Solution (source code)

= Solution

For $\operatorname{Re}\alpha>0$, the even exponential is $h(t)=g(t)+g(-t)$ except for an irrelevant single value at zero. <Linearity> and the <scaling property of the Fourier transform> at $b=-1$ give
$$
\widetilde h(\omega)=\frac1{\alpha+i\omega}+\frac1{\alpha-i\omega}
=\boxed{\frac{2\alpha}{\alpha^2+\omega^2}}.
$$
In particular, for positive real $\alpha$ the transform is real and even, as expected from the symmetry of $h$.