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SUMMARY:Influence of Gaussian and non-Gaussian elementary sources on high-
 order multiplicity cumulants in a toy model of relativistic nucleus-nucleu
 s collisions
DTSTART;VALUE=DATE-TIME:20261028T133500Z
DTEND;VALUE=DATE-TIME:20261028T135000Z
DTSTAMP;VALUE=DATE-TIME:20261023T153903Z
UID:indico-contribution-6299@cern.ch
DESCRIPTION:Speakers: Александр Зарщиков (Saint Petersbur
 g State University)\nA.Zarchikov\, G.A.Feofilov*\n \n         Saint-Peters
 burg University\, St. Petersburg State University\, SPbSU\,\n        SPbU\
 , 7/9 Universitetskaya nab.\, St. Petersburg\, 199034 Russia.\n        *e-
 mail: g.feofilov@spbsu.ru\nHigh-order cumulants of event-by-event multipli
 city distributions are widely used in the search for the QCD critical poin
 t in relativistic heavy-ion collisions. Their sensitivity to non-Gaussian 
 fluctuations [1] makes them promising observables [2]\, but at the same ti
 me they can be strongly affected by non-critical background effects\, in p
 articular by volume fluctuations and by the procedure of centrality class 
 selection[3].\n\nIn this work\, we study these effects using a simple toy 
 Monte Carlo model of nucleus-nucleus collisions. The collision geometry is
  described through the impact parameter and the corresponding number of pa
 rticipant nucleons. Particle multiplicity is generated as a superposition 
 of elementary nucleon-nucleon sources. In the first version of the model\,
  the elementary source is assumed to be Gaussian. We show that even in thi
 s case nonzero third- and fourth-order cumulants can appear after selectin
 g events by final-state multiplicity\, due to the admixture of events with
  different collision geometry and different effective volume.\n\nThe model
  is then extended to the inclusion of non-Gaussian elementary sources. Thi
 s allows us to compare two different contributions to high-order cumulants
 : the intrinsic non-Gaussianity of particle production --  in  case of pro
 ximity to the critical point\, and  trivial contribution caused by the vol
 ume fluctuations. Special attention is paid to the comparison of multiplic
 ity-based event -by-event selection of  narrow classes of participating nu
 cleons (Npart).\n\nThe results demonstrate that the measured values of hig
 h-order cumulants may be significantly distorted by centrality and volume 
 fluctuations even in the absence of critical dynamics. Therefore\, careful
  control of the initial geometry and the use of narrow classes of the numb
 er of Npart and relevant reduced cumulants are essential for separating po
 ssible critical-point signals from the non-critical background contributio
 ns.\n\n \nThe authors acknowledge Saint-Petersburg State University for a 
 research project ID: 153212394\n \nReferences:\n[1]. M. A. Stephanov\, Phy
 s. Rev. Lett. 102\, 032301 (2009).\n\n[2]. Hannah Elfner and Berndt Mülle
 r 2023\, J. Phys. G: Nucl. Part. Phys. 50 103001.\n\n[3]. G.Feofilov\, Phy
 s.Part and Nucl.\, 2026\, vol.57\, No.3\, pp 401-406.\n\nhttps://indico.pa
 rticle.mephi.ru/event/626/contributions/6299/
LOCATION:Sevastopol Hotel
URL:https://indico.particle.mephi.ru/event/626/contributions/6299/
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