Measurements of J/?? production vs event multiplicity in the forward rapidity in p+p and p+A?? collisions in the PHENIX experiment

J/?? production has been studied extensively in high energy ??+?? and heavy ion collisions at RHIC and other facilities, and several promising pQCD based production models have been investigated in details, however, our understanding of the production mechanisms still remain largely uncertain. The recent observations of enhanced particle yields, including ??/??, in high event multiplicity ??+?? collisions at RHIC and LHC suggest strong contributions from possible semi-hard Multi-Parton Interactions (MPI) as well as from other effects including gluon saturation in the initial state. These new results challenge not only the traditional “single hard-scattering” pQCD description, but also the interpretation of other important observables, such as event centrality in heavy ion collisions and certain transverse spin asymmetries in polarized ??+??(??) interactions. To gain further insight into particle production mechanisms, we study the ??/?? yield in the forward (and backward) rapidity in p+p and p+Au collisions as a function of event multiplicity determined over a broad range of rapidity, considering both possible global and local correlations. The latest results from PHENIX will be presented.