Why we know the renormalization work to all order in renormalizable theory?

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Discussion Overview

The discussion revolves around the concept of renormalization in quantum field theory, specifically addressing why renormalization is believed to work at all orders in perturbation theory within renormalizable theories. Participants explore the definitions, implications, and specific theorems related to renormalization.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks clarification on how finite divergent constants are absorbed by counterterms in higher orders of perturbation theory.
  • Another participant reflects on their initial understanding of the absorption process in renormalization, noting that higher-order diagrams involve an interplay of different counterterms, leading to uncertainty about the absorption's effectiveness at all orders.
  • A third participant asserts that the condition for renormalization working is essentially a definition of a renormalizable theory, suggesting that the question posed is tautological.
  • In response, another participant argues that the definition of renormalizable theory acknowledges that divergences can occur at all orders in perturbation theory, thus challenging the tautology claim.
  • One participant mentions that the BPHZ theorem provides an answer to the original question and requests assistance with its proof.

Areas of Agreement / Disagreement

Participants express differing views on whether the question of renormalization's effectiveness is tautological. There is no consensus on the implications of the BPHZ theorem or its proof, as some seek clarification while others assert its relevance.

Contextual Notes

Participants acknowledge the complexity of divergences in perturbation theory and the definitions surrounding renormalizable theories, but the discussion does not resolve the nuances of these concepts.

ndung200790
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Please teach me this:
In renormalizable theory,a finite divergent constants being absorbed by counterterms diagrams which are straight line counterterms and vertex counterterms.But I do not understand why in higher order of perturbation series the absorption still work.
Thank you very much in advanced.
 
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At first time,e.g in Phi4 theory there are only two divergent diagrams which are two leg and four leg diagrams with three divergent constants.With two counterterm diagrams that are straight line counterterm diagram and vertex counterterm diagram,I thought that the ''absorption'' for renormalization working for all diagrams(so for all order in perturbation series.But after that I realized in higher order diagrams,there is the interplay of different couterterms.So I suspect the working of ''the absorption'' for renormalization for all order of diagrams.Because my simple thinking before is not still correct.
 
Actually, your condition that renormalization works is a definition of a renormalizable theory, so your question is a tautology.
 
It seem to me that is not tautology,because the definition of renormalizable theory is: Only a finite ber of amplitudes superficially diverge;however,divergences occur at all orders in perturbation theory.
 
Sorry,having some spell mistakes.The definition of renormalizable theory is: Only a finite number of amplitudes superficially diverge;however,divergences occur at all orders in perturbation theory.
 
At the moment,I have known that the answer for the question is the BPHZ(Bogoliubov-Parasiuk-Hepp-Zimermann) theorem.Any one could be pleasure to help me to give the proof of BPHZ theorem?
 
ndung200790 said:
At the moment,I have known that the answer for the question is the BPHZ(Bogoliubov-Parasiuk-Hepp-Zimermann) theorem.Any one could be pleasure to help me to give the proof of BPHZ theorem?

try http://www.math.ru.nl/~landsman/CMP1.pdf
 

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