Is the pole in this integrand integrable?

In summary, the conversation discusses a complicated expression involving integration variables, constants, and poles. The speaker is trying to determine if the poles in the expression are integrable, but is unsure due to the complexity of the expression. Another speaker suggests looking for symmetry or comparing it to the Dirac delta function, but doubts that it will have the same properties.
  • #1
junt
18
1
I am trying to numerically integrate the following complicated expression:

$$\frac{-2\exp{\frac{-4m(u^2+v^2+vw+w^2+u(v+w))}{\hbar^2\beta}-\frac{\hbar\beta(16\epsilon^2-8m\epsilon(-uv+uw+vw+w^2-4(u+w)\xi +8\xi^2)\omega^2+m^2(u^2+2v^2+2vw+w^2+2u(v+w-2\xi)-4w\xi+8\xi^2)(u^2+w^2-4(u+w)\xi+8\xi^2)\omega^4 )}{8m(u+w-4\xi)^2\omega^2}}}{|m(u+w-4\xi)\omega^2)|}$$

My integration variables are ##u##, ##v## and ##w## from +##\infty## to -##\infty##. Everything else are constants.

This is just an example of one integrand (motivated by a quantum mechanical system) where there exists infinitely many poles at ##u+w=4\xi##. I am wondering if such poles are integrable. My pole is linear, and as a result quite simple. But I am really unable to prove if this pole is integrable or not. Does anybody have any idea about this problem? It would be a great help!
 
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  • #2
At first look, I would doubt it. Unless you could show some kind of symmetry, which would cancel out. Or you could show it is like the Del function, which is infinitely high, yet infintessimally small, so that the area under it is equal to 1. But this doesn't look like something which would do that.
 

1. What is meant by "pole" in an integrand?

A pole in an integrand refers to a point where the function being integrated becomes infinite. It can also be thought of as a singularity in the function.

2. How do I determine if the pole in an integrand is integrable?

The integrability of a pole depends on the type of pole and the function being integrated. In general, simple poles (where the function approaches infinity in a smooth, linear manner) are integrable, while essential poles (where the function approaches infinity in an oscillatory manner) are not integrable.

3. Can a function have multiple poles that are all integrable?

Yes, a function can have multiple poles that are all integrable. In fact, many commonly used functions in mathematics and physics have multiple integrable poles.

4. Is there a specific method for integrating a pole in an integrand?

Yes, there are various techniques for integrating poles in integrands, such as the residue theorem and contour integration. The specific method used will depend on the type of pole and the function being integrated.

5. What are the implications of a non-integrable pole in an integrand?

If a pole in an integrand is non-integrable, it means that the integral cannot be evaluated using traditional techniques. This can have significant implications in certain calculations and may require alternative approaches to solve the integral.

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