Doubly-tagged Ds decays at 4.03 GeV

Citation

Prabhakar, Ernest N. (1995) Doubly-tagged Ds decays at 4.03 GeV. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/2ja4-ts17. https://resolver.caltech.edu/CaltechETD:etd-10122007-082523

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

The [...] is a pseudoscalar meson composed of two second generation quarks, the heavy charm and the light strange. The bulk of our knowledge of the [...] comes from secondary production via B decays. These experiments have high statistics but are poorly suited to absolute branching fraction or production cross-section measurements. The best way to perform those is to use double-tagging of threshold pair production. Unfortunately, there is no strong resonance near [...] threshold, making it difficult to obtain sufficient statistics.

This thesis makes use of the [...] integrated luminosity collected by the Beijing Spectrometer from the Beijing Electron-Positron Collider at 4.03 GeV. This energy was chosen because the coupled-channel model of Eichten et al. predicts an enhancement there of the [...] cross section to somewhat below 1 nb. We attempt to fully reconstruct hadronic and semileptonic [...] pairs from six-prong events not containing any photons. We combine the [...] from kinematic fitting and particle identification to form a single value, the joint confidence level, for each event.

Using this in the analysis yields five hadronic events, with multiple combinations per event. Since the [...] principally decays to resonant moves, we preferentially select those combinations which lead to resonant two-body masses. This gives us a signal containing 7 resonant decays and 3 non-resonant [...] decays. We use Monte Carlo efficiencies and knowledge of the ratio [...] to estimate the production rates represented by these tags.

We perform a likelihood analysis using those numbers, together with the absolute branching fractions, to obtain a value of [...] one sigma below the coupled channel model. Using only relative [...] branching fractions, we fit to a value for the ratio [...] This is within one sigma of the current world average, and differs [...] noticeably from the model of Bauer, Stech, and Wirbel value of [...]

Thesis Files