R. Moller

A study of atmospheric neutrino oscillations in the Fréjus experiment

Abstract Atmospheric neutrino interactions have been studied with the Frejus proton decay detector using a total fiducial sensitivity of 1.56 kT yr. The atmospheric neutrino interaction sample has been compared to a Monte Carlo simulation which includes neutrino oscillations. The v e ( v e ) ∌v μ , ( v μ ), v e ( v e ) ∌v τ v μ ( v μ ) ∌v τ ( v τ) oscillations channels have been studied using the ratio of electron to muon charged current events. Three independent analyses have been performed and no evidence for neutrino oscillations has been found. The resulting limits on Δm2 for maximal mixing are more restrictive by more than one order of magnitude with respect to earlier measurements.

Evidence for dominant vector-meson production in inelastic proton-proton collisions at 53 GeV c.m. energy

Abstract The Split Field Magnet facility at the CERN ISR has been used to measure inclusive resonance production in inelastic p-p collisions at a c.m. energy of 53 GeV. The mass spectrum of pairs of oppositely charged hadrons shows a strong correlation, which can be explained as a consequence of dominant vector meson production, accounting for more than 60% of all pions and kaons produced.

Search for neutron-antineutron oscillations in the Fréjus detector

Abstract From the analysis of the fully contained events recorded in the underground Frejus detector, a lower limit of 1.2×108s at 90% CL is derived for the free neutron-antineutron oscillation time.

High

Abstract The production of direct photons has been measured relative to π 0 s in the rapidity range 2.00 y s = 63 GeV at the CERN Intersecting Storage Rings. The γ/π 0 ratio increases from ⪅2% at p T = 1.5 GeV/ c to ∼8% at p T = 4.25 GeV/ c , similar to the value observed near 90°. The results indicate no strong enhancement of single-photon production due to quark bremsstrahlung in this kinematic region.

p_T

The conjectures of Freund and Harari, together with s-channel helicity conservation in diffraction are shown to stand the tests now available in the KN channel. The relevant amplitudes were obtained through a partial wave analysis in the c.m. energy range from 1.55 to 2.14 GeV. Some evidence for the existence of P01 and S11 resonances is discussed.