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Study of charm production in Z decays

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>09/2000
<mark>Journal</mark>The European Physical Journal C (EPJ C) - Particles and Fields
Issue number4
Number of pages15
Pages (from-to)597-611
Publication StatusPublished
<mark>Original language</mark>English


The production rates of D∗± , D∗±s , D± , D0/D¯0 , D±s , and Λ+c/Λ¯−c in Z→cc¯ decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the D∗± is well described as the sum of three contributions: charm hadronisation, b hadron decays and gluon splitting into a pair of heavy quarks. The probability for a c quark to hadronise into a D∗+ is found to be f(c→D∗+)=0.233±0.010(stat.)±0.011(syst.) . The average fraction of the beam energy carried by D∗± mesons in Z→cc¯ events is measured to be ⟨XE(D∗±)⟩cc¯=0.4878±0.0046(stat.)±0.0061(syst.). The D∗± energy and the hemisphere mass imbalance distributions are simultaneously used to measure the fraction of hadronic Z decays in which a gluon splits to a cc¯ pair: n¯g→cc¯=(3.23±0.48(stat.)±0.53(syst.))%. The ratio of the Vector/(Vector+Pseudoscalar) production rates in charmed mesons is found to be PV=0.595±0.045 . The fractional decay width of the Z into cc¯ pairs is determined from the sum of the production rates for various weakly decaying charmed states to be Rc=0.1738±0.0047(stat.)±0.0116(syst.).