Baryon resonance production in quasi-two-body reactions has been studied for the channels K + p→K°p π + , K + n π + and K + p π ° at beam momenta of 2.53, 2.76 and 3.20 GeV/ c . The production cross sections, four-momentum transfer distributions and density matrix elements are given for the Δ(1236), N ∗ (1400), N ∗ (1500) and N ∗ (1680) states. The reaction K + p→K° Δ ++ (1236) is compared to the line reversed reaction K − n → K °Δ − and the charge-exchange SU(3) sum rule for pseudo-scalar meson plus Δ(1236) is tested.
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The exclusive reaction $\gamma p \to p \pi^+ \pi^-$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was about 20 pb$^{-1}$. The reaction was isolated by detecting the $\pi^+$ and proton in CLAS, and reconstructing the $\pi^-$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $S$, $P$, and $D$-waves in the $M_{\pi^+\pi^-}$ mass range $0.4-1.4$ GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the $\rho(770)$ meson in the $P$-wave, evidence for the $f_0(980)$ and the $f_2(1270)$ mesons was found in the $S$ and $D$-waves, respectively. The differential production cross sections $d\sigma/dt$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the $f_0(980)$ has been measured in a photoproduction experiment.
Moments YLM(LM=00) of the di-pion angular distribution for -T.
Moments YLM(LM=00) of the di-pion angular distribution for -T.
Moments YLM(LM=00) of the di-pion angular distribution for -T.
An analysis has been performed of neutrino and antineutrino interactions with protons and neutrons in a deuterium bubble chamber. The interactions under study are quasielastic neutrino-neutron scattering and one-, two- and three-pion production reactions. Results are presented on cross sections, effective mass distributions, resonance production, momentum transfer distributions and coefficients of the decay angular distributions. Where possible, comparisons are made with existing theoretical models and predictions.
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Numerical values supplied by A.Tenner.
Numerical values supplied by A.Tenner.
A non q q ,J PC = 1 −+ , I G =1 − meson has been observed in the study of the exclusive reaction π − p→π 0 ηn at 100 GeV. Its mass is (1406±20) MeV. Its width is (180±30) MeV.
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The K − η effective mass spectrum in the reaction K − p→K − π + π − π 0 p at 11 GeV/ c has a prominent peak at ≈1.75 GeV/ c 2 , which is shown to be due to the K 3 ∗ (1780) by a spherical harmonic moments analysis and amplitude decomposition; there is no significant signal for K 2 ∗ (1430). The measured branching fractions for the leading L =1 and L =2 K ∗, s, [BF(K 2 ∗ (1430)→Kη) <0.45% at the 95% CL and BF ( K 3 ∗ (1780)→ Kη )=9.4±3.4%] confirm the SU(3) prediction that the Kη channel couples preferentially to odd spin K *, s.
Numerical data of acceptance corrected spherical harmonic moments requested from authors.
Including systematic error.
High statistics data for the reaction K − p→K − π + n at 11 GeV / c have been obtained in the LASS spectrometer at SLAC. A spherical harmonic moments analysis provides clear evidence for the production of the complete leading orbitally excited K ∗ series up through J P = 5 − . New measurements are made of the masses and widths of the 1 − K ∗ (892), 2 + K ∗ (1430 ), 3 − K ∗ (1780), and 4 + K ∗ (2060), and evidence is presented for the production of a new K ∗ state at 2382 MeV / c 2 with spin-parity 5 − .
Unnormalised acceptance corrected spherical moments.
Correlation matrices.
Correlation matrices.
In diffractive photoproduction ofηπ+π−, the two-body substatesηρ0 andA2π are found to contribute significantly to the cross-section forηπ+π− masses below 2.4 GeV. From a spin-parity analysis the branching ratio, ρ′(1600)→ηρ/ρ′(1600)→, is determined to be <0.02 at the 68.3% confidence level. TheA2π component shows an enhancement around 1.7 GeV. The spin-parity analysis indicates a probable contribution to this signal from exclusive photoproduction of theg(1690).
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Not corrected for 35% background under the eta --> gamma gamma peak.
Not corrected for 35% background under the ETA --> GAMMA GAMMA peak.
We have studied the reactions π+n→K+K−p, π+p→K+K−Δ++, and π+p→(K+K−π+)p in 10-GeV/c π+d interactions using the large-aperture solenoid spectrometer at SLAC. We measure the cross sections times branching ratios for the production of the known meson resonances f(1270), g(1690), and h(2040). We also observe a new resonance with mass 2747±32 MeV, width 195±75 MeV, and production cross section times branching ratio into K+K−π+ of 0.84±0.08 μb. The data are consistent with the quantum numbers of this state being I=1, JP=7−.
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We present an analysis of theKs0Ks0 system produced in the reaction π−p→Ks0Ks0n at 63 GeV based on ∼700 events in the kinematical region of |t|<0.5 GeV2. We concentrate on masses between 1,200 and 1,600 MeV where a double maximum structure is observed. Performing an amplitude analysis in this mass interval we find thatS,D0 andD+ waves contribute to the mass spectrum at approximately equal strength. The peaks are attributed to spin 2 waves. However, we failed to explained them by interferingf(1270),A2(1310) andf′(1520) resonances alone. While the first peak can be associated withf(1270)−A2(1310) production, an additional tensor meson is needed with mass of ∼1410 MeV and a narrow width for a description of the second one. The analysis as well as the energy dependence deduced from some publishedKs0Ks0 mass spectra suggests this object to be dominantly produced by a natural parity exchange. Because the 2++\(q\bar q\) nonet is already complete the nature of the new tensor meson is an open question.
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