I want to expand Einstein-Hilbert action for the metric
gμν=ημν+hμν
up to quadratic order in hμν. For this purpose I need to calculate the Ricci tensor at some stage. There is no problem in linear terms of the metric perturbation but there happens to be a problem when I intend to calculate the quadratic terms using
R(2)μν=∂αΓα(2)μν−∂νΓα(2)μα+Γα(1)βαΓβ(1)μν−Γα(1)βνΓβ(1)μα
When I use
Γα(1)μν=12(∂μhαν+∂νhαμ−∂αhμν)
Γα(2)μν=−12hαβ(∂μhβν+∂νhμβ−∂βhμν)
in the above expression for R(2)μν I suppose to find
R(2)μν=12[12∂μhαβ∂νhαβ+∂βhνα(∂βhαμ−∂αhβμ)+hαβ(∂μ∂νhαβ+∂α∂βhμν−∂β∂νhαμ−∂β∂μhαν)−(∂αhαβ−12∂βh)(∂μhνβ+∂νhμβ−∂βhμν)]
but I do not. I tried it over and over again but somehow I cannot get the correct result. It seems I am missing something but I don't know what. I will be glad if someone can help.
This post imported from StackExchange Physics at 2015-02-13 11:37 (UTC), posted by SE-user sahin