Gauge invariance in quantum hadrodynamics

This paper describes the derivation of a new representation of an SU(2)LxSU(2)R locally invariant model of the strong interactions called quantum hadrodynamics 3 (QHD-III). QHD-III is a gauge-invariant theory based on the linear σ model, the gauge bosons being the ρ and the a1. The new representation considerably simplifies the Lagrangian. To derive the new representation, the gauge invariance of the model is exploited. The role of the gauge boson masses in gauge-invariant models of the strong interactions based on the σ model is also discussed, and it is shown that these masses are necessary if the pion is to survive as a physical field. copyright 1999 The American Physical Society