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

The elliptic azimuthal anisotropy coefficient (v₂) of open-charm hadron at midrapidity (|η<1|) was studied in p--Pb collisions at √sNN= 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 pT spectrum and v₂ of D⁰ meson, as well as the v₂ of light flavor meson Kₛ⁰. We found that the D⁰ and Kₛ⁰ v₂ are both significantly affected by different parton scatterings among charm and light quarks. In addition, the predictions for the v₂ of other charm hadrons including D⁺, Dₛ⁺ and Λc⁺ in p--Pb collisions are given for the first time. The v₂ 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.