Results on photoproduction of π + π − π 0 in the photon energy range 20–70 GeV are presented. For the ω meson, the production cross-section is found to be 1010±15 (statistical)±290 (systematic) nb and is constant over the incident photon energy range. Spin-density matrix elements are evaluated for ω meson production. The φ meson is observed with a total photoproduction cross section (corrected for branching ratio to π + π − π 0 ) of 610±35±170 nb. A third resonance, at 1.67 GeV, is seen in the mass spectrum and its interpretation is discussed. The production of a broad π + π − π 0 continuum, mainly via ϱπ, and peaking at 1.2 GeV, contributes with a cross section of about 2.5 ωb. The spin-parity content is analysed by the moments of the π + π − π 0 decay angular distribution in the helicity frame and by maximum likelihood fits to the π + π − π 0 Dalitz plot. It is found that production of J P = 1 − states accounts for less than half of the total mass spectrum above 900 MeV. There is a broad enhancement in the 1 + wave around 1.15 GeV indicating photoproduction of the H(1190) meson.
No description provided.
EXPONENTIAL FITS TO D(SIG)/DT IN OMEGA MASS REGION.
EXPONENTIAL FITS TO D(SIG)/DT OVER FULL ENERGY FOR THREE MASS REGIONS CORRESPONDING TO OMEGA, PHI AND OMEGA*.
The difference between total cross sections in pure transverse-initial-spin states for the p−p interaction has been measured at Tp=487, 639, and 791 MeV, using a frozen-spin target. A comparison with previous data and available phase-shift analyses is made.
No description provided.
We present results on photoproduction of ϱ 0 and ω in the reactions γ p→ π + π − p and γ p→ π + π − π 0 p by tagged photons in the energy ranges 20 to 70 GeV and 20 to 45 GeV, respectively. The production of the ϱ 0 shows dominantly the characteristics of a diffractive process with respect to the E γ and t dependence of the cross section and the spin density matrix. The ϱ 0 photoproduction yields on average over the photon energy range a total cross section of σ ( γ p→ ϱ 0 p) = 9.4±0.1 μ b with an additional systematic error of ±1 μ b, and average slope parameters of the t distribution d σ /d t ≈exp(− b | t | + ct 2 ), of b =9.1±0.1 GeV −2 and c = 3.1 ±±0.2 GeV −4 . The shape of the ϱ 0 peak in the π + π − invariant spectra shows a skewing similar to that observed at lower energies. The photoproduction of ω is also consistent with a diffractive process and has a cross section of σ ( γ p→ ω p) = 1.2± 0.1 μ b with an additional systematic error of ±0.2 μ b. The average slope parameters of the t distribution are b =8.3 ± 1.3 GeV −2 and c = 3.4±2.6 GeV −4 .
FITS USING THE SODING PARAMETERIZATION.
FITS USING THE ROSS-STODOLSKY PARAMETERIZATION.
No description provided.
The results of an experiment to study elasticK+K− photoproduction are presented. Differential cross sections and spin density matrix elements for ϕ(1.019) production are stddied as a function of incident photon energy and over a wide range of momentum transfer,t (tmin>t>−1.5(GeV/c)2). Helicity conserving amplitudes are observed to dominate ϕ production throughout this range and the differential cross sections exhibit a forward diffractive peak which cannot be understood in terms of a simple exponential dependence. A new value of the photon ϕ coupling constant is determined and shown to be consistent withe+e− annihilation measurements. A detailed study of the energy dependence of the differential cross sections is made, including other experimental data, and the extracted effective Regge trajectory compared with other diffractive processes. A study of the dependence of theK+K− decay angular distribution on invariant mass reveals evidence for ans wave contribution interfering with thep wave ϕ which may be attributable to theS* meson.
LOWER LIMIT OF ABS(T) IN TABLE IS TMIN.
No description provided.
LOW T VARIATION WITH ELAB. LOWER LIMIT OF ABS(T) IN TABLE IS TMIN.
We present differential cross sections andΔ++ spin density matrix elements for the photoproduction processγp→π−Δ++ and differential cross sections for the processγp→π+Δ0. The incident photon energy dependence is studied and a comparison is made with previous experiments and with the predictions of a theoretical model.
DIFFERENTIAL CROSS SECTION AVERAGED OVER WHOLE ENERGY RANGE.
DIFFERENTIAL CROSS SECTION AVERAGED OVER WHOLE ENERGY RANGE.
DIFFERENTIAL CROSS SECTION FOR DIFFERENT ENERGY RANGES.
A tagged photon beam (2.8
FITTED CROSS SECTION ENERGY DEPENDENCE IS SIG = (6.7 +- 0.7 MUB*GEV**2) * P**(-2.1 +- 0.2), INCLUDING HIGHER ENERGY DATA.
EXPONENTIAL SLOPE IS 6.1 +- 2.0 GEV**-2 FOR -T = 0.2 TO 0.7 GEV**2.
No description provided.
Virtual photoproduction of J/ ψ mesons has been measured for 280 GeV muon iron interactions in an iron/scintillator calorimeter target. The J/ψ's were identified by their decay into muon pairs. 315 events were observed, about half of which were elastic. The t , Q 2 and v distributions of these elastic events are presented. The v dependence is measured between 40 and 180 Mev and compared with lower energy photoproduction results. The Q 2 dependence is compared with the predictions of the vector dominance model.
TPRIME DISTRIBUTION OF ELASTIC J/PSI EVENTS FOR ALL Q2 AND NU WITH 280 GEV MUON BEAM.
NORMALIZED Q**2 DISTRIBUTION OF ELASTIC J/PSI EVENTS FOR ALL NU AND T WITH 280 GEV MUON BEAM.
EXTRAPOLATION OF Q**2 AND T DEPENDENCE TO CALCULATE D(SIG)/DT AT Q**2=0 AND T=0 FOR ELASTIC J/PSI PHOTOPRODUCTION PER NUCLEON.
Measurements of the photoproduction processes γρ→ρ+n and γρ→ρ-Δ++ (1236) are reported in the energy range 2.8 to 4.8 GeV. The data show shrinkage of the differential cross section in this energy region for the process γρ→ρ-Δ++ (1236); no shrinkage is observed for the ρ+n process. The energy dependences of the ρ+n and ρ-Δ++ (1236) total cross sections are much steeper than current model prediction. The ρ spin density matrices for each process are also presented.
No description provided.
SLOPE AND INTERCEPT OF D(SIG)/DT.
No description provided.
The s and t dependence of φ (1019) photoproduction has been investigated in the incident photon energy range 2.8 to to 4.8 GeV. Differential cross-sections and density matrix elements are presented for a t range extending from t min out to −1.3 (GeV/ c ) 2 . The results are discussed in terms discussed in terms of an effective Regge trajectory in the t -channel.
DIFFERENTIAL CROSS SECTIONS AVERAGED OVER TWO RANGES OF INCIDENT PHOTON ENERGY.
VARIATION OF SMALL -T DIFFERENTIAL CROSS SECTION WITH PHOTON ENERGY.
INTERCEPT AND SLOPE FROM FITS TO D(SIG)/DT AT SMALL -T.
The differential cross section of π+p elastic scattering has been measured in two high-statistics bubble-chamber exposures at laboratory beam momenta of 3.7 and 7.1 GeV/c. A new feature suggested by these data is a dip in dσdu at −u≃3 GeV2. This dip corresponds well to the third zero of J0(b−u′), where ℏcb=1 fm. The effective u-channel Regge trajectory computed for these two energies has a slope of 0.22 ± 0.26.
No description provided.
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