Multi-GeV neutrinos from internal dissipation in gamma-ray burst fireballs

Subphotospheric internal shocks and transverse differences of the bulk Lorentz factor in relativistic fireball models of gamma-ray bursts (GRBs) lead to neutron diffusion relative to protons, resulting in inelastic nuclear collisions. This results in significant fluxes of nu(mu)(<(nu)over bar>(mu)) of similar to 3 GeV and nu(e)(<(nu)over bar>(e)) of similar to 2 GeV, scaling with the flow Lorentz factor eta < eta(pi) similar to 400. This extends significantly the parameter space for which neutrinos from inelastic collision are expected, which in the absence of the above effects requires values in excess of eta(pi). A model with sideways diffusion of neutrons from a slower wind into a fast jet can lead to production of nu(mu)(<(nu)over bar>(mu)) and nu(e)(<(nu)over bar>(e)) in the range 2-25 GeV or higher, depending on the value of eta. The emission from either of these mechanisms from GRBs at redshifts z similar to 1 may be detectable in suitably densely spaced detectors.