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. ItsLagrangian density is

${\displaystyle {\mathcal {L}}={\frac {1}{2}}(\partial _{\mu }\varphi )^{2}-{\frac {m_{0}^{2}}{6g^{2}}}(2e^{g\varphi }+e^{-2g\varphi })}$

where ${\displaystyle m_{0}\,}$ is a mass parameter, ${\displaystyle g\,}$ is the coupling constant and ${\displaystyle \varphi \,}$ 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.