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Bs0lifetime measurement in theCP-odd decay channelBs0→J/ψ f0(980)
Abazov, V. M.,Abbott, B.,Acharya, B. S.,Adams, M.,Adams, T.,Agnew, J. P.,Alexeev, G. D.,Alkhazov, G.,Alton, A.,Askew, A.,Atkins, S.,Augsten, K.,Aushev, V.,Aushev, Y.,Avila, C.,Badaud, F.,Bagby, L.,Bal American Physical Society 2016 Physical Review D Vol.94 No.1
<P>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).</P>
Abazov, V.M.,Abbott, B.,Acharya, B.S.,Adams, M.,Adams, T.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Aoki, M.,Askew, A.,Atkins, S.,Augsten, K.,Avila, C.,Badaud, F.,Bagby, L.,Baldin, B.,Bandurin Elsevier 2012 Physics letters: B Vol.714 No.1
<P><B>Abstract</B></P><P>We present measurements of the differential cross section dσ/dpTγ for the inclusive production of a photon in association with a <I>b</I>-quark jet for photons with rapidities |<SUP>yγ</SUP>|<1.0 and 30<pTγ<300?GeV, as well as for photons with 1.5<|<SUP>yγ</SUP>|<2.5 and 30<pTγ<200?GeV, where pTγ is the photon transverse momentum. The <I>b</I>-quark jets are required to have <SUB>pT</SUB>>15 GeV and rapidity |<SUP>yjet</SUP>|<1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb<SUP>−1</SUP>, recorded with the D0 detector at the Fermilab Tevatron pp¯ Collider at 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 <SUB>kT</SUB>-factorization QCD approach, and those from the <SMALL>SHERPA</SMALL> and <SMALL>PYTHIA</SMALL> Monte Carlo event generators.</P>
Study of the X±(5568) state with semileptonic decays of the Bs0 meson
Abazov, V. M.,Abbott, B.,Acharya, B. S.,Adams, M.,Adams, T.,Agnew, J. P.,Alexeev, G. D.,Alkhazov, G.,Alton, A.,Askew, A.,Atkins, S.,Augsten, K.,Aushev, V.,Aushev, Y.,Avila, C.,Badaud, F.,Bagby, L.,Bal American Physical Society 2018 Physical Review D Vol.97 No.9
<P>We present a study of the X-+/-(5568) using semileptonic decays of the B-s(0) meson using the full run II integrated luminosity of 10.4 fb(-1) in proton-antiproton collisions at a center of mass energy of 1.96 TeV collected with the DO detector at the Fermilab Tevatron Collider. We report evidence for a narrow structure, X-+/-(5568), in the decay sequence X-+/-(5568) -> B-s(0) pi(+/-) where B-s(0)-> mu(-/+) (DsX)-X-+/-, D-s(+/-)-> phi pi(+/-)which is consistent with the previous measurement by the DO Collaboration in the hadronic decay mode, X-+/-(5568) -> B-s(0)pi(+/-) where B-s(0 )-> J/psi phi. The mass and width of this state are measured using a combined fit of the hadronic and semileptonic data, yielding m = 5566.9(-3.1)(+3.2)(stat)(-1.2)(+0.6)(syst) MeV/c(2), Gamma = 18.6(-6.1)(+7.9)(stat)(-3.8)(+3.5) (syst) McV/c(2) with a significance of 6.7 sigma.</P>
Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Ancu, L.S.,Andeen, T.,Anzelc, M.S.,Aoki, M.,Arn Elsevier 2009 Physics letters: B Vol.680 No.1
<P><B>Abstract</B></P><P>A search for supersymmetric partners of quarks is performed in the topology of multijet events accompanied by at least one tau lepton decaying hadronically and large missing transverse energy. Approximately 1 fb<SUP>−1</SUP> of pp¯ collision data from the Fermilab Tevatron Collider at a center of mass energy of 1.96 TeV recorded by the DØ detector is analyzed. Results are combined with the previously published DØ inclusive search for squarks and gluinos. No evidence of physics beyond the Standard Model is found and lower limits on the squark mass up to 410 GeV are derived in the framework of minimal supergravity with tanβ=15, <SUB>A0</SUB>=−2<SUB>m0</SUB> and μ<0, in the region where decays to tau leptons dominate. Gaugino masses <SUB>m1/2</SUB> are excluded up to 172 GeV.</P>
Search for pair production of first-generation leptoquarks in pp¯ collisions at s=1.96 TeV
Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Ancu, L.S.,Andeen, T.,Anzelc, M.S.,Aoki, M.,Arn Elsevier 2009 Physics letters: B Vol.681 No.3
<P><B>Abstract</B></P><P>A search for pair production of first-generation leptoquarks (<I>LQ</I>) is performed with data collected by the DØ experiment in pp¯ collisions at s=1.96 TeV at the Fermilab Tevatron Collider. In a sample of data corresponding to ∼1<SUP> fb−1</SUP> the search has been performed on the final states with two electrons and two jets or one electron, two jets and missing transverse energy. We find our data consistent with standard model expectations. The results are combined with those found in a previous analysis of events with two jets and missing transverse energy to obtain scalar <I>LQ</I> mass limits. We set 95% C.L. lower limits on a scalar <I>LQ</I> mass of 299 GeV, 284 GeV and 216 GeV for β=1, β=0.5 and β=0.02 respectively, where <I>β</I> is the <I>LQ</I> branching ratio in the <I>eq</I> channel. This improves the results obtained with a lower luminosity sample from Run II of the Tevatron. Lower limits on vector <I>LQ</I> masses with different couplings from 357 GeV to 464 GeV for β=0.5 are also set using this analysis.</P>
Search for supersymmetry in di-photon final states at s=1.96 TeV
Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahn, S.H.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Anastasoaie, M.,Ancu, L.S.,Andeen, T. Elsevier 2008 Physics letters: B Vol.659 No.5
<P><B>Abstract</B></P><P>We report results of a search for supersymmetry (SUSY) with gauge-mediated symmetry breaking in di-photon events collected by the D0 experiment at the Fermilab Tevatron Collider in 2002–2006. In 1.1 fb<SUP>−1</SUP> of data, we find no significant excess beyond the background expected from the standard model and set the most stringent lower limits to date for a standard benchmark model on the lightest neutralino and chargino masses of 125 GeV and 229 GeV, respectively, at 95% confidence.</P>
DO Collaboration,Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Anastasoaie, M.,Ancu, L.S.,And North-Holland Pub. Co 2009 Physics letters: B Vol.679 No.3
We present a measurement of the top quark pair production cross section in pp@? collisions at s=1.96 TeV using approximately 1 fb<SUP>-1</SUP> collected with the DO detector. We consider decay channels containing two high p<SUB>T</SUB> 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 τ lepton. For a mass of the top quark of 170 GeV, the measured cross section is 7.5<SUB>-1.0</SUB><SUP>+1.0</SUP>(stat)<SUB>-0.6</SUB><SUP>+0.7</SUP>(syst)<SUB>-0.5</SUB><SUP>+0.6</SUP>(lumi) pb. Using @?τ events only, we measure: σ<SUB>tt@</SUB>?xB(tt@?->@?τbb@?)=0.13<SUB>-0.08</SUB><SUP>+0.09</SUP>(stat)<SUB>-0.06</SUB><SUP>+0.06</SUP>(syst)<SUB>-0.02</SUB><SUP>+0.02</SUP>(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 Chromodynamics theoretical prediction, we extract a mass of the top quark of 171.5<SUB>-8.8</SUB><SUP>+9.9</SUP> GeV, in agreement with direct measurements.
D0 Collaboration,Abazov, V.M.,Abbott, B.,Acharya, B.S.,Adams, M.,Adams, T.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Ancu, L.S.,Aoki, M.,Arnoud, Y.,Arov, M.,Askew, A.,Asman, B.,Atr North-Holland Pub. Co 2011 Physics letters: B Vol.698 No.2
Data recorded by the D0 experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. The search is performed in the three-b-quark channel using multijet-triggered events corresponding to an integrated luminosity of 5.2 fb<SUP>-1</SUP>. In the absence of any significant excess above background, limits are set on the cross section multiplied by the branching ratio in the Higgs boson mass range 90 to 300 GeV, extending the excluded regions in the parameter space of the minimal supersymmetric standard model.
Zγ production and limits on anomalous ZZγ and Zγγ couplings in pp@? collisions at s=1.96 TeV
DO Collaboration,Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahn, S.H.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Anastasoaie, M.,Ancu North-Holland Pub. Co 2007 Physics letters: B Vol.653 No.5
We present a study of eeγ and μμγ events using 1109 (1009) pb<SUP>-1</SUP> of data in the electron (muon) channel, respectively. These data were collected with the DO detector at the Fermilab Tevatron pp@? collider at s=1.96 TeV. Having observed 453 (515) candidates in the eeγ (μμγ) final state, we measure the Zγ production cross section for a photon with transverse energy E<SUB>T</SUB>>7 GeV, separation between the photon and leptons ΔR<SUB>@</SUB>?<SUB>&</SUB>gamma;>0.7, and invariant mass of the di-lepton pair M<SUB>@</SUB>?<SUB>@</SUB>?>30 GeV/c<SUP>2</SUP>, to be 4.96+/-0.30(stat.+syst.)+/-0.30(lumi.) pb, in agreement with the Standard Model prediction of 4.74+/-0.22 pb. This is the most precise Zγ cross section measurement at a hadron collider. We set limits on anomalous trilinear Zγγ and ZZγ gauge boson couplings of -0.085<h<SUB>30</SUB><SUP>&</SUP>gamma;<0.084, -0.0053<h<SUB>40</SUB><SUP>&</SUP>gamma;<0.0054 and -0.083<h<SUB>30</SUB><SUP>Z</SUP><0.082, -0.0053<h<SUB>40</SUB><SUP>Z</SUP><0.0054 at the 95% C.L. for the form-factor scale Λ=1.2 TeV.
DO Collaboration,Abazov, V.M.,Abbott, B.,Abolins, M.,Acharya, B.S.,Adams, M.,Adams, T.,Aguilo, E.,Ahn, S.H.,Ahsan, M.,Alexeev, G.D.,Alkhazov, G.,Alton, A.,Alverson, G.,Alves, G.A.,Anastasoaie, M.,Ancu North-Holland Pub. Co 2008 Physics letters: B Vol.666 No.5
The process pp@?->γ+jet+X is studied using 1.0 fb<SUP>-1</SUP> of data collected by the D0 detector at the Fermilab Tevatron pp@? collider at a center-of-mass energy s=1.96 TeV. Photons are reconstructed in the central rapidity region |y<SUP>&</SUP>gamma;|<1.0 with transverse momenta in the range 30<p<SUB>T</SUB><SUP>&</SUP>gamma;<400 GeV while jets are reconstructed in either the central |y<SUP>jet</SUP>|<0.8 or forward 1.5<|y<SUP>jet</SUP>|<2.5 rapidity intervals with p<SUB>T</SUB><SUP>jet</SUP>>15 GeV. The differential cross section d<SUP>3</SUP>σ/dp<SUB>T</SUB><SUP>&</SUP>gamma;dy<SUP>&</SUP>gamma;dy<SUP>jet</SUP> is measured as a function of p<SUB>T</SUB><SUP>&</SUP>gamma; in four regions, differing by the relative orientations of the photon and the jet in rapidity. Ratios between the differential cross sections in each region are also presented. Next-to-leading order QCD predictions using different parameterizations of parton distribution functions and theoretical scale choices are compared to the data. The predictions do not simultaneously describe the measured normalization and p<SUB>T</SUB><SUP>&</SUP>gamma; dependence of the cross section in the four measured regions.