Study of the Hadronic Tau Decays Spectrum by using the New Experimental Data
The tau lepton is the heaviest and the only lepton that is able to decay into hadrons, therefore it provides a perfect tool to test the structure of the weak currents and the universality of their couplings to the gauge bosons. In the framework of the standard model, the w boson has both vector and axial vector components and can be coupled to hadronic states with spin-parity: JP = 0¯, 0+, 1¯, 1+. In the non- strange tau decays which G-parity is conserved, the separation of vector and axial-vector components in hadronic final states, can be observed directly by pions. Even number of pions (with G-parity = 1) are related to vector states and odd number of pions (with G-parity = -1) are related to axial-vector states. In this study, the widths of some dominant hadronic (semi-leptonic) tau decays are calculated and compared with new experimental data such as BABAR, ALEPH, DELPHI, FRASCATI and ORSAY. Since branching fraction ratio for two decay is equal with those decay width, by determining decay widths, we could be predict precise value for ratio of branching fractions.
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