A measurement of the gluon structure fusion using direct photon events observed with the UA2 detector in p p collisions at √ s =630 GeV is presented. The x -range covered by this analysis is between 0.049 and 0.207 and the Q 2 range is between 280 GeV 2 and 3670 GeV 2 . The data sample corresponds to an integrated luminosity of 7.14 pb −1 . The results are found to be in good agreement with the gluon distributions measured in deep inelastic scattering experiments extrapolated to the UA2 Q 2 values.
X(Q=PARTON) and Q**2 are mean values.
A measurement of the cross-sections for single and double prompt photon production in p p interactions at s = 630 GeV is presented. The data sample corresponds to an integrated luminosity of 13.2 pb −1 . The results are in good agreement with the predictions of perturbative QCD. The signal from double prompt photon production has a statistical significance of 4.3 standard deviations.
There is an overall systematic error of 9 pct not included in the table.
Errors quoted include statistical and all PT dependent systematic uncertainties. There is in addition a 6.8 pct overall normalization uncertainty.
Results on the cross section for the production of electron pairs in p p collisions at √ s = 630 GeV are presented. The measured value is σ = 405 ± 51 (syst.) ± 84 (syst.) pb, in the invariant mass interval 10 < m < 70 GeV. The results are compared to recent theoretical calculations which include O( α s 2 ) QCD contributions. The comparison of these data with those of lower energy experiments show approximate scaling as a function of the variable √τ = m √s .
No description provided.
Statistical and systematic errors combined.
Statistical errors only.
The decays W → ev and Z → e + e − are studied in [ovbar|p]p collisions at √ s =630 GeV . The products of production cross section and branching ratio are measured as σ e w =682±12±40 pb and σ e w =65.6±4.0±3.8 pb. The results are in good agreement with O(α 2 s ) calculations of the production cross sections. Many systematic effects cancel in the ratio, R =10.4± 0.7 0.6 ±0.3, which can be used to give an indirect measurement of the total width of the W boson: Γ w =2.10±0.13±0.09 GeV . The width gives a limit on the top quark mass, m top >53 GeV (95% CL), which is independent of the top decay mode.
No description provided.
A measurement of the inclusive cross-section for production of direct photons in p̄p collisions at a centre of mass energy of 630 GeV is presented as a function of the photon transverse momentum. The data correspond to a total integrated luminosity of 7.4 pb −1 . The results support predictions from QCD theory.
No description provided.
The inclusive jet cross-section has been measured at the CERN p p Collider ( s = 630 GeV ) as a function of the jet transverse momentum ( p T ) and pseudorapidity ( η ) for p T values up to 180 GeV and for−2< η <2. The results are consistent with leading order QCD calculations, and a lower limit Λ c >825 GeV (95% CL ) is set on the quark compositeness scale Λ c .
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The transverse momentum distributions ofW andZ bosons produced in\(\bar pp\) collisions at\(\sqrt s= 630 GeV\) are examined. Comparisons are made with QCD predictions, and good agreement is found. The fraction ofW bosons produced withpT>25 GeV is found to be 3.8±0.6(stat)−1.3+0.9(syst)%.
No description provided.
Combining the cross section for pbar p --> W X * BR(W --> E NU) given in Alitti et al, ZP C47 (90) 11. (660 +- 15 (DSYS=37) pb).
A study of the two-jet mass spectrum measured with the UA 2 calorimeter has revealed a signal from hadronic decays ofW andZ bosons above a large background. Production and decay properties of the signal have been measured. The combined production cross-section σ·B(W, Z → two jets) is 9.6±2.3 (stat.)±1.1 (syst.) nb, compared with an expectation of 5.8 nb calculated to order αs2. A limit on the production cross-section of additional heavy vector bosons decaying into two jets is given as a function of the boson mass.
No description provided.
Results on the production cross sections ofW andZ bosons detected in the UA2 experiment are given based on a large sample ofW→eν andZ→e+e− decays. The measured cross sections are σWe = 660±15(stat)±37(syst)pb, σZe = 70.4±5.5(stat)±4.0(syst)pb and their ratioR=9.38−0.72+0.82(stat)±0.25(syst). In the framework of the Standard Model, the measured value ofR is used to determine the total width of theW, Γ(W)=2.30±0.19(stat)±0.06(syst) GeV.
No description provided.
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A measurement of the direct production of photons with high transverse momentum from\(\bar pp\) collisions at\(\sqrt s= 630\) GeV is presented. The structure of events containing a high transverse momentum photon is studied. The results support predictions from QCD theory.
The last data point is an average over the interval 60-100 GeV in which 5 events are found.
No description provided.
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