Charm quark and QGP interactions through the spectra and anisotropic flow of D$^0$ over the widest p$_\text{T}$ interval using event-shape engineering at CMS

Abstract

The charm quark is formed almost exclusively during the initial stages of the collision, and a significant fraction of the charm quarks fragment into the $\mathrm{D}^{0}$ meson, the lightest open-charm hadron. We can gain insights into the interactions between the charm quark and the quark-gluon plasma (QGP) medium by studying the production and the flow of the $\mathrm{D}^{0}$ meson in heavy-ion collisions. We study the effect of the initial shape of the collision system on the elliptic flow ($v_{2}$) of promptly produced $\mathrm{D}^{0}$ mesons in the $p_\mathrm{T}$ region $2-30$ GeV/c using event-shape engineering (ESE) in PbPb collisions at 5.02 TeV at the CMS experiment. A correlation between the initial shape anisotropy and the $\mathrm{D}^{0}$ $v_{2}$ would suggest that the flow gets driven by the interactions between the charm quark and the QGP. Comparison with theoretical predictions allows us to unravel the mechanism behind the generation of $v_{2}$. We also study the anisotropic flow of nonprompt $\mathrm{D}^{0}$ produced due to the decay of the bottom quarks and the nuclear modification factor ($\mathrm{R_{AA}}$) for prompt and nonprompt $\mathrm{D}^{0}$. These studies provide further insights into the QGP interactions of heavy quarks like charm and bottom in heavy-ion collisions in different $p_\mathrm{T}$ regions ranging from $1-40$ GeV/c, the widest ever performed with ESE, and centralities between 0--50%.

Figures (3)

• Figure 1: The prompt and nonprompt D0 $v_2$ (upper panels) and $v_3$ (lower panels) as functions of their $p_{\mathrm{T}}$ and in three bins of centrality. The bars and the boxes represent statistical and systematic uncertainties, respectively. This figure is taken from Ref. HIN-21-003.
• Figure 2: Correlation between the normalized D0 $v_2$ and the charged-particle $v_2$. The $v_2$ value in each $q_2$ bin is scaled by the $v_2$ in each centrality bin. The charged-particle $v_2$ is measured in the $p_{\mathrm{T}}$ region 1--3${\,\text{Ge\spaceV\space/\space}c}$. The correlation plots for D0 $p_{\mathrm{T}}$ 2--4 (left), 4--6 (middle), and 6--10 (right) in the centrality class 20-30%. The red band corresponds to the uncertainty of one standard deviation. These figures are taken from Ref. HIN-24-015_PAS
• Figure 3: The slopes (left) and intercepts (right) obtained from the correlation plots of the prompt D0 $v_2$ vs the charged-particle $v_2$ for each $p_{\mathrm{T}}$ and centrality class of D0. For the correlation plots, the $v_2$ in each $q_2$ bin is normalized by the $q_2$-inclusive $v_2$. The vertical lines correspond to the statistical uncertainties, and the vertical bands correspond to the systematic uncertainties added in quadrature. The slopes and intercepts calculated are consistent with unity and zero, respectively. These figures are taken from Ref. HIN-24-015_PAS