847 research outputs found
with a production
The cross section of
process with a complete set of tree diagrams, 232 diagrams in the unitary
gauge, was calculated at the energy range of = 340 - 500 GeV by
using GRACE system. A main contribution to the cross section comes from
production, where and decay into and
, respectively. It was found that the
interference between the diagrams with production and those with
single- through pair production amounts to 10% at the
threshold energy region. In the energy region above twice of the top quark
mass, more than 95% of the cross section comes from the diagrams.Comment: 17 pages, 8 PostScript figures, LateX; To appear in Phys. Lett.
Testing the Higgs Sector of the Minimal Supersymmetric Standard Model at Large Hadron Colliders
We study the Higgs sector of the Minimal Supersymmetric Standard Model, in
the context of proton-proton collisions at LHC and SSC energies. We assume a
relatively heavy supersymmetric particle spectrum, and include recent results
on one-loop radiative corrections to Higgs-boson masses and couplings. We begin
by discussing present and future constraints from the LEP experiments. We then
compute branching ratios and total widths for the neutral () and charged
() Higgs particles. We present total cross-sections and event rates for
the important discovery channels at the LHC and SSC. Promising physics
signatures are given by , or or , , and followed by
, which should allow for an almost complete coverage
of the parameter space of the model.Comment: 51 pages, 30 figures (not enclosed and not available via e-mail
Unidades demonstrativas de produção de peixes em tanques-rede na Represa de Boa Esperança: alternativa de geração de renda às comunidades de pescadores e agricultores do Piauà e Maranhão.
bitstream/item/131197/1/Doc232.pd
Input-modulation as an alternative to conventional learning strategies
Animals use various strategies for learning stimulus-reward associations. Computational methods that mimic animal behaviour most commonly interpret learning as a high level phenomenon, in which the pairing of stimulus and reward leads to plastic changes in the final output layers where action selection takes place. Here, we present an alternative input-modulation strategy for forming simple stimulus-response associations based on reward. Our model is motivated by experimental evidence on modulation of early brain regions by reward signalling in the honeybee. The model can successfully discriminate dissimilar odours and generalise across similar odours, like bees do. In the most simplified connectionist description, the new input- modulation learning is shown to be asymptotically equivalent to the standard perceptron
Towards Open Access Publishing in High Energy Physics : Report of the SCOAP3 Working Party
This Report concerns the implementation of a process today supported by leading actors from the particle physics community, and worked through in detail by members of an international Working Party. The initiative offers an opportunity for the cost-effective dissemination of high-quality research articles in particle physics, enabling use of the new technologies of e-Science across the literature of High Energy physics
Prospects for heavy supersymmetric charged Higgs boson searches at hadron colliders
We investigate the production of a heavy charged Higgs boson at hadron
colliders within the context of the MSSM. A detailed study is performed for all
important production modes and basic background processes for the
t\bar{t}b\bar{b} signature. In our analysis we include effects of initial and
final state showering, hadronization, and principal detector effects. For the
signal production rate we include the leading SUSY quantum effects at high
\tan\beta>~ mt/mb. Based on the obtained efficiencies for the signal and
background we estimate the discovery and exclusion mass limits of the charged
Higgs boson at high values of \tan\beta. At the upgraded Tevatron the discovery
of a heavy charged Higgs boson (MH^+ >~ 200 GeV) is impossible for the
tree-level cross-section values. However, if QCD and SUSY effects happen to
reinforce mutually, there are indeed regions of the MSSM parameter space which
could provide 3\sigma evidence and, at best, 5\sigma charged Higgs boson
discovery at the Tevatron for masses M_H^+<~ 300 GeV and M_H^+<~ 250 GeV,
respectively, even assuming squark and gluino masses in the (500-1000) GeV
range. On the other hand, at the LHC one can discover a H^+ as heavy as 1 TeV
at the canonical confidence level of 5\sigma; or else exclude its existence at
95% C.L. up to masses ~ 1.5 TeV. Again the presence of SUSY quantum effects can
be very important here as they may shift the LHC limits by a few hundred GeV.Comment: Latex2e, 44 pages, 15 figures, 6 tables, uses JHEP3.sty, axodraw.sty.
Comments added. Discussion on QCD factors clarified. Added discussion on
uncertainties. Change of presentation of Tables 4 and 5 and Fig.6. Results
and conclusions unchanged. Version accepted in JHE
Life below water: conservation and responsible use of seas, oceans and coastal environments.
This chapter addresses the context in which this Agenda was created, the problems that SDG 14 intends to solve by 2030 and its 11 agreed targets, which include reducing marine pollution and sustainably managing marine and coastal ecosystems through conservation of coastal areas, regarded as nurseries of marine life. In addition, a brief description of the Brazilian context and the history of contributions of Embrapa to the targets of this SDG are presented.bitstream/item/219207/1/chapter1-2020.pd
Advances and future challenges.
This chapter, present a summary of problems raised throughout this book and solutions presented: what is the role of Embrapa in the conservation and use of seas and oceans and how this commitment is presented in the Company's Master Plan.bitstream/item/219209/1/chapter6-2020-.pd
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