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arXiv · 2506.01543

Dynamical dark energy in the no-scale Brans-Dicke gravity

Muzi Hong·Kyohei Mukaida·Tsutomu T. Yanagida
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Abstract

We add a new scalar field in the no-scale Brans-Dicke gravity and require it to have a global O(2) symmetry with the original scalar field in the Brans-Dicke gravity. This gives us a new massless scalar field in the Einstein frame due to the SO(2) symmetry. We then explicitly break the O(2) symmetry to a $D_4$ symmetry, and this scalar field gains a periodic potential. This scalar field can serve as the quintessence field to explain dark energy. If we further add the $R^2$ term and the non-minimal coupling to the Higgs field, we can realize inflation and reheating, and this leads to a super-Planckian decay constant of the quintessence potential. The super-Planckian decay constant is consistent with the newly released observational data according to a recent analysis.

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Muzi Hong, Kyohei Mukaida, Tsutomu T. Yanagida. 2025-06-02. Dynamical dark energy in the no-scale Brans-Dicke gravity. https://doi.org/10.1016/j.physletb.2025.139932

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