Related papers: The Fermi function and the neutron's lifetime
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…
The experimental determination of V_{ud} from neutron beta decay requires accurate values of the neutron lifetime and the ratio of the weak axial-vector to vector coupling constants of the nucleon. The latter is derived from measurements of…
$\beta$-decay, a process that changes a neutron into a proton (and vice versa), is the dominant decay mode of atomic nuclei. This decay offers a unique window to physics beyond the standard model, and is at the heart of microphysical…
Fermi helped establish a new framework for understanding matter, based on quantum theory. This framework refines and improves traditional atomism in two crucial respects. First, the elementary constituents of matter belong to a very small…
The calculation of the $\mu$ decay is performed in V-A theory taking into account that, in agreement with the observation of the oscillations, the neutrinos must be massive. Provided that the masses of the electron and muon neutrinos are…
A spacetime-varying fine structure constant alpha(x^mu) could generate quantum corrections in some of the coefficients of the Lorentz-violating standard model extension (SME) associated with electrically charged fermions. The quantum…
The electron would decay into a photon and neutrino if the law of electric charge conservation is not respected. Such a decay would cause vacancy in closed shells of atoms giving rise to emission of x-rays and Auger electrons. Experimental…
The existing calculations of the nuclear matrix elements of the neutrinoless double $\beta$-decay differ by about a factor three. This uncertainty prevents quantitative interpretation of the results of experiments searching for this…
We employ, within the framework of Skyrme energy-density functional theory, the subtracted second random-phase approximation, recently developed for charge-exchange excitations, to compute $\beta$-decay half-lives in four nuclei, $^{24}$O,…
In this contribution we study the Dirac equation for a finite size proton in an external electric field with explicit introduction of Dirac-Pauli form factors. Our aim is twofold. On the one hand, we wish to study whether our conclusions…
The effective number of neutrino species, $N_{\rm eff}$, serves as a key fitting parameter extensively employed in cosmological studies. In this work, we point out a fundamental inconsistency in the conventional treatment of $N_{\rm eff}$…
The Standard Model extension with additional Lorentz violating terms allows for redefining the equation of motion of a propagating left-handed fermionic particle. The obtained Dirac-type equation can be embedded in a generalized…
A correction to the nuclear functional is proposed in order to improve the density of states around the Fermi surface. The induced effect of this correction is to produce a surface-peaked effective mass, whose mean value can be tuned to get…
We report the microscopic origins of the anomalously suppressed beta decay of 14C to 14N using the ab initio no-core shell model (NCSM) with the Hamiltonian from chiral effective field theory (EFT) including three-nucleon force (3NF) terms.…
The existing experimental evidence on the vector and axial-vector coupling constants, $G_V$ and $G_A$, for neutron $\beta$-decay exhibits two prominent problems: (i) the unitarity for the first row of the CKM matrix seems violated; (ii) one…
We propose a procedure to analyze the relation between the exact factorization of the electron-nuclear wave function and the Born-Oppenheimer approximation. We define the adiabatic limit as the limit of infinite nuclear mass. To this end,…
The nuclear energy density functional method at finite temperature is a useful tool for studies of nuclear structure at high excitation, and also for researches of nuclear matter involved in explosive stellar phenomena and neutron stars.…
In this paper we explore the time-reversal-odd triple-correlation coefficient in neutron beta decay, the so-called "D coefficient", using heavy-baryon effective field theory with photon degrees of freedom. We find that this framework allows…
Precision tests of the Standard Model using $\beta$ decay have always relied on a careful choice of transition to minimize residual nuclear structure uncertainties. Following breakthroughs in nucleon-level radiative corrections in the last…
The precise value of the neutron lifetime is of fundamental importance to particle physics and cosmology. The neutron lifetime recently obtained, 878.5 +/- 0.7stat +/- 0.3sys s, is the most accurate one to date. The new result for the…