Flavor Ratio of Astrophysical Neutrinos above 35 TeV in IceCube

• Main Authors: Aartsen, M. G, Ackermann, M, Altmann, D, Bay, R, Berghaus, P, Berley, D, Bernhard, A, Besson, D. Z, Binder, G, Boersma, D. J, Bohm, C, Brayeur, L, Cheung, E, Christov, A, Coenders, S, Day, M, Dembinski, H, Desiati, P, Eagan, R, Eichmann, B, Eisch, J, Fazely, A. R, Feintzeig, J, Filimonov, K, Fuchs, T, Gladstone, L, Góra, D, Groß, A, Haack, C, Hallgren, A, Halzen, F, Hanson, K, Heereman, D, Heinen, D, Hellwig, D, Hickford, S, Hoshina, K, Jacobi, E, Jacobsen, J, Karle, A, Kolanoski, H, Kopper, S, Kriesten, A, Krings, K, Kroll, G, Kroll, M, Kunnen, J, Kurahashi, N, Kuwabara, T, Lanfranchi, J. L, Larsen, D. T, Larson, M. J, Lesiak-Bzdak, M, Leuermann, M, Maggi, G, Matis, H. S, McNally, F, Middell, E, Middlemas, E, Montaruli, T, Nahnhauer, R, Obertacke, A, Omairat, A, O'Murchadha, A, Palczewski, T, Paul, L, Penek, Ö, Heros, C. Pérez de los, Pfendner, C, Pinat, E, Przybylski, G. T, Rameez, M, Rawlins, K, Rees, I, Reimann, R, Relich, M, Richman, M, Ryckbosch, D, Saba, S. M, Santander, M, Schöneberg, S, Schulte, L, Schulz, O, Seckel, D, Spiczak, G. M, Stamatikos, M, Sutherland, M, Ter-Antonyan, S, Tilav, S, Usner, M, Vallecorsa, S, Vehring, M, Wallraff, M, Whitehorn, N, Wissing, H, Wolf, M, Xu, Y, Yodh, G, Zarzhitsky, P, Ziemann, J
• Format: Journal Article
• Language: English
• Published: 11-02-2015
• Subjects: Physics - High Energy Astrophysical Phenomena; Physics - High Energy Physics - Experiment
• DOI: 10.48550/arxiv.1502.03376

Phys. Rev. Lett. 114, 171102 (2015) A diffuse flux of astrophysical neutrinos above $100\,\mathrm{TeV}$ has been
observed at the IceCube Neutrino Observatory. Here we extend this analysis to
probe the astrophysical flux down to $35\,\mathrm{TeV}$ and analyze its flavor
composition by classifying events as showers or tracks. Taking advantage of
lower atmospheric backgrounds for shower-like 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
$(f_e:f_{\mu}:f_\tau)_\oplus\approx(1:1:1)_\oplus$ flavor ratio at Earth
commonly expected from the averaged oscillations of neutrinos produced by pion
decay in distant astrophysical sources. Limits are placed on non-standard
flavor compositions that cannot be produced by averaged neutrino oscillations
but could arise in exotic physics scenarios. A maximally track-like composition
of $(0:1:0)_\oplus$ is excluded at $3.3\sigma$, and a purely shower-like
composition of $(1:0:0)_\oplus$ is excluded at $2.3\sigma$.