First measurement of the Bc+ meson nuclear modification factor in PbPb collisions with CMS

Guillaume Falmagne,On Behalf Of The Cms Collaboration

doi:10.1051/epjconf/202225912011

Abstract

The Bc+ meson is observed in lead-lead and proton-proton collisions at a center-of-mass energy per nucleon pair of √SNN = 5.02 TeV, via the Bc+ → (J/ψ → μ+μ−)μ+vμ decay and using 2017 and 2018 data from the CMS detector. The resulting Bc+ nuclear modification factor is measured in two bins of the trimuon transverse momentum and of the collision centrality. Less suppression is observed than for other quarkonia and most open heavy flavour mesons. This first observation of the Bc+ meson in heavy ion collisions will shed light on the interplay of suppression and enhancement mechanisms in the production of heavy-flavor mesons in the quark-gluon plasma.

Highlights

The disappearance of quarkonia due to the screening of the heavy-quark potential at high temperature has been considered a signature of the quark-gluon plasma (QGP) formation [1]
While the strong J/ψ suppression observed in heavy-ion collisions at lower energies [2, 3] seems consistent with screening effects, the smaller suppression reported at the Large Hadron Collider [4] points to the recombination of charm quarks in the QGP [5]
Monte Carlo (MC) simulation is used for background studies and for estimating the acceptance and efficiency of the reconstruction and selection

Summary

As the bridge

B+c the meson contains a charm and a beauty quark, measurements of its properties gap between charmonia and bottomonia. + c melting in the QGP is expected to occur between the J/ψ and Υ(1S) dissociation temperatures [7]. Heavy-quark recombination processes could affect the B+c state, with production rates typically scaling linearly with the charm multiplicity in the QGP (contrarily to a quadratic scaling for J/ψ mesons)

It could lead to a large enhancement of the

Comparing the quenching of

Since the

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