Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube

IceCube Collaboration, Lionel Brayeur, Martin Casier, Catherine De Clercq, Krijn De Vries, Geraldina Tamara Golup, Jan Kunnen, Giuliano Maggi, Jonathan Miller, Erik Strahler, Nicolaas Van Eijndhoven

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153 Citations (Scopus)


A diffuse flux of astrophysical neutrinos above 100 TeV has been observed at the IceCube Neutrino Observatory. Here we extend this analysis to probe the astrophysical flux down to 35 TeV and analyze its flavor composition by classifying events as showers or tracks. Taking advantage of lower atmospheric backgrounds for showerlike events, we obtain a shower-biased sample containing 129 showers and 8 tracks collected in three years from 2010 to 2013. We demonstrate consistency with the (fe∶fμ∶fτ)⊕≈(1∶1∶1)⊕ flavor ratio at Earth commonly expected from the averaged oscillations of neutrinos produced by pion decay in distant astrophysical sources. Limits are placed on nonstandard flavor compositions that cannot be produced by averaged neutrino oscillations but could arise in exotic physics scenarios. A maximally tracklike composition of (0∶1∶0)⊕ is excluded at 3.3σ, and a purely showerlike composition of (1∶0∶0)⊕ is excluded at 2.3σ.
Original languageEnglish
Article number171102
Pages (from-to)1-8
Number of pages8
JournalPhysical Review Letters
Issue number17-1
Publication statusPublished - 28 Apr 2015


  • neutrino : flavor : ratio
  • neutrino : oscillation
  • neutrino : VHE
  • flavor : ratio
  • atmosphere : background
  • pi : decay
  • IceCube
  • showers
  • tracks
  • flux
  • observatory

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