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TL;DR: In this paper, the pure lepton decay of the polarized muon is considered, accounting for a new tensor interaction which is outside of the Michel local interactions, leading to new energy distribution and polarization of the final charged lepton.
Abstract: The pure lepton decay of the polarized muon is considered, accounting for a new tensor interaction which is outside of the Michel local interactions. This interaction leads to new energy distribution and polarization of the final charged lepton. The presence of such a type of interaction is strongly required for the description of the latest experimental results on the weak radiative pion decay in the full kinematic region. Assuming quark–lepton universality, predictions for a deviation from the Standard Model are made using only one new parameter. They do not contradict the present experimental data and can be verified further in the on-going experiments at PSI and TRIUMF, at least to the level of 3 standard deviations.
3 citations
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TL;DR: An Introduction to Quarks and Partons by F.E. Close as discussed by the authors is a good starting point for a discussion of the relationship between quarks and partons in the context of physics.
Abstract: An Introduction to Quarks and Partons. By F.E. Close. Pp.481. (Academic: London, New York and San Francisco, 1979.) £26.40; $54.50.
261 citations
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TL;DR: In this article, a measurement of delta was performed using the first physics data recorded by the TWIST experiment at TRIUMF, and the obtained value, delta=0.74964+-0.00066+−0.00112(syst.), is consistent with the Standard Model expectation delta=3/4.
Abstract: The muon decay parameter delta characterizes momentum dependence of the parity-violating muon decay asymmetry. A new measurement of delta has been performed using the first physics data recorded by the TWIST experiment at TRIUMF. The obtained value, delta=0.74964+-0.00066(stat.)+-0.00112(syst.), is consistent with the Standard Model expectation delta=3/4. This is the first determination of delta performed using a blind analysis technique. Combined with other data, the measurement sets new model-independent limits on effective right-handed couplings of the muon. Improved limits on the product of another muon decay parameter, xi, and the muon polarization in pion decay, Pmu, are obtained in the form: 0.9960
6 citations
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TL;DR: In this paper, it was shown that the discrepancy in pion spectral functions extracted from positron-electron annihilation and tau decay leads to different predictions for the muon anomalous magnetic moment.
Abstract: It is known that the discrepancy in pion spectral functions extracted from positron-electron annihilation and tau decay leads to different predictions for the muon anomalous magnetic moment. We will show that this discrepancy effects also the extraction of the Cabibbo angle from the hadronic tau decays. The corrections to the tau branching fractions, corresponding to the presence of new centi-weak tensor interactions, allow us to extract the Cabibbo angle from tau decays in agreement with its other precision determinations. Thus a more precise value of |V_us|=0.2246 +/- 0.0012 is obtained and as a consequence f(0)=0.9645 +/- 0.0055 and F_K/F_pi=1.196 +/- 0.007.
2 citations