25,164 research outputs found
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B physics at SLD
No full textThe 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
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SLD liquid argon calorimeter
No full textThe liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z{sup 0} decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z{sup 0} events) is discussed
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VXD3: The SLD vertex detector upgrade based on a 307 Mpixel CCD system
No full textThe SLD Collaboration is building a new CCD vertex detector (VXD3) comprising 96 3.2 Mpixel CCDs of 13 cm{sup 2} each for a total of 307 million pixels. This system is an upgrade of the Pioneering CCD vertex detector VXD2 which has operated in SLD since 1992. The CCDs of VXD3 are mounted on beryllium ladders in three cylinders, providing three space point measurements along each track of about 5 microns resolution in all three coordinates. The design and construction of VXD3 builds on three years of successful performance of VXD2. Significant improvements are achieved with VXD3 in impact parameters resolution (about a factor of two) and acceptance ({approximately}20%) through optimized geometry and reduced material. New readout electronics have been developed for this system. This new vertex detector will be installed in late 1995 for the future runs of SLD
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Physics at the Z pole with SLD
No full textThe authors review recent results from a wide physics program in polarized e{sup +}e{sup {minus}} interactions at the SLC performed by the SLD experiment. Unique and precise measurements of the electroweak parameters A{sub e}, A{sub b}, A{sub c}, and R{sub b} provide valuable constraints on the Standard Model. The excellent 3-D vertexing capabilities of SLD are further 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. Finally, the unique capabilities of the SLC/SLD are used to test QCD in new ways. The authors present results on general properties of particle production in light, c, and b quark events, as well as the first observation of leading particle production in light-quark hemispheres
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Highlights of SLD physics
No full textThe SLAC polarized electron beam allows the SLD experiment a high-precision measurement of sin{sup 2}{theta}{sub W}{sup eff} using the parity violating cross section asymmetry A{sub LR} at the e{sup +}e{sup {minus}} {yields} Z{sup o} vertex. The SLD also uses the small luminous e{sup +}e{sup {minus}} collision region and CCD vertex detector to tag heavy quark final states for probing the Z{sup o} {yields} q{bar q} vertex. Results are presented on the following selected topics: A{sub LR}, the Z{sup o} {yields} the Z{sup o} {yields} b{bar b} branching fraction R{sub b}, and the parity violating cross section asymmetries A{sub b} and A{sub b} and A{sub c} for the Z{sup o} {yields} b{bar b} and Z{sup o} {yields} b{bar b} and Z{sup o} {yields} c{bar c} final states
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Measurement of R{sub b} at SLD
No full textWe report a new measurement of Rb using a double tag technique where the b selection is based on topological reconstruction of the mass of the B-decay vertex. The measurement was performed using a sample of 150k hadronic Zo events collected with the SLD at the SLAC Linear Collider during the years 1993-1995. The method utilizes the 3-D vertexing abilities of the SLD CCD pixel vertex detector and the small stable SLC beams to obtain a high b tagging efficiency of 37% for a purity of 97.2%. The high purity reduces the systematics introduced by charm contamination and correlations with Rc. We obtain a result of Rb = 0.2176 +/- 0.0033stat. +/- 0.0017syst. +/- 0.0008Rc
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Tau physics results from SLD
No full textResults 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)
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Status of A{sub LR} measurement at SLD
No full textThe SLD Collaboration is making a precision measurement of the left-right asymmetry (A{sub LR}) at the SLAC Linear Collider, exploiting the significantly improved luminosity and the high electron-beam polarization of over 60%. General features of the polarized source and polarimetry are described. The experimental method is briefly presented, together with the preliminary values of the raw asymmetry, which should lead to a precision in the measurement of sin{sup 2}{theta}{sub W}{sup eff} of {plus_minus}0.0008 {plus_minus} 0.0005. The collaboration is preparing a proposal for an extended run for one million Z{sup o}s with improved polarimetry to reach an ultimate level of {delta} sin{sup 2} {theta}{sub W}{sup eff} = {plus_minus}0.00025
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Electroweak coupling measurements from polarized Bhabha scattering at SLD
No full textThe cross section for Bhabah scattering (e{sup +}e{sup {minus}} {yields} e{sup +}e{sup {minus}}) with polarized electrons at the center of mass energy of the Z{sup 0} resonance has been measured with the SLD experiment at the SLAC Linear Collider (SLC) during the 1992--1993 runs. The first measurement of the left-right asymmetry in Bhabah scattering (A{sub LR}{sup e+}e{sup {minus}} ({theta})) is presented. From A{sub LR}{sup e+}{sup {minus}} ({Theta}) the effective weak mixing angle is measured to be sin{sup 2}{theta}{sub W}{sup eff} = 0.2245{plus_minus}0.0010. When combined with the measurement of A{sub LR}, the effective electron couplings are measured to be v{sub e} = {minus}0.0414{plus_minus}0.0020 and a{sub e} = {minus}0.4977{plus_minus}0.0045
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VXD3: The SLD Vertex Detector Upgrade Based on a 307 MPixel CCD System
No full textThe SLD upgrade CCD vertex detector (VXD3) is described. Its 307 million pixels are assembled from 96 3.2 Mpixel CCDs of 13 cm{sup 2} each. The system has evolved from the pioneering CCD vertex detector VXD2, which has operated in SLD since 1992. The CCDs of VXD3 are mounted on beryllium ladders in three cylinders, providing three space point measurements along each track of about 5 microns resolution in all three co-ordinates. Significant improvements are achieved with VXD3 in impact parameter resolution (about a factor of two) and acceptance ({approximately}20%) through optimized geometry and reduced material. New readout electronics have been developed for this system
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