Effects of conversions for high energy neutrinos originating from cosmological gamma-ray burst fireballs

Abstract

We study neutrino conversions in the recently envisaged source of high energy ($E\ge 10^6$ GeV) neutrinos, that is, in the vicinity of cosmological gamma-ray burst fireballs (GRB). We consider mainly the possibility of neutrino conversions due to an interplay of neutrino transition magnetic moment, $\mu$, and the violation of equivalence principle (VEP), parameterized by $\Delta f$, in a reasonable strength of magnetic field in the vicinity of the GRB. We point out that for $\Delta f\sim 10^{-25}(\delta m^2/1{eV}^2)$, a resonant spin-flavour precession between ${\bar{\nu }}_{\mu }$ and ${\nu }_{\tau }$ may occur in the vicinity of GRB for $\mu \sim 10^{-12}{\mu }_B$ (${\mu }_B$ is Bohr magneton), thus enhancing the expected high energy ${\nu }_{\tau }$ flux from GRBs.

Comments: 12 pages, Latex (uses revtex), Two figures included as eps files)