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V(us) and m(s) from hadronic tau decays.
Elvira Gámiz1, Matthias Jamin, Antonio Pich
1Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
Physical Review Letters
|February 9, 2005
Summary
This study determines the CKM matrix element V(us) and the strange quark mass m(s) using hadronic tau decays. The results are competitive with existing methods and consistent with the Standard Model.
Area of Science:
- Particle Physics
- Hadronic Tau Decays
- CKM Matrix Elements
Background:
- Hadronic tau decays provide a unique probe for fundamental parameters in particle physics.
- Precise determination of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements is crucial for testing the Standard Model.
- The strange quark mass (m(s)) is an important parameter in Quantum Chromodynamics (QCD).
Purpose of the Study:
- To determine the magnitude of the CKM matrix element V(us) using experimental data from hadronic tau decays.
- To calculate the strange quark mass m(s) at a specific energy scale (2 GeV).
- To compare the extracted V(us) with values obtained from other processes, such as kaon decays.
Main Methods:
- Analysis of experimental results from the OPAL Collaboration on hadronic tau decays.
- Application of moments of the invariant mass distribution of tau decay products.
- Theoretical framework incorporating QCD corrections for precise calculations.
Main Results:
- Determination of V(us) = 0.2208 ± 0.0034.
- Determination of m(s)(2 GeV) = 81 ± 22 MeV.
- The experimental uncertainty on V(us) is currently the dominant error source.
Conclusions:
- The derived value of V(us) from tau decays is competitive with the standard extraction from K(e3) decays.
- The results are consistent with the unitarity of the CKM matrix.
- Future experimental improvements can further refine the precision of V(us).