Pomeron effective intercept, logarithmic derivatives of $F_2(x,Q^2)$ in DIS and Regge models

Abstract

The drastic rise of the proton structure function $F_2(x,Q^2)$ when the Björken variable $x$ decreases, seen at HERA for a large span of $Q^2$, may be damped when $x\to 0$ and $Q^2$ increases beyond $\sim$ several hundreds \g2. This phenomenon observed in the Regge type models is discussed in terms of the effective Pomeron intercept and of the derivative $B_x=\partial \ell n{F}_2(x,Q^2)/\partial \ell n(1/x)$. The method of the overlapping bins is used to extract the derivatives $B_x$ and $B_Q=\partial \ell n{F}_2(x,Q^2)/\partial Q^2$ from the data on $F_2$ for $6.0\cdot 10^{-5}\le x\le 0.61$ and $1.2\le Q^2$ (\g2) $\le 5000$. It is shown that the extracted derivatives are well described by recent Regge models with the Pomeron intercept equal one.

Comments: 18 pages, LaTeX2e with cite.sty, 7 figures