Effective field theory for vector-like leptons and its collider signals

TL;DR

This paper develops an effective field theory framework to analyze vector-like leptons in models with multiple high scales, highlighting new collider signals and proposing improved search strategies for the LHC.

Contribution

It introduces a novel EFT approach for vector-like leptons, deriving bounds on interactions and proposing new observables to enhance collider searches.

Findings

Bounds on dimension-six interactions around 0.05 TeV$^{-2}$

New observables improve current LHC analyses

Impact assessment on UV completions of SM with vector-like leptons

Abstract

We argue that in models with several high scales; e.g. in composite Higgs models or in gauge extensions of the Standard Model (SM), vector-like leptons can be likely produced in a relatively large $\sqrt{s}$ region of the phase space. Likewise, they can easily decay into final states not containing SM gauge bosons. This contrasts with the topology in which these new particles are being searched for at the LHC. Adopting an effective field theory approach, we show that searches for excited leptons must be used instead to test this scenario. We derive bounds on all the relevant interactions of dimension six; the most constrained ones being of about $0.05$ TeV$^{-2}$. We build new observables to improve current analyses and study the impact on all single-field UV completions of the SM extended with a vector-like lepton that can be captured by the effective field theory at tree level, in the current and in the high-luminosity phase of the LHC.