Results for "Luca Fossati"

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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
The Role of N2 as a Geo-Biosignature for the Detection and Characterization of Earth-like HabitatsApr 26 2019Since the Archean, N2 has been a major atmospheric constituent in Earth's atmosphere. Nitrogen is an essential element in the building blocks of life, therefore the geobiological nitrogen cycle is a fundamental factor in the long term evolution of both ... 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 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
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 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
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
EUV influences on exoplanet atmospheric stability and evolutionMar 13 2019The planetary effective surface temperature alone is insufficient to characterize exoplanet atmospheres and their stability or evolution. Considering the star-planet system as a whole is necessary, and a critical component of the system is the photoionizing ... 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
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
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
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
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
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
Understanding Exoplanet Atmospheres with UV Observations II: The Far UV and Atmospheric EscapeMar 26 2019Much of the focus of exoplanet atmosphere analysis in the coming decade will be at infrared wavelengths, with the planned launches of the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope (WFIRST). However, without being placed ... 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
Understanding Exoplanet Atmospheres with UV Observations I: NUV and Blue/OpticalMar 21 2019Much of the focus of exoplanet atmosphere analysis in the coming decade will be atinfrared wavelengths, with the planned launches of the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope (WFIRST). However, without being placed ... 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
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
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
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
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
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
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
Scientific Report on Low Energy Absorption Features Detected by BeppoSAX LECS in Bright Blazar TargetsApr 27 1998Apr 28 1998The apparency of low energy absorption features in Blazar LECS spectra has been reported during the early phase of the BeppoSAX mission (e.g. by Grandi et al. 1997 for 3C~273 SVP data; Giommi et al. 1997 for PKS 2155--304 SVP data), with data reduction ... More
The Riemann Problem for Hyperbolic Equations under a Nonconvex Flux with Two Inflection PointsFeb 24 2014This report addresses the solution of Riemann problems for hyperbolic equations when the nonlinear characteristic fields loose their genuine nonlinearity. In this context, exact solvers for nonconvex 1D Riemann problems are developed. First a scalar conservation ... More
From Lock Freedom to Progress Using Session TypesDec 10 2013Inspired by Kobayashi's type system for lock freedom, we define a behavioral type system for ensuring progress in a language of binary sessions. The key idea is to annotate actions in session types with priorities representing the urgency with which such ... More
Linear lambda Calculus with Explicit Substitutions as Proof-Search in Deep InferenceNov 16 2010May 26 2011SBV is a deep inference system that extends the set of logical operators of multiplicative linear logic with the non commutative operator Seq. We introduce the logical system SBVr which extends SBV by adding a self-dual atom-renaming operator to it. We ... More
A Discussion on the Heisenberg Uncertainty Principle from the Perspective of Special RelativityJan 09 2015Sep 16 2016In this note, we consider the implications of the Heisenberg uncertainty principle (HUP) when computing uncertainties that affect the main dynamical quantities, from the perspective of special relativity. Using the well-known formula for propagating statistical ... More
Conformal metrics on R^{2m} with constant Q-curvature and large volumeFeb 06 2012We study conformal metrics on R^{2m} with constant Q-curvature and finite volume. When m=3 we show that there exists V* such that for any V\in [V*,\infty) there is a conformal metric g on R^{6} with Q_g = Q-curvature of S^6, and vol(g)=V. This is in sharp ... More
Classification of solutions to the higher order Liouville's equation on R^{2m}Jan 17 2008We classify the solutions to the equation (- \Delta)^m u=(2m-1)!e^{2mu} on R^{2m} giving rise to a metric g=e^{2u}g_{R^{2m}} with finite total $Q$-curvature in terms of analytic and geometric properties. The analytic conditions involve the growth rate ... More
Discrete bright solitons in Bose-Einstein condensates and dimensional reduction in quantum field theoryNov 01 2014Nov 04 2014We first review the derivation of an effective one-dimensional (1D) discrete nonpolynomial Schr\"odinger equation from the continuous 3D Gross-Pitaevskii equation with transverse harmonic confinement and axial periodic potential. Then we study the bright ... More
Two-dimensional quasi-ideal Fermi gas with Rashba spin-orbit couplingNov 16 2013Nov 22 2013We investigate the zero-temperature properties of a quasi-ideal Fermi gas with Rashba spin-orbit coupling. We find that the spin-orbit term strongly affects the speeds of zero sound and first sound in the Fermi gas, due to the presence of a third-order ... More
Contact intensity and extended hydrodynamics in the BCS-BEC crossoverOct 12 2012In the first part of this chapter we analyze the contact intensity $C$, which has been introduced by Tan [Ann. Phys. 323, 2952 (2008)] and appears in several physical observables of the strongly correlated two-component Fermi gas. We calculate the contact ... More
Supersonic and subsonic shock waves in the unitary Fermi gasOct 03 2011We investigate shock waves in the unitary Fermi gas by using the zero-temperature equations of superfluid hydrodynamics. We obtain analytical solutions for the dynamics of a localized perturbation of the uniform gas. These supersonic bright and subsonic ... More
Triaxial Bright Solitons in Bose-Condensed Atomic VaporsJul 25 2004The properties of triaxial bright solitons (TBSs) made of attractive Bose-Einstein condensed atoms under transverse anisotropic harmonic confinement are investigated by using a variational approach. We show that these metastable TBSs change their shape ... More
Statistical Mechanics of a Trapped Bose-Einstein CondensateMar 26 1998Bose-Einstein condensation (BEC) in a gas has now been achieved. Alkali atoms ($^{87}Rb$, $^{23}Na$ and $^{7}Li$) have been cooled to the point of condensation (temperature of 100 nK) using laser cooling and trapping, followed by magnetic trapping and ... More
Review on 'Integrability of the S-Matrix vs Integrability of the Hamiltonian' by C. Jung and T.H. SeligmanDec 16 1997We review the paper 'Integrability of the S-Matrix vs Integrability of the Hamiltonian' by C. Jung and T.H. Seligman (Phys. Rep. 285, 77-141 (1997)). This paper deals with the connection between the integrability of the scattering matrix $S$ and the integrability ... More
Quantum Transition from Order to Chaos in the Nuclear Shell ModelJul 21 1997We discuss the role of quantum chaos in atomic nuclei. After reviewing the basic assumptions of the nuclear shell model, we analyze the spectral statistics of the energy levels obtained with realistic shell-model calculations in the fp shell. In particular, ... More
On the Torus Quantization of Two Anyons with Coulomb Interaction in a Magnetic FieldApr 10 1997We study two anyons with Coulomb interaction in a uniform magnetic field $B$. By using the torus quantization we obtain the modified Landau and Zeeman formulas for the two anyons. Then we derive a simple algebraic equation for the full spectral problem ... More
Multi Solitons of a Bose-Einstein Condensate in a Three-Dimensional RingNov 03 2005A Bose-Einstein Condensate (BEC) made of alkali-metal atoms at ultra-low temperatures is well described by the three-dimensional cubic nonlinear Schr\"odinger equation, the so-called Gross-Pitaevskii equation (GPE). Here we consider an attractive BEC ... More
Particles and Anti-Particles in a Relativistic Bose CondensateJul 22 2002We study the Bose-Einstein condensation (BEC) for a relativistic ideal gas of bosons. In the framework of canonical thermal field theory, we analyze the role of particles and anti-particles in the determination of BEC transition temperature. At the BEC ... More
Embedding right-angled Artin groups into graph braid groupsJun 13 2005Apr 02 2010We construct an embedding of any right-angled Artin group $G(\Delta)$ defined by a graph $\Delta$ into a graph braid group. The number of strands required for the braid group is equal to the chromatic number of $\Delta$. This construction yields an example ... More
Time-dependent Hypercritical Accretion onto Black HolesDec 10 1996Results are presented from a time-dependent, numerical investigation of super-Eddington spherical accretion onto black holes with different initial conditions. We have studied the stability of stationary solutions, the non-linear evolution of shocked ... More
Detections of millisecond pulsars with the Fermi Large Area TelescopeOct 25 2009The Fermi observatory was launched on June 11, 2008. It hosts the \emph{Large Area Telescope} (LAT), sensitive to $\gamma$-ray photons from 20 MeV to over 300 GeV. When the LAT began its activity, nine young and energetic pulsars were known in $\gamma$ ... More
Comment on "Bell's Theorem without Inequalities and without Alignments"Sep 20 2004In this Comment we show that Cabello's proof of Bell's theorem without inequalities [Phys. Rev. Lett. 91, 230403 (2003)] does not exhibit two of the three "remarkable properties" which the proof is claimed to possess. More precisely it is our purpose ... More
Photometric stellar parameters for asteroseismology and Galactic studiesSep 08 2014Asteroseismology has the capability of delivering stellar properties which would otherwise be inaccessible, such as radii, masses and thus ages of stars. When coupling this information with classical determinations of stellar parameters, such as metallicities, ... More
Covariant Anomalies and Functional DeterminantsDec 06 1993We analize the algebraic structure of consistent and covariant anomalies in gauge and gravitational theories: using a complex extension of the Lie algebra it is possible to describe them in a unified way. Then we study their representations by means of ... More
LFV in Models with A4 Flavour SymmetryNov 21 2008The approximated tri-bimaximal mixing observed in the neutrino oscillations is a particular feature of a class of models characterized by the spontaneously broken horizontal flavour symmetry A4. In this paper, it is presented an analysis on the predictions ... More
Theoretical Models for Neutrino MassesMay 25 2012The recent measurements of the neutrino reactor angle require a re-examination of flavour models based on discrete groups. Indeed, when these models deal with the Tri-Bimaximal, the Bimaximal and the Golden Ratio mixing patterns, some tensions arise in ... More
R-symmetry breaking, runaway directions and global symmetries in O'Raifeartaigh modelsMay 14 2007We discuss O'Raifeartaigh models with general R-charge assignments, introduced by Shih to break R-symmetry spontaneously. We argue that most of these models have runaway directions related to the R-symmetry. In addition, we study the simplest model with ... More
Theoretical approaches to the physics of spectral line polarizationMar 28 2011Due to the continuous developments in polarimetric instrumentation, which will become even more dramatic in the near future with the availability of new generation solar telescopes, we are now severely confronted with a variety of new detailed observations ... More
Galilean symmetry in generalized abelian Schrödinger-Higgs models with and without gauge field interactionMar 16 2015Oct 14 2015We consider a generalization of nonrelativistic Schr\"odinger-Higgs Lagrangian by introducing a nonstandard kinetic term. We show that this model is Galilean invariant, we construct the conserved charges associated to the symmetries and realize the algebra ... More
Singular soliton solution in the Chern-Simons-CP(1) modelApr 26 2011Sep 13 2011We show that the Chern-Simons-CP(1) model can support a singular soliton solution in which the magnetic field is a Dirac delta.
The Limiting Shape for Drifted Internal Diffusion Limited Aggregation is a True Heat BallFeb 09 2012Feb 17 2013We build the iDLA cluster using drifted random walks, and study the limiting shapes they exhibit, with the help of sandpile models. For constant drift, the normalised cluster converges to a canonical shape S, which can be termed a true heat ball, in that ... More
Lagrangian mechanics on Lie groups: a pedagogical approachNov 05 2011We describe a new method to formulate classical Lagrangian mechanics on a finite-dimensional Lie group. This new approach is much more pedagogical than many previous treatments of the subject, and it directly introduces students to generator matrices ... More
Lower complexity bounds for positive contactomorphismsFeb 19 2016Let $S^*Q$ be the spherization of a closed connected manifold of dimension at least two. Consider a contactomorphism $\varphi$ that can be reached by a contact isotopy that is everywhere positively transverse to the contact structure. In other words, ... More
Asymptotic Equation for Zeros of Hermite Polynomials from the Holstein-Primakoff RepresentationJun 01 2015Jun 05 2015The Holstein-Primakoff representation for spin systems is used to derive expressions with solutions that are conjectured to be the zeros of Hermite polynomials $H_n(x)$ as $n \rightarrow \infty$. This establishes a correspondence between the zeros of ... More
A solvable model of the evolutionary loopJun 19 1998A model for the evolution of a finite population in a rugged fitness landscape is introduced and solved. The population is trapped in an evolutionary loop, alternating periods of stasis to periods in which it performs adaptive walks. The dependence of ... More
On some extensions to GA package: hybrid optimisation, parallelisation and islands evolutionMay 06 2016Genetic algorithms are stochastic iterative algorithms in which a population of individuals evolve by emulating the process of biological evolution and natural selection. The R package GA provides a collection of general purpose functions for optimisation ... More
On the existence of Euler-Lagrange orbits satisfying the conormal boundary conditionsJul 21 2015Sep 07 2016Let $(M,g)$ be a closed Riemannian manifold, $L: TM\rightarrow \mathbb R$ be a Tonelli Lagrangian. Given two closed submanifolds $Q_0$ and $Q_1$ of $M$ and a real number $k$, we study the existence of Euler-Lagrange orbits with energy $k$ connecting $Q_0$ ... More
On Continuous Flavour Symmetries for NeutrinosMar 11 2015Flavour 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
Observational Constraints on Monomial Warm InflationMay 20 2016Jul 31 2016Warm inflation is, as of today, one of the best motivated mechanisms for explaining an early inflationary period. In this paper, we derive and analyze the current bounds on warm inflation with a monomial potential $U\propto \phi^p$, using the constraints ... More
"Large" conformal metrics of prescribed Q-curvature in the negative caseFeb 03 2016Given a compact and connected four dimensional smooth Riemannian manifold $(M,g_0)$ with $k_P := \int_M Q_{g_0} dV_{g_0} <0$ and a smooth non-constant function $f_0$ with $\max_{p\in M}f_0(p)=0$, all of whose maximum points are non-degenerate, we assume ... More
A simple assessment on the hierarchy problemApr 16 2015Apr 04 2016We consider the simplest extension of the standard model, where torsion couples to spinor as well as the scalar fields, and in which the cosmological constant problem is solved.
On the existence of orbits satisfying periodic or conormal boundary conditions for Euler-Lagrange flowsNov 24 2015Let $(M,g)$ be a closed Riemannian manifold and $L:TM\rightarrow \mathbb R$ be a Tonelli Lagrangian. In this thesis we study the existence of orbits of the Euler-Lagrange flow associated with $L$ satisfying suitable boundary conditions. We first look ... More
Notes on diagonals of the product and symmetric variety of a surfaceOct 16 2015Nov 09 2015Let $X$ be a smooth quasi-projective algebraic surface and let $\Delta_n$ the big diagonal in the product variety $X^n$. We study cohomological properties of the ideal sheaves $\mathcal{I}^k_{\Delta_n}$ and their invariants $(\mathcal{I}^k_{\Delta_n})^{\mathfrak{S}_n}$ ... More
A chiral lagrangian with broken scale: a Fortran code with the thermal contributions of the dilaton fieldSep 04 2009The Chiral Dilaton Model is a chiral lagrangian in which the breaking of scale invariance is regulated by the expectation value of a scalar field, called dilaton. Here we provide a Fortran code \cite{epaps,ind}, as a tool to make calculations within the ... More
Lehmer problem and Drinfeld modulesFeb 01 2013Jan 21 2015We propose a lower bound estimate in Dobrowolski's style of the canonical height on a certain family of Drinfeld modules of characteristic 0, including under some hypothesis on their degree and their base field, the complex multiplication case, extending ... More
Phantom energy mediates a long-range repulsive forceSep 22 2004Oct 14 2004Scalar field models with non-standard kinetic terms have been proposed in the context of k-inflation, of Born-Infeld lagrangians, of phantom energy and, more in general, of low-energy string theory. In general, scalar fields are expected to couple to ... More
Schröder partitions, Schröder tableaux and weak poset patternsJun 21 2016We introduce the notions of Schr\"oder shape and of Schr\"oder tableau, which provide some kind of analogs of the classical notions of Young shape and Young tableau. We investigate some properties of the partial order given by containment of Schr\"oder ... More
Torsion Gravity for Dirac ParticlesNov 25 2016We elucidate the role of torsion in gravity by showing how Dirac matter fields have distributions that are stable and localized and as such they can be seen as particles.
The KSBA compactification of the moduli space of $D_{1,6}$-polarized Enriques surfacesAug 08 2016Oct 11 2016We describe the moduli compactification by stable pairs of a $4$-dimensional family of Enriques surfaces, which arise as the $\mathbb{Z}_2^2$-covers of the blow up of $\mathbb{P}^2$ at three general points branched along a configuration of three pairs ... More
Quasilinear parabolic stochastic evolution equations via maximal $ L^{p} $-regularityNov 28 2016We study the Cauchy problem for an abstract quasilinear stochastic parabolic evolution equation on a Banach space driven by a cylindrical Brownian motion. We prove existence and uniqueness of a local strong solution up to a maximal stopping time, that ... More
Dirac-Jacobi BundlesFeb 18 2015Feb 10 2016We show that a suitable notion of Dirac-Jacobi structure on a generic line bundle $L$ is provided by Dirac structures in the omni-Lie algebroid of $L$. Dirac-Jacobi structures on line bundles generalize Wade's $\mathcal E^1 (M)$-Dirac structures and unify ... More
Search for Sterile Neutrinos at Long and Short BaselinesApr 22 2016Neutrino physics is currently suffering from lack of knowledge from at least four major ingredients. One of them is the presence or not of new sterile neutrino states at the mass scale of around 1 eV. Settling this point should be the highest priority ... More
Run-and-tumble particles, telegrapher's equation and absorption problems with partially reflecting boundariesJan 19 2016Absorption problems of run-and-tumble particles, described by the telegrapher's equation, are analyzed in one space dimension considering partially reflecting boundaries. Exact expressions for the probability distribution function in the Laplace domain ... More
Looking for ovoids of the Hermitian surface: a computational approachOct 09 2012In this note we present a computational approach to the construction of ovoids of the Hermitian surface and show some related experimental results.
Zero Energy of Plane-Waves for ELKOsAug 02 2010Feb 23 2011We consider the ELKO field in interaction through contorsion with its own spin density, and we investigate the form of the consequent autointeractions; to do so we take into account the high-density limit and find plane wave solutions: such plane waves ... More
Torsionally-gravitating charged matter fields and quantaMar 17 2015Jan 26 2016In the present article we shall consider the torsional completion of a gravitational background that is filled with electrodynamically interacting material fields, taken to be of fermionic type, eventually deriving properties like the impossibility of ... More
Polar solutions with tensorial connection of the spinor equationFeb 28 2019Mar 08 2019Dirac field equations are studied for spinor fields without any external interaction and when they are considered on a background having a tensorial connection with a specific non-vanishing structure some solution can be found in polar form displaying ... More
Termination of canonical context-sensitive rewriting and productivity of rewrite systemsDec 22 2015Termination of programs, i.e., the absence of infinite computations, ensures the existence of normal forms for all initial expressions, thus providing an essential ingredient for the definition of a normalization semantics for functional programs. In ... More
Invitation to higher local fields, Part I, section 18: On ramification theory of monogenic extensionsDec 18 2000Ramification theory of monogenic extensions of complete discrete valuation fields is presented. Relations to Kato's conductor are discussed.
Symmetrization and anti-symmetrization in parabolic equationsApr 13 2016Apr 28 2016We derive some symmetrization and anti-symmetrization properties of parabolic equations. First, we deduce from a result by Jones a quantitative estimate of how far the level sets of solutions are from being spherical. Next, using this property, we derive ... More
A Reformulation of the Riemann Hypothesis in Terms of Continuity of the Limit Function of a Certain Ratio of Partial Sums of a Series for the Dirichlet Eta FunctionJul 14 2009Oct 26 2009For any $s \in \mathbb{C}$ with $\Re(s)>0$, denote by $S_n(s)$ the $n^{th}$ partial sum of the alternating Dirichlet series $1-2^{-s}+3^{-s}-... $ . We first show that $S_n(s)\neq 0$ for all $n$ greater than some index $N(s)$ . Denoting by $D={s \in \mathbb{C}: ... More
The product of the eigenvalues of a symmetric tensorFeb 27 2018Mar 06 2018We study E-eigenvalues of a symmetric tensor $f$ of degree $d$ on a finite-dimensional Euclidean vector space $V$, and their relation with the E-characteristic polynomial of $f$. We show that the leading coefficient of the E-characteristic polynomial ... More
Some combinatorics related to central binomial coefficients: Grand-Dyck paths, coloured noncrossing partitions and signed pattern avoiding permutationsJun 05 2008We give some interpretations to certain integer sequences in terms of parameters on Grand-Dyck paths and coloured noncrossing partitions, and we find some new bijections relating Grand-Dyck paths and signed pattern avoiding permutations. Next we transfer ... More
Groupes linéaires finis permutant deux fois transitivement un ensemble de droitesOct 09 2009Dec 13 2009Let n >1 be an integer, and G a doubly transitive subgroup of the symmetric group on X={1,...,n}. In this paper we find all linear group representations rho of G on an euclidean vector space V which contains a set of equiangular vector lines GG={< v_1>,...,} ... More
On the stochastic Cahn-Hilliard equation with a singular double-well potentialOct 05 2017Jan 31 2018We prove well-posedness and regularity for the stochastic pure Cahn-Hilliard equation under homogeneous Neumann boundary conditions, with both additive and multiplicative Wiener noise. In contrast with great part of the literature, the double-well potential ... More
Well-posedness for a class of doubly nonlinear stochastic PDEs of divergence typeNov 21 2016We prove well-posedness for doubly nonlinear parabolic stochastic partial differential equations of the form $dX_t-\text{div}\,\gamma(\nabla X_t)\,dt+\beta(X_t)\,dt\ni B(t,X_t)\,dW_t$, where $\gamma$ and $\beta$ are the two nonlinearities, assumed to ... 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