Observation of muon-neutrino reactions producing a positron and a strange particle

In addition to one previously reported event, a second event, in which a positron is observed together with a strange particle and a negative muon, has been seen in the bubble chamber Gargamelle exposed to the CERN neutrino beam. The level of the background for this type of event is found to be very low. The data strongly indicate the existence of a new type of interaction leading to a charged lepton pair correlated with a strange particle in the final state. The interpretation of these two events in terms of production of a charmed hadron is presented. © 1976.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Total cross sections for ve and ve interactions and search for neutrino oscillations and decay

About 200 and 60 candidates for electron neutrino and antineutrino interactions, respectively, have been analyzed in the heavy liquid bubble chamber Gargamelle exposed to the CERN PS neutrino beam. Evidence for scaling has been found for these interactions, with slopes of the cross sections in good agreement with those obtained for muon neutrino and antineutrino events in the same chamber. No evidence appears for oscillations of neutrinos or antineutrinos, which would induce in the present experiment an excess of electron or positron events. The corresponding limits are given as functions of the mixing parameter, for the finite mass Majorana neutrinos. The possibility of a multiplicative law for the lepton number has also been investigated. A search for isolated electron-positron pairs revealed no excess in the forward direction, in contradiction to the expectation for muonic neutrino and antineutrino decays. The corresponding limits on the c.m. half lifetimes are given. © 1978.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Upper limit to the cross-section for the process νμ + e- → νμ + e-

An upper limit of 3 × 10-42 Eν cm2 per electron, at 90% confidence level, has been obtained for the cross section of the process νμ + e- → νμ + e-, interpreted in the usual V-A framework, for an electron recoil energy larger than 0.3 GeV. This estimate is based on the observation of one candidate event in exposures of Gargamelle to the CERN PS neutrino beam. © 1978.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Evidence for the leptonic neutral current reaction νμ+e-→νμ+e-

In the Gargamelle neutrino experiment, three unambiguous candidates for the reaction νμ+e-→νμe- have been observed corresponding to a cross section for a recoil electron energy within the range 0.3 < Ee- < 2.0 GeV of 0.06 × 10-41 Eν (GeV) cm2/electron. The calculated background is 0.44 ± 0.13 events and the probability that all three candidates could be due to this background is 1%. © 1976.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Determination of the neutral to charged current inclusive cross-section ratio for v and v interactions in the "Gargamelle" experiment

0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Relations among neutral current couplings to test su(2) by u(1) gauge group structure

We propose a test of the validity of SU(2) ⊗ U(1) as the gauge group of weak and electromagnetic interactions. We find that, among the seven empirical neutral current couplings, there are two restrictions which do not rely on a particular model. The relations are 2( G V + G A ) + ( α + β ) + 3( γ + δ ) = 0 and 2 k − ( α + β ) + 3( γ + δ ) = 0, where where α , β , γ , δ ( G V , G A ) are the couplings measured in neutrino-hadron (electron) scattering and κ is obtained from interference experiments. We also find several inequalities. Comparison with present data is given