Unitarity Bounds for New Physics from Axial Coupling at LHC

TL;DR

This paper derives model-independent unitarity bounds on the scale of new physics associated with axial couplings of massive vector bosons at the LHC, indicating potential energy limits for new particles or interactions.

Contribution

It provides a novel, model-independent method to estimate the maximum energy scale of new physics from axial couplings observed at the LHC.

Findings

Upper limit of 78 TeV for $M_{G}/ g_{A} < 3$ TeV with top quark coupling

Unitarity bounds depend on the axial coupling strength and fermion mass

Method applies broadly to various new physics scenarios involving axial couplings

Abstract

If a new massive vector boson with nonzero axial couplings to fermions will be observed at LHC, then an upper limit on the scale of new physics could be derived from unitarity of $\mathcal{S}$-matrix. The new physics will involve either new massive fermions, or scalars, or even a strongly coupled sector. We derive a model independent bound on the scale of new physics. If $M_{G}/ g_{A} < 3$ TeV and the fermion is a top quark, the upper limit is 78 TeV.