Radiative Corrections to Semileptonic Beta Decays: Progress and Challenges

We review some recent progress in the theory of electroweak radiative corrections in semileptonic decay processes. The resurrection of the so-called Sirlin’s representation based on current algebra relations permits a clear separation between the perturbatively-calculable and incalculable pieces in the O(GFα) radiative corrections. The latter are expressed as compact hadronic matrix elements that allow systematic non-perturbative analysis such as dispersion relation and lattice QCD. This brings substantial improvements to the precision of the electroweak radiative corrections in semileptonic decays of pion, kaon, free neutron and JP=0+ nuclei that are important theory inputs in precision tests of the Standard Model. Unresolved issues and future prospects are discussed.

The Neutrino Decay of the Free Neutron and the Neutrino Structure According to the Planck Vacuum Theory

The Planck vacuum (PV) theory derives equations for the neutrino and antineutrino, and relates them to the unstable free neutron and antineutron. Remarkably, these neu- trons and neutrinos share the same wavefunction solutions that describe the proton and electron and their antiparticle cores. The neutrino and antineutrino are chargeless and massless; so their propagation through matter goes unnoticed, making these neutrinos invisible. The equations to follow that describe these pseudo-particles are the theoretical embodiment of the circa 1930 Pauli neutrino hypothesis. Finally, depending on one’s perspective, the neutrons can be viewed as decaying meta-particles or as stable nuclear particles.

Off-centred force-free neutron star magnetospheres

Neutron star electromagnetic activity produces pairs that fill their magnetosphere represented to the zeroth order by the force-free approximation. Neither dissipation nor acceleration nor radiation from charged particles is expected from this simplified model. So far, only centred dipole magnetic fields have been studied in this limit. In this paper, we explore the consequences of a rotating off-centred dipole on the force-free magnetosphere, showing the new magnetic field geometry, its spin-down luminosity as well as the electromagnetic kick and torque felt by the neutron star. Solutions are obtained by time-dependent numerical simulations of the force-free regime using our pseudo-spectral code written in spherical coordinates. Our results are also compared to known analytical expressions found for the off-centred vacuum dipole by an expansion to lowest order in the parameter ε = d/R, where d is the displacement of the dipole from the stellar centre and R the neutron star radius. The presence of a force-free plasma enhances the spin-down luminosity as well as the electromagnetic kick and torque with respect to a centred force-free dipole. The impact on isolated and binary neutron stars is revised in light of these new results.

This The Neutron Meta-Particles and their Decay as Viewed in the Planck Vacuum Theory

The mean life of the free neutron is about fifteen minutes, after which it decays into a proton plus an electron and an electron-neutrino. According to the Planck vacuum (PV) theory, however, it is the neutron and ``antineutron" meta-particles (MP)s that decay, in roughly fifteen minutes, into the stable electron and proton cores. The electron and proton core spins remain constant during the transformations-so there is no need for the neutrino spin correction during the decay process, bringing into question the validity of the neutrino itself.

On the Free Neutron Decay with Neutrino(s) Interactions

This paper proposes a mechanism for the decay of free neutron with interactions with neutrino(s). A mathematical framework is developed using canonical ensemble framework for the interactions. Probability distribution of neutron discrete energy states has been derived which is a function of neutrino-zeta – a macroscopic property of neutrinos. Consequently, a relationship between neutron decay constant and probability of neutron beta decay is provided, assuming linear proportionality. Furthermore, qualitative explanation of neutron lifetime puzzle, where discrepancy in lifetime measurements based on measurement method (Bottle vs Beam), is related to neutrino microscopic cross-sections. In addition, inverse beta-decay reaction of proton and beta-negative and beta-positive reaction of radionuclides have been analyzed using the proposed mechanism. The probabilities of beta-negative and beta-positive reactions in nature are qualitatively in agreement with the proposed mechanism. Lastly, way to test the mechanism experimentally with reactor neutrinos and neutrino beams has been presented.

Radiative pulsar magnetospheres: aligned rotator

ABSTRACT Force-free neutron star magnetospheres are nowadays well known and found through numerical simulations. Even extension to general relativity has recently been achieved. However, those solutions are by definition dissipationless, meaning that the star is unable to accelerate particles and let them radiate any photon. Interestingly, the force-free model has no free parameter however it must be superseded by a dissipative mechanism within the plasma. In this Letter, we investigate the magnetosphere electrodynamics for particles moving in the radiation reaction regime, using the limit where acceleration is fully balanced by radiation, also called Aristotelian dynamics. An Ohm’s law is derived, from which the dissipation rate is controlled by a one parameter family of solutions depending on the pair multiplicity κ. The spatial extension of the dissipation zone is found self-consistently from the simulations. We show that the radiative magnetosphere of an aligned rotator tends to the force-free regime whenever the pair multiplicity becomes moderately large, κ ≫ 1. However, for low multiplicity, a substantial fraction of the spin-down energy goes into particle acceleration and radiation in addition to the Poynting flux, the latter remaining only dominant for large multiplicities. We show that the work done on the plasma occurs predominantly in the equatorial current sheet right outside the light-cylinder.