Baryon resonance production in quasi-two-body reactions has been studied for the channels K + p→K°p π + , K + n π + and K + p π ° at beam momenta of 2.53, 2.76 and 3.20 GeV/ c . The production cross sections, four-momentum transfer distributions and density matrix elements are given for the Δ(1236), N ∗ (1400), N ∗ (1500) and N ∗ (1680) states. The reaction K + p→K° Δ ++ (1236) is compared to the line reversed reaction K − n → K °Δ − and the charge-exchange SU(3) sum rule for pseudo-scalar meson plus Δ(1236) is tested.
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A two-arm spectrometer for simple event topologies is described. Its main characteristics are: (i) large solid-angle acceptance for the forward emitted particles, owing to the absence of magnetic-momentum analysis; (ii) high-resolution time-of-flight measurement of the recoil proton, in the momentum-transfer range 0.05 < | t | < 1 (GeV/ c ) 2 ; (iii) high data-taking rate and on-line pattern recognition.
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K*(892)+ REGION.
High statistics data for the reaction K − p→K − π + n at 11 GeV / c have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moments analysis provides clear evidence for the production of the complete leading orbitally excited K ∗ series up through J P = 5 − . New measurements are made of the masses and widths of the 1 − K ∗ (892), 2 + K ∗ (1430 ), 3 − K ∗ (1780), and 4 + K ∗ (2060), and evidence is presented for the production of a new K ∗ state at 2382 MeV / c 2 with spin-parity 5 − .
Unnormalised acceptance corrected spherical moments.
Correlation matrices.
Correlation matrices.
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We have studied the reactions π+n→K+K−p, π+p→K+K−Δ++, and π+p→(K+K−π+)p in 10-GeV/c π+d interactions using the large-aperture solenoid spectrometer at SLAC. We measure the cross sections times branching ratios for the production of the known meson resonances f(1270), g(1690), and h(2040). We also observe a new resonance with mass 2747±32 MeV, width 195±75 MeV, and production cross section times branching ratio into K+K−π+ of 0.84±0.08 μb. The data are consistent with the quantum numbers of this state being I=1, JP=7−.
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An experiment studying the reaction π+p→Δ++π0π0 using the Argonne National Laboratory 1.5-m streamer chamber combined with a lead-glass hodoscope is described. The data were analyzed in terms of π+π−→π0π0 scattering, and the details of the extrapolation to the pole are discussed. An energy-independent amplitude analysis from threshold to 2.3 GeV is presented. In this analysis the f0(1270), the h0(2040), and a JP=2+ state at 1.8 GeV with a width of 0.280 GeV are observed. The amplitude ambiguity arising from analyses of π+π−→π+π− data in the 1.6-GeV region is resolved. An energy-dependent phase-shift analysis from 1.0 to 1.5 GeV is presented.
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The cross sections for K+p interactions at a center-of-mass energy of 3 GeV (4.3 GeV/c incident momentum) have been determined for the K+pπ+π−, K0pπ+π0, and K0π+π+n final states. The shape of the differential cross section dσdt′ for the quasi-two-body final state K*0(890)+Δ++(1236) is not a single exponential. Characteristics of the low-mass Kππ and pππ enhancements are discussed.
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DECAY MOMENTS OF THE K*0 AND DEL++.
We present the observation of a J P = 4 + , I G = 1 − state in the reaction π − p → K S 0 K − p at 10 GeV/ c measured with a non-magnetic spectrometer at the CERN proton synchrotron (PS). A spherical harmonics moments analysis of the K S 0 K − system shows a signal at ∼ 1900 MeV in the 〈 Y 7 0 〉 and 〈 Y 8 0 〉 moments, indicative of a spin 4.
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We compare production of the low mass K π -resonances by K + and K − beams in the non-charge-exchange reactions K ± p → K 0 s π ± p at 10 GeV/ c . High statistics data, obtained with the same apparatus, allow extraction of the K ∗ (890) and K ∗ (1420) production amplitudes corresponding to unnatural and natural parity exchange in the t -channel. The NPE-part dominates in both charge states. Its t -dependence shows a strong crossover at t ≈ −0.3 (GeV/ c ) 2 for the K ∗ (1420). For the K ∗ (890) the crossover is weaker but it occurs at the same value of t . This behaviour can be explained by pomeron, f and ω Regge exchange contributions to the NPE amplitude. The UPE amplitudes agree, both in normalisation and t -dependence, with the expectations of π and B exchange as isolated from data for the charge exchange reaction K − p → (K − π + )n.
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A non q q ,J PC = 1 −+ , I G =1 − meson has been observed in the study of the exclusive reaction π − p→π 0 ηn at 100 GeV. Its mass is (1406±20) MeV. Its width is (180±30) MeV.
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