2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/132932We investigate the functional form of the order-parameter (two-point) correlation function in quantum critical phenomena. Contrary to the common lore, when there is no particle-hole symmetry we find that the equal-time correlation function at criticality does not display a diverging correlation length. We illustrate our conclusions by Monte Carlo calculations of the quantum rotor model in $d=2$ space dimensions4 pages, 4 figuresStatistical MechanicsStrongly Correlated Electronstext