Bullough–Dodd model

The Bullough–Dodd model is an integrable model in 1+1-dimensional quantum field theory introduced by Robin Bullough and Roger Dodd. Its Lagrangian density is


 * $$\mathcal{L}=\frac{1}{2}(\partial_\mu\varphi)^2-\frac{m_0^2}{6g^2}(2e^{g\varphi}

+e^{-2g\varphi}) $$

where $$m_0\,$$ is a mass parameter, $$g\,$$ is the coupling constant and  $$\varphi\,$$ is a real scalar field.

The Bullough–Dodd model belongs to the class of affine Toda field theories.

The spectrum of the model consists of a single massive particle.