Study of the fragmentation of b quarks into B mesons at the Z peak

TL;DR

This paper investigates how b quarks fragment into B mesons at the Z peak using ALEPH data, measuring energy distributions and comparing them with theoretical models to improve understanding of quark fragmentation processes.

Contribution

It provides a model-independent measurement of B meson energy distribution at the Z peak using a semi-exclusive reconstruction method.

Findings

Measured mean B meson energy fraction: 0.716 ± 0.006 (stat) ± 0.006 (syst).

Reconstructed energy spectra are compared with various fragmentation models.

Results help refine theoretical models of b quark fragmentation.

Abstract

The fragmentation of b quarks into B mesons is studied with four million hadronic Z decays collected by the ALEPH experiment during the years 1991-1995. A semi-exclusive reconstruction of B->l nu D(*) decays is performed, by combining lepton candidates with fully reconstructed D(*) mesons while the neutrino energy is estimated from the missing energy of the event. The mean value of xewd, the energy of the weakly-decaying B meson normalised to the beam energy, is found to be mxewd = 0.716 +- 0.006 (stat) +- 0.006 (syst) using a model-independent method; the corresponding value for the energy of the leading B meson is mxel = 0.736 +- 0.006 (stat) +- 0.006 (syst). The reconstructed spectra are compared with different fragmentation models.