Estimations for the Single Diffractive production of the Higgs boson at the Tevatron and the LHC

The single diffractive production of the standard model Higgs boson is computed using the diffractive factorization formalism, taking into account a parametrization for the Pomeron structure function provided by the H1 Collaboration. We compute the cross sections at next-to-leading order accuracy for the gluon fusion process, which includes QCD and electroweak corrections. The gap survival probability ($$) is also introduced to account for the rescattering corrections due to spectator particles present in the interaction, and to this end we compare two different models for the survival factor. The diffractive ratios are predicted for proton-proton collisions at the Tevatron and the LHC for the Higgs boson mass of $M_H$ = 120 GeV. Therefore, our results provide updated estimations for the diffractive ratios of the single diffractive production of the Higgs boson in the Tevatron and LHC kinematical regimes.Comment: 20 pages, 6 figures, 3 table

Mechanism of Reconnection on Kinetic Scales Based on Magnetospheric Multiscale Mission Observations

We examine the role that ions and electrons play in reconnection using observations from the Magnetospheric Multiscale (MMS) mission on kinetic ion and electron scales, which are much shorter than magnetohydrodynamic scales. This study reports observations with unprecedented high resolution that MMS provides for magnetic eld (7.8 ms) and plasma (30 ms for electrons and 150 ms for ions). We analyze and compare approaches to the magnetopause in 2016 November, to the electron diffusion region in the magnetotail in 2017 July followed by a current sheet crossing in 2018 July. Besides magnetic eld reversals, changes in the direction of the ow velocity, and ion and electron heating, MMS observed large uctuations in the electron ow speeds in the magnetotail. As expected from numerical simulations, we have veried that when the eld lines and plasma become decoupled a large reconnecting electric eld related to the Hall current (110 mV/m) is responsible for fast reconnection in the ion diffusion region. Although inertial accelerating forces remain moderate (12 mV/m), the electric elds resulting from the divergence of the full electron pressure tensor provide the main contribution to the generalized Ohms law at the neutral sheet (as large as 200 mV/m). In our view, this illustrates that when ions decouple electron physics dominates. The results obtained on kinetic scales may be useful for better understanding the physical mechanisms governing reconnection processes in various magnetized laboratory and space plasmas

Cnidaria, Scleractinia, Siderastreidae, Siderastrea siderea (Ellis and Solander, 1786): Hartt Expedition and the first record of a Caribbean siderastreid in tropical Southwestern Atlantic

Samples of Siderastrea collected by the geologist C. F. Hartt during expedition to Brazil (19th century), anddeposited at the National Museum of the Natural History, Smithsonian Institution, have been re-examined. Taxonomicalanalyses resulted in the identification of a colony of S. siderea from offshore northern Bahia state. Following recentstudies, the occurrence of Caribbean siderastreids to western South Atlantic provides new criteria to assess intra- andinterpopulational morphological variation of the endemic S. stellata, refuting historical trends of synonymizations possiblybiased by long-term taxonomical misunderstandings

Macrofauna edáfica associada a plantas de cobertura em plantio direto em um Latossolo Vermelho do Cerrado.

O objetivo deste trabalho foi caracterizar a macrofauna edáfica e avaliar o efeito de plantas de cobertura em plantio direto, nos principais grupos da macrofauna do solo, em duas épocas de avaliação em um Latossolo Vermelho distroférrico. O delineamento experimental foi o de blocos ao acaso, com oito tratamentos (plantas de cobertura) e quatro repetições. As plantas de cobertura: Crotalaria juncea, guandu-anão (Cajanus cajan), Stylosanthes guianensis, Brachiaria brizantha, B. brizantha consorciada com milho (Zea mays), milheto (Pennisetum glaucum), mombaça (Panicum maximum) e Sorghum bicolor foram cultivadas de novembro a abril. Em setembro de cada ano, foi realizado o plantio de feijão, em cultivo irrigado por pivô central. A área útil em cada parcela foi de 60 m². Amostras de solo na forma de monólitos (25x25 cm) foram retiradas aleatoriamente em cada parcela, para contagem da macrofauna, às profundidades de 0?10 cm e 10?20 cm, em abril e em setembro de 2005. Os grupos taxonômicos, identificados em ordem decrescente de densidade relativa, são: Formicidae, Oligochaeta, Dermaptera, Coleoptera, Hemiptera, Miriapoda, Isoptera, Araneae, Lepidoptera, Blattodea e larvas de Diptera. Crotalaria juncea apresentou maior densidade de macrofauna, seguida por B. Brizantha, B. Brizantha consorciada com milho, Sorghum bicolor, Stylosanthes guianensis, Cajanus Cajans, Pennisetum Glaucum e Panicum maximum. O uso das plantas de cobertura, associado à irrigação na avaliação de setembro, favorece a colonização do solo pela macrofauna

Perfilhamento de Eragrostis plana Ness sob estresse hídrico.

CONGREGA

Avaliação das características morfogênicas e estruturais de espécies forrageiras nativas do Sul do Brasil submetidas a diferentes condições hídricas.

JAI

Rural-urban migration in d-dimensional lattices

The rural-urban migration phenomenon is analyzed by using an agent-based computational model. Agents are placed on lattices which dimensions varying from d=2 up to d=7. The localization of the agents in the lattice define their social neighborhood (rural or urban) not being related to their spatial distribution. The effect of the dimension of lattice is studied by analyzing the variation of the main parameters that characterizes the migratory process. The dynamics displays strong effects even for around one million of sites, in higher dimensions (d=6, 7).Comment: 9 pages, 7 figures, to be published in International Journal of Modern Physics C 1