Effective Field Theory for jet substructure in heavy ion collisions

I develop an Effective Field Theory (EFT) framework to compute jet substructure observables for heavy ion collision experiments. As an example, I consider dijet events that accompany the formation of a weakly coupled long lived Quark Gluon Plasma (QGP) medium in a heavy ion collision and look at an observable insensitive to jet selection bias: the simultaneous measurement of jet mass along with the transverse momentum imbalance between the jets that are groomed to remove soft radiation. Treating the jet as an open quantum system, I write down a factorization formula within the SCET (Soft Collinear Effective Theory) framework in the forward scattering regime. The physics of the medium is encoded in a universal soft field correlator while the jet-medium interaction is captured by a medium induced jet function. The factorization formula leads to a Lindblad type equation for the evolution of the reduced density matrix of the jet in the Markovian approximation. The solution for this equation allows a resummation of large logarithms that arise due to the final state measurements imposed while simultaneously summing over multiple incoherent interactions of the jet with the medium.

Automated summary

The author developed an Effective Field Theory (EFT) framework to compute jet substructure observables for heavy ion collision experiments, focusing on a dijet system accompanying the formation of a weakly coupled long lived Quark Gluon Plasma (QGP) medium. By treating the jet as an open quantum system, the author derived a factorization formula within the SCET framework to study the evolution and interaction of the jet within the medium. This factorization formula led to a Lindblad type equation for the reduced density matrix of the jet, allowing a resummation of large logarithms and summing over multiple incoherent interactions with the medium.