SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Strom Sara S.) srt2:(2006-2009)"

Sökning: WFRF:(Strom Sara S.) > (2006-2009)

  • Resultat 1-10 av 22
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Abazov, V. M., et al. (författare)
  • Study of the decay B-s(0)->(DsDs(*))-D-(*)
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:24
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a study of the decay B-s(0)->(DsDs(*))-D-(*) using a data sample corresponding to 1.3 fb(-1) of integrated luminosity collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. One D-s((*)) meson was partially reconstructed in the decay D-s ->phi mu nu, and the other D-s((*)) meson was identified using the decay D-s ->phi pi where no attempt was made to distinguish D-s and D-s(*) states. For the branching fraction Br(B-s(0)->(DsDs(*))-D-(*)) we obtain a 90% C.L. range [0.002,0.080] and central value 0.039(-0.017)(+0.019)(stat)(-0.015)(+0.016)(syst). This was subsequently used to make the most precise estimate of the width difference Delta Gamma(CP)(s) in the B-s(0)-(B)over bar(s)(0) system: Delta Gamma(CP)(s)/Gamma(s)=0.079(-0.035)(+0.038)(stat)(-0.030)(+0.031)(syst).
  •  
2.
  • Abazov, V. M., et al. (författare)
  • Evidence for production of single top quarks and first direct measurement of vertical bar V-tb vertical bar
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:18, s. 181802-
  • Tidskriftsartikel (refereegranskat)abstract
    • The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron < p(p)over bar > collider. Using a 0.9 fb(-1) dataset, we apply a multivariate analysis to separate signal from background and measure sigma(< p(p)over bar >-> tb+X,tqb+X)=4.9 +/- 1.4 pb. The probability to measure a cross section at this value or higher in the absence of a signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the Cabibbo-Kobayashi-Maskawa matrix element that describes the Wtb coupling and find 0.68 <= 1 at 95% C.L. within the standard model.
  •  
3.
  • Abazov, V. M., et al. (författare)
  • Search for single production of scalar leptoquarks in p(p)over-bar collisions decaying into muons and quarks with the D0 detector
  • 2007
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 647:2-3, s. 74-81
  • Tidskriftsartikel (refereegranskat)abstract
    • lWe report on a search for second generation leptoquarks (LQ(2)) which decay into a muon plus quark in (p) over barp collisions at a center-of-mass energy of root s = 1.96 TeV in the DO detector using an integrated luminosity of about 300 pb(-1). No evidence for a leptoquark signal is observed and an upper bound on the product of the cross section for single leptoquark production times branching fraction into a quark and a muon was determined for second generation scalar leptoquaiks as a function of the leptoquark mass. This result has been combined with a previously published DO search for leptoquark pair production to obtain leptoquark mass limits as a function of the leptoquark-muon-quark coupling, lambda. Assuming lambda = 1, lower limits on the mass of a second generation scalar leptoquark coupling to a u quark and a muon are m(LQ2) > 274 GeV and m(LQ2) > 226 GeV for beta = 1 and beta = 1/2, respectively.
  •  
4.
  • Abazov, V. M., et al. (författare)
  • Search for techniparticles in e plus jets events at D0
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:22, s. 221801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We search for the technicolor process p(p) over bar ->rho(T)/omega(T)-> W pi(T) in events containing one electron and two jets, in data corresponding to an integrated luminosity of 390 pb(-1), recorded by the D0 experiment at the Fermilab Tevatron. Technicolor predicts that technipions pi(T) decay dominantly into b(b) over bar, b(c) over bar, or (b) over barc, depending on their charge. In these events b and c quarks are identified by their secondary decay vertices within jets. Two analysis methods based on topological variables are presented. Since no excess above the standard model prediction was found, the result is presented as an exclusion in the pi(T) vs rho(T) mass plane for a given set of model parameters.
  •  
5.
  • Abazov, V. M., et al. (författare)
  • Experimental discrimination between charge 2e/3 top quark and charge 4e/3 exotic quark production scenarios
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:4, s. 041801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first experimental discrimination between the 2e/3 and 4e/3 top quark electric charge scenarios, using top quark pairs (t (t) over bar) produced in p (p) over bar collisions at root s =1.96 TeV by the Fermilab Tevatron Collider. We use 370 pb(-1) of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and (b) over bar -quark jets by using the charge and momenta of tracks within the jet cones. The data are consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs Q (Q) over bar with |q|=4e/3. We place an upper limit on the fraction of Q (Q) over bar pairs rho < 0.80 at the 90% C.L.
  •  
6.
  • Abazov, V. M., et al. (författare)
  • Lifetime difference and CP-violating phase in the B-s(0) system
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:12, s. 121801-
  • Tidskriftsartikel (refereegranskat)abstract
    • From an analysis of the decay B-s(0)-> J/psi phi, we obtain the width difference between the light and heavy mass eigenstates Delta Gamma equivalent to(Gamma(L)-Gamma(H))=0.17 +/- 0.09(stat)+/- 0.02(syst) ps(-1) and the CP-violating phase phi(s)=-0.79 +/- 0.56(stat)(-0.01)(+0.14)(syst). Under the hypothesis of no CP violation (phi(s)equivalent to 0), we obtain 1/Gamma=tau/(B-s(0))=1.52 +/- 0.08(stat)(-0.03)(+0.01)(syst) ps and Delta Gamma=0.12(-0.10)(+0.08)(stat)+/- 0.02(syst) ps(-1). The data sample corresponds to an integrated luminosity of about 1.1 fb(-1) accumulated with the D0 detector at the Fermilab Tevatron collider. This is the first direct measurement of the CP-violating mixing phase in the B-s(0) system.
  •  
7.
  • Abazov, V. M., et al. (författare)
  • Measurement of the charge asymmetry in semileptonic B-s(0) decays
  • 2007
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 98:15, s. 151801-
  • Tidskriftsartikel (refereegranskat)abstract
    • We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic B-s(0) decays A(SL)(s,unt) by comparing the decay rate of B-s(0) -> mu(+) D-s(-) nu X, where D-s(-) -> phi pi(-) and phi -> K+K-, with the charge-conjugate (B) over bar (0)(s) decay rate. This sample was selected from 1: 3 fb(-1) of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain A(SL)(s,unt) = [1.23 +/- 0.97(stat) +/- 0.17(syst)] x 10(-2). Assuming that Delta m(s)/(Gamma) over bar (s) >> 1, this result can be translated into a measurement of the CP-violating phase in B-s(0) mixing: Delta Gamma(s)/Delta m(s) tan phi(s) = [2.45 +/- 1.93(stat) +/- 0.35(syst)] x 10(-2).
  •  
8.
  • Abazov, V. M., et al. (författare)
  • Model-independent measurement of the W-boson helicity in top-quark decays at D0
  • 2008
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100:6
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb(-1) sample of candidate t (t) over bar events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron p (p) over bar Collider. We reconstruct the angle theta(*) between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos theta(*) distribution finds that the fraction of longitudinal W bosons f(0)=0.425 +/- 0.166(stat)+/- 0.102(syst) and the fraction of right-handed W bosons f(+)=0.119 +/- 0.090(stat)+/- 0.053(syst), which is consistent at the 30% C.L. with the standard model.
  •  
9.
  • Abazov, V. M., et al. (författare)
  • Measurement of the Lifetime of the B-c(+/-) Meson in the Semileptonic Decay Channel
  • 2009
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:9, s. 092001-
  • Tidskriftsartikel (refereegranskat)abstract
    • Using approximately 1.3 fb(-1) of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the B-c(+/-) meson in the B-c(+/-)-> J/psi mu(+/-)+X final state. A simultaneous unbinned likelihood fit to the J/psi+mu invariant mass and lifetime distributions yields a signal of 881 +/- 80(stat) candidates and a lifetime measurement of tau(B-c(+/-))=0.448(-0.036)(+0.038)(stat)+/- 0.032(syst) ps.
  •  
10.
  • 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.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 22

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy