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

Abstract

The asymmetric initial geometry in p + 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 + Pb collisions at √ s N N = 5.02 TeV. The pseudorapidity density ( d N / d η ) 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 + 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 + Pb collisions.