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Search for Extremely-High-Energy Neutrinos and First Constraints on the Ultrahigh-Energy Cosmic-Ray Proton Fraction with IceCube
Rasha Abbasi, M. Ackermann, J. Adams, Sanjib Kumar Agarwalla, J. A. Aguilar, M. Ahlers, Jean-Marco Alameddine, N. M. Amin, K. Andeen, C. Argüelles, Y. Ashida, S. Athanasiadou, S. N. Axani, Rishi Babu, X. Bai, Aswathi Balagopal, M. Baricevic, S. W. Barwick, Simeon Bash, Vedant Basu, R. Bay, J. J. Beatty, J. Becker Tjus, Jakob Beise, Chiara Bellenghi, S. BenZvi, D. Berley, E. Bernardini, Dominique Besson, E. Blaufuss, Lucas Bloom, Summer Blot, F. Bontempo, Julia Book, Caterina Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, Bennett Brinson, Zoe Brisson-Tsavoussis, J. Brostean-Kaiser, Livia Brusa, Ryan T. Burley, Delaney Butterfield, Michael Campana, I. Caracas, Kiara Carloni, Jose Carpio, S. Chattopadhyay, Thien Nhan Chau, Z. Chen, D. Chirkin, S. Choi, Brian Clark, Alan Coleman, Peter John Cusack Coleman, G. H. Collin, A. Connolly, J. M. Conrad, Rebecca Corley, D. F. Cowen, C. De Clercq, James DeLaunay, Diyaselis Delgado, Sen Deng, Abhishek Desai, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, A. Diaz, J. C. Díaz–Vélez, P. Dierichs, M. Dittmer, A. Domi, Lincoln Draper, Hrvoje Dujmović, Daniel Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, Leonhard Eidenschink, A. Eimer, P. Eller, E. Ellinger, Sharif El Mentawi, R. Engel, H. Erpenbeck, Waleed Esmail, J. Evans, P. A. Evenson, Kwok Lung Fan, K. Fang, Kareem Ramadan Farrag, A. R. Fazely, Anatoli Fedynitch, N. Feigl, S. Fiedlschuster, C. Finley, Leander Fischer, D. B. Fox, A. Franckowiak, Satoshi Fukami, Philipp Fürst, J. S. Gallagher, Erik Ganster, Alfonso Garcia, M. García, Gaurav Garg, Eliot Genton, L. Gerhardt, L. Gerhardt, C. Girard-Carillo, Christian Gläser, T. Glüsenkamp, J. G. Gonzalez, S. Goswami, Alejandra Granados, D. Grant, S. J. Gray, S. Griffin, Spencer Griswold, Kathrine Mørch Groth, David Joseph Guevel, C. Günther, Pascal Gutjahr, C. Ha, Christian Haack, A. Hallgren, L. Halve, F. Halzen, Leon Hamacher, H. Hamdaoui, M. Ha Minh, Michael Handt, K. Hanson, J. Hardin, A. A. Harnisch, P. Hatch, A. Haungs, Jonas Häußler, K. Helbing, Jonas Hellrung, J. Hermannsgabner, L. Heuermann, Nils Heyer, S. Hickford, A. Hidvegi, Colton Hill, G. C. Hill, Ramy Hmaid, K. D. Hoffman, Sam Hori, K. Hoshina, Matheus Hostert, Wenjie Hou, Thomas Huber, K. Hultqvist, Mirco Huennefeld, R. Hussain, Karolin Hymon, A. Ishihara, W. Iwakiri, Marc Jacquart, Samyak Jain, Oliver Janik, M. Jansson, Minjin Jeong, Miaochen Jin, B. J. P. Jones, N. Kamp, Donghwa Kang, Woosik Kang, X. S. Kang, A. Kappes, D. Kappesser, Leonora Kardum, T. Karg, Martina Karl, A. Karle, Akanksha Katil, U. Katz, M. Kauer, J. L. Kelley, Manish Khanal, A. Khatee Zathul, Ali Kheirandish, J. Kiryluk, S. R. Klein, Yukiho Kobayashi, Alina Kochocki, Ramesh Koirala, H. Kolanoski, Tomas Kontrimas, L. Köpke, Claudio Kopper, D. J. Koskinen, Paras Koundal, M. Kowalski, T. Kozynets, Gerhard Krieger, J. Krishnamoorthi, T. Krishnan, Karlijn Kruiswijk, E. Krupczak, Anil Kumar, E. Kun, N. Kurahashi, Neha Navnitkumar Lad, Cristina Lagunas Gualda, M. Lamoureux, M. J. Larson, Frederik Hermann Lauber, Jeffrey Lazar, Kayla Leonard DeHolton, A. Leszczyńska, J. Liao, Massimiliano Lincetto, Y. T. Liu, M. Liubarska, Christina Love, L. Lu, Francesco Lucarelli, William Luszczak, Yang Lyu, J. Madsen, Else Magnus, Kendall Mahn, Y. Makino, Elena Manao, Sarah Mancina, Alicia Mand, W. Marie Sainte, I. C. Mariş, Szabolcs Márka, Z. Márka, M. Marsee, Ivan Martínez-Soler, R. Maruyama, Finn Mayhew, Frank McNally, J. V. Mead, K. Meagher, S. Mechbal, A. Medina, Maximilian Meier, Y. Merckx, Lukas Merten, J. Mitchell, T. Montaruli, R. W. Moore, Y. Morii, R. Morse, Marjon Moulai, Tista Mukherjee, Richard Naab, M. Nakos, U. Naumann, Jannis Necker, Akshima Negi, Ludwig Neste, M. Neumann, Hans Niederhausen, M. U. Nisa, K. Noda, A. Noell, Alexander S. Novikov, A. Obertacke Pollmann, Vivian O'Dell, A. Olivas, R. Orsoe, J. Osborn, Erin O’Sullivan, Veronika Palušová, Hershal Pandya, N. Park, G. K. Parker, V. A. Parrish, Ek Narayan Paudel, Larissa Paul, C. Pérez de los Heros, Teresa Pernice, J. Peterson, A. Pizzuto, M. Plum, Axel Pontén, Y. Popovych, M. Prado Rodriguez, B. Pries, R. Procter-Murphy, G. T. Przybylski, Lilly Pyras, Christoph Raab, J. Rack-Helleis, N. Rad, Martin Langgård Ravn, K. Rawlins, Z. Rechav, Abdul Rehman, E. Resconi, S. Reusch, W. Rhode, Benedikt Riedel, Adam Rifaie, E. J. Roberts, S. Robertson, Steven T. Rodan, Martin Rongen, Aske Rosted, C. Rott, T. Ruhe, L. Ruohan, D. Ryckbosch, I. Safa, Julian Saffer, Daniel Salazar-Gallegos, P. Sampathkumar, Alexander Sandrock, M. Santander, Sourav Sarkar, S. Sarkar, J. Savelberg, P. Savina, Patrick Schaile, M. Schaufel, H. Schieler, S. Schindler, Lea Schlickmann, B. Schlüter, Felix Schlüter, Nick Schmeisser, T. Schmidt, Judith Schneider, Frank Schröder, L. Schumacher, Sonke Schwirn, S. Sclafani, D. Seckel, Leo Seen, Mohammad Ful Hossain Seikh, Minhye Seo, S. Seunarine, P. Sevle Myhr, Riya Shah, S. Shefali, Nobuhiro Shimizu, M. Silva, Barbara Skrzypek, B. Smithers, R. Snihur, J. Soedingrekso, A. Søgaard, Dennis Soldin, Philipp Soldin, Giacomo Sommani, C. Spannfellner, G. M. Spiczak, C. Spiering, Juliana Stachurska, M. Stamatikos, T. Stanev, T. Stezelberger, T. Stürwald, Thomas Stuttard, G. W. Sullivan, I. Taboada, S. Ter–Antonyan, A. Terliuk, Matthias Thiesmeyer, W. G. Thompson, Jessie Thwaites, S. Tilav, Kirsten Tollefson, C. Tönnis, S. Toscano, D. Tosi, A. Trettin, Martin Unland Elorrieta, Anuj Kumar Upadhyay, K. Upshaw, A. Vaidyanathan, Nora Valtonen-Mattila, J. Vandenbroucke, N. van Eijndhoven, D. Vannerom, J. V. Santen, J. Vara, F. Varsi, J. Veitch-Michaelis, M. Venugopal, Matthias Vereecken, Sebastian Vergara Carrasco, Stef Verpoest, D. Veske, A. Vijai, C. Walck, A. Wang, C. Weaver, P. Weigel, A. Weindl, J. Weldert, Alex Wen, C. Wendt, J. Werthebach, M. Weyrauch, N. Whitehorn, C. H. Wiebusch, D. R. Williams, Lucas Witthaus, Martin Wolf, G. Wrede, Xiaolin Xu, J. P. Yanez, E. Yildizci, S. Yoshida, R. Young, Felix J. Yu, Shiqi Yu, Tianlu Yuan, Angela Zegarelli, Shuo Zhang, Z. Zhang, P. Zhelnin, Perri Zilberman, Melany Zimmerman
Bibliographic record
VenuePhysical Review Letters · 2025
Typearticle
Languageen
FieldPhysics and Astronomy
TopicAstrophysics and Cosmic Phenomena
Canadian institutionsSimon Fraser UniversityUniversity of AlbertaQueen's University
FundersOffice of Experimental Program to Stimulate Competitive ResearchJapan Society for the Promotion of ScienceNatural Sciences and Engineering Research Council of CanadaOffice of Polar ProgramsCollege of Engineering, Michigan State UniversityAlliance de recherche numérique du CanadaHelmholtz Alliance for Astroparticle PhysicsHelmholtz AssociationInstitute for Global Prominent Research, Chiba UniversityRWTH Aachen UniversityVillum FondenNational Research Foundation of KoreaMarsden FundBundesministerium für Bildung und ForschungSchweizerischer Nationalfonds zur Förderung der Wissenschaftlichen ForschungNational Science FoundationBelgian Federal Science Policy OfficeDeutsche ForschungsgemeinschaftDeutsches Elektronen-SynchrotronNational Energy Research Scientific Computing CenterAustralian Research CouncilWestern Canada Research GridFonds De La Recherche Scientifique - FNRSPolarforskningssekretariatetKnut och Alice Wallenbergs StiftelseUniversity of MarylandWisconsin Alumni Research FoundationCanada Foundation for InnovationMarquette UniversityVetenskapsrådetU.S. Department of EnergyUniversity of Wisconsin-MadisonNvidiaCarlsbergfondetOffice of Advanced CyberinfrastructureEuropean CommissionMichigan State UniversityFonds Wetenschappelijk Onderzoek
KeywordsCosmic rayPhysicsNeutrinoProtonNuclear physicsEnergy (signal processing)Ultra-high-energy cosmic rayAstrophysicsParticle physics
Abstract
We present a search for the diffuse extremely-high-energy neutrino flux using 12.6 years of IceCube data. The nonobservation of neutrinos with energies well above 10 PeV constrains the all-flavor neutrino flux at 10^{18} eV to a level of E^{2}Φ_{ν_{e}+ν_{μ}+ν_{τ}}≃10^{-8} GeV cm^{-2} s^{-1} sr^{-1}, the most stringent limit to date. Using these data, we constrain the proton fraction of ultrahigh-energy cosmic rays (UHECRs) above ≃30 EeV to be ≲70% (at 90% CL) if the cosmological evolution of the sources is comparable to or stronger than the star formation rate. This is the first result to disfavor the "proton-only" hypothesis for UHECR in this evolution regime using neutrino data. This result complements direct air-shower measurements by being insensitive to uncertainties associated with hadronic interaction models. We also evaluate the tension between IceCube's nonobservation and the ∼200 PeV KM3NeT neutrino candidate (KM3-230213A), finding it to be ∼2.9σ based on a joint-livetime fit between neutrino datasets.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
metaresearch head score (Codex)0.001
metaresearch head score (Gemma)0.002
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Observational · Consensus signal: Observational
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.004
Threshold uncertainty score0.009
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
Opus teacher head0.013
GPT teacher head0.249
Teacher spread0.236 · how far apart the two teachers sit on this one work
Validation status
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
The models applied no category: nothing in the taxonomy fit this work.
Study designObservational
Domainnot available
GenreEmpirical
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".
Quick stats
Citations31
Published2025
Admission routes2
Has abstractyes