Parity doubling of highly excited mesons

Glozman has proposed that highly excited mesons and baryons fall into parity doublets, and that the f4(2050) on the leading Regge trajectory should have a nearly degenerate J^{PC} = 4^{-+} partner. A re-analysis of Crystal Barrel data does not support this idea. A likely explanation is that centrifugal barriers on the leading trajectory allow formation of the L=J-1 states, but are too strong to allow L=J states. Two new polarisation experiments have the potential for major progress in meson spectroscopy.Comment: 7 pages, 2 figures, 1 table. Further experimental detail added and additional algebra. Conclusions unchanged. To be published in Physics Letters

Spin Correlation Coefficients in pp-->pnpi+ from 325 to 400 MeV

The spin correlation coefficient combinations Axx + Ayy, Axx - Ayy and the analyzing powers Ay(theta) were measured for pp-->pnpi+ at beam energies of 325, 350, 375 and 400 MeV. A polarized internal atomic hydrogen target and a stored, polarized proton beam were used. These polarization observables are sensitive to contributions of higher partial waves. A comparison with recent theoretical calculations is provided.Comment: 8 Pages, 1 Table, 5 Figures. Accepted for publication in Phys. Lett.

Spin observables of the reactions NN -> DeltaN and pd -> Delta (pp)(1S0) in collinear kinematics

A general formalism for double and triple spin-correlations of the reaction NN -> DeltaN is developed for the case of collinear kinematics. A complete polarization experiment allowing to reconstruct all of the four amplitudes describing this process is suggested. Furthermore, the spin observables of the inelastic charge-exchange reaction pd -> Delta^0(pp)(1S0) are analyzed in collinear kinematics within the single pN scattering mechanism involving the subprocess pn -> Delta^0p. The full set of spin observables related to the polarization of one or two initial particles and one final particle is obtained in terms of three invariant amplitudes of the reaction pd -> Delta (pp)(1S0) and the transition form factor d->(pp)(1S0). A complete polarization experiment for the reaction pd -> Delta^0(pp)(1S0) is suggested which allows one to determine three independent combinations of the four amplitudes of the elementary subprocess NN -> DeltaN.Comment: 12 pages, 1 figur

Quark-model study of few-baryon systems

We review the application of non-relativistic constituent quark models to study one, two and three non-strange baryon systems. We present results for the baryon spectra, potentials and observables of the NN, N$\Delta$, $\Delta\Delta$ and NN$^*(1440)$ systems, and also for the binding energies of three non-strange baryon systems. We make emphasis on observable effects related to quark antisymmetry and its interplay with quark dynamics.Comment: 82 pages, 36 figures, 18 tables. Accepted for publication in Reports on Progress in Physic

Calibration of a polarized proton target

Proton polarization of a butanal 5% H₂O-EHBA-Cr(V) polarized target have been measured by elastic scattering to an accuracy of ± 2%. The four cubic centimeter target sample, suspended in a 25 KG field, was cooled by a pumped ³He refrigerator. Left right asymmetry of scattered particles were detected by a two arm telescope, each arm consisting of a MWPC and a plastic scintillator. Separation of elastic two body events in hydrogen from non-elastic two body events in nonhydrogenous material was achieved using a coplanarity test.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Measurement of spin asymmetry parameters in the [reaction proton + proton --> proton + neutron + positive pion using a polarized hydrogen target and a polarized proton beam]

Measurements have been made of the spin asymmetry parameters A[sub NN], A[sub LL], A[sub SS], A[sub SL], A[sub NO] and A[sub ON] in the inelastic reaction pp → pn π⁺ at incident beam energies of 510, 465 and 420 MeV. The measurement of A[sub NN] is described specifically. This experiment has reported the first results of a spin asymmetry measurement with a polarized beam and polarized target in a reaction having a three particle final state. Neutrons were detected in an array of position sensitive scintillation counters while the two charged particles were detected in an array of multi-wire proportional chambers. Time of flight was recorded for the neutron. Events were kinematically reconstructed in the analysis program in which free and quasi-free scattering events were separated by a X² test to the kinematical fit. The unpolarized background from non-hydrogenous material in the target was estimated from unpolarized data obtained with the target material replaced by teflon. Results are presented as asymmetries binned against single kinematic variables. The statistical precision is 10% on the best data. The data are sufficiently complete to identify the dominant partial wave amplitudes. A comparison is made with calculations based on a one-pion-exchange Δ dominance model. Discrepancies from the model are attributed the neglect of the TTN S₃₁ interaction in the calculations.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Measurement of the Z 0 line shape parameters and the electroweak couplings of charged leptons

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