2 hours ago, by
Charlie If we're looking at $\phi^4$ loop corrections, and we get an integral (which we've Wick rotated) that looks like: $$\int \tilde d^4k_E \frac{1}{k_E+m^2}$$ for which we then impose a cutoff at $\Lambda$ and note that at large $k_E$, $k^2_E+m^2\sim k^2$. Apparently the integral becomes $$\int^\Lambda \frac{|k_E|^3 d|k_E|}{|k_E|^2},$$ but how come the measure changes here?