Measurement of Single Muons at Forward Rapidity in p+p Collisions at sqrt(s) = 200 GeV and Implications for Charm Production

TL;DR

This study measures muon production at forward rapidity in proton-proton collisions at 200 GeV, inferring charm quark production rates and comparing results with theoretical models to understand heavy flavor production.

Contribution

It provides the first measurement of charm production cross section at forward rapidity in p+p collisions at RHIC energies, using muon spectra and theoretical comparisons.

Findings

Charm production cross section at y=1.6 is approximately 0.243 mb.

Muon excess attributed to heavy flavor decays, mainly charm.

Results agree with perturbative QCD predictions within uncertainties.

Abstract

Muon production at forward rapidity (1.5 < |\eta| < 1.8) has been measured by the PHENIX experiment over the transverse momentum range 1 < p_T \le 3 GeV/c in sqrt(s) = 200 GeV 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 d\sigma_(c c^bar)/dy|_(y=1.6)=0.243 +/- 0.013 (stat.) +/- 0.105 (data syst.) ^(+0.049)_(-0.087) (PYTHIA syst.) mb.