Elliptic flow in small systems due to elliptic gluon distributions?

Yoshikazu Hagiwara,Yoshitaka Hatta,Bo-Wen Xiao,Feng Yuan

doi:10.1016/j.physletb.2017.05.083

Yoshikazu Hagiwara, Yoshitaka Hatta + Show 2 more

Open Access

https://doi.org/10.1016/j.physletb.2017.05.083

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Abstract

We investigate the contributions from the so-called elliptic gluon Wigner distributions to the rapidity and azimuthal correlations of particles produced in high energy pp and pA collisions by applying the double parton scattering mechanism. We compute the ‘elliptic flow’ parameter v2 as a function of the transverse momentum and rapidity, and find qualitative agreement with experimental observations. This shall encourage further developments with more rigorous studies of the elliptic gluon distributions and their applications in hard scattering processes in pp and pA collisions.

Highlights

One of the interesting experimental observations from the proton–proton and proton–nucleus collisions at the Large HadronCollider (LHC) and Relativistic Heavy Ion Collider (RHIC) is the long range rapidity and azimuthal angle correlations between hadrons [1,2,3,4,5,6,7,8,9], see, e.g., a recent review in Ref. [10]
Since the impact parameters for the two hard scatterings are correlated due to the double parton scattering (DPS) mechanism, we expect the transverse momenta from the two hard scatterings are correlated as well
We have explored the two-particle productions in small systems created in high energy pp and p A collisions from the double parton scattering mechanism, where the elliptic gluon

Summary

Introduction

Collider (LHC) and Relativistic Heavy Ion Collider (RHIC) is the long range rapidity and azimuthal angle correlations between hadrons [1,2,3,4,5,6,7,8,9], see, e.g., a recent review in Ref. [10]. We investigate the contribution from the double parton scattering (DPS) [34,35] coupled with the so-called elliptic gluon Wigner distribution [36,37,38]. We expect the DPS, or in general, the multi-parton scattering, is the dominant source for multi-particle productions. [39] that the DPS plays an important role in two particle production in forward p A and d A collisions at RHIC This idea was followed up in the saturation formalism in Ref. Since the impact parameters for the two hard scatterings are correlated due to the DPS mechanism, we expect the transverse momenta from the two hard scatterings are correlated as well This will naturally give rise to the cos(2φ) two-particle correlation in the final state.

Double parton scattering contributions in the dilute-dense collisions

Model calculation

Conclusions and discussions