Charm-strange meson production in relativistic heavy ion collisions

TL;DR

The paper addresses how charm-strange hadrons form in a quark-gluon plasma created in heavy-ion collisions at $\sqrt{s_{NN}}=5.02$ TeV, by applying a covariant coalescence framework that connects strange and charm quark $p_T$ spectra—extracted from ALICE data on $\phi$ and $D^0$—to the production of $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$. It computes the $p_T$ distributions and yields for these states, including feed-down and fragmentation, and compares them to ALICE measurements and SHMc predictions, highlighting the role of strangeness enhancement and charm conservation. A key result is that the measured $D_s$ spectrum is reproduced reasonably well, with the $D_s$ yield closely matching data while the thermal-equilibrium yields overpredict the measurements; the study also shows a pronounced difference in yields between a two-quark and a four-quark structure for $D_{s0}^*(2317)$, suggesting a potential experimental discriminator of its internal composition. Overall, the work provides a quantitative framework to probe hadronization dynamics and the quark-content of exotic charm-strange states in the QGP environment.

Abstract

We study charm-strange mesons, or $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons by focusing on their production by coalescence from a quark-gluon plasma in relativistic heavy ion collisions at $\sqrt{s_{NN}}=5.02$ TeV. Starting from the investigation of the transverse momentum distribution of both charm and strange quarks through transverse momentum distributions of $φ$ and $D^0$ mesons, we calculate the transverse momentum distributions and yields of $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons based on the coalescence model. We find that the yield and transverse momentum distribution of the $D_s$ meson agree well with the experimental measurements at $\sqrt{s_{NN}}=5.02$ TeV at LHC. We further evaluate the transverse momentum ratio between $D_s$ and $D^0$ mesons, and investigate the role of light and strange quarks in the production of charmed mesons in heavy ion collisions. Finally, we calculate the transverse momentum distribution and yield of the $D_{s0}^*(2317)$ meson in a four-quark state, and compare to those of $D_{s0}^*(2317)$ meson in a two-quark state.

Figures (5)

• Figure 1: Transverse momentum distribution of the $\phi$ meson, $dN_{\phi}/dp_T$ at mid-rapidity at $\sqrt{s_{NN}}=5.02$ TeV together with the measurement of the $\phi$ meson at the same LHC energy by ALICE Collaboration ALICE:2019xyr.
• Figure 2: Transverse momentum distribution of $D^0$ mesons at mid-rapidity, $dN_{D^0}/dp_T$ at the LHC $\sqrt{s_{NN}}=5.02$ TeV energy together with the experimental measurement of that by ALICE Collaboration ALICE:2021rxa at 0-10$\%$ centrality in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV. Also shown are transverse momentum distributions of $D^0$ mesons produced purely by coalescence and also by fragmentation. Here, feed-down contributions to the production of $D^0$ mesons, Eq. (\ref{['feeddownD0']}) have been taken into account.
• Figure 3: (a) Transverse momentum distributions of $D_s$, $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons at mid-rapidity, $dN/dp_T$ at $\sqrt{s_{NN}}=5.02$ TeV and (b) transverse momentum distribution of $D_s$ mesons, $dN_{D_s}/dp_T$ at mid-rapidity at $\sqrt{s_{NN}}=5.02$ TeV with that of the $D_s$ meson measured at the same rapidity range and energy by ALICE Collaboration ALICE:2021kfc. For the transverse momentum distribution of the $D_s$ meson, the feed-down contribution from $D_s^*$, $D_{s0}^*(2317)$, and $D_{s1}(2460)$ mesons to the $D_s$ as well as the production of $D_s$ meson by fragmentation from the remaining charm quarks, Eq. (\ref{['feeddown']}) have been taken into account.
• Figure 4: Transverse momentum distribution ratio between $D_s$ and $D^0$ mesons, $(dN_{D_s}/dp_T)/(dN_{D^0}/dp_T)$ at mid-rapidity in $0-10\%$ centrality at $\sqrt{s_{NN}}=5.02$ TeV at LHC. Also shown is the same transverse momentum distribution ratio between $D_s$ and $D^0$ mesons measured by ALICE Collaboration at $\sqrt{s_{NN}}=5.02$ TeV at LHC ALICE:2021kfc.
• Figure 5: (a) Transverse momentum distributions of $D_{s0}^*(2317)$ mesons in a two- and four-quark state, $dN_{D_{s0}^*(2317)}/dp_T$ at mid-rapidity in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV. (b) Transverse momentum distribution ratios between $D_{s0}^*(2317)$ and $D_s$, ($dN_{D_{s0}^*(2317)}/dp_T$) /($dN_s/dp_T$) for the $D_{s0}^*(2317)$ in a two- and four-quark state.