Describing ϕ Meson Production in Small Collision Systems with Nuclear Modified Parton Distribution Functions

The deconfined state of strongly interacting quarks and gluons, quark–gluon plasma, may be formed in relativistic ion collisions at sufficient temperature and energy density. The signatures of quark–gluon plasma formation were observed in heavy-ion collisions by studying ϕ meson production. In small-collision systems, such as p+Al , p+Au , d+Au , and ^3He+Au , the volume and lifetime of the produced medium might be insufficient for observation of quark–gluon plasma effects. However various physics mechanisms reflecting initial state of the collision, cold nuclear matter effects, may lead to a collective-like behavior in small-collision systems without quark–gluon plasma formation. The nuclear modified parton distribution functions are considered to be an underlying physics mechanism of cold nuclear matter effects. This paper presents the comparison of ϕ meson production in p+Al , p+Au , d+Au , and ^3He+Au collisions at √(s_NN)=200 GeV at midrapidity ( |η|<0.35) , measured by PHENIX, to PYTHIA calculations with nuclear modified parton distribution functions EPPS16 and n CTEQ15. The ϕ meson production in p/d/^3He+Au collisions at √(s_NN)=200 GeV might be driven by mechanisms additional to nuclear modification of parton distribution functions.