K − p elastic scattering at 10 GeV/ c is studied on ∼3600 bubble chamber events. The elastic cross section is found to be σ el = (3.20 ± 0.14)mb and the ratio σ el σ tot = (0.142 ± 0.006) , that is below the upper limit of 0.185 suggested in a model by Van Hove. The value of the forward differential cross section is consistent with zero real part to the scattering amplitude. The slope of d σ d t is similar to that for π ± and greater than that of K + , with no evidence for shrinkage of the diffraction peak. No events of backward scattering were observed. The Regge-pole model of Phillips and Rarita gives a good fit to the data.
No description provided.
The production of $\phi$ mesons in the reaction $e~{+}p \rightarrow e~{+} \phi p$ ($\phi \rightarrow K~{+}K~{-}$) at a median $Q~{2}$ of $10~{-4} \ \rm{GeV~2}$ has been studied with the ZEUS detector at HERA. The differential $\phi$ photoproduction cross section $d\sigma/dt$ has an exponential shape and has been determined in the kinematic range $0.1<|t|<0.5 \ \rm{GeV~2}$ and $60 < W < 80 \ \rm{GeV}$. An integrated cross section of $\sigma_{\gamma p \rightarrow \phi p} = 0.96 \pm 0.19~{+0.21}_{-0.18}$ $\rm{\mu b}$ has been obtained by extrapolating to {\it t} = 0. When compared to lower energy data, the results show a weak energy dependence of both $\sigma_{\gamma p \rightarrow \phi p}$ and the slope of the $t$ distribution. The $\phi$ decay angular distributions are consistent with $s$-channel helicity conservation. From lower energies to HERA energies, the features of $\phi$ photoproduction are compatible with those of a soft diffractive process.
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Numerical values of dsig/dt distribution requested from authors.
Numerical values of dsig/dt distribution read from plot.
We report a study of 20 exclusive reactions measured at the AGS at 5.9 GeV/c incident momentum, 90° center of mass. This experiment confirms the strong quark flow dependence of two-body hadron-hadron scattering at large angle. At 9.9 GeV/c an upper limit had been set for the ratio of cross sections for (p¯p→p¯p)(pp→pp) at 90° c.m., with the ratio less than 4%. The present experiment was performed at lower energy to gain sensitivity, but was still within the fixed angle scaling region. A ratio R(p¯ppp)≈140 was measured at 5.9 GeV/c, 90° c.m. in comparison to a ratio near 1.7 for small angle scattering. In addition, many other reactions were measured, often for the first time at 90° c.m. in the scaling region, using beams of π±, K±, p, and p¯ on a hydrogen target. There are similar large differences in cross sections for other reactions: R(K−p→π+Σ−K−p→π−Σ+)≈112, for example. The relative magnitudes of the different cross sections are consistent with the dominance of quark interchange in these 90° reactions, and indicate that pure gluon exchange and quark-antiquark annihilation diagrams are much less important. The angular dependence of several elastic cross sections and the energy dependence at a fixed angle of many of the reactions are also presented.
Cross sections at 90 degrees in the centre-of-mass.
No description provided.
No description provided.
Quasi-elastic scattering with central dipion cluster production is studied in π+p andK+p interactions at 250 GeV/c. The cross section of double pomeron exchange is obtained as σDPE(π+p →π+(π+π−)p)=24 ±5 µb and σDPE(K+p→K+(π+π−)p)=19 ±5 µb. The low energy pomeron-pomeron cross section is estimated for the first time.
Numerical values supplied by W. Kittel.
Numerical values supplied by W. Kittel.
Numerical values supplied by W. Kittel.
Data on the reactions (K+/π+)p→(K+/π+)pπ+π- and (K+/π+)p→(K+/π+)p2π+2π-, obtained with the European Hybrid Spectrometer, are presented and compared with data at lower energies. The contribution of beam and target diffractive dissociation and double Pomeron exchange, and porperties of these reactions are discussed.
No description provided.
No description provided.
No description provided.
Results are presented on π + p and K + p elastic scattering at 250 GeV/ c , the highest momentum so far reached for positive meson beams. The experiment (NA22) was performed with the european hybrid spectrometer. The π + p elastic cross section stays constant with energy while the K + p cross section increases.
No description provided.
No description provided.
ERRORS IN ELASTIC CROSS SECTIONS INCLUDE SYSTEMATIC ERRORS.
Primakoff production of the K0*(896) by incident KL’s was observed in the energy range 100–200 GeV. Production from Cu and Pb targets was measured simultaneously leading to a new value for the K0*(896) radiative width Γ(K0*(896)→K0+γ) of 116.5±9.9 keV. The result agrees with a previous determination while being considerably more precise and allows for more stringent tests of quark-model relations among the radiative widths of the low-lying vector mesons.
Data requested from authors.
Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
No description provided.
No description provided.
No description provided.
We have measured the coherent nuclear production of low-mass K+ω systems in K+A collisions at 202.5 GeV. Results for carbon, copper, and lead targets are similar to those found for π+π+π− production in π+A reactions at the same energy.
M(K+ OMEGA) < 1.5 GEV.
A study of ϕ-meson photoproduction by partially polarized photons of energy 20–40 GeV is reported. The production mechanism is found to conserves-channel helicity and to proceed via natural-parity exchange in thet channel. In the photoproduction of high-massK+K− states with photons of energy 20–70 GeV, there is evidence for an enhancement at a mass of 1.76 GeV with width 0.08 GeV.
No description provided.
No description provided.
No description provided.
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