Exploring New Propagation Scales With Galactic Neutrinos

TL;DR

This paper investigates testing new neutrino propagation physics using Galactic neutrinos observed by IceCube and KM3NeT. It analyzes two Beyond-Standard-Model scenarios: quasi-Dirac neutrinos with hyperfine mass splittings $δm^2$ and neutrino decays described by $α ≡ m/τ$, including both invisible and visible channels. Using the TANDEM Galactic emission model and projected detector responses, the authors forecast sensitivities via a joint Poisson likelihood analysis that incorporates backgrounds and an unconstrained Galactic flux normalization. They demonstrate that a combined IceCube+KM3NeT analysis can access $δm^2$ and $α$-dependent signatures, highlighting the potential to probe neutrino mass models with Galactic baselines.

Abstract

The recent observation of high-energy Galactic neutrinos by IceCube allows for searches of new physics affecting neutrino propagation on scales of $O(10^9-10^{15})\,\mathrm{km/GeV}$ in distance over energy. We assess the sensitivity of upcoming measurements of Galactic neutrinos by IceCube and KM3NeT to such new phenomena. We focus on two scenarios: quasi-Dirac neutrinos and neutrino decays. In the quasi-Dirac scenario, we find that joint measurements by IceCube and KM3NeT are sensitive to the mass-squared differences $δm^2 \in \left(10^{-13.5}~\mathrm{eV^2}, 10^{-11.9}~\mathrm{eV^2}\right)$ at the $90\%$ confidence level. For neutrino decays, the same measurements are sensitive to mass over lifetime ratios $m / τ> 10^{-12.3}~\mathrm{eV^2}$ at the same significance. Our results demonstrate that measurements of Galactic neutrinos by a global network of neutrino telescopes can probe signatures of neutrino mass models.

Figures (8)

• Figure 1: Expected rates of neutrinos from natural sources as a function of L/E. This figure depicts the rate of neutrinos from various natural sources, at ideal Earth-based detectors. We plot the rate as a function of the baseline to energy ratio $L/E$, in units of neutrinos per kiloton-year. For reference, the exposure of Super-Kamiokande and IceCube are indicated by grey dotted lines. To calculate the rate, we multiply the source flux by the relevant cross-section; for solar neutrinos, we use the neutrino-electron scattering cross-section, whereas for all other sources we use neutrino-nucleon cross-section. All sources except the solar atmospherics have been detected in the ranges shown.
• Figure 2: Spatial distribution of Galactic neutrinos under SM and BSM scenarios. Shown are maps of $z$-integrated Galactic neutrino emission at $10\,\mathrm{TeV}$ weighted by survival probability at Earth under a given BSM scenario (see \ref{['eq:QDinos', 'eq:invisibledecays']}). The emission model assumes a gas distribution as calculated in Ref. Soding:2025scd. Left: Neutrino emission under a SM scenario. Middle: Neutrino emission under a quasi-Dirac scenario with $\delta m^2 = 10^{-13}\,\mathrm{eV^2}$. Right: Neutrino emission, after decay with $\alpha = 10^{-13.6}\,\mathrm{eV^2}$.
• Figure 3: Survival probability of neutrino emission along different lines of sight in a quasi-Dirac scenario.Top: Galactic neutrino flux as a function of Galactic latitude $\ell$ and longitude $b$, with three representative sky locations marked: A at $(0^\circ, 0^\circ)$, B at $(60^\circ, 0^\circ)$, and C at $(0^\circ, 15^\circ)$. Middle: "Survival" probability, i.e. the probability that neutrinos along a given line of sight remain in active states, as a function of true neutrino energy. Bottom: "Survival" probability, accounting for energy and angular resolutions characteristic of cascade (above) and track (below) events.
• Figure 4: Survival probability of neutrino emission along different lines of sight in a decay scenario. Same as Fig. \ref{['fig:oscsmears_QD_soding']} (middle, bottom), but for an invisible decay scenario with $\alpha = 10^{-13.6}~\mathrm{eV^2}$.
• Figure 5: Predicted distributions of events from the Galactic center region in IceCube and KM3NeT under SM and QD scenarios. On the left, we show all IceCube cascade events within a wide Galactic window, ($|\ell| < 80^\circ,~|b| < 10^\circ$), whereas on the right we show KM3NeT track events in a narrower window ($|\ell| < 80^\circ,~|b| < 1^\circ$). Top rows: Distributions of galactic neutrinos in energy in the SM ($S_0$) and QD ($S_1$) scenarios, as well as of atmospheric neutrinos ($B$). Bottom rows: Ratio of the QD disappearance effect ($S_1 - S_0$) to the statistical uncertainty on the total event count, in each energy bin.