Results for "M. Grech"

total 207753took 0.10s
Optimal parametrizations of adiabatic pathsMar 10 2010May 18 2010The parametrization of adiabatic paths is optimal when tunneling is minimized. Hamiltonian evolutions do not have unique optimizers. However, dephasing Lindblad evolutions do. The optimizers are simply characterized by an Euler-Lagrange equation and have ... More
High-quality ion beams by irradiating a nano-structured target with a petawatt laser pulseJun 22 2009Sep 21 2009We present a novel laser based ion acceleration scheme, where a petawatt circularly polarized laser pulse is shot on an ultra-thin (nano-scale) double-layer target. Our scheme allows the production of high-quality light ion beams with both energy and ... More
Adiabatic theorems for generators of contracting evolutionsJun 23 2011Jun 04 2012We develop an adiabatic theory for generators of contracting evolution on Banach spaces. This provides a uniform framework for a host of adiabatic theorems ranging from unitary quantum evolutions through quantum evolutions of open systems generated by ... More
Kinetic effects on the transition to relativistic self-induced transparency in laser-driven ion accelerationMar 21 2016Oct 04 2016We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring and ion acceleration. It is shown, using ... More
From quantum to classical modelling of radiation reaction: a focus on stochasticity effectsJul 09 2017Feb 08 2018Radiation-reaction in the interaction of ultra-relativistic electrons with a strong external electromagnetic field is investigated using a kinetic approach in the weakly quantum regime ($\chi \lesssim 1$, with $\chi$ the electron quantum parameter). Three ... More
Simple Scalings for Various Regimes of Electron Acceleration in Surface Plasma WavesJun 28 2015Different electron acceleration regimes in the evanescent field of a surface plasma wave are studied by considering the interaction of a test electron with the high-frequency electromagnetic field of a surface wave. The non-relativistic and relativistic ... More
Landau-Zener tunneling for dephasing Lindblad evolutionsDec 23 2009Mar 29 2010We derive an analog of the Landau-Zener adiabatic tunneling formula for an open, two-level system coupled to a memoryless, dephasing bath. The derivation rests on a geometric view of the spectral subspaces as adiabatic invariants.
High-quality ion beams from a nanometric double-layer target and their application to hadron-therapySep 21 2009Dec 21 2009The production of ion beams from the interaction of a circularly polarized laser pulse with a nanometric double-layer target is discussed in the regime where all electrons are expelled from the target by laser radiation pressure. Quasi-monochromatic, ... More
Decompositions of the authomorphism groups of edge-colored graphs into the direct product of permutation groupsMar 18 2019In the paper Graphical complexity of products of permutation groups, M. Grech, A. Jez, A. Kisielewicz have proved that the direct product of automorphism groups of edge-colored graphs is itself the automorphism groups of an edge-colored graph. In this ... More
Graphical Cyclic Permutation GroupsOct 25 2012We establish conditions for a permutation group generated by a single permutation of a prime power order to be an automorphism group of a graph or an edge-colored graph. This corrects and generalizes the results of the two papers on cyclic permutation ... More
Second Loop Corrections from Superheavy Gauge Sector to Gauge Coupling UnificationMar 17 1999Aug 04 1999We deal with extensions of the Standard Model by adding horizontal interactions between particle generations. We calculate two loop corrections caused by the presence of coupling between hypothetical horizontal gauge bosons and matter fields, both at ... More
From quantum to classical modelling of radiation reaction: a focus on the radiation spectrumFeb 08 2018Soon available multi petawatt ultra-high-intensity (UHI) lasers will allow us to probe high-amplitude electromagnetic fields interacting with either ultra-relativistic electron beams or hot plasmas in the so-called moderately quantum regime. The correct ... More
Coherent forward stimulated Brillouin scattering of a spatially incoherent laser beam in a plasma and its effect on beam sprayMay 20 2008A statistical model for forward stimulated Brillouin scattering (FSBS) is developed for a spatially incoherent, monochromatic, laser beam propagating in a plasma. A threshold for the average power in a speckle is found, well below the self-focusing one, ... More
Effect of electron heating on self-induced transparency in relativistic intensity laser-plasma interactionSep 14 2012Nov 15 2012The effective increase of the critical density associated with the interaction of relativistically intense laser pulses with overcritical plasmas, known as self-induced transparency, is revisited for the case of circular polarization. A comparison of ... More
Energy dispersion in radiation pressure accelerated ion beamsMay 24 2011We address the problem of energy dispersion of radiation pressure accelerated (RPA) ion beams emerging from a thin (solid) target. Two different acceleration schemes, namely phase-stable acceleration and multi-stage acceleration, are considered by means ... More
Electron Weibel Instability in Relativistic Counter-Streaming Plasmas with Flow-Aligned External Magnetic FieldsDec 12 2016The Weibel instability driven by two symmetric counter-streaming relativistic electron plasmas, also referred to as current-filamentation instability, is studied in a constant and uniform external magnetic field aligned with the plasma flows. Both the ... More
Multifractal dynamics of stock marketsDec 17 2009We present a comparative analysis of multifractal properties of financial time series built on stock indices from developing (WIG) and developed (S&P500) financial markets. It is shown how the multifractal image of the market is altered with the change ... More
Can One Make Any Crash Prediction in Finance Using the Local Hurst Exponent Idea?Nov 27 2003We apply the Hurst exponent idea for investigation of DJIA index time-series data. The behavior of the local Hurst exponent prior to drastic changes in financial series signal is analyzed. The optimal length of the time-window over which this exponent ... More
Impact of scaling range on the effectiveness of detrending methodsSep 23 2013Nov 04 2013We make the comparative study of scaling range properties for detrended fluctuation analysis (DFA), detrended moving average analysis (DMA) and recently proposed new technique called modified detrended moving average analysis (MDMA). Basic properties ... More
Oblique-incidence, arbitrary-profile wave injection for electromagnetic simulationsSep 12 2018In an electromagnetic code, a wave can be injected in the simulation domain by prescribing an oscillating field profile at the domain boundary. The process is straightforward when the field profile has a known analytical expression (typically, paraxial ... More
All totally symmetric colored graphsJan 21 2012In this paper we describe all edge-colored graphs that are fully symmetric with respect to colors and transitive on every set of edges of the same color. They correspond to fully symmetric homogeneous factorizations of complete graphs. Our description ... More
On the scaling range of power-laws originated from fluctuation analysisDec 20 2012We extend our previous study of scaling range properties done for detrended fluctuation analysis (DFA) \cite{former_paper} to other techniques of fluctuation analysis (FA). The new technique called Modified Detrended Moving Average Analysis (MDMA) is ... More
Identification of cross and autocorrelations in time series within an approach based on Wigner eigenspectrum of random matricesJul 17 2014We present an original and novel method based on random matrix approach that enables to distinguish the respective role of temporal autocorrelations inside given time series and cross correlations between various time series. The proposed algorithm is ... More
Symmetry groups of Boolean FunctionsMar 06 2013We prove that every abelian permutation group, but known exceptions, is the symmetry group of a boolean function. This solves the problem posed in the book by Clote and Kranakis. In fact, our result is proved for a larger class of groups, namely, for ... More
The Local Fractal Properties of the Financial Time Series on the Polish Stock Exchange MarketAug 02 2007We investigate the local fractal properties of the financial time series based on the evolution of the Warsaw Stock Exchange Index (WIG) connected with the largest developing financial market in Europe. Calculating the local Hurst exponent for the WIG ... More
Numerical Simulation of the Perrin - like ExperimentsDec 19 2006Feb 07 2007A simple model of random Brownian walk of a spherical mesoscopic particle in viscous liquids is proposed. The model can be both solved analytically and simulated numerically. The analytic solution gives the known Eistein-Smoluchowski diffusion law $<r^2> ... More
Comparison study of DFA and DMA methods in analysis of autocorrelations in time seriesJul 16 2005Statistics of the Hurst scaling exponents calculated with the use of two methods: recently introduced Detrended Moving Average Analysis(DMA) and Detrended Fluctuation Analysis (DFA)are compared. Analysis is done for artificial stochastic Brownian time ... More
The problem of friction in two-dimensional relative motionJun 07 2000Jul 31 2000We analyse a mechanical system in two-dimensional relative motion with friction. Although the system is simple, the peculiar interplay between two kinetic friction forces and gravity leads to the wide range of admissible solutions exceeding most intuitive ... More
On the scaling ranges of detrended fluctuation analysis for long-memory correlated short series of dataJun 05 2012We examine the scaling regime for the detrended fluctuation analysis (DFA) - the most popular method used to detect the presence of long memory in data and the fractal structure of time series. First, the scaling range for DFA is studied for uncorrelated ... More
Effects of maximal fluctuation moment $q$ and detrending polynomial orders on the observed multifractal features within MFDFAJul 13 2013Jul 25 2013We focus on the importance of $q$ moments range used within multifractal detrended fluctuation analysis (MFDFA) to calculate the generalized Hurst exponent spread and multifractal properties of signals. Different orders of detrending polynomials are also ... More
How much multifractality is included in monofractal signals?Aug 09 2011Sep 25 2011We investigate the presence of residual multifractal background for monofractal signals which appears due to the finite length of the signals and (or) due to the long memory the signals reveal. This phenomenon is investigated numerically within the multifractal ... More
New measure of multifractality and its application in financesSep 21 2013We provide an alternative method for analysis of multifractal properties of time series. The new approach takes into account the behaviour of the whole multifractal profile of the generalized Hurst exponent $h(q)$ for all moment orders $q$, not limited ... More
The excitation spectrum for weakly interacting bosons in a trapMay 23 2012We investigate the low-energy excitation spectrum of a Bose gas confined in a trap, with weak long-range repulsive interactions. In particular, we prove that the spectrum can be described in terms of the eigenvalues of an effective one-particle operator, ... More
An Adiabatic Theorem for the Gross-Pitaevskii EquationAug 10 2015Aug 12 2015We prove an adiabatic theorem for the non-autonomous Gross-Pitaevskii equation in the case of a weak trap. More precisely, we assume that the external potential decays suitably at infinity and admits exactly one bound state.
Random matrix approach in search for weak signals immersed in background noiseJul 14 2011We present new, original and alternative method for searching signals coded in noisy data. The method is based on the properties of random matrix eigenvalue spectra. First, we describe general ideas and support them with results of numerical simulations ... More
On the multifractal effects generated by monofractal signalsJul 08 2013Aug 24 2013We study quantitatively the level of false multifractal signal one may encounter while analyzing multifractal phenomena in time series within multifractal detrended fluctuation analysis (MF-DFA). The investigated effect appears as a result of finite length ... More
Coulomb explosion of uniformly charged spheroidsMay 02 2011Jul 05 2011A simple, semi-analytical model is proposed for non-relativistic Coulomb explosion of a uniformly charged spheroid. This model allows us to derive the time-dependent particle energy distributions. Simple expressions are also given for the characteristic ... More
Perpendicular relativistic shocks in magnetized pair plasmaDec 07 2017Perpendicular relativistic ($\gamma_0=10$) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the ... More
On the Zipf strategy for short-term investments in WIG20 futuresJul 17 2011We apply the Zipf power law to financial time series of WIG20 index daily changes (open-close). Thanks to the mapping of time series signal into the sequence of 2k+1 'spin-like' states, where k=0, 1/2, 1, 3/2, ..., we are able to describe any time series ... More
Perpendicular relativistic shocks in magnetized pair plasmaDec 07 2017Apr 24 2018Perpendicular relativistic ($\gamma_0=10$) shocks in magnetized pair plasmas are investigated using two dimensional Particle-in-Cell simulations. A systematic survey, from unmagnetized to strongly magnetized shocks, is presented accurately capturing the ... More
The Spectral Structure of the Electronic Black Box HamiltonianAug 12 2012We give results on the absence of singular continuous spectrum of the one-particle Hamiltonian underlying the electronic black box model.
Anomalous Self-Generated Electrostatic Fields in Nanosecond Laser-Plasma InteractionJan 04 2011Electrostatic (E) fields associated with the interaction of a well-controlled, high-power, nanosecond laser pulse with an underdense plasma are diagnosed by proton radiography. Using a current 3D wave propagation code equipped with nonlinear and nonlocal ... More
Radiation Pressure Driven Ion Weibel Instability and Collisionless ShocksMay 15 2017Aug 11 2017The Weibel instability from counterstreaming plasma flows is a basic process highly relevant for collisionless shock formation in astrophysics. In this Letter we investigate, via two- and three- dimensional simulations, suitable configurations for laboratory ... More
Heaps Don't Lie: Countering Unsoundness with Heap SnapshotsMay 06 2019Static analyses aspire to explore all possible executions in order to achieve soundness. Yet, in practice, they fail to capture common dynamic behavior. Enhancing static analyses with dynamic information is a common pattern, with tools such as Tamiflex. ... More
A Morphological Study of the Supernova Remnant RX J0852.0-4622 (Vela Jr.)Sep 06 2018We conduct a multi-wavelength morphological study of the Galactic supernova remnant RXJ0852.0-4622 (also known as Vela Jr., Vela Z and G266.2-1.2). RX J0852.0-4622 is coincident with the edge of the larger Vela supernova remnant causing confusion in the ... More
Static analysis of energy consumption for LLVM IR programsMay 18 2014Jul 16 2015Energy models can be constructed by characterizing the energy consumed by executing each instruction in a processor's instruction set. This can be used to determine how much energy is required to execute a sequence of assembly instructions, without the ... More
Modeling of radiative and quantum electrodynamics effects in PIC simulations of ultra-relativistic laser-plasma interactionNov 05 2013Nov 06 2013Next generation of ultra-intense laser facilities will lead to novel physical conditions ruled by collective and quantum electrodynamics effects, such as synchrotron-like emission of high-energy photons and electron-positron pair generation. In view of ... More
Adaptive SIMD optimizations in particle-in-cell codes with fine-grain particle sortingOct 09 2018Particle-In-Cell (PIC) codes are broadly applied to the kinetic simulation of plasmas, from laser-matter interaction to astrophysics. Their heavy simulation cost can be mitigated by using the Single Instruction Multiple Data (SIMD) capibility, or vectorization, ... 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
Lorentz Conserving Noncommutative Standard ModelMar 29 2007May 10 2007We consider Lorentz conserving noncommutative field theory to construct the Lorentz conserving noncommutative standard model based on the gauge group $SU(3)\times SU(2)\times U(1)$. We obtain the enveloping algebra-valued of Higgs field up to the second ... More
Shelving and Probe Efficiency in Trapped Ion ExperimentsFeb 24 2014A generalized probe sequence typical of trapped ion experiments using shelving is studied. Detection efficiency is analyzed for finite shelved state lifetimes and using multi-modal count distributions. Multi-modal distributions are more appropriate for ... More
The Neutralino Relic Density in Minimal N=1 SupergravityJul 10 1992We compute the cosmic relic (dark matter) density of the lightest supersymmetric particle (LSP) in the framework of minimal $N=1$ Supergravity models with radiative breaking of the electroweak gauge symmetry. To this end, we re--calculate the cross sections ... More
Quantization and $2π$ Periodicity of the Axion Action in Topological InsulatorsJun 17 2010Nov 10 2010The Lagrangian describing the bulk electromagnetic response of a three-dimensional strong topological insulator contains a topological `axion' term of the form '\theta E dot B'. It is often stated (without proof) that the corresponding action is quantized ... More
Massive Neutrino in Non-commutative Space-timeDec 24 2007Apr 01 2008We consider the noncommutative standard model based on $SU(3)\times SU(2)\times U(1)$. We study the gauge transformation of right handed neutrino and its direct interaction with photon in the noncommutative space-time. We show that the massive Dirac neutrinos, ... More
Infinite order excitonic Bloch equations for asymmetric nanostructuresJul 04 2003We present a new exciton-based formalism for calculating the coherent response of asymmetric semiconductor multiple quantum well structures to ultra-short optical pulses valid to infinite order in the optical field and including the self-generated intraband ... More
Scalar StoponiumAug 18 1993We study the decays of a scalar \stst\ bound state \sigst, 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 $m_h < \mst \ll \mstt$, a pair of light scalar Higgs bosons ... More
Neutralino-Nucleon Scattering RevisitedJul 01 1993We present a detailed discussion of the elastic scattering of a supersymmetric neutralino off a nucleon or nucleus, with emphasis on the spin--independent interaction. We carefully treat QCD effects on the squark exchange contribution. In particular, ... More
Quantum information processing: The case of vanishing interaction energyOct 27 2002We investigate the rate of operation of quantum "black boxes" ("oracles") and point out the possibility of performing an operation by a quantum "oracle" whose average energy equals zero. This counterintuitive result not only presents a generalization ... More
Self-Organized Topological State with Majorana FermionsJul 08 2013Nov 06 2013Topological phases, quite generally, are difficult to come by. They either occur under rather extreme conditions (e.g. the quantum Hall liquids, which require high sample purity, strong magnetic fields and low temperatures) or demand fine tuning of system ... More
Spin Response of Electrons on the Surface of a Topological InsulatorJan 11 2012The surface of a topological insulator hosts a very special form of a quasi-two dimensional metallic system when it is embedded in a topologically trivial medium like the vacuum. The electronic properties of this unusual 2D metal are distinct in many ... 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
Photon Neutrino Scattering in Non-Commutative SpaceNov 04 2005Jan 19 2006We extend the non-commutative standard model based on the minimal $SU(3)\times SU(2)\times U(1)$ gauge group to include the interaction of photon with neutrino. We show that, in the gauge invariant manner, only the right handed neutrino can directly couple ... 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
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
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.
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