The differential cross section for K+p elastic scattering has been measured at several momenta in the interval 200-600 MeV/c within a hydrogen bubble chamber. The data have been fitted with a partial-wave analysis. We obtain solutions which are dominated over the entire momentum range by s-wave scattering, with constructive interference between the nuclear and Coulomb scattering. The effective-range approximation with only s waves yields a K+p scattering length a=−0.314±0.007 F and an effective range r0=0.36±0.007 F. The measured total inelastic cross section at 588 MeV/c is 11−5+9 μb.
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Results are given on the inclusive production of charged pions, kaons, and nucleons, in proton-proton collisions at c.m. energies from √ s = 23 to 63 GeV at large angles and for the transverse momentum range 0.1 < p T < 4.8 GeV/ c . The dependence of the production spectra on the collision energy √ s , the transverse momentum p T , and the longitudinal rapidity is discussed.
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Axis error includes +- 15.0/15.0 contribution (NORMALIZATION ERROR - THE LARGEST SYSTEMATICS).
Inelastic differential cross sections have been measured for π±p, K±p, and p±p at 140- and 175-GeV/c incident momentum over a |t| range from 0.05 to 0.6 GeV2 and covering a missing-mass region from 2.4 to 9 GeV2. For Mx2 greater than 4 GeV2, the invariant quantity Mx2d2σdtdMx2 was found to be independent of Mx2 at fixed t and could be adequately described by a simple triple-Pomeron form. The values obtained for the triple-Pomeron couplings are identical within statistics for all channels.
Data from 140 GeV and 175 GeV are combined. The distributions are fit to CONST*(SLOPE(C=1)*T+SLOPE(C=2)*T**2).
The differential cross sections for the elastic scattering of π+, π−, K+, K−, p, and p¯ on protons have been measured in the t interval -0.04 to -0.75 GeV2 at five momenta: 50, 70, 100, 140, and 175 GeV/c. The t distributions have been parametrized by the quadratic exponential form dσdt=Aexp(B|t|+C|t|2) and the energy dependence has been described in terms of a single-pole Regge model. The pp and K+p diffraction peaks are found to shrink with α′∼0.20 and ∼0.15 GeV−2, respectively. The p¯p diffraction peak is antishrinking while π±p and K−p are relatively energy-independent. Total elastic cross sections are calculated by integrating the differential cross sections. The rapid decline in σel observed at low energies has stopped and all six reactions approach relatively constant values of σel. The ratio of σelσtot approaches a constant value for all six reactions by 100 GeV, consistent with the predictions of the geometric-scaling hypothesis. This ratio is ∼0.18 for pp and p¯p, and ∼0.12-0.14 for π±p and K±p. A crossover is observed between K+p and K−p scattering at |t|∼0.19 GeV2, and between pp and p¯p at |t|∼0.11 GeV2. Inversion of the cross sections into impact-parameter space shows that protons are quite transparent to mesons even in head-on collisions. The probability for a meson to pass through a proton head-on without interaction inelastically is ∼20% while it is only ∼6% for an incident proton or antiproton. Finally, the results are compared with various quark-model predictions.
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We have measured the production cross section for K s 0 in e + e − annihilation from 3.6 to 5.0 GeV center of mass energy. A substantial increase of the K s 0 yield is observed around 4 GeV in qualitative agreement with the charm hypothesis.
THE DATA GIVEN HERE AT 9.3 GEV AND ABOVE ARE REPORTED IN C. BERGER ET AL., PL 104B, 79 (1981). THE 12.0 AND 30 GEV DATA WERE TAKEN AT PETRA.
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The Split Field Magnet facility at the CERN ISR has been used to measure inclusive resonance production in inelastic p-p collisions at a c.m. energy of 53 GeV. The mass spectrum of pairs of oppositely charged hadrons shows a strong correlation, which can be explained as a consequence of dominant vector meson production, accounting for more than 60% of all pions and kaons produced.
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At the CERN intersecting storage ring the inclusive differential cross section [dσdσ]y=1 has been measured for f0, g0, K*0(1420), and K¯*0(1420) production: We obtain 0.58±0.05 mb, 0.09±0.05 mb, 38±15 μb, and 26±13 μb, respectively. The corresponding total inclusive cross sections are estimated to be 2.62±0.26 mb, 0.40±0.22 mb, 154±60 μb, and 107±52 μb, respectively. The magnitude of the K* cross section implies a cross section of approximately 5 μb for production of a charmed DD¯ pair.
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Inclusive cross sections for the production of π ± and K ± mesons in proton-proton collisions have been measured at a c.m. energy √ s = 45 GeV, in the range 0.41 < x < 0.95 and 0.35 < p T < 1.45 GeV, where x = 2 p L/√ s and p L , p T are the longitudinal and transverse components of the momentum of the meson. Within the measured range the p T dependence of the invariant cross section is essentially independent of x and weakly dependent on the type of particle. For all particles the invariant cross sections at fixed p T fall by three orders of magnitude between x = 0.4 and 0.95. Except at the highest values of x and p T , the statistical accuracy is better than 10%. The data are compared with a triple-Regge model and with a simple quark-parton model.
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A charge hyperon beam has been brought into operation at the CERN SPS. Particles are identified by a DISC Čerenkov counter, and decay products are analysed by a magnetic spectrometer. Cross sections for the inclusive production of π + , K + , p , Σ + , Σ − , ζ − , d, and π − , K − , p , Σ + , Σ − , ζ − , ω − , d in the forward direction have been measured at laboratory momenta between 70 and 130 GeV/ c . This range of momenta corresponds to 0.35 ⩽ x ⩽ 0.66 for an incident proton momentum of 200 GeV/ c . Antihyperon ( Σ − , ζ − , Σ + ) and Σ + and ω − fluxes have been measured for the first time in a hyperon beam.
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