Review on Flavianet analyses

Abstract

We present a global analysis of leptonic and semileptonic kaon decay data, including all recent results published by the BNL-E865, KLOE, KTeV, ISTRA+ and NA48 experiments. This analysis, in conjunction with precise lattice calculations of the hadronic matrix elements now available, leads to a very accurate determination of V us , and allows us to perform several stringent tests of the Standard Model.

precise SM tests

“…2.1. These allow a precise determination of the CKM matrix elements V us and of the ratio V us /V ud , as discussed in detail by Palutan [8] and illustrated in Figure 2: as seen there, the CKM passes perfectly the unitarity test, and with it an essential building block of the SM is experimentally confirmed. Even safer against hadronic uncertainties are ratios of decay rates in which the hadronic part cancels out completely, like in…”

“…The current status of these has been reviewed in the talks of Boyle [5] and Mescia [6]. Moreover, if one uses the independent determination of V ud from superallowed Fermi decay of nuclei together with F K /F π to extract V us from the ratio Γ(K → ℓν)/Γ(π → ℓν) one obtains two independent and compatible determinations of V us [7,8]. This nontrivial result confirms that the systematic uncertainties of lattice calculations are under good control.…”

Precision SM calculations and theoretical interests beyond the SM in Kl2 and Kl3 decays

“…With an accuracy of 0.5%, this determination becomes by now competitive with other determinations such as the one coming from τ decays, see [71]. In addition, a phenomenological determination of ∆ Kπ SU (2) , see section 2.1.2, is by now possible comparing the results on charged and neutral decay widths, Eq.…”

“…For discussions and details on the lattice set-ups and results, we refer to the forthcoming review by the Flavianet Lattice Averaging Group (FLAG) presented at this conference by G. Colangelo [59] and also to the talk by P. Boyle [70]. As presented in [71], taking for illustrative purpose the HPQCD-UKQCD result [65], one gets |V us |/|V ud | = 0.2319(15).…”

“…Refs. [35,38,71,78] for further discussions. The results from the different analyses are reported in the table, Fig.…”