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No description provided.
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CROSS SECTION ON NEUTRON CALCULATED FROM DEUTERIUM MEASUREMENTS USING THE NUCLEON SPECTATOR MODEL.
Results are reported on the reaction p p → π + π + π − π − π 0 at six lab momenta spanning the region from 0.686 to 1.098 GeV/ c . The cross section for this process drops from 20.3 ± 1.2 mb at 0.686 GeV/ c to 13 1.0 mb at 1.098 GeV/ c . Resonance production is determined by means of a model which includes Bose symmetrization, Breit-Wigner amplitudes and Bose-Einstein correlations for the like-charged pion pairs in the nonresonant part of the amplitude. The likelihood fit to the resonance channels yields about 0.8% ηππ , 12% ϱ ± πππ , 2% f πππ , 8% ω ππ , 22% ϱ ± ϱ 0 π , 13% ωϱ 0 and 9% ω f with errors on the order of a few percent. Several percent A 1 ± ππ and X(1440) π were also needed to obtain good fits. The ϱ 0 πππ and ϱ 0 ϱ 0 π channels as well as A 2 ππ and A 1 0 ππ are consistent with zero. Reasonable fits to the mass distributions are obtained. Production angular distributions are found to be essentially uniform. The angular correlations between pion pairs are approximately fit by the simple model of resonance production with Bose symmetrization.
Axis error includes +- 0.0/0.0 contribution.
Axis error includes +- 0.0/0.0 contribution.
Approximately 100 000 four-prong antiproton annihilations in hydrogen were measured. A clean, unbiased sample of 842 K + K − π + π − events was obtained. This reaction is dominated by K ∗ (∼45%) and ϱ 0 (∼20%) production, with smaller amounts of A 2 0 (∼15%) and ϕ (∼5%) production. 25% of the reactions involved double resonance production. No significant three-body resonance production is observed.
ERRORS INCLUDE SYSTEMATICS.
A phase shift analysis of the K<sup loc="post">+</sup>p elastic scattering at 780 MeV/c has been performed. The experimental differential cross section is best explained by a solution with dominant s wave, negative s wave phase shift (−42.7 ± 1 deg.) and small contributions of p and d waves.
Corrected for PI+ P events and scanning efficiency.
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No description provided.
We present the final results of a measurement of the polarization parameter P 0 in high-energy n~-p and p-p elastic scattering, performed using a target which contained polarized protons. Data were taken at beam momenta of 6.0, 8.0, 10.0 and 12.0 GeV/c for n-, and of 6.0, 10.0 and 12.0 GeV/c for n+ and p, in the interval of invariant four-momentum transfer squared-t from 0.1 to 0.75 (GeV/c)2.
No description provided.
No description provided.
No description provided.
We study the processes $e^+ e^-\to K_S^0 K_L^0 \gamma$, $K_S^0 K_L^0 \pi^+\pi^-\gamma$, $K_S^0 K_S^0 \pi^+\pi^-\gamma$, and $K_S^0 K_S^0 K^+K^-\gamma$, where the photon is radiated from the initial state, providing cross section measurements for the hadronic states over a continuum of center-of-mass energies. The results are based on 469 fb$^{-1}$ of data collected with the BaBar detector at SLAC. We observe the $\phi(1020)$ resonance in the $K_S^0 K_L^0$ final state and measure the product of its electronic width and branching fraction with about 3% uncertainty. We present a measurement of the $e^+ e^-\to K_S^0 K_L^0 $ cross section in the energy range from 1.06 to 2.2 GeV and observe the production of a resonance at 1.67 GeV. We present the first measurements of the $e^+ e^-\to K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ cross sections, and study the intermediate resonance structures. We obtain the first observations of \jpsi decay to the $K_S^0 K_L^0 \pi^+\pi^-$, $K_S^0 K_S^0 \pi^+\pi^-$, and $K_S^0 K_S^0 K^+K^-$ final states.
Cross section measurement for PHI(1020).
Mass measurement for PHI(1020).
Measurement of the PHI(1020) width.
The process e+e- --> p anti-p gamma is studied using 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider, at an e+e- center-of-mass energy of 10.6 GeV. From the analysis of the p anti-p invariant mass spectrum, the energy dependence of the cross section for e+e- --> p anti-p is measured from threshold to 4.5 GeV. The energy dependence of the ratio of electric and magnetic form factors, |G_E/G_M|, and the asymmetry in the proton angular distribution are measured for p anti-p masses below 3 GeV. We also measure the branching fractions for the decays J/psi --> p anti-p and psi(2S) --> p anti p.
Measurement of the cross section as a function of the invariant mass of the PBAR-P system and the effective form factor for the reaction E+ E- --> PBAR P. The contributions from J/PSI and PSI(25) decaying to PBAR-P have been subtracted. The form factor error is the combined statistical and systematic.
The polarization of the recoil proton in γ + p → p + π0 has been measured at photon energies of 725 MeV and 900 MeV for centerof-mass angles near 90° using a small propane-ethane gas bubble chamber. Protons emerging from a liquid hydrogen target are momentum-analysed with a magnet, and the scattering from carbon observed in the bubble chamber. A counter telescope rejects pions and electrons, and protons from multiple pion processes are discriminated against by keeping the peak bremsstrahlung energy just above the mean photon energy. The visual method of observing scattering asymmetries has the advantage of being insensitive to systematic asymmetries in the incoming proton flux. It also quickly eliminates strongly inelastic scatters (stars), and provides a complete angular distribution from which the fraction of scatters which are inelastic can be deduced. The effect of inelastic scatters upon the scattering asymmetry is large when the energy-loss resolution is poor, an inherent problem with bremsstrahlung beams. The counting rate for this small chamber (3.4g/cm2 carbon scatterer) was 11 scatters/hour using every 5th synchrotron pulse; larger chambers with more dense scatterers (such as Freon) could give higher counting rates. Results are fork = 725MeV and ϑ (pion) = 87° (cm.), P=0.74±0.20, and for k=900MeV and ϑ (pion) = 70°, P=.51±.7. P is taken to be positive along the directionK xp, wherep is the momentum of the outgoing proton.
No description provided.
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