Specific Features of Heavy Quark Production. LPHD approach to heavy particle spectra

TL;DR

The paper develops a perturbative QCD LPHD framework to describe heavy-quark jet energy spectra, explicitly incorporating heavy-quark mass effects, Sudakov resummation, and two-loop corrections through a radiator formalism. It introduces a physical, infrared-finite coupling $a_{ ext{eff}}$ to absorb higher-order contributions and threshold effects, enabling a robust determination of QCD parameters such as $ar{ ext{MS}}(M_Z)$ and the low-momentum integral of the coupling. By confronting charm and bottom energy losses with data, it extracts $ar{ ext{MS}}(M_Z) \, ext{approximately }0.125$ and an infrared integral $ar{A}(2 ext{ GeV}) \, ext{approximately }0.18$, supporting universality of the effective coupling in inclusive heavy-quark spectra. The work also connects PT predictions to hadronization via LPHD, comparing with Peterson fragmentation and showing a near-model-independent description of energy losses, with implications for heavy-flavour measurements at colliders. Overall, it provides a perturbative path to quantify confinement effects in heavy-quark production and to extract fundamental QCD parameters from jet observables.

Abstract

Perturbative QCD formula for inclusive energy spectra of heavy quarks from heavy quark initiated jets which takes into account collinear and/or soft logarithms in all orders, the exact first order result and two-loop effects is applied to distributions of heavy flavoured hadrons in the framework of the LPHD concept. Fits to experimentally measured charm and bottom mean energy losses result in $α_{\MSbar}(M_Z)=0.125\pm 0.003\pm 0.004$ and $(2\GeV)^{-1}\int_0^{2\GeV} dk α_s^{eff}(k)= 0.18\pm 0.01\pm 0.02$ with $α_s^{eff}$ an infrared finite effective QCD coupling.