I'm reading this paper by Dong where he proposed a general formula to obtain entanglement entropy (EE) for a given gravitational action. The EE can be obtain by:
SEE=2π∫ddy√g{∂L∂Rzˉzzˉz+∑α(∂2L∂Rzizj∂Rˉzkˉzl)α8KzijKˉzklqα+1}
Now suppose we have the following Lagrangian:
L=λ1R2+λ2RμνRμν+λ3RμρνσRμρνσ
then we get,
SEE=−4π∫ddy√g[2λ1R+λ2(Ra a−12KaKa)+2λ3(Rab ab−KaijKaij)]
where the terms with extrinsic curvature are coming from the second order differential in first equation. He calls this terms the Anomaly term. I wonder if anyone can explain or show me explicitly how to obtain the extrinsic curvature terms just like above. I did the differentiation but when I do the contractions all appropriately I don't get the nice form above.