Experimental physics

The European Physical Journal C - Particles and Fields

, Volume 12, Issue 2, pp 225-241

First online:

Measurements of the Z partial decay width into \(c\bar c\) and multiplicity of charm quarks per b decay

  • The DELPHI Collaboration
  • , P. Abreu et al.Affiliated withLIP, IST, FCUL - Av. Elias Garcia, 14-1° 1000 Lisboa Codex, Portugal

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The partial decay width \(R_c\) of the Z into \(c\bar c\) quark pair and the number of charm quarks \(n_c\) per b decay are measured with the DELPHI detector at LEP 1. Particle identification provides clear \(D^0\), \(D^+\), \(D_s^+\) and \(\Lambda_c^+\) signatures. The charm hadron production rate is measured in each channel by a fit to the scaled energy, impact parameter information and the invariant mass spectrum. Two measurements of \(R_c\) are presented, from the \(D^{*+}\) production rate and from the overall charm counting, including strange charm baryon production, in \(c\bar c\) events. The multiplicity \(n_c\), which includes hidden \(c\bar c\) and strange charm baryon production, is inferred from the charm counting in \(b\bar{b}\) events. The final results are \(R_c = 0.1665 \pm 0.0095\) and \(n_c = 1.166 \pm 0.086\).