Sep 6 – 8, 2018
Max Planck Institute for Astrophysics (MPA)
Europe/Berlin timezone

Hydrodynamic Collectivity in Proton–Proton Collisions at 13 TeV

Sep 8, 2018, 10:05 AM
E.0.11 (Max Planck Institute for Astrophysics (MPA))


Max Planck Institute for Astrophysics (MPA)

Karl-Schwarzschild-Str. 1 85748 Garching
Small systems Small Systems


Huichao Song


In this paper, we investigate the hydrodynamic collectivity in proton–proton (p–p) collisions at 13 TeV, using vishnu hybrid model with hijing initial conditions. With properly tuned parameters, our model simulations can remarkably describe all the measured 2-particle correlations, including integrated and differential elliptic flow coefficients for all charged and identified hadrons ($K_S^0$, $\Lambda$). However, our model calculations show positive 4-particle cumulant $c_{2}\{4\}$ in high multiplicity pp collisions, and can not reproduce the negative $c_{2}\{4\}$ measured in experiment. Further investigations on the \hijing\ initial conditions show that the fluctuations of the second order anisotropy coefficient $\varepsilon_{2}$ increases with the increase of its mean value, which leads to a similar trend of the flow fluctuations. For a simultaneous description of the 2- and 4- particle cumulants within the hydrodynamic framework, it is required to have significant improvements on initial condition for pp collisions, which is still lacking of knowledge at the moment.

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