Search for Excited Muons in ppbar Collisions at sqrt(s) = 1.96 TeV

TL;DR

This study searches for excited muons in proton-antiproton collisions at 1.96 TeV, finding no evidence of their existence and setting mass exclusion limits up to 618 GeV.

Contribution

First search for excited muons at Tevatron energies using mu* to mu gamma decay channel, establishing new mass exclusion limits.

Findings

No excess above standard model expectations observed.

Excluded excited muon masses below 618 GeV at 95% confidence level.

Set upper limits on production cross sections between 0.057 and 0.112 pb.

Abstract

We present the results of a search for the production of an excited state of the muon, mu*, in proton antiproton collisions at sqrt s = 1.96 TeV. The data have been collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 380 pb^-1. We search for mu* in the process p pbar -> mu* mu, with the mu* subsequently decaying to a muon plus photon. No excess above the standard model expectation is observed in data. Interpreting our data in the context of a model that describes mu* production by four-fermion contact interactions and mu* decay via electroweak processes, we exclude production cross sections higher than 0.057 pb -- 0.112 pb at the 95% confidence level, depending on the mass of the excited muon. Choosing the scale for contact interactions to be Lambda = 1 TeV, excited muon masses below 618 GeV are excluded.