Measurement of D0 Azimuthal Anisotropy at Midrapidity in Au+Au Collisions at sNN=200 GeV

Le résumé fourni par la source

We report the first measurement of the elliptic anisotropy (${v}_{2}$) of the charm meson ${D}^{0}$ at midrapidity ($|y|<1$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}=200\text{ }\text{ }\mathrm{GeV}$. The measurement was conducted by the STAR experiment at RHIC utilizing a new high-resolution silicon tracker. The measured ${D}^{0}$ ${v}_{2}$ in 0%--80% centrality $\mathrm{Au}+\mathrm{Au}$ collisions can be described by a viscous hydrodynamic calculation for a transverse momentum (${p}_{T}$) of less than $4\text{ }\text{ }\mathrm{GeV}/c$. The ${D}^{0}$ ${v}_{2}$ as a function of transverse kinetic energy (${m}_{T}\ensuremath{-}{m}_{0}$, where ${m}_{T}=\sqrt{{p}_{T}^{2}+{m}_{0}^{2}}$) is consistent with that of light mesons in 10%--40% centrality $\mathrm{Au}+\mathrm{Au}$ collisions. These results suggest that charm quarks have achieved local thermal equilibrium with the medium created in such collisions. Several theoretical models, with the temperature-dependent, dimensionless charm spatial diffusion coefficient ($2\ensuremath{\pi}T{D}_{s}$) in the range of $\ensuremath{\sim}2--12$, are able to simultaneously reproduce our ${D}^{0}$ ${v}_{2}$ result and our previously published results for the ${D}^{0}$ nuclear modification factor.

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