Showing the Representation of the Delta Function

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SUMMARY

The discussion centers on demonstrating that the expression \(\frac{1}{\pi}\lim_{\epsilon \to 0^+}\frac{\epsilon}{\epsilon^2+k^2}\) serves as a representation of the delta function. Participants reference the integral \(\int^{\infty}_{-\infty}\frac{\epsilon}{\epsilon^2+k^2}dk=\pi\) and discuss the significance of the limit approaching from the positive side, \(\epsilon \to 0^+\). The confusion arises around the implications of this limit and its role in defining the delta function's properties.

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  • Understanding of delta functions in mathematical analysis
  • Familiarity with limits and their properties in calculus
  • Knowledge of Fourier transforms and their applications
  • Basic proficiency in integral calculus
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  • Learn about the derivation and applications of Fourier transforms
  • Explore the concept of limits in calculus, particularly one-sided limits
  • Investigate the role of regularization techniques in mathematical physics
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Homework Statement


Show that
##\frac{1}{\pi}\lim_{\epsilon \to 0^+}\frac{\epsilon}{\epsilon^2+k^2}##
is representation of delta function.

Homework Equations


##\delta(x)=\frac{1}{2 \pi}\int^{\infty}_{-\infty}dke^{ikx}##

The Attempt at a Solution



##\int^{\infty}_{-\infty}\frac{\epsilon}{\epsilon^2+k^2}dk=\pi##
One can take ##F[e^{-\epsilon x}]## and then put ##\epsilon to go to zero +. Why ##0^+##. I'm confused?
 
Physics news on Phys.org
Why ##0^+##. I'm confused?
What happens when you take the limit from the other side?
 

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