Quantum Cosmology in $f(R, T)$ Theory with Schutz's Perfect Fluid

TL;DR

This paper explores quantum cosmology within the $f(R, T)$ gravity framework, using Schutz's perfect fluid to define a matter-based time parameter, and derives the corresponding Schrödinger–Wheeler–DeWitt equation for early universe models.

Contribution

It introduces a quantum cosmological analysis of $f(R, T)$ gravity with a matter-derived time parameter, extending previous $f(R)$ studies and emphasizing matter-geometry coupling effects.

Findings

Derived the SWDW equation for specific $f(R, T)$ forms.

Obtained the universe's wave function considering matter-geometry coupling.

Compared quantum dynamics with previous $f(R)$ models.

Abstract

The $f(R, T)$ theory of gravity extends general relativity (GR) by allowing the gravitational Lagrangian to depend on both the Ricci scalar $R$ and the trace of the energy-momentum tensor $T$. The resulting matter-geometry coupling introduces additional dynamical effects that may account for the late-time acceleration of the universe without invoking dark energy. In the present work, we focus instead on the early-time regime and investigate the corresponding quantum cosmological dynamics. We analyze a Friedmann--Lemaitre--Robertson--Walker (FLRW) universe within the $f(R, T)$ framework, employing Schutz's perfect fluid formalism to extract a time parameter emerging from the matter sector itself. This approach is particularly well motivated in $f(R, T)$ gravity, where the coupling between geometry and the energy-momentum tensor's trace makes matter an active participant in the dynamics of spacetime and the evolution of cosmic time. The gravitational Hamiltonian, canonical momenta, and potential are derived, leading to the corresponding Schr\"odinger--Wheeler--DeWitt (SWDW) equation. The wave function of the universe is obtained for specific forms of $f(R, T)$, and the results are compared with previous studies in $f(R)$ and $f(R, T)$ models, highlighting the role of matter-geometry coupling in the emergence of quantum cosmological dynamics.