Aspects of gravitational decoherence in neutrino lensing

TL;DR

This paper investigates how gravitational effects influence neutrino flavor oscillations and decoherence in curved spacetime, especially in lensing scenarios, revealing dependencies on neutrino properties and potential for probing fundamental parameters.

Contribution

It introduces a framework for understanding neutrino decoherence in curved spacetime, emphasizing the role of proper time and classical trajectories in gravitational lensing contexts.

Findings

Decoherence length depends on proper time along geodesics.

Neutrino wave packets decohere more in strong gravitational fields.

Lensing effects can reveal neutrino mixing parameters.

Abstract

We study decoherence effects in neutrino flavour oscillations in curved spacetime with particular emphasis on the lensing in a Schwarzschild geometry. Assuming Gaussian wave packets for neutrinos, we argue that the decoherence length derived from the exponential suppression of the flavour transition amplitude depends on the proper time of the geodesic connecting the events of the production and detection in general gravitational setting. In the weak gravity limit, the proper time between two events of given proper distance is smaller than that in the flat spacetime. Therefore, in presence of a Schwarzschild object, the neutrino wave packets have to travel relatively more physical distance in space to lapse the same amount of proper time before they decoher. For non-radial propagation applicable to the lensing phenomena, we show that the decoherence, in general, is sensitive to the absolute values of neutrino masses as well as the classical trajectories taken by neutrinos between the source and detector along with the spatial widths of neutrino wave packets. At distances beyond the decoherence length, the probability of neutrino flavour transition due to lensing attains a value which depends only on the leptonic mixing parameters. Hence, the observability of neutrino lensing significantly depends on these parameters and in-turn the lensing can provide useful information about them.