$B_c^+$ Formation from Random Charm and Anti-bottom Quarks in the Quark-Gluon Plasma

TL;DR

This paper investigates the production of $B_c^+$ mesons in heavy-ion collisions, demonstrating that coalescence in the quark-gluon plasma enhances their yield and provides evidence for deconfined medium formation.

Contribution

It introduces a combined Langevin and Instantaneous Coalescence Model to quantify $B_c^+$ production in QGP, highlighting the role of coalescence in heavy-ion collisions.

Findings

$B_c^+$ production is enhanced by coalescence in QGP.

The nuclear modification factor $R_{AA}$ exceeds unity.

Model aligns well with experimental data.

Abstract

We study the $B_c^+$ production in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV. In the quark-gluon plasma (QGP) produced in heavy-ion collisions, heavy quarks make random motions with the energy loss. We employ the Langevin equations to study the non-equilibrium distributions of heavy quarks and the Instantaneous Coalescence Model (ICM) to study the hadronization process. Due to abundant charm and bottom quarks in the QGP, their coalescence probability is significantly enhanced compared with the situations in proton-proton collisions. We find that the final production of $B_c^+$ is increased by the coalescence process, which makes the nuclear modification factor ($R_{AA}$) of $B_c^+$ larger than the unit. Our model explains the experimental data well at semi-central and central collisions. The observation of $R_{AA}(B_c^+)>1$ is regarded as an evident and strong signal of the existence of the deconfined medium generated in heavy-ion collisions.