Partons and jets at strong coupling from AdS/CFT

TL;DR

This paper uses AdS/CFT correspondence to explore the parton structure and jet behavior in a strongly coupled plasma, revealing unique phenomena like jet suppression and altered particle production patterns.

Contribution

It provides a novel interpretation of parton evolution and jet quenching at strong coupling using holographic duality, contrasting with perturbative QCD predictions.

Findings

Parton cascade down to small x and transverse momenta below saturation scale Q_s.

Absence of jets in electron-proton annihilation at strong coupling.

Suppressed particle production at forward and backward rapidities.

Abstract

Calculations using the AdS/CFT correspondence can be used to unveil the short-distance structure of a strongly coupled plasma, as it would be seen by a `hard probe'. The results of these calculations admit a natural physical interpretation in terms of parton evolution in the plasma: via successive branchings, essentially all partons cascade down to very small values of the longitudinal momentum fraction x and to transverse momenta smaller than the saturation momentum Q_s\sim T/x. This scale Q_s controls the energy loss and the transverse momentum broadening of an energetic jet propagating through the plasma. This picture has some striking consequences, like the absence of jets in electron-proton annihilation at strong coupling, of the absence of particle production at forward and backward rapidities in hadron-hadron collisions, which look very different from the corresponding predictions of perturbative QCD and also from the known experimental situation.