Ising model description of the SU(2)1 quantum critical point in a dimerized two-leg spin-1/2 ladder Original Research Article

A nonperturbative analytical description of the SU(2)1 quantum critical point in an explicitly dimerized two-leg spin-1/2 Heisenberg ladder is presented. It is shown that this criticality essentially coincides with that emerging in a weakly dimerized spin-1 chain with a small Haldane gap. The approach is based on the mapping onto an SO(3)-symmetric model of three strongly coupled quantum Ising chains. This mapping is used to establish the correspondence between all physical fields of the spin ladder and those characterizing the SU(2)1 criticality at the infrared fixed point.