Tue·Jan 2, 2024Tuesday·January 2, 2024

1. 01*

   Search for the Chiral Magnetic and Vortical Effects Using Event Shape Approaches in Au+Au Collisions at STAR

   Zhiwan Xu (for the STAR Collaboration)🇺🇸

   The chiral magnetic/vortical effect (CME/CVE) in heavy-ion collisions probe the topological sector of Quantum Chromodynamics, where P and CP symmetries are violated locally in strong interactions. However, the experimental observables for the CME/CVE are dominated by backgrounds related to elliptic flow and nonflow. We employ event shape variables to mitigate the flow background and event planes based on spectators to minimize the nonflow background. We report on the CME search in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 14.6, 19.6, 27, and 200 GeV, as well as the CVE search at 19.6 and 27 GeV.

   nucl-exhep-exEPJ Web Conf.(2024)·8 citations
2. 02*

   Measurements of $p-\Lambda$ and $d-\Lambda$ correlations in 3 GeV Au+Au collisions at STAR

   Yu Hu (for the STAR Collaborations)🇺🇸

   Heavy-ion collisions provide a unique opportunity to explore nucleon-hyperon (N-Y) interactions through two-particle correlations. The $p-\Lambda$ and $d-\Lambda$ correlations shed light on both N-Y two-body and N-N-Y three-body interactions, which is crucial for understanding neutron star properties. We present the high precision measurement of $p-\Lambda$ and the first measurement of $d-\Lambda$ correlation with $\sqrt{s_{{}_{\mathrm{NN}}}}=$ 3 GeV Au+Au collisions at STAR. Using the Lednicky-Lyuboshitz formalism, we characterized emission source size, the scattering length ($f_0$), and the effective range ($d_0$) of $p-\Lambda$ and $d-\Lambda$ interactions. Using the $f_0$ and $d_0$ extracted from two spin states in $d-\Lambda$ correlation, the parameters from the doublet state indicate the hypertriton binding energy is consistent with the current average of world measurements.

   nucl-exhep-exhep-phnucl-thEPJ Web Conf.(2024)·10 citations
3. 03*

   Optimization of muonium yield in perforated silica aerogel

   Shihan Zhao🇨🇳 · Jian Tang🇨🇳

   A muonium consists of a positive muon associated with an orbital electron, and the spontaneous conversion to antimuonium serves as a clear indication of new physics beyond the Standard Model in particle physics.One of the most important aspects in muonium-to-antimuonium conversion experiment (MACE) is to increase the muonium yield in vacuum to challenge the latest limit obtained in 1999. This study focuses on a simulation of the muonium formation and diffusion in the perforated silica aerogel. The independent simulation results can be well validated by experimental data. By optimizing the target geometry, we find a maximum muonium emission efficiency of $7.92(2)\%$ and a maximum vacuum yield of $1.134(2)\%$ with a typical surface muon beam, indicating a 2.6 times and a 2.1 times enhancement, respectively. Our results will pave the way for muonium experiments.

   ↳ hep-exnucl-exPRD(2024)·5 citations
4. 04*

   The Intrinsic Energy Resolution of LaBr${}_3$(Ce) Crystal for GECAM

   Pei-Yi Feng (1 and 2) · Xi-Lei Sun (3)🇨🇳 · Zheng-Hua An (1) · Cheng-Er Wang (4) · Da-Li Zhang (1)🇨🇳 · Xin-Qiao Li (1) · Chao Zheng (1 and 2) · Shao-Lin Xiong (1)🇨🇳 · Hong Lu (1) ((1) Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China, (2) University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China, (3) State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China, (4) National Engineering Research Center for Rare Earth, Grirem Advanced Materials Co., Ltd., Beijing, China)

   This study aims to provide an accurate estimation of the intrinsic resolution of LaBr${}_3$(Ce) crystal through a combination of experimental and simulation methods. We re-analyzed the data from previous Wide-Angle Compton Coincidence (WACC) and Hard X-ray Calibration Facility (HXCF) experiments, conducted PMT Single-Photoelectron Calibration (SPEC) and radial non-uniformity (also called Spot Scanning, SS) experiments to acquire new data, and combined these results with Geant4 simulations to isolate the contribution of each physical process to the total energy resolution, thereby allowing for a precise estimation of the scintillator's intrinsic resolution. For 100 keV X-rays, the total energy resolution of LaBr${}_3$(Ce) crystal is 3.99% $\pm$ 0.04% (expressed as 1-$\sigma$), with statistical fluctuations and intrinsic resolution as the main components, contributing 2.47% $\pm$ 0.00% and 3.06% $\pm$ 0.06%, respectively. We identify two main sources of intrinsic resolution: one primarily due to non-proportional scintillation, contributing 2.28% $\pm$ 0.00%, and the other due to fluctuations in the energy transfer process, contributing 2.04% $\pm$ 0.08%. We quantified six components of the total energy resolution and reconstructed the photon response using Geant4. The consistency between the reconstructed relative light yield and the experimental measurements validated the mass model of the LaBr${}_3$(Ce) detector used in the simulations.

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exJINST(2025)·3 citations
5. 05*

   In-medium mass shift of two-flavored heavy mesons, $B_c$, $B_c^{\ast }$, $B_s$, $B_s^{\ast }$, $D_s$ and $D_s^{\ast }$

   G. N. Zeminiani🇧🇷 · S. L. P. G. Beres🇧🇷 · K. Tsushima🇧🇷

   For the first time, we estimate the in-medium mass shift of the two-flavored heavy mesons $B_c,B_c^{\ast },B_s,B_s^{\ast },D_s$ and $D_s^{\ast }$ in symmetric nuclear matter. The estimates are made by evaluating the lowest order one-loop self-energies. The enhanced excitations of intermediate state heavy-light mesons in symmetric nuclear matter are the origin of their negative mass shift. This negative mass shift may be regarded as a signature of partial restoration of chiral symmetry in an empirical sense because the origin of the negative mass shift in the study is not directly related to the chiral symmetry mechanism. Our results show that the magnitude of the mass shift for the $B_c$ meson ($\bar{b}c$ or $b\bar{c}$) is larger than those of the ${\eta }_c(\bar{c}c)$ and ${\eta }_b(\bar{b}b)$, different from a naive expectation that it would be in between them. While, that of the $B_c^{\ast }$ shows the in between of the $J/\psi$ and ${\rm Y}$. We observe that the lighter vector meson excitation in each meson self-energy gives a dominant contribution for the corresponding meson mass shift, $B_c,B_s,$ and $D_s$.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·8 citations
6. 06*

   3D Multi-system Bayesian Calibration with Energy Conservation to Study Rapidity-dependent Dynamics of Nuclear Collisions

   Andi Mankolli🇺🇸 · Aaron Angerami🇺🇸 · Ritu Arora🇺🇸 · Steffen Bass🇺🇸 · Shanshan Cao🇨🇳 · Yi Chen🇺🇸 · Lipei Du🇨🇦 · Raymond Ehlers🇺🇸 · Hannah Elfner🇩🇪 · Wenkai Fan🇺🇸 · Rainer J. Fries🇺🇸 · Charles Gale🇨🇦 and 39 other authors

   Considerable information about the early-stage dynamics of heavy-ion collisions is encoded in the rapidity dependence of measurements. To leverage the large amount of experimental data, we perform a systematic analysis using three-dimensional hydrodynamic simulations of multiple collision systems -- large and small, symmetric and asymmetric. Specifically, we perform fully 3D multi-stage hydrodynamic simulations initialized by a parameterized model for rapidity-dependent energy deposition, which we calibrate on the hadron multiplicity and anisotropic flow coefficients. We utilize Bayesian inference to constrain properties of the early- and late- time dynamics of the system, and highlight the impact of enforcing global energy conservation in our 3D model.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2024)·7 citations
7. 07*

   Bulk medium properties of heavy-ion collisions from the beam energy scan with a multistage hydrodynamic model

   Lipei Du🇨🇦

   We introduce a method to reconstruct full rapidity distributions of charged particle multiplicity and net proton yields, crucial for constraining the longitudinal dynamics of nuclear matter created in the beam energy scan program. Employing rapidity distributions within a multistage hydrodynamic model calibrated for Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=7.7-200$GeV, we estimate the total energy and baryon number deposited into the collision fireball, offering insights into initial dynamics and the identification of nuclear remnants. We explore the potential of rapidity-dependent measurements in probing equations of state at finite chemical potentials. Furthermore, we compare the freeze-out parameters derived from both hydrodynamics and thermal models, highlighting that the parameters extracted via thermal models represent averaged properties across rapidities.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2024)·17 citations
8. 08*

   Exploring the partonic collectivity in small systems at the LHC

   Yuanyuan Wang · Wenbin Zhao · Huichao Song

   Using the Hydro-Coal-Frag model that combines hydrodynamics at low $p_{\mathrm{T}}$, quark coalescence at intermediate $p_{\mathrm{T}}$, and the LBT transport model at high $p_{\mathrm{T}}$, we study the spectra and elliptic flow of identified hadrons in high multiplicity p--Pb and p--p collisions at the Large Hadron Collider (LHC). In p--Pb collisions, the Hydro-Coal-Frag model gives a good description of the differential elliptic flow over the $p_{\mathrm{T}}$ range from 0 to 6 GeV and the approximate number of constituent quark (NCQ) scaling at intermediate $p_{\mathrm{T}}$. Although Hydro-Coal-Frag model can also roughly describe the elliptic flow in high multiplicity p--p collisions with the quark coalescence process, the larger contribution from the string fragmentations leads to a notable violation of the NCQ scaling of $v_2$ at intermediate $p_{\mathrm{T}}$ as observed in the experiment. Comparison runs of the Hydro-Frag model without the coalescence process demonstrate that regardless the parameter adjustments, the Hydro-Frag model cannot simultaneously describe the $p_{\mathrm{T}}$ spectra and the elliptic flow of identified hadrons in either p--Pb collisions or p--p collisions. The calculations in this paper thus provide support for the existence of partonic degrees of freedom and the possible formation of the QGP in the small systems created at the LHC.

   ↳ nucl-thhep-phnucl-exPRC(2026)·12 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.