Seminar in Hadronic Physics

Anomalous diffusion in QCD matter

Yacine Mehtar-Tani

Brookhaven National Laboratory

Transverse momentum broadening (TMB) of energetic partons in QCD matter plays a central role in a variety of processes studied at colliders to probe QCD ranging from jet suppression in heavy ion collisions (HIC) to TMD gluon distributions that encode information on the 3D structure of the proton and nuclei in electron-proton or proton-proton collisions. I will discuss in this talk the leading quantum corrections to the TMB distribution of fast partons in large QCD media. I will show in particular that the resummation to all order of double logarithmic contributions from gluon radiation in the presence of a saturation boundary yields a universal distribution and exhibits anomalous scaling of super diffusive type in contrast with normal diffusion seen at tree level. Exploiting a formal analogy with traveling waves in reaction-diffusion processes and gluon saturation exact analytic results for fixed and running coupling are derived. This remarkable anomalous scaling caused by nonlocal quantum corrections is reflected at large transverse momentum by the emergence of a heavy tail, akin to Lévy random walks, which may have measurable effects in dijet processes in HIC.