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Show moreThe reactions pp→N*++(1238)n and p̅ n→N̅ *--(1238)p at 2.8 GeV/c incident laboratory momentum are analyzed with the Brookhaven National Laboratory 20-in. bubble chamber. Isobar and anti-isobar production differential cross sections and decay angular distributions are compared with the predictions of an absorptive single-pion-exchange model. The absolute values, shapes, and ratios of the cross sections are in good agreement with the theory when the absorptive parameters γ1 and γ2 are 0.033 and 0.016 for the p̅ n reaction, and 0.057 and 0.019, respectively, for the pp reaction.
The reactions pp→N*++(1238)n and p̅ n→N̅ *--(1238)p at 2.8 GeV/c incident laboratory momentum are analyzed with the Brookhaven National Laboratory 20-in. bubble chamber. Isobar and anti-isobar production differential cross sections and decay angular distributions are compared with the predictions of an absorptive single-pion-exchange model. The absolute values, shapes, and ratios of the cross sections are in good agreement with the theory when the absorptive parameters γ1 and γ2 are 0.033 and 0.016 for the p̅ n reaction, and 0.057 and 0.019, respectively, for the pp reaction.
Phys. Rev. 162, 1320–1322 (1967)
http://link.aps.org/doi/10.1103/PhysRev.162.1320
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Show moreA novel method of analysis which eliminates the combinatorial background in searches for states produced in p¯n annihilations and in association with a recoil π- is presented. The difference between π- and π+ spectra on p¯n annihilations is the spectrum of the recoiling π- or difference spectrum. We applied this analysis to the exclusive channels p¯n→2π-π+, 2π-π+π0, 3π-2π+. A new prominent state of mass and width ≃1480 and 100 MeV/c2 is present in the first and dominates the third channel. These three channels are interpreted in terms of two-body intermediate states only. The suppression or absence of ‘‘direct’’ annihilation is consistent with theoretical models which view the annihilation as a short-range (0.1 fm) phenomenon.
Phys. Rev. Lett. 56, 215–218 (1986)
http://link.aps.org/doi/10.1103/PhysRevLett.56.215
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Phys. Lett. 19 65 (1965
Show moreThis paper presents an analysis of the features observed in the neutral mass spectrum of events of this type: π+d - pp neutrals
Phys. Lett. 19 65 (1965)
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Show moreInclusive production of Λ and K0 in pp interactions at 12 GeV/c has been studied in an exposure of the Argonne National Laboratory 12-foot bubble chamber to a 50% transversely polarized proton beam. Beam-polarization-induced asymmetries are observed for both K0 and Λ production in the forward direction.
Phys. Rev. D 21, 10–11 (1980)
http://link.aps.org/doi/10.1103/PhysRevD.21.10
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Show moreInclusive charged-pion spectra from p¯d annihilations at rest have been measured in a high-statistics experiment in search of broad states. Analysis of these spectra reveals an enhancement of the π- spectrum at 315 MeV/c. This may be interpreted as a production of a new state of mass 1485 MeV/c2 and width at most 200 MeV/c2 recoiling against the π-. This quasi two-body final state accounts for a large fraction of the p¯n annihilations.
Phys. Rev. Lett. 56, 211–214 (1986)
http://link.aps.org/doi/10.1103/PhysRevLett.56.211
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http://link.aps.org/doi/10.1103/PhysRevLett.10.457
Show moreWe present evidence for the decay A20→ωπ+π0 with a branching ratio Γ(A2→ωππ)/Γ(A2→ρπ)=0.28±0.09 and for the decay ω(1675)→ωπ+π- with a branching ratio Γ(ω(1975)→ωπ+π-)/Γ(ω(1675)→ρπ)=0.47±0.18. Evidence is given for an intermediate B(1235)π state in the ω(1675) decay.
Phys. Rev. Lett. 32, 260–264 (1974)
http://link.aps.org/doi/10.1103/PhysRevLett.32.260
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Show moreForward-angle differential cross sections for the 165Ho(π+,π0)165Er(IAS) reaction have been measured at Tπ=98.0, 163.2, and 228.3 MeV in the angular range & ≲14°. The shapes of the angular distributions at 98.0 and 163.2 MeV are compared to predictions arising from the strong absorption model of pion single-charge exchange scattering. Extrapolated 0° cross sections are compared with trends previously established with mostly spherical and near-spherical nuclei. The measurement demonstrates the possibility of using the (π+,π0) reaction for studying neutron density deformations in oriented 165Ho.
Phys. Rev. C 35, 1382–1387 (1987)
http://link.aps.org/doi/10.1103/PhysRevC.35.1382
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Show moreWe have studied antiproton elastic scattering on Al, Cu, and Pb for two incident momenta: 514 and 633 MeV/c. The angular region covered extends from the forward Coulomb region to approximately 30 deg. The differential cross sections were analyzed using a nonrelativistic optical potential of the Woods-Saxon form, with the imaginary shape taken from electron scattering data. We obtained fits for the strengths of the real and imaginary parts of the potential, (V0, W0), of (51, 116) MeV for Al, (12, 71) MeV for Cu, and (12, 278) MeV for Pb.
Phys. Rev. C 30, 1080–1083 (1984)
http://link.aps.org/doi/10.1103/PhysRevC.30.1080
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Show moreWe have measured the ratio of the real to the imaginary parts of the p̅ p forward-scattering amplitude in the incident-momentum range 360 to 650 MeV/c. These results are in good agreement with predictions of the Paris nucleon-antinucleon potential model which include spin-flip effects.
Phys. Rev. Lett. 54, 518–521 (1985)
http://link.aps.org/doi/10.1103/PhysRevLett.54.518
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Show moreThe branching ratio for the Λ weak radiative decay has been measured to be B(Λ→n+γ)/(Λ→anything) =[1.78±0.24(stat)±0.160.14(syst)]×10-3. A low-energy kaon beam was used to produce the Λ hyperons via the reaction K-+p→Λ+π0 at rest. Photons from the signal channel and π0 decay were detected with a NaI(Tl) array. The final spectrum contains 287 events after background subtraction, an order of magnitude more events than from the only previous measurement.
Phys. Rev. Lett. 69, 414–417 (1992)
http://link.aps.org/doi/10.1103/PhysRevLett.69.414
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Phys. Rev. Lett. 31, 562–565 (
Show moreWe have observed the decay mode f0→π+π+π-π- and determined the branching ratio Γ(f0→π+π+π-π-)/Γ(f0→π+π-)=(5.5±1.0)×10-2.
Phys. Rev. Lett. 31, 562–565 (1973)
http://link.aps.org/doi/10.1103/PhysRevLett.31.562
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http://link.aps.org/doi/10.1103/PhysRevLett.7.196
Show more3600 two-pronged events, obtained in p-p interactions at 2 Bev in the BNL 20-in. hydrogen bubble chamber, have been analyzed. Cross sections have been measured for elastic scattering, for the two modes of single-pion production, p+p→p+n+π+, p+p→p+p+π0, and for strange-particle production. The branching ratio for the two one-pion production reactions is σ(pnπ+)/σ(ppπ0)=4.17±0.25. Momentum distributions and Q values indicate that single-pion production proceeds almost entirely through the (3/2, 3/2) resonant state. The data have been considered in terms of the extended isobar model and also a one-pion exchange model for production. The branching ratio and momentum distributions can be explained by including a small effect from the I=1/2 resonant state in addition to the dominant I=3/2 resonance. The c.m. angular distribution of the nucleons in single-pion production shows very marked backward-forward peaking indicating a one-pion exchange mechanism. Absolute differential cross sections as a function of laboratory kinetic energy have been calculated from Selleri's equation for the pnπ+ reaction. There is good agreement with the data for low four-momentum transfers [q2<0.15(Bev/c)2], but for higher momentum transfers the theoretical cross sections are larger than the experimental cross sections.
http://link.aps.org/doi/10.1103/PhysRev.125.2082
Phys. Rev. 125, 2082–2090 (1962)
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Phys. Rev. Lett. 6, 62
Show morePart of the work reported here was done by J. R. Sanford who held a National Science Foundation Cooperative Graduate Fellowship.
Phys. Rev. Lett. 6, 624–625 (1961)
http://link.aps.org/doi/10.1103/PhysRevLett.6.624
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Show moreDouble pion production has been observed in 871 MeV π−-p interactions in a hydrogen bubble chamber. A total of 347 events were identified as π−+p→π−+p+π−+π+ corresponding to a partial cross-section of (0.30±0.03) mb. The results are compared to a one-pion-exchange model and to a statistical model with (π+p) isobar formation. The latter model seems to explain deviations from four-body phase space observed in the experimental distributions.
Il Nuovo Cimento (1955-1965) Volume 32, Number 1, 18-24
http://www.springerlink.com/content/9m2828m2642m5ul3/
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Show moreThe photon spectrum from K- stopping in liquid hydrogen has been measured with a high-resolution (1.5% FWHM at 300 MeV) NaI(Tl) detector. The branching ratios for K-p→Λγ (Eγ=281.4 MeV) and K-p→Σ0γ (Eγ=219.5 MEV) were obtained. The results are RΛγ=(0.86±0.07-0.08+0.1)×10-3 and RΣ0γ=(1.44±0.20-0.10±0.12)×10-3 where the first error is statistical and the second systematic. These results are not in good agreement with published predictions or with previous Λγ measurements.
Phys. Rev. Lett. 63, 1352–1355 (1989)
http://link.aps.org/doi/10.1103/PhysRevLett.63.1352
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Show moreThe photon spectrum from K-d→Λnγ at rest has been measured for the first time. We obtained the branching ratio, in the end-point region, of (1.89±0.12±0.28)×10-3 where the first error is statistical and the second is systematic. We have found that the shape of the photon energy spectrum is consistent with the distribution calculated by Workman and Fearing with Λn scattering lengths and effective ranges predicted by the Nijmegen group.
Phys. Rev. C 42, R475–R478 (1990)
http://link.aps.org/doi/10.1103/PhysRevC.42.R475
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Show moreResonant structure is studied in the 1.5-to-1.9-GeV mass region of the neutral four-pion system in the reaction π+n→pπ+π+π-π- at 6 GeV/c incident momentum. The ρ0 and A2± content are determined as a function of the four-pion mass. The 4π mass spectrum is best fitted by two resonances, both of which decay predominantly into ρ0π+π-, each with evidence for an appreciable A2π component.
Phys. Rev. D 23, 595–599 (1981)
http://link.aps.org/doi/10.1103/PhysRevD.23.595
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Show moreThe interaction between antiprotons and protons has been studied in the range 1910 to 1990 MeV center-of-mass energy in a drift-chamber experiment at the Brookhaven Alternating Gradient Synchrotron. The total cross section has been determined at eleven different incident momenta, and the elastic cross section between 8 and 30 deg in the laboratory has been measured with an energy resolution of about 5 MeV. The cross section for annihilation into charged mesons has also been measured, with the same resolution. There is no evidence in any of these channels for the existence of a narrow resonance.
Phys. Rev. D 34, 3332–3342 (1986)
http://link.aps.org/doi/10.1103/PhysRevD.34.3332
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