Like this.
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
\int \frac{d^4 \mathnormal{k}}{(2\pi)^4}\text{log}(-k^2+m^2)=& i\int
\frac{d^4 \mathnormal{k_E}}{(2\pi)^4}\text{log}(k_E^2+m^2)\notag\\
=&-i \frac{\partial}{\partial \alpha}\int \frac{d^4
\mathnormal{k_E}}{(2\pi)^4}\frac{1}
{(k_E^2+m^2)^{\alpha}}\Big\vert_{\alpha=0}\notag\\
=&-i \frac{\partial}{\partial \alpha} \Big(\frac{1}
{(4\pi)^{d/2}}\frac{\Gamma(\alpha-\frac{d}{2})}
{\Gamma(\alpha)}\frac{1}{(m^2)^{\alpha-\frac{d}{2}}} \Big) \Big
\vert_{\alpha=0}\notag\\
=& -i\frac{\Gamma(\frac{-d}{2})}{(4\pi)^{d/2}}\frac{1}{(m^2)^{-
d/2}}
\tag{11.72}
\end{align}
\end{document}

However, I would at least use \log
instead of \text{log}
and make the differential d distiguishable from the dimension d
in dimensional regularization, and same for the imaginary i
. Nor would I set the equation number by hand.
\documentclass{article}
\usepackage{amsmath}
\usepackage{cleveref}
\newcommand{\dd}[1]{\mathrm{d}#1}
\numberwithin{equation}{section}
\begin{document}
\section{Dimensional regularization}
\dots
After a Wick rotation we get
\begin{align}
\int\! \frac{\dd^4 \mathnormal{k}}{(2\pi)^4}\log(-k^2+m^2)&= \mathrm{i}\,\int\!
\frac{\dd^4 \mathnormal{k_E}}{(2\pi)^4}\log(k_E^2+m^2)\notag\\
&=-\mathrm{i} \frac{\partial}{\partial \alpha}\int\! \frac{\dd^4
\mathnormal{k_E}}{(2\pi)^4}\frac{1}
{(k_E^2+m^2)^{\alpha}}\Big\vert_{\alpha=0}\notag\\
&=-\mathrm{i}\, \frac{\partial}{\partial \alpha} \Big(\frac{1}
{(4\pi)^{d/2}}\frac{\Gamma(\alpha-\frac{d}{2})}
{\Gamma(\alpha)}\frac{1}{(m^2)^{\alpha-\frac{d}{2}}} \Big) \Big
\vert_{\alpha=0}\notag\\
&= -\mathrm{i}\,\frac{\Gamma(\frac{-d}{2})}{(4\pi)^{d/2}}
\frac{1}{(m^2)^{-
d/2}}
\label{eq:DimRegInt1}
\end{align}
\dots
As shown in \cref{eq:DimRegInt1}, \dots
\end{document}
