Complete theory of radiative corrections to K ℓ3 decays and the V us update

Abstract

Abstract We fill up the missing piece in our own re-analysis of the long-distance electromagnetic radiative corrections to semileptonic kaon decays by performing a rigorous study in the K → πμ + ν μ (γ) channels. With appropriate experimental and lattice inputs, we achieve a precision level of 10 −4 in these channels. This is comparable to our previous analysis in the K → πe + ν e (γ) channels. With this new result, we present an updated global analysis to extract the Standard Model parameter |V us | from semileptonic kaon decays. We obtain |V us | = 0.22308(55) and 0.22356(73), using the lattice average of the K 0 → π − transition form factor at N f = 2 + 1 + 1 and N f = 2 + 1, respectively.

Keywords

• CKM Parameters
• Electroweak Precision Physics
• Higher Order Electroweak Calculations
• Kaons