Are There Closed Timelike Curves in $f(R,\mathcal{L}_m,\Phi,g^{\mu\nu}\nabla_\mu \Phi \nabla_\nu \Phi)$-Gravity?

Faizuddin Ahmed; A. F. Santos

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arXiv · 2605.21040

Are There Closed Timelike Curves in $f(R,\mathcal{L}_m,\Phi,g^{\mu\nu}\nabla_\mu \Phi \nabla_\nu \Phi)$-Gravity?

Faizuddin Ahmed·A. F. Santos

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Abstract

A modified gravitational model whose action is given by an arbitrary function of the Ricci scalar, the matter Lagrangian density, a scalar field, and its kinetic term is investigated as an extension of the gravitational sector including an additional dynamical degree of freedom. Within this framework, the causal structure of rotating cosmological solutions is analyzed by considering a cylindrically symmetric Pertov-type N space-times and an axially symmetric Petrov type-III with a cosmological constant as background geometries used as theoretical probes of the model consistency. In both cases, pure radiation as matter sources are examined, including a scalar-field configurations. We demonstrate that, although the considered space-times are exact solutions to the field equations of general relativity with a matter source, they are inconsistent within the modified gravity theory considered here.

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Faizuddin Ahmed, A. F. Santos. 2026-05-20. Are There Closed Timelike Curves in $f(R,\mathcal{L}_m,\Phi,g^{\mu\nu}\nabla_\mu \Phi \nabla_\nu \Phi)$-Gravity?. https://arxiv.org/abs/2605.21040

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