Hadron Mass Effects in Power Corrections to Event Shapes

TL;DR

This paper investigates how hadron masses influence power corrections in dijet event-shape distributions, introducing a new operator and classifying universality classes, with implications for precision QCD analyses.

Contribution

It introduces the transverse velocity operator to account for hadron mass effects and provides a method to classify universality classes of event shapes.

Findings

Hadron masses break universality in power corrections.

A new operator describes hadron mass effects.

Computed the anomalous dimension of the power correction.

Abstract

We study the effect of hadron masses on the leading power correction of dijet event-shape distributions. We define the transverse velocity operator, that describes the effects of hadron masses. It depends on the "transverse velocity" r, which is different from one only for non-vanishing hadron masses. We find that hadron-mass effects in general break universality. However we provide a simple method to identify universality classes of event shapes with a common power correction. We also compute the anomalous dimension of the power correction and the structure of the corresponding Wilson coefficient, finding a nontrivial result.