  The nondetection of neutrinos coming from Gamma Ray Bursts (GRBs) by the
IceCube experiment has raised serious questions on our understanding of GRB's
and the mechanism of neutrino flux production in them. Motivated by this and
the need for a precise calculation for GRB neutrino flux, here we study the
effects of beyond standard model physics on the GRB neutrino flux. In the
internal shock model of GRB, high energy neutrinos are expected from muon, pion
and kaon decays. Using the latest best fit neutrino oscillation parameters, we
compute the expected flux on earth for standard as well as non-standard
oscillation scenarios. Among the non-standard scenarios, we consider neutrino
decay, pseudo-dirac nature of neutrinos and presence of one eV scale light
sterile neutrino. Incorporating other experimental bounds on these new physics
scenarios, we show that neutrino decay scenario can significantly alter the
neutrino flux on earth from the expected ones whereas the corresponding changes
for pseudo-dirac and sterile neutrino cases are moderate.
