We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W({yields}l{nu})+{gamma} production in e{gamma} and {mu}{gamma} final states. Using ...data corresponding to an integrated luminosity of 4.2 fb{sup -1} collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp{yields}W{gamma}+X{yields}l{nu}{gamma}+X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW{gamma} couplings for data from hadron colliders: -0.4<{Delta}{kappa}{sub {gamma}<}0.4 and -0.08<{lambda}{sub {gamma}<}0.07 at the 95% C.L.
We present measurements of the differential cross section d I / d p T gamma for the associated production of a c-quark jet and an isolated photon with rapidity | y gamma | 15 GeV . The ratio of ...differential cross sections for gamma + c to gamma + b production as a function of p T gamma is also presented. The results are based on data corresponding to an integrated luminosity of 8.7 fb - 1 recorded with the D0 detector at the Fermilab Tevatron p p A= Collider at s = 1.96 TeV . The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the k T -factorization approach, and to predictions from the sherpa and pythia Monte Carlo event generators.
We present searches for the anomalous gamma WW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from W gamma , WW, ...and WZ production with leptonic final states. The analyzed data correspond to up to 8.6 fb - 1 of integrated luminosity collected by the D0 detector in p p A= collisions at s = 1.96 TeV . We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters I kappa gamma , I>, and I g 1 Z for a cutoff energy scale I = 2 TeV . The combined 68% C.L. limits are - 0.057 < I kappa gamma < 0.154 , - 0.015 < 0.028 , and - 0.008 < I g 1 Z < 0.054 for the LEP parameterization, and - 0.007 < I kappa < 0.081 and - 0.017 < 0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.
We present a search for the standard model Higgs boson and a fermiophobic Higgs boson in the diphoton final states based on 8.2 fb{sup -1} of pp collisions at {radical}(s)=1.96 TeV collected with the ...D0 detector at the Fermilab Tevatron Collider. No excess of data above background predictions is observed and upper limits at the 95% C.L. on the cross section multiplied by the branching fraction are set which are the most restrictive to date. A fermiophobic Higgs boson with a mass below 112.9 GeV is excluded at the 95% C.L.
We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an ...integrated luminosity of 7.3 fb{sup -1}. This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tan{beta}. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limits on the cross section times branching ratio in the Higgs boson mass range from 90 to 320 GeV/c{sup 2}. We interpret our result in the MSSM parameter space, excluding tan{beta} values down to 25 for Higgs boson masses below 170 GeV/c{sup 2}.
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to ...parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance IR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of IR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in p p A= collisions at s = 1.96 TeV . The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50a400 GeV.
We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb{sup -1} collected ...with the D0 detector at {radical}(s)=1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c{sup 2}. The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at 145 GeV/c{sup 2} is 8x10{sup -6}.
We search for resonant WW or WZ production by using up to 5.4 fb{sup -1} of integrated luminosity collected by the D0 experiment in run II of the Fermilab Tevatron Collider. The data are consistent ...with the standard model background expectation, and we set limits on a resonance mass by using the sequential standard model W{sup '} boson and the Randall-Sundrum model graviton G as benchmarks. We exclude a sequential standard model W{sup '} boson in the mass range 180-690 GeV and a Randall-Sundrum graviton in the range 300-754 GeV at 95% C.L.
We present a search for the standard model Higgs boson in 9.5 fb-1 of p p A= collisions at s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered ...contains a pair of b jets and is characterized by an imbalance in transverse energy, as expected from p p A= ? Z H ? ? ? A= b b A= production. The search is also sensitive to the W H ? l ? b b A= channel when the charged lepton is not identified. The data are found to be in good agreement with the expected background. For a Higgs boson mass of 125 GeV, we set a limit at the 95% C.L. on the cross section s (p p A= ? Z / W H) , assuming standard model branching fractions, that is a factor of 4.3 times larger than the theoretical standard model value, while the expected factor is 3.9. The search is also used to measure a combined WZ and ZZ production cross section that is a factor of 0.94 +/- 0.31 (stat) +/- 0.34 (syst) times the standard model prediction of 4.4 pb, with an observed significance of 2.0 standard deviations.
We present a search for the standard model Higgs boson (H) in pp collisions at {radical}(s)=1.96 TeV in events containing a charged lepton (l), missing transverse energy, and at least two jets, using ...5.4 fb{sup -1} of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay H{yields}WW{yields}l{nu}q{sup '}q, where l is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH{yields}l{nu}bb. In the absence of a signal, we set limits at the 95% C.L. on the cross section for H production {sigma}(pp{yields}H+X) in these final states. For a mass of M{sub H}=160 GeV, the limit is a factor of 3.9 larger than the cross section in the standard model and consistent with an a priori expected sensitivity of 5.0.
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