a High Precision Measurement of Electroweak Effects in Electron-Positron ---> Positive Muon, Negative Muon at SQRT.S = 29 GEV.
A high statistics measurement has been made of the process e('+)e('-) (--->) (mu)('+)(mu)('-) at SQRT.(s = 29 GeV using the MAC detector at PEP. The electroweak forward-backward charge asymmetry for a sample of approximately 16000 events was measured to be A(,(mu)(mu)) = -0.063 (+OR -) 0.008 (+OR-) 0.002. The cross section ratio relative to lowest order QED was measured to be R(,(mu)(mu)) = 1.01 (+OR-) 0.01 (+OR-) 0.03. From these results the weak neutral axial vector and vector couplings are determined to be g(,A)('e)g(,A)('(mu)) = 0.25 (+OR-) 0.03 (+OR-) 0.01 and g(,V)('e)g(,V)('(mu)) = -0.02 (+OR-) 0.03 (+OR-) 0.09.('). The experiment exploits the good muon detection provided by an array of drift chambers which track charged particles after they have travelled through over one meter of iron (i.e. muons). These arrays are discussed in detail, since it was designed, constructed, installed and maintained by the Northeastern group. The performance of the arrays met our initial goal to have the instrumental error less than the multiple scattering error in the iron, which gave us a momentum resolution of (delta)p/p = 30%.
- Pub Date:
- Physics: Elementary Particles and High Energy