Expectation values of descendent fields in the Bullough–Dodd model and related perturbed conformal field theories Original Research Article

The exact vacuum expectation values of the second level descendent fields 〈(∂ϕ)2(∂̄ϕ)2eaϕ〉 in the Bullough–Dodd model are calculated. By performing quantum group restrictions, we obtain 〈L−2L̄−2Φlk〉 in the Φ12, Φ21 and Φ15 perturbed minimal CFTs. In particular, the exact expectation value 〈TT̄〉 is found to be proportional to the square of the bulk free energy.