FM 2000-12  mp_arc 00-184

Authors: Giuseppe Benfatto, Vieri Mastropietro

Title: Renormalization Group, hidden symmetries and approximate Ward
identities in the XYZ model, II.

Abstract:
An expansion based on renormalization group methods for the spin
correlation function in the z direction of the Heisenberg-Ising XYZ
chain with an external magnetic field directed as the z axis is
derived. Moreover, by using the hidden symmetries of the model, we
show that the running coupling constants are small, if the coupling in
the z direction is small enough, that a critical index appearing in
the correlation function is exactly vanishing (because of an
approximate Ward identity) and other properties, so obtaining a rather
detailed description of the XYZ correlation function.

Key Words: Quantum Statistical Mechanics, Renormalization Group, Fermi
systems.