What Causes Divergences in QFT?

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In summary, the conversation discusses the question of whether all divergences in QFT can be expressed as integrals of the form \int_{0}^{\infty}dkk^{m}, where m is a non-negative integer. It is suggested that any other divergences can be expressed as a series of these integrals with coefficients a(r). The conversation concludes that, in general, all integrals in QFT follow this form, but there may be additional complexities such as overlapping divergences and subgraphs.
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eljose
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more than a proper topic this is a question...my question is if all the divergences that appear in QFT are due to integrals in the form:

[tex] \int_{0}^{\infty}dkk^{m} [/tex]

with m=-1 (logarithmic),0,1,2,3,4,5,...

if not i think that for any other divergences you could express them as:

[tex] \int_{0}^{\infty}dkF(k)= \sum_{r=0}^{\infty}a(r)\int_{0}^{\infty}dkk^{r} [/tex]

r=0,1,2,3,4,5,... and a(r) the coefficients of the series expansion for the function F(k) of course K here is the "momentum" modulus [tex] p=\hbar{k} [/tex]
 
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Roughly speaking yes, all integrals are of this form. Though there is the issue of overlapping divergences and subgraphs, e.g. a single loop integral might result in a logarithmically divergent term that contains the integration variable of another loop integral.
 

1. What is a divergence in Quantum Field Theory (QFT)?

A divergence in QFT refers to a mathematical term used to describe an infinite or undefined value in a calculation. It arises when trying to describe the behavior of particles at extremely small distances or high energies. These divergences indicate a breakdown of the theory and require special techniques to be resolved.

2. What causes divergences in QFT?

Divergences in QFT are caused by the inherent limitations of the theory itself. QFT is a quantum theory that describes the interactions between particles and fields, but it is based on classical theories that do not take into account the effects of quantum mechanics. This mismatch between the underlying theories leads to divergences when trying to describe extremely small distances and high energies.

3. How are divergences in QFT resolved?

There are various techniques used to resolve divergences in QFT, such as renormalization and regularization. Renormalization involves redefining certain parameters in the theory to cancel out the infinities, while regularization involves introducing a finite cutoff to restrict the calculations to a certain range of energies. These techniques allow for meaningful and accurate predictions to be made within the framework of QFT.

4. Can divergences in QFT be eliminated completely?

No, it is not possible to completely eliminate divergences in QFT. They are a fundamental part of the theory and are a consequence of trying to describe the behavior of particles at extremely small distances and high energies. However, through the use of techniques such as renormalization and regularization, these infinities can be controlled and predictions can be made with high accuracy.

5. How do divergences in QFT affect our understanding of the universe?

Divergences in QFT have led to some of the most profound discoveries in physics, such as the existence of the Higgs boson and the prediction of the cosmic microwave background radiation. They also play a crucial role in our understanding of the fundamental forces and particles in the universe. By studying and resolving these infinities, we are able to gain a deeper understanding of the underlying principles that govern our universe.

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