simplifying expressions – Real part of a function

How to find the real part of the following function in Mathematica?
The function is $$e^{-ipsi}langlebeta|alpharangle$$. When expanded, it is given as:
$$e^{-ipsi}expleft(beta^{*}alpha-vertalphavert^{2}/2-vertbetavert^{2}/2right)$$

The following is what I have written in Mathematica.

E^(-I (Psi) - 
 1/2 (Alpha) Conjugate((Alpha)) + (Alpha) Conjugate((Beta)) - 
 1/2 (Beta) Conjugate((Beta)))