Neutron \beta-decay as the origin of IceCube's PeV (anti)neutrinos

TL;DR

This paper proposes that PeV neutrinos detected by IceCube could originate from neutron beta-decay, requiring specific cosmic ray suppression mechanisms involving extragalactic magnetic fields.

Contribution

It introduces a novel astrophysical source model for IceCube's PeV neutrinos based on neutron beta-decay with magnetic shielding effects.

Findings

Only 1-10% of cosmic rays produce observable antineutrinos.

Magnetic shielding in extragalactic fields explains the suppression of cosmic rays.

The model accounts for IceCube's neutrino flux and muon track deficit.

Abstract

Motivated by the indications of a possible deficit of muon tracks in the first three-year equivalent dataset of IceCube we investigate the possibility that the astrophysical (anti)neutrino flux (in the PeV energy range) could originate from \beta-decay of relativistic neutrons. We show that to accommodate IceCube observations it is necessary that only about 1% to 10% of the emitted cosmic rays in the energy decade 10^{8.5} \alt E_{CR}/GeV \alt 10^{9.5}$, yielding antineutrinos on Earth (10^{5.5} \alt E_{\bar \nu}/GeV \alt 10^{6.5}), are observed. Such a strong suppression can be explained assuming magnetic shielding of the secondary protons which diffuse in extragalactic magnetic fields of strength 10 \alt B/nG \alt 100 and coherence length \alt Mpc.