Spatial rotation
= Spatial rotation
A spatial rotation acts by $\mathbf x\mapsto R\mathbf x$ with $R$ orthogonal. A rotationally invariant scalar two-point function depends only on the magnitude of its momentum.
= Spatial rotation
A spatial rotation acts by $\mathbf x\mapsto R\mathbf x$ with $R$ orthogonal. A rotationally invariant scalar two-point function depends only on the magnitude of its momentum.