107 research outputs found
Monotonicity conditions for multirate and partitioned explicit Runge-Kutta schemes
Multirate schemes for conservation laws or convection-dominated problems seem to come in two Âżavors: schemes that are locally inconsistent, and schemes that lack mass-conservation. In this paper these two defects are discussed for one-dimensional conservation laws. Particular attention will be given to monotonicity properties of the multirate schemes, such as maximum principles and the total variation diminishing (TVD) property. The study of these properties will be done within the framework of partitioned Runge-Kutta methods. It will also be seen that the incompatibility of consistency and mass-conservation holds for âgenuineâ multirate schemes, but not for general partitioned methods
Search for W' bosons decaying to an electron and a neutrino with the D0 detector
This Letter describes the search for a new heavy charged gauge boson W'
decaying into an electron and a neutrino. The data were collected with the D0
detector at the Fermilab Tevatron proton-antiproton Collider at a
center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity
of about 1 inverse femtobarn. Lacking any significant excess in the data in
comparison with known processes, an upper limit is set on the production cross
section times branching fraction, and a W' boson with mass below 1.00 TeV can
be excluded at the 95% C.L., assuming standard-model-like couplings to
fermions. This result significantly improves upon previous limits, and is the
most stringent to date.Comment: submitted to Phys. Rev. Let
Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV
We present a study of events with Z bosons and jets produced at the Fermilab
Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV.
The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding
to the integrated luminosity of 0.4 fb-1 collected using the D0 detector.
Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross
section have been measured for n = 1 to 4 jet events. Our measurements are
found to be in good agreement with a next-to-leading order QCD calculation and
with a tree-level QCD prediction with parton shower simulation and
hadronization.Comment: 7 pages, 2 figures, slightly modified, submitted to Phys. Lett.
Search for Supersymmetry in Di-Photon Final States at sqrt{s} = 1.96 TeV
We report results of a search for supersymmetry (SUSY) with gauge-mediated
symmetry breaking in di-photon events collected by the D0 experiment at the
Fermilab Tevatron Collider in 2002--2006. In 1.1 fb of data, we find no
significant excess beyond the background expected from the standard model and
set the most stringent lower limits to date for a standard benchmark model on
the lightest neutralino and chargino masses of 125 GeV and 229 GeV,
respectively, at 95% confidence
Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV
A data sample corresponding to an integrated luminosity of 2.1 fb-1 collected
by the D0 detector at the Fermilab Tevatron Collider was analyzed to search for
squarks and gluinos produced in ppbar collisions at a center-of-mass energy of
1.96 TeV. No evidence for the production of such particles was observed in
topologies involving jets and missing transverse energy, and 95% C.L. lower
limits of 379 GeV and 308 GeV were set on the squark and gluino masses,
respectively, within the framework of minimal supergravity with tan(beta)=3,
A0=0, and mu<0. The corresponding previous limits are improved by 54 GeV and 67
GeV
Search for scalar leptoquarks in the acoplanar jet topology in ppbar collisions at sqrt(s)=1.96 TeV
A search for leptoquarks has been performed in 310 pb-1 of data from ppbar
collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector
at the Fermilab Tevatron Collider. The topology analyzed consists of acoplanar
jets with missing transverse energy. The data show good agreement with standard
model expectations, and a lower mass limit of 136 GeV has been set at the 95%
C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.Comment: Minor changes in v2 to match the published version, 8 pages, 5
figure
Measurement of B(t->Wb)/B(t->Wq) at sqrt(s) = 1.96 TeV
We present the measurement of R = B(t->Wb)/B(t->Wq) in ppbar collisions at
sqrt(s) = 1.96 TeV, using 230 pb-1 of data collected by the DO experiment at
the Fermilab Tevatron Collider. We fit simultaneously R and the number of
selected top quark pairs (ttbar), to the number of identified b-quark jets in
events with one electron or one muon, three or more jets, and high transverse
energy imbalance. To improve sensitivity, kinematical properties of events with
no identified b-quark jets are included in the fit. We measure R = 1.03 +0.19
-0.17 (stat+syst), in good agreement with the standard model. We set lower
limits of R > 0.61 and |V_tb| > 0.78 at 95% confidence level.Comment: 7 pages, 1 figure submitted to Phys. Rev. Let
Search for the lightest scalar top quark in events with two leptons in p-pbar collisions at sqrt(s) = 1.96 TeV
Data collected by the D0 detector at a p-pbar center-of-mass energy of 1.96
TeV at the Fermilab Tevatron Collider have been used to search for pair
production of the lightest supersymmetric partner of the top quark decaying
into . The search is performed in the
and final states. No evidence for this process has been found in data
samples of approximately 400 pb^-1. The domain in the
[] plane excluded at the 95% C.L. is
substantially extended by this search.Comment: 9 pages, 11 figures. Selection-cut layouts slightly different than in
PL
Search for the Standard Model Higgs Boson in the ZH --> neutrino-neutrino-b-b channel
We report a search for the standard model (SM) Higgs boson based on data
collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding
to an integrated luminosity of 260 pb^-1. We study events with missing
transverse energy and two acoplanar b-jets, which provide sensitivity to the ZH
production cross section in the neutrino-neutrino-b-b channel and to WH
production, when the lepton from the W -> lepton+neutrino decay is undetected.
The data are consistent with the SM background expectation, and we set 95% C.L.
upper limits on sigma(p p-bar -> ZH/WH) x B(H -> b b-bar) from 3.4/8.3 to
2.5/6.3 pb, for Higgs masses between 105 and 135 GeV.Comment: submitted to Phys. Rev. Letter
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