[Paper Review] Fundamental Physics with High-Energy Cosmic Neutrinos

M. Ackermann, Ahlers, Markus+17 more|arXiv (Cornell University)|Jan 1, 2019

Astrophysics and Cosmic Phenomena214 references35 citations

TL;DR

This white paper outlines how high-energy cosmic neutrinos can probe new physics beyond the Standard Model, including Lorentz invariance violation, neutrino magnetic moments, and sterile neutrinos. By measuring their energy spectrum, flavor composition, arrival directions, and timing, upcoming neutrino observatories like IceCube-Gen2 and KM3NeT can test fundamental symmetries and new particles at energy scales unreachable in terrestrial experiments.

ABSTRACT

High-energy cosmic neutrinos can reveal new fundamental particles and interactions, probing energy and distance scales far exceeding those accessible in the laboratory. This white paper describes the outstanding particle physics questions that high-energy cosmic neutrinos can address in the coming decade. A companion white paper discusses how the observation of cosmic neutrinos can address open questions in astrophysics. Tests of fundamental physics using high-energy cosmic neutrinos will be enabled by detailed measurements of their energy spectrum, arrival directions, flavor composition, and timing.

Motivation & Objective

• To identify key fundamental physics questions in particle physics that can be addressed using high-energy cosmic neutrinos.
• To outline how future neutrino observatories can measure neutrino energy spectra, flavor composition, arrival directions, and timing to test new physics.
• To establish a roadmap for how cosmic neutrino observations can probe physics at energy scales far exceeding those accessible in Earth-based accelerators.
• To motivate the development of next-generation neutrino detectors by demonstrating their potential to resolve open questions in fundamental physics.
• To provide a scientific foundation for future investments in neutrino astronomy and its role in uncovering new physics.

Proposed method

• Analyzing the expected energy spectrum of high-energy cosmic neutrinos to constrain new physics beyond the Standard Model.
• Modeling the flavor composition of astrophysical neutrinos to detect deviations from standard three-flavor oscillations.
• Using arrival direction distributions to search for anisotropies linked to new physics, such as neutrino decay or Lorentz violation.
• Applying timing analysis of neutrino bursts relative to electromagnetic signals (e.g., gamma-ray bursts) to test Lorentz invariance and equivalence principle violations.
• Simulating neutrino interactions in large-volume detectors (e.g., IceCube, KM3NeT) to predict sensitivity to new particles and couplings.
• Integrating theoretical frameworks such as neutrino portal dark matter, doubly special relativity, and CPT violation to define measurable signatures.

Experimental results

Research questions

• RQ1 Can high-energy cosmic neutrinos reveal evidence of Lorentz invariance violation through energy-dependent time delays relative to photons?
• RQ2 Do deviations in the flavor ratio of cosmic neutrinos from the expected 1:1:1 indicate new physics such as neutrino decay or magnetic moment interactions?
• RQ3 Can the energy spectrum of cosmic neutrinos constrain the existence of sterile neutrinos or other weakly interacting particles?
• RQ4 Do time-resolved measurements of neutrino bursts from transient sources like blazars or gamma-ray bursts reveal violations of the equivalence principle?
• RQ5 Can the flavor composition of neutrinos from distant sources be used to probe new interactions or non-standard neutrino oscillations?

Key findings

• High-energy cosmic neutrinos can probe new physics at energy scales exceeding 10^16 GeV, far beyond the reach of terrestrial accelerators.
• Measurements of neutrino flavor ratios above 100 TeV can constrain neutrino magnetic moments to below 10^-15 Bohr magnetons.
• A detection of energy-dependent time delays between high-energy neutrinos and photons from gamma-ray bursts would provide evidence for Lorentz invariance violation.
• The arrival direction distribution of cosmic neutrinos can reveal anisotropies linked to new physics, such as neutrino decay or coupling to dark matter.
• Flavor composition measurements from next-generation detectors like IceCube-Gen2 could detect deviations from standard three-flavor oscillations, signaling new neutrino interactions.
• Timing coincidences between neutrino events and electromagnetic transients can be used to test the weak equivalence principle with sub-second precision.