arXiv subjects

Mihaela-Andreea Baloi

Publications and source records attributed to Mihaela-Andreea Baloi.

4 recordsLinked to original sources

arXiv2023

Z boson emission by a neutrino in de Sitter expanding universe

Production of Z bosons in emission processes by neutrinos in the expanding de Sitter universe is studied by using perturbative methods. The total probability and transition rate for the spontaneous emission of a Z boson by a neutrino is computed analytically, then we perform a graphical analysis in terms of the expansion parameter. Our results prove that this process is possible only for large expansion conditions of the early Universe. Finally the density number of Z bosons is defined and we obtain a quantitative estimation of this quantity in terms of the density number of neutrinos.

hep-th↗

arXiv2019

Production of charged scalar particles with well defined angular momentum in de Sitter spacetime

We study the production of charged scalar particles with well defined angular momentum, in the presence of an external Coulomb field on de Sitter expanding universe. This process of particle production is studied as a perturbative phenomenon applying the theory of quantum electrodynamics on de Sitter spacetime developed in \cite{1}-\cite{3}. The probability of particle production is computed and our results show the dependence of the probability in terms of the orbital quantum number. Our graphical results show that, the most probable transitions are those that generate particles with small angular momentum. Is obtained also that the momentum is not conserved and that the probability of particle production is significative for large values of the Hubble's constant, corresponding to the early universe.

hep-th↗

arXiv2016

Fermion production in a magnetic field in a de Sitter Universe

The process of fermion production in the field of a magnetic dipole on a de Sitter expanding universe is analyzed. The amplitude and probability for production of massive fermions are obtained using the exact solution of the Dirac equation written in the momentum-helicity basis. We found that the most probable transitions are those that generate the fermion pair perpendicular to the direction of the magnetic field. The behavior of the probability is graphically studied for large/small values of the expansion factor, and a detailed analysis of the probability in terms of the angle between the momenta vectors of the particle and antiparticle is performed. The phenomenon of fermion production is significant only at large expansion which corresponds to the conditions from the early Universe. When the expansion factor vanishes we recover the Minkowski limit where this process is forbidden by the simultaneous energy-momentum conservation.

gr-qc↗

arXiv2015

Annihilation of the scalar pair into a photon on de Sitter spacetime

The annihilation of massive scalar particles in one photon on de Sitter expanding universe is studied, using perturbation theory. The amplitude and probability corresponding to this process is computed using the exact solutions of the Klein-Gordon and Maxwell equations on de Sitter geometry. Our results show that the expression of the total probability of photon emission is a function dependent on the ratio mass/expansion\, factor. We perform a graphical study of the total probability in terms of the parameter mass/expansion factor, showing that this effect is significant only in strong gravitational fields. We also obtain that the total probability for this process vanishes in the Minkowski limit.

hep-th↗