Cancellation of Infrared Divergence in Inclusive Production of Lepton Pair Near the Threshold of Heavy Quarkonia

TL;DR

This paper proves the cancellation of infrared divergences in the inclusive production of lepton pairs near heavy quarkonium thresholds, supporting the validity of NRQCD factorization in such processes.

Contribution

It provides a detailed proof of infrared divergence cancellation in lepton pair production near heavy quarkonium thresholds, emphasizing the importance of state transition effects.

Findings

Infrared divergences cancel in the process near the quarkonium threshold.

The proof supports NRQCD factorization for these production processes.

Transition effects between heavy quark states are crucial for divergence cancellation.

Abstract

The detailed proof of cancellation of topologically unfactorized infrared divergences in the inclusive production of lepton pair close to the threshold of heavy quarkonia is presented. To make the effects of transition between states containing heavy quark pairs, which is important in such cancellation, the final detected states are constrained to be lepton pair near the threshold of the heavy quarkonia instead of heavy quarkonia themselves. Such cancellation is crucial for the NRQCD factorization of these processes.