STUDIES OF B QUARK PRODUCTION IN ELECTRON-POSITRON ANNIHILATION AT SQRT.S = 29 GEV

CHI-WAI RAY NG, Purdue University

Abstract

This thesis reports studies of the heavy quark system produced in $e\sp{+}e\sp{-}$ annihilation. Semileptonic decays of heavy quarks were isolated by selecting events with electrons of high transverse momentum with respect to the jet axis. The semileptonic branching ratios of b and c quarks are measured to be (10.8 $\pm$ 0.8)% and (7.6 $\pm$ 1.1)% respectively. The forward-backward electroweak asymmetry of the b quark has been measured to be $A\sb{b}$ = $-(14$ $\pm$ 12)%, consistent with the Standard Model prediction. The lifetime of B hadrons extracted from this sample is determined to be $\tau\sb{B}$ = 1.02 $\pm$ $\sbsp{0.37}{0.41}$ ps. The constraint on the magnitude of the Kobayashi-Maskawa matrix element $V\sb{bc}$ is found to be 0.042 $\pm$ $\sbsp{0.006}{0.010}$. These measurements were made using a large data sample of 300 $pb\sp{-1}$ accumulated with the High Resolution Spectrometer (HRS) at the PEP $e\sp{+}e\sp{-}$ storage ring, operated at a center-of-mass energy, $\sqrt s$, of 29 GeV.

Degree

Ph.D.

Subject Area

Particle physics

COinS