We have measured the inclusive cross sections for γ, Ks0, Λ, and Λ¯ production in π+p and pp interactions at 100 GeV/c and compared various inclusive distributions of the produced γ and Ks0.
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From a large-statistics π+p experiment at 7.1 GeV/c, data are presented on the reactions π+p→ρ0Δ++(1238) and π+p→ωΔ++(1238). Cross sections, differential cross sections, and vector-meson single-density-matrix elements are presented and a general comparison of the production properties of the two reactions is given. In addition to (ρ,ω)Δ++(1238) production there is also strong evidence for production of a π+p enhancement with mass ∼ 1880 MeV, Γ∼200 MeV, and J≥72 produced in association with the ρ and ω resonances. Detailed properties of this structure are presented and its production mechanism is compared with that of the corresponding Δ(1238) reactions. This state is also observed in the reaction K+p→K*0(890)Δ++(1880) at 12.0 GeV/c, for which data are also presented.
STATISTICAL ERRORS ONLY.
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JACKSON FRAME.
The experimental upper limit for the diffractive photoproduction of the ψ(3105) is 29 nb, with 90% confidence, at an average photon energy of 18.2 GeV.
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We have done a JP analysis of the low-mass π+ω system, using the reaction π+p→π+ωp at 7.1 GeV/c. We find that the B resonance cannot be JP=0− and must belong to the unnatural-parity series (1+, 2−, 3+,...), regardless of the amount of interference between the B and the background. If we assume that the B does not interfere with the background, we find that all JP states for the resonance are rejected except for 1+. Even if interference effects are allowed in the analysis, a good fit with reasonable parameters is obtained only with the 1+ hypothesis for the B meson. In an appendix, we give relevant theoretical formulas appropriate for a πω system with any number of spin-parity states and arbitrary degrees of interference among them.
TAKING INTO ACCOUNT 0- AND 1+ SMOOTH BACKGROUND UNDER THE B MESON. EVENTS WITH 1.08 < M(PI+ OMEGA) < 1.38 GEV.
Total cross sections of π± and K± on protons and deuterons have been measured at 50, 100, 150, and 200 GeV/c. All of the cross sections rise with increasing momentum.
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PARTICLE-ANTIPARTICLE CROSS SECTION DIFFERENCES - SOME COMMON ERRORS CANCEL.
Proton and antiproton total cross sections on protons and deuterons have been measured at 50, 100, 150, and 200 GeV/c. The proton cross sections rise with increasing momentum. Antiproton cross sections fall with increasing momentum, but the rate of fall decreases between 50 and 150 GeV/c, and from 150 to 200 GeV/c there is little change in cross section.
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ANTIPARTICLE-PARTICLE CROSS SECTION DIFFERENCES.
A spin and parity decomposition is presented of the (π+π+π−) final state formed opposite a proton by incident 13-GeV/c π+ mesons. The A3 enhancement is identified as the 2− amplitude decaying to f0π+ via an S wave. A change in relative phase is noted between the 2−S amplitude and the other principal contributions; this is not incompatible with analyses of the (3π)− system. The method employs the University of Illinois three-body partialwave analysis program.
A3+ DEFINED AS JP=2- S-WAVE.
The missing mass spectrum opposite the proton in a 750 000 picture exposure, 13 GeV/ c π + p bubble chamber experiment, is investigated in two and four pion channels for structures observed or denied by boson spectrometers at the same energy in the reaction π − p→X − p.
BREIT-WIGNER FITS.
FOR 1.6 < M(4PI) < 1.8 GEV.
A recent spin-parity analysis of the π + π + π − system formed opposite a proton and a coherent deuteron by incident 13 GeV/ c 2 π + mesons, is extended to a three-pion mass of 1.9 GeV/ c . Relative proportions of the contributing partial waves are presented, from threshold, and the A 3 region is discussed in detail. Contrary to results with the (3 π ) − system, a change in phase is noted for the 2 − amplitude decaying to f 0 π + via am S-wave.
FOR A3+ DEFINED AS 2+ S-WAVE WITH 1.5 < M(3PI) < 1.8 GEV).
CONSTRAINT IMPLIES RHO(11) + RHO(1-1) = 0.
CONSTRAINT IMPLIES RHO(11) + RHO(1-1) = 0.
The reactions of positive pions with protons yielding four charged particles and one or more neutrals have been studied, especially the reaction π+p→Δ++ω0→pπ+π+π−π0. The results presented in this paper were obtained from a 100 000-picture exposure of the Argonne-MURA 30-in. liquid hydrogen bubble chamber, with a beam of incident pions of 4.09−GeVc momentum. Comparisons have been made with corresponding results of other experiments at various incident beam momenta, and with the predictions of some theoretical models of the π+p interaction.
INCLUDING CORRECTIONS FOR BACKGROUND.
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