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First determination of $f_+(0) |V_{us}|$ from a combined analysis of $\tau\to K\pi \nu_\tau$ decay and $\pi K$ scattering with constraints from $K_{\ell3}$ decays
- Source :
- JHEP06(2014)082
- Publication Year :
- 2013
-
Abstract
- We perform a combined analysis of $\tau\to K\pi \nu_\tau$ decay and $\pi K$ scattering with constraints from $K_{\ell3}$ data using a $N/D$ approach that fulfills requirements from unitarity and analyticity. We obtain a good fit of the $I=1/2$ $\pi K$ amplitude in the $P$ wave using the LASS data above the elastic region while in this region data are generated via Monte Carlo using the FOCUS results based on $D_{\ell 4}$ decay. The spectrum and branching ratio of $\tau\to K\pi \nu_\tau$ constrained by $K_{\ell3}$ decays are also well reproduced leading to $f_+(0) |V_{us}|= 0.2163 \pm 0.0014 $. Furthermore, we obtain the slope of the vector form factor $\lambda_+=(25.56 \pm 0.40) \times 10^{-3} $ while the value of the scalar form factor at the Callan-Treiman point is $\ln C=0.2062 \pm 0.0089$. Given the experimental precision our results are compatible with the Standard model.<br />Comment: 30 pages, 7 figures, Updated numerics and discussion slightly extended. Published version
- Subjects :
- High Energy Physics - Phenomenology
High Energy Physics - Experiment
Subjects
Details
- Database :
- arXiv
- Journal :
- JHEP06(2014)082
- Publication Type :
- Report
- Accession number :
- edsarx.1311.2569
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1007/JHEP06(2014)082