Related papers: On V_ud determination from kaon decays
Surveying known hadronic rare B decays, we find that the factorization approximation can give a coherent account of $K\pi$, $\pi\pi$ and $\rho^0\pi^+$ data and give predictions for $\omega^0\pi^+$, $\rho\pi$ and $K^*\pi$ modes, {\it if…
A simple matching procedure is proposed to extract constraints on effective meson theories. In this way, a QCD prediction for the pion decay constant is found, F(pi)=2 m(pi)/pi, i.e. approximately 90MeV. The same procedure also determines…
An approach is discussed on the determination of the leading order hadronic contribution to the muon anomaly, $a_\mu^{HAD}$, based entirely on theory. This method makes no use of $e^+ e^-$ annihilation data, a likely source of the current…
We search for decays of a B meson into a neutral D meson and a kaon, with the D meson decaying into K+pi-pi0. This final state can be reached through the b --> c transition B- -> D0K- followed by the doubly Cabibbo-suppressed D0 -->…
We update the determination of |V_us| using semielectronic and semimuonic decays of K mesons. A modest improvement of 15% with respect to its present value is obtained for the error bar of this matrix element when we combine the four…
In this talk I briefly review the precision test of the first row CKM unitarity, focusing mainly on $V_{ud}$ and $V_{us}$ extracted from pion, kaon, neutron and superallowed nuclear beta decays. I will discuss the current status of several…
The $K^+ \to \pi^0 \pi^0 e^+ \nu$ ($K_{e4}^{00}$) decay has been measured with stopped positive kaons for a data sample of 216 events. A comparison of the observed spectra with a Monte Carlo simulation determined the $K_{e4}^{00}$ form…
This review presents the analysis of leptonic and semileptonic kaon decays data done by the FlaviaNet Kaon Working group, as described in FlaviaNet Note of October 2008. Data include all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and…
We calculate radiative corrections to the flavor-changing neutral current process K --> pi l+ l-, both for charged and neutral kaon decays. While the soft-photon approximation is shown to work well for the muon channels, we discuss the…
Charged and neutral B decays into two charged pions and a charged or a neutral kaon are analyzed within the QCD factorization scheme where final state interactions before and after hadronization are included. The K*(892) and K*(1430)…
The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay $K^+ \to \pi^+ \nu \bar{ \nu }$, using the decay in flight of kaons in an unseparated beam with…
We use recent data on K^+ -> pi^+ e^+ e^-, together with known values for the pion form factor, to derive experimental values for the kaon electromagnetic form factor for 0 < q^2 < 0.125 (GeV/c)^2. The results are then compared with the…
We search for decays of a B meson into a neutral D meson and a kaon, with the D meson decaying into K+pi-pi0. This final state can be reached through the b --> c transition B- -> D0K- followed by the doubly Cabibbo-suppressed D0 -->…
We describe two recent developments of the radiative correction theory in semileptonic beta decays. For neutron, a novel dispersive analysis of the $\gamma W$-box diagram making use of neutrino scattering data leads to an improved precision…
The importance of rare $K$ decays especially in the context of a kaon unitarity triangle (KUT) is emphasized. The decay $K_L \to \pi^0 \nu \bar \nu$ is theoretically very clean but experimentally extremely challenging. The Standard Model…
We study theoretically the decay $\tau^- \to \nu_\tau P^- A$, with $P^-$ a $\pi^-$ or $K^-$ and $A$ an axial-vector resonance $b_1(1235)$, $h_1(1170)$, $h_1(1380)$, $a_1(1260)$, $f_1(1285)$ or any of the two poles of the $K_1(1270)$. The…
We analyse the hadronization structure of both vector and axial-vector currents leading to tau -> KKpi nu_tau decays. At leading order in the 1/Nc expansion, and considering only the contribution of the lightest resonances, we work out,…
The first dedicated search for the rare neutral-kaon decay $K_L^0\to\pi^0\nu\bar{\nu}$ has been carried out in the E391a experiment at the KEK 12-GeV proton synchrotron. The final upper limit of 2.6 $\times 10^{-8}$ at the 90% confidence…
We use recent data on K^+ -> pi^+e^+e^-, together with known values for the pion form factor, to derive the kaon electromagnetic form factor for 0 <q^2 <0.125 (GeV/c)^2. The results are then compared with predictions of the Linear sigma…
We study the decays $\pi^{+}\to l^{+}\nu_{l}$ in the presence of a background electromagnetic plane wave with circular polarization. We find that, in the presence of this background, the number of hadronic form factors required to describe…