Massless Parton Asymptotics within Variable Flavour Number Schemes

TL;DR

This paper examines the theoretical uncertainties in high Q^2 deep inelastic heavy quark production due to variations in the charm input scale within variable flavour number schemes, proposing methods for scale optimization and stability analysis.

Contribution

It identifies the charm input scale as a significant source of uncertainty and suggests scale optimization to improve the reliability of heavy quark production calculations.

Findings

Q_0 variations cause substantial theoretical uncertainties.

Scale optimization can reduce uncertainties.

Comparison of fixed order and resummed series enhances stability analysis.

Abstract

In this note we formulate and investigate theoretical uncertainties for high Q^2 deep inelastic heavy quark (charm, etc.) production rates which arise within collinear resummation techniques from variations of the a priori unknown charm input scale Q_0 of O(alpha_s) variable flavour number schemes. We show that Q_0 variations constitute a source of considerable theoretical uncertainty of present O(alpha_s) calculations within such schemes and we suggest to consider a scale optimization from higher order corrections. We also outline how the stability of the fixed order and collinearly resummed perturbation series for heavy quark production can be comparatively investigated by variation of Q_0.