Correlations in the Initial Conditions of Heavy-Ion Collisions

Douglas Wertepny, Jacquelyn Noronha-Hostler, Matthew Sievert, Skandaprasad Rao, Noah Paladino

Research output: Contribution to conferencePaperpeer-review


Ultracentral collisions of heavy nuclei, in which the impact parameter is nearly zero, are especially sensitive to the details of the initial state model and the microscopic mechanism for collective flow. In a hydrodynamic “flow” picture, the final state momentum correlations are a direct response to the fluctuating initial geometry, although models of the initial geometry differ widely. Alternatively, dynamical mechanisms based in the color glass condensate (CGC) formalism can naturally lead to many-body correlations with very different systematics. Here we present a calculation of event-by-event elliptic flow in both the hydrodynamic and CGC paradigms and show that they can be qualitatively distinguished in ultracentral collisions of deformed nuclei. Specifically, the multiplicity dependence in such collisions is qualitatively opposite, with the CGC correlations increasing with multiplicity while the hydrodynamic correlations decrease. The consistency of the latter with experimental data on UU collisions appears to rule out a CGC-mediated explanation. We find that these qualitative features also persist in small deformed systems and can therefore be a valuable test of the microscopic physics in that regime.

Original languageEnglish (US)
StatePublished - Jun 16 2020
Event49th International Symposium on Multiparticle Dynamics, ISMD 2019 - Santa Fe, United States
Duration: Sep 9 2019Sep 13 2019


Conference49th International Symposium on Multiparticle Dynamics, ISMD 2019
Country/TerritoryUnited States
CitySanta Fe

ASJC Scopus subject areas

  • Condensed Matter Physics


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