I have learned that the effective action can be obtained from legendre transforming the generating function $$W(J) = \ln(Z(J)),$$ which corresponds to connected graphs. However I don't quite get an idea of why effective action corresponds to one-particle-irreducible (1PI) graphs.
Asked
Active
Viewed 41 times
0
-
Possible duplicate: https://physics.stackexchange.com/q/146734/2451 – Qmechanic Jul 21 '22 at 14:13
-
The first chapter of Damiano Anselmi's free textbook `Renormalization' has a good discussion of this and some more advanced things about generating functionals – octonion Jul 21 '22 at 14:13
-
$\uparrow$ p. 34-39. – Qmechanic Jul 21 '22 at 15:03