Results for "F. Arroja"

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CMB statistical anisotropy from noncommutative gravitational wavesJan 30 2014Jul 27 2014Primordial statistical anisotropy is a key indicator to investigate early Universe models and has been probed by the cosmic microwave background (CMB) anisotropies. In this paper, we examine tensor-mode CMB fluctuations generated from anisotropic gravitational ... More
Living with ghosts in Horava-Lifshitz gravityJan 20 2016May 23 2016We consider the branch of the projectable Horava-Lifshitz model which exhibits ghost instabilities in the low energy limit. It turns out that, due to the Lorentz violating structure of the model and to the presence of a finite strong coupling scale, the ... More
On the four-dimensional effective theories in brane-worldsDec 08 2008Models with extra dimensions have attracted much interest recently because they may provide the solution for long standing problems in physics. One interesting and very attractive idea is that our visible universe is confined to a four-dimensional hypersurface ... More
Non-gaussianity from the trispectrum in general single field inflationFeb 08 2008Nov 28 2008We compute the fourth order action in perturbation theory for scalar and second order tensor perturbations for a minimally coupled single field inflationary model, where the inflaton's lagrangian is a general function of the field's value and its kinetic ... More
A note on the role of the boundary terms for the non-Gaussianity in general k-inflationMar 06 2011Jun 29 2011In this short note we clarify the role of the boundary terms in the calculation of the leading order tree-level bispectrum in a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of ... More
Pathological behaviour of the scalar graviton in Hořava-Lifshitz gravityOct 11 2009Apr 12 2010We confirm the recent claims that, in the infrared limit of Ho\v{r}ava-Lifshitz gravity, the scalar graviton becomes a ghost if the sound speed squared is positive on the flat de Sitter and Minkowski background. In order to avoid the ghost and tame the ... More
Moduli instability in warped compactification - 4D effective theory approachFeb 07 2006Jun 14 2006We consider a 5D BPS dilatonic two brane model which reduces to the Randall-Sundrum model or the Horava-Witten theory for a particular choice of parameters. Recently new dynamical solutions were found by Chen et al., which describe a moduli instability ... More
Strong scale dependent bispectrum in the Starobinsky model of inflationApr 29 2012We compute analytically the dominant contribution to the tree-level bispectrum in the Starobinsky model of inflation. In this model, the potential is vacuum energy dominated but contains a subdominant linear term which changes the slope abruptly at a ... More
A note on the equivalence of a barotropic perfect fluid with a K-essence scalar fieldFeb 06 2010Jul 05 2010In this short note, we obtain the necessary and sufficient condition for a class of non-canonical single scalar field models to be exactly equivalent to barotropic perfect fluids, under the assumption of an irrotational fluid flow. An immediate consequence ... More
Large and strong scale dependent bispectrum in single field inflation from a sharp feature in the massJun 27 2011Jul 13 2011We study an inflationary model driven by a single minimally coupled standard kinetic term scalar field with a step in its mass modeled by an Heaviside step function. We present an analytical approximation for the mode function of the curvature perturbation, ... More
On the full quantum trispectrum in multi-field DBI inflationJul 14 2009Oct 20 2009We compute the leading order connected four-point function of the primordial curvature perturbation coming from the four-point function of the fields in multi-field DBI inflation models. We confirm that the consistency relations in the squeezed limit ... More
Non-gaussianity from the bispectrum in general multiple field inflationJun 04 2008We study the non-gaussianity from the bispectrum in multi-field inflation models with a general kinetic term. The models include the multi-field K-inflation and the multi-field Dirac-Born-Infeld (DBI) inflation as special cases. We find that, in general, ... More
On the 4D effective theory in warped compactifications with fluxes and branesJul 20 2006We present a systematic way to derive the four-dimensional effective theories for warped compactifications with fluxes and branes in the ten-dimensional type IIB supergravity. The ten-dimensional equations of motion are solved using the gradient expansion ... More
Cosmological matching conditions for gravitational waves at second orderJul 21 2009Jan 06 2010We compute the second-order matching conditions for tensor metric perturbations at an abrupt change in the equation of state. For adiabatic perturbations on large scales the matching hypersurface coincides with a uniform-density hypersurface. We show ... More
Cosmological perturbations in mimetic Horndeski gravityDec 29 2015Jul 20 2016We study linear scalar perturbations around a flat FLRW background in mimetic Horndeski gravity. In the absence of matter, we show that the Newtonian potential satisfies a second-order differential equation with no spatial derivatives. This implies that ... More
Singular Instantons in Eddington-inspired-Born-Infeld GravityDec 02 2016Mar 13 2017In this work, we investigate $O(4)$-symmetric instantons within the Eddington-inspired-Born-Infeld gravity theory (EiBI). We discuss the regular Hawking-Moss instanton and find that the tunneling rate reduces to the General Relativity (GR) value, even ... More
Lorentz boost and non-Gaussianity in multi-field DBI-inflationMay 28 2009Jul 06 2009We show that higher-order actions for cosmological perturbations in the multi-field DBI-inflation model are obtained by a Lorentz boost from the rest frame of the brane to the frame where the brane is moving. We confirm that this simple method provides ... More
On the Trispectrum of Galileon InflationJul 20 2013We present a detailed study of the trispectrum of the curvature perturbation generated within a stable, well defined and predictive theory which comprises an inflationary phase. In this model the usual shift symmetry is enhanced up to the so-called Galileon ... More
The two faces of mimetic Horndeski gravity: disformal transformations and Lagrange multiplierJun 29 2015Dec 29 2015We show that very general scalar-tensor theories of gravity (including, e.g., Horndeski models) are generically invariant under disformal transformations. However there is a special subset, when the transformation is not invertible, that yields new equations ... More
Singular Instantons in Eddington-inspired-Born-Infeld GravityDec 02 2016In this work, we investigate $O(4)$-symmetric instantons within the Eddington-inspired-Born-Infeld gravity theory (EiBI). We discuss the regular Hawking-Moss instanton and find that the tunneling rate reduces to the General Relativity (GR) value, even ... More
On the full trispectrum in single field DBI-inflationMay 22 2009We compute the tree-level connected four-point function of the primordial curvature perturbation for a fairly general minimally coupled single field inflationary model, where the inflaton's Lagrangian is a general function of the scalar field and its ... More
Low energy effective theory on a regularized brane in 6D gauged chiral supergravityOct 15 2007We derive the low energy effective theory on a brane in six-dimensional chiral supergravity. The conical 3-brane singularities are resolved by introducing cylindrical codimension one 4-branes whose interiors are capped by a regular spacetime. The effective ... More
Planck 2018 results. IX. Constraints on primordial non-GaussianityMay 14 2019We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and modal bispectrum ... More
Planck 2015 results. XVII. Constraints on primordial non-GaussianityFeb 05 2015Jul 19 2016The Planck full mission cosmic microwave background(CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity(NG). Using three classes of optimal bispectrum estimators - separable template-fitting (KSW), ... More
Quantum Monte Carlo simulations of the half-filled two-dimensional Kondo lattice modelApr 13 1999The 2D half-filled Kondo lattice model with exchange J and nearest neighbor hopping t is considered. It is shown that this model belongs to a class of Hamiltonians for which zero-temperature auxiliary field Monte Carlo methods may be efficiently applied. ... More
A Self-Organizing Neural Scheme for Door Detection in Different EnvironmentsJan 03 2013Doors are important landmarks for indoor mobile robot navigation and also assist blind people to independently access unfamiliar buildings. Most existing algorithms of door detection are limited to work for familiar environments because of restricted ... More
Geodesics on an ellipsoid of revolutionFeb 07 2011Algorithms for the computation of the forward and inverse geodesic problems for an ellipsoid of revolution are derived. These are accurate to better than 15 nm when applied to the terrestrial ellipsoids. The solutions of other problems involving geodesics ... More
Stochastic Ion Heating by a Lower Hybrid Wave: IIJan 07 2005The motion of an ion in a coherent lower hybrid wave (characterized by |k_parallel| << |k_perp| and omega >> Omega_i) in a tokamak plasma is studied. For ions satisfying v_perp > omega/k_perp, the Lorentz force law for the ions is reduced to a set of ... More
Right-left asymmetry of radiation from fission induced by polarised neutronsFeb 09 2009The effect of the right-left asymmetry is considered in the angular distribution of gamma quanta from fission of U-235 by polarised thermal neutrons, which depends on the polarisation of the neutrons with respect to the gamma-fission plane. Electric dipole ... More
Angula distanco en kalotoDec 02 2003A cap in a 2-D sphere is considered, smaller than an hemisphere. Two points are randomly chosen in the cap. The probability density that the angular separation between the points have a given value is obtained. The knowledge of this function is important ... More
Movoj sub newtona logaritma potencialoOct 16 2003A linear density of mass is assumed uniformly distributed along an infinitely long straight line. All possible motions of a test particle are described, under the newtonian logarithmic gravitational potential alone. Those most interesting occur in planes ... More
The index of isolated umbilics on surfaces of non-positive curvatureApr 09 2014It is shown that if a $C^2$ surface $M\subset\mathbb R^3$ has negative curvature on the complement of a point $q\in M$, then the $\mathbb Z/2$-valued Poincar\'e-Hopf index at $q$ of either distribution of principal directions on $M-\{q\}$ is non-positive. ... More
On the vDVZ discontinuity in massive conformal gravityMar 03 2017Mar 05 2019By taking the massless limit of linearized massive conformal gravity coupled to a source, we show that the theory is free from the vDVZ discontinuity. This result is confirmed when we take the massless limit of the gravitational potential of the theory, ... More
On the mixing time of the 2D stochastic Ising model with "plus" boundary conditions at low temperatureMay 19 2009Sep 15 2009We consider the Glauber dynamics for the 2D Ising model in a box of side L, at inverse temperature $\beta$ and random boundary conditions $\tau$ whose distribution P either stochastically dominates the extremal plus phase (hence the quotation marks in ... More
Collinear true ternary fission as the consequence of the collective nuclear modelApr 24 2019May 05 2019The concept of collinear spontaneous true ternary fission of 252Cf is subject to critical analysis. The conclusion is that the collinear flight of the fragments turns out to be a natural and most probable mode. The collinearity arises in the model on ... More
Depleted Kondo LatticesApr 07 2001Nov 17 2001We consider a two dimensional Kondo lattice model with exchange J and hopping t in which three out of four impurity spins are removed in a regular way. At the particle-hole symmetric point the model may be studied with auxiliary field quantum Monte Carlo ... More
The interplay between d-wave superconductivity and antiferromagnetic fluctuations: a quantum Monte Carlo studyJun 25 1998We consider the repulsive Hubbard model on a square lattice with an additional term, W, which depends upon the square of a single-particle nearest-neighbor hopping. At half-band filling, constant W, we show that enhancing U/t drives the system from a ... More
Superconductors as ideal spin sources for spintronicsNov 05 2007Apr 03 2008Spin-polarized transport is investigated in normal metal-superconductor (NS) junctions as a function of interface transmissivity as well as temperature when the density of states of a superconductor is Zeeman-split in response to an exchange field (h_exc). ... More
Ultra-High-Energy Cosmic Rays from the Radio Lobes of AGNsSep 22 2008In the past year, the HiRes and Auger collaborations have reported the discovery of a high-energy cutoff in the ultra-high energy cosmic-ray (UHECR) spectrum, and an apparent clustering of the highest energy events towards nearby active galactic nuclei ... More
Sampling exactly from the normal distributionMar 25 2013Jun 10 2014An algorithm for sampling exactly from the normal distribution is given. The algorithm reads some number of uniformly distributed random digits in a given base and generates an initial portion of the representation of a normal deviate in the same base. ... More
Transverse Mercator with an accuracy of a few nanometersFeb 08 2010Feb 03 2011Implementations of two algorithms for the transverse Mercator projection are described; these achieve accuracies close to machine precision. One is based on the exact equations of Thompson and Lee and the other uses an extension of Krueger's series for ... More
Quaternions in molecular modelingJun 23 2005Apr 04 2006Quaternions are an important tool to describe the orientation of a molecule. This paper considers the use of quaternions in matching two conformations of a molecule, in interpolating rotations, in performing statistics on orientational data, in the random ... More
Long-Time Correlations in Stochastic SystemsJan 11 2005In recent years, there has been considerable interest in understanding the motion in Hamiltonian systems when phase space is divided into stochastic and integrable regions. This paper studies one aspect of this problem, namely, the motion of trajectories ... More
Exchange Monte Carlo for Molecular Simulations with Monoelectronic HamiltoniansMar 04 2002We introduce a general Monte Carlo scheme for achieving atomistic simulations with monoelectronic Hamiltonians including the thermalization of both nuclear and electronic degrees of freedom. The kinetic Monte Carlo algorithm is used to obtain the exact ... More
Contraction Elimination in Sequent Based Ground Equational CalculusDec 30 2015In "Cut Elimination for Gentzen's Sequent Calculus with Equality and Logic of Partial Terms" LNCS 7750,161-172(2013), we have shown that the cut rule is eliminable in two ground equational sequent calculi, to be denoted by EQ_M and EQ'. In this note we ... More
Probing the unitarity of the renormalizable theory of massive conformal gravityJul 27 2017Apr 03 2018The presence of an unstable massive spin-2 ghost state in the renormalizable theory of massive conformal gravity leads to a pair of complex poles appearing in the first sheet of the energy plane. Here we show that the positions of these poles are gauge ... More
Reply to "Comment on 'Quantum massive conformal gravity' by F. F. Faria"Aug 03 2016Jan 07 2017Recently in (Eur. Phys. J. C 76:341, 2016) [arXiv:1604.08706], Myung has suggested that the renormalizability of massive conformal gravity is meaningless unless the massive ghost states of the theory are stable. Here we show that massive conformal gravity ... More
Cosmology in massive conformal gravityOct 19 2014Mar 06 2019In this paper we find the cosmological solutions of the massive conformal gravity field equations in the presence of matter fields. In particular, we show that the solution of negative curvature is in good agreement with our universe.
Computation of Green's functions through algebraic decomposition of operatorsJul 04 2017In this article we use linear algebra to improve the computational time for the obtaining of Green's functions of linear differential equations with reflection (DER). This is achieved by decomposing both the `reduced' equation (the ODE associated to a ... More
Model pseudofermionic systems: connections with exceptional pointsFeb 25 2014We discuss the role of pseudo-fermions in the analysis of some two-dimensional models, recently introduced in connection with non self-adjoint hamiltonians. Among other aspects, we discuss the appearance of exceptional points in connection with the validity ... More
The acoustic spectrum of alpha Cen AJun 04 2002This paper presents the analysis of Doppler p-mode observations of the G2V star $\alpha$ Cen A obtained with the spectrograph CORALIE in May 2001. Thirteen nights of observations have made it possible to collect 1850 radial velocity measurements with ... More
PINGSoft: an IDL visualisation and manipulation tool for Integral Field Spectroscopic dataJun 04 2010In this article we introduce PINGSoft, a set of IDL routines designed to visualise and manipulate, in an interactive and friendly way, Integral Field Spectroscopic data. The package is optimised for large databases and a fast visualisation rendering. ... More
Spin, charge and single-particle spectral functions of the one-dimensional quarter filled Holstein modelJul 15 2008Sep 30 2008We use a recently developed extension of the weak coupling diagrammatic determinantal quantum Monte Carlo method to investigate the spin, charge and single particle spectral functions of the one-dimensional quarter-filled Holstein model with phonon frequency ... More
Upper and lower limits for the number of S-wave bound states in an attractive potentialOct 25 2002New upper and lower limits are given for the number of S-wave bound states yielded by an attractive (monotonic) potential in the context of the Schrodinger or Klein-Gordon equation.
Velocity-Space Diffusion in a Perpendicularly Propagating Electrostatic WaveJan 07 2005The motion of ions in the fields B = B_0 zhat and E = E_0 yhat cos(k_perp y - omega t) is considered. When omega >> Omega_i and v_perp > omega/k_perp, the equations of motion may be reduced to a set of difference equations. These equations exhibit stochastic ... More
Minimal Length Uncertainty Relation and gravitational quantum wellMay 18 2006The dynamics of a particle in a gravitational quantum well is studied in the context of nonrelativistic quantum mechanics with a particular deformation of a two-dimensional Heisenberg algebra. This deformation yields a new short-distance structure characterized ... More
Existence of mesons after deconfinementJun 27 2007Oct 24 2007We investigate the possibility for a quark-antiquark pair to form a bound state at temperatures higher than the critical one ($T>T_c$), thus after deconfinement. Our main goal is to find analytical criteria constraining the existence of such mesons. Our ... More
On the premelting features in sodium clustersDec 08 2003Melting in Na_n clusters described with an empirical embedded-atom potential has been reexamined in the size range 55<=n<=147 with a special attention at sizes close to 130. Contrary to previous findings, premelting effects are also present at such medium ... More
Interacting power-law and logarithmic entropy-corrected holographic dark energy models with different cut-offs in Brans-Dicke cosmologyAug 29 2015Sep 29 2016In the framework of Brans-Dicke cosmology, we have studied the interacting power-law and logarithmic entropy-corrected holographic dark energy models with different cut-offs. The Brans-Dicke parameter is investigated versus the conditions for the acceleration ... More
Distances in plane membranesNov 13 2001Dec 27 2001A flat membrane with given shape is displayed; two points in the membrane are randomly selected; the probability that the separation between the points have a specified value is sought. A simple method to evaluate the probability density is developed, ... More
Cosmic crystallography: the hyperbolic isometriesOct 29 2000All orientation preserving isometries of the hyperbolic three-space are studied, and the probability density of conjugate pair separations for each isometry is presented. The study is relevant for the cosmic crystallography, and is the theoretical counterpart ... More
The ideal relativistic spinning gas: polarization and spectraOct 30 2007Feb 22 2008We study the physics of the ideal relativistic rotating gas at thermodynamical equilibrium and provide analytical expressions of the momentum spectra and polarization vector for the case of massive particles with spin 1/2 and 1. We show that the finite ... More
Reply to "Comment on 'Quantum massive conformal gravity' by F. F. Faria"Aug 03 2016Recently in Eur. Phys. J. C 76, 341 (2016) [arXiv:1604.08706] Myung has suggested that the problem with unphysical states in massive conformal gravity, which was pointed in Eur. Phys. J. C 76, 188 (2016), is solved if we quantize the dilaton field in ... More
Comment on "Astrophysical gravitational waves in conformal gravity"Feb 15 2019Recently, in Phys. Rev. D 98, 084002 (2018), an investigation was carried out on the gravitational radiation from binary systems in conformal gravity and massive conformal gravity. According to the authors of the paper, these two theories differ only ... More
Quantum massive conformal gravityMar 14 2015Apr 07 2016We first find the linear approximation of the second plus fourth order derivative massive conformal gravity action. Then we reduce the linearized action to separated second order derivative terms, which allows us to quantize the theory by using the standard ... More
Solar system tests for linear massive conformal gravityApr 08 2016We first find the linearized gravitational field of a static spherically symmetric mass distribution in massive conformal gravity. Then we test this field with two solar system experiments: deflection of light by the sun and radar echo delay. The result ... More
Massive conformal gravityDec 19 2013Dec 15 2014In this article we construct a massive theory of gravity that is invariant under conformal transformations. The massive action of the theory depend on the metric tensor and a scalar field, which are considered as the only field variables. We find the ... More
Conformal theory of everythingMar 09 2019By using conformal symmetry we unify the standard model of particle physics with gravity in a consistent quantum field theory which describes all the fundamental particles and forces of nature.
Funciones de Green para Ecuaciones Diferenciales con InvolucionesNov 20 2014In this work we revise the most recent developments concerning the study of first order problems regarding differential equations with involutions. We take into account two cases: the case of initial conditions and constant coefficients and the case of ... More
Fokker-Planck and Quasilinear CodesJan 13 2005The interaction of radio-frequency waves with a plasma is described by a Fokker-Planck equation with an added quasilinear term. Methods for solving this equation on a computer are discussed.
Numerical Techniques for the Study of Long-Time CorrelationsJan 26 2004In the study of long-time correlations extremely long orbits must be calculated. This may be accomplished much more reliably using fixed-point arithmetic. Use of this arithmetic on the Cray-1 computer is illustrated.
Phase diagram of the half-filled two-dimensional SU(N) Hubbard-Heisenberg model: a quantum Monte Carlo studyJun 03 2004We investigate the phase diagram of the half-filled SU(N) Hubbard-Heisenberg model with hopping t, exchange J and Hubbard U, on a square lattice. In the large-N limit, and as a function of decreasing values of t/J, the model shows a transition from a ... More
Coherence scale of the two-dimensional Kondo Lattice modelJan 07 2004A doped hole in the two-dimensional half-filled Kondo lattice model with exchange J and hopping t has momentum (pi,pi) irrespective of the coupling J/t. The quasiparticle residue of the doped hole, Z_{(\pi, \pi)}, tracks the Kondo scale, T_K, of the corresponding ... More
UHECRs from the Radio Lobes of AGNsSep 23 2008Oct 07 2008We report a stochastic mechanism of particle acceleration from first principles in an environment having properties like those of Radio Lobes in AGNs. We show that energies $\sim 10^{20}$ eV are reached in $\sim 10^6$ years for protons. Our results reopen ... More
Taub, Rindler, and the static plateFeb 03 2005An infinite 3D plate of homogeneous incompressible fluid is considered, with finite thickness, together with a 2D infinite homogeneous mass in its centre. Einstein equations are exactly solved, in the interior of the 3D mass. The solution is joined to ... More
Separations inside a cubeDec 28 2001Two points are randomly selected inside a three-dimensional euclidian cube. The value l of their separation lies somewhere between zero and the length of a diagonal of the cube. The probability density P(l) of the separation is obtained analytically. ... More
Cosmic crystallography in a circleMay 15 2000Oct 05 2000In a circle (an S^1) with circumference 1 assume m objects distributed pseudo-randomly. In the universal covering R^1 assume the objects replicated accordingly, and take an interval L>1. In this interval, make the normalized histogram of the pair separations ... More
Synchronization of non-chaotic dynamical systemsAug 09 1999Dec 14 2000A synchronization mechanism driven by annealed noise is studied for two replicas of a coupled-map lattice which exhibits stable chaos (SC), i.e. irregular behavior despite a negative Lyapunov spectrum. We show that the observed synchronization transition, ... More
tbW vertex in the Littlest Higgs Model with T-parityOct 27 2008Feb 12 2009A study of the effective tbW vertex is done in the littlest Higgs model with T parity that includes the one loop induced weak dipole coefficient f_{2R}. The top's width, the W-boson helicity in the t-> bW^+ decay as well as the t-channel and the s-channel ... More
Non-Statistical gamma Rays from FragmentsOct 09 2007Polarization mechanism by Strutinsky-Denisov gives rise to the electric dipole radiation from fragments. Its probability calculated within the LDM turns out to be ~3.5x10-2 per fission. The radiation occurs during thermolization of the post-rupture deformation ... More
Stochastic Optimal Control with Delay in the Control II: Verification Theorem and Optimal FeedbacksJul 21 2016We consider a stochastic optimal control problem governed by a stochastic differential equation with delay in the control. Using a result of existence and uniqueness of a sufficiently regular mild solution of the associated Hamilton-Jacobi-Bellman (HJB) ... More
Measurement of wave-particle interaction and metastable lifetime using laser-induced fluorescenceFeb 27 2019Extensive information, such as ion temperature and wave-particle interactions, can be obtained by direct measurement of ion distribution functions using laser-induced fluorescence (LIF). This nonintrusive plasma diagnostic provides an important window ... More
Measurement of wave-particle interaction and metastable lifetime using laser-induced fluorescenceFeb 27 2019Apr 20 2019Extensive information, such as ion temperature and wave-particle interactions, can be obtained by direct measurement of ion distribution functions using laser-induced fluorescence (LIF). This nonintrusive plasma diagnostic provides an important window ... More
A hyperbolic analog of the phasor addition formulaNov 20 2014Feb 23 2017In this article we review the basics of the phasor formalism in a rigorous way, highlighting the physical motivation behind it and presenting a hyperbolic counterpart of the phasor addition formula.
Relativeca Dopplera efiko inter du akcelataj korpoj - IJan 15 2008Feb 27 2008We describe the Doppler effect between equally accelerated light source and observer under the special relativity. The proper accelerations are constant and parallel. An English version is available by request. - - - - - - - - - - - Ni priskribas luman ... More
Braneworlds in Horndeski gravityOct 18 2018In this paper we address the issue of finding braneworld solutions in a five-dimensional Horndeski gravity and the mechanism of gravity localization into the brane via `almost massless modes' for suitable values of the Horndeski parameters. We compute ... More
Two- and three- dimensional few-body systems in the universal regimeNov 11 2014Macro properties of cold atomic gases are driven by few-body correlations, even if the gas has thousands of particles. Quantum systems composed of two and three particles with attractive zero\=/range pairwise interactions are considered for general masses ... More
SU(2)-spin Invariant Auxiliary Field Quantum Monte Carlo Algorithm for Hubbard modelsJun 25 1998Auxiliary field quantum Monte Carlo methods for Hubbard models are generally based on a Hubbard-Stratonovitch transformation where the field couples to the z-component of the spin. This transformation breaks SU(2) spin invariance. The symmetry is restored ... More
Adiabatic Magnetization of Superconductors as a High-Performance Cooling MechanismNov 25 2008The adiabatic magnetization of a superconductor is a cooling principle proposed in the 30s, which has never been exploited up to now. Here we present a detailed dynamic description of the effect, computing the achievable final temperatures as well as ... More
Hybrid superconducting quantum magnetometerMar 18 2011Dec 03 2011A superconducting quantum magnetometer based on magnetic flux-driven modulation of the density of states of a proximized metallic nanowire is theoretically analyzed. With optimized geometrical and material parameters transfer functions up to a few mV/Phi_0 ... More
Long-Time Correlations in the Stochastic RegimeJan 11 2005The phase space for Hamiltonians of two degrees of freedom is usually divided into stochastic and integrable components. Even when well into the stochastic regime, integrable orbits may surround small stable regions or islands. The effect of these islands ... More
Temporal Evolution of Lower Hybrid Waves in the Presence of Ponderomotive Density FluctuationsJan 10 2005The propagation of lower hybrid waves in the presence of ponderomotive density fluctuations is considered. The problem is treated in two dimensions and, in order to be able to correctly impose the boundary conditions, the waves are allowed to evolve in ... More
Algorithms for geodesicsSep 21 2011Mar 28 2012Algorithms for the computation of geodesics on an ellipsoid of revolution are given. These provide accurate, robust, and fast solutions to the direct and inverse geodesic problems and they allow differential and integral properties of geodesics to be ... More
Stochastic Optimal Control with Delay in the Control I: solving the HJB equation through partial smoothingJul 21 2016Stochastic optimal control problems governed by delay equations with delay in the control are usually more difficult to study than the the ones when the delay appears only in the state. This is particularly true when we look at the associated Hamilton-Jacobi-Bellman ... More
Experimentally obtaining metrics in general relativityMay 10 2005It seems to be not well known that the metrics of general relativity (GR) can be obtained without integrating Einstein equations. To that, we need only define a unit for GR-interval $\Delta s$, and observe 10 geodesics (out of which at least one must ... More
Right-Left Asymmetry of Radiation from FissionOct 09 2007The effect of the right-left asymmetry is considered in the predicted earlier electric dipole radiation from fission fragments arising due to the Strutinski-Denisov induced polarisation mechanism. The magnitude of the asymmetry parameter is on the level ... More
Gas accretion on spiral galaxies: bar formation and renewalJun 17 2002The effects of gas accretion on spiral disk dynamics and stability are studied through N-body simulations, including star formation and gas/stars mass exchange. The detailed processes of bar formation, bar destruction and bar re-formation are followed, ... More
Formation of polar ring galaxiesJan 20 2003Feb 04 2003Polar ring galaxies are peculiar systems in which a gas rich, nearly polar ring surrounds an early-type or elliptical host galaxy. Two formation scenarios for these objects have been proposed: they are thought to form either in major galaxy mergers or ... More
Cosmology in massive conformal gravityOct 19 2014Sep 25 2015In this article we find the cosmological solutions of the massive conformal gravity field equations in the presence of matter fields. In particular, we show that the solution of negative spatial curvature is in good agreement with our universe.
FCNC production of same sign Top quark pairs at the LHCNov 05 2003Nov 06 2003We study the possibility of same sign top quark pair production at the LHC (and the VLHC) as a direct probe of FCNC processes. Besides the SM neutral Z boson, two other neutral bosons are considered, a top-Higgs type scalar and a Z' boson that appear ... More