Hydrodynamic collectivity in proton–proton collisions at 13 TeV

Abstract

In this paper, we investigate the hydrodynamic collectivity in proton-proton (p-p) collisions at 13 TeV, using iEBE-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 0 S , Λ). However, our model calculations show positive 4-particle cumulant c2{4} in high multiplicity pp collisions, and can not reproduce the negative c2{4} measured in experiment. Further investigations on the HIJING initial conditions show that the fluctuations of the second order anisotropy coefficient ε2 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.

Spectra and flow of light nuclei in relativistic heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

“…[22,23], we calculate v 2 (p T ) using the event-plane method with particle of interest (POIs) and reference particles (RPs) selected from two sub-events with their pseudorapidity η taken within −1.0 < η < 0 and 0 < η < 1.0, respectively. It is seen that the iEBE-VISHNU hybrid model with AMPT initial conditions and other tuned parameters [38,39] gives an overall quantitative description of v 2 (p T ) of protons below 2.5 GeV but becomes increasingly larger than the data as the proton momentum increases, where the hydrodynamic approach becomes not applicable. The elliptic flow of deuterons and helium-3 from the coalescence model using the phase-space distri- [44].…”

“…During the past few years, iEBE-VISHNU has been widely used to study various soft physics at RHIC and LHC, and this has led to many nice descriptions and predictions of various flow data, including flow harmonics, flow distributions, symmetric cumulants, event plane correlations, etc. [27,[36][37][38][39][40][41][42]. In particular, the iEBE-VISHNU hybrid model with AMPT initial conditions has successfully described and predicted the spectra and flow harmonics of pions, kaons and protons in Pb+Pb collisions at √ s N N = 2.76 and 5.02…”

Unified description of hadron yield ratios from dynamical core-corona initialization

“…[6,7]). One of those data shows sizable azimuthal anisotropy in final hadron distributions [8][9][10][11][12][13][14], which can be interpreted as a result of the hydrodynamic response of the QGP medium to the initial collision geometry [15][16][17][18][19][20][21][22]. Although this has been discussed actively from relativistic hydrodynamics, another interpretation is brought about also by the color glass condensate picture, which gives long-range correlation in rapidity in small colliding systems without invoking the QGP formation [23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

Investigations of Anisotropic Flow Using Multiparticle Azimuthal Correlations in pp , p−Pb , Xe-Xe, and Pb-Pb Collisions at the LHC

“…Whether the observed similarities between small (pp and p-A) and large (A-A) collision systems arise from the same physics mechanism is under intense debate. Besides hydrodynamic descriptions [29][30][31][32][33], calculations from transport models [34][35][36], hadronic rescattering [37,38], a string rope and shoving mechanism [39], as well as initial stage effects [40][41][42] have been investigated.…”