Excited state TBA and renormalized TCSA in the scaling Potts model

Understand

We consider the field theory describing the scaling limit of the Potts quantum spin chain using a combination of two approaches.

• The first is the renormalized truncated conformal space approach (TCSA), while the second one is a new thermodynamic Bethe Ansatz (TBA) system for the excited state spectrum in finite volume.
• For the TCSA we investigate and clarify several aspects of the renormalization procedure and counter term construction.
• The TBA system is first verified by comparing its ultraviolet limit to conformal field theory and the infrared limit to exact S-matrix predictions.