The implications of noninertial motion on covariant quantum spin

TL;DR

This paper investigates how noninertial motion affects the Lorentz invariance of the covariant quantum spin vector, proposing a new invariant spin vector and exploring potential experimental detection in muon decay.

Contribution

It introduces a Lorentz-invariant spacelike spin vector applicable to noninertial motion and generalizes the classification of spin-1/2 particles.

Findings

The Pauli-Lubanski spin vector violates Lorentz invariance in noninertial frames.

A new Lorentz-invariant spin vector is derived for noninertial motion.

Potential experimental detection of invariance violation in muon decay experiments.

Abstract

It is shown that the Pauli-Lubanski spin vector defined in terms of curvilinear co-ordinates does not satisfy Lorentz invariance for spin-1/2 particles in noninertial motion along a curved trajectory. The possibility of detecting this violation in muon decay experiments is explored, where the noninertial contribution to the decay rate becomes large for muon beams with large momenta and trajectories with radius of curvature approaching the muon's Compton wavelength scale. A new spacelike spin vector is derived from the Pauli-Lubanski vector that satisfies Lorentz invariance for both inertial and noninertial motion. In addition, this spin vector suggests a generalization for the classification of spin-1/2 particles, and has interesting properties that are applicable for both massive and massless particles.