A study ofv e −v μ universality and search for neutrino oscillations

Abstract

In the SKAT neutrino bubble chamber experiment at the Serpukhov accelerator we observe 83 events with electrons and no further lepton in the final state. Comparing the ratio of electron to muon charged current events at energies 3<E v <30 GeV with that expected fromv e -beam background assuming lepton universality we find $$R = (N_{e^ - } /N_{\mu ^ - } )_{\exp } /(N_{e^ - } /N_{\mu ^ - } )_{calc} = 0.98 \pm 0.15$$ . Furthermore we compare experimental observations and theoretical expectations for some differential distributions of the electron-neutrino charged current reaction. No significant deviation from lepton universality is found. Looking in the charged current reaction for oscillations of muon to electron type neutrinos we find no effect down to the 90% confidence limits Δm 2 =1.3 eV2 at sin22θ=1 and sin22θ=2.5·10−3 at Δm 2=60 eV2.