We have determined the strong coupling αs from measurements of jet rates in hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. Using six collinear and infrared safe jet algorithms we compared our data with the predictions of QCD calculated up to second order in perturbation theory, and also with resummed calculations. We find αs(MZ2)=0.118±0.002(stat)±0.003(syst)±0.010(theory), where the dominant uncertainty is from uncalculated higher order contributions.
The second systematic error comes from the theoretical uncertainties.
We present a new determination of the nonsinglet structure function ${\mathit{F}}_{2}^{\mathit{p}}$ - ${\mathit{F}}_{2}^{\mathit{n}}$ at ${\mathit{Q}}^{2}$=4 ${\mathrm{GeV}}^{2}$ using recently measured values of ${\mathit{F}}_{2}^{\mathit{d}}$ and ${\mathit{F}}_{2}^{\mathit{n}}$/${\mathit{F}}_{2}^{\mathit{p}}$. A new evaluation of the Gottfried sum is given, which remains below the simple quark-parton model value of 1/3.
Errors of F2(D) are the estimated total uncertainties and those on the ratio and difference are statistical only.
Values of the Gottfried Sum Rule integral (GS) defined as the integral between X(C=MIN) and X = 0.8 of (F2(P)-F2(N))DX/X.
No description provided.
Antiproton-proton elastic scattering was measured at c.m.s. energies √s =546 and 1800 GeV in the range of four-momentum transfer squared 0.025<-t<0.29 GeV2. The data are well described by the exponential form ebt with a slope b=15.28±0.58 (16.98±0.25) GeV−2 at √s =546 (1800) GeV. The elastic scattering cross sections are, respectively, σel=12.87±0.30 and 19.70±0.85 mb.
Final results (systematic errors included).
Final results (systematic errors included).
Statistical errors only. Data supplied by S. Belforte.
We report a measurement of the proton-antiproton total cross section σT at c.m.s. energies √s =546 and 1800 GeV. Using the luminosity-independent method, we find σT=61.26±0.93 mb at √s =546 GeV and 80.03±2.24 mb at √s =1800 GeV. In this energy range, the ratio σel/σT increases from 0.210±0.002 to 0.246±0.004.
No description provided.
Assuming RHO = 0.15.
Fermilab Experiment-665 measured deep-inelastic scattering of 490 GeV muons off deuterium and xenon targets. Events were selected with a range of energy exchange ν from 100 GeV to 500 GeV and with large ranges of Q2 and xBj: 0.1 GeV2/c2<Q2<150 GeV2/c2 and 0.001<xBj<0.5. The fractional energy (z) distributions of forward-produced hadrons from the two targets have been compared as a function of the kinematics of the scattering; specifically, the kinematic region of ‘‘shadowing’’ has been compared to that of nonshadowing. The dependence of the distributions upon the order of the hadrons, determined by the fractional energies, has been examined as well; a strong degree of similarity has been observed in the shapes of the distributions of the different order hadrons. These z distributions, however, show no nuclear dependence, even in the kinematic region of shadowing.
Showing effect of shadowing in the ratios of cross sections.
Showing effect of shadowing in the ratios of cross sections.
Showing effect of shadowing in the ratios of cross sections.
We report a measurement of the diffraction dissociation differential cross section d2σSD/dM2dt for p¯p→p¯X at √s =546 and 1800 GeV, M2/s<0.2 and 0≤-t≤0.4 GeV2. Our results are compared to theoretical predictions and to extrapolations from experimental results at lower energies.
Single diffraction dissociation cross section.
Results on the production of charged hadrons in muon-deuteron and muon-xenon interactions are presented. The data were taken with the E665 spectrometer, which was exposed to the 490 GeV muon beam of the Tevatron at Fermilab. The use of a streamer chamber as vertex detector provides nearly 4π acceptance for charged particles. The μD data are compared with the μXe data in terms of multiplicity distributions, average multiplicities, forward-backward multiplicity correlations, rapidity and transverse momentum distributions and of two-particle rapidity correlations of charged hadrons. The data cover a range of invariant hadronic massesW from 8 to 30 GeV.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-deuteron scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial function fit to the multiplicity distribution of charged hadrons in muon-xenon scattering. DISPERSION = SQRT(1/MULT + 1/K) is this dispersion of the scaled multiplicity Z = N/MULT.
Results of negative binomial fits to charged hadron multiplicity distributions in muon-deuteron interactions for backward and forward hemispheres of the hadronic cm.
This paper presents our first measurement of the F 2 structure function in neutral-current, deep inelastic scattering using the ZEUS detector at HERA, the ep colliding beam facility at DESY. The data correspond to an integrated luminosity of 24.7 nb −1 . Results are presented for data in range of Q 2 from 10 GeV 2 to 4700 GeV 2 and Bjorken x down to 3.0 × 10 −4 . The F 2 structure function increases rapidly as x decreases.
No description provided.
No description provided.
No description provided.
Multistrange baryon and antibaryon production is suggested to be a useful probe in the search for Quark-Gluon Plasma formation. We report the detection of an Ω − + Ω − signal in central S + W interactions at 200 A GeV/c and measure the ratio Ω − Ω − = 0.57±0.41 at central rapidity and p T >1.6 GeV/ c .
Note that this ratio is uncorrected for possible differences in the acceptance and efficiency for omega- and omegabar+ detection.
Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.
Data supplied by V. Paolone.
Cross section data using Bethe-Heitler event normalization.
Cross section data using the Beam Gamma Monitor normalization.
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