Topological and channel cross sections are given for annihilation and inelastic final states produced in p p interactions at 9.1 GeV/c. Cross sections for prominent resonances in specific channels and charged pion, ϱ 0 and Δ ++ inclusive cross sections are also presented.
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FITTED FORWARD D(SIG)/DT = 153 +- 8 MB/GEV**2.
CHANNEL CROSS SECTIONS FOR 2, 4, 6, AND 8 PRONG REACTIONS.
We have measured $\rho$ , the ratio of the real to the imaginary part of the $p \bar{p}$ forward elastic scattering amplitude, at $\sqrt{s}$ = 1.8 TeV. Our result is $\rho$ = 0.132 $\pm$ 0.056; this can be combined with a previous measurement at the same energy to give $\rho$ = 0.135 $\pm$ 0.044.
Measured value of the total cross section.
The measured value of the ratio of real to imaginary part of the forward scattering amplitude.
We report a measurement of the p p ̄ total cross section at s =1.8 TeV at the Fermilab Tevatron Collider, using the luminosity independent method. Our result is σ T =71.71±2.02 mb. We also obtained values of the total elastic and total inelastic cross sections.
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The highest-energy measurement of ΔσL(pp) and the first ever measurement of ΔσL(p¯p), the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/c polarized beams incident on a polarized-proton target. The results are measured to be ΔσL(pp)=−42±48(stat)±53(syst) μb and ΔσL(p¯p)=−256±124(stat)±109(syst) μb. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at 200 GeV/c in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the 10−5 level.
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We report a measurement of the proton-antiproton total cross section σT at c.m.s. energies √s =546 and 1800 GeV. Using the luminosity-independent method, we find σT=61.26±0.93 mb at √s =546 GeV and 80.03±2.24 mb at √s =1800 GeV. In this energy range, the ratio σel/σT increases from 0.210±0.002 to 0.246±0.004.
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Assuming RHO = 0.15.
We have obtained the branching ratios for p p annihilation at rest into π + π − and K + K − in a pure p p initial angular momentum state L = 1. A gaseous hydrogen target at normal pressure and temperature was used and events associated with transitions of the antiprotonic atom to the 2p level were selected by detecting the Balmer X-ray series. The branching ratios for p p annihilation into π + π − and K + K − from the 2p state are (4.81 ± 0.49) × 10 −3 and (2.87 ± 0.51) × 10 −4 , respect The pion yield is slightly larger than in liquid hydrogen, where L = 0 annihilation dominates, while the kaon yield is suppressed by a factor of four. Using these and previous data, we derive the branching ratios for pp annihilation into all ππ and K K modes from S and P states. A measurement in gaseous hydrogen, without X-ray requirement, yields the branching ratios (4.30 ± 0.14) × 10 −3 and (6.92 ± 0.41) × 10 −4 . With the known branching ratios of (3.33 ± 0.17) × 10 −3 and (1.01 ± 0.05) × 10 −3 in liquid hydrogen, we find that (50.3 ± 6.4)% of all annihilations in gas at NTP occur in the initial angular momentum state L = 1.
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
This is the first full solid angle analysis of large transverse energy events in\(p\bar p\) collisions at the CERN collider. Events with transverse energies in excess of 200 GeV at\(\sqrt s= 630 GeV\) are studied for any non-standard physics and quantitatively compared with expectations from perturbative QCD Monte Carlo models. A corrected differential cross section is presented. A detailed examination is made of jet profiles, event jet multiplicities and the fraction of the transverse energy carried by the two jets with the highest transverse jet energies. There is good agreement with standard theory for events with transverse energies up to the largest observed values\(( \approx \sqrt {s/2} )\) and the analysis shows no evidence for any non-QCD mechanism to account for the event characteristics.
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Data on antiproton-proton cross sections at the c.m. energies 200 and 900 GeV are presented. The data were obtained at the CERN antiproton-proton Collider operated in a new pulsed mode in which the same beams were accelerated and decelerated between beam energies of 450 and 100 GeV. The properties of the machine determine the ratio of the luminosities at the two energies to about 1% and thus an accurate measurement of the ratioR of the inelastic cross sections could be made. We findR (=σ900/σ200)=1.20±0.01±0.02, where the first error is statistical and the second systematic. Interpolating existing data to estimateσine1(200 GeV) this measurement ofR leads toσine1(900 GeV)=50.3+0.4+1.0 mb. Using an extrapolated value ofσe1/σtot we estimate the total cross section at 900 GeV to be 65.3±0.7±1.5 mb. Both the inelastic and total cross sections are compatible with a ln2s dependence. Comparisons are made with different fits to the total cross section energy dependence.
Ratio of inelastic cross sections at 900 and 200 Gev.
Estimate of 900 Gev total cross section based on a) interpolation to obtain total cross section at sqrt(s)=200 Gev (51.6 +- 0.4mb.) b) interpolation and extrapolation to obtain the ratio of elastic to total cross sections at 200 & 900 Gev (0.19 +- 0.01 and 0.23 +- 0.01 respectively).
New data are presented on charged particle multiplicity distributions for non single-diffractive events produced at CM energies s = 200 and 900 GeV . The data were obtained at the CERN antiproton-proton collider operated in a new pulsed mode. The multiplicity distributions are very well described by a negative binomial distribution. The highest energy data show no sign of approaching scaling, confirming our earlier results on the breaking of KNO scaling. The energy variation of the average charged multiplicity can be fitted to a quadratic in ln s or a s 0.13 dependence.
Figure gives uncorrected multiplicity distributions. Here we give the corrected distributions. Data supplied by D. Ward.
Results for multiplicity moments based on negative binomial fit to corrected data. Errors reflect both statistical and systematic effects. Results from earlier data at 546 Gev cm energy are also given.
C moments for corrected data where CQ=<N**Q>/<N>**Q.
The real-to-imaginary ratio of the p p forward elastic scattering amplitude has been measured at the LEAR facility of CERN by the Coulomb-nuclear interference method at seven beam momenta between 181 and 590 MeV/ c . The ratio is positive at 590 MeV/ c , becomes negative below 500 MeV/ c , reaches a minimum at 260 MeV/ c and then crosses zero again at about 230 MeV/ c .
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Results on charged particle production in pp̄ collision at s 1 2 = 540 GeV are presented. The data were obtained at the CERN pp̄ collider using the UA1 detector, operated without magnetic field. The central particle density is 3.3 + - 0.2 per unit o pseudo-rapidity for non-diffractive events. KNO scaling of the multiplicity distributions withresults from ISR energies is observed.
Pseudorapidity density distribution for all charged multiplicities corrected for acceptance and backgrounds by excluding NSD events. Data have been read from the plot.
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We report the final results of a search for narrow structures in the p¯p total cross section between 395 and 740 MeV/c with a rms mass resolution of 1.5 MeV around the S-resonance region. A reanalysis of the data significantly improved the statistical accuracy. No evidence is found for narrow structures and a 90%-confidence-level upper limit of 24 mb MeV is set at around 500 MeV/c for the integrated cross section of a Breit-Wigner-type resonance of width ≲4 MeV.
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Reactions p p → p p and p p → n n were studied at the kinetic energy 230 MeV of incident p by using bubble chamber films. Total cross sections for both of the reactions were found to be 51.2 ± 1.6 mb and 9.1 ± 0.6 mb, respectively. Differential cross sections are well explained by the phenomenological theory given by Bryan and Phillips.
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The Σ − p and Σ − d total cross sections have been measured to a statistical accuracy of ±1% and ±0.5%, respectively, at five momenta from 74.5 to 136.9 GeV/ c , using the hyperon beam at the CERN SPS. The Ξ − p and Ξ − d total cross sections have also been measured to the same statistical accuracy at 101.5 and 133.8 GeV/ c . The systematic uncertainty at each momentum is estimated to be of the order of ±0.5%. The hyperon-nucleon cross sections are shown to be rising with energy, and the data are compared with various phenomenological models.
Axis error includes +- 0.10/0.10 contribution (FOR DEUT TARGET. ADDED TO STAT. ERROR IN QUADRATURESAME AS ABOVE). Axis error includes +- 0.15/0.15 contribution (FOR PROTON TARGET. ADDED TO STAT. ERROR IN QUADRATURE.UNCERTAINTY OF EXTRAPOLATION OVER T).
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Proton-antiproton elastic scattering at CM energy 540 GeV has been studied in the t -range 0.04 < − t < 0.45 GeV 2 . The data are well fitted by the form exp ( bt ) with b = 17.1 ± 1.0 GeV −2 for | t | = 0.04 − 0.18 GeV su 2 and b = 13.7 ± 0.2 ± 0.2 GeV −2 for | t | = 0.21−0.45 GeV 2 . A luminosity measurement combined with the optical theorem gives σ tot = 67.6 ± 5.9 ± 2.7 mb and σ e1 / σ tot = 0.209 ± 0.018 ± 0.008.
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ELASTIC RATIO ASSUMES RHO=0.
Absolute inclusive cross sections for\(\bar pp\) interactions at 7.3 GeV/c are given. The data cover prong cross sections,V0, γ production and inclusive charged particle (p/π) production. Separation has been made into annihilation and non-annihilation components. Inclusive π+, π− production in the processes of\(\bar pp\) annihilation and non-annihilation are compared with simple quark models.
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ANNIHILATION AND NON-ANNIHILATION TOPOLOGICAL CROSS SECTIONS.
Total cross sections of p¯p and p¯d have been measured between 360 and 1050 MeV/c, with high statistical precision. Structures are observed in both cross sections at about the same momenta. For p¯p, the central mass is 1932±2 MeV/c2, and a fit to the data with a simple Breit-Wigner resonance plus background gives Γ=9−3+4 MeV/c2. The data suggest that the structures are in the isospin-1 state.
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The total p¯p cross section has been measured in the S region by the transmission method with use of a beam-monitoring spectrometer. The result is inconsistent with the existence of the narrow resonance S(1936) with cross sections reported by previous experiments.
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Total and annihilation cross sections for p¯p and p¯d have been measured over the momentum range 355-1066 MeV/c at closely spaced momenta and with good energy resolution. No evidence is seen for the narrow structure reported by other experiments in the vicinity of 500 MeV/c. The present measurements indicate a broader enhancement in this region, which, if interpreted as a resonance, would have a height of ∼ 3 mb and a width of ∼ 20 MeV. This structure appears only in the p¯p data.
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The differential cross sections of p p elastic scattering at 0.7 GeV/ c were obtained in the range 0.0018<| t |⩽0.0320 GeV 2 . From the interference between the Coulomb and the nuclear amplitude, the ratio of real to imaginary part of the forward nuclear amplitude was found to be +0.33±0.04.
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FIT FOR FORWARD NUCLEAR AMPLITUDE IN COULOMB INTERFERENCE REGION.
The presence of a structure in the p̄p total cross section at 1930–1940 MeV, with a narrow width of 9 MeV is confirmed. The interpretation of the effect as a single, non interfering, resonance is made difficult by the comparison of the elastic scattering with the charge exchange cross sections.
'INELASTIC' IS 0+2+4+6 PRONGS MINUS ELASTIC.
Channel cross sections have been determined for p p annihilations into final states containing 3 to 9 pions at 4.6 GeV/ c . The moments of both the charged and neutral pion multiplicity distributions are presented and model predictions are critically examined.
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Proton and antiproton total cross sections on protons and deuterons have been measured at 50, 100, 150, and 200 GeV/c. The proton cross sections rise with increasing momentum. Antiproton cross sections fall with increasing momentum, but the rate of fall decreases between 50 and 150 GeV/c, and from 150 to 200 GeV/c there is little change in cross section.
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ANTIPARTICLE-PARTICLE CROSS SECTION DIFFERENCES.
New measurements are reported of total cross sections for π ± , K ± , p and p on protons and deuterons at 11 momenta between 23 and 280 GeV/ c .
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The inclusive spectra for p p collisions at 22.4 GeV/ c are investigated. We show that the transverse momentum distributions resemble those in high-energy pp interactions and discuss the influence of annihilation processes on the p T 2 distributions. The invariant inclusive cross section for pions in the central region is found to be 28 ± 1 mb. A charge asymmetry is indicated by the y ∗ spectrum in the central region, the asymmetry parameter having the value 0.15 ± 0.01. Finally, we estimate the upper limit of the diffraction dissociation of the beam particle to be 3.68 −0.15 +0.45 mb.
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Total p−p cross-section measurements have been made at 28 momenta, in the range (0.575÷5.35) GeV/c. The cross-section decreases monotonically with increasing momentum. No important irregularity has been found.
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