Universality relations in non-solvable quantum spin chains
G. Benfatto, Vieri Mastropietro
Abstract
We prove the exact relations between the critical exponents and the susceptibility, implied by the Haldane Luttinger liquid conjecture, for a generic lattice fermionic model or a quantum spin chain with short range weak interaction. The validity of such relations was only checked in some special solvable models, but there was up to now no proof of their validity in non-solvable models. 1 Introduction and Main results One dimensional (1D) electron systems can be experimentally realized [1, 2] and their properties can be measured with increasing precision. Realistic models are very difficult to study and most of the theoretical predictions for such systems (for some recent experiments see [3]) are based on a number of