An experiment using the Fermilab Single Arm Spectrometer (SAS) facility and an associated nonmagnetic vertex detector studied the reactions a+p→c+X, where a and c were π±, K±, p, or p¯. Extensive measurements were made at 100 and 175 GeV/c beam momenta with the outgoing hadrons detected in the SAS covering a kinematic range 0.12<x<1.0 and pT<1.25 GeV/c. Additional data covering a more restricted range in x were also gathered at 70 GeV/c incident momentum. In this high-statistics experiment, the identification of both the incoming and outgoing charged hadrons were made with a total of eight Čerenkov counters. New and extensive single-particle inclusive data for charged-particle production in low-pT hadronic fragmentation are presented. The average associated charged-particle multiplicity and pseudorapidity distributions are also given.
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Data are presented on the inclusive production of π±, K±, p, and p¯ for π+, K+, and protons incident on nuclear targets at 100 GeV. The results cover the kinematic range 30≤P≤88 GeV/c for Pt=0.3 and 0.5 GeV/c. The observed A dependence of the invariant cross sections exhibits remarkable simplicity, which does not naturally follow from current models of particle production. The results show that the hypothesis of limiting fragmentation can be extended to include collisions with nuclei.
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The analyzing power A y 0 in the reaction p↑p→dπ + has been measured using the polarized proton beam at Argonne National Laboratory's zero gradient synchrotron. Data were taken at beam momenta of 1.17, 1.47, 1.70, and 1.96 GeV/ c and for pion center of mass angles from 8° to 163°.
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Inclusive production of (D0, D¯0) and D± mesons have been observed in e+e− annihilation at 29 GeV. The signals correspond to R values of R(D0+D¯0)=3.25±1.2 and R(D++D−)=1.35±0.6. D*± production is also observed via the process D*+→D0π+ and its charge conjugate. The D and D* production rates are compared.
EXTRAPOLATION TO ALL Z.
EXTRAPOLATION TO ALL Z.
EXTRAPOLATION TO ALL Z.
We have obtained 1400 events of the baryon-exchange reaction pp→ΛpK+ using the ANL Zero Gradient Synchrotron 11.75-GeV/c polarized proton beam and the effective-mass spectrometer. A search for enhancements in the Λp mass spectrum has been made. No enhancements are observed; in particular, the narrow Λp enhancement at 2.13 GeV seen in K−d→Λpπ− is not observed. We establish limits on the production of narrow states of ∼ 10 nb. Also, 100000 events of the forward reaction pp→ΛK+p were examined and no narrow Λp enhancements are seen.
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D* FRAGMENTATION FUNCTION.
R VALUE IS RADIATIVELY CORRECTED (BUT NOT CROSS SECTION).
We present data on the multiplicity structure of inclusive charged hadron production in charged current neutrino and antineutrino freon interactions in the energy range 3–30 GeV resulting from an experiment with the bubble chamber SKAT. Average multiplicities, dispersions and correlation coefficients are investigated. Furthermore, KNO-scaling is studied and average net charges are calculated in different kinematical regions. Our data are compared with results from\(\begin{array}{*{20}c}{( - )}\\v\\ \end{array} \)-interactions on an isoscalar target of “free” nucleons to study the influence of nuclear effects.
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THE DATA ARE SATISFACTORILY DESCRIBED BY A LINEAR FUNCTION IN LN(W**2): <N> = A + B * LN(W**2) A=0.15+-0.09, B=0.84+-0.05 FOR CHARGED+ AND A=-0.49+-0.06, B=0.63+-0.04 FOR CHARGED-.
We present inclusive spectra of charged hadrons produced in\(\begin{array}{*{20}c}{( - )}\\v\\ \end{array}\)-Freon interactions at average beam energies of about 6 GeV. The experiment was done using the bubble chamber SKAT at the 70 GeV Serpukhov accelerator. In the hadronic energy range,W<5 GeV, dominantly isotropic events are found. The transverse momentum of the produced particles shows no strongW2-dependence. Feynman-scaling may be reached forW2≳10 GeV2, where also theż-spectra are described by the predictions of the parton model. All experimental data are reproduced rather well also by a Monte Carlo model based on ordinary phase space.
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During the initial data run with the High Resolution Spectrometer (HRS) at SLAC PEP, an integrated luminosity of 19.6 pb−1 at a center-of-mass energy of 29 GeV was accumulated. The data on Bhabha scattering and muon pair production are compared with the predictions of QED and the standard model of electroweak interactions. The measured forward-backward charge asymmetry in the angular distribution of muon pairs is -8.4%±4.3%. A comparison between the data and theoretical predictions places limits on alternative descriptions of leptons and their interactions. The existence of heavy electronlike or photonlike objects that alter the structure of the QED vertices or modify the propagator are studied in terms of the QED cutoff parameters. The Bhabha-scattering results give a lower limit on a massive photon and upper limits on the effective size of the electron of Λ+>121 GeV and Λ−>118 GeV at the 95% confidence level. Muon pair production yields Λ+>172 GeV and Λ−>172 GeV. If electrons have substructure, the magnitude and character of the couplings of the leptonic constituents affects the Bhabha-scattering angular distributions to such an extent that limits on the order of a TeV can be extracted on the effective interaction length of the components. For models in which the constituents interact with vector couplings of strength g24π∼1, the energy scale ΛVV for the contact interaction is measured to be greater than 1419.0 GeV at the 95% confidence level. We set limits on the production of supersymmetric scalar electrons through s-channel single-photon annihilation and t-channel inelastic scattering. Using events with two noncollinear electrons and no other charged or observed neutral particles in the final state, we see one event which is consistent with a simple supersymmetric model but which is also consistent with QED. This allows us to exclude the scalar electron to 95% confidence level in the mass range 1.8 to 14.2 GeV/c2.
Comparison of Bhabhas with QED.
Muon angular distributions.
Forward-backward asymmetry from full angular range.
The electroweak production asymmetry and the decay fragmentation function for e + e − → c c have been measured at s = 29 GeV using charged D ∗ production over the full kinematic range. The data were taken at PEP using the High Resolution Spectrometer. The measured asymmetry is −0.12 ± 0.08. The total production cross section in units of the point cross section corrected for initial state radiation is R D ∗ = 2.7 ± 0.9 .
ASSUMES SIG(D*+) = SIG(D*0). (EXPT. MEASURES D*+ PRODUCTION ONLY). R VALUE CORRECTED FOR INITIAL STATE RADIATION.
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