The mixed spin-spin correlation parameter Cσσ≈0.5CSS−0.8CSL for np elastic scattering was measured for incident-neutron-beam kinetic energies of 484, 634, and 788 MeV over the center-of-mass angular range 75°-180°. These Cσσ data are important for determining the I=0 nucleon-nucleon amplitudes and provide strong constraints on the phase-shift solutions. It was found that the P11, S13, and D13 isospin-0 partial waves are most strongly affected.
Mixed spin parameter POL.POL(NAME=CXX) is given by 0.475 * CSS + 0.088 CNN + 0.1390 CLL - 0.744 CSL.
Mixed spin parameter POL.POL(NAME=CXX) is given by 0.506 * CSS + 0.064 CNN + 0.163 CLL - 0.809 CSL.
Mixed spin parameter POL.POL(NAME=CXX) is given by 0.528 * CSS + 0.050 CNN + 0.178 CLL - 0.824 CSL.
The high antiproton-proton luminosity obtained by using a target system consisting of a hydrogen gas-jet crossing a coasting beam of cooled antiproton circulating in one of the rings of CERN's ISR provides the possibility to measure low cross section reactions with very high precision. We present measurements of the antiproton-proton elastic cross section at 90° CM at incident momenta between 3.5 GeV/ c and 5.7 GeV/ c . The precision of these measurements is much higher than previously reported results. The data show that the cross section of this reaction decreases faster than s −12 over this momentum range.
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43 EVENTS WITH LAMBDA, 54 EVENTS WITH KS.
43 EVENTS WITH LAMBDA, 54 EVENTS WITH KS.
43 EVENTS WITH LAMBDA, 54 EVENTS WITH KS. D(N)/D(P) WAS FITTED BY P**2*EXP(-SLOPE*EKIN).
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The production of Λ 's and Ξ − 's in proton-antiproton collisions at 200 and 900 GeV c.m. energy has been studied using decays observed in the UA5 streamer chambers. The results are compared to previously published 546 GeV data, to results from other experiments, and to four theoretical models. The Λ yield per inelastic event is estimated to be 0.42±0.11 at 200 GeV and 0.66±0.14 at 900 GeV. We find a mean number of Ξ − 's per inelastic collision of 0.03 −0.02 +0.04 at 200 GeV and 0.06 −0.03 +0.05 at 900 GeV. The average transverse momentum of Λ's in the rapidity region | y |⩽2 is found to be 0.80 −0.14 +0.20 GeV/ c at 200 GeV and 0.74±0.09 GeV/ c at 900 GeV. The average transverse momentum of Ξ − 's in the rapidity region | y |⩽3 is estimated to be 0.8 −0.2 +0.4 GeV/ c at 200 GeV and 0.7 −0.1 +0.2 GeV/ c at 900 GeV which is lower than the unexpectedly high value of 1.1±0.2 GeV/ c measured at 546 GeV. The ratio of Ξ − production to Λ production in the region | y |⩽2, p t >1 GeV/ c is 0.07 −0.04 +0.08 at 900 GeV. This value is consistent with the ratio found in e + e − collisions and lower energy pp collisions but lower than the value obtained at 546 GeV. The average particle composition of events at 200 and 900 GeV, estimated using UA5 data, is presented.
Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
Corrected lambda transverse momentum distributions. Numerical values supplied by F. Lotse. Data at 546 GeV are taken from an earlier publication - Phys. Rep. 154 (87) 247.
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NUCLEUS IS NUCLEAR PHOTOEMULSION. EVENT WITH A TOTAL CHARGE OF ALL SPECTATOR FRAGMENTS OF A PROJECTILE = 0.
NUCLEUS IS NUCLEAR PHOTOEMULSION. EVENT WITH A TOTAL CHARGET OF ALL SPECTATOR FRAGMENTS OF A PROJECTILE = 1.
NUCLEUS IS NUCLEAR PHOTOEMULSION.
We have measured dijet angular distributions at √s =1.8 TeV with the Collider Detector at Fermilab and the Tevatron p¯p Collider and find agreement with leading-order QCD. By comparing the distribution for the highest dijet invariant masses with the prediction of a model of quark compositeness, we set a lower limit on the associated scale parameter Λc at 330 GeV (95% C.L.).
Numerical values read from figure in preprint.
Production rates of multijet hadronic final states are studied ine+e− annihilation at 29 GeV center of mass energy. QCD shower model calculations with exact first order matrix element weighting at the first gluon vertex are capable of reproducing the observed multijet event rates over a large range of jet pair masses. The method used to reconstruct jets is well suited for directly comparing experimental jet rates with parton rates calculated in perturbative QCD. Evidence for the energy dependene of αs is obtained by comparing the observed production rates of 3-jet events with results of similar studies performed at higher center of mass energies.
Observed production rates relative to the total hadronic cross section.
Production rates corrected for fragmentation, initial state radiation and detector effects.
The reaction e + e − → τ + τ − has been studied at centre of mass energies between 14.0 and 46.8 GeV with the CELLO detector at the PETRA e + e − collider. We present results for the cross section σ τ and the charge asymmetry A τ . The results are in good agreement with the standard model. We have also measured the topological decay rates BR 1 , BR 3 and BR 5 for the inclusive decay of the τ lepton into one, three and five charge particles. The results confirm and improve earlier CELLO measurements at other energies. We find for the combined values at all energies BR 1 = (84.9 ± 0.4 ± 0.3)%, BR 3 = (15.0 ± 0.4 ± 0.3)% and BR 5 = (0.16 ± 0.13 ± 0.04)%.
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Corrected for radiative effects and background contributions.
Fermilab experiment 711 has investigated proton-nucleus collisions in which two high-transverse-momentum hadrons are produced forming high-mass ++, +-, and -- charged states, using an 800-GeV/c proton beam on targets of beryllium, aluminum, iron, and tungsten. Our data cover the range in dihadron mass from 6 to 15 GeV/c2. We show here that the dependence of the cross section on atomic weight A can be parametrized as Aα where α=1.043±0.011(stat)±0.025 (syst), and is independent of the charge state of the dihadron system.
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