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

Understand

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.