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An enhancement at the ΣK threshold (1680) MeV observed in K- p reactions at 4.2 GeV/c

Physics Letters B 80:1-2 (1978) 145-149

Authors:

C Dionisi, J Diaz, R Armenteros, P Gavillet, A Gurtu, RJ Hemingway, M Mazzucato, R Blokzijl, JC Kluyver, GGG Massaro, WJ Metzger, J Schotanus, HG Tiecke, B Foster, PR Lamb, WL McDowell

Abstract:

An enhancement in the (ΣK) mass spectrum at threshold is observed in K-p interactions at 4.2 GeV/c. It appeats both in the neutral and negative charge states. Corresponding ΛK mass distributions show weak evidence for an effect close to this threshold (∼1680 MeV). Although the interpretation of the (ΣK) enhancement by itself is ambiguous, a (ΣK)-(ΛK) coupled channel analysis gives results compatible with its interpretation as a new Ξ*. © 1978.
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Ω- produced in K-p reactions at 4.2 GeV/c

Nuclear Physics, Section B 142:3 (1978) 205-219

Authors:

RJ Hemingway, R Armenteros, C Dionisi, P Gavillet, A Gurtu, SO Holmgren, MJ Losty, JC Marin, M Mazzucato, L Montanet, M Banting, R Blokzijl, AJ De Groot, B Jongejans, JC Kluyver, WM Van Leeuwen, GGG Massaro, AG Tenner, GF Wolters, PM Heinen, EW Kittel, WJ Metzger, HGJM Tiecke, JJM Timmermans, RT Van De Walle, B Foster, P Grossmann, PR Lamb, JL Lloyd, J Wells

Abstract:

Forty Ω- events have been observed in a large (133 events/βb) experiment at 4.2 GeV/c incident K- momentum. Thirty nine of the events come from the three-body reaction K-p→Ω-K+K0. The Ω- is mainly produced in the forward hemisphere (direction of the incident K-). The lifetime is measured to be τ = (0.75 +0.14-0.11 × 10-10 sec substantially less than the Particle Data Group value of (1.3 -0.3+0.2) × 10-10 sec. The mass is determined to be 1671.7 ± 0.6 MeV, in good agreement with other determinations. The decay asymmetry parameter α (for the decay mode Ω- → ΛK-) is found to be -0.2 ± 0.4. © 1978.
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An I = 1 enhancement at a mass of 1550 MeV in the (Λπ) and (Σπ)-systems

Physics Letters B 78:1 (1978) 154-157

Authors:

C Dionisi, R Armenteros, J Diaz, P Gavillet, JB Gay, A Gurtu, RJ Hemingway, M Mazzucato, P Trepagnier, R Blokzijl, GGG Massaro, B Jongejans, J Engelen, JJ Timmermans, RT Van De Walle, B Foster, PR Lamb, WL McDowell

Abstract:

Evidence is presented for an I = 1 enhancement observed in the reactions K-p→Λ(Σ)K01K ±π∓ at 4.2 GeV c inciden momentum. The mass and width of the proposed new Y* are, respectively, (1553 ± 7) MeV) and (80 ± 30) MeV. A decay branching ratio Σπ (Σπ + Λπ) = (35 ± 12)% is also obtained. © 1978.
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Backward production of the B meson in K-p interactions at 4.2 GeV c

Physics Letters B 78:1 (1978) 158-161

Authors:

P Gavillet, C Dionisi, A Gurtu, RJ Hemingway, MJ Losty, JC Marin, M Mazzucato, L Montanet, E Pagiola, R Blokzijl, B Jongejans, JC Kluyver, GGG Massaro, JJ Engelen, JSM Vergeest, M Zralek, B Foster, P Grossmann, J Wells

Abstract:

The backward production of the B(1235) meson is studied in the reaction K-p→Σ-π+ω. This reaction is observed in the final state Σ-π+π+π-π 0. A π+ω mass enhancement is visible in the region of the B meson for events with small |u|K- →Σ-) squared four-momentum transfer. The properties of the enhancement agree with those of the B meson. The cross section for K-p→Σ-B+ at 4.15 GeV c incident K- momentum is (3.2 ± 0.5) μb. The backward production of the B meson is compared with similar baryon exchange productions of the A1 and C(Q1) axial vector mesons observed in the same experiment. © 1978.
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A spin determination of the Ξ* (1820) resonance

Physics Letters B 77:4-5 (1978) 451-453

Authors:

D Teodoro, J Diaz, C Dionisi, JB Gay, RJ Hemingway, MJ Losty, M Mazzucato, R Blokzijl, GGG Massaro, H Voorthuis, WJ Metzger, JJM Timmermans, RT van de Walle, B Foster, P Grossmann, WL McDowell

Abstract:

Using a spin test proposed recently by Minnaert, we determine the spin of the Ξ* (1820) resonance to be 3 2. © 1978.
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