Quantum-Deformed Phase-Space Geometry and Emergent Inflation in Effective Four-Dimensional Spacetime

Abstract

We develop a phase-space approach to quantum-deformed gravity. Reducing it to an effective four-dimensional spacetime structure facilitates reanalyzing cosmic inflation and quantum gravity dynamics. Initiated on a cotangent bundle, the gravitational Hamiltonian is then deformed by a zero-homogeneous scalar determined by projective momentum directions and quantum phase-space properties, forming an anisotropic Hamilton geometry on a non-null conic domain. Through section-pullback procedures, an effective spacetime metric is derived, which in the homogeneous and isotropic sector reduces to a conformally deformed FLRW geometry governed by a scalar deformation field. The corresponding modified Einstein, Klein-Gordon, geodesic-deviation, and Raychaudhuri equations are derived and then utilized to construct inflationary background dynamics, slow-roll regimes, e-folds, and perturbation spectra. The framework shows that leading inflationary corrections stem from phase-space deformation and its time dependence, whereas canonical quantization of cosmological perturbations remains standard following background redefinitions. Ultimately, this model establishes a covariant link between quantum-deformed phase-space geometry and effective four-dimensional inflationary dynamics, demonstrating that quantum gravity effects can be encoded as projective phase-space deformations while preserving the classical limit and standard perturbative structure.