Key points are not available for this paper at this time.
Einstein's celebrated theory of gravitation can be presented in three forms: general relativity, teleparallel gravity, and the rarely considered before symmetric teleparallel gravity. Extending the latter, we introduce a new class of theories where a scalar field is coupled nonminimally to nonmetricity Q, which here encodes the gravitational effects like curvature R in general relativity or torsion T in teleparallel gravity. We point out the similarities and differences with analogous scalar-curvature and scalar-torsion theories by discussing the field equations, role of connection, conformal transformations, relation to f (Q) theory, and cosmology. The equations for a spatially flat universe coincide with those of teleparallel dark energy, thus allowing us to explain accelerating expansion.
Järv et al. (Mon,) studied this question.