A Bilocal Model for the Relativistic Spinning Particle

TL;DR

This paper introduces a bilocal model for relativistic spinning particles, describing them as two entangled constituents separated by a fixed distance, providing new insights into relativistic interactions and the nature of spin.

Contribution

It presents a novel bilocal classical and quantum model for spinning particles, resolving issues in relativistic interaction descriptions and explaining the prevalence of low-spin massive objects.

Findings

Model describes particles as entangled constituents with fixed separation

Interaction vertices are local at each constituent, resolving long-standing issues

Relativistic constraints lead to a phase space description with integer spin

Abstract

In this work we show that a relativistic spinning particle can be described at the classical and the quantum level as being composed of two physical constituents which are entangled and separated by a fixed distance. This bilocal model for spinning particles allows for a natural description of particle interactions as a local interaction at each of the constituents. This form of the interaction vertex provides a resolution to a long standing issue on the nature of relativistic interactions for spinning objects in the context of the worldline formalism. It also potentially brings a dynamical explanation for why massive fundamental objects are naturally of lowest spin. We analyze first a non-relativistic system where spin is modeled as an entangled state of two particles with the entanglement encoded into a set of constraints. It is shown that these constraints can be made relativistic and that the resulting description is isomorphic to the usual description of the phase space of massive relativistic particles with the restriction that the quantum spin has to be an integer.