RBRC Seminar

Abstract: 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 TMD gluon distributions that encode information on the 3D structure of the proton and nuclei in electron-proton or proton-proton collisions to jet suppression in heavy ion collisions.
In this talk, I study the leading quantum corrections to the TMB distribution of high energy partons in large QCD media. I show that the resummation to all orders of double logarithmic contributions from gluon radiation in the presence of a saturation boundary yields a universal distribution for large system sizes. This universal distribution exhibits anomalous scaling of super diffusive type, in contrast with normal diffusion seen at tree level, and a heavy tail at large transverse momentum, akin to Lévy random walks.
Exploiting a formal analogy with traveling waves in reaction-diffusion processes, the universal pre-asymptotic solutions for fixed and running coupling are derived. I finally discuss possible applications to small-x and jet quenching phenomenology. In particular, I argue that our formulas can provide a model-independent functional form for the initial condition of the BK-JIMWLK evolution equations.