Thermal effect on mixed state geometric phases for neutrino propagation in a magnetic field

TL;DR

This paper investigates how thermal effects influence the mixed state geometric phases of neutrinos propagating in magnetic fields, with implications for astrophysical neutrino spin conversions.

Contribution

It formulates the mixed state geometric phases of neutrinos in thermal environments, extending previous pure state analyses to include temperature-dependent effects.

Findings

Thermal effects significantly alter the geometric phases of neutrinos.

Off-diagonal and diagonal geometric phases are characterized in thermal states.

Temperature influences the resonance conditions for neutrino spin conversion.

Abstract

In astrophysical environments, neutrinos may propagate over a long distance in a magnetic field. In the presence of a rotating magentic field, the neutrino spin can flip from left-handed neutrino to right-handed neutrino. Smirnov demonstrated that the pure state geometric phase due to the neutrino spin precession may cause resonantg spin conversion inside the Sun. However, in general, the neutrinos may in an ensemble of thermal state. In this article, the corresponding mixed state geometric phases will be formulated, including the off-diagonal casse and diagonal ones. The spefic features towards temperature will be analysized.