Characterization of the Three-Flavor Composition of Cosmic Neutrinos with IceCube

IceCube Collaboration; R Abbasi; M Ackermann; J. Adams; S K Agarwalla; J. A Aguilar; M Ahlers; J. M Alameddine; S Ali; N. M Amin; K. Andeen; C Argüelles; M. Hostert

doi:10.1103/vntd-m133

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Characterization of the Three-Flavor Composition of Cosmic Neutrinos with IceCube

Journal article

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Characterization of the Three-Flavor Composition of Cosmic Neutrinos with IceCube

IceCube Collaboration, R Abbasi, M Ackermann, J. Adams, S K Agarwalla, J. A Aguilar, M Ahlers, J. M Alameddine, S Ali, N. M Amin, …

Physical review letters, Vol.137(8), 081002

08/18/2026

DOI: 10.1103/vntd-m133

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Abstract

The flavor composition of cosmic neutrinos probes both the physical properties of their sources and oscillations over energies and distances unreachable by terrestrial experiments. Using 11.4 yr of IceCube data, we analyze the flavor composition of the all-sky neutrino flux from 5 TeV-10 PeV, significantly lowering the analysis threshold from a previous minimum of 35 TeV. The best-fit flavor fractions are f(e); f(mu); f(tau) = 0.30(-0.15)(+0.20) , 0.37(-0.16)(+0.14), 0.33(-0.25)(+0.24) . For the first time, we report that neutrinos of all three flavors are present in the observed cosmic neutrino flux at > 90% confidence level. We infer the flavor composition at their sources, finding good agreement with pion decay while pure neutron decay is disfavored, with posterior probability 2.7 & times; 10(-5) (similar to 4 sigma).

Physical Sciences

Physics

Physics, Multidisciplinary

Science & Technology

Details

Title: Subtitle: Characterization of the Three-Flavor Composition of Cosmic Neutrinos with IceCube
Creators: IceCube Collaboration
R Abbasi (Contributor) - Loyola University Chicago
M Ackermann (Contributor) - Deutsches Elektronen-Synchrotron DESY
J. Adams (Contributor) - University of Canterbury
S K Agarwalla (Contributor) - University of Wisconsin–Madison
J. A Aguilar (Contributor) - Université Libre de Bruxelles
M Ahlers (Contributor) - University of Copenhagen
J. M Alameddine (Contributor)
S Ali (Contributor) - University of Kansas
N. M Amin (Contributor) - University of Delaware
K. Andeen (Contributor) - Marquette University
C Argüelles (Contributor) - Harvard University
M. Hostert (Contributor) - Harvard University Press
Resource Type: Journal article
Publication Details: Physical review letters, Vol.137(8), 081002
DOI: 10.1103/vntd-m133
ISSN: 0031-9007
eISSN: 1079-7114
Publisher: Amer Physical Soc
Number of pages: 9
Grant note: Frontera and Ranch Computing Project at the Texas Advanced Computing Center Funds for Scientific Research (FRS-FNRS) U.S. National Science Foundation-Office of Advanced Cyberinfrastructure Center for High Throughput Computing (CHTC) at the University of Wisconsin-Madison Japan Society for Promotion of Science (JSPS); Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT); Japan Society for the Promotion of Science Wisconsin Alumni Research Foundation Compute Ontario U.S. National Science Foundation-Office of Polar Programs; National Science Foundation (NSF) European Commission (Denmark) Astroparticle Physics Computational Facility at Marquette University
Language: English
Date published: 08/18/2026
Academic Unit: Physics and Astronomy
Record Identifier: 9985221947402771

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