Abstract
Hadronic decays of the τ lepton provide a clean environment to study hadron dynamics in an energy regimedominated by resonances. The interesting information is captured in the spectral functions. Recent results from ALEPH on exclusive channels are presented, with emphasis on the ππ 0 final state which plays a crucial role for the determination of the hadronic contribution to the muon anomalous magnetic moment. A comparison between 2 π spectral functions obtained in τ decays (after corrections for isospin-breaking) and e + e − annihilation reveals some discrepancy in the line shape of the ρ resonance which can be attributed to different pole mass values for the charged and neutral ρ's, which are determined through a robust fitting procedure. However, after applying this correction, the normalization of the two spectral functions differ by 3.3%. Inclusive spectral functions are the basis for QCD analyses, which deliver an accurate determination of the strong coupling constant, quantitative information on nonperturbative contributions and a measurement of the mass of the strange quark.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.