The K − p reactions leading to charge exchange and hyperon final states have been studied at nine momenta between 862 and 1001 MeV/ c using data from a 600 000 picture exposure of the Lawrence Berkeley Laboratory 25″ liquid hydrogen bubble chamber. Partial cross sections are determined for all final states resolved by kinematic fitting. In addition, differential cross sections are presented for the two-body final states K o n , Λπ o and Σ +- π -+ along with hyperon polarization angular distributions for Λπ o and Σ + π − .
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The differential cross sections of the combined elastic and break-up K − d reaction have been measured at 1.21, 1.42 and 2.61 GeV/ c incident K − momentum. The measurements have been performed at the CERN PS using multiwire proportional chambers. The values of the invariant momentum transfer t explored (0.0005<| t |<0.1 GeV 2 ) include the Coulomb-nuclear interference region. The differential cross sections have been analysed in the framework of the Glauber impact-parameter formalism. The observed interference effects have been used to derive the ratio of the real to imaginary part of the forward K − n nuclear amplitude.
SUM OF COHERENT AND BREAK-UP SCATTERING.
SUM OF COHERENT AND BREAK-UP SCATTERING.
SUM OF COHERENT AND BREAK-UP SCATTERING.
The differential cross section in the very forward direction has been measured for K − and K + scattering (break-up and coherent) on a deuterium target at an incident momentum of 10 GeV/ c . From these measurements and using a model for the scattering and re-scattering effects in deuterium, we have exploited the Coulomb-nuclear interference to deduce the real part of the K ± n scattering amplitude at a momentum transfer t = 0. The measurements are the first ever obtained for the K + n reaction and the first at this energy for the K − n reaction. A comparison has been made between our results and those predicted from dispersion relations. A new dispersion-relation fit including all the existing K ± n values at different energies has been performed.
SUM OF COHERENT AND BREAK-UP SCATTERING ON DEUTERIUM.
FROM FIT TO D(SIG)/DT OVER -T=0.0018 TO 0.074 GEV**2 ALLOWING FOR COULOMB SCATTERING, DOUBLE SCATTERING, INTERFERENCES AND FERMI MOTION. CORRELATION BETWEEN SLOPE AND RE(AMP)/IM(AMP) IS REFLECTED IN THE GIVEN SYSTEMATIC E RRORS.
We have searched for production of charmed mesons in the reaction π−+N→D*−+X, D*−→π−+D¯0, D¯0→K++π− at a beam momentum of 10.5 GeV/c. We measure the cross section times branching ratio to be 7±20 nb/nucleon.
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CROSS-OVER IS AT -T = 0.17 +- 0.02 GEV**2. DIVIDE BY 20 TO GET D(SIG)/DT IN MB/GEV**2. CORRECTED FOR LOST EVENTS FOR -T < 0.12 GEV**2.
FROM QUADRATIC EXPONENTIAL FIT TO D(SIG)/DT. BOTH STATISTICAL AND SYSTEMATIC ERRORS INCLUDED IN VALUES.
After summarizing the properties of the socalled Dalitz Array (DA), which is a genuine characteristics of a resonance, we determine those of the well known ε, γ, andA2 resonances produced in theK−p→π+π−π0Λ final state at 4.2 Ge V/c. A tentative measurement of the DA of theA1 meson produced backwards in the reactionK−p→π+π+π−Σ− is also presented. The data for this analysis come from the high statistics (130 events/μb) experiment performed by the ACNO Collaboration.
FROM FITTING MOMENTS OF DALITZ SERIES WITH BREIT-WIGNER RESONANCE PLUS BACKGROUND. FOR -T < 1.0 GEV**2, CROSS SECTION IS 14 +- 2.5 MUB.
BACKWARD CROSS SECTION USING DALITZ SERIES.
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In an experiment on K--proton interactions in a hydrogen bubble chamber, the cross sections and angular distributions have been studied for elastic and charge-exchange scattering, and charged sigma hyperon production in the momentum range 90-300 MeV/c. Good agreement is found with previous cross sections except for the charge-exchange channel where the new values are 60% larger. The production distributions of the charged sigma hyperons and the polarisation of the Sigma + hyperon clearly indicate that P waves are present down to about 150 MeV/c, much lower than previously reported.
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Evidence is presented for a newK*\(\bar K\)+c.c. resonance with a mass of (1,526±6) MeV, a width of (107±15) MeV and quantum numbersIJPC=01++. We call itD′ meson. Initially it is observed as aK*\(\bar K\)+c.c. enhancement in the reactionsK−p→(Ks0K±π∓)Λ at 4.2 GeV/c. The isospin assignmentI=0 comes from its further observation in the reactionsK−p→(Ks0K±π∓)Σ0 andK−p→(Ks0K±π∓)Σ(1,385)0 but not inK−p→(K+K−π−)Σ+ orK−p→(Ks0K±π∓)Σ(1,385)+. A maximum likelihood analysis of the (K\(\bar K\)π) decay Dalitz plots in the reactionsK−p→(Ks0K±π∓) determines theJPC of theD′ meson to be 1++. A satisfactorySU(3) fit is obtained to a 1++ nonet composed of theI-1A1, theI=1/2QA with theD(1,285) and theD′(1,526) as theI=0 members having a mixing angle close to the magic one.
CROSS SECTIONS FOR PRODUCTION IN FORWARD DIRECTION IN THE REACTION CM FRAME WITH RESPECT TO K- BEAM. CORRECTION FOR UNOBSERVED (K AK PI) DECAY MODES AND FOR INVISIBLE LAMBDA AND K0 DECAYS.
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