Investigation into the limits of perturbation theory at low Q2 using HERA deep inelastic scattering data

Abstract

A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering has been performed. The data are presented and investigated for a kinematic range extending from values of the four-momentum transfer, Q 2 , above 10 4 GeV 2 down to the lowest values observable at HERA ofand Bjorken x, x Bj ¼ 6 × 10 −7 . The data are well described by fits based on perturbative quantum chromodynamics (QCD) using collinear factorisation and evolution of the parton densities encompassed in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi formalism from the highest Q 2 down to Q 2 of a few GeV 2 . The Regge formalism with the soft Pomeron pole can describe the data up to Q 2 ≈ 0.65 GeV 2 . The complete data set can be described by a new fit using the Abramowicz-LevinLevy-Maor parametrization. The region between the Regge and the perturbative QCD regimes is of particular interest.

Photon structure studied at an electron ion collider

“…FIG. 2 (upper plots) shows an excellent agreement between the PYTHIA-6 simulation using CTEQ5m as the Proton PDF and SAS 1D-LO as the Photon PDF and the low Q 2 data from HERA [20]. The lower parts of FIG.…”

Saturation model of DIS: an update

“…We fit the proton structure function F 2 computed from the HERA data [1] on the γ * p cross section from the relation…”

“…The new data [1] on the proton structure function F 2 , extracted from the HERA measurements [2,3], prompted us to address the question how the saturation model of DIS [26][27][28] describes this data for small values of the Bjorken variable, x ≤ 10 −2 , and Q 2 in the range between 0.065 GeV 2 and 650 GeV 2 . Table 1 and 3, respectively, against the HERA data from [49].…”

“…The logarithmic slope in x of F 2 as a function of Q 2 is shown in the right plot for the same models. The experimental points are from Ref [1]…”

Recent investigations of QCD at HERA

“…The recently published final combined HERA data in inclusive deep inelastic scattering [11] provide a wealth of input to understanding QCD, such as being the pre-eminent data set in the extraction of proton PDFs and a precise extraction of α s . The data can also be used to understand a region where pQCD is not expected to describe the data, at low Q 2 and low Bjorken x [20]. Data at the lowest Q 2 are shown in Fig.…”