Elements of the spin density matrix for W bosons in e+e- -> W+W- -> qqln events are measured from data recorded by the OPAL detector at LEP. This information is used calculate polarised differential cross-sections and to search for CP-violating effects. Results are presented for W bosons produced in e+e- collisions with centre-of-mass energies between 183 GeV and 209 GeV. The average fraction of W bosons that are longitudinally polarised is found to be (23.9 +- 2.1 +- 1.1)% compared to a Standard Model prediction of (23.9 +- 0.1)%. All results are consistent with CP conservation.
The fraction of longitudinal polarization for leptonically and hadronically decaying W bosons. The average values for all the centre of mass energies and for both lepton and hadron decay combined are also given.
The luminosity weighted average over all the centre of mass energies of the diagonal elements of the RHO++ and RHO-- SDM as a function of the cosine of the angle of the W- boson for the leptonic decay channel.
The luminosity weighted average over all the centre of mass energies of the diagonal element of the RHO00 SDM as a function of the cosine of the angle of the W- boson for both leptonic and hadronic decay channels, and combined.
Results are presented for the quasi two-body hypercharge exchange reactions of the type using data from a high statistics bubble chamber experiment. Total and differential cross sections and the momentum transfer dependence of the meson and hyperon resonance single density matrix elements are discussed. Amplitude analyses are performed for the first two reactions. The results are compared with quark model and duality predictions and with those from other related reactions.
No description provided.
No description provided.
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We present results of an analysis of two-prong events for elastic scattering and single-pion production in K−p interactions at 5.5 GeVc. The resonance parameters for the charged and neutral K*(890) and K*(1420) are determined and the observed production and decay properties of the charged and neutral K*(890) are compared with the theoretical predictions of an absorptive one-particle-exchange model and a Regge model. The K*(1420) differential cross section and density-matrix elements are presented and the question of whether more than one resonance exists in this mass range is considered. A search for resonance effects at Kπ mass beyond 1500 MeV is made. In particular, the recently reported state at 1800 MeV is discussed. A B5-model analysis of the reaction K−p→K¯0π−p is also presented.
NORMALIZED TO SIG(K- P --> ANYTHING) OF 24.3 +- 0.8 MB.
FORWARD CROSS SECTION OPTICAL POINT FROM TWO PARAMETER EXPONENTIAL FIT OVER 0.12 < -T < 0.68 GEV**2.
No description provided.
The reactions of positive pions with protons yielding four charged particles and one or more neutrals have been studied, especially the reaction π+p→Δ++ω0→pπ+π+π−π0. The results presented in this paper were obtained from a 100 000-picture exposure of the Argonne-MURA 30-in. liquid hydrogen bubble chamber, with a beam of incident pions of 4.09−GeVc momentum. Comparisons have been made with corresponding results of other experiments at various incident beam momenta, and with the predictions of some theoretical models of the π+p interaction.
INCLUDING CORRECTIONS FOR BACKGROUND.
No description provided.
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The results presented in this paper are obtained from an analysis of bubble-chamber pictures of K−d interactions at an incident K− momentum of 5.5 GeV/c. Generally, the quasitwo-body final states are produced peripherally, with a small backward peak occurring in some of the final states. The final states Σ−ω, Σ−ρ0, and Σ−φ appear to be produced primarily by vector-meson exchange. In the final state Λ(1520)π− the decay distributions of the Λ(1520) hyperon are found to be consistent with a vector-exchagne production process with M2 coupling at the nucleon vertex. The predictions of the independent-quark model and of other symmetry schemes, namely that the forward cross sections for Σ−ρ0, Σ−ω, Σ−φ production be in the ratios 1: 1: 2, are not inconsistent with our experimental values.
No description provided.
FRACTIONAL FORWARD HYPERON CROSS SECTION AFTER BACKGROUND SUBTRACTION.
No description provided.
New data for the reaction π+p→η0Δ++ are presented at 11 momenta between 1.28 and 2.67 GeV/c. Existing data at higher momenta are included in an analysis of the reaction in terms of A2 exchange. An effective trajectory parametrization of the data above 2 GeV/c is shown to describe adequately those data, although it yields an effective trajectory steeper than expected from ρ−A2 exchange degeneracy. An existing Regge-pole model is refitted to the data above 2 GeV/c with generally satisfactory results. Both the effective trajectory parametrization and the Regge model are extrapolated to the lower-momenta data and shown to give remarkably good agreement with the data. Evidence is presented against a dominant contribution to the lower-momenta data from s-channel resonances.
BACKGROUND SUBTRACTED ONLY ABOVE 1.67 GEV/C.
NOT CORRECTED FOR BACKGROUND - MINIMAL DISTORTION EXPECTED. NORMALIZED TO INTEGRATED CROSS SECTION.
ISOTROPIC FIT JACKSON FRAME DENSITY MATRIX ELEMENTS.
This report concerns itself with the study of four- or five-body final states produced by the interaction of 4.48-GeV/c K− mesons on neutrons. The data result from a 372 000-picture exposure in the Argonne National Laboratory 30-in. deuterium-filled bubble chamber. The reactions studied include (1) K−n→Λπ+π−π−, (2) K−n→Σ0π+π−π−, (3) K−n→Λπ+π−π−π0, (4) K−n→Λπ+π−π−MM, (5) K−n→Λπ−K+K−, and (6) K−n→Λπ−KL0KS0, where all the Λ particles decayed visibly. Evidence is presented for the existence of the Σ(1640) whose mass and width are 1642 ± 12 MeV/c2 and 55 ± 24 MeV/c2, respectively. The branching ratios are found to be consistent with an octet assignment. The A2 data are presented and are compatible with JPC=2++. In addition, the productions of ρ0, ω, and φ0 are discussed in conjunction with simultaneous Σ−(1385) production and the results are compared with quark-model predictions.
No description provided.
No description provided.
A detailed analysis is presented of the reactions pp→pp,pp→ppπ0 and pp→pπ+n. The production cross sections are found to be 11.47 ± 0.33 mb, 2.54 ± 0.16 mb, and 5.73 ± 0.35 mb, respectively. The t dependence of elastic scattering can be described by the form e7.9t over the range 0.05<−t<0.50 GeV2. The single-particle distributions for the single-pion production processes are presented. Further detailed analyses are presented which demonstrate that pion-exchange phenomenology, both elementary and Reggeized, can account for the gross features of the peripheral pp→pπ+n data for M(pπ+)<2.4 GeV. Isospin-12 isobars are produced by some other processes in the channel pp→pN*+, especially when the invariant mass of the pion with the unrelated proton is large. We discuss the properties of these isobars.
No description provided.
FITTED OVER 0.05 < -T < 0.5 GEV**2.
No description provided.
Elastic K+p scattering at a beam momentum of 4.27 GeV/c is studied and compared with elastic K−p scattering in order to extract the imaginary part of the non-Pomeranchukon-exchange amplitude. The single-pion-production cross sections are presented as well as production cross sections and resonance parameters for the Δ(1236), the K*+(890), and the K*+(1420). Production and decay distributions for the Δ++(1236) and the K*+(890) are presented and compared with the absorptive particle-exchange model and with Regge-pole-exchange models.
No description provided.
BREIT-WIGNERS PLUS PHASE SPACE TO DETERMINE RESONANCE PRODUCTION CROSS SECTIONS.
No description provided.
The reactions π − p → p π − and π − p → p ϱ − ( ϱ − → π − π 0 ) at 10 GeV/ c with the proton in the forward direction in the c.m.s. are discussed on the basis of 953 elastic scattering events and 2240 events of the reaction π − p → p π − π 0 . The total backward cross sections are 0.52±0.10 and 1.52±0.28 μ b, respectively. In both cases the production mechanism is compatible with the dominance of the baryonic Δ δ Regge trajectory exchange. The ϱ − decay angular distributions are studied in the u -channel helicity frame and the spin density matrix elements are presented as functions of u .
No description provided.
DATA FROM PRIV COMM WITH B. GHIDINI.
DATA FROM PRIV COMM WITH B. GHIDINI.
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