Eur. Phys. J. C (2022) 82: 1031
https://doi.org/10.1140/epjc/s10052-022-10795-y

Regular Article - Experimental Physics

Detection of astrophysical tau neutrino candidates in IceCube

¹ III. Physikalisches Institut, RWTH Aachen University, 52056, Aachen, Germany
² Department of Physics, University of Adelaide, 5005, Adelaide, Australia
³ Department of Physics and Astronomy, University of Alaska Anchorage, 3211 Providence Dr., 99508, Anchorage, AK, USA
⁴ Department of Physics, University of Texas at Arlington, Box 19059, 502 Yates St., Science Hall Rm 108, 76019, Arlington, TX, USA
⁵ CTSPS, Clark-Atlanta University, 30314, Atlanta, GA, USA
⁶ School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 30332, Atlanta, GA, USA
⁷ Department of Physics, Southern University, 70813, Baton Rouge, LA, USA
⁸ Department of Physics, University of California, 94720, Berkeley, CA, USA
⁹ Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA
¹⁰ Institut für Physik, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
¹¹ Fakultät für Physik and Astronomie, Ruhr-Universität Bochum, 44780, Bochum, Germany
¹² Science Faculty CP230, Université Libre de Bruxelles, 1050, Brussels, Belgium
¹³ Vrije Universiteit Brussel (VUB), Dienst ELEM, 1050, Brussels, Belgium
¹⁴ Department of Physics and Laboratory for Particle Physics and Cosmology, Harvard University, 02138, Cambridge, MA, USA
¹⁵ Department of Physics, Massachusetts Institute of Technology, 02139, Cambridge, MA, USA
¹⁶ Department of Physics and Institute for Global Prominent Research, Chiba University, 263-8522, Chiba, Japan
¹⁷ Department of Physics, Loyola University Chicago, 60660, Chicago, IL, USA
¹⁸ Department of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
¹⁹ Department of Physics, University of Maryland, 20742, College Park, MD, USA
²⁰ Department of Astronomy, Ohio State University, 43210, Columbus, OH, USA
²¹ Department of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, 43210, Columbus, OH, USA
²² Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
²³ Department of Physics, TU Dortmund University, 44221, Dortmund, Germany
²⁴ Department of Physics and Astronomy, Michigan State University, 48824, East Lansing, MI, USA
²⁵ Department of Physics, University of Alberta, T6G 2E1, Edmonton, AB, Canada
²⁶ Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058, Erlangen, Germany
²⁷ Physik-Department, Technische Universität München, 85748, Garching, Germany
²⁸ Département de physique nucléaire et corpusculaire, Université de Genève, 1211, Geneva, Switzerland
²⁹ Department of Physics and Astronomy, University of Gent, 9000, Gent, Belgium
³⁰ Department of Physics and Astronomy, University of California, 92697, Irvine, CA, USA
³¹ Institute for Astroparticle Physics, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
³² Department of Physics and Astronomy, University of Kansas, 66045, Lawrence, KS, USA
³³ SNOLAB, 1039 Regional Road 24, Creighton Mine 9, P3Y 1N2, Lively, ON, Canada
³⁴ Department of Physics and Astronomy, UCLA, 90095, Los Angeles, CA, USA
³⁵ Department of Physics, Mercer University, 31207-0001, Macon, GA, USA
³⁶ Department of Astronomy, University of Wisconsin-Madison, 53706, Madison, WI, USA
³⁷ Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin-Madison, 53706, Madison, WI, USA
³⁸ Institute of Physics, University of Mainz, Staudinger Weg 7, 55099, Mainz, Germany
³⁹ Department of Physics, Marquette University, 53201, Milwaukee, WI, USA
⁴⁰ Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
⁴¹ Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, 19716, Newark, DE, USA
⁴² Department of Physics, Yale University, 06520, New Haven, CT, USA
⁴³ Department of Physics, University of Oxford, Parks Road, OX1 3PU, Oxford, UK
⁴⁴ Department of Physics, Drexel University, 3141 Chestnut Street, 19104, Philadelphia, PA, USA
⁴⁵ Physics Department, South Dakota School of Mines and Technology, 57701, Rapid City, SD, USA
⁴⁶ Department of Physics, University of Wisconsin, 54022, River Falls, WI, USA
⁴⁷ Department of Physics and Astronomy, University of Rochester, 14627, Rochester, NY, USA
⁴⁸ Oskar Klein Centre and Department of Physics, Stockholm University, 10691, Stockholm, Sweden
⁴⁹ Department of Physics and Astronomy, Stony Brook University, 11794-3800, Stony Brook, NY, USA
⁵⁰ Department of Physics, Sungkyunkwan University, 16419, Suwon, Korea
⁵¹ Institute of Basic Science, Sungkyunkwan University, 16419, Suwon, Korea
⁵² Department of Physics and Astronomy, University of Alabama, 35487, Tuscaloosa, AL, USA
⁵³ Department of Astronomy and Astrophysics, Pennsylvania State University, 16802, University Park, PA, USA
⁵⁴ Department of Physics, Pennsylvania State University, 16802, University Park, PA, USA
⁵⁵ Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
⁵⁶ Department of Physics, University of Wuppertal, 42119, Wuppertal, Germany
⁵⁷ DESY, 15738, Zeuthen, Germany
⁵⁸ Università di Padova, 35131, Padua, Italy
⁵⁹ Earthquake Research Institute, University of Tokyo, Bunkyo, 113-0032, Tokyo, Japan

^a analysis@icecube.wisc.edu https://icecube.wisc.edu/

Received: 15 June 2022
Accepted: 12 September 2022
Published online: 15 November 2022

Abstract

High-energy tau neutrinos are rarely produced in atmospheric cosmic-ray showers or at cosmic particle accelerators, but are expected to emerge during neutrino propagation over cosmic distances due to flavor mixing. When high energy tau neutrinos interact inside the IceCube detector, two spatially separated energy depositions may be resolved, the first from the charged current interaction and the second from the tau lepton decay. We report a novel analysis of 7.5 years of IceCube data that identifies two candidate tau neutrinos among the 60 “High-Energy Starting Events” (HESE) collected during that period. The HESE sample offers high purity, all-sky sensitivity, and distinct observational signatures for each neutrino flavor, enabling a new measurement of the flavor composition. The measured astrophysical neutrino flavor composition is consistent with expectations, and an astrophysical tau neutrino flux is indicated at 2.8 significance.