User:Amir

Amir Khosrowshahi

<math>S = {T \over 2}\int d^2 \sigma \sqrt{-|h|} h^{ab} g_{\mu \nu} \partial_a X^\mu (\sigma) \partial_b X^\nu(\sigma)</math>

<math>R_{ab} - {1 \over 2}R g_{ab} + \Lambda g_{ab} = {8 \pi} T_{ab}</math>