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

• Main Authors: De, Avik, Loo, Tee How, Saridakis, Emmanuel N.
• Format: Article
• Published: IOP Publishing 2024
• Subjects: QA Mathematics
• Online Access: http://eprints.um.edu.my/45498/; https://doi.org/10.1088/1475-7516/2024/03/050
• Institution: Universiti Malaya

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 from the standard Levi-Civita Ricci scalar 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.