Related papers: Electroweak box diagram contribution for pion and …
CKM matrix is unitary by construction in the standard model(SM). The recent analyses on the first row of CKM matrix show $ \approx 3\sigma$ tension with unitarity. Nonperturbative calculations of the radiative corrections can reduce the…
Recently, the first ever lattice computation of the $\gamma W$-box radiative correction to the rate of the semileptonic pion decay allowed for a reduction of the theory uncertainty of that rate by a factor of $\sim3$. A recent dispersion…
We present the first realistic lattice QCD calculation of the $\gamma W$-box diagrams relevant for beta decays. The nonperturbative low-momentum integral of the $\gamma W$ loop is calculated using a lattice QCD simulation, complemented by…
The value of the V_{ud} matrix element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be derived from nuclear superallowed beta decays, neutron decay, and pion beta decay. We survey current world data for all three. Today, the most…
The leading electromagnetic (e.m.) and strong isospin-breaking corrections to the $\pi^+ \to \mu^+ \nu[\gamma]$ and $K^+ \to \mu^+ \nu[\gamma]$ leptonic decay rates are evaluated for the first time on the lattice. The results are obtained…
The value of the $V_{ud}$ matrix element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be derived from nuclear superallowed beta decays, neutron decay, and pion beta decay. We survey current world data for all three. Today, the most…
We present the first lattice QCD calculation of the universal axial $\gamma W$-box contribution $\square_{\gamma W}^{VA}$ to both superallowed nuclear and neutron beta decays. This contribution emerges as a significant component within the…
High-precision determinations of Cabibbo-Kobayashi-Maskawa (CKM) matrix elements are essential probes of physics Beyond the Standard Model (BSM). Current precision tests show a deficit in the first row unitarity relation. At the current…
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…
Although well studied, the neutron still offers a unique laboratory for precise tests of Standard Model (SM) predictions. Neutron decay is free of nuclear structure corrections present in nuclear beta decays, and, with a $10^8$ times larger…
Combining the ratio of experimental kaon and pion decay widths, Gamma(K to mu antineutrino{mu} (gamma)) / Gamma(pi to mu \antineutrino (gamma)), with a recent lattice gauge theory calculation of f{K}/f{pi} provides a precise value for the…
We discuss the recent progress in the study of semileptonic kaon and pion decays, including new experimental results, improved electroweak radiative corrections, form factor calculations and isospin-breaking effects. As a result, we obtain…
Neutrinoless double-beta ($0\nu\beta\beta$) decay is a heretofore unobserved process which, if observed, would imply that neutrinos are Majorana particles. Interpretations of the stringent experimental constraints on $0\nu\beta\beta$-decay…
The two most precise determinations of the CKM matrix element V_us are based on the analyses of leptonic and semileptonic kaon decays. These studies also rely on the lattice QCD calculations of two hadronic parameters, namely the ratio of…
The rare decays of a kaon into a pion and a charged lepton/antilepton pair proceed via a flavour changing neutral current and therefore may only be induced beyond tree level in the Standard Model. This natural suppression makes these decays…
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…
We report on a new measurement of neutron $\beta$-decay asymmetry. From the result \linebreak $A_0$ = -0.1189(7), we derive the ratio of the axial vector to the vector coupling constant $\lambda$ = ${\it g_A/g_V}$ = -1.2739(19). When…
The first lattice QCD calculation of the form factors governing $\Lambda_c \to \Lambda \ell^+ \nu_\ell$ decays is reported. The calculation was performed with two different lattice spacings and includes one ensemble with a pion mass of…
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…
The decreasing uncertainties in theoretical predictions and experimental measurements of several hadronic observables related to weak processes, which in many cases are now smaller than $\mathrm{O}(1\%)$, require theoretical calculations to…