Thermalization of heavy quarks in the quark-gluon plasma

Abstract

Charm-and bottom-quark rescattering in a quark-gluon plasma (QGP) is investigated with the objective of assessing the approach toward thermalization. Employing a Fokker-Planck equation to approximate the collision integral of the Boltzmann equation we augment earlier studies based on perturbative parton cross sections by introducing resonant heavy-light quark interactions. The latter are motivated by recent QCD lattice calculations that indicate the presence of "hadronic" states in the QGP. We model these states by colorless (pseudo-) scalar and (axial-) vector D and B mesons within a heavy-quark effective theory framework. We find that the presence of these resonances at moderate QGP temperatures substantially accelerates the kinetic equilibration of c quarks as compared to using perturbative interactions. We also comment on consequences for D-meson observables in ultrarelativistic heavy-ion collisions.

Collisional dissociation of heavy mesons in dense QCD matter

“…The cause of this disagreement is readily identified with the small quenching of B-mesons, which dominate the high-p T single electron yields. Similar results have been * Electronic address: azfar@phys.columbia.edu † Electronic address: ivitev@lanl.gov found in a Langevin approach to heavy quark diffusion where strong heavy quark interactions with D-and B-resonances near the phase transition have been assumed [15,16]. The model for predicting the quenched hadron spectra in A + A collisions, where final-state in-medium effects are important, has been very simple: it is assumed that the hard jet hadronizes in vacuum, having fully traversed the region of dense nuclear matter, L QGP T ≤ 6 fm, and lost energy via radiative and collisional processes.…”

Measurements ofD0andD*production inp+pcollisions atAdamczyk1, Agakishiev2, Aggarwal3 et al. 2012Phys. Rev. D14281240View full textAdd to dashboardCite

“…Thus they carry clean information from the system at the early stage. The interaction between heavy quarks and the medium is sensitive to the medium dynamics, therefore heavy quarks are suggested as an "ideal" probe to quantify the properties of the strongly interacting QCD matter [4][5][6]. Consequently, measurements of heavy-quark production over a wide transverse momentum (p T ) region in proton-proton (p + p) collisions are critical to provide a baseline for understanding the results from heavy-ion collisions.…”

Charmed hadrons from strangeness-rich QGP

“…These heavy flavor quarks participate in the evolution of the dense QCD matter from the beginning. In view of the recent RHIC results it can be hoped that their momentum distribution could reach approximate thermalization within the dense QGP phase [3].…”