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 ($E \geq 10^{6}$ 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, $μ$, and the violation of equivalence principle (VEP), parameterized by $Δf$, in a reasonable strength of magnetic field in the vicinity of the GRB. We point out that for $Δf \sim 10^{-25}(δm^2/1 {eV}^2)$, a resonant spin-flavour precession between $\barν_μ$ and $ν_τ$ may occur in the vicinity of GRB for $μ\sim 10^{-12} μ_{B}$ ($μ_{B}$ is Bohr magneton), thus enhancing the expected high energy $ν_τ$ flux from GRBs.