Gamma-ray bursts (GRBs) are expected to provide a source of ultra high energy cosmic rays, accompanied with potentially detectable neutrinos at neutrino telescopes. Recently, IceCube has set an upper bound on this neutrino flux well below theoretical
expectation. We investigate whether this mismatch between expectation and observation can be due to neutrino decay. We demosntrate the phenomenological consistency and theoretical plausibility of the neutrino decay hypothesis. A potential implication is the observability of majoron-emitting neutrinoless double beta decay.
We show how neutrino data can be used in order to constrain the free parameters of possible extensions to the standard model of elementary particles (SM). For definiteness, we focus in the recently proposed unparticle scenario. We show that neutrino
data, in particular the MUNU experiment, can set stronger bounds than previous reported limits in the scale dimension parameter for certain region (d > 1.5). We compute the sensitivity of future neutrino experiments to unparticle physics such as future neutrino-electron scattering detectors, coherent neutrino-nuclei scattering as well as the ILC . In particular, we show that the measurement of coherent reactor neutrino scattering off nuclei provide a good sensitivity to the couplings of unparticle interaction with neutrinos and quarks.Finally our results are compared with the current astrophysical limits.
