EpsContract[exp]
handles contractions of two Levi-Civita tensors. It is also an option of Contract
and other functions that specifies whether such contractions should be done or not.
[\[Mu], \[Nu], \[Rho], \[Sigma]]
LCD
[% %] // Factor2 EpsContract
[LCD[\[Mu], \[Nu], \[Rho], \[Sigma]]^2] // Factor2 Contract
[LCD[\[Mu], \[Nu], \[Rho], \[Sigma]]^2, EpsContract -> False] Contract