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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Polarization Measurement of the $\Sigma^+$ Produced in the Line Reversed Reactions $\pi^+ p \to K^+ \Sigma^+$ and $K^- p \to \pi^- \Sigma^+$ at 7-{GeV}/$c$ and 11.6-{GeV}/$c$

Baker, P.A. ; Chima, J.S. ; Dornan, P.J. ; et al.
Phys.Rev.Lett. 40 (1978) 678, 1978.
Inspire Record 129108 DOI 10.17182/hepdata.20914

The polarization of the Σ+ has been measured for the line-reversed reactions π+p→K+Σ+ and K−p→π−Σ+ at 7 and 11.6 GeV/c using the SLAC Hybrid Facility. Since the Σ+ decay is observed in the bubble chamber, the trigger of the flash lamps on a fast K+(π−) did not bias the polarization measurements. We find that the Σ+ polarizations from the two reactions have opposite signs but similar magnitudes and are in much better agreement with the predictions of weak exchange degeneracy than previous lower-energy comparisons.

1 data table

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