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

No description provided.

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FIT FOR FORWARD CROSS SECTION AND SLOPE.

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Study of three quasi-two-body channels from pi + p interactions at 3.9 GeV/c

Haber, B. ; Hodous, M.F. ; Hulsizer, R.I. ; et al.
Phys.Rev.D 11 (1975) 495-509, 1975.
Inspire Record 107224 DOI 10.17182/hepdata.24871

The pπ+π0 and pπ+π+π− final states from π+p interactions at 3.9 GeV/c have been analyzed by the prism-plot technique and the following three quasi-two-body channels have been studied in detail: π+p→ρ+p, π+p→π0Δ++, and π+p→ρ0Δ++. Results are presented on cross sections, differential cross sections, and single and joint spin density matrix elements. These are compared with the Dar-Watts-Weisskopf absorption model and Reggeized pion-exchange model predictions. Relations among joint spin density matrix elements for ρ0Δ++ are compared with quark-model predictions.

2 data tables

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Study of four-prong events in pi+ p interactions at 3.5 gev/c

Ronat, E.E. ; Eisenberg, Y. ; Lyons, L. ; et al.
Nucl.Phys.B 38 (1972) 20-36, 1972.
Inspire Record 75333 DOI 10.17182/hepdata.32958

The non-strange four-prong events of π + p interactions at 3.5 GeV/ c are studied. Cross sections are calculated for all resonance productions in the channels π + p → p π + π + π − ( σ T = 3.18 ± 0.13 mb) and π + p → p π + π + π − π o ( σ T = 4.03 ± 0.16 mb). The dominant two body reactions Δ ++ ϱ o and Δ ++ ω o are investigated in detail, and production and decay distributions are presented as well as joint decay density matrix elements and joint correlation terms. The Δ ++ ϱ o reaction is compared to predictions of OPE with absorption and the Δ ++ ω o is compared to rho-exchange with sharp cutoff.

7 data tables

FOUR-PRONG, NON-STRANGE CROSS SECTIONS. SYSTEMATIC ERROR INCLUDED.

BREIT-WIGNER RESONANCE FITS, ALLOWING FOR PHASE SPACE AND RELEVANT REFLECTIONS, TO <P PI+ PI+ PI-> FINAL STATE.

BREIT-WIGNER RESONANCE FITS, ALLOWING FOR PHASE SPACE AND RELEVANT REFLECTIONS, TO <P PI+ PI+ PI- PI0> FINAL STATE.

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Study of pi+ p four prong interactions from 2.95-GeV/c to 4.08-GeV/c

Brown, David ; Gidal, George ; Birge, Robert W. ; et al.
Phys.Rev.D 1 (1970) 3053, 1970.
Inspire Record 74876 DOI 10.17182/hepdata.25065

In a study of the production mechanism of quasi-two-body final states at the five incident π+ momenta 2.95, 3.2, 3.5, 3.75, and 4.08 GeV/c, approximately 40 000 events with four outgoing charged particles were investigated. The cross sections for the processes π+p→N*++ρ, π+p→N*++ω, π+p→N*++η, and π+p→N*++f have been measured as a function of the pion energy. The differential cross sections and the decay density-matrix elements are discussed in terms of one-meson-exchange models [with absorption (OPEA) and with form factor (OPEW)] and Regge models. For the N*++ρ and the N*++ω reactions, the joint-decay matrix elements are calculated. The formation of N*(2850) in the direct channel is also investigated.

30 data tables

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STUDY OF REACTIONS pi+ p ---> (rho0, omega) DELTA++ (1236) AT 10.3-GeV/c

Beaufays, J. ; Kennedy, C.N. ; Key, A.W. ; et al.
Phys.Rev.D 18 (1978) 27, 1978.
Inspire Record 6322 DOI 10.17182/hepdata.24331

Cross sections, differential cross sections, single and joint spin-density matrix elements are given for the reactions π+p→(ρ0, ω)Δ++ at 10.3 GeV/c. Correlations between the vector-meson and the Δ++ decay angular distributions are observed. A discussion of the results in terms of particle exchange, SU(3) symmetry, quark additivity, and the equal-phase hypothesis is presented. The amplitudes for the process π+p→ρ0Δ++ are extracted by a model-dependent analysis and compared with current theoretical predictions.

9 data tables

P-WAVE BREIT-WIGNER RESONANCES PLUS BACKGROUND USED WITH SLICE TECHNIQUE.

FROM RESONANCE OVERLAP REGION WITH BACKGROUND SUBTRACTED AND NORMALIZED TO TOTAL CROSS SECTION.

FROM RESONANCE OVERLAP REGION WITH BACKGROUND SUBTRACTED AND NORMALIZED TO TOTAL CROSS SECTION.

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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

No description provided.


Rho0 delta++ and omega delta++ joint decay correlations at 3.7 gev/c

Barnham, K.W.J. ; Abrams, G.S. ; Butler, W.R. ; et al.
Phys.Rev.D 7 (1973) 1384-1394, 1973.
Inspire Record 82336 DOI 10.17182/hepdata.22157

The joint decay density-matrix elements have been measured for the ρ0Δ++ and ωΔ++ channels at 3.7 GeV/c. The data are presented as a function of momentum transfer in both the t-channel and s-channel coordinate systems. The presence of correlated decays is illustrated for both reactions by employing selective cuts on the decay angles of one resonance, and displaying the effects on the decay distribution of the opposing resonance. An amplitude analysis is performed with the data near 0° production angle, where we obtain a helicity decomposition of the scattering amplitude with no experimental ambiguity.

4 data tables

T-CHANNEL COORDINATE SYSTEM (XYZ=TH).

T-CHANNEL COORDINATE SYSTEM (XYZ=TH).

S-CHANNEL COORDINATE SYSTEM (XYZ=SH).

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Study of the Reaction pi+ p --> omega Delta++ (1236) at 16-GeV/c

The Aachen-Berlin-Bonn-CERN-Cracow-Heidelberg collaboration Grassler, H. ; Honecker, R. ; Laven, H. ; et al.
Nucl.Phys.B 115 (1976) 365-384, 1976.
Inspire Record 110390 DOI 10.17182/hepdata.35656

The reaction π + p→ ωΔ ++ (1236) is studied at 16 GeV/ c . Cross section, differential cross section, single and joint spin-density matrix elements are given and the correlations between the ε and Δ ++ (1236) decay angular distributions are investigated. Natural and unnatural spin-parity exchanges contribute to this reaction in roughly equal amounts. Natural exchanges lead predominantly to Δ ++ (1236) with helicity ± 3 2 , while unnatural exchanges lead predominantly to Δ ++ (1236) with helicity ± 1 2 and to ε with helicity zero. Furthermore, unnatural exchanges are small at t ′≅0.2 GeV 2 compared to other t ′ values, which may be due to the nonsense wrong-signature-zero of the B-meson exchange. Quark model relations are found to be satisfied by the data.

6 data tables

CORRECTED FOR UNSEEN OMEGA DECAY MODES. 'SLICE METHOD' USED TO HANDLE RESONANCE TAILS AND BACKGROUND.

FROM EVENTS WITHIN MASS-CUTS FOR RESONANCES AND NORMALIZED TO TOTAL CROSS SECTION.

'ALL'.

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Study of the Reaction pi+ p --> rho0 Delta++ (1236) at 16-GeV/c

The Aachen-Berlin-Bonn-CERN-Cracow-Heidelberg collaboration Honecker, R. ; Lauscher, P. ; Laven, H. ; et al.
Nucl.Phys.B 106 (1976) 365-384, 1976.
Inspire Record 108897 DOI 10.17182/hepdata.35864

The reaction π + p → ϱ 0 Δ ++ (1236) at 16 GeV/ c has been studied. Cross section, differential cross section, single and joint spin-density matrix elements are given. Correlations between the ϱ 0 and Δ ++ (1236) decay distributions are observed. Unnatural spin-parity exchanges, mainly observed at small t ' values, dominate the ϱ 0 Δ ++ (1236) production. The natural exchange contributions are only (7 ± 2)% and become as important as the unnatural exchanges beyond t ' = 0.3 GeV 2 . Contributions to Δ ++ (1236) helicity 3 2 states do not exceed 20% of the total ϱ 0 Δ ++ (1236) cross section and are mainly due to unnatural exchanges.

6 data tables

'SLICE METHOD' USED TO HANDLE RESONANCE TAILS AND BACKGROUND.

FROM EVENTS WITHIN MASS-CUTS FOR RESONANCES AND NORMALIZED TO TOTAL CROSS SECTION.

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