Top quark as a resonance

TL;DR

This paper develops a formalism for describing the top quark as a resonance with parity violation effects, revealing deviations from standard resonance shapes and spin corrections, which are negligible for the Standard Model top quark.

Contribution

It introduces a new representation of the dressed fermion propagator with parity non-conservation, including general off-shell projectors and resonance factors, extending previous models.

Findings

Resonance factors deviate from Breit-Wigner form due to parity violation.

Spin corrections appear in the resonance description.

For the Standard Model top quark, the resonance factor simplifies to the standard form.

Abstract

We suggest the description of the dressed fermion propagator with parity non-conservation in the form with separated positive and negative energy poles. We found general form of the $\gamma$-matrix off-shell projectors and corresponding resonance factors. The parity violation leads to deviation of resonance factors from the naive Breit--Wigner form and to appearance of non-trivial spin corrections. However, for top quark with SM vertex the resonance factor returns to the standard one due to $\Gamma/m\ll1$.