None
OVERALL NORMALIZATION ERROR NOT INCLUDED. -TMIN IS 0.015 (0.023) GEV**2 FOR THE LAMBDA (SIGMA0) REACTION.
INCLUDING NORMALIZATION UNCERTAINTY IN ERRORS. USING EMPIRICAL FITS TO D(SIG)/DT FOR -T > 1.0 GEV**2.
In order to determine the ηNN coupling constant we have measured the two reactions K − p→ Λη and K − p→ Λπ 0 with a magnetic wire chamber spectrometer which contained a gamma counter for the γγ decays of π 0 and η. The Λ polarization and the differential cross sections are given. The latter have quite different u dependences. Their ratio is interpreted, in terms of a nucleon-Regge exchange model, as the effect of a small ηNN coupling constant for which we obtain G η NN 2 = G π NN 2 · (0.26 ± 0.10) as allowed by SU(3). The large value given by Heisenberg's non-linear field theory, G η NN 2 = G π NN 2 · 0.9, is excluded by this measurement if the characteristic u dependence of the Λπ 0 channel is attributed to N α Regge exchange.
Axis error includes +- 10/10 contribution.
No description provided.
Axis error includes +- 10/10 contribution.
We have studied photoproduction using a 1 m streamer chamber at DESY and a tagged photon beam with an energy range of 1.6 GeV < E γ < 6.3 GeV. We analysed approximately 30 000 events and report topological, channel and resonance production cross sections for a large number of reactions with three and five outgoing charged particles.
CHANNEL CROSS SECTIONS FOR 3, 5 AND 7 PRONG REACTIONS.
'PARAMETRIZATION'.
'INTERFERENCE'.
The reaction γp→; π + π − p in the energy range 4.1 to 6.2 GeV has been studied with a tagged photon beam incident on a liquid hydrogen target in the DESY one-meter streamer chamber. The reaction is analysed in terms of the longitudinal phase space (LPS) method. The one-pion-exchange model for Δ(1236) production and decay is examined. For the diffractive part of the LPS a dual model with pomeron exchange is investigated. In particular, the s -channel helicity conservation dual model of Dewey and Humpert describes the data well.
No description provided.
CORRECTED FOR LOSSES AT SMALL T (UNLIKE VALUES OF 'REF 1'). BACKGROUND SUBTRACTION ERROR HAS BEEN ADDED QUADRATICALLY TO THE STATISTICAL ERROR.
Total and differential cross sections for the reaction gamma p -> pi^o eta p have been measured with the Crystal Ball/TAPS detector using the tagged photon facility at the MAMI C accelerator in Mainz. In the energy range E_gamma=0.95-1.4 GeV the reaction is dominated by the excitation and sequential decay of the Delta(1700)D33 resonance. Angular distributions measured with high statistics allow us to determine the ratio of hadronic decay widths \Gamma_{\eta \Delta}/\Gamma_{\pi S11} and the ratio of the helicity amplitudes A_{3/2}/A_{1/2} for this resonance.
Total cross section for the GAMMA P --> PI0 ETA P reaction.. Statistical erros only.
The differential cross section as a function of cos(theta(pi0) in the canonical(K) reference frame.. Statistical erros only.
The differential cross section as a function of phi(pi0) in the canonical(K) reference frame.. Statistical erros only.
The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.
Double differential cross section for Q^2=725 GeV^2.
Double differential cross section for Q^2=875 GeV^2.
Double differential cross section for Q^2=1025 GeV^2.
The cross section for the reaction $ e p \to e^{\prime} p \pi^{+} \pi^{-}$ was measured in the resonance region for 1.4$<$W$<$2.1 GeV and 0.5$<Q^{2}<$1.5 GeV$^{2}$/c$^{2}$ using the CLAS detector at Jefferson Laboratory. The data shows resonant structures not visible in previous experiments. The comparison of our data to a phenomenological prediction using available information on $N^{*}$ and $\Delta$ states shows an evident discrepancy. A better description of the data is obtained either by a sizeable change of the properties of the $P_{13}$(1720) resonance or by introducing a new baryon state, not reported in published analyses.
Measured cross section DSIG/DM(PI+PI-) for the W range 1400 to 1425GeV.
Measured cross section DSIG/DM(PI+PI-) for the W range 1425 to 1450GeV.
Measured cross section DSIG/DM(PI+PI-) for the W range 1450 to 1475GeV.
We have measured the reaction γ p → p π + π − in the DESY 1 m Streamer Chamber. The dominant ϱ o production is analyzed in terms of various models.
No description provided.
FOR ALL EVENTS.
FOR ALL TWO PION EVENTS.
Results from the first PWA of the K + K − system produced by incident K − , are presented in the mass range from the threshold to 1.70 GeV. In the P and D waves only the φ and f′ mesons are observed and their production mechanism studied. A broad S wave peaking at 1.4 GeV is observed but the lack of information about its phase makes the search for new 0 ++ mesons inconclusive.
ASSUMING BRANCHING RATIO 0.486 FOR PHI --> K+ K-.
No description provided.
No description provided.
Inclusive production of $\mathrm{D^{*\pm}}$ mesons in two-photon collisions was measured by the L3 experiment at LEP. The data were collected at a centre-of-mass energy $\sqrt{s} = 189$ GeV with an integrated luminosity of $176.4 \mathrm{pb^{-1}}$. Differential cross sections of the process $\mathrm{e^+e^- \to D^{*\pm} X}$ are determined as functions of the transverse momentum and pseudorapidity of the $\mathrm{D^{*\pm}}$ mesons in the kinematic region 1 GeV $< p_{T}^{\mathrm{D^*}} < 5 $ GeV and $\mathrm{|\eta^{D^*}|} < 1.4$. The cross section integrated over this phase space domain is measured to be $132 \pm 22(stat.) \pm 26(syst.)$ pb. The differential cross sections are compared with next-to-leading order perturbative QCD calculations.
The measured cross sections, as a function of PT over the bin ranges and the differential cross sections after bin-centre corrections.
The measured cross sections, as a function of pseudorapidity over the bin ranges and the differential cross sections after bin-centre corrections.
Integrated cross section in the visible kinematic region.
Forum