Closing the SU(3)L⊗U(1)XSU(3)_L\otimes U(1)_X Symmetry at Electroweak Scale

We show that some models with $SU(3)_C\otimes SU(3)_L\otimes U(1)_X$ gauge symmetry can be realized at the electroweak scale and that this is a consequence of an approximate global $SU(2)_{L+R}$ symmetry. This symmetry implies a condition among the vacuum expectation value of one of the neutral Higgs scalars, the $U(1)_X$'s coupling constant, $g_X$, the sine of the weak mixing angle $\sin\theta_W$, and the mass of the $W$ boson, $M_W$. In the limit in which this symmetry is valid it avoids the tree level mixing of the $Z$ boson of the Standard Model with the extra $Z^\prime$ boson. We have verified that the oblique $T$ parameter is within the allowed range indicating that the radiative corrections that induce such a mixing at the 1-loop level are small. We also show that a $SU(3)_{L+R}$ custodial symmetry implies that in some of the models we have to include sterile (singlets of the 3-3-1 symmetry) right-handed neutrinos with Majorana masses, being the see-saw mechanism mandatory to obtain light active neutrinos. Moreover, the approximate $SU(2)_{L+R}\subset SU(3)_{L+R}$ symmetry implies that the extra non-standard particles of these 3-3-1 models can be considerably lighter than it had been thought before so that new physics can be really just around the corner.Comment: 32 pages, no figure, RevTeX. Some typos correcte

Identificação varietal de algumas videiras cultivadas no Rio Grande do Sul.

Esta publicraçã contém a descrição ampelográfica das copas que comumente apresentam dificuldades para identificação. bem como dos principais porta-enxertos difundidas na MRH 311.bitstream/item/40787/1/cir11.pdf2. ed. rev

Caracterização da macrofauna invertebrada do solo sob diferentes fitofisionomias do Pantanal.

bitstream/item/66197/1/31473.pdfFERTBIO

X, Y and Z States

Many new states in the charmonium mass region were recently discovered by BaBar, Belle, CLEO-c, CDF, D0, BESIII, LHCb and CMS Collaborations. We use the QCD Sum Rule approach to study the possible structure of some of these states.Comment: Contribution for the proceedings of the "XII Quark Confinement and the Hadron Spectrum - CONF12" conferenc

DigitalPinDirector: A digital pinscreen editor for images and realtime animation in low cost personal computers

This paper presents the main characteristics of the traditional Pinscreen, the way it works, its problems and results achieved. The first Digital Pinscreen system is presented, along with its main characteristics and limitations. The rest of the paper describes and presents the DigitalPinDirector: a system that enables a full and true creative access to the unique visual and animation characteristics of the Pinscreen.info:eu-repo/semantics/publishedVersio

Adubação Verde na Produção Orgânica de Abacaxi na Chapada Diamantina, BA.

A prática da adubação verde promove benefícios ao solo, dentre estes, aumenta os teores de matéria orgânica, favorece a ciclagem de nutrientes e mantém a cobertura do solo. O presente trabalho objetivou avaliar a produção de biomassa vegetal e os estoques de carbono (C) e macronutrientes na matéria seca de diferentes espécies de adubos verdes utilizados em pré-plantio na cultura do abacaxi