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51.
  • Abazov, V. M., et al. (författare)
  • Search for anomalous Wtb couplings in single top quark production in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 708:1-2, s. 21-26
  • Tidskriftsartikel (refereegranskat)abstract
    • We present new direct constraints on a general Wtb interaction using data corresponding to an integrated luminosity of 5.4 fb(-1) collected by the DO detector at the Tevatron p (p) over bar collider. The standard model provides a purely left-handed vector coupling at the Wtb vertex, while the most general, lowest dimension Lagrangian allows right-handed vector and left- or right-handed tensor couplings as well. We obtain precise limits on these anomalous couplings by comparing the data to the expectations from different assumptions on the Wtb coupling.
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52.
  • Abazov, V. M., et al. (författare)
  • Search for associated Higgs boson production using like charge dilepton events in p(p)over-bar collisions at root s=1.96 TeV
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84, s. 092002-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for associated Higgs boson production in the process p (p) over bar -> W/ZH -> l(+/-)l'(+/-) + X in ee, e mu, and mu mu final states. The search is based on data collected by the D0 experiment at the Fermilab Tevatron Collider at root s = 1.96 TeV corresponding to 5.3 fb(-1) of integrated luminosity. We require two isolated leptons (electrons or muons) with the same electric charge and additional kinematic requirements. No significant excess above background is observed, and we set 95% C. L. observed (expected) upper limits on ratio of the production cross section to the standard model prediction of 6.4 (7.3) for a Higgs boson mass of 165 GeV and 13.5 (19.8) for a mass of 115 GeV.
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53.
  • Abazov, V. M., et al. (författare)
  • Search for Charged Massive Long-Lived Particles
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:12, s. 121802-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on a search for charged massive long-lived particles (CMLLPs), based on 5.2 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar collider. We search for events in which one or more particles are reconstructed as muons but have speed and ionization energy loss (dE/dx) inconsistent with muons produced in beam collisions. CMLLPs are predicted in several theories of physics beyond the standard model. We exclude pair-produced long-lived gauginolike charginos below 267 GeV and Higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar top quarks with mass below 285 GeV.
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54.
  • Abazov, V. M., et al. (författare)
  • Search for Doubly Charged Higgs Boson Pair Production in p(p)over-bar Collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:2, s. 021801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for pair production of doubly charged Higgs bosons in the processes q (q) over bar -> H(++)H(--) decaying through H(+/-+/-) ->tau(+/-)tau(+/-), mu(+/-)tau(+/-), mu(+/-)mu(+/-). The search is performed in p (p) over bar collisions at a center-of-mass energy of root s = 1:96 TeV using an integrated luminosity of up to 7:0 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. The results are used to set 95% C. L. limits on the pair production cross section of doubly charged Higgs bosons and on their mass for different H(+/-+/-) branching fractions. Models predicting different H(+/-+/-) decays are investigated. Assuming B(H(+/-+/-) -> tau(+/-)tau(+/-)) = 1 yields an observed (expected) lower limit on the mass of a left- handed H(L)(+/-+/-) boson of 128 (116) GeV and assuming B(H(+/-+/-) -> mu(+/-)tau(+/-)) = 1 the corresponding limits are 144 (149) GeV. In a model with B(H(+/-+/-) -> tau +/-tau(+/-) B(H(+/-+/-) -> mu(+/-)tau(+/-)) = B(H(+/-+/-) -> mu(+/-)mu(+/-) ) 1/3, we obtain M(H(L)(+/-+/-)) > 130 (138) GeV.
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55.
  • Abazov, V. M., et al. (författare)
  • Search for first generation leptoquark pair production in the electron plus missing energy plus jets final state
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:7, s. 071104-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the pair production of first generation scalar leptoquarks (LQ) in data corresponding to an integrated luminosity of 5.4 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider in p (p) over bar collisions at root s = 1.96 TeV. In the channel LQLQ -> eqv(e)q', where q, q' are u or d quarks, no significant excess of data over background is observed, and we set a 95% C. L. lower limit of 326 GeV on the LQ mass, assuming equal probabilities of LQ decays to eq and v(e)q'.
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56.
  • Abazov, V. M., et al. (författare)
  • Search for Higgs bosons of the minimal supersymmetric standard model in p(p)over-bar collisions at root s=1.96 TeV D0 Collaboration
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 710:4-5, s. 569-577
  • Tidskriftsartikel (refereegranskat)abstract
    • We report results from searches for neutral Higgs bosons produced in p (p) over bar collisions recorded by the D0 experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral Higgs boson in the tau tau final state and in association with a b quark in the b tau tau and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300 GeV. We exclude tan beta > 20-30 for Higgs boson masses below 180 GeV. These are the most stringent constraints on MSSM Higgs boson production in p (p) over bar collisions.
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57.
  • Abazov, V. M., et al. (författare)
  • Search for Neutral Minimal Supersymmetric Standard Model Higgs Bosons Decaying to Tau Pairs Produced in Association with b Quarks in p(p)over-bar Collisions at root s=1.96 TeV
  • 2011
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:12, s. 121801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an integrated luminosity of 7.3 fb(-1). This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tan beta. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limits on the cross section times branching ratio in the Higgs boson mass range from 90 to 320 GeV/c(2). We interpret our result in the MSSM parameter space, excluding tan beta values down to 25 for Higgs boson masses below 170 GeV/c(2).
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58.
  • Abazov, V. M., et al. (författare)
  • Search for pair production of the scalar top quark in muon plus tau final states D0 Collaboration
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 710:4-5, s. 578-586
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the pair production of scalar top quarks ((t) over tilde (1)), the lightest supersymmetric partners of the top quarks, in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of 7.3 fb(-1) collected with the D0 experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a b quark, a charged lepton, and a scalar neutrino ((nu) over bar). We investigate final states arising from (t) over tilde (1)(t) over tilde (1) -> b (b) over bar mu tau(nu nu) over tilde and (t) over tilde (1)(t) over tilde (1) -> b (b) over bar tau tau(nu nu) over tilde. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the (m((t) over tilde1), m((nu) over tilde)) plane.
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59.
  • Abazov, V. M., et al. (författare)
  • Search for the Standard Model Higgs Boson in Associated WH Production in 9.7 fb(-1) of p(p)over-bar Collisions with the D0 Detector
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 109:12, s. 121804-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the standard model Higgs boson in final states with a charged lepton (electron or muon), missing transverse energy, and two or three jets, at least one of which is identified as a b-quark jet. The search is primarily sensitive to WH -> lvb (b) over bar production and uses data corresponding to 9.7 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. We observe agreement between the data and the expected background. For a Higgs boson mass of 125 GeV, we set a 95% C.L. upper limit on the production of a standard model Higgs boson of 5.2 x sigma(SM), where sigma(SM) is the standard model Higgs boson production cross section, while the expected limit is 4: 7 x sigma(SM).
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60.
  • Abazov, V. M., et al. (författare)
  • Search for the Standard Model Higgs Boson in ZH -> l(+) l(-) b(b)over-bar Production with the D0 Detector in 9.7 fb(-1)of p(p)over-bar Collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 109:12, s. 121803-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the standard model (SM) Higgs boson produced in association with a Z boson in 9.7 fb(-1) of p (p) over bar collisions collected with the D0 detector at the Fermilab Tevatron Collider at root s = 1.96 TeV. Selected events contain one reconstructed Z -> e(+) e(-) or Z -> mu(+) mu(-)candidate and at least two jets, including at least one jet identified as likely to contain a b quark. To validate the search procedure, we also measure the cross section for ZZ production in the same final state. It is found to be consistent with its SM prediction. We set upper limits on the ZH production cross section times branching ratio for H -> b (b) over bar at the 95% C.L. for Higgs boson masses 90 <= M-H <= 150 GeV. The observed (expected) limit for M-H = 125 GeV is 7.1 (5.1) times the SM cross section.
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61.
  • Abazov, V. M., et al. (författare)
  • Search for Universal Extra Dimensions in p(p)over-bar Collisions
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:13, s. 131802-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by the D0 detector at a p (p) over bar center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R-1 > 260 GeV in a minimal UED model.
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62.
  • Abazov, V. M., et al. (författare)
  • Search for WH associated production in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:3, s. 032005-
  • Tidskriftsartikel (refereegranskat)abstract
    • This report describes a search for associated production of W and Higgs bosons based on data corresponding to an integrated luminosity of L approximate to 5.3 fb(-1) collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider. Events containing a W -> l nu candidate (with l corresponding to e or mu) are selected in association with two or three reconstructed jets. One or two of the jets are required to be consistent with having evolved from a b quark. A multivariate discriminant technique is used to improve the separation of signal and backgrounds. Expected and observed upper limits are obtained for the product of the WH production cross section and branching ratios and reported in terms of ratios relative to the prediction of the standard model as a function of the mass of the Higgs boson (M-H). The observed and expected 95% C. L. upper limits obtained for an assumed M-H = 115 GeV are, respectively, factors of 4.5 and 4.8 larger than the value predicted by the standard model.
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63.
  • Abazov, V. M., et al. (författare)
  • Study of the decay Bs0→J/ψf2′(1525) in μ +μ -K +K - final states
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:9, s. 092011-
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the decay Bs0→J/ψK +K - for invariant masses of the K +K - pair in the range 1.35<M(K +K -)<2GeV. The data sample corresponds to an integrated luminosity of 10.4fb -1 of pp̄ collisions at √s=1.96TeV accumulated with the D0 detector at the Fermilab Tevatron collider. From the study of the invariant mass and spin of the K +K - system, we find evidence for the two-body decay Bs0→J/ψf2′(1525) and measure the relative branching fraction of the decays Bs0→J/ψf2′(1525) and Bs0→J/ψ to be R f2′/=0.19±0.05(stat)±0.04(syst).
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64.
  • Abazov, V. M., et al. (författare)
  • Z(gamma) production and limits on anomalous ZZ(gamma) and Z(gamma gamma) couplings in p(p)over-bar collisions at root s 1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 85:5, s. 052001-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of p (p) over bar -> Z gamma -> l(+)l(-)gamma (l = e, mu) production with a data sample corresponding to an integrated luminosity of 6.2 fb(-1) collected by the D0 detector at the Fermilab Tevatron p (p) over bar Collider. The results of the electron and muon channels are combined, and we measure the total production cross section and the differential cross section d(sigma)/dp(T)(gamma), where p(T)(gamma) is the momentum of the photon in the plane transverse to the beam line. The results obtained are consistent with the standard model predictions from next-to-leading order calculations. We use the transverse momentum spectrum of the photon to place limits on anomalous ZZ gamma and Z gamma gamma couplings.
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65.
  • Abazov, V. M., et al. (författare)
  • Measurement of leptonic asymmetries and top-quark polarization in t(t)over-bar production
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:1, s. 011103-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of lepton (l) angular distributions in top-quark (t) pair production and t (t) over bar -> W(+)bW-(b) over bar -> l(+) vbl-(v) over bar(b) over bar decays produced in p (p) over bar collisions at a center-of-mass energy of root s = 1.96 TeV, where l is an electron or muon. Using data corresponding to an integrated luminosity of 5.4 fb(-1), collected with the D0 detector at the Fermilab Tevatron Collider, we measure for the first time the leptonic forward-backward asymmetry in dilepton final states and obtain A(FB)(l) = (5.8 +/- 5.1(stat) +/- 1.3(syst))%, corrected for detector acceptance. This is compared to the standard model prediction of A(FB)(l)(predicted) = (4.7 +/- 0.1)%. A deviation from the standard model prediction as previously seen in a D0 measurement based on the analysis of the l + jets final state is not observed in these dilepton final states. The two results differ from each other by 1.4 standard deviations and are combined to obtain A(FB)(l) = (11.8 +/- 3.2)%. Furthermore, we present a first study of the top-quark polarization.
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66.
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67.
  • Abazov, V. M., et al. (författare)
  • Measurement of Spin Correlation in t(t)over-bar Production Using a Matrix Element Approach
  • 2011
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:3, s. 032001-
  • Tidskriftsartikel (refereegranskat)abstract
    • We determine the fraction of t (t) over bar events with spin correlation, assuming that the spin of the top quark is either correlated with the spin of the top antiquark as predicted by the standard model or is uncorrelated. For the first time we use a matrix-element-based approach to study t (t) over bar spin correlation. We use t (t) over bar -> W(+)bW(-)(b) over bar -> l(+)nu bl(-)(nu) over bar(b) over bar final states produced in p (p) over bar collisions at a center- of- mass energy root s = 1: 96 TeV, where l denotes an electron or a muon. The data correspond to an integrated luminosity of 5: 4 fb(-1) and were collected with the D0 detector at the Fermilab Tevatron collider. The result agrees with the standard model prediction. We exclude the hypothesis that the spins of the t (t) over bar are uncorrelated at the 97.7% C.L.
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68.
  • Abazov, V. M., et al. (författare)
  • Measurement of the combined rapidity and p(T) dependence of dijet azimuthal decorrelations in p(p)over-bar collisions at root s=1.96 TeV
  • 2013
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 721:4-5, s. 212-219
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first combined measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, using the recently proposed quantity R-Delta phi. The variable R-Delta phi measures the fraction of the inclusive dijet events in which the azimuthal separation of the two jets with the highest transverse momenta is less than a specified value of the parameter Delta phi(max). The quantity R-Delta phi is measured in p (p) over bar collisions at root s = 1.96 TeV, as a function of the dijet rapidity interval, the total scalar transverse momentum, and Delta phi(max). The measurement uses an event sample corresponding to an integrated luminosity of 0.7 fb(-1) collected with the DO detector at the Fermilab Tevatron Collider. The results are compared to predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for non-perturbative effects. The theory predictions describe the data well, except in the kinematic region of large dijet rapidity intervals and small Delta phi(max).
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69.
  • Abazov, V. M., et al. (författare)
  • Measurement of the differential cross section d sigma/dt in elastic p(p)over-bar scattering at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:1, s. 012009-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the elastic differential cross section dσ(pp̅ →pp̅ )/dt as a function of the four-momentum-transfer squared t. The data sample corresponds to an integrated luminosity of ≈31  nb-1 collected with the D0 detector using dedicated Tevatron pp̅ Collider operating conditions at √s=1.96  TeV and covers the range 0.26<|t|<1.2  GeV2. For |t|<0.6  GeV2, dσ/dt is described by an exponential function of the form Ae-b|t| with a slope parameter b=16.86±0.10(stat)±0.20(syst)  GeV-2. A change in slope is observed at |t|≈0.6  GeV2, followed by a more gradual |t| dependence with increasing values of |t|.
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70.
  • Abazov, V. M., et al. (författare)
  • Measurement of the differential gamma plus c-jet cross section and the ratio of differential gamma plus c and gamma plus b cross sections in p(p)over-bar collisions at root s=1.96 TeV
  • 2013
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 719:4-5, s. 354-361
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of the differential cross section d sigma/dp(T)(gamma) for the associated production of a c-quark jet and an isolated photon with rapidity vertical bar y(gamma)vertical bar < 1.0 and transverse momentum 30 < p(T)(gamma) < 300 GeV. The c-quark jets are required to have vertical bar y(jet)vertical bar < 1.5 and p(T)(jet) > 15 GeV. The ratio of differential cross sections for gamma + c to gamma + b production as a function of p(T)(gamma) is also presented. The results are based on data corresponding to an integrated luminosity of 8.7 fb(-1) recorded with the D0 detector at the Fermilab Tevatron p (p) over bar Collider at root s = 1.96 TeV. The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the k(T)-factorization approach, and to predictions from the SHERPA and PYTHIA Monte Carlo event generators. 
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71.
  • Abazov, V. M., et al. (författare)
  • Measurement of the Lambda(0)(b) lifetime in the exclusive decay Lambda(0)(b) -> J/psi Lambda(0) in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 85:11, s. 112003-
  • Tidskriftsartikel (refereegranskat)abstract
    • We measure the Lambda(0)(b) lifetime in the fully reconstructed decay Lambda(0)(b) -> J/psi Lambda(0) using 10.4 fb(-1) of p (p) over bar collisions collected with the D0 detector at root s = 1.96 TeV. The lifetime of the topologically similar decay channel B-0 -> J/psi K-S(0) is also measured. We obtain tau(Lambda(0)(b)) = 1.303 +/- 0.075(stat) +/- 0.035(syst) ps and tau(B-0) = 1.508 +/- 0.025(stat) +/- 0.043(syst) ps. Using these measurements, we determine the lifetime ratio of tau(Lambda(0)(b))/tau(B-0) = 0.864 +/- 0.052(stat) +/- 0.033(syst).
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72.
  • Abazov, V. M., et al. (författare)
  • Measurement of the production fraction times branching fraction f(b -> Lambda(b)) . B(Lambda(b) -> J/psi Lambda)
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:3, s. 031102-
  • Tidskriftsartikel (refereegranskat)abstract
    • The Lambda(b)(udb) baryon is observed in the decay Lambda(b) -> J/psi Lambda using 6.1fb(-1) of p (p) over bar collisions collected with the D0 detector at root s = 1/96 TeV. The production fraction multiplied by the branching fraction for this decay relative to that for the decay B(0) -> J/psi K(s)(0) is measured to be 0.345 +/- 0.034(stat) +/- 0.033(syst) +/- 0.003(PDG). Using the world average value of f(b -> B(0)) . B(B(0) -> J/psi K(s)(0) = (1.74 +/- 0.08) x 10(-5), we obtain f(b -> Lambda(b)) . B(Lambda(b) -> J/psi Lambda) = (6.01 +/- 0.60(stat) +/- 0.58(syst) +/- 0.28(PDG)) x 10(-5). This measurement represents an improvement in precision by about a factor of 3 with respect to the current world average.
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73.
  • Abazov, V. M., et al. (författare)
  • Measurement of the ratio of differential cross sections sigma(p(p)over-bar -> Z + b jet)/sigma(p(p)over-bar -> Z + jet) in p(p)over-bar collisions at root s = 1.96 TeV
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:9, s. 092010-
  • Tidskriftsartikel (refereegranskat)abstract
    • We measure the ratio of cross sections, sigma(p (p) over bar -> Z + b jet)/sigma(p (p) over bar -> Z + jet), for associated production of a Z boson with at least one jet. The ratio is also measured as a function of the Z boson transverse momentum, jet transverse momentum, jet pseudorapidity, and the azimuthal angle between the Z boson with respect to the highest p(T) b tagged jet. These measurements use data collected by the D0 experiment in Run II of Fermilab's Tevatron p (p) over bar Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of 9.7 fb(-1). The results are compared to predictions from next-to-leading order calculations and various Monte Carlo event generators.
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74.
  • Abazov, V. M., et al. (författare)
  • Measurement of the Semileptonic Charge Asymmetry using B-S(0) -> D-s mu X Decays
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:1, s. 011801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a measurement of the time-integrated flavor-specific semileptonic charge asymmetry in the decays of B-s(0) mesons that have undergone flavor mixing, a(sl)(s), using B-s(0)((B) over bar (0)(s)) -> D-s(-/+) mu(+/-) X decays, with D-s(-/+) -> phi pi(-/+) and phi -> K+K-, using 10.4 fb(-1) of proton-antiproton collisions collected by the D0 detector during Run II at the Fermilab Tevatron Collider. A fit to the difference between the time-integrated D0 detector during Run II at the Fermilab Tevatron Colllider. A fit to the difference between the time-integrated D-s(-) and D-s(+) mass distributions of the B-s(0) and ($) over bar (0)(s) candidates yields the flavor-specific asymmetry a(sl)(s) = [-1.12 +/- 0.74(stat) +/- 0.17(syst)]%, which is the most precise measurement and in agreement with the standard model prediction.
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75.
  • Abazov, V. M., et al. (författare)
  • Measurement of the ZZ production cross section in p(p)over-bar collisions at root s=1.96 TeV
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:1, s. 011103-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a new measurement of the production cross section sigma(p (p) over bar -> ZZ) at a center-of-mass energy root s = 1.96 TeV, obtained from the analysis of the four charged lepton final state l(+)l(-)l'(+)l'-(l,l' = e or mu). We observe ten candidate events with an expected background of 0: 37 +/- 0: 13 events. The measured cross section sigma(p (p) over bar -> ZZ) = 1.26(-0.37)(+0.47)(stat) +/- 0.14(syst) pb is in agreement with NLO QCD predictions. This result is combined with a previous result from the ZZ -> l(+)l(-)v (v) over bar channel resulting in a combined cross section of sigma(p (p) over bar -> ZZ) = 1.40(-0.37)(+0.43)(stat) +/- 0.14(syst) pb.
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76.
  • Abazov, V. M., et al. (författare)
  • Model-independent measurement of t-channel single top quark production in p(p)over-bar collisions at,root s=1.96 TeV
  • 2011
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 705:4, s. 313-319
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a model-independent measurement of t-channel electroweak production of single top quarks in p collisions at root s = 1.96 TeV. Using 5.4 fb(-1) of integrated luminosity collected by the DO detector at the Fermilab Tevatron Collider, and selecting events containing an isolated electron or muon, missing transverse energy and one or two jets originating from the fragmentation of b quarks, we measure a cross section sigma (p (p) over bar -> tqb + X) = 2.90 +/- 0.59 (stat + syst) pb for a top quark mass of 172.5 GeV. The probability of the background to fluctuate and produce a signal as large as the one observed is 1.6 x 10(-8), corresponding to a significance of 5.5 standard deviations. (C) 2011 Elsevier B.V. All rights reserved.
  •  
77.
  • Abazov, V. M., et al. (författare)
  • Observation of a narrow mass state decaying into Y(1S)+gamma in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:3, s. 031103-
  • Tidskriftsartikel (refereegranskat)abstract
    • Using data corresponding to an integrated luminosity of 1.3 fb(-1), we observe a narrow mass state decaying into Gamma(1S) + gamma, where the Gamma(1S) meson is detected by its decay into a pair of oppositely charged muons, and the photon is identified through its conversion into an electron-positron pair. The significance of this observation is 5.6 standard deviations. The mass of the state is centered at 10.551 +/- 0.014(stat) +/- 0.017(syst) GeV/c(2), which is consistent with that of the state recently observed by the ATLAS Collaboration.
  •  
78.
  • Abazov, V. M., et al. (författare)
  • Precise measurement of the top-quark mass from lepton plus jets events at D0
  • 2011
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 84:3, s. 032004-
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a measurement of the mass of the top quark in lepton + jets final states of p (p) over bar -> t (t) over bar data corresponding to 2.6 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. A matrix-element method is developed that combines an in situ jet energy calibration with our standard jet energy scale derived from studies of gamma + jet and dijet events. We then implement a flavor-dependent jet-response correction through a novel approach. This method is used to measure a top-quark mass of m(t) = 176.01 +/- 1.64 GeV. Combining this result with our previous result obtained on an independent data set, we measure a top-quark mass of m(t) = 174.94 +/- 1.49 GeV for a total integrated luminosity of 3.6 fb(-1).
  •  
79.
  • Abazov, V. M., et al. (författare)
  • Precise Measurement of the Top Quark Mass in the Dilepton Channel at D0
  • 2011
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:8, s. 082004-
  • Tidskriftsartikel (refereegranskat)abstract
    • We measure the top quark mass (m(t)) in p (p) over bar collisions at a center of mass energy root s = 1.96 TeV using dilepton t (t) over bar -> W(+)bW(-)b(-) -> l(+)nu(l)bl(-)(nu) over bar (l)(b) over bar events, where l denotes an electron, a muon, or a tau that decays leptonically. The data correspond to an integrated luminosity of 5.4 fb(-1) collected with the D0 detector at the Fermilab Tevatron Collider. We obtain m(t) = 174.0 +/- 1.8(stat) +/- 2.4(syst) GeV, which is in agreement with the current world average m(t) = 173.3 +/- 1.1 GeV. This is currently the most precise measurement of mt in the dilepton channel.
  •  
80.
  • Abazov, V. M., et al. (författare)
  • Search for a Fourth Generation t ' Quark in p(p)over-bar Collisions at root s=1.96 TeV
  • 2011
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:8, s. 082001-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for pair production of a fourth generation t' quark and its antiparticle, followed by their decays to a W boson and a jet, based on an integrated luminosity of 5: 3 fb(-1) of proton-antiproton collisions at root s = 1.96 TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the t'(t) over bar' production cross section that exclude at the 95% C. L. a t' quark that decays exclusively to W + jet with a mass below 285 GeV. We observe a small excess in the mu + jets channel which reduces the mass range excluded compared to the expected limit of 320 GeV in the absence of a signal.
  •  
81.
  • Abazov, V. M., et al. (författare)
  • Search for charged massive long-lived particles at root s=1.96 TeV
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:5, s. 052011-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for charged massive long-lived particles (CMLLPs) that are pair produced in p (p) over bar collisions at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider. Our result is a combination of two searches where either one or both CMLLPs are reconstructed in the detector. We select events with muonlike particles that have both speed and ionization energy loss (dE/dx) different from muons produced in p (p) over bar collisions. In the absence of evidence for CMLLPs corresponding to 6.3 fb(-1) of integrated luminosity, we set limits on the CMLLP masses in several supersymmetric models, excluding masses below 278 GeV for long-lived gaugino-like charginos, and masses below 244 GeV for long-lived Higgsino-like charginos at the 95% C.L. We also set limits on the cross section for pair production of long-lived scalar tau leptons that range from 0.04 to 0.008 pb for scalar tau lepton masses of 100-300 GeV.
  •  
82.
  • Abazov, V. M., et al. (författare)
  • Search for Higgs boson production in oppositely charged dilepton and missing energy events in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:3, s. 032010-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the standard model Higgs boson using events with two oppositely charged leptons and large missing transverse energy as expected in H -> WW decays. The events are selected from data corresponding to 8.6 fb(-1) of integrated luminosity in p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. No significant excess above the standard model background expectation in the Higgs boson mass range this search is sensitive to is observed, and upper limits on the Higgs boson production cross section are derived.
  •  
83.
  • Abazov, V. M., et al. (författare)
  • Search for Higgs boson production in oppositely charged dilepton and missing energy final states in 9.7 fb(-1) of p(p)over-bar collisions at root s=1.96 TeV
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052006-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the Higgs boson in final states with two oppositely charged leptons and large missing transverse energy as expected in H -> WW -> lvl(1)v(1)decays. The events are selected from the full Run II data sample of 9.7 fb(-1) of p (p) over bar collisions collected with the D0 detector at the Fermilab Tevatron Collider at root s = 1.96 TeV. To validate our search methodology, we measure the nonresonant WW production cross section and find sigma(WW) 11.6 +/- 0.7 pb, in agreement with the standard model prediction. In the Higgs boson search, no significant excess above the background expectation is observed. Upper limits at the 95% confidence level on the Higgs boson production cross section are therefore derived. Within the standard model, the Higgs boson mass range 159 < M-H < 176 GeV is excluded while the expected exclusion sensitivity is 156 < M-H < 172 GeV. For a mass hypothesis of M-H = 125 GeV, we exclude Higgs boson production cross sections 4.1 times larger than the standard model expectation, which is compatible with the presence of a Higgs boson at this mass. Within a theoretical framework with a fourth generation of fermions, the mass range 125 < M-H < 218 GeV is excluded. The search results are also interpreted in the context of fermiophobic Higgs boson couplings, which yields an exclusion of fermiophobic Higgs boson production cross sections 3.1 times larger than the expectation for M-H = 125 GeV.
  •  
84.
  • Abazov, V. M., et al. (författare)
  • Search for Higgs bosons decaying to tau(+)tau(-) pairs in p(p)over-bar collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 707:3-4, s. 323-329
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the production of neutral Higgs bosons decaying into tau(+)tau(-) pairs in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb(-1), were collected by the DO experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tau(+)tau(-) pairs, and we interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.
  •  
85.
  • Abazov, V. M., et al. (författare)
  • Search for the Higgs boson in lepton, tau, and jets final states
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052005-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the standard model Higgs boson in final states with an electron or muon and a hadronically decaying tau lepton in association with two or more jets using 9:7 fb(-1) of Run II Fermilab Tevatron Collider data collected with the D0 detector. The analysis is sensitive to Higgs boson production via gluon fusion, associated vector boson production, and vector boson fusion, followed by the Higgs boson decay to tau lepton pairs or to W boson pairs. The ratios of 95% C.L. upper limits on the cross section times branching ratio to those predicted by the standard model are obtained for orthogonal subsamples that are enriched in either H -> tau tau decays or H -> WW decays, and for the combination of these subsample limits. The observed and expected limit ratios for the combined subsamples at a Higgs boson mass of 125 GeV are 11.3 and 9.0, respectively.
  •  
86.
  • Abazov, V. M., et al. (författare)
  • Search for Violation of Lorentz Invariance in Top Quark Pair Production and Decay
  • 2012
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 108:26, s. 261603-
  • Tidskriftsartikel (refereegranskat)abstract
    • Using data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to 5: 3 fb(-1) of integrated luminosity, we search for violation of Lorentz invariance by examining the t (t) over bar production cross section in lepton + jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the t (t) over bar production cross section on sidereal time as the orientation of the detector changes with the rotation of the Earth. Within this framework, we measure components of the matrices (c(Q))(mu nu 33) and (c(U))(mu nu 33) containing coefficients used to parametrize violation of Lorentz invariance in the top quark sector. Within uncertainties, these coefficients are found to be consistent with zero.
  •  
87.
  • Abazov, V. M., et al. (författare)
  • Search for Z gamma events with large missing transverse energy in p(p)over-bar collisions at root s = 1.96 TeV
  • 2012
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 86:7, s. 071701-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first search for new phenomena in Z gamma final states with large missing transverse energy using data corresponding to an integrated luminosity of 6.2 fb(-1) collected with the D0 experiment in p (p) over bar collisions at root s 1.96 TeV. This signature is predicted in gauge-mediated supersymmetry-breaking models, where the lightest neutralino (chi) over tilde (0)(1) is the next-to-lightest supersymmetric particle and is produced in pairs, possibly through decay from heavier supersymmetric particles. The (chi) over tilde (0)(1) can decay either to a Z boson or a photon and an associated gravitino that escapes detection. We exclude this model at the 95% C.L. for supersymmetry-breaking scales of Lambda < 87 TeV.
  •  
88.
  • Abazov, V. M., et al. (författare)
  • Combination of searches for anomalous top quark couplings with 5.4 fb(-1) of p(p)over-bar collisions
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 713:3, s. 165-171
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in t (t) over bar events. We set upper limits on anomalous tWb coupling form factors using data collected with the DO detector at the Tevatron p (p) over bar collider corresponding to an integrated luminosity of 5.4 fb(-1).
  •  
89.
  • Abazov, V. M., et al. (författare)
  • Determination of the pole and (MS)over-bar masses of the top quark from the t(t)over-bar cross section
  • 2011
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 703:4, s. 422-427
  • Tidskriftsartikel (refereegranskat)abstract
    • We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the t (t) over bar cross section measured in the lepton + jets channel in p (p) over bar collisions at root s = 1.96 TeV using 5.3 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and (MS) over bar mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
  •  
90.
  • Abazov, V. M., et al. (författare)
  • Measurement of the photon plus b-jet production differential cross section in p(p)over-bar) collisions at root s=1.96 TeV
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 714:1, s. 32-39
  • Tidskriftsartikel (refereegranskat)abstract
    • We present measurements of the differential cross section d sigma/dp(T)(gamma) for the inclusive production of a photon in association with a b-quark jet for photons with rapidities vertical bar y(gamma)vertical bar < 1.0 and 30 < p(T)(gamma) < 300 GeV, as well as for photons with 1.5 < vertical bar y(gamma)vertical bar < 2.5 and 30 < p(T)(gamma) < 200 GeV, where p(T)(gamma) is the photon transverse momentum. The b-quark jets are required to have p(T) > 15 GeV and rapidity vertical bar Y-jet vertical bar < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb(-1), recorded with the DO detector at the Fermilab Tevatron p<(p)over bar>) Collider at root s = 1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the k(T)-factorization QCD approach, and those from the SHERPA and PYTHIA Monte Carlo event generators.
  •  
91.
  • Abazov, V. M., et al. (författare)
  • Search for the rare decay B-s(0) -> mu(+) mu(-)
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:7, s. 072006-
  • Tidskriftsartikel (refereegranskat)abstract
    • We perform a search for the rare decay B-s(0) -> mu(+) mu(-) using data collected by the D0 experiment at the Fermilab Tevatron Collider. This result is based on the full D0 Run II data set corresponding to 10.4 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV. We use a multivariate analysis to increase the sensitivity of the search. In the absence of an observed number of events above the expected background, we set an upper limit on the decay branching fraction of B(B-s(0) -> mu(+) mu(-)) < 15 x 10(-9) (12 x 10(-9)) at the 95% (90%) C.L. 
  •  
92.
  • Abazov, V. M., et al. (författare)
  • Search for the standard model Higgs boson in tau lepton final states D0 Collaboration
  • 2012
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 714:2-5, s. 237-245
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a search for the standard model Higgs boson in final states with an electron or muon and a hadronically decaying tau lepton in association with zero, one, or two or more jets using data corresponding to an integrated luminosity of up to 7.3 fb(-1) collected with the D0 detector at the Fermilab Tevatron collider. The analysis is sensitive to Higgs boson production via gluon-gluon fusion, associated vector boson production, and vector boson fusion, and to Higgs boson decays to tau tau, WW, ZZ and b (b) over bar pairs. Observed (expected) limits are set on the ratio of 95% C.L. upper limits on the cross section times branching ratio, relative to those predicted by the Standard Model, of 22 (14) at a Higgs boson mass of 115 GeV and 6.8 (7.7) at 165 GeV.
  •  
93.
  • Abazov, V. M., et al. (författare)
  • Study of double parton interactions in diphoton plus dijet events in p<(p)over bar> collisions at root s = 1.96 TeV
  • 2016
  • Ingår i: PHYSICAL REVIEW D. - 2470-0010. ; 93:5
  • Tidskriftsartikel (refereegranskat)abstract
    • We use a sample of diphoton + dijet events to measure the effective cross section of double parton interactions, which characterizes the area containing the interacting partons in proton-antiproton collisions, and find it to be sigma(eff) = 19.3 +/- 1.4(stat) +/- 7.8(syst) mb. The sample was collected by the D0 detector at the Fermilab Tevatron collider in p (p) over bar collisions at root s = 1.96 TeV and corresponds to an integrated luminosity of 8.7 fb(-1).
  •  
94.
  • Abazov, V. M., et al. (författare)
  • B-s(0) lifetime measurement in the CP-odd decay channel B-s(0) -> J/Psi f(0)(980)
  • 2016
  • Ingår i: PHYSICAL REVIEW D. - 2470-0010. ; 94:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The lifetime of the B-s(0) meson is measured in the decay channel B-s(0) -> J/Psi pi(+)pi(-) with 880 <= M pi+pi- <= 1080 MeV/c(2), which is mainly a CP-odd state and dominated by the f(0)(980) resonance. In 10.4 fb(-1) of data collected with the D0 detector in Run II of the Tevatron, the lifetime of the B-s(0) meson is measured to be tau(B-s(0)) = 1.70 +/- 0.14(stat) +/- 0.05(syst) ps. Neglecting CP violation in B-s(0)/(B) over bar (0)(s) mixing, the measurement can be translated into the width of the heavy mass eigenstate of the B-s(0), Gamma(H) = 0.59 +/- 0.05(stat) +/- 0.02(syst) ps(-1).
  •  
95.
  • Abazov, V. M., et al. (författare)
  • Combination of D0 measurements of the top quark mass
  • 2017
  • Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 95:11
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a combination of measurements of the top quark mass by the D0 experiment in the lepton + jets and dilepton channels. We use all the data collected in Run I (1992-1996) at root s = 1.8 TeV and Run II (2001-2011) at root s = 1.96 TeV of the Tevatron p (p) over bar collider, corresponding to integrated luminosities of 0.1 fb(-1) and 9.7 fb(-1), respectively. The combined result is: m(t) = 174.95 +/- 0.40(stat)+/- 0.64(syst) GeV = 174.95 +/- 0.75 GeV.
  •  
96.
  • Abazov, V. M., et al. (författare)
  • Combined search for the Higgs boson with the D0 experiment
  • 2013
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:5, s. 052011-
  • Tidskriftsartikel (refereegranskat)abstract
    • We perform a combination of searches for standard model Higgs boson production in p (p) over bar collisions recorded by the D0 detector at the Fermilab Tevatron Collider at a center of mass energy of root s = 1.96 TeV. The different production and decay channels have been analyzed separately, with integrated luminosities of up to 9.7 fb(-1) and for Higgs boson masses 90 <= M-H <= 200 GeV. We combine these final states to achieve optimal sensitivity to the production of the Higgs boson. We also interpret the combination in terms of models with a fourth generation of fermions, and models with suppressed Higgs boson couplings to fermions. The result excludes a standard model Higgs boson at 95% C.L. in the ranges 90 < M-H < 101 GeV and 157 < M-H < 178 GeV, with an expected exclusion of 155 < M-H < 175 GeV. In the range 120 < M-H < 145 GeV, the data exhibit an excess over the expected background of up to 2 standard deviations, consistent with the presence of a standard model Higgs boson of mass 125 GeV.
  •  
97.
  • Abazov, V. M., et al. (författare)
  • Constraints on Models for the Higgs Boson with Exotic Spin and Parity in VH -> Vb(b)over-bar Final States
  • 2014
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:16, s. 161802-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present constraints on models containing non-standard-model values for the spin J and parity P of the Higgs boson H in up to 9.7 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. These are the first studies of Higgs boson J(P) with fermions in the final state. In the ZH -> llb (b) over bar, WH -> l nu b (b) over barb, and ZH -> nu nu b (b) over bar final states, we compare the standard model (SM) Higgs boson prediction, J(P) = 0(+), with two alternative hypotheses, J(P) = 0(-) and J(P) = 2(+). We use a likelihood ratio to quantify the degree to which our data are incompatible with non-SM J(P) predictions for a range of possible production rates. Assuming that the production rate in the signal models considered is equal to the SM prediction, we reject the J(P) = 0(-) and J(P) = 2(+) hypotheses at the 97.6% CL and at the 99.0% CL, respectively. The expected exclusion sensitivity for a J(P) = 0(-)(J(P) = 2(+)) state is at the 99.86% (99.94%) CL. Under the hypothesis that our data are the result of a combination of the SM-like Higgs boson and either a J(P) = 0(-) or a J(P) = 2(+) signal, we exclude a J(P) = 0(-) fraction above 0.80 and a JP = 2(+) fraction above 0.67 at the 95% CL. The expected exclusion covers J(P) = 0(-)(J(P) = 2(+)) fractions above 0.54 (0.47).
  •  
98.
  • Abazov, V. M., et al. (författare)
  • Double parton interactions in gamma+3 jet and gamma plus b/c jet+2 jet events in p(p)over-bar collisions at root s=1.96 TeV
  • 2014
  • Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:7, s. 072006-
  • Tidskriftsartikel (refereegranskat)abstract
    • We determine the fraction of events with double parton (DP) Scattering in a single p (p) over bar collisions at root s = 1.96 TeV in gamma + 3 jet and gamma + b/c jet + 2 jet events collected with the D0 detector and corresponding to an integrated luminosity of about 8.7 fb(-1). The DP fractions and effective cross sections (sigma(eff)) are measured for both event samples using the same kinematic selections. The measured DP fractions range from 0.21 to 0.17, with effective cross sections in the gamma + 3 jet and gamma + b/cjet + 2 jet samples of sigma(incl)(eff) = 12.7 +/- 0.2(stat) +/- 1.3(syst) mb and sigma(HF)(eff) = 14.6 +/- 0.6(stat) +/- 3.2(syst) mb, respectively.
  •  
99.
  • Abazov, V. M., et al. (författare)
  • Electron and photon identification in the Do experiment
  • 2014
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 750, s. 78-95
  • Tidskriftsartikel (refereegranskat)abstract
    • The electron and photon reconstruction and identification algorithms used by the DO Collaboration at the Fermilab Tevatron collider are described. The determination of the electron energy scale and resolution is presented. Studies of the performance of the electron and photon reconstruction and identification are summarized. The results are based on measurements of Z boson decay events of Z ee and Z gamma ll(i=e mu) collected in pp(over bar) collisions at a center- of- mass energy of 1.96 TeV using an integrated luminosity of up to10 fb(-1.)
  •  
100.
  • Abazov, V. M., et al. (författare)
  • Evidence for a B-s(0)pi(+/-) State
  • 2016
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 117:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We report evidence for a narrow structure, X(5568), in the decay sequence X(5568) -> B-s(0)pi(+/-), B-s(0) -> J/psi phi, J/psi -> mu(+)mu(-), phi -> K+K-. This is evidence for the first instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m = 5567.8 +/- 2.9(stat)(-1.9)(+0.9) (syst) MeV/c(2) and Gamma = 21.9 +/- 6.4(stat)(-2.5)(+5.0) (syst) MeV/c(2). If the decay is X(5568) -> B-s*pi(+/-). B-s(0)gamma pi(+/-) with an unseen gamma, m(X(5568)) will be shifted up by m(B-s*) - m(B-s(0)) similar to 49 MeV/c(2). This measurement is based on 10.4 fb(-1) of p (p) over bar collision data at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
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