Cosmological inviability of $f(R,T)$ gravity

Understand

Among many alternative gravitational theories to General Relativity (GR), $f(R,T)$ gravity (where $R$ is the Ricci scalar and $T$ the trace of the energy-momentum tensor) has been widely studied recently.

• By adding a matter contribution to the gravitational Lagrangian, $f(R,T)$ theories have become an interesting extension to GR displaying a broad phenomenology in astrophysics and cosmology.
• In this paper, we discuss however the difficulties appearing in explaining a viable and realistic cosmology within the $f(R,T)$ class of theories.
• Our results challenge the viability of $f(R,T)$ as an alternative modification of gravity.