Rigid particle revisited: Extrinsic curvature yields the Dirac equation

• New way of canonical quantization of relativistic rigid particle is proposed.
• Quantization made in terms of so(3.2)so(3.2) angular momentum algebra.
• Quantization yields massive Dirac equation.

We reexamine the model of relativistic particle with higher-derivative linear term on the first extrinsic curvature (rigidity). The passage from classical to quantum theory requires a number of rather unexpected steps which we report here. We found that, contrary to common opinion, quantization of the model in terms of so(3.2)so(3.2)-algebra yields massive Dirac equation.