Study of HERA ep Data at Low Q^2 and Low x_Bj and the Need for Higher-Twist Corrections to Standard pQCD Fits

I. Abt; A. Cooper-Sarkar; B. Foster; B. Foster; V. Myronenko; K. Wichmann; M. Wing

Paper

Study of HERA ep Data at Low Q^2 and Low x_Bj and the Need for Higher-Twist Corrections to Standard pQCD Fits

Abstract

A detailed comparison of HERA data at low Bjorken-

and low four-momentum-transfer squared,

, with predictions based on

evolution (DGLAP) in perturbative Quantum Chromo Dynamics suggests inadequacies of this framework. The standard DGLAP evolution was augmented by including an additional higher-twist term in the description of the longitudinal structure function,

. This additional term,

, improves the description of the reduced cross sections significantly. The resulting predictions for

suggest that further corrections are required for

less than about 2 GeV