Measurement of proton-dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERAThe ZEUS Collaboration
(Received: 22 May 2002 / Published online: 9 December 2002)
Diffractive photoproduction of vector mesons, , where Y is a proton-dissociative system, has been measured in e+p interactions with the ZEUS detector at HERA using an integrated luminosity of 25 . The differential cross section, , is presented for 1.2<-t<12 GeV2, where t is the square of the four-momentum transferred to the vector meson. The data span the range in photon-proton centre-of-mass energy, W, from 80 GeV to 120 GeV. The t distributions are well fit by a power law, . The slope of the effective Pomeron trajectory, measured from the W dependence of the and cross sections in bins of t, is consistent with zero. The ratios to and to increase with increasing -t. Decay-angle analyses for , and mesons have been carried out. For the and mesons, contributions from single and double helicity flip are observed. The results are compared to expectations of theoretical models.
© Società Italiana di Fisica, Springer-Verlag 2003