Recent content by Einsling

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    Graduate Commutate relation of lowering operator and sperical tensor operators

    Hi all, I found a commutation relation of lowering operator(J-) and spherical operator in Shankar's QM (2ed, page 418, Eq 15.3.11): [J_-,T_k^q] = - \hbar \sqrt{(k+q)(k-q+1)} T_k^{q-1} I wonder how the minus sign in the beginning of the right hand side come out? I have googled some...
    • Einsling
    • Thread
    • Lowering operator Operator Operators Relation Tensor
    • Replies: 1
    • Forum: Quantum Physics
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    Graduate How to Integrate e^x / (1+x^2) with Complex Contour Integration?

    Hi Could you please tell me how to integrate it? Thanks ~~ \int_{-\infty}^{\infty} \frac {e^{i\omega t}} {1+\frac{t^2}{\tau^2}} dt where i is imaginary unit, \omega, \tau are positive real,