Inelastic photoproduction of polarised J/ψ
Abstract
The comparison of
J/ψ
photoproduction data in the inelastic region with theoretical predictions based on the NRQCD approach has remained somewhat ambiguous and controversial, in particular at large values of the inelasticity variable
z
. We study the polar and azimuthal decay angular distribution of
J/ψ
mesons as functions of
z
and transverse momentum
p
t
. Future measurements of decay angular distributions at the HERA
ep
collider will provide a new test of theoretical approaches to factorisation between perturbation theory and quarkonium bound-state dynamics and shed light on the colour-octet production fraction in various regions of
z
and
p
t
.