The experimentally determined average charged-particle multiplicities, 〈nX〉, of the systems, X, produced in the following reactions for 147 GeV/c incident pion momentum are presented as functions of the square of the invariant mass of X, MX2, and of |t|:π−p→πfast−X, π−p→pX, π−p→Δ++X, π−p→(π−π+)ρ0X, and π−p→Λ0X. Details of the analysis are discussed. These data can be fit by the expression 〈nX〉=A+B ln MX2+C|t| and the coefficients obtained for B are equal within their uncertainties. C is significantly different from zero only for π−p→πfast−X. These results and 〈nX〉 data from other inclusive and total-inelastic-reaction studies are discussed in terms of a simple model which assumes contributions to 〈nX〉 from the target-fragmentation, the central, and the beam-fragmentation regions in the case of total-inelastic reactions. For inclusive reactions, either the beam or target fragmentation is replaced by an exchange-particle-fragmentation contribution. The s, t, and MX2 dependence of the parameters of the model are deduced from triple-Regge considerations. The data are found to be consistent with the model and values are presented for the parameters.
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We report on the measurement of the reaction e+e−→e+e− with a large—solid-angle electromagnetic shower detector at center-of-mass energies s=13 and 17 GeV. Comparison of our results with predictions of quantum electrodynamics shows excellent agreement in both the angular distribution and energy dependence. Values of cutoff parameters are also given.
No description provided.
We report the first measurement of the ratio R=(σe+e−→hadrons)(σe+e−→μ+μ−) (with negligible τ-lepton contribution) at a center-of-mass energy s=13 GeV and s=17 GeV, from the just finished electron-positron colliding-beam facility PETRA. The detector, MARK-J, has an approximately 4π solid angle and measures γ, e, μ, and charged and neutral hadrons simultaneously. Our results yield R(s=17 GeV)=4.9±0.6 (statistical) ±0.7 (systematic error), and R(s=13 GeV)=4.6±0.5 (statistical) ±0.7 (systematic error). The ratio R(s=17 GeV)R(s=13 GeV) is 1.08±0.18.
No description provided.
No description provided.
The production of KS, Λ, Λ¯, and γ in π−p collisions at 147 GeV/c is analyzed. Cross sections, rapidity, Feynman-x, and pT2 distributions are presented and compared to charged-particle production. The energy dependence of multiplicities in π−p and pp collisions is shown. A new scaling form for the correlation of neutral- and charged-particle multiplicities is presented for compilations of πp and pp data.
Axis error includes +- 0.0/0.0 contribution (?////ERRORS QUOTED ARE MAINLY STATISTICAL BUT INCLUDE CONTRIBUTIONS FROM ESTIMATES OF CONTAMINATION AND OF THE RELIABILITY OF WEIGHTING SCHEMES10 PCT OF ALAMBDA EVENTS COULD BE GAMMA CONTAMINATION, 0.5 PCT OF KS EVENTS COULD HAVE BEEN MISCLASSIFIED AS GAMMA'S).
Axis error includes +- 0.0/0.0 contribution (?////ERRORS QUOTED ARE MAINLY STATISTICAL BUT INCLUDE CONTRIBUTIONS FROM ESTIMATES OF CONTAMINATION AND OF THE RELIABILITY OF WEIGHTING SCHEMES10 PCT OF ALAMBDA EVENTS COULD BE GAMMA CONTAMINATION, 0.5 PCT OF KS EVENTS COULD HAVE BEEN MISCLASSIFIED AS GAMMA'S).
The cross section for the fully constrained reaction ep→eppp¯ has been determined as a function of the electroproduction variables Q2 and s, in the range 0.7<Q2<3 GeV2 and 8<s<16 GeV2. Evidence is presented and cross-section estimates are made for resonances in the final-state p¯p system.
The cross section for virtual photon are derived from E- P cross section bydividing on the virtual-photon flux factor.
The cross section for virtual photon are derived from E- P cross section bydividing on the virtual-photon flux factor.
We measured dσdt for p↑+p↑→p+p from P⊥2=4.50 to 5.09 (GeV/c)2 at 11.75 GeV/c. We used a 59%-polarized proton beam and a 71%-polarized proton target with both spins oriented perpendicular to the scattering plane. In these large-P⊥2 hard-scattering events, spin effects are very large and the ratio (dσdt)↑↑:(dσdt)↑↓ grows rapidly with increasing P⊥2, reaching a value of 4 at 90° (c.m.). Thus, hard elastic scattering, which is presumably due to the direct scattering of the protons' constituents, may only occur when the two incident protons' spins are parallel.
THE ERRORS INCLUDE STATISTICAL AND SYSTEMATIC ERRORS ADDED IN QUADRATURE. THE PARALLEL/ANTIPARALLEL SPIN CROSS SECTION RATIO IS (1+CNN)/(1-CNN).
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.
No description provided.
No description provided.
SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
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.
No description provided.
No description provided.
We present results on the inclusive distributions of final-state hadrons created in deep-inelastic electron scattering from protons and deuterons. Data were taken from all portions of the kinematic range simultaneously in an apparatus which had equal detection efficiency for both charge signs. A subset of the produced hadrons were identified with a threshold-type Čerenkov counter. We find that the charge ratio h+h− is a strong function of Q2, xF, and pT2, with little dependence on s. The ratio of production of h− from deuterium to that from hydrogen as a function of φ is flat. The invariant cross section for each charge sign and each target exhibits the seagull effect (a correlation in 〈pT〉 and 〈xF〉). The value of 〈pT〉 for data in the range 0.4<xF<0.85 increases slightly as Q2 increases. The exponential dropoff in pT for production of protons and kaons is similar to that for pions. The dropoff in xF for production of pions shows a definite dependence on Q2, but this effect is largely caused by the decay products of the exclusive ρ0 final state. Finally, f(xF) for π+, π−, K+, K−, p, and p¯ is presented for each target type.
No description provided.
No description provided.
No description provided.
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).
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