On the dilation current in metric-affine gravity

D. Kenzhalin, S. Myrzakul, R. Myrzakulov, L. Ravera

Published 2023-12-31Version 1

We review $F(R,\mathcal{D})$ gravity in the metric-affine framework, where $\mathcal{D}$ is the divergence of the dilation current appearing in the hypermomentum tensor. We assume only linear couplings between the general affine connection and the matter fields and break projective invariance to preserve a nonvanishing dilation current and observe that, in cases that are more complicated with respect to the linear one, the $\mathcal{D}$ contribution to the metric field equations is nontrivial and can affect the cosmology of the theory.