A. Dominguez

We report evidence for a narrow structure, X(5568), in the decay sequence X(5568)→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, J/ψ→μ^{+}μ^{-}, ϕ→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 Γ=21.9±6.4(stat)_{-2.5}^{+5.0}(syst) MeV/c^{2}. If the decay is X(5568)→B_{s}^{*}π^{±}→B_{s}^{0}γπ^{±} with an unseen γ, m(X(5568)) will be shifted up by m(B_{s}^{*})-m(B_{s}^{0})∼49 MeV/c^{2}. This measurement is based on 10.4 fb^{-1} of pp[over ¯] collision data at sqrt[s]=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.

We investigate the decay B + → J/ψφK + in a search for the X(4140) state, a narrow threshold resonance in the J/ψφ system.The data sample corresponds

We present a measurement of the forward--backward asymmetry in top quark-antiquark production using the full Tevatron Run II dataset collected by the D0 experiment at Fermilab. The measurement is performed in lepton+jets final states using a new kinematic fitting algorithm for events with four or more jets and a new partial reconstruction algorithm for events with only three jets. Corrected for detector acceptance and resolution effects, the asymmetry is evaluated to be 10.6+-3.0 %. Results are consistent with the standard model predictions which range from 5.0% to 8.8%. We also present the dependence of the asymmetry on the invariant mass of the top quark--antiquark system and the difference in rapidities of top quark and antiquark.

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We present the observation of doubly-produced $J/\psi$ mesons with the D0 detector at Fermilab in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV. The production cross section for both singly and doubly-produced $J/\psi$ mesons is measured using a sample with an integrated luminosity of 8.1fb$^{-1}$. For the first time, the double $J/\psi$ production cross section is separated into contributions due to single and double parton scatterings. Using these measurements, we determine the effective cross section $\sigma_{eff}$, a parameter characterizing an effective spatial area of the parton-parton interactions and related to the parton spatial density inside the nucleon.

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at $\sqrt{s}=1800$ GeV and $\sqrt{s}=630$ GeV and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in $\eta$--$\phi$ space are defined, at the same pseudo-rapidity, $\eta$, as the jet with the highest transverse energy ($E_T^{(1)}$), and at $\pm 90^o$ in the azimuthal direction, $\phi$. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of $E_T^{(1)}$ and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet $E_T^{(1)}$ over most of the measured range. This study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. %this is new The distribution of the sum of the track momenta in the two cones is also examined for five different $E_T^{(1)}$ bins. The HERWIG and PYTHIA Monte Carlos are reasonably successful in describing the data, but neither can describe completely all of the event properties.

We present a measurement of the semileptonic mixing asymmetry for ${B}^{0}$ mesons, ${a}_{\mathrm{sl}}^{d}$, using two independent decay channels: ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{D}^{\ensuremath{-}}X$, with ${D}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{\ensuremath{-}}$; and ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{D}^{*\ensuremath{-}}X$, with ${D}^{*\ensuremath{-}}\ensuremath{\rightarrow}{\overline{D}}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}$, ${\overline{D}}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ (and charge conjugate processes). We use a data sample corresponding to $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, collected with the D0 experiment at the Fermilab Tevatron collider. We extract the charge asymmetries in these two channels as a function of the visible proper decay length of the ${B}^{0}$ meson, correct for detector-related asymmetries using data-driven methods, and account for dilution from charge-symmetric processes using Monte Carlo simulation. The final measurement combines four signal visible proper decay length regions for each channel, yielding ${a}_{\mathrm{sl}}^{d}=[0.68\ifmmode\pm\else\textpm\fi{}0.45(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{syst})]%$. This is the single most precise measurement of this parameter, with uncertainties smaller than the current world average of $B$ factory measurements.

We present a measurement of the electron charge asymmetry in $p\bar{p}\rightarrow W+X \rightarrow e\nu +X$ events at a center-of-mass energy of 1.96 TeV, using data corresponding to 9.7~fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The asymmetry is measured as a function of the electron pseudorapidity and is presented in five kinematic bins based on the electron transverse energy and the missing transverse energy in the event. The measured asymmetry is compared with next-to-leading-order predictions in perturbative quantum chromodynamics and provides accurate information for the determination of parton distribution functions of the proton. This is the most precise lepton charge asymmetry measurement to date.

We measure the inclusive single muon charge asymmetry and the like-sign dimuon charge asymmetry in pp collisions using the full data set of 10.4 fb -1 collected with

We measure the mass of the top quark in lepton+jets final states using the full sample of $p\bar{p}$ collision data collected by the D0 experiment in Run~II of the Fermilab Tevatron Collider at $\sqrt s=1.96~$TeV, corresponding to $9.7~{\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $t\bar t$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $m_t=174.98\pm0.76~{\rm GeV}$. This constitutes the most precise single measurement of the top-quark mass.

We report evidence for the simultaneous production of $J/\psi$ and $\Upsilon$ mesons in 8.1 fb$^{-1}$ of data collected at $\sqrt{s}=$1.96 TeV by the D0 experiment at the Fermilab $p \bar p$ Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, $\sigma_{eff}=2.2\pm 0.7\mbox{(stat)} \pm 0.9 \mbox{(syst)} ~\mbox{mb}$.

We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance Delta-R in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of Delta-R and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in pp-bar collisions at sqrt(s)=1.96 The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.

Using data corresponding to an integrated luminosity of 1.3 fb^-1, we observe a narrow mass state decaying into Upsilon(1S)+gamma, where the Upsilon(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 \pm 0.014 (stat.) \pm 0.017 (syst.) GeV/c^2, which is consistent with that of the state recently observed by the ATLAS Collaboration.

We present a comprehensive analysis of inclusive W(\to e\nu)+n-jet (n\geq 1,2,3,4) production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV at the Tevatron collider using a 3.7 fb^{-1} dataset collected by the D0 detector. Differential cross sections are presented as a function of the jet rapidities (y), lepton transverse momentum (p_T) and pseudorapidity (\eta), the scalar sum of the transverse energies of the W boson and all jets (H_T), leading dijet p_T and invariant mass, dijet rapidity separations for a variety of jet pairings for p_T-ordered and angular-ordered jets, dijet opening angle, dijet azimuthal angular separations for p_T-ordered and angular-ordered jets, and W boson transverse momentum. The mean number of jets in an event containing a W boson is measured as a function of H_T, and as a function of the rapidity separations between the two highest-p_T jets and between the most widely separated jets in rapidity. Finally, the probability for third-jet emission in events containing a W boson and at least two jets is studied by measuring the fraction of events in the inclusive W+2-jet sample that contain a third jet over a p_T threshold. The analysis employs a regularized singular value decomposition technique to accurately correct for detector effects and for the presence of backgrounds. The corrected data are compared to particle level next-to-leading order perturbative QCD predictions, predictions from all-order resummation approaches, and a variety of leading-order and matrix-element plus parton-shower event generators. Regions of the phase space where there is agreement or disagreement with the data are discussed for the different models tested.

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, ${a}_{\mathrm{sl}}^{s}$, using ${B}_{s}^{0}({\overline{B}}_{s}^{0})\ensuremath{\rightarrow}{D}_{s}^{\ensuremath{\mp}}{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}X$ decays, with ${D}_{s}^{\ensuremath{\mp}}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\pi}}^{\ensuremath{\mp}}$ and $\ensuremath{\phi}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$, using $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ 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 ${D}_{s}^{\ensuremath{-}}$ and ${D}_{s}^{+}$ mass distributions of the ${B}_{s}^{0}$ and ${\overline{B}}_{s}^{0}$ candidates yields the flavor-specific asymmetry ${a}_{\mathrm{sl}}^{s}=[\ensuremath{-}1.12\ifmmode\pm\else\textpm\fi{}0.74(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.17(\mathrm{syst})]%$, which is the most precise measurement and in agreement with the standard model prediction.

We present measurements of lepton ($\ensuremath{\ell}$) angular distributions in top-quark ($t$) pair production and $t\overline{t}\ensuremath{\rightarrow}{W}^{+}b{W}^{\ensuremath{-}}\overline{b}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}\ensuremath{\nu}b{\ensuremath{\ell}}^{\ensuremath{-}}\overline{\ensuremath{\nu}}\overline{b}$ decays produced in $p\overline{p}$ collisions at a center-of-mass energy of $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, where $\ensuremath{\ell}$ is an electron or muon. Using data corresponding to an integrated luminosity of $5.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, 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 ${A}_{\mathrm{FB}}^{\ensuremath{\ell}}=(5.8\ifmmode\pm\else\textpm\fi{}5.1(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.3(\mathrm{syst}))%$, corrected for detector acceptance. This is compared to the standard model prediction of ${A}_{\mathrm{FB}}^{\ensuremath{\ell}}(\mathrm{predicted})=(4.7\ifmmode\pm\else\textpm\fi{}0.1)%$. A deviation from the standard model prediction as previously seen in a D0 measurement based on the analysis of the $\ensuremath{\ell}+\mathrm{\text{jets}}$ 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 ${A}_{\mathrm{FB}}^{\ensuremath{\ell}}=(11.8\ifmmode\pm\else\textpm\fi{}3.2)%$. Furthermore, we present a first study of the top-quark polarization.

We determine the fraction of events with double parton (DP) scattering in a single ppbar collision at sqrt{s}=1.96 TeV in samples of photon + 3 jet and photon + 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 photon + 3 jet and photon + b/c jet + 2 jet samples of sigma_eff^incl = 12.7 +- 0.2 (stat) +- 1.3 (syst) mb and sigma_eff^HF = 14.6 +- 0.6 (stat) +- 3.2 (syst) mb, respectively.

We present a study of the inclusive production of the X(4140) state with the decay to the J/ψϕ final state in hadronic collisions. Based on 10.4 fb^{-1} of pp[over ¯] collision data collected by the D0 experiment at the Fermilab Tevatron collider, we report the first evidence for the prompt production of an X(4140) state and find the fraction of X(4140) events originating from b hadrons to be f_{b}=0.39±0.07(stat)±0.10(syst). The ratio of the nonprompt X(4140) production rate to the B_{s}^{0} yield in the same channel is R=0.19±0.05(stat)±0.07(syst). The values of the mass M=4152.5±1.7(stat)_{-5.4}^{+6.2}(syst) MeV and width Γ=16.3±5.6(stat)±11.4(syst) MeV are consistent with previous measurements.

We present measurements of the cross sections for the two main production modes of single top quarks in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV in the Run II data collected with the D0 detector at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 9.7 fb$^{-1}$. The s-channel cross section is measured to be $σ(p\bar{p} \to tb+X) = 1.10^{+0.33}_{-0.31}$ pb with no assumptions on the value of the t-channel cross section. Similarly, the t-channel cross section is measured to be $σ(p\bar{p} \to tqb+X) = 3.07^{+0.54}_{-0.49}$ pb. We also measure the $s+t$ combined cross section as $σ(p\bar{p} \to tb+X, tqb+X) = 4.11^{+0.60}_{-0.55}$ pb and set a lower limit on the CKM matrix element $|V_{tb}| > 0.92$ at $95\%$ C.L., assuming $m_t=172.5$ GeV. The probability to measure a cross section for the s channel at the observed value or higher in the absence of signal is $1.0\times 10^{-4}$, corresponding to a significance of 3.7 standard deviations.

We present measurements of asymmetries in angular distributions of leptons produced in $t\overline{t}$ events in proton-antiproton collisions at the Fermilab Tevatron Collider. We consider final states where the ${W}^{\ifmmode\pm\else\textpm\fi{}}$ bosons from top quark and antiquark decays both decay into $\ensuremath{\ell}\ensuremath{\nu}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$) resulting in oppositely charged dilepton final states with accompanying jets. Using $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected with the D0 detector, we find the asymmetries in lepton pseudorapidity compatible with predictions based on the standard model.

The production of top quark-antiquark pair events in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is studied as a function of the transverse momentum and absolute value of the rapidity of the top quarks as well as of the invariant mass of the $t\bar{t}$ pair. We select events containing an isolated lepton, a large imbalance in transverse momentum, and four or more jets with at least one jet identified to originate from a $b$ quark. The data sample corresponds to 9.7 fb$^{-1}$ of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Observed differential cross sections are consistent with standard model predictions.

We present measurements of the differential cross section dσ/dpTγ for the associated production of a c-quark jet and an isolated photon with rapidity |yγ|<1.0 and transverse momentum 30<pTγ<300GeV. The c-quark jets are required to have |yjet|<1.5 and pTjet>15GeV. The ratio of differential cross sections for γ+c to γ+b production as a function of pTγ is also presented. The results are based on data corresponding to an integrated luminosity of 8.7fb−1 recorded with the D0 detector at the Fermilab Tevatron pp¯ Collider at s=1.96TeV. The obtained results are compared to next-to-leading order perturbative QCD calculations using various parton distribution functions, to predictions based on the kT-factorization approach, and to predictions from the sherpa and pythia Monte Carlo event generators.

We present searches for the anomalous γWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wγ, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6fb−1 of integrated luminosity collected by the D0 detector in pp¯ collisions at s=1.96TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Δκγ, λ, and Δg1Z for a cutoff energy scale Λ=2TeV. The combined 68% C.L. limits are −0.057<Δκγ<0.154, −0.015<λ<0.028, and −0.008<Δg1Z<0.054 for the LEP parameterization, and −0.007<Δκ<0.081 and −0.017<λ<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.

We present measurements of the differential cross section dσ/dpTγ for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |yγ|<1.0 and 30<pTγ<300GeV, as well as for photons with 1.5<|yγ|<2.5 and 30<pTγ<200GeV, where pTγ is the photon transverse momentum. The b-quark jets are required to have pT>15GeV and rapidity |yjet|<1.5. 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 pp¯ Collider at s=1.96TeV. 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 kT-factorization QCD approach, and those from the sherpa and pythia Monte Carlo event generators.

We present a measurement of the cross section for W boson production in association with at least one b-quark jet in proton–antiproton collisions. The measurement is made using data corresponding to an integrated luminosity of 6.1fb−1 recorded with the D0 detector at the Fermilab Tevatron pp¯ Collider at s=1.96TeV. We measure an inclusive cross section of σ(W(→μν)+b+X)=1.04±0.05(stat.)±0.12(syst.) pb and σ(W(→eν)+b+X)=1.00±0.04(stat.)±0.12(syst.) pb in the phase space defined by pTν>25GeV, pTb-jet>20GeV, |ηb-jet|<1.1, and a muon (electron) with pTℓ>20GeV and |ημ|<1.7 (|ηe|<1.1 or 1.5<|ηe|<2.5). The combined result per lepton family is σ(W(→ℓν)+b+X)=1.05±0.12(stat.+syst.)pb for |ηℓ|<1.7. The results are in agreement with predictions from next-to-leading order QCD calculations using mcfm, σ(W+b)⋅B(W→ℓν)=1.34−0.34+0.41(syst.)pb, and also with predictions from the sherpa and madgraph Monte Carlo event generators.

We present a search for anomalous components of the quartic gauge boson coupling W W γγ in events with an electron, a positron and missing transverse energy.The analyzed data correspond to 9.

We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into b bbar using the data sample collected with the D0 detector in p pbar collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% CL upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV <= M_H <= 150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% CL. In the mass range 120 GeV <= M_H <= 145 GeV the data exhibit an excess above the background prediction with a global significance of 1.5 standard deviations, consistent with the expectation in the presence of a standard model Higgs boson.

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 tt[over ¯] production cross section in lepton+jets final states. We quantify this violation using the standard-model extension framework, which predicts a dependence of the tt[over ¯] 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))(μν33) and (c(U))(μν33) 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.

We present a study of the ${X}^{\ifmmode\pm\else\textpm\fi{}}(5568)$ using semileptonic decays of the ${B}_{s}^{0}$ meson using the full run II integrated luminosity of $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ in proton-antiproton collisions at a center of mass energy of 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. We report evidence for a narrow structure, ${X}^{\ifmmode\pm\else\textpm\fi{}}(5568)$, in the decay sequence ${X}^{\ifmmode\pm\else\textpm\fi{}}(5568)\ensuremath{\rightarrow}{B}_{s}^{0}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ where ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{\mp}}{D}_{s}^{\ifmmode\pm\else\textpm\fi{}}\mathrm{X}$, ${D}_{s}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ which is consistent with the previous measurement by the D0 Collaboration in the hadronic decay mode, ${X}^{\ifmmode\pm\else\textpm\fi{}}(5568)\ensuremath{\rightarrow}{B}_{s}^{0}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ where ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\phi}$. The mass and width of this state are measured using a combined fit of the hadronic and semileptonic data, yielding $m={5566.9}_{\ensuremath{-}3.1}^{+3.2}{(\mathrm{stat})}_{\ensuremath{-}1.2}^{+0.6}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$, $\mathrm{\ensuremath{\Gamma}}={18.6}_{\ensuremath{-}6.1}^{+7.9}{(\mathrm{stat})}_{\ensuremath{-}3.8}^{+3.5}(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ with a significance of $6.7\ensuremath{\sigma}$.

We present measurements of direct photon pair production cross sections using 8.5 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron $p \bar p$ collider. The results are presented as differential distributions of the photon pair invariant mass $d\sigma/dM_{\gamma \gamma}$, pair transverse momentum $d \sigma /dp^{\gamma \gamma}_T$, azimuthal angle between the photons $d\sigma/d\Delta \phi_{\gamma \gamma}$, and polar scattering angle in the Collins-Soper frame $d\sigma /d|\cos \theta^*|$. Measurements are performed for isolated photons with transverse momenta $p^{\gamma}_T>18 ~(17)$ GeV for the leading (next-to-leading) photon in $p_T$, pseudorapidities $|\eta^{\gamma}|<0.9$, and a separation in $\eta-\phi$ space $\Delta\mathcal R_{\gamma\gamma} > 0.4$. We present comparisons with the predictions from Monte Carlo event generators {\sc diphox} and {\sc resbos} implementing QCD calculations at next-to-leading order, $2\gamma${\sc nnlo} at next-to-next-to-leading order, and {\sc sherpa} using matrix elements with higher-order real emissions matched to parton shower.

We present a measurement of the W boson production charge asymmetry in pp̄→W+X→eν+X events at a center of mass energy of 1.96 TeV, using 9.7 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider. The neutrino longitudinal momentum is determined by using a neutrino weighting method, and the asymmetry is measured as a function of the W boson rapidity. The measurement extends over wider electron pseudorapidity region than previous results and is the most precise to date, allowing for precise determination of proton parton distribution functions in global fits.

We present an overview of the muon reconstruction and identification methods employed by the D0 collaboration to analyze the Run II (2001–2011) pp¯ data of the Fermilab Tevatron collider at s=1.96TeV. We discuss the performance of these methods, how it is measured using D0 data, and how it is properly modeled by the D0 simulation program. In its pseudorapidity acceptance, |η|<2, the muon system identifies high-pT muons (pT≳10GeV) with efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the D0 central tracking system with efficiencies ranging from 85% to 92% and with a typical relative momentum resolution of 10% for pT=40GeV. Isolation criteria reject multijet background with efficiencies of 87–99%.

The calibration of jet energy measured in the D0 detector is presented, based on pp¯ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. Jet energies are measured using a sampling calorimeter composed of uranium and liquid argon as the passive and active media, respectively. This paper describes the energy calibration of jets performed with γ+jet, Z+jet and dijet events, with jet transverse momentum pT>6GeV and pseudorapidity range |η|<3.6. The corrections are measured separately for data and simulation, achieving a precision of 1.4–1.8% for jets in the central part of the calorimeter and up to 3.5% for the jets with pseudorapidity |η|=3.0. Specific corrections are extracted to enhance the description of jet energy in simulation and in particular of the effects due to the flavor of the parton originating the jet, correcting biases up to 3–4% in jets with low pT originating from gluons and up to 6–8% in jets from b quarks.

We present evidence for the exotic charged charmoniumlike state ${Z}_{c}^{\ifmmode\pm\else\textpm\fi{}}(3900)$ decaying to $J/\ensuremath{\psi}{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$ in semi-inclusive weak decays of $b$-flavored hadrons. The signal is correlated with a parent $J/\ensuremath{\psi}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ system in the invariant-mass range 4.2--4.7 GeV that would include the exotic structure $Y(4260)$. The study is based on $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collision data collected by the D0 experiment at the Fermilab Tevatron collider.

We use a sample of diphoton + dijet events to measure the effective cross section of double parton interactions, which is found to be $\sigma_{\rm eff} = 19.3$ $\pm$ $1.4({\rm stat})$ $\pm$ $7.8({\rm syst})$ mb. The sample was collected by the D0 detector at the Fermilab Tevatron collider in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV and corresponds to an integrated luminosity of 8.7 fb$^{-1}$.

We give a detailed description of the measurement of the $W$ boson mass, $M_W$, performed on an integrated luminosity of 4.3 fb$^{-1}$, which is based on similar techniques as used for our previous measurement done on an independent data set of 1 fb$^{-1}$ of data. The data were collected using the D0 detector at the Fermilab Tevatron Collider. This data set yields $1.68\times 10^6$ $W\rightarrow e\nu$ candidate events. We measure the mass using the transverse mass, electron transverse momentum, and missing transverse energy distributions. The $M_W$ measurements using the transverse mass and the electron transverse momentum distributions are the most precise of these three and are combined to give $M_W$ = 80.367 $\pm$ 0.013 (stat) $\pm$ 0.022 (syst) GeV = 80.367 $\pm$ 0.026 GeV. When combined with our earlier measurement on 1 fb$^{-1}$ of data, we obtain $M_W$ = 80.375 $\pm$ 0.023 GeV.

We present a simultaneous measurement of the forward-backward asymmetry and the top-quark polarization in $t\bar t$ production in dilepton final states using 9.7 fb$^{-1}$ of proton-antiproton collisions at $\sqrt{s}=1.96$ TeV with the D0 detector. To reconstruct the distributions of kinematic observables we employ a matrix element technique that calculates the likelihood of the possible $t\bar t$ kinematic configurations. After accounting for the presence of background events and for calibration effects, we obtain a forward-backward asymmetry of $A^{t\bar t} = (15.0 \pm 6.4 \text{ (stat)} \pm 4.9 \text{ (syst)})\%$ and a top-quark polarization times spin analyzing power in the beam basis of $\kappa P = (7.2 \pm 10.5 \text{ (stat)} \pm 4.2 \text{ (syst)})\%$, with a correlation of $-56\%$ between the measurements. If we constrain the forward-backward asymmetry to its expected standard model value, we obtain a measurement of the top polarization of $\kappa P = (11.3 \pm 9.1 \text{ (stat)} \pm 1.9 \text{ (syst)})\%.$ If we constrain the top polarization to its expected standard model value, we measure a forward-backward asymmetry of $A^{t\bar t} = (17.5 \pm 5.6 \text{ (stat)} \pm 3.1 \text{ (syst)})\%.$ A combination with the D0 $A^{t\bar t}$ measurement in the lepton+jets final state yields an asymmetry of $ A^{t\bar t} = (11.8 \pm 2.5 \text{ (stat)} \pm 1.3 \text{ (syst)})\% . $ Within their respective uncertainties, all these results are consistent with the standard model expectations.

We present a measurement of the fundamental parameter of the standard model, the weak mixing angle, in $p\bar{p}\rightarrow Z/\gamma^{*}\rightarrow e^{+}e^{-}$ events at a center of mass energy of 1.96 TeV, using data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron. The effective weak mixing angle is extracted from the forward-backward charge asymmetry as a function of the invariant mass around the Z boson pole. The measured value of $\sin^2\theta_{\text{eff}}^{\text{$\ell$}}=0.23147 \pm 0.00047$ is the most precise measurement from light quark interactions to date, with a precision close to the best LEP and SLD results.

We measure the Lambda_b^0 lifetime in the fully reconstructed decay Lambda_b^0 -> J/psi Lambda^0 using 10.4 fb^-1 of ppbar collisions collected with the D0 detector at sqrt(s)=1.96 TeV. The lifetime of the topologically similar decay channel B^0 -> J/psi K^0_S is also measured. We obtain tau(Lambda_b^0) = 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_b^0)/tau(B^0) = 0.864 +- 0.052 (stat.) +- 0.033 (syst.).

We present a search for the standard model Higgs boson in 9.5 fb-1 of ppbar collisions at sqrt(s) = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered contains a pair of b jets and is characterized by an imbalance in transverse energy, as expected from ppbar->ZH->vvbb production. The search is also sensitive to the WH->lvbb channel when the charged lepton is not identified. The data are found to be in good agreement with the expected background. For a Higgs boson mass of 125 GeV, we set a limit at the 95% C.L. on the cross section sigma(ppbar->[Z/W]H), assuming standard model branching fractions, that is a factor of 4.3 times larger than the theoretical standard model value, while the expected factor is 3.9. The search is also used to measure a combined WZ and ZZ production cross section that is a factor of 0.94 +/- 0.31(stat) +/- 0.34(syst) times the standard model prediction of 4.4 pb, with an observed significance of 2.0 standard deviations.

We perform a combination of searches for standard model Higgs boson production in $p\bar{p}$ collisions recorded by the D0 detector at the Fermilab Tevatron Collider at a center of mass energy of $\sqrt{s}=1.96$ 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 $90\leq M_H \leq 200$ 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 two standard deviations, consistent with the presence of a standard model Higgs boson of mass 125 GeV.

The electron and photon reconstruction and identification algorithms used by the D0 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→γℓℓ (ℓ=e,μ) collected in pp¯ collisions at a center-of-mass energy of 1.96 TeV using an integrated luminosity of up to 10 fb−1.

We present the first measurements of the ratios of cross sections, \sigma(ppbar -> Z+c jet)/\sigma(ppbar -> Z+jet) and \sigma(ppbar -> Z+c jet)/\sigma(ppbar -> Z+b jet) for the associated production of a Z boson with at least one charm or bottom quark jet. Jets have transverse momentum p_{T}>20 GeV and pseudorapidity |\eta|<2.5. These cross section ratios are measured differentially as a function of jet and $Z$ boson transverse momenta, based on 9.7 fb^{-1} of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt(s) = 1.96 TeV. The measurements show significant deviations from perturbative QCD calculations and predictions from various event generators.

We present measurements of the forward-backward asymmetry in the angular distribution of leptons from decays of top quarks and antiquarks produced in proton-antiproton collisions. We consider the final state containing a lepton and at least three jets. The entire sample of data collected by the D0 experiment during Run II of the Fermilab Tevatron Collider, corresponding to 9.7 inverse fb of integrated luminosity, is used. The asymmetry measured for reconstructed leptons is $A_{FB}^l = \big(2.9 \pm 2.1(stat.) ^{+1.5}_{-1.7}(syst.) \big)$%. When corrected for efficiency and resolution effects within the lepton rapidity coverage of $|y_l|<1.5$, the asymmetry is found to be $A_{FB}^l = \big(4.2 \pm 2.3(stat.) ^{+1.7}_{-2.0}(syst.) \big)$%. Combination with the asymmetry measured in the dilepton final state yields $A_{FB}^l = \big(4.2 \pm 2.0(stat.) \pm 1.4(syst.) \big)$%. We examine the dependence of $A_{FB}^l$ on the transverse momentum and rapidity of the lepton. The results are in agreement with predictions from the next-to-leading-order QCD generator \mcatnlo, which predicts an asymmetry of $A_{FB}^l = 2.0$% for $|y_l|<1.5$.

We measure the top quark mass in dilepton final states of top-antitop events in proton-antiproton collisions at sqrt(s) = 1.96 TeV, using data corresponding to an integrated luminosity of 9.7 fb^-1 at the Fermilab Tevatron Collider. The analysis features a comprehensive optimization of the neutrino weighting method to minimize the statistical uncertainties. We also improve the calibration of jet energies using the calibration determined in top-antitop to lepton+jets events, which reduces the otherwise limiting systematic uncertainty from the jet energy scale. The measured top quark mass is mt = 173.32 +/- 1.36(stat) +/- 0.85(syst) GeV.

We use a neural-network technique to search for standard model single-top-quark production in the $106{\mathrm{pb}}^{\ensuremath{-}1}$ dataset accumulated by the Collider Detector at Fermilab detector during the 1992--1995 collider run (``run I''). Using a sample of 64 $W+1,$ 2, 3 jets events, we set a 95% confidence level upper limit of 24 pb on the W-gluon and ${W}^{*}$ combined single-top cross section.

We present a measurement of the isolated direct photon cross section in p-pbar collisions at sqrt(s) = 1.8 TeV and |eta| < 0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two-track event signature. To remove pi0 -> gamma gamma and eta -> gamma gamma events we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of pT is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.

We measure the mass of the top quark in lepton$+$jets final states using the full sample of $p\bar{p}$ collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at $\sqrt s=1.96 $TeV, corresponding to $9.7 {\rm fb}^{-1}$ of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from $t\bar t$ production or background. The overall jet energy scale is constrained in situ by the mass of the $W$ boson. We measure $m_t=174.98\pm0.76$ GeV. This constitutes the most precise single measurement of the top-quark mass.

We have measured the azimuthal angular correlation of $b\overline{b}$ production, using $86.5\text{ }\text{ }\mathrm{p}{\mathrm{b}}^{\ensuremath{-}1}$ of data collected by Collider Detector at Fermilab (CDF) in $p\overline{p}$ collisions at $\sqrt{s}=1.8\text{ }\text{ }\mathrm{TeV}$ during 1994--1995. In high-energy $p\overline{p}$ collisions, such as at the Tevatron, $b\overline{b}$ production can be schematically categorized into three mechanisms. The leading-order (LO) process is ``flavor creation,'' where both $b$ and $\overline{b}$ quarks substantially participate in the hard scattering and result in a distinct back-to-back signal in final state. The ``flavor excitation'' and the ``gluon splitting'' processes, which appear at next-leading-order (NLO), are known to make a comparable contribution to total $b\overline{b}$ cross section, while providing very different opening angle distributions from the LO process. An azimuthal opening angle between bottom and antibottom, $\ensuremath{\Delta}\ensuremath{\phi}$, has been used for the correlation measurement to probe the interaction creating $b\overline{b}$ pairs. The $\ensuremath{\Delta}\ensuremath{\phi}$ distribution has been obtained from two different methods. One method measures the $\ensuremath{\Delta}\ensuremath{\phi}$ between bottom hadrons using events with two reconstructed secondary vertex tags. The other method uses $b\overline{b}\ensuremath{\rightarrow}(J/\ensuremath{\psi}X)(\ensuremath{\ell}{X}^{\ensuremath{'}})$ events, where the charged lepton ($\ensuremath{\ell}$) is an electron ($e$) or a muon ($\ensuremath{\mu}$), to measure $\ensuremath{\Delta}\ensuremath{\phi}$ between bottom quarks. The $b\overline{b}$ purity is determined as a function of $\ensuremath{\Delta}\ensuremath{\phi}$ by fitting the decay length of the $J/\ensuremath{\psi}$ and the impact parameter of the $\ensuremath{\ell}$. Both methods quantify the contribution from higher-order production mechanisms by the fraction of the $b\overline{b}$ pairs produced in the same azimuthal hemisphere, ${f}_{\mathrm{toward}}$. The measured ${f}_{\mathrm{toward}}$ values are consistent with both parton shower Monte Carlo and NLO QCD predictions.

The polarization of the $W$ boson in $t\ensuremath{\rightarrow}Wb$ decay is unambiguously predicted by the standard model of electroweak interactions and is a powerful test of our understanding of the $tbW$ vertex. We measure this polarization from the invariant mass of the $b$ quark from $t\ensuremath{\rightarrow}Wb$ and the lepton from $W\ensuremath{\rightarrow}l\ensuremath{\nu}$ whose momenta measure the $W$ decay angle and direction of motion, respectively. In this paper we present a measurement of the decay rate (${f}_{V+A}$) of the $W$ produced from the decay of the top quark in the hypothesis of $\mathrm{V}+\mathrm{A}$ structure of the $tWb$ vertex. We find no evidence for the nonstandard $\mathrm{V}+\mathrm{A}$ vertex and set a limit on ${f}_{V+A}$ $&lt;$ 0.80 at $95%$ confidence level. By combining this result with a complementary observable in the same data, we assign a limit on ${f}_{V+A}$ $&lt;$ 0.61 at $95%$ CL. This corresponds to a constraint on the right-handed helicity component of the W polarization of ${f}_{+}&lt;0.18$ at $95%$ CL. This limit is the first significant direct constraint on ${f}_{V+A}$ in top decay.

We present a search for the standard model (SM) Higgs boson produced in association with a Z boson in 9.7 fb(-1) of pp collisions collected with the D0 detector at the Fermilab Tevatron Collider at √s = 1.96 TeV. Selected events contain one reconstructed Z→e(+)e(-) or Z→μ(+)μ(-) 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→bb 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.

We perform a search for the rare decay Bs->mumu using data collected by the D0 experiment at the Fermilab Tevatron Collider. This result is based on the full D0 Run II dataset corresponding to 10.4 fb^(-1) of ppbar collisions at sqrt(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 BR(Bs->mumu) < 15x10^(-9) at the 95% C.L.

We measure the ratio of cross sections, $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}Z+b\text{ }\mathrm{\text{jet}})/\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}Z+\mathrm{\text{jet}})$, 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 $p\overline{p}$ Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The results are compared to predictions from next-to-leading order calculations and various Monte Carlo event generators.

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→ℓνbb production and uses data corresponding to 9.7 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp Collider at √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 × σ(SM), where σ(SM) is the standard model Higgs boson production cross section, while the expected limit is 4.7 × σ(SM).

The inclusive cross section of top quark-antiquark pairs produced in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton$+$jets and dilepton decay channels. The data sample corresponds to 9.7 fb${}^{-1}$ of integrated luminosity recorded with the D0 detector during Run II of the Fermilab Tevatron Collider. Employing multivariate analysis techniques we measure the cross section in the two decay channels and we perform a combined cross section measurement. For a top quark mass of 172.5 GeV, we measure a combined inclusive top quark-antiquark pair production cross section of $\sigma_{t\bar{t}} = 7.26 \pm 0.13\,(\mathrm{stat.})\,^{+0.57}_{-0.50}\,(\mathrm{syst.})$ pb which is consistent with standard model predictions. We also perform a likelihood fit to the measured and predicted top quark mass dependence of the inclusive cross section, which yields a measurement of the pole mass of the top quark. The extracted value is $m_t = 172.8 \pm 1.1\,(\mathrm{theo.})\,^{+3.3}_{-3.1}\,(\mathrm{exp.})$ GeV.

We present a study of the production of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ in inelastic $p\overline{p}$ collisions at $\sqrt{s}=1800$ and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and $⟨{p}_{T}⟩$ of ${K}_{S}^{0}$ and ${\ensuremath{\Lambda}}^{0}$ on charged particle multiplicity, are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The ${p}_{T}$ distributions extend above $8\text{ }\text{ }\mathrm{GeV}/c$, showing a $⟨{p}_{T}⟩$ higher than previous measurements. The dependence of the mean ${K}_{S}^{0}({\ensuremath{\Lambda}}^{0})$ ${p}_{T}$ on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.

We present the first combined measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, based on 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 for the parameter $\Delta \phi_{\rm max}$. The quantity $R_{\Delta \phi}$ is measured in $p\bar{p}$ collisions at $\sqrt{s}=1.96\,$TeV, as a function of the dijet rapidity interval, the total scalar transverse momentum, and $\Delta \phi_{\rm max}$. The measurement uses an event sample corresponding to an integrated luminosity of $0.7\,$fb$^{-1}$ collected with the D0 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, except in the kinematic region of large dijet rapidity intervals and large $\Delta \phi_{\rm max}$.

We present a measurement of Z boson pair production in ppbar collisions at 1.96 TeV with 9.6 fb-1 to 9.8fb-1 of D0 data. We examine the final states with four electrons, two electrons plus two muons, and four muons. Based on selected data, the measured cross section in the mass region M(Z/gamma*) > 30 GeV is sigma(ppbar to Z/gamma* Z/gamma*)= 1.26 ^{+0.44}_{-0.36} (stat) ^{+0.17}_{-0.15} (syst) +/- 0.08 (lumi) pb; after correcting for the expected ratio of sigma(ppbar to Z/gamma* Z/gamma*) to sigma(ppbar to ZZ), we derive a cross section for ppbar to ZZ production of 1.05 ^{+0.37}_{-0.30} (stat) ^{+0.14}_{-0.12} (syst) +/- 0.06 (lumi) pb. This result is combined with a previous result from the ZZ to two charged leptons plus two neutrinos channel resulting in a combined ppbar to ZZ cross section measurement of 1.32 ^{+0.29}_{-0.25} (stat) +/- 0.12 (syst) +/- 0.04 (lumi)} pb. These measurements are consistent with the standard model expectation of 1.43 \pm 0.10 pb. We extend this analysis to search for the standard model (SM) Higgs boson between 115 and 200 GeV. At a Higgs boson mass of 125 GeV, we expect to set a limit of 43 times the SM expectation at 95% C.L., and set a limit of 42 times the SM expectation at 95% C.L.

We present a measurement of the forward-backward asymmetry in the production of $B^{\pm}$ mesons, $A_{\rm FB}(B^{\pm})$, using $B^{\pm} \rightarrow J/\psi K^{\pm}$ decays in 10.4 ${\rm fb}^{-1}$ of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV collected by the D0 experiment during Run II of the Tevatron collider. A nonzero asymmetry would indicate a preference for a particular flavor, i.e., $b$ quark or $\bar{b}$ antiquark, to be produced in the direction of the proton beam. We extract $A_{\rm FB}(B^{\pm})$ from a maximum likelihood fit to the difference between forward- and backward-produced $B^{\pm}$ mesons. We measure an asymmetry consistent with zero: $A_{\rm FB}(B^{\pm})$ = [$-$0.24 $\pm$ 0.41 (stat) $\pm$ 0.19 (syst)]%.

We present a measurement of the top quark mass in $p\overline{p}$ collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The matrix element technique is applied to $t\overline{t}$ events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the $\mathrm{lepton}+\text{jets}$ final state of $t\overline{t}$ decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of ${m}_{t}=173.93\ifmmode\pm\else\textpm\fi{}1.84\text{ }\text{ }\mathrm{GeV}$.

We present a measurement of the direct CP-violating charge asymmetry in B(±) mesons decaying to J/ψK(±) and J/ψπ(±) where J/ψ decays to μ(+) μ(-), using the full run II data set of 10.4 fb(-1) of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. A difference in the yield of B(-) and B(+) mesons in these decays is found by fitting to the difference between their reconstructed invariant mass distributions resulting in asymmetries of A(J/ψK) = [0.59 ± 0.37]%, which is the most precise measurement to date, and A(J/ψπ) = [-4.2 ± 4.5]%. Both measurements are consistent with standard model predictions.

We study the process of associated photon and jet production, $p\overline{p}\ensuremath{\rightarrow}\ensuremath{\gamma}+\mathrm{\text{jet}}+X$, using $8.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider at a center-of-mass energy $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. Photons are reconstructed with rapidity $|{y}^{\ensuremath{\gamma}}|&lt;1.0$ or $1.5&lt;|{y}^{\ensuremath{\gamma}}|&lt;2.5$ and transverse momentum ${p}_{T}^{\ensuremath{\gamma}}&gt;20\text{ }\text{ }\mathrm{GeV}$. The highest-${p}_{T}$ jet is required to be in one of four rapidity regions up to $|{y}^{\mathrm{jet}}|\ensuremath{\le}3.2$. For each rapidity configuration we measure the differential cross sections in ${p}_{T}^{\ensuremath{\gamma}}$ separately for events with the same sign (${y}^{\ensuremath{\gamma}}{y}^{\mathrm{jet}}&gt;0$) and opposite signs (${y}^{\ensuremath{\gamma}}{y}^{\mathrm{jet}}\ensuremath{\le}0$) of photon and jet rapidities. We compare the measured triple-differential cross sections, ${\mathrm{d}}^{3}\ensuremath{\sigma}/\mathrm{d}{p}_{T}^{\ensuremath{\gamma}}\mathrm{d}{y}^{\ensuremath{\gamma}}\mathrm{d}{y}^{\mathrm{jet}}$, to next-to-leading order (NLO) perturbative QCD calculations using different sets of parton distribution functions, and to predictions from the sherpa and pythia Monte Carlo event generators. The NLO calculations are found to be in general agreement with the data but do not describe all kinematic regions.

We investigate the decay $B_s^0 \rightarrow J/\psi K^+ K^-$ for invariant masses of the $K^+K^-$ pair in the range $1.35<M(K^+K^-)<2$ GeV. The data sample corresponds to an integrated luminosity of 10.4 fb$^{-1}$ of $p \bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV 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 \bsf and measure the relative branching fraction of the decays \bsf and \bsdec to be $R_{f_2^{\prime}/\phi} = 0.19 \pm 0.05 \rm \thinspace{(stat)} \pm 0.04 \rm \thinspace{(syst)}$.

We present a measurement of the cross sections for the associated production of a W boson with at least one heavy quark jet, b or c, in proton–antiproton collisions. Data corresponding to an integrated luminosity of 8.7fb−1 recorded with the D0 detector at the Fermilab Tevatron pp¯ Collider at s=1.96TeV are used to measure the cross sections differentially as a function of the jet transverse momenta in the range 20 to 150 GeV. These results are compared to calculations of perturbative QCD theory as well as predictions from Monte Carlo generators.

We present an updated measurement of the B(s)(0) lifetime using the semileptonic decays B(s)(0)→D(s)(-)μ(+)νX, with D(s)(-)→ϕπ(-) and ϕ→K(+)K(-) (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at √[s]=1.96 TeV, comprising an integrated luminosity of 10.4 fb(-1). We find a flavor-specific lifetime τ(fs)(B(s)(0))=1.479±0.010(stat)±0.021(syst) ps. This technique is also used to determine the B(0) lifetime using the analogous B(0)→D(-)μ(+)νX decay with D(-)→ϕπ(-) and ϕ→K(+)K(-), yielding τ(B(0))=1.534±0.019(stat)±0.021(syst) ps. Both measurements are consistent with the current world averages, and the B(s)(0) lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio τ(fs)(B(s)(0))/τ(B(0))=0.964±0.013(stat)±0.007(syst).

We present, in detail, a search for the standard model Higgs boson, $H$, in final states with a charged lepton (electron or muon), missing energy, and two or more jets in data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected at a center of mass energy of $\sqrt{s}$ = 1.96 TeV with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider. The search uses $b$-jet identification to categorize events for improved signal versus background separation and is sensitive to associated production of the $H$ with a $W$ boson, $WH\to\ell\nu b\bar{b}$; gluon fusion with the Higgs decaying to $W$ boson pairs, $H\to WW\to\ell\nu jj$; and associated production with a vector boson where the Higgs decays to $W$ boson pairs, $VH\to VWW \to \ell\nu jjjj$ production (where $V = W$ or $Z$). We observe good agreement between data and expected background. We test our method by measuring $WZ$ and $ZZ$ production with $Z\to b\bar{b}$ and find production rates consistent with the standard model prediction. 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 \obslimA$\times\sigma_{\rm SM}$, where $\sigma_{\rm SM}$ is the standard model Higgs boson production cross section, while the expected limit is \explimA$\times\sigma_{\rm SM}$. We also interpret the data considering models with fourth generation fermions, or a fermiophobic Higgs boson.

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 7.3fb−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 ττ, WW, ZZ and bb¯ 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.

We present a measurement of the distribution of the variable ${\ensuremath{\phi}}_{\ensuremath{\eta}}^{*}$ for muon pairs with masses between 30 and 500 GeV, using the complete run II data set collected by the D0 detector at the Fermilab Tevatron proton-antiproton collider. This corresponds to an integrated luminosity of $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The data are corrected for detector effects and presented in bins of dimuon rapidity and mass. The variable ${\ensuremath{\phi}}_{\ensuremath{\eta}}^{*}$ probes the same physical effects as the $Z/{\ensuremath{\gamma}}^{*}$ boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. These are the first measurements at any collider of the ${\ensuremath{\phi}}_{\ensuremath{\eta}}^{*}$ distributions for dilepton masses away from the $Z\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ boson mass peak. The data are compared to QCD predictions based on the resummation of multiple soft gluons.

We present the first search for CPT-violating effects in the mixing of ${B_s^0}$ mesons using the full Run II data set with an integrated luminosity of 10.4 fb$^{-1}$ of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. We measure the CPT-violating asymmetry in the decay $B_s^0 \to \mu^\pm D_s^\pm$ as a function of celestial direction and sidereal phase. We find no evidence for CPT-violating effects and place limits on the direction and magnitude of flavor-dependent CPT- and Lorentz-invariance violating coupling coefficients. We find 95\% confidence intervals of $\Delta a_{\perp} < 1.2 \times 10^{-12}$ GeV and $(-0.8 < \Delta a_T - 0.396 \Delta a_Z < 3.9) \times 10^{-13}$ GeV.

We present a measurement of the correlation between the spins of t and t¯ quarks produced in proton–antiproton collisions at the Tevatron Collider at a center-of-mass energy of 1.96 TeV. We apply a matrix element technique to dilepton and single-lepton+jets final states in data accumulated with the D0 detector that correspond to an integrated luminosity of 9.7fb−1. The measured value of the correlation coefficient in the off-diagonal basis, Ooff=0.89±0.22(stat+syst), is in agreement with the standard model prediction, and represents evidence for a top–antitop quark spin correlation difference from zero at a level of 4.2 standard deviations.

We study the production of the exotic charged charmonium-like state $Z_c^{\pm}(3900)$ in $p \bar p$ collisions through the sequential process $\psi(4260) \rightarrow Z_c^{\pm}(3900) \pi^{\mp}$, $Z_c^{\pm}(3900) \rightarrow J/\psi \pi^{\pm}$. Using the subsample of candidates originating from semi-inclusive weak decays of $b$-flavored hadrons, we measure the invariant mass and natural width to be $M=3902.6^{+5.2}_{-5.0}{\rm \thinspace (stat)}^{+3.3}_{-1.4}{\rm \thinspace (syst)}$ MeV and $\Gamma=32 ^{+28}_{-21}{\rm \thinspace (stat)} ^{+26}_{-7}{\rm \thinspace (syst)}$ MeV, respectively. We search for prompt production of the $Z_c^{\pm}(3900)$ through the same sequential process. No significant signal is observed, and we set an upper limit of 0.66 at the 95\% credibility level on the ratio of prompt production to the production via $b$-hadron decays. The study is based on $10.4~\rm{fb^{-1}}$ of $p \overline p $ collision data collected by the D0 experiment at the Fermilab Tevatron collider.

We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, ${N}_{q}$ and ${N}_{g}$, produced at the Fermilab Tevatron in $p\overline{p}$ collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of ${\ensuremath{\theta}}_{c}=0.28$, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness $Q={E}_{\mathrm{jet}}{\ensuremath{\theta}}_{c}$ varies in the range from 12 to 25 GeV. At $Q=19.2\text{ }\text{ }\mathrm{GeV}$, the ratio of multiplicities $r={N}_{g}/{N}_{q}$ is found to be $1.64\ifmmode\pm\else\textpm\fi{}0.17$, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

We present a new search for ${H}^{0}V$ production, where ${H}^{0}$ is a scalar Higgs boson decaying into $b\overline{b}$ with branching ratio $\ensuremath{\beta}$, and $V$ is a ${Z}^{0}$ boson decaying into ${e}^{+}{e}^{\ensuremath{-}}$, ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, or $\ensuremath{\nu}\overline{\ensuremath{\nu}}$. This search is then combined with previous searches for ${H}^{0}V$ where $V$ is a ${W}^{\ifmmode\pm\else\textpm\fi{}}$ boson or a hadronically decaying ${Z}^{0}$. The data sample consists of $106\ifmmode\pm\else\textpm\fi{}4\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.8\text{ }\text{ }\mathrm{TeV}$ accumulated by the Collider Detector at Fermilab. Observing no evidence of a signal, we set 95% Bayesian credibility level upper limits on $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}{H}^{0}V)\ifmmode\times\else\texttimes\fi{}\ensuremath{\beta}$. For ${H}^{0}$ masses of 90, 110, and $130\text{ }\text{ }\mathrm{GeV}/{c}^{2}$, the limits are 7.8, 7.2, and 6.6 pb, respectively.

The Compact Muon Solenoid Experiment (CMS) will start taking data at the Large Hadron Collider (LHC) in 2007 with the largest silicon tracking detector ever built. The central components of this tracker consist of two forward/backward pixel disks on each side of the interaction region and three barrel pixel layers. The silicon pixel detector will be crucial to pattern recognition and track reconstruction in the hadronic collisions of CMS and will play a key role in the physics program of the LHC. During the 2007 pilot physics run of the LHC, CMS will run with a subset of the final detector to be installed in 2008. In this report, the final design and results from test beam runs and expected performance of the detector are given. The expected radiation tolerance and projected lifetime of the pixel detector will be discussed as well its impact on the physics program of CMS.

We present a search for a Higgs boson decaying into a pair of photons based on $9.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ collected with the D0 detector at the Fermilab Tevatron Collider. The search employs multivariate techniques to discriminate signal from the nonresonant background and is separately optimized for a standard model and a fermiophobic Higgs boson. No significant excess of data above the background prediction is observed and upper limits on the product of the cross section and branching fraction are derived at the 95% confidence level as a function of Higgs boson mass. For a standard model Higgs boson with mass of 125 GeV, the observed (expected) upper limits are a factor of 12.8 (8.7) above the standard model prediction. The existence of a fermiophobic Higgs boson with mass in the 100--113 GeV range is excluded at the 95% confidence level.

We present a search for charged massive long-lived particles (CMLLPs) that are pair produced in p-pbar collisions at sqrt(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 muon-like particles that have both speed and ionization energy loss dE/dx different from muons produced in p-pbar 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 pb to 0.008 pb for scalar tau lepton masses of 100 to 300 GeV.

We present the first measurements of the differential cross section dσ/dpTγ for the production of an isolated photon in association with at least two b-quark jets. The measurements consider photons with rapidities |yγ|<1.0 and transverse momenta 30<pTγ<200GeV. The b-quark jets are required to have pTjet>15GeV and |yjet|<1.5. The ratio of differential production cross sections for γ+2 b-jets to γ+b-jet as a function of pTγ is also presented. The results are based on the proton–antiproton collision data at s=1.96TeV collected with the D0 detector at the Fermilab Tevatron Collider. The measured cross sections and their ratios are compared to the next-to-leading order perturbative QCD calculations as well as predictions based on the kT-factorization approach and those from the sherpa and pythia Monte Carlo event generators.

We present a measurement of the ratio of multijet cross sections in pp-bar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R3/2, has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the PYTHIA event generator do not agree with the data, while SHERPA provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data.

The lifetime of the $B^{0}_{s}$ meson is measured in the decay channel $B^{0}_{s} \to J/\psi\mbox{ }\pi^+ \pi^-$ with $880 \leq M_{\pi^+\pi^-} \leq 1080$ 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 $B^{0}_{s}$ meson is measured to be $\tau(B^{0}_{s}) = 1.70\pm 0.14 \mbox{ (stat)} \pm 0.05 \mbox{ (syst) ps}$. Neglecting CP violation in $B_s^0/\bar{B}_s^0$ mixing, the measurement can be translated into the width of the heavy mass eigenstate of the $B^0_s$, $\Gamma_H = 0.59 \pm 0.05 \mbox{ (stat)} \pm 0.02 \mbox{ (syst)} \mbox{ ps$^{-1}$}$.

We present the first measurement of the A_2 and A_3 angular coefficients of the W boson produced in proton-antiproton collisions. We study W-> e+nu and W-> mu+nu candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at sqrt(s)=1.8 TeV. The corresponding integrated luminosity was 110 pb^-1. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order alpha_s^2 in QCD.

We present a measurement of the coefficient alpha_2 of the leptonic polar-angle distribution from W boson decays, as a function of the W transverse momentum. The measurement uses an 80+/-4 pb^{-1} sample of proton-antiproton collisions at sqrt{s}=1.8 TeV collected by the CDF detector and includes data from both the W->e+nu and W->mu+nu decay channels. We fit the W boson transverse mass distribution to a set of templates from a Monte Carlo event generator and detector simulation in several ranges of the W transverse momentum. The measurement agrees with the Standard Model expectation, whereby the ratio of longitudinally to transversely polarized W bosons, in the Collins-Soper W rest frame, increases with the W transverse momentum at a rate of approximately 15% per 10 GeV/c.

We present a measurement of the electric charge of top quarks using $t\overline{t}$ events produced in $p\overline{p}$ collisions at the Tevatron. The analysis is based on fully reconstructed $t\overline{t}$ pairs in $\text{lepton}+\text{jets}$ final states. Using data corresponding to $5.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity, we exclude the hypothesis that the top quark has a charge of $Q=\ensuremath{-}4/3e$ at a significance greater than 5 standard deviations. We also place an upper limit of 0.46 on the fraction of such quarks that can be present in an admixture with the standard model top quarks ($Q=+2/3e$) at a 95% confidence level.

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 $p\bar{p}$ collisions at $\sqrt{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 $ZH\rightarrow \ell\ell b\bar{b}$, $WH\rightarrow \ellνb\bar{b}$, and $ZH\rightarrow ννb\bar{b}$ 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 is 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 $J^{P}=2^{+}$ fraction above 0.67 at the 95$\%$ CL. The expected exclusion covers $J^{P}=0^{-}$ ($J^{P}=2^{+}$) fractions above 0.54 (0.47).

We present the first search for supersymmetry (SUSY) in Zgamma 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 ppbar collisions at sqrt(s)=1.96 TeV. This signature is predicted in gauge-mediated SUSY-breaking models, where the lightest neutralino is the next-to-lightest supersymmetric particle (NLSP) and is produced in pairs, possibly through decay from heavier supersymmetric particles. The NLSP 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 SUSY breaking scales of Lambda < 87 TeV, corresponding to neutralino masses of < 151 GeV.

We present a search for the Higgs boson in final states with two oppositely charged leptons and large missing transverse energy as expected in $H\ensuremath{\rightarrow}WW\ensuremath{\rightarrow}\ensuremath{\ell}\ensuremath{\nu}{\ensuremath{\ell}}^{\ensuremath{'}}{\ensuremath{\nu}}^{\ensuremath{'}}$ decays. The events are selected from the full Run II data sample of $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions collected with the D0 detector at the Fermilab Tevatron Collider at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. To validate our search methodology, we measure the nonresonant $WW$ production cross section and find ${\ensuremath{\sigma}}_{WW}=11.6\ifmmode\pm\else\textpm\fi{}0.7\text{ }\text{ }\mathrm{pb}$, 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 $159&lt;{M}_{H}&lt;176\text{ }\text{ }\mathrm{GeV}$ is excluded while the expected exclusion sensitivity is $156&lt;{M}_{H}&lt;172\text{ }\text{ }\mathrm{GeV}$. For a mass hypothesis of ${M}_{H}=125\text{ }\text{ }\mathrm{GeV}$, 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 $125&lt;{M}_{H}&lt;218\text{ }\text{ }\mathrm{GeV}$ 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 ${M}_{H}=125\text{ }\text{ }\mathrm{GeV}$.

We present a search for the standard model Higgs boson produced in association with a $Z$ boson in $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of $p\overline{p}$ collisions collected with the D0 detector at the Fermilab Tevatron Collider at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. Selected events contain one reconstructed $Z\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ or $Z\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ candidate and at least two jets, including at least one jet likely to contain a $b$ quark. To validate the search procedure, we also measure the cross section for $ZZ$ production and find that it is consistent with the standard model expectation. We set upper limits at the 95% C.L. on the product of the $ZH$ production cross section and branching ratio $\mathcal{B}(H\ensuremath{\rightarrow}b\overline{b})$ for Higgs boson masses $90\ensuremath{\le}{M}_{H}\ensuremath{\le}150\text{ }\text{ }\mathrm{GeV}$. The observed (expected) limit for ${M}_{H}=125\text{ }\text{ }\mathrm{GeV}$ is a factor of 7.1 (5.1) larger than the standard model prediction.

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with pT > 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV pp collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(+0.84)(-0.07) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta = 3) model.

A search for the direct production of Higgs bosons in the di-tau decay mode is performed with 86.3±3.5 pb−1 of data collected with the Collider Detector at Fermilab during the 1994–1995 data taking period of the Tevatron. We search for events where one tau decays to an electron plus neutrinos and the other tau decays hadronically. We perform a counting experiment and set limits on the cross section for supersymmetric Higgs boson production where tanβ is large and mA is small. For a benchmark parameter space point where mA0=100 GeV/c2 and tanβ=50, we limit the production cross section multiplied by the branching ratio to be less than 77.9 pb at the 95% confidence level compared to the theoretically predicted value of 11.0 pb. This is the first search for Higgs bosons decaying to tau pairs at a hadron collider.5 MoreReceived 13 June 2005DOI:https://doi.org/10.1103/PhysRevD.72.072004©2005 American Physical Society

We present a measurement of the effective weak mixing angle parameter sin^{2}θ_{eff}^{ℓ} in pp[over ¯]→Z/γ^{*}→μ^{+}μ^{-} events at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb^{-1} of integrated luminosity. The measured value of sin^{2}θ_{eff}^{ℓ}[μμ]=0.23016±0.00064 is further combined with the result from the D0 measurement in pp[over ¯]→Z/γ^{*}→e^{+}e^{-} events, resulting in sin^{2}θ_{eff}^{ℓ}[comb]=0.23095±0.00040. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the Z/γ^{*} to light quarks.

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 $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ 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 $H\ensuremath{\rightarrow}\ensuremath{\tau}\ensuremath{\tau}$ decays or $H\ensuremath{\rightarrow}WW$ 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.

We present a search for Higgs bosons in multilepton final states in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ recorded with the D0 detector at the Fermilab Tevatron Collider, using the full Run II data set with integrated luminosities of up to $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The multilepton states considered are $ee\ensuremath{\mu}$, $e\ensuremath{\mu}\ensuremath{\mu}$, $\ensuremath{\mu}{\ensuremath{\tau}}_{h}{\ensuremath{\tau}}_{h}$, and like-charge ${e}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}$ pairs. These channels directly probe the HVV ($V=W$, $Z$) coupling of the Higgs boson in production and decay. The $\ensuremath{\mu}{\ensuremath{\tau}}_{h}{\ensuremath{\tau}}_{h}$ channel is also sensitive to $H\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ decays. Upper limits at the 95% C.L on the rate of standard model Higgs boson production are derived in the mass range $100\ensuremath{\le}{M}_{H}\ensuremath{\le}200\text{ }\text{ }\mathrm{GeV}$. The expected and observed limits are a factor of 6.3 and 8.4 above the predicted standard model cross section at ${M}_{H}=125\text{ }\text{ }\mathrm{GeV}$. We also interpret the data in a fermiophobic Higgs boson model.

We measure the direct $CP$-violating parameter ${A}_{CP}$ for the decay of the charged charm meson, ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ (and charge conjugate), using the full $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ sample of $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from $B\ensuremath{\rightarrow}D$ processes) using input from Monte Carlo simulation. We measure ${A}_{CP}=[\ensuremath{-}0.16\ifmmode\pm\else\textpm\fi{}0.15(\text{stat})\ifmmode\pm\else\textpm\fi{}0.09(\text{syst})]%$, which is consistent with zero, as expected from the standard model prediction of $CP$ conservation, and is the most precise measurement of this quantity to date.

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 $\sqrt s=1.8$ TeV and Run II (2001--2011) at $\sqrt s=1.96$ TeV of the Tevatron $p \bar{p}$ collider, corresponding to integrated luminosities of 0.1 fb$^{-1}$ and 9.7 fb$^{-1}$, respectively. The combined result is: $m_t = 174.95 \pm0.40\,{\rm(stat)} \pm 0.64\,{\rm(syst)}\,{\rm{GeV}}=174.95 \pm 0.75 \, {\rm{GeV}}$.

We present a measurement of the direct CP-violating charge asymmetry in Ds+ → ϕ π(±) decays where the ϕ meson decays to K(+)K(-), using the full Run II data set with an integrated luminosity of 10.4 fb-1 of proton-antiproton collisions collected using the D0 detector at the Fermilab Tevatron Collider. The normalized difference A(CP) in the yield of D(s)(+) and D(s)(-) mesons in these decays is measured by fitting the difference between their reconstructed invariant mass distributions. This results in an asymmetry of A(CP) = [-0.38 ± 0.27]%, which is the most precise measurement of this quantity to date. The result is consistent with the standard model prediction of zero CP asymmetry in this decay.

We present a study of the normalized transverse momentum distribution of $W$ bosons produced in $p\overline{p}$ collisions, using data corresponding to an integrated luminosity of $4.35\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the D0 detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The measurement focuses on the transverse momentum region below 15 GeV, which is of special interest for electroweak precision measurements; it relies on the same detector calibration methods which were used for the precision measurement of the $W$ boson mass. The measured distribution is compared to different QCD predictions and a procedure is given to allow the comparison of any further theoretical models to the D0 data.

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 $H\ensuremath{\rightarrow}WW$ decays. The events are selected from data corresponding to $8.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ 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.

We present a measurement of top quark polarization in $t\overline{t}$ pair production in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using data corresponding to $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. We consider final states containing a lepton and at least three jets. The polarization is measured through the distribution of lepton angles along three axes: the beam axis, the helicity axis, and the transverse axis normal to the $t\overline{t}$ production plane. This is the first measurement of top quark polarization at the Tevatron using $\mathrm{lepton}+\text{jet}$ final states and the first measurement of the transverse polarization in $t\overline{t}$ production. The observed distributions are consistent with standard model predictions of nearly no polarization.

We measure the ratio of cross sections, $\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}Z+2b\text{ }\text{jets})/\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}Z+2\text{ }\text{jets})$, for associated production of a $Z$ boson with at least two jets with transverse momentum ${p}_{T}^{\text{jet}}&gt;20\text{ }\text{ }\mathrm{GeV}$ and pseudorapidity $|{\ensuremath{\eta}}^{\text{jet}}|&lt;2.5$. This measurement uses data corresponding to an integrated luminosity of $9.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the D0 experiment in Run II of Fermilab's Tevatron $p\overline{p}$ Collider at a center-of-mass energy of 1.96 TeV. The measured integrated ratio of $0.0236\ifmmode\pm\else\textpm\fi{}0.0032(\text{stat})\ifmmode\pm\else\textpm\fi{}0.0035(\text{syst})$ is in agreement with predictions from next-to-leading-order perturbative QCD and the Monte Carlo event generators pythia and alpgen.

We measure the forward-backward asymmetry in the production of ${\mathrm{\ensuremath{\Lambda}}}_{b}^{0}$ and ${\overline{\mathrm{\ensuremath{\Lambda}}}}_{b}^{0}$ baryons as a function of rapidity in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using $10.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. The asymmetry is determined by the preference of ${\mathrm{\ensuremath{\Lambda}}}_{b}^{0}$ or ${\overline{\mathrm{\ensuremath{\Lambda}}}}_{b}^{0}$ particles to be produced in the direction of the beam protons or antiprotons, respectively. The measured asymmetry integrated over rapidity $y$ in the range $0.1&lt;|y|&lt;2.0$ is $A=0.04\ifmmode\pm\else\textpm\fi{}0.07(\text{stat})\ifmmode\pm\else\textpm\fi{}0.02(\text{syst})$.