Quadrupole interaction of relativistic quantum particle with external fields

TL;DR

This paper investigates the quadrupole interactions of a relativistic spinning particle in external electromagnetic and gravitational fields, deriving explicit expressions and analyzing how the quadrupole moment affects energy dependence.

Contribution

It provides a first-order analysis of a relativistic particle's motion with arbitrary spin in external fields, including explicit second-order spin interaction expressions and quadrupole moment conditions.

Findings

Derived explicit expression for second-order spin interaction.

Identified quadrupole moment value reducing interaction with increasing energy.

Analyzed motion of relativistic particles with arbitrary spin in external fields.

Abstract

We consider the motion of a spinning relativistic particle with an arbitrary value of spin in external electromagnetic and gravitational fields, to first order in the external field. We use the noncovariant description of spin. An explicit expression is obtained for the interaction of second order in spin. The value of the quadrupole moment is found for which this interaction decreases when the energy grows.