⁵A redefinition of the form $\Lambda \to c\Lambda$ by a real constant $c$ corresponds to a redefinition of the coupling of the form $1∕g^2\to 1∕g^2-c^{\prime }$ where $c^{\prime }$ is another constant, or equivalently $g^2\to g^2+c^{\prime }{g}^4+\cdots$. Therefore this is a redefinition starting at the one-loop order, keeping the leading order definition of $g^2$ fixed. In this lecture note, we do not track such finite renormalization of the coupling very carefully.