Results for "V. C. Antochi"

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First results on the scalar WIMP-pion coupling, using the XENON1T experimentNov 29 2018We present first results on the scalar WIMP-pion coupling from 1 t$\times$yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most ... More
Constraining the spin-dependent WIMP-nucleon cross sections with XENON1TFeb 08 2019We report the first experimental results on spin-dependent elastic WIMP-nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full tonne-year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only ... More
The combinatorics of resource sharingSep 23 2003We discuss general models of resource-sharing computations, with emphasis on the combinatorial structures and concepts that underlie the various deadlock models that have been proposed, the design of algorithms and deadlock-handling policies, and concurrency ... More
Control over adversarial packet-dropping communication networks revisitedMar 22 2014We revisit a one-step control problem over an adversarial packet-dropping link. The link is modeled as a set of binary channels controlled by a strategic jammer whose intention is to wage a `denial of service' attack on the plant by choosing a most damaging ... More
Caustics of $1/r^n$ binary gravitational lenses: from galactic haloes to exotic matterNov 25 2015Mar 07 2016We investigate the caustic topologies for binary gravitational lenses made up of two objects whose gravitational potential declines as $1/r^n$. With $n<1$ this corresponds to power-law dust distributions like the singular isothermal sphere. The $n>1$ ... More
Approximate Dynamic Programming via a Smoothed Linear ProgramAug 04 2009Oct 03 2009We present a novel linear program for the approximation of the dynamic programming cost-to-go function in high-dimensional stochastic control problems. LP approaches to approximate DP have typically relied on a natural `projection' of a well studied linear ... More
Deforming the Lie algebra of vector fields on $S^1$ inside the Poisson algebra on $\dot T^*S^1$Jul 07 1997We study deformations of the standard embedding of the Lie algebra $\Vect(S^1)$ of smooth vector fields on the circle, into the Lie algebra of functions on the cotangent bundle $T^*S^1$ (with respect to the Poisson bracket). We consider two analogous ... More
The interleaved multichromatic number of a graphSep 23 2003For $k\ge 1$, we consider interleaved $k$-tuple colorings of the nodes of a graph, that is, assignments of $k$ distinct natural numbers to each node in such a way that nodes that are connected by an edge receive numbers that are strictly alternating between ... More
High order Nyström methods for transmission problems for Helmholtz equationOct 22 2015May 12 2016We present superalgebraic compatible Nystr\"om discretizations for the four Helmholtz boundary operators of Calder\'{o}n's calculus on smooth closed curves in 2D. These discretizations are based on appropriate splitting of the kernels combined with very ... More
Two-parameter generalization of the logarithm and exponential functions and Boltzmann-Gibbs-Shannon entropyMar 30 2007The $q$-sum $x \oplus_q y \equiv x+y+(1-q) xy$ ($x \oplus_1 y=x+y$) and the $q$-product $x\otimes_q y \equiv [x^{1-q} +y^{1-q}-1]^{\frac{1}{1-q}}$ ($x\otimes_1 y=x y$) emerge naturally within nonextensive statistical mechanics. We show here how they lead ... More
Conformally equivariant quantizationJan 27 1998Feb 25 2000Let $(M,g)$ be a pseudo-Riemannian manifold and $F_\lambda(M)$ the space of densities of degree $\lambda$ on $M$. We study the space $D^2_{\lambda,\mu}(M)$ of second-order differential operators from $F_\lambda(M)$ to $F_\mu(M)$. If $(M,g)$ is conformally ... More
An extension of the Burau representation to a mapping class group associated to Thompson's group TFeb 25 2003We study some aspects of the geometric representation theory of the Thompson and Neretin groups, suggested by their analogies with the diffeomorphism groups of the circle. We prove that the Burau representation of the Artin braid groups extends to a mapping ... More
Lorentzian worldlines and Schwarzian derivativeSep 11 1998We relate in this note the classical Schwarzian derivative to the curvature of time-like curves in Lorentz surfaces of constant curvature.
Projectively equivariant quantization and symbol calculus: noncommutative hypergeometric functionsMar 15 2001We extend projectively equivariant quantization and symbol calculus to symbols of pseudo-differential operators. An explicit expression in terms of hypergeometric functions with noncommutative arguments is given. Some examples are worked out, one of them ... More
Space of second order linear differential operators as a module over the Lie algebra of vector fieldsSep 12 1994The space of linear differential operators on a smooth manifold $M$ has a natural one-parameter family of $Diff(M)$ (and $Vect(M)$)-module structures, defined by their action on the space of tensor-densities. It is shown that, in the case of second order ... More
Are Spiral Disks Really Opaque ?Nov 24 1994We compare the ultra-violet, optical, and far-infrared emission for a sample of 135 spiral galaxies in order to address the widely debated problem concerning the opacity of spiral disks. We find that the re-radiation of the dust, estimated from the far-infrared ... More
Ground state of antiferromagnetic ordering in fullerene $C_{60}$ moleculeJan 15 2001Theoretical study of mutual orientation of fullerene $C_{60}$ molecule atom spins is presented in this work. Spin-spin interaction was described by Habbard's model. Existence of antiferromagnetic sturcture of spin sub-system in ground state is found.
2MASS Two-color Interstellar Reddening Line in the Direction of the North America and Pelican Nebulae and the Cyg OB2 AssociationSep 16 2008The slope of the interstellar reddening line in the J-H vs. H-Ks diagram of the 2MASS survey in the direction of the North America and Pelican nebulae, the L935 dust cloud and the Cyg OB2 association is determined. The MK types were either classified ... More
The motion of a charged particle in Kalusa-Klein manifoldsOct 09 2007In this paper we use Jacobi fields to describe the motion of a charged particle in the classical gravitational, electromagnetic, and Yang-Mills fields.
Mapping Among Manifolds IIINov 14 2013In two previous papers, we constructed two modified Hamiltonian formalisms to make maps among manifolds explicit. In this paper, the two modified formalisms were adapted to manifolds with local coordinates given by scalar fields, as in a classical nonlinear ... More
A Possible Origin of Dark Matter, Dark Energy, and Particle-Antiparticle AsymmetrySep 30 2010In this paper we present a possible origin of dark matter and dark energy from a solution of the Einstein's equation to a primordial universe, which was presented in a previous paper. We also analyze the Dirac's equation in this primordial universe and ... More
Atom made from charged elementary black holeJan 10 2000It is believed that there may have been a large number of black holes formed in the very early universe. These would have quantised masses. A charged ``elementary black hole'' (with the minimum possible mass) can capture electrons, protons and other charged ... More
Theory of Spike Spiral Waves in a Reaction-Diffusion SystemAug 11 1998We discovered a new type of spiral wave solutions in reaction-diffusion systems --- spike spiral wave, which significantly differs from spiral waves observed in FitzHugh-Nagumo-type models. We present an asymptotic theory of these waves in Gray-Scott ... More
A Random Search Framework for Convergence Analysis of Distributed Beamforming with FeedbackJun 18 2008Jul 13 2010The focus of this work is on the analysis of transmit beamforming schemes with a low-rate feedback link in wireless sensor/relay networks, where nodes in the network need to implement beamforming in a distributed manner. Specifically, the problem of distributed ... More
Conformal Form of Pseudo-Riemannian Metrics by Normal Coordinate TransformationsJun 15 2010In this paper we extend the Cartan's approach of Riemannian normal coordinates and show that all n-dimensional pseudo-Riemannian metrics are conformal to a flat manifold, when, in normal coordinates, they are well-behaved in the origin and in its neighborhood. ... More
Comment on "Global Positioning System Test of the Local Position Invariance of Planck's Constant"Mar 26 2012In their Letter, Kentosh and Mohageg [Phys. Rev. Lett. 108, 110801 (2012)] seek to use data from clocks aboard global positioning system (GPS) satellites to place limits on local position invariance (LPI) violations of Planck's constant, h. It is the ... More
Bit storage by $360^\circ$ domain walls in ferromagnetic nanoringsNov 28 2008We propose a design for the magnetic memory cell which allows an efficient storage, recording, and readout of information on the basis of thin film ferromagnetic nanorings. The information bit is represented by the polarity of a stable 360$^\circ$ domain ... More
Spike autosolitons in the Gray-Scott modelMar 31 1998Jan 18 2000We performed a comprehensive study of the spike autosolitons: self-sustained solitary inhomogeneous states, in the classical reaction-diffusion system --- the Gray-Scott model. We developed singular perturbation techniques based on the strong separation ... More
General theory of instabilities for patterns with sharp interfaces in reaction-diffusion systemsMar 06 1996An asymptotic method for finding instabilities of arbitrary $d$-dimensional large-amplitude patterns in a wide class of reaction-diffusion systems is presented. The complete stability analysis of 2- and 3-dimensional localized patterns is carried out. ... More
Ab-initio density functional studies of stepped TaC surfacesOct 06 2002We report on density functional total energy calculations of the step formation and interaction energies for vicinal TaC(001) surfaces. Our calculations show that double and triple-height steps are favored over single-height steps for a given vicinal ... More
Quasinormal Modes of Lovelock Black HolesMay 21 2014The quasinormal modes of metric perturbations in asymptotically flat black hole spacetimes in the Lovelock model are calculated for different spacetime dimensions and higher orders of curvature. It is analytically established that in the asymptotic limit ... More
Learning through experimenting: an original way of teaching geometrical opticsSep 26 2016Over the past 10 years, we have developed at University Paris Sud a first year course on geometrical optics centered on experimentation. In contrast with the traditional top-down learning structure usually applied at university, in which practical sessions ... More
Vertical distribution of Galactic disk stars IV - AMR and AVR from clump giantsDec 09 2007We present the parameters of 891 stars, mostly clump giants, including atmospheric parameters, distances, absolute magnitudes, spatial velocities, galactic orbits and ages. One part of this sample consists of local giants, within 100 pc, with atmospheric ... More
Combining configuration interaction with perturbation theory for atoms with large number of valence electronsNov 01 2016A version of the configuration interaction (CI) method is developed which treats highly excited many-electron basis states perturbatively, so that their inclusion does not affect the size of the CI matrix. This removes, at least in principle, the main ... More
Atoms which can bind positronsAug 03 2013Feb 01 2014Calculations of the positron binding energies to all atoms in the periodic table are presented and atoms where the positron-atom binding actually exists are identified. The results of these calculations and accurate calculations of other authors (which ... More
Calculation of positron binding to silver and gold atomsJan 25 2000Positron binding to silver and gold atoms was studied using a fully {\it ab initio} relativistic method, which combines the configuration interaction method with many-body perturbation theory. It was found that the silver atom forms a bound state with ... More
H_3^(2+) molecular ion in a strong magnetic field: a triangular configurationJan 12 2000Jan 19 2000The bound state in the system of three protons and an electron (pppe) under a homogeneous strong magnetic field where the protons are situated in the vertices of an equilateral triangle perpendicular to the magnetic field lines is found. It is shown that ... More
Supercurrent and multiple singlet-doublet phase transitions of a quantum dot Josephson junction inside an Aharonov-Bohm ringOct 21 2008Jan 28 2009We study a quantum dot Josephson junction inside an Aharonov-Bohm environment. The geometry is modeled by an Anderson impurity coupled to two directly-linked BCS leads. We illustrate that the well-established picture of the low-energy physics being governed ... More
Searching for evidence of jet-cloud interaction in radio galaxies. First results for 3C 381Jan 10 2013We present results of Gemini spectroscopy and Hubble Space Telescope imaging of the 3C~381 radio galaxy. Possible ionising mechanisms for the Extended Emission-Line Region were studied through state-of-the-art diagnostic analysis employing line-ratios. ... More
A search for water masers toward extrasolar planetsFeb 17 2006Water is the most common triatomic molecule in the universe and the basis of life on Earth. Astrophysical masers have been widely studied in recent years and have been shown to be invaluable probes of the details of the environment in which they are found. ... More
On free resolutions in multivariable operator theorySep 17 2001Sep 18 2001We define the notion of a free resolution of a d-tuple $(T_1, T_2, . . . T_d)$ of mutually commuting operators acting on a Hilbert space H, and that this invariant gives rise to a class of vector space complexes parametrized by points in the unit ball ... More
"Stokes' Second Problem in High Frequency Limit. Application to Micro (Nano)- ResonatorsSep 25 2006Mar 26 2007Using kinetic equation in the relaxation approximation (RTA), we investigate a flow generated by an infinite plate oscillating with frequency $\omega$. Geometrical simplicity of the problem allows a solution in the entire range of dimensionless frequency ... More
Dilepton Production at SPS-energy Heavy Ion CollisionsJun 14 1996The production of dileptons is studied within a hadronic transport model. We investigate the sensitivity of the dilepton spectra to the initial configuration of the hadronic phase in a ultrarelativistic heavy ion collision. Possible in medium correction ... More
Writhing Geometry of Open DNAJan 14 2003Motivated by recent experiments on DNA torsion-force-extension characteristics we consider the writhing geometry of open stiff molecules. We exhibit a cyclic motion which allows arbitrarily large twisting of the end of a molecule via an activated process. ... More
Variable electrostatic transformer: controllable coupling of two charge qubitsApr 07 2003Jul 28 2003We propose and investigate a novel method for the controlled coupling of two Josephson charge qubits by means of a variable electrostatic transformer. The value of the coupling capacitance is given by the discretized curvature of the lowest energy band ... More
Ergodic Properties of the Spin - Boson SystemAug 17 1995We investigate the dynamics of a 2-level atom (or spin-1/2) coupled to a mass-less bosonic field at positive temperature. We prove that, at small coupling, the combined quantum system approaches thermal equilibrium. Moreover we establish that this approach ... More
QCDMAPT_F: Fortran version of QCDMAPT packageJul 06 2011The QCDMAPT program package facilitates computations in the framework of dispersive approach to Quantum Chromodynamics. The QCDMAPT_F version of this package enables one to perform such computations with Fortran, whereas the previous version was developed ... More
A frequentist analysis of solar neutrino dataJul 14 2000We calculate with Monte Carlo the goodness of fit and the confidence level of the standard allowed regions for the neutrino oscillation parameters obtained from the fit of solar neutrino data. We show that the values of the goodness of fit and of the ... More
Statistical Analysis of Solar Neutrino DataDec 19 2000We calculate with Monte Carlo the goodness of fit and the confidence level of the standard allowed regions for the neutrino oscillation parameters obtained from the fit of the total rates measured in solar neutrino experiments. We show that they are significantly ... More
Parametrised strict deformation quantization of C*-bundles and Hilbert C*-modulesJul 27 2010Nov 26 2010In this paper, we use the parametrised strict deformation quantization of C*-bundles obtained in a previous paper, and give more examples and applications of this theory. In particular, it is used here to classify H_3-twisted noncommutative torus bundles ... More
Strong curvature singularities in quasispherical asymptotically de Sitter dust collapseSep 06 2001We study the occurrence, visibility, and curvature strength of singularities in dust-containing Szekeres spacetimes (which possess no Killing vectors) with a positive cosmological constant. We find that such singularities can be locally naked, Tipler ... More
Shell crossing in generalized Tolman-Bondi spacetimesJul 26 2001We study the occurrence of shell crossing in spherical weakly charged dust collapse in the presence of a non-vanishing cosmological constant. We find that shell crossing always occurs from generic time-symmetric regular initial data, near the center of ... More
Coherent control of lattice deformations in quantum wires by optical self-trappingOct 22 2004Jun 01 2005We investigate theoretically a semiconductor quantum wire under the effect of an intense off-resonant cw laser. We show that in the regime of strong exciton-phonon coupling the light-dressed ground state of the wire reveals symmetry-breaking features, ... More
Mass function and assembly of dark halos: an approach to inventory isolated overdense regions in random fieldsApr 02 2013Sep 08 2013In order to attain a statistical description of the evolution of cosmic density fluctuations in agreement with results from the numerical simulations, we introduce a probability conditional formalism (CF) based on an inventory of isolated overdense regions ... More
The stellar and dark halo mass assembly of galaxiesMar 22 2011The emerging empirical picture of galaxy stellar mass (Ms) assembly shows that galaxy population buildup proceeds from top to down in Ms. By connecting galaxies to LCDM halos and their histories, individual (average) Ms growth tracks can be inferred. ... More
Properties and evolution of disk galaxies in a hierarchical formation scenarioSep 20 2000We highlight some results from disk galaxy evolution models conceived within a cosmological context. When disk mergers and strong disk-halo feedback are omitted, several properties and correlations of disk galaxies seem to be related to initial conditions ... More
Quasi Normal Modes and P-V Criticallity for scalar perturbations in a class of dRGT massive gravity around Black HolesJun 03 2016We investigate black holes in a class of dRGT massive gravity for their quasi normal modes (QNMs) for neutral and charged ones using Improved Asymptotic Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are studied for different ... More
Scalar and Electromagnetic Quasinormal modes of Extended black hole in F(R) gravityAug 05 2014In this paper we study the scalar and electromagnetic perturbations of an extended black hole in F(R) gravity. The quasinormal modes in two cases are evaluated and studied their behavior by plotting graphs in each case. To study the quasinormal mode, ... More
Massive Charged Scalar Quasinormal Modes of Reissner-Nördstrom Black Hole Surrounded by QuintessenceFeb 11 2008We evaluate the complex frequencies of the normal modes for the massive charged scalar field perturbations around a Reissner-N\"ordstrom black hole surrounded by a static and spherically symmetric quintessence using third order WKB approximation approach. ... More
Quasinormal Modes and Thermodynamics of Linearly Charged BTZ Black holes in Massive Gravity in (Anti)de Sitter Space TimeAug 18 2016In this work we study the Quasi Normal Modes(QNMs) under massless scalar perturbations and the thermodynamics of linearly charged BTZ black holes in massive gravity in the (Anti)de Sitter((A)dS) space time. It is found that the behavior of QNMs changes ... More
A Mond Programme from Einstein Hilbert ActionApr 11 2011In the usual derivation of Einstein's equation from action, the surface terms are neglected. Hawking \cite{hw} gave a derivation of the gravitational Hamiltonian keeping all surface terms. Using such surface terms Easson et.al.\cite{ea} showed that Friedmann ... More
Evolution of massive fields around a black hole in Horava gravityNov 30 2010May 23 2011We study the evolution of massive scalar field in the spacetime geometry of Kehagias-Sfetsos(KS) black hole in deformed Horava-Lifshitz(HL) gravity by numerical analysis. We find that the signature of HL theory is encoded in the quasinormal mode(QNM) ... More
Generalized Bernoulli numbers and a formula of LucasFeb 12 2014An overlooked formula of E. Lucas for the generalized Bernoulli numbers is proved using generating functions. This is then used to provide a new proof and a new form of a sum involving classical Bernoulli numbers studied by K. Dilcher. The value of this ... More
Quantum supersymmetric FRW cosmology with a scalar fieldNov 13 2015Dec 23 2015We analyze the quantum supersymmetric cosmological FRW model with a scalar field, with a conditional probability density and the scalar field identified as time. The Hilbert space has a spinorial structure and there is only one consistent solution, with ... More
Quasinormal modes of RN black hole space time with cosmic string in a Dirac fieldSep 06 2008We evaluate quasinormal mode frequencies for RN black hole space times with cosmic string perturbed by a massless Dirac field, using P\"{o}schl-Teller potential method. We find that only in the case of RN black hole having small charge, the effect due ... More
Hadronization via CoalescenceMay 13 2004We review the quark coalescence model for hadronization in relativistic heavy ion collisions and show how it can explain the observed large baryon to meson ratio at intermediate transverse momentum and scaling of the elliptic flows of identified hadrons. ... More
reentrance effect in normal-metal/superconducting hybrid loopsMay 22 1998We have measured the transport properties of two mesoscopic hybrid loops composed of a normal-metal arm and a superconducting arm. The samples differed in the transmittance of the normal/superconducting interfaces. While the low transmittance sample showed ... More
Area spectrum and thermodynamics of KS black holes in Hořava gravityJul 24 2013We investigate the area spectrum of Kehagias-Sfetsos black hole in Ho\v{r}ava-Lifshitz gravity via modified adiabatic invariant $I=\oint p_i d q_i$ and Bohr-Sommerfeld quantization rule. We find that the area spectrum is equally spaced with a spacing ... More
Two-pion light-cone distribution amplitudes from the instanton vacuumJun 16 1998We calculate the two-pion light-cone distribution amplitudes in the effective low-energy theory based on the instanton vacuum. These generalized distribution amplitudes describe the soft (non-perturbative) part of the process $\gamma^*\gamma \to \pi\pi$ ... More
Lorentz-covariant deformed algebra with minimal lengthDec 12 2006The $D$-dimensional two-parameter deformed algebra with minimal length introduced by Kempf is generalized to a Lorentz-covariant algebra describing a ($D+1$)-dimensional quantized space-time. For D=3, it includes Snyder algebra as a special case. The ... More
Deformed algebras, position-dependent effective masses and curved spaces: An exactly solvable Coulomb problemMar 25 2004We show that there exist some intimate connections between three unconventional Schr\"odinger equations based on the use of deformed canonical commutation relations, of a position-dependent effective mass or of a curved space, respectively. This occurs ... More
Yang-Baxter and reflection maps from vector solitons with a boundaryMay 05 2012May 08 2014Based on recent results obtained by the authors on the inverse scattering method of the vector nonlinear Schr\"odinger equation with integrable boundary conditions, we discuss the factorization of the interactions of N-soliton solutions on the half-line. ... More
Vector Nonlinear Schrödinger Equation on the half-lineOct 13 2011Jan 30 2012We investigate the Manakov model or, more generally, the vector nonlinear Schr\"odinger equation on the half-line. Using a B\"acklund transformation method, two classes of integrable boundary conditions are derived: mixed Neumann/Dirichlet and Robin boundary ... More
Scattering in the pion-nucleon negative parity channel in lattice QCDDec 20 2012Feb 20 2013We study the coupled pion-nucleon system (negative parity, isospin 1/2) based on a lattice QCD simulation for nf=2 mass degenerate light quarks. Both, standard 3-quarks baryon operators as well as meson-baryon (4+1)-quark operators are included. This ... More
Nucleon excited states on the latticeApr 15 2013Apr 18 2013We study the pion-nucleon system in s-wave in the framework of lattice QCD in order to gain new information on the nucleon excited states. We perform simulations for $n_f =2$ mass degenerate light quarks at a pion mass of 266 MeV. The results show that ... More
SmartTennisTV: Automatic indexing of tennis videosJan 04 2018In this paper, we demonstrate a score based indexing approach for tennis videos. Given a broadcast tennis video (BTV), we index all the video segments with their scores to create a navigable and searchable match. Our approach temporally segments the rallies ... More
m-irreducible numerical semigroupsJun 17 2010In this paper we introduce the notion of m-irreducibility that extends the standard concept of irreducibility of a numerical semigroup when the multiplicity is fixed. We analyze the structure of the set of m-irreducible numerical semigroups, we give some ... More
Analysis of Boundary Conditions for Crystal Defect Atomistic SimulationsJun 22 2013May 23 2016Numerical simulations of crystal defects are necessarily restricted to finite computational domains, supplying artificial boundary conditions that emulate the effect of embedding the defect in an effectively infinite crystalline environment. This work ... More
Manifestations of a spatial variation of fundamental constants on atomic clocks, Oklo, meteorites, and cosmological phenomenaAug 24 2010The remarkable detection of a spatial variation in the fine-structure constant, alpha, from quasar absorption systems must be independently confirmed by complementary searches. In this letter, we discuss how terrestrial measurements of time-variation ... More
Astronomical and laboratory searches for space-time variation of fundamental constantsSep 20 2010We review recent activity searching for variations in the fundamental constants of nature in quasar absorption spectra and in the laboratory. While research in this direction has been ongoing for many decades, the topic has recently been stimulated by ... More
Polysulfanes on interstellar grains as a possible reservoir of interstellar sulphurJul 23 2012The form of depleted sulphur in dense clouds is still unknown. Until now, only two molecules, OCS and SO2, have been detected in interstellar ices but cannot account for the elemental abundance of sulphur observed in diffuse medium. Chemical models suggest ... More
The fingerprints of Photoionization and Shock-Ionization in two CSS sourcesOct 23 2015We investigate the ionization state of the Extended Emission-Line Regions (EELRs) around two compact steep-spectrum (CSS) radio galaxies, 3C~268.3 and 3C~303.1, in order to identify the contribution of photoionization and shock-ionization. We perform ... More
Self-generated electronic heterogeneity and quantum glassiness in the high temperature superconductorsOct 05 2004We present a systematic study of the spin and charge dynamics of copper oxide superconductors as a function of carrier concentration $x$. Our results portray a coherent physical picture, which reveals a quantum critical point at optimum doping ($x=x_{opt}$), ... More
Natural multiparticle entanglement in a Fermi gasFeb 20 2005Aug 29 2005We investigate multipartite entanglement in a non-interacting fermion gas, as a function of fermion separation, starting from the many particle fermion density matrix. We prove that all multiparticle entanglement can be built only out of two-fermion entanglement. ... More
A novel evolutionary formulation of the maximum independent set problemSep 22 2003We introduce a novel evolutionary formulation of the problem of finding a maximum independent set of a graph. The new formulation is based on the relationship that exists between a graph's independence number and its acyclic orientations. It views such ... More
Comment on "Constraining the smoothness parameter and dark energy using observational H(z) data"Mar 01 2011In this Comment we discuss a recent analysis by Yu et al. [RAA 11, 125 (2011)] about constraints on the smoothness $\alpha$ parameter and dark energy models using observational $H(z)$ data. It is argued here that their procedure is conceptually inconsistent ... More
Enhanced laboratory sensitivity to variation of the fine-structure constant using highly-charged ionsJul 07 2010Jul 08 2010We study atomic systems that are in the frequency range of optical atomic clocks and have enhanced sensitivity to potential time-variation of the fine structure constant, alpha. The high sensitivity is due to coherent contributions from three factors: ... More
Comment on "Elasticity Model of a Supercoiled DNA Molecule"Jan 11 2001We perform simulations to numerically study the writhe distribution of a stiff polymer. We compare with analytic results of Bouchiat and Mezard (PRL 80 1556- (1998); cond-mat/9706050).
MSW effect with flavor changing interactions and the atmospheric neutrino problemMay 08 2000We consider flavor changing effective neutrino interactions in the context of massive neutrinos in the issue of atmospheric neutrinos. Assuming as usual that this is an indication of the oscillation of muon neutrinos into tau neutrinos we show that there ... More
Large magnetic dipole moments for neutrinos with arbitrary massesJul 01 1999We show that there is a general sort of models in which it is possible to have large magnetic dipole moments for neutrinos while keeping their masses arbitrarily small. Some examples of these models are considered.
Statistical treatment of detection cross-section uncertainties in the analysis of solar neutrino dataJun 02 2000Jun 13 2000We propose a modification to the standard statistical treatment of the detection cross-section uncertainties in the analysis of solar neutrino data. We argue that the uncertainties of the energy-averaged cross sections of the different neutrino fluxes ... More
Relativistic shells: Dynamics, horizons, and shell crossingDec 30 2002We consider the dynamics of timelike spherical thin matter shells in vacuum. A general formalism for thin shells matching two arbitrary spherical spacetimes is derived, and subsequently specialized to the vacuum case. We first examine the relative motion ... More
Comment on gr-qc/0309003: ``Comment on `Absence of trapped surfaces and singularities in cylindrical collapse' ''Sep 02 2003Very recently, a ``Comment'' by Wang [gr-qc/0309003] on a paper by Gon\c{c}alves [Phys. Rev. D {\bf 65}, 084045 (2002)] appeared, claiming that Gon\c{c}alves' analysis of trapped surfaces in certain kinds of cylindrical spacetimes was incomplete. Specifically, ... More
Absence of trapped surfaces and singularities in cylindrical collapseFeb 12 2002Mar 22 2002The gravitational collapse of an infinite cylindrical thin shell of generic matter in an otherwise empty spacetime is considered. We show that geometries admitting two hypersurface orthogonal Killing vectors cannot contain trapped surfaces in the vacuum ... More
Strength and genericity of singularities in Tolman-Bondi-de Sitter collapseAug 08 2001We study the curvature strength and visibility of the central singularity arising in Tolman-Bondi-de Sitter collapse. We find that the singularity is visible and Tipler strong along an infinite number of timelike geodesics, independently of the initial ... More
Integrability of the Minimal Strain Equations for the Lapse and Shift in 3+1 Numerical RelativityNov 06 1999Feb 23 2000Brady, Creighton and Thorne have argued that, in numerical relativity simulations of the inspiral of binary black holes, if one uses lapse and shift functions satisfying the ``minimal strain equations'' (MSE), then the coordinates might be kept co-rotating, ... More
Dilation Theoretic Parametrizations of Positive Matrices with Applications to Quantum InformationOct 03 2006This paper, dedicated to the memory of late Professor Tiberiu Constantinescu, discusses two parametrizations of positive matrices. The first, called the Schur-Constantinescu parametrization, is used to construct several examples of separable states (e.g., ... More
Stability of black holes in Horava gravity: Gravitational quasinormal modesSep 27 2009Dec 17 2009Gravitational perturbations in the geometry of asymptotically flat black hole solution in the deformed Ho\v{r}ava-Lifshitz(HL) gravity are considered and the associated quasinormal mode(QNM) frequencies are evaluated using WKB method. Black holes are ... More
Moduli of parahoric $\mathcal G$--torsors on a compact Riemann surfaceSep 17 2010Nov 05 2012Let $X$ be an irreducible smooth projective algebraic curve of genus $g \geq 2$ over the ground field $\bc$ and let $G$ be a semisimple simply connected algebraic group. The aim of this paper is to introduce the notion of semistable and stable parahoric ... More
Evolutionary models for disk galaxies, a comparison with the observations up to intermediate redshifts (z<~1)Mar 09 1998We present a scenario for the formation and evolution of disk galaxies within the framework of an inflationary CDM universe, and we compare the results with observations ranking from the present-day up to z~1. Galactic disks are built-up inside-out by ... More