The reaction e + e − → ω o has been measured by detecting the charged pions of the π + π − π o decay mode of the ω o. A partial decay width of ω o in e + e − : Γ e + e − =0.94±0.18 keV is deduced from this result.
FITTED, BACKGROUND SUBTRACTED, PEAK OMEGA CROSS SECTION, CORRECTED FOR UNOBSERVED DECAYS, IS 1.82 +- 0.34 MUB. TABULATED ASSUMING CENTRAL ENERGY IS 782.6 MEV. VACUUM POLARIZATION AND RADIATIVE CORRECTIONS APPLIED.
The electromagnetic form factor of the pion has been determined in the ϱ o resonance region by measuring the absolute cross section of the reaction e + e − → π + π − with the Orsay storage ring. More than 800 pion pairs have been detected. The excitation curve has been fitted with a Breit-Wigner formula which leads to the following values: σ peak = (1.69 ± 0.21) 10 −30 cm 2 ; m ϱ = (770 ± 4) MeV ; Γ ϱ = (111 ± 6) MeV . The partial width of the ϱ o going into e + e − thus obtained is: Γ ϱ → e + e − =(7.36±0.7) keV .
No description provided.
About 10 000 two-prong events of 8.1 GeV/ c proton-proton interactions in the CERN 2 m. bubble chamber have been analyzed. We study elastic scattering and single-pion production reactions. We give cross sections for isobar production. We attempt to interpret the general features of the pp→pn π + reaction by the Deck mechanism. We compare the production and the decay of δ ++ (1236) with absorption or π Regge trajectory exchange models.
No description provided.
No description provided.
No description provided.
We have studied neutral final states produced in π−p collisions at momenta of 1.71, 1.89, 2.07, 2.27, and 2.46 GeVc, by observing the γ rays emitted. In particular, measurements are presented of (i) π−p→π0n, for which the Regge-pole fit at momenta ≥5.9 GeVc also agrees rather well here; (ii) π−p→η0n, for which the Regge model which fits at higher energies does not agree here; (iii) π−p→π0γn, in which there is some evidence for a diffraction dissociation process as well as ω0-meson production; (iv) π−p→π0π0n, which is dominated by production of N*0(1236)π0 and by peripheral production of pion pairs. In (iv), the former process is found to fit with the same Reggeized ρ-meson exchange model as charge-exchange scattering, while the latter gives indication of the s-wave ππ interaction. An account is given of new techniques, particularly in the data analysis, which were developed in the course of this work.
No description provided.
No description provided.
No description provided.
We have measured the e + e − → φ reaction by the K S 0 K L 0 and 3 π decay modes of the φ. We have deduced Γ ( φ → all), Γ ( φ →e + e − ), as well as B ( φ →K S 0 K L 0 ), B ( φ →K + K − ) and B ( φ → π + π − π 0 ).
No description provided.
RESONANCE FIT TO 12 DATA POINTS AROUND PHI FOR EACH CHANNEL GIVES PHI WIDTH OF 4.2 +- 0.9 MEV AND BR(PHI --> PI+ PI0 PI-/PHI --> KL KS) OF 0.667 +- 0.157 (RATHER HIGH).
No description provided.
Angular distributions are presented for p¯−p elastic scattering at 8 and 16 GeV/c for |t|<1.3 (GeV/c)2. At both energies there is structure in the differential cross sections in the region 0.5<~|t|<~1.0 (GeV/c)2, similar to that observed at lower energies. The diffraction peak continues to expand with increasing incident momentum.
No description provided.
No description provided.
No description provided.
A spark-chamber experiment on the peripheral production of 9245 pion pairs by 12- and 18-GeV/c incident pions is reported and analyzed in terms of a one-pion-exchange model in which the final state at the nucleon vertex contains generally one or more pions. The relevant dynamics and kinematics appropriate to this problem are reviewed, and the experimental and analysis techniques giving good resolution and detection-bias correction are discussed in some detail. From the results, fair agreement is found between the data and the one-pion-exchange calculation of the ρ0 production cross sections and of the associated missing-mass spectra. The ρ0 is found to be consistent with a single peak, and no evidence of peak splitting is observed. A search for a narrow s-wave dipion resonance is made with negative results. Normalizing to the ρ0 meson, the s-wave π+π− scattering cross section is computed from the abundant low-dipion-mass events, giving a cross section falling smoothly from 50 mb (300 MeV) to about 20 mb (600 MeV). No evidence of an s-wave resonance is found in this range of energies. Below 450 MeV, the pion-pion scattering asymmetry favors backward scattering (by 2½ standard deviations), which is consistent with a negative and falling J=T=0 phase shift. The extrapolated forward-backward asymmetry and the s-wave cross section are both consistent with a J=T=0 phase shift near|90°| at about 750 MeV.
Dipion production cross section under RHO resonance. Errors are statistical only.
Dipion production cross section under RHO resonance. Errors are statistical only.
RHO0 cross section. Errors are statistical only.
None
No description provided.
Differential cross sections for the reaction π−p→π0n were measured at nine incident-pion kinetic energies in the interval from 500 to 1300 MeV. The negative pion beam from the bevatron was focused on a liquidhydrogen target completely surrounded by a cubic array of six steel-plate spark chambers. The spark chambers were triggered on events with neutral final states. Charge-exchange events were identified from the one-shower and two-shower events in the spark-chamber pictures. By the Monte Carlo technique, the π0 distributions were calculated from the bisector distributions of the two-shower π0 events together with the observed γ-ray distributions of the one-shower π0 events. These π0 distributions were fitted with both Legendre-polynomial expansions and power-series expansions by the method of least squares. The extrapolated forward differential cross sections are in good agreement with the dispersion calculations. The Legendre coefficients for the differential cross sections in isospin state T=12 were obtained by combining our results with available data on π±p elastic scattering. In the light of existing phase-shift solutions, the behavior of these coefficients is discussed. The D5F5 interference term that peaks near 900 MeV is verified to be in isospin state T=12 only. We report here also the total neutral cross sections and the cross sections for the production of neutral multipion final states 2π0n and 3π0n. The 4π solid angle and the calibrated energy response of the spark chambers contribute to the accuracy of the results.
No description provided.
No description provided.
No description provided.
We have analyzed 2560 events in the final-state K O 1 K O 1 n produced in π − p interactions at 5, 7 and 12 GeV/ c . We observe the S ∗ (1070), f O and A 2 decaying into K O 1 K O 1 . Resonance parameters, cross sections, and branching ratios are given.
Cross section times branching ratio.
Forum