Émilien Chapon

Prospects for quarkonium-production studies accessible during the upcoming high-luminosity phases of the CERN Large Hadron Collider operation after 2021 are reviewed. Current experimental and theoretical open issues in the field are assessed together with the potential for future studies in quarkonium-related physics. This will be possible through the exploitation of the huge data samples to be collected in proton-proton, proton-nucleus and nucleus-nucleus collisions, both in the collider and fixed-target modes. Such investigations include, among others, those of: (i) J/psi and Upsilon produced in association with other hard particles; (ii) chi(c,b) and eta(c,b) down to small transverse momenta; (iii) the constraints brought in by quarkonia on gluon PDFs, nuclear PDFs, TMDs, GPDs and GTMDs, as well as on the low-x parton dynamics; (iv) the gluon Sivers effect in polarised-nucleon collisions; (v) the properties of the quark-gluon plasma produced in ultra-relativistic heavy-ion collisions and of collective partonic effects in general; and (vi) double and triple parton scatterings.

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 study the W/Z pair production via two-photon exchange at the LHC and give the sensitivities on trilinear and quartic gauge anomalous couplings between photons and W/Z bosons for an integrated luminosity of 30 and 200 fb^{-1}. For simplicity and to obtain lower backgrounds, only the leptonic decays of the electroweak bosons are considered.

The goal of this report is to give a comprehensive overview of the rich field of forward physics, with a special attention to the topics that can be studied at the LHC. The report starts presenting a selection of the Monte Carlo simulation tools currently available, chapter 2, then enters the rich phenomenology of QCD at low, chapter 3, and high, chapter 4, momentum transfer, while the unique scattering conditions of central exclusive production are analyzed in chapter 5. The last two experimental topics, Cosmic Ray and Heavy Ion physics are presented in the chapter 6 and 7 respectively. Chapter 8 is dedicated to the BFKL dynamics, multiparton interactions, and saturation. The report ends with an overview of the forward detectors at LHC. Each chapter is correlated with a comprehensive bibliography, attempting to provide to the interested reader with a wide opportunity for further studies.

We report an updated measurement of the CP-violating phase, $\phi_s^{J/\psi \phi}$, and the decay-width difference for the two mass eigenstates, $\Delta \Gamma_s$, from the flavor-tagged decay $B_s^0 \rightarrow J/\psi \phi$. The data sample corresponds to an integrated luminosity of 8.0 fb$^{-1}$ accumulated with the D0 detector using $p \barp$ collisions at $\sqrt{s} = 1.96$ TeV produced at the Fermilab Tevatron collider. The 68% confidence level intervals, including systematic uncertainties, are $\Delta \Gamma_s = 0.163 +0.065 -0.064 ps^{-1}$ and $\phi_s^{J/\psi \phi} = -0.55 +0.38 -0.36$. The $p$-value for the Standard Model point is 29.8%.

We present a measurement of the W boson mass using data corresponding to 4.3fb^-1 of integrated luminosity collected with the D0 detector during Run II at the Fermilab Tevatron p\bar{p} collider. With a sample of 1,677,394 W -> e\nu candidate events, we measure M_W = 80.367 +/- 0.026 GeV. This result is combined with an earlier D0 result determined using an independent Run II data sample, corresponding to 1fb^-1 of integrated luminosity, to yield M_W = 80.375 +/- 0.023 GeV.

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 describe an analysis comparing the $p\overline{p}$ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in $pp$ collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a model-independent approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the $pp$ cross section. The two data sets disagree at the $3.4\ensuremath{\sigma}$ level and thus provide evidence for the $t$-channel exchange of a colorless, $C$-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same $C$-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in $pp$ scattering for which the significance is between $3.4\ensuremath{\sigma}$ and $4.6\ensuremath{\sigma}$. The combined significance is larger than $5\ensuremath{\sigma}$ and is interpreted as the first observation of the exchange of a colorless, $C$-odd gluonic compound.

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.

We present an improved determination of the total width of the top quark, $Γ_t$, using 5.4 fb$^{-1}$ of integrated luminosity collected by the D0 Collaboration at the Tevatron $p\bar{p}$ Collider. The total width $Γ_t$ is extracted from the partial decay width $Γ(t\to Wb)$ and the branching fraction $\mathcal{B}(t\to Wb)$. $Γ(t\to Wb)$ is obtained from the $t$-channel single top quark production cross section and $\mathcal{B}(t\to Wb)$ is measured in $t\bar{t}$ events. For a top mass of $172.5\;\rm GeV$, the resulting width is $Γ_t = 2.00^{+0.47}_{-0.43}$ GeV. This translates to a top-quark lifetime of $τ_t = (3.29^{+0.90}_{-0.63})\times10^{-25}$ s. We also extract an improved direct limit on the CKM matrix element $0.81 < |V_{tb}| \leq 1$ at 95% C.L. and a limit of $|V_{tb'}| < 0.59$ for a high mass fourth generation bottom quark assuming unitarity of the fourth generation quark mixing matrix.

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.

We present a measurement of the inclusive jet cross section using the Run II cone algorithm and data collected by the D0 experiment in p pbar collisions at a center-of-mass energy sqrt(s)=1.96 TeV, corresponding to an integrated luminosity of 0.70 fb^(-1). The jet energy calibration and the method used to extract the inclusive jet cross section are described. We discuss the main uncertainties, which are dominated by the jet energy scale uncertainty. The results cover jet transverse momenta from 50 GeV to 600 GeV with jet rapidities in the range -2.4 to 2.4 and are compared to predictions using recent proton parton distribution functions. Studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented.

We present a measurement of the elastic differential cross section $d\ensuremath{\sigma}(p\overline{p}\ensuremath{\rightarrow}p\overline{p})/dt$ as a function of the four-momentum-transfer squared $t$. The data sample corresponds to an integrated luminosity of $\ensuremath{\approx}31\text{ }\text{ }{\mathrm{nb}}^{\ensuremath{-}1}$ collected with the D0 detector using dedicated Tevatron $p\overline{p}$ Collider operating conditions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ and covers the range $0.26<|t|<1.2\text{ }\text{ }{\mathrm{GeV}}^{2}$. For $|t|<0.6\text{ }\text{ }{\mathrm{GeV}}^{2}$, $d\ensuremath{\sigma}/dt$ is described by an exponential function of the form $A{e}^{\ensuremath{-}b|t|}$ with a slope parameter $b=16.86\ifmmode\pm\else\textpm\fi{}0.10(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.20(\mathrm{syst})\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}2}$. A change in slope is observed at $|t|\ensuremath{\approx}0.6\text{ }\text{ }{\mathrm{GeV}}^{2}$, followed by a more gradual $|t|$ dependence with increasing values of $|t|$.

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 ratio of events with correlated t and tbar spins to the total number of ttbar events. This ratio f is evaluated using a matrix-element-based approach in events with a single lepton (electron or muon) and at least four jets. We analyze ppbar collisions data corresponding to an integrated luminosity of 5.3 fb^-1 collected with the D0 detector at the Fermilab Tevatron collider operating at a center of mass energy $\sqrt{s}=1.96$ TeV. Combining this result with a recent measurement of f in dilepton final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in ttbar events with a significance of more than three standard deviations.

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 a measurement of the muon charge asymmetry from the decay of the $W$ boson via $W\ensuremath{\rightarrow}\ensuremath{\mu}\ensuremath{\nu}$ using $7.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron Collider at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The muon charge asymmetry is presented in two kinematic regions in muon transverse momentum and event missing transverse energy: (${p}_{T}^{\ensuremath{\mu}}>25\text{ }\text{ }\mathrm{GeV}$, ${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}>25\text{ }\text{ }\mathrm{GeV}$) and (${p}_{T}^{\ensuremath{\mu}}>35\text{ }\text{ }\mathrm{GeV}$, ${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}>35\text{ }\text{ }\mathrm{GeV}$). The measured asymmetries are compared with theory predictions made using three parton distribution function sets. The data at ${p}_{T}^{\ensuremath{\mu}}>35\text{ }\text{ }\mathrm{GeV}$, ${\mathrm{E\ensuremath{\llap{\not\;}}}}_{T}>35\text{ }\text{ }\mathrm{GeV}$, and larger values of $|{\ensuremath{\eta}}^{\ensuremath{\mu}}|$ favor an increased $d(x)/u(x)$ ratio at higher values of $x$ than is predicted.

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.

The charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 inverse femtobarns, were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios.

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 measurements of production cross sections of single top quarks in $\ppbar$ collisions at $\sqrt{s}=1.96\;\rm TeV$ in a data sample corresponding to an integrated luminosity of $5.4\;\rm fb^{-1}$ collected by the D0 detector at the Fermilab Tevatron Collider. We select events with an isolated electron or muon, an imbalance in transverse energy, and two, three, or four jets, with one or two of them containing a bottom hadron. We obtain an inclusive cross section of $\sigma({\ppbar}{\rargap}tb+X, tqb+X) = 3.43\pm^{0.73}_{0.74}\;\rm pb$ and use it to extract the CKM matrix element $0.79 < |V_{tb}| \leq 1$ at the 95% C.L. We also measure $\sigma({\ppbar}{\rargap}tb+X) = 0.68\pm^{0.38}_{0.35}\;\rm pb$ and $\sigma({\ppbar}{\rargap}tqb+X) = 2.86\pm^{0.69}_{0.63}\;\rm pb$ when assuming, respectively, $tqb$ and $tb$ production rates as predicted by the standard model.

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 relative branching fraction, ${R}_{{f}_{0}/\ensuremath{\phi}}$, of ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{f}_{0}(980)$, with ${f}_{0}(980)\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, to the process ${B}_{s}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\phi}$, with $\ensuremath{\phi}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$. The $J/\ensuremath{\psi}{f}_{0}(980)$ final state corresponds to a $CP$-odd eigenstate of ${B}_{s}^{0}$ that could be of interest in future studies of $CP$ violation. Using $8\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data recorded with the D0 detector at the Fermilab Tevatron Collider, we find ${R}_{{f}_{0}/\ensuremath{\phi}}=0.275\ifmmode\pm\else\textpm\fi{}0.041(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.061(\mathrm{syst})$.

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.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not.The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.W gamma Production and Limits on Anomalous WW gamma Couplings in p(p)over-bar Collisions at root s=1.96TeV

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 report a search for a narrow $t\overline{t}$ resonance that decays into a $\mathrm{\text{lepton}}+\mathrm{\text{jets}}$ final state based on an integrated luminosity of $5.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of proton-antiproton collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the production cross section of such a resonance multiplied by its branching fraction to $t\overline{t}$. We exclude a leptophobic topcolor ${Z}^{\ensuremath{'}}$ at the 95% confidence level for masses below 835 GeV (940 GeV) if its width is 1.2% (3%) of its mass. We also exclude color octet vector bosons (colorons) with masses below 775 GeV.

We study the processes $p\overline{p}\ensuremath{\rightarrow}WZ\ensuremath{\rightarrow}{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\nu}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ and $p\overline{p}\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}\ensuremath{\nu}\overline{\ensuremath{\nu}}$, where $\ensuremath{\ell}=e$ or $\ensuremath{\mu}$. Using $8.6\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron collider, we measure the $WZ$ production cross section to be ${4.50}_{\ensuremath{-}0.66}^{+0.63}\text{ }\text{ }\mathrm{pb}$ which is consistent with, but slightly larger than, the prediction of the standard model. The $ZZ$ cross section is measured to be $1.64\ifmmode\pm\else\textpm\fi{}0.46\text{ }\text{ }\mathrm{pb}$, in agreement with a prediction of the standard model. Combination with an earlier analysis of the $ZZ\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ channel yields a $ZZ$ cross section of ${1.44}_{\ensuremath{-}0.34}^{+0.35}\text{ }\text{ }\mathrm{pb}$.

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 present new direct constraints on a general $Wtb$ interaction using data corresponding to an integrated luminosity of 5.4 fb$^{-1}$ collected by the D0 detector at the Tevatron $p\bar{p}$ collider. The standard model provides a purely left-handed vector coupling at the $Wtb$ vertex, while the most general, lowest dimension Lagrangian allows right-handed vector and left- or right-handed tensor couplings as well. We obtain precise limits on these anomalous couplings by comparing the data to the expectations from different assumptions on the $Wtb$ coupling.

We report on a search for charged massive long-lived particles (CMLLPs), based on 5.2 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron pp collider. We search for events in which one or more particles are reconstructed as muons but have speed and ionization energy loss (dE/dx) inconsistent with muons produced in beam collisions. CMLLPs are predicted in several theories of physics beyond the standard model. We exclude pair-produced long-lived gauginolike charginos below 267 GeV and Higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar top quarks with mass below 285 GeV.

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 study $WW$ and $WZ$ production with $\ensuremath{\ell}\ensuremath{\nu}qq$ ($\ensuremath{\ell}=e,\ensuremath{\mu}$) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to $4.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity from $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. Assuming the ratio between the production cross sections $\ensuremath{\sigma}(WW)$ and $\ensuremath{\sigma}(WZ)$ as predicted by the standard model, we measure the total $WV$ ($V=W,Z$) cross section to be $\ensuremath{\sigma}(WV)={19.6}_{\ensuremath{-}3.0}^{+3.2}\text{ }\text{ }\mathrm{pb}$ and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use $b$-jet discrimination to separate the $WZ$ component from the dominant $WW$ component. Simultaneously fitting $WW$ and $WZ$ contributions, we measure $\ensuremath{\sigma}(WW)={15.9}_{\ensuremath{-}3.2}^{+3.7}\text{ }\text{ }\mathrm{pb}$ and $\ensuremath{\sigma}(WZ)={3.3}_{\ensuremath{-}3.3}^{+4.1}\text{ }\text{ }\mathrm{pb}$, which is consistent with the standard model predictions.

We present a measurement of $p\overline{p}\ensuremath{\rightarrow}Z\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}\ensuremath{\gamma}$ ($\ensuremath{\ell}=e$, $\ensuremath{\mu}$) production with a data sample corresponding to an integrated luminosity of $6.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the D0 detector at the Fermilab Tevatron $p\overline{p}$ Collider. The results of the electron and muon channels are combined, and we measure the total production cross section and the differential cross section $d\ensuremath{\sigma}/d{p}_{T}^{\ensuremath{\gamma}}$, where ${p}_{T}^{\ensuremath{\gamma}}$ is the momentum of the photon in the plane transverse to the beam line. The results obtained are consistent with the standard model predictions from next-to-leading order calculations. We use the transverse momentum spectrum of the photon to place limits on anomalous $ZZ\ensuremath{\gamma}$ and $Z\ensuremath{\gamma}\ensuremath{\gamma}$ couplings.

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.

The determination of failure modes in composite materials is often difficult to characterize because of the composition and variety of these materials. Several theoreti cal failure theories have been proposed, but no single one is accurate for every composite material; most of them predict only the first failure. Since most composites structures may still carry load after one or more plies have failed, the behavior of composite laminates is investigated beyond the first failure. This article presents a theoretical and experimental in vestigation of the successive failure modes of graphite epoxy laminated beams. Two failure theories are used: the maximum stress and the Tsai-Wu failure theories. Calculations are based on laminated plate theory.

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 ability to identify jets which originated from b quarks is an important tool of the physics program of the D0 experiment at the Fermilab Tevatron pp¯ collider. This paper describes a new algorithm designed to select jets originating from b quarks while suppressing the contamination caused by jets from other quark flavors and gluons. Additionally, a new technique, the SystemN method, for determining the misidentification rate directly from data is presented.

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 present a measurement of the top-quark mass (${m}_{t}$) in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using $t\overline{t}$ events with two leptons ($ee$, $e\ensuremath{\mu}$, or $\ensuremath{\mu}\ensuremath{\mu}$) and accompanying jets in $4.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. We analyze the kinematically underconstrained dilepton events by integrating over their neutrino rapidity distributions. We reduce the dominant systematic uncertainties from the calibration of jet energy using a correction obtained from $t\overline{t}$ events with a final state of a single lepton plus jets. We also correct jets in simulated events to replicate the quark flavor dependence of the jet response in data. We measure ${m}_{t}=173.7\ifmmode\pm\else\textpm\fi{}2.8\text{ }(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.5\text{ }(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$ and combining with our analysis in $1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of preceding data we measure ${m}_{t}=174.0\ifmmode\pm\else\textpm\fi{}2.4\text{ }(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.4\text{ }(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$. Taking into account statistical and systematic correlations, a combination with the D0 matrix element result from both data sets yields ${m}_{t}=173.9\ifmmode\pm\else\textpm\fi{}1.9\text{ }(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.6\text{ }(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$.

We report results from searches for neutral Higgs bosons produced in pp¯ collisions recorded by the D0 experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral Higgs boson in the ττ final state and in association with a b quark in the bττ and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300GeV. We exclude tanβ>20–30 for Higgs boson masses below 180GeV. These are the most stringent constraints on MSSM Higgs boson production in pp¯ collisions.

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 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 pair production of scalar top quarks ($\tilde{t}_{1}$), the lightest supersymmetric partners of the top quarks, in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of {7.3 $fb^{-1}$} collected with the \dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino ($\tilde{\nu}$). We investigate final states arising from $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu}$ and $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu} \tilde{\nu}$. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the ($m_{\tilde{t}_{1}}$,$m_{\tilde{\nu}}$) plane.

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 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 describe a model independent search for physics beyond the standard model in lepton final states. We examine 117 final states using 1.1 fb$^{-1}$ of $p \bar{p}$ collisions data at $\sqrt{s} = 1.96$ TeV collected with the D0 detector. We conclude that all observed discrepancies between data and model can be attributed to uncertainties in the standard model background modeling, and hence we do not see any evidence for physics beyond the standard model.

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 consider the hadroproduction of W gauge bosons in their leptonic decay mode. Starting from the leading-order expressions, we show that by defining a suitable scaling variable the centre-of-mass dependence of the cross sections at the LHC energies can be essentially described by a simple power law. The scaling exponent is directly linked to the small-$x$ behaviour of parton distribution functions (PDF) which, at the high virtualities involved in W production, is largely dictated by QCD evolution equations. This entails a particularly simple scaling law for the lepton charge asymmetry and also predicts that measurements in different collision systems (p-p, p-$\bar{\rm p}$, p-Pb Pb-Pb) are straightforwardly related. The expectations are compared with the existing data and a very good overall agreement is observed. It is shown that the PDF uncertainty in certain cross-section ratios between nearby centre-of-mass energies can be significantly reduced by taking the ratios at fixed value of scaling variable instead of fixed rapidity.

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 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 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 a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by the D0 detector at a pp center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R(-1)>260 GeV in a minimal UED model.