A dipion enhancement of mass 1.59 GeV and width 0.23 GeV is observed in the channel γp→π + π − p. The spin-parity of the enhancement is consistent with being 1 − .
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.
Evidence is presented for inclusive photoproduction of F ± mesons in three decay modes, ηπ ± , ηπ ± π + π − and ηπ ± π + π + π − π − . The average mass of the F ± is found to be 2.020±0.010 GeV.
No description provided.
The reaction γ p → K + K − p has been investigated with tagged photons in the energy range of 20 < E γ < 70 GeV. A structure in the 1.7 GeV mass region is observed and interpreted in terms of a recurrence of the ø.
No description provided.
Measurements of the reaction γ p → p π + π − π + π − are presented, in which π + π − π + π − systems with masses up to 3 GeV are produced from fragmentation of the incident photon. The reaction is dominated by production of the large peak of the ϱ′(1600) meson and, at higher masses ≳2 GeV, y production of jet-like 4 π systems. The ϱ′(1600) meson is produced by a predominantly s -channel helicity conserving mechanism. At higher masses there are also indications of ϱπ peaks, of masses 1.3 GeV (the A 2 meson) and 1.75 GeV, produced with a recoiling π meson by a mechanism consistent with the Deck effect.
CORRECTED FOR TAILS OF BREIT-WIGNER RESONANCE USED IN FIT AND ALLOWING FOR 10 PCT BACKGROUND.
The reaction γ p→K + K − p has been investigated with photons in the energy range of 20< E γ <36 GeV and with K + K − pairs in the mass range of M K + K − <2.0 GeV. The production of the φ(1019) contributes with a cross section σ ( γ p → φ p) × BR( φ →K + K − ) = 240±6 nb with an additional systematic error of ±20 nb. In the higher mass range of 1.05< M K + K − <2.0 GeV the production of K + K − pairs yields a cross section σ ( γ p→K + K − p) = 160±8 nb with an additional systematic error of +40 −30 nb.
No description provided.
K+ K- PRODUCTION ABOVE PHI MASS.
No description provided.
Inclusive momentum and energy spectra of neutral and charged D-mesons produced in e + e − annihilation at energies near 7 GeV are presented. The slope of the energy spectrum is similar to the charged pion spectrum at the same energy. The inclusive cross section σ(e + e − → D or D + anything) at 7 GeV is 4.8±1.3 nb.
No description provided.
No description provided.
SCALING VARIABLE IS X(P=3,DEF=2*E(P=3)/SQRT(S)) > 0.54.
We present measurements of the cross section for inclusive D and K meson production in e + e − annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e + e − annihilation at energies above 4 GeV.
No description provided.
No description provided.
No description provided.
The inclusive production of antiprotons and Λ's in e+e− annihilation has been measured as a function of the c.m. energy in the range 3.7-7.6 GeV. We find that the baryon cross section has a behavior different from the total hadronic production. Our results show a rapid rise in the ratio σp¯σμμ between 4.4 and 5 GeV, consistent with what would be expected from charmed baryon production. Λ¯ production is 10-15% of p¯ production at all energies.
NOT INCLUDING SYSTEMATIC ERRORS.
We observe a resonance in the total cross section for hadron production in e+e− annihilation at a mass of 3772±6 MeV/c2 having a total width of 28±5 MeV/c2 and a partial width to electron pairs of 370±90 eV/c2.
BEFORE ANY RADIATIVE CORRECTIONS.
AFTER APPLYING ALL RADIATIVE CORRECTIONS.
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