4,369 research outputs found
Demonstração de mecanismo de resistência e da presença de genes diferentes de resistência a Ramularia areola em dois genótipos do algodoeiro.
Semiclassical coherent state propagator for systems with spin
We derive the semiclassical limit of the coherent state propagator for
systems with two degrees of freedom of which one degree of freedom is canonical
and the other a spin. Systems in this category include those involving
spin-orbit interactions and the Jaynes-Cummings model in which a single
electromagnetic mode interacts with many independent two-level atoms. We
construct a path integral representation for the propagator of such systems and
derive its semiclassical limit. As special cases we consider separable systems,
the limit of very large spins and the case of spin 1/2.Comment: 19 pages, no figure
GeantV: Results from the prototype of concurrent vector particle transport simulation in HEP
Full detector simulation was among the largest CPU consumer in all CERN
experiment software stacks for the first two runs of the Large Hadron Collider
(LHC). In the early 2010's, the projections were that simulation demands would
scale linearly with luminosity increase, compensated only partially by an
increase of computing resources. The extension of fast simulation approaches to
more use cases, covering a larger fraction of the simulation budget, is only
part of the solution due to intrinsic precision limitations. The remainder
corresponds to speeding-up the simulation software by several factors, which is
out of reach using simple optimizations on the current code base. In this
context, the GeantV R&D project was launched, aiming to redesign the legacy
particle transport codes in order to make them benefit from fine-grained
parallelism features such as vectorization, but also from increased code and
data locality. This paper presents extensively the results and achievements of
this R&D, as well as the conclusions and lessons learnt from the beta
prototype.Comment: 34 pages, 26 figures, 24 table
Outros equipamentos e métodos.
Neste capítulo são apresentados resultados do desenvolvimento de outros equipamentos e métodos não-convencionais realizados pela EMBRAPA-CNPDIA e demais instituições colaboradoras, para atender às demandas julgadas importantes para o avanço da pesquisa agropecuária. Cada equipamento ou método mostrado consta de uma introdução ao assunto, a abordagem do problema, uma breve descrição de como o equipamento ou método contribuiu para a solução, incluindo resultados e recomendações. O texto é ilustrado por figuras, diagramas e fotos, evitando-se o aprofundamento detalhado do tema, o que pode ser obtido pelas referências mencionadas para cada tópico tratado. Esta colocação mais abrangente tem por objetivo mostrar o potencial que os instrumentos aqui apresentados dispõem para enfocar e resolver problemas com o uso de equipamentos e métodos não-convencionais
Search for the standard model and a fermiophobic Higgs boson in diphoton final states
We present a search for the standard model Higgs boson and a fermiophobic
Higgs boson in the diphoton final states based on 8.2 fb-1 of ppbar collisions
collected with the D0 detector at the Fermilab Tevatron Collider. No excess of
data above background predictions is observed and upper limits at the 95% C.L.
on the cross section multiplied by the branching fraction are set which are the
most restrictive to date. A fermiophobic Higgs boson with a mass below 112.9
GeV is excluded at the 95% C.L.Comment: 12 pages, 21 figures, submitted to PR
Direct measurement of the mass difference between top and antitop quarks
We present a direct measurement of the mass difference between top and
antitop quarks (dm) in lepton+jets top-antitop final states using the "matrix
element" method. The purity of the lepton+jets sample is enhanced for
top-antitop events by identifying at least one of the jet as originating from a
b quark. The analyzed data correspond to 3.6 fb-1 of proton-antiproton
collisions at 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron
Collider. The combination of the e+jets and mu+jets channels yields dm = 0.8
+/- 1.8 (stat) +/- 0.5 (syst) GeV, which is in agreement with the standard
model expectation of no mass difference.Comment: submitted to Phys. Rev.
Zgamma production and limits on anomalous ZZgamma and Zgammagamma couplings in ppbar collisions at sqrt(s)=1.96 TeV
We present a measurement of ppbar->Zgamma->ll+gamma (l = e, mu) production
with a data sample corresponding to an integrated luminosity of 6.2 fb^{-1}
collected by the D0 detector at the Fermilab Tevatron ppbar Collider. The
results of the electron and muon channels are combined, and we measure the
total production cross section and the differential cross section
dsigma/dp_T^gamma, where p_T^gamma is the momentum of the photon in the plane
transverse to the beamline. 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 ZZgamma
and Zgammagamma couplings
Search for first generation leptoquark pair production in the electron + missing energy + jets final state
We present a search for the pair production of first generation scalar
leptoquarks (LQ) in data corresponding to an integrated luminosity of 5.4
fb collected with the D0 detector at the Fermilab Tevatron Collider in
ppbar collisions at TeV. In the channel , where q, q' are u or d quarks, no significant excess
of data over background is observed, and we set a 95% C.L. lower limit of 326
GeV on the leptoquark mass, assuming equal probabilities of leptoquark decays
to eq and .Comment: 7 pages, 6 figures, submitted to PRD-R
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