We have measured the total and subchannel cross sections for the reaction p¯p→p¯pπ+π− at 49 GeV/c. This reaction is dominated by two production mechanisms, diffraction and meson exchange. In addition, we have measured the total cross section for p¯p→p¯p2π+2π− and compared it to values at other momenta and with the corresponding pp interaction. Within the present statistics, no significant amount of exclusive annihilation is found into two, four, and six charged pions.
No description provided.
We report a measurement of the diffraction dissociation differential cross section d2σSD/dM2dt for p¯p→p¯X at √s =546 and 1800 GeV, M2/s<0.2 and 0≤-t≤0.4 GeV2. Our results are compared to theoretical predictions and to extrapolations from experimental results at lower energies.
Single diffraction dissociation cross section.
We present results from a measurement of double diffraction dissociation in $\bar pp$ collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width $\Delta\eta^0>3$ (overlapping $\eta=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.
Cross sections for double diffractive production.
We report the first observation of diffractively produced W bosons. In a sample of W -> e nu events produced in p-barp collisions at sqrt{s}=1.8 TeV, we find an excess of events with a forward rapidity gap, which is attributed to diffraction. The probability that this excess is consistent with non-diffractive production is 1.1 10^{-4} (3.8 sigma). The relatively low fraction of W+Jet events observed within this excess implies that mainly quarks from the pomeron, which mediates diffraction, participate in W production. The diffractive to non-diffractive W production ratio is found to be R_W=(1.15 +/- 0.55)%.
No description provided.
Antiproton-proton elastic scattering was measured at c.m.s. energies √s =546 and 1800 GeV in the range of four-momentum transfer squared 0.025<-t<0.29 GeV2. The data are well described by the exponential form ebt with a slope b=15.28±0.58 (16.98±0.25) GeV−2 at √s =546 (1800) GeV. The elastic scattering cross sections are, respectively, σel=12.87±0.30 and 19.70±0.85 mb.
Final results (systematic errors included).
Final results (systematic errors included).
Statistical errors only. Data supplied by S. Belforte.
We studied K+p interactions at 100 GeV with the Fermi National Accelerator Laboratory 30-in. hydrogen bubble chamber and associated spark-chamber system. We find σtot(K+p)=18.7±1.8 mb and σel(K+p)=2.0±0.4 mb. We present the charged-multiplicity distribution and its moments, and the charge-transfer distribution. The average inelastic charged multiplicity is 〈nc〉=6.65±0.31 and the two-charged-particle correlation functions are f2cc=4.52±1.32 and f2−−=0.47±0.35.
No description provided.
The elastic and topological p¯p cross sections have been measured at 48.9 GeV/c in the Fermilab proportional-wire-chamber-30-in.-bubble-chamber hybrid spectrometer. The elastic cross section is 7.81±0.24 mb and the slope of the elastic differential cross section at t=0 is 13.4±0.8 GeV−2. Further, the moments of the inelastic topological-cross-section distribution are 〈nc〉=5.69±0.03, 〈nc〉D=2.10±0.02, and f2cc=1.67±0.12.
Axis error includes +- 0.0/0.0 contribution (?////DALITZ PAIRS. VEES AND GAMMA CONVERSIONS NEAR THE VERTEX WERE DETERMINED TO BE NEGLIGIBLE. LOW -T ELASTIC EVENTS//ODD-PRONG EVENTS APPARANTLY NOT CAUSED BY SECONDARY INTERACTIONS WERE MOVED TO THE NEXT HIGHER MULTIPLICITY ON THE ASSUMPTION THAT A SHORT TRACK WAS NOTVISIBLETOTAL AP-P CROSS SECTION OF 43.86+-0.25 MB FROM A.S.CARROL ET AL.PRL 33, 928(1974) WAS USED FOR NORMALIZATION).
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The 2m hydrogen bubble chamber was exposed to a separated beam of α-particles from the ITEP synchrotron. The momentum of the 4 He-nuclei beam averaged over the bubble-chamber fiducial volume was equal to 2.7 GeV/ c (the kinetic energy of the initial protons in the nuclear rest frame was T p = 220 MeV). The total and topological cross sections were measured as well as the cross section of separate 4 He-p interaction channels and the differential cross sections d σ d t of the elastic 4 He-p scattering. The experimental results have been compared with the data of the previous experiments and with the theoretical predictions based on the Glauber-Sitenko multiple-scattering theory.
No description provided.
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