Truncated Conformal Space Approach for 2D Landau-Ginzburg Theories

We study the spectrum of Landau-Ginzburg theories in 1 + 1 dimensions using the truncated conformal space approach employing a compactified boson. We study these theories both in their broken and unbroken phases. We first demonstrate that we can reproduce the expected spectrum of a Phi(2) theory (i.e. a free massive boson) in this framework. We then turn to Phi(4) in its unbroken phase and compare our numerical results with the predictions of two-loop perturbation theory, finding excellent agreement. We then analyze the broken phase of Phi(4) where kink excitations together with their bound states are present. We confirm the semiclassical predictions for this model on the number of stable kink-antikink bound states. We also test the semiclassics in the double well phase of Phi(6) Landau-Ginzburg theory, again finding agreement.