Fourier transform of vector potential

Amith2006
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Homework Statement


I have question on doing the following indefinite integral:
$$\int{d^3x(\nabla^2A^{\mu}(x))e^{iq.x}}$$

Homework Equations


This is part of derivation for calculating the Rutherford scattering cross section from Quarks and Leptons by Halzen and Martin. This books gives the following result obtained by partial integration of the above integral:
$$\int{d^3xA^{\mu}(x)(\nabla^2e^{iq.x})}$$

The Attempt at a Solution


I tried to use the identity from vector calculus:
$$\nabla^2(\phi\psi) = \phi\nabla^2\psi + \psi\nabla^2\phi + 2\nabla\phi.\nabla\psi$$
But not sure how to get rid of the other terms.
Any help is most welcome.
 
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No, you need to use partial integration as mentioned by the authors and not vector identities. I suggest you start in one dimension and then see how it generalises. Also remember that the fields are assumed to go to zero at infinity such that the boundary terms from the partial integration vanishes.
 
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There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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