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  • 1051. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of the pp(-)-> W gamma plus X cross section at root s=1.96 TeV and WW gamma anomalous coupling limits2005In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 71, no 9, p. 091108-Article in journal (Refereed)
    Abstract [en]

    The WW gamma triple gauge boson coupling parameters are studied using p (p) over bar -> l nu gamma + X(l = e, mu) events at root s = 1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162 pb(-1) delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p (p) over bar -> W(gamma) + X -> l nu gamma + X with E-T(gamma) > 8 GeV and Delta R-l gamma > 0.7 is 14.8 +/- 1.6(stat) +/- 1.0(syst) +/- 1.0(lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa(gamma) < 0.96 and -0.20 < lambda(gamma) < 0.20.

  • 1052. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV in dilepton final states2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 626, p. 55-64Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the top quark pair (a) production cross section in pp collisions at root s = 1.96 TeV using events with two charged leptons in the final state. This analysis utilizes an integrated luminosity of 224-243 pb(-1) collected with the DO detector at the Fermilab Tevatron Collider. We observe 13 events in the e(+)e(-), e mu and mu(+)mu(-) channels with an expected background of 3.2 +/- 0.7 events. For a top quark mass of 175 GeV, we measure a t (t) over bar production cross section of sigma(t (t) over bar) = 8.6(-2.7)(+3.2) (stat) +/- 1.1(syst) +/- 0.6(lumi) pb, consistent with the standard model prediction.

  • 1053. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV using kinematic characteristics of lepton plus jets events2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 626, p. 45-54Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the top quark pair (t (t) over bar) production cross section (sigma(t (t) over bar)) in pp collisions at a center-of-mass energy of 1.96 TeV using 230 pb(-1) of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the t (t) over bar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(t (t) over bar) 6.7(-1.3)(+1.4)(stat)(-1.1)(+1.6)(syst) +/- 0.4(lumi) pb, in good agreement with the standard model prediction.

  • 1054. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of the t(t)over-bar production cross section in p(p)over-bar collisions at root s=1.96 TeV using lepton plus jets events with lifetime b-tagging2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 626, p. 35-44Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the top quark pair (t (t) over bar) production cross section (sigma(t (t) over bar)) in pp collisions at root s = 1.96 TeV using 230 pb(-1) of data collected by the DO experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the t F purity of the selected sample. For a top quark mass of 175 GeV, we measure sigma(t (t) over bar) 8.6(-1.5)(+1.6) (stat. + syst.) +/- 0.6(lumi.) pb, in agreement with the standard model expectation.

  • 1055. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Production of WZ events in pp(-) collisions at root s=1.96 TeV and limits on anomalous WWZ couplings2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 14, p. 141802-Article in journal (Refereed)
    Abstract [en]

    We present results from a search for WZ production with subsequent decay to l nu l'(l) over bar'(l and l' = e or mu) using 0.30 fb(-1) of data collected by the D0 experiment between 2002 and 2004 at the Fermilab Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71 +/- 0.08 events, we measure the WZ production cross section to be 4.5(-2.6)(+3.8) pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0 <Delta kappa(Z)< 2.4 for form factor scale Lambda=1 TeV, and -0.48 <lambda(Z)< 0.48 and -0.49 <Delta g(1)(Z)< 0.66 for Lambda=1.5 TeV.

  • 1056. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for large extra spatial dimensions in dimuon production with the D0 detector2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 16, p. 161602-Article in journal (Refereed)
    Abstract [en]

    We present the results of a search for the effects of large extra spatial dimensions in p (p) over bar collisions at root s = 1: 96 TeV in events containing a pair of energetic muons. The data correspond to 246 pb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C. L. lower limits on the fundamental Planck scale between 0.85 and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date.

  • 1057. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for neutral supersymmetric Higgs bosons in multijet events at root s=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 15, p. 151801-Article in journal (Refereed)
    Abstract [en]

    We have performed a search for neutral Higgs bosons produced in association with bottom quarks in p (p) over bar collisions, using 260 pb(-1) of data collected with the D0 detector in Run II of the Fermilab Tevatron Collider. The cross sections for these processes are enhanced in many extensions of the standard model (SM), such as in its minimal supersymmetric extension at large tan beta. The results of our analysis agree with expectations from the SM, and we use our measurements to set upper limits on the production of neutral Higgs bosons in the mass range of 90 to 150 GeV.

  • 1058. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for randall-sundrum gravitons in dilepton and diphoton final states2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 9, p. 091801-Article in journal (Refereed)
    Abstract [en]

    We report the first direct search for the Kaluza-Klein (KK) modes of Randall-Sundrum gravitons using dielectron, dimuon, and diphoton events observed with the D0 detector operating at the Fermilab Tevatron p (p) over bar Collider at root s = 1: 96 TeV. No evidence for resonant production of gravitons has been found in the data corresponding to an integrated luminosity of approximate to 260 pb(-1). Lower limits on the mass of the first KK mode at the 95% C. L. have been set between 250 and 785 GeV, depending on its coupling to standard model particles.

  • 1059. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for right-handed W bosons in top quark decay2005In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 72, no 1, p. 011104-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the fraction f(+) of right-handed W bosons produced in top quark decays, based on a candidate sample of t (t) over bar events in the lepton+jets decay mode. These data correspond to an integrated luminosity of 230 pb(-1), collected by the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s=1.96 TeV. We use a constrained fit to reconstruct the kinematics of the t (t) over bar and decay products, which allows for the measurement of the leptonic decay angle theta(*) for each event. By comparing the cos theta(*) distribution from the data with those for the expected background and signal for various values of f(+), we find f(+)=0.00 +/- 0.13(stat)+/- 0.07(syst). This measurement is consistent with the standard model prediction of f(+)=3.6 x 10(-4).

  • 1060. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for single top quark production in pp collisions at root s=1.96 TeV2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 622, no 3-4, p. 265-276Article in journal (Refereed)
    Abstract [en]

    We present a search for electroweak production of single top quarks in the s-channel and t-channel using neural networks for signal-background separation. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron Collider at a center-of-mass energy of 1.96 TeV and find no evidence for a single top quark signal. The resulting 95% confidence level upper limits on the single top quark production cross sections are 6.4 pb in the s-channel and 5.0 ph in the t-channel.

  • 1061. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Search for supersymmetry via associated production of charginos and neutralinos in final states with three leptons2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 15, p. 151805-Article in journal (Refereed)
    Abstract [en]

    A search for associated production of charginos and neutralinos is performed using data recorded with the D0 detector at a p (p) over bar center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider. This analysis considers final states with missing transverse energy and three charged leptons, of which at least two are electrons or muons. No evidence for supersymmetry is found in a data set corresponding to an integrated luminosity of 320 pb(-1). Limits on the product of the production cross section and leptonic branching fraction are set. For the minimal supergravity model, a chargino lower mass limit of 117 GeV at the 95% C.L. is derived in regions of parameter space with enhanced leptonic branching fractions.

  • 1062. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E.G.
    et al.,
    Limits on anomalous trilinear gauge couplings from WW -> e(+)e(-), WW -> e(+/-)mu(-/+), and WW ->mu(+)mu(-) events from pp collisions at root s=1.96 TeV2006In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 74, no 5, p. 057101-Article in journal (Refereed)
    Abstract [en]

    Limits are set on anomalous WW gamma and WWZ trilinear gauge couplings using W+W--> e(+)nu(e)e(-)(nu) over bar (e), W+W--> e(+/-)nu(e)mu(-/+)nu(mu), and W+W-->mu(+)nu(mu)mu(-)(nu) over bar (mu) events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250 pb(-1) of integrated luminosity at root s=1.96 TeV. Under the assumption that the WW gamma couplings are equal to the WWZ couplings and using a form factor scale of Lambda=2.0 TeV, the combined 95% C.L. one-dimensional coupling limits from all three channels are -0.32 <Delta kappa < 0.45 and -0.29 <lambda < 0.30.

  • 1063. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E.G.
    et al.,
    Search for neutral, long-lived particles decaying into two muons in p(p)over-bar collisions at root s=1.96 TeV2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 16, p. 161802-Article in journal (Refereed)
    Abstract [en]

    We present a search for a neutral particle, pair produced in pp collisions at root s=1.96 TeV, which decays into two muons and lives long enough to travel at least 5 cm before decaying. The analysis uses approximate to 380 pb(-1) of data recorded with the D0 detector. The background is estimated to be about one event. No candidates are observed, and limits are set on the pair-production cross section times branching fraction into dimuons + X for such particles. For a mass of 10 GeV and lifetime of 4x10(-11) s, we exclude values greater than 0.14 pb (95% C.L.). These results are used to limit the interpretation of NuTeV's excess of dimuon events.

  • 1064. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E.G.
    et al.,
    Search for pair production of scalar bottom quarks in p(p)over-bar collisions at root s = 1.96 TeV2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 17, p. 171806-Article in journal (Refereed)
    Abstract [en]

    A search for direct production of scalar bottom quarks ((b) over bar) is performed with 310 pb(-1) of data collected by the D0 experiment in p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (chi(0)(1)), with chi(0)(1) assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m(b), m(chi 1)(0)) mass plane, improving significantly upon the results from run I of the Tevatron.

  • 1065. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Direct limits on the B(s)(0) oscillation frequency2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 2, p. 021802-Article in journal (Refereed)
    Abstract [en]

    We report results of a study of the B(s)(0) oscillation frequency using a large sample of B(s)(0) semileptonic decays corresponding to approximately 1 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider in 2002-2006. The amplitude method gives a lower limit on the B(s)(0) oscillation frequency at 14.8 ps(-1) at the 95% C.L. At Delta m(s)=19 ps(-1), the amplitude deviates from the hypothesis A=0 (1) by 2.5 (1.6) standard deviations, corresponding to a two-sided C.L. of 1% (10%). A likelihood scan over the oscillation frequency, Delta m(s), gives a most probable value of 19 ps(-1) and a range of 17 <Delta m(s)< 21 ps(-1) at the 90% C.L., assuming Gaussian uncertainties. This is the first direct two-sided bound measured by a single experiment. If Delta m(s) lies above 22 ps(-1), then the probability that it would produce a likelihood minimum similar to the one observed in the interval 16-22 ps(-1) is (5.0 +/- 0.3)%.

  • 1066. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Measurement of beta (t -> Wb)/beta(t -> Wq) at root s=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 639, no 6, p. 616-622Article in journal (Refereed)
    Abstract [en]

    We present the measurement of R = B(t -> Wb)/B(t -> Wq) in pp collisions at root s = 1.96 TeV, using 230 pb(-1) of data collected by the DO experiment at the Fermilab Tevatron Collider. We fit simultaneously R and the number (N-tt) of selected top quark pairs (tt), to the number of identified b-quark jets in events with one electron or one muon, three or more jets, and high transverse energy imbalance. To improve sensitivity, kinematical properties of events with no identified b-quark jets are included in the fit. We measure R = 1.03(-0.17)(0.19) (stat + syst), in good agreement with the standard model. We set lower limits of R > 0.61 and vertical bar V-tb vertical bar > 0.78 at 95% confidence level.

  • 1067. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Stockholms universitet.
    Zverev, E. G.
    et al.,
    Measurement of the B-s(0) lifetime using semileptonic decays2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 24, p. 241801-Article in journal (Refereed)
    Abstract [en]

    We report a measurement of the B-s(0) lifetime in the semileptonic decay channel B-s(0)-> D-s(-)mu(+)nu X (and its charge conjugate), using approximately 0.4 fb(-1) of data collected with the D0 detector during 2002-2004. Using 5176 reconstructed D-s(-)mu(+) signal events, we have measured the B-s(0) lifetime to be tau(B-s(0))=1.398 +/- 0.044(stat)(-0.025)(+0.028)(syst) ps. This is the most precise measurement of the B-s(0) lifetime to date.

  • 1068. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Measurement of the isolated photon cross section in p(p)over-bar collisions at root s=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 639, no 3-4, p. 151-158Article in journal (Refereed)
    Abstract [en]

    The cross section for the inclusive production of isolated photons has been measured in p (p) over bar collisions at root s = 1.96 TeV with the DO detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity vertical bar n vertical bar < 0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.

  • 1069. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for a heavy resonance decaying into a Z plus jet final state in p(p)over-bar collisions at root s=1.96 TeV using the D0 detector2006In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 74, no 1, p. 011104-Article in journal (Refereed)
    Abstract [en]

    We have searched for a heavy resonance decaying into a Z+jet final state in p (p) over bar collisions at a center of mass energy of 1.96 TeV at the Fermilab Tevatron collider using the D0 detector. No indication for such a resonance was found in a data sample corresponding to an integrated luminosity of 370 pb(-1). We set upper limits on the cross section times branching fraction for heavy resonance production at the 95% C.L. as a function of the resonance mass and width. The limits are interpreted within the framework of a specific model of excited quark production.

  • 1070. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for associated Higgs boson production WH -> WWW*-> l(+/-)nu l('+/-)nu(')+X in p(p)over-bar collisions at root S=1.96 TeV2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 15, p. 151804-Article in journal (Refereed)
    Abstract [en]

    We present a search for associated Higgs boson production in the process p (p) over bar -> WH -> WWW*-> l(+/-)nu l('+/-)nu(')+X in final states containing two like-sign isolated electrons or muons (e(+/-)e(+/-), e(+/-)mu(+/-), or mu(+/-)mu(+/-)). The search is based on D0 run II data samples corresponding to integrated luminosities of 360-380 pb(-1). No excess is observed over the predicted standard model background. We set 95% C.L. upper limits on sigma ->(p (p) over bar WH) x Br(H -> WW*) between 3.2 and 2.8 pb for Higgs boson masses from 115 to 175 GeV.

  • 1071. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for excited muons in p(p)over-bar collisions at root s=1.96 TeV2006In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 73, no 11, p. 111102-Article in journal (Refereed)
    Abstract [en]

    We present the results of a search for the production of an excited state of the muon, mu(*), in proton antiproton collisions at root s =1.96 TeV. The data have been collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 380 pb(-1). We search for mu(*) in the process p (p) over bar ->mu(*)mu, with the mu(*) subsequently decaying to a muon plus photon. No excess above the standard model expectation is observed in data. Interpreting our data in the context of a model that describes mu(*) production by four-fermion contact interactions and mu(*) decay via electroweak processes, we set a 95% confidence level production cross section upper limit ranging from 0.057 to 0.112 pb, depending on the mass of the excited muon. Choosing the scale for contact interactions to be Lambda=1 TeV, excited muon masses below 618 GeV are excluded.

  • 1072. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for neutral Higgs bosons decaying to tau pairs in p(p)over-bar collisions at root s=1.96 TeV2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 12, p. 121802-Article in journal (Refereed)
    Abstract [en]

    A search for the production of neutral Higgs bosons Phi decaying into tau(+)tau(-) final states in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325 pb(-1), were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for Phi b((b) over bar)-> b (b) over barb((b) over bar) and are interpreted in the minimal supersymmetric standard model.

  • 1073. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for pair production of second generation scalar leptoquarks in p(p)over-bar collisions at root s-=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 636, no 3-4, p. 183-190Article in journal (Refereed)
    Abstract [en]

    We report on a search for the pair production of second generation scalar leptoquarks (LQ(2)) in p (p) over bar collisions at the center-of-mass energy, root s = 1.96 TeV, using data corresponding to an integrated luminosity of 294 19 pb(-1) recorded with the DO detector. No evidence for a leptoquark signal in the LQ(2)LQ(2) -> mu q mu q channel has been observed, and upper bounds on the product of cross section times branching fraction were set. This yields lower mass limits of m(LQ2) > 247 GeV/c(2) for beta = B(LQ(2) -> mu q) = 1 and m(LQ2) > 182 GeV/c(2) for beta = 1/2. Combining these limits with previous DO results, the lower limits on the mass of a second generation scalar leptoquark are m(LQ2) > 251 GeV/c(2) and m(LQ2) > 204 GeV/c(2) for beta = I and beta = 1/2, respectively.

  • 1074. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for particles decaying into a Z boson and a photon in p(p)over-bar collisions at root s=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 641, no 6, p. 415-422Article in journal (Refereed)
    Abstract [en]

    We present the results of a search for a new particle X produced in p (p) over bar collisions at root s- = 1.96 TeV and subsequently decaying to Z gamma. The search uses 0.3 fb(-1) of data collected with the DO detector at the Fermilab Tevatron Collider. We set limits on the production cross section times the branching fraction sigma(p (p) over bar -> X) x B(X -> Z gamma) that range from 0.4 to 3.5 pb at the 95% C.L. for X with invariant masses between 100 and 1000 GeV/c(2), over a wide range of X decay widths.

  • 1075. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for resonant second generation slepton production at the Fermilab Tevatron2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 11, p. 111801-Article in journal (Refereed)
    Abstract [en]

    We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon sneutrinos in the channels mu ->chi(0)(1)mu, mu ->chi(0)(2,3,4)mu, and nu(mu)->chi(+/-)(1,2)mu. We analyzed 0.38 fb(-1) of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function of slepton and gaugino masses. In the framework of minimal supergravity, we set limits on the coupling parameter lambda(')(211), extending significantly previous results obtained in Run I of the Tevatron and at the CERN LEP collider.

  • 1076. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for R-parity violating supersymmetry via the LL(E)over-bar couplings lambda(121), lambda(122) or lambda(133) in p(p)over-bar collisions at root s=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 638, no 5-6, p. 441-449Article in journal (Refereed)
    Abstract [en]

    A search for gaugino pair production with a trilepton signature in the framework of R-parity violating supersymmetry via the couplings; lambda(121), lambda(122), or lambda(133) is presented. The data, corresponding to an integrated luminosity of L approximate to 360 pb(-1), were collected from April 2002 to August 2004 with the D0 detector at the Fermilab Tevatron Collider, at a center-of-mass energy of root s = 1.96 TeV. This analysis considers final states with three charged leptons with the flavor combinations eel, mu mu l, and ee tau (l = e or mu). No evidence for supersymmetry is found and limits at the 95% confidence level are set on the gaugino pair production cross section and lower bounds on the masses of the lightest neutralino and chargino are derived in two supersymmetric models.

  • 1077. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for scalar leptoquarks in the acoplanar jet topology in p(p)over-bar collisions at root s=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 640, no 5-6, p. 230-237Article in journal (Refereed)
    Abstract [en]

    A search for leptoquarks has been performed in 310 pb-1 of data from p over(p, ̄) collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider. The topology analyzed consists of acoplanar jets with missing transverse energy. The data show good agreement with standard model expectations, and a lower mass limit of 136 GeV has been set at the 95% C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.

  • 1078. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for squarks and gluinos in events with jets and missing transverse energy in p(p)over-bar collisions at root s-=1.96 TeV2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 638, no 2-3, p. 119-127Article in journal (Refereed)
    Abstract [en]

    The results of a search for squarks and gluinos using data from p (p) over bar collisions recorded at a center-of-mass energy of 1.96 TeV by the DO detector at the Fermilab Tevatron Collider are reported. The topologies analyzed consist of acoplanar-jet and multijet events with large missing transverse energy. No evidence for the production of squarks or gluinos was found in a data sample of 310pb(-1). Lower limits of 325 and 241 GeV were derived at the 95% C.L. on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan beta=3, A(0) = 0, and mu < 0.

  • 1079. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for the Higgs boson in H -> WW(*) decays in p(p)over-bar collisions at root(s)=1.96 TeV2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, no 1, p. 011801-Article in journal (Refereed)
    Abstract [en]

    We present a search for the standard model Higgs boson in H -> WW(*) decays with e(+)e(-), e(+/-)mu(-/+), and mu(+)mu(-) final states in p (p) over bar collisions at a center-of-mass-energy of root s = 1.96 TeV. The data, collected from April 2002 to june 2004 with the D0 detector, correspond to an integrated luminosity of 300-325 pb(-1), depending on the final state. The number of events observed is consistent with the expectation from backgrounds. Limits from the combination of all three channels on the Higgs boson production cross section times branching ratio sigma x BR(H -> WW(*)) are presented.

  • 1080. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for the rare decay B-s(0)->phi mu(+)mu(-) with the D0 detector2006In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 74, no 3, p. 031107-Article in journal (Refereed)
    Abstract [en]

    We present a search for the flavor-changing neutral current decay B-s(0)->phi mu(+)mu(-) using about 0.45 fb(-1) of data collected in p (p) over bar collisions at root s=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to B-s(0)-> J/psi phi of B(B-s(0)->phi mu(+)mu(-))/B(B-s(0)-> J/psi phi)< 4.4x10(-3) at the 95% C.L. Using the central value of the world average branching fraction of B-s(0)-> J/psi phi, the limit corresponds to B(B-s(0)->phi mu(+)mu(-))< 4.1x10(-6) at the 95% C.L., the most stringent upper bound to date.

  • 1081. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for the standard model Higgs boson in the p(p)over-bar -> ZH -> v(v)over-barb(b)over-bar channel2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 97, no 16, p. 161803-Article in journal (Refereed)
    Abstract [en]

    We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260 pb(-1). We study events with missing transverse energy and two acoplanar b jets, which provide sensitivity to the ZH production cross section in the nu nu bb channel, and to WH production when the lepton from the W ->center dot nu decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on sigma(pp -> ZH/WH) x B(H -> bb) from 3.4/8.3 to 2.5/6.3 pb, for Higgs-boson masses between 105 and 135 GeV.

  • 1082. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Search for W ' boson production in the W ' -> t(b)over-bar decay channel2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 641, no 6, p. 423-431Article in journal (Refereed)
    Abstract [en]

    We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb(-1) of data collected with the DO detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events above the standard model expectation is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W' bosons times branching ratio to top quarks at the 95% confidence level for several different W, boson masses. We exclude masses between 200 and 610 GeV for a W' boson with standard-model-like couplings, between 200 and 630 GeV for a W, boson with right-handed couplings that is allowed to decay to both leptons and quarks, and between 200 and 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.

  • 1083. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    The upgraded DO detector2006In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 565, no 2, p. 463-537Article in journal (Refereed)
    Abstract [en]

    The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.

  • 1084. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, S.
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of dijet azimuthal decorrelations at central rapidities in p(p)over-bar collisions at root s=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 22, p. 221801-Article in journal (Refereed)
    Abstract [en]

    Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (p) over bar collisions at a center-of-mass energy root s=1.96 TeV. The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.

  • 1085. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, S.
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of the Lambda(0)(b) lifetime in the decay Lambda(0)(b)-> J/psi Lambda(0) with the D0 detector2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 10, p. 102001-Article in journal (Refereed)
    Abstract [en]

    We present measurements of the Lambda(b)(0) lifetime in the exclusive decay channel Lambda(b)(0)-> J/psi Lambda(0), with J/psi ->mu(+)mu(-) and Lambda(0)-> p pi(-), the B-0 lifetime in the decay B-0-> J/psi K-S(0) with J/psi ->mu(+)mu(-) and K-S(0)->pi(+)pi(-), and the ratio of these lifetimes. The analysis is based on approximately 250 pb(-1) of data recorded with the D0 detector in p (p) over bar collisions at root s = 1.96 TeV. The Lambda(b)(0) lifetime is determined to be tau(Lambda(b)(0))=1.22(-0.18)(+0.22)(stat)+/- 0.04(syst) ps, the B-0 lifetime tau(B-0)=1.40(-) (+0.11)(0.10)(stat)+/- 0.03(syst) ps, and the ratio tau(Lambda(b)(0))/tau(B-0)=0.87(-) (+0.17)(0.14)(stat)+/- 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Lambda(b)(0) lifetime based on a fully reconstructed decay channel.

  • 1086. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zverev, E. G.
    et al.,
    Study Z gamma events and limits on anomalous ZZ gamma and Z gamma gamma couplings in pp(-) collisions at root s=1.96 Tev2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 5, p. 051802-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the Z gamma production cross section and limits on anomalous ZZ gamma and Z gamma gamma couplings for form-factor scales of Lambda=750 and 1000 GeV. The measurement is based on 138 (152) candidates in the ee gamma (mu mu gamma) final state using 320(290) pb(-1) of p (p) over bar collisions at root s=1.96 TeV. The 95% C.L. limits on real and imaginary parts of individual anomalous couplings are vertical bar h(10,30)(Z)vertical bar < 0.23, vertical bar h(20,40)(Z)vertical bar < 0.020, vertical bar h(10,30)(gamma)vertical bar < 0.23, and vertical bar h(20,40)(gamma)vertical bar < 0.019 for Lambda=1000 GeV.

  • 1087. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of inclusive differential cross sections for Upsilon(1S) production in p(p)over-bar collisions at root s=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 23, p. 232001-Article in journal (Refereed)
    Abstract [en]

    We present measurements of the inclusive production cross sections of the Upsilon(1S) bottomonium state in p (p) over bar collisions at root s=1.96 TeV. Using the Upsilon(1S)->mu(+)mu(-) decay mode for a data sample of 159 +/- 10 pb(-1) collected by the D0 detector at the Fermilab Tevatron collider, we determine the differential cross sections as a function of the Upsilon(1S) transverse momentum for three ranges of the Upsilon(1S) rapidity: 0 <\y(Upsilon)\<= 0.6, 0.6 <\y(Upsilon)\<= 1.2, and 1.2 <\y(Upsilon)\<= 1.8.

  • 1088. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    Search for the flavour-changing neutral current B-s(0)->mu+mu- in p(p)over-bar collisions at root s=1.96 TeV with the D0 dectector2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 7, p. 071802-Article in journal (Refereed)
    Abstract [en]

    We present the results of a search for the flavor-changing neutral current decay B-s(0)-->mu(+)mu(-) using a data set with integrated luminosity of 240 pb(-1) of p (p) over bar collisions at roots=1.96 TeV collected with the D0 detector in run II of the Fermilab Tevatron collider. We find the upper limit on the branching fraction to be B(B-s(0)-->mu(+)mu(-))less than or equal to5.0x10(-7) at the 95% C.L. assuming no contributions from the decay B-d(0)-->mu(+)mu(-) in the signal region. This limit is the most stringent upper bound on the branching fraction B-s(0)-->mu(+)mu(-) to date.

  • 1089. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of sigma(p(p)over-bar -> Z)center dot Br(Z ->tau tau) at root s=1.96 TeV2005In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 71, no 7, p. 072004-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the cross section for Z production times the branching fraction to tau leptons, sigma.Br(Z ->tau(+)tau(-)), in p (p) over bar collisions at root s=1.96 TeV in the channel in which one tau decays into mu nu(mu)nu(tau), and the other into hadrons+nu(tau) or e nu(e)nu(tau). The data sample corresponds to an integrated luminosity of 226 pb(-1) collected with the D0 detector at the Fermilab Tevatron collider. The final sample contains 2008 candidate events with an estimated background of 55%. From this we obtain sigma.Br(Z ->tau(+)tau(-)) = 237 +/- 15(stat)+/- 18(sys)+/- 15(lum)pb, in agreement with the standard model prediction.

  • 1090. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of the ratio of B+ and B-0 meson lifetimes2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 18, p. 182001-Article in journal (Refereed)
    Abstract [en]

    The ratio of the B+ and B-0 meson lifetimes was measured using data collected in 2002-2004 by the D0 experiment in Run II of the Fermilab Tevatron Collider. These mesons were reconstructed in B&RARR;&mu;(+)&nu; D*-X decays, which are dominated by B-0 and B&RARR;&mu;(+)&nu;(D) over bar X-0 decays, which are dominated by B+. The ratio of lifetimes is measured to be &tau;(+)/&tau;(0)=1.080&PLUSMN; 0.016(stat)&PLUSMN; 0.014(syst).

  • 1091. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of the ratio of inclusive cross sections sigma(p(p)over-bar -> Z plus b jet)/sigma(p(p)over-bar -> Z plus jet) at root s=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 16, p. 161801-Article in journal (Refereed)
    Abstract [en]

    Using the data collected with the D0 detector at root s=1.96 TeV, for integrated luminosities of about 180 pb(-1), we have measured the ratio of inclusive cross sections for p(p) over bar -> Z+b jet to p(p) over bar -> Z+jet production. The inclusive Z+b-jet reaction is an important background to searches for the Higgs boson in associated ZH production at the Fermilab Tevatron collider. Our measurement is the first of its kind, and relies on the Z -> e(+)e(-) and Z ->mu(+)mu(-) modes. The combined measurement of the ratio yields 0.021 +/- 0.005 for hadronic jets with transverse momenta p(T)> 20 GeV/c and pseudorapidities vertical bar eta vertical bar < 2.5, consistent with next-to-leading-order predictions of the standard model.

  • 1092. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of the WW production cross section in p(p)over-bar collisions at root(s)over-bar=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 15, p. 151801-Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the W boson pair-production cross section in p(p) over bar collisions at a center-of-mass energy of root s=1.96 TeV. The data, collected with the Run II D0 detector at Fermilab, correspond to an integrated luminosity of 224-252 pb(-1) depending on the final state (ee, e mu, or mu mu). We observe 25 candidates with a background expectation of 8.1 +/- 0.6(stat)+/- 0.6(syst)+/- 0.5(lum) events. The probability for an upward fluctuation of the background to produce the observed signal is 2.3x10(-7), equivalent to 5.2 standard deviations. The measurement yields a cross section of 13.8(-3.8)(+4.3)(stat)(-0.9)(+1.2)(syst)+/- 0.9(lum) pb, in agreement with predictions from the standard model.

  • 1093. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Search for anomalous heavy-flavor quark production in association with W bosons2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 15, p. 152002-Article in journal (Refereed)
    Abstract [en]

    We search for anomalous production of heavy-flavor quark jets in association with W bosons at the Fermilab Tevatron p(p) over bar Collider in final states in which the heavy-flavor quark content is enhanced by requiring at least one tagged jet in an event. Jets are tagged using one algorithm based on semileptonic decays of b/c hadrons, and another on their lifetimes. We compare e+jets (164 pb(-1)) and mu+jets (145 pb(-1)) channels collected with the D0 detector at root s = 1.96 TeV to expectations from the standard model and set upper limits on anomalous production of such events.

  • 1094. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Search for first-generation scalar leptoquarks in p(p)over-bar collisions at root s=1.96 TeV2005In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 71, no 7, p. 071104-Article in journal (Refereed)
    Abstract [en]

    We report on a search for pair production of first-generation scalar leptoquarks (LQ) in p (p) over bar collisions at root s=1.96 TeV using an integrated luminosity of 252 pb(-1) collected at the Fermilab Tevatron collider by the D0 detector. We observe no evidence for LQ production in the topologies arising from LQ(LQ) over bar -> eqeq and LQ(LQ) over bar -> eq nu q, and derive 95% C.L. lower limits on the LQ mass as a function of beta, where beta is the branching fraction for LQ -> eq. The limits are 241 and 218 GeV/c(2) for beta=1 and 0.5, respectively. These results are combined with those obtained by D0 at root s=1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c(2).

  • 1095. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Lager, Sara
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Search for Wbb(-) and WH production in pp(-) collisions at root s=1.96 TeV2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 9, p. 091802-Article in journal (Refereed)
    Abstract [en]

    We present a search for Wb (b) over bar production in p (p) over bar collisions at root s=1.96 TeV in events containing one electron, an imbalance in transverse momentum, and two b-tagged jets. Using 174 pb(-1) of integrated luminosity accumulated by the D0 experiment at the Fermilab Tevatron collider, and the standard-model description of such events, we set a 95% C.L. upper limit on Wb (b) over bar production of 6.6 pb for b quarks with transverse momenta p(T)(b)> 20 GeV and b (b) over bar separation in pseudorapidity-azimuth space Delta R-bb> 0.75. Restricting the search to optimized b (b) over bar mass intervals provides upper limits on WH production of 9.0-12.2 pb for Higgs-boson masses of 105-135 GeV.

  • 1096. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Measurement of the B-s(0) lifetime in the exclusive decay channel B-s(0)-> J/psi phi2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 94, no 4, p. 042001-Article in journal (Refereed)
    Abstract [en]

    Using the exclusive decay B-s(0)-->J/psi(mu(+)mu(-))phi(K+K-), we report the most precise single measurement of the B-s(0) lifetime. The data sample corresponds to an integrated luminosity of approximately 220 pb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2004. We reconstruct 337 signal candidates, from which we extract the B-s(0) lifetime, tau(B-s(0))=1.444(-0.090)(+0.098)(stat)+/-0.020(sys) ps. We also report a measurement for the lifetime of the B-0 meson using the exclusive decay B-0-->J/psi(mu(+)mu(-))K-*0(892)(K(+)pi(-)). We reconstruct 1370 signal candidates, obtaining tau(B-0)=1.473(-0.050)(+0.052)(stat)+/-0.023(sys) ps, and the ratio of lifetimes, tau(B-s(0))/tau(B-0)=0.980(-0.071)(+0.076)(stat)+/-0.003(sys).

  • 1097. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Strandberg, Jonas
    Zylberstejn, A.
    et al.,
    Observation and properties of the X(3872) decaying to J/psi pi(+)pi(-) in p(p)over-bar collisions at root s=1.96 TeV2004In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 93, no 16, p. 162002-Article in journal (Refereed)
    Abstract [en]

    We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.

  • 1098.
    Abazov, V. M.
    et al.
    Joint Inst Nucl Res, Dubna, Russia..
    Åsman, Bengt
    KTH.
    Clement, Christophe
    KTH.
    Gollub, Nils
    KTH.
    Lager, S.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Soeldner-Rembold, S.
    Univ Manchester, Manchester, Lancs, England..
    Strandberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Search for particles decaying into a Z boson and a photon in collisions p (p)over-bar at root s = 1.96 TeV (vol 641, pg 415, 2006)2009In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 670, no 4-5, p. 455-458Article in journal (Refereed)
  • 1099.
    Abazov, V. M.
    et al.
    Joint Inst Nucl Res, Dubna, Russia..
    Åsman, Björn
    KTH.
    Bandurin, D. V.
    Kansas State Univ, Manhattan, KS 66506 USA..
    Belanger-Champagne, C.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Clement, C.
    Lund Univ, Lund, Sweden.;Royal Inst Technol, Stockholm, Sweden.;Stockholm Univ, S-10691 Stockholm, Sweden.;Uppsala Univ, Uppsala, Sweden..
    Gollub, Nils
    KTH.
    Hansson, P.
    KTH.
    Strandberg, S
    KTH.
    Measurement of the isolated photon cross section in p(p)over-bar collisions at root s = 1.96 TeV (vol 639, pg 151, 2006)2008In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 658, no 5, p. 285-289Article in journal (Refereed)
  • 1100. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    Zverev, E.G.
    Study of direct CP violation in B(+/-)-> J/psi K(+/-)(pi(+/-)) decays2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 21, p. 211802-Article in journal (Refereed)
    Abstract [en]

    We present a search for direct CP violation in B(+/-) -> J/psi K(+/-) (pi(+/-)) decays. The event sample is selected from 2: 8 fb(-1) of p (p) over bar collisions recorded by D0 experiment in run II of the Fermilab Tevatron Collider. The charge asymmetry A(CP)(B(+) -> J/psi K(+)) = +0: 0075 +/- 0: 0061(stat) +/- 0: 0030 (syst) is obtained using a sample of approximately 40 000 B(+/-) -> J/psi K(+/-) decays. The achieved precision is of the same level as the expected deviation predicted by some extensions of the standard model. We also measured the charge asymmetry A(CP) (B(+) -> J/psi pi(+)) = - 0: 09 +/- 0: 08(stat) +/- 0: 03(syst).

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