Results for "M. Chatzikos"

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H, He-like recombination spectra II: $l$-changing collisions for He Rydberg statesAug 31 2016Cosmological models can be constrained by determining primordial abundances. Accurate predictions of the He I spectrum are needed to determine the primordial helium abundance to a precision of $< 1$% in order to constrain Big Bang Nucleosynthesis models. ... More
H-, He-like recombination spectra III: $n$-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination linesMar 13 2019At intermediate to high densities, electron (de-)excitation collisions are the dominant process for populating or depopulating high Rydberg states. In particular, the accurate knowledge of the energy changing ($n$-changing) collisional rates is determinant ... More
H, He-like recombination spectra I: $l$-changing collisions for hydrogenApr 13 2016Hydrogen and helium emission lines in nebulae form by radiative recombination. This is a simple process which, in principle, can be described to very high precision. Ratios of He I and H I emission lines can be used to measure the He$^+$/H$^+$ abundance ... More
Ultraviolet emission lines of Si II in cool star and solar spectraOct 29 2015Recent atomic physics calculations for Si II are employed within the Cloudy modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, Beta-Geminorum, Alpha-Centauri A and B, as well as previously published HST/GHRS ... More
Accurate determination of the free-free Gaunt factor; I - non-relativistic Gaunt factorsJul 18 2014Aug 17 2014Modern spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum emitted by an ionized plasma. Until now no set of data exists ... More
Stout: Cloudy's Atomic and Molecular DatabaseJun 04 2015We describe a new atomic and molecular database we developed for use in the spectral synthesis code Cloudy. The design of Stout is driven by the data needs of Cloudy, which simulates molecular, atomic, and ionized gas with kinetic temperatures 2.8 K < ... More
Accurate determination of the free-free Gaunt factor. II - relativistic Gaunt factorsFeb 24 2015When modelling an ionised plasma, all spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists ... More
Implications of Coronal Line Emission in NGC 4696Oct 16 2014We announce a new facility in the spectral code CLOUDY that enables tracking the evolution of a cooling parcel of gas with time. For gas cooling from temperatures relevant to galaxy clusters, earlier calculations estimated the [Fe XIV] {\lambda}5303 / ... More
Chandra Observation of Abell 2065: An Unequal Mass Merger?Feb 08 2006We present an analysis of a 41 ks Chandra observation of the merging cluster Abell 2065 with the ACIS-I detector. Previous observations with ROSAT and ASCA provided evidence for an ongoing merger, but also suggested that there were two surviving cooling ... More
On the Observability of Optically Thin Coronal Hyperfine Structure LinesJun 03 2014We present Cloudy calculations for the intensity of coronal hyperfine lines in various environments. We model indirect collisional and radiative transitions, and quantify the collisionally-excited line emissivity in the density-temperature phase-space. ... More
Deep Chandra, HST-COS, and Megacam Observations of the Phoenix Cluster: Extreme Star Formation and AGN Feedback on Hundred Kiloparsec ScalesAug 24 2015We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously-undetected filaments of star formation, extending to radii of ~50-100 kpc in multiple directions. Combined UV-optical ... More
Space Telescope and Optical Reverberation Mapping Project. X. The Hidden Life of "the Obscurer" in NGC 5548 and Understanding the Absorption-Line HolidayDec 30 2018Jan 02 2019The flux variations in the emission lines in active galactic nuclei (AGNs) are driven by variations in the ionizing continuum flux --which are usually reflected in the observable UV-optical continuum. The "Reverberation mapping" technique measures the ... More
Effects of External Radiation Fields on Line Emission - Application to Star-forming RegionsOct 29 2013A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background (CMB), as well as by a nearby active ... More
Challenges and Techniques for Simulating Line EmissionAug 24 2018Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of "Walking the Line", a 3-day conference held in ... More
Production and Decay of Scalar Stoponium Bound StatesDec 02 1993In this paper we discuss possible signatures for the production of scalar \stst\ (stoponium) bound states \sigst\ at hadron colliders, where \st\ is the lighter scalar top eigenstate. We first study the decay of \sigst; explicit expressions are given ... More
Parton Model in Lorentz Invariant Non-Commutative SpaceMay 26 2004Aug 22 2004We consider the Lorentz invariant non-commutative QED and complete the Feynman rules for the theory up to the order $\theta^2$. In the Lorentz invariant version of the non-commutative QED the particles with fractional charges can be also considered. We ... More
Electromagnetic Response of Weyl SemimetalsMar 22 2013Jun 27 2013It has been suggested recently, based on subtle field-theoretical considerations, that the electromagnetic response of Weyl semimetals and the closely related Weyl insulators can be characterized by an axion term E.B with space and time dependent axion ... More
The Charm Quark Contribution to the Proton Structure FunctionOct 14 2006Dec 27 2006The charm quark structure function $F^c_2$ and the longitudinal structure function $F_l^p$ are directly sensitive to the gluon content of proton and therefore are crucial in understanding of proton structure function, in particular at low momentum transfer ... More
The decay of singlet scalar dark matter to unparticle and photonMay 06 2008We consider the unparticle physics introduced by Georgi and show that if the standard model is extended to include a singlet scalar as a dark matter candidate, there is a channel which leads to its decay to photon and unparticle. We calculate the decay ... More
On the effect of the thermal gas component to the stability of vortices in trapped Bose-Einstein condensatesMar 12 2002We study the stability of vortices in trapped single-component Bose-Einstein condensates within self-consistent mean-field theories--especially we consider the Hartree-Fock-Bogoliubov-Popov theory and its recently proposed gapless extensions. It is shown ... More
A new signal for scalar top bound state productionOct 01 1993We study the production and decay of a scalar \stst\ bound state \sigst\ at hadron supercolliders, where \st\ is the lighter stop eigenstate. If \st\ has no tree--level 2--body decays, the dominant decay modes of \sigst\ are $gg$ or, if $m_h < \mst \ll ... More
Complete Resolution of the Quantum Zeno Paradox for Outside ObserversJan 27 2004The quantum Zeno paradox is fully resolved for purely indirect and incomplete measurements performed by the detectors outside the system. If the outside detectors are prepared to observe propagating signals of a decay event of an excited state in the ... More
The relativistic nuclear dynamics for the SU(3) Goldstone bosons of chiral QCDDec 04 2002In this habilitation theses the chiral SU(3) Lagrangian is applied to antikaon and hyperon propagation in cold nuclear matter. The self consistent many-body dynamics relies on a detailed analysis of the pion, kaon and antikaon-nucleon scattering data ... More
Migdal's short range correlations in a covariant modelOct 26 2002Aug 13 2003We construct a covariant model for short range correlations of a pion emerged in nuclear matter. Once the delta-hole contribution is considered an additional and so far neglected channel opens that leads to significant modifications in the vicinity of ... More
Resolution of Verb Ellipsis in Japanese Sentence using Surface Expressions and ExamplesDec 13 1999Verbs are sometimes omitted in Japanese sentences. It is necessary to recover omitted verbs for purposes of language understanding, machine translation, and conversational processing. This paper describes a practical way to recover omitted verbs by using ... More
Higgs PhysicsJan 27 2015Feb 23 2015We discuss the interpretation of the LHC Higgs data and the test of the Higgs mechanism. This is done in a more model-independent approach relying on an effective Lagrangian, as well as in specific models like composite Higgs models and supersymmetric ... More
The dynamical disconnection of sunspots from their magnetic rootsJun 27 2005After a dynamically active emergence phase, magnetic flux at the solar surface soon ceases to show strong signs of the subsurface dynamics of its parent magnetic structure. This indicates that some kind of disconnection of the emerged flux from its roots ... More
Partial cohomology of groupsSep 26 2013Dec 19 2014We develop a cohomology theory of groups based on partial actions and explore its relation with the partial Schur multiplier as well as with cohomology of inverse semigroups.
Boundary layer emission and Z-track in the color-color diagram of luminous LMXBsJun 01 2005Mar 09 2006We demonstrate that Fourier-frequency resolved spectra of atoll and Z- sources are identical, despite significant difference in their average spectra and luminosity (by a factor of ~10-20). This result fits in the picture we suggested earlier, namely ... More
Statistical Mechanics of the Hyper Vertex Cover ProblemJul 02 2007Jul 03 2007We introduce and study a new optimization problem called Hyper Vertex Cover. This problem is a generalization of the standard vertex cover to hypergraphs: one seeks a configuration of particles with minimal density such that every hyperedge of the hypergraph ... More
The Earliest Epoch of Reionisation in the Standard $Λ$CDM ModelMar 06 2003Jul 15 2003We show that the earliest possible reionisation of the Universe is approximately at $z\simeq 13.5$ and the optical depth is $\tau\simeq 0.17$ in the conventionally accepted $\Lambda$ cold dark matter ($\Lambda$CDM) model with adiabatic fluctuations of ... More
Consistency of Microcanonical and Canonical Finite-Size ScalingAug 07 2000Typically, in order to obtain finite-size scaling laws for quantities in the microcanonical ensemble, an assumption is taken as a starting point. In this paper, consistency of such a Microcanonical Finite-Size Scaling Assumption with its commonly accepted ... More
Neutron $2p$ and $1f$ spin--orbit splittings in $^{40}$Ca, $^{36}$S, and $^{34}$Si $N=20$ isotones: tensor--induced and pure spin--orbit effectsNov 04 2015Neutron $2p$ and $1f$ spin--orbit splittings were recently measured in the isotones $^{37}$S and $^{35}$Si by $(d,p)$ transfer reactions. Values were reported by using the major fragments of the states. An important reduction of the $p$ splitting was ... More
A Robust Scheme for PSS Detection and Integer Frequency Offset Recovery in LTE SystemsMay 12 2015Before establishing a communication link in a cellular network, the user terminal must activate a synchronization procedure called initial cell search in order to acquire specific information about the serving base station. To accomplish this task, the ... More
Data mining for cones of metrics, quasi-metrics, hemi-metrics and super-metricsJan 02 2002Dec 27 2002Using some adaptations of the adjacency decomposition method \cite{CR} and the program {\it cdd} (~\cite{Fu}), we compute the first computationally difficult cases of convex cones of $m$-ary and oriented analogs of semi-metrics and cut semi-metrics, which ... More
Dyadic shift randomization in classical discrepancy theorySep 06 2014Nov 16 2014Dyadic shifts of point distributions in the multi-dimensional unit cube are considered as a randomization. Explicit formulas for the discrepancies of such randomized distributions are given in the paper in terms of Rademacher functions. Relaying on the ... More
Holographic entanglement entropy of the BTZ black holeJul 09 2009Jul 22 2009We investigate quantum entanglement of gravitational configurations in 3D AdS gravity using the AdS/CFT correspondence. We derive explicit formulas for the holographic entanglement entropy (EE) of the BTZ black hole, conical singularities and regularized ... More
Pair excitations and the mean field approximation of interacting Bosons, IISep 19 2015Jul 31 2016We consider a large number of Bosons with interaction potential $v_N(x)=N^{3 \beta}v(N^{\beta}x)$. In earlier papers we considered a set of equations for the condensate $\phi$ and pair excitation function $k$ and proved that they provide a Fock space ... More
Singlet particles as cold dark matter in noncommutative space-timeMar 10 2009We extend the noncommutative (NC) standard model to incorporate singlet particles as cold dark matter. In the NC space-time, the singlet particles can be coupled to the U(1) gauge field in the adjoint representation. We Study the relic density of the ... More
Contractions on a manifold polarized by an ample vector bundleOct 27 1994A complex manifold $X$ of dimension $n$ together with an ample vector bundle $E$ on it will be called a {\sf generalized polarized variety}. The adjoint bundle of the pair $(X,E)$ is the line bundle $K_X + det(E)$. We study the positivity (the nefness ... More
On the twisted cohomology of arrangements of linesJul 07 2015Let $\A$ be an affine line arrangement in $\C^2,$ with complement $\M(\A).$ The twisted (co)homology of $\M(\A)$ is an interesting object which has been considered by many authors, strictly related to the (co)homology of the Milnor fibre associated to ... More
Scalar transport in compressible flowNov 29 1996Transport of scalar fields in compressible flow is investigated. The effective equations governing the transport at scales large compared to those of the advecting flow are derived by using multi-scale techniques. Ballistic transport generally takes place ... More
Color superconductivity in two- and three-flavor systems at moderate densitiesMay 02 2002May 06 2002Basic features of color superconductivity are reviewed, focusing on the regime of ``moderate densities'', which is not accessible by perturbation theory. We discuss the standard picture of two- and three flavor color superconductors and study the color-flavor ... More
Color-Flavor Unlocking and Phase Diagram with Self-Consistently Determined Strange Quark MassesSep 11 2001Dec 17 2001The phase diagram of strongly interacting matter at non-zero temperature and baryon chemical potential is calculated within a 3-flavor NJL-type quark model with realistic quark masses. The model exhibits spontaneous chiral symmetry breaking as well as ... More
Biorthogonal Laurent polynomials, Toeplitz determinants, minimal Toda orbits and isomonodromic tau functionsMar 23 2005We consider the class of biorthogonal polynomials that are used to solve the inverse spectral problem associated to elementary co-adjoint orbits of the Borel group of upper triangular matrices; these orbits are the phase space of generalized integrable ... More
Fractional supersymmetric Quantum Mechanics as a set of replicas of ordinary supersymmetric Quantum MechanicsDec 06 2003A connection between fractional supersymmetric quantum mechanics and ordinary supersymmetric quantum mechanics is established in this Letter.
Modeling the Spectral Energy Distribution and Variability of 3C 66A during the WEBT campaign of 2003 -- 2004Apr 03 2007The BL Lac object 3C 66A was observed in an extensive multiwavelength monitoring campaign from July 2003 till April 2004. The spectral energy distribution (SED) was measured over the entire electromagnetic spectrum, with flux measurements from radio to ... More
High confidence AGN candidates among unidentified Fermi-LAT sources via statistical classificationJun 27 2013The second Fermi-LAT source catalog (2FGL) is the deepest survey of the gamma-ray sky ever compiled, containing 1873 sources that constitute a very complete sample down to an energy flux of about 10^(-11) erg cm^(-2) s^(-1). While counterparts at lower ... More
Reliability of astrophysical jet simulations in 2D: On inter-code reliability and numerical convergenceOct 22 2001In the present paper, we examine the convergence behavior and inter-code reliability of astrophysical jet simulations in axial symmetry. We consider both, pure hydrodynamic jets and jets with a dynamically significant magnetic field. The setups were chosen ... More
Longitudinal top quark polarizationApr 20 2001Longitudinal polarization of the top quark, averaged over the production angle, is discussed for the top quark produced in e+e- annihilation near its production threshold. It is demonstrated that Coulomb type corrections and rescattering corrections are ... More
A new class of solutions of the DMPK equationMar 17 2003Sep 03 2003We introduce and discuss a new class of solutions of the DMPK equation in which some of the eigenvalues are grouped into clusters which are conserved in the asymptotic large distance limit (i.e. as the length of the wire increases). We give an explicit ... More
Wilson renormalization group and improved perturbation theoryMay 20 1997We discuss a resummed perturbation theory based on the Wilson renormalization group. In this formulation the Wilsonian flowing couplings, which generalize the running coupling, enter directly into the loop expansion. In the case of an asymptotically free ... More
An improvement of the BeppoSAX LECS and MECS positioning accuracyOct 04 2002We present a study of the source positioning accuracy of the LECS and MECS instruments on-board BeppoSAX. From the analysis of a sample of archival images we find that a systematic error, which depends on the spacecraft roll angle and has an amplitude ... More
J/psi Production via Fragmentation at the TevatronMay 06 1994May 31 1994The production of $\jpsi$ at large transverse momenta ($\pt > M_\jpsi$) in $p\bar p$ collisions is considered by including the mechanism of fragmentation. Both contributions of fragmentation to $\jpsi$ and of fragmentation to $\chi$ states followed by ... More
Floquet states and persistent currents transitions in a mesoscopic ringJul 10 2002We consider the effect of an oscillating potential on the single-particle spectrum and the time-averaged persistent current of a one-dimensional phase-coherent mesoscopic ring with a magnetic flux. We show that in a ring with an even number of spinless ... More
Scattering Theory of Dynamic Electrical TransportFeb 09 2005We have developed a scattering matrix approach to coherent transport through an adiabatically driven conductor based on photon-assisted processes. To describe the energy exchange with the pumping fields we expand the Floquet scattering matrix up to linear ... More
The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodogramsJan 16 2009The Lomb-Scargle periodogram is a common tool in the frequency analysis of unequally spaced data equivalent to least-squares fitting of sine waves. We give an analytic solution for the generalisation to a full sine wave fit, including an offset and weights ... More
Quasilocal Energy in FRW CosmologyMar 23 2009Oct 03 2009This paper presents a calculation of the quasilocal energy of a generic FRW model of the universe. The results have the correct behavior in the small-sphere limit and vanish for the empty Milne universe. Higher order corrections are found when comparing ... More
Ultrahigh energy neutrino interactions and weak-scale string theoriesMay 15 2000Oct 05 2000It has been suggested that ultrahigh energy neutrinos can acquire cross-sections approaching hadronic size if the string scale is as low as 1-10 TeV. In this case, the vertical air showers observed with energies above the Greisen-Zatsepin-Kuzmin cutoff ... More
Nonreciprocal Dispersion of Spin Waves in Ferromagnetic Thin Films Covered with a Finite-Conductivity MetalJan 29 2014We study the effect of one-side metallization of a uniform ferromagnetic thin film on its spin-wave dispersion relation in the Damon-Eshbach geometry. Due to the finite conductivity of the metallic cover layer on the ferromagnetic film the spin-wave dispersion ... More
Color fluctuation effects in proton-nucleus collisionsJan 04 2013Mar 21 2013Color fluctuations in hadron-hadron collisions are responsible for the presence of inelastic diffraction and lead to distinctive differences between the Gribov picture of high energy scattering and the low energy Glauber picture. We find that color fluctuations ... More
Mobile Phone Faraday CageDec 23 2011A Faraday cage is an interesting physics phenomena where an electromagnetic wave can be excluded from a volume of space by enclosure with an electrically conducting material. The practical application of this in the classroom is to block the signal to ... More
The Wonders of LevitationOct 27 2010I discuss some interesting classroom demonstrations of diamagnetism and how this effect can produce levitation. The possibilities for hands-on demonstrations of diamagnetic and superconducting levitation are discussed. To conclude I discuss some practical ... More
Kinetic theory of cluster impingement in the framework of statistical mechanics of rigid disksJul 09 2005The paper centres on the evaluation of the function n(theta)=N(theta)/N0, that is the normalized number of islands as a function of coverage 0<theta<1, given N0 initial nucleation centres (dots) having any degree of spatial correlation. A mean field approach ... More
Fractional Spin through Quantum Affine Algebra $\hat A(n)$ and quantum affine superalgebra $\hat A(n,m)$Oct 29 2000Using the splitting of a $Q$-deformed boson, in the $Q \to q= e^{\frac{\rm 2\pi i}{\rm k}}$ limit, the fractional decomposition of the quantum affine algebra $\hat A(n)$ and the quantum affine superalgebra $\hat A(n,m)$ are found. This decomposition is ... More
Sterile neutrino dark matter as a consequence of nuMSM-induced lepton asymmetryApr 29 2008Jun 29 2008It has been pointed out in ref.[1] that in the nuMSM (Standard Model extended by three right-handed neutrinos with masses smaller than the electroweak scale), there is a corner in the parameter space where CP-violating resonant oscillations among the ... More
Thermodynamics of Non-Topological SolitonsApr 06 1998In theories with low energy supersymmetry breaking, the effective potential for squarks and sleptons has generically nearly flat directions, V(phi) ~ M^4 (log(phi/M))^n. This guarantees the existence of stable non-topological solitons, Q-balls, that carry ... More
Diffraction for non-believersNov 04 2005Diffractive reactions involving a hard scale can be understood in terms of quarks and gluons. These reactions have become a valuable tool for investigating the low-x structure of the proton and the behavior of QCD in the high-density regime, and they ... More
Signal and noise simulation of CUORE bolometric detectorsJun 20 2011Jul 18 2011Bolometric detectors are used in particle physics experiments to search for rare processes, such as neutrinoless double beta decay and dark matter interactions. By operating at cryogenic temperatures, they are able to detect particle energies from a few ... More
Fine structure of two-electron states in single and double quantum dotsAug 21 2009Aug 22 2009Energy spectrum fine structure of triplet two-electron states is investigated theoretically. Spin-orbit interaction induced terms in the effective Hamiltonian of electron-electron interaction are derived for zinc-blende lattice semiconductor nanostructures: ... More
Magnetic field effects on spin relaxation in heterostructuresJun 16 2004Effect of magnetic field on electron spin relaxation in quantum wells is studied theoretically. We have shown that Larmor effect and cyclotron motion of carriers can either jointly suppress D'yakonov-Perel' spin relaxation or compensate each other. The ... More
K-minus Estimator Approach to Large Scale StructureAug 01 2007Self similar 3D distributions of point-particles, with a given quasifractal dimension D, were generated on a Menger sponge model and then compared with \textit{2dfGRS} and \textit{Virgo project} data \footnote{,}. ... More
Systematic study of longitudinal and transverse helicity amplitudes in the hypercentral Constituent Quark ModelJun 19 2015The predictions of the hypercentral Consituent Quark Model for the nucleon helicity amplitudes are briefly reported. Some future perspectives are also discussed.
Introduction: GDH and related topicsJan 07 2003The formulation of the Gerasimov-Drell-Hearn sum rule is revisited, showing its connection with other sum rules occurring in electron scattering and discussing the problem of its saturation, both from the theoretical and experimental point of v iew. The ... More
Multiflavor QCD* on R_3 x S_1: Studying Transition From Abelian to Non-Abelian ConfinementJan 23 2009The center-stabilized multiflavor QCD* theories formulated on R_3 x S_1 exhibit both Abelian and non-Abelian confinement as a function of the S_1 radius, similar to the Seiberg-Witten theory as a function of the mass deformation parameter. For sufficiently ... More
Confinement in Yang--Mills: Elements of a Big PictureOct 21 2008Nov 12 2008We present a nontechnical review of the current understanding of the phenomenon of color confinement. The emphasis is put on recent advances. This is a combined and slightly expanded version of talks delivered at 14th International QCD Conference "QCD ... More
String vacua with flux from freely-acting obifoldsOct 27 2003Jan 12 2004A precise correspondence between freely-acting orbifolds (Scherk-Schwarz compactifications) and string vacua with NSNS flux turned on is established using T-duality. We focus our attention to a certain non-compact Z_2 heterotic freely-acting orbifold ... More
Junction conditions for F(R)-gravity and their consequencesMar 06 2013Jun 04 2013I present the junction conditions for F(R) theories of gravity and their implications: the generalized Israel conditions and equations. These junction conditions are necessary to construct global models of stars, galaxies, etc., where a vacuum region ... More
Report on workshop A1: Exact solutions and their interpretationOct 29 2007Nov 29 2007I report on the communications and posters presented on exact solutions and their interpretation at the GRG18 Conference, Sydney.
Symmetric hyperbolic systems for a large class of fields in arbitrary dimensionJul 26 2006Symmetric hyperbolic systems of equations are explicitly constructed for a general class of tensor fields by considering their structure as r-fold forms. The hyperbolizations depend on 2r-1 arbitrary timelike vectors. The importance of the so-called "superenergy" ... More
General Electric-Magnetic decomposition of fields, positivity and Rainich-like conditionsOct 25 2000Oct 29 2000We show how to generalize the classical electric-magnetic decomposition of the Maxwell or the Weyl tensors to arbitrary fields described by tensors of any rank in general $n$-dimensional spacetimes of Lorentzian signature. The properties and applications ... More
New conservation laws for electromagnetic fields in gravityNov 10 2003A recently found (gr-qc/0303036) 2-index, symmetric, trace-free, divergence-free tensor is introduced for arbitrary source-free electromagnetic fields. The tensor can be constructed for any test Maxwell field in Einstein spaces (including proper vacuum), ... More
Novel results on trapped surfacesNov 03 2003A unifying definition of trapped submanifold for arbitrary codimension by means of its mean curvature vector is presented. Then, the interplay between (generalized) symmetries and trapped submanifolds is studied, proving in particular that (i) stationary ... More
Adiabatic theory of off-center vibronic polarons: Local dynamics and itinerant features along a linear chainJan 18 2006The vibronic mixing by an odd-parity vibrational mode of two opposite-parity nearly-degenerate electronic states at a molecular site may drive the small polaron off-center. An associated electric dipole may occur due to broken inversion symmetry which ... More
The long wavelength view of GG Tau A: Rocks in the Ring WorldJul 19 2013We present the first detection of GG Tau A at centimeter-wavelengths, made with the Arcminute Microkelvin Imager Large Array (AMI-LA) at a frequency of 16 GHz ({\lambda} = 1.8 cm). The source is detected at > 6 {\sigma}_{rms} with an integrated flux density ... More
Precise predictions for Higgs production at e+ e- colliders and Numerical calculation of one-loop integralsOct 12 2004Some of the most interesting Higgs-production processes at future e+ e- colliders are of the type e+ e- -> f anti-f H. We present a calculation of the complete O(alpha) corrections to these processes in the Standard Model for final-state neutrinos and ... More
Existence of Multiagent Equilibria with Limited AgentsJun 30 2011Multiagent learning is a necessary yet challenging problem as multiagent systems become more prevalent and environments become more dynamic. Much of the groundbreaking work in this area draws on notable results from game theory, in particular, the concept ... More
Ideal quantum glass transitions: many-body localization without quenched disorderSep 04 2013Nov 06 2013We explore the possibility for translationally invariant quantum many-body systems to undergo a dynamical glass transition, at which ergodicity and translational invariance break down spontaneously, driven entirely by quantum effects. In contrast to analogous ... More
Topological Terms in String Theory on OrbifoldsSep 21 1994We study toroidal orbifold models with topologically invariant terms in the path integral formalism and give physical interpretations of the terms from an operator formalism point of view. We briefly discuss a possibility of a new class of modular invariant ... More
Analysis of $f(R)$ Theory Corresponding to NADE and NHDEOct 14 2013We develop the connection of $f(R)$ theory with new agegraphic and holographic dark energy models. The function $f(R)$ is reconstructed, regarding the $f(R)$ theory as an effective description for these dark energy models. We show the future evolution ... More
Cosmology of Holographic and New Agegraphic $f(R,T)$ ModelsAug 29 2013We consider the $f(R,T)$ theory, where $R$ is the scalar curvature and $T$ is the trace of energy-momentum tensor, as an effective description for the holographic and new agegraphic dark energy and reconstruct the corresponding $f(R,T)$ functions. In ... More
Stability of Thin-Shell Wormholes in Nonlinear ElectrodynamicsJun 17 2013In this paper, we construct thin-shell wormholes by applying the cut and paste procedure to a regular charged black hole in nonlinear electrodynamics field. We discuss different physical aspects of wormholes such as, the possible equation of state to ... More
The Stability of a Shearing Viscous Star with Electromagnetic FieldDec 04 2013We analyze the role of electromagnetic field for the stability of shearing viscous star with spherical symmetry. Matching conditions are given for the interior and exterior metrics. We use perturbation scheme to construct the collapse equation. The range ... More
Mechanical Stability of Cylindrical Thin-Shell WormholesJul 31 2013Aug 07 2013In this paper, we apply the cut and paste procedure to charged black string for the construction of thin-shell wormhole. We consider the Darmois-Israel formalism to determine the surface stresses of the shell. We take Chaplygin gas to deal with the matter ... More
Stability of Anisotropic Cylinder with Zero ExpansionMay 24 2013We study the dynamical instability of anisotropic collapsing cylinder with the expansion-free condition, which generates vacuum cavity within fluid distribution. The perturbation scheme is applied to distinguish Newtonian, post-Newtonian and post-post ... More
Energy-Momentum Distribution: Some ExamplesDec 08 2006In this paper, we elaborate the problem of energy-momentum in General Relativity with the help of some well-known solutions. In this connection, we use the prescriptions of Einstein, Landau-Lifshitz, Papapetrou and M\"{o}ller to compute the energy-momentum ... More
Multiparameter quantum function algebra at roots of 1Oct 15 1994We study the theory of representations of a multiparameter deformation of the function algebra of a simple algebraic group (as defined by Reshetikhin) when the quantum parameter is a root of unity. We extend the technics of De Concini-Lyubashenko in the ... More
Exceptional sets in dynamical systems and Diophantine approximationAug 30 2001The nature and origin of exceptional sets associated with the rotation number of circle maps, Kolmogorov-Arnol'd-Moser theory on the existence of invariant tori and the linearisation of complex diffeomorphisms are explained. The metrical properties of ... More
Linear Hilbertian manifold domainsAug 20 2003Necessary and sufficient conditions for a dense subspace of a Hilbert space to be a linear Hilbertian manifold domain are given. Some relations between linear Hilbertian manifold domains and domains of self-adjoint operators are found.
The central charge in three dimensional anti-de Sitter spaceJun 11 1998This paper collects the various ways of computing the central charge $c=3l/2G$ arising in 3d asymptotically anti-de Sitter spaces, in the Chern-Simons formulation. Their similarities and differences are displayed.