Measurement of the t dependence in exclusive photoproduction of   Upsilon(1S) mesons at HERA
  The exclusive photoproduction reaction gamma p -> Upsilon(1S) p has been studied with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 468 pb^-1. The measurement covers the kinematic range 60<W<220 GeV and Q^2<1 GeV^2, where W is the photon-proton centre-of-mass energy and Q^2 is the photon virtuality. The exponential slope, b, of the t dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured, yielding b = 4.3 +2.0 -1.3 (stat.) +0.5 -0.6 (syst.) GeV^-2. This constitutes the first measurement of the t dependence of the gamma p -> Upsilon(1S) p cross section. 
ZEUS collaboration: H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, R.   Aggarwal, S. Antonelli, P. Antonioli, A. Antonov, M....
hep-ex