Bounds on Z′Z^\prime from 3-3-1 model at the LHC energies

The Large Hadron Collider will restart with higher energy and luminosity in 2015. This achievement opens the possibility of discovering new phenomena hardly described by the Standard Model, that is based on two neutral gauge bosons: the photon and the $Z$. This perspective imposes a deep and systematic study of models that predicts the existence of new neutral gauge bosons. One of such models is based on the gauge group $SU(3)_C \times SU(3)_L \times U(1)_N$ called 3-3-1 model for short. In this paper we perform a study with $Z^\prime$ predicted in two versions of the 3-3-1 model and compare the signature of this resonance in each model version. By considering the present and future LHC energy regimes, we obtain some distributions and the total cross section for the process $p + p \longrightarrow \ell^{+} + \ell^{-} + X$. Additionally, we derive lower bounds on $Z^\prime$ mass from the latest LHC results. Finally we analyze the LHC potential for discovering this neutral gauge boson at 14 TeV center-of-mass energy.Comment: 6 pages, 9 figures, 2 table

The Role of the Brain in the Pathogenesis and Physiology of Polycystic Ovary Syndrome (PCOS).

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder, affecting at least 10% of women of reproductive age. PCOS is typically characterized by the presence of at least two of the three cardinal features of hyperandrogenemia (high circulating androgen levels), oligo- or anovulation, and cystic ovaries. Hyperandrogenemia increases the severity of the condition and is driven by increased luteinizing hormone (LH) pulse secretion from the pituitary. Indeed, PCOS women display both elevated mean LH levels, as well as an elevated frequency of LH pulsatile secretion. The abnormally high LH pulse frequency, reflective of a hyperactive gonadotropin-releasing hormone (GnRH) neural circuit, suggests a neuroendocrine basis to either the etiology or phenotype of PCOS. Several studies in preclinical animal models of PCOS have demonstrated alterations in GnRH neurons and their upstream afferent neuronal circuits. Some rodent PCOS models have demonstrated an increase in GnRH neuron activity that correlates with an increase in stimulatory GABAergic innervation and postsynaptic currents onto GnRH neurons. Additional studies have identified robust increases in hypothalamic levels of kisspeptin, another potent stimulator of GnRH neurons. This review outlines the different brain and neuroendocrine changes in the reproductive axis observed in PCOS animal models, discusses how they might contribute to either the etiology or adult phenotype of PCOS, and considers parallel findings in PCOS women

Two definitions of the electric polarizability of a bound system in relativistic quantum theory

For the electric polarizability of a bound system in relativistic quantum theory, there are two definitions that have appeared in the literature. They differ depending on whether or not the vacuum background is included in the system. A recent confusion in this connection is clarified

Fermion masses in a model for spontaneous parity breaking

In this paper we discuss a left-right symmetric model for elementary particles and their connection with the mass spectrum of elementary fermions. The model is based on the group $SU(2)_L\otimes SU(2)_R\otimes U(1)$. New mirror fermions and a minimal set of Higgs particles that breaks the symmetry down to $U(1)_{em}$ are proposed. The model can accommodate a consistent pattern for charged and neutral fermion masses as well as neutrino oscillations. An important consequence of the model is that the connection between the left and right sectors can be done by the neutral vector gauge bosons Z and a new heavy Z'.Comment: 7 pages, 3 figures. Accepted in Eur. Phys. J.

Vector- and Scalar-Bilepton Pair Production in Hadron Colliders

We study the double-charged vector-bilepton pair production and double-charged scalar-bilepton pair production {\it via} $p + p \longrightarrow Y^{++} + Y^{--} + X$ and $p + p \longrightarrow S_1^{++} + S_1^{--} + X$, where $Y$ and $S_1$ are vector and scalar bileptons respectively, in the framework of the minimal version of the 3-3-1 model. We compute the photon, $Z$, and $Z^\prime$ s-channel contributions for the elementary process of bilepton scalar pair production, and to keep the correct unitarity behavior for the elementary $q \bar q$ interaction, we include the exotic quark t-channel contribution in the vector-bilepton pair production calculation. We explore a mass range for $Z^\prime$ and we fix the exotic quark mass within the experimental bounds. In this model, the vector-bilepton mass is directly related to $M_{Z^\prime}$ and we consider scalar mass values around the vector-bilepton mass. We show that the total cross section for vector-bilepton production is 3 orders of magnitude larger than for scalar pair production for $\sqrt s= 7$ TeV and 14 TeV and we obtain the number of events for the proposed LHC luminosities as a function of the bilepton mass. In addition we present some invariant mass and transverse momentum distributions. When comparing these distributions we observe quite different behavior providing the determination of the bilepton nature. We conclude that one can disentangle the production rates and that the LHC can be capable of detecting these predicted particles as a signal for new physics.Comment: 29 pages, 18 figures, 4 table

Top quark forward-backward asymmetry from the 3−3−13-3-1 model

The forward-backward asymmetry $A_{FB}$ in top quark pair production, measured at the Tevatron, is probably related to the contribution of new particles. The Tevatron result is more than a $2\sigma$ deviation from the standard model prediction and motivates the application of alternative models introducing new states. However, as the standard model predictions for the total cross section $\sigma_{tt}$ and invariant mass distribution $M_{tt}$ for this process are in good agreement with experiments, any alternative model must reproduce these predictions. These models can be placed into two categories: One introduces the s-channel exchange of new vector bosons with chiral couplings to the light quarks and to the top quark and another relies on the t-channel exchange of particles with large flavor-violating couplings in the quark sector. In this work we employ a model which introduces both s- and t-channel nonstandard contributions for the top quark pair production in proton antiproton collisions. We use the minimal version of the $SU(3)_C \otimes SU(3)_L \otimes U (1)_X$ model (3-3-1 model) that predicts the existence of a new neutral gauge boson, called $Z^\prime$. This gauge boson has both flavor-changing couplings to up and top quarks and chiral coupling to the light quarks and to the top quark. This very peculiar model coupling can correct the $A_{FB}$ for top quark pair production for two ranges of $Z^\prime$ mass while leading to cross section and invariant mass distribution quite similar to the standard model ones. This result reinforces the role of the 3-3-1 model for any new physics effect.Comment: 12 pages, 4 figures, 2 table

Padrões da distribuição espacial de queimadas no Estado de Mato Grosso.

The accelerated rate of land usage and the heightened incidence of fire points as historically seen in the legal Amazon region have reached alarming proportions and have attracted the attention of politicians, environmentalists and society in general. Different policies, strategies and monitoring and control actions have been proposed, with the objective of containing the advance of the agricultural frontier on remanent areas of natural vegetation, more specifically on Humid Tropical Forest areas. The State of Mato Grosso, located in the Legal Amazon Region, presents special characteristics for the understanding of relationships between land use or land cover and the incidence of burns due to the convergence of important environmental diversity and socioeconomic actors. This paper focuses on the dynamics of burns in this state, by identifying some of the principal contributing factors based on spatial-statistical analysis. The results show the existence of different spacial and temporal patterns that influence the occurrence of fires. These patterns point to the limitations of simplistic and generalized adaptation of localized information and burn quantification, whatever their spacial delimitation, for the purpose of elaborating public policies that aim to definitively change ou eradicate the chronic emergency stage of fires occurrence in the Legal Amazon Region in Brazil

Dynamical complexity of discrete time regulatory networks

Genetic regulatory networks are usually modeled by systems of coupled differential equations and by finite state models, better known as logical networks, are also used. In this paper we consider a class of models of regulatory networks which present both discrete and continuous aspects. Our models consist of a network of units, whose states are quantified by a continuous real variable. The state of each unit in the network evolves according to a contractive transformation chosen from a finite collection of possible transformations, according to a rule which depends on the state of the neighboring units. As a first approximation to the complete description of the dynamics of this networks we focus on a global characteristic, the dynamical complexity, related to the proliferation of distinguishable temporal behaviors. In this work we give explicit conditions under which explicit relations between the topological structure of the regulatory network, and the growth rate of the dynamical complexity can be established. We illustrate our results by means of some biologically motivated examples.Comment: 28 pages, 4 figure