Study of charm production in Z decays

• Main Authors: BARATE, R., THULASIDAS, M.
• Format: text
• Language: English
• Published: Institutional Knowledge at Singapore Management University 2000
• Subjects: Computer Sciences; Databases and Information Systems
• Online Access: https://ink.library.smu.edu.sg/sis_research/5860; https://ink.library.smu.edu.sg/context/sis_research/article/6863/viewcontent/arXiv_hep_ex_9909032v1_20_Sep_1999.pdf
• Institution: Singapore Management University

The production rates of D∗±D∗±, D∗±sDs∗±, D±D±, D0/D¯0D0/D¯0, D±sDs±, and Λ+c/Λ¯−cΛc+/Λ¯c− in Z→cc¯Z→cc¯ decays are measured using the LEP I data sample recorded by the ALEPH detector. The fractional energy spectrum of the D∗±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∗+D∗+ is found to be f(c→D∗+)=0.233±0.010(stat.)±0.011(syst.)f(c→D∗+)=0.233±0.010(stat.)±0.011(syst.). The average fraction of the beam energy carried by D∗±D∗± mesons in Z→cc¯Z→cc¯ events is measured to be ⟨XE(D∗±)⟩cc¯=0.4878±0.0046(stat.)±0.0061(syst.).⟨XE(D∗±)⟩cc¯=0.4878±0.0046(stat.)±0.0061(syst.). The D∗±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¯cc¯ pair: n¯g→cc¯=(3.23±0.48(stat.)±0.53(syst.))%.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±0.045PV=0.595±0.045. The fractional decay width of the Z into cc¯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.).