e+e−→bbˉudˉμ−νˉμe^+e^- \to b \bar{b} u \bar{d} \mu^- \bar{\nu}_\mu with a ttˉt\bar{t} production

The cross section of $e^+e^- \to b \bar{b} u \bar{d} \mu^- \bar{\nu}_\mu$ process with a complete set of tree diagrams, 232 diagrams in the unitary gauge, was calculated at the energy range of $\sqrt{s}$ = 340 - 500 GeV by using GRACE system. A main contribution to the cross section comes from $t\bar{t}$ production, where $t$ and $\bar{t}$ decay into $bu\bar{d}$ and $\bar{b} \mu^- \bar{\nu}_{\mu}$, respectively. It was found that the interference between the diagrams with $t\bar{t}$ production and those with single-$t$ through $WW$ pair production amounts to 10% at the $t \bar{t}$ threshold energy region. In the energy region above twice of the top quark mass, more than 95% of the cross section comes from the $t\bar{t}$ 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 ($h,H,A$) and charged ($H^\pm$) 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 $h \to \gamma \gamma$, $H \to \gamma \gamma$ or $Z^* Z^*$ or $\tau^+ \tau^-$, $A \to \tau^+ \tau^-$, and $t \to b H^+$ followed by $H^+ \to \tau^+ \nu_{\tau}$, 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 Piauí e Maranhão.

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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