D Meson Production in e+e- Annihilation [Thesis]
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., CA (United States)
The production of D mesons in e+e- annihilation for the center-of-mass energy range 3.7 to 7.0 GeV has been studied with the MARK I magnetic detector at the Stanford Positron Electron Accelerating Ring facility. We observed a resonance in the total cross-section for hadron production in e+e- annihilation at an energy just above the threshold for charm production. This resonance, which we name ψ", has a mass of 3772 ± 6 MeV/c2, a partial width to electron pairs of 345 ± 85 eV/c2, and decays almost exclusively into $$D\overline{D}$$ pairs. The ψ" provides a rich source of background-free and kinematically well defined D mesons for study. From the study of D mesons produced in the decay of the ψ" we have determined the masses of the Do and D+ mesons to be 1863.3 ± 0.9 MeV/c2 and 1868.3 ± 0.9 MeV/c2 respectively. we also determined the branching fraction for Do to K-π+, K-oπ+π- and K-π+π-π+ to be (2.2 ± 0.6)%, (4.0 ± 1.3)%, and (3.2 ± 1.1)% and the branching fractions for D+ decay to K-oπ+ and K-π+π+ to be (1.5 ± 0.6)% and (3.9 ± 1.0)%. The average number of kaons per D decay was found to be 0.52 ± 0.14 Ko's and 0.42 ± 0.12 K+'s. The rate for inclusive production of D mesons at center-of-mass energies above the ψ" has been measured; we find that it can account for most, if not all, of the observed increase in the total hadronic cross-section for center-of-mass energies above 4 GeV. The inclusive momentum and energy spectra for D's have been measured at the highest available center-of-mass energy (7 GeV). The energy spectra are rapidly decreasing functions of energy with a slope similar to the slope of the charged pion spectrum at the same center-of-mass energy. This behaviour suggests that the fragmentation function of the charmed quark into charmed mesons is a decreasing function of the scaling variable z = 2ED/ECM.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1453963
- Report Number(s):
- SLAC-R-220; SLAC-220
- Country of Publication:
- United States
- Language:
- English
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