A Study of the LEP and SLD Measurements of AbA_b

A systematic study is made of the data dependence of the parameter $A_{\rm{b}}$, that, since 1995, has shown a deviation from the Standard Model prediction of between 2.4 and 3.1 standard deviations. Issues addressed include: the effect of particular measurements, values found by individual experiments, LEP/SLD comparison, and the treatment of systematic errors. The effect, currently at the 2.4$\sigma$ level, is found to vary in the range from 1.7$\sigma$ to 2.9$\sigma$ by excluding marginal or particularly sensitive data. Since essentially the full LEP and SLD Z decay data sets are now analysed the meaning of the deviation, (new physics, or marginal statistical fluctuation) is unlikely to be given by the present generation of colliders.Comment: 15 pages 7 figures 7 table

Quantum Interference Effects in the Detection Probability of Charged Leptons Produced in Charged Current Weak Interactions

The phases of quantum interference effects in charged lepton production by neutrinos (neutrino oscillations) following pion decay at rest and in flight, muon decay and nuclear $\beta-$decay at rest as well as for `muon oscillations' following pion decay at rest and in flight are calculated. The same phase is found for neutrino and muon oscillations following pion decay at rest. The results found disagree with the conventionally used value: $\phi_{12} = \Delta m^2 L/(2P)$. Differences to previous treatments are briefly commented onComment: 8 pages, 1 figure. Letter summarising the results obtained in hep-ph/0303151. (Updated, revised and corrected version of hep-ph/0110066