Speaker
Description
Ultra-peripheral nucleus-nucleus collisions (UPC) are mediated by strong
electromagnetic fields, offering the opportunity to study photon-nucleus pro-
cesses at RHIC. Coherent J/ψ photoproduction is of particular interest for its
sensitivity to nuclear gluon distribution. The J/ψ mesons are heavy enough to
be described by perturbative Quantum Chromodynamics (pQCD), where coher-
ent cross section, at the first order, is proportional to the square of the nuclear
gluon distribution. This makes coherent J/ψ cross section an ideal probe to
phenomena of gluon saturation and nuclear gluon shadowing.
In this talk, we present a brief overview of the topic and preliminary results
of exclusive coherent J/ψ photoproduction in Au+Au UPC at sqrt(sNN ) =
200 GeV at central rapidity |y| < 1, where the photoproduction was tagged
at the trigger level by forward neutrons emitted as a result of electromagnetic
excitation of the nuclei.
