1–5 Sept 2026
University of Sussex
Europe/London timezone

The axion coupling accelerates the Universe through \cPT-symmetric phases

2 Sept 2026, 15:00
20m
Large Lecture Theatre (Jubilee Building)

Large Lecture Theatre

Jubilee Building

Speaker

Prof. Sarben Sarkar (King's College London)

Description

The conjecture by two of the authors (N.E.M. and S.S.) that a \cPT-symmetric phase plays a role in understanding singular renormalisation 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 \cPT -symmetric phases of (repulsive) gravity characterise 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.

Affiliation King's College London
Link to paper DOI: https://doi.org/10.1103/11dp-b5cj
Career status Senior

Author

Co-author

Prof. Sarben Sarkar (King's College London)

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