Unitarity and universality with kaon physics at KLOE - High Energy Physics - Experiment

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Abstract: All relevant inputs for the extraction of the CKM matrix element \vus from\kl, \ks and \kpm decays have been measured at KLOE. From a global fit usingonly KLOE results, but \ks lifetime, a value of $|\vus|\fzero = 0.2157 \pm0.0006$ is obtained, where \fzero is the form factor parametrizing the hadronicmatrix element evaluated at zero momentum transfer. Comparison of the values of\fVus for $K {e3}$ and $K {\mu3}$ modes provides a test of lepton universalityat 0.8% level of accuracy. The value $\vus-\vud=0.232315$ has been obtainedfrom the ratio $\GammaK\to\mu u-\Gamma\pi\to\mu u$ using KLOEmeasurement of $\BR\kpm \to \mudue$ and lattice calculation of the ratio ofdecay constants $f K-f {\pi}$. These results, together with $\vud =0.9741826$, are compatible at 0.6$\sigma$ level with CKM matrix unitarity.The universality of lepton and quark weak couplings can be tested andconstraints on new physics extensions of the Standard Model can be set usingthese very precise measurements from kaon decays.

Autor: Erika De Lucia for the KLOE Collaboration

Fuente: https://arxiv.org/