Measurement of single muons at forward rapidity in p+p collisions at s=200GeV and implications for charm production

Muon production at forward rapidity (1.5≤|η|≤1.8) has been measured by the PHENIX experiment over the transverse momentum range 1≤p_T≤3GeV/c in s=200GeV p+p collisions at the Relativistic Heavy Ion Collider. After statistically subtracting contributions from light hadron decays an excess remains which is attributed to the semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks. The resulting muon spectrum from heavy flavor decays is compared to PYTHIA and a next-to-leading-order perturbative QCD calculation. PYTHIA is used to determine the charm quark spectrum that would produce the observed muon excess. The corresponding differential cross section for charm quark production at forward rapidity is determined to be dσ_cc¯/dy|_y=1.6=0.243±0.013(stat.)±0.105(datasyst.)(+0.049)/(-0.087)(PYTHIAsyst.)mb.