Showing 1–50 of 857 results for author: Liu, X

Tracing Vacuum Hadronization with Conserved Currents

Authors: Weiyao Ke, Hai Tao Li, Wanchen Li, Xiaohui Liu, Ding Yu Shao

Abstract: We show that color triality constrains the nonperturbative states that screen a Wilson-line endpoint, allowing the joint flows of net electric charge, baryon number, and strangeness to probe QCD vacuum hadronization. Whether evaluated from resolved hadrons in a jet initiated by a quark of flavor $f$ or from the corresponding charge correlators, these flows satisfy the Gell-Mann--Nishijima relation… ▽ More We show that color triality constrains the nonperturbative states that screen a Wilson-line endpoint, allowing the joint flows of net electric charge, baryon number, and strangeness to probe QCD vacuum hadronization. Whether evaluated from resolved hadrons in a jet initiated by a quark of flavor $f$ or from the corresponding charge correlators, these flows satisfy the Gell-Mann--Nishijima relation $\langle Q_{\rm flow}\rangle_f \simeq I_{3,f} +\frac{1}{2}\left( \langle S_{\rm flow}\rangle_f +\langle B_{\rm flow}\rangle_f \right)$, where $I_{3,f}$ is the third component of the initiating-quark isospin. The net jet baryon number, $\langle B_{\rm flow}\rangle_f\simeq \frac{r_{qq}}{1+r_{qq}}$, directly probes the relative probability of a diquark--antidiquark vacuum excitation, with $r_{qq}$ the diquark-to-quark production ratio. Thus, for $r_{qq}\ll1$, the baryon number carried by the jet is substantially suppressed relative to the initiating-quark value $B_f=1/3$. Likewise, the strange-to-light pair-production ratio, defined by $u\bar u:d\bar d:s\bar s=1:1:r_s$, is encoded in the measured jet strangeness $\langle S_{\rm flow}\rangle_f \simeq S_f+\frac{3r_s}{2+r_s} \left(\frac{1}{3}- \langle B_{\rm flow}\rangle_f\right)$, predicting a nonzero mean net strangeness even in $u$- and $d$-initiated jets. The conserved-current moments appearing in these relations are independent of the renormalization scale. Their simultaneous measurement therefore provides a direct, flavor-resolved probe of vacuum pair production and quantum-number transport during hadronization. △ Less

Submitted 20 August, 2026; originally announced August 2026.

Comments: 25 pages, 8 figures, 3 tables, including 4 pages of appendices

Bound-state spectra of $χ_{cJ}$ in finite nuclei and the universal pattern of mass levels

Authors: Tian-Le Gao, Ze-Hua Zhang, Xiang Liu

Abstract: In this work, we investigate possible $χ_{cJ}$--nuclear bound states with $J=0,1,2$ using in-medium mass shifts generated by virtual $D^{(*)}\bar{D}^{(*)}$ loops within an unquenched framework. The resulting $χ_{cJ}$--nucleus potentials are constructed in the local density approximation, and the bound state spectra are calculated for $^{12}{\rm C}$, $^{16}{\rm O}$, $^{40}{\rm Ca}$,… ▽ More In this work, we investigate possible $χ_{cJ}$--nuclear bound states with $J=0,1,2$ using in-medium mass shifts generated by virtual $D^{(*)}\bar{D}^{(*)}$ loops within an unquenched framework. The resulting $χ_{cJ}$--nucleus potentials are constructed in the local density approximation, and the bound state spectra are calculated for $^{12}{\rm C}$, $^{16}{\rm O}$, $^{40}{\rm Ca}$, $^{90}{\rm Zr}$, $^{197}{\rm Au}$, and $^{208}{\rm Pb}$. Bound states are obtained for all systems considered. The $χ_{c0}(1P)$ and $χ_{c1}(1P)$ spectra are nearly degenerate, whereas the larger in-medium mass shift of $χ_{c2}(1P)$ leads to deeper binding. Although the absolute bound state energies depend appreciably on the cutoff parameter, the energy differences relative to the $1s$ level are considerably less sensitive to it and exhibit a regular pattern that decreases approximately as $A^{-2/3}$ with increasing nuclear mass number. A cosh-type potential with a common nuclear geometry provides a compact description of these spectra. The predicted bound-state structures and level-spacing systematics could be investigated in future high-statistics near-threshold photoproduction experiments at the upgraded JLab facility. △ Less

Submitted 18 August, 2026; originally announced August 2026.

Comments: 14 pages, 5 figures and 5 tables

Truncation of the Radial Ladder in Heavy Quarkonia

Authors: Wen-Xuan Zhang, Si-Qiang Luo, Xiang Liu

Abstract: A fundamental open question in hadron spectroscopy is whether the radial excitation ladder of quarkonia truncates at a finite level---a possibility that would challenge the conventional quark-antiquark bound-state picture and offer decisive clues to the nonperturbative strong interaction. Taking advantage of the newly observed high-mass hadronic states, we address this issue by solving a screened… ▽ More A fundamental open question in hadron spectroscopy is whether the radial excitation ladder of quarkonia truncates at a finite level---a possibility that would challenge the conventional quark-antiquark bound-state picture and offer decisive clues to the nonperturbative strong interaction. Taking advantage of the newly observed high-mass hadronic states, we address this issue by solving a screened Godfrey--Isgur Hamiltonian for charmonium and bottomonium using the Gaussian expansion method. The calculated spectra saturate at $4.74\,\mathrm{GeV}$ ($c\bar{c}$) and $11.67\,\mathrm{GeV}$ ($b\bar{b}$), while root-mean-square radii grow to $\sim10\,\mathrm{fm}$---an order of magnitude above the confinement scale---where adjacent mass gaps drop below $10\,\mathrm{MeV}$. Combining a threshold-based mass-gap criterion, defined by the onset of mass--radius decoupling, with additional diagnostics, we locate the operational upper radial limits at $n\approx8$--$10$ for charmonium and $n\approx12$--$13$ for bottomonium. Beyond these limits, the conventional $q\bar{q}$ description ceases to apply. This work provides the first quantitative determination of these upper limits, and the proposed criterion is directly testable with forthcoming high-statistics data from BESIII, Belle II, and LHCb. △ Less

Submitted 17 August, 2026; originally announced August 2026.

Comments: Manuscript (5 pages) combined with Supplemental Material (16 pages)

Universality and Kinematic Dependence of Hadronization Effects in DIS Global Event Shapes

Authors: Radja Boughezal, Haotian Cao, Zhong-Bo Kang, Xiaohui Liu, Sonny Mantry, Frank Petriello

Abstract: We propose a unified framework for a combined global analysis to constrain leading hadronization effects across the 1-Jettiness class of global event shapes for Deep Inelastic Scattering (DIS). We show that for the subclass of jet-based event shapes where the leading jet direction is determined dynamically event-by-event, the leading hadronization effects can acquire a non-trivial dependence on th… ▽ More We propose a unified framework for a combined global analysis to constrain leading hadronization effects across the 1-Jettiness class of global event shapes for Deep Inelastic Scattering (DIS). We show that for the subclass of jet-based event shapes where the leading jet direction is determined dynamically event-by-event, the leading hadronization effects can acquire a non-trivial dependence on the hard scattering kinematics. However, this dependence is explicitly calculable, allowing for universality of leading hadronization effects in the 1-Jettiness class. The non-trivial kinematic dependence provides an independent lever arm for simultaneously constraining hadronization effects in the jet-based and DIS thrust event shapes. This universality, combined with the kinematic lever arm, could allow for including the typically ignored peak region, where hadronization effects are most severe, in precision extractions of the strong coupling. We demonstrate the need for such a unified treatment of hadronization effects through comparisons of theoretical predictions with simulation data. △ Less

Submitted 16 August, 2026; originally announced August 2026.

Exploring charmonia $η_c(6S,7S)$ in the $Λ_c^+\barΛ_c^-$ invariant mass spectrum of $B^0 \to K_S^0Λ_c^+\barΛ_c^-$

Authors: Cheng-Xi Liu, Jun-Zhang Wang, Xiang Liu

Abstract: We analyze the $B^0 \to K_S^0 Λ_c^+ \barΛ_c^-$ decay recently observed by the LHCb Collaboration. The $Λ_c^+\barΛ_c^-$ invariant-mass spectrum exhibits an accumulation near 4.63~GeV, which we investigate together with the accompanying $Λ_c^+ K_S^0$ spectrum constrained by the known $Ξ_c(2923)$ and $Ξ_c(2939)$ states. Our amplitude model includes a nonresonant term, the two established $Ξ_c$ contri… ▽ More We analyze the $B^0 \to K_S^0 Λ_c^+ \barΛ_c^-$ decay recently observed by the LHCb Collaboration. The $Λ_c^+\barΛ_c^-$ invariant-mass spectrum exhibits an accumulation near 4.63~GeV, which we investigate together with the accompanying $Λ_c^+ K_S^0$ spectrum constrained by the known $Ξ_c(2923)$ and $Ξ_c(2939)$ states. Our amplitude model includes a nonresonant term, the two established $Ξ_c$ contributions, and high-lying charmonium states in the $Λ_c^+\barΛ_c^-$ channel. Guided by screened Godfrey--Isgur and quark-pair-creation calculations, we test the 4.63~GeV enhancement with a fixed $η_c(6S)$ amplitude at $(4629.00, 24.20)$~MeV, {which improves the description of the 4.63~GeV region}, and examine a fixed $η_c(7S)$ contribution at $(4718.84, 22.84)$~MeV, which improves the higher-mass region of the spectrum. We also evaluate the $η_c(nS) \to Λ_c^+ \barΛ_c^-$ baryonic decays via a hadron-loop mechanism and estimate the $B^0 \to K_S^0 η_c(nS)$ production in naive factorization. Within the narrow width approximation, the fit yields a $\mathcal B(B^0\to K_S^0η_c(6S)) \mathcal B(η_c(6S)\toΛ_c^+\barΛ_c^-)$ of about $6.2 \times 10^{-6}$, while the factorization and hadron-loop calculations give rates roughly one to three orders of magnitude lower than the above fitted ratio. These results highlight the need for more precise data and a full amplitude analysis to determine the line shapes and clarify the nature of the higher-mass contribution. △ Less

Submitted 16 August, 2026; originally announced August 2026.

Comments: 12 pages, 4 figures and 3 tables

Strong $\mathcal{CP}$ and Quark Mass Hierarchies from Modular Invariance

Authors: Xiang-Gan Liu, Michael Ratz, Alexander Stewart

Abstract: The strong $\mathcal{CP}$ problem and quark mass hierarchies can probe the same ultraviolet structure. We show this by extending modular strong-$\mathcal{CP}$ solutions to non-Abelian finite modular symmetries. This reveals a previously overlooked modular-anomaly condition from the finite representations. Regularity removes the dependence of the QCD angle on the $\mathcal{CP}$-breaking modulus, yi… ▽ More The strong $\mathcal{CP}$ problem and quark mass hierarchies can probe the same ultraviolet structure. We show this by extending modular strong-$\mathcal{CP}$ solutions to non-Abelian finite modular symmetries. This reveals a previously overlooked modular-anomaly condition from the finite representations. Regularity removes the dependence of the QCD angle on the $\mathcal{CP}$-breaking modulus, yielding $\barθ=0$. For positive modular weight, it also forces the quark Yukawa determinant to vanish at the cusp. This leads to pronounced mass hierarchies among the quarks. We further stress that modular symmetries act as R-symmetries. Under moderate additional assumptions, this renders the QCD angle independent of the dilaton. An explicit model illustrates the mechanism. △ Less

Submitted 13 August, 2026; originally announced August 2026.

Comments: 6 pages, 1 figure; Supplemental Material included

The $K(1690)$ signal from COMPASS as a strange hybrid state

Authors: Bing Chen, Ri-Qing Qian, Xiang Liu

Abstract: A pseudoscalar resonance structure, denoted as the $K(1690)$, was recently discovered by the COMPASS Collaboration in the scattering reaction $K^-+p\to K^-π^-π^++p$. If the $K(1690)$ is a genuine state, there are three observed pseudoscalar strange mesons, namely the $K(1460)$, $K(1690)$, and $K(1830)$, in the 1.0$-$2.0 GeV region. However, within the conventional quark model, only the $2^1S_0$ an… ▽ More A pseudoscalar resonance structure, denoted as the $K(1690)$, was recently discovered by the COMPASS Collaboration in the scattering reaction $K^-+p\to K^-π^-π^++p$. If the $K(1690)$ is a genuine state, there are three observed pseudoscalar strange mesons, namely the $K(1460)$, $K(1690)$, and $K(1830)$, in the 1.0$-$2.0 GeV region. However, within the conventional quark model, only the $2^1S_0$ and $3^1S_0$ strange meson states are expected in this energy region. Therefore, at least one of these states should be interpreted as an exotic candidate. In this work, we study the spectrum of strange mesons systematically, and find that the $K(1460)$ and $K(1830)$ are good candidates of $2^1S_0$ and $3^1S_0$ strange mesons, respectively. A further investigation of their strong decays also supports this assignment. Furthermore, we note that the production mechanism of the $K(1690)$ is similar to that of the $π_1(1600)$, which has been widely regarded as a hybrid meson candidate. We investigate the strong decays of the $K(1690)$ within a constituent gluon model by treating it as a $0^-$ strange hybrid meson and find that the results support the $K(1690)$ as a hybrid state. Finally, we identify several important decay modes of the $K(1690)$ that may be used in future experiments to test whether it contains the $n^1S_0$ ($n=$2 and 3) $s\bar{q}$ component. We also suggest BESIII to search for the $K(1690)$ state through the $J/ψ\to K K(1690) \to KK^{\ast}_0(1430)π\to KKππ$ process. △ Less

Submitted 10 August, 2026; v1 submitted 22 July, 2026; originally announced July 2026.

Comments: 7 pages, 1 figures, 5 tables. Version accepted by PRD

Transverse Charge Distribution as a Probe of Nucleon Transversity

Authors: Wanchen Li, Xiaohui Liu, Ding Yu Shao

Abstract: We introduce the transverse charge distribution as a spin-sensitive charge-flow probe for fragmentation and nucleon tomography. By measuring the angular distribution of net electric charge around a fragmenting quark, this observable relies entirely on the tracking of charged-particle directions and charge signs, strictly bypassing the need for calorimetric energy measurements. At leading twist, th… ▽ More We introduce the transverse charge distribution as a spin-sensitive charge-flow probe for fragmentation and nucleon tomography. By measuring the angular distribution of net electric charge around a fragmenting quark, this observable relies entirely on the tracking of charged-particle directions and charge signs, strictly bypassing the need for calorimetric energy measurements. At leading twist, the distribution decomposes into an unpolarized charge monopole and a chiral-odd transverse charge dipole. We derive the operator product expansion of these distributions onto charge-weighted collinear moments: a charge monopole and a charge dipole governed by the Collins effect and couples directly to transversity. Applying this formalism to transversely polarized $p^\uparrow p$ collisions at RHIC, we show that charge weighting suppresses the unpolarized monopole background and causes the spin-dependent dipoles from oppositely charged hadrons to add coherently. This coherence strongly enhances the resulting azimuthal asymmetries, establishing a theoretically clean and experimentally precise track-only avenue for extracting transversity. △ Less

Submitted 6 August, 2026; v1 submitted 17 July, 2026; originally announced July 2026.

Comments: 7 pages, 4 figures + Supplemental Material (5 pages, 1 figure)

$λ$, $ρ$, and $σ$ Regge trajectories for the quadruply heavy pentaquark $bb\bar{u}cc$ in the diquark-triquark picture

Authors: Xin-Ru Liu, Qi Liu, Jiao-Kai Chen

Abstract: Systematic investigations of four series of Regge trajectories for quadruply heavy pentaquarks are still lacking. Using the diquark and triquark Regge trajectory relations, we propose the Regge trajectory relations for the quadruply heavy pentaquark ${bb\bar{u}cc}$: $M=2m_{b}+2m_{c}+m_{u}+5C/2 +β_{x_λ}(x_λ+c_{0x_λ})^{2/3}$… ▽ More Systematic investigations of four series of Regge trajectories for quadruply heavy pentaquarks are still lacking. Using the diquark and triquark Regge trajectory relations, we propose the Regge trajectory relations for the quadruply heavy pentaquark ${bb\bar{u}cc}$: $M=2m_{b}+2m_{c}+m_{u}+5C/2 +β_{x_λ}(x_λ+c_{0x_λ})^{2/3}$$+β_{x_{ρ_1}}(x_{ρ_1}+c_{0x_{ρ_1}})^{2/3}+β_{x_{ρ_2}}\sqrt{x_{ρ_2}+c_{0x_{ρ_2}}} +β_{x_σ}(x_σ+c_{0x_σ})^{2/3}$. Four series of Regge trajectories, namely the $λ$-, $ρ_1$-, $ρ_2$-, and $σ$-trajectories, are investigated. We demonstrate that accounting for the internal structure and substructure of pentaquarks is indispensable for constructing the $ρ_1$-, $ρ_2$-, and $σ$-trajectories; without such structural considerations, functional form and trajectory parameters can only be obtained via pure fitting against theoretical or experimental data. We further prove that the Regge trajectories of diquark 1, triquark, and diquark 2 (emdedded within the triquark) do not correspond one-to-one to the $ρ_1$-, $ρ_2$-, and $σ$-trajectories. Nevertheless, these trajectories govern the behaviors of the respective $ρ_1$-, $ρ_2$-, and $σ$-trajectories. For both configurations $(bb)(\bar{u}(cc))$ and $(cc)(\bar{u}(bb))$, the $λ$-, $ρ_1$-, and $σ$-trajectories exhibit behavior of $M{\sim}x^{2/3}$ ($x=n_{r_1},n_{r_3},l_1,l_3,N_{r},L$), whereas the $ρ_2$-trajectories exhibit behavior of $M{\sim}\sqrt{x}$ ($x=n_{r_2},\,l_2$). The functional behavior of Regge trajectories for diquarks and triquark offers guidance for fitting the pentaquark Regge trajectories. Additionally, we provide rough estimates for spin-averaged masses of the $λ$-, $ρ_1$-, $ρ_2$-, and $σ$-excited states. △ Less

Submitted 12 July, 2026; originally announced July 2026.

Comments: 11 pages, 5 figures, 7 tables

Production of hidden-charm molecular candidates in $ψ(4660)$ decays

Authors: Xiao-Yun Wang, Ya-Rong Wang, Shi-Dong Liu, Xiao-Hai Liu, Gang Li

Abstract: We investigate the production of several hidden-charm exotic candidates, including $Z_c(3900)$, $Z_c(4020)$, $Z_{cs}(3985)$, and $Z_2(4250)$, in $ψ(4660)$ decays under the assumption that these states are predominantly hadronic molecules. Treating $ψ(4660)$ as a conventional $ψ(5S)$ charmonium state, the production mechanisms are described through intermediate charmed-meson triangle loops, with it… ▽ More We investigate the production of several hidden-charm exotic candidates, including $Z_c(3900)$, $Z_c(4020)$, $Z_{cs}(3985)$, and $Z_2(4250)$, in $ψ(4660)$ decays under the assumption that these states are predominantly hadronic molecules. Treating $ψ(4660)$ as a conventional $ψ(5S)$ charmonium state, the production mechanisms are described through intermediate charmed-meson triangle loops, with its couplings to charmed-meson pairs estimated within the quark model. A systematic analysis of the processes $ψ(4660)\to Z_c(3900)π$, $ψ(4660)\to Z_c(4020)π$, $ψ(4660)\to Z_{cs}(3985)K$, and $ψ(4660)\to Z_2(4250)π$ is performed within a unified framework. The predicted branching fractions are found to be of the order of $10^{-2}$, $10^{-4}$, $10^{-3}$, and $10^{-6}$, respectively, exhibiting only a mild dependence on the cutoff parameter. We further find that the contributions from the $SHH$ intermediate loops dominate over those from the $THH$ and $HHH$ loops in most channels. The sizable production rates obtained in this work indicate that $ψ(4660)$ decays provide a promising platform for probing the molecular nature of charged hidden-charm exotic states and testing their underlying production mechanisms. △ Less

Submitted 10 July, 2026; originally announced July 2026.

Comments: 13 pages, 8 figures

AMFlow 2.0: significant algorithmic and software improvements for Feynman integral evaluation

Authors: Rui-Jun Huang, Xiao Liu, Yan-Qing Ma

Abstract: We present significant improvements to the AMFlow package for the numerical computation of dimensionally regularized Feynman integrals. Several new features are introduced to reduce computational cost, including an alternative recursion mode, a high-performance differential equation solver, support for state-of-the-art integration-by-parts reducers and other useful improvements. We benchmark the n… ▽ More We present significant improvements to the AMFlow package for the numerical computation of dimensionally regularized Feynman integrals. Several new features are introduced to reduce computational cost, including an alternative recursion mode, a high-performance differential equation solver, support for state-of-the-art integration-by-parts reducers and other useful improvements. We benchmark the new version on a three-loop five-point topology and find that both the symbolic and numerical performance are significantly improved. △ Less

Submitted 9 July, 2026; originally announced July 2026.

Comments: 17 pages, 1 figure

Lepton mixing from the $Δ(96)$ Modular Littlest Seesaw

Authors: Hai-Zhi Hao, Li-Na Yan, Xiang-Gan Liu, Cai-Chang Li

Abstract: We perform the first comprehensive and model independent study of Modular Littlest Seesaw models based on the finite modular group $Δ(96)$. We construct the vector-valued modular forms (VVMFs) for all irreducible representations of modular $Δ(96)$, classify the inequivalent symmetry-preserving fixed points, and derive the corresponding alignments of the low-weight and next-to-lowest-weight triplet… ▽ More We perform the first comprehensive and model independent study of Modular Littlest Seesaw models based on the finite modular group $Δ(96)$. We construct the vector-valued modular forms (VVMFs) for all irreducible representations of modular $Δ(96)$, classify the inequivalent symmetry-preserving fixed points, and derive the corresponding alignments of the low-weight and next-to-lowest-weight triplet VVMFs. These results allow an exhaustive scan over the residual symmetries in the charged lepton, atmospheric neutrino, and solar neutrino sectors. We identify 35 phenomenologically viable and inequivalent breaking patterns, including 21 with normal ordering and 14 with inverted ordering. The resulting Dirac neutrino mass matrices go beyond the conventional CSD$(n)$ structure, yielding new fixed PMNS columns and novel correlations among the lepton mixing parameters beyond the TM$_1$ paradigm. The viable models are highly predictive, giving narrow ranges for neutrino masses, mixing parameters and CP phases, and can be stringently tested by upcoming experiments such as JUNO, DUNE and T2HK. △ Less

Submitted 8 July, 2026; originally announced July 2026.

Comments: 53 pages, 6 figures

$λ$, $ρ$, and $σ$ Regge trajectories for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ in the triquark-antitriquark picture

Authors: Xin-Ru Liu, Qi Liu, Jiao-Kai Chen

Abstract: We propose Regge trajectory relations for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ by using the Regge trajectory relations for diquarks and triquarks. With these newly derived relations, we investigate five series of hexaquark Regge trajectories: the $λ$-, $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories. We demonstrate that, apart from the simplest $λ_1$-trajectories, the $ρ_1$-, $ρ_2$-,… ▽ More We propose Regge trajectory relations for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ by using the Regge trajectory relations for diquarks and triquarks. With these newly derived relations, we investigate five series of hexaquark Regge trajectories: the $λ$-, $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories. We demonstrate that, apart from the simplest $λ_1$-trajectories, the $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories cannot be constructed by merely mimicking the meson Regge trajectories, since mesons possess no internal substructures. To derive these trajectories, one must account for the structure and internal substructure of hexaquark. Without this structural information, the $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories could only be obtained through direct fits to available theoretical predictions or future experimental data. We demonstrate that the $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories for the hexaquark do not correspond respectively to the Regge trajectories for the triquark, antitriquark, diquark, and antidiquark. Nevertheless, their behaviors match those of the Regge trajectories for the triquark $(\bar{u}(cc))$, the antitriquark $(b(\bar{b}\bar{b}))$, the diquark $(cc)$, and the antidiquark $(\bar{b}\bar{b})$, in that respective order. Furthermore, we present rough mass estimates for the excited states corresponding to the $λ$-, $ρ_1$-, $ρ_2$-, $σ_1$-, and $σ_2$-trajectories. △ Less

Submitted 28 June, 2026; originally announced June 2026.

Comments: 13 pages, 5 figures, 9 tables

Revisiting identified-particle $p_{\mathrm{T}}$ spectra using the Boltzmann-Gibbs blast-wave model in a Bayesian inference framework

Authors: Z. Xie, W. Z. Li, J. Q. Tao, H. Zheng, W. C. Zhang, W. Dai, L. L. Zhu, X. Q. Liu, D. M. Zhou, B. H. Sa

Abstract: We perform a Bayesian analysis of transverse momentum ($p_{\mathrm{T}}$) spectra of identified particles, i.e., pions, kaons, and protons, at midrapidity in Au+Au collisions and Pb+Pb collisions using the Boltzmann-Gibbs blast-wave (BGBW) model. We investigate whether it is possible to simultaneously describe the $p_{\mathrm{T}}$ spectra of identified particles without imposing the particle specie… ▽ More We perform a Bayesian analysis of transverse momentum ($p_{\mathrm{T}}$) spectra of identified particles, i.e., pions, kaons, and protons, at midrapidity in Au+Au collisions and Pb+Pb collisions using the Boltzmann-Gibbs blast-wave (BGBW) model. We investigate whether it is possible to simultaneously describe the $p_{\mathrm{T}}$ spectra of identified particles without imposing the particle species-dependent $p_{\mathrm{T}}$ fit ranges -- a practice that was followed in conventional blast-wave model studies to achieve reasonable simultaneous fits. Using Bayesian analysis, our results indicate that a simultaneous description of the $p_{\mathrm{T}}$ spectra of pions, kaons, and protons is feasible without imposing the particle species-dependent $p_{\mathrm{T}}$ fit ranges, for Au+Au collisions up to the available data ($\sim$2 GeV/c) and for Pb+Pb collisions up to 3 GeV/c. The extracted parameters remain broadly consistent with those obtained from conventional BGBW simultaneous fits, while the extension of the fit range leads to moderate changes in some parameters. Furthermore, Bayesian analysis yields well-constrained posterior distributions for the kinetic freeze-out temperature $T_{kin}$, the average transverse flow velocity $\langle β_{\mathrm{T}}\rangle$, and the exponent of the velocity profile $n$ and shows their correlations transparently. We suggest that the BGBW model in a Bayesian inference framework proposed can be applied in future data analyses to simultaneously describe the $p_{\mathrm{T}}$ spectra of identified particles and extract the relevant information about the collision system. △ Less

Submitted 28 June, 2026; originally announced June 2026.

Comments: 9 pages, 3 figures

Fermion mass relations in one-parameter modular models

Authors: Salvador Centelles Chuliá, Xueqi Li, Xiang-Gan Liu, Omar Medina, J. T. Penedo

Abstract: Modular flavour symmetries provide a possible organizing principle for the Standard Model Yukawa sector, by replacing generic couplings with a potentially small number of modular forms controlled by a single complex modulus. We study the extreme limit of this idea: \acp{OPM}, in which each charged-fermion mass matrix is fixed by a single modular invariant contraction. We develop a systematic metho… ▽ More Modular flavour symmetries provide a possible organizing principle for the Standard Model Yukawa sector, by replacing generic couplings with a potentially small number of modular forms controlled by a single complex modulus. We study the extreme limit of this idea: \acp{OPM}, in which each charged-fermion mass matrix is fixed by a single modular invariant contraction. We develop a systematic method to construct such models, showing that the \ac{OPM} requirement is already highly constraining at the level of possible fermion hierarchies. In a concrete realization, the charged-lepton and down-quark sectors are controlled by the common modulus, leading to exact mass relations at the flavour scale, \[ m_s^5 = 2\sqrt{2}\,m_d^3m_b^2, \qquad m_μ^3 = \sqrt{2}\,m_e m_τ^2, \qquad m_s^2m_τ= \sqrt{2}\,m_e m_b^2. \] We show that, once renormalization-group evolution and selective supersymmetric threshold effects are included, these high-scale relations can be made compatible with low-energy charged-fermion data. Our results provide a working proof of principle for \acp{OPM} and point towards a possible route to the flavour puzzle through highly △ Less

Submitted 23 June, 2026; originally announced June 2026.

Comments: 23 pages, 5 figures, 4 tables

Production of high-orbital kaon excited states in the $K^{-}p$ reaction

Authors: Ting-Yan Li, Zi-Yue Bai, Xiang Liu

Abstract: In this work, a systematic investigation of the production of high-orbital-excitation kaons in $K^{-}p$ reactions is carried out within an effective Lagrangian approach. The relevant $t$-channel processes are constructed, and the model is calibrated using a single adjustable parameter determined from existing experimental data. With this parameter, the measured production cross sections for the… ▽ More In this work, a systematic investigation of the production of high-orbital-excitation kaons in $K^{-}p$ reactions is carried out within an effective Lagrangian approach. The relevant $t$-channel processes are constructed, and the model is calibrated using a single adjustable parameter determined from existing experimental data. With this parameter, the measured production cross sections for the $K_3^*(1780)$, $K_2(1820)$, $K_2(1770)$ and $K_4^*(2045)$ states are successfully reproduced. Employing the same framework, the production cross sections for other high-orbital kaons are predicted. The results indicate that these states possess sizable cross sections and exhibit characteristically forward-peaked angular distributions, which is a typical feature of $t$-channel exchange, highlighting their great potential for observation in future experiments. △ Less

Submitted 16 June, 2026; v1 submitted 14 June, 2026; originally announced June 2026.

Comments: 15 pages, 8 figures and 2 tables. More references added and some typos corrected

Investigation of fully heavy tetraquark within chiral quark model

Authors: Yuheng Wu, Xuejie Liu, Ye Yan, Yue Tan, Qi Huang, Hongxia Huang, Jialun Ping

Abstract: In the framework of the Chiral quark model (ChQM), we investigate the fully charmed and fully bottomed tetraquark with $J^{PC}=2^{++}$ including two structures: $Q\bar{Q}-Q\bar{Q}$ and $QQ-\bar{Q}\bar{Q}$. The bound-state calculation shows that there is no bound state in either $cc\bar{c}\bar{c}$ or $bb\bar{b}\bar{b}$ systems. However, by using the real-scaling method, some resonance states are ob… ▽ More In the framework of the Chiral quark model (ChQM), we investigate the fully charmed and fully bottomed tetraquark with $J^{PC}=2^{++}$ including two structures: $Q\bar{Q}-Q\bar{Q}$ and $QQ-\bar{Q}\bar{Q}$. The bound-state calculation shows that there is no bound state in either $cc\bar{c}\bar{c}$ or $bb\bar{b}\bar{b}$ systems. However, by using the real-scaling method, some resonance states are obtained. For the $cc\bar{c}\bar{c}$ system, when the channel-coupling includes only three $S$-wave channels, two resonant states are obtained: one with a mass around $7002$ MeV and decay width near $54$ MeV, and another with a mass around $7227$ MeV and a decay width near $66$ MeV. The former can be regarded as a candidate for the $X(6900)$, and the latter can be considered as a candidate for the $X(7200)$. Upon adding the $χ_{c0}χ_{c2}$, $χ_{c1}χ_{c1}$, $χ_{c1}χ_{c2}$, $χ_{c2}χ_{c2}$ channels, both resonant states still remain. For the $bb\bar{b}\bar{b}$ system, only one resonant state is obtained, regardless of whether the four channels composition of the excited mesons are included or excluded. The mass and width of this resonant state are around $19743$ MeV and $67$ MeV, respectively. We suggest that future experiments search for the possible resonance state in the invariant mass spectrum of $ΥΥ$ or $ΥΥ(2S)$. △ Less

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

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

Final-state rescattering mechanism of the $Δ(1232)^{++}$ production in $Λ^+_c \to K^- π^+ p$ decay

Authors: Zu-Xin Cai, Cheng Chen, Si-Wei Liu, Xiang Wei, Gang Li, Xiao-Hai Liu, Ju-Jun Xie

Abstract: We investigate the production of the $Δ(1232)^{++}$ resonance in the charmed baryon weak decay $Λ^+_c \to K^- π^+ p$, focusing on the $π^+ p$ final-state rescattering mechanism. The direct $W^+$ exchange diagram is expected to be suppressed, hence we adopt the $W^+$ internal emission process $Λ^+_c \to p \bar K^{*0}(892)$ followed by the subsequent decay $\bar{K}^{*0} \to K^- π^+$ as the dominant… ▽ More We investigate the production of the $Δ(1232)^{++}$ resonance in the charmed baryon weak decay $Λ^+_c \to K^- π^+ p$, focusing on the $π^+ p$ final-state rescattering mechanism. The direct $W^+$ exchange diagram is expected to be suppressed, hence we adopt the $W^+$ internal emission process $Λ^+_c \to p \bar K^{*0}(892)$ followed by the subsequent decay $\bar{K}^{*0} \to K^- π^+$ as the dominant source of the final state particles. The $Δ(1232)^{++}$ resonance is then generated via $π^+ p$ rescattering within a triangle loop mechanism. Our calculations incorporate both the tree-level $\bar K^{*0}(892)$ and the dynamically generated $\bar{K}^*_0(700)$ state arising from the $S$-wave $K π$ final state interaction. We find that our theoretical results can reproduce the bump and peak structures in the $K^- π^+$ invariant mass distributions for the $\bar{K}^*_0(700)$ and $\bar{K}^{*0}(892)$, respectively. Meanwhile, the peak for the $Δ(1232)^{++}$ in the $π^+ p$ invariant mass distributions is also well described. The $Δ(1232)^{++}$ signal naturally emerges from rescattering effects, and adopting the pole parameters of $Δ(1232)$ resonance yields an improved description of the experimental data. In addition, we obtain a branching fraction ratio $\mathcal{B}[Λ_c^+ \to Δ(1232)^{++} K^-] / \mathcal{B}[Λ_c^+ \to p \bar{K}^{*0}(892)] \approx 0.5$, which is lower than the experimentally measured value. This discrepancy suggests that interference effects are likely significant in this decay process. Future high-precision measurements will further verify the proposed rescattering mechanism. △ Less

Submitted 2 June, 2026; originally announced June 2026.

Comments: 9 pages, 5 figures

Prediction of doubly-charm hadronic molecules with double strange quarks

Authors: Fu-Lai Wang, Xiang Liu

Abstract: In this work, we investigate whether the $T$-doublet charmed-strange mesons and their antiparticles can form hidden-charm hidden-strangeness molecular tetraquarks by applying the one-boson-exchange model. We identify $D_{s1}\bar D_{s1}$ ($J^{PC}=0^{++},\,1^{+-},\,2^{++}$), $D_{s1}\bar D_{s2}^*$ ($J^{PC}=1^{+\pm},\,2^{+\pm},\,3^{+\pm}$), and $D_{s2}^*\bar D_{s2}^*$ (… ▽ More In this work, we investigate whether the $T$-doublet charmed-strange mesons and their antiparticles can form hidden-charm hidden-strangeness molecular tetraquarks by applying the one-boson-exchange model. We identify $D_{s1}\bar D_{s1}$ ($J^{PC}=0^{++},\,1^{+-},\,2^{++}$), $D_{s1}\bar D_{s2}^*$ ($J^{PC}=1^{+\pm},\,2^{+\pm},\,3^{+\pm}$), and $D_{s2}^*\bar D_{s2}^*$ ($J^{PC}=0^{++},\,1^{+-},\,2^{++},\,3^{+-},\,4^{++}$) as promising hidden-charm hidden-strangeness molecular tetraquark candidates. Notably, the $D_{s1}\bar D_{s2}^*$ state with $J^{PC}=2^{+-}$ possesses exotic spin-parity quantum numbers forbidden for conventional mesons, providing a clean experimental signature for exotic hadrons. Moreover, the $D_{s2}^*\bar D_{s2}^*$ state with $J^{PC}=4^{++}$ is a rare high-spin hadronic molecule. We then extend the same framework to discuss the binding properties of the $T_s T_s$ systems and construct the mass spectrum of corresponding doubly-charm doubly-strangeness molecular tetraquarks. The promising candidates are $D_{s1}D_{s1}$ ($J^P=2^+$), $D_{s1}D_{s2}^*$ ($J^P=3^+$), and $D_{s2}^*D_{s2}^*$ ($J^P=4^+$), all of which are absolutely flavor-exotic. We encourage experimental searches for these predicted hadronic molecules, which would be a crucial step toward establishing doubly-charm molecular tetraquarks with strangeness $S=0$ or $2$. △ Less

Submitted 1 June, 2026; originally announced June 2026.

Comments: 14 pages, 2 figures, and 5 tables

Sivers Tomography from Charge and Angle Only

Authors: Haotian Cao, Xiaohui Liu, Frank Petriello

Abstract: We propose a one-point charge-correlator (OPCC) probe of the Sivers effect in back-to-back deep-inelastic scattering. This measurement uses only the signs and directions of charged tracks, with no calorimetric or particle-identification information required. The observable weights the final state by its electric charge and measures the azimuthal correlation between the charge flow and the transver… ▽ More We propose a one-point charge-correlator (OPCC) probe of the Sivers effect in back-to-back deep-inelastic scattering. This measurement uses only the signs and directions of charged tracks, with no calorimetric or particle-identification information required. The observable weights the final state by its electric charge and measures the azimuthal correlation between the charge flow and the transverse spin of the proton. This probe is shown to be IRC finite and admits a factorization involving the usual Sivers distribution and a perturbatively calculable charge-weighted jet function for small transverse seperation $b\ll Λ_{\rm QCD}^{-1}$, with no reliance on non-perturbative fragmentation functions or track functions due to charge conservation. We validate the factorization against the full fixed-order QCD and present resummed predictions at N\(^3\)LL accuracy for the unpolarized distribution and N\(^2\)LL for the Sivers asymmetry. The OPCC provides a theoretically clean and simple experimental measurement, and establishes a charge-and-angle measurement paradigm for spin physics at a future Electron-Ion Collider. △ Less

Submitted 14 May, 2026; originally announced May 2026.

Comments: 5 pages, 4 figures

Spin-flavor entanglement in $Λ_b \to ΛD$ and weak phase extraction

Authors: Yong Du, Chao-Qiang Geng, Xiao-Gang He, Chia-Wei Liu, Sheng-Lin Liu, Xin-Yi Liu

Abstract: We identify a new spin-flavor entanglement structure in $Λ_b\toΛD$ decays, formed by the correlation between the $Λ$ spin and the $D$ flavor states ($D=D^0,\overline D^0,D_1,D_2$). The entanglement information is encoded in the decay rates and Lee-Yang parameters of the four neutral-$D$ modes. We then show that the same spin-flavor structure provides a new method to determine the weak phase $γ$, a… ▽ More We identify a new spin-flavor entanglement structure in $Λ_b\toΛD$ decays, formed by the correlation between the $Λ$ spin and the $D$ flavor states ($D=D^0,\overline D^0,D_1,D_2$). The entanglement information is encoded in the decay rates and Lee-Yang parameters of the four neutral-$D$ modes. We then show that the same spin-flavor structure provides a new method to determine the weak phase $γ$, a key angle of the Cabibbo-Kobayashi-Maskawa unitarity triangle. We find that the experimental uncertainty scales as $σ_γ\propto 1/{\cal C}$, where ${\cal C}$ is the Wootters concurrence, thereby quantitatively relating the precision of the weak-phase extraction to the amount of spin-flavor entanglement. △ Less

Submitted 10 May, 2026; originally announced May 2026.

Comments: 5 pages, 3 figures

Probing the nature of $D_1 K$ and $D_2 K$ molecules through $D_s^{(*)}ππ$ and $D_{s0(s1)}π$ decays

Authors: Xing-Meng Zhao, Liu-Lin Wang, Ying-Bo He, Xiao-Yun Wang, Xiao-Hai Liu

Abstract: We study the two- and three-body decays of the $I=0$ $D_1K$ and $D_2K$ molecular states $T_{c\bar{s}1}^*$ and $T_{c\bar{s}2}^*$ into $D_s^{(*)}$ mesons and pions. Triangle singularities produce narrow peaks in the $D_s^*π$ and $D_sπ$ invariant mass spectra near the $D^*K$ and $DK$ thresholds. The isospin-violating two-body decays $T_{c\bar{s}1}^*\to D_{s1}(2460)π^0$,… ▽ More We study the two- and three-body decays of the $I=0$ $D_1K$ and $D_2K$ molecular states $T_{c\bar{s}1}^*$ and $T_{c\bar{s}2}^*$ into $D_s^{(*)}$ mesons and pions. Triangle singularities produce narrow peaks in the $D_s^*π$ and $D_sπ$ invariant mass spectra near the $D^*K$ and $DK$ thresholds. The isospin-violating two-body decays $T_{c\bar{s}1}^*\to D_{s1}(2460)π^0$, $T_{c\bar{s}2}^*\to D_{s1}(2460)π^0$, and $T_{c\bar{s}2}^*\to D_{s0}^*(2317)π^0$ exhibit large partial widths, reflecting the strong couplings inherent to molecular states. These predictions, obtained within heavy hadron chiral perturbation theory and the chiral unitary approach, provide complementary signatures for identifying $D_1K$ and $D_2K$ molecules at experiments. △ Less

Submitted 10 May, 2026; originally announced May 2026.

Comments: 12 pages, 13 figures

Exponentially improved quantum simulation of scalar QFT

Authors: Qing-Hong Cao, Ying-Ying Li, Xiaohui Liu, Liang-Qi Zhang, Ke Zhao

Abstract: Quantum simulations of scalar quantum field theories (QFT) provide important benchmarks for demonstrating quantum advantage. We revisit digitization in the occupation basis, which is typically hindered by unfavorable circuit depth scaling. We present an approach that achieves exponential reductions in circuit depth and significantly mitigates Trotter errors by diagonalizing field operators prior t… ▽ More Quantum simulations of scalar quantum field theories (QFT) provide important benchmarks for demonstrating quantum advantage. We revisit digitization in the occupation basis, which is typically hindered by unfavorable circuit depth scaling. We present an approach that achieves exponential reductions in circuit depth and significantly mitigates Trotter errors by diagonalizing field operators prior to their decomposition into Pauli strings. Focusing on a scalar QFT in 2+1 dimensions, we show that this method substantially reduces circuit depth and CNOT gate counts for time evolution. Using the Lorentzian energy-energy correlator as a benchmark observable, we find parameter regimes in which occupation-basis digitization converges more rapidly with respect to local truncation than the amplitude-basis approach of Jordan, Lee, and Preskill. These results provide both algorithmic advances and phenomenological benchmarks for studies of light-ray observables on near-term quantum devices. △ Less

Submitted 28 April, 2026; originally announced April 2026.

Comments: 11 pages,5 figures,6 tables

Revisiting Turner Window Axions: The Untapped Potential of NaI Dark Matter Detectors

Authors: W. C. Haxton, Xing Liu, Anupam Ray, Evan Rule

Abstract: The "Turner window" corresponds to axions with masses $\gtrsim$ 1 eV that have sufficiently strong couplings to matter to evade limits from the cooling of SN1987A. This window, through which the trajectories for the KSVZ and DFSZ QCD axions run, has been thought to be largely closed because of (1) the floor established by SN1987A cooling, (2) the absence of SN1987A-associated photons in the Kamiok… ▽ More The "Turner window" corresponds to axions with masses $\gtrsim$ 1 eV that have sufficiently strong couplings to matter to evade limits from the cooling of SN1987A. This window, through which the trajectories for the KSVZ and DFSZ QCD axions run, has been thought to be largely closed because of (1) the floor established by SN1987A cooling, (2) the absence of SN1987A-associated photons in the Kamioka II detector, and (3) the limit on neutrons produced by solar axions in the Sudbury Neutrino Observatory. We show that a more complete treatment of the axion opacity in SN1987A, significantly weakens (2). Consequently, for axion or axion-like particles with hadronic couplings, $g_{ann}$ and $g_{app}$, significant regions within the Turner window now become viable. We describe a new opportunity to constrain such hadronically coupled axions via their resonant absorption in NaI detectors. The source is the Milky Way's carbon-burning stars -- the progenitors of ONeMg white dwarfs as well as electron-capture and core-collapse supernovae -- which synthesize significant quantities of $^{23}$Na, keeping it at temperatures $\sim 10^9$K for periods up to tens of thousands of years. $^{23}$Na acts as a thermal pump to convert stellar energy into axions, which arrive at the Earth as a thermally broadened line at 440 keV. These axions can be detected via resonant absorption in NaI, with the needed detector arrays already in place, developed by DAMA/LIBRA and other collaborations to search for the elastic scattering of light WIMPs. In axion detection, NaI serves as both the target, producing $γ$'s following resonant absorption, and the detector for those $γ$'s. With current array masses and backgrounds, we find that the coupling range $|g_{app}| \sim 10^{-6.5}$--$10^{-2}$ can be covered after two years of data, including QCD axions with $m_a \gtrsim 10$ eV. △ Less

Submitted 28 April, 2026; originally announced April 2026.

Comments: v1: 23 pages, 12 figures

Report number: N3AS-26-007, INT-PUB-26-016, LA-UR-26-21773

Deciphering the universal scaling of particle transverse momentum spectra in heavy-ion collisions

Authors: Xi-Yao Guo, Hua Zheng, Wenchao Zhang, Li-Lin Zhu, Xing-Quan Liu, Zhi-Guang Tan, Dai-Mei Zhou, Ben-Hao Sa

Abstract: We systematically investigate the scaling properties of the transverse momentum spectra for pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, as well as in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV, across different centrality classes, using experimental data from the collaborations at the Relativistic Heavy Ion Collider (RHIC).… ▽ More We systematically investigate the scaling properties of the transverse momentum spectra for pions, kaons, and protons in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, as well as in U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV, across different centrality classes, using experimental data from the collaborations at the Relativistic Heavy Ion Collider (RHIC). Universal scaling emerges when the particle transverse momentum spectra are scaled by global physical quantities, i.e., the average total particle multiplicity and mean transverse momentum, confirming recent scaling findings from the data at the Large Hadron Collider (LHC) by the ExTrEMe collaboration. The scaling behavior breaks down in the high $p_{T}$ region and in peripheral collisions. We provide a natural explanation for these observations by invoking the Cooper-Frye formula, which is used for hadronization in hydrodynamics. Furthermore, we demonstrate the equivalence between the scaling found by the ExTrEMe collaboration and the Hwa-Yang scaling which was proposed two decades ago. △ Less

Submitted 19 April, 2026; originally announced April 2026.

Comments: 11 pages, 5 figures

Proposed mixing between $2P$ and $1F$ wave charmonia

Authors: Peng-Yu Sun, Tian-Le Gao, Zi-Long Man, Xiang Liu

Abstract: We investigate $2P$-$1F$ mixing in charmonium, focusing on the close-in-mass $χ_{c2}(2P)$ and $χ_{c2}(1F)$ states. The conventional tensor force yields negligible mixing, motivating the inclusion of coupled-channel effects. Our unquenched calculation reveals sizable mixing angles of $7.5^\circ$ and $15.4^\circ$. We predict the corresponding two-photon and two-gluon decay widths as key observables… ▽ More We investigate $2P$-$1F$ mixing in charmonium, focusing on the close-in-mass $χ_{c2}(2P)$ and $χ_{c2}(1F)$ states. The conventional tensor force yields negligible mixing, motivating the inclusion of coupled-channel effects. Our unquenched calculation reveals sizable mixing angles of $7.5^\circ$ and $15.4^\circ$. We predict the corresponding two-photon and two-gluon decay widths as key observables for experimental verification. Additionally, we discuss the production of these two $2P$-$1F$ mixed states of charmonium via $γγ$ fusion. Current data are insufficient to determine the mixing, highlighting the need for precise future measurements to resolve this aspect of charmonium spectroscopy. △ Less

Submitted 13 July, 2026; v1 submitted 18 April, 2026; originally announced April 2026.

Comments: 13 pages, 2 figures, 5 tables, accepted by Phys. Rev. D

Journal ref: Phys. Rev. D 114, 034011 (2026)

Precision QCD with the Electron-Ion Collider

Authors: C. Alexandrou, M. Arratia, E. C. Aschenauer, A. Avkhadiev, P. V. Balachandran, V. Bertone, I. Borsa, M. Cerutti, X. Chu, W. Cosyn, D. de Florian, A. Dumitru, M. Engelhardt, R. Fatemi, S. Forte, Y. Fu, L. Gamberg, H. Gao, T. Gehrmann, A. Gehrmann-De Ridder, Y. Go, Y. Guo, Y. Hatta, J. Haug, T. J. Hobbs , et al. (44 additional authors not shown)

Abstract: This document summarizes the discussions at the program "Precision QCD with the Electron Ion Collider", held from May to June 2025 at the Institute for Nuclear Theory (INT) at the University of Washington. The program was co-sponsored by the INT and by the Center for Frontiers in Nuclear Science (CFNS, Stony Brook University). Over its five-week duration it brought together about 70 theorists, exp… ▽ More This document summarizes the discussions at the program "Precision QCD with the Electron Ion Collider", held from May to June 2025 at the Institute for Nuclear Theory (INT) at the University of Washington. The program was co-sponsored by the INT and by the Center for Frontiers in Nuclear Science (CFNS, Stony Brook University). Over its five-week duration it brought together about 70 theorists, experimentalists and computer scientists all interested in the physics program at the future Electron Ion Collider in preparation at Brookhaven National Laboratory. Key topics at the program were: higher-order perturbative-QCD calculations and techniques; nuclear structure and tomography; comparisons of phenomenological and lattice determinations of parton distribution functions; identification of signature observables for saturated gluons; assessment of the importance of AI techniques for EIC studies and detector development. △ Less

Submitted 6 April, 2026; originally announced April 2026.

Comments: Summary of the 2025 joint CFNS-INT program: Precision QCD with the Electron-Ion Collider. 165 pages, 35 figures

Report number: INT-PUB-26-011

Observation of $Λ^+_c\to nπ^+η$ and search for $Λ^+_c\to na_0(980)^+$

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. (722 additional authors not shown)

Abstract: By analysing 6.1 ${\rm fb}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\rm GeV$ with the BESIII detector at the BEPCII collider, we observe the decay $Λ_c^+\to nπ^+η$ for the first time with a statistical significance of $9.5σ$. The ratio of branching fractions $\mathcal{B}(Λ_c^+\to nπ^+η)/\mathcal{B}(Λ_c^+\to Λπ^+η)$ is measured to be… ▽ More By analysing 6.1 ${\rm fb}^{-1}$ of data collected at center-of-mass energies between $\sqrt{s}=4.600$ and 4.843 $\rm GeV$ with the BESIII detector at the BEPCII collider, we observe the decay $Λ_c^+\to nπ^+η$ for the first time with a statistical significance of $9.5σ$. The ratio of branching fractions $\mathcal{B}(Λ_c^+\to nπ^+η)/\mathcal{B}(Λ_c^+\to Λπ^+η)$ is measured to be $0.155\pm0.031_{\rm stat.}\pm0.012_{\rm syst.}$ Taking the world average of $\mathcal{B}(Λ_c^+\to Λπ^+η)$ as reference, the absolute branching fraction is calculated to be $\mathcal{B}(Λ_c^+\to nπ^+η)=(2.94\pm0.59_{\rm stat.}\pm0.23_{\rm syst.}\pm0.13_{\rm ref.})\times10^{-3}$. The intermediate process $Λ_c^+\to na_0(980)^+$ is also searched for in the $π^+η$ invariant mass spectrum. Since no significant signal is found, the upper limit on $\mathcal{B}(Λ_c^+\to na_0(980)^+)\times\mathcal{B}(a_0(980)^+\toπ^+η)$ is set to $8.4\times10^{-4}$ at 90\% confidence level. A sophisticated deep learning approach using a Transformer-based architecture is employed to distinguish signals from prevalent hadronic backgrounds, complemented by thorough validation and systematic uncertainty quantification. △ Less

Submitted 7 August, 2026; v1 submitted 30 March, 2026; originally announced March 2026.

Comments: 26 pages, 6 figures

Journal ref: JHEP 08 (2026), 009

$B_{(s)}$ to Light Axial Vector Meson Form Factors via LCSR in HQEFT with Applications to Semileptonic Decays

Authors: Ya-Bing Zuo, Ming-Ge Li, Shi-Yu Liang, Wan-Ting Liu, Xin-Su Liu

Abstract: In the present work, the form factors of $B_{(s)}$ to light P-wave axial vector mesons are calculated via the light cone sum rules (LCSR) in the framework of heavy quark effective field theory (HQEFT). Firstly, the expressions of form factors in terms of the light cone distribution amplitudes (DAs) of axial vector mesons are derived via the LCSR at the leading order of heavy quark expansion. It is… ▽ More In the present work, the form factors of $B_{(s)}$ to light P-wave axial vector mesons are calculated via the light cone sum rules (LCSR) in the framework of heavy quark effective field theory (HQEFT). Firstly, the expressions of form factors in terms of the light cone distribution amplitudes (DAs) of axial vector mesons are derived via the LCSR at the leading order of heavy quark expansion. It is found that the penguin type form factors can be obtained directly from the corresponding semileptonic ones, which is similar to the case of S-wave mesons. Considering the light axial vector meson DAs to twist-3, we give the numerical results of form factors systematically. As applications, we investigate the branching ratios, longitudinal polarization fractions and forward-backward asymmetries of relevant semileptonic decays induced by charged current. Our results may be tested by more precise experiments in the future. △ Less

Submitted 26 March, 2026; originally announced March 2026.

Comments: 54 pages, 37 figures, 18 tables

Five-flavor molecular pentaquarks in the $Ξ_b^{(\prime,\,*)} \bar D^{(*)}$ and $Ξ_c^{(\prime,\,*)} B^{(*)}$ systems

Authors: Fu-Lai Wang, Xiang Liu

Abstract: The discovery of hidden-charm pentaquarks and open-flavor tetraquarks motivates the search for even more exotic hadron configurations. In this work, we investigate genuinely exotic molecular pentaquark candidates comprising five different flavors, focusing on the $Ξ_b^{(\prime,\,*)} \bar D^{(*)}$ and $Ξ_c^{(\prime,\,*)} B^{(*)}$ systems. Employing the one-boson-exchange model with the $S$-$D$ wave… ▽ More The discovery of hidden-charm pentaquarks and open-flavor tetraquarks motivates the search for even more exotic hadron configurations. In this work, we investigate genuinely exotic molecular pentaquark candidates comprising five different flavors, focusing on the $Ξ_b^{(\prime,\,*)} \bar D^{(*)}$ and $Ξ_c^{(\prime,\,*)} B^{(*)}$ systems. Employing the one-boson-exchange model with the $S$-$D$ wave mixing and coupled-channel dynamics, we identify the most promising molecular pentaquark candidates comprising five different flavors. These include the $Ξ_b \bar D$, $Ξ_b^{\prime} \bar D$, $Ξ_c B$, and $Ξ_c^{\prime} B$ states with $I(J^P)=0(1/2^-)$, the $Ξ_b \bar D^{*}$, $Ξ_b^{\prime} \bar D^{*}$, $Ξ_c B^{*}$, and $Ξ_c^{\prime} B^{*}$ states with $I(J^P)=0(1/2^-,\,3/2^-)$, the $Ξ_b^{*} \bar D$ and $Ξ_c^{*} B$ states with $I(J^P)=0(3/2^-)$, as well as the $Ξ_b^{*} \bar D^{*}$ and $Ξ_c^{*} B^{*}$ states with $I(J^P)=0(1/2^-,\,3/2^-,\,5/2^-)$. Importantly, these loosely bound states exhibit pronounced spin splittings across different total angular momentum configurations after incorporating the spin-dependent interactions or the channel couplings. In addition, we identify several possible isovector molecular pentaquark candidates within the $Ξ_b^{(\prime,\,*)} \bar D^{(*)}$ and $Ξ_c^{(\prime,\,*)} B^{(*)}$ systems. Our predictions provide clear targets for experimental searches at facilities such as LHCb and Belle II, where the unique five-flavor quark configuration offers a distinctive experimental signature. △ Less

Submitted 29 May, 2026; v1 submitted 24 March, 2026; originally announced March 2026.

Comments: 15 pages, 2 figures, and 8 tables

Journal ref: Phys. Rev. D 113, 094037(2026)

Is the Turner Window Open? Seeking Closure with Resonant Absorption of Galactic Axions in NaI Dark Matter Detectors

Authors: W. C. Haxton, Xing Liu, Anupam Ray, Evan Rule

Abstract: Motivated by the DAMA/LIBRA annual modulation signal, the dark matter community has invested heavily in ultra-clean underground NaI detectors to search for light WIMPs. We point out a new target of opportunity for these detectors -- axions produced by the carbon-burning stars within our galaxy. These stars synthesize large quantities of $^{23}$Na, keeping it at temperatures $\sim 10^9$K for period… ▽ More Motivated by the DAMA/LIBRA annual modulation signal, the dark matter community has invested heavily in ultra-clean underground NaI detectors to search for light WIMPs. We point out a new target of opportunity for these detectors -- axions produced by the carbon-burning stars within our galaxy. These stars synthesize large quantities of $^{23}$Na, keeping it at temperatures $\sim 10^9$K for periods up to tens of thousands of years. Under these conditions, $^{23}$Na radiates 440 keV axions through repeated photo-excitation and axio-deexcitation of its first excited state. Upon reaching a NaI detector, the process is reversed: the axion is resonantly absorbed, producing a 440 keV deexcitation photon. NaI thus serves as both $γ$ source and $γ$ detector. We find that existing NaI detectors can probe axion-nucleon couplings $|g_{aNN}^\mathrm{eff~^{23}Na}| \approx g_{app} \sim 10^{-6}$--$10^{-2}$, including QCD axions with $m_a \gtrsim 10$ eV. While there are several astrophysical constraints on axions with these couplings, our re-examination of these bounds shows that substantial gaps remain, providing strong motivation for the proposed searches. △ Less

Submitted 17 March, 2026; originally announced March 2026.

Comments: v1: 7 pages, 2 figures

Report number: N3AS-26-005, INT-26-008, LA-UR-26-22066

Axial-anomaly effects and chiral phase structure in holographic QCD

Authors: Xin-Yi Liu, Yue-Liang Wu, Zhen Fang

Abstract: We study the impact of axial-anomaly effects on the chiral phase structure in a $U(3)$-extended soft-wall holographic QCD model. Including the pseudoscalar singlet sector allows for a dynamical description of the $η$-$η^\prime$ system through a determinant interaction with a holographic-coordinate-dependent strength. Vacuum pseudoscalar observables, particularly the $η^\prime$ mass and the $η$-… ▽ More We study the impact of axial-anomaly effects on the chiral phase structure in a $U(3)$-extended soft-wall holographic QCD model. Including the pseudoscalar singlet sector allows for a dynamical description of the $η$-$η^\prime$ system through a determinant interaction with a holographic-coordinate-dependent strength. Vacuum pseudoscalar observables, particularly the $η^\prime$ mass and the $η$-$η^\prime$ mixing pattern, constrain the overall magnitude of the anomaly contribution but leave its holographic profile largely undetermined. We then examine how different anomaly profiles consistent with vacuum phenomenology affect the finite-temperature chiral transition. Constructing the Columbia plot within this framework, we find that the predicted phase structure depends sensitively on the anomaly implementation: some profiles yield crossover/second-order behavior across the entire quark-mass plane, while others generate a first-order region in the light-quark corner. These results highlight the strong sensitivity of the holographic QCD phase structure to the modeling of axial-anomaly effects. △ Less

Submitted 12 March, 2026; originally announced March 2026.

Comments: 13 pages, 8 figures, 8 tables

Scattering of $Λ_{c}Λ_{c}$ and $Λ_{c}\barΛ_{c}$ in chiral effective field theory

Authors: Zhe Liu, Hao Xu, Zhan-Wei Liu, Xiang Liu

Abstract: We investigate the $S$-wave scatterings of $Λ_cΛ_c$ and $Λ_{c}\bar Λ_{c}$ systems within a unified chiral effective field theory framework up to next-to-leading order. The contact low-energy coupling constants are determined by fitting to the lattice QCD results for the $Λ_cΛ_c$ scattering phase shift at an unphysical pion mass. After extrapolating to the physical pion mass, we find a repulsive in… ▽ More We investigate the $S$-wave scatterings of $Λ_cΛ_c$ and $Λ_{c}\bar Λ_{c}$ systems within a unified chiral effective field theory framework up to next-to-leading order. The contact low-energy coupling constants are determined by fitting to the lattice QCD results for the $Λ_cΛ_c$ scattering phase shift at an unphysical pion mass. After extrapolating to the physical pion mass, we find a repulsive interaction in the $I(J^P)=0(0^{+})$ $Λ_cΛ_c$ channel, consistent with the lattice QCD simulation. On the $Λ_{c}\bar Λ_{c}$ side, using the fitted contact low-energy constants, we predict the phase shifts and potentials for $Λ_c \barΛ_c$ scattering in the $I(J^{PC})=0(0^{-+})$ and $0(1^{--})$ channels. Attractive interactions are found in both channels, each allowing for the formation of bound states. In particular, the attraction in the $0(1^{--})$ $Λ_c \barΛ_c$ channel is stronger. In addition, our analysis reveals that the spin-spin term caused by the two-pion exchange contributes significantly to the interactions, leading to a distinct mass splitting between the $0(0^{-+})$ and $0(1^{--})$ $Λ_c \barΛ_c$ channels. △ Less

Submitted 10 March, 2026; originally announced March 2026.

Comments: 10 pages, 8 figures

INFLAVON: CMB as cosmic tracer of Flavor physics

Authors: Mu-Chun Chen, Anish Ghoshal, V. Knapp-Perez, Xueqi Li, Xiang-Gan Liu, Cameron Moffett-Smith

Abstract: We unify one of the most widely studied frameworks to explain the hierarchical structure of the flavor sector in the Standard Model, the Froggatt-Nielsen mechanism, with cosmic inflation. We propose that the complex scalar field, the so-called flavon, which breaks the Froggatt-Nielsen $U(1)$ symmetry and generates the Yukawa couplings of the Standard Model, to also drive inflation, which we dub as… ▽ More We unify one of the most widely studied frameworks to explain the hierarchical structure of the flavor sector in the Standard Model, the Froggatt-Nielsen mechanism, with cosmic inflation. We propose that the complex scalar field, the so-called flavon, which breaks the Froggatt-Nielsen $U(1)$ symmetry and generates the Yukawa couplings of the Standard Model, to also drive inflation, which we dub as Inflavon. After inflation ends, the decay of the inflavon reheats the Universe, establishing a novel link between early Universe cosmology and flavor physics. As concrete examples, we present realizations where the inflavon potential is described by an $α$-attractor potential. We then compute the resulting CMB observables, specifically the spectral index ($n_s$), the tensor-to-scalar ratio ($r$), and the amplitude of scalar perturbations ($A_s$) as functions of the underlying Froggatt-Nielsen model parameters. We identify the parameter space in Froggatt-Nielsen models involving the scale of Flavor symmetry breaking $Λ_{\rm FN}$ and FN charges which is ruled out by Planck and ACT data, as well as the region that could be probed by next-generation CMB experiments like CMB-S4, SO and LiteBIRD. We also discuss inflavon as dark matter and its isocurvature constraints. △ Less

Submitted 23 February, 2026; originally announced February 2026.

Comments: 32 pages, 6 figures, 2 tables

Report number: UCI-TR-2026-02

Unquenched Charmonium and Beyond

Authors: Zi-Yue Bai, Dian-Yong Chen, Qi-Huang, Xiang Liu, Si-Qiang Luo, Jun-Zhang Wang

Abstract: The year 2024 marked the 50th anniversary of the discovery of the $J/ψ$ particle, which unveiled the charm quark and the charmonium spectrum, instigating the "November Revolution" in particle physics. This discovery catalyzed the development of quenched potential models, most notably the Cornell model, which provided a foundational quantitative description of the hadronic spectrum. However, the la… ▽ More The year 2024 marked the 50th anniversary of the discovery of the $J/ψ$ particle, which unveiled the charm quark and the charmonium spectrum, instigating the "November Revolution" in particle physics. This discovery catalyzed the development of quenched potential models, most notably the Cornell model, which provided a foundational quantitative description of the hadronic spectrum. However, the landscape of hadron spectroscopy has been profoundly transformed since the turn of the 21st century with the observation of numerous charmonium-like states, such as $X(3872)$, which exhibit properties starkly at odds with quenched model predictions. These discrepancies, exemplified by the "$X(3872)$ low-mass puzzle" and the "$Y$ problem" associated with vector states like $Y(4260)$, underscore the critical limitations of the quenched approximation and signal the necessity for a new theoretical paradigm. This review synthesizes recent advances in hadronic spectroscopy, arguing that the unquenched picture, which incorporates coupled-channel effects such as hadronic loops, is essential for a unified description of these new states and associated anomalies. We demonstrate how unquenched effects provide compelling solutions to long-standing puzzles in charmonium decays (e.g., the "$ρπ$ puzzle" and anomalous dipion transitions), predict and explain the existence of exotic charged states like $Z_c(3900)$ and $Z_b(10610)$ via mechanisms such as Initial Single Pion Emission, and offer a framework for understanding interactions between charmonia and with nucleons. Furthermore, we emphasize the universality of unquenched effects, extending their application to bottomonium and light-flavor sectors. As experimental precision continues to improve, we advocate for the systematic development of unquenched hadronic spectroscopy. △ Less

Submitted 5 August, 2026; v1 submitted 23 February, 2026; originally announced February 2026.

Comments: 217 pages, 134 figures, 21 tables, accepted by Physics Reports

Regge trajectories for the doubly heavy triquarks $((Qq)\bar{Q}')$

Authors: Xin-Ru Liu, Qi Liu, He Song, Jiao-Kai Chen

Abstract: We attempt to apply the Regge trajectory approach to the doubly heavy triquarks $((Qq)\bar{Q}^{\prime})$ $(Q,\,Q'=b,\,c; q=u,\,d,\,s)$. We propose the Regge trajectory relations for the doubly heavy triquarks, and then employ them to crudely estimate the spectra of the triquarks $((cu)\bar{c})$, $((cu)\bar{b})$, $((cs)\bar{c})$, $((cs)\bar{b})$, $((bu)\bar{c})$, $((bu)\bar{b})$, $((bs)\bar{c})$, a… ▽ More We attempt to apply the Regge trajectory approach to the doubly heavy triquarks $((Qq)\bar{Q}^{\prime})$ $(Q,\,Q'=b,\,c; q=u,\,d,\,s)$. We propose the Regge trajectory relations for the doubly heavy triquarks, and then employ them to crudely estimate the spectra of the triquarks $((cu)\bar{c})$, $((cu)\bar{b})$, $((cs)\bar{c})$, $((cs)\bar{b})$, $((bu)\bar{c})$, $((bu)\bar{b})$, $((bs)\bar{c})$, and $((bs)\bar{b})$. The $λ$-trajectories and the $ρ$-trajectories are investigated. The triquark Regge trajectory becomes a new and very simple approach for estimating the spectra of triquarks. It also provides a simple method to investigate the $ρ$-mode and $σ$-mode excitations of pentaquarks and hexaquarks in the triquark picutre. Moreover, the spin-averaged masses of the ground states of pentaquarks $(\bar{c}(cu))(cu)$, $(\bar{b}(bu))(bu)$ and $(\bar{c}(cu))(bu)$ are estimated, which are consistent with other theoretical predictions. △ Less

Submitted 18 February, 2026; originally announced February 2026.

Comments: 13 pages,3 figures,8 tables

Revisiting charmonium hybrid spectroscopy

Authors: Ri-Qing Qian, Bing Chen, Xiang Liu

Abstract: Hadrons with explicit gluonic degrees of freedom, such as charmonium hybrids, are key to understanding nonperturbative behavior of strong interaction, yet they remain experimentally elusive. Within a constituent gluon model treating the hybrid as a $c\bar{c}g$ three-body system with a transverse electric gluon, we predict the masses of the lightest hybrid multiplet (… ▽ More Hadrons with explicit gluonic degrees of freedom, such as charmonium hybrids, are key to understanding nonperturbative behavior of strong interaction, yet they remain experimentally elusive. Within a constituent gluon model treating the hybrid as a $c\bar{c}g$ three-body system with a transverse electric gluon, we predict the masses of the lightest hybrid multiplet ($J^{PC}=1^{--}, 0^{-+}, 1^{-+}, 2^{-+}$) to lie in the range $4.19$--$4.32$ GeV. By analyzing their decay patterns, we provide specific, experimentally testable signatures to guide the search for these exotic states at current and future facilities. △ Less

Submitted 10 August, 2026; v1 submitted 16 February, 2026; originally announced February 2026.

Comments: 10 pages, 4 figures

Journal ref: Phys. Rev. D 114, 034017 (2026)

Producing $Λ(1405)$ and $Λ(1520)$ in $π^-p$ reaction to explore their inner structures

Authors: Yuan Gao, Xiao-Yun Wang, Xiang Liu

Abstract: In this work, the production mechanisms of the hyperon resonances $Λ(1405)$ and $Λ(1520)$ in the $π^- p$ scattering are investigated within an effective Lagrangian approach incorporating Regge trajectories. By including contributions from $t$-channel $K^*$ and $u$-channel $Σ$ exchanges, we perform global fits to the total and differential cross sections for $π^{-} p \rightarrow KΛ(1405)$ and… ▽ More In this work, the production mechanisms of the hyperon resonances $Λ(1405)$ and $Λ(1520)$ in the $π^- p$ scattering are investigated within an effective Lagrangian approach incorporating Regge trajectories. By including contributions from $t$-channel $K^*$ and $u$-channel $Σ$ exchanges, we perform global fits to the total and differential cross sections for $π^{-} p \rightarrow KΛ(1405)$ and $π^{-} p \rightarrow KΛ(1520)$. The results show good agreement with available experimental data. For the total cross section of $Λ(1405)$ production, the $u$-channel contribution is dominant, whereas the $t$-channel contribution plays the primary role in $Λ(1520)$ production. Furthermore, the differential cross sections of the two processes exhibit distinctly different shapes, reflecting their distinct underlying reaction mechanisms. An analysis based on the constituent counting rule indicates that $Λ(1520)$ is consistent with a conventional three-quark configuration, while $Λ(1405)$ shows a clear deviation, suggesting a more exotic structure. Owing to the large branching ratio of $Λ^* \to πΣ$, the Dalitz process $π^{-} p \rightarrow K Λ^{*} \rightarrow K πΣ$ is also calculated. Our results demonstrate that reconstructing $Λ^*$ via the $KπΣ$ final state is experimentally feasible. This study provides important theoretical insights into the production dynamics of these hyperon resonances, and suggests future high-precision measurements of the $t$-distribution at large momentum transfer at facilities such as AMBER, J-PARC, HIKE, and HIAF, which can further clarify their reaction mechanisms and structural properties. △ Less

Submitted 17 February, 2026; v1 submitted 11 February, 2026; originally announced February 2026.

Comments: 11 pages, 18 figures

Journal ref: Phys. Rev. D 113 (2026) 114006

Assessing the validity of the Born-Oppenheimer approximation in potential models for doubly heavy hadrons

Authors: Zi-Long Man, Hao Zhou, Si-Qiang Luo, Xiang Liu

Abstract: The Born-Oppenheimer approximation is widely used to investigate the properties of hydrogen-like systems and doubly heavy hadrons. However, the extent to which this approximation captures the features of such systems within potential models remains an open question. In this work, we adopt the results obtained with the Gaussian expansion method as a benchmark to assess the validity of the Born-Oppe… ▽ More The Born-Oppenheimer approximation is widely used to investigate the properties of hydrogen-like systems and doubly heavy hadrons. However, the extent to which this approximation captures the features of such systems within potential models remains an open question. In this work, we adopt the results obtained with the Gaussian expansion method as a benchmark to assess the validity of the Born-Oppenheimer approximation within potential models for hadronic systems. We also investigate the dependence of the Born-Oppenheimer approximation results on the choice of trial wave functions. A comprehensive study of the Born-Oppenheimer approximation is carried out by performing calculations using Slater-type functions and Gaussian-type functions as trial wave functions, and by comparing the resulting predictions with those obtained from the Gaussian expansion method. We find that the calculations performed within the Born-Oppenheimer approximation are close to those obtained with the Gaussian expansion method when the heavy-quark mass is relatively small. However, as the heavy-quark mass increases, calculations employing Slater-type functions yield larger values than those from the Gaussian expansion method, whereas those using Gaussian-type functions lead to smaller ones. The use of Slater-type functions generally leads to an enhanced binding energy. The underestimation observed in Born-Oppenheimer approximation calculations with Gaussian-type functions primarily stems from the neglect of non-adiabatic corrections. This comparative study provides deeper insight into the structure of doubly heavy hadrons and helps clarify the applicability and limitations of the Born-Oppenheimer treatment within potential models. △ Less

Submitted 15 April, 2026; v1 submitted 9 February, 2026; originally announced February 2026.

Comments: 10 pages, 2 figures and 6 tables, published in Phys. Rev. D

Journal ref: Phys. Rev. D 113, 074020 (2026)

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)

Production of high-spin $ω_J/ρ_J$ ($J=2,3,4,5$) mesons in $π^{-}p$ reactions

Authors: Ting-Yan Li, Zi-Yue Bai, Xiang Liu

Abstract: In this work, we perform a comprehensive investigation of the production of high-spin $ω_J$ and $ρ_J$ mesons ($J=2,3,4,5$) in $π^- p$ reactions using an effective Lagrangian approach. By constructing the relevant $t$-channel processes and calibrating the model with a single adjustable parameter fitted to existing data, we successfully reproduce the measured total and differential cross sections fo… ▽ More In this work, we perform a comprehensive investigation of the production of high-spin $ω_J$ and $ρ_J$ mesons ($J=2,3,4,5$) in $π^- p$ reactions using an effective Lagrangian approach. By constructing the relevant $t$-channel processes and calibrating the model with a single adjustable parameter fitted to existing data, we successfully reproduce the measured total and differential cross sections for the $J=3$ states $ω_3(1670)$ and $ρ_3(1690)$. Within the same framework, we predict the production cross sections for their lower- and higher-spin partners: $ω_2(1975)$, $ρ_2(1940)$, $ω_4(2250)$, $ρ_4(2230)$, $ω_5(2350)$, and $ρ_5(2350)$. Our results show that these states exhibit measurable cross sections with characteristically forward-peaked angular distributions, underscoring their strong potential for observation in future $πp$ meson-beam experiments. △ Less

Submitted 11 March, 2026; v1 submitted 25 January, 2026; originally announced January 2026.

Comments: 12 pages, 9 figures and 5 tables. Accepted by Phys. Rev. D

Journal ref: Phys.Rev. D 113, 054050 (2026)

Unveiling the spectral morphological division of fast radio bursts with CHIME/FRB Catalog 2

Authors: Wan-Peng Sun, Yin-Long Cao, Yong-Kun Zhang, Ji-Guo Zhang, Xiaohui Liu, Yichao Li, Fu-Wen Zhang, Wan-Ting Hou, Jing-Fei Zhang, Xin Zhang

Abstract: Fast radio bursts (FRBs) are commonly classified into repeating and apparently nonrepeating sources, yet whether this distinction reflects intrinsically different physical populations remains uncertain. Using the Second CHIME/FRB Catalog, we apply an unsupervised machine learning framework combining Uniform Manifold Approximation and Projection (UMAP) with density-based clustering to investigate t… ▽ More Fast radio bursts (FRBs) are commonly classified into repeating and apparently nonrepeating sources, yet whether this distinction reflects intrinsically different physical populations remains uncertain. Using the Second CHIME/FRB Catalog, we apply an unsupervised machine learning framework combining Uniform Manifold Approximation and Projection (UMAP) with density-based clustering to investigate the intrinsic structure of the FRB population in a multi-dimensional parameter space. We find that FRBs are primarily separated into two robust clusters dominated by spectral morphology. One cluster is characterized by narrowband emission and longer durations, while the other exhibits relatively broadband spectra and shorter burst timescales. This classification scheme achieves a recall of 0.94 for known repeaters. Within the repeating population, we further identify a stable subclass of atypical repeaters that are broadband, shorter in duration, and more luminous, resembling nonrepeating bursts. Furthermore, broadband nonrepeaters exhibit systematically higher dispersion measures (by approximately 200 $\text{pc cm}^{-3}$) and isotropic luminosities approximately an order of magnitude larger than those of repeating FRBs. Without invoking catastrophic progenitor scenarios, these differences are naturally explained by instrumental sensitivity limits and distance-dependent selection effects. Our results provide new statistical evidence for a physical connection between repeating and nonrepeating FRBs. △ Less

Submitted 13 March, 2026; v1 submitted 22 January, 2026; originally announced January 2026.

Comments: 18 pages, 9 figures

The dynamically generated $h_1$ state by the $K^*\bar{K}^*$ interaction and its $K_1(1270)\bar{K}$ and $b_1(1235)π$ decays

Authors: Qing-Hua Shen, Li-Sheng Geng, Xiang Liu, Ju-Jun Xie

Abstract: We investigate the dynamically generated $h_1$ state with spin-parity $J^P = 1^+$ and a mass around 1790~MeV, arising from the $K^* \bar{K}^*$ interaction within the chiral unitary approach. The partial decay widths into the $K_1(1270)\bar{K}$ and $b_1(1235)π$ channels are calculated via a triangular loop mechanism. In this mechanism, the $h_1$ state couples to $K^* \bar{K}^*$, and final-state int… ▽ More We investigate the dynamically generated $h_1$ state with spin-parity $J^P = 1^+$ and a mass around 1790~MeV, arising from the $K^* \bar{K}^*$ interaction within the chiral unitary approach. The partial decay widths into the $K_1(1270)\bar{K}$ and $b_1(1235)π$ channels are calculated via a triangular loop mechanism. In this mechanism, the $h_1$ state couples to $K^* \bar{K}^*$, and final-state interactions between $K^*$ and $\bar{K}^*$ proceed through pseudoscalar-meson exchange, leading to the final states $\bar{K}$ (or $π$) and $K_1(1270)$ [or $b_1(1235)$]. We also present the invariant mass distributions of a vector meson and a pseudoscalar meson originating from the decays of $K_1(1270)$ or $b_1(1235)$, along with the corresponding decay widths. Our results show that these decay widths are all of the order of a few MeV. We hope that future experiments can test the predictions presented here, thereby helping to identify this $h_1$ state. △ Less

Submitted 9 June, 2026; v1 submitted 20 January, 2026; originally announced January 2026.

Journal ref: Phys.Rev.D 113,114013(2026)

Search for Cosmic Ray Electron Boosted Dark Matter with the CDEX-10 Experiment

Authors: R. Xu, L. T. Yang, Q. Yue, K. J. Kang, Y. J. Li, H. P. An, Greeshma C., J. P. Chang, H. Chen, Y. H. Chen, J. P. Cheng, J. Y. Cui, W. H. Dai, Z. Deng, Y. X. Dong, C. H. Fang, H. Gong, Q. J. Guo, T. Guo, X. Y. Guo, L. He, J. R. He, H. X. Huang, T. C. Huang, S. Karmakar , et al. (63 additional authors not shown)

Abstract: We present new constraints on the cosmic ray electron boosted light dark matter (CReDM) using the 205.4 kg$\cdot$day data of the CDEX-10 experiment located at the China Jinping Underground Laboratory. The cosmic ray electron spectrum and distribution in the Galaxy are generated by the $\tt GALPROP$ code package. In the calculation process of DM-electron scattering process in the Galaxy, we conside… ▽ More We present new constraints on the cosmic ray electron boosted light dark matter (CReDM) using the 205.4 kg$\cdot$day data of the CDEX-10 experiment located at the China Jinping Underground Laboratory. The cosmic ray electron spectrum and distribution in the Galaxy are generated by the $\tt GALPROP$ code package. In the calculation process of DM-electron scattering process in the Galaxy, we consider the energy-dependency of the DM-electron scattering cross section. The constraints on CReDM are set for both heavy and light mediator scenarios using the CDEX-10 dataset. The result exceeds previous Standard Halo Model (SHM) limits for DM mass lower than 0.6 MeV in heavy mediator case and corresponds to the best sensitivity among all direct detection experiments from 1 keV to 0.5 MeV in the light mediator scenario. △ Less

Submitted 13 January, 2026; originally announced January 2026.

Comments: 7 pages, 5 figures

Finding a clean process $B^- \to K^- D^0 K^0$ to probe absolutely exotic four-quark states

Authors: Man-Yu Duan, Guan-Ying Wang, Yun Liang, En Wang, Xiang Liu, Dian-Yong Chen

Abstract: Motivated by the observations of $T_{c\bar{s}0}(2900)^0$ and $T_{c\bar{s}0}(2900)^{++}$, we propose to search for $\tcsbar^0$ in the cleaner process $B^- \to K^- D^0 K^0$. In the $D^*K^*$ molecular picture, our estimates suggest that $T_{c\bar{s}0}(2900)^0$ should contribute significantly to the $D^0 K^0$ invariant mass distribution in $B^- \to K^- D^0 K^0$, as reported by the Belle II Collaborati… ▽ More Motivated by the observations of $T_{c\bar{s}0}(2900)^0$ and $T_{c\bar{s}0}(2900)^{++}$, we propose to search for $\tcsbar^0$ in the cleaner process $B^- \to K^- D^0 K^0$. In the $D^*K^*$ molecular picture, our estimates suggest that $T_{c\bar{s}0}(2900)^0$ should contribute significantly to the $D^0 K^0$ invariant mass distribution in $B^- \to K^- D^0 K^0$, as reported by the Belle II Collaboration. The corresponding fit fraction is estimated to be $(9.72\pm 3.92)\%$ or $(7.09\pm 5.88)\%$ in different fitting schemes. Further precise measurements of this process at Belle II and LHCb could be helpful for clarifying the nature of $T_{c\bar{s}0}(2900)$. △ Less

Submitted 22 May, 2026; v1 submitted 4 January, 2026; originally announced January 2026.

Comments: 6 pages, 6 figures, published version

Journal ref: Phys. Rev. D 113, L091502 (2026)

Next-to-leading order QCD corrections to electromagnetic production and decay of fully charm tetraquarks

Authors: Xinran Liu, Yefan Wang, Ruilin Zhu

Abstract: We investigate the electromagnetic properties of the fully charm tetraquark states, particularly incorporating contributions from internal gluon radiation. The paper first presents analytical expressions for the next-to-leading-order (NLO) QCD corrections to the decay amplitudes of fully charm tetraquarks into two photons. It is found that the QCD corrections are significant for the… ▽ More We investigate the electromagnetic properties of the fully charm tetraquark states, particularly incorporating contributions from internal gluon radiation. The paper first presents analytical expressions for the next-to-leading-order (NLO) QCD corrections to the decay amplitudes of fully charm tetraquarks into two photons. It is found that the QCD corrections are significant for the $J^{PC}=0^{++}$ and $J^{PC}=2^{++}$ fully charm tetraquark decay process. Subsequently, by considering photon-photon fusion in ultra-peripheral high-energy collisions of protons and nuclei and in electron-positron collision, we provide theoretical predictions for the production cross sections of fully charm tetraquark states. The results presented in this work regarding the electromagnetic production and decay of fully charm tetraquarks shall be tested in current and future experiments. △ Less

Submitted 10 July, 2026; v1 submitted 26 December, 2025; originally announced December 2025.

Comments: 10 pages, 3 tables and 3 figures; new LDMEs employed; version to appear in PRD

Demystifying stringy miracles with eclectic flavor symmetries

Authors: V. Knapp-Perez, Xiang-Gan Liu, Hans Peter Nilles, Saul Ramos-Sanchez

Abstract: Effective field theories arising from string compactifications are subject to constraints originating from the duality transformations of string theory. Interpreting these so-called selection rules in terms of conventional symmetries has remained challenging. We show that particular selection rules in heterotic orbifolds can be explained from a subtle interplay between modular and traditional flav… ▽ More Effective field theories arising from string compactifications are subject to constraints originating from the duality transformations of string theory. Interpreting these so-called selection rules in terms of conventional symmetries has remained challenging. We show that particular selection rules in heterotic orbifolds can be explained from a subtle interplay between modular and traditional flavor symmetries within the eclectic flavor framework. △ Less

Submitted 24 December, 2025; originally announced December 2025.

Comments: 17 pages, 1 figure

Dynamical study of hidden-strange pentaquarks as analogs of the hidden-charm states

Authors: Xuejie Liu, Yue Tan, Yuheng Wu, Dianyong Chen, Hongxia Huang, Jialun Ping

Abstract: Motivated by the recent BESIII experiment~\cite{BESIII:2024muk} searching for hidden-strange exotic hadrons, we perform a systematic theoretical study of the hidden-strange pentaquark system within the framework of the quark delocalization color screening model (QDCSM) and the resonating group method (RGM). Our results demonstrate that the channel coupling effect plays a decisive role in the forma… ▽ More Motivated by the recent BESIII experiment~\cite{BESIII:2024muk} searching for hidden-strange exotic hadrons, we perform a systematic theoretical study of the hidden-strange pentaquark system within the framework of the quark delocalization color screening model (QDCSM) and the resonating group method (RGM). Our results demonstrate that the channel coupling effect plays a decisive role in the formation of bound and resonance states. It not only significantly enhances the short-range attraction but also induces essential attractive contributions from pion exchange. We predict three bound states with masses of $1759$ MeV, $2000$ MeV, and $2407$ MeV. Furthermore, we report the existence of a hidden-strange pentaquark resonance state, $ΞK^{\ast}$, with quantum numbers $I(J^{P})=0(1/2^{-})$. This resonance is identified in the $S$-wave scattering phase shifts of the $Λη_{s}$ and $Λφ$ open channels, with a predicted mass in the range of $2204\text{--}2208$ MeV. By accounting for both the scattering width from channel coupling and the intrinsic decay width of the constituent $K^{\ast}$, the total decay width is estimated to be $55\text{--}63$ MeV. These theoretical predictions provide important guidance for future experimental searches for such exotic states at facilities like BESIII. △ Less

Submitted 11 December, 2025; originally announced December 2025.

Dedicated Searches for Millicharged Particles at Intensity-Frontier Facilities: SpinQuest and SHiP

Authors: Leo Bailloeul, Matthew Citron, Yanou Cui, Saeid Foroughi-Abari, Insung Hwang, Fengyi Li, Yu-Dai Tsai, Ming Xiong Liu, Kranti Gunthoti, Jae Hyeok Yoo

Abstract: We conduct a dedicated study of searches for millicharged particles (mCPs) utilizing scintillator-based detectors at high-intensity fixed-target experiments, with particular focus on the SpinQuest and forthcoming Search for Hidden Particles experiment (SHiP) facilities. The analysis incorporates the three primary production mechanisms: meson decays, Drell-Yan processes, and proton bremsstrahlung.… ▽ More We conduct a dedicated study of searches for millicharged particles (mCPs) utilizing scintillator-based detectors at high-intensity fixed-target experiments, with particular focus on the SpinQuest and forthcoming Search for Hidden Particles experiment (SHiP) facilities. The analysis incorporates the three primary production mechanisms: meson decays, Drell-Yan processes, and proton bremsstrahlung. In particular, our updated analysis reveals that proton bremsstrahlung dominates the production rate in the sub-GeV mass regime. Detailed detector simulations and background evaluations are performed to obtain realistic sensitivity estimates. Our results demonstrate that future experiments located in the SpinQuest and SHiP facilities can achieve substantial improvements in discovery potential, enhancing sensitivity to the mCP charge parameter $ε=q_χ/e$ (with $q_χ$ denoting the mCP electric charge) by up to two orders of magnitude relative to existing limits. △ Less

Submitted 11 December, 2025; originally announced December 2025.

Comments: 28 pages, 8 figures