Perturbative QCD Evolution and Color Dipole Picture
Abstract
The proton structure function in the diffraction region of small Bjorken$x$ and $10 {\rm GeV}^2 \le Q^2 \le 100 {\rm GeV}^2$ behaves as $F_2 (x, Q^2) = F_2 (W^2) = f_0 \cdot (W^2)^{C_2}$, where $x = Q^2 / W^2$. The exponent $C_2$ of the $\gamma^* p$ centerofmass energy squared, $W^2$, is predicted from evolution of the flavorsinglet quark distribution, $C_2 = 0.29$, and the only free parameter, the normalization $f_0 = 0.063$, is fitted. The evolution of the gluon density multiplied by $\alpha_s (Q^2)$ is dentical to the evolution of the flavorsinglet quark density. This simple picture is at variance with the standard approach to evolution based on the coupled equations of flavorsinglet and gluon density.
 Publication:

arXiv eprints
 Pub Date:
 April 2011
 arXiv:
 arXiv:1104.0850
 Bibcode:
 2011arXiv1104.0850S
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 11 pages, 4 figures