Microscopic and Macroscopic Effects in the Decoherence of Neutrino Oscillations

TL;DR

This paper introduces a layered framework combining quantum and classical uncertainties to analyze decoherence in neutrino oscillations, enabling simplified numerical calculations and experimental sensitivity estimates.

Contribution

It presents a generic layer structure for neutrino decoherence, classifying effects into state and phase decoherence, and provides a method to estimate experimental sensitivities.

Findings

Decoherence effects can be classified into state and phase decoherence.

The layer structure simplifies numerical calculations of decoherence.

Experimental sensitivities are estimated for reactor and decay-at-rest neutrinos.

Abstract

We present a generic structure (the layer structure) for decoherence effects in neutrino oscillations, which includes decoherence from quantum mechanical and classical uncertainties. The calculation is done by combining the concept of open quantum system and quantum field theory, forming a structure composed of phase spaces from microscopic to macroscopic level. Having information loss at different levels, quantum mechanical uncertainties parameterize decoherence by an intrinsic mass eigenstate separation effect, while decoherence for classical uncertainties is typically dominated by a statistical averaging effect. With the help of the layer structure, we classify the former as state decoherence (SD) and the latter as phase decoherence (PD), then further conclude that both SD and PD result from phase wash-out effects of different phase structures on different layers. Such effects admit for simple numerical calculations of decoherence for a given width and shape of uncertainties. While our structure is generic, so are the uncertainties, nonetheless, a few notable ones are: the wavepacket size of the external particles, the effective interaction volume at production and detection, the energy reconstruction model and the neutrino production profile. Furthermore, we estimate the experimental sensitivities for SD and PD parameterized by the uncertainty parameters, for reactor neutrinos and decay-at-rest neutrinos, using a traditional rate measuring method and a novel phase measuring method.