Searches for violations of the Pauli exclusion principle as a low-energy probe of quantum gravity

Abstract

The Pauli exclusion principle is one of the pillars of quantum physics. In relativistic quantum field theory it is rooted in the spin–statistics connection and therefore in locality, causal structure and Poincaré covariance. These ingredients may be modified in candidate quantum-gravity scenarios, including noncommutative spacetimes and theories with deformed relativistic symmetries. This opens a low-energy experimental route to test quantum-gravity models through high-sensitivity searches for Pauli-forbidden atomic transitions. We review the conceptual basis, experimental strategy and recent results of the VIP experiments at the INFN Gran Sasso National Laboratory. The distinction between model-independent limits on anomalous X-ray emission, phenomenological limits on the conventional violation probability [Formula: see text], and model-dependent constraints on quantum-spacetime deformation scales is addressed. We discuss the role of the Messiah–Greenberg superselection rule, the complementarity of open- and closed-system searches, and recent field-theoretic developments connecting [Formula: see text]-deformed Poincaré symmetry, quon-like exchange and particle indistinguishability. Finally, we outline how the ongoing VIP-3 measurements across the periodic table, directional configurations and sidereal-time analyses can transform Pauli-principle tests from single-parameter exclusions into a differential program of quantum-gravity phenomenology.