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R. Horvat

Publications and source records attributed to R. Horvat.

41 records · Page 3Linked to original sources
arXiv1998

Medium effects in string-dilaton-induced neutrino oscillations

We consider the unconventional way to interpret the current data on solar neutrino oscillations as derived recently by Halprin and Leung from a string model based on the existence of the string dilaton field which remains massless in the low-energy world. The equivalence principle violation entailed by the existence of a massless dilaton may then produce neutrino oscillations even for neutrinos that are degenerate in mass. Here we calculate the medium-induced mass squared difference for solar neutrinos, which is due to their coherent interactions with the cosmic neutrino background and with solar plasma constituents. We show that this difference can naturally be large enough to satisfy the known experimental limits on the Just So solution as well as on the MSW solution of the solar neutrino problem.

hep-ph↗
arXiv1998

Pulsar velocities due to a violation of the equivalence principle by neutrinos

We consider the pulsar velocity problem and relate it to some unconventional neutrino oscillation mechanisms based on a violation of the equivalence principle by neutrinos. We show that the observed pulsar velocities may be explained by violations at the level from 10^{-9} to 10^{-10} in the case of a non-universal tensor neutrino-gravity coupling, whereas there is no solution in the case of a non-universal scalar neutrino-gravity coupling. Neutrinos may remain massless and the requisite magnetic field strength is similar to that in the conventional mass oscillation mechanism.

hep-ph↗
arXiv1997

On finite--temperature and --density radiative corrections to the neutrino effective potential in the early Universe

Finite-temperature and -density radiative corrections to the neutrino effective potential in the otherwise CP-symmetric early Universe are considered in the real-time approach of Thermal Field Theory. A consistent perturbation theory endowed with the hard thermal loop resummation techniques developed by Braaten and Pisarski is applied. Special attention is focused on the question whether such corrections can generate any nonzero contribution to the CP-symmetric part of the neutrino potential, if the contact approximation for the W-propagator is used.

hep-ph↗
arXiv1994

Covariant model of a quarkonium with the funnel potential

The bound--state problem for the pion as a quarkonium with the funnel (Coulomb--plus--linear) interaction is solved in a framework that combines the bilocal approach to mesons with the covariant generalization of the instantaneous--potential model. The potential interaction leads to dynamical breaking of chiral symmetry. However, the Coulomb potential leads to ultraviolet divergences that must be subtracted. A careful choice of the renormalization prescription is needed in order to get the correct chiral limit. The mass, the lepton decay constant of the pion, as well as the pion decay width in two photons are calculated.

hep-ph↗