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1. Prompt and non-prompt J/ψ production at midrapidity in Pb–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV

   https://doi.org/10.1007/JHEP02(2024)066  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (February 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> The transverse momentum (p_T) and centrality dependence of the nuclear modification factorR_AAof prompt and non-prompt J/ψ, the latter originating from the weak decays of beauty hadrons, have been measured by the ALICE collaboration in Pb–Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV. The measurements are carried out through the e⁺e⁻decay channel at midrapidity (|y| < 0.9) in the transverse momentum region 1.5 <p_T< 10 GeV/c. Both prompt and non-prompt J/ψmeasurements indicate a significant suppression forp_T> 5 GeV/c, which becomes stronger with increasing collision centrality. The results are consistent with similar LHC measurements in the overlappingp_Tintervals, and cover the kinematic region down top_T= 1.5 GeV/cat midrapidity, not accessible by other LHC experiments. The suppression of prompt J/ψin central and semicentral collisions exhibits a decreasing trend towards lower transverse momentum, described within uncertainties by models implementing J/ψproduction from recombination of c and$$ \overline{\textrm{c}} $$ $\overline{c}$quarks produced independently in different partonic scatterings. At high transverse momentum, transport models including quarkonium dissociation are able to describe the suppression for prompt J/ψ. For non-prompt J/ψ, the suppression predicted by models including both collisional and radiative processes for the computation of the beauty-quark energy loss inside the quark-gluon plasma is consistent with measurements within uncertainties. 

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2. Hadronization of heavy quarks

   https://doi.org/10.1103/PhysRevC.109.054912  

   Zhao, Jiaxing; Aichelin, Jörg; Gossiaux, Pol Bernard; Beraudo, Andrea; Cao, Shanshan; Fan, Wenkai; He, Min; Minissale, Vincenzo; Song, Taesoo; Vitev, Ivan; et al (May 2024, Physical Review C)

   Heavy-flavor hadrons produced in ultrarelativistic heavy-ion collisions are a sensitive probe for studying hadronization mechanisms of the quark-gluon-plasma. In this paper, we survey how different transport models for the simulation of heavy-quark diffusion through a quark-gluon plasma in heavy-ion collisions implement hadronization and how this affects final state observables. Utilizing the same input charm-quark distribution in all models at the hadronization transition, we find that the transverse-momentum dependence of the nuclear modification factor of various charm hadron species has significant sensitivity to the hadronization scheme. In addition, the charm-hadron elliptic flow exhibits a nontrivial dependence on the elliptic flow of the hadronizing partonic medium. 

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3. Measurement of in-medium modification of energy-space structure of jets via γ and π⁰ triggered hadrons in Au+Au collisions at RHIC

   https://doi.org/10.1051/epjconf/202429611011  

   Connors, Megan (June 2024, EPJ Web of Conferences)

   Bellwied, R; Geurts, F; Rapp, R; Ratti, C; Timmins, A; Vitev, I (Ed.)

   Since the discovery of the jet quenching at RHIC, the in-medium interaction of hard scattered partons with the nuclear medium created by highenergy heavy-ion collisions has been an excellent tool to understand not only the transport properties of the medium but also its time evolution towards hadronization. The multi-differential measurement of the high momentum twoparticle correlations can probe a particular space-time window as a function of energy transfer. Comparing the correlations with the prompt photon-triggered hadron spectra, one can extract the property of the medium from various aspects and contribute to distinct models. The PHENIX experiment at RHIC has collected its highest statistics of theγ and π⁰ triggered hadron events in Au+Au collisions at √s_NN= 200 GeV in the RHIC Year-2014 run, and measured not only the inclusive spectra of the triggered hadrons but also the angle and energy dependent I_AA and D_AA. We will discuss the in-medium modification of the energy-space structure of the jets at the RHIC energies with the results obtained. 

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4. Production of $$ {\textrm{K}}_{\textrm{S}}^0 $$ , Λ ($$ \overline{\Lambda} $$), Ξ±, and Ω± in jets and in the underlying event in pp and p–Pb collisions

   https://doi.org/10.1007/JHEP07(2023)136  

   Acharya, S.; Adamová, D.; Adler, A.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Ahuja, I.; et al (July 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> The production of strange hadrons ($$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$, Λ, Ξ^±, and Ω^±), baryon-to-meson ratios (Λ/$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$, Ξ/$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$, and Ω/$$ {\textrm{K}}_{\textrm{S}}^0 $$ $K_S^0$), and baryon-to-baryon ratios (Ξ/Λ, Ω/Λ, and Ω/Ξ) associated with jets and the underlying event were measured as a function of transverse momentum (p_T) in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV and p Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, Ξ^±and Ω^±, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p–Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadronp_T(0.6–6 GeV/c). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with Pythia8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadronp_Tregion. The maximum deviation is observed for Ξ^±and Ω^±which reaches a factor of about six. The event multiplicity dependence is further investigated in p−Pb collisions. In contrast to what is observed in the underlying event, there is no significant event-multiplicity dependence for particle production in jets. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies. 

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5. Strangeness production in $$ \sqrt{s_{\textrm{NN}}} $$ = 3 GeV Au+Au collisions at RHIC

   https://doi.org/10.1007/JHEP10(2024)139  

   Abdulhamid, M I; Aboona, B E; Adam, J; Adamczyk, L; Adams, J R; Aggarwal, I; Aggarwal, M M; Ahammed, Z; Aschenauer, E C; Aslam, S; et al (October 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We report multi-differential measurements of strange hadron production ranging from mid- to target-rapidity in Au+Au collisions at a center-of-momentum energy per nucleon pair of$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{s_{\mathrm{NN}}}$= 3 GeV with the STAR experiment at RHIC.$$ {K}_S^0 $$ $K_S^0$meson and Λ hyperon yields are measured via their weak decay channels. Collision centrality and rapidity dependences of the transverse momentum spectra and particle ratios are presented. Particle mass and centrality dependence of the average transverse momenta of Λ and$$ {K}_S^0 $$ $K_S^0$are compared with other strange particles, providing evidence of the development of hadronic rescattering in such collisions. The 4πyields of each of these strange hadrons show a consistent centrality dependence. Discussions on radial flow, the strange hadron production mechanism, and properties of the medium created in such collisions are presented together with results from hadronic transport and thermal model calculations. 

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