低横动量Υ(1S)介子在强子气体中的分布  

Distribution of low-pT Υ(1S)in hadron gas

作　　者：丁慧强 戴婷婷 程鸾 张卫宁[1] 王恩科 Ding Hui-Qiang;Dai Ting-Ting;Cheng Luan;Zhang Wei-Ning;Wang En-Ke(Department of Physics,Dalian University of Technology,Dalian 116024,China;Institute of Quantum Matter,South China Normal University,Guangzhou 510631,China)

机构地区：[1]大连理工大学物理学院,大连116024 [2]华南师范大学量子物质研究院,广州510631

出　　处：《物理学报》2023年第19期86-92,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12175031);广东省核物质科学与技术重点实验室(批准号:2019B121203010)资助的课题。

摘　　要：Υ(1S)是高能重离子碰撞中的干净探针,其研究具有重要意义.强子气体中Υ(1S)的分布受到集体流、量子效应和强相互作用三种效应的影响.此前的模型均只分析了其中一到两种效应而忽略了其他效应,将忽略的效应放入到了拟合参数中.本文从新的视角提出了两体分形模型,从物理计算而非参数拟合的方法开展研究.本文认为Υ(1S)与最相近的介子形成两体结构,与介子内部的两夸克结构具有自相似性.引入环境影响因子qfqs来描述上述三种效应影响;引入伴随因子q2来描述b,b之间的相互作用和上述三种效应的影响.通过求解概率与熵方程,得到不同碰撞条件下qfqs与q2的值.将qfqs代入到分布函数中,得到低横动量区的横动量谱并与实验对比,结果表明理论与实验符合良好.还分析了qfqs随温度的变化关系,并发现qfqs>1,这是由环境效应减少了Υ(1S)的微观状态数所致.另外,计算显示qfqs随着系统温度的降低而减小,这与随着系统膨胀强子气体影响减弱的现象相一致.The Υ(1S)mecon aervea ao a reliable probe in heavy-ion collisiong,ng the regeneration proceaa in the quark-gluon plaoma(QGP)ia negligible compared to J/ψ.Therefore,the diotribution of Υ(1S)in the hadron gao provideo valuable information about the QGP.Consequently,ito otudy holdo great aignificance.The distribution in the hadron ga io influenced by flow,quantum,and strong internction effecta.Previous models have predominantly focused on one or two of theae effecto while neglecting the others,resulting in the inclusion of unconaidered effecta in the fitted parametera.In thio paper,we aim to comprehenoively exarmine all three effecto oimultaneouoly from a novel fractal peropective through phyaical calculationa,rather than relying solely on data fitting.Close to the critical temperature,the combined action of the three effecto leada to the formation of a two-meaon atructure comprioing Υ(1S)and its neareat neighboring mecon.However,with the evolution of the ayotem,moat of these atates undergo disintegration.To describe thio physical process,we establish a two-particle fractal(TPF)model.Our model proposea that,under the influence of the three effecto near the critical temperature,a aelf-oimilarity atruoture emergeo,involving a Υ(1S)-πtwo-meoon aotate and a Υ(1S)-πtwo-quark otate.Ao the oyatem evolves,the two-meaon struoture gradually disintegrates.We introduce an influencing factor,qs,to account for the flow,quantum,and strong internction effecta,80 well 00 an ecort factor,92,to represent the binding force between b and b and the combined impact of the three effecto.By olving the probability and entropy equationo,we derive the valueaof 9qs and q2 at various collision energieo.Subotituting the value of 9fqs into the distribution funotion,we succeoofully obtain the tranovere momentum opectrum of low-pr Υ(1S),which demonstrates good agreement with experimental data.Additionally,we analyze the evolution of 9qs with temperature.Intereatingly,we observe that 9iqs ia greater than 1 and decrensea the temperature decre

关 键 词：横动量谱 分形理论 伴随概率 TSALLIS熵 

分 类 号：O571.6[理学—粒子物理与原子核物理]