Thu·Jul 4, 2024Thursday·July 4, 2024

1. 01*

   Properties of the QCD Matter -- An Experimental Review of Selected Results from RHIC BES Program

   Jinhui Chen · Xin Dong · Xionghong He · Huanzhong Huang · Feng Liu · Xiaofeng Luo · Yu-Gang Ma · Lijuan Ruan · Ming Shao · Shusu Shi · Xu Sun · Aihong Tang and 16 other authors

   In the paper, we discuss the development of the multi-gap resistive plate chamber Time-of-Flight (TOF) technology and the production of the STAR TOF detector in China at the beginning of the 21st century. Then we review recent experimental results from the first beam energy scan program (BES-I) at the Relativistic Heavy Ion Collider (RHIC). Topics cover measurements of collectivity, chirality, criticality, global polarization, strangeness, heavy-flavor, di-lepton and light nuclei productions.

   nucl-exhep-exnucl-thNucl.Sci.Tech.(2024)·203 citations
2. 02*

   Observation of double J/$\psi$ meson production in pPb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

   CMS Collaboration

   The first observation of the concurrent production of two J/$\psi$ mesons in proton-nucleus collisions is presented. The analysis is based on a proton-lead (pPb) data sample recorded at a nucleon-nucleon center-of-mass energy of 8.16 TeV by the CMS experiment at the CERN LHC and corresponding to an integrated luminosity of 174.6 nb${}^{-1}$. The two J/$\psi$ mesons are reconstructed in their ${\mu }^{+}{\mu }^{-}$ decay channels with transverse momenta $p_{\mathrm{T}}$ $>$ 6.5 GeV and rapidity $|y|$ $<$ 2.4. Events where one of the J/$\psi$ mesons is reconstructed in the dielectron channel are also considered in the search. The pPb $\to$ J/$\psi$J/$\psi$ + X process is observed with a significance of 5.3 standard deviations. The measured inclusive fiducial cross section, using the four-muon channel alone, is $\sigma$(pPb $\to$ J/$\psi$J/$\psi$ + X) = 22.0 $\pm$ 8.9 (stat) $\pm$ 1.5 (syst) nb. A fit of the data to the expected rapidity separation for pairs of J/$\psi$ mesons produced in single (SPS) and double (DPS) parton scatterings yields ${\sigma }_{\text{SPS}}^{\mathrm{pPb}\to \mathrm{J}/\psi \mathrm{J}/\psi +\mathrm{X}}$ = 16.5 $\pm$ 10.8 (stat) $\pm$ 0.1 (syst) nb and ${\sigma }_{\text{DPS}}^{\mathrm{pPb}\to \mathrm{J}/\psi \mathrm{J}/\psi +\mathrm{X}}$ = 5.4 $\pm$ 6.2 (stat) $\pm$ 0.4 (syst) nb, respectively. This latter result can be transformed into a lower bound on the effective DPS cross section, closely related to the squared average interparton transverse separation in the collision, of ${\sigma }_{\text{eff}}$ $>$ 1.0 mb at 95% confidence level.

   nucl-exhep-exPRD(2024)·14 citations
3. 03*

   Upper Limit on the Photoproduction Cross Section of the Spin-Exotic ${\pi }_1(1600)$

   GlueX Collaboration: F. Afzal🇩🇪 · C. S. Akondi🇺🇸 · M. Albrecht🇺🇸 · M. Amaryan🇺🇸 · S. Arrigo🇺🇸 · V. Arroyave🇺🇸 · A. Asaturyan🇺🇸 · A. Austregesilo🇺🇸 · Z. Baldwin🇺🇸 · F. Barbosa🇺🇸 · J. Barlow🇺🇸 · E. Barriga🇺🇸 and 137 other authors

   The spin-exotic hybrid meson ${\pi }_1(1600)$ is predicted to have a large decay rate to the $\omega \pi \pi$ final state. Using 76.6~pb${}^{-1}$ of data collected with the GlueX detector, we measure the cross sections for the reactions $\gamma p\to \omega {\pi }^{+}{\pi }^{-}p$, $\gamma p\to \omega {\pi }^0{\pi }^{0}p$, and $\gamma p\to \omega {\pi }^{-}{\pi }^0{\Delta }^{++}$ in the range $E_{\gamma }=$ 8-10 GeV. Using isospin conservation, we set the first upper limits on the photoproduction cross sections of the ${\pi }_1^0(1600)$ and ${\pi }_1^{-}(1600)$. We combine these limits with lattice calculations of decay widths and find that photoproduction of ${\eta }^{\prime }\pi$ is the most sensitive two-body system to search for the ${\pi }_1(1600)$.

   nucl-exhep-exPRL(2024)·18 citations
4. 04*

   Backward DVCS on the pion in Sullivan processes

   Abigail Rodrigues Castro🇫🇷 · Cedric Mezrag🇫🇷 · Jose M. Morgado Chávez🇫🇷 · Bernard Pire🇫🇷

   The purpose of this work is to do a systematic feasibility study of measuring in backward region deeply virtual Compton scattering on the pion in Sullivan processes in the framework of collinear QCD factorization where pion to photon transition distribution amplitudes (TDAs) describe the photon content of the $\pi$ meson. Our approach employs TDAs based on the overlap of light front wave functions, using a previously developed pion light-front wave function and deriving a consistent model for the light front wave functions of the photon. This work is expected to lead us to an estimate of the cross-sections that could be measured in the future U.S. and China's electron-ion colliders. It will also provide a comparison with the forward Sullivan DVCS case, which gives access to pion GPDs and for which a strong signal is expected.

   ↳ hep-phhep-exhep-thnucl-ex+1PoS(2025)·0 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.