Baker, J. Frantz, D. I. Glazier, D. W. Higinbotham, T. Horn, J. Huang, G. Huber, R. Reed, J. Roche , et al. (258 additional authors not shown)

Abstract: This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fr… ▽ More This article presents a collection of simulation studies using the ECCE detector concept in the context of the EIC's exclusive, diffractive, and tagging physics program, which aims to further explore the rich quark-gluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detecter system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirmed the proposed technology and design satisfy the requirements. The projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb^-1 of integrated luminosity. Additionally, a few insights on the potential 2nd Interaction Region can (IR) were also documented which could serve as a guidepost for the future development of a second EIC detector. △ Less

Submitted 6 March, 2023; v1 submitted 30 August, 2022; originally announced August 2022.

Open Heavy Flavor Studies for the ECCE Detector at the Electron Ion Collider

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will… ▽ More The ECCE detector has been recommended as the selected reference detector for the future Electron-Ion Collider (EIC). A series of simulation studies have been carried out to validate the physics feasibility of the ECCE detector. In this paper, detailed studies of heavy flavor hadron and jet reconstruction and physics projections with the ECCE detector performance and different magnet options will be presented. The ECCE detector has enabled precise EIC heavy flavor hadron and jet measurements with a broad kinematic coverage. These proposed heavy flavor measurements will help systematically study the hadronization process in vacuum and nuclear medium especially in the underexplored kinematic region. △ Less

Submitted 23 July, 2022; v1 submitted 21 July, 2022; originally announced July 2022.

Comments: Open heavy flavor studies with the EIC reference detector design by the ECCE consortium. 11 pages, 11 figures, to be submitted to the Nuclear Instruments and Methods A

Report number: LANL report number: LA-UR-22-27181

Exclusive J/$ψ$ Detection and Physics with ECCE

Authors: X. Li, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann, M. H. S. Bukhari, A. Bylinkin , et al. (262 additional authors not shown)

Abstract: Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the… ▽ More Exclusive heavy quarkonium photoproduction is one of the most popular processes in EIC, which has a large cross section and a simple final state. Due to the gluonic nature of the exchange Pomeron, this process can be related to the gluon distributions in the nucleus. The momentum transfer dependence of this process is sensitive to the interaction sites, which provides a powerful tool to probe the spatial distribution of gluons in the nucleus. Recently the problem of the origin of hadron mass has received lots of attention in determining the anomaly contribution $M_{a}$. The trace anomaly is sensitive to the gluon condensate, and exclusive production of quarkonia such as J/$ψ$ and $Υ$ can serve as a sensitive probe to constrain it. In this paper, we present the performance of the ECCE detector for exclusive J/$ψ$ detection and the capability of this process to investigate the above physics opportunities with ECCE. △ Less

Submitted 21 July, 2022; originally announced July 2022.

Comments: 11 pages, 14 figures, 1 table

Design and Simulated Performance of Calorimetry Systems for the ECCE Detector at the Electron Ion Collider

Authors: F. Bock, N. Schmidt, P. K. Wang, N. Santiesteban, T. Horn, J. Huang, J. Lajoie, C. Munoz Camacho, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, W. Boeglin, M. Borysova, E. Brash , et al. (263 additional authors not shown)

Abstract: We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key… ▽ More We describe the design and performance the calorimeter systems used in the ECCE detector design to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapdity range from -3.7 to 3.8 and two hadronic calorimeters. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented. △ Less

Submitted 19 July, 2022; originally announced July 2022.

Comments: 19 pages, 22 figures, 5 tables

AI-assisted Optimization of the ECCE Tracking System at the Electron Ion Collider

Authors: C. Fanelli, Z. Papandreou, K. Suresh, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, J. C. Bernauer, F. Bock, W. Boeglin, M. Borysova, E. Brash, P. Brindza, W. J. Briscoe, M. Brooks, S. Bueltmann , et al. (258 additional authors not shown)

Abstract: The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to… ▽ More The Electron-Ion Collider (EIC) is a cutting-edge accelerator facility that will study the nature of the "glue" that binds the building blocks of the visible matter in the universe. The proposed experiment will be realized at Brookhaven National Laboratory in approximately 10 years from now, with detector design and R&D currently ongoing. Notably, EIC is one of the first large-scale facilities to leverage Artificial Intelligence (AI) already starting from the design and R&D phases. The EIC Comprehensive Chromodynamics Experiment (ECCE) is a consortium that proposed a detector design based on a 1.5T solenoid. The EIC detector proposal review concluded that the ECCE design will serve as the reference design for an EIC detector. Herein we describe a comprehensive optimization of the ECCE tracker using AI. The work required a complex parametrization of the simulated detector system. Our approach dealt with an optimization problem in a multidimensional design space driven by multiple objectives that encode the detector performance, while satisfying several mechanical constraints. We describe our strategy and show results obtained for the ECCE tracking system. The AI-assisted design is agnostic to the simulation framework and can be extended to other sub-detectors or to a system of sub-detectors to further optimize the performance of the EIC detector. △ Less

Submitted 19 May, 2022; v1 submitted 18 May, 2022; originally announced May 2022.

Comments: 16 pages, 18 figures, 2 appendices, 3 tables

Scientific Computing Plan for the ECCE Detector at the Electron Ion Collider

Authors: J. C. Bernauer, C. T. Dean, C. Fanelli, J. Huang, K. Kauder, D. Lawrence, J. D. Osborn, C. Paus, J. K. Adkins, Y. Akiba, A. Albataineh, M. Amaryan, I. C. Arsene, C. Ayerbe Gayoso, J. Bae, X. Bai, M. D. Baker, M. Bashkanov, R. Bellwied, F. Benmokhtar, V. Berdnikov, F. Bock, W. Boeglin, M. Borysova, E. Brash , et al. (256 additional authors not shown)

Abstract: The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing thes… ▽ More The Electron Ion Collider (EIC) is the next generation of precision QCD facility to be built at Brookhaven National Laboratory in conjunction with Thomas Jefferson National Laboratory. There are a significant number of software and computing challenges that need to be overcome at the EIC. During the EIC detector proposal development period, the ECCE consortium began identifying and addressing these challenges in the process of producing a complete detector proposal based upon detailed detector and physics simulations. In this document, the software and computing efforts to produce this proposal are discussed; furthermore, the computing and software model and resources required for the future of ECCE are described. △ Less

Submitted 17 May, 2022; originally announced May 2022.

Journal ref: NIMA 1047, 167859 (2023)

First measurement of high-energy reactor antineutrinos at Daya Bay

Authors: Daya Bay collaboration, F. P. An, A. B. Balantekin, H. R. Band, M. Bishai, S. Blyth, G. F. Cao, J. Cao, J. F. Chang, Y. Chang, H. S. Chen, S. M. Chen, Y. Chen, Y. X. Chen, J. Cheng, Z. K. Cheng, J. J. Cherwinka, M. C. Chu, J. P. Cummings, O. Dalager, F. S. Deng, Y. Y. Ding, M. V. Diwan, T. Dohnal, J. Dove , et al. (162 additional authors not shown)

Abstract: This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12~MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10~MeV is rej… ▽ More This Letter reports the first measurement of high-energy reactor antineutrinos at Daya Bay, with nearly 9000 inverse beta decay candidates in the prompt energy region of 8-12~MeV observed over 1958 days of data collection. A multivariate analysis is used to separate 2500 signal events from background statistically. The hypothesis of no reactor antineutrinos with neutrino energy above 10~MeV is rejected with a significance of 6.2 standard deviations. A 29\% antineutrino flux deficit in the prompt energy region of 8-11~MeV is observed compared to a recent model prediction. We provide the unfolded antineutrino spectrum above 7 MeV as a data-based reference for other experiments. This result provides the first direct observation of the production of antineutrinos from several high-$Q_β$ isotopes in commercial reactors. △ Less

Submitted 8 July, 2022; v1 submitted 13 March, 2022; originally announced March 2022.

Comments: 7 pages, 4 figures, accepted by Physical Review Letters

Journal ref: Phys. Rev. Lett. 129, 041801 (2022)

Joint Determination of Reactor Antineutrino Spectra from $^{235}$U and $^{239}$Pu Fission by Daya Bay and PROSPECT

Authors: Daya Bay Collaboration, PROSPECT Collaboration, F. P. An, M. Andriamirado, A. B. Balantekin, H. R. Band, C. D. Bass, D. E. Bergeron, D. Berish, M. Bishai, S. Blyth, N. S. Bowden, C. D. Bryan, G. F. Cao, J. Cao, J. F. Chang, Y. Chang, H. S. Chen, S. M. Chen, Y. Chen, Y. X. Chen, J. Cheng, Z. K. Cheng, J. J. Cherwinka, M. C. Chu , et al. (217 additional authors not shown)

Abstract: A joint determination of the reactor antineutrino spectra resulting from the fission of $^{235}$U and $^{239}$Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of $^{235}$U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The c… ▽ More A joint determination of the reactor antineutrino spectra resulting from the fission of $^{235}$U and $^{239}$Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of $^{235}$U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant $^{235}$U and $^{239}$Pu isotopes and improves the uncertainty of the $^{235}$U spectral shape to about 3\%. The ${}^{235}$U and $^{239}$Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the $^{235}$U and $^{239}$Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors. △ Less

Submitted 22 February, 2022; v1 submitted 23 June, 2021; originally announced June 2021.

Comments: 8 pages, 5 figures, Supplementary Material Included

Journal ref: Physical Review Letters 128, 081801 (2022)

Observation of a near-threshold structure in the $K^+$ recoil-mass spectra in $e^+e^-\to K^+ (D_s^- D^{*0} + D^{*-}_s D^0)$

Authors: BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, S. Ahmed, M. Albrecht, R. Aliberti, A. Amoroso, Q. An, Anita, X. H. Bai, Y. Bai, O. Bakina, R. Baldini Ferroli, I. Balossino, Y. Ban, K. Begzsuren, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, J Biernat, J. Bloms, A. Bortone, I. Boyko , et al. (481 additional authors not shown)

Abstract: We report a study of the processes of $e^+e^-\to K^+ (D_s^- D^{*0} + D^{*-}_s D^0)$ based on $e^+e^-$ annihilation samples collected with the BESIII detector operating at BEPCII at five center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb$^{-1}$. An excess over the known contributions of the conventional charmed mesons is observed near the… ▽ More We report a study of the processes of $e^+e^-\to K^+ (D_s^- D^{*0} + D^{*-}_s D^0)$ based on $e^+e^-$ annihilation samples collected with the BESIII detector operating at BEPCII at five center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb$^{-1}$. An excess over the known contributions of the conventional charmed mesons is observed near the $D_s^- D^{*0}$ and $D^{*-}_s D^0$ mass thresholds in the $K^{+}$ recoil-mass spectrum for events collected at $\sqrt{s}=4.681$ GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as $(3982.5^{+1.8}_{-2.6}\pm2.1)$ MeV/$c^2$ and $(12.8^{+5.3}_{-4.4}\pm3.0)$ MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 $σ$ over the contributions only from the conventional charmed mesons. This is the first candidate of the charged hidden-charm tetraquark with strangeness, decaying into $D_s^- D^{*0}$ and $D^{*-}_s D^0$. However, the properties of the excess need further exploration with more statistics. △ Less

Submitted 12 March, 2021; v1 submitted 16 November, 2020; originally announced November 2020.

Comments: 17 pages; Version published in Phys. Rev. Lett

Journal ref: Phys. Rev. Lett. 126, 102001 (2021)

Supernova Neutrino Burst Detection with the Deep Underground Neutrino Experiment

Authors: DUNE collaboration, B. Abi, R. Acciarri, M. A. Acero, G. Adamov, D. Adams, M. Adinolfi, Z. Ahmad, J. Ahmed, T. Alion, S. Alonso Monsalve, C. Alt, J. Anderson, C. Andreopoulos, M. P. Andrews, F. Andrianala, S. Andringa, A. Ankowski, M. Antonova, S. Antusch, A. Aranda-Fernandez, A. Ariga, L. O. Arnold, M. A. Arroyave, J. Asaadi , et al. (949 additional authors not shown)

Abstract: The Deep Underground Neutrino Experiment (DUNE), a 40-kton underground liquid argon time projection chamber experiment, will be sensitive to the electron-neutrino flavor component of the burst of neutrinos expected from the next Galactic core-collapse supernova. Such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. The gen… ▽ More The Deep Underground Neutrino Experiment (DUNE), a 40-kton underground liquid argon time projection chamber experiment, will be sensitive to the electron-neutrino flavor component of the burst of neutrinos expected from the next Galactic core-collapse supernova. Such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. The general capabilities of DUNE for neutrino detection in the relevant few- to few-tens-of-MeV neutrino energy range will be described. As an example, DUNE's ability to constrain the $ν_e$ spectral parameters of the neutrino burst will be considered. △ Less

Submitted 29 May, 2021; v1 submitted 15 August, 2020; originally announced August 2020.

Comments: 29 pages, 17 figures; paper based on DUNE Technical Design Report. arXiv admin note: substantial text overlap with arXiv:2002.03005

Report number: FERMILAB-PUB-20-380-LBNF