%0 Journal Article
%T Flavor Composition of the High-Energy Neutrino Events in IceCube
%A Mena, O.
%A Palomares-Ruiz, S.
%A Vincent, A. C.
%J Physical Review Letters
%D 2014
%V 113
%N 9
%I Amer Physical Soc
%@ 0031-9007
%G English
%F Mena_etal2014
%O WOS:000341292800005
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=1920), last updated on Thu, 02 Oct 2014 11:13:12 +0000
%X 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.
%R 10.1103/PhysRevLett.113.091103
%U http://arxiv.org/abs/arXiv:1404.0017
%U https://doi.org/10.1103/PhysRevLett.113.091103
%P 091103-5pp