Search for excited muons in pp-bar collisions at s√=1.96 TeV

Abstract

We present the results of a search for the production of an excited state of the muon, μ∗, in proton antiproton collisions at 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 μ∗ in the process pp-bar→μ∗μ, with the μ∗ 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 μ∗ production by four-fermion contact interactions and μ∗ decay via electroweak processes, we set a 95% confidence level production cross section upper limit ranging from 0.057 to 0.112 pb, depending on the mass of the excited muon. Choosing the scale for contact interactions to be Λ=1 TeV, excited muon masses below 618 GeV are excluded.