# Are there any $f(R, T)$ models of gravity?

For the past few months I have been studying $f(R)$ models of gravity. Recently I came cross $f(R, T)$ modified models of gravity. For the past few days I have tried to work out the difference between the two models. The problem is that while there are several models of $f(R)$ gravity, I couldn't find any models of $f(R,T)$ gravity. My question Are there any $f(R, T)$ models of gravity?

• By T, do you mean the stress energy tensor? – Slereah Jul 2 '15 at 10:11
• The stress energy tensor itself derives from the Lagrangian, so it is a bit weird that it would be in the Lagrangian itself. – Slereah Jul 2 '15 at 11:56
• $T$ in $f(T)$ is torsion – innisfree Jul 2 '15 at 13:11
• @innisfree, I know that there $f(T)$ models and $f(R)$ models, but are there any models of $f(R, T)$ gravity. – MrDi Jul 2 '15 at 13:44
• For more on torsion, see e.g. also this Phys.SE post. – Qmechanic Jul 11 '15 at 18:34