Nuclear modification factor of D$^0$ mesons in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

TL;DR

This paper measures the production of D0 mesons in proton-proton and lead-lead collisions at 5.02 TeV, revealing significant suppression in lead-lead collisions at certain transverse momenta, which informs understanding of quark-gluon plasma effects.

Contribution

First measurement of D0 meson nuclear modification factor at 5.02 TeV in PbPb collisions, providing new insights into heavy quark energy loss in quark-gluon plasma.

Findings

D0 meson production is suppressed in central PbPb collisions at 6-10 GeV pT.

Suppression decreases at higher pT, with less suppression observed at 60-100 GeV.

Results agree with some theoretical models of parton energy loss.

Abstract

The transverse momentum ($p_\mathrm{t}$) spectrum of prompt D$^0$ mesons and their antiparticles has been measured via the hadronic decay channels D$^0 \to \mathrm{K}^- \pi^+$ and $\overline{\mathrm{D}}^0 \to \mathrm{K}^+ \pi^-$ in pp and PbPb collisions at a centre-of-mass energy of 5.02 TeV per nucleon pair with the CMS detector at the LHC. The measurement is performed in the D$^0$ meson $p_\mathrm{t}$ range of 2-100 GeV and in the rapidity range of $|y| < $1. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 27.4 pb$^{-1}$ (530 $\mu$b$^{-1}$). The measured D$^0$ meson $p_\mathrm{t}$ spectrum in pp collisions is well described by perturbative QCD calculations. The nuclear modification factor, comparing D$^0$ meson yields in PbPb and pp collisions, was extracted for both minimum-bias and the 10% most central PbPb interactions. For central events, the D$^0$ meson yield in the PbPb collisions is suppressed by a factor of 5-6 compared to the pp reference in the $p_\mathrm{t}$ range of 6-10 GeV. For D$^0$ mesons in the high-$p_\mathrm{t}$ range of 60-100 GeV, a significantly smaller suppression is observed. The results are also compared to theoretical calculations.