Heavy quark mass effects in charged-current deep-inelastic scattering at approximate NNLO in the Aivazis-Collins-Olness-Tung scheme

Abstract

The approximate SACOT-$\ddot{I}‡$ scheme for heavy quark production in deep-inelastic scattering was initially formulated for the neutral current structure functions $F_2$ and $F_L$. We extend this approach to the charged current case (also including $F_3$), and thereby complete the definitions for the most relevant inclusive structure functions. Furthermore, we implement these structure functions in the open-source code $\text{APFEL++}$ which provides fast numerical evaluations over a wide kinematic range; this addition to the $\text{APFEL++}$ code is publicly available, with details provided in the appendix. This SACOT-$\ddot{I}‡$ implementation enables, for the first time, detailed numerical insights on the mass dependence of the structure functions and cross sections in the $(x,Q^2)$-plane for both neutral and charged current processes. We consider kinematic regions relevant for the experimental measurements from fixed-target $\hat{I}½$DIS experiments (NuTeV, CCFR and Chorus) and HERA, and also projections for the upcoming EIC. In particular, the $\hat{I}½$DIS experiments reveal a surprisingly strong dependence on the mass effects, offering valuable insights that may help resolve long-standing challenges in accurately describing these datasets.

22 pages, 4 appendices, 12 figures, 2 tables, matches published version