Search for a Heavy Neutral Particle Decaying to $e\mu$, $e\tau$, or $\mu\tau$ in $pp$ Collisions at $\sqrt{s}=8$ TeV with the ATLAS Detector

TL;DR

This paper searches for heavy neutral particles decaying into different-flavor dileptons in proton-proton collisions at 8 TeV, finding no excess and setting limits on new physics models involving lepton flavor violation.

Contribution

It provides the first search for such particles in these decay channels at 8 TeV and sets new limits on R-parity-violating supersymmetry and lepton-flavor-violating Z' models.

Findings

No significant excess observed over Standard Model expectations.

Limits set on cross sections for new particles in specified models.

Constraints improve previous bounds on lepton-flavor-violating processes.

Abstract

This Letter presents a search for a heavy neutral particle decaying into an opposite-sign different-flavor dilepton pair, $e^\pm \mu^\mp$, $e^\pm \tau^\mp$, or $\mu^\pm \tau^\mp$ using 20.3 fb$^{-1}$ of $pp$ collision data at $\sqrt{s} = 8$ TeV collected by the ATLAS detector at the LHC. The numbers of observed candidate events are compatible with the Standard Model expectations. Limits are set on the cross section of new phenomena in two scenarios: the production of $\tilde{\nu}_{\tau}$ in $R$-parity-violating supersymmetric models and the production of a lepton-flavor-violating $Z'$ vector boson.