A question on counterterms

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In summary, the conversation discusses the issue of adding counterterms to the Lagrangian in order to make it finite when dealing with logarithmic divergences. It is suggested that using dimensional regularization can reduce power law divergences to only logarithmic divergences. However, the exact number of counterterms needed to achieve finite results is uncertain. Another approach is using operator-regularization, which is a more general method that can eliminate the need for adding extra terms to the original Lagrangian.
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zetafunction
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If i have ONLY logarithmic divergences as [tex] \lambda \rightarrow \infty [/tex] of the form

[tex] log(a+\lambda ^{n}) [/tex] or [tex] log (\lambda ) [/tex] or [tex] log^{k}(\lambda) [/tex] for some real numbers a,n and k HOW many counterterms should i put into de Lagrangian in order to make it FINITE ?? , the idea is let us suppose we use DIMENSIONAL REGULARIZATION so we only had logarithmic divergent integrals (and assuming that power law divergences can be reduced by dimensional regularization or other method to only logarithmic divergences), how many counterterms should i add to the original lagrangian to obtain finite results ??
 
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  • #2
One way around is to use operator-regularization (a generalization of the zeta-function) that will take care of everything, and preclude the need to add extra terms to the original Lagrangian (should they be needed).
 

1. What are counterterms?

Counterterms are mathematical quantities that are added to the equations of a physical theory in order to remove divergences or inconsistencies. They are used in the process of renormalization, which is a technique used to make sense of calculations in quantum field theory.

2. Why are counterterms necessary?

Counterterms are necessary because many physical theories, particularly in quantum field theory, contain infinities or divergences in their calculations. These infinities arise from the fact that the equations used to describe the behavior of particles at a very small scale break down. Counterterms are added to the equations to cancel out these infinities and make the calculations meaningful.

3. How are counterterms determined?

The determination of counterterms is a highly technical process that involves using mathematical techniques such as perturbation theory and dimensional regularization. These methods involve making small adjustments to the original equations to remove the infinities, and then using experimental data to determine the specific values of the counterterms.

4. Do all physical theories require counterterms?

No, not all physical theories require counterterms. The need for counterterms arises in quantum field theories, which describe the behavior of particles at a very small scale. In other theories, such as classical mechanics or general relativity, these infinities do not arise and therefore counterterms are not needed.

5. Can counterterms be experimentally verified?

Yes, counterterms can be experimentally verified. The values of counterterms are determined using experimental data, and the predictions made by the theory with these counterterms can be compared to experimental results. If the predictions match the data, it provides evidence that the counterterms were chosen correctly.

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