Finite-size scaling for the spin-Heisenberg antiferromagnetic chain

Corrections to the asymptotic correlation function in a Heisenberg spin- antiferromagnetic spin chain are known to vanish slowly (logarithmically) as a function of the distance r or the chain size L . This leads to significant differences with numerical results. We calculate the sub-leading logarithmic corrections to the finite-size correlation function, using renormalization group improved perturbation theory, and compare the result with numerical data.