A comprehensive measurement of the differential cross section for π±p and pp elastic scattering has been made at large center-of-mass angles. π−p and pp scattering were measured with incident laboratory momenta ranging from 2 to 9.5 GeV/c. π+p scattering was measured with momenta from 2 to 6.3 GeV/c. Scattering angles were in the range −0.3≲cosθc.m.≲0.4. The results of the experiment are compared to constituent models and statistical models.
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This paper presents the results of a study of the dominant neutral final states from π−p interactions. The data were obtained in an experiment performed at the Brookhaven National Laboratory Alternating Gradient Synchrotron, using a set of steel-plate optical spark chambers surrounding a liquid-hydrogen target. We present differential and total cross sections for the reactions (1) π−p→n+π0 and (2) π−p→n+η0(η0→2γ) and total cross sections for the reactions (3) π−p→n+kπ0 (k=2, 3, 4, and 5) and (4) π−p→all neutrals for eighteen values of beam momentum in the interval 1.3 to 4.0 GeV/c. The angular distributions for (1) and (2) have been analyzed in terms of expansions in Legendre polynomials, the coefficients for which are also given.
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SIG = 4*PI*LEG(L=0).
FORWARD DIFFERENTIAL CROSS SECTION CALCULATED FROM LEGENDRE POLYNOMIAL COEFFICIENTS AND ERROR MATRICES.
We have identified 262 doubly tagged two-photon events. A subset of the data shows an enhancement of 21 events in the inclusive two-photon mass squared distribution between 0.8 and 2.2 GeV 2 . If these events result from spin 2 resonance production then Γ γγ = 9.5 ± 3.9 ± 2.4 keV (statistical and systematic). From another subset of 58 events in which the final state could be classified we determine the two-photon hadron to muon cross section ratio R γγ = 1.1 ± 0.3 ± 0.3.
ELECTRON BEAM ENERGIES OF 3.0 AND 3.6 GEV.
K ∗0 (890) production in the hyperchange exchange reaction π − p → K ∗0 (890) Λ 0 Σ 0 at 10 GeV/ c (28 448 events) is discussed. An amplitude analysis in the t ′ range up to 1 GeV 2 shows that the production mechanism is dominated by natural parity exchange (∼84%). Comparisons are made with predictions from a Regge model and a quark model.
DENSITY MATRIX ELEMENTS IN THE GOTTFRIED-JACKSON SYSTEM ALLOWING FOR COHERENT S-WAVE BACKGROUND TO P-WAVE BREIT-WIGNER K*(892)0 RESONANCE.
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d2σdΩdT for π+ mesons produced in π−p→π−π+n was measured at seven incident energies between 203 and 357 MeV and the integrated reaction cross section was calculated. The matrix element, when extrapolated to threshold and compared with soft-pion calculations, determined the chiral-symmetry-breaking parameter ξ=0.05±0.26, which is consistent with the Weinberg Lagrangian. The large hard-pion contributions at 203 MeV demonstrated the absolute necessity for comparing at threshold.
Axis error includes +- 0.0/0.0 contribution (?////).
This Letter compares neutral-current and charged-current scaling-variable distributions in neutrino-nucleon interactions induced by a narrow-band beam at Brookhaven National Laboratory; the x distribution of neutral-current events has been reported previously. The first measurement of flux-normalized neutrino cross sections from a narrow-band beam in the energy range Eν=3−9 GeV is also presented.
Measured charged current total cross section.
Results are presented from a study of inclusive neutral strange particle production by a 147 GeV/ c tagged π + /K + /p beam in the Fermilab 30-inch hydrogen bubble chamber. The experiment made use of the proportional hybrid spectrometer system. Results are based on 995 K S 0 , 485 Λ, and 83 Λ found in a sample of 132 000 pictures. Cross sections are given for inclusive production of these particles by each of the three beam particles, and comparisons are made with measurements at other energies. Topological cross sections are also calculated, and KNO multiplicity scaling is investigated. Distributions are presented of invariant cross sections as functions of the Feynman scaling variable x and c.m. rapidity y . The transverse momentum-squared distributions with their fitted slopes are also given. Comparisons are made of the production characteristics for the three beam types.
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The average transverse momentum squared, 〈 p ⊥ 2 〉, of hadrons is studied as a function of W 2 and of Q 2 for ν and ν interactions on an isoscalar target. An increase of 〈 p ⊥ 2 〉 with W 2 is observed for the hadrons emitted forward in the hadronic c.m.s. The p ⊥ dependence of the fragmentation function is found to factorise from the structure function at fixed W , but does not factorise at fixed Q 2 . Unlike the case of forward-going particles, the 〈 p ⊥ 2 〉 of hadrons going backward in the c.m.s. shows no strong dependence on W 2 .
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The first measurements are reported of the asymmetry in resonance-region scattering of longitudinally polarized electrons by longitudinally polarized protons. Data have been obtained at Q2=0.5 and 1.5 (GeV/c)2 in the missing-mass range W=1.1−1.9 GeV. Results are compatible with a multipole analysis of single-pion electroproduction. The spin-dependent behavior is consistent with a duality mechanism as in the unpolarized case.
ELECTRON ASYMMETRY AT Q**2 ABOUT 0.5 GEV**2.
ELECTRON ASYMMETRY AT Q**2 ABOUT 1.5 GEV**2.
PHOTON ASYMMETRY AT Q**2 ABOUT 0.5 GEV**2.
We have measured the polarization for elastic scattering in the reaction π−p→π−p at 2.93 and 3.25 GeV/c using a polarized proton target and multiwire proportional chambers (MWPC's) with emphasis on large-angle scattering. Events were selected by fast scintillation-counter logic. Beam trajectories were measured with four MWPC's and the scattered-particle angles were measured with one or two MWPC's; elastic events were determined by coplanarity and angle-angle correlations. The polarization is in agreement with previous measurements below |t|=2.0 (GeV/c)2, and crosses from negative to positive near the secondary dip in the differential cross section dσdt. In the backward region, an energy dependence appears with the polarization being large and negative at 2.93 GeV/c and consistent with zero at 3.25 GeV/c.
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