2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/29113We have discovered a new example of quantum spin liquid which is a superconducting (SC) phase in 2D electron system close to electronic topological transition. As a quantum spin liquid in low dimensional localized spin systems it is characterized by a resonance spin mode and a well separated two-particle continuum. Application of the theory to the high-T_c cuprates allows to shed light on many observed in the underdoped regime features such as the so called 40 meV resonance peak, incommensurability at lower ω, spin gap etc.4 pages, RevTeX, 6 PS figures includedSuperconductivitytext