SPIN ALIGNMENT OF RHO-O MESONS PRODUCED IN ANTINEUTRINO AND NEUTRINO NEON CHARGED-CURRENT INTERACTIONS

In a bubble chamber experiment with BEBC the spin alignment parameter η= 1 2 (2ρ{variant}00 - ρ{variant}11 - ρ{variant}-1-1) is measured for ρ{variant}0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be ηv=0.48±0.27 (stat.)±0.15 (syst.) for vNe and ηv=0.12±0.20 (stat.)±0.10 (syst.) for vNe interactions. © 1987

MEASUREMENT OF TOTAL AND PARTIAL PHOTON PROTON CROSS-SECTIONS AT 180 GEV CENTER-OF-MASS ENERGY RID C-1693-2008 RID B-9165-2008 RID C-5889-2009 RID A-4818-2008

Photon proton cross sections for elastic light vector meson production, sigma(el)gammap, inelastic diffractive production, sigma(d)gammap, non-diffractive production, sigma(nd)gammap, as well as the total cross section, sigma(tot)gammap, have been measured at an average gammap center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are sigma(el)gammap = 18 +/- 7 mub, sigma(d)gammap = 33 +/- 8 mub, sigma(nd)gammap = 91 +/- 11 mub, and sigma(tot)gammap = 143 +/- 17 mub, where the errors include statistical and systematic errors added in quadrature

SEARCH FOR LEPTOQUARKS WITH THE ZEUS DETECTOR

A search for any resonant state coupled to an electron and a proton constituent has been performed using collisions of electron and proton beams at HERA. In a sample with integrated luminosity of 26 nb-1, no evidence has been found for production of leptoquarks with decays to e- + jet or ν + jet. Limits on the coupling strength of scalar leptoquarks to electron and quark have been determined for masses above 25 GeV. For example, scalar isosinglet leptoquarks (S0) with electroweak coupling strength to (e-u) states are ruled out at the 95% confidence level for masses below 168 GeV for left-handed couplings and below 176 GeV for right-handed couplings