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Axion coupling accelerates the Universe through PT-symmetric phases

Leqian Chen1, Nick E. Mavromatos2,1,*, and Sarben Sarkar1

  • *On leave from: Physics Division, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Zografou Campus, Athens 157 80, Greece.
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Phys. Rev. D 113, 064049 – Published 24 March, 2026

DOI: https://doi.org/10.1103/11dp-b5cj

Abstract

The conjecture by two of the authors (N. E. M. and S. S.) that a PT-symmetric phase plays a role in understanding singular renormalization group (RG) flows for a Chern-Simons (CS) gauge theory of axions, has been reexamined and significantly improved. We have used the more complete Wetterich equation, which includes gravitational couplings in a systematic way from the start, to understand the emergence of this phase. The singular structure of the RG flows has persisted on including gravitational couplings, thereby offering further support to the conjecture that PT -symmetric phases of (repulsive) gravity characterize string-effective CS gravitational theories, where the axion is the massless string-model independent axion, which can also play a role of a totally antisymmetric torsion degree of freedom. This has suggested a novel interpretation of the currently observed acceleration of the expansion of the Universe in terms of such a phase at large (cosmological) scales.

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Physics Subject Headings (PhySH)

See Also

Chern-Simons gravity and PT symmetry

N. E. Mavromatos and Sarben Sarkar
Phys. Rev. D 110, 045004 (2024)

Article Text

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Phys. Rev. D 113, 064049– Published 24 March, 2026
  • Received 5 January 2026
  • Accepted 2 March 2026
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