Measurement of proton-dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERA

  • The ZEUS Collaboration
  • S. Chekanov et al.
Experimental Physics


Diffractive photoproduction of vector mesons, \(\gamma p \to V Y\), 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\(\pbi\). The differential cross section, \(d\sigma/d t\), is presented for \(1.2 < -t<12{\rm GeV}^2\), 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, \(d\sigma/d t \propto (-t)^{-n}\). The slope of the effective Pomeron trajectory, measured from the W dependence of the \(\rho^0\) and \(\phi\) cross sections in bins of t, is consistent with zero. The ratios \(d\sigma_{\gamma p \to \phi Y}/d t\) to \(d\sigma_{\gamma p \to \rho^0 Y}/d t\) and \(d\sigma_{\gamma p \to J/\psi Y}/d t\) to \(d\sigma_{\gamma p \to \rho^0 Y}/d t\) increase with increasing -t. Decay-angle analyses for \(\rho^0\), \(\phi\) and \(J/\psi\) mesons have been carried out. For the \(\rho^0\) and \(\phi\) mesons, contributions from single and double helicity flip are observed. The results are compared to expectations of theoretical models.


Theoretical Model Momentum Transfer Differential Cross Section Vector Meson Differential Cross 
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Copyright information

© Springer-Verlag Berlin Heidelberg / Società Italiana di Fisica 2002

Authors and Affiliations

  • The ZEUS Collaboration
  • S. Chekanov et al.
    • 1
  1. 1.Argonne National Laboratory, Argonne, Illinois 60439-4815, USA US

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