A How to Approach Solving a Complex Trigonometric Integral?

AI Thread Summary
The discussion centers on solving a complex trigonometric integral related to the function S_T(ω). The integral involves parameters like k_B, T, g, c, and D, with a specific form presented in a referenced paper. Users suggest differentiating the integral to verify the results and recommend using tools like WolframAlpha for numerical verification. A transformation from ω to θ is proposed as a method to simplify the integral. The conversation emphasizes the need for clarity in reaching the solution presented in the paper.
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Hello everyone

Can someone help me out solving this integral:
\begin{equation}
S_T(\omega)=\frac{2k_BT^2g}{4\pi^2c^2}\int_0^{\infty}\frac{sin^2(kl)}{k^2l^2}\frac{k^2}{D^2k^4+\omega^2}dk
\end{equation}

Where $$D=g/c$$

According to this paper https://doi.org/10.1103/PhysRevB.13.556. The solution to the integral is:

\begin{equation}
S_T(\omega)=\frac{k_BT^2D^{1/2}}{4\sqrt{2}l^2c\pi\omega^{3/2}}(1-e^{-\theta}(sin(\theta)+cos(\theta)))
\end{equation}

Where $$\theta=(\omega/\omega_0)^{1/2}$$ and $$\omega_0=D/2l^2$$

I am not able to reach the result they present in the paper. Hence any help will be very much appreciated.
 
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If you only want to verify it, why don't you just differentiate?
 
fresh_42 said:
If you only want to verify it, why don't you just differentiate?
It is a specific integral, not an antiderivative.

WolframAlpha and similar tools should be able to verify it, at least numerically.

Going from w to θ should simplify the integral significantly.
 
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