Speaker
Dr
Yacine Mehtar-Tani
(IPhT Saclay)
Description
We study the evolution of a high energy jet triggered by its interactions with a dense QCD medium. We show that the relatively components of the jet which propagate at large angles can be described as the products of a classical branching process, in which successive branchings proceed independently from each other. This exploits the fact that the in-medium rescattering is very efficient in destroying the color coherence between the soft emitted partons: this coherence is washed out already during the branching process, that is, over time scales which are much shorter than the size L of the medium. This allows us to construct a master equation for the generating functional encoding all the intra-jet multi-parton distributions (that is, the distributions in energies and in angles).
The `jet quenching parameter' $\hat q$, which is the only medium-dependent parameter in this description, receives large radiative corrections from a different type of radiation --- namely, from hard gluon emissions which are triggered by a single scattering in the medium and occur on time scales much shorter than the typical branching time alluded to above.These radiative corrections, enhanced by a double logarithm $\alpha_s \log^2 (L T)$ with $T$ the temperature of the medium, are strongly ordered and overlapping in formation time. We show that these coherent branchings can be absorbed into a renormalization of the jet quenching parameter without spoiling the probabilistic picture mentioned above and which involves only incoherent branchings.
arXiv:1209.4585 [hep-ph] JHEP 1301 (2013) 143
arXiv:1307.xxxx [hep-ph] In preparation
Primary authors
Dr
Edmond Iancu
(IPhT Saclay)
Dr
Fabio Dominguez
(IPhT Saclay)
Dr
Jean-Paul Blaizot
(IPhT Saclay)
Dr
Yacine Mehtar-Tani
(IPhT Saclay)
