What is the Fourier transform of this function ?

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Discussion Overview

The discussion revolves around finding the Fourier transform of the function \( \frac{1}{\sqrt{q^2 + m^2}} \), where \( m \neq 0 \) is a parameter. Participants explore methods for calculating this transform, including contour integration and potential connections to Bessel functions.

Discussion Character

  • Exploratory, Technical explanation, Mathematical reasoning

Main Points Raised

  • One participant expresses difficulty in finding the Fourier transform and requests assistance.
  • Another participant provides the integral form of the Fourier transform and confirms the request for the forward transform.
  • A participant mentions attempting to evaluate the integral using contour integration but encounters issues due to the non-integer order of the pole at \( q = im \).
  • One participant speculates that the solution may involve Bessel functions and shares a link to an external Fourier transform calculator for further exploration.
  • A later reply indicates that the integral is related to finding the Green's function for a graphene ribbon.

Areas of Agreement / Disagreement

Participants generally agree on the function to be transformed and the methods being considered, but there is no consensus on how to proceed with the calculation or the nature of the solution.

Contextual Notes

Participants have not resolved the mathematical challenges associated with the contour integration or the implications of the pole's order. The discussion remains open to various approaches and interpretations.

hiyok
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Hi, I have problems finding out the Fourier transform of the following function,

1/\sqrt{q^2 + m^2}, where m\neq 0 denotes a parameter.

It seems easy, but I don't know how. Could anybody show me how to do it ?

Thanks in advance.

hiyok
 
Last edited:
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$$f(q)=\frac{1}{\sqrt{q^2+m^2}}\\ \mathcal{F}(p)=\int_{-\infty}^\infty \frac{e^{-2\pi iqp}}{\sqrt{q^2+m^2}}\;\text{d}q$$ ... this correct?
i.e. you want the forward Fourier transform...

Please show your best attempt.
 
Last edited:
Yes, that is exactly what I meant.

I tried to make a contour and evaluate the residue around the pole q=im. But the order of this pole is not integer. I don't know how to proceed.

Thanks
 
Thanks a lot for your useful message. I'll look into your link.

I met this integral when trying to find out the Green's function for a graphene ribbon.
 

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