TY  - JOUR
AU  - Mena, O.
AU  - Palomares-Ruiz, S.
AU  - Vincent, A. C.
PY  - 2014
DA  - 2014//
TI  - Flavor Composition of the High-Energy Neutrino Events in IceCube
T2  - Phys. Rev. Lett.
JO  - Physical Review Letters
SP  - 091103
EP  - 5pp
VL  - 113
IS  - 9
PB  - Amer Physical Soc
AB  - The IceCube experiment has recently reported the observation of 28 high-energy (> 30 TeV) neutrino events, separated into 21 showers and 7 muon tracks, consistent with an extraterrestrial origin. In this Letter, we compute the compatibility of such an observation with possible combinations of neutrino flavors with relative proportion (alpha(e:)alpha(mu):alpha tau)(circle plus). Although the 7: 21 track-to-shower ratio is naively favored for the canonical (1:1:1)(circle plus) at Earth, this is not true once the atmospheric muon and neutrino backgrounds are properly accounted for. We find that, for an astrophysical neutrino E-2 energy spectrum, (1:1:1)(circle plus). at Earth is disfavored at 81% C. L. If this proportion does not change, 6 more years of data would be needed to exclude (1:1:1)(circle plus) at Earth at 3 sigma C.L. Indeed, with the recently released 3-yr data, that flavor composition is excluded at 92% C. L. The best fit is obtained for (1:0:0)(circle plus). at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. If confirmed, this result would suggest either a misunderstanding of the expected background events or a misidentification of tracks as showers, or even more compellingly, some exotic physics which deviates from the standard scenario.
SN  - 0031-9007
UR  - http://arxiv.org/abs/arXiv:1404.0017
UR  - https://doi.org/10.1103/PhysRevLett.113.091103
DO  - 10.1103/PhysRevLett.113.091103
LA  - English
N1  - WOS:000341292800005
ID  - Mena_etal2014
ER  -