Conformal Killing factor ($\lambda ={\nabla }_{\mu }{X}^{\mu }/n$)

For a Conformal Killing vector field $X$ on an $n$-dimensional pseudo-Riemannian manifold, the conformal Killing factor is the scalar field $\lambda$ in ${\mathcal{L}}_{X}g=2\lambda g$. For the Levi-Civita connection, taking the tensor contraction of the Conformal Killing equation gives $\lambda ={\nabla }_{\mu }{X}^{\mu }/n$. A Killing vector field has $\lambda =0$, while the dilation generator $x^{\mu }{\partial }_{\mu }$ on Minkowski spacetime has $\lambda =1$.