The Critical Properties of a Modulated Quantum Sine-Gordon Model

Abstract

A new procedure of trial variational wave functional is proposed for investigating the mass renormailzation and the local structure of the ground state of a one-dimensional quantum sine-Gordon model with linear spatial modulation, whose ground state differs from that without modulation. The phase diagram obtained in parameters $(αΛ^{-2},β^{2})$ plane shows that the vertical part of the boundary between soliton lattice phase and incommensurate (IC) phase with vanishing gap sticks at $β^{2}$ $=4π$, the IC phase can only appear for $β^{2}$ $\geq 4π$ and the IC phase regime is enlarged with increasing spatial modulation in the case of definite parameter $αΛ^{-2}$. The transition is of the continuous type on the vertical part of the boundary, while it is of the first order on the boundary for $β^{2}>4π$.

12 pages in tex, 7 PS figures