On the flavor composition of the high-energy neutrinos in IceCube

The IceCube experiment has recently released 3 years of data of the first ever detected high-energy (greater than or similar to 30 TeV) neutrinos, which are consistent with an extraterrestrial origin. In this talk, we compute the compatibility of the observed track-to-shower ratio with possible combinations of neutrino flavors with relative proportion (alpha(e) : alpha(mu) : alpha(tau))circle plus. Although this observation is naively favored for the canonical (1 : 1 : 1)circle plus at Earth, once we consider the IceCube expectations for the atmospheric muon and neutrino backgrounds, this flavor combination presents some tension with data. We find that, for an astrophysical neutrino E-v(-2) energy spectrum, (1 : 1 : 1)circle plus at Earth is currently disfavored at 92% C.L. We discuss the trend of this result by comparing the results with the 2-year and 3-year data. We obtain the best-fit for (1 : 0 : 0)circle plus at Earth, which cannot be achieved from any flavor ratio at sources with averaged oscillations during propagation. Although it is not statistically significant at present, 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.