Impact of low-x resummation on QCD analysis of HERA data

Abstract

Abstract Fits to the final combined HERA deep-inelastic scattering cross-section data within the conventional DGLAP framework of QCD have shown some tension at low x and low $$Q^2$$ Q2 . A resolution of this tension incorporating $$\ln (1/x)$$ ln(1/x) -resummation terms into the HERAPDF fits is investigated using the xFitter program. The kinematic region where this resummation is important is delineated. Such high-energy resummation not only gives a better description of the data, particularly of the longitudinal structure function $$F_L$$ FL , it also results in a gluon PDF which is steeply rising at low x for low scales, $$Q^2 \simeq 2.5\,\hbox {GeV}^2$$ Q2≃2.5GeV2 , contrary to the fixed-order NLO and NNLO gluon PDF.