- #1

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## Homework Statement

Write the momentum space integral representation for the following diagram in QED

## Homework Equations

## The Attempt at a Solution

[/B]

##i\mathcal{M}=(-1)\bar{u}(k')v(k'_+)(-ie\gamma^\nu)\left(\frac{-ig_{\nu\sigma}}{q^2+i\epsilon}\right)\left(\frac{-ig_{\mu\rho}}{q^2+i\epsilon}\right)(-ie\gamma^\mu)u(k)\bar{v}(k_+)\displaystyle\int\frac{d^4l}{(2\pi)^4}\times##

##\times tr\left[(-ie\gamma^\sigma)\frac{i(\slashed{l}+\slashed{q}+m)}{(l+q)^2-m^2+i\epsilon}(-ie\gamma^\rho)\frac{i(\slashed{l}+m)}{l^2-m^2+i\epsilon}

\right]##

Is this correct? I'm using the rules on page 801 of Peskin & Schroeder. The main thing I'm not sure about if I should have those ##\epsilon## since I've seen examples where they weren't included.

The ##-1## comes from a closed fermion loop.