Two-body strange-particle final states in pi- p interactions at 4.5 and 6 gev/c

Crennell, D.J. ; Gordon, H.A. ; Lai, Kwan-Wu ; et al.
Phys.Rev.D 6 (1972) 1220-1254, 1972.
Inspire Record 73936 DOI 10.17182/hepdata.3601

Results on the following π−p reactions involving a hyperon are studied at 4.5 and 6.0 GeV/c from a high-statistics bubble-chamber experiment. (1) π−p→(Λ, Σ0)K0: Differential cross sections and hyperon polarizations are presented. Comparison with the line-reversed reactions K¯N→(Λ, Σ0)π indicates the failure of the predictions of K*(890) and K*(1420) exchange degeneracy. Effective trajectories for these two reactions are compared. Shrinkage is observed in K¯N→Λπ and not in π−p→ΛK0. (2) π−p→(Λ, Σ0)K*(890)0: Differential cross sections, hyperon polarizations, and K*(890)0 density-matrix elements are determined. ΛK*(890)0 decay correlations are found to impose strong constraints on the scattering amplitudes. The data indicate that both natural- and unnatural-parity exchanges contribute large, but opposite, Λ polarizations. This behavior cannot be explained by a simple exchange model utilizing K and the exchange-degenerate K*(890) and K*(1420) only. Additional trajectories or absorption effects are required to obtain the observed Λ-polarization effects. Comparison of ΛK*(890)0 and Σ0K*(890)0 indicates the greater importance of unnatural-parity exchange in the former reaction. We observe no evidence for deviations from isospin predictions in ΛK*(890)0 production where K*(890)0→K+π− and KS0π0. (3) π−p→ΛK*(1420)0 and ΛK*(1300)0: K*(1420)0 density-matrix elements satisfying positivity constraints are determined allowing for s-wave interference effects. Evidence of the existence of a narrow K*(1300)0→Kππ with a dominant K+ρ− decay mode is observed in the 4.5- and 6-GeV/c data. (4) Σ(1385), Λ(1405), Λ(1520) production: Differential cross sections for the quasi-two-body reactions π−p→Y0K0, where Y0 is Λ(1405), Λ(1520), or Σ(1385)0, are presented and found to have a very similar flat slope in the forward direction. Data for forward K+ scattering in the reaction π−p→Σ(1385)−K+ are presented and discussed. It is argued that this forward peak cannot be explained by kinematic reflection or an s-channel effect and therefore must be due to either two-particle exchange or a single exotic exchange in the t channel.

39 data tables

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FIT FOR FORWARD CROSS SECTION AND SLOPE.

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Study of the Reactions $\pi^- p \to K^0 \Sigma^0(1385)$ and $\pi^- p \to K^+ \Sigma^-(1385)$ at 3.95-{GeV}/$c$

The CERN-College de France-Madrid-Stockholm collaboration Aguilar-Benitez, M. ; Albajar, M.C. ; Ferrando, A. ; et al.
Z.Phys.C 6 (1980) 109-123, 1980.
Inspire Record 153921 DOI 10.17182/hepdata.14369

The reactionsπ−p→K0∑0(1385) andπ−p→K+∑−(1385) are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to approximately 90 events/μb. The total and differential cross sections and the density matrix elements of the Σ(1385) are presented. The results are compared with those obtained for the related processesπpp→K+∑+(1385) and\(K^ -p \to \pi ^ \mp\sum ^ \pm(1385)\) in this energy range. Evidence is presented for the existence of production mechanisms with exotic exchanges in thet channel.

16 data tables

FROM THE CHANNEL PI- P --> LAMBDA K0 PI0 WHICH HAS A CROSS SECTION OF 72 +- 4 MUB.

FROM THE CHANNEL PI- P --> LAMBDA K+ PI- WHICH HAS A CROSS SECTION OF 79 +- 3 MUB.

FORWARD CROSS SECTION.

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Study of the Reactions $\pi^- p \to K^0(890)\Lambda$, $K^0(890) \Sigma^0$ and $K^0(890) \Sigma^0(1385)$ at 3.95-{GeV}/$c$

The CERN-College de France-Madrid-Stockholm collaboration Aguilar-Benitez, M. ; Albajar, M.C. ; Ferrando, A. ; et al.
Z.Phys.C 6 (1980) 195-215, 1980.
Inspire Record 153917 DOI 10.17182/hepdata.1428

The reactionsπ−p→K0(890) Λ,K0(890)Σ0 andK0(890)Σ0 are studied at an incident momentum of 3.95 GeV/c using data from a high statistics bubble chamber experiment corresponding to ∼90 events/μb. The differential cross sections, density matrix elements of the vector meson and hyperon polarizations are presented. A transversity amplitude analysis is performed for each of the reactions. The results are compared with those obtained for the SU(3) related processesK−p→ϕΔ, ϕΣ0, ϕΣ0(1385) andϱ−Σ+(1385) and with predictions of the additive quark model and SU(6) sum rules.

39 data tables

BREIT-WIGNER FIT WITH BACKGROUND POLYNOMIAL.

BACKWARD CROSS SECTION.

TOTAL CROSS SECTION USING SLICING TECHNIQUE. FORWARD (-TP < 1.2 GEV**2) CROSS SECTION IS 25 +- 2 MUB: DOUBLE MASS CUT GIVES 20 +- 7 PCT BACKGROUND CONTAMINATION.

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Strange-particle production in pi- p collisions at 11.2 gev/c leading to two charged final particles

Dameri, M. ; Tomasini, G. ; Trevisan, U. ; et al.
Nuovo Cim.A 9 (1972) 1-27, 1972.
Inspire Record 78421 DOI 10.17182/hepdata.37457

In this paper we present the results of an analysis of strange-particle production in π−p collisions leading to two charged final particles and at least one strange neutral decay. The sample consists

1 data table

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Study of Hypercharge Exchange Reactions of the Type 0- 1/2+ $\to$ 2+ 1/2+ at 4-{GeV}/$c$

The CERN-College de France-Madrid-Stockholm collaboration Aguilar-Benitez, M. ; Albajar, M.C. ; Ferrando, A. ; et al.
Z.Phys.C 8 (1981) 313, 1981.
Inspire Record 156685 DOI 10.17182/hepdata.13530

Results are presented for the quasi two-body hypercharge exchange reactions of the type 0−1/2+→2+1/2+:$$\begin{gathered}

12 data tables

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Backward $K^{*0}$ Production in $\pi^- p \to \Lambda^0 K^+ \pi^-$ Reaction at 9-{GeV}/$c$ and 12-{GeV}/$c$

Ferrer, A. ; Treille, D. ; Rivet, P. ; et al.
Nucl.Phys.B 178 (1981) 373-391, 1981.
Inspire Record 153782 DOI 10.17182/hepdata.34397

We have analysed about 85 000 fast Λ 0 events, obtained in a fast proton triggered experiment performed at the CERN-Ω spectrometer at 9 and 12 GeV/ c incident π − beam. Nearly 2500 Λ 0 K + π − events have been isolated. We find strong production of quasi-two-body processes Λ 0 K ∗0 and ∑ ∗− K + consistent with u -channel hyperon exchange. Results on Λ 0 polarization, K ∗0 decay parameters and differential cross sections are given for Λ 0 K ∗0 (892) and Λ 0 K ∗0 (1430) final states. A comparison is made with the associated backward Λ 0 (1520) K ∗0 production seen in the four-prong reaction π − p→pK − K + π − obtained in the same experiment.

8 data tables

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EXPONENTIAL FIT TO DN/DU.

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K*0 (890) POLARIZATION MEASUREMENTS IN THE HYPERCHARGE EXCHANGE REACTION PI- P ---> K*0 (890) LAMBDA0 / SIGMA0 AT 10-GEV/C

The BARI-BONN-CERN-DARESBURY-GLASGOW-LIVERPOOL-MILAN-VIENNA collaboration Evangelista, C. ; Ghidini, B. ; Palano, A. ; et al.
Nucl.Phys.B 165 (1980) 383-394, 1980.
Inspire Record 157497 DOI 10.17182/hepdata.34585

K ∗0 (890) production in the hyperchange exchange reaction π − p → K ∗0 (890) Λ 0 Σ 0 at 10 GeV/ c (28 448 events) is discussed. An amplitude analysis in the t ′ range up to 1 GeV 2 shows that the production mechanism is dominated by natural parity exchange (∼84%). Comparisons are made with predictions from a Regge model and a quark model.

2 data tables

DENSITY MATRIX ELEMENTS IN THE GOTTFRIED-JACKSON SYSTEM ALLOWING FOR COHERENT S-WAVE BACKGROUND TO P-WAVE BREIT-WIGNER K*(892)0 RESONANCE.

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Amplitude analysis from decay correlations - application to pi- p ---> k*(0) lambda at 3.9 gev/c

Abramovich, M. ; Irving, A.C. ; Martin, Alan D. ; et al.
Phys.Lett.B 39 (1972) 353-357, 1972.
Inspire Record 75784 DOI 10.17182/hepdata.28306

Decay correlation data for π − p → K ∗ Λ at 3.9 GeV /c are analyzed to determine the amplitude structure. We emphasize combinations of observables invariant under rotations between s and t channel frames.

1 data table

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Study of the k*0 lambda and k*0 sigma0 final states from pi- p interactions at 3.9 gev/c

Abramovich, M. ; Chaloupka, V. ; Chung, S.U. ; et al.
Nucl.Phys.B 39 (1972) 189-200, 1972.
Inspire Record 75244 DOI 10.17182/hepdata.32953

A study of π − p → K ∗ Λ and π − p → K ∗ Σ° at 3.9 GeV /c indicates that the main features of both reactions can be interpreted in terms of simple exchange processes, the first involving both natural and unnatural exchange, the second showing evidence for natural parity exchange only.

1 data table

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A STUDY OF THE REACTIONS pi- p ---> K* LAMBDA, K* SIGMA AND K* Y1* (1385) AT 3.93-GeV/c

Yaffe, D. ; Abramovich, M. ; Chaloupka, V. ; et al.
Nucl.Phys.B 75 (1974) 365-387, 1974.
Inspire Record 80700 DOI 10.17182/hepdata.32197

We have investigated the final states K ∗0 (890)Σ, K ∗0 (890)Σ 0 and K ∗0 (890) Y 1 ∗0 (1385) produced in π − p interactions at 3.93 GeV/ c . We present the differential cross sections and spin density matrix elements for the resonances as functions of momentum transfer, as well as the gL and Σ 0 polarizations. The Σ 0 polarization is found to be positive and maximal. An amplitude analysis is performed for the K ∗ Λ and K ∗ Σ 0 reactions, and it is found that one natural parity transversity amplitude is dominant for the latter.

14 data tables

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