p p annihilation cross sections into 2-, 4- and 6-prong topologies, and the exclusive annihilation cross sections for the π + π − , K + K − , π + π − π 0 , π + π + π − π − , π + π + π − π − π 0 , π + π + π + π − π − π − , and π + π + π + π − π − π − π 0 channels in the momentum range 374–680 MeV/ c were measured. No prominent structure was observed in the momentum dependence of any of the above cross sections, but a small enhancement in the cross section was observed at 490 MeV/ c corresponding to the S meson mass in the topological, and π + π − π 0 and π + π + π − π − π 0 cross sections. If the extensive of the S meson with a mass and width of 1935.5 and 2.8 MeV/ c 2 is assumed, our measurement gives a total resonant annihilation cross section into charged particles of 10.0±3.0 mb.
FIRST CROSS SECTION IS CHARGED ANNIHILATION CROSS SECTION AND IS THE SUM OF THE 2, 4, AND 6PRONG.
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The PS185 experiment at the CERN Low Energy Antiproton Ring (LEAR) has studied the reaction p ̄ p → \ ̄ gLΛ at several momenta. In this paper results from two runs with high statistics at 1.546 GeV/ c and 1.695 GeV/ c are described. Based on 4063 and 11362 analysed events, respectively, differential and integrated cross sections, polarizations and spin correlations are presented. The singlet fraction, extracted from the spin correlations, is consistent with zero at both momenta, showing that the \ ̄ gLΛ pairs are produced in a pure triplet state. A comparison of the decay asymmetry parameters of Λ and \ ̄ gL reduces the upper limits for the violation of the CP invariance for this system.
No description provided.
THE BESTFIT WITH LMAX=3, HI2=1.204.
THE BESTFIT WITH LMAX=6, HI2=0.547.
The reaction p p → Λ Σ 0 together with its charge conjugate channel (c.c.) has been measured at LEAR. The incident p momentum was 1.695 GeV/ c , corresponding to an excess energy above threshold of 14.8 MeV. Results are given for the production cross section and the differential cross section as well as for the polarization. Comparisons are made with theoretical calculations and with the reaction p p → Λ Λ .
No description provided.
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The folded differential cross sections dσdΩ(θ*)+dσdΩ(π−θ*), where θ* is the center-of-mass angle of the negatively charged outgoing particle, have been measured for the reactions p¯p→π−π+ and K−K+ at 15 incident beam momenta between 360 and 760 MeV/c with much better statistics than previous experiments. The total cross sections for these reactions, σπ−π+ and σκ−κ+, have also been obtained by integrating the folded differential cross sections. The folded differential cross sections of both reactions show a similar behavior at all measured beam momenta, characterized by a prominent peak at |cosθ*|=1. The cross section σπ−π+ shows a smooth but rapidly decreasing behavior as the beam momentum increases up to 550 MeV/c, whereas σκ−κ+ shows a smooth and flat momentum dependence. These results are compared with some theoretical calculations based on nonrelativistic quark models. Although the shape of the folded differential cross section of the p¯p→π−π+ reaction is rather well reproduced by these models, that of the p¯p→K−K+ reaction, and, in particular, the prominent peak at |cosθ*|=1 cannot be explained at all. The information from other experiments indicates that this discrepancy is most pronounced at the backward angles. Moreover, the momentum dependence of both σπ−π+ and σκ−κ+ is not satisfactorily reproduced by these models.
Folded differential cross sections.
Folded differential cross sections.
Folded differential cross sections.
This paper contains the results of a study of the reaction K−p→Λπ0 in the center-of-mass-system-energy region of 1647 to 1715 MeV. An energy-dependent partial-wave analysis was performed in this channel. Two allowable solutions were obtained. The first solution in this region contains the D13[t=0.08±0.01, Γ(ER)=44±11 MeV, and ER=1671±3 MeV] partial wave as the only resonant amplitude; the second solution contains both the P11[t=0.16±0.01, Γ(ER)=81±10 MeV, and ER=1671±2 MeV] and the D13[t=0.17±0.01, Γ(ER)=76±5 MeV, and ER=1655±2 MeV] partial wave as resonant.
No description provided.
LAMBDA DECAY-ASYMMETRY PARAMETER TIMES COEFFICIENTS OF ASSOCIATED LEGENDRE POLYNOMIAL EXPANSION.
No description provided.
The observation of 70 000 K 0 p π + events produced with K + incident momenta of 1.21, 1.29, 1.38 and 1.69 GeV/ c allows a detailed description of the production and decay of the Δ(1236) and K ∗ (892) resonances which dominate the K 0 p π + final state. No striking variations with energy are observed. The associated production of Δ and K ∗ near threshold shows striking similarities with the same production at higher energy.
INCLUDING 1 PCT SYSTEMATIC ERROR ON CORRECTIONS.
FIT 'A', ALLOWING FOR DELTA-K* INTERFERENCE (TWO OTHER FITS GIVEN IN PAPER).
S-CHANNEL HELICITY FRAME.
An analysis has been made of 64 600 events of the type K−p→K−p and 22 800 events of the type K−p→K¯0n in the Berkeley 25-in. hydrogen bubble chamber. Differential cross sections have been measured in intervals of 10 MeV/c over the momentum range 220 to 470 MeV/c. Legendre-polynomial fits to the distributions have been made, and the coefficients show structure from the resonant D-wave [Λ(1520)] and background S and P waves. No new structure is observed. The total K−p cross section determined from measurements of all final states seen in this exposure is also presented.
No description provided.
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Cross-section, angular distribution and polarization measurements are presented at six incident π + energies for the reaction π + p → K + Σ + . Results at already studied energies are compatible with existing data and roughly agree with predictions of partial-waves analyses. However, new results around 1.920 GeV are in disagreement with such predictions, casting some doubt on the determination of decay branching ratios of the T = 3 2 isobars around this mass into K + Σ + .
No description provided.
No description provided.
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Results on the channels K − p → Λ 0 η 0 , Λ 0 π 0 , Σ 0 π 0 , Λ 0 π 0 π 0 and Σ 0 π 0 π 0 are obtained in a K − p formation experiment using 1 million photographs taken in a heavy liquid bubble chamber filled with a CF 3 BrC 3 H 8 mixture. The results are compared with hydrogen bubble chamber (HBC) experiments and with experiments having full or partial gamma-ray detection. Our Λ 0 π 0 and Λ 0 + neutral cross section agree with HBC results. Our Σ 0 π 0 cross section does not exhibit a bump at 1670 MeV as previously seen in HBC experiments. Our Λ 0 π 0 π 0 data are dominated by a Σ (1385) π 0 production. Our Σ 0 π 0 π 0 data is consistent with the presence of some Σ (1405) π 0 production.
No description provided.
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No description provided.
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