Bochum 1998 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HK: Hadronen und Kerne
HK 67: Structure of Baryons, Mesons IX, Theory
HK 67.9: Gruppenbericht
Donnerstag, 19. März 1998, 16:30–17:00, H
Consequences of chiral structure of the nucleon at high energy collisions — •A. Szczurek1, A. Budzanowski1, J. Speth2, and V. Uleshchenko1 — 1Institute of Nuclear Physics, PL-31-342 Kraków — 2Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich
In last few years the nonperturbative effects due to the chiral structure of the nucleon turned out to be very important in quantitative understanding of the Gottfried Sum Rule violation, SU(3) symmetry violation of the nucleon sea and the Drell-Yan asymmetry measured at CERN. We investigate possible consequences of the chiral structure of the nucleon for the production of the W and Z bosons in hadron-hadron collisions. We start from the description of the muon and charged-current (anti)neutrino deep-inelastic scattering including explicitly corrections due to the meson cloud effects. We get a good description of the total W and Z production cross sections measured in the proton-antiproton collisions by the UA1 and UA2 collaboration at CERN and the CDF collaboration at FNAL as well as the lepton asymmetry obtained recently by the CDF collaboration. Our model predicts an enhancement of the cross section for the W boson production in proton-proton collisions in comparison to proton-antiproton collisions. The charge lepton asymmetry measured recently by the CDF collaboration can be described only if meson cloud effects are included explicitly. We critically study a possibility to test the d − ū asymmetry in the nucleon by the analysis of various asymmetries possible to measure in principle at RHIC. We examine to which degree the effect of the inclusion of target mass corrections in the description at low-Q2 DIS and meson cloud effects may, after QCD evolution, modify DIS cross section at large x and Q2. This is of interest in the context of recently reported excess of events observed by H1 and ZEUS collaborations at HERA. We predict an enhanced production of events at large-x in comparison to standard sets of quark distributions with rather mild Q2-dependence. Our analysis leaves some room for more exotic effects beyond parton approach and/or Standard Model. Our large-x effects can be verified in the future when the HERA luminosity will be increased.