How to Approach Solving a Complex Trigonometric Integral?

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SUMMARY

The discussion focuses on solving the complex trigonometric integral defined as S_T(ω) involving parameters such as k_B, T, g, and c. The integral is presented in the context of a specific paper, which provides a solution that includes the terms D, θ, and ω_0. Participants suggest using differentiation for verification and recommend utilizing WolframAlpha for numerical validation. The transformation from ω to θ is highlighted as a method to simplify the integral.

PREREQUISITES
  • Understanding of trigonometric integrals and their properties
  • Familiarity with the concepts of thermal energy (k_B, T) in physics
  • Knowledge of integral calculus, specifically techniques for solving complex integrals
  • Experience with computational tools like WolframAlpha for numerical analysis
NEXT STEPS
  • Study the derivation of the integral solution presented in the paper (https://doi.org/10.1103/PhysRevB.13.556)
  • Learn about the application of differentiation in verifying integral results
  • Explore the transformation techniques from ω to θ in integral calculus
  • Investigate advanced numerical methods for solving complex integrals using software tools
USEFUL FOR

Mathematicians, physicists, and students engaged in advanced calculus or integral equations, particularly those working with thermal physics and trigonometric integrals.

Excom
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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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