Little Flavor: Heavy Leptons, Z' and Higgs Phenomenology

TL;DR

This paper extends the Little Flavor model to include leptons, exploring its implications for neutrino masses, mixing, and collider phenomenology, including new decay channels and flavor violation suppression.

Contribution

It develops the lepton sector of the Little Flavor model, integrating neutrino mass generation and analyzing collider signatures of TeV-scale leptons and gauge bosons.

Findings

TeV-scale lepton partners can produce distinctive collider signals.

Branching ratios of Z' to dileptons are suppressed, evading current bounds.

New decay channels like Z' -> MET + leptons/jets are possible.

Abstract

The Little Flavor model is a close cousin of the Little Higgs theory which aims to generate flavor structure around TeV scale. While the original Little Flavor only included the quark sector, here we build the lepton part of the Little Flavor model and explore its phenomenology. The model produces the neutrino mixing matrix and Majorana masses of the Standard Model neutrinos through coupling to heavy lepton partners and Little Higgses. We combine the usual right-handed seesaw mechanism with global symmetry protection to suppress the Standard Model neutrino masses, and identify the TeV partners of leptons as right-handed Majorana neutrinos. The lepton masses and mixing matrix are calculated perturbatively in the theory. The TeV new gauge bosons have suppressed decay width in dilepton channels. Even assuming the Standard Model couplings, the branching ratios to normal dilepton channels are largely reduced in the model, to evade the bound from current $Z'$ search. It also opens up the new search channels for exotic gauge bosons, especially Z' -> MET + multi L+jets. The multiple lepton partners will create new chain decay signals in flavor related processes in colliders, which also give rise to flavor anomalies. The lepton flavor violation process can be highly suppressed in charged lepton sector and happens only through neutrinos.