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A Preliminary Improved Test of the Flavor Independence of Strong Interactions (open access)

A Preliminary Improved Test of the Flavor Independence of Strong Interactions

The authors present an improved comparison of the strong couplings of gluons to light (u, d, and s), c, and b quarks, determined from multijet rates in flavor-tagged samples of hadronic Z{sup 0} decays recorded with the SLC Large Detector at the SLAC Linear Collider between 1993 and 1995. Flavor separation on the basis of lifetime and decay multiplicity differences among hadrons containing light, c, and b quarks was made using the SLD precision tracking system, yielding tags with high purity and low bias against {ge} 3-jet final states. They find: {alpha}{sub s}{sup uds}/{alpha}{sub s}{sup all} = 0.997 {+-} 0.011(stat) {+-} 0.011(syst) {+-} 0.005(theory), {alpha}{sub s}{sup c}/{alpha}{sub s}{sup all} = 0.984 {+-} 0.042 {+-} 0.053 {+-} 0.022, {alpha}{sub s}{sup b}/{alpha}{sub s}{sup all} = 1.022 {+-} 0.019 {+-} 0.023 {+-} 0.012.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
System: The UNT Digital Library
Production of {pi}{sup {+-}}, K{sup {+-}}, K{sup 0}, K*{sup 0}, {phi}, p and {Lambda}{sup 0} in Hadronic Z{sup 0} Decays (open access)

Production of {pi}{sup {+-}}, K{sup {+-}}, K{sup 0}, K*{sup 0}, {phi}, p and {Lambda}{sup 0} in Hadronic Z{sup 0} Decays

The authors have measured production rates as a function of momentum of the identified hadrons {pi}{sup +}, K{sup +}, K{sup 0}, K*{sup 0}, {phi}, p, {Lambda}{sup 0} and their antihadrons in inclusive hadronic Z{sup 0} decays, as well as separately in decays into light, c and b flavors. In addition they have compared hadron and antihadron production rates in light quark (rather than antiquark) jets. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The vertex detector was used to tag high-purity samples of light- and b-flavor events. The electron beam polarization was used to tag samples of quark and antiquark jets. Clear flavor dependences are observed, consistent with expectations based upon measured production and decay properties of heavy hadrons. They use the light-flavor results to test the predictions of MLLA QCD and of various fragmentation models. Differences between hadron and antihadron production in light quark jets are observed at high momentum fraction, providing direct evidence that higher-momentum particles are more likely to contain a primary quark or antiquark, and they use these results to make a new direct measurement of strangeness suppression in the jet fragmentation process.
Date: June 1, 1997
Creator: Abe, K.; Abe, K.; Akagi, T. & Collaboration, SLD
System: The UNT Digital Library
VXD3: The SLD Vertex Detector Upgrade Based on a 307 MPixel CCD System (open access)

VXD3: The SLD Vertex Detector Upgrade Based on a 307 MPixel CCD System

The 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.
Date: December 1995
Creator: Brau, James E.
System: The UNT Digital Library
The production of {pi}{sup {+-}}, K{sup {+-}}, p, k{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays (open access)

The production of {pi}{sup {+-}}, K{sup {+-}}, p, k{sup 0} and {Lambda}{sup 0} in hadronic Z{sup 0} decays

The authors have measured production fractions and spectra for {pi}{sup {+-}}, K{sup {+-}} and p, and production spectra for K{sup 0} and {Lambda}{sup 0} in both hadronic Z{sup 0} decays and a Z{sup 0} {yields} light quark (uds) subset at SLD. The SLD Cherenkov Ring Imaging Detector was used to identify charged hadrons. The CCD vertex detector was used to select the enriched uds sample. For the global sample, the results are consistent with previous experiments. The authors observe a clear flavor dependence in production spectra, but only a small effect in hadron fractions and {xi} = ln(1/x{sub p}) peak positions.
Date: August 1, 1995
Creator: Baird, K.
System: The UNT Digital Library