The real part of the forward amplitude for Compton scattering on protons was measured through the interference between the Compton and Bethe-Heithler amplitudes by detecting the zero-degree electron pairs asymmetrically. The measurement was made at an average photon energy of 〈k〉=2.2 GeV, and an average momentum transfer to the recoil proton 〈t〉=−0.027 (GeV/c)2. The result confirms the prediction of the Kramers-Kronig relation.
No description provided.
The polarization parameter P(t) for the reaction π−p→π0n has been measured at 3.5 and 5.0 GeV/c over the range 0.2<~−t<~1.8 (GeV/c)2. The two γ rays from the π0 decay were detected in a large lead-glass hodoscope. The results agree with the positive polarization values found in earlier Argonne National Laboratory data at −t<0.35 (GeV/c)2. P(t) drops to a small value near t=−0.6 (GeV/c)2 and remains the same out to t=−1.8 (GeV/c)2.
DATA POINTS MEASURED FROM SMALL GRAPH.
We have measured the total cross section for electron-positron annihilation into three or more hadrons, with at least two charged particles in the final state. The measurement was made at a center-of-mass energy of 4 GeV with a 2π−sr nonmagnetic detector. With 88 events detected, we obtain a model-independent lower limit on the hadron production cross section of 9.6 ± 1.4 nb; a calculation of detection efficiency based on invariant phase-space production of pions leads to a total cross section of 26 ± 6 nb. This cross section is 4.7 ± 1.1 times the theoretical total cross section for e+e−→μ+μ−. The average charged multiplicity is n¯=4.2±0.6.
No description provided.
The results presented in this paper are obtained from an analysis of bubble-chamber pictures of K−d interactions at an incident K− momentum of 5.5 GeV/c. Generally, the quasitwo-body final states are produced peripherally, with a small backward peak occurring in some of the final states. The final states Σ−ω, Σ−ρ0, and Σ−φ appear to be produced primarily by vector-meson exchange. In the final state Λ(1520)π− the decay distributions of the Λ(1520) hyperon are found to be consistent with a vector-exchagne production process with M2 coupling at the nucleon vertex. The predictions of the independent-quark model and of other symmetry schemes, namely that the forward cross sections for Σ−ρ0, Σ−ω, Σ−φ production be in the ratios 1: 1: 2, are not inconsistent with our experimental values.
No description provided.
FRACTIONAL FORWARD HYPERON CROSS SECTION AFTER BACKGROUND SUBTRACTION.
No description provided.
We observe an energy-dependent polarization of the Σ+ produced in the reaction π+n→K0Σ+ at incident beam momenta between 1.1 and 2.4 GeV/c. These data form a significant source of information on the Σ− polarization in the charge-symmetric reaction π−p→K+Σ−.
INTEGRATED OVER ALL PRODUCTION ANGLES.
No description provided.
Measurements are presented of the recoil-proton polarization for π0 photoproduction angles near 64° in the c.m. system. The steep angular dependence observed by others at lower energies persists to at least 1500 MeV, and the polarization crosses through zero near 63° over the entire 900-1600-MeV energy interval. Summary fits are made to available recoil-proton polarization data, 950-1250 MeV, and are found to require terms of order cos3θ, but no higher.
Axis error includes +- 0.0/0.0 contribution (?////).
We have studied η′ production using a π+ beam incident on deuterium in the 72-in. bubble chamber, with beam momenta from 1.1 to 2.4 GeVc. Cross sections for reactions leading to five- and six-pronged final states are presented. We observe η′ production in the reaction π+d→ppη′, with the decay mode η′→π+π−η. The cross section for π+n→pη′ (studied in the impulse approximation) is observed to rise to a maximum of about 100 μb at 2.2-GeV c.m. energy. The production angular distribution develops peripheral peaking with increasing energy.
No description provided.
The results of an experiment performed at Adone, the 2×1.5-GeV e+e− Frascati storage ring, are presented. During ∼ 1500 hours of running time a total of 5164 electron-positron elastic scattering events (integrated luminosity L=3.5×1035 cm−2) and 605 noncoplanar events from the reaction e+e−→a±+b±+anything (effective integrated luminosity L=2.5×1035 cm−2) have been collected at c.m. energies ranging from 1.4 to 2.4 GeV. Over the energy range explored (1.4-2.4 GeV), corresponding to an average q2 ranging from 0.8 to 2.4 (GeV/c)2, the yield of wide-angle (60°<θ<120°) electron-positron elastic scattering events is found to be in good agreement with the predictions of quantum electrodynamics (QED) (R=σexpσQED=1.05±0.04). The noncoplanar events appear to be of a hadronic nature and are produced with a much higher cross section than predicted on the basis of ρ, ω, φ dominance at these energies. The total cross section for the reaction e+e−→a±b±+anything shows a rapid increase to ∼ 90 nb between 1.0 and 1.5 GeV and falls off slowly to ∼ 50 nb at 2.4 GeV. Cross sections for some of the channels contributing to this multihadron process (e+e−→π+π−π+π−, e+e−→π+π−π+π−+neutrals, e+e−→3π+3π−) have been determined and are reported.
DATA VALUES MEASURED FROM GRAPH IN JOURNAL.
VALUES OF R CALCULATED FROM TOTAL CROSS SECTION.
Differential cross sections for coherent π0-photoproduction from deuterium have been measured in the photon energy range from 240 to 400 MeV and for pion c.m. angles between 70 ° and 160 °. The recoil deuterons were analysed in angle and momentum by a magnetic spectrometer. The cross sections obtained were higher by a factor of about 2 compared with the results from Stanford [7], the only data available up to now in the first resonance region. Below the resonance the measured cross sections give a smooth extension to the low energy data from Glasgow [5] and Orsay [6].
No description provided.
Photoproduction of π−-mesons on deuteron has been studied in the first resonance region with an annihilation photon beam with adjustable peak energy (from 250 MeV to 400 MeV). A coincidence detection of both outgoing π−-meson and forward proton has been performed with a set of 9 multiwire proportional chambers (1700 wires) inside the gap of a spectrometer. The momentum of the second proton is computed from three-body kinematics; their distribution is found in excellent agreement with the spectator model, even at the top of the resonance. The differential cross-sections of π− have been measured from 100° to 180° (center of mass); they are in reasonable agreement with conventional multipole calculations and do not indicate an appreciable isotensor term.
No description provided.
No description provided.
No description provided.
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