Visible decay of astrophysical neutrinos at IceCube

High energy astrophysical neutrinos interacting with ultralight dark matter (DM) can undergo flavour oscillations that induce an energy dependence in the flavour ratios. Such a dependence on the neutrino energy will reflect in the track to shower ratio in neutrino telescopes like IceCube or KM3NeT. This opens up a possibility to study DM density profiles of astrophysical objects like AGN, GRB etc., which are the suspected sources of such neutrinos.

Section: Jhep10(2021)004mentioning

confidence: 99%

Astronomy with energy dependent flavour ratios of extragalactic neutrinos

Karmakar

Pandey

Rakshit

2021

“…However, given the sensitivity of current neutrino detectors, data from the next galactic supernova is expected to probe decay modes of the type ν i → ν j φ with rates τ ν 10 7 s eV −1 [118][119][120]. Similarly, neutrino decays can be searched for with neutrino telescopes [121][122][123]. A very recent analysis of IceCube data [124] shows that τ ν 1, 2 > (1 − 3) × 10 −3 s eV −1 at 90% CL for IO.…”

Section: B Complementary Bounds On Invisible Neutrino Decay Ratesmentioning

confidence: 99%

“…For NO no bound has been reported yet, but similar lifetimes are expected to be probed in the years to come [124]. Furthermore, neutrino telescopes are expected to reach sensitivities to neutrino decays up to τ ν /m ν 10 3 s eV −1 from astrophysical sources [121][122][123][124].…”

Section: B Complementary Bounds On Invisible Neutrino Decay Ratesmentioning

confidence: 99%

Relaxing cosmological neutrino mass bounds with unstable neutrinos

Escudero

López‐Pavón

Rius

et al. 2020

At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (ΛCDM), the Planck collaboration reports ∑mv< 0.12 eV at 95 % CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe τν ≲ tU, represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state ν4 and a Goldstone boson ϕ, in which νi→ ν4ϕ decays can loosen the neutrino mass bounds up to ∑mv ∼ 1 eV, without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a U(1)μ−τ flavor symmetry, which are otherwise in tension with the current bound on ∑mv.

“…More precisely, only a small fraction of the area of the flavor ternary triangle is accessible by variation within the standard model (i.e., by assuming total or partial muon energy loss at the source or by invoking a significant contribution from the neutron decay at the source) [2]. Even by turning on new physics such as the neutrino decay [3,4], quantum decoherence, pseudo-Dirac neutrino, the accessible region in the ternary triangle remains small [2]. In particular, the flux at Earth will still include a significant ν τ component.…”

Section: Introductionmentioning

confidence: 99%

On the τ flavor of the cosmic neutrino flux

Farzan

2021

Observation of high energy cosmic neutrinos by ICECUBE has ushered in a new era in exploring both cosmos and new physics beyond the Standard Model (SM). In the standard picture, although mostly νμ and νe are produced in the source, oscillation will produce ντen route. Certain beyond SM scenarios, like interaction with ultralight DM can alter this picture. Thus, the flavor composition of the cosmic neutrino flux can open up the possibility of exploring certain beyond the SM scenarios that are inaccessible otherwise. We show that the τ flavor holds a special place among the neutrino flavors in elucidating new physics. Interpreting the two anomalous events observed by ANITA as ντ events makes the tau flavor even more intriguing. We study how the detection of the two tau events by ICECUBE constrains the interaction of the neutrinos with ultralight dark matter and discuss the implications of this interaction for even higher energy cosmic neutrinos detectable by future radio telescopes such as ARA, ARIANNA and GRAND. We also revisit the 3 + 1 neutrino scheme as a solution to the two anomalous ANITA events and clarify a misconception that exists in the literature about the evolution of high energy neutrinos in matter within the 3 + 1 scheme with a possibility of scattering off nuclei. We show that the existing bounds on the flux of ντ with energy of EeV rules out this solution for the ANITA events. We show that the 3 + 1 solution can be saved from both this bound and from the bound on the extra relativistic degrees of freedom in the early universe by turning on the interaction of neutrinos with ultralight dark matter.