Heavy quark radiation in the quark–gluon plasma in the Moliere theory: angular distribution of the radiation

We study the effects of adding the Coulomb interactions to the harmonic oscillator (HO) approximation of the heavy parton propagating through the quark–gluon plasma (the extension to QCD of the Molliere theory). We explicitly find the expression for the transverse momentum distribution of the gluon radiation of the heavy quark propagating in the quark gluon plasma in the framework of the Moliere theory, taking into account the BDMPSZ radiation in the HO approximation, and the Coulomb logarithms described by the additional logarithmic terms in the effective potential. We show that these Coulomb logarithms significantly influence the HO distribution, derived in the BDMPSZ works, especially for the small transverse momenta, filling the dead cone, and reducing the dead cone suppression of the heavy quark radiation (dead cone effect). In addition we study the effect of the phase space constraints on the heavy quark energy loss, and argue that taking into account of both the phase space constraints and of the Coulomb gluons reduces the dependence of the heavy quark energy loss on its mass in the HO approximation.

Measurement of D-meson production and flow in Pb–Pb collisions with ALICE at the LHC

Open-charmed mesons are unique tools to study the properties of the Quark–Gluon Plasma (QGP) formed in ultra-relativistic nucleus–nucleus collisions. The nuclear modification factor ([Formula: see text]) and elliptic flow ([Formula: see text]) of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] mesons were measured by the ALICE Collaboration in Pb–Pb collisions at [Formula: see text]. The D-meson [Formula: see text] provides information on the charm-quark interactions with the medium and the charm-quark energy loss. The D-meson elliptic flow at low transverse momentum ([Formula: see text]) gives insight into the participation of charm quarks in the collective expansion of the system and their possible in-medium thermalization. At high [Formula: see text], the [Formula: see text] is sensitive to the path-length dependence of parton energy loss. The role of the recombination mechanism is investigated measuring the [Formula: see text]-differential yield ratios between D-meson species with and without strange-quark content. Finally, the coupling of charm quarks to light quarks of the underlying medium is examined applying the Event-Shape Engineering (ESE) technique to the nonstrange D-meson elliptic flow.

Effect of back reaction on light quark energy loss in heavy quark cloud

We study the effect of back reaction on the energy loss of light quarks in strongly coupled $${\mathcal {N}}=4$$ N = 4 supersymmetric Yang–Mills (SYM) plasma, by using the AdS/CFT correspondence. We perform the analysis within falling string and shooting string approaches, respectively. It is shown that the back reaction, arising from the presence of static heavy quarks uniformly distributed over SYM, enhances the energy loss, in agreement with the findings of the drag force and jet quenching parameter.

Heavy quark energy loss in the quark-gluon plasma in the Moller theory

We study the energy loss of a heavy quark propagating in the quark-gluon plasma (QGP) in the framework of the Moller theory, including possible large Coulomb logarithms as a perturbation to BDMPSZ bremsstrahlung, described in the harmonic oscillator (HO) approximation. We derive the analytical expression that describes the energy loss in the entire emitted gluon frequency region. In the small frequencies region, for angles larger than the dead cone angle, the energy loss is controlled by the BDMPSZ mechanism, while for larger frequencies it is described by N = 1 term in the GLV opacity expansion. We estimate corresponding quenching rates for different values of the heavy quark path length and different m/E ratios.

Effect of gluon condensate on light quark energy loss

Applying the AdS/CFT correspondence, we study the jet quenching of light quarks traversing in a deformed AdS background with backreaction due to the gluon condensate. We perform the analysis using the falling string and shooting string cases, respectively. It is found that the two methods lead to a unanimous conclusion: the inclusion of the gluon condensate enhances the energy loss. In particular, the energy loss decreases as the value of the gluon condensate decreases in the deconfined phase, and at high temperature, it is nearly not modified by the gluon condensate, in agreement with the findings of the jet quenching parameter and drag force.