Speaker
Stephen Jones
(MPI, Munich)
Description
We present an updated and improved extraction of the low-$x$ gluon distribution from the HERA and LHCb (7 TeV and preliminary 13 TeV) exclusive $J/\psi$ production data in the context of $k_T$ factorisation. Critically, we use a more precise expression for the photon flux and re-calculate the rapidity gap survival factors.
In collinear factorisation exclusive $J/\psi$ photoproduction receives large perturbative corrections at NLO which prevents immediately using the coefficient function to extract a gluon PDF from the data. Attempts to understand and overcome the problems caused by the large perturbative corrections are discussed.
Primary authors
Alan Martin
Mikhail Ryskin
(Petersburg Nuclear Physics Institute)
Stephen Jones
(MPI, Munich)
Thomas Teubner
(University of Liverpool)
