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1. Investigating $D^0$ meson production in p-Pb collisions at 5.02 TeV with a multi-phase transport model

   https://doi.org/10.1140/epjc/s10052-024-13265-9  

   Zhang, Chao; Zheng, Liang; Shi, Shusu; Lin, Zi-Wei (September 2024, The European Physical Journal C)

   Abstract We study the production of$$D^0$$ $D^0$meson inp+pandp-Pb collisions using the improved AMPT model considering both coalescence and independent fragmentation of charm quarks after the Cronin broadening is included. After a detailed discussion of the improvements implemented in the AMPT model for heavy quark production, we show that the modified AMPT model can provide a good description of$$D^0$$ $D^0$meson spectra inp-Pb collisions, the$$Q_{\textrm{pPb}}$$ $Q_{\text{pPb}}$data at different centralities and$$R_{\textrm{pPb}}$$ $R_{\text{pPb}}$data in both mid- and forward (backward) rapidities. We also studied the effects of nuclear shadowing and parton cascade on the rapidity dependence of$$D^{0}$$ $D^0$meson production and$$R_{\textrm{pPb}}$$ $R_{\text{pPb}}$. Our results indicate that using the same strength of the Cronin effect (i.e$$\delta $$ $\delta$value) as that obtained from the mid-rapidity data leads to a considerable overestimation of the$$D^0$$ $D^0$meson spectra and$$R_{\textrm{pPb}}$$ $R_{\text{pPb}}$data at high$$p_{\textrm{T}}$$ $p_{\text{T}}$in the backward rapidity. As a result, the$$\delta $$ $\delta$is determined via a$$\chi ^2$$ ${\chi }^2$fitting of the$$R_{\textrm{pPb}}$$ $R_{\text{pPb}}$data across various rapidities. This work lays the foundation for a better understanding of cold-nuclear-matter (CNM) effects in relativistic heavy-ion collisions. 

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2. Disentangling the development of collective flow in high energy proton proton collisions with a multiphase transport model

   https://doi.org/10.1140/epjc/s10052-024-13378-1  

   Zheng, Liang; Liu, Lian; Lin, Zi-Wei; Shou, Qi-Ye; Yin, Zhong-Bao (October 2024, The European Physical Journal C)

   Abstract In this work, we investigate the collective flow development in high energy proton proton (pp) collisions with a multiphase transport model (AMPT) based on PYTHIA8 initial conditions with a sub-nucleon structure. It is found that the PYTHIA8 based AMPT model can reasonably describe both the charged hadron productions and elliptic flow experimental data measured in pp collisions at$$\sqrt{s}=13$$ $\sqrt{s}=13$TeV. By turning on the parton and hadron rescatterings in AMPT separately, we find that the observed collective flow in pp collisions is largely developed during the parton evolution, while no significant flow effect can be generated with the pure hadronic rescatterings. It is also shown that the parton escape mechanism is important for describing both the magnitude of the two-particle cumulant and the sign of the four-particle cumulants. We emphasize that the strong mass ordering of the elliptic flow results from the coalescence process in the transport model and can thus be regarded as unique evidence related to the creation of deconfined parton matter in high energy pp collisions. 

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3. Heavy ion collisions from $\sqrt{s_{NN}}$ of 62.4 GeV down to 7.7 GeV in the EPOS4 framework

   https://doi.org/10.1103/PhysRevC.111.014903  

   Werner, K; Jahan, J; Karpenko, I; Pierog, T; Stefaniak, M; Vintache, D (January 2025, Physical Review C)

   The EPOS4 project is an attempt to construct a realistic model for describing relativistic collisions of different systems, from proton-proton ( $pp$) to nucleus-nucleus ( $AA$), at energies from several TeV per nucleon down to several GeV. We argue that a parallel scattering formalism (as in EPOS4) is relevant for primary scatterings in $AA$collisions above 4 GeV, whereas sequential scattering (cascade) is appropriate below. We present briefly the basic elements of EPOS4, and then investigate heavy ion collisions from 62.4 GeV down to 7.7 GeV, to understand how physics changes with energy, studying in particular the disappearance of the fluid component at low energies. 

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4. Recent developments in mathematical aspects of relativistic fluids

   https://doi.org/10.1007/s41114-024-00052-x  

   Disconzi, Marcelo (October 2024, Living Reviews in Relativity)

   Abstract We review some recent developments in mathematical aspects of relativistic fluids. The goal is to provide a quick entry point to some research topics of current interest that is accessible to graduate students and researchers from adjacent fields, as well as to researches working on broader aspects of relativistic fluid dynamics interested in its mathematical formalism. Instead of complete proofs, which can be found in the published literature, here we focus on the proofs’ main ideas and key concepts. After an introduction to the relativistic Euler equations, we cover the following topics: a new wave-transport formulation of the relativistic Euler equations tailored to applications; the problem of shock formation for relativistic Euler; rough (i.e., low-regularity) solutions to the relativistic Euler equations; the relativistic Euler equations with a physical vacuum boundary; relativistic fluids with viscosity. We finish with a discussion of open problems and future directions of research. 

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5. Baryon Number Transport, Strangeness Conservation and Ω-hadron Correlations

   https://doi.org/10.1051/epjconf/202327603002  

   Wu, Xiatong; Dong, Weijie; Yu, Xiaozhou; Li, Hui; Wang, Gang; Zhong Huang, Huan; Lin, Zi-Wei (January 2023, EPJ Web of Conferences)

   Kim, Y.; Moon, D.H. (Ed.)

   Although strange quarks are produced in ss¯ pairs, the ratio of Ω − to Ω¯ + is greater than one in heavy-ion collisions at lower RHIC energies. Thus the produced Ω hyperons must carry net baryon quantum numbers from the colliding nuclei. We present results of K-Ω correlations from AMPT model simulations of Au+Au collisions at √S NN = 14.6 GeV, to probe dynamics for baryon number transport to mid-rapidities at this beam energy. We use both the default and string-melting versions to illustrate how hadronization schemes of quark coalescence and string fragmentations could leave imprints on such correlations. Implications on the measurements of these correlations with the STAR experiment at RHIC will also be discussed. 

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