The production of thef0 in two photon collisions, with the subsequent decayf0→π+π− has been observed in the CELLO detector at PETRA. Thef0 peak was found to lie on a dipion continuum and to be shifted downwards in mass by ≃50 MeV/c2. The ππ mass spectrum from 0.8 to 1.5 GeV/c2 was well fitted by the model of Mennessier using only a unitarised Born amplitude and helicity 2f0 amplitude. The previously observed mass shift and distortion of thef0 peak are explained by strong interference between the Born andf0 amplitudes. The only free parameter in the fit of the data to the model is the radiative widthΓγγ(f0). It was found that:Γγγ(f0)=2.5±0.1±0.5 keV where the first (second) quoted errors are statistical (systematic).
Data read from graph.
Data read from graph.
We present new measurements of parity conservation in the 293-nm transition in atomic Tl81205. Linearly polarized 293-nm photons, polarization ε^, are absorbed by 6P122 atoms in crossed electric and magnetic fields. The transition probability for each Zeeman component contains a term proportional to ε^·B→ε^·E→×B→ arising from interference between the Stark E1 amplitude βE and the parity-nonconserving E1 amplitude Ep. Our result, [ImEpβ]expt=−1.73±0.33 mV/cm, is compared with estimates based on the standard electroweak model.
Spin of the Tl nucleus is 1/2.
The differential cross sections of the reaction p―p→n―n were measured at 390, 490, 590, 690, and 780 MeV/c. The existence of the theoretically predicted forward dip is confirmed. The results are compared with the predictions of various N―N potential models.
NUMERICAL VALUES SUPPLIED BY F. SAI.
NUMERICAL VALUES SUPPLIED BY F. SAI.
NUMERICAL VALUES SUPPLIED BY F. SAI.
The magnetic moment of the Ξ− hyperon has been measured to be μ(Ξ−)=−0.69±0.04±0.02 nuclear magnetons, where the uncertainties are statistical and systematic, respectively.
No description provided.
The search for parity nonconservation in heavy elements has been extended to the 1.28-μm P03→P13 magnetic dipole transition in atomic lead. The experimental result, R=Im(E1M1)=(−9.9±2.5)×10−8, agrees, within the present uncertainties in experiment and atomic theory, with the prediction, R=−13×10−8, derived from the Weinberg-Salam-Glashow theory of weak neutral-current interactions.
No description provided.
WE SUM BOTH STATISTICAL AND SYSTEMATIC ERRORS TO OBTAIN A WEIGHTED AVERAGE OF ALL DATA GROUPS. QUOTED ERROR INCLUDES STATISTICAL AND SYSTEMATIC CONTRIBUTIONS.
Reconstruction of charged D ∗ 's produced inclusively in e + e −. annihilation at CM energies near 34.4 GeV is accomplished in the decay modes D ∗ + → D 0 π + → K − gp + π 0 π + and D ∗ + → D 0 π + → K − gp + π − π + π + and their charge conjugates. Using these and previously reported D ∗ + → D 0 π + → K − gp + π + and D ∗ + → D 0 π + → K − gp + π + + missing π 0 channels we present evidence for hard gluon bremsstrahlung from charm quarks and show that the ratio of the quark-gluon coupling constant of charm quarks to the coupling constant obtained in the average hadronic event, α s c α rms = 100 ± 0.20 ± 1.20 . Our result provides evidence that the quark-gluon coupling constant is independent of flavor.
No description provided.
No description provided.
No description provided.
e + e − annihilation into hadrons was studied at CM energies between 39.8 and 45.2 GeV and a search was made for new heavy quarks. No evidence was found for the existence of a narrow state excluding the possible existence of the lowest vector toponium state in this mass range. A search for continuum production of heavy quarks led to lower mass limits for new quarks of 22.0 GeV ( e Q = 2 3 ) and 21.0 GeV ( e Q = 1 3 ). Quarks are found to be pointlike, the corresponding mass parameter being larger than 288 GeV. A fit of the QCD and the electroweak contributions to R = σ tot / σ μμ yielded sin 2 θ W = 0.30 −0.07 +0.23 .
STATISTICAL ERRORS ONLY. NUMERICAL VALUES OF DATA TAKEN FROM PREPRINT.
No description provided.
No description provided.
None
No description provided.
No description provided.
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.
Results are presented from a study of the annihilation interaction p―p→K+K−π+π− at 8.3 GeV/c based on data from an experiment performed with the large-aperture solenoid spectrometer (LASS) at the Stanford Linear Accelerator Center. A measurement of the reaction cross section is made, and contributions to the final state from the φ, f0A20, K*(890), K*(1430), and ρ0 resonances are studied.
No description provided.
No description provided.
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