Comment on Resummation of Mass Distribution for Jets Initiated by Massive Quarks

TL;DR

This paper calculates a soft coefficient in heavy quark effective theory for jet mass distributions, confirming previous QCD results and clarifying differences with heavy flavor decay coefficients.

Contribution

The paper provides a new calculation of the soft coefficient D_2 within heavy quark effective theory, showing its distinction from coefficients in heavy flavor decay.

Findings

Agreement with previous full QCD computation

Identification of the coefficient's difference from heavy flavor decay

Clarification of the coefficient's role in jet resummation

Abstract

We compute in the heavy quark effective theory the soft coefficient D_2 entering the resummation of next-to-next-to-leading threshold logarithms for jets initiated by a quark with a small mass compared to the hard scale of the process. We find complete agreement with a previous computation in full QCD. Contrary to our previous guess, this coefficient turns out to be different from that one entering heavy flavor decay or heavy flavor fragmentation.