Effects of new leptons in Electroweak Precision Data

TL;DR

This paper investigates how new vector-like leptons at the TeV scale influence electroweak precision data, providing limits that complement existing lepton flavor violation constraints and exploring their impact on the Higgs mass fit.

Contribution

It presents new limits on TeV-scale vector-like leptons from electroweak data and analyzes their effects on the Higgs mass constraints within the Standard Model.

Findings

Limits on vector-like leptons at the TeV scale from electroweak tests

Global fit quality comparable to the Standard Model

Potential to accommodate a heavier Higgs mass (up to 260 GeV)

Abstract

We obtain limits on generic vector-like leptons at the TeV scale from electroweak precision tests. These limits are complementary to the ones obtained from lepton flavour violating processes. In general, the quality of the global electroweak fit is comparable to the one for the Standard Model. In the case of an extra neutrino singlet mixing with the muon or electron, the global fit allows for a relatively large Higgs mass (M_H < 260 GeV at 90 % C.L.), thus relaxing the tension between the direct LEP limit and the Standard Model fit.