We have observed the D(1285), E(1420) and δ(975) mesons produced in 12 and 15 GeV/ c π − p interactions at the CERN Omega Spectrometer. Production cross sections and decay branching ratios are presented. Analysis of the decay D(1285) → δ (975) π favours a spin-parity assignment of 1 + .
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CORRECTED FOR DECAY MODES OTHER THAN <ETA PI+ PI-> AND FOR THE UNOBSERVED PARTS OF THE T-DISTRIBUTION.
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We have measured inclusive γ and π0 production in multiprong events produced by e+e− annihilation in the center-of-mass energy range 4.9 to 7.4 GeV. We find the π0 inclusive cross section to be consistent in shape and normalization with half the charged-π cross section between x=0.15 and 0.60, with an integrated inclusive cross-section ratio of σ(π0)|σ(π+)+σ(π−)|=0.47±0.10.
NUMERICAL VALUES OF DATA FROM THIS EXPERIMENT HAVE NOT BEEN KEPT (M. L. PERL, PRIV COMM, 3 MAY 1979).
Neutral-pion production in pp interactions has been studied using 8000 photon conversions in the Fermilab 15-ft bubble chamber. Inclusive π0 multiplicity moments and ππ correlation integrals are presented; f200 is determined to be + 3.0±0.8. For the semi-inclusive π0 multiplicity distributions we find 〈n(π0)〉n− to increase with n−, while the dispersions are n− independent. Results on f2−0, f200, and f2,n−00 are compared to predictions of simple cluster models.
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We present results for the reactions νp→μ−π+p and νp→μ−K+p at energies above 5 GeV. The average cross section for the first reaction between 15 and 40 GeV is (0.80±0.12) × 10−38 cm2 and for events with Mπ+p<1.4 GeV is (0.55±0.08) × 10−38 cm2. The ratio of the cross section for the second reaction to that for the first is 0.017±0.010.
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RAPIDITY IS MEASURED IN 'QUARK' REST FRAME DEFINED AS Y(Q)=Y(LAB)-LOG(W**2/M**2) WHERE Y(LAB)=0.5*LOG((E+PL)/(E-PL)).
Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e + e − annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e + e − → D or D + anything) at 7 GeV is 4.8±1.3 nb.
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SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
Final results of our measurements of elastic proton-proton scattering at the CERN Intersecting Storage Rings (ISR) for c.m. energies √ s from 23 to 63 GeV and momentum transfers | t | from 0.8 to 10 GeV 2 are presented. Absolute differential cross sections have been obtained using the split-field magnet detector facility (SFM) at the five standard energies for integrated luminosities ranging from 0.3 to 4.9 (pb) −1 . The rising total cross section is found to define a scale for diffractive phenomena near the forward peak, including the position of the diffraction minimum near t = −1.4 GeV 2 . The cross section at the minimum is strongly energy dependent, approximately as the ratio of the real to imaginary part of the scattering amplitude in the forward direction. The phase of the scattering amplitude is found to change sign near the minimum. The component of diffraction scattering beyond the second maximum has a much weaker t -dependence than expected in simple eikonal or constituent pictures connecting this region to the forward peak. A further break in slope is observed near t = −6 GeV 2 . There is no evidence for another minimum for t values up to 10 GeV 2 .
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Approximately 350 A 2 + events have been observed in the reaction π + p → K + K S 0 p ( K S 0 → π + π − ) at an incident π + laboratory momentum of 12.7 GeV/ c . The events are distributed over a range of four-momentum transfer squared 0.01 ⩽ − t ⩽ 0.60 (GeV/ c ) 2 and K + K S 0 mass 1.11 ⩽ m K + K S 0 ⩽ 1.51 GeV . A Breit-Wigner fit to the mass spectrum yields a mass for the A 2 + , m A 2 + = 1.324 ± 0.005 GeV, and a width Γ 0 = 0.110 ± 0.018 GeV. We find a cross section σ ( π + p → A 2 + p) = 1.71 ± 0.30 μb referring to the above-mentioned mass and t range and A 2 + → K + K S O with K S 0 → π + π − . The spin-space density matrix in the Gottfried-Jackson frame is practically saturated by ϱ 11 ⋍ ϱ 1−1 = 1 2 suggesting natural parity exchanges only. There is a forward dip in the angular distribution consistent with dominance of s -channel net helicity flip amplitudes and ϱ and f Regge exchanges suffice to describe adequately our differential cross sections.
SUBTRACTED BACKGROUND IS PHASE SPACE. FITTED D(SIG)/DT SLOPE IS 9.5 +- 0.9 GEV**-2.
SUBTRACTED BACKGROUND IS AN S-WAVE WITH SLOPE OF 8 GEV**-2. FITTED D(SIG)/DT SLOPE IS 6.9 +- 0.6 GEV**-2.
FROM D(SIG)/DT. ERROR INCLUDES 15 PCT SCALE ERROR ADDED QUADRATICALLY.
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We have determined the coherent KS regeneration amplitudes on various nuclei, from 20 to 140 GeV/c, using a particularly systematics-free technique. Our results are well represented by |(f−f¯)k|=2.23A0.758p−0.614 mb. This p dependence corresponds to an effective "nuclear" intercept ``αω(0)''=0.386±0.009, whereas the elementary value is αω(0)=0.44±0.01. Comparisons are made with data below 25 GeV/c, and with optical-model predictions. The latter work only if "αω(0)" is postulated to hold for the elementary amplitudes.
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Proton-proton elastic scattering at 400 GeV/c has been measured in the region 5.4<−t<14.4 GeV2 with no sign of a second dip or "break." If the data are fitted by exp(At), the slope A decreases from 1.5±0.1 to 0.7±0.2 GeV−2 over the range. At fixed t the 400-GeV/c cross sections are about 0.6 times those at 200 GeV/c in this t range. At fixed θc.m.=15°, dσdt∝s−n where n=9.7±0.3.
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