Eur. Phys. J. C 24, 345-360 (2002)
DOI: 10.1007/s10052-002-0953-7
Exclusive photoproduction of mesons at HERA
The ZEUS collaboration(Received: 1 February 2002 / Published online: 22 May 2002)
Abstract
The exclusive photoproduction of
mesons,
,
has been studied in
ep collisions with the ZEUS detector at HERA,
in the kinematic range
GeV, where
is
the photon-proton centre-of-mass energy.
The
mesons were reconstructed in the muon and the electron
decay channels
using integrated luminosities of 38
and 55
, respectively.
The helicity structure of
production shows that
the hypothesis of
s-channel helicity conservation is satisfied
within two standard deviations.
The total cross section and
the differential cross-sec tion
,
where
t is the squared four-momentum transfer at the proton vertex,
are presented as a function of
W, for
|t|<1.8 GeV
2.
The
t distribution exhibits an exponential shape with a
slope parameter increasing logarithmically with
W with a value
at
.
The effective parameters of the Pomeron trajectory are
and
.
© Società Italiana di Fisica, Springer-Verlag 2002