Effects of initial state fluctuations on the mean transverse momentum

Fernando G. Gardim , Giuliano Giacalone (1) , Matthew Luzum , Jean-Yves Ollitrault (1)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681

We show that in ideal hydrodynamic simulations of heavy-ion collisions, initial state fluctuations result in an increase of the mean transverse momentum of outgoing hadrons, 〈pt〉 . Specifically, 〈pt〉 is larger by a few percent if realistic fluctuations are implemented than with smooth initial conditions, the multiplicity and impact parameter being kept fixed. We show that result can be traced back to the fact that for a given total entropy, the initial energy contained in the fluid is larger if the density profile is bumpy. We discuss the implication of these results for the extraction of the equation of state of QCD from experimental data.

Mots clés: heavy ions; nucleus-nucleus collisions; LHC; equation of state; initial state: fluctuation; quantum chromodynamics: equation of state; heavy ion: scattering; nucleus nucleus: scattering; transverse momentum; boundary condition; impact parameter; hydrodynamics; multiplicity; CERN LHC Coll; fluid; numerical calculations

Domaines: Physique Nucléaire Théorique [nucl-th]; Physique des Hautes Energies - Phénoménologie [hep-ph]; Physique Nucléaire Expérimentale [nucl-ex]

Fernando G. Gardim, Giuliano Giacalone, Matthew Luzum, Jean-Yves Ollitrault. Effects of initial state fluctuations on the mean transverse momentum. 28th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, Nov 2019, Wuhan, China. pp.121999, ⟨10.1016/j.nuclphysa.2020.121999⟩. ⟨hal-02497871⟩