Elliptic anisotropy of open-charm hadrons from parton scatterings in p--Pb collisions at energies available at the CERN Large Hadron Collider

Abstract

The elliptic azimuthal anisotropy coefficient ($v_{2}$) of open-charm hadron at midrapidity ($|\eta<1|$) was studied in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV using a multi-phase transport (AMPT) model included an additional charm quark--antiquark pair production trigger. The model provides a simultaneously description of the measured $p_{\mathrm{T}}$ spectrum and $v_{2}$ of $D^{0}$ meson, as well as the $v_{2}$ of light flavor meson $K_{s}^{0}$. We found that the $D^{0}$ and $K_{s}^{0}$ $v_{2}$ are both significantly affected by different parton scatterings among charm and light quarks. In addition, the predictions for the $v_{2}$ of other charm hadrons including $D^{+}$, $D_{s}^{+}$ and $\Lambda_{c}^{+}$ in p--Pb collisions are given for the first time. The $v_{2}$ of open-charm hadron reasonably follows the number-of-constituent-quark (NCQ) scaling up to 2.5 GeV, strongly indicating the importance of partonic degrees of freedom for the collectivity of heavy flavors in high-multiplicity p--Pb collisions. These findings may hint the formation of deconfined matter in small collision systems, and provide referential value for future measurements of azimuthal anisotropy at the LHC energies.