Search NASA⌕ Search

Engineering topics

Corcoran, M.

Publications and source records attributed to Corcoran, M..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states from $t\bar t$ production at the Tevatron

We present a simultaneous measurement of the forward-backward asymmetry and the top-quark polarization in tt¯ production in dilepton final states using 9.7 fb –1 of proton-antiproton collisions at √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 tt¯ kinematic configurations. After accounting for the presence of background events and for calibration effects, we obtain a forward-backward asymmetry of A tt¯ =(15.0±6.4(stat)±4.9(syst))% and a top-quark polarization times spin analyzing power in the beam basis of κP=(7.2±10.5(stat)±4.2(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 κP=(11.3±9.1(stat)±1.9(syst))%. If we constrain the top polarization to its expected standard model value, we measure a forward-backward asymmetry of A tt¯ =(17.5±5.6(stat)±3.1(syst))%. A combination with the D0 A tt¯ measurement in the lepton+jets final state yields an asymmetry of Att¯=(11.8±2.5(stat)±1.3(syst))%. Within their respective uncertainties, all these results are consistent with the standard model expectations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of the ratio of inclusive cross sections $\sigma (p\bar{p} \rightarrow Z+2~b~\text{jets}) / \sigma (p\bar{p} \rightarrow Z+ \text{2 jets})$ in $p\bar{p}$ collisions at $\sqrt s=1.96$ TeV

In this study, we measure the ratio of cross sections, σ(pp¯ → Z + 2 b jets)/σ(pp¯ → Z + 2 jets), for associated production of a Z boson with at least two jets with transverse momentum p jet T > 20 GeV and pseudorapidity |η jet | < 2.5. This measurement uses data corresponding to an integrated luminosity of 9.7 fb –1 collected by the D0 experiment in Run II of Fermilab’s Tevatron pp¯ Collider at a center-of-mass energy of 1.96 TeV. The measured integrated ratio of 0.0236 ± 0.0032(stat) ± 0.0035(syst) is in agreement with predictions from next-to-leading-order perturbative QCD and the Monte Carlo event generators PYTHIA and ALPGEN .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

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 ) .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of the direct C P -violating parameter A C P in the decay D + → K - π + π +

We measure the direct C P -violating parameter A C P for the decay of the charged charm meson, D + → K - π + π + (and charge conjugate), using the full 10.4 fb - 1 sample of p p ¯ collisions at s = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B → D processes) using input from Monte Carlo simulation. We measure A C P = [ - 0.16 ± 0.15 ( stat ) ± 0.09 ( syst ) ] % , which is consistent with zero, as expected from the standard model prediction of C P conservation, and is the most precise measurement of this quantity to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurement of the W Boson Production Charge Asymmetry in p p ¯ → W + X → e ν + X Events at s = 1.96 TeV

We present a measurement of the W boson production charge asymmetry in p$\bar{p}$→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.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗