Search NASA⌕ Search

Engineering topics

Adams, Todd

Publications and source records attributed to Adams, Todd.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

A measurement of the $WZ$ and $ZZ$ production cross sections using leptonic final states in 8.6 fb$^{-1}$ of $p\bar{p}$ collisions

We study the processes p{bar p} {yields} WZ {yields} {ell}{nu}{ell}{sup +}{ell}{sup -} and p{bar p} {yields} ZZ {yields} {ell}{sup +}{ell}{sup -}{nu}{bar {nu}}, where {ell} = e or {mu}. Using 8.6 fb{sup -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{sub -0.66}{sup +0.63} pb which is consistent with, but slightly above a prediction of the standard model. The ZZ cross section is measured to be 1.64 {+-} 0.46 pb, in agreement with a prediction of the standard model. Combination with an earlier analysis of the ZZ {yields} {ell}{sup +}{ell}{sup -}{ell}{sup +}{ell}{sup -} channel yields a ZZ cross section of 1.44{sub -0.34}{sup +0.35} pb.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

W{gamma} Production and Limits on Anomalous WW{gamma} Couplings in pp Collisions at {radical}(s)=1.96 TeV

We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W({yields}l{nu})+{gamma} production in e{gamma} and {mu}{gamma} final states. Using data corresponding to an integrated luminosity of 4.2 fb{sup -1} collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp{yields}W{gamma}+X{yields}l{nu}{gamma}+X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW{gamma} couplings for data from hadron colliders: -0.4<{Delta}{kappa}{sub {gamma}<}0.4 and -0.08<{lambda}{sub {gamma}<}0.07 at the 95% C.L.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurements of single top quark production cross sections and |V tb | in pp̄ collisions at √s=1.96 TeV

We present measurements of production cross sections of single top quarks in pp̄ collisions at √s=1.96 TeV in a data sample corresponding to an integrated luminosity of 5.4 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 σ(pp̄→tb+X,tqb+X)=3.43± 0.73 0.74 pb and use it to extract the CKM matrix element 0.79<|V tb |≤1 at the 95% C.L. We also measure σ(pp̄→tb+X)=0.68±0.380.35 pb and σ(pp̄→tqb+X)=2.86± 0.69 0.63 pb when assuming, respectively, tqb and tb production rates as predicted by the standard model.

Abazov, V. M.↗
DOE OSTI2011

Search for universal extra dimensions in ppbar collisions

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{sup -1}, collected by the D0 detector at a p{bar p} 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{sup -1} > 260 GeV in a minimal UED model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Search for a Narrow $t\bar{t}$ Resonance in $p\bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV

We report a search for a narrow t{bar t} resonance that decays into a lepton+jets final state based on an integrated luminosity of 5.3 fb{sup -1} of proton-antiproton collisions at {radical}s = 1.96 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{bar t} which we compare to predictions for a leptophobic topcolor Z' boson. We exclude such a resonance at the 95% confidence level for masses below 835 GeV.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Zgamma production and limits on anomalous ZZgamma and Zgammagamma couplings in ppbar collisions at sqrt(s)=1.96 TeV

We present a study of ee{gamma} and {mu}{mu}{gamma} events using 1109 (1009) pb{sup -1} of data in the electron (muon) channel, respectively. These data were collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at {radical}s = 1.96 TeV. Having observed 453 (515) candidates in the ee{gamma} ({mu}{mu}{gamma}) final state, we measure the Z{gamma} production cross section for a photon with transverse energy ET > 7 GeV, separation between the photon and leptons {Delta}R{ell}{gamma} > 0.7, and invariant mass of the di-lepton pair M{ell}{ell} > 30 GeV/c{sup 2}, to be 4.96 {+-} 0.30(stat.+syst.) {+-} 0.30(lumi.) pb, in agreement with the Standard Model prediction of 4.74 {+-} 0.22 pb. This is the most precise Z{gamma} cross section measurement at a hadron collider. We set limits on anomalous trilinear Z{gamma}{gamma} and ZZ{gamma} gauge boson couplings of {approx}0.085 < h{sub 30}{sup {gamma}} < 0.084, {approx}0.0053 < h{sub 40}{sup {gamma}} < 0.0054 and {approx}0.083 < h{sub 30}{sup Z} < 0.082, {approx}0.0053 < h{sub 40}{sup Z} < 0.0054 at the 95% C.L. for the form-factor scale {Lambda} = 1.2 TeV.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Measurement of the inclusive jet cross section in $p \bar {p}$ collisions at $\sqrt{s}=1.96$ TeV

The ratio of the cross section for p{bar p} interactions producing a Z boson and at least one b-quark jet to the inclusive Z+jet cross section is measured using 4.2 fb{sup -1} of p{bar p} collisions collected with the D0 detector at the Fermilab Tevatron collider at {radical}s = 1.96 TeV. The Z {yields} {ell}{sup +}{ell}{sup -} candidate events with at least one b jet are discriminated from Z+charm and light jet(s) events by a novel technique that exploits the properties of the tracks associated to the jet. The measured ratio is 0.0193 {+-} 0.0027 for events having a jet with transverse momentum p{sub T} > 20 GeV and pseudorapidity |{eta}| {le} 2.5, which is the most precise to date and is consistent with theoretical predictions.

43 PARTICLE ACCELERATORS↗
DOE OSTI2011

Model-independent measurement of $\boldsymbol{t}$-channel single top quark production in $\boldsymbol{p\bar{p}}$ collisions at $\boldsymbol{\sqrt{s}=1.96}$ TeV

We present a model-independent measurement of t-channel electroweak production of single top quarks in p{bar p} collisions at {radical}s = 1.96 TeV. Using 5.4 fb{sup -1} of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider, and selecting events containing an isolated electron or muon, missing transverse energy and one or two jets originating from the fragmentation of b quarks, we measure a cross section {sigma}(p{bar p} {yields} tqb + X) = 2.90 {+-} 0.59 (stat + syst) pb for a top quark mass of 172.5 GeV. The probability of the background to fluctuate and produce a signal as large as the one observed is 1.6 x 10{sup -8}, corresponding to a significance of 5.5 standard deviations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurement of the production fraction times branching fraction $\boldsymbol{ f(b\to\Lambda_{b})\cdot \mathcal{B}(\Lambda_{b}\to J/\psi \Lambda)}$

The {Lambda}{sub b}(udb) baryon is observed in the decay {Lambda}{sub b} {yields} J/{psi}{Lambda} using 6.1 fb{sup -1} of p{bar p} collisions collected with the D0 detector at {radical}s = 1.96 TeV. The production fraction multiplied by the branching fraction for this decay relative to that for the decay B{sup 0} {yields} J/{psi}K{sub s}{sup 0} is measured to be 0.345 {+-} 0.034 (stat.) {+-} 0.033 (syst.) {+-} 0.003 (PDG). Using the world average value of f(b {yields} B{sup 0}) {center_dot} {Beta}(B{sup 0} {yields} J/{psi}K{sub s}{sup 0}) = (1.74 {+-} 0.08) x 10{sup -5}, they obtain f(b {yields} {Lambda}{sub b}) {center_dot} {Beta}({Lambda}{sub b} {yields} J/{psi}{Lambda}) = (6.01 {+-} 0.60 (stat.) {+-} 0.58 (syst.) {+-} 0.28 (PDG)) x 10{sup -5}. This measurement represents an improvement in precision by about a factor of three with respect to the current world average.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Implantable Biofuel Cell

Explore the source record for details and available documents.

24 POWER TRANSMISSION AND DISTRIBUTION↗