Generalized L\"uscher Formula in Multi-channel Baryon-Meson Scattering

TL;DR

This paper extends L"uscher's formula to multi-channel baryon-meson scattering involving spin 1/2 particles, providing a generalized relation between finite-volume energy levels and scattering matrices in quantum mechanics and quantum field theory.

Contribution

It introduces a generalized L"uscher formula for baryon-meson scattering with spin 1/2 particles in multiple channels, bridging quantum mechanics and quantum field theory approaches.

Findings

Derived a generalized relation between energy levels and scattering matrices.

Verified equivalence of quantum mechanics and quantum field theory methods.

Established the formula's validity up to exponentially suppressed terms.

Abstract

L\"uscher's formula relates the elastic scattering phase shifts to the two-particle energy levels in a finite cubic box. The original formula was obtained for elastic scattering of two massive spinless particles in the center of mass frame. In this paper, we consider the case for the scattering of a spin 1/2 particle with a spinless particle in multi-channel scattering. A generalized relation between the energy of two particle system and the scattering matrix elements is established. We first obtain this relation using quantum-mechanics in both center-of-mass frame and in a general moving frame. The result is then generalized to quantum field theory using methods outlined in Ref. \cite{Hansen:2012tf}. We verify that the results obtained using both methods are equivalent up to terms that are exponentially suppressed in the box size.