Question

Where is a proof that string field theory is generally covariant?

Answer 1

Given a space-time coordinate of a string Xμ(σ) dependent on the position σ around the string. And a string field functional Φ[X], is there a proof that the equations of motion (or the action) are generally covariant. ie. invariant under a transform Xμ(σ)→Yμ(X(σ)) ?  All I have seen are talks about Xμ(σ) being diffeomorphically invariant under a change of string coordinates Xμ(σ)→Xμ(f(σ)). But that isn't the same thing. Pls mark it the brainliest