Constraining $\tau$-lepton dipole moments and gluon couplings at the LHC

TL;DR

This paper investigates how the Large Hadron Collider can set limits on anomalous tau-lepton couplings, including magnetic, electric, weak dipole moments, and gluon interactions, using an effective field theory approach.

Contribution

It introduces dimension-six and dimension-eight operators to constrain tau-lepton couplings at the LHC, highlighting the potential for competitive and improved bounds.

Findings

14% measurement precision can match existing bounds on dipole moments.

A sensitivity of 500 sigma for tau-Higgs production can best constrain tau-gluon couplings.

Dimension-eight operators enhance the sensitivity to tau-gluon interactions at the LHC.

Abstract

We study the constraints that can be placed on anomalous $\tau$-lepton couplings at the LHC. We use an effective Lagrangian description for physics beyond the standard model which contains the $\tau$-lepton anomalous magnetic moment, electric dipole moment and weak dipole moments in two operators of dimension six. We include in our study two additional operators of dimension eight that directly couple the $\tau$-leptons to gluons and are therefore enhanced at the LHC. We consider the two main effects from these couplings: modifications to the Drell-Yan cross-section and to the $\tau$-lepton pair production in association with a Higgs boson. We find that a measurement of the former at the 14% level can produce constraints comparable to existing ones for the anomalous dipole couplings; and that a bound on the latter at a sensitivity level of $500\ \sigma_{SM}$ or better would produce the best constraint on the $\tau$-gluonic couplings.