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arXiv · 2308.00652

Non-metricity with bounday terms: $f(Q,C)$ gravity and cosmology

Avik De·Tee-How Loo·Emmanuel N. Saridakis
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Abstract

We formulate $f(Q,C)$ gravity and cosmology. Such a construction is based on the symmetric teleparallel geometry, but apart form the non-metricity scalar $Q$ we incorporate in the Lagrangian the boundary term $C$ of its difference form the standard Levi-Civita Ricci scalar $\mathring R$. We extract the general metric and affine connection field equations, we apply them at a cosmological framework, and adopting three different types of symmetric teleparallel affine connections we obtain the modified Friedmann equations. As we show, we acquire an effective dark-energy sector of geometrical origin, which can lead to interesting cosmological phenomenology. Additionally, we may obtain an effective interaction between matter and dark energy. Finally, examining a specific model, we show that we can obtain the usual thermal history of the universe, with the sequence of matter and dark-energy epochs, while the effective dark-energy equation-of-state parameter can be quintessence-like, phantom-like, or cross the phantom-divide during evolution.

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Avik De, Tee-How Loo, Emmanuel N. Saridakis. 2023-08-01. Non-metricity with bounday terms: $f(Q,C)$ gravity and cosmology. https://doi.org/10.1088/1475-7516/2024/03/050

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