Probing doubly charged Higgs in e+e−e^+ e^- Colliders in 3-3-1 Model

The SU(3)_L\otimesU(1)_N electroweak model predicts new Higgs bosons beyond the one of the standard model. In this work we investigate the signature and production of doubly charged Higgs bosons in the $e^-e^+$ International Linear Collider and in the CERN Linear Collider. We compute the branching ratios for the doubly charged gauge bosons of the model.Comment: 17 pages, 12 figure

Signatures of Double Charged Higgs in SU(3)L⊗U(1)NSU(3)_L\otimes U(1)_N model

The scalar sector of the simplest version of the 3-3-1 electroweak models is constructed with three Higgs triplets only. We show that a relation involving two of the constants of the Higgs potential, two vacuum expectation values of the neutral scalars and the mass of the doubly charged Higgs boson leads to important information concerning the signals of this scalar particle.Comment: 6 pages and 9 figure

Data mining with neural networks and support vector machines using the R/rminer tool

We present rminer, our open source library for the R tool that facilitates the use of data mining (DM) algorithms, such as neural Networks (NNs) and support vector machines (SVMs), in classification and regression tasks. Tutorial examples with real-world problems (i.e. satellite image analysis and prediction of car prices) were used to demonstrate the rminer capabilities and NN/SVM advantages. Additional experiments were also held to test the rminer predictive capabilities, revealing competitive performances.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/EIA/64541/200

Possibilities for charged Higgs bosons at the LHC in a SU(3)_L\otimesU(1)_N Model

We have studied the branching ratios of doubly charged Higgs bosons at the LHC using a version of the SU(3)_L\otimesU(1)_N electroweak model. At the end of this work we have made a very simple plotting comparating the total cross section of this model using Drell-Yan, gluon-gluon fusion and Left-right symmetric model.Comment: Talk given at 18th International IUPAP Conference on Few-Body Problems in Physics (FB18), Santos, Sao Paulo, Brazil, 21-26 Aug 200

Acausality in Gowdy spacetimes

We present a parametrization of $T^3$ and $S^1\times S^2$ Gowdy cosmological models which allows us to study both types of topologies simultaneously. We show that there exists a coordinate system in which the general solution of the linear polarized special case (with both topologies) has exactly the same functional dependence. This unified parametrization is used to investigate the existence of Cauchy horizons at the cosmological singularities, leading to a violation of the strong cosmic censorship conjecture. Our results indicate that the only acausal spacetimes are described by the Kantowski-Sachs and the Kerr-Gowdy metrics.Comment: Typos corrected, 10 pages. Dedicated to Michael P. Ryan on the occasion of his 60-th birthda

Métodos de análise orgânica do café. II. Comparação entre métodos de determinação da cafeína em café verde

The micro Bailey-Andrew method (official of A. O. A. C, 1970) and the proposed reference method of Navellier et al. (1969) for determination of caffeine in coffee were studied. For the caffeine extraction and purification, it was followed the A. O. A. C. (1970) and Navellier et al. (1969) procedures, without modification, but for the caffeine estimation, the weight, total nitrogen, spectrofotometry with base line correction and the peak at 273 nm were used. The following conclusion could be drawn: a) the determination of caffeine by using the weight should not be applied by either methods, because it gave high values in comparison with nitrogen and spectrophotometry, and because of the high coeficient of variation. b) the extration and purification procedures used by Navellier don't remove all nitrogenous materials which interferes on the total nitrogen determination, whereas the Navellier spectrofotometry method gave similar results with the A. O. A. C. (1970) nitrogen and spectrophotometric determinations. c) no diference was found for nitrogen and spetrophotometric (with correction of base line) determination of caffeine when A. O. A. C. (1970) extraction and purification procedures were used.O método micro Bailey-Andrew, oficial da A. O. A, C. (1970) e o proposto por NAVELLIER et al. (1969) para determinação de cafeína em café, foram comparados. Para extração e purificação seguiu-se os dois métodos citados e para a determinação propriamente dita utilizou-se o peso, nitrogênio total, espectrofotometria com correção da linha de base e o pico à 273 nm. As seguintes conclusões foram tiradas: a) A determinação por pesagem não deve ser utilizada para nenhum dos dois métodos de extração e purificação, pois além dos valores encontrados serem bem acima dos reais, os coeficientes de variação também foram altos. b) O método de extração e purificação de NAVELLIER et al. (1969) não consegue remover interferentes nitrogenados, mas talvez possa ser utilizado quando a cafeína é determinada por espectrofotometria com correção da linha de base. c) Não houve diferença significativa entre a determinação da cafeína pelo nitrogênio e espectrofotometria com correlação da linha de base quando se seguiu a extração e purificação da A, O. A. C. (1970)

Millisecond-range electron spin memory in singly-charged InP quantum dots

We report millisecond-range spin memory of resident electrons in an ensemble of InP quantum dots (QDs) under a small magnetic field of 0.1 T applied along the optical excitation axis at temperatures up to about 5 K. A pump-probe photoluminescence (PL) technique is used for optical orientation of electron spins by the pump pulses and for study of spin relaxation over the long time scale by measuring the degree of circular polarization of the probe PL as a function of pump-probe delay. Dependence of spin decay rate on magnetic field and temperature suggests two-phonon processes as the dominant spin relaxation mechanism in this QDs at low temperatures.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

Searching for doubly charged Higgs bosons at the LHC in a 3-3-1 Model

Using a peculiar version of the SU(3)L x U(1)N electroweak model, we investigate the production of doubly charged Higgs boson at the Large Hadron Collider. Our results include branching ratio calculations for the doubly charged Higgs and for one of the neutral scalar bosons of the model.Comment: 19 pages, 3 figure

Decoherence times of universal two-qubit gates in the presence of broad-band noise

The controlled generation of entangled states of two quantum bits is a fundamental step toward the implementation of a quantum information processor. In nano-devices this operation is counteracted by the solid-state environment, characterized by a broadband and non-monotonic power spectrum, often 1/f at low frequencies. For single-qubit gates, incoherent processes due to fluctuations acting on different time scales result in peculiar short- and long-time behavior. Markovian noise gives rise to exponential decay with relaxation and decoherence times, T1 and T2, simply related to the symmetry of the qubit-environment coupling Hamiltonian. Noise with the 1/f power spectrum at low frequencies is instead responsible for defocusing processes and algebraic short-time behavior. In this paper, we identify the relevant decoherence times of an entangling operation due to the different decoherence channels originating from solid-state noise. Entanglement is quantified by concurrence, which we evaluate in an analytic form employing a multi-stage approach. The 'optimal' operating conditions of reduced sensitivity to noise sources are identified. We apply this analysis to a superconducting \sqrt{i-SWAP} gate for experimental noise spectra.Comment: 35 pages, 11 figure