Atri Bhattacharya, Raj Gandhi, Werner Rodejohann, Atsushi Watanabe
We revisit the signatures of the Glashow resonance process $\bar{\nu}_e e \to
W$ in the high-energy astrophysical neutrino observatory IceCube. We note that
in addition to the standard hadronic and electromagnetic showers produced by an
incoming neutrino at the resonance energy of $E_\nu \approx 6.3$ PeV, there are
two clear signals of the process: the "pure muon" from $\bar{\nu}_e e \to
\bar{\nu}_\mu \mu$ and the "contained lollipop" from $\bar{\nu}_e e \to
\bar{\nu}_\tau \tau$. The event rate and the signal-to-background ratio (the
ratio of the resonant to concurrent non-resonant processes) are calculated for
each type of interaction, based on current flux limits on the diffuse neutrino
flux. Because of the low background in the neighborhood of the resonance, the
observation of only one pure muon or contained lollipop event essentially
signals discovery of the resonance, even if the expected event numbers are
small. We also evaluate the total event rates of the Glashow resonance from the
extra-galactic diffuse neutrino flux and emphasize its utility as a discovery
tool to enable first observations of such a flux. We find that one can expect
3.6 (0.65) events per year for a pure $pp$ ($p\gamma$) source, along with an
added contribution of 0.51 (0.21) from non-resonant events. We also give
results as a function of the ratio of $pp$ vs $p\gamma$ sources.
View original:
http://arxiv.org/abs/1108.3163
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