Mon·Jul 24, 2023Monday·July 24, 2023

1. 01*

   Multiplicity and transverse momentum dependence of charge-balance functions in pPb and PbPb collisions at LHC energies

   CMS Collaboration

   Measurements of the charge-dependent two-particle angular correlation function in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV and lead-lead (PbPb) collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV are reported. The pPb and PbPb data sets correspond to integrated luminosities of 186 nb${}^{-1}$ and 0.607 nb${}^{-1}$, respectively, and were collected using the CMS detector at the CERN LHC. The charge-dependent correlations are characterized by balance functions of same- and opposite-sign particle pairs. The balance functions, which contain information about the creation time of charged particle pairs and the development of collectivity, are studied as functions of relative pseudorapidity ($\Delta \eta$) and relative azimuthal angle ($\Delta \varphi$), for various multiplicity and transverse momentum ($p_{\mathrm{T}}$) intervals. A multiplicity dependence of the balance function is observed in $\Delta \eta$ and $\Delta \varphi$ for both systems. The width of the balance functions decreases toward high-multiplicity collisions in the momentum region $<$ 2 GeV, for pPb and PbPb results. Integrals of the balance functions are presented in both systems, and a mild dependence of the charge-balancing fractions on multiplicity is observed. No multiplicity dependence is observed at higher transverse momentum. The data are compared with HYDJET, HIJING and AMPT generator predictions, none of which capture completely the multiplicity dependence seen in the data. The comparison of results with different center-of-mass energies suggest that the balance functions become narrower at higher energies, which is consistent with the idea of delayed hadronization and the effect of radial flow.

   nucl-exhep-exJHEP(2024)·10 citations
2. 02*

   Study of charm hadronization with prompt ${\Lambda }_{\mathrm{c}}^{+}$ baryons in proton-proton and lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   CMS Collaboration

   The production of prompt ${\Lambda }_{\mathrm{c}}^{+}$ baryons is measured via the exclusive decay channel ${\Lambda }_{\mathrm{c}}^{+}$ $\to$ pK${}^{-}{\pi }^{+}$ at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb${}^{-1}$, respectively. The measurements are performed within the ${\Lambda }_{\mathrm{c}}^{+}$ rapidity interval $|y|$ $<$ 1 with transverse momentum ($p_{\mathrm{T}}$) ranges of 3-30 and 6-40 GeV/$c$ for pp and PbPb collisions, respectively. Compared to the yields in pp collisions scaled by the expected number of nucleon-nucleon interactions, the observed yields of ${\Lambda }_{\mathrm{c}}^{+}$ with $p_{\mathrm{T}}$ $>$ 10 GeV/$c$ are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The ${\Lambda }_{\mathrm{c}}^{+}$ / D${}^0$ production ratio is similar in PbPb and pp collisions at $p_{\mathrm{T}}$ $>$ 10 GeV/$c$, suggesting that the coalescence process does not play a dominant role in prompt ${\Lambda }_{\mathrm{c}}^{+}$ baryon production at higher $p_{\mathrm{T}}$.

   nucl-exhep-exJHEP(2024)·31 citations
3. 03*

   Hard and electromagnetic probes: plans for future measurements at the CERN SPS

   E. Scomparin🇮🇹

   The CERN SuperProtoSynchrotron (SPS) represents an ideal facility for fixed-target heavy-ion experiments exploring the phase diagram of strongly interacting matter in the region $200\le {\mu }_{\mathrm{B}}\le 500$ MeV. It can deliver high-intensity beams ($>10^6$ Pb/s), allowing a study of rare probes of the Quark-Gluon Plasma, including electromagnetic and hard processes. The NA61/SHINE experiment is currently active and plans to perform a first direct measurement of open charm production in Pb--Pb collisions at top SPS energy and possibly at lower energies. The project of a new experiment, NA60+, based on a muon spectrometer coupled to a vertex spectrometer is currently being developed, for the study of dimuon and heavy quark production, and a Letter of Intent was recently submitted. In this contribution the physics motivation for the studies of rare probes, the existing and planned experimental set-ups and their expected physics performance will be discussed.

   nucl-exPoS(2024)·2 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.