Exact Critical Exponents of the Staircase Model

The staircase model is a recently discovered one-parameter family of integrable two-dimensional continuum field theories. We analyze the novel critical behavior of this model, seen as a perturbation of a minimal conformal theory M_p: the leading thermodynamic singularities are simultaneously governed by all fixed points M_p, M_{p-1}, ..., M_3. The exponents of the magnetic susceptibility and the specific heat are obtained exactly. Various corrections to scaling are discussed, among them a new type specific to crossover phenomena between critical fixed points.