Speakers
Prof.
A. Cooper-Sarkar
(Oxford)Prof.
Amanda Cooper-Sarkar
(Oxford University)Prof.
Amanda Cooper-Sarkar
(Oxford)
Description
In the HERAPDF2.0 PDF analysis it was noted that the fit $chi^2$
worsens significantly at low $Q^2$ for both NLO and NNLO fits. The
turn over of the reduced cross section at low-$x$ and low $Q^2$ due to
the contribution of the longitudinal cross section $F_L$ is also not
very well described. In this paper the prediction for $F_L$ is
highlighted and the corresponding extraction of $F_2$ from the data is
further investigated, showing discrepancies with description of
HERAPDF2.0 at low $x$ and $Q^2$. The effect of adding a simple higher
twist term of the form ~constant/Q^2 to the description of $F_L$ is
investigated. This results in a significantly better description of
the reduced cross-sections, F2 and FL at low x, Q^2 and a
significantly lower $\chi^2$ for the NNLO fit as compared to the NLO
fit. This is not the case if the higher twist term is added to $F_2$.
Primary authors
Prof.
Amanda Cooper-Sarkar
(Oxford)
Prof.
Brian Foster
(Hamburg University, Oxford)
Dr
Iris Abt
(MPI)
Dr
Katarzyna Wichmann
(DESY)
Prof.
Matthew Wing
(UCL)
Mr
Volodymyr Myronenko
(DESY)
