Measurement of the Charge Ratio of Atmospheric Muons at the Compact Muon Solenoid in Events with Momenta Between 5 GeV/c and 1 TeV/c

The ratio of positive to negative charges in the secondary cosmic muon flux is measured at the Compact Muon Solenoid experiment. Muons with momenta between 5 GeV/c and 1 TeV/c are observed in data collected at ground level or 89 m underground; and found to be a constant 1.2766 +/- 0.0032 (stat.) +/- 0.0032 (syst.) for momenta below 100 GeV/c, and rising with higher momenta. The fraction of charged pions and kaons in the secondary cosmic flux resulting in positive muon production has been estimated, with the fraction for pions = 0.553 +/- 0.005 and for kaons = 0.66 +/- 0.06, respectively. The results presented herein are in good agreement with cosmic ray shower models, consistent with previous measurements, and represent the most precise measurement to date for atmospheric muons up to 500 GeV/c. This is also the first physics measurement involving muons at the completed CMS detector.