\u3cem\u3eJ/ψ\u3c/em\u3e Production at Low Transverse Momentum in \u3cem\u3ep\u3c/em\u3e + \u3cem\u3ep\u3c/em\u3e and \u3cem\u3ed\u3c/em\u3e + Au Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200 GeV

Abstract

We report on the measurement of J/ψ production in the dielectron channel at midrapidity (|y| \u3c 1) in p + p and d + Au collisions at √sNN = 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum pTspectra in p + p for pT \u3c 4 GeV/c and d + Au collisions for pT \u3c 3 GeV/c are presented. These measurements extend the STAR coverage for J/ψ production in p + p collisions to low pT. The ⟨p2T⟩ from the measured J/ψ invariant cross section in p + p and d + Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for J/ψ is extracted as a function of pT and collision centrality in d + Au and compared to model calculations using the modified nuclear parton distribution function and a final-state J/ψ nuclear absorption cross section