QUANTUM CRITICAL SCALING AND TEMPERATURE-DEPENDENT LOGARITHMIC CORRECTIONS IN THE SPIN-HALF HEISENBERG CHAIN

Low temperature dynamics of the S = 1/2 Heisenbeig chain is studied vi a a simple ansatz generalizing the conformal mapping and analytic cont inuation procedures to correlation functions with multiplicative logar ithmic factors. Closed form expressions for the dynamic susceptibility and the NMR relaxation rates 1/T-1 and 1/T2(G) are obtained, and are argued to improve the agreement with recent experiments. Scaling in q/ T and omega/T are violated due-to these logarithmic terms. Numerical r esults show that the logarithmic corrections are very robust. While no t yet in the asymptotic low temperature regime, they provide striking qualitative confirmation of the theoretical results.