Color coherence in a heavy quark antenna radiating gluons inside a QCD medium

Abstract

We compute the color coherence effects for soft gluon radiation off antennas containing heavy quarks in the presence of a QCD medium -the actual calculations is made for a triplet configuration and then generalize to both color singlet and octet ones. This work completes the studies of antenna radiation inside a medium which provide a useful picture of the relevance of interference effects in jet parton showers for the jet quenching phenomenon observed in high-energy nuclear collisions. The analysis is performed resumming the multiple scatterings of the partonic system with the medium. The main conclusion is that decorrelation due to color rotation is more effective in the case in which at least one of the emitters of the antenna is a heavy quark. This effect, present both for a heavy-quark-antiquark or a heavy-quark-gluon antenna is more relevant for the later or for the case in which the energies of the quark and antiquark are very different. The parameter controlling these effects involves the deadcone angle. We find that interferences are cancelled, spoiling the color correlation of the pair, whenωL where E and ω are the energies of the heavy quark and the radiated gluon and L is the medium length. In the case of a heavy-quark-antiquark antenna t form , defined as the difference in splitting times in amplitude and complex conjugate of the amplitude, appears instead of L if the original splitting is symmetric. The presence or absence of interferences modifies the energy loss pattern.

Higher-order corrections to heavy-quark jet quenching

“…It depends explicitly on the opening angle of the pair, in particular S 2 (t) = 1 for n 2 12 = 0. The formula in (B1) generalizes the result previously obtained in [34]. It is worth pointing out that, due to the Galilean symmetry of the problem, the spectrum does not depend on the directions of the emitters apart from the dipole opening angle n 12 .…”

“…We proceed now with the calculation of the interference spectrum. It was first computed for a color-charged dipole involving a massive quark in [34] but an explicit expression…”

“…We proceed now with the calculation of the interference spectrum. It was first computed for a color-charged dipole involving a massive quark in [34] but an explicit expression is not available in the literature. It is therefore meaningful to rederive the spectrum in more generality here.…”

“…The interference spectrum associated with a massive dipole is given explicitly in Eq. (A9), see also [34], and evaluated in the multiple-soft scattering approximation in Eqs. (B20) and (B21).…”

Theory @ Hard Probes 2013

“…Interestingly, this result is between the BDMPS result L 2 and the strong coupling result L 3 . Several technical improvements were also presented, such as the complete single gluon radiation off a quark, including the in-and out-of-medium emission and their interference (L. Apolinario, [32]) and a study of the effect of the mass of heavy quarks on the destruction of the antenna coherence (M. Calvo, [33]).…”