Energy independent scaling of the ridge and final state description of high multiplicity p+p collisions at s=7 and 13 TeV

Debojit Sarkar

doi:10.1103/physrevd.97.034036

Abstract

An energy independent scaling of the near-side ridge yield at a given multiplicity has been observed by the ATLAS and the CMS collaborations in p+p collisions at s = 7 and 13 TeV. Such a striking feature of the data can be successfully explained by approaches based on initial state momentum space correlation generated due to gluon saturation. In this paper, we try to examine if such a scaling is also an inherent feature of the approaches that employ strong final state interaction in p+p collisions. We find that hydrodynamical modeling of p+p collisions using EPOS 3 shows a violation of such scaling. The current study can, therefore, provide important new insights on the origin of long range azimuthal correlations in high multiplicity p+p collisions at the LHC energies.

Highlights

The long-range ridgelike structure of the azimuthal correlations as observed in the high multiplicity p þ p [1,2] and p þ A collisions [3,4] at the LHC energies shows striking similarity with similar measurements in heavy ion collisions
In heavy ion collisions [5,6,7,8] such long-range correlations are attributed to hydrodynamical response of a strongly interacting system to the initial spatial anisotropy
Simulations based on EPOS 3 which includes event by event 3 þ 1 D hydrodynamic evolution can provide a good explanation of the energy dependence of dNch/dη in p þ p collisions [12], ridge [10,11], mass ordering of the elliptic flow coefficients (v2) of identified particles [11], hardening of spectra with multiplicity and the trend of baryon to meson enhancement at the intermediate transverse momentum in p þ p and p þ Pb collisions at the LHC energies [13,22,23,24,25]

Summary

Introduction

The long-range ridgelike structure of the azimuthal correlations as observed in the high multiplicity p þ p [1,2] and p þ A collisions [3,4] at the LHC energies shows striking similarity with similar measurements in heavy ion collisions. In heavy ion collisions [5,6,7,8] such long-range correlations are attributed to hydrodynamical response of a strongly interacting system to the initial spatial anisotropy. Assuming the applicability of hydrodynamics [18,19,20,21] one can explain several experimental observations in high multiplicity p þ p and p þ Pb collisions at LHC energies [9,10,11,13].

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