Open system approach to neutrinos propagating in an ultralight scalar background

TL;DR

This paper investigates how an ultralight scalar field causes decoherence in neutrino oscillations by inducing variable mass shifts, and establishes a theoretical framework linking detailed models to phenomenological descriptions.

Contribution

It introduces an open quantum systems framework to model neutrino decoherence from ultralight scalar fields and derives a new scaling law for the decoherence parameter.

Findings

Decoherence scales as L^2/E^2, differing from traditional L/E assumptions.

Recasting neutrino-scalar interactions within open quantum systems provides new insights.

Mapping between detailed models and phenomenological approaches is established.

Abstract

We examine decoherence in neutrino oscillations induced by an ultralight scalar field coupled to neutrinos. The scalar induces time- and position-dependent shifts in the neutrino mass matrix. Neutrinos sample different field configurations throughout an experimental data-taking period, which leads to damping effects in the oscillation pattern in the form of decoherence. By recasting the neutrino-scalar dynamics within the open quantum systems framework, we establish a mapping between a complete model and phenomenological decoherence approaches. We find that the parameter driving decoherence scales as $L^2/E^2$, where $L$ is the baseline and $E$ is the neutrino energy, as opposed to $L/E$ typically assumed in phenomenological studies of open system approaches to neutrino oscillations.