Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e + e − annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e + e − → D or D + anything) at 7 GeV is 4.8±1.3 nb.
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SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
We present measurements of the cross section for inclusive D and K meson production in e + e − annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e + e − annihilation at energies above 4 GeV.
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The elastic and topological p¯p cross sections have been measured at 48.9 GeV/c in the Fermilab proportional-wire-chamber-30-in.-bubble-chamber hybrid spectrometer. The elastic cross section is 7.81±0.24 mb and the slope of the elastic differential cross section at t=0 is 13.4±0.8 GeV−2. Further, the moments of the inelastic topological-cross-section distribution are 〈nc〉=5.69±0.03, 〈nc〉D=2.10±0.02, and f2cc=1.67±0.12.
Axis error includes +- 0.0/0.0 contribution (?////DALITZ PAIRS. VEES AND GAMMA CONVERSIONS NEAR THE VERTEX WERE DETERMINED TO BE NEGLIGIBLE. LOW -T ELASTIC EVENTS//ODD-PRONG EVENTS APPARANTLY NOT CAUSED BY SECONDARY INTERACTIONS WERE MOVED TO THE NEXT HIGHER MULTIPLICITY ON THE ASSUMPTION THAT A SHORT TRACK WAS NOTVISIBLETOTAL AP-P CROSS SECTION OF 43.86+-0.25 MB FROM A.S.CARROL ET AL.PRL 33, 928(1974) WAS USED FOR NORMALIZATION).
Axis error includes +- 0.0/0.0 contribution (?////DALITZ PAIRS. VEES AND GAMMA CONVERSIONS NEAR THE VERTEX WERE DETERMINED TO BE NEGLIGIBLE. LOW -T ELASTIC EVENTS//ODD-PRONG EVENTS APPARANTLY NOT CAUSED BY SECONDARY INTERACTIONS WERE MOVED TO THE NEXT HIGHER MULTIPLICITY ON THE ASSUMPTION THAT A SHORT TRACK WAS NOTVISIBLETOTAL AP-P CROSS SECTION OF 43.86+-0.25 MB FROM A.S.CARROL ET AL.PRL 33, 928(1974) WAS USED FOR NORMALIZATION).
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Inclusive distributions are presented for final-state π0 and η0 mesons produced in γp interactions. For photon energies from 50 to 130 GeV, both cross sections scale for fractional momenta xF>~0.30. The average transverse momentum for both mesons is approximately constant with energy and equal to 0.51±0.05 GeV/c at large xF. The η0π0 ratio similarly rises from 0.07±0.03 at xF=0.38 to 0.30±0.09 at xF=0.90. The π0 distributions are in good agreement with those seen in the scattering of highly virtual incident photons.
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Using data from the Fermilab fixed target experiment E665, general properties of forward produced charged hadrons in μp interactions at a primary muon energy of 470 GeV are investigated. The normalized inclusive singleparticle distributions for Feynman-x D(xF ) and for the transverse momentum D(p2t , xF ) are measured as a function of W and Q2. The dependence of the average transverse momentum squared 〈p2t〉 on xF , W and Q2 is studied. The increasing contribution from diffractive production as Q2 decreases leads to a reduction of the average charged hadron multiplicities at low (positive) xF and an enhancement at large xF , for Q2 ≲ 10 GeV2. It also reduces 〈p2t〉 for Q2 ≲ 5 GeV2 and 0.4 ≲ xF < 1.0.
Normalised inclusive single particle distributions of charged hadrons for all events in W intervals. Additional systematic uncertainty of 4 PCT.
Normalised inclusive single particle distributions of charged hadrons for all events in Q**2 intervals. Additional systematic uncertainty of 4 PCT.
Normalised inclusive single particle distributions of charged hadrons for all events in X (Bjorken) intervals. Additional systematic uncertainty of 4 PCT.
We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 0.7 < Q^2 < 20 GeV^2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets. Our measured g2 approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d2p and d2n are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x->0. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range. The absolute value of A2 is significantly smaller than the sqrt[R(1+A1)/2] limit.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 2.75 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 5.5 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
Values of A2 and X*G2 from proton and deuterium target data at mean electron scattering angle of 10.5 degrees and incident energy 29.1 GeV. Errors shown are statistical only.
We present measurements of the total production rates and momentum distributions of the charmed baryon $\Lambda_c^+$ in $e^+e^- \to$ hadrons at a center-of-mass energy of 10.54 GeV and in $\Upsilon(4S)$ decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in $e^+e^- \to c\bar{c}$ events, allowing direct studies of $c$-quark fragmentation. We measure a momentum distribution for $\Lambda_c^+$ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of $\left< x_p \right> = 0.574\pm$0.009 and a total rate of $N_{\Lambda c}^{q\bar{q}} = 0.057\pm$0.002(exp.)$\pm$0.015(BF) $\Lambda_c^+$ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, $pK^-\pi^+$. In $\Upsilon (4S)$ decays we measure a total rate of $N_{\Lambda c}^{\Upsilon} = 0.091\pm$0.006(exp.)$\pm$0.024(BF) per $\Upsilon(4S)$ decay, and find a much softer momentum distribution than expected from B decays into a $\Lambda_c^+$ plus an antinucleon and one to three pions.
LAMBDA/C+ differential production rate per hadronic event for the continuum at cm energy 10.54 GeV.
The integrated number of LAMBDA/C+'s per hadronic event for the continuum at cm energy 10.54 GeV.
LAMBDA/C+ differential production rate per UPSILON(4S) decay at cm energy 10.58 GeV.
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