Results for "Luca Fossati"

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Cold gas in hot star clusters: the wind from the red supergiant W26 in Westerlund 1Aug 27 2015The massive red supergiant (RSG) W26 in Westerlund 1 is one of a growing number of RSGs shown to have winds that are ionized from the outside in. The fate of this dense wind material is important for models of second generation star formation in massive ... More
Chemical abundance studies of CP stars in open clustersNov 22 2013In stellar astrophysics, the study of the atmospheres of early-type stars plays a very special role. The atmospheres of these stars display a variety of different phenomena, such as the presence of large magnetic fields, strong surface convection, pulsation, ... More
Observational consequences of turbulent pressure in the envelopes of massive starsJul 14 2015The major mass fraction of the envelope of hot luminous stars is radiatively stable. However, the partial ionisation of hydrogen, helium and iron gives rise to extended sub-surface convection zones in all of them. In this work, we investigate the effect ... More
Aerosol Constraints on the Atmosphere of the Hot Saturn-mass planet WASP-49bOct 06 2017The strong, nearly wavelength-independent absorption cross section of aerosols produces featureless exoplanet transmission spectra, limiting our ability to characterize their atmospheres. Here we show that even in the presence of featureless spectra, ... More
Colorado Ultraviolet Transit Experiment Data SimulatorMar 08 2019The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying on-board a low-resolution (R~2000--3000), near-ultraviolet (2500--3300 {\AA}) spectrograph. It has a rectangular primary Cassegrain telescope to maximize the collecting area. ... More
An Overabundance of Low-density Neptune-like PlanetsNov 28 2016We present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to $M_{\rm p}<30\,M_{\oplus}$). For each planet we compute the restricted Jeans escape parameter, $\Lambda$, for a hydrogen ... More
Spectral Energy Distributions of Gamma-ray BlazarsDec 09 1996Average Spectral Energy Distributions (SED) for different subgroups of blazars are derived from available homogeneous (but small) data sets, including the gamma-ray band. Comparing Flat Spectrum Radio Quasars (FSRQ) with BL Lacs extracted from radio (RBL) ... More
The importance of non-photon noise in stellar spectropolarimetry. The spurious detection of a non-existing magnetic field in the A0 supergiant HD 92207Sep 09 2013Sep 13 2013The low-resolution, Cassegrain mounted, FORS spectropolarimeter of the ESO Very Large Telescope is being extensively used for magnetic field surveys. Some of the new discoveries suggest that relatively strong magnetic fields may play an important role ... More
Chemical composition of intermediate mass stars members of the M6 (NGC 6405) open clusterOct 19 2015We present here the first abundance analysis of 44 late B, A and F-type members of the young open cluster M6 (NGC 6405, age about 75 Myrs). Spectra, covering the 4500 to 5800 \AA{} wavelength range, were obtained using the FLAMES/GIRAFFE spectrograph ... More
Chemical composition of A and F dwarfs members of the Hyades open clusterJun 28 2010Abundances of 15 chemical elements have been derived for 28 F and 16 A stars members of the Hyades open cluster in order to set constraints on self-consistent evolutionary models including radiative and turbulent diffusion. A spectral synthesis iterative ... More
GAUFRE: a tool for an automated determination of atmospheric parameters from spectroscopyJan 30 2013We present an automated tool for measuring atmospheric parameters (T_eff, log(g), [Fe/H]) for F-G-K dwarf and giant stars. The tool, called GAUFRE, is written in C++ and composed of several routines: GAUFRE-RV measures radial velocity from spectra via ... More
Tracing early stellar evolution with asteroseismology: pre-main sequence stars in NGC 2264Nov 03 2014Asteroseismology has been proven to be a successful tool to unravel details of the internal structure for different types of stars in various stages of their main sequence and post-main sequence evolution. Recently, we found a relation between the detected ... More
Diagnostic of the unstable envelopes of Wolf-Rayet starsMar 29 2016The envelopes of stars near the Eddington limit are prone to various instabilities. A high Eddington factor in connection with the Fe opacity peak leads to convective instability, and a corresponding envelope inflation may induce pulsational instability. ... More
Relating turbulent pressure and macroturbulence across the HR diagram with a possible link to γ-Dor starsNov 04 2015A significant fraction of the envelope of low- and intermediate-mass stars is unstable to convection, leading to sub-surface turbulent motion. Here, we consider and include the effects of turbulence pressure in our stellar evolution calculations. In search ... More
Metallicity dependence of turbulent pressure and macroturbulence in stellar envelopesAug 02 2016Macroturbulence, introduced as a fudge to reproduce the width and shape of stellar absorption lines, reflects gas motions in stellar atmospheres. While in cool stars, it is thought to be caused by convection zones immediately beneath the stellar surface, ... More
Using the SED to locate the Gamma-ray emission site of powerful blazarsFeb 28 2012The location of the Gamma-ray emission of powerful blazars is a matter of active debate. Is the location within the UV emitting sub-pc scale broad line region, or farther out at pc scales where the molecular torus IR emission dominates? We present a diagnostic ... More
The magnetic fields of hot subdwarf starsMar 30 2012Detection of magnetic fields has been reported in several sdO and sdB stars. Recent literature has cast doubts on the reliability of most of these detections. We revisit data previously published in the literature, and we present new observations to clarify ... More
Confronting uncertainties in stellar physics: calibrating convective overshooting with eclipsing binariesJan 21 2015As part of a larger program aimed at better quantifying the uncertainties in stellar computations, we attempt to calibrate the extent of convective overshooting in low to intermediate mass stars by means of eclipsing binary systems. We model 12 such systems, ... More
Generation of a Circumstellar Gas Disk by Hot Jupiter WASP-12bMay 02 2018Observations of transiting extra-solar planets provide rich sources of data for probing the in-system environment. In the WASP-12 system, a broad depression in the usually-bright MgII h&k lines has been observed, in addition to atmospheric escape from ... More
An In-Depth Spectroscopic Analysis of the Blazhko Star RR Lyr. I. Characterisation of the star: abundance analysis and fundamental parametersApr 28 2010The knowledge of accurate stellar parameters is a keystone in several fields of stellar astrophysics, such as asteroseismology and stellar evolution. Although the fundamental parameters can be derived both from spectroscopy and multicolour photometry, ... More
CUTE Data Simulator and Reduction PipelineJul 20 2018The Colorado Ultraviolet Transit Experiment (CUTE) is a 6U NASA CubeSat carrying a low-resolution (R ~3000), near-ultraviolet (255 - 330nm) spectrograph fed by a rectangular primary Cassegrain. CUTE, is planned for launch in spring 2020 and it will monitor ... More
Rejuvenation of stellar mergers and the origin of magnetic fields in massive starsJan 19 2016Approximately 10% of massive OBA main-sequence (MS) and pre-MS stars harbour strong, large-scale magnetic fields. At the same time there is a dearth of magnetic stars in close binaries. A process generating strong magnetic fields only in some stars must ... More
Polarimetric StandardizationOct 09 2006The use of polarimetric techniques is nowadays widespread among solar and stellar astronomers. However, notwithstanding the recommandations that have often been made about the publication of polarimetric results in the astronomical literature, we are ... More
Stellar physics with high-resolution UV spectropolarimetryMar 15 2019Current burning issues in stellar physics, for both hot and cool stars, concern their magnetism. In hot stars, stable magnetic fields of fossil origin impact their stellar structure and circumstellar environment, with a likely major role in stellar evolution. ... More
Breaking the Blazar Sequence: A New View of Radio Loud AGN UnificationMay 03 2012In recent work, we have identified two sub-populations of radio-loud AGN which appear to be distinguished by jet structure, where low-efficiency accreting systems produce `weak' jets which decelerate more rapidly than the `strong' jets of black holes ... More
Toward a New Paradigm for the Unification of Radio Loud AGN and its Connection to AccretionNov 21 2011We recently argued (Meyer 2011) that the collective properties of radio loud active galactic nuclei point to the existence of two families of sources, one of powerful sources with single velocity jets and one of weaker jets with significant velocity gradients ... More
A grid of upper atmosphere models for 1--40 MEARTH planets: application to CoRoT-7 b and HD219134 b,cSep 18 2018There is growing observational and theoretical evidence suggesting that atmospheric escape is a key driver of planetary evolution. Commonly, planetary evolution models employ simple analytic formulae (e.g., energy limited escape) that are often inaccurate, ... More
Far-Ultraviolet Activity Levels of F, G, K, and M dwarf Exoplanet Host StarsSep 19 2018We present a survey of far-ultraviolet (FUV; 1150 - 1450 Ang) emission line spectra from 71 planet-hosting and 33 non-planet-hosting F, G, K, and M dwarfs with the goals of characterizing their range of FUV activity levels, calibrating the FUV activity ... More
Quantum bright solitons in a quasi-one-dimensional optical latticeJan 31 2014Jun 04 2014We study a quasi-one-dimensional attractive Bose gas confined in an optical lattice with a superimposed harmonic potential by analyzing the effective one-dimensional Bose-Hubbard Hamiltonian of the system. In order to have a reliable description of the ... More
Safe Recursion on Notation into a Light Logic by LevelsMay 04 2010We embed Safe Recursion on Notation (SRN) into Light Affine Logic by Levels (LALL), derived from the logic L4. LALL is an intuitionistic deductive system, with a polynomial time cut elimination strategy. The embedding allows to represent every term t ... More
Discovery of magnetic A supergiants: the descendants of magnetic main sequence B starsJul 03 2017In the context of the high resolution, high signal-to-noise ratio, high sensitivity, spectropolarimetric survey BritePol, which complements observations by the BRITE constellation of nanosatellites for asteroseismology, we are looking for and measuring ... More
Overcoming the limitations of the energy-limited approximation for planet atmospheric escapeOct 16 2018Studies of planetary atmospheric composition, variability, and evolution require appropriate theoretical and numerical tools to estimate key atmospheric parameters, among which the mass-loss rate is often the most important. In evolutionary studies, it ... More
Refining the asteroseismic model for the young delta Scuti star HD 144277 using HARPS spectroscopyJun 04 2014HD 144277 was previously discovered by MOST space photometry to be a young and hot delta Scuti star showing regular groups of pulsation frequencies. The first asteroseismic models required lower than solar metallicity to fit the observed frequency range ... More
The transiting multi-planet system HD3167: a 5.7 MEarth Super-Earth and a 8.3 MEarth mini-NeptuneJun 08 2017HD3167 is a bright (V=8.9 mag) K0V star observed by the NASA's K2 space mission during its Campaign 8. It has been recently found to host two small transiting planets, namely, HD3167b, an ultra short period (0.96 d) super-Earth, and HD3167c, a mini-Neptune ... More
Low energy cosmic ray positron fraction explained by charge-sign dependent solar modulationNov 29 2012Jan 24 2013We compute cosmic ray (CR) nuclei, proton, antiproton, electron and positron spectra below 1 TeV at Earth by means of a detailed transport description in the galaxy and in the solar system. CR spectra below 10 GeV are strongly modified by charge-sign ... More
Statistical geometry of random weave statesJan 19 2001I describe the first steps in the construction of semiclassical states for non-perturbative canonical quantum gravity using ideas from classical, Riemannian statistical geometry and results from quantum geometry of spin network states. In particular, ... More
Neutrinos Oscillations with Long-Base-Line Beams (Past, Present and very near Future)Jun 24 2010We overview the status of the studies on neutrino oscillations with accelerators at the present running experiments. Past and present results enlighten the path towards the observation of massive neutrinos and the settling of their oscillations. The very ... More
Elastic Z^0 production at HERAOct 13 2014The production of $Z^{0}$ bosons in the reaction $eparrow eZ^{0}p^{(*)}$, where $p^{(*)}$ stands for a proton or a low-mass nucleon resonance, has been studied in $ep$ collisions at HERA using the ZEUS detector. The analysis is based on a data sample ... More
Local aspects of free open bosonic string field theoryDec 01 2008We show that strictly local observables with arbitrarily small support in space-time exist in covariant free open bosonic string field theory. The main ingredient of the proof is a modified version of the well known DDF operators, which we rigourously ... More
Star Operation in Quantum MechanicsJul 06 2000Jul 21 2000We outline the description of Quantum Mechanics with noncommuting coordinates within the framework of star operation. We discuss simple cases of integrability.
Extending a system in the calculus of structures with a self-dual quantifierDec 18 2012We recall that SBV, a proof system developed under the methodology of deep inference, extends multiplicative linear logic with the self-dual non-commutative logical operator Seq. We introduce SBVQ that extends SBV by adding the self-dual quantifier Sdq. ... More
Communication, and concurrency with logic-based restriction inside a calculus of structuresDec 19 2012It is well known that we can use structural proof theory to refine, or generalize, existing paradigmatic computational primitives, or to discover new ones. Under such a point of view we keep developing a programme whose goal is establishing a correspondence ... More
Natural Warm InflationJul 18 2011Sep 06 2011We derive the requirements that a generic axion-like field has to satisfy in order to play the role of the inflaton field in the warm inflation scenario. Compared to the parameter space in ordinary natural inflation models, we find that the parameter ... More
Conformal metrics on $\R^{2m}$ with constant Q-curvatureMay 06 2008We study the conformal metrics on $\R^{2m}$ with constant Q-curvature $Q$ having finite volume, particularly in the case $Q\leq 0$. We show that when $Q<0$ such metrics exist in $\R^{2m}$ if and only if $m>1$. Moreover we study their asymptotic behavior ... More
Quantization for the prescribed Q-curvature equation on open domainsMar 21 2010We discuss compactness, blow-up and quantization phenomena for the prescribed $Q$-curvature equation $(-\Delta)^m u_k=V_ke^{2mu_k}$ on open domains of $\R{2m}$. Under natural integral assumptions we show that when blow-up occurs, up to a subsequence $$\lim_{k\to ... More
Condensate formation with three-component ultracold fermionsMar 05 2011We investigate the formation of Bose-Einstein condensation and population imbalance in a three-component Fermi superfluid by increasing the U(3) invariant attractive interaction. We consider the system at zero temperature in three dimensions and also ... More
Generalized nonpolynomial Schrodinger equations for matter waves under anisotropic transverse confinementJul 07 2009Starting from the three-dimensional Gross-Pitaevskii equation we derive a 1D generalized nonpolynomial Schrodinger equation, which describes the dynamics of Bose-Einstein condensates under the action of a generic potential in the longitudinal axial direction ... More
Ideal Quantum Gases in D-dimensional Space and Power-law PotentialsAug 22 2000We investigate ideal quantum gases in D-dimensional space and confined in a generic external potential by using the semiclassical approximation. In particular, we derive density of states, density profiles and critical temperatures for Fermions and Bosons ... More
Chaotic Oscillations in Finite Quantum Systems: Trapped Bose-Einstein CondensatesJun 22 1999We discuss the recently achieved Bose-Einstein condensation for alkali-metal atoms in magnetic traps. The theoretically predicted low-energy collective oscillations of the condensate have been experimentally confirmed by laser imaging techniques. We show ... More
Quantum Chaos in a Yang-Mills-Higgs SystemJun 12 1997We study the energy fluctuations of a spatially homogeneous SU(2) Yang-Mills-Higgs system. In particular, we analyze the nearest-neighbour spacing distribution which shows a Wigner-Poisson transition by increasing the value of the Higgs field in the vacuum. ... More
Low-temperature thermodynamics of the unitary Fermi gas: superfluid fraction, first sound and second soundNov 22 2010We investigate the low-temperature thermodynamics of the unitary Fermi gas by introducing a model based on the zero-temperature spectra of both bosonic collective modes and fermonic single-particle excitations. We calculate the Helmholtz free energy and ... More
Condensate fraction in metallic superconductors and ultracold atomic vaporsMar 19 2010We investigate the condensate density and the condensate fraction of conduction electrons in weak-coupling superconductors by using the BCS theory and the concept of off-diagonal-long-range-order. We discuss the analytical formula of the zero-temperature ... More
Weak complementarity from discrete symmetriesOct 15 2009The neutrino oscillation data find a good approximation in the so-called tri-bimaximal pattern. Recently a paper appeared showing that also the bimaximal pattern, which is already ruled out by the measurements, could be a very good starting point in order ... More
Neutrino Masses and Mixings from Continuous SymmetriesNov 11 2014Flavour symmetries are fundamental tools in the search for an explanation to the flavour puzzle: fermion mass hierarchies, the neutrino mass ordering, the differences between the mixing matrices in the quark and lepton sector, can all find an explanation ... More
Geometry and topology of turbulence in active nematicsSep 04 2014Aug 03 2015The problem of low Reynolds number turbulence in active nematic fluids is theoretically addressed. Using numerical simulations I demonstrate that an incompressible turbulent flow, in two-dimensional active nematics, consists of an ensemble of vortices ... More
Softly Constrained FilmsApr 03 2013The shape of materials is often subject to a number of geometric constraints that limit the size of the system or fix the structure of its boundary. In soft and biological materials, however, these constraints are not always hard, but are due to other ... More
Superstrings in AdSApr 13 2011Feb 12 2012This is a comprehensive review of the worldsheet techniques for the quantization of type IIB superstring theory on the AdS_5 x S^5 background, using the pure spinor formalism. Particular emphasis is devoted to AdS/CFT applications, with several examples ... More
Fitness landscapes and evolutionMay 02 1995The concept of fitness is introduced, and a simple derivation of the Fundamental Theorem of Natural Selection (which states that the average fitness of a population increases if its variance is nonzero) is given. After a short discussion of the adaptative ... More
Firm size distribution in Italy and employment protectionDec 02 2014The number of Italian firms in function of the number of workers is well approximated by an inverse power law up to 15 workers but shows a clear downward deflection beyond this point, both when using old pre-1999 data and when using recent (2014) data. ... More
The dependence of cosmological parameters estimated from the microwave background on non-gaussianityJul 27 2001The estimation of cosmological parameters from cosmic microwave experiments has almost always been performed assuming gaussian data. In this paper the sensitivity of the parameter estimation to different assumptions on the probability distribution of ... More
Scaling solutions in general non-minimal coupling theoriesApr 09 1999A class of generalized non-minimal coupling theories is investigated, in search of scaling attractors able to provide an accelerated expansion at the present time. Solutions are found in the strong coupling regime and when the coupling function and the ... More
Non-Gaussian Chi-squared method with the multivariate Edgeworth expansionOct 13 1998I present here a generalization of the maximum likelihood method and the $\chi^2$ method to the cases in which the data are {\it not} assumed to be Gaussian distributed. The method, based on the multivariate Edgeworth expansion, can find several astrophysical ... More
Coupled QuintessenceAug 03 1999A new component of the cosmic medium, a light scalar field or ''quintessence '', has been proposed recently to explain cosmic acceleration with a dynamical cosmological constant. Such a field is expected to be coupled explicitely to ordinary matter, unless ... More
Inapproximability of Combinatorial Optimization ProblemsSep 24 2004We survey results on the hardness of approximating combinatorial optimization problems.
Existence of affine pavings for varieties of partial flags associated to nilpotent elementsMay 15 2013May 19 2014The flag variety of a complex reductive linear algebraic group G is by definition the quotient G/B by a Borel subgroup. It can be regarded as the set of Borel subalgebras of Lie(G). Given a nilpotent element e in Lie(G), one calls Springer fiber the subvariety ... More
Characterizations of BMO through commutators of bilinear singular integral operatorsOct 16 2014Dec 09 2014In this paper we characterize BMO in terms of the boundedness of commutators of various bilinear singular integral operators with pointwise multiplication. In particular, we study commutators of a wide class of bilinear operators of convolution type, ... More
Self-Dual Soliton Solution in a Generalized Jackiw-Pi ModelJul 31 2012Aug 30 2012We consider a generalization of Jackiw-Pi model by introducing a nonstandard kinetic term. We present a Bogomolnyi framework for this theory and as a particular case we show that the Bogomolnyi equations of Chern-Simons Higgs theory can be obtained. Finally, ... More
Inclusive searches for SUSY at CMSSep 12 2014Multiple searches for supersymmetry have been performed at the CMS experiment. Of these, inclusive searches aim to remain as sensitive as possible to the widest range of potential new physics scenarios. The results presented in this talk use the latest ... More
Constraining chameleon models with cosmologyMar 17 2014Jan 04 2015Chameleon fields may modify gravity on cluster scales while recovering general relativity locally. This article reviews signatures of chameleon modifications in the nonlinear cosmological structure, comparing different techniques to model them, summarising ... More
A note on vortices from Lorentz-violating modelsNov 18 2013Apr 12 2014We consider two self-dual abelian Higgs systems obtained from Lorentz breaking symmetry models by dimensional reduction. For the first model, we show that the self-dual equations are identical to those of Nielsen-Olesen vortices. Also, we show that our ... More
Spherical Schrödinger Hamiltonians: Spectral Analysis and Time DecayNov 15 2016In this survey, we review recent results concerning the canonical dispersive flow $e^{itH}$ led by a Schr\"odinger Hamiltonian $H$. We study, in particular, how the time decay of space $L^p$-norms depends on the frequency localization of the initial datum ... More
Stokes paradox in electronic Fermi liquidsDec 02 2016The Stokes paradox is the statement that in a viscous two dimensional fluid, the "linear response" problem of fluid flow around an obstacle is ill-posed. We present a simple consequence of this paradox in the hydrodynamic regime of a Fermi liquid of electrons ... More
Why do we need Hilbert spaces?Aug 23 2017These are the notes written for the talk given at the workshop Rethinking foundations of physics 2016. In section 2, a derivation of the the quantum formalism starting from propositional calculus (quantum logic) is reviewed, pointing out which are the ... More
Microlocalization of subanalytic sheavesFeb 15 2007Jun 24 2010In this paper we define specialization and microlocalization for subanalytic sheaves. Applying these functors to the sheaves of tempered and Whytney holomorphic functions we get a unifying description of tempered and formal microlocalization using the ... More
The L^p-continuity of the wave operators for the three dimensional Schroedinger operatorJan 04 2007May 14 2007This paper has been withdrawn, because of an error in the proof of the main Theorem
On the largest planar graphs with everywhere positive combinatorial curvatureAug 28 2017A planar PCC graph is a simple connected planar graph with everywhere positive combinatorial curvature which is not a prism or an antiprism and with all vertices of degree at least 3. We prove that every planar PCC graph has at most 208 vertices, thus ... More
Conformal Standard ModelJul 03 2011Apr 10 2014In recent papers we have constructed the conformal theory of metric-torsional gravitation, and in this paper we shall include the gauge fields to study the conformal U(1) X SU(2) Standard Model; we will show that the metric-torsional degrees of freedom ... More
Boundaries of analytic varietiesNov 05 2012We prove that every smooth CR manifold $M\subset\subset \C^n$, of hypersurface type, has a complex strip-manifold extension in $\C^n$. If $M$ is, in addition, pseudoconvex-oriented, it is the "exterior" boundary of the strip. In turn, the strip extends ... More
K3 surfaces with $\mathbb{Z}_2^2$ symplectic actionJul 31 2017Jul 27 2018Let $G$ be a finite abelian group which acts symplectically on a K3 surface. The N\'eron-Severi lattice of the projective K3 surfaces admitting $G$ symplectic action and with minimal Picard number is computed by Garbagnati and Sarti. We consider a $4$-dimensional ... More
A note on the Bruhat decomposition of semisimple Lie groupsJul 28 2008Let a split element of a connected semisimple Lie group act on one of its flag manifolds. We prove that each connected set of fixed points of this action is itself a flag manifold. With this we can obtain the generalized Bruhat decomposition of a semisimple ... More
The Navarro refinement of the McKay conjecture for finite groups of Lie type in defining characteristicMar 27 2017In this paper we verify Navarro's refinement of the McKay conjecture for quasi-simple groups of Lie type $G$ and the prime $p$, where $p$ is the defining characteristic of $G$. Navarro's refinement takes into account the action of specific Galois automorphisms ... More
Factorization of a class of composed polynomialsSep 05 2018In this paper, we provide the degree distribution of irreducible factors of the composed polynomial $f(L(x))$ over $\mathbb F_q$, where $f(x)\in \mathbb F_q[x]$ is irreducible and $L(x)\in \mathbb F_q[x]$ is a linearized polynomial. We further provide ... More
Proper stacksJun 19 2006Nov 14 2006We generalize the notion of proper stack introduced by Kashiwara and Schapira to the case of a general site, and we prove that a proper stack is a stack.
Eigenvectors distribution and quantum unique ergodicity for deformed Wigner matricesNov 19 2017Jul 13 2018We analyze the distribution of eigenvectors for mesoscopic, mean-field perturbations of diagonal matrices in the bulk of the spectrum. Our results apply to a generalized $N\times N$ Rosenzweig-Porter model. We prove that the eigenvectors entries are asymptotically ... More
On Morphic Actions and Integrability of LA-GroupoidsFeb 12 2009Lie theory for the integration of Lie algebroids to Lie groupoids, on the one hand, and of Poisson manifolds to symplectic groupoids, on the other, has undergone tremendous developements in the last decade, thanks to the work of Mackenzie-Xu, Moerdijk-Mrcun, ... More
Integrability and reduction of Poisson group actionsOct 30 2007Nov 01 2007In this paper we study Poisson actions of complete Poisson groups, without any connectivity assumption or requiring the existence of a momentum map. For any complete Poisson group $G$ with dual $G^\star$ we obtain a suitably connected integrating symplectic ... More
A Tutte polynomial for toric arrangementsNov 25 2009Nov 09 2010We introduce a multiplicity Tutte polynomial M(x,y), with applications to zonotopes and toric arrangements. We prove that M(x,y) satisfies a deletion-restriction recurrence and has positive coefficients. The characteristic polynomial and the Poincare' ... More
Investigation of Rule 73 as Case Study of Class 4 Long-Distance Cellular AutomataOct 11 2013Cellular automata (CA) have been utilized for decades as discrete models of many physical, mathematical, chemical, biological, and computing systems. The most widely known form of CA, the elementary cellular automaton (ECA), has been studied in particular ... More
A View of Neutrino Studies with the Next Generation FacilitiesNov 30 2015Apr 26 2016Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long--standing investigation of new physics beyond the Standard Model. The rather recent measurement of the third mixing angle $\theta_{13}$ in ... More
Search for Sterile Neutrinos at OPERA and other Long--Baseline ExperimentsOct 14 2015The OPERA experiment at the CNGS beam has observed muon to tau neutrino oscillations in the atmospheric sector. Based on this result new limits on the mixing parameters of a massive sterile neutrino may be set. Preliminary results of the analysis done ... More
The Freidlin-Gartner formula for general reaction termsMar 31 2015May 18 2016We devise a new geometric approach to study the propagation of disturbance - compactly supported data - in reaction diffusion equations. The method builds a bridge between the propagation of disturbance and of almost planar solutions. It applies to very ... More
Super Chern-Simons Quantum MechanicsMay 04 2004The Super Chern-Simons mechanics, and quantum mechanics of a particle, on the coset super-manifolds SU(2|1)/ U(2) and SU(2|1)/U(1)X U(1), is considered. Within a convenient quantization procedure the well known Chern-Simons mechanics on SU(2)/U(1) is ... More
The transformation laws of algebraic theta functionsSep 15 2016We give a comprehensive treatment of the transformation laws of theta functions from an algebro-geometric perspective, that is, in terms of moduli of abelian schemes. This is accomplished by introducing geometric notions of theta-descent structures, metaplectic ... More
The algebraic functional equation of Riemann's theta functionDec 14 2015Aug 23 2016We give an algebraic analog of the functional equation of Riemann's theta function. More precisely, we define a `theta multiplier' line bundle over the moduli stack of principally polarized abelian schemes with theta characteristic and prove that its ... More
Threshold resummation in SCET vs. direct QCD: a systematic comparisonMay 06 2014We perform a systematic comparison of soft-gluon resummation in SCET and in a standard "direct" QCD (dQCD) approach, both from an analytical and a phenomenological point of view. In particular, we concentrate on Higgs boson production in gluon-gluon fusion ... More
A discussion on the most general torsion-gravity with electrodynamics for Dirac spinor matter fieldsSep 06 2014Jul 21 2015We consider the most general torsional completion of gravitation together with electrodynamics for the Dirac spinorial material fields, and we show that consistency arguments constrain torsion to be completely antisymmetric and the dynamics to be parity-invariant ... More
Conformal Gravity with Electrodynamics for Fermion Fields and their Symmetry Breaking MechanismMay 24 2012Oct 15 2013In this paper we consider an axial torsion to build metric-compatible connections in conformal gravity, with gauge potentials; the geometric background is filled with Dirac spinors: scalar fields with suitable potentials are added eventually. The system ... More
A Discussion on Dirac Field Theory, No-Go Theorems and RenormalizabilityJun 23 2011Oct 14 2012We study Dirac field equations coupled to electrodynamics with metric and torsion fields: we discuss how special spinorial solutions are incompatible with torsion; eventually these results will be used to sketch a discussion on the problem of renormalizability ... More
Conformal Gravity with Dirac MatterJan 12 2011Apr 10 2014Recently, we have constructed the conformal gravity with metric and torsion, finding the gravitational field equations that give the conservation laws and trace condition; in the present paper we apply this theory to the case of the Dirac matter field: ... More
Metric-Torsional Conformal GravityJan 10 2011Apr 10 2014When in general geometric backgrounds the metric is accompanied by torsion, the metric conformal properties should correspondingly be followed by analogous torsional conformal properties; however a combined metric torsional conformal structure has never ... More