Professor Amanda Cooper-Sarkar

Abstract:

The cross section for coherent production of a single π- meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175±25) 10-40 cm2/neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9±0.1) % of the total charged current {Mathematical expression} cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, the Q2 dependence is well described by a propagator containing a mass m=(1.35±0.18) GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5-150 GeV. © 1986 Springer-Verlag.

Abstract:

Evidence for a significant higher twist contribution to high z π^- production in antineutrino scattering is presented. In events with W>3 GeV and Q²>1 GeV² in our data, it accounts for (51 ±8)% of all π^- with z above 0.5. It is consistent with the z-Q² correlations of Berger's higher twist prediction. The data are inconclusive concerning the predicted y-z correlation and pT dependence. The z -Q² correlation is not adequately described by the Lund Monte-Carlo. © 1986 Springer-Verlag.

Abstract:

Observational upper limits on anomalous neutral-current events in a proton beam dump experiment are used to constrain the possible hadroproduction and decay of light gluinos. These results require ifmg̃ $ ̌4 GeV for ifmq̃ - minw. © 1985.

Abstract:

New limits on lepton mixing parameters are derived from a search for decays of heavy neutrinos in a proton beam dump experiment. The limits |Uøi|2, |Uei|2 < 10-6-10-7 are obtained for neutrino mass eigenstates vi of mass between 0.5 and 1.75 GeV, which can be produced through mixing in charmed D meson decays. This is the first such limit on |Uøi|2 for neutrino masses greater than 0.5 GeV. For the mass eigenstate v3 in particular, we obtain the limits |Uø3|2 < 10-7-10-8, |Ue3|2 < 10-9-10-10 for the mass range 150-190 MeV, assuming the v3 to be produced directly in charmed F meson decays. © 1985.

Abstract:

A sample of over 25,000 fully measured neutrino and antineutrino charged current interactions in BEBC includes 192 dilepton candidates. The prompt signal after subtraction of background is 41 ±7μ+e-, 35±7μ+μ- events from {Mathematical expression} interactions, and 32±7μ-μ+ events from ν interactions. There are 2 trileptons, μ-μ-e+ and μ-μ-μ+. Results are compared with other experimental data and with the standard model. Limits to prompt like sign μ+e+, μ+μ+ and μ-μ- signals are given and compared with other experiments and with theoretical calculations. © 1985 Springer-Verlag.