Ultraviolet via dimensional regularization

In summary, using dimensional regularization can effectively handle divergent integrals, including those of power divergence, thanks to the cancellation of the Gamma function pole at d = 2.
  • #1
kassem84
13
0
The integral:
[itex]\int[/itex]d[itex]^{3}k[/itex][itex]\frac{1}{k^{2}+m^{2}}[/itex]
is linearly divergent i.e. ultraviolet divergent.
However, If one performs dimensional regularization to the above integral:
[itex]\frac{1}{(2\pi)^d}[/itex][itex]\int[/itex]d[itex]^{d}k[/itex][itex]\frac{1}{k^{2}+m^{2}}[/itex]=[itex]\frac{(m^{2})^{d/2-1}}{(4\pi)^{d/2}}[/itex][itex]\Gamma(1-d/2)[/itex]
As you can notice that the poles of the Gamma function are for even dimension i.e. d=2,4,6..etc and that the integral is convergent for d=3 for example!
What is the reason behind this convergence? Is it due to the Veltman's formula:
[itex]\frac{1}{(2\pi)^d}[/itex][itex]\int[/itex]d[itex]^{d}k[/itex][itex] (k^{2})^{n-1}[/itex] = 0, for n=0,1,2,..
I am dealing with a divergent integral of power divergence (ultraviolet, quadratic, quartic,... and no logarithmic divergence). Do you advise me to use dimensional regularization or other methods?
 
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  • #2
The reason why the integral is convergent in 3 dimensions when using dimensional regularization is because the Gamma function in the expression has a pole at d = 2, which cancels out the divergence of the integral. This is known as the 'dimensional regularization trick'. Dimensional regularization is a useful tool for dealing with divergent integrals, especially those of power divergence. It can also be used to regularize logarithmic divergences, though this requires some additional work. Other methods such as Pauli-Villars regularization and Zeta function regularization can also be used to regularize divergent integrals.
 

1. What is "Ultraviolet via dimensional regularization"?

"Ultraviolet via dimensional regularization" is a method used in theoretical physics to regulate divergences that occur in calculations involving ultraviolet (UV) radiation. It involves extending the number of dimensions in which the calculation takes place, typically from 3+1 dimensions to 4+d dimensions, and then taking the limit as d approaches zero.

2. Why is "Ultraviolet via dimensional regularization" used?

"Ultraviolet via dimensional regularization" is used because it provides a systematic and consistent way to deal with divergences that arise in quantum field theory calculations. It allows for the calculation of physical quantities, such as particle masses and interactions, without encountering infinite values.

3. How does "Ultraviolet via dimensional regularization" work?

"Ultraviolet via dimensional regularization" works by introducing a parameter, d, that represents the number of extra dimensions. This parameter is used to regulate the UV divergences by allowing for the integration to be performed in higher dimensions. The final result is then obtained by taking the limit as d approaches zero.

4. What are the advantages of "Ultraviolet via dimensional regularization"?

One of the main advantages of "Ultraviolet via dimensional regularization" is that it is a mathematically rigorous method that can provide finite results for divergent calculations. It also preserves important symmetries, such as gauge symmetry and Lorentz symmetry, making it a useful tool in theoretical physics.

5. Are there any limitations to "Ultraviolet via dimensional regularization"?

While "Ultraviolet via dimensional regularization" is a powerful tool, it does have its limitations. It can only be used for calculations involving UV divergences and is not suitable for dealing with infrared (IR) divergences. It also requires careful handling of the limit as d approaches zero, as this can introduce certain mathematical subtleties.

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