A study was made of the reaction e+e- → mu+mu- using the CELLO detector at PETRA. Using data collected at a centre of mass energy of 35 GeV the total cross section, sigma0 and the electroweak charge asymmetry. Afb were measured giving: Rmumu =sigma0/sigmaQED = 0.95+/-0.02+/-0.05; Afb = -8.9+/-2.0+/-1.0 % The results are in good agreement with the values predicted by the electroweak model of Rmumu = 1.0 and Afb = -8.9% at this energy. Using data collected at a centre of mass energy of 43 GeV a search was made for acoplanar muon pairs, a signature of scalar muons. No candidates were found and the following masses were excluded at the 95% C. L
