Thermal Bethe-ansatz study of the correlation length of the one-dimensionalS=1/2 Heisenberg antiferromagnet

We investigate the correlation length of the one-dimensional S=1/2 Heisenberg antiferromagnet by the thermal Bethe-ansatz method proposed by Koma. The numerical result shows that the correlation length diverges as ξ∼${\mathit{T}}^{\mathrm{-}1}$ at low temperatures with logarithmic corrections. This logarithmic correction can be explained by conformal field theory.