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The extraction of the total cross section $\sigma _{e p}$

The $ep$ cross section $\sigma _{e p}$ can be viewed as the product of the flux of virtual photon times total cross section of photon proton scattering:
\sigma_{e p }( Q^2 < Q^2_{max} ; y_{min}<y<y_{max}) = \int
\int dy dQ^2 \sigma_{\gamma^* p} ( Q^2, W) \phi (Q^2,y)
\end{displaymath} (3)

\phi (Q^2,y) = \frac{\alpha _{em}}{2\pi } \frac{1}{yQ^{2}}
\left[ 1+(1-y)^{2}-2\frac{m^{2}_{e}y^{2}}{Q^{2}}\right]
\end{displaymath} (4)

is the flux of virtual photon.


Giulio D'Agostini 2004-05-05