Production of φ mesons in e+e− annihilation at a center-of-mass energy of 29 GeV has been observed with the time-projection chamber detector at the PEP storage ring. The φ production rate has been measured in the energy range 0.075<x<0.55 (x=2Eφs), giving 0.077±0.012(stat)±0.016(syst) φ's per event. The average value of pt2 relative to the thrust axis is 1.0±0.4 (GeV/c)2.
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EXTRAPOLAATION TO ALL X USES LUND MONTE CARLO PREDICTIONS.
ERRORS ARE BOTH STATISTICAL AND SYSTEMATIC. PT IS MEASURED RELATIVE TO THE EVENT THRUST AXIS, AND IS FOUND TO HAVE A MEAN VALUE OF 1.0 +- 0.4 GEV.
Invariant cross sections for hadron production (π±,K±,p and\(\bar p\)) by protons off C, Al, Cu, Sn and Pb nuclei have been measured at 70 GeV for theP∧ range from 1 up to 4.65 GeV/c. TheA-dependence of the invariant cross section is not described by the exponentialAα(P∧), which points to the presence of secondary hadron absorption in nuclei.
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We measured the cross sections of hadron pair production (π, K, p) with symmetric momenta produced back-to-back in the c.m.s. in pp collisions in the range 0.45 ⩽ P T ⩽ 1.99 GeV/ c . Particle correlations showing dependence on quantum numbers and transverse momentum are presented. The data are discussed in the framework of parton models.
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The deep-inelastic electron-scattering cross sections per nucleon σA for D, He, Be, C, A1, Ca, Fe, Ag, and Au were measured in the kinematic range 0.09<~x<~0.9 and 2<~Q2<~15 (GeV/c)2 with use of electrons with energies ranging from 8 to 24.5 GeV. The ratio σAσD is consistent with unity in the range 0.1<x<0.3. For 0.3<x<0.8, the ratio decreases logarithmically with atomic weight A, or linearly with average nuclear density. No Q2 dependence in the ratio was observed over the kinematic range of the data.
THESE RATIOS ARE AVERAGED OVER Q**2.
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Data are presented on elastic πp and Kp scattering for values of −t up to 2.5 and 3.5 (GeV/c)2 at incident momenta of 100 and 200 GeV/c, respectively. All of the cross sections are found to be nearly identical, although there is some momentum dependence of the π+p data; a small systematic difference observed between pion and kaon data cannot be explained by geometrical scaling.
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The reaction π−p→K0K−p has been measured from 50 to 175 GeV/c. The production characteristics of the A2 have been analyzed. We find spin and t dependence similar to lower energies, but the cross section falls rapidly with energy. In a Regge description of π−p→A2−p our data imply a rather small Pomeron-exchange component.
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RAW CROSS SECTION WITHIN MASS CUTS.
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TheΞ-p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.01<−<0.42(GeV/c)2, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)−2 at 102 GeV/c and 8.2 ±0.5(GeV/c)−2 at 135 GeV/c. The corresponding total elastic cross sections areσel=4.9±0.7 mb andσel=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.
NUMERICAL VALUES OF DATA SUPPLIED BY P.ROSSELET.
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