Differential cross sections for $K^-$ radiative capture in flight on the proton, leading to the $\gamma\Lambda$ and $\gamma\Sigma^0$ final states, have been measured at eight $K^-$ momenta between 514 and 750 MeV/$c$. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated $K/\pi$ beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the $\gamma\Sigma^0$ final state is dominated by hyperonresonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the $\gamma\Lambda$ final state, on the other hand, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.
Differential cross section for the K- P --> GAMMA LAMBDA reaction at thelower beam momenta.
Differential cross section for the K- P --> GAMMA LAMBDA reaction at thehigher beam momenta.
Differential cross section for the K- P --> GAMMA SIGMA0 reaction at thelower beam momenta.
A study of the reaction pi+ + d --> p + p has been performed in the energy range of 18 - 44 MeV. Total cross sections and differential cross sections at six angles have been measured at 15 energies with an energy increment of 1 - 2 MeV. This is the most systematic data set in this energy range. No structure in the energy dependence of the cross section has been observed within the accuracy of this experiment.
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Measurements of the total and differential cross sections of the reaction p p → K s K s are presented for values of s in the region near 2230 MeV. The 18 energies of the scan were chosen to permit a sensitive search for resonant structure related to the ¢E(2230) state in a channel with a minimal non-resonant background. No such structure is observed. Stringent limits for the branching ratio are set based on various assumptions for the width and spin of the ¢E.
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Legendre polynomial fit to dsig/domega to order 0.
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.
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THE BESTFIT WITH LMAX=3, HI2=1.204.
THE BESTFIT WITH LMAX=6, HI2=0.547.
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.
Differential cross sections have been measured for π+p and π−p elastic scattering at 378, 408, 427, 471, 509, 547, 586, 625, 657, and 687 MeV/c in the angular range -0.8<cosθc.m.<0.8. The scattered pion and recoil proton were detected in coincidence using scintillation-counter hodoscopes. A liquid-hydrogen target was used except for measurements at forward angles, in which a CH2 target was used. Statistical uncertainties in the data are typically less than 1%. Systematic uncertainties in acceptance and detection efficiency are estimated to be 1%. Absolute normalization uncertainties are 2–3 % for most of the data. The measurements are compared with previous data and with the results of recent partial-wave analyses. The data are fit with Legendre expansions from which total elastic cross sections are obtained.
Normalisation uncertainty = 3.1 pct.
Normalisation uncertainty = 4.1 pct.
Normalisation uncertainty = 2.1 pct.
Differential cross sections for the process pi +d to pp at seven energies in the region Tpi =280-450 MeV and in the angular range theta * approximately=4-90 degrees have been measured on the LNPI synchrocyclotron. The results include 94 new data points. The measurements have been carried out using a ten-channel hodoscope set-up. Statistical errors are between 2.5% and 7.8% depending on the scattering angle and Tpi . The data obtained indicate that there is an essential contribution from the partial wave with orbital angular momentum l=3 over the whole energy range considered. The authors also observe a noticeable contribution from the l=4 partial wave to the differential cross sections of the pi +d to pp reaction from Tpi >or=357 MeV. The total cross sections for the process pi +d to pp are also presented.
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pp interactions at 11 momenta in the range 0.9 to 2.0 GeV/ c have been studied. The elastic angular distributions, covering the c.m. angular range 22°–90°, agree in general with Hoshizaki's phase-shift analysis which shows the looping 1 D in and 3 F 3 amplitudes in the Argand diagram. About 80% of pn π + events come from the n Δ ++ state at all momenta above 1.2 GeV/ c . The behavior of the density matrix elements of the Δ ++ show no momentum or angular dependence. A large fraction of pp π 0 events also come from the p Δ + state at all momenta above 1.2 GeV/ c . The behavior of the Δ + density matrix elements is similar to that for the case of Δ ++ .
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The unpolarized differential cross section for the reaction pp→π + d has been measured at SIN at seven energies between 514 and 583 MeV. Data are presented in terms of a Legendre polynomial expansion. An observed strong energy dependence of the 4th order coefficient can be understood as a threshold phenomenon in a phenomenological NΔ resonant description. No evidence was found for a 1 D 2 dibaryon resonance near 600 MeV.
LEGENDRE POLYNOMIAL EXPANSION COEFFICIENTS DEFINED BY 4*PI*D(SIG)/DOMEGA = LEG(L=0)*P0 + LEG(L=2)*P2 + LEG(L=4)*P4. THUS, LEG(L=0) IS INTEGRATED CROSS SECTION SIG.
COEFFICIENTS OF COS(THETA)**2 EXPANSION OF 32*PI*D(SIG)/DOMEGA.
Data are presented from a high statistics bubble chamber experiment to K − p interactions over the c.m. energy range 1720 to 1796 MeV. Channel cross sections, differential cross sections and, where appropriate, polarisation distributions have been obtained for the final states K − p , K 0 n , π 0 Λ and π ± Σ ∓ . These data are compared with those from previously published experiments and with the predictions from the RL-IC 77 partial-wave amplitudes for each of these channels.
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EXTRAPOLATED FORWARD AND BACKWARD DIFFERENTIAL CROSS SECTIONS.
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