Strongest atomic physics bounds on Non-Commutative Quantum Gravity Models

Investigations of possible violations of the Pauli Exclusion Principle represent critical tests of the microscopic space-time structure and properties. Space-time non-commutativity provides a class of universality for several Quantum Gravity models. In this context the VIP-2 Lead experiment sets the strongest bounds, searching for Pauli Exclusion Principle violating atomic-transitions in lead, excluding the $\theta$-Poincaré Non Commutative Quantum Gravity models far above the Planck scale for non-vanishing ${\theta }_{\mu \nu }$ ``electric-like’’ components, and up to $6.9\cdot {10}^{-2}$ Planck scales if ${\theta }_{0i}=0$.