In an experiment with the 1.5 m bubble chamber at the Rutherford Laboratory, the reaction K + d→K 0 pp has been studied at beam momenta of 2.2, 2.45 and 2.7 GeV/ c . The cross section for the reaction K + n→K 0 p has been estimated and found to be approximately twice that of the line-reversed reaction K − p → K 0 n at comparable energies. An SU(3) sum rule, due to Barger and Cline, has been tested and found not to be valid in this momentum range. The differential cross section for K + n→K 0 p has also been measured and a determination made of the imaginary to real ratio of the forward amplitude, using the optical theorem. Implications of these, and other results, for various Regge models are briefly discussed.
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Results are presented on the inclusive reactions p p → K 0 X , p p → Λ X and p p → Λ X at an incident antiproton momentum of 12 GeV/ c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x , the rapidity, the transverse momentum of the V 0 and the missing mass squared. The dependence of the Λ and Λ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/ c are also made. Finally, events with two detected V 0 are analyzed in order to study correlations arising from the production of two strange neutral particles.
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The reactions p p → K ∗ (890) X , p p →Σ ± (1385) X and p p → S ∗ (993) X at 12 GeV/ c incident momentum have been studied using 19 000 events with a visible V 0 decay in BEBC. Inclusive production cross sections of these resonances as a function of transverse momentum and rapidity are presented. The contribution of annihilation to the production of the K ∗ (890) is investigated from a comparison with the corresponding pp data.
COMBINDED K*+ AND K*- DATA IN THIS TABLE.
COMBINDED K*+ AND K*- DATA IN THIS TABLE.
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We present a study of the inclusive reactions p p → K S 0 X, ΛX and Λ X at 3.6 GeV/ c based on 35.4 events/μb. The cross sections are presented in terms of the Feynman variable, rapidity and the transverse momentum. The absolute value of the Λ polarization is found to increase with increasing p T of Λ. A comparison of the inclusive productions of K S 0 in p p and e + e − is presented.
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OTHER DATA AT PLAB=5.7 AND 12. GEV/C. ALSO INCLUDED.
The photonic part of multihadronice+e− annihilation events has been analyzed at a c.m. energy of 34 GeV. The photonic energy fraction per event is determined to befγ=0.251±0.003 (stat.) ±0.04 (syste.). The neutral and charged components of the events are analyzed separately revealing close similarity in thrust axis directions and momentum distributions in agreement with the hypothesis that most photons result from π0 decay. π0's are reconstructed separately and used to determine the inclusive cross section. Comparing these cross sections with lower energy data from SPEAR we find some indication for scaling violation.
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The reaction (e+e−→μ+μ−) has been measured between\(\sqrt S= 14.0\) and\(\sqrt S= 36.4\). The total cross section result is in good agreement with the QED prediction and the following Λ values have been obtained:Λ+=186 GeV,Λ−=101 GeV. The angular distribution at high energy (\(\left( {\left. {\left\langle {\sqrt S } \right.} \right\rangle= 34.2 GeV} \right)\)) shows a fitted charge asymmetry of −0.064±0.064 in agreement with theW-S model prediction of −0.092, corresponding to an axial coupling parametera2=4ga2=0.69±0.69.
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Errors include contribution from systematics. Result based on fit(1 + cos(theta)**2 + q cos(theta)) to corrected angular distribution.
The e + e − → τ + τ − process has been measured using the CELLO detector at a mean total centre of mass energy of 34.2 GeV using essentially all the decay channels of the τ lepton. The measured cross section yields R τ =1.03±0.05 (stat)±0.07 (syst). Topological branching fraction are given for τ → 1, 3 or 5 charged tracks. The angular distribution shows a clear 1 + cos 2 θ dependance with a forward-backward asymmetry of -0.103 ± 0.052 corresponding to an axial-vector coupling a τ of the τ to the weak neutral current given by a τ =−1.12 ± 0.57.
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Forward-backward asymmetry based on 1 + (cos(theta))**2 + bcos(theta) fit for angular distribution.
Measurements of energy weighted angular correlations in electron positron annihilations at c.m. energies of 22 GeV and 34 GeV are presented.
ENERGY-ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
ENERGY-ENERGY CORRELATIONS FOR PRIMORDIAL HADRONS.
ASSYMETRY IN ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
Hadronic events obtained with the CELLO detector at PETRA were compared with first-order QCD predictions using two different models for the fragmentation of quarks and gluons, the Hoyer model and the Lund model. Both models are in reasonable agreement with the data, although they do not completely reproduce the details of many distributions. Several methods have been applied to determine the strong coupling constant α S . Although within one model the value of α S varies by 20% among the different methods, the values determined using the Lund model are 30% or more larger (depending on the method used) than the values determined with the Hoyer model. Our results using the Hoyer model are in agreement with previous results based on this approach.
DATA CORRECTED WITH HOYER MODEL (ALPHA-S=0.15).
DATA CORRECTED WITH LUND MODEL (ALPHA-S=0.25).
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Differential cross sections fore+e−→e+e−, τ+, τ- measured with the CELLO detector at\(\left\langle {\sqrt s } \right\rangle= 34.2GeV\) have been analyzed for electroweak contributions. Vector and axial vector coupling constants were obtained in a simultaneous fit to the three differential cross sections assuming a universal weak interaction for the charged leptons. The results,v2=−0.12±0.33 anda2=1.22±0.47, are in good agreement with predictions from the standardSU(2)×U(1) model for\(\sin ^2 \theta _w= 0.228\). Combining this result with neutrino-electron scattering data gives a unique axial vector dominated solution for the leptonic weak couplings. Assuming the validity of the standard model, a value of\(\sin ^2 \theta _w= 0.21_{ - 0.09}^{ + 0.14}\) is obtained for the electroweak mixing angle. Additional vector currents are not observed (C<0.031 is obtained at the 95% C.L.).
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Combined MU and TAU asymmetry. See PL 114B(1982)282 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1234> RED = 1234 </a>) and ZP C14(1982)283 (<a href=http://durpdg.dur.ac.uk/scripts/reacsearch.csh/TESTREAC/red+1245> RED = 1245 </a>) for individual asymmetry measurements.
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