NON-ABELIAN BOSONIZATION OF THE FRUSTRATED ANTIFERROMAGNETIC SPIN-1 2CHAIN/

We study the spin-1/2 chain with nearest-neighbor (kappa(1)) and next- nearest-neighbor (kappa(2)) interactions in the regime kappa(2) much g reater than kappa(1), which is equivalent to two chains with a ''zigza g'' interaction. In the continuum limit, this system is described in t erms of two coupled level-1 Wess-Zumino-Witten field theories. We illu strate its equivalence with four off-critical Ising models (Majorana f ermions). This description is used to investigate the opening of a gap as a function of kappa(1) and the associated spontaneous breakdown of parity. We calculate the dynamic spin structure factor near the wave vectors accessible to the continuum limit. We comment on the nonzero s tring order parameter and show the presence of a hidden Z(2)xZ(2) symm etry via a nonlocal transformation on the microscopic Hamiltonian. For a ferromagnetic interchain coupling, the model is conjectured to be c ritical, with different velocities for the spin-singlet and spin-tripl et excitations.