Proton structure function. Soft and hard Pomerons

Regge models for proton structure function with and without a hard Pomeron contribution are compared with all available data in the region $W>3$ GeV, $Q^2\le 3000$ GeV${}^2$ and $x<0.75$. It is shown that the data do not support a hard Pomeron term in ${\gamma }^{\ast }p$ amplitude. Moreover, the data support the idea that the soft Pomeron, either is a double pole with ${\alpha }_P(0)=1$ in the angular momentum $j$-plane, or is a simple pole with ${\alpha }_P(0)=1+ϵ$ where $ϵ\ll 1$.