Exclusive and dissociative J/ψ production with collinear-improved Balitsky-Kovchegov equation *

Abstract

Abstract We extend the hotspot model to include the virtuality dependence and use it to study the exclusive and dissociative production combined with the dipole amplitude in the target rapidity representation. We determined that virtuality takes effect on a number of hotspots, thus providing a better description of the production data at HERA. The collinear improved Balitsky-Kovchegove equation in the target rapidity representation is numerically solved and used to fit the experimental data with a series of hotspot sizes. We infer that virtuality significantly influences the number and size of hotspots. The expression resulting from the fit with the collinear improved dipole amplitude in the target rapidity representation is more reasonable than the corresponding originating from the leading order fit, which indicates that the collinear improved evolution equation in the target rapidity representation can provide a relatively good depiction of the exclusive and dissociative HERA data.