arXiv subjects

Alexandra Dobrynina

Publications and source records attributed to Alexandra Dobrynina.

3 recordsLinked to original sources

arXiv2020

Influence of magnetic field on beta-processes in supernova matter

An influence of a magnetic field on beta-processes is investigated under conditions of a core-collapse supernova. For realistic magnetic fields reachable in astrophysical objects we obtain simple analytical expressions for reaction rates of beta-processes as well as the energy and momentum transferred from neutrinos and antineutrinos to the matter. Based on the results of one-dimensional simulations of a supernova explosion, we found that, in the magnetic field with the strength $B \sim 10^{15}$ G, the quantities considered are modified by a few percents only and, as a consequence, the magnetic-field effects can be safely neglected, considering neutrino interaction and propagation in a supernova matter. The analytical results can be also applied for accretion discs formed at a merger of compact objects in close binary systems.

astro-ph.HE↗

arXiv2017

Photon-photon dispersion of TeV gamma rays and its role for photon-ALP conversion

The propagation of TeV gamma rays can be strongly modified by B-field induced conversion to axionlike particles (ALPs). We show that, at such high energies, photon dispersion is dominated by background photons - the only example where photon-photon dispersion is of practical relevance. We determine the refractive index for all energies and find that, for fixed energy density, background photons below the pair-production threshold dominate. The cosmic microwave background alone provides an "effective photon mass" of (m_gamma)^2 = -(1.01 neV * E/TeV)^2 for E < 1000 TeV. The extragalactic background light is subdominant, but local radiation fields in the galaxy or the source regions provide significant contributions. Photon-photon dispersion is small enough to leave typical scenarios of photon-ALP oscillations unscathed, but big enough to worry about it case by case.

astro-ph.HE↗

arXiv2016

Helicity oscillations of Dirac and Majorana neutrinos

The helicity of a Dirac neutrino with mass $m$ evolves under the influence of a $B$-field because it has a magnetic dipole moment proportional to $m$. Moreover, it was recently shown that a polarized or anisotropic medium engenders the same effect for both Dirac and Majorana neutrinos. Because a $B$-field polarizes a background medium, it instigates helicity oscillations even for Majorana neutrinos unless the medium is symmetric between matter and antimatter. Motivated by these observations, we review the impact of a $B$-field and of an anisotropic or polarized medium on helicity oscillations for Dirac and Majorana neutrinos from the common perspective of in-medium dispersion.

hep-ph↗