SetDimensions is an option for
ScalarProduct, CartesianScalarProduct and
various FCLoopBasis* functions.
For scalar products it specifies the dimensions for which the scalar
products will be set when ScalarProduct or
CartesianScalarProduct are used with the equality sign,
e.g. in ScalarProduct[a, b] = m^2. By default, the scalar
products are set for 4 and D dimensions. By changing this option the
user can add other dimensions or remove the existing ones.
In case of the FCLoopBasis* functions this option
specifies the dimensions of the loop and external momenta to be taken
into account when extracting the propagator basis.
Overview, ScalarProduct, CartesianScalarProduct.