Proton structure function. Soft and hard Pomerons

Abstract

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, $Q^{2}\leq 3000$ GeV$^{2}$ and $x<0.75$. It is shown that the data do not support a hard Pomeron term in $\gamma^{*} p$ 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 $\alpha_{P}(0)=1+\epsilon$ where $\epsilon \ll 1$.