Techniques for calculations with nPI effective actions
1 Department of Physics, Brandon University, Brandon, Manitoba, R7A6A9, Canada
2 Winnipeg Institute for Theoretical Physics, Winnipeg, Manitoba, Canada
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Published online: 29 May 2015
We consider a symmetric scalar theory with quartic coupling in 2- and 3- dimensions and compare the self-consistent 4-point vertex obtained from the 4PI effective action with the Bethe-Salpeter 4-vertex from 2PI effective action. We show that when the coupling is large the contributions from the higher order effective action are large. We also show that one can solve the 2PI equations of motion in 4-dimensions, without introducing counter-terms, using a renormalization group method. This method provides a promising starting point to study the renormalization of higher order nPI theories.
© Owned by the authors, published by EDP Sciences, 2015
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