Wave Packets Losing Their Covariance

TL;DR

This paper demonstrates that in relativistic quantum systems, wave packets initially covariant can lose their covariance after evolution and measurement, challenging assumptions in neutrino physics.

Contribution

It provides a simple example showing how wave packets can become non-covariant through relativistic interactions and measurements, highlighting a potential flaw in standard assumptions.

Findings

Wave packets can lose covariance after evolution and measurement.

Initial covariant conditions do not guarantee covariant outcomes.

Implications for neutrino physics and relativistic quantum theory.

Abstract

In neutrino physics, it is sometimes assumed that all wave packets must transform covariantly as Lorentz vectors. We show in a simple example that even if the initial conditions of a wave packet are covariant, then evolution in a relativistic interacting theory followed by a measurement of entangled particles can lead to a wave packet which is no longer covariant.