arXiv subjects

Sergio Rodríguez-González

Publications and source records attributed to Sergio Rodríguez-González.

3 recordsLinked to original sources

arXiv2026

Global variables and dynamics of emergent cosmology in loop gravity

Deriving emergent cosmology from the discrete geometry of Loop Quantum Gravity remains an open challenge. We solve the two-vertex model exactly, including general non-symmetric configurations, by introducing macroscopic global variables that form a closed Poisson subalgebra. This yields an intrinsic minimal area gap from the Casimir invariants of the subalgebra. In the semiclassical limit, a generalized Friedmann equation emerges incorporating graph anisotropies and quantum geometry corrections, which lead to a Big Bounce. This global formulation opens a coarse-graining route toward statistical descriptions of quantum spacetime.

gr-qc↗

arXiv2026

Area bounds and gauge fixing: alternative canonical variables for loop gravity

We use a canonical parametrization of twisted geometries describing the classical phase space of loop quantum gravity on a fixed graph, and establish its explicit correspondence with the associated frame bases and spinorial descriptions. Applied to the two-vertex model, this framework yields analytical bounds on the evolution of the total area, proving the existence of a non-vanishing lower bound at finite times. These findings, previously observed only numerically, suggest a bounce-like behavior and highlight the usefulness of these variables for the study of more general configurations. As a second result, the canonical variables are shown to simplify the gauge-fixing procedure, generalizing previous results restricted to two-vertex models with four links.

gr-qc↗

arXiv2025

Homothetic expansion of polyhedra in the two-vertex model: emergence of FLRW

The cosmological behavior associated to a U(N)-symmetry reduced sector of the loop-quantum-gravity truncation known as the two-vertex model is further explored in this work. We construct convenient frame bases that encode the whole classical phase space of the twisted geometry associated to the graph. We show that the polyhedra of the twisted geometry suffer under evolution an homothetic expansion, which strengthens the correspondence to the Robertson-Walker geometry.

gr-qc↗