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  • 151. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for stopped gluinos from p(p)over-bar collisions at root s=1.96 TeV2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 13, p. 131801-1-131801-8Article in journal (Refereed)
    Abstract [en]

    Long-lived, heavy particles are predicted in a number of models beyond the standard model of particle physics. We present the first direct search for such particles' decays, occurring up to 100 h after their production and not synchronized with an accelerator bunch crossing. We apply the analysis to the gluino (g), predicted in split supersymmetry, which after hadronization can become charged and lose enough momentum through ionization to come to rest in dense particle detectors. Approximately 410 pb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector during Run II of the Fermilab Tevatron collider are analyzed in search of such "stopped gluinos" decaying into a gluon and a neutralino ((chi) over tilde (0)(1)). Limits are placed on the (gluino cross section) x (probability to stop) x [BR((g) over tilde -> g (chi) over tilde (0)(1))] as a function of the gluino and (chi) over tilde (0)(1) masses, for gluino lifetimes from 30 mu s-100 h.

  • 152. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for techniparticles in e plus jets events at D02007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 22, p. 221801-1-221801-7Article in journal (Refereed)
    Abstract [en]

    We search for the technicolor process p(p) over bar ->rho(T)/omega(T)-> W pi(T) in events containing one electron and two jets, in data corresponding to an integrated luminosity of 390 pb(-1), recorded by the D0 experiment at the Fermilab Tevatron. Technicolor predicts that technipions pi(T) decay dominantly into b(b) over bar, b(c) over bar, or (b) over barc, depending on their charge. In these events b and c quarks are identified by their secondary decay vertices within jets. Two analysis methods based on topological variables are presented. Since no excess above the standard model prediction was found, the result is presented as an exclusion in the pi(T) vs rho(T) mass plane for a given set of model parameters.

  • 153. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for third-generation scalar leptoquarks in p(p)over-bar collisions at root s=1.96 TeV2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 6, p. 061801-1-061801-7Article in journal (Refereed)
    Abstract [en]

    We report on a search for charge-1/3 third-generation leptoquarks (LQ) produced in p (p) over bar collisions at root s =1.96 TeV using the D0 detector at Fermilab. Third-generation leptoquarks are assumed to be produced in pairs and to decay to a tau neutrino and a b quark with branching fraction B. We place upper limits on sigma(p (p) over bar -> LQ (LQ) over bar )B-2 as a function of the leptoquark mass M-LQ. Assuming B=1, we exclude at the 95% confidence level third-generation scalar leptoquarks with M-LQ < 229 GeV.

  • 154. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Study of the decay B-s(0)->(DsDs(*))-D-(*)2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 99, no 24, p. 241801-1-241801-7Article in journal (Refereed)
    Abstract [en]

    We report a study of the decay B-s(0)->(DsDs(*))-D-(*) using a data sample corresponding to 1.3 fb(-1) of integrated luminosity collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. One D-s((*)) meson was partially reconstructed in the decay D-s ->phi mu nu, and the other D-s((*)) meson was identified using the decay D-s ->phi pi where no attempt was made to distinguish D-s and D-s(*) states. For the branching fraction Br(B-s(0)->(DsDs(*))-D-(*)) we obtain a 90% C.L. range [0.002,0.080] and central value 0.039(-0.017)(+0.019)(stat)(-0.015)(+0.016)(syst). This was subsequently used to make the most precise estimate of the width difference Delta Gamma(CP)(s) in the B-s(0)-(B)over bar(s)(0) system: Delta Gamma(CP)(s)/Gamma(s)=0.079(-0.035)(+0.038)(stat)(-0.030)(+0.031)(syst).

  • 155. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the forward-backward charge asymmetry in top-quark pair production2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 14, p. 142002-1-142002-7Article in journal (Refereed)
    Abstract [en]

    We present the first measurement of the integrated forward-backward charge asymmetry in top-quark-top-antiquark pair (t (t) over bar) production in proton-antiproton (p (p) over bar) collisions in the lepton+jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming t (t) over bar +X production and decay, a sample of 0.9 fb(-1) of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on t (t) over bar +X production via a Z' resonance.

  • 156. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    University of Chicago.
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the Semileptonic Branching Ratio of Bs(0) to an Orbitally Excited D-s** State: Br(Bs(0) -> Ds1(-)(2536)mu(+)nu X)2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 5, p. 051801-1-051801-7Article in journal (Refereed)
    Abstract [en]

    In a data sample of approximately 1.3 fb(-1) collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D-s1(+/-)(2536) has been observed with a measured mass of 2535.7 +/- 0.6(stat) +/- 0.5(syst) MeV/c(2) via the decay mode B-s(0) -> D-s1(-)(2536)mu(+)nu X-mu. A first measurement is made of the branching ratio product Br((b) over bar -> D-s1(-)(2536)mu(+)nu X-mu) x Br(D-s1(-) -> D*K--(S)0). Assuming that D-s1(-)(2536) production in semileptonic decay is entirely from B-s(0), an extraction of the semileptonic branching ratio Br(B-s(0) -> D-s1(-)(2536)mu(+)nu X-mu) is made.

  • 157. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the shape of the boson-transverse momentum distribution in p(p)over-bar -> Z/gamma*-> e(+)e(-)+X events produced at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 10, p. 102002-1-102002-7Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the shape of the Z/gamma* boson transverse momentum (q(T)) distribution in p (p) over bar -> Z/gamma(*)-> e(+)e(-)+X events at a center-of-mass energy of 1.96 TeV using 0.98 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron collider. The data are found to be consistent with the resummation prediction at low q(T), but above the perturbative QCD calculation in the region of q(T)> 30 GeV/c. Using events with q(T)< 30 GeV/c, we extract the value of g(2), one of the nonperturbative parameters for the resummation calculation. Data at large boson rapidity y are compared with the prediction of resummation and with alternative models that employ a resummed form factor with modifications in the small Bjorken x region of the proton wave function.

  • 158. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    University of Chicago.
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Model-independent measurement of the W-boson helicity in top-quark decays at D02008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 6, p. 062004-1-062004-7Article in journal (Refereed)
    Abstract [en]

    We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb(-1) sample of candidate t (t) over bar events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron p (p) over bar Collider. We reconstruct the angle theta(*) between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos theta(*) distribution finds that the fraction of longitudinal W bosons f(0)=0.425 +/- 0.166(stat)+/- 0.102(syst) and the fraction of right-handed W bosons f(+)=0.119 +/- 0.090(stat)+/- 0.053(syst), which is consistent at the 30% C.L. with the standard model.

  • 159. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Observation and properties of the orbitally excited B-s2* meson2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 8, p. 082002-1-082002-7Article in journal (Refereed)
    Abstract [en]

    We report the direct observation of the excited L=1 state B-s2* in fully reconstructed decays to B+K-. The mass of the B-s2* meson is measured to be 5839.6 +/- 1.1(stat)+/- 0.7(syst) MeV/c(2), and its production rate relative to the B+ meson is measured to be [1.15 +/- 0.23(stat)+/- 0.13(syst)]%.

  • 160. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for flavor-changing-neutral-current D meson decays2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 10, p. 101801-1-101801-7Article in journal (Refereed)
    Abstract [en]

    We study the flavor-changing-neutral-current process c -> u mu(+)mu(-) using 1.3 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D-s(+) and D+->phi pi(+)->mu(+)mu(-)pi(+) final states with significance greater than 4 standard deviations above background for the D+ state. We search for the continuum neutral-current decay of D+->pi(+)mu(+)mu(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D+->pi(+)mu(+)mu(-))< 3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c -> u mu(+)mu(-) transition.

  • 161. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for Randall-Sundrum gravitons with 1 fb(-1) of data from p(p)over-bar collisions at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 9, p. 091802-1-091802-7Article in journal (Refereed)
    Abstract [en]

    We search for decays of Kaluza-Klein excitations of the graviton in the Randall-Sundrum model of extra dimensions to e(+)e(-) and gamma gamma in 1 fb(-1) of p (p) over bar collisions at root s=1.96 TeV collected by the D0 detector at the Fermilab Tevatron. We set 95% confidence level upper limits on the production cross section times branching fraction, which translate into lower limits on the mass of the lightest excitation between 300 and 900 GeV for values of the coupling k/(M) over bar (P1) between 0.01 and 0.1.

  • 162. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    University of Chicago.
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for scalar neutrino superpartners in e+mu final states in p(p)over-bar collisions at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 24, p. 241803-Article in journal (Refereed)
    Abstract [en]

    We report a search for R-parity-violating production and decay of sneutrino particles in the e mu final state with 1.04 +/- 0.06 fb(-1) of data collected with the D-0 detector at the Fermilab Tevatron Collider in 2002-2006. Good agreement between the data and the standard model prediction is observed. With no evidence for new physics, we set limits on the R-parity-violating couplings lambda'(311) and lambda(312) as a function of the sneutrino mass.

  • 163. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for W ' bosons decaying to an electron and a neutrino with the D0 detector2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 3, p. 031804-1-031804-7Article in journal (Refereed)
    Abstract [en]

    This Letter describes the search for a new heavy charged gauge boson W-' decaying into an electron and a neutrino. The data were collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s=1.96 TeV, and correspond to an integrated luminosity of about 1 fb(-1). Lacking any significant excess in the data in comparison with known processes, an upper limit is set on sigma(')(W)xB(W-'-> e nu), and a W-' boson with mass below 1.00 TeV can be excluded at the 95% C.L., assuming standard-model-like couplings to fermions. This result significantly improves upon previous limits and is the most stringent to date.

  • 164. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Search for ZZ and z gamma* production in p(p)over-bar collisions at root s=1.96 TeV and limits on anomalous ZZZ and ZZ gamma* couplings2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 13, p. 131801-1-131801-7Article in journal (Refereed)
    Abstract [en]

    We present a study of mu mu mu mu, eeee, and mu mu ee events using 1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. Requiring the lepton pair masses to be greater than 30 GeV, we observe one event, consistent with the expected background of 0.13 +/- 0.03 events and with the predicted standard model ZZ and Z gamma(*) production of 1.71 +/- 0.15 events. We set an upper limit on the ZZ and Z gamma(*) cross section of 4.4 pb at the 95% C.L. We also derive limits on anomalous neutral trilinear ZZZ and ZZ gamma(*) gauge couplings. The one-parameter 95% C.L. coupling limits with a form-factor scale Lambda = 1.2 TeV are -0.28 < f(40)(Z)< 0.28, -0.31 < f(50)(Z)< 0.29, -0.26 < f(40)(gamma)< 0.26, and -0.30 < f(50)(gamma)< 0.28.

  • 165. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Simultaneous measurement of the ratio R = B(t -> Wb)/B(t -> Wq) and the top-quark pair production cross section with the D0 detector at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 19, p. 192003-1-192003-7Article in journal (Refereed)
    Abstract [en]

    We present the first simultaneous measurement of the ratio of branching fractions, R = B(t --> Wb)/B(t --> Wq), with q being a d, s, or b quark, and the top-quark pair production cross section sigma(t (t) over bar) in the lepton plus jets channel using 0.9 fb(-1) of p (p) over bar collision data at root s = 1.96 TeV collected with the D0 detector. We extract R and sigma(t (t) over bar) by analyzing samples of events with 0, 1, and >= 2 identified b jets. We measure R = 0.97(-0.08)(+0.09) (stat + syst) and sigma(t (t) over bar) = 8.18(-0.84)(+0.90) (stat + syst) +/- 0.50(lumi) pb, in agreement with the standard model prediction.

  • 166. Abazov, V. M.
    et al.
    Åsman, Barbro
    Bélanger-Champagne, Camille
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Measurement of the Forward-Backward Charge Asymmetry and Extraction of sin(2)theta(eff)(W) in pp -> Z/gamma(*)+X -> e(+)e(-)+X Events Produced at s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 19, p. 191801-1-191801-7Article in journal (Refereed)
    Abstract [en]

    We present a measurement of the forward-backward charge asymmetry (A(FB)) in pp -> Z/gamma(*)+X -> e(+)e(-)+X events at a center-of-mass energy of 1.96 TeV using 1.1 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron collider. A(FB) is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the A(FB) measurement to extract the effective weak mixing angle sin(2)theta(eff)(W)=0.2326 +/- 0.0018(stat)+/- 0.0006(syst).

  • 167. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Hansson, Per
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Strandberg, Jonas
    Strandberg, Sara
    Zverev, E. G.
    et al.,
    Experimental discrimination between charge 2e/3 top quark and charge 4e/3 exotic quark production scenarios2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98, no 4, p. 041801-1-041801-7Article in journal (Refereed)
    Abstract [en]

    We present the first experimental discrimination between the 2e/3 and 4e/3 top quark electric charge scenarios, using top quark pairs (t (t) over bar) produced in p (p) over bar collisions at root s =1.96 TeV by the Fermilab Tevatron Collider. We use 370 pb(-1) of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and (b) over bar -quark jets by using the charge and momenta of tracks within the jet cones. The data are consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs Q (Q) over bar with |q|=4e/3. We place an upper limit on the fraction of Q (Q) over bar pairs rho < 0.80 at the 90% C.L.

  • 168. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    Measurement of semileptonic branching fractions of B mesons to narrow D-** states2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 17, p. 171803-Article in journal (Refereed)
    Abstract [en]

    Using the data accumulated in 2002-2004 with the D0 detector in proton-antiproton collisions at the Fermilab Tevatron collider with a center-of-mass energy of 1.96 TeV, the branching fractions of the decays B ->(D) over bar (0)(1)(2420)mu(+)nu(mu)X and B ->(D) over bar (*0)(2)(2460)mu(+)nu(mu)X and their ratio have been measured: B (b) over bar -> B)xB(B -> (D) over bar (0)(1)mu(+)nu(mu)X)xB((D) over bar (0)(1)-> D(*-)pi(+))=[0.087 +/- 0.007(stat)+/- 0.014(syst)]%; B((b) over bar -> B)xB(B ->(D) over bar (*0)(2)mu(+)nu(mu)X)xB((D) over bar (*0)(2)-> D(*-)pi(+))=[0.035 +/- 0.007(stat)+/- 0.008(syst)]% and [B(B ->(D) over bar (*0)(2)mu(+)nu(mu)X)xB((D) over bar (*0)(2)-> D(*-)pi(+))]/[B(B ->(D) over bar (0)(1)mu(+)nu(mu)X)xB((D) over bar (0)(1)-> D(*-)pi(+))]=0.39 +/- 0.09(stat)+/- 0.12(syst), where the charge conjugated states are always implied.

  • 169. Abazov, V. M.
    et al.
    Åsman, Barbro
    Clément, Christophe
    Gollub, Nils
    Lager, Sara
    Strandberg, Jonas
    Zverev, E.G.
    et al.,
    Measurement of the lifetime difference in the B-s(0) system2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 17, p. 171801-Article in journal (Refereed)
    Abstract [en]

    We present a study of the decay B-s(0)-> J/psi phi. We obtain the CP-odd fraction in the final state at time zero R-perpendicular to = 0.16 +/- 0.10 (stat) +/- 0.02(syst), the average lifetime of the (B-s(0), (B) over bar (0)(s)) system, (tau) over bar (B-s(0)) = 1.39(-0.16)(+0.13)(stat)(-0.02)(+0.01)(syst) ps, and the relative width difference between the heavy and light mass eigen-states, Delta Gamma/(Gamma) over bar = (Gamma(L) - Gamma(H))/(Gamma) over bar = 0.24(-0.38)(+0.28)(stat)(-0.04)(+0.03)(syst). With the additional constraint from the world average of the B-s(0) lifetime measurements using semileptonic decays, we find (tau) over bar (B-s(0)) = 1.39 +/- 0.06 ps and Delta Gamma/(Gamma) over bar = 0.25(-0.15)(+0.14). For the ratio of the B-s(0) and B-0 lifetimes we obtain (tau) over bar (B-s(0))/tau(B-s(0)) = 0.91 +/- 0.09(stat) +/- 0.003(syst).

  • 170. 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.

  • 171. 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.

  • 172. 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.

  • 173. 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.

  • 174. 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.

  • 175. 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.

  • 176. 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.

  • 177. 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)%.

  • 178. 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.

  • 179. 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.

  • 180. 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.

  • 181. 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.

  • 182. 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.

  • 183. 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.

  • 184. 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.

  • 185. 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.

  • 186. 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.

  • 187. 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.

  • 188. 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.

  • 189. 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).

  • 190. 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.

  • 191. 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.

  • 192. 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.

  • 193. 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.

  • 194. 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).

  • 195. 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.

  • 196. 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).

  • 197. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    First study of the radiation-amplitude zero in W gamma production and limits on anomalous WW gamma couplings at root s=1.96 TeV2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 24, p. 241805-Article in journal (Refereed)
    Abstract [en]

    We present results from a study of p (p) over bar -> W gamma+X events utilizing data corresponding to 0.7 fb(-1) of integrated luminosity at root s = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We set limits on anomalous WW gamma couplings at the 95% C.L. The one-dimensional 95% C.L. limits are 0.49 <kappa(gamma)< 1.51 and -0.12 <lambda(gamma)< 0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the W gamma system.

  • 198. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Measurement of the Lifetime of the B(c)(+/-) Meson in the Semileptonic Decay Channel2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 9, p. 092001-Article in journal (Refereed)
    Abstract [en]

    Using approximately 1.3 fb(-1) of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the B(c)(+/-) meson in the B(c)(+/-)-> J/psi mu(+/-)+X final state. A simultaneous unbinned likelihood fit to the J/psi+mu invariant mass and lifetime distributions yields a signal of 881 +/- 80(stat) candidates and a lifetime measurement of tau(B(c)(+/-))=0.448(-0.036)(+0.038)(stat)+/- 0.032(syst) ps.

  • 199. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Associated W and Higgs Boson Production in p(p)over-bar Collisions at root s=1.96 TeV2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 5, p. 051803-Article in journal (Refereed)
    Abstract [en]

    We present results of a search for WH -> l nu b (b) over bar production in p (p) over bar collisions based on the analysis of 1.05 fb(-1) of data collected by the D0 experiment at the Fermilab Tevatron, using a neural network for separating the signal from backgrounds. No signal-like excess is observed, and we set 95% C. L. upper limits on the WH production cross section multiplied by the branching ratio for H -> b (b) over bar for Higgs boson masses between 100 and 150 GeV. For a mass of 115 GeV, we obtain an observed (expected) limit of 1.5 (1.4) pb, a factor of 11.4 (10.7) times larger than the standard model prediction.

  • 200. Abazov, V.M.
    et al.
    Gollub, Nils
    Strandberg, Jonas
    University of Chicago.
    Zverev, E.G.
    et al.,
    Search for Neutral Higgs Bosons at High tan beta in the b(h/H/A) -> b tau(+)tau(-) Channel2009In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 102, no 5, p. 051804-Article in journal (Refereed)
    Abstract [en]

    The first search in p (p) over bar collisions at root s = 1.96 TeV for the production of neutral Higgs bosons in association with bottom quarks and decaying in two tau leptons is presented. The cross section for this process is enhanced in many extensions of the standard model, such as its minimal supersymmetric extension (MSSM) at large tan beta. The data, corresponding to an integrated luminosity of 328 pb(-1), were collected with the D0 detector at the Fermilab Tevatron Collider. An upper limit is set on the production cross section of neutral Higgs bosons in the mass range of 90 to 150 GeV, and this limit is used to exclude part of the MSSM parameter space.

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