Related papers: The Evaluation of V_{ud}, Experiment and Theory
Superallowed $0^+ \to 0^+$ nuclear beta decay provides a direct measure of the weak vector coupling constant, $\GV$. We survey current world data on the nine accurately determined transitions of this type, which range from the decay of…
Unitarity along with precision measurements of sin2\beta, V_{us} and V_{cb} allows one to find a lower bound V_{ub}\geq 0.0035 which, on using the recently measured angle \alpha of the unitarity triangle, translates to V_{ub}= 0.0035\pm…
Prompted by the level of accuracy now being achieved in tests of the unitarity of the CKM matrix, we consider the possible modification of the Fermi matrix element for the $\beta$-decay of a neutron, including possible in-medium and isospin…
We use the exclusive baryonic $B$ decays to determine the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{ub}$. From the relation $|V_{ub}|^2/|V_{cb}|^2=({\cal B}_\pi/{\cal B}_D){\cal R}_{ff}$ based on $B^-\to p\bar p \pi^-$ and $\bar…
The measured $ft$-values for superallowed $0^{+} \to 0^{+}$ nuclear $\beta$-decay can be used to obtain the value of the vector coupling constant and thus to test the unitarity of the Cabibbo-Kobayashi-Maskawa matrix. An essential…
Determinations of $\vud$ and $\vus$ along with their implications for the unitarity test $\vud^2+\vus^2+\vub^2=1$ are discussed. The leading two loop radiative corrections to neutron $\beta$-decay are evaluated and used to derive a refined…
Pion beta decay, $\pi^+\to \pi^0 e^+\nu(\gamma)$, provides a theoretically clean $\pm 0.3\%$ determination of the CKM matrix element $V_{\text{ud}}$. That value falls short of super-allowed nuclear beta decays where an order of magnitude…
A new critical survey is presented of all half-life, decay-energy and branching-ratio measurements related to 20 0+ to 0+ beta decays. Compared with our last review, there are numerous improvements: First, we have added 27 recently…
The matrix element Vud of the CKM matrix can be determined by two independent measurements on neutron decay: the neutron lifetime tau and the ratio of coupling constants lambda, which is most precisely determined by measurements of the beta…
We point out that the measurements of the CP asymmetries in neutral B-decays together with a measurement of $Br(K_L\to \pi^\circ\nu\bar\nu)$ and the known value of $\mid V_{us}\mid $ can determine {\it all} elements of the…
We propose a new method for precise determination of |V_{td} / V_{ub}| from the ratios of branching ratios BR(B -> \rho \nu \bar \nu ) / BR(B ->\rho l \nu ) and BR(B -> \pi \nu \bar \nu ) / BR(B -> \pi l \nu ). These ratios depend only on…
We propose a model-independent method to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ from exclusive $B$ and $D$ decays. Combining information obtainable from $B\to \rho\ell\bar\nu_\ell$, $B\to…
The aim of the paper is to propose another tool for phenomenological analyses of experimental data from superallowed nuclear and neutron $\beta$ decays, and from leptonic and semileptonic decays, that allows the finding of the most probable…
The Cabibbo-Cobayashi-Maskawa (CKM) matrix parametrizes the misalignement between the up- and down-quark mass basis in the Standard Model (SM). The observation of first row CKM unitarity violation has recently emerged as a new anomaly of…
New developments in both the theories and experiments related to the extraction of the top-row Cabibbo-Kobayashi-Maskawa matrix elements $V_{ud}$ and $V_{us}$ led to a series of new anomalies, for instance the apparent violation of the…
The current value of Vud is determined from superallowed beta-decay experiments. Other methods, briefly summarised here, have to overcome specific experimental hurdles before they are competitive. However, the nuclear results do depend on a…
It has been proposed to determine the CKM matrix element |V_ub| in a model-independent way from a combination of rare and semileptonic B and D decays near the zero recoil point. An essential ingredient in such a determination is a heavy…
Measurements of neutron beta decay observables required to determine $|V_{ud}|$ are reaching the 0.1% accuracy. In this paper we review the calculation of the decay rate of this process, discuss its relevant uncertainties, and obtain an…
We present a determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{cb}$ using $B\to D\ell\nu$ decays. The result is based on $e^+e^-\to\Upsilon(4S)$ data recorded by the Belle II detector corresponding to…
Recent experimental and theoretical results on kaon semileptonic decays have significantly improved the determination of the CKM matrix element V_us. After briefly summarizing the impact of the new experimental determinations, I will…