VECTOR MESON PRODUCTION IN HYPERCHARGE EXCHANGE REACTIONS AT 7-GeV/c AND 11.5-GeV/c

Ballam, Joseph ; Brau, J. ; Bouchez, J. ; et al.
Nucl.Phys.B 166 (1980) 189-206, 1980.
Inspire Record 143136 DOI 10.17182/hepdata.34582

Results are presented on vector meson production in the hypercharge exchange reactions: π + p → K ∗+ (890) Y + and K − p→ ρ − Y + where Y + is either Σ + or Y ∗+ (1385). These reactions have been studied at 7 GeV/ c and 11.5 GeV/ c using the SLAC Hybrid Facility. Total and differential cross sections, hyperon polarization, and vector meson decay angular distributions are presented. We find that reactions with Σ + production are dominated by natural parity exchange. The Y ∗ (1385) reactions are consistent with substantial natural parity exchange contributions but also show significant unnatural parity exchange. The differential cross sections and polarization measurements for the vector meson production are compared to the pseudoscalar production reactions.

7 data tables

Axis error includes +- 20/20 contribution.

Axis error includes +- 20/20 contribution.

Axis error includes +- 20/20 contribution.

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Confirmation of Exchange Degeneracy Predictions in the Line Reversed Reactions: $\pi^+ p \to K^+ Y^*(1385)$ and $K^- p \to \pi^- Y^*(1385)$ at 11.6-{GeV}/$c$

Ballam, Joseph ; Bouchez, J. ; Carroll, J.T. ; et al.
Phys.Rev.Lett. 41 (1978) 676, 1978.
Inspire Record 130550 DOI 10.17182/hepdata.20815

We have measured in a single experimental setup the differential cross sections and polarizations of the Y*(1385) produced in the two line-reversed reactions π+p→K+Y*(1385) (260 eV/μb) and K−p→π−Y*(1385) (180 eV/μb) at 11.5 GeV/c. We compare these results to Σ+ production in the same experiment. The data have been derived from a triggered bubble-chamber experiment using the SLAC Hybrid Facility. We find that both helicity-flip-dominated (Y*) and helicity-nonflip-dominated (Σ) processes are consistent with weak-exchange-degeneracy predictions.

5 data tables

Axis error includes +- 10/10 contribution.

Axis error includes +- 10/10 contribution.

Axis error includes +- 10/10 contribution.

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Lambda Polarization at 90-degrees in K+Lambda Photoproduction

Groom, D.E. ; Marshall, J.H. ;
Phys.Rev. 159 (1967) 1213-1219, 1967.
Inspire Record 52237 DOI 10.17182/hepdata.26579

The Λ polarization and the differential cross section for the reaction γ+p→K++Λ have been measured, using the Caltech synchrotron, at 90° in the c.m. system and at laboratory photon energies of 1100, 1200, and 1300 MeV. Protons from the asymmetric decay of the Λ were detected by counters placed above and below the production plane. Kaons were identified by their behavior in a thick range telescope. Polarization results were PΛ=+0.34±0.09 at 1100 MeV, +0.30±0.07 at 1200 MeV, and +0.08±0.07 at 1300 MeV, where PΛ was measured in the p^γ×p^Λ direction. The differential cross section was constant with energy at 0.14±0.01 μb/sr. Although the apparent bump in the polarization at 90° at a total energy of ≈1700 MeV adds support to models which invoke a resonance here, no really new conclusions can be reached.

2 data tables

No description provided.

No description provided.