{"title":"Event-by-Event Fluctuation Study in UrQMD Model in Heavy Ion Interactions","authors":"G. Bhoumik","doi":"10.1134/S1547477125702061","DOIUrl":null,"url":null,"abstract":"<p>Event-by-event pseudo-rapidity fluctuations of pions produced in UrQMD-simulated <sup>16</sup>O-AgBr (60 A GeV) and <sup>32</sup>S-AgBr (200 A GeV) interactions has been analyzed using variable ϕ, a variable defined as a measure of fluctuation and it is sensitive to the correlated pion emission in A–A collision. Non-zero ϕ values indicate the presence of correlation among the pions and hence event-by-event fluctuation for both interactions in UrQMD model. Fluctuations, measured using the ϕ parameter, show clear dependence on rapidity zone width and average multiplicity. ϕ increases with zone width, indicating long range correlations, and decreases with multiplicity, suggesting dilution from multiple particle sources. Stronger fluctuations are observed in <sup>32</sup>S-AgBr interactions. While UrQMD captures key trends, it underestimates fluctuation magnitudes compared to experimental data highlighting limitations in modeling ultra-relativistic nucleus-nucleus collisions. Further, UrQMD events show slightly higher correlation and fluctuation than FRITIOF generated events.</p>","PeriodicalId":730,"journal":{"name":"Physics of Particles and Nuclei Letters","volume":"23 2","pages":"174 - 180"},"PeriodicalIF":0.5000,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics of Particles and Nuclei Letters","FirstCategoryId":"1085","ListUrlMain":"https://link.springer.com/article/10.1134/S1547477125702061","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, PARTICLES & FIELDS","Score":null,"Total":0}
引用次数: 0
Abstract
Event-by-event pseudo-rapidity fluctuations of pions produced in UrQMD-simulated 16O-AgBr (60 A GeV) and 32S-AgBr (200 A GeV) interactions has been analyzed using variable ϕ, a variable defined as a measure of fluctuation and it is sensitive to the correlated pion emission in A–A collision. Non-zero ϕ values indicate the presence of correlation among the pions and hence event-by-event fluctuation for both interactions in UrQMD model. Fluctuations, measured using the ϕ parameter, show clear dependence on rapidity zone width and average multiplicity. ϕ increases with zone width, indicating long range correlations, and decreases with multiplicity, suggesting dilution from multiple particle sources. Stronger fluctuations are observed in 32S-AgBr interactions. While UrQMD captures key trends, it underestimates fluctuation magnitudes compared to experimental data highlighting limitations in modeling ultra-relativistic nucleus-nucleus collisions. Further, UrQMD events show slightly higher correlation and fluctuation than FRITIOF generated events.
urqmd模拟的16O-AgBr （60 A GeV）和32S-AgBr （200 A GeV）相互作用中产生的介子的事件-事件伪快速波动使用变量ϕ进行了分析，该变量定义为波动的度量，并且对A -A碰撞中的相关介子发射敏感。非零ϕ值表明π介子之间存在相关性，因此UrQMD模型中两个相互作用的逐个事件波动。使用ϕ参数测量的波动明显依赖于速度、区域宽度和平均多重性。φ随着区域宽度的增加而增加，表明长距离相关性，并随着多重性而减少，表明来自多个粒子源的稀释。在32S-AgBr相互作用中观察到更强的波动。虽然UrQMD捕捉到了关键趋势，但与实验数据相比，它低估了涨落幅度，这突出了在模拟超相对论核-核碰撞方面的局限性。此外，UrQMD事件比FRITIOF生成的事件具有稍高的相关性和波动性。
期刊介绍：
The journal Physics of Particles and Nuclei Letters, brief name Particles and Nuclei Letters, publishes the articles with results of the original theoretical, experimental, scientific-technical, methodological and applied research. Subject matter of articles covers: theoretical physics, elementary particle physics, relativistic nuclear physics, nuclear physics and related problems in other branches of physics, neutron physics, condensed matter physics, physics and engineering at low temperatures, physics and engineering of accelerators, physical experimental instruments and methods, physical computation experiments, applied research in these branches of physics and radiology, ecology and nuclear medicine.
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