-
Best Reaction Target To Determine Proton Distribution Radii of Atomic Nuclei
Authors:
Jun-Yao Xu,
Bao-Hua Sun,
Isao Tanihata,
Satoru Terashima,
Jian-Wei Zhao,
Ji-Chao Zhang,
Ge Guo,
Shi-Tao Wang,
Lei Shen,
Jun Su,
Xiao-Dong Xu,
Andrej Prochazka,
Guang-Shuai Li,
Xiu-Lin Wei,
Chang-Jian Wang,
Feng Wang,
Meng Wang,
Jing Wang,
Liu-Chun He,
Chuan-Ye Liu,
Wen-Jian Lin,
Wei-Ping Lin,
Zhong Liu,
Pei-Pei Ren,
Yu Zhang
, et al. (7 additional authors not shown)
Abstract:
We found that a heavy target such as Pb is most suitable for determining the proton distribution radii of unstable nuclei through charge-changing cross-section ($σ_\text{cc}$) measurements. As a heavy ion probe, low-$Z$ targets are routinely used to determine nucleon distribution radii of unstable isotopes. This approach has recently been extended to study proton distribution radii from…
▽ More
We found that a heavy target such as Pb is most suitable for determining the proton distribution radii of unstable nuclei through charge-changing cross-section ($σ_\text{cc}$) measurements. As a heavy ion probe, low-$Z$ targets are routinely used to determine nucleon distribution radii of unstable isotopes. This approach has recently been extended to study proton distribution radii from $σ_\text{cc}$ measurements. However, empirical scaling factors have to be introduced to apply the Glauber models. In the present work, we systematically investigated the scaling factor using 39 new $σ_\text{cc}$ data of 18 $p$-shell nuclei on hydrogen, carbon, silver, and lead targets at around 240 MeV/nucleon. Together with the existing data, we reveal a universal dependence of the scaling factor on both the masses of target nuclei and the separation energies of projectile nuclei. The scaling factors decrease with increasing target-nucleus mass and converge to 1 for the highest-$Z$ target, making the scaling unnecessary. We conclude that instead of a low-$Z$ target, employing a heavy target such as Pb in $σ_\text{cc}$ measurements is the best option to determine the proton distribution radii of unstable nuclei.
△ Less
Submitted 14 August, 2026;
originally announced August 2026.
-
Modification of $Υ$ production in $p$O and OO collisions at LHCb
Authors:
LHCb collaboration,
R. Aaij,
M. Abdelfatah,
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,
S. Akar,
K. Akiba,
H. Al Saleh,
P. Albicocco,
J. Albrecht,
R. Aleksiejunas,
F. Alessio,
P. Alvarez Cartelle,
S. Amato,
J. L. Amey,
Y. Amhis,
Z. Amos
, et al. (1166 additional authors not shown)
Abstract:
The production rates of $\mathitΥ(2S)$ and $\mathitΥ(3S)$ mesons relative to that of the $\mathitΥ(1S)$ state are measured in $pp$, $p$O, and OO collisions by the LHCb collaboration. The ratios measured in $pp$ data are consistent with previous LHCb measurements at different center-of-mass energies. Only slight relative suppression of the $\mathitΥ(2S)$ and $\mathitΥ(3S)$ states is found in $p$O c…
▽ More
The production rates of $\mathitΥ(2S)$ and $\mathitΥ(3S)$ mesons relative to that of the $\mathitΥ(1S)$ state are measured in $pp$, $p$O, and OO collisions by the LHCb collaboration. The ratios measured in $pp$ data are consistent with previous LHCb measurements at different center-of-mass energies. Only slight relative suppression of the $\mathitΥ(2S)$ and $\mathitΥ(3S)$ states is found in $p$O collisions, while in OO collisions the $\mathitΥ(2S)$ is suppressed by a factor of $\sim2$, with evidence for suppression of the $\mathitΥ(3S)$. The significant suppression in OO data, compared to the small effect in $p$O data, shows the emergence of additional suppression mechanisms in the relatively small OO collision system. Models incorporating quark-gluon plasma formation in OO collisions successfully describe the data. Implications for the interplay between cold nuclear matter effects and color screening in a deconfined quark-gluon plasma are discussed.
△ Less
Submitted 31 July, 2026;
originally announced August 2026.
-
Basis Representation for Nuclear Densities from Principal Component Analysis
Authors:
Chen-Jun Lv,
Tian-Yu Wu,
Xin-Hui Wu,
Gianluca Colò,
Kouichi Hagino
Abstract:
We develop an efficient method to represent nuclear densities using basis functions extracted via Principal Component Analysis (PCA). Applying PCA to densities of 75 nuclei calculated with the relativistic continuum Hartree-Bogoliubov (RCHB) theory yields an orthogonal set of components that efficiently capture the dominant features of nuclear density distributions, which can be used as basis func…
▽ More
We develop an efficient method to represent nuclear densities using basis functions extracted via Principal Component Analysis (PCA). Applying PCA to densities of 75 nuclei calculated with the relativistic continuum Hartree-Bogoliubov (RCHB) theory yields an orthogonal set of components that efficiently capture the dominant features of nuclear density distributions, which can be used as basis functions for nuclear density representation. The first five basis functions account for more than 99.999\% of the total variance, demonstrating the efficiency of these PCA basis functions. The PCA basis achieves significantly higher accuracy and faster convergence than the Fourier-Bessel and Sum-of-Gaussians methods for reconstructing both theoretical and experimental densities. This approach provides an efficient and robust representation of nuclear densities, offering a practical tool for experimental density representation and for theories where densities play a central role, such as the orbital-free density functional theory, or the double folding model for nuclear reactions.
△ Less
Submitted 2 March, 2026; v1 submitted 24 January, 2026;
originally announced January 2026.
-
Point-proton density distributions of stable nuclei
Authors:
Tianyu Wu,
Baohua Sun,
Huihui Xie,
Junyao Xu,
Ge Guo
Abstract:
Point-proton density distributions are deduced for 130 stable nuclei from $^{7}\mathrm{Li}$ to $^{232}\mathrm{Th}$ from nuclear charge densities determined in elastic electron scattering. There are 171 cases are presented in model-dependent forms, including the modified Harmonic-oscillator function, two-parameter Femi function (2pF), three-parameter Femi function, three-parameter Gaussian function…
▽ More
Point-proton density distributions are deduced for 130 stable nuclei from $^{7}\mathrm{Li}$ to $^{232}\mathrm{Th}$ from nuclear charge densities determined in elastic electron scattering. There are 171 cases are presented in model-dependent forms, including the modified Harmonic-oscillator function, two-parameter Femi function (2pF), three-parameter Femi function, three-parameter Gaussian function, and 97 in Fourier-Bessel series model-independent forms. Independent of density functions, the point-proton root-mean-square (rms) radii of the derived point-proton density show excellent agreement with each other. We identify cases where the tabulated data of charge densities and charge radii are inconsistent, and the deduced point-proton density distributions are inaccurate due to insufficient experimental momentum transfer coverage or inconsistent scattering experiments. For the widely used 2pF distribution, it is found that the surface diffuseness parameters can be empirically calculated from those of charge density, while the half-density radius parameters follow the $A^{1/3}$ rule. The derived point-proton density distributions can be used as input in nuclear reaction studies and compared with nuclear model predictions.
△ Less
Submitted 7 May, 2025;
originally announced May 2025.
-
Full realization of the RIBLL2 separator at the HIRFL-CSR facility
Authors:
Xiao-Dong Xu,
Yong Zheng,
Zhi-Yu Sun,
Yu-Nan Song,
Bao-Hua Sun,
Satoru Terashima,
Chang-Jian Wang,
Ge Guo,
Guang-Shuai Li,
Xiu-Lin Wei,
Jun-Yao Xu,
Ji-Chao Zhang,
Yong Cao,
Bing-Shui Gao,
Jia-Xing Han,
Jin-Rong Liu,
Chen-Gui Lu,
Shu-Ya Jin,
Hooi Jin Ong,
Hao-Tian Qi,
Yun Qin,
Ya-Zhou Sun,
Isao Tanihata,
Lu-Ping Wan,
Kai-Long Wang
, et al. (11 additional authors not shown)
Abstract:
A new experimental platform was constructed at the Second Radioactive Ion Beam Line in Lanzhou (RIBLL2) of HIRFL-CSR accelerator facility at Lanzhou, China. Its performance, along with several newly developed detectors, was tested in two radioactive ion beam experiments utilizing a 400 MeV/u 40Ar beam and a 350 MeV/u 78Kr beam, respectively. The first results from these two experiments demonstrate…
▽ More
A new experimental platform was constructed at the Second Radioactive Ion Beam Line in Lanzhou (RIBLL2) of HIRFL-CSR accelerator facility at Lanzhou, China. Its performance, along with several newly developed detectors, was tested in two radioactive ion beam experiments utilizing a 400 MeV/u 40Ar beam and a 350 MeV/u 78Kr beam, respectively. The first results from these two experiments demonstrate a good particle identification capability of the setup, thereby affirming the full realization of the RIBLL2 separator.
△ Less
Submitted 30 April, 2025;
originally announced May 2025.
-
Three ways to decipher the nature of exotic hadrons: multiplets, three-body hadronic molecules, and correlation functions
Authors:
Ming-Zhu Liu,
Ya-Wen Pan,
Zhi-Wei Liu,
Tian-Wei Wu,
Jun-Xu Lu,
Li-Sheng Geng
Abstract:
In the past two decades, a plethora of hadronic states beyond the conventional quark model of $q\bar{q}$ mesons and $qqq$ baryons have been observed experimentally, which motivated extensive studies to understand their nature and the non-perturbative strong interaction. Since most of these exotic states are near the mass thresholds of a pair of conventional hadrons, the prevailing picture is that…
▽ More
In the past two decades, a plethora of hadronic states beyond the conventional quark model of $q\bar{q}$ mesons and $qqq$ baryons have been observed experimentally, which motivated extensive studies to understand their nature and the non-perturbative strong interaction. Since most of these exotic states are near the mass thresholds of a pair of conventional hadrons, the prevailing picture is that they are primarily hadronic molecules. In principle, one can verify the molecular nature of these states by thoroughly comparing their masses, decay widths, and production rates in a particular picture with experimental data. However, this is difficult or impossible. First, quantum mechanics allows for the mixing of configurations allowed by symmetries and quantum numbers. Second, data are relatively scarce because of their small production rates and the many difficulties in the experimental measurements. As a result, other alternatives need to be explored. This review summarizes three such approaches that can help disentangle the nature of the many exotic hadrons discovered. In the first approach, based on the molecular interpretations for some exotic states, we study the likely existence of multiplets of hadronic molecules related by various symmetries, such as isospin symmetry, SU(3)-flavor symmetry, heavy quark spin/flavor symmetry, and heavy antiquark diquark symmetry. In the second approach, starting from some hadronic molecular candidates, one can derive the underlying hadron-hadron interactions. With these interactions, one can study related three-body systems and check whether three-body bound states/resonances exist. In the third approach, one can turn to the femtoscopy technique to derive the hadron-hadron interactions, hence inaccessible. This technique provided an unprecedented opportunity to understand the interactions between unstable hadrons.
△ Less
Submitted 16 December, 2024; v1 submitted 9 April, 2024;
originally announced April 2024.
-
Production of the $ΞN$ dibaryon as a weakly bound system in $pp$ collisions
Authors:
Tian-Chen Wu,
Atsushi Hosaka,
Li-Sheng Geng
Abstract:
The $ΞN$ interaction plays an important role in our understanding on the long-anticipated $H$-dibaryon. Recent lattice QCD calculations verified the attractive nature of the $ΞN$ interaction. On the other hand, whether it is strong enough to generate a bound state remains inconclusive.In this work, assuming that it can generate a weakly bound state, we study the yields of the $ΞN$ dibaryon for dif…
▽ More
The $ΞN$ interaction plays an important role in our understanding on the long-anticipated $H$-dibaryon. Recent lattice QCD calculations verified the attractive nature of the $ΞN$ interaction. On the other hand, whether it is strong enough to generate a bound state remains inconclusive.In this work, assuming that it can generate a weakly bound state, we study the yields of the $ΞN$ dibaryon for different binding energies in $pp$ collisions at 7 TeV using the coalescence model and the transport model PACIAE. The yields are estimated first numerically and then analytically adopting a Yukawa-type wave function. In particular, we find that in the weak binding limit, there exists a universal relation between the yield and the binding energy, valid for $pp$ collisions.
△ Less
Submitted 3 November, 2023;
originally announced November 2023.
-
The Performance of AC-coupled Strip LGAD developed by IHEP
Authors:
Weiyi Sun,
Mengzhao Li,
Zhijun Liang,
Mei Zhao,
Xiaoxu Zhang,
Tianyuan Zhang,
Yuan Feng,
Shuqi Li,
Xinhui Huang,
Yunyun Fan,
Tianya Wu,
Xuan Yang,
Bo Liu,
Wei Wang. Yuekun Heng,
Gaobo Xu,
João Guimaraes da Costa
Abstract:
The AC-coupled Strip LGAD (Strip AC-LGAD) is a novel LGAD design that diminishes the density of readout electronics through the use of strip electrodes, enabling the simultaneous measurement of time and spatial information. The Institute of High Energy Physics has designed a long Strip AC-LGAD prototype with a strip electrode length of 5.7 mm and pitches of 150 $μm$, 200 $μm$, and 250 $μm$. Spatia…
▽ More
The AC-coupled Strip LGAD (Strip AC-LGAD) is a novel LGAD design that diminishes the density of readout electronics through the use of strip electrodes, enabling the simultaneous measurement of time and spatial information. The Institute of High Energy Physics has designed a long Strip AC-LGAD prototype with a strip electrode length of 5.7 mm and pitches of 150 $μm$, 200 $μm$, and 250 $μm$. Spatial and timing resolutions of the long Strip AC-LGAD are studied by pico-second laser test and beta source tests. The laser test demonstrates that spatial resolution improves as the pitch size decreases, with an optimal resolution achieved at 8.3 $μ$m. Furthermore, the Beta source test yields a timing resolution of 37.6 ps.
△ Less
Submitted 2 May, 2024; v1 submitted 8 July, 2023;
originally announced July 2023.
-
Tribaryons with lattice QCD and one-boson exchange potentials
Authors:
Tian-Wei Wu,
Si-Qiang Luo,
Ming-Zhu Liu,
Li-Sheng Geng,
Xiang Liu
Abstract:
Motivated by the existence of two-body hadronic molecules composed of $ΩΩ$, $Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}$ predicted by lattice QCD simulations, we use the Gaussian expansion method to investigate whether three-body systems composed of $ΩΩΩ$, $Ω_{ccc}Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}Ω_{bbb}$ can bind with the two-body $^1S_0$ interactions provided by lattice QCD. Our results show that non…
▽ More
Motivated by the existence of two-body hadronic molecules composed of $ΩΩ$, $Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}$ predicted by lattice QCD simulations, we use the Gaussian expansion method to investigate whether three-body systems composed of $ΩΩΩ$, $Ω_{ccc}Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}Ω_{bbb}$ can bind with the two-body $^1S_0$ interactions provided by lattice QCD. Our results show that none of the three-body systems bind. On the other hand, we find that with the one-boson exchange potentials the $ΩΩΩ$ system develops a bound state, for which the $^5S_2$ interaction plays an important role. Our studies support the existence of the $\frac{3}{2}^+$ $ΩΩΩ$ bound state and the nonexistence of the $\frac{3}{2}^+$ $Ω_{ccc}Ω_{ccc}Ω_{ccc}$ and $Ω_{bbb}Ω_{bbb}Ω_{bbb}$ bound states, due to the suppressed $^5S_2$ interactions in heavier systems.
△ Less
Submitted 22 November, 2023; v1 submitted 2 January, 2023;
originally announced January 2023.
-
Multi-hadron molecules: status and prospect
Authors:
Tian-Wei Wu,
Ya-Wen Pan,
Ming-Zhu Liu,
Li-Sheng Geng
Abstract:
Starting from 2003, the discovery of a large amount of the so-called exotic hadronic states, i.e., the $XYZ$ states, the pentaquark states as well as the tetraquark states, have not only revived studies of hadron spectroscopy, but also hinted at the existence of new multi-hadron states made of hadrons other than nucleons and hyperons. We briefly comment on some of the latest studies on multi-hadro…
▽ More
Starting from 2003, the discovery of a large amount of the so-called exotic hadronic states, i.e., the $XYZ$ states, the pentaquark states as well as the tetraquark states, have not only revived studies of hadron spectroscopy, but also hinted at the existence of new multi-hadron states made of hadrons other than nucleons and hyperons. We briefly comment on some of the latest studies on multi-hadron molecules in the light and heavy flavor sectors and highlight what should be done in the future.
△ Less
Submitted 1 August, 2022;
originally announced August 2022.
-
Evaluation of a Positron-Emission-Tomography-based SiPM readout for Compact Segmented Neutron Imagers
Authors:
Viacheslav A. Li,
Felicia Sutanto,
Timothy M. Classen,
Steven A. Dazeley,
Igor Jovanovic,
Tingshiuan C. Wu
Abstract:
Gamma-ray emission from special nuclear material (SNM) is relatively easy to shield from detection using modest amounts of high-Z material. In contrast, fast-neutrons are much more penetrating and can escape relatively thick high-Z shielding without losing significant energy. Furthermore, fast neutrons provide a clear and unambiguous signature of the presence of SNM with few competing natural back…
▽ More
Gamma-ray emission from special nuclear material (SNM) is relatively easy to shield from detection using modest amounts of high-Z material. In contrast, fast-neutrons are much more penetrating and can escape relatively thick high-Z shielding without losing significant energy. Furthermore, fast neutrons provide a clear and unambiguous signature of the presence of SNM with few competing natural background sources. The challenge of detecting fast neutrons is twofold. First, the neutron flux from SNM are only a fraction of the corresponding gamma-ray flux. Second, fast neutrons can be difficult to differentiate from gamma rays. The ability to discriminate gamma rays from neutrons combined with neutron imaging can yield large benefit to isolate the localized SNM neutron source from background. With the recent developments of pulse-shape-sensitive plastic scintillators that offer excellent gamma-ray/neutron discrimination, and arrays of silicon photomultipliers combined with highly scalable and fast positron-emission-tomography (PET) multi-channel readout systems, field-deployable neutron imagers suitable for SNM detection might now be within reach. In this paper, we present a characterization of the performance of a recently available commercial PET-scanner readout, including its sensitivity to pulse-shape differences between fast neutrons and gamma rays, energy and timing resolution, as well as linearity and dynamic range. We find that, while the pulse-shape discrimination is achievable with stilbene, further improvement of the readout is required to achieve it with the best available plastic scintillators. The time and energy resolution appear to be adequate for neutron imaging in some circumstances.
△ Less
Submitted 15 February, 2022;
originally announced February 2022.
-
$DK$, $DDK$, and $DDDK$ molecules--understanding the nature of the $D_{s0}^*(2317)$
Authors:
Tian-Wei Wu,
Ming-Zhu Liu,
Li-Sheng Geng,
Emiko Hiyama,
Manuel Pavon Valderrama
Abstract:
The $DK$ interaction is strong enough to form a bound state, the $D_{s0}^*(2317)$. This in turn begs the question of whether there are bound states composed of several charmed mesons and a kaon. Previous calculations indicate that the three-body $DDK$ system is probably bound, where the quantum numbers are $J^P = 0^{-}$, $I=\tfrac{1}{2}$, $S = 1$ and $C = 2$. The minimum quark content of this stat…
▽ More
The $DK$ interaction is strong enough to form a bound state, the $D_{s0}^*(2317)$. This in turn begs the question of whether there are bound states composed of several charmed mesons and a kaon. Previous calculations indicate that the three-body $DDK$ system is probably bound, where the quantum numbers are $J^P = 0^{-}$, $I=\tfrac{1}{2}$, $S = 1$ and $C = 2$. The minimum quark content of this state is $cc\bar{q}\bar{s}$ with $q=u,d$, which means that, if discovered, it will be an explicitly exotic tetraquark. In the present work. we apply the Gaussian Expansion Method to study the $DDDK$ system and show that it binds as well. The existence of these three and four body states is rather robust with respect to the $DD$ interaction and subleading (chiral) corrections to the $DK$ interaction. If these states exist, it is quite likely that their heavy quark symmetry counterparts exist as well. These three-body $DDK$ and four-body $DDDK$ molecular states could be viewed as counterparts of atomic nuclei, which are clusters of nucleons bound by the residual strong force, or chemical molecules, which are clusters of atoms bound by the residual electromagnetic interaction.
△ Less
Submitted 27 June, 2019;
originally announced June 2019.
-
Observation of $^{6}$He+$t$ cluster states in $^{9}$Li
Authors:
W. H. Ma,
J. S. Wang,
D. Patel,
Y. Y. Yang,
J. B. Ma,
S. L. Jin,
P. Ma,
Q. Hu,
Z. Bai,
M. R. Huang,
X. Q. Liu,
Y. J. Zhou,
J. Chen,
Z. H. Gao,
Q. Wang,
J. Lubian,
J. X. Li,
T. F. Wang,
S. Mukherjee,
X. Y. Ju,
Y. S. Yu,
T. W. Wu,
C. Ni,
X. D. Jia,
Q. B. Liu
, et al. (3 additional authors not shown)
Abstract:
$^{6}$He+$t$ cluster states of exited $^{9}$Li have been measured by 32.7 MeV/nucleon $^{9}$Li beams bombarding on $^{208}$Pb target. Two resonant states are clearly observed with the excitation energies at 9.8 MeV and 12.6 MeV and spin-parity of 3/2$^{-}$ and 7/2$^{-}$ respectively. These two states are considered to be members of K$^π$=1/2$^{-}…
▽ More
$^{6}$He+$t$ cluster states of exited $^{9}$Li have been measured by 32.7 MeV/nucleon $^{9}$Li beams bombarding on $^{208}$Pb target. Two resonant states are clearly observed with the excitation energies at 9.8 MeV and 12.6 MeV and spin-parity of 3/2$^{-}$ and 7/2$^{-}$ respectively. These two states are considered to be members of K$^π$=1/2$^{-}$ band. The spin-parity of them are identified by the method of angular correlation analysis and verified by the continuum discretized coupled channels (CDCC) calculation, which agrees with the prediction of the generator coordinate method (GCM). A monopole matrix element about 4 fm$^{2}$ for the 3/2$^{-}$ state is extracted from the distorted wave Born approximation (DWBA) calculation. These results strongly support the feature of clustering structure of two neutron-rich clusters in the neutron-rich nucleus $^{9}$Li for the first time.
△ Less
Submitted 5 January, 2018; v1 submitted 7 September, 2017;
originally announced September 2017.