Speaker
Mr
Xavier Janssen
(Inter-University Institute for High Energies ULB-VUB Brussels)
Description
Exclusive rho^0 electroproduction at HERA has been studied with the ZEUS detector using 120 pb-1 of integrated luminosity collected during 1996-2000. The analysis was carried out in the kinematic range of photon virtuality 2 < Q2 < 160 GeV2, and gamma* p centre-of-mass energy 32 < W < 180 GeV. The results include the Q2 and W dependence of the gamma*p->rho^0 p cross section and the distribution of the squared-four-momentum transfer to the proton. The helicity analysis of the decay-matrix elements of the rho^0 was used to study the ratio of the gamma*p cross section for longitudinal and transverse photon as a function of Q2 and W. Finally, an effective Pomeron trajectory was extracted. The results are compared to various theoretical predictions.
An analysis of H1 data for rho and phi VM diffractive production, both in the elastic and proton dissociative channel is presented. The analysed data, which correspond to 51 pb-1, include a total of 12500 events in the transition region from low Q2 to the perturbative domain, $2.5 < Q2 < 60 GeV2, with data analysed in a consistent way, in particular for background estimates. The total, longitudinal and transverse cross sections are measured as a function of Q2, W and |t|. The polarisation efects are discussed in detail, in particular the Q2, |t| and (for rho mesons) M(pi,pi) dependences of the s-channel helicity conserving and violating amplitudes and phases. A consistent picture of VM production at intermediate and large Q2 thus emerges from H1 HERA-1 measurements, which can be interpreted in a QCD framework.
Primary author
Mr
Xavier Janssen
(Inter-University Institute for High Energies ULB-VUB Brussels)
Co-author
Stefan Schmitt
(DESY)
