@article{9808ade397954989a064e9d214fc01b8,
title = "Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data",
abstract = "We report a quasidifferential upper limit on the extremely-high-energy (EHE) neutrino flux above 5×106 GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above 106 GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between 5×106 and 2×1010 GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of Eν2φνe+νμ+ντ≃2×10-8 GeV/cm2 sec sr at 109 GeV. A significant part of the parameter space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is disfavored independently of uncertain models of the extragalactic background light which previous IceCube constraints partially relied on.",
author = "{(IceCube Collaboration)} and Aartsen, {M. G.} and M. Ackermann and J. Adams and Aguilar, {J. A.} and M. Ahlers and M. Ahrens and {Al Samarai}, I. and D. Altmann and K. Andeen and T. Anderson and I. Ansseau and G. Anton and C. Arg{\"u}elles and J. Auffenberg and S. Axani and P. Backes and H. Bagherpour and X. Bai and A. Barbano and Barron, {J. P.} and Barwick, {S. W.} and V. Baum and R. Bay and Beatty, {J. J.} and {Becker Tjus}, J. and Becker, {K. H.} and S. Benzvi and D. Berley and E. Bernardini and Besson, {D. Z.} and G. Binder and D. Bindig and E. Blaufuss and S. Blot and C. Bohm and M. B{\"o}rner and F. Bos and S. B{\"o}ser and O. Botner and E. Bourbeau and J. Bourbeau and F. Bradascio and J. Braun and M. Brenzke and Bretz, {H. P.} and S. Bron and J. Brostean-Kaiser and A. Burgman and Busse, {R. S.} and Cowen, {D. F.}",
note = "Funding Information: We acknowledge the support from the following agencies: USA—U.S. National Science Foundation-Office of Polar Programs, U.S. National Science Foundation-Physics Division, Wisconsin Alumni Research Foundation, Center for High Throughput Computing (CHTC) at the University of Wisconsin-Madison, Open Science Grid (OSG), Extreme Science and Engineering Discovery Environment (XSEDE), U.S. Department of Energy-National Energy Research Scientific Computing Center, Particle astrophysics research computing center at the University of Maryland, Institute for Cyber-Enabled Research at Michigan State University, and Astroparticle physics computational facility at Marquette University; Belgium—Funds for Scientific Research (FRS-FNRS and FWO), FWO Odysseus and Big Science programmes, and Belgian Federal Science Policy Office (BELSPO); Germany—Bundesministerium f{\"u}r Bildung und Forschung (BMBF), Deutsche Forschungsgemeinschaft (DFG), Helmholtz Alliance for Astroparticle Physics (HAP), Initiative and Networking Fund of the Helmholtz Association, Deutsches Elektronen Synchrotron (DESY), and High Performance Computing cluster of the RWTH Aachen; Sweden—Swedish Research Council, Swedish Polar Research Secretariat, Swedish National Infrastructure for Computing (SNIC), and Knut and Alice Wallenberg Foundation; Australia—Australian Research Council; Canada—Natural Sciences and Engineering Research Council of Canada, Calcul Qu{\'e}bec, Compute Ontario, Canada Foundation for Innovation, WestGrid, and Compute Canada; Denmark—Villum Fonden, Danish National Research Foundation (DNRF); New Zealand—Marsden Fund; Japan—Japan Society for Promotion of Science (JSPS) and Institute for Global Prominent Research (IGPR) of Chiba University; Korea—National Research Foundation of Korea (NRF); Switzerland—Swiss National Science Foundation (SNSF). Publisher Copyright: {\textcopyright} 2018 American Physical Society.",
year = "2018",
month = sep,
day = "12",
doi = "10.1103/PhysRevD.98.062003",
language = "English (US)",
volume = "98",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "American Physical Society",
number = "6",
}