Bloch-Nordsieck restoration in llbar -> qqbar

TL;DR

This paper discusses a gauge-invariant approach that restores the Bloch-Nordsieck theorem in weak interactions by replacing asymptotic states with composite states, aligning with phenomenological observations.

Contribution

It introduces a method to restore the Bloch-Nordsieck theorem in weak interactions using composite states, addressing a known violation.

Findings

Restores Bloch-Nordsieck theorem in weak interactions

Uses gauge-invariant composite states

Aligns with existing phenomenology

Abstract

Usually, the Bloch-Nordsieck theorem is expected to be violated in weak interactions, as the corresponding asymptotic states are not weak singlets. However, a manifest gauge-invariant approach replaces the asymptotic states with composite states, and thereby restores the Bloch- Nordsieck theorem. The Froehlich-Morchio-Strocchi mechanism ensures that this is in agreement with existing phenomenology. We outline the necessary steps of this construction.