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Z{sup 0} pole direct measurements of the parity violation parameters A{sub b} and A{sub c} at SLD

Description: This report presents three different techniques used at SLD to measure directly the parity violation parameters of Zb{bar b} and Zc{bar c} couplings from the left-right forward-backward asymmetries. The results have been obtained using 150,000 hadronic Z{sup 0} decays accumulated during the 1993-95 runs with high electron beam polarization.
Date: September 1, 1996
Creator: Mancinelli, G.
Partner: UNT Libraries Government Documents Department

Updated measurement of the tau lifetime at SLD

Description: We present an updated measurement of the tau lifetime at SLD. 4316 {tau}-pair events, selected from a 150k Z{sup 0} data sample, are analyzed using three techniques: decay length, impact parameter, and impact parameter difference methods. The measurement benefits from the small and stable interaction region at the SLC and the precision CCD pixel vertex detector of the SLD. The combined result is: {tau}{sub {tau}} = 288.1 {+-} 6.1(stat) {+-} 3.3(syst) fs.
Date: July 23, 1996
Partner: UNT Libraries Government Documents Department

Design and performance of a new 307 Mpixel CCD vertex detector

Description: During the past year, the SLD Collaboration completed construction and began operation of a new vertex detector (VXD3) with 307,000,000 CCD pixels. This upgrade will improve the SLD measurement of the polarization-enhanced forward-backward asymmetry for b and c-quarks and the precision of the measurement of the b-fraction in hadronic Z decays and opens the possibility to observe B{sub s}{sup 0}-mixing. Full separation of primary, secondary and tertiary vertices is accessible.
Date: September 1, 1996
Creator: Brau, J.E. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

The endcap Cherenkov ring imaging detector at SLD

Description: The authors present the Cherenkov Ring Imaging Detector in the endcap regions of the SLD detector and report initial performance. The endcap CRID was completed and commissioned in 1993 and is fully operational for the 1994 run. First Cherenkov rings have been observed. The endcap CRID detectors and fluid systems are described and initial operational experience is discussed.
Date: May 1, 1995
Creator: Abe, K.; Hasegawa, K.; Hawegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H. et al.
Partner: UNT Libraries Government Documents Department

Hadronic Charmless B Decays at the SLD

Description: Rare decays of beauty particles were studied in several two-body exclusive hadronic charmless modes using the 19.4 pb<sup>-1</sup> Z-pole data collected with the SLD detector at SLAC from 1993 to 1998. These decays are mediated by both tree level b {yields} u and one-loop penguin b {yields} s, d transitions. Upper limits for the branching ratios are set for the investigated modes B<sub>s</sub>, B<sub>0</sub> {yields} P<sup>+</sup>P<sup>-</sup>, B<sup>+</sup> {yields} V P<sup>+</sup> and B<sub>s</sub>, B<sup>0</sup> {yields} V V , where the pseudoscalar particle P<sup>+</sup> is either {pi}<sup>+</sup> or K<sup>+</sup> and the vector particle V is either {rho}<sup>0</sup>, K<sup>* 0</sup> or {phi}. Using an event selection algorithm consisting of a set of hard cuts combined with a set of discriminator functions, the efficiencies range between 24% and 37% with near zero background.
Date: September 2, 1999
Creator: Reinertsen, Per L
Partner: UNT Libraries Government Documents Department

B Decay Studies at SLD

Description: We present three preliminary results from SLD on B decays: an inclusive search for the process b {r_arrow} s gluon, a measurement of the branching ratio for the process B {r_arrow} D{bar D}X, and measurements of the charged and neutral B lifetimes. All three measurements make use of the excellent vertexing efficiency and resolution of the CCD Vertex Detector and the first two make use of the excellent particle identification capability of the Cherenkov Ring Imaging Detector. The b {r_arrow} sg analysis searches for an enhancement of high momentum charged kaons produced in B decays. Within the context of a simple, Jetset-inspired model of b {r_arrow} sg, a limit of B(b {r_arrow} sg) &lt; 7.6% is obtained. The B(B {r_arrow} D{bar D}X) analysis reconstructs two secondary vertices and uses identified charged kaons to determine which of these came from charm decays. The result of the analysis is B(B {r_arrow} D{bar D}X) = (16.2 {+-} 1.9 {+-} 4.2)%. The results of the lifetime analysis are: {tau}{sub B{sup +}} = 1.686 {+-} 0.025 {+-} 0.042 ps, {tau}{sub B{sup 0}} = 1.589 {+-} 0.026 {+-} 0.055 ps and {tau}{sub B{sup +}}/{tau}{sub B{sup 0}} = 1.061 {+-} 0.031/0.029 {+-} 0.027.
Date: March 19, 1999
Creator: Convery, Mark R
Partner: UNT Libraries Government Documents Department

Combined SLD Measurement of Ab at the Z0 Resonance using Various Techniques

Description: We present a new preliminary combination of measurements of the parity-violation parameter A<sub>b</sub> made by the SLD collaboration using various experimental techniques. The techniques differ in detail, but in general a sample of b anti-b events is selected or enhanced by using the topologically reconstructed mass of the separated vertices formed by decaying B hadrons. The direction of the b(anti-b) quark is signed by one of four final state tags: jet charge, vertex charge, leptons, or identified K<sup>=</sup> from the b vertex. We account for statistical and systematic correlations between the four analyses to arrive at our combined result: A<sub>b</sub> = 0.905 ± 0.017(stat) ± 0.020(syst).
Date: July 27, 1999
Creator: Crawford, Glen D
Partner: UNT Libraries Government Documents Department

Current Performance of the SLD VXD3

Description: During 1996, the SLD collaboration completed construction and began operation of a new charge-coupled device (CCD) vertex detector (VXD3). Since then, its performance has been studied in detail and a new topological vertexing technique has been developed. In this paper, we discuss the design of VXD3, procedures for aligning it, and the tracking and vertexing improvements that have led to its world-record performance.
Date: September 14, 1999
Creator: Abe, Toshinori
Partner: UNT Libraries Government Documents Department

First measurement of the triple-product correlation in polarized Z{sup 0} decays to three jets

Description: We present the first measurement of the triple-product correlation in polarized Z{sup o} decays to three jets using the SLD detector at SLAC and utilizing a longitudinally polarized electron beam. The CP-even and T-odd triple product {rvec S}{sub z} {center_dot} ({rvec k}{sub 1} x {rvec k}{sub 2}) formed from the two fastest jet momenta {rvec k}{sub 1} and {rvec k}{sub 2} and the Z{sup o} polarization vector {rvec S}{sub z} is sensitive to physics beyond the Standard Model. We measure the expectation value of this quantity to be consistent with zero and set an upper limit on correlations between the Z{sup 0}-spin and the three-jet plane orientation.
Date: July 1, 1995
Partner: UNT Libraries Government Documents Department

Tau physics results from SLD

Description: Results on {tau} physics at SLD are presented. They are based on 4,316 {tau}-pair events selected from a 150 k Z{sup 0} data sample collected at the SLC. These results include measurements of the {tau} lifetime ({tau}{sub r} = 288.1 {+-} 6.1 {+-} 3.3 fs), the {tau} Michel parameters ({rho} = 0.71 {+-} 0.09 {+-} 0.04, {zeta} = 1.03 {+-} 0.36 {+-} 0.05, and {zeta}{delta} = 0.84 {+-} 0.27 {+-} 0.05), and the {tau} neutrino helicity (h{sub {nu}} = {minus}0.81 {+-} 0.18 {+-} 0.03).
Date: August 10, 1996
Creator: Daoudi, M. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

A measurement of the tau Michel parameters at SLD

Description: This thesis presents a measurement of the tau Michel parameters. This measurement utilizes the highly polarized SLC electron beam to extract these quantities directly from the measured tau decay spectra using the 1993--95 SLD sample of 4,528 tau pair events. The results are {rho}{sup e} = 0.71 {+-} 0.14 {+-} 0.05, {xi}{sup e} = 1.16 {+-} 0.52 {+-} 0.06, and ({xi}{delta}){sup e} = 0.85 {+-} 0.43 {+-} 0.08 for tau decays to electrons and {rho}{sup {mu}} = 0.54 {+-} 0.28 {sup {minus}} 0.14, {eta}{sup {mu}} = {minus}0.59 {+-} 0.82 {+-} 0.45, {xi}{sup {mu}} = 0.75 {+-} 0.50 {+-} 0.14, and ({xi}{delta}){sup {mu}} = 0.82 {+-} 0.32 {+-} 0.07 for tau decays to muons. Combining all leptonic tau decays gives {rho} = 0.72 {+-} 0.09 {+-} 0.03, {xi} = 1.05 {+-} 0.35 {+-} 0.04, and {Xi}{delta} = 0.88 {+-} 0.27 {+-} 0.04. These results agree well with the current world average and the Standard Model.
Date: May 1, 1997
Creator: Quigley, J.
Partner: UNT Libraries Government Documents Department

Measurements of AP{sub LR}, A{sub lepton} and A{sub b} from SLD

Description: We present the measurements of the leptonic asymmetries in Z{sup 0} decays measured by the SLD experiment at SLAC. A data sample of approximately 550,000 Z{sup 0} bosons are used for the preliminary measurement of A{sub LR}(A{sub e}) and the leptonic final state measurements of A{sub e}, A{sub {mu}} and A{sub {tau}}, representing the entire set of 1992-1998 SLD runs. When combining all results, a preliminary value for the effective weak mixing angle is obtained: sin{sup 2} {theta}{sub W}{sup eff} = 0.23109 {+-} 0.00029. We also present the direct measurements of A{sub b} from left-right forward-backward asymmetries, using partial data samples from 1993-1998 SLD runs. The preliminary value combines jet charge, cascade kaon and semileptonic decay analyses to obtain A{sub b} = 0.866 {+-} 0.036.
Date: March 19, 1999
Creator: Fernandez, Jorge P.
Partner: UNT Libraries Government Documents Department

Electroweak Results from the SLD Experiment

Description: We present an overview of the electroweak physics program of the SLD experiment at the Stanford Linear Accelerator Center (SLAC). A data sample of 550K Z{sup 0} decays has been collected. This experiment utilizes a highly polarized electron beam, a small interaction volume, and a very precise pixel vertex detector. It is the first experiment at a linear electron collider. We present a preliminary result for the weak mixing angle, sin{sup 2}({theta}{sub W}{sup eff}) = 0.23110 {+-} 0.00029. We also present a preliminary result for the parity violating parameter, A{sub b} = 0.898 {+-} 0.029. These measurements are used to test for physics beyond the Standard Model.
Date: May 7, 1999
Creator: Woods, Michael B
Partner: UNT Libraries Government Documents Department

The first results from the CRID detector at SLD

Description: We report first results from the initial physics run of the Cherenkov Ring Imaging Detector (CRID) in the SLD experiment at the SLC. We describe the experimental conditions, show liquid and gas rings, report the number of photoelectrons per ring, and comment on resolution.
Date: October 1, 1992
Creator: Va`vra, J.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S. et al.
Partner: UNT Libraries Government Documents Department

Measurement of the B{sup +} and B{sup 0} lifetimes from semileptonic decays at SLD

Description: The lifetimes of B{sup +} and B{sup 0} mesons have been measured using a sample of 150,000 hadronic Z{sup 0} decays collected by the SLD experiment at the SLC between 1993 and 1995. The analysis identifies the semileptonic decays of B mesons with high (p,p{sub t}) leptons and reconstructs the B meson decay length and charge by vertexing the lepton with a partially reconstructed D meson. This method results in a sample of 634 (584) charged (neutral) decays with high charge purity. A maximum likelihood fit finds: {tau}{sub B{sup +}} = 1.60{sub {minus}0.11}{sup +0.12}(stat) {+-} 0.06(syst) ps, {tau}{sub B{sup 0}} = 1.55{sub {minus}0.12}{sup +0.13}(stat) {+-} 0.09(syst) ps, and the ratio {tau}{sub B{sup +}}/{tau}{sub B{sup 0}} = 1.03{sub {minus}0.13}{sup +0.15}(stat) {+-} 0.08(syst).
Date: July 1, 1996
Partner: UNT Libraries Government Documents Department

B lifetimes and mixing with the SLD

Description: The lifetimes of B{sup 0} and B{sup {plus_minus}} mesons have been measured with the SLD detector at the SLC using topological reconstructions of the B mesons. Studies of B{sub s} mixing, using similar techniques, show that the prospects for measuring B{sub s} mixing with an upgraded vertex detector are good if x{sub x} {le} 15.
Date: December 1, 1995
Partner: UNT Libraries Government Documents Department

The scanning Compton polarimeter for the SLD experiment

Description: For the 1994/95 run of the SLD experiment at SLAC, a Compton polarimeter measured the luminosity-weighted electron beam polarization to be (77.2 {+-} 0.5)%. This excellent accuracy is achieved by measuring the rate asymmetry of Compton-scattered electrons near the kinematic endpoint. The polarimeter takes data continuously while the electron and positron beams are in collision and achieves a statistical precision of better than 1% in a three minute run. To calibrate the polarimeter and demonstrate its accuracy, many scans are frequently done. These include scans of the laser polarization, the detector position with respect to the kinematic edge, and the laser power.
Date: October 1, 1996
Creator: Woods, M. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

Measurement of time-dependent B{sub d}{degrees} - {bar B}{sub d}{degrees} mixing using inclusive semileptonic decays

Description: The time dependence of B{sub d}{sup 0} - W{sub d}{sup o} mixing has been observed in events containing high-P{sub t} leptons using a highly inclusive vertexing method to determine the B decay position. The initial state B hadron flavor was determined using the large forward-backward asymmetry provided by the highly polarized electron beam of SLC in combination with a jet charge technique. From a sample of 150,000 hadronic Z{degrees} decays observed in the SLD detector at the SLC between 1993 and 1995, a preliminary analysis of the mass difference between the two Bo mass eigenstates yields {Delta}m{sub d} = 0.520 {+-} 0.072(stat) {+-} 0.035(syst) ps{sup -1}.
Date: July 1, 1996
Partner: UNT Libraries Government Documents Department

Determination of electroweak parameters at the SLC

Description: We present an improved measurement of the left-right cross section asymmetry (A{sub LR}) for Z{sup 0} boson production by e{sup +}e{sup -} collisions. The measurement was performed at a center-of-mass energy of 91.28 GeV with the SLD detector at the SLAC Linear Collider (SLC) during the 1994-95 running period. The luminosity-weighted average polarization of the SLC electron beam during this run was measured to be (77.23 {+-} 0.52)%. Using a sample of 93,644 hadronic Z{sup 0} decays, we measure the pole asymmetry A{sub LR}{sup 0} to be 0.1512 {+-} 0.0042(stat.) {+-} 0.0011(syst.) which is equivalent to an effective weak mixing angle of sin{sup 2} {theta}{sub W}{sup eff} = 0.23100 {+-} 0.00054(stat.) {+-} 0.00014(syst.). We also present a preliminary direct measurement of the Z{sup 0}-lepton coupling asymmetries A{sub e}, A{sub {mu}}, and A{sub {tau}} extracted from the differential cross section observed in leptonic Z{sup 0} decays. We combine these results with our previous A{sub LR} measurement to obtain a combined determination of the weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.23061 {+-} 0.00047.
Date: September 1, 1996
Creator: Torrence, E.
Partner: UNT Libraries Government Documents Department

Production of {pi}{sup {plus_minus}}, K{sup {plus_minus}}, p, K{sup 0}{sub s}, {Lambda}{sup 0}, K{sup *0} and {phi} in Hadronic Z{sup 0} Decays

Description: Production rates and momentum distributions have been measured for {pi}{sup {+-}}, K{sup {+-}}, p, K{sup 0}{sub s}, {Lambda}{sup 0}, K{sup *0} and {phi} in 150,000 hadronic Z{sup 0} decays recorded by the SLD detector at the SLD collider at SLAC. The analysis uses the SLD Cerenkov Ring Imaging Detector (CRID) for clean and efficient identification of charged tracks and significant background reduction. In addition, K{sup *0} production has been studied in quark and anti-quark jet samples, which were identified by their electroweak forward backward asymmetries using the SLD high electron beam polarization. A difference between the two samples is observed in the K{sup *0} rate at high momentum, consistent with leading particle and strangeness suppression hypotheses.
Date: August 1, 1996
Creator: Dima, Mihai & Collaboration, SLD
Partner: UNT Libraries Government Documents Department

The SLD VXD3 detector and its initial performance

Description: The SLD collaboration completed construction of a new CCD vertex detector (VXD3) in January 1996 and started data taking in April 1996 with the new system. VXD3 is an upgrade of the original CCD vertex detector, VXD2, which had successfully operated in SLD for three years. VXD3 consists of 96 large area CCDs, each having 3.2 million 20 microns x20 microns pixels. By reducing the detector material and lengthening the lever arm, VXD3 is expected to improve secondary vertex resolution by about a factor of two compared with VXD2. The new three layered structure enables stand alone tracking without any ambiguity and its extended size along the beam direction improves the polar angle coverage to COS THETA {lt}0.85. An overview of this detector system and its initial performance are described.
Date: June 1, 1996
Creator: Suekane, F. & Group, SLD /VXD3
Partner: UNT Libraries Government Documents Department

B physics at SLD

Description: The authors review recent B physics results obtained in polarized e{sup +}e{sup {minus}} interactions at the SLC by the SLD experiment. The excellent 3-D vertexing capabilities of SLD are exploited to extract precise B{sup +} and B{sub d}{sup 0} lifetimes, as well as measurements of the time evolution of B{sub d}{sup 0} - ({anti B}{sub d}{sup 0}) mixing.
Date: June 1, 1997
Creator: Willocq, S. & Collaboration, SLD
Partner: UNT Libraries Government Documents Department