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1.	Aaltonen, T., et al. (författare) Combination of Tevatron Searches for the Standard Model Higgs Boson in the W+W- Decay Mode 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061802- Tidskriftsartikel (refereegranskat)abstract We combine searches by the CDF and D0 Collaborations for a Higgs boson decaying to W+W-. The data correspond to an integrated total luminosity of 4.8 (CDF) and 5.4 (D0) fb(-1) of p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron collider. No excess is observed above background expectation, and resulting limits on Higgs boson production exclude a standard model Higgs boson in the mass range 162-166 GeV at the 95% C.L.
2.	Abazov, V. M., et al. (författare) Measurement of the B-s(0) lifetime using semileptonic decays 2006 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:24, s. 241801- Tidskriftsartikel (refereegranskat)abstract 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.
3.	Abazov, V. M., et al. (författare) Evidence for the Decay B-s(0)->(DsDs())-D-() and a Measurement of Delta Gamma(CP)(s)/Gamma(s) 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 091801- Tidskriftsartikel (refereegranskat)abstract We search for the semi-inclusive process B-s(0)->(DsDs())-D-() using 2.8 fb(-1) of pp collisions at s=1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We observe 26.6 +/- 8.4 signal events with a significance above background of 3.2 standard deviations yielding a branching ratio of B(B-s(0)->(DsDs())-D-())=0.035 +/- 0.010(stat.)+/- 0.011(syst.). Under certain theoretical assumptions, these double-charm final states saturate CP-even eigenstates in the B-s(0) decays resulting in a width difference of Delta Gamma(CP)(s)/Gamma(s)=0.072 +/- 0.021(stat.)+/- 0.022(syst.).
4.	Abazov, V. M., et al. (författare) Search for Anomalous Top-Quark Couplings with the D0 Detector 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 092002- Tidskriftsartikel (refereegranskat)abstract Anomalous Wtb couplings modify the angular correlations of the top-quark decay products and change the single top-quark production cross section. We present limits on anomalous top-quark couplings by combining information from W boson helicity measurements in top-quark decays and anomalous coupling searches in the single top-quark final state. We set limits on right-handed vector couplings as well as left-handed and right-handed tensor couplings based on about 1 fb(-1) of data collected by the D0 experiment.
5.	Abazov, V. M., et al. (författare) Measurement of the Angular and Lifetime Parameters of the Decays B-d(0) -> J/psi K(0) and B-s(0) -> J/psi phi 2009 Ingår i:* Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:3, s. 032001-:102, s. 032001- Tidskriftsartikel (refereegranskat)abstract We present measurements of the linear polarization amplitudes and the strong relative phases that describe the flavor-untagged decays B-d(0) --> J/psi K(0) and B-s(0) --> J/psi phi in the transversity basis. We also measure the mean lifetime (tau) over bar (s) of the B-s(0) mass eigenstates and the lifetime ratio (tau) over bar (s)/tau(d). The analyses are based on approximately 2.8 fb(-1) of data recorded with the D0 detector. From our measurements of the angular parameters we conclude that there is no evidence for a deviation from flavor SU( 3) symmetry for these decays and that the factorization assumption is not valid for the B-d(0) --> J/psi K(0) decay.
6.	Abazov, V. M., et al. (författare) Search for Large Extra Spatial Dimensions in the Dielectron and Diphoton Channels in p(p)over-bar Collisions at root s=1.96 TeV 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 051601-:102, s. 051601- Tidskriftsartikel (refereegranskat)abstract We report on a search for large extra spatial dimensions in the dielectron and diphoton channels using a data sample of 1: 05 fb(-1) of p (p) over bar collisions at a center-of-mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. The invariant mass spectrum of the data agrees well with the prediction of the standard model. We find the most restrictive 95% C. L. lower limits on the effective Planck scale between 2.1 and 1.3 TeV for 2 to 7 extra dimensions.
7.	Abazov, V. M., et al. (författare) Search for Neutral Higgs Bosons at High tan beta in the b(h/H/A) -> b tau(+)tau(-) Channel 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 051804-:102, s. 051804- Tidskriftsartikel (refereegranskat)abstract 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.
8.	Abazov, V. M., et al. (författare) Measurement of the top quark mass in final states with two leptons 2009 Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 80, s. 092006- Tidskriftsartikel (refereegranskat)abstract We present measurements of the top quark mass (m(t)) in tt candidate events with two final state leptons using 1 fb(-1) of data collected by the D0 experiment. Our data sample is selected by requiring two fully identified leptons or by relaxing one lepton requirement to an isolated track if at least one jet is tagged as a b jet. The top quark mass is extracted after reconstructing the event kinematics under the tt hypothesis using two methods. In the first method, we integrate over expected neutrino rapidity distributions, and in the second we calculate a weight for the possible top quark masses based on the observed particle momenta and the known parton distribution functions. We analyze 83 candidate events in the data and obtain m(t)=176.2 +/- 4.8(stat)+/- 2.1(sys) GeV and m(t)=173.2 +/- 4.9(stat)+/- 2.0(sys) GeV for the two methods, respectively. Accounting for correlations between the two methods, we combine the measurements to obtain m(t)=174.7 +/- 4.4(stat)+/- 2.0(sys) GeV.
9.	Abazov, V. M., et al. (författare) Search for CP violation in B-s(0) -> mu(+) D-s(-) X decays in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998 .- 1550-2368. ; 82:1, s. 012003- Tidskriftsartikel (refereegranskat)abstract We have performed a search for CP violation in a sample of B-s(0) -> mu+Ds-X decays corresponding to 5 fb(-1) of proton-antiproton collisions collected by the D0 detector in Run II at the Fermilab Tevatron Collider. New physics in B-s(0) mixing could contribute a significant CP violating weak phase, which would be observed as a difference in the decay-time distribution for B-s(0) -> (B) over bar (0)(s) oscillated states versus that for (B) over bar (0)(s) -> B-s(0). A fit to the decay-time distributions of the B-s(0)/(B) over bar (0)(s) candidates yields the flavor-specific asymmetry as a(fs)(s) = [-1.7 +/- 9.1(stat)(-1.5)(+1.4)(syst) x 10(-3), which excludes CP violation due to new physics within the experimental sensitivity.
10.	Abazov, V. M., et al. (författare) Dependence of the t(t)over-bar production cross section on the transverse momentum of the top quark 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 515-521 Tidskriftsartikel (refereegranskat)abstract We present a measurement of the differential cross section for t (t) over bar events produced in p (p) over bar collisions at root s = 1.96 TeV as a function of the transverse momentum (p(T)) of the top quark. The selected events contain a high-p(T) lepton (l), a large imbalance in p(T). four or more jets with at least one candidate for a b jet, and correspond to 1 fb(-1) of integrated luminosity recorded with the D0 detector. Objects in the event are associated through a constrained kinematic fit to the t (t) over bar -> WbW (b) over bar -> lvbq (q) over bar' (b) over bar process. Results from next and next-to-next-to-leading-order perturbative QCD calculations agree with the measured differential cross section. Comparisons are also provided to predictions from Monte Carlo event generators using QCD calculations at different levels of precision. (C) 2010 Elsevier B.V. All rights reserved.
11.	Abazov, V. M., et al. (författare) Determination of the strong coupling constant from the inclusive jet cross section in pp collisions at s=1.96 TeV 2009 Ingår i: PHYS REV D. - 1550-7998 .- 1550-2368. ; 80, s. 111107- Tidskriftsartikel (refereegranskat)abstract We determine the strong coupling constant alpha(s) and its energy dependence from the p(T) dependence of the inclusive jet cross section in pp collisions at s=1.96 TeV. The strong coupling constant is determined over the transverse momentum range 50 < p(T)< 145 GeV. Using perturbative QCD calculations to order O(alpha(3)(s)) combined with O(alpha(4)(s)) contributions from threshold corrections, we obtain alpha(s)(M-Z)=0.1161(-0.0048)(+0.0041). This is the most precise result obtained at a hadron-hadron collider.
12.	Abazov, V. M., et al. (författare) Double parton interactions in gamma+3 jet events in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 81:5, s. 052012- Tidskriftsartikel (refereegranskat)abstract We have used a sample of gamma + 3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb(-1) to determine the fraction of events with double parton scattering (f(DP)) in a single p (p) over bar collision at root s = 1.96 TeV. The DP fraction and effective cross section (sigma(eff)), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in p(T)) jet transverse momentum p(T)(jet2) within the range 15 <= p(T)(jet2) <= 30 GeV. In this range, f(DP) varies between 0.23 <= f(DP) <= 0.47, while sigma(eff) has the average value sigma(ave)(eff) = 16.4 +/- 0.3(stat) +/- 2.3(syst) mb.
13.	Abazov, V. M., et al. (författare) Measurement of the t-channel single top quark production cross section 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 363-369 Tidskriftsartikel (refereegranskat)abstract The DO Collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb(-1) of p (p) over bar collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14(-0.80)(+0.94) pb for the t-channel and 1.05 +/- 0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.
14.	Abazov, V. M., et al. (författare) Measurement of the t(t)over-bar cross section using high-multiplicity jet events 2010 Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 82, s. 032002- Tidskriftsartikel (refereegranskat)abstract We present a measurement of the t (t) over bar cross section using high-multiplicity jet events produced in p (p) over bar collisions at root s = 1.96 TeV. These data were recorded at the Fermilab Tevatron Collider with the D0 detector. Events with at least six jets, two of them identified as b jets, were selected from a 1 fb(-1) data set. The measured cross section, assuming a top quark mass of 175 GeV/c(2), is 6.9 +/- 2.0 pb, in agreement with theoretical expectations.
15.	Abazov, V. M., et al. (författare) Measurement of Z/gamma* plus jet plus X angular distributions in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:4-5, s. 370-380 Tidskriftsartikel (refereegranskat)abstract We present the first measurements at a hadron collider of differential cross sections for Z/gamma* + jet + X production in Delta phi(Z. jet), vertical bar Delta y(Z, jet)vertical bar and vertical bar y(boost)(Z + jet)vertical bar. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.
16.	Abazov, V. M., et al. (författare) Search for a Resonance Decaying into WZ Boson Pairs in p(p)over-bar Collisions 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061801- Tidskriftsartikel (refereegranskat)abstract We present the first search for an electrically charged resonance W' decaying to a WZ boson pair using 4.1 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron p (p) over bar collider. The WZ pairs are reconstructed through their decays into three charged leptons (l = e, mu). A total of 9 data events is observed in good agreement with the background prediction. We set 95% C.L. limits on the W'WZ coupling and on the W' production cross section multiplied by the branching fractions. We also exclude W' masses between 188 and 520 GeV within a simple extension of the standard model and set the most restrictive limits to date on low-scale technicolor models.
17.	Abazov, V. M., et al. (författare) Search for charged Higgs bosons in top quark decays 2009 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 682:3, s. 278-286 Tidskriftsartikel (refereegranskat)abstract We present a search for charged Higgs bosons in top quark decays. We analyze the e + jets, mu + jets, ee, e mu, mu mu, tau e and tau mu final states from top quark pair production events, using data from about 1 fb (1) of integrated luminosity recorded by the DO experiment at the Fermilab Tevatron Collider. We consider different scenarios of possible charged Higgs boson decays, one where the charged Higgs boson decays purely hadronically into a charm and a strange quark, another where it decays into a tau lepton and a tau neutrino and a third one where both decays appear. We extract limits on the branching ratio B(t -> H(+)b) for all these models. We use two methods, one where the t (t) over bar production cross section is fixed, and one where the cross section is fitted simultaneously with B(t -> H(+)b). Based on the extracted limits, we exclude regions in the charged Higgs boson mass and tan beta parameter space for different scenarios of the minimal supersymmetric standard model.
18.	Abazov, V. M., et al. (författare) Search for Higgs Boson Production in Dilepton and Missing Energy Final States with 5.4 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061804- Tidskriftsartikel (refereegranskat)abstract A search for the standard model Higgs boson is presented using events with two charged leptons and large missing transverse energy selected from 5.4 fb(-1) of integrated luminosity in p ($) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron collider. No significant excess of events above background predictions is found, and observed (expected) upper limits at 95% confidence level on the rate of Higgs boson production are derived that are a factor of 1.55 (1.36) above the predicted standard model cross section at m(H) = 165 GeV.
19.	Abazov, V. M., et al. (författare) Search for New Fermions ("Quirks'') at the Fermilab Tevatron Collider 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:21, s. 211803- Tidskriftsartikel (refereegranskat)abstract We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in 2: 4 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron p (p) over bar collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like SU(N) sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107, 119, and 133 GeV for the mass of a charged quirk with strong dynamics scale Lambda in the range from 10 keV to 1 MeV and N = 2, 3, and 5, respectively.
20.	Abazov, V. M., et al. (författare) Search for single top quarks in the tau plus jets channel using 4.8 fb(-1) of p(p)over-bar collision data 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 5-14 Tidskriftsartikel (refereegranskat)abstract We present the first direct search for single top quark production using reconstructed tau leptons in the final state. The search is based on 4.8 fb(-1) of integrated luminosity collected in p (p) over bar collisions at root s= 1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We select events with a final state including an isolated tau lepton. missing transverse energy, two or three jets, one or two of them being identified as b quark jet. We use a multivariate technique to discriminate signal from background. The number of events observed in data in this final state is consistent with the signal plus background expectation. We set in the tau + jets channel an upper limit on the single top quark cross section of 7.3 pb at the 95% C.L. This measurement allows a gain of 4% in expected sensitivity for the observation of single top production when combining it with electron + jets and muon + jets channels already published by the DO Collaboration with 2.3 fb(-1) of data. We measure a combined cross section of 3.84(-0.83)(+0.89) pb, which is the most precise measurement to date.
21.	Abazov, V. M., et al. (författare) Search for the Associated Production of a b Quark and a Neutral Supersymmetric Higgs Boson that Decays into τ Pairs 2010 Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 104:15 Tidskriftsartikel (refereegranskat)abstract We report results from a search for production of a neutral Higgs boson in association with a b quark. We search for Higgs decays to tau pairs with one tau subsequently decaying to a muon and the other to hadrons. The data correspond to 2: 7 fb(-1) of p (p) over bar collisions recorded by the D0 detector at.. root s = 1.96 TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.
22.	Abazov, V. M., et al. (författare) Search for the Standard Model Higgs Boson in the ZH -> v(v)over-barb(b)over-bar Channel in 5.2 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:7, s. 071801- Tidskriftsartikel (refereegranskat)abstract A search is performed for the standard model Higgs boson in 5.2 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV, collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered is a pair of b jets and large missing transverse energy, as expected from p (p) over bar -> ZH -> v (v) over barb (b) over bar production. The search is also sensitive to the WH -> lvb (b) over bar channel when the charged lepton is not identified. For a Higgs boson mass of 115 GeV, a limit is set at the 95% C.L. on the cross section multiplied by branching fraction for [p (p) over bar -> (Z/W)H](H -> b (b) over bar) that is a factor of 3.7 larger than the standard model value, consistent with the factor of 4.6 expected.
23.	Abazov, V. M., et al. (författare) Search for a heavy neutral gauge boson in the dielectron channel with 5.4 fb(-1) of p(p)over-bar collisions at root s=1.96 TeV 2011 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 695:1-4, s. 88-94 Tidskriftsartikel (refereegranskat)abstract We report the results of a search for a heavy neutral gauge boson Z' decaying into the dielectron final state using data corresponding to an integrated luminosity of 5.4 fb(-1) collected by the D0 experiment at the Fermilab Tevatron Collider. No significant excess above the standard model prediction is observed in the dielectron invariant-mass spectrum. We set 95 sigma(p (p) over bar -> Z') x BR(Z' -> ee) depending on the dielectron invariant mass. These cross section limits are used to determine lower mass limits for bosons in a variety of models. For the sequential standard model boson a lower mass limit of 1023 GeV is obtained.
24.	Abazov, V. M., et al. (författare) Search for Diphoton Events with Large Missing Transverse Energy in 6.3 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:22, s. 221802- Tidskriftsartikel (refereegranskat)abstract We report a search for diphoton events with large missing transverse energy produced in p (p) over bar collisions at root s = 1.96 TeV. The data were collected with the D0 detector at the Fermilab Tevatron Collider and correspond to 6.3 fb(-1) of integrated luminosity. The observed missing transverse energy distribution is well described by the standard model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the standard model. In a gauge-mediated supersymmetry breaking scenario, the breaking scale Lambda is excluded for Lambda < 124 TeV. In a universal extra dimension model including gravitational decays, the compactification radius R-c is excluded for R-c(-1) < 477 GeV.
25.	Abazov, V. M., et al. (författare) Search for Events with Leptonic Jets and Missing Transverse Energy in p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:21, s. 211802- Tidskriftsartikel (refereegranskat)abstract We present the first search for pair production of isolated jets of charged leptons in association with a large imbalance in transverse energy in p (p) over bar collisions using 5: 8 fb(-1) of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider. No excess is observed above the standard model background, and the result is used to set upper limits on the production cross section of pairs of supersymmetric chargino and neutralino particles as a function of "dark-photon'' mass, where the dark photon is produced in the decay of the lightest supersymmetric particle.
26.	Abazov, V. M., et al. (författare) Search for Sneutrino Production in e mu Final States in 5.3 fb(-1) of p(p)over-bar Collisions at root s = 1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:19, s. 191802- Tidskriftsartikel (refereegranskat)abstract We report the results of a search for R parity violating (RPV) interactions leading to the production of supersymmetric sneutrinos decaying into e mu final states using 5.3 fb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Having observed no evidence for production of e mu resonances, we set direct bounds on the RPV couplings lambda'(311) and lambda(312) as a function of sneutrino mass.
27.	Abazov, V. M., et al. (författare) Search for ZH -> l(+)l(-) b(b)over-bar Production in 4.2 fb(-1) of p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:25, s. 251801- Tidskriftsartikel (refereegranskat)abstract We present a search for the standard model Higgs boson produced in association with a Z boson in 4: 2 fb(-1) of p (p) over bar collisions, collected with the D0 detector at the Fermilab Tevatron 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 b-tagged jet. In the absence of an excess over the background expected from other standard model processes, limits on the ZH cross section multiplied by the branching ratios are set. The limit at M-H = 115 GeV is a factor of 5.9 larger than the standard model prediction.
28.	Abazov, M, et al. (författare) Measurement of gamma + b + X and gamma + c + X Production Cross Sections in pp > Collisions at s=1.96 TeV 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:19, s. 192002- Tidskriftsartikel (refereegranskat)abstract First measurements of the differential cross sections d(3)sigma/(dp(T)(gamma)dy(gamma)dy(jet)) for the inclusive production of a photon in association with a heavy quark (b, c) jet are presented, covering photon transverse momenta 30 < p(T)(gamma)< 150 GeV, photon rapidities \|y(gamma)\|< 1.0, jet rapidities \|y(jet)\|< 0.8, and jet transverse momenta p(T)(jet)> 15 GeV. The results are based on an integrated luminosity of 1 fb(-1) in pp collisions at s=1.96 TeV recorded with the D0 detector at the Fermilab Tevatron Collider. The results are compared with next-to-leading order perturbative QCD predictions.
29.	Abazov, M, et al. (författare) Measurement of the t(t)over-bar production cross section and top quark mass extraction using dilepton events in p(p)over-bar collisions 2009 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 679:3, s. 177-185 Tidskriftsartikel (refereegranskat)abstract We present a measurement of the top quark pair production cross section in p (p) over bar collisions at root s = 1.96 TeV using approximately 1 fb(-1) collected with the DO detector. We consider decay channels containing two high p(T) charged leptons where one lepton is identified as an electron or a muon while the other lepton can be an electron, a muon or a hadronically decaying tau lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5(-1.0)(+1.0)(stat)(-0.6)(+0.7)(syst)(-0.5)(+0.6)(lumi) pb. Using l tau events only, we measure: sigma(t (t) over bar) x B(t (t) over bar -> l tau b (b) over bar) = 0.13(-0.08)(+0.09)(stat)(-0.06)(+0.06)(syst)(-0.02)(+0.02)(lumi) pb. Comparing the measured cross section as a function of the mass of the top quark with a partial next-to-next-to leading order Quantum Chroniodynamics theoretical prediction, we extract a mass of the top quark of 171.5(-8.8)(+9-9) GeV, in agreement with direct measurements.
30.	Abazov, M, et al. (författare) Search for admixture of scalar top quarks in the t(t)over-bar lepton + jets final state at root s=1.96 TeV 2009 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 674:1, s. 4-10 Tidskriftsartikel (refereegranskat)abstract A search for pair production of the lightest supersymmetric partner of the top quark, (t) over tilde (1), is performed in the lepton + jets channel using 0.9 fb(-1) of data collected by the D circle divide experiment. Kinematic differences between (t) over tilde (1)(t) over tilde (1) and the dominant top quark pair production background are used to separate the two processes. First limits from Run II of the Fermilab Tevatron Collider for the scalar top quark decaying to a chargino and a b quark ((t) over tilde1 -> (chi) over tilde (+)(1)b) are obtained for scalar top quark masses of 130-190 GeV and chargino masses of 90-150 GeV.
31.	Abazov, M, et al. (författare) Search for associated production of charginos and neutralinos in the trilepton final state using 2.3 fb(-1) of data 2009 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 680:1, s. 34-43 Tidskriftsartikel (refereegranskat)abstract We report the results of a search for associated production of charginos and neutralinos using a data set corresponding to an integrated luminosity of 2.3 fb(-1) collected with the Demptyset experiment during Run II of the Tevatron proton-antiproton collider. Final states containing three charged leptons and missing transverse energy are probed for a signal from supersymmetry with four dedicated trilepton event selections. No evidence for a signal is observed, and we set limits on the product of production cross section and leptonic branching fraction. Within minimal supergravity, these limits translate into bounds on m(0) and m(1/2) that are well beyond existing limits.
32.	Abazov, M, et al. (författare) Search for Resonant Diphoton Production with the D0 Detector 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:23, s. 231801- Tidskriftsartikel (refereegranskat)abstract We present a search for a narrow resonance in the inclusive diphoton final state using similar to 2.7 fb(-1) of data collected with the D0 detector at the Fermilab Tevatron p (p) over bar Collider. We observe good agreement between the data and the background prediction, and set the first 95% C. L. upper limits on the production cross section times the branching ratio for decay into a pair of photons for resonance masses between 100 and 150 GeV. This search is also interpreted in the context of several models of electroweak symmetry breaking with a Higgs boson decaying into two photons.
33.	Abazov, V. M., et al. (författare) b-Jet identification in the D0 experiment 2010 Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 620:2-3, s. 490-517 Tidskriftsartikel (refereegranskat)abstract Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron p (p) over bar collider. This article describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.
34.	Abazov, V. M., et al. (författare) Determination of the Width of the Top Quark 2011 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:2, s. 022001- Tidskriftsartikel (refereegranskat)abstract We extract the total width of the top quark, Gamma(t), from the partial decay width Gamma(t -> Wb) measured using the t-channel cross section for single top-quark production and from the branching fraction B(t -> Wb) measured in t (t) over bar t events using up to 2.3 fb(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron p (p) over bar Collider. The result is Gamma(t) = 1.99(-0.55)(+0.69) GeV, which translates to a top-quark lifetime of tau(t) = (3.3-(+1.3)(0.9)) x 10(-25) s. Assuming a high mass fourth generation b' quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on vertical bar V-tb'vertical bar < 0.63 at 95% C.L.
35.	Abazov, V. M., et al. (författare) Evidence for an anomalous like-sign dimuon charge asymmetry 2010 Ingår i: Physical Review D. - 1550-7998. ; 82:13, s. 032001- Tidskriftsartikel (refereegranskat)abstract We measure the charge asymmetry A of like-sign dimuon events in 6.1 fb(-1) of p (p) over bar collisions recorded with the D0 detector at a center-of-mass energy root s = 1.96 TeV at the Fermilab Tevatron collider. From A, we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.00957 +/- 0.00251 (stat) +/- 0.00146 (syst). This result differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(0.6)(+0.5)) x 10(-4) and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
36.	Abazov, V. M., et al. (författare) Evidence for an Anomalous Like-Sign Dimuon Charge Asymmetry 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:8, s. 081801- Tidskriftsartikel (refereegranskat)abstract We measure the charge asymmetry A =(N++ -N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb(-1) of p (p) over bar collisions recorded with the D0 detector at a center-of-mass energy root s = 1: 96 TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 +/- 0.00251(stat) +/- 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) x 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
37.	Abazov, V. M., et al. (författare) High mass exclusive diffractive dijet 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. ; 705:3, s. 193-199 Tidskriftsartikel (refereegranskat)abstract We present evidence for diffractive exclusive dijet production with an invariant dijet mass greater than 100 GeV in data collected with the DO experiment at the Fermilab Tevatron Collider. A discriminant based on calorimeter information is used to measure a significant number of events with little energy (typically less than 10 GeV) outside the dijet system, consistent with the diffractive exclusive dijet production topology. The probability for these events to be explained by other dijet production processes is 2 x 10(-6), corresponding to a 4.7 standard deviation significance.
38.	Abazov, V. M., et al. (författare) Measurement of direct photon pair production cross sections in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:2, s. 108-117 Tidskriftsartikel (refereegranskat)abstract We present a measurement of direct photon pair production cross sections using 4.2 fb(-1) of data collected with the DO detector at the Fermilab Tevatron p (p) over bar Collider. We measure single differential cross sections as a function of the diphoton mass, the transverse momentum of the diphoton system, the azimuthal angle between the photons, and the polar scattering angle of the photons. In addition, we measure double differential cross sections considering the last three kinematic variables in three diphoton mass bins. The results are compared with different perturbative QCD predictions and event generators. (C) 2010 Elsevier B.V. All rights reserved.
39.	Abazov, V. M., et al. (författare) Measurement of t(t)over-bar production in the tau plus jets topology using p(p)over-bar collisions root s=1.96 TeV 2010 Ingår i: PHYS REV D. - 1550-7998. ; 82:7, s. 071102- Tidskriftsartikel (refereegranskat)abstract We present a measurement of the t (t) over bar production cross section multiplied by the branching ratio to tau lepton decaying semihadronically (tau(h)) plus jets, sigma(p (p) over bar -> t (t) over bar + X) center dot BR(t (t) over bar -> tau(h) + jets), at a center of mass energy root s = 1.96 TeV using 1 fb(-1) of integrated luminosity collected with the D0 detector. Assuming a top quark mass of 170 GeV, we measure sigma(t (t) over bar) center dot BR tau h (+ j) = 0.60(-0.22)(+0.23)(stat)(-0.14)(+0.15)(syst) +/- 0.04(lumi) pb. In addition, we extract the t (t) over bar production cross section using the t (t) over bar -> tau(h) + jets topology, with the result sigma(t (t) over bar) = 6.9(-1.2)(+1.2)(stat)(-0.7)(+0.8)(syst) +/- 0.4(lumi) pb. These findings are in good agreement with standard model predictions and measurements performed using other top quark decay channels.
40.	Abazov, V. M., et al. (författare) Measurement of the dijet invariant mass cross section in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 531-538 Tidskriftsartikel (refereegranskat)abstract The inclusive dijet production double differential cross section as a function of the dijet invariant mass and of the largest absolute rapidity of the two jets with the largest transverse momentum in an event is measured in p (p) over bar collisions at root s = 1.96 TeV using 0.7 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The measurement is performed in six rapidity regions up to a maximum rapidity of 2.4. Next-to-leading order perturbative QCD predictions are found to be in agreement with the data. (C) 2010 Elsevier B.V. All rights reserved.
41.	Abazov, V. M., et al. (författare) Measurement of the normalized Z/gamma* -> mu(+)mu(-) transverse momentum distribution in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 522-530 Tidskriftsartikel (refereegranskat)abstract We present a new measurement of the Z/gamma* transverse momentum distribution in the range 0-330 GeV, in proton-antiproton collisions at root s = 1.96 TeV. The measurement uses 0.97 fb(-1) of integrated luminosity recorded by the D0 experiment and is the first using the Z/gamma* -> mu(+)mu(-) + X channel at this center-of-mass energy. This is also the first measurement of the Z/gamma* transverse momentum distribution that presents the result at the level of particles entering the detector, minimizing dependence on theoretical models. As any momentum of the Z/gamma* in the plane transverse to the incoming beams must be balanced by some recoiling system, primarily the result of QCD radiation in the initial state, this variable is an excellent probe of the underlying process. Tests of the predictions of QCD calculations and current event generators show they have varied success in describing the data. Using this measurement as an input to theoretical predictions will allow for a better description of hadron collider data and hence it will increase experimental sensitivity to rare signals. (C) 2010 Elsevier B.V. All rights reserved.
42.	Abazov, V. M., et al. (författare) Measurement of the WZ -> lvll cross section and limits on anomalous triple gauge couplings in p(p)over-bar collisions at root s=1.96 TeV 2011 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 695:1-4, s. 67-73 Tidskriftsartikel (refereegranskat)abstract We present a new measurement of the WZ -> lvll (l = e, mu) cross section and limits on anomalous triple gauge couplings. Using 4.1 fb(-1) of integrated luminosity of p (p) over bar collisions at root s = 1.96 TeV, we observe 34 WZ candidate events with an estimated background of 6.0 +/- 0.4 events. We measure the WZ production cross section to be 3.89(-0.90)(+1.07) pb, in good agreement with the standard model prediction. We find no evidence for anomalous WWZ couplings and set 95% C.L. limits on the coupling parameters, -0.077 < lambda(z) < 0.093 and -0.029 < Delta kappa(z) < 0.080 in the HISZ parameterization for a Lambda = 2 TeV form factor scale. These are the best limits to date obtained from the direct measurement of the WWZ vertex.
43.	Abazov, V. M., et al. (författare) Precise Study of the Z/gamma* Boson Transverse Momentum Distribution in p(p)over-bar Collisions Using a Novel Technique 2011 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:12, s. 122001- Tidskriftsartikel (refereegranskat)abstract Using 7.3 fb(-1) of p (p) over bar collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable phi(eta), which probes the same physical effects as the Z/gamma boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the phi(eta)* distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.
44.	Abazov, V. M., et al. (författare) Search for flavor changing neutral currents via quark-gluon couplings in single top quark production using 2.3 fb(-1) of p(p)over-bar collisions 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:2, s. 81-87 Tidskriftsartikel (refereegranskat)abstract We present a search for flavor changing neutral currents via quark-gluon couplings in a sample of single top quark final states corresponding to 2.3 fb(-1) of integrated luminosity collected with the DO detector at the Fermilab Tevatron Collider. We select events containing a single top quark candidates with an additional jet, and obtain separation between signal and background using Bayesian neural networks. We find consistency between background expectation and observed data, and set limits on flavor changing neutral current gluon couplings of the top quark to up quarks (tgu) and charm quarks (tgc). The cross section limits at the 95% C.L. are sigma(tgu) < 0.20 pb and sigma(tgc) < 0.27 pb. These correspond to limits on the top quark decay branching fractions of B(t -> gu) < 2.0 x 10(-4) and B(t -> gc) < 3.9 x 10(-3).
45.	Abazov, V. M., et al. (författare) Search for pair production of the scalar top quark in the electron plus muon final state 2011 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 696:4, s. 321-327 Tidskriftsartikel (refereegranskat)abstract We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ((t) over tilde (1)) in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb(-1). The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ((nu) over bar). and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and substantially improved exclusion limits at the 95% C.L. are set in the the (M-(t) over tilde1, M-(nu) over tilde mass plane.
46.	Abazov, V. M., et al. (författare) Search for Randall-Sundrum Gravitons in the Dielectron and Diphoton Final States with 5.4 fb(-1) of Data from p(p)over-bar Collisions at root s=1.96 TeV 2010 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:24, s. 241802- Tidskriftsartikel (refereegranskat)abstract Using 5: 4 fb(-1) of integrated luminosity from p (p) over bar collisions at root s = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider, we search for decays of the lightest Kaluza-Klein mode of the graviton in the Randall-Sundrum model to ee and gamma gamma. We set 95% C. L. lower limits on the mass of the lightest graviton between 560 and 1050 GeV for values of the coupling k/(M) over bar (P1) between 0.01 and 0.1.
47.	Abazov, V. M., et al. (författare) Search for scalar bottom quarks and third-generation leptoquarks in p(p)over-bar collisions at root s=1.96 TeV 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:2, s. 95-101 Tidskriftsartikel (refereegranskat)abstract We report the results of a search for pair production of scalar bottom quarks ((b) over bar (1)) and scalar third-generation leptoquarks (LQ(3)) in 5.2 fb(-1) of p (p) over bar collisions at the D0 experiment of the Fermilab Tevatron Collider. Scalar bottom quarks are assumed to decay to a neutralino ((chi) over bar (1)(0)) and a b quark, and we set 95% C.L. lower limits on their production in the (m((b) over bar1), m((chi) over bar 10)) mass plane such as m((b) over bar1) > 247 GeV for m(<(chi)over) (bar>10) = 0 and m((chi) over bar 10) > 110 GeV for 160 m(<(b) over bar1) < 200 GeV. The leptoquarks are assumed to decay to a tau neutrino and a b quark, and we set a 95% C.L. lower limit of 247 GeV on the mass of a charge-1/3 third-generation scalar leptoquark.
48.	Abazov, V. M., et al. (författare) Search for the rare decay B-s(0) -> mu(+)mu(-) 2010 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 539-544 Tidskriftsartikel (refereegranskat)abstract We present the results of a search for the flavor changing neutral current decay B-s(0) -> mu(+)mu(-) using 6.1 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. The observed number of B-s(0) candidates is consistent with background expectations. The resulting upper limit on the branching fraction is B(B-s(0) -> mu(+)mu(-)) < 5.1 x 10(-8) at the 95% C.L. This limit is a factor of 2.4 better than that of the previous DO analysis and the best limit to date. Published by Elsevier B.V.
49.	Abazov, M, et al. (författare) Evidence of WW and WZ Production with lepton plus jets Final States in pp Collisions at root s=1.96 TeV 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:16, s. 161801- Tidskriftsartikel (refereegranskat)abstract We present first evidence for WW+WZ production in lepton+jets final states at a hadron collider. The data correspond to 1.07 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is < 5.4x10(-6), which corresponds to a significance of 4.4 standard deviations.
50.	Abazov, M, et al. (författare) Measurement of the Z gamma -> nu(nu)over-bar gamma Production Cross Section and Limits on Anomalous ZZ gamma and Z gamma gamma Couplings in p(p)over-bar Collisions at root s=1.96 TeV 2009 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:20, s. 201802- Tidskriftsartikel (refereegranskat)abstract We present the first observation of the Z gamma -> nu(nu) over bar gamma process at the Fermilab Tevatron at 5.1 standard deviations significance, based on 3.6 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. The measured Z gamma production cross section multiplied by the branching fraction of Z -> nu(nu) over bar is 32 +/- 9(stat + syst) +/- 2(lumi) fb for the photon E-T > 90 GeV. It is in agreement with the standard model prediction of 39 +/- 4 fb. We set limits on anomalous trilinear Z gamma gamma and ZZ gamma gauge boson couplings, most of which are the most restrictive to date.

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