Proton-antiproton elastic scattering was measured at the CERN SPS Collider at the centr-of-mass energy s =546 GeV in the Coulomb interference region. The data provide information on the phase of the hadronic amplitude in the forward direction. The conventional analysis gives for the ratio ϱ of the real to the imaginary part of the hadronic amplitude the result ϱ =0.24±0.04.
Axis error includes +- 0.025/0.025 contribution (Normalisation was fixed using a previous UA4 measurement of the total cross section: sig(name=tot)*(1 + alpha**2)).
Best estimate of alpha(rho).
Proton-antiproton elastic scattering at a centre-of-mass energy of 540 GeV was measured in the four-momentum transfer range 0.05 < − t < s .19 GeV 2 . The t -distribution can be fitted by the exponential exp( b ) with b =17.2±1.0 GeV −2 . This result indicates a rapid decrease of the width of the diffraction peak between ISR and Collider energies.
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EXPONENTIAL SLOPE OF FIT TO DN/DT IN REGION 0.05 <-T <0.19 GEV**-2.
Proton-antiproton elastic scattering was measured at a centre of mass energy s = 540 GeV . In the four-momentum transfer range 0.21 < − t < 0.50 GeV 2 the t -distribution of about 7000 events is well represented by the exponential shape exp ( bt ) with slope parameter b = 13.7 ± 0.3 GeV −2 . A new measurement of the slope for − t < 0.19 GeV 2 confirms our earlier result, giving evidence for a change of slope of about 4 GeV −2 around − l ̷ ≈ 0.15 GeV 2 .
NUMERICAL VALUES OF LOW T DATA GIVEN IN BOZZO 84. STATISTICAL ERRORS ONLY.
NUMERICAL VALUES OF MEDIUM T DATA TAKEN FROM BOZZO 84. THESE ARE THE EARLIER (BATTISTON 83) VALUES RENORMALISED TO THE NEW LOW T DATA IN THE OVERLAP REGION. ERRORS ARE STATISTICAL ONLY.
SLOPE VALUES FROM BATTISTON 83.
Proton-antiproton elastic scattering was measured at the center-of-mass energy s =546 GeV in the four-momentum transfer range 0.45⩽−⩽1.55GeV 2 . The shape of the t -distribution is quite different from that observed in proton-proton scattering at the ISR. Rather than a dip-bump structure, a kink is present at − ≈0.9GeV 2 followed by a shoulder. The cross section at the second maximum is more than one order of magnitude higher than at the ISR.
No description provided.
Proton-antiproton elastic scattering was measured at the centre-of-mass energy s = 630 GeV in the four-momentum transfer range 0.7 ⩽ − t ⩽ 2.2 GeV 2 . The new data confirm our previous results at s = 546 GeV on the presence of a break in the t -distribution at − t ≃ 0.9 GeV 2 which is followed by a shoulder, and extend the momentum transfer range to larger values. The t -dependence of the differential cross section beyond the break is discussed.
Errors contain statistics and acceptance uncertainty.
The proton-antiproton total cross section was measured at the CM energy √s = 546 GeV . The result is σ tot = 61.9± 1.5 mb . The ratio of the elastic to the total cross section is σ e ℓ / σ tot = 0.215±0.005. A comparison to the lower energy data shows that the increase of the total cross section with energy is very close to a log 2 s behaviour.
CROSS SECTIONS ASSUMING RHO = 0.15.
RATIO OF ELASTIC TO TOTAL CROSS SECTION.
A precise measurement of p̄p elastic scattering in the Coulomb-strong interaction interference region was performed at the CERN Sp̄pS Collider at a centre-of-mass energy of 541 GeV. The ratio of the real to the imaginary part of the forward elastic scattering amplitude was found to be ρ = 0.135 ± 0.015. The slope of the exponential fall off of the strong interaction part was also measured to be b = 15.5 ± 0.1 GeV −2 .
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Real part of amplitude extracted using a more precise UA4 measurement. (1 +RE(AMP)/IM(AMP)**2)SIG(TOT) = 63.5 +- 1.5 MB (Bozzo et al. PL 147B(1984)392).
The proton-antiproton total cross section was measured at the center-of-mass energy of s = 541 GeV at the S p pS at CERN using a luminosity dependent method. The result σ tot =63.0±2.1 mb is in agreement with the luminosity independent measurement performed earlier by the UA4 Collaboration.
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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.
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