Decoupling Properties of MSSM particles in Higgs and Top Decays

We study the supersymmetric (SUSY) QCD radiative corrections, at the one-loop level, to $h^0$, $H^{\pm}$ and t quark decays, in the context of the Minimal Supersymmetric Standard Model (MSSM) and in the decoupling limit. The decoupling behaviour of the various MSSM sectors is analyzed in some special cases, where some or all of the SUSY mass parameters become large as compared to the electroweak scale. We show that in the decoupling limit of both large SUSY mass parameters and large CP-odd Higgs mass, the $\Gamma (h^0\to b \bar b)$ decay width approaches its Standard Model value at one loop, with the onset of decoupling being delayed for large $\tan\beta$ values. However, this decoupling does not occur if just the SUSY mass parameters are taken large. A similar interesting non-decoupling behaviour, also enhanced by $\tan\beta$, is found in the SUSY-QCD corrections to the $\Gamma (H^+\to t \bar b)$ decay width at one loop. In contrast, the SUSY-QCD corrections in the $\Gamma (t\to W^+ b)$ decay width do decouple and this decoupling is fast.Comment: 19 pages, 10 figures. Invited talk presented by M.J.Herrero at the 5th International Symposium on Radiative Corrections (RADCOR 2000) Carmel CA, USA, 11-15 September, 200

Quantum corrections to the MSSM h^0 b b-bar vertex: Decoupling limit

We consider the leading one-loop Yukawa-coupling corrections to the h^0 b b-bar coupling at O(m_t^2)in the MSSM in the decoupling limit. The decoupling behavior of the corrections from the various MSSM sectors is analyzed in the case of having some or all of the supersymmetric mass parameters and/or the CP-odd Higgs mass large as compared to the electroweak scale.Comment: LaTeX, 5 pages, 4 figures. To appear in the Proceedings of the "7th International Symposium on Radiative Corrections (RADCOR05)", Shonan Village, Japan, 200

Flavour physics at large tan(beta) with a Bino-like LSP

The MSSM with large tan(beta) and heavy squarks is a theoretically well motivated and phenomenologically interesting extension of the SM. This scenario naturally accommodates the (g-2)_\mu anomaly and the upper bound on the Higgs boson mass. In a wide region of the parameter space, visible non-standard effects are expected in a few low-energy observables, such as BR(B->tau nu), BR(B->l+ l-), BR(B->Xs gamma), and BR(mu->e gamma). We analyse the correlations of these non-standard effects under the additional assumption that the relic density of a Bino-like LSP accommodates the observed dark matter distribution.Comment: 19 pages, 7 figures; v2: published version (minor modifications

Conservação de recursos genéticos de mandioca (Manihot esculenta Crantz) no Brasil.

A cultura da mandioca (Manihot esculenta Crantz originou-se e completou a maioria de sua diversificação no continente latino-americano. Análises filogenéticas do gênero Manihot realizadas por Shall et al. (1994), baseadas em marcadores moleculares, indicaram que a mandioca originou-se na América do Sul, mais precisamente no Brasil. A mandioca apresenta uma ampla diversidade genética concentrada principalmente na América Latina e Caribe. Essa diversidade é resultado da seleção natural ocorrida durante a evolução da espécie, nas fases de pré e pós-domesticação. Nos diversos ambientes onde a mandioca se diversificou a seleção resultou numa ampla diversidade de clones com adaptação específica a determinados ecossistemas (Hershey, 1988), representada em sua maioria por variedades crioulas.bitstream/item/223456/1/Conservacao-de-recursos-geneticos.pd

Flavour Changing Neutral Higgs Boson Decays from Squark - Gluino Loops

We study the flavour changing neutral Higgs boson decays that can be induced from genuine supersymmetric particles at the one-loop level and within the context of the Minimal Supersymmetric Standard Model. We consider all the possible flavour changing decay channels of the three neutral Higgs bosons into second and third generation quarks, and focus on the Supersymmetric-QCD corrections from squark-gluino loops which are expected to provide the dominant contributions. We assume here the more general hypothesis for flavour mixing, where there is misalignment between the quark and squark sectors, leading to a flavour non-diagonal squark mass matrix. The form factors involved, and the corresponding Higgs partial decay widths and branching ratios, are computed both analytically and numerically, and their behaviour with the parameters of the Minimal Supersymmetric Standard Model and with the squark mass mixing are analyzed in full detail. The large rates found, are explained in terms of the non-decoupling behaviour of these squark-gluino loop corrections in the scenario with very large supersymmetric mass parameters. Our results show that if these decays are seen in future colliders they could provide clear indirect signals of supersymmetry.Comment: 32 Pages and 12 PostScript Level 2 Figures. Some references adde

Effective Higgs-quark-quark couplings from a heavy SUSY spectrum

In this paper we study the Yukawa Higgs-quark-quark interactions that are generated from radiative corrections of squarks and gluinos, in the Minimal Supersymmetric Standard Model. We compute the corrections to the effective action for Higgs and quark fields that are produced by explicit integration, in the path integral formalism, of all the squarks and gluinos, at the one-loop level and order $\alpha_s$. In addition, we consider the limit of nearly degenerate heavy squarks and gluinos, with masses much larger than the electroweak scale, and derive the effective Lagrangian containing all the relevant new local Higgs-quark-quark interactions. We show that these new interactions do remain non-vanishing, even in the case of infinitely heavy supersymmetric particles and, therefore, we demonstrate explicitly the non-decoupling behavior of squarks and gluinos in Higgs bosons physics. We present the set of new Yukawa couplings and finally derive the corresponding one-loop, order $\alpha_s$, corrections to the Higgs bosons partial decay widths into quarks.Comment: 21 pages, 1 ps figure. Version to appear in Phys. Rev,

SUSY-QCD corrections to the MSSM h0bbˉh^0 b \bar b vertex in the decoupling limit

We analyze the supersymmetric (SUSY) QCD contribution to the $h^0 b \bar{b}$ coupling at one loop in the Minimal Supersymmetric Model (MSSM) in the decoupling limit. Analytic expressions in the large SUSY mass region are derived and the decoupling behavior of the corrections is examined in various limiting cases, where some or all of the SUSY mass parameters become large. We show that in the decoupling limit of large SUSY mass parameters and large CP-odd Higgs mass, the $h^0 b \bar b$ coupling approaches its Standard Model value at one loop. However, the onset of decoupling is delayed when $\tan\beta$ is large. In addition, the one-loop SUSY-QCD corrections decouple if the masses of either the bottom squarks or the gluino are separately taken large; although the approach to decoupling is significantly slower in the latter case.Comment: 27 pages, 7 figures and 1 table in LaTeX2e format; with a few minor changes and updated reference

Productive Parvovirus B19 Infection of Primary Human Erythroid Progenitor Cells at Hypoxia Is Regulated by STAT5A and MEK Signaling but not HIFα

Human parvovirus B19 (B19V) causes a variety of human diseases. Disease outcomes of bone marrow failure in patients with high turnover of red blood cells and immunocompromised conditions, and fetal hydrops in pregnant women are resulted from the targeting and destruction of specifically erythroid progenitors of the human bone marrow by B19V. Although the ex vivo expanded erythroid progenitor cells recently used for studies of B19V infection are highly permissive, they produce progeny viruses inefficiently. In the current study, we aimed to identify the mechanism that underlies productive B19V infection of erythroid progenitor cells cultured in a physiologically relevant environment. Here, we demonstrate an effective reverse genetic system of B19V, and that B19V infection of ex vivo expanded erythroid progenitor cells at 1% O2 (hypoxia) produces progeny viruses continuously and efficiently at a level of approximately 10 times higher than that seen in the context of normoxia. With regard to mechanism, we show that hypoxia promotes replication of the B19V genome within the nucleus, and that this is independent of the canonical PHD/HIFα pathway, but dependent on STAT5A and MEK/ERK signaling. We further show that simultaneous upregulation of STAT5A signaling and down-regulation of MEK/ERK signaling boosts the level of B19V infection in erythroid progenitor cells under normoxia to that in cells under hypoxia. We conclude that B19V infection of ex vivo expanded erythroid progenitor cells at hypoxia closely mimics native infection of erythroid progenitors in human bone marrow, maintains erythroid progenitors at a stage conducive to efficient production of progeny viruses, and is regulated by the STAT5A and MEK/ERK pathways