Medium modifications to the initial-final coherence pattern

We have recently released a new article where we investigated medium modifications to the color coherence pattern between the initial and final state radiation. All the details of our new work can be found in the link listed below

http://arxiv.org/abs/arXiv:1308.2186

The experimental results of high pT hadrons produced in high energy nuclear collisions at RHIC and LHC requires a correct understanding of the medium modifications to the color coherence among different emitters in a parton branching. These problems have been addressed in a series of papers by studying the antenna radiation. It is natural to study another different configuration relevant from an antenna.

In our new work, we determine analytically the different contributions to the soft gluon spectrum due to a highly energetic parton created in the remote past. This parton suffers a hard scattering and afterwards it crosses a QCD medium of finite size. Within controlled approximations, we show that the presence of a QCD medium indeed modifies the inter- ference pattern among both emitters compared with the vacuum case. We observe that depending on the interplay of the relevant kinematic variables of our problem there is a partial suppression of the interferences either in the coherent or incoherent limit. As a con- sequence, we would observe that both emitters can radiate gluons at large angles and there is a maximal angle completely determined by the medium properties. Our setup might have phenomenological consequences in the dense-dilute regime, e.g., pA collisions.