Production and Decay of Cascade Hyperons

1969/03/25 by P.M. Dauber, Philip M. Dauber, J. Peter Berge +5 · 3 citations
Physics and Astronomy · #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #High-Energy Particle Collisions Research

paper · doi:10.1103/physrev.179.1262

Abstract

The production of cascade hyperons by K^\ensuremath- incident on hydrogen has been studied at beam momenta of 1.7, 2.1, and 2.4-2.7 GeV/c. A sample of 3028\ensuremathΞ^\ensuremath- and 934\ensuremathΞ⁰ was obtained. Cross sections and polarization for \ensuremathΞ^\ensuremath-K⁺ and \ensuremathΞ⁰K⁰ production are presented. The data are compatible with dominance by I=0 baryon exchange in \ensuremathΞ^\ensuremath-K⁺ production, but also provide strong evidence for resonance formation in the s channel compatible with Y₀^*(2100). Copious production of \ensuremathΞ^*(1530) and K^*(890) is observed in the three-and four-body final states. A broad \ensuremathΞ\ensuremathπ enhancement is observed in the \ensuremathΞ^\ensuremath-K⁺\ensuremathπ⁰ and \ensuremathΞ⁰K⁺\ensuremathπ^\ensuremath- final states at a mass near 1894 MeV/c² and with a width of about 98 MeV/c². This enhancement is identified with the \ensuremathΞ^*(1930) first observed by Badier et al. Lifetime measurements give \ensuremathτ_\ensuremathΞ^\ensuremath-=(1.61\ifmmode±\else\textpm\fi0.04)\ifmmode×\else\texttimes\fi10^\ensuremath-10 sec and \ensuremathτ_\ensuremathΞ⁰=(3.07_\ensuremath-0.20^+0.22)\ifmmode×\else\texttimes\fi10^\ensuremath-10 sec. A decay-parameter analysis assuming spin \textonehalf yields \ensuremathα_\ensuremathΞ^\ensuremath-=\ensuremath-0.391\ifmmode±\else\textpm\fi0.045, \ensuremathα_\ensuremathΞ⁰=\ensuremath-0.43\ifmmode±\else\textpm\fi0.09, \ensuremathΦ_\ensuremathΞ^\ensuremath-\ensuremath≡invtan(\frac\ensuremathβ\ensuremathγ)_\ensuremathΞ^\ensuremath-=\ensuremath-(14\ifmmode±\else\textpm\fi11)\ifmmode^∘\else\textdegree\fi, and \ensuremathΦ_\ensuremathΞ⁰=(38\ifmmode±\else\textpm\fi19)\ifmmode^∘\else\textdegree\fi if \ensuremathα_\ensuremathΛ=0.647 is used. These results are in agreement with T invariance and the |\ensuremathΔI|=(1)/(2) rule. A compilation of LRL results for \ensuremathΞ^\ensuremath- and \ensuremathΞ⁰ yields \ensuremathα_\ensuremathΞ=\ensuremath-0.380\ifmmode±\else\textpm\fi0.034 and \ensuremathΦ_\ensuremathΞ=\ensuremath-(1\ifmmode±\else\textpm\fi7)\ifmmode^∘\else\textdegree\fi, implying \ensuremathΔ=invtan(\ensuremath-\frac\ensuremathβ\ensuremathα)_\ensuremathΞ=(178\ifmmode±\else\textpm\fi16)\ifmmode^∘\else\textdegree\fi. Hence the final-state \ensuremathΛ\ensuremathπ phase difference \ensuremathδ_s\ensuremath-\ensuremathδ_p=\ensuremath-(2\ifmmode±\else\textpm\fi16)\ifmmode^∘\else\textdegree\fi if T is strictly conserved in the decay. Two examples of \ensuremathΞ^\ensuremath-\ensuremath→\ensuremathΛe^\ensuremath-\ensuremathν were observed. Upper limits \ensuremath≈ 1\ifmmode×\else\texttimes\fi10^\ensuremath-3 have been set for the branching fractions of other |\ensuremathΔS|=1 and |\ensuremathΔS|=2 leptonic and nonleptonic decays of \ensuremathΞ^\ensuremath- and \ensuremathΞ⁰.

Citations

• Some Properties of Ξ − and Ξ 0 Hyperons Produced in K − p Interactions between 1.05 and 1.7 BeV/ c
• K − − p Interaction at 2.24 BeV c
• Partial-Wave Analysis of K − p → Ξ − K + at 2 GeV c

Cited by

• Strange Pentaquark Molecules in QCD Sum Rules
• Study of the interaction between Ξ baryons and light mesons via femtoscopy at the LHC
• Ξ(1530) production in K^-p scattering process

Related

• Some Properties of Ξ − and Ξ 0 Hyperons Produced in K − p Interactions between 1.05 and 1.7 BeV/ c
• ReactionsK−p→Hyperon+Mesonat 3.5 GeV/c
• Investigation of the \mathbfΣ⁰ Production Mechanism in p(3.5 GeV)+p Collisions
• Hyperon-Production Studies in p+p → Λ+ K⁰_S + p + π⁺ with HADES
• Highlights of the Spectroscopy of Hyperons and Cascade Baryons