Eur. Phys. J. C 25, 25-39 (2002)
DOI: 10.1007/s10052-002-01009-8
Inelastic photoproduction of
mesons at HERA
The H1 Collaboration (Received: 21 May 2002 / Published online: 26 July 2002 )
Abstract
An analysis of inelastic photoproduction of
mesons is presented
using data collected at the
ep collider HERA corresponding to an integrated
luminosity of above
.
Differential and double differential cross sections are measured in a wide
kinematic region:
,
and
0.05<z<0.9, where
z is the fraction of the energy of the
exchanged photon transferred to the
meson in the rest frame of the
target proton.
Cross sections at
are presented for the first time.
Theoretical calculations within the Colour Singlet Model at NLO for direct photon
processes are shown to give a good description of the data in the medium
z region (
0.3<z<0.9)
up to the highest
values.
A calculation using a
kt factorisation approach
in LO in the Colour Singlet Model is also able to describe these data.
The data in the full
z range are also compared to LO calculations within a non-relativistic
QCD framework including colour octet and colour singlet contributions for
direct and resolved photons. It seems
possible to reconcile data and theory with modest contributions from
colour octet processes.
The polarisation of the
meson is measured as a function of
z and
and is reasonably described by the theoretical predictions.
© Società Italiana di Fisica, Springer-Verlag 2002