The Standard Model predictions for $W\gamma$ and $Z\gamma$ production are tested using an integrated luminosity of 200 pb$^{-1}$ of \ppbar collision data collected at the Collider Detector at Fermilab. The cross sections are measured selecting leptonic decays of the $W$ and $Z$ bosons, and photons with transverse energy $E_T>7$ GeV that are well separated from leptons. The production cross sections and kinematic distributions for the $W\gamma$ and $Z\gamma$ are compared to SM predictions.
Measured cross sections for W+ GAMMA production.
Measured cross sections for Z0 GAMMA production.
Charmonium production in p – A collisions is a unique tool for the study of the interaction of bound c c states in nuclear matter. It can provide details on the basic features of the resonance formation mechanism and, in particular, on its non-perturbative aspects. In this Letter, we present an experimental study of charmonia and Drell–Yan production in proton–nucleus collisions at 450 GeV/ c . The results are analyzed in the framework of the Glauber model and lead to the values of the nuclear absorption cross-section σ abs pA for J / ψ and ψ ′. Then, we compare the J / ψ absorption in proton–nucleus and sulphur–uranium interactions, using NA38 data. We obtain that, for the J / ψ , σ abs pA and σ abs SU are compatible, showing that no sizeable additional suppression mechanism is present in S–U collisions, and confirming that the anomalous J / ψ suppression only sets in for Pb–Pb interactions.
The J/PSI production cross section times the branching ratio to MU+ MU- pernucleon-nucleon collision for the differential nuclear targets.
The PSI(3685) production cross section times the branching ratio to MU+ MU-per nucleon-nucleon collision for the differential nuclear targets.
The Drell Yan cross section, divided by the mass number A, and multiplied by the isospin correction factors in the mass interval 2.9 to 4.5 GeV.
We report on measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential cross sections (d2σ/dpTdy)|y|<0.4, as well as on the ϒ(1S) polarization in pp¯ collisions at s=1.8TeV using a sample of 77±3pb−1 collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay ϒ→μ+μ−. The measured angular distribution of the muons in the ϒ(1S) rest frame is consistent with unpolarized meson production.
The differential cross section times the branching ratio into mu+ mu- for UPSILON(1S) production.
The differential cross section times the branching ratio into mu+ mu- for UPSILON(2S) production. The first DSYS error is the systematic error due to the polarization of the UPSILON which is shown seperately from the other systematic errors.
The differential cross section times the branching ratio into mu+ mu- for UPSILON(3S) production. The first DSYS error is the systematic error due to the polarization of the UPSILON which is shown seperately from the other systematic errors.
The observation of an anomalous J/ ψ suppression in Pb–Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/ ψ suppression pattern as a function of the forward hadronic energy E ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between E ZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N part and E ZDC . Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/ ψ suppression as a function of the number of participants.
Minimum Bias E(C=ZDC) spectrum. Data extracted from fig with g3data, statistical errors not included and are set to 0, the systematic errors given by g3data due to extraction.
Number of participants as a function of E(C=ZDC) Data exctracted from fig with g3data, the systematic errors given by g3data due to extraction, and those marked (stat) are in this case the r.m.s. of the Npart distribution at fixed E(C=ZDC).;.
SIG(J/PSI)/SIG(DY) as a function of E(C=ZDC) with the standard analyses of the 1996 DATA 1996, standard analyses.
We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A_FB, and production cross section dsigma/dM for e+e- pairs with mass M_ee>40 GeV/c2. The data sample consists of 108 pb-1 of p-pbar collisions at sqrt(s)=1.8 TeV taken by the Collider Detector at Fermilab during 1992-1995. The measured asymmetry and dsigma/dM are compared with the predictions of the Standard Model and a model with an extra Z' gauge boson.
The E+ E- production cross section and the forward-backward asymmetry. The errors contain the statistical and systematic uncertainties combined in quadrature, but not the additional uncertainty of the luminosity.
The forward, backward and total production cross sections for dielectron production for the mass regions above 105 GeV. The errors contain the statistical and systematic uncertainties combined in quadrature, but not the additional uncertainty of the luminosity.
The production cross section for di-muons for the mass region above 105 GeV. The errors contain the statistical and systematic uncertainties combined in quadrature, but not the additional uncertainty of the luminosity.
We present measurements of the semi-inclusive cross sections for νμ- and ν¯μ-nucleon deep inelastic scattering interactions with two oppositely charged muons in the final state. These events dominantly arise from the production of a charm quark during the scattering process. The measurement was obtained from the analysis of 5102 νμ-induced and 1458 ν¯μ-induced events collected with the NuTeV detector exposed to a sign-selected beam at the Fermilab Tevatron. We also extract a cross-section measurement from a reanalysis of 5030 νμ-induced and 1060 ν¯μ-induced events collected from the exposure of the same detector to a quad-triplet beam by the Chicago Columbia Fermilab Rochester (CCFR) experiment. The results are combined to obtain the most statistically precise measurement of neutrino-induced dimuon production cross sections to date. These measurements should be of broad use to phenomenologists interested in the dynamics of charm production, the strangeness content of the nucleon, and the Cabibbo-Kobayashi-Maskawa matrix element Vcd.
NuTeV forward cross section of neutrino induced events at mean energy of 90.18 GeV.
NuTeV forward cross section of neutrino induced events at mean energy of 174.37 GeV.
NuTeV forward cross section of neutrino induced events at mean energy of 244.72 GeV.
Muon pairs produced in Pb–Pb interactions at 158 GeV/ c per nucleon are used to study the transverse momentum distributions of the J/ ψ , ψ ′ and dimuons in the mass continuum. In particular, the dependence of these distributions on the centrality of the Pb–Pb collision is investigated in detail.
Mean values of PT and PT**2 calculated from the IMR distributions.
Mean values of PT and PT**2 calculated from the J/PSI distributions.
Mean values of PT and PT**2 calculated from the PSI(3685) distributions.
We report on measurements of hadronic and leptonic cross sections and leptonic forward-backward asymmetries performed with the L3 detector in the years 1993-95. A total luminosity of 103 pb^-1 was collected at centre-of-mass energies \sqrt{s} ~ m_Z and \sqrt{s} ~ m_Z +/- 1.8 GeV which corresponds to 2.5 million hadronic and 245 thousand leptonic events selected. These data lead to a significantly improved determination of Z parameters. From the total cross sections, combined with our measurements in 1990-92, we obtain the final results: m_Z = 91189.8 +/- 3.1 MeV, Gamma_Z = 2502.4 +/- 4.2 MeV, Gamma_had = 1741.1 +/- 3.8 MeV, Gamma_l = 84.14 +/- 0.17 MeV. An invisible width of Gamma_inv = 499.1 +/- 2.9 MeV is derived which in the Standard Model yields for the number of light neutrino species N_nu = 2.978 +/- 0.014. Adding our results on the leptonic forward-backward asymmetries and the tau polarisation, the effective vector and axial-vector coupling constants of the neutral weak current to charged leptons are determined to be \bar{g}_V^l = -0.0397 +/- 0.0017 and \bar{g}_A^l = -0.50153 +/- 0.00053.Including our measurements of the Z -> b \bar{b} forward-backward and quark charge asymmetries a value for the effective electroweak mixing angle of sin^2\bar{\theta}_W = 0.23093 +/- 0.00066 is derived. All these measurements are in good agreement with the Standard Model of electroweak interactions. Using all our measurements of electroweak observables an upper limit on the mass of the Standard Model Higgs boson of m_H < 133 GeV is set at 95% confidence level.
Updated values of coupling constants and electroweak mixing angle.
Cross sections for hadron production from the 1993 data. The first DSYS error is the uncorrelated part of the systematic error. The second DSYS error is from the statistical error on the absolute luminosity. In addition there is a fully correlated multiplicative contribution to the systematic error of 0.039 PCT plus an absolute uncertainty of 3.2pb together with an additional error from the absolute luminosity of 0.105 PCT.
Cross sections for hadron production from the 1994 data. The first DSYS error is the uncorrelated part of the systematic error. The second DSYS error is from the statistical error on the absolute luminosity. In addition there is a fully correlated multiplicative contribution to the systematic error of 0.039 PCT plus an absolute uncertainty of 3.2pb together with an additional error from the absolute luminosity of 0.088 PCT.
An analysis of the data collected in 1997 and 1998 with the DELPHI detector at e+e- collision energies close to 183 and 189 GeV was performed in order to extract the hadronic and leptonic fermion-pair cross-sections, as well as the leptonic forward-backward asymmetries and angular distributions. The data are used to put limit on contact interactions between fermions, the exchange of R-parity violating SUSY sneutrinos, Z' bosons and the existence of gravity in extra dimensions.
No description provided.
No description provided.
No description provided.
During 1993 and 1995 LEP was run at 3 energies near the Z$^0$peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP o
Hadronic cross section measured with the 1993 data. Additional systematic error of 0.10 PCT (efficiencies and backgrounds) and 0.29 PCT (absolute luminosity).
Hadronic cross section measured with the 1994 data. Additional systematic error of 0.11 PCT (efficiencies and backgrounds) and 0.11 PCT (absolute luminosity).
Hadronic cross section measured with the 1995 data. Additional systematic error of 0.10 PCT (efficiencies and backgrounds) and 0.11 PCT (absolute luminosity).
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