Exact critical theory of the two-impurity Kondo model

The two-impurity Kondo Hamiltonian is known to possess a multicritical point separating stable Fermi-liquid phases in which the two impurities either form a singlet or else are screened by the conduction electrons. We propose an exact critical theory for this non-Fermi-liquid multicritical point, using conformal field theory methods, which predicts all critical properties including the finite-size spectrum, specific heat, susceptibilities, renormalization-group behavior, residual entropy, scattering matrix, and local pair Green’s function.