The inelastic scattering of muons has been measured using positive muons of momentum 10 GeV/c incident upon a liquid-hydrogen target. We present values of the differential cross section and of the virtual photon-photon absorption cross section for |q| in the range 0.05 to 1.2 (GeV/c)2 and for equivalent photon laboratory energies of 0.6 to 6.5 GeV.
No description provided.
No description provided.
No description provided.
The polarization parameter in proton-proton scattering has been measured at incident proton kinetic energies of 1.7, 2.85, 3.5, 4.0, 5.05, and 6.15 BeV and for four-momentum transfer squared between 0.1 and 1.0 (BeV/c)2. The experiment was done with an unpolarized proton beam from the Bevatron striking a polarized proton target. Both final-state protons were detected in coincidence and the asymmetry in counting rate for target protons polarized parallel and antiparallel to the scattering normal was measured. The maximum polarization was observed to decrease from 0.4 at 1.7 BeV to 0.2 at 6.1 BeV. The maximum of the polarization at all energies studied occurs at a four-momentum transfer squared of 0.3 to 0.4 (BeV/c)2.
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High-statistics measurements of the absolute differential cross section for n−p scattering have been made over neutron c.m.-system scattering angles 9.5°<θ*<64.5°. The statistical error is 1.7 to 3.3% for 2°-wide angular bins, and the systematic error is 2.7 to 3.3%. The cross section is fitted by dσdΩ*=A exp(bt), with A=10.27±0.36 mb/sr, b=5.00±0.05, and 0.01<−t<0.39 (GeV/c)2. For the ratio of the real to the imaginary part of the forward-scattering amplitude we obtained αn>~−0.43±0.04, consistent with other less precise determinations of αn.
EXPONENTIAL FIT TO D(SIG)/DOMEGA OVER -T = 0.01 TO 0.39 GEV**2 (THETA = 9.5 TO 64.5 DEG).
The differential cross section for n−p elastic scattering in the angular region 145°<θc.m.<180° has been measured with high statistical accuracy using the monoenergetic neutron beam at Clinton P. Anderson Meson Physics Facility. The results differ significantly from previous Dubna and Princeton-Pennsylvania Accelerator results but agree reasonably well with recent Saclay data except at extreme backward angles.
No description provided.
The quasifree $\overrightarrow{\gamma} d\to\pi^0n(p)$ photon beam asymmetry, $\Sigma$, has been measured at photon energies, $E_\gamma$, from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49 to 148$^\circ$. In this kinematic region, polarization observables are sensitive to contributions from the $\Delta (1232)$ and $N(1440)$ resonances. The extracted values of $\Sigma$ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID, and Bonn-Gatchina analyses; while a revised SAID fit, including the new $\Sigma$ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict $\pi^0n$ photoproduction observables, based on fits to published data in the channels $\pi^0p$, $\pi^+n$, and $\pi^-p$.
Photon beam asymmetry Sigma at W= 1.2711 GeV
Photon beam asymmetry Sigma at W= 1.2858 GeV
Photon beam asymmetry Sigma at W= 1.3003 GeV
We present results of a detailed analysis of inclusive direct photon production at the ψ(3095). The direct-photon momentum distribution for x>0.4 is presented and compared with the leading-order quantum-chromodynamic prediction. The total production rate is found to be consistent with theoretical expectations, but the observed momentum distribution is considerably softer. Results of an analysis of some inclusive properties of the hadronic system recoiling against the direct photon are presented. The mean charged-particle and Ks multiplicities are presented as functions of the invariant mass of the hadronic system. These data agree well with the corresponding mean multiplicities measured in e+e− annihilations at center-of-mass energies comparable to the invariant mass of the hadronic system.
TOTAL INCLUSIVE PHOTON MOMENTUM SPECTRUM. ERRORS ARE STATISTICAL ONLY.
PHOTON SPECTRUM PREDICTED FROM MEASUREMENT OF THE PI0 AND ETA DISTRIBUTIONS. ERRORS INCLUDE BOTH STATISTICAL AND RELATIVE SYSTEMATIC COMPONENTS.
INCLUSIVE PI0 MOMENTUM DISTRIBUTION. QUOTED ERRORS ARE STATISTICAL ONLY. OVERALL AND RELATIVE SYSTEMATIC ERRORS ARE LESS THAN 30 PCT AND MAY VARY SLOWLY WITH X.
We present a measurement of the cross section for hadron production by e+e− annihilation in the vicinity of the previously observed resonance near 3.77 GeV. The data are used to determine the parameters of the ψ(3770) resonance. The values found are: mass, 3764±5 MeV/c2, total width, 23.5±5 MeV, and partial width to electron pairs, 276±50 eV.
THESE RESULTS ARE ALSO IN THE THESIS OF R. H. SCHINDLER, SLAC-219 (1979), THE RECORD OF WHICH CONTAINS THE TABULATED CROSS SECTIONS.
BREIT-WIGNER RESONANCE PLUS BACKGROUND FIT TO RADIATIVELY CORRECTED DATA YIELDS RESONANCE MASS OF 3764 +- 5 MEV, TOTAL WIDTH OF 23.5 +- 5 MEV AND PARTIAL WIDTH TO ELECTRON PAIRS OF 276 +- 50 EV.
PEAK CROSS SECTION FOR D MESON PAIR PRODUCTION AT PSI(3770) RESONANCE. J/PSI, PSI(3684) AND CONTINUUM BACKGROUND (R=2.5) SUBTRACTED.
Two-photon interactions have been studied with the SLAC-LBL Mark II magnetic detector at SPEAR. The cross section for η′ production by the reaction e+e−→e+e−η′ has been measured at beam energies from 2.0 to 3.7 GeV. The radiative width Γγγ(η′) has been determined to be 5.8±1.1 keV (±20% systematic uncertainty). Upper limits on the radiative widths of the f(1270), A2(1310), and f′(1515) tensor mesons have been determined. A search has been made for production of the E(1420) by γγ collisions, but no signal is observed.
No description provided.
NO SIGNAL ABOVE BACKGROUND SEEN. UPPER LIMITS AT 95 PCT CL GIVEN.
The Mark II detector at SPEAR has been used to study D-meson production in e+e− annihilation at center-of-mass energies between 3.8 and 6.7 GeV. The neutral and charged D mesons are identified from their K∓π± and K∓π±π± decay modes. Measurements of RD and of the inclusive differential cross section s dσdz are presented. The quasi-two-body cross sections σDD¯, σD*D¯, and σD*D¯* are derived from an overall fit to the D recoil spectra. No evidence was found for the associated production of charmed mesons and charmed baryons.
No description provided.
No description provided.
THE DIFFERENTIAL SCALING CROSS SECTION FOR NEUTRAL AND CHARGED D'S. DEFINITION OF Z IS 2*E(P=3)/SQRT(S).
We present a study of the decay properties of charmed D mesons produced near the peak of the ψ′′(3770) resonance in e+e− annihilation. Branching fractions for nine Cabibbo-favored and three Cabibbo-suppressed decay modes are presented along with upper limits on one additional Cabibbo-favored and four additional Cabibbo-suppressed decay modes. A study of Kππ-decay-mode Dalitz plots reveals a large quasi-two-body pseudoscalar-vector component for the D0 decays and an apparent nonuniform population on the Dalitz plot for the D+ decay into K−π+π+. Using tagged events, we measure the charged-particle multiplicity and strange-particle content of D decays. A measurement of the D+ and D0 semileptonic decay fractions indicates that the D+ has a significantly longer lifetime than the D0.
INCLUSIVE CROSS SECTIONS UNCORRECTED FOR RADIATIVE EFFECTS.
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