Professor Amanda Cooper-Sarkar

Abstract:

The production of the meson resonances ρ{variant}(770) (all three charge states), η(550), ω(783) and f2(1270) in {Mathematical expression} Ne and ν Ne charged current interactions is investigated in a bubble chamber experiment with BEBC at CERN. Except for the f2, the main features of resonance production are reasonably well described by the Lund model, although the average resonance multiplicities are overestimated by the model by (67±30)%. The average multiplicities of all resonances, including the f2, are well reproduced by a semiempirical model, whose parameters were determined from hadron interaction data. © 1989 Springer-Verlag.

Abstract:

Backward proton and pion production is studied in ν and {Mathematical expression} charged current interactions in neon. The results are compared with other experiments and theory. The complete backward proton data is compatible with protons produced by reinteractions in the nucleus. However in events with only one proton, muon variables appear correlated to those for the backward proton, as expected by the two-nucleon correlation model. © 1989 Springer-Verlag.

Abstract:

At HERA energies the small x region (x≲10-2) can be explored at Q2 values large enough that leading twist QCD calculations are valid. We show how measurement of the longitudinal structure function, FL(x,Q2), can lead to accurate measurement of the gluon structure function at such small x values. Experimental systematic errors are discussed fully and requirements for the measurement outlined. We conclude that it should be possible to distinguish between the widely varying gluon distributions which are currently allowed. © 1988 Springer-Verlag.

Abstract:

The average multiplicities of charged hadrons and of π⁺, π^- and π⁰ mesons, produced in {Mathematical expression}Ne and νNe charged current interactions in the forward and backward hemispheres of the W^±-nucleon center of mass system, are studied with data from BEBC. The dependence of the multiplicities on the hadronic mass (W) and on the laboratory rapidity (yLab) and the energy fraction (z) of the pion is also investigated. Special care is taken to determine the π⁰ multiplicity accurately. The ratio of average π multiplicities {Mathematical expression} is consistent with 1. In the backward hemisphere {Mathematical expression} is positively correlated with the charged multiplicity. This correlation, as well as differences in multiplicities between {Mathematical expression} and {Mathematical expression}, {Mathematical expression} scattering, is attributed to reinteractions inside the neon nucleus of the hadrons produced in the initial {Mathematical expression} interaction. © 1988 Springer-Verlag.

Abstract:

Nearly 40000 neutrino and antineutrino interactions in BEBC are compared to measure the differences between neon and deuterium in the quark and antiquark distributions and in the nucleon structure functions. The ratio of Ne to D cross sections indicates some decrease between x∼0.2 and x∼0.6. The y distributions show there is no significant increase in the neon sea, but prefer a small decrease. Taken altogether, the x and y distributions and the measured total cross-sections indicate some change in the shape of the valence distributions. No significant dependence on A is observed for either the shape of the sea or the ratio of longitudinal to transverse cross-sections. © 1987 Springer-Verlag.