Related papers: Fermi matrix element with isospin breaking
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…
The calculated nuclear matrix elements for the neutrinoless double-beta ($0\nu\beta\beta$) decay suffer from several limitations. Predicted matrix-element values depend on the many-body method used to calculate them and, in addition, they…
An exactly solvable model for a description of the two-neutrino double beta decay transition of the Fermi type is considered. By using perturbation theory an explicit dependence of the two-neutrino double beta decay matrix element on the…
The extra contributions due to an extra generation of vector-like quarks to the isospin symmetry breaking observable associated with the radiative B->K^* \gamma decay is obtained. It is shown that this additional contribution is sensitive…
Based on an exact formalism, we study the effects of isospin-symmetry-breaking interactions on superallowed 0+ -> 0+ transitions. We calculate the second-order renormalization of the Fermi matrix element due to radial contributions and show…
We introduce a method for isospin restoration in the calculation of nuclear matrix elements (NME) for $0\nu\beta\beta$ and $2\nu\beta\beta$ decay within the framework of interacting boson model (IBM-2). With this method, we calculate NME…
After the recent high precision determinations of $V_{us}$ and $V_{ud}$, the first row of the CKM matrix shows more than $4\sigma$ deviation from unitarity. Two possible scenarios beyond the Standard Model can be investigated in order to…
We have studied the influences of isospin symmetry breaking of nucleon-nucleon interaction on the various properties of asymmetrical nuclear matter and $\beta$-stable matter. For asymmetrical nuclear matter, it is found that by including…
Superallowed $0^+\rightarrow 0^+$ transitions between $T=1$ nuclei have been a perfect avenue avenue for determining the Cabibbo-Kobayashi-Maskawa matrix element $V_{ud}$, which imposes powerful constraints on physics beyond the Standard…
We present a comprehensive analysis of the $\gamma W$ interference radiative correction to the neutron $\beta$-decay matrix element. Within a dispersion relations approach, we compute the axial-vector part of the $\gamma W$ box amplitude…
We evaluate the finite 1-loop threshold corrections, proportional to $tan\beta$, to the down quark mass matrix. These result in corrections to down quark masses and to Cabibbo-Kobayashi-Maskawa [CKM] matrix elements. The corrections to CKM…
We compute radiative corrections to the superallowed $\beta$ decay of $^{10}{\rm C}$ in an effective field theory approach using nuclear matrix elements obtained from quantum Monte Carlo calculations. These corrections are an important…
A new critical survey is presented of all half-life, decay-energy and branching-ratio measurements related to 20 superallowed 0+ --> 0+ beta decays. Included are 222 individual measurements of comparable precision obtained from 177…
We investigate the radial-overlap part of the isospin-symmetry breaking correction to superallowed $0^+\to 0^+$-decay using the shell-model approach similar to that of Refs. [1, 2]. The 8 sd-shell emitters with masses between $A=22$ and…
Precision studies of $0^{+} \rightarrow 0^{+}$ superallowed $\beta$ decays provide the necessary data to test stringently the CVC hypothesis. They will also provide a value for the weak vector coupling constant and the $V_{ud}$ quark mixing…
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…
The traditional Fermi function ansatz for nuclear beta decay describes enhanced perturbative effects in the limit of large nuclear charge $Z$ and/or small electron velocity $\beta$. We define and compute the quantum field theory object that…
We revisit the extraction of the $|V_{ud}|$ CKM matrix element from the superallowed transition decay rate of $^{26m}$Al$\rightarrow$$^{26}$Mg, focusing on finite nuclear size effects. The decay rate dependence on the $^{26m}$Al charge…
Determinations of vuds with super-allowed Fermi beta-decay in nuclei and of the weak charge of the cesium in atomic parity-violation deviate from the Standard Model predicitions by 2 sigma or more. In both cases, the Standard Model…
Data on superallowed Fermi beta decay in nuclei are compiled and electromagnetic corrections discussed. Recommended values for the weak vector coupling constant and the leading element of the Cabibbo-Kobayashi-Maskawa mixing matrix are…