Charm and beauty quark masses in the MMHT2014 global PDF analysis

TL;DR

This paper explores how varying charm and beauty quark masses affects the MMHT2014 PDFs, providing new PDF sets and analyzing data preferences for different quark mass values.

Contribution

It introduces PDF sets with varied heavy quark masses and compares their predictions to experimental data, highlighting preferences for lower masses.

Findings

Heavy quark data slightly favor lower masses than default.

PDF variations impact predictions for structure functions.

Provides PDF sets with different active quark flavors.

Abstract

We investigate the variation in the MMHT2014 PDFs when we allow the heavy quark masses $m_c$ and $m_b$ to vary away from their default values. We make PDF sets available in steps of $\Delta m_c =0.05~{\rm GeV}$ and $\Delta m_b =0.25~{\rm GeV}$, and present the variation in the PDFs and in the predictions. We examine the comparison to the HERA data on charm and beauty structure functions and note that in each case the heavy quark data, and the inclusive data, have a slight preference for lower masses than our default values. We provide PDF sets with 3 and 4 active quark flavours, as well as the standard value of 5 flavours. We use the pole mass definition of the quark masses, as in the default MMHT2014 analysis, but briefly comment on the $\overline{\rm MS}$ definition.