[Show abstract][Hide abstract] ABSTRACT: The process p̄p→evy+X is studied as √s=630 GeV The observed signal is used to extract a direct measurement of the parameters κ and λ which define the magnetic dipole and electric quadrupole moments of the W boson and therefore the WWγ coupling We find κ=1-2 2+2 6 and λ=0-1 8+1 7 and their 95% confidence limits - 3 5 < κ < 5 9 and -3 6 < λ < 3 5 The results are model independent and in good agreement with the standard model values, κ=1 and λ=0.
[Show abstract][Hide abstract] ABSTRACT: The process ppBAR --> e-nu-gamma + X is studied as square-root s = 630 GeV. The observed signal is used to extract a direct measurement of the parameters-kappa and lambda which define the magnetic dipole and electric quadrupole moments of the W boson and therefore the WW-gamma coupling. We find kappa = 1(-2.2)+2.6 and lambda = 0(-1.8)+1.7 and their 95% confidence limits -3.5 < kappa < 5.9 and -3.6 < lambda < 3.5. The results are model independent and in good agreement with the standard model values, kappa = 1 and lambda = 0.
Physics Letters B 02/1992; 277(1-2):194-202. DOI:10.1016/0370-2693(92)90979-E · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The decays W→ev and Z→e+e- are studied in pp collisions at √s=630 GeV. The products of production cross section and branching ratio are measured as σWe = 682±12±40 pb and σZe= 65.6±4.0±3.8 pb. The results are in good agreement with O(αs2) calculations of the production cross sections. Many systematic effects cancel in the ratio, R=10.4±0.60.7±0.3, which can be used to give an indirect measurement of the total width of the W boson: ΓW=2.10±0.13±0.09 GeV. The width gives a limit on the top quark mass, mtop > 53 GeV (95% CL), which is independent of the top decay mode.
[Show abstract][Hide abstract] ABSTRACT: The W and Z bosons masses, m(W) and m(Z), are measured using samples of W --> ev and Z --> e+e- decays observed in ppBAR collisions at square-root s = 630 GeV. The ratio is found to be m(W)/m(Z) = 0.8813 +/- 0.0036 +/- 0.0019. This gives a value sin2 theta(w) = 0.2234 +/- 0.0064 +/- 0.0033, and in combination with precise m(Z) measurements from LEP yields m(W) = 80.35 +/- 0.33 +/- 0.17 GeV. This result is in good agreement with other experiments, and with the standard model for a top quark mass lighter than 250 GeV.
Physics Letters B 02/1992; 276(3-276):354-364. DOI:10.1016/0370-2693(92)90332-X · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Results are given on a search for the decay W±→π±γ with the UA2 detector in collisions at √s=630 GeV. No signal for such a process is observed and upper limits on the ration R=Γ(W±→π±γ)/Γ(W±→e±v)<4.9×10−3 and on the branching ratio BR(W±→π±γ)<5.4×10−4 are derived at 95% confidence level.
[Show abstract][Hide abstract] ABSTRACT: Results on the cross section for the production of electron pairs in ppBAR collisions at square-root s = 630 GeV are presented. The measured value is sigma = 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(alpha(s)2) QCD contributions. The comparison of these data with those of lower energy experiments show approximate scaling as a function of the variable square-root tau = m/ square-root s.
Physics Letters B 01/1992; 275(1-2). DOI:10.1016/0370-2693(92)90876-6 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A measurement of the cross-sections for single and double prompt photon production in pp interactions at √5 = 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.
[Show abstract][Hide abstract] ABSTRACT: Summary form only given. A research and development program is being conducted in view of realizing an electromagnetic and hadronic calorimeter for the Large Hadron Collider (LHC). The authors report on tests on fast electronics, coupled to an electromagnetic prototype calorimeter built with an accordion structure. Three different types of preamplifiers have been used. In two (Si and GaAs hybrids), the preamplifier is operated in liquid argon. In the third one, a common based (Si JFET or GaAs) transistor is in the liquid, the charge preamplifier being outside the cryostat, after about 6 m of 50-Ω cable. The shaping amplifier uses RC-CR filtering. The response to a short current pulse peaks after about 20 ns. When the system is connected to the calorimeter, the liquid argon signals peak, as expected, after 30 ns. Noise, linearity, and cross-talk between channels were investigated. First results from an exposure of the calorimeter to electrons of energy 30 to 175 GeV were obtained
Nuclear Science Symposium and Medical Imaging Conference, 1991., Conference Record of the 1991 IEEE; 12/1991
[Show abstract][Hide abstract] ABSTRACT: The first prototype of a lead-liquid-argon e.m. calorimeter with accordion-shaped absorber and electrode plates has been built and tested with electron and muon beams at the CERN SPS. This novel geometry combines good granularity with high readout speed and minimal dead space. For a response peaking time of 140 ns, an energy resolution of 10%/sqrt(E[GeV]) and a space resolution of 4.4 mm/sqrt(E[GeV]) with a 2.7 cm cell size have been achieved for electrons. The position accuracy for muons is better than 2 mm.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 11/1991; 309(3). DOI:10.1016/0168-9002(91)90247-N · 1.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A study of events containing at least four high transverse momentum jets and a search for double parton scattering (DPS) have been performed using data collected with the UA2 detector at the CERN p Collider (√s=630 GeV). The results are in good agreement with leading order QCD calculations. A value of σDPS<0.82 nb at 95% confidence level (CL) is obtained for the DPS cross section.
[Show abstract][Hide abstract] ABSTRACT: 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.
Physics Letters B 07/1991; 263(3-263):544-550. DOI:10.1016/0370-2693(91)90503-I · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The large sample of W→eν events collected by the UA2 experiment at the CERN pp̄ collider between 1988 and 1990 has been used to determine the strong coupling constant αs. From a measurement of the ratio of the production rate of W events with one jet to that with no jets, αs has been extracted to second order in the scheme: .
[Show abstract][Hide abstract] ABSTRACT: The ratio of branching fractions of theW decaying to [`(p)]p\bar pp
Ös = 630\sqrt s = 630
GeV. The ratio of the electroweak charged current couplings to theW is then determined to beg
=0.9970.056 (stat.)0.042 (syst.). The decay modeZ++ is observed and also found to be consistent withe- universality.
Zeitschrift für Physik C 05/1991; 52(2):209-218. DOI:10.1007/BF01560438