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No description provided.
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We present a measurement of the left-right cross-section asymmetry (ALR) for Z boson production by e+e- collisions. The measurement includes the final data taken with the SLD detector at the SLAC Linear Collider (SLC) during the period 1996-1998. Using a sample of 383,487 Z decays collected during the 1996-1998 runs we measure the pole-value of the asymmetry, ALR0, to be 0.15056+-0.00239 which is equivalent to an effective weak mixing angle of sin2th(eff) = 0.23107+-0.00030. Our result for the complete 1992-1998 dataset comprising 537 thousand Z decays is sin2th(eff) = 0.23097+-0.00027.
The observed, corrected asymmetry measurement using the 1997-98 data sets.
The observed, corrected asymmetry measurement using the 1996 data sets.
The pole asymmetry for the 1997-98 data sets.
The differential cross sections and density matrix elements for the φ and ϱ 0 mesons have been measured in the reactions K − p → K − K + ( Λ , Σ 0 ) and K − p → π − π + ( Λ , Σ 0 ) at 13 GeV using a wire chamber spectrometer. The analysis shows that while the vector meson production is dominated by the natural parity exchange amplitude, some unnatural parity exchange is also required. Furthermore the φ and ϱ natural exchange cross sections are identical in shape and have the 2:1 relative strength expected in the quark model with K ∗ and K ∗∗ exchange degeneracy. The analysis of the clear peak-dip ϱ 0 − ω interference pattern observed in the π − π + data indicates that the ω production is in phase with the ϱ and of similar magnitude. Both the S ∗ and f′ meson are clearly observed in this experiment. The S ∗ data are found to be consistent with S ∗ parameters deduced from ππ scattering analyses. The f′ density matrix elements and a new limit of the f′ → π − π + branching ratio are presented.
No description provided.
CROSS SECTIONS CORRECTED FOR EVENTS OUTSIDE THE PHI MASS CUT. <T-CHANNEL>.
CROSS SECTIONS CORRECTED FOR EVENTS OUTSIDE THE PHI MASS CUT. <S-CHANNEL>.
Large samples of inclusively produced Ξ−, Ω−, and Ξ0(1530) events are presented from a 1427 events/μb exposure of the large-aperture superconducting-solenoid spectrometer to an 11-GeV/c K− beam. Production characteristics of these states are compared with other data and shown to be consistent with hyperon exchange. Polarization of Ξ− shows an increase in magnitude with both Feynman x and transverse momentum. The Ξ− decay parameters are measured to be αΞ=-0.40±0.03 and ΦΞ=(5±10)° . Results of searches for higher-mass hyperons are presented. The Ξ−(1820)→Ξ0(1530)π− decay is observed, while we fail to confirm the existence of the Σ+(3170).
No description provided.
No description provided.
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The results of a wire chamber spectrometer experiment studying K ∗ (890) production in the reaction K − p→ K − π + n at 13 GeV are presented. Strong forward structure is observed for | t |< m 2 π in the s -channel density matrix elements and differential cross section. These features are similar to those observed in π − p→ϱ 0 n data and are characteristics of π exchange. In contrast in the intermediate, | t | ∼ 0.2 GeV 2 , and large momentum transfer regions K ∗ (890) production is demonstrated by the natural parity ϱ−A 2 exchange contribution.
No description provided.
The logarithmic slope of the differentical cross section for K ± p elastic scattering at 10 and 14 GeV, and for π ± p and p ± p at 10GeV has been measured. Rich structure is observed in the forward slope for all processes, which is well accounted for by the properties of a peripheral exchange amplitude for the nonexotic reactions, and by a peripheral component of the diffractive amplitude as clearly seen in the exotic processes, K ± p and pp.
GRAPH OF D(SIG)/DT.
SLOPE AS A FUNCTION OF T.
Differential cross sections in the t -range between 0.02 and 1.5 GeV 2 have been measured for the elastic scattering of particles and antiparticles on protons at 6.4, 10.4 and 14 GeV for K ± p and 10.4 GeV for π ± p and p ± p . Large statistics have been achieved and systematic uncertainties have been minimized. The relative systematic uncertainty between particle and antiparticle data is less than 0.5%. Accurate measurements of the position of the first crossover between particle and antiparticle differential cross sections have been performed. As the energy increases from 6.4 to 14 GeV the K ± p crossover moves to smaller values by 0.010 GeV 2 with a statistical error of 0.006 GeV 2 and a systematic uncertainty of 0.005 GeV 2 . The crossover positions at 10.4 GeV for π ± , K ± and p ± scale approximately with the interaction radii.
CROSSOVER POSITION IS -T = 0.209 +- 0.004 (DSYS = 0.003) GEV**2.
CROSSOVER POSITION IS -T = 0.209 +- 0.004 (DSYS = 0.003) GEV**2. SMALL ANGLE CROSS SECTIONS IN SMALLER T-BINS.
CROSSOVER POSITION IS -T = 0.211 +- 0.004 (DSYS = 0.0025) GEV**2.
The cross sections for the line-reversed reaction pairs K+n→K0p and K−p→K¯0n, and K+p→K0Δ++ and K−n→K¯0Δ− have been determined with high statistics and good relative normalization at 8.36 and 12.8 GeV/c in a spectrometer experiment at Stanford Linear Accelerator Center. The cross sections for the K+-induced reactions are larger than for the K−, contrary to the expectations of weakly-exchange-degenerate Regge-pole models. The ratio of the reaction cross sections is about the same as at lower energies and shows little change with momentum transfer.
Axis error includes +- 11/11 contribution.
Axis error includes +- 11/11 contribution.
Axis error includes +- 11/11 contribution.
The momentum transfer (t′) dependence of the JP=1+K*π and ρK partial waves in the K±π+π− system is presented. The production of the Q1 meson (m∼1300 MeV), which has a large ρK decay mode, obeys approximate s-channel helicity conservation. In contrast the production of the Q2 meson (m∼1400 MeV), which decays predominantly to K*π, satisfies approximate t-channel helicity conservation. Furthermore the Q1 production distributions are virtually identical, whereas the Q2± distributions exhibit a distinct cross-over for |t′|∼0.18 GeV2.
No description provided.
We have developed a new technique for inclusive reconstruction of the energy of B hadrons. The excellent efficiency and resolution of this technique allow us to make the most precise determination of the b-quark fragmentation function, using e+e- -> Z0 decays recorded in the SLD experiment at SLAC. We compared our measurement with the predictions of a number of fragmentation models. We excluded several of these models and measured the average scaled energy of weakly-decaying B hadrons to be <x_B>=0.714+-0.005(stat)+-0.007(syst) +-0.002(model dependence).
Unfolded distribution of weakly decaying scaled B-hadron enery with statistical errors only.
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