Quasi-classical Gravity effect on neutrino oscillations in a gravitational field of an heavy astrophysical object

TL;DR

This paper explores how quantum gravity effects, specifically graviton interactions, can cause decoherence in neutrino oscillations in astrophysical gravitational fields, potentially affecting neutrino observations and offering a new detection method.

Contribution

It introduces a novel quantum gravity mechanism causing neutrino decoherence and proposes a method to detect energetic gravitons via neutrino flavor measurements.

Findings

Graviton interactions can induce significant neutrino decoherence in astrophysical environments.

Neutrino flavor composition can reveal the presence of energetic gravitons.

The proposed technique offers a new way to indirectly detect gravitons.

Abstract

In the framework of quantum field theory, a graviton interacts locally with a quantum state having definite mass, i.e. the gravitational mass eigenstate, while a weak boson interacts with a state having definite flavor, i.e. the flavor eigenstate. An interaction of a neutrino with an energetic graviton may trigger the collapse of the neutrino to a definite mass eigenstate with probability expressed in terms of PMNS mixing matrix elements. Thus, gravitons would induce quantum decoherence of a coherent neutrino flavor state similarly to how weak bosons induce quantum decoherence of a neutrino in a definite mass state. We demonstrate that such an essentially quantum gravity effect may have strong consequences for neutrino oscillation phenomena in astrophysics due to relatively large scattering cross sections of relativistic neutrinos undergoing large-angle radiation of energetic gravitons in gravitational field of a classical massive source (i.e. the quasi-classical case of gravitational Bethe-Heitler scattering). This graviton-induced {\it decoherence} is compared to {\it decoherence} due to propagation in the presence of the Earth matter effect. Based on this study, we propose a new technique for the indirect detection of energetic gravitons by measuring the flavor composition of astrophysical neutrinos.