Probing the profile of bulk matter in p+Pb collisions via directed flow of heavy quarks

Md Rihan Haque,Bedangadas Mohanty,Subhash Singha

doi:10.1103/physrevc.104.024901

Abstract

The asymmetric initial geometry in $p+\text{Pb}$ collisions provide an opportunity to probe the initial matter distribution in these collisions. Using a multiphase transport (AMPT) model, we have studied the production of light and heavy quark particles in $p+\text{Pb}$ collisions at $\sqrt{{s}_{NN}}$ = 5.02 TeV. The pseudorapidity density $(dN/d\ensuremath{\eta})$ and elliptic flow $({v}_{2})$ of light quark particles from AMPT reasonably agrees with the measurements by ALICE. We predicted the directed flow of light and heavy quarks in $p+\text{Pb}$ collisions. The ${v}_{1}$ of both light and heavy quark mesons show a nontrivial ${p}_{T}$ dependence in $p$- and Pb-going directions. When integrated over the transverse momentum range 0 $<{p}_{T}<5$ GeV/c, the magnitude of heavy quark directed flow $({v}_{1})$ is found to be 15 times larger than the light quark species in the Pb-going direction while the same in the $p$-going direction are comparable. The light and heavy quarks ${v}_{1}$ may offer the possibility to probe the initial matter density as well as the collective dynamics in $p+\text{Pb}$ collisions.

Highlights

Relativistic heavy-ion collision (A + A) experiments are performed to understand the formation and evolution of a strongly interacting matter, called quark gluon plasma (QGP) [1]
The recent measurement of high multiplicity events in p + A collisions at both Large Hadron Collider (LHC) and Relativistic Heavy Ion Collider (RHIC) energies reveal a strikingly similar collective behavior as those observed in A + A collisions at comparable multiplicities [3,4,5,6]
We observe that a multiphase transport (AMPT)-SM moderately captures the feature in the data

Summary

INTRODUCTION

Relativistic heavy-ion collision (A + A) experiments are performed to understand the formation and evolution of a strongly interacting matter, called quark gluon plasma (QGP) [1]. [16,17] that the heavy quark directed flow (v1) can be used as a probe for the longitudinal profile of the bulk matter distribution. The STAR experiment at RHIC observed about 25 times larger magnitude of v1 slope for the D0 mesons compared to the charged kaons [18] These measurements provide vital information about the geometry of the matter distribution in the longitudinal direction in heavy-ion collisions, i.e., the tilting of bulk medium with respect to the colliding beam direction (z direction). We would like to probe the initial distribution of the bulk medium in p + Pb collisions via the directed flow of light and heavy quark particles.

THE AMPT MODEL

RESULTS AND DISCUSSION

SUMMARY AND CONCLUSION