System-size scan of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>D</mml:mi></mml:math> meson <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>R</mml:mi><mml:mrow><mml:mi>A</mml:mi><mml:mi>A</mml:mi></mml:mrow></mml:msub></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:math> using PbPb, XeXe, ArAr, and OO collisions at energies available at the CERN Large Hadron Collider

Abstract

Experimental measurements indicate no suppression (e.g., ${R}_{\text{p}\text{Pb}}\ensuremath{\approx}1$) but a surprisingly large $D$ meson ${v}_{2}$ was measured in $p+\mathrm{Pb}$ collisions. In order to understand these results, we use Trento $+\text{v-usp}\text{hydro}+dab\ensuremath{-}mod$ with event-by-event realistic hydrodynamic background to make predictions and propose a system size scan at the Large Hadron Collider (LHC) involving $^{208}\mathrm{PbPb}, ^{129}\mathrm{XeXe}, ^{40}\mathrm{ArAr}$, and $^{16}\mathrm{OO}$ 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 nontrivial 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 ${p}_{\text{T}}=2--10\phantom{\rule{0.28em}{0ex}}\mathrm{GeV}$ to the slight deformation of $^{129}\mathrm{Xe}$ recently found at the LHC.

Topics & Concepts