New description of neutrino flavour evolution in solar matter

TL;DR

This paper develops a quantum open system formalism for neutrino flavor evolution in solar matter, extending classical models and analyzing differences in predictions, especially regarding oscillation suppression inside the Sun.

Contribution

It introduces a quasilinear extension of the von Neumann equation to model neutrino evolution, broadening the classical Wolfenstein formalism with a novel quantum approach.

Findings

Similar average neutrino survival probabilities in both models

Quasilinear approach predicts oscillation suppression inside the Sun

Discussion of energy transfer and evolution speed in neutrino-solar matter interactions

Abstract

Assuming that the interacting neutrino and the solar matter can be treated as an open quantum system we formulate a formalism of neutrino state evolution in terms of the Bloch vector, obtained by solving a quasilinear extension of the von Neumann equation. We broaden the classical Wolfenstein formalism by means of exploiting the strictly linear von Neumann equation and reinterpreting the results in terms of the quantities appropriate for the quasilinear approach. We obtain similar predictions for the averaged neutrino survival probability measured on Earth in both approaches, differing by details inside the Sun where the quasilinear evolution predicts a suppression of oscillations. We discuss the issues of energy transfer between the neutrino and the Sun and the speed of the state evolution in both approaches.