System size scan of D meson $R_\text{AA}$ and $v_n$ using PbPb, XeXe, ArAr, and OO collisions at LHC

Abstract

Experimental measurements indicate no suppression (e.g. $R_\text{pPb} \sim 1$) but a surprisingly large D meson $v_2$ was measured in pPb collisions. In order to understand these results we use Trento+v-USPhydro+DAB-MOD to make predictions and propose a system size scan at the LHC involving $^{208}$PbPb, $^{129}$XeXe, $^{40}$ArAr, and $^{16}$OO collisions. We find that the nuclear modification factor approaches unity as the system size is decreased, but nonetheless, in the 0-10% most central collisions $v_2\{2\}$ is roughly equivalent regardless of system size. These results arise from a rather non-trivial interplay between the shrinking path length and the enhancement of eccentricities in small systems at high multiplicity. Finally, we also find a surprising sensitivity of D mesons $v_2\{2\}$ in 0-10% at $p_T = 2-10$ GeV to the slight deformation of $^{129}$Xe recently found at LHC.