Proton structure function at smallQ 2

Abstract

A fit is made to the data for the proton structure function up to Q 2 = 10 GeV 2 , including the real γp total cross-section. It is economical and simple, and its form is motivated by physical principles. It is extrapolated down to very small values of x. Data for the ratio νW n 2 /νW p 2 are also fitted.

Charm production in deep inelastic and diffractive scattering

“…The low energy data for electroproduction are from Ref. [30,31] and the high energy data from H1 [32]. The latter data correspond to Q 2 values slightly different from those of the low energy data and of our calculations.…”

Exclusive Production of Neutral Vector Mesons at the Electron-Proton Collider HERA

“…10, along with the ZEUS results from the 1994 data at low Q 2 . The comparison to data from the E665 collaboration [112] at higher x using extrapolations based on Regge-type energy dependence [110] and that expected from QCD calculations [116] indicates that the transition occurs between Q 2 values of 0.16 and 3.0 GeV 2 . While this conclusion is mitigated by the necessity of comparing results from two different experiments and by the 5% normalization uncertainty in the ZEUS results not shown in Fig.…”

“…In this plot we compare as well the very different energy dependences of the photoproduction and deep inelastic cross sections. The solid line indicates the expectations based on phenomenological Regge theory [110], which describe the photoproduction measurements well but are inconsistent with the virtual-photon-proton measurements. The dashed line corresponds to the limit of validity ZEUS 1994 of the cross section definition specified by eq.…”

“…[109], compared to measurements at higher Q 2 using the 1993 data [28], the HERA photoproduction cross section measurements [103,104], and the low-energy deep inelastic [30,111,112], and photoproduction [113] measurements. The curve represents a parametrization of the photoproduction measurements based on phenomenological Regge theory [110]. The dashed line connects points where x=0.1.…”

“…The low-energy photoproduction measurements [113] are also shown. Calculations based on phenomenological Regge theory [110] are indicated as dotted lines and perturbative QCD calculations [116] …”