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

where  is a mass parameter,   is the coupling constant and   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. See also

List of integrable models

References

Quantum field theory
Exactly solvable models
Integrable systems