Download or read book Preliminary Measurement of the Charged Multiplicities in B C and Light Quark Events from Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z[sup 0] decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities:[anti n][sub uds]= 20.21[+-] 0.10 (stat.)[+-] 0.17 (syst.), [anti n][sub c]= 21.28[+-] 0.46 (stat.)[sub -0.33][sup+0.38] (syst.) and[anti n][sub b]= 23.14[+-] 0.10 (stat.)[sub -0.34][sup+0.35] (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events:[Delta][anti n][sub c]= 1.07[+-] 0.47 (stat.)[sub -0.30][sup+0.36] (syst.) and[Delta][anti n][sub b]= 2.93[+-] 0.14 (stat.)[sub -0.29][sup+0.30] (syst.). We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.

Download or read book Preliminary Measurement of the Charged Multiplicities in B C and Light Quark Events from Z Decays written by and published by . This book was released on 1996 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z° decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities: {anti n}{sub uds} = 20.21 ± 0.10 (stat.) ± 0.17 (syst.), {anti n}{sub c} = 21.28 ± 0.46 (stat.){sub -0.33}{sup +0.38} (syst.) and {anti n}{sub b} = 23.14 ± 0.10 (stat.){sub -0.34}{sup +0.35} (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: [Delta]{anti n}{sub c} = 1.07 ± 0.47 (stat.){sub -0.30}{sup +0.36} (syst.) and [Delta]{anti n}{sub b} = 2.93 ± 0.14 (stat.){sub -0.29}{sup +0.30} (syst.). We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.

Download or read book Measurement of the Charged Multiplicities of B C and Light Quark Events from Z sup 0 Decays written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately for[ital b, c] and light quark ([ital u, d, s]) events from Z[sup 0] decays at SLD. Impact parameters of charged tracks were used to select enriched samples of[ital b] and light quark events. We measured the charged multiplicities:[bar[ital n]][sub[ital uds]]= 19.80[+-] 0.09 ([ital stat])[+-] 0.57 ([ital syst]), [bar[ital n]][sub[ital c]]= 21.17[+-] 0.44 ([ital stat])[+-] 1.01 ([ital syst]) and[bar[ital n]][sub[ital b]][+-]23.14[+-] 0.09 ([ital stat])[+-] 1.03 ([ital syst]) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of[ital c] or[ital b] quark events and light quark events:[delta][bar[ital n]][sub[ital c]]= 1.37[+-] 0.45 ([ital stat])[+-] 0.86 ([ital syst]) and[delta][bar[ital n]][sub[ital b]]= 3.34[+-] 0. 13 ([ital stat])[+-] 0.77 ([ital syst]) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.

Download or read book Measurement of the Charged Multiplicities of B C and Light Quark Events from Z Decays written by and published by . This book was released on 1995 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Average charged multiplicities have been measured separately for {ital b, c} and light quark ({ital u, d, s}) events from Z° decays at SLD. Impact parameters of charged tracks were used to select enriched samples of {ital b} and light quark events. We measured the charged multiplicities: {bar {ital n}}{sub {ital uds}} = 19.80 ± 0.09 ({ital stat}) ± 0.57 ({ital syst}), {bar {ital n}}{sub {ital c}} = 21.17 ± 0.44 ({ital stat}) ± 1.01 ({ital syst}) and {bar {ital n}}{sub {ital b}}±23.14 ± 0.09 ({ital stat}) ± 1.03 ({ital syst}) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of {ital c} or {ital b} quark events and light quark events: [delta]{bar {ital n}}{sub {ital c}} = 1.37 ± 0.45 ({ital stat}) ± 0.86 ({ital syst}) and [delta]{bar {ital n}}{sub {ital b}} = 3.34 ± 0. 13 ({ital stat}) ± 0.77 ({ital syst}) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.

Download or read book A Measurement of the Z Sup 0 Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at E Sub Cm written by and published by . This book was released on 1992 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays,?{bar n}{sub b} = 2.11 {plus minus} 1.82(stat) {plus minus} 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 {plus minus} 1.82 (stat) {plus minus} 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 {plus minus} 1.82 (stat) {plus minus} 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.

Download or read book Preliminary Measurement of Leading Particle Effects in Hadronic Z Decays written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present preliminary evidence for leading particle production in hadronic decays of the Z° to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and [Lambda]/{bar {Lambda}} are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z° decay. Similarly, more high momentum K− that K are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K{sup {+-}} are produced predominantly in s{bar s} events rather than {ital u}{bar {ital u}} events.

Download or read book A Measurement of the Z Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at E sub Cm written by and published by . This book was released on 1992 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays, [delta]{bar n}{sub b} = 2.11 ± 1.82(stat) ± 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 ± 1.82 (stat) ± 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 ± 1.82 (stat) ± 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.

Download or read book Identified Hadron Production and Light Quark Fragmentation in Z sup 0 Decays written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the differential cross sections for the production of[pi][sup+], K[sup+], K[sup 0], K*[sup 0], [phi], p, [Lambda] and their corresponding antiparticles in separate samples of flavor-tagged Z[sup 0][yields] light-flavor (u[bar u], d[bar d], or s[bar s]), Z[sup 0][yields] b[bar b] events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of A[sub s], the parity-violating coupling of the Z[sup 0] to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. Our preliminary result is A[sub s]= 0.82[+-] 0.10(stat.)[+-] 0.07(syst.).

Download or read book A Preliminary Direct Measurement of the Parity Violating Coupling of the Z sup 0 to Strange Quarks A sub S written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a preliminary direct measurement of the parity violating coupling of the Z[sup 0] to strange quarks, A[sub s], derived from a sample of approximately 300,000 hadronic decays of Z[sup 0] produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1997. Z[sup 0][r-arrow] s[bar s] events are tagged by the presence in each event hemisphere of a high-momentum K[sup[+-]], K[sub s][sup 0] or[Lambda][sup 0]/[bar[Lambda]][sup 0] identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial strange quark. The coupling A[sub s] is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged strange quark. To reduce the model dependence of the measurement, the background from primary up and down events is measured from the data, as is the analyzing power of the method for primary strange events. We measure: A[sub s]= 0.82[+-] 0.10(stat.)[+-] 0.08(syst.)(preliminary).

Download or read book Measurement of the Charged Multiplicity of Bottom and Light Quark Events in E E Annihilation at s written by and published by . This book was released on 1997 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Charged Multiplicity of Z B bar B Events written by and published by . This book was released on 1994 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using an impact parameter tag to select an enriched sample of Z° --> b{bar b} events, the authors have measured the difference between the average charged multiplicity of Z° --> b{bar b} and Z° --> hadrons to be {bar n}{sub b} - {bar n}{sub had} = 2.24 " 0.30(stat.) " 0.33(syst.) tracks per event. From this, they have derived {bar n}{sub b} - {bar n}{sub uds} = 3.31 " 0.41 " 0.79. Comparing this measurement with those at lower center-of-mass energies, the authors find no evidence that {bar n}{sub b} - {bar n}{sub uds} depends on energy, in agreement with a precise prediction of perturbative QCD.

Download or read book A Measurement of the Z0 Hadronic Branching Fraction to Bottom Quarks and the Charged Multiplicity of Bottom Quark Events Using Precision Vertex Detectors at Ecm written by Dale Steven Koetke and published by . This book was released on 1992 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Preliminary Direct Measurement of the Parity Violating Coupling of the Z to Strange Quarks A sub S written by and published by . This book was released on 1999 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a preliminary direct measurement of the parity violating coupling of the Z° to strange quarks, A{sub s}, derived from a sample of approximately 300,000 hadronic decays of Z° produced with a polarized electron beam and recorded by the SLD experiment at SLAC between 1993 and 1997. Z° → s{bar s} events are tagged by the presence in each event hemisphere of a high-momentum K{sup ±}, K{sub s}° or [Lambda]°/{bar {Lambda}}° identified using the Cherenkov Ring Imaging Detector and/or a mass tag. The CCD vertex detector is used to suppress the background from heavy flavor events. The strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial strange quark. The coupling A{sub s} is obtained directly from a measurement of the left-right-forward-backward production asymmetry in polar angle of the tagged strange quark. To reduce the model dependence of the measurement, the background from primary up and down events is measured from the data, as is the analyzing power of the method for primary strange events. We measure: A{sub s} = 0.82 ± 0.10(stat.) {+-} 0.08(syst.)(preliminary).

Download or read book Search for the Production of ZW and ZZ Boson Pairs Decaying Into Charged Leptons and Jets in Proton antiproton Collisions at Sqrt s written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9 fb(̂-1) of integrated luminosity. We increase the sensitivity to vector boson decays into pairs of quarks using a neural network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be 2.5 +2.0 -1.0 pb (

Download or read book Identified Hadron Production and Light Quark Fragmentation in Z Decays written by and published by . This book was released on 1998 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the differential cross sections for the production of [pi], K, K°, K*°, [phi], p, [Lambda] and their corresponding antiparticles in separate samples of flavor-tagged Z° 2!light-flavor (u{bar u}, d{bar d}, or s{bar s}), Z° 2!b{bar b} events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of A{sub s}, the parity-violating coupling of the Z° to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. Our preliminary result is A{sub s} = 0.82 ± 0.10(stat.) ± 0.07(syst.).

Download or read book Properties of Leading Particles in Hadronic Z Decays written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors present studies of leading particle production in Z° decays into light, c, and b quarks performed with the SLD experiment at SLAC. The SLD precision vertex detector was exploited to tag light-flavor events, to tag charmed meson vertices and separate the prompt and B-decay components, and to reconstruct B-hadrons partially. The relative production of prompt pseudoscalar and vector D-mesons was measured to be P{sub V} = 0.53 " 0.06(stat.) " 0.02(syst.) (preliminary). The shape of the B-hadron energy spectrum was found to be consistent with the predictions of a number of models, and the average energy fraction was measured to be x{sub E} = 0.697 " 0.012(stat.) " 0.028(syst.) (preliminary). Separation of light quark and antiquark jets was achieved using the highly polarized SLC electron beam, and hadrons were identified using the SLD Cherenkov Ring Imaging Detector. Production of particles and antiparticles in quark jets was compared, allowing the first direct observation of leading particles in ee− --> u{anti u}, d{anti d}, s{anti s} events. More high momentum baryons and K−'s than antibaryons and K's were observed, providing evidence for leading baryon and kaon production, as well as for strangeness suppression at high momentum.

Download or read book Measurement of the Running B quark Mass Using E sup e sup yields B bar B g Events written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the determination of the running b-quark mass, m[sub b](M[sub Z]), using Z[sup 0] decays into 3 or more hadronic jets. We calculated the ratio of[ge] 3-jet fractions in e[sup+]e[sup -][yields] b[bar b] vs. e[sup+]e[sup -][yields] q[sub l][bar q][sub l] (q[sub l]= u or d or s) events at next-to-leading order in perturbative QCD using six different infra-red- and collinear-safe jet-finding algorithms. We compared with corresponding measurements from the SLD Collaboration and found a significant algorithm-dependence of the fitted m[sub b](M[sub Z]) value. Our best estimate, taking correlations into account, is m[sub b](M[sub Z])= 2.52[+-] 0.27(stat.)[sub -0.47][sup+0.33](syst.)[sub -1.46][sup+0.54](theor.) GeV/c[sup 2].