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

TL;DR

This paper investigates how heavy quark mass influences jet quenching in nuclear matter, predicting a reversal of the mass hierarchy in jet suppression and proposing a new measurement to better understand in-medium splitting effects.

Contribution

It introduces a novel prediction of reversed mass hierarchy in jet quenching effects and proposes a new experimental measurement involving heavy flavor jet substructure.

Findings

Reversal of mass hierarchy in jet quenching effects predicted.

Prompt $b$-jet substructure shows stronger modification than light jets.

New measurement proposed to constrain in-medium splitting functions.

Abstract

In these proceedings, we discuss the role of heavy quark mass on the formation of parton showers. Mass effects are not well understood when parton branching occurs in nuclear matter, such as the quark-gluon plasma. Recently, a theoretically consistent picture of open heavy flavor production in ultra relativistic nuclear collisions has begun to emerge based on effective theories of QCD, such as soft collinear effective theory with Glauber gluons. We show that implementation of in-medium splitting processes containing heavy quarks into next-to-leading order calculations of heavy flavor production leads to larger cross section suppression when compared to traditional energy loss phenomenology. To better constrain the important mass dependence of in-medium splitting functions, we propose a new measurement in relativistic heavy ion collisions, based on a two-prong structure inside a reconstructed heavy flavor jet. In the region of jet transverse momenta where parton mass effects are leading, we predict a unique reversal of the mass hierarchy of jet quenching effects in heavy ion relative to proton collisions. We find that the momentum sharing distribution of prompt $b$-tagged jets is more strongly modified in comparison to the one for light jets. The work summarized here opens new directions of research on the substructure of heavy flavor jets.