Neutrinos masses in a multi-higgs model with A 4 symmetry

Presently it is well known that neutrino oscillation data are well described by massive neutrinos and their mixing. This suggests changes in the standard model (SM) and makes the flavor physics even more interesting. Recently, it has been proposed a multi-Higgs extension of the SM with Abelian and non-Abelian discrete symmetries which seeks to explain the origin of the masses and mixing matrices in all charge sectors. © 2012 Elsevier B.V.

Quasi-Dirac neutrinos in a model with local B - L symmetry

In a model with B - L gauge symmetry, right-handed neutrinos may have exotic local B - L charge assignments: two of them with B - L = -4 and the other one having B - L = 5. Then, it is natural to accommodate the right-handed neutrinos with the same B - L charge in a doublet of the discrete S3 symmetry, and the third one in a singlet. If the Yukawa interactions involving right-handed neutrinos are invariant under S3, the quasi-Dirac neutrino scheme arises naturally in this model. However, we will show how in this scheme it is possible to give a value for θ13 in agreement with the Daya Bay results. For example the S3 symmetry has to be broken in the Yukawa interactions involving right-handed charged leptons. © 2013 IOP Publishing Ltd.

Local attractors, degeneracy and analyticity: Symmetry effects on the locally coupled Kuramoto model

In this work we study the local coupled Kuramoto model with periodic boundary conditions. Our main objective is to show how analytical solutions may be obtained from symmetry assumptions, and while we proceed on our endeavor we show apart from the existence of local attractors, some unexpected features resulting from the symmetry properties, such as intermittent and chaotic period phase slips, degeneracy of stable solutions and double bifurcation composition. As a result of our analysis, we show that stable fixed points in the synchronized region may be obtained with just a small amount of the existent solutions, and for a class of natural frequencies configuration we show analytical expressions for the critical synchronization coupling as a function of the number of oscillators, both exact and asymptotic. © 2013 Elsevier Ltd. All rights reserved.

Chiral symmetry, massive gluons and confinement

It is quite difficult to obtain non-trivial chiral symmetry breaking solutions for the quark gap equation in the presence of dynamically generated gluon masses. An effective confining propagator has recently been proposed by Cornwall in order to solve this problem. We study phenomenological consequences of this approach, showing its compatibility with the experimental data. We argue that this confining propagator should be restricted to a small region of momenta, leading to effective four-fermion interactions at low energy. © 2013 American Institute of Physics.

Study of the ℤ3 symmetry in QCD at finite temperature and chemical potential using a worm algorithm

Traditional Monte Carlo simulations of QCD in the presence of a baryon chemical potential are plagued by the complex phase problem and new numerical approaches are necessary for studying the phase diagram of the theory. In this work we consider a ℤ3 Polyakov loop model for the deconfining phase transition in QCD and discuss how a flux representation of the model in terms of dimer and monomer variable solves the complex action problem. We present results of numerical simulations using a worm algorithm for the specific heat and two-point correlation function of Polyakov loops. Evidences of a first order deconfinement phase transition are discussed. © 2013 American Institute of Physics.

Quasi-homologous spherically symmetric branes and their symmetry breaking

We revisit the dynamical system-based approach of spherically symmetric vacuum braneworlds, pointing out and studying the existence of a transcritical bifurcation as the dark pressure parameter changes its sign, we analyze some consequences of not discard the brane cosmological constant. For instance, it is noteworthy that the existence of an isothermal state equation between the dark fluid parameters cannot be obtained via the requirement of a quasi-homologous symmetry of the vacuum. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

Cohomology ring of the brst operator associated to the sum of two pure spinors

In the study of the Type II superstring, it is useful to consider the BRST complex associated to the sum of two pure spinors. The cohomology of this complex is an infinite-dimensional vector space. It is also a finite-dimensional algebra over the algebra of functions of a single pure spinor. In this paper we study the multiplicative structure. © 2013 World Scientific Publishing Company.

Dynamical chiral symmetry breaking: the fermionic gap equation with dynamical gluon mass and confinement

Pós-graduação em Física - IFT

Excitonic instabilities and spontaneous time-reversal symmetry breaking on the honeycomb lattice

We elucidate the close relationship between spontaneous time-reversal symmetry breaking and the physics of excitonic instabilities in strongly correlated multiband systems. The underlying mechanism responsible for the spontaneous breaking of time-reversal symmetry in a many-body system is closely related to the Cooper-like pairing instability of interband particle-hole pairs involving higher-order symmetries. Studies of such pairing instabilities have, however, mainly focused on the mean-field aspects of the virtual exciton condensate, which ignores the presence of the underlying collective Fermi-liquid excitations. We show that this relationship can be exploited to systematically derive the coupling of the condensate order parameter to the intraband Fermi-liquid particle-hole excitations. Surprisingly, we find that the static susceptibility is negative in the ordered phase when the coupling to the Fermi-liquid collective excitations are included, suggesting that a uniform condensate of virtual excitons, with or without time-reversal breaking, is an unstable phase at T = 0.

Demixing and symmetry breaking in binary dipolar Bose-Einstein-condensate solitons

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

PT-symmetry management in oligomer systems

We study the effects of management of the PT-symmetric part of the potential within the setting of Schrodinger dimer and trimer oligomer systems. This is done by rapidly modulating in time the gain/loss profile. This gives rise to a number of interesting properties of the system, which are explored at the level of an averaged equation approach. Remarkably, this rapid modulation provides for a controllable expansion of the region of exact PT-symmetry, depending on the strength and frequency of the imposed modulation. The resulting averaged models are analysed theoretically and their exact stationary solutions are translated into time-periodic solutions through the averaging reduction. These are, in turn, compared with the exact periodic solutions of the full non-autonomous PT-symmetry managed problem and very good agreement is found between the two.

Aspects of semilocal BPS vortex in systems with Lorentz symmetry breaking

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Unitarity and nonrelativistic potential energy in a higher-order Lorentz symmetry breaking electromagnetic model

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dirac gaugions, R symmetry and the 125 GeV Higgs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

QCD chiral symmetry restoration with a large number of quarks in a model with a confining propagator and dynamically massive gluons

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)