Calculation of Power Corrections to Hadronic Event Shapes of Tagged b Events

TL;DR

This paper calculates power corrections to hadronic event shapes in tagged b quark events, revealing mass effects reduce corrections by 10-30% across energies from Z peak to 20 GeV, using a dispersive approach.

Contribution

It extends the dispersive approach to include mass effects in power corrections for b quark events, showing the corrections are similar to the massless case but scaled by mass-dependent factors.

Findings

Power corrections are similar to massless case but scaled by mass-dependent factors.

Mass effects reduce power corrections by 10-30% across energies.

Results are applicable from Z peak down to 20 GeV.

Abstract

We compute power corrections to mean values of hadronic event shapes - the thrust and the C parameter - of tagged b quark events in electron positron annihilation, using the dispersive approach. We find that the leading power corrections are of the same type of 1/Q corrections as for event shapes in the massless case, with the same non-perturbative coefficient times a perturbatively calculable mass-dependent coefficient. The effect of the mass correction in the power correction is to reduce the latter by 10-30% for tagged b events, for centre-of-mass energies ranging from the Z peak down to 20 GeV.