Monday, January 28, 2013

1301.6102 (Jean-Paul Blaizot et al.)

Medium-induced QCD cascade: democratic branching and wave turbulence    [PDF]

Jean-Paul Blaizot, Edmond Iancu, Yacine Mehtar-Tani
We study the average properties of the cascade of gluons that is generated by an energetic parton propagating through a quark-gluon plasma. We focus on the soft, medium-induced, emissions which control the energy transport at large angles with respect to the leading parton. We show that the effect of multiple branchings are important. In contrast to what happens in a usual QCD cascade in vacuum, medium-induced branchings are quasi-democratic, with offspring gluons carrying sizable fractions of the energy of their parent gluon. This results in a new mechanism for the transport of energy towards the medium, which is akin to wave turbulence with a scaling spectrum $\sim 1/\sqrt{\omega}$. We argue that the turbulent flow may be responsible for the excess energy carried by very soft quanta, as revealed by the analysis of the di-jet asymmetry observed in Pb-Pb collisions at the LHC.
View original: http://arxiv.org/abs/1301.6102

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