Title

Establishment of Bs meson production at the psi(5S) energy using beauty and charm decays

Date of Award

2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Advisor(s)

Sheldon Stone

Keywords

Meson production, Beauty, Charm, Psi(5S)

Subject Categories

Physical Sciences and Mathematics | Physics

Abstract

The Υ(5S) resonance has long been thought to be a source of B s mesons, since it is massive enough to produce B s B s pairs. In this work, we establish the presence of B s mesons at the Υ(5S) energy and measure its production rate using both beauty and charm decays. We use all the e + e - collision data collected by the CLEO III detector at the Υ(5S) and at the Υ(4S) resonance energies. This data consists of 0.423 fb -1 on the Υ(5S) resonance, 6.34 fb -1 on the Υ(4S) and 2.32 fb -1 in the continuum below the Υ(4S). We also use 281 pb -1 data accumulated with the CLEO-c detector on the ψ (3770) resonance and another 195 pb -1 taken in the region near 4170 MeV center-of-mass energy.

In the first analysis, we measure the asymmetry of D s meson production in Υ(4S) and Υ(5S) decays as [Special characters omitted.] (Υ(5 S ) [arrow right] D s X )/[Special characters omitted.] (Υ(4S) [arrow right] D s X ) = (2:5 ± [Special characters omitted.] ). We take advantage of this asymmetry, which is due to the difference of B and B s meson production in the decays of the two resonances, to establish B s meson production in Υ(5S) decays and measure its fraction, f s , as (16:8±[Special characters omitted.] )% using a theoretical estimate of (92±11)% for the inclusive branching ratio [Special characters omitted.] ( B s [arrow right] D s X ). We also show the dependence of this measurement on the [Special characters omitted.] [arrow right] [straight phi]π + branching fraction.

Knowledge of the B s production rate at the Υ(5S) resonance is imperative for B s studies at the Υ(5S) using current B -factories, and for future e + e - Super- B Factories. We show in the second part of this work that the determination of f s in a model independent manner requires several tens of fb -1 . We present a method that provides a measurement of f s using the relative rates of like-sign versus opposite sign dileptons; the like-sign leptons result from B 0 and B s mixing. In addition, we show that determining the rates of single, double and triple [Special characters omitted.] mesons provides an alternative way of finding f s .

To constrain our knowledge of B s production at the Υ(5S) by making other measurements with other model dependencies, we examine CLEO-c data for other particle species than D s , that are produced with much higher rate in B s meson decays than in B meson decays. Such particle like η, η' and [straight phi], with their ss quark composition, are expected to be enhanced in D s than in D meson decays. We therefore measure the inclusive branching fractions of charm mesons, namely D 0 , D + and [Special characters omitted.] , into η X , η' X , and [straight phi] X decays. We find that the rates from [Special characters omitted.] are much larger than from D 0 and D + .

We use the inclusive [straight phi] meson yields which is higher by one order of magnitude in D s than in D decays to make a second measurement of [Special characters omitted.] (Υ(5 S ) [arrow right] [Special characters omitted.] ) using our model estimate of [Special characters omitted.] ( B s [arrow right] [straight phi] X ). We measure [Special characters omitted.] (Υ(5 S ) [arrow right] [straight phi] X ) = (13:8 ± [Special characters omitted.] )% and [Special characters omitted.] (Υ(4 S ) [arrow right] [straight phi] X ) = (7:1 ± 0:1 ± 0:6)%, the ratio of the two rates is (1:9 ± [Special characters omitted.] ). This is the first measurement of the [straight phi] meson yield from the Υ(5S). We measure f s = (24:6±[Special characters omitted.] )% and we also report on the total Υ(5 S ) hadronic cross section above continuum to be σ( e + e - Υ(5 S )) = (0:301 ± 0:002 ± 0:039) nb. This allows us to extract the fraction of B mesons as (58:9 ± 10:0 ± 9:2)%, equal to 1- f s . Averaging the three methods gives a model dependent result of f s = ([Special characters omitted.] )%.

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