Inelastic photoproduction of polarised $J/ψ$

M. Beneke; M. Kramer; M. Vänttinen

Paper

Inelastic photoproduction of polarised $J/ψ$

Abstract

The comparison of

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

. We study the polar and azimuthal decay angular distribution of

mesons as functions of

and transverse momentum

. Future measurements of decay angular distributions at the HERA

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

and