# ICHEP2018 SEOUL

Jul 4 – 11, 2018
COEX, SEOUL
Asia/Seoul timezone

## Studies of HERA deep inelastic scattering data at low Q^2 and low x_Bj

Jul 5, 2018, 12:00 PM
15m
101 (COEX, Seoul)

### 101

#### COEX, Seoul

Parallel Strong Interactions and Hadron Physics

### Speaker

Dr Volodymyr Myronenko (Deutsches Elektronen-Synchrotron)

### Description

A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering (DIS) 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 of $Q^2 = 0.045$ GeV$^2$ and Bjorken $x$, $x_{\rm Bj} = 6 \times 10^{−7}$. 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 DGLAP formalism from the highest $Q^2$ down to $Q^2$ of a few GeV$^2$. The standard DGLAP evolution was augmented by including an additional higher-twist term in the description of the longitudinal structure function, $F_L$. This additional term, $F_L A_L^{\rm HT}/Q^2$, improves the description of the reduced cross sections significantly. The resulting predictions for F_L suggest that further corrections are required for $Q^2$ less than about 2 GeV$^2$. The Regge formalism can describe the data up to $Q^2 \sim 0.65$ GeV$^2$. The complete data set can be described by a new fit using the ALLM parameterisation. The region between the Regge and the perturbative QCD regimes is of particular interest.

### Primary authors

Matthew Wing (University College London) Katarzyna Wichmann (Deutsches Elektronen-Synchrotron (DE)) Dr Volodymyr Myronenko (Deutsches Elektronen-Synchrotron) Brian Foster (University of Oxford (GB)) Amanda Sarkar (University of Oxford (GB)) Iris Abt (MPI)