Dresden 2013 – scientific programme
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T: Fachverband Teilchenphysik
T 20: Neutrinophysik (Theorie)
T 20.6: Talk
Tuesday, March 5, 2013, 18:00–18:15, WIL-B122
Decay of neutrinos from cosmological sources and prospects of observation at neutrino telescopes — •Mauricio Bustamante, Philipp Baerwald, and Walter Winter — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany
We explore the possibility that ultra-high energy neutrinos produced at cosmological sources decay during their propagation. By solving a redshift-dependent decay equation, we find important conceptual differences compared to more rudimentary treatments of neutrino decay. Notably, we find that the maximum travel distance is bounded by the Hubble length, so that the common notion that longer neutrino lifetimes can be probed by using more distant sources is valid only for redshifts below ∼ 1. Using a sophisticated calculation of the neutrino flux from gamma-ray bursts, we discuss the effects of decay on the neutrino spectra and flavor ratios. If ν1 is stable, as implied by the observation of SN 1987A, and if ν2 and ν3 have lifetimes much shorter than their current bounds, then the expected νµ flux at PeV energies, where IceCube is most sensitive, is reduced in approximately one order of magnitude, while the νe flux is only slightly affected. This suggests that it is possible that no muon tracks from gamma-ray burst neutrinos will be found in the experiment, and that only cascade measurements will have to be used to reliably study high-energy astrophysical neutrinos. As a result, the two cascade events recently detected by IceCube at PeV energies might not be accompanied by muon tracks of comparable energies.