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ANTIPROTONS STOPPING IN THE PHOTOEMULSION.
The TPC/Two-Gamma Collaboration has measured the inclusive cross section for production of charmed D ∗± mesons in photon-photon collisions. The reaction utilized was e + e - →e + e - D ∗± X, with D ∗± →D O π +- , D O →K -+ π ± , and either zero or one outgoing e ± detected. The result, σ(e + e - → e + e - D ∗± X) = 74±26±19 pb , is in agreement with the quark parton mo del prediction for e + e - → e + e - c c , combined with a Lund model for the hadronization of the charmed quarks.
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We report measurements of b-quark and B-hadron production in pp̄ collisions at √ s =630 GeV. We use muon samples to extract beauty production cross-sections over a wide range of transverse momentum in the central rapidity range | y | < 1.5. We compare our results to an O(α s 3 ) QCD prediction and find good agreement over the measured b-quark transverse momentum range 6 GeV / c to 54 GeV / c . Using the shape of the p T and y distribution predicted by QCD to extrapolate our data, we infer a total cross-section for b-quark production at √s=630 GeV of σ( p p ̄ → b b ̄ + X )=19.3±7( exp. )±9( th. μ b .
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The cross section is multipled on the B(J/PSI --> MU+ MU-).
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The error includes the experimental uncertainties (±0.003), uncertainties of hadronisation corrections and of the degree of parton virtualities to which the data are corrected, as well as the uncertainty of choosing the renormalisation scale.
Jet production rates using the E0 recombination scheme.
Jet production rates using the E recombination scheme.
Jet production rates using the p0 recombination scheme.
The transverse energy distributions have been measured for interactions of 32 S nuclei with Al, Ag, W, Pt, Pb, and U targets, at an incident energy of 200 GeV per nucleon in the pseudorapidity region −0.1 < ν lab < 5.5. These distributions are compared with those for 16 OW interactions in the same pseudorapidity region and with earlier measurements performed with 16 O and 32 S projectiles in the region −0.1 < ν lab < 2.9. These comparisons provide both a better understanding of the dynamics involved and improved estimates of stopping power and energy density.
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The structure of the nucleon is studied by means of deep-inelastic neutrino-nucleon scattering at high energies through the weak neutral current. The neutrino-nucleon scattering events were observed in a 340-metric-ton fine-grained calorimeter exposed to a narrow-band (dichromatic) neutrino beam at Fermilab. The data sample after analysis cuts consists of 9200 charged-current and 3000 neutral-current neutrino and antineutrino events. The neutral-current valence and sea nucleon structure functions are extracted from the x distribution reconstructed from the measured angle and energy of the recoil-hadron shower and the incident narrow-band neutrino-beam energy. They are compared to those extracted from charged-current events analyzed as neutral-current events. It is shown that the nucleon structure is independent of the type of neutrino interaction, which confirms an important aspect of the standard model. The data are also used to determine the value of sin2θW=0.238±0.013±0.015±0.010 for a single-parameter fit, where the first error is from statistical sources, the second from experimental systematic errors, and the third from estimated theoretical errors.
Neutral-current valence-quark distribution referenced to Q**2 = 10 GeV**2. The first systematic error is for the hadronic shower angle resolution degraded (improved) by 10 pct and the second is the change if the data are analysed with X values reduced by 5 pct.
Neutral-current sea-quark distribution referenced to Q**2 = 10 GeV**2. The first systematic error is for the hadronic shower angle resolution degraded (improved) by 10 pct and the second is the change if the data are analysed with X values reduced by 5 pct.
Charged-current valence-quark distribution referenced to Q**2 = 10 GeV**2. The first systematic error is for the hadronic shower angle resolution degraded (improved) by 10 pct and the second is the change if the data are analysed with X values reduced by 5 pct.
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An analysis of W and Z boson production at UA1, using 4.66 pb −1 of data from the 1988 and 1989 CERN p p Collider runs at s =0.63 TeV , yields R ≡ σ W Br(W→ μ v)/ σ z Br( Z → μμ )=10.4 −1.5 +1.8 stat.±0.8(syst.) We find R =9.5 −1.0 +1.1 (stat.+syst.) when combining all available UA1 data, in both the electron and muon channel, taken in the period 1983–1989. In the framework of the standard model, the value of R is used to infer the total width of the W boson, Γ W tot =2.18 −0.24 +0.26 (exp.)±0.04(theory) GeV/ c 2 .
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The photon structure function F 2 has been measured at average Q 2 values of 73,160 and 390 ( GeV c ) 2 . We compare the x dependence of the Q 2 = 73 ( GeV c ) 2 data with theoretical expectations based on QCD. In addition we present results on the Q 2 evolution of the structure function for the intermediate x range (0.3⩽ x ⩽0.8). The results are consistent with QCD.
X dependence at Q**2 = 73 GeV**2 for light quark data.
X dependence at Q**2 = 73 GeV**2 for total data.
Photon structure function F2 for total data.
From an analysis of multi-hadron events from Z 0 decays, values of the strong coupling constant α s ( M 2 Z 0 )=0.131±0.006 (exp)±0.002(theor.) and α s ( M z 0 2 ) = −0.009 +0.007 (exp.) −0.002 +0.006 (theor.) are derived from the energy-energy correlation distribution and its asymmetry, respectively, assuming the QCD renormalization scale μ = M Z 0 . The theoretical error accounts for differences between O ( α 2 s ) calculations. A two parameter fit Λ MS and the renormalization scale μ leads to Λ MS =216±85 MeV and μ 2 s =0.027±0.013 or to α s ( M 2 Z 0 )=0.117 +0.006 −0.008 (exp.) for the energy-energy correlation distribution. The energy-energy correlation asymmetry distribution is insensitive to a scale change: thus the α s value quoted above for this variable includes the theoretical uncertainty associated with the renormalization scale.
Data are at the hadron level, unfolded for initial-state radiation and for detector acceptance and resolution. Note that the systematic errors between bins are correlated.
Alpha-s determined from the EEC measurements. The systematic error is an error in the theory.
Alpha-s determined from the AEEC measurements. The systematic error is an error in the theory.
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