Vacuum state Lorentz invariance

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Discussion Overview

The discussion centers around the Lorentz invariance of the vacuum state in quantum field theory (QFT). Participants explore whether this invariance is as self-evident as often claimed, particularly in the context of rigorous formulations of QFT beyond quantum electrodynamics (QED).

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant questions the necessity of proving Lorentz invariance of the vacuum state, suggesting it may not be as obvious in general cases as it is in QED.
  • Another participant asserts that Lorentz invariance is established in rigorous relativistic QFT by satisfying the Osterwalder-Schrader conditions, noting that rigorous constructions exist only in lower dimensions (1+1D and 2+1D).
  • Several participants share resources for further reading on the topic, including links to axiomatic QFT and specific texts.
  • There is a discussion about the merits of Bogoliubov's books on axiomatic QFT and a specific paper by Bednorz, with one participant expressing uncertainty about the paper's content but acknowledging its potential worth.
  • Concerns are raised about the perturbative nature of Bednorz's proof, which assumes the existence of the theory, contrasting it with the more constructive approaches referenced earlier.

Areas of Agreement / Disagreement

Participants express differing views on the clarity and necessity of proving Lorentz invariance of the vacuum state. While some assert its established nature in rigorous QFT, others question its obviousness and express uncertainty regarding the implications of related literature.

Contextual Notes

The discussion highlights limitations in the current understanding of Lorentz invariance in QFT, particularly regarding the dimensionality of rigorous constructions and the assumptions underlying perturbative proofs.

Who May Find This Useful

Readers interested in advanced topics in quantum field theory, particularly those exploring the foundations of Lorentz invariance and rigorous formulations of QFT.

Gvido_Anselmi
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Hi everybody!
Why we don't have to prove Lorentz invariance of the Vacuum state in QFT?
This fact is quite obvious in QED and follows from Lorentz invariance of electric charges.
But in general case?
I don't know, but it seems to me this fact is not so obvious as it treated.
 
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It is proved in rigourous relativistic quantum field theory by verifying that the construction satisfies conditions such as the Osterwalder-Schrader conditions.

So far, rigourous relativistic QFTs have only been constructed in 1+1D and 2+1d. The usual quantum field theories like QED etc are not rigourous.
 
atyy said:
It is proved in rigourous relativistic quantum field theory by verifying that the construction satisfies conditions such as the Osterwalder-Schrader conditions.

So far, rigourous relativistic QFTs have only been constructed in 1+1D and 2+1d. The usual quantum field theories like QED etc are not rigourous.

Thank you for your answer! Where can I read about it?
 
Last edited:
atyy said:
http://ncatlab.org/nlab/show/Wightman+axioms
http://ncatlab.org/nlab/show/Osterwalder-Schrader+theorem

http://rivasseau.com/resources/book.pdf
From perturbative to constructive Renormalization
Vincent Rivasseau

https://www.amazon.com/dp/1107005094/?tag=pfamazon01-20
Quantum Mechanics and Quantum Field Theory: A Mathematical Primer
Jonathan Dimock

Thank you, I will study these texts. And how do you like Bogoliubov's books on axiomatic QFT?
Can I also ask for your opinion on this paper? http://arxiv.org/pdf/1209.0209v2.pdf
 
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Ok, then I will better follow your recommendations in literature ))
 
Gvido_Anselmi said:
Ok, then I will better follow your recommendations in literature ))

Well, the comments of the referees don't seem to disagree that Bednorz's work is correct. The only dispute is about its novelty. So it seems Bednorz's paper is worth studying. I think the main limitation of the proof is that it is perturbative, as Bednorz mentions in his abstract, so it assumes the theory exists. In contrast, the references I gave do construct the theory.
 
atyy said:
Well, the comments of the referees don't seem to disagree that Bednorz's work is correct. The only dispute is about its novelty. So it seems Bednorz's paper is worth studying. I think the main limitation of the proof is that it is perturbative, as Bednorz mentions in his abstract, so it assumes the theory exists. In contrast, the references I gave do construct the theory.

Thank you very much. Quite possible it worth studying. But it seems to me quite strange in some ways. It's very different from QFT to which I am accustomed. So my decision is that following your recommendations will be more usefull now.
 

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