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HERAPDF fits including $F_2$(charm) data

A M Cooper-Sarkar

TL;DR

This work extends the HERAPDF1.0 framework by incorporating the combined HERA $F_2$(charm) data and exploring multiple heavy-quark schemes and charm masses. It demonstrates that the charm data are highly sensitive to $m_c$ and to the treatment of heavy quarks, leading to scheme- and mass-dependent shifts in the gluon and sea quark PDFs. These PDF variations propagate to LHC predictions for $W$ and $Z$ cross sections, highlighting an important source of theoretical uncertainty and guiding future refinements of heavy-quark schemes in PDF analyses.

Abstract

PDF fits in the HERAPDF1.0 formalism have been made to the combined HERA-I inclusive data and the newly combined $F_2$(charm) data from the H1 and ZEUS experiments. The charm data are found to be sensitive to the value of the charm mass and the choice of the heavy quark scheme. This has consequences for the predictions of $W$ and $Z$ cross sections at the LHC.

HERAPDF fits including $F_2$(charm) data

TL;DR

This work extends the HERAPDF1.0 framework by incorporating the combined HERA (charm) data and exploring multiple heavy-quark schemes and charm masses. It demonstrates that the charm data are highly sensitive to and to the treatment of heavy quarks, leading to scheme- and mass-dependent shifts in the gluon and sea quark PDFs. These PDF variations propagate to LHC predictions for and cross sections, highlighting an important source of theoretical uncertainty and guiding future refinements of heavy-quark schemes in PDF analyses.

Abstract

PDF fits in the HERAPDF1.0 formalism have been made to the combined HERA-I inclusive data and the newly combined (charm) data from the H1 and ZEUS experiments. The charm data are found to be sensitive to the value of the charm mass and the choice of the heavy quark scheme. This has consequences for the predictions of and cross sections at the LHC.

Paper Structure

This paper contains 3 sections, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. HERAPDF Fits including $F_2$(charm) data
  3. Summary and Discussion

Figures (4)

  • Figure 1: Left: comparison of $F_2$(charm) data to a PDF fit which includes these data for $m_c=1.4$ and $1.65~$GeV, using the standard RT-VFN scheme. Right: the PDFs which correspond to these two fits.
  • Figure 2: Left: comparison of $F_2$(charm) data to a PDF fit which includes these data for $m_c=1.4$ and $1.65~$GeV, using the optimized RT-VFN scheme. Right: the PDFs which correspond to these two fits.
  • Figure 3: Left: PDFs corresponding to the ACOT scheme fit for $m_c=1.4$ and $1.65~$GeV. Right: PDFs corresponding to the FFN scheme fit for $m_c=1.4$ and $1.65~$GeV.
  • Figure 4: Comparison of $F_2$(charm data) to a PDF fit which includes these data for $m_c=1.4$ and $1.65~$GeV, using the standard RT-VFN scheme at NNLO and $\alpha_s=0.1145$.