分类： 物理学 >> 核物理学 提交时间： 2025-01-19
摘要： In this work, we perform a systematic study on the multiplicity dependence of hadron productions at mid-rapidity (|y|<0.5), ranging from the light to the charm sector in pp collisions at \sqrt{s}=13 TeV. This study utilizes a multi-phase transport model (AMPT) coupled with PYTHIA8 initial conditions. We have investigated the baryon to meson ratios as well as the strange to non-strange meson ratios varying with the charged particle density. By tuning the coalescence parameters, the AMPT model provides a reasonable description to the experimental data for inclusive productions of both light and charm hadrons, comparable to the string fragmentation model calculations with color reconnection effects. Additionally, we have analyzed the relative production of hadrons by examining self-normalized particle ratios as a function of the charged hadron density. Our findings suggest that parton evolution effects and the coalescence hadronization process in AMPT model lead to a strong flavor hierarchy in the multiplicity dependence of the baryon to meson ratio. Furthermore, our investigation on the p_T differential double ratio of baryon to meson fraction between high and low multiplicity events indicates distinct modifications to the flavor associated baryon to meson ratio p_T shape in high multiplicity events when comparing the coalescence hadronization model to the color reconnection model. These observations highlight the importance of understanding the hadronization process in high-energy proton-proton collisions through a comprehensive multiplicity dependent multi-flavor analysis.
分类： 物理学 >> 核物理学 提交时间： 2025-01-04
摘要： In this work, we perform a systematic study on the multiplicity dependence of hadron productions at mid-rapidity (|y|<0.5), ranging from the light to the charm sector in pp collisions at \sqrt{s}=13 TeV. This study utilizes a multi-phase transport model (AMPT) coupled with PYTHIA8 initial conditions. We have investigated the baryon to meson ratios as well as the strange to non-strange meson ratios varying with the charged particle density. By tuning the coalescence parameters, the AMPT model provides a reasonable description to the experimental data for inclusive productions of both light and charm hadrons, comparable to the string fragmentation model calculations with color reconnection effects. Additionally, we have analyzed the relative production of hadrons by examining self-normalized particle ratios as a function of the charged hadron density. Our findings suggest that parton evolution effects and the coalescence hadronization process in AMPT model lead to a strong flavor hierarchy in the multiplicity dependence of the baryon to meson ratio. Furthermore, our investigation on the p_T differential double ratio of baryon to meson fraction between high and low multiplicity events indicates distinct modifications to the flavor associated baryon to meson ratio p_T shape in high multiplicity events when comparing the coalescence hadronization model to the color reconnection model. These observations highlight the importance of understanding the hadronization process in high-energy proton-proton collisions through a comprehensive multiplicity dependent multi-flavor analysis.
分类： 物理学 >> 核物理学 提交时间： 2024-07-17
摘要： We present a theoretical study of the medium modifications on the p_T balance (x_J) of dijets in Xe+Xe collisions at sqrt{s_{NN}} = 5.44 TeV. The initial production of dijets is carried out by the POWHEG+PYTHIA8 prescription, which matches the next-to-leading order (NLO) QCD matrix elements with the parton shower (PS) effect. The in-medium evolution in nucleus-nucleus collisions is described by the SHELL model with a transport approach. The theoretical results of the dijet x_J in Xe+Xe collisions exhibit more imbalanced distributions than that in p+p, consistent with the recently reported ATLAS data. By utilizing the Interleaved Flavor Neutralisation, an infrared-and-collinear-safe jet flavor algorithm, to identify the flavor of the reconstructed jets, we classify dijets processes into three categories: gluon-gluon (gg), quark-gluon (qg) and quark-quark (qq), and investigate the respective medium modification patterns and fraction changes of the gg, qg, and qq components of the dijet sample in Xe+Xe collisions. It is shown that the qg component plays a key role in the increased imbalance of the dijet x_J , and especially the q_1g_2 (quark-jet-leading) dijets experience more significant asymmetric energy loss than the g_1q_2 (gluon-jet-leading) dijets as traversing the QGP. By comparing the ∆⟨x_J⟩ of inclusive, ccbar and bbbar dijets in Xe+Xe collisions, we observe ∆⟨x_J⟩_{incl.} > ∆⟨x_J⟩_{ccbar} > ∆⟨x_J⟩_{bbbar}. Moreover, ρ_{Xe,Pb}, the ratios of nuclear modification factors of dijets in Xe+Xe to that in Pb+Pb, are calcualted, which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe due to the larger radius of the lead nucleus.
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