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

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 root s(NN) = 5.02 TeV. The pseudorapidity density (dN/d 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 + 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.

Automated summary

The study using the multiphase transport (AMPT) model in p + Pb collisions shows that the pseudorapidity density and elliptic flow of light quark particles agree reasonably with measurements by ALICE. Predictions were also made regarding the directed flow of light and heavy quarks in these collisions, showing a significant difference in magnitude between heavy and light quark species. The results suggest that the v(1) values of light and heavy quarks may be used to probe the initial matter density and collective dynamics in p + Pb collisions.