Joint Discovery - HET seminar – University of Copenhagen

Joint Discovery - HET seminar

Speaker: Konrad Tywoniuk

Title: Jet modifications in heavy-ion collisions dictated by color coherence

Abstract: The modification of jets in heavy-ion collisions, a phenomenon
commonly called "jet quenching", is one of the main tools to determine
the properties of the QCD matter created under these extreme
conditions. In vacuum, jets are precisely described within
perturbative QCD and can therefore serve as well-calibrated and highly
versatile probes. Their description relies heavily on the phenomenon
of color coherence, which introduces an ordering of subsequent
emissions that reduces the complexity of these multi-particle
processes. We will describe how the presence of a hot and dense
background field alters the jet by de-cohering particles in the
cascade and inducing additional soft radiation. These effects are
governed by one, common medium resolution scale, related to the
dynamical transport properties of the plasma, which competes with the
intrinsic jet scales in the course of the evolution. This scale allows
us to rearrange the jet shower into effective charges that are
sensitive to medium effects which, nevertheless, leave their internal
structure unaffected. In particular, we explore the potential of
measuring high-energy, collimated jets in Pb+Pb collisions at the LHC
and discuss directions for establishing a jet calculus in medium.