We have measured ρ, the ratio of the real to the imaginary part of the p¯p forward elastic-scattering amplitude, at √s =1.8 TeV. Our result, ρ=0.140±0.069, is compared with extrapolations from lower-energy data based on dispersion relations, and with the UA4 value at √s =546 GeV.
Results of least square's fit to the distribution.
The antiproton-proton small-angle elastic-scattering distribution was measured at\(\sqrt s \) GeV at the Fermilab Tevatron Collider. A fit to the nuclear-scattering distribution in the range 0.065≤|t|≤0.21 (GeV/c)2 givesb=(16.2±0.5±0.5) (GeV/c)−2 for the logarithmic slope parameter. Using the optical theorem and the luminosity from Collider parameters, we obtain σtoto(1+ρ2)1/2 =(61.7±3.7±4.4)mb.
Slope was derived in the t range -0.065 < t < -0.21 (GeV/c)**2.
The differential cross section in the very forward direction has been measured for K − and K + scattering (break-up and coherent) on a deuterium target at an incident momentum of 10 GeV/ c . From these measurements and using a model for the scattering and re-scattering effects in deuterium, we have exploited the Coulomb-nuclear interference to deduce the real part of the K ± n scattering amplitude at a momentum transfer t = 0. The measurements are the first ever obtained for the K + n reaction and the first at this energy for the K − n reaction. A comparison has been made between our results and those predicted from dispersion relations. A new dispersion-relation fit including all the existing K ± n values at different energies has been performed.
SUM OF COHERENT AND BREAK-UP SCATTERING ON DEUTERIUM.
FROM FIT TO D(SIG)/DT OVER -T=0.0018 TO 0.074 GEV**2 ALLOWING FOR COULOMB SCATTERING, DOUBLE SCATTERING, INTERFERENCES AND FERMI MOTION. CORRELATION BETWEEN SLOPE AND RE(AMP)/IM(AMP) IS REFLECTED IN THE GIVEN SYSTEMATIC E RRORS.
The small-angle elastic scattering for pp at s=23.5, 30.7, and 52.8 GeV and for p¯p at s=52.8 GeV are measured. The data are normalized on Coulomb scattering. Using the optical theorem and the best estimate of the real part of the forward scattering amplitude, ρ(pp¯)=0.1, we obtain σtot(p¯p)=44.1±2.9 mb for the total cross section and b(p¯p)=13.6±2.2 GeV−2 for the nuclear slope parameter. This supports the dispersion relation prediction that σtot(p¯p) will start to rise above Elab≈200 GeV.
No description provided.
No description provided.
We have measured the antiproton-proton total cross section at √s =1.8 TeV at the Fermilab Tevatron Collider; the value obtained is 78.3±5.9 mb. B, the nuclear slope parameter for elastic scattering, was measured to be 16.3±0.5 (GeV/c)−2. From these data, we derive a value for the total elastic cross section.
Nuclear Store Parameter.
Elastic Cross Section.
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.
Results on \jpsi\ production in $e p$ interactionsin the H1 experiment at HERA are presented. The \jpsi\ mesons are produced by almost real photons ($Q~2\approx 0$) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of $2.7\,\mbox{pb}~{-1}$. The $\gamma p$ cross section for elastic \jpsi\ production is observed to increase strongly with the \cm\ energy. The cross section for diffractive $J/\psi$ production with proton dissociation is found to be of similar magnitude as the elastic cross section. Distributions of transverse momentum and decay angle are studied and found to be in accord with a diffractive production mechanism. For inelastic \jpsi\ production the total $\gamma p$ cross section, the distribution of transverse momenta, and the elasticity of the \jpsi\ are compared to NLO QCD calculations in a colour singlet model and agreement is found. Diffractive \psiprime\ production has been observed and a first estimate of the ratio to \jpsi\ production in the HERA energy regime is given.
Combined cross section for ELASTIC J/PSI production with proton dissociation.
Slope for J/PSI production with proton dissociation.
Cross section for PSI(3685) production.
TheΞ-p differential elastic cross section has been measured in the SPS hyperon beam at 102 and 135 GeV/c. In the range 0.01<−<0.42(GeV/c)2, thet distributions are found to be compatible with the formA exp(Bt) whereB is 7.7±0.4(GeV/c)−2 at 102 GeV/c and 8.2 ±0.5(GeV/c)−2 at 135 GeV/c. The corresponding total elastic cross sections areσel=4.9±0.7 mb andσel=5.6±0.9 mb, respectively. These results are compared with the predictions of phenomenological models.
NUMERICAL VALUES OF DATA SUPPLIED BY P.ROSSELET.
No description provided.
The differential elastic scattering cross section for 2.24 GeV/ c K − p collisions has been measured in film from the Brookhaven 20″ bubble chamber. The total elastic cross section is found to be 6.2 ± 0.7 mb. The exponential dependence on square of the momentum t in (GeV/ c ) 2 is fitted by ( d σ d Ω elastic = (12.4 ± 1.0 mb/sr) exp (7.81 ± 0.25)t . A A fit to a black disc model requires a radius of 0.95 ± 0.05 fm.
D(SIG)/D(T) was fitted to CONST*EXP(-SLOPE*T).
We present measurements of the αα elastic scattering differential cross section at √ s = 126 GeV in the range 0.05 ⩽ ‖ t ‖
ERRORS ARE STATISTICAL ONLY.
EXPONENTIAL FIT TO CROSS SECTION BELOW T = 0.075 GEV**2.
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