V. V. Lyukov

Limits on neutral light scalar and pseudoscalar particles in a proton beam dump experiment

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton beam dump experiment. No positive signal is observed. Limits on the mass and life-time of these particles are set in the frame of the Standard Model and its minimal supersymmetric extension. The Higgs particle of theSU2L×U1 Standard Theory is excluded for masses in the range 1 MeV<mH<80 MeV at 95%CL. Limits on the Peccei-Quinn like axions are derived.

Search for heavy neutrinos at the IHEP-JINR neutrino detector

Abstract Data from a proton beam-dump experiment at the 70 GeV Serpukhov accelerator were analysed to search for heavy neutrino decays ν H → e + e − ν e at the IHEP-JINR Neutrino Detector. No signal over background was found. The upper limits on the elements if a mixing matrix | U eH | 2 in the mass range 5 m νH U eH || U μH | in the mass range 3 m νH

Neutrino production of charmed particles in a hybrid experiment E-564

AbstractCryogenically sensitive nuclear emulsion was placed inside the 15-foot bubble chamber of FNAL and exposed to a wide-band energy (up to 200 GeV) neutrino beam. 194 charged-current neutrino interactions and 13 decays of charmed particles were registered. Using the nuclear emulsion as a vertex detector with the good spectrometric properties of the 15-foot bubble chamber has allowed the decays of charmed particles to be effectively analysed. Attentions is focussed on the new physical results. Λc+ baryon andDs+ meson decay channels, production of charmed ∑c baryons and Λc+ via ∑c. For the first time an event interpreted as production of the excited (c

Production and decay of F+(2030) observed in νμ interactions in emulsion

\overline s

Investigation of prompt electron-neutrino production in a proton beam dump experiment with the IHEP-JINR ν detector

)-state with mass ∼2790 MeV/c2 has been registered.

Mass limits on a light Higgs boson from π-, K-, η′ -meson decays in the 70 GeV proton beam-dump experiment

A search has been performed for weakly interacting neutral light scalar and pseudoscalar particles in a proton-iron beam dump experiment via the Bethe-Heitler process. No positive signal was observed. Limits are derived on the masses of these particles in the framework of the Standard Model and its minimal supersymmetric extension (MSSM) comparing the experimental results with expectations for Bethe-Heitler e+e− and μ+μ− pair production. The Higgs particle of the SU2L×U1 Standard Theory is excluded for masses in the range mH<0.9 MeV at 95% CL. Limits on light Higgs particles of the MSSM and Peccei-Quinn like axions are derived.

Backward emitted protons in interactions of neutrinos with nuclei in photoemulsion

Abstract An event representing the production and decay of the charmed F+ meson has been identified by means of a 3-constraint fit to decay hypothesis F+ → π+π+π−π0, in which both γ-rays from the π0 converted. The event was produced by a charged current νμ interaction in an emulsion stack located inside the Fermilab 15-foot bubble chamber. The F+ traveled 50 μm, corresponding to a proper time of 1.4 × 10−13 seconds, before decaying in flight. Its mass was determined to be 2017 ± 25MeV.

Estimation ofvμ→vτ oscillation parameters in the E-564 hybrid experiment

The experiment on the search for inclusive electron neutrino oscillations is being carried out at the special neutrino beam of the Serpukhov 70 GeV accelerator using the IHEP-JINR neutrino detector. The short decay cavity of the neutrino beam makes it possible to search for oscillations analyzing the shape of the distribution of events using the variable LE, where L is the distance from the point of origin to the point of interaction of neutrino, E is the neutrino energy. The data of the two runs are processed and analysed. The best fit is obtained with Δm2 = 300 eV2 and sin2 2Θ = 0.144, but the X2 does not differ much for the hypothesis of no oscillations (within one standard deviation). This gives the limits on the oscillation parameters of sin2 2Θ < 0.115 at Δm2 = 175 eV2 (90% C.L.). For reasons outlined in the text, we believe this limit to be better or more reliable than earlier limits published by other experiments.