Talk:Schwinger's quantum action principle

I don't understand

From looking at good books (like Joachain, 1975) on scattering theory on Schwinger variatonal principle, I really don't understand what is the relation of this article with what is known in the literature under this name. Is the Schwinger variational principles really so simple? Since I don't know what is S_AB, I cannot judge. But as far as I know I am thinking at a crackpot!

• I agree with the user above, the value of S_AB should be indicated although if its an action perhaps is of the form:

$S_{AB}=\alpha ({\dot {X}})^{2}-V(X)$

where X is the position operator and V is the potential..

Also, a definition of S needs to be given. Xxanthippe (talk) 22:59, 10 July 2011 (UTC).