Divergent series in perturbation theory of quantum field theory

In summary, if we know the divergent series in perturbation theory of quantum field theory goes in the form of a sum with coefficients dependent on the parameter g and the cutoff parameter epsilon, where epsilon approaches 0, then we can apply the renormalization procedure by choosing a regularization scheme, such as a cutoff, to eliminate the divergences and obtain finite results. This cannot be done for non-renormalizable series and the specific details of the renormalization process depend on the chosen regularization scheme.
  • #1
eljose
492
0
if we know that the divergent series in perturbation theory of quantum field theory goes in the form:

[tex]\sum_{n=0}^{\infty}a(n)g^{n}\epsilon^{-n}[/tex] with

[tex]\epsilon\rightarrow{0} [/tex]

then ..how would we apply the renormalization procedure to eliminate the divergences and obtain finite results?...why can not this be done to NOn-renormalizable series?..thanks.
 
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  • #2
Ok first of all you are abusing terminology a little bit.

What you want to do is first and foremost, choose a regularization scheme.

Namely, pick a cutoff on that infinite series. The details of the renormalization process depends crucially on the details of which type of cutoff you pick.
 
  • #3
I would not chose this cutoff. Chose something like exp(-epsilon*n)
If esilon-->0 then exp(-epsilon*n)=1.
 

Related to Divergent series in perturbation theory of quantum field theory

1. What is the perturbation theory in quantum field theory?

The perturbation theory in quantum field theory is a mathematical method used to calculate approximate solutions to quantum field theories. It is based on the idea of dividing a complex problem into a simpler one, where the solution can be obtained by adding corrections to the simpler solution. It is widely used in many areas of physics, including particle physics and condensed matter physics.

2. How does the perturbation theory apply to the Divergent series?

In the Divergent series, the perturbation theory is used to deal with divergences that arise in the calculations. These divergences are mathematical infinities that arise due to the nature of quantum field theories. The perturbation theory allows us to systematically remove these infinities and obtain meaningful results.

3. What is the role of Feynman diagrams in the perturbation theory of quantum field theory?

Feynman diagrams are a graphical representation of the perturbation theory in quantum field theory. They depict the various interactions between particles and can be used to calculate the probability of a particular process occurring. They are an essential tool in understanding and predicting the behavior of quantum field theories.

4. Can the perturbation theory be used for all quantum field theories?

The perturbation theory is a powerful tool, but it is not applicable to all quantum field theories. It is most effective for theories where the coupling constants (which describe the strength of interactions) are small. In theories with strong coupling, the perturbation theory breaks down, and alternative methods must be used.

5. What are the limitations of the perturbation theory in quantum field theory?

One of the main limitations of the perturbation theory is that it only provides an approximate solution. As the number of corrections increases, the results become more accurate, but there is always a margin of error. In addition, there are certain situations, such as in the presence of large external fields, where the perturbation theory may not be applicable. In these cases, other techniques, such as non-perturbative methods, must be used.

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