Inverting the mass hierarchy of jet quenching effects with prompt $b$-jet substructure

TL;DR

This paper proposes a new experimental approach to study how heavy quark masses influence jet quenching in quark-gluon plasma, predicting a reversal of the expected mass hierarchy in jet modifications.

Contribution

It introduces a novel measurement method using prompt $b$-jet substructure to constrain in-medium splitting functions and predicts a unique reversal of the jet quenching mass hierarchy.

Findings

Prompt $b$-jets show stronger modifications than light jets in certain momentum regions.

Reversal of the expected mass hierarchy in jet quenching effects.

Guides experimental efforts at LHC and RHIC.

Abstract

The mass of heavy quarks, such as charm and bottom, plays an important role in the formation of parton showers. This effect is apparently not well understood when parton showers evolve in a strongly interacting quark-gluon plasma. We propose a new experimental measurement in relativistic heavy ion collisions, based on a two-prong subjet structure inside a reconstructed heavy flavor jet, which can place stringent constraints on the mass dependence of in-medium splitting functions. We identify the region of jet transverse momenta where parton mass effects are leading and predict a unique reversal of the mass hierarchy of jet quenching effects in heavy ion relative to proton collisions. Namely, the momentum sharing distribution of prompt $b$-tagged jets is more strongly modified in comparison to the one for light jets. Our work is useful in guiding experimental efforts at the Large Hadron Collider and the Relativistic Heavy Ion Collider in the near future.