We present measurements of the cross section for inclusive D and K meson production in e + e − annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e + e − annihilation at energies above 4 GeV.
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We have studied hypercharge exchange in two pairs of line-reversed reactions at 7 GeV/ c incident beam momentum in a triggered bubble chamber experiment at the SLAC Hybrid Facility. The experiment was carried out with the particular object of testing the predictions of exchange degeneracy using the same apparatus. We present differential and total cross sections for the reactions π + p → K + Σ + , K − p →π − Σ + and π + p → K + Y ∗+ (1385), K − p →π − Y ∗+ (1385) from a π + exposure of sensitivity 150 events/μb and a K − exposure of 100 events/μb. In each case we have measured the polarization of the final-state hyperon for | t |<1.0 (GeV/ c ) 2 by direct observation of its decay in the bubble chamber. We present results from an amplitude analysis of the Y ∗ (1385) reactions and find agreement with the predictions of the additive quark model. The Σ + polarization data are consistent with weak exchange degeneracy but the predicted equality of the differential cross section is not observed.
Axis error includes +- 10/10 contribution.
Axis error includes +- 10/10 contribution.
INCREASED STATISTICS OVER EARLIER RESULTS REPORTED IN P. A. BAKER ET AL., PRL 40, 678 (1978).
The inclusive γ and π0 momentum spectra from ψ(3100) decay have been measured in e+e− annihilation at SPEAR. When the γ spectrum is compared with that expected from π0 decay, an excess of high-momentum γ's is observed. This excess is compared with that predicted by quantum chromodynamics for the decay of the ψ into a γ and two gluons.
THE STATISTICAL AND SYSTEMATIC ERRORS ARE GIVEN SEPARATELY AS WELL AS COMBINED IN QUADRATURE FOR THE QUOTED TOTAL ERROR.
THE STATISTICAL AND SYSTEMATIC ERRORS ARE GIVEN SEPARATELY AS WELL AS COMBINED IN QUADRATURE FOR THE QUOTED TOTAL ERROR. SYSTEMATIC ERROR IS 17 PCT.
QUOTED ERRORS ARE STATISTICAL. SYSTEMATIC ERROR IS 20 PCT. ONLY HALF THE SUM OF THE PI+ AND PI- CROSS SECTIONS IS PLOTTED IN THE FIGURE IN THE JOURNAL.
The elastic and topological p¯p cross sections have been measured at 48.9 GeV/c in the Fermilab proportional-wire-chamber-30-in.-bubble-chamber hybrid spectrometer. The elastic cross section is 7.81±0.24 mb and the slope of the elastic differential cross section at t=0 is 13.4±0.8 GeV−2. Further, the moments of the inelastic topological-cross-section distribution are 〈nc〉=5.69±0.03, 〈nc〉D=2.10±0.02, and f2cc=1.67±0.12.
Axis error includes +- 0.0/0.0 contribution (?////DALITZ PAIRS. VEES AND GAMMA CONVERSIONS NEAR THE VERTEX WERE DETERMINED TO BE NEGLIGIBLE. LOW -T ELASTIC EVENTS//ODD-PRONG EVENTS APPARANTLY NOT CAUSED BY SECONDARY INTERACTIONS WERE MOVED TO THE NEXT HIGHER MULTIPLICITY ON THE ASSUMPTION THAT A SHORT TRACK WAS NOTVISIBLETOTAL AP-P CROSS SECTION OF 43.86+-0.25 MB FROM A.S.CARROL ET AL.PRL 33, 928(1974) WAS USED FOR NORMALIZATION).
Axis error includes +- 0.0/0.0 contribution (?////DALITZ PAIRS. VEES AND GAMMA CONVERSIONS NEAR THE VERTEX WERE DETERMINED TO BE NEGLIGIBLE. LOW -T ELASTIC EVENTS//ODD-PRONG EVENTS APPARANTLY NOT CAUSED BY SECONDARY INTERACTIONS WERE MOVED TO THE NEXT HIGHER MULTIPLICITY ON THE ASSUMPTION THAT A SHORT TRACK WAS NOTVISIBLETOTAL AP-P CROSS SECTION OF 43.86+-0.25 MB FROM A.S.CARROL ET AL.PRL 33, 928(1974) WAS USED FOR NORMALIZATION).
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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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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.
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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