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.
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We would like to thank Dr. C. Ahn for fruitful discussions and also to acknowledge the support in part by the Non Directed Research Fund, Korea Research Foundation (1993) and by the Korean Science and Engineering Foundation.