1. |
- Abazov, V. M., et al.
(author)
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The upgraded DO detector
- 2006
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In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
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Journal article (peer-reviewed)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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2. |
- Abazov, V. M., et al.
(author)
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A combined search for the standard model Higgs boson at root S=1.96 TeV
- 2008
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 663:1-2, s. 26-36
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Journal article (peer-reviewed)abstract
- We present new results of the search for WH --> lvb (b) over bar production in p (p) over bar collisions at a center-of-mass energy of root S = 1.96 TeV, based on a dataset with integrated luminosity of 0.44 fb(-1). We combine these new results with previously published searches by the DO collaboration, for WH and ZH production analyzed in the E(T)b (b) over bar final state, for ZH (--> l(+)l(-)b (b) over bar) production, for WH (-->. WWW) production, and for H (--> W W) direct production. No signal-like excess is observed either in the W H analysis or in the combination of all D0 Higgs boson analyses. We set 95% C.L. (expected) upper limits on sigma(p (p) over bar --> WH) x B(H --> b (b) over bar) ranging from 1.6 (2.2) ph to 1.9 (3.3) pb for Higgs boson masses between 105 and 145 GeV, to be compared to the theoretical prediction of 0.13 pb for a Standard Model (SM) Higgs boson with mass in m(H) = 115 GeV. After combination with the other DO Higgs boson searches, we obtain for in H = 115 GeV an observed (expected) limit 8.5 (12.1) times higher than the SM predicted Higgs boson production cross section. For m(H) = 160 GeV, the corresponding observed (expected) ratio is 10.2 (9.0).
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3. |
- Abazov, V. M., et al.
(author)
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Combined D0 measurements constraining the CP-violating phase and width difference in the B-s(0) system
- 2007
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In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; 76:5, s. 057101-
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Journal article (peer-reviewed)abstract
- We combine the D0 measurement of the width difference between the light and heavy B-s(0) mass eigenstates and of the CP-violating mixing phase determined from the time-dependent angular distributions in the B-s(0)-> J/psi phi decays along with the charge asymmetry in semileptonic decays also measured with the D0 detector. With the additional constraint from the world average of the flavor-specific B-s(0) lifetime, we obtain Delta Gamma(s)equivalent to(Gamma(L)-Gamma(H))=0.13 +/- 0.09 ps(-1) and vertical bar phi(s)vertical bar=0.70(-0.47)(+0.39) or Delta Gamma(s)=-0.13 +/- 0.09 ps(-1) and vertical bar phi(s)vertical bar=2.44(-0.39)(+0.47). The data sample corresponds to an integrated luminosity of 1.1 fb(-1) accumulated with the D0 detector at the Fermilab Tevatron Collider.
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4. |
- Abazov, V. M., et al.
(author)
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Direct observation of the strange b baryon Xi(-)(b)
- 2007
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:5, s. 052001-
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Journal article (peer-reviewed)abstract
- We report the first direct observation of the strange b baryon Xi(-)(b)(Xi) over bar (+)(b)). We reconstruct the decay Xi(-)(b)-->J/psi Xi(-), with J/psi-->mu(+)mu(-), and Xi(-)-->Lambda pi(-)-->p pi(-)pi(-) in p (p) over bar collisions at root s = 1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(-)(b) candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psi Lambda, we measure the relative rate sigma(Xi(-)(b))xB(Xi(-)(b)-->J/psi Xi)/ sigma(Lambda(b))xB(Lambda(b)-->J/psi Lambda) = 0.28 +/- 0.09(stat)(-0.08)(+0.09)(syst).
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5. |
- Abazov, V. M., et al.
(author)
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Measurement of the forward-backward charge asymmetry in top-quark pair production
- 2008
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100:14:100, s. 142002-
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Journal article (peer-reviewed)abstract
- We present the first measurement of the integrated forward-backward charge asymmetry in top-quark-top-antiquark pair (t (t) over bar) production in proton-antiproton (p (p) over bar) collisions in the lepton+jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming t (t) over bar +X production and decay, a sample of 0.9 fb(-1) of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on t (t) over bar +X production via a Z' resonance.
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6. |
- Abazov, V. M., et al.
(author)
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Measurement of the isolated photon cross section in p(p)over-bar collisions at root s=1.96 TeV
- 2006
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 639:3-4, s. 151-158
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Journal article (peer-reviewed)abstract
- The cross section for the inclusive production of isolated photons has been measured in p (p) over bar collisions at root s = 1.96 TeV with the DO detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity vertical bar n vertical bar < 0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.
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7. |
- Abazov, V. M., et al.
(author)
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Measurement of the Lambda(0)(b) lifetime using semileptonic decays
- 2007
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:18, s. 182001-
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Journal article (peer-reviewed)abstract
- We report a measurement of the Lambda(0)(b) lifetime using a sample corresponding to 1.3 fb(-1) of data collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. The Lambda(0)(b) baryon is reconstructed via the decay Lambda(0)(b)->mu(nu) over bar Lambda X-+(c). Using 4437 +/- 329 signal candidates, we measure the Lambda(0)(b) lifetime to be tau(Lambda(0)(b))=1.290(-0.110)(+0.119)(stat)(-0.091)(+0.087)(syst) ps, which is among the most precise measurements in semileptonic Lambda(0)(b) decays. This result is in good agreement with the world average value.
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8. |
- Abazov, V. M., et al.
(author)
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Measurement of the Lambda(b) lifetime in the exclusive decay Lambda(b)-> J/psi Lambda
- 2007
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:14, s. 142001-
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Journal article (peer-reviewed)abstract
- We have measured the Lambda(b) lifetime using the exclusive decay Lambda(b)-> J/psi Lambda, based on 1.2 fb(-1) of data collected with the D0 detector during 2002-2006. From 171 reconstructed Lambda(b) decays, where the J/psi and Lambda are identified via the decays J/psi ->mu(+)mu(-) and Lambda -> p pi, we measured the Lambda(b) lifetime to be tau(Lambda(b))=1.218(-0.115)(+0.130)(stat)+/- 0.042(syst) ps. We also measured the B-0 lifetime in the decay B-0 -> J/psi(mu(+)mu(-))K-S(0)(pi(+)pi(-)) to be tau(B-0)=1.501(-0.074)(+0.078)(stat)+/- 0.050(syst) ps, yielding a lifetime ratio of tau(Lambda(b))/tau(B-0)=0.811(-0.087)(+0.096)(stat)+/- 0.034(syst).
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9. |
- Abazov, V. M., et al.
(author)
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Measurement of the muon charge asymmetry from W boson decays
- 2008
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In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-7998. ; D:77, s. 011106-
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Journal article (peer-reviewed)abstract
- We present a measurement of the muon charge asymmetry from W boson decays using 0.3 fb(-1) of data collected at root s =1.96 GeV between 2002 and 2004 with the D0 detector at the Fermilab Tevatron (p) over bar Collider. We compare our findings with expectations from next-to-leading-order calculations performed using the CTEQ6.1M and MRST04 NLO parton distribution functions. Our findings can be used to constrain future parton distribution function fits.
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10. |
- Abazov, V. M., et al.
(author)
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Measurement of the p(p)over-bar -> WZ+X cross section at root s=1.96 TeV and limits on WWZ trilinear gauge couplings
- 2007
-
In: Physical Review D. - 1550-7998 .- 1550-2368. ; 76:11
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Journal article (peer-reviewed)abstract
- We present measurements of the process p (P) over bar -> WZ + X -> l 'nu(l ')l (l) over bar at root s = 1:96 TeV,where l and l ' are electrons or muons. Using 1 fb(-1) of data from the D0 experiment, we observe 13 candidates with an expected background of 4.5 +/- 0.6 events and measure a cross section sigma(WZ) = 2.7(-1.3)(+1.7) pb. From the number of observed events and the Z boson transverse momentum distribution, we limit the trilinear WWZ gauge couplings to -0: 17 <= lambda(Z) <= 0.21 (Delta k(Z) <= 0.29(lambda(Z) = 0) at the 95% C.L. for a form factor scale Lambda = 2 TeV. Further, assuming that Delta g(1)(Z) = Delta k(Z), we find -0.12 <= Delta k(Z) <= 0.29(lambda(Z) = 0) at the 95% C. L. These are the most restrictive limits on the WWZ couplings available to date.
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