학술논문
A precise measurement of the pseudoscalar decay constant fDs using charm-tagged events in the electron-positron collisions at the upsilon(4S).
Document Type
Theses
Author
Source
Dissertation Abstracts International; Dissertation Abstract International; 67-05B.
Subject
Language
English
Abstract
Summary: Measurement of the pseudoscalar decay constant fDs of the charm strange meson D+s is a benchmark test of the theoretical methods, foremost lattice QCD, that quantitatively describe the non-perturbative low-energy regime of QCD. From 1999 through 2004, the BABAR experiment, at the PEP-II storage ring at the Stanford Linear Accelerator Center, collected 230.2 fb -1 of data in e+e - collision at s = 10.58 GeV. In this thesis, a sample of 510,000 charmed mesons arising from e+e- → cc¯ events is identified, and the decay D*+s → gD+s gammamu+nu is searched for in the recoil. A total of 489 +/- 55 decays are detected. In the same charm-tagged sample 2093 +/- 99 events containing the decay D*+s → gD+s → gamma&phis;pi+ are isolated, yielding the ratio of the partial widths: Gamma( D+s → mu+numu)/Gamma( D+s → &phis;pi+) = 0.143 +/- 0.018stat +/- 0.006sys. Using B ( D+s → &phis;pi+) = (4.81 +/- 0.64) %, the branching fraction B ( D+s → mu+numu) = (6.65+/-0.81 stat+/-0.25sys+/-0.88norm) %, and the pseudoscalar decay constant fDs = (281 +/-17stat +/- 6sys +/- 19norm) MeV are calculated. These measurements are comparable in precision with the world average. In combination with fD (CLEO-c), good agreement with lattice QCD calculations is found: ( fDs /fD)/( fDs /fD)lattice = 1.01 +/- 0.11.