SEARCH · Engineering Papers
Results for “Deterrence”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Search for Violation of Lorentz Invariance in Top Quark Pair Production and Decay
Not Available
Combined Search for the Standard Model Higgs Boson Decaying to bb̄ Using the D0 Run II Data Set
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 bb̄ using the data sample collected with the D0 detector in pp̄ collisions at √s=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% C.L. 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% C.L. 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.
Search for the standard model Higgs Boson in associated W H production in 9.7 fb – 1 of p p ¯ collisions with the D0 detector
Here, 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 $WH\to\ell\nu b\bar{b}$ production and uses data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at $\sqrt{s}=1.96$ TeV. We observe agreement between 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$\times\sigma_{\rm SM}$, where $\sigma_{\rm SM}$ is the standard model Higgs boson production cross section, while the expected limit is 4.7$\times\sigma_{\rm SM}$.
Measurement of the $B_s^0$ Lifetime in the Flavor-Specific Decay Channel $B_s^0 \to D_s^- \mu^+\nu X$
We present an updated measurement of the B s 0 lifetime using the semileptonic decays B s 0 → D s - μ + ν X , with D s - → ϕ π - 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 + ν X decay with D - → ϕ π - 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 ) .
Measurement of the Effective Weak Mixing Angle in p p ¯ → Z / γ * → e + e - Events
We present a measurement of the fundamental parameter of the standard model, the weak mixing angle sin 2 θ ℓ eff which determines the relative strength of weak and electromagnetic interactions, in pp¯→Z/γ*→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 θ ℓ eff =0.23147±0.00047 is the most precise measurement from light quark interactions to date, with a precision close to the best LEP and SLD results.
Evidence for Simultaneous Production of J/ψ and Υ Mesons
We report evidence for the simultaneous production of J/ψ and Υ 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, σ$_{eff}$=2.2±0.7(stat)±0.9(syst) mb.
Evidence for a $B_s^0 \pi^\pm$ state
We report evidence for a narrow structure, X(5568), in the decay sequence X(5568)→Bs0π±, Bs0→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/c2 and Γ=21.9±6.4(stat)-2.5+5.0(syst) MeV/c2. If the decay is X(5568)→Bs*π±→Bs0γπ± with an unseen γ, m(X(5568)) will be shifted up by m(Bs*)-m(Bs0)∼49 MeV/c2. This measurement is based on 10.4 fb−1 of pp¯ collision data at s=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.
Measurement of the Effective Weak Mixing Angle in p p ¯ → Z / γ * → ℓ + ℓ − Events
Not Available
Electron and photon identification in the D0 experiment
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.
Measurement of the photon plus b-jet production differential cross section in $p\bar{p}$ collisions at $\sqrt{s}$ =1.96 TeV
We present measurements of the differential cross section dσ/dρ γ τ for the inclusive production of a photon in association with a b -quark jet for photons with rapidities |y γ | < 1.0 and 30 < ρ γ τ < 300 GeV , as well as for photons with 1.5 <|y γ | < 2.5 and 30 < ρ γ τ < 200 GeV, where ρ γ τ is the photon transverse momentum. The b -quark jets are required to have p T > 15 GeV and rapidity |y jet | < 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 $p\bar{p}$ Collider at $\sqrt{s}$ =1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the SHERPA and PYTHIA Monte Carlo event generators.
Measurement of angular correlations of jets at root s=1.96 TeV and determination of the strong coupling at high momentum transfers
N/A
Limits on anomalous trilinear gauge boson couplings from WW, WZ and W gamma production in p(p)over-bar collisions at root s=1.96 TeV
N/A
Measurement of the p(p)over-bar -> W plus b plus X production cross section at root s=1.96 TeV D0 Collaboration
.
Measurement of the differential gamma plus c-jet cross section and the ratio of differential gamma plus c and gamma plus b cross sections in p(p)over-bar collisions at root s=1.96 TeV
N/A
Measurement of the ratio of three-jet to two-jet cross sections in p(p)over-bar collisions at root s=1.96 TeV
N/A
Measurement of the combined rapidity and p(T) dependence of dijet azimuthal decorrelations in p(p)over-bar collisions at root s=1.96 TeV
.
Measurement of the differential cross sections for isolated direct photon pair production in $p\bar{p}$ collisions at $\sqrt{s}$= 1.96 TeV
We present measurements of direct photon pair production cross sections using 8.5fb -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 $dσ/dM_{γγ}$, pair transverse momentum $dσ/dp^{γγ}_{T}$, azimuthal angle between the photons $dσ/dΔφ_{γγ}$, and polar scattering angle in the Collins–Soper frame $dσ/d|cos θ*|$. Measurements are performed for isolated photons with transverse momenta $p^γ_T$ > 18(17)GeV for the leading (next-to-leading) photon in $p_T$, pseudorapidities , |$η^γ$| < 0.9 and a separation in η–φ space Δ$\mathscr{R}_{γγ}$ >0.4. We present comparisons with the predictions from Monte Carlo event generators DIPHOX and RESBOS implementing QCD calculations at next-to-leading order, 2γNNLO at next-to-next-to-leading order, and SHERPA using matrix elements with higher-order real emissions matched to parton shower.