Low-temperature specific heat of the generalized antiferromagnetic SU (N) Heisenberg model with and without a field

Abstract We discuss the low-temperature specific heat of the integrable SU ( N )-invariant Heisenberg model in one dimension with degrees of freedom in the symmetric rank- m tensor representation, especially for the antiferromagnetic coupling. It is known that the linear specific heat coefficient γ [ N,m ] is a function of a field which breaks the Su ( N ) invariance of the internal degrees of freedom. We calculate the γ [ N,m ] in zero field and in a small field. The in-field γ [ N,m ] is less than the zero-field γ [ N,m ] as expected since the entropy is reduced in the ordered system. The zero-field γ [ N,m ] is the same as the one obtained by the prediction of the critical behavior of 1D quantum spin systems via conformal field theory. This extends the previous results for N = 2 to arbitrary N .