Results for "Fabio Scardigli"

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GUP parameter from quantum corrections to the Newtonian potentialNov 04 2016Jan 25 2017We propose a technique to compute the deformation parameter of the generalized uncertainty principle by using the leading quantum corrections to the Newtonian potential. We just assume General Relativity as theory of Gravitation, and the thermal nature ... More
Some considerations on Determinism and Free WillMay 12 2019This article has been written, in a slightly different version, as an introductory chapter for the book collecting the essays of theoretical physicist Gerard 't Hooft, philosopher Emanuele Severino, and theologian Piero Coda, and inspired by the talks ... More
Some Heuristic Semiclassical Derivations of the Planck Length, the Hawking Effect and the Unruh EffectJun 09 2002The formulae for Planck length, Hawking temperature and Unruh-Davies temperature are derived by using only laws of classical physics together with the Heisenberg principle. Besides, it is shown how the Hawking relation can be deduced from the Unruh relation ... More
Generalized Uncertainty Principle in Quantum Gravity from Micro-Black Hole Gedanken ExperimentApr 05 1999We review versions of the Generalized Uncertainty Principle (GUP) obtained in string theory and in gedanken experiments carried out in Quantum Gravity. We show how a GUP can be derived from a measure gedanken experiment involving micro-black holes at ... More
Glimpses on the micro black hole Planck phaseSep 10 2008Mass thresholds, lifetimes, entropy and heat capacity for micro black holes close to their late Schwarzschild phase are computed using two different generalized uncertainty principles, in the framework of models with extra spatial dimensions. Emissions ... More
A quantum-like description of the planetary systemsJul 11 2005Nov 25 2007The Titius-Bode law for planetary distances is reviewed. A model describing the basic features of this rule in the "quantum-like" language of a wave equation is proposed. Some considerations about the 't Hooft idea on the quantum behaviour of deterministic ... More
The deformation parameter of the generalized uncertainty principleApr 27 2019After a short introduction to the generalized uncertainty principle (GUP), we review some of the physical predictions of the GUP, and we focus in particular on the bounds that present experimental tests can put on the value of the deformation parameter ... More
Gravity coupling from micro-black holesJul 17 1999Jul 31 2000Recently much work has been done in lowering the Planck threshold of quantum gravitational effects (sub-millimeter dimension(s), Horava-Witten fifth dimension, strings or branes low energy effects, etc.). Working in the framework of 4-dim gravity, with ... More
Black Hole Entropy: a spacetime foam approachJun 11 1997The spacetime foam structure is reviewed briefly (topogical fluctuations and virtual black hole possibility; equation of state of the foam). A model of space foam at the surface of the event horizon is introduced. The model is applied to the calculus ... More
Analysis of a Shell System in General RelativityJun 03 2002This Thesis concerns a thin fluid shell embedded in its own gravitational field. The starting point is a work of Hajicek and Kijowski, where the hamiltonian formalism for shell(s) (with no symmetry) in Einstein gravity is developed. An open problem at ... More
Hawking temperature for various kinds of black holes from Heisenberg uncertainty principleJul 04 2006Hawking temperature is computed for a large class of black holes (with spherical, toroidal and hyperboloidal topologies) using only laws of classical physics plus the "classical" Heisenberg Uncertainty Principle. This principle is shown to be fully sufficient ... More
The emergence of Special and Doubly Special RelativityMay 19 2011Jun 28 2012Building on our previous work [Phys.Rev.D82,085016(2010)], we show in this paper how a Brownian motion on a short scale can originate a relativistic motion on scales that are larger than particle's Compton wavelength. This can be described in terms of ... More
Inferences from the dark sky: Olbers' paradox revisitedJul 28 2000Dec 24 2002The classical formulation of "Olbers' Paradox" consists in looking for an explanation of the fact that the sky at night is dark. We use the experimental datum of the nocturnal darkness in order to put constraints on a Newtonian cosmological model. We ... More
Spacetimes as topological spaces, and the need to take methods of general topology more seriouslyApr 15 2018Nov 15 2018Why is the manifold topology in a spacetime taken for granted? Why do we prefer to use Riemann open balls as basic-open sets, while there also exists a Lorentz metric? Which topology is a best candidate for a spacetime; a topology sufficient for the description ... More
Is the Equivalence Principle violated by Generalized Uncertainty Principles and Holography in a brane-world?Nov 23 2007It has been recently debated whether a class of generalized uncertainty principles that include gravitational sources of error are compatible with the holographic principle in models with extra spatial dimensions. We had in fact shown elsewhere that the ... More
Gravitational tests of the Generalized Uncertainty PrincipleJul 01 2014We compute the corrections to the Schwarzschild metric necessary to reproduce the Hawking temperature derived from a Generalized Uncertainty Principle (GUP), so that the GUP deformation parameter is directly linked to the deformation of the metric. Using ... More
Lorentz violation and generalized uncertainty principleSep 02 2017Investigations on possible violation of Lorentz invariance have been widely pursued in the last decades, both from theoretical and experimental sides. A comprehensive framework to formulate the problem is the standard model extension (SME) proposed by ... More
Reply to "Holographic principle in spacetimes with extra spatial dimensions" and "About quantum fluctuations and holographic principle in (4+n)-dimensional spacetime"Jun 23 2006We reply to the comments by P.Midodashvili about our previous paper [1]. We argue that, contrary to the conclusions in Refs. [2,3], the Generalized Uncertainty Principle proposed by Ng and van Dam in Ref. [4] is compatible with the Holographic Principle ... More
Special Relativity induced by Granular SpaceJan 17 2013Mar 25 2013We show that the special relativistic dynamics when combined with quantum mechanics and the concept of superstatistics can be interpreted as arising from two interlocked non-relativistic stochastic processes that operate at different energy scales. This ... More
GUP parameter from quantum corrections to the Newtonian potentialNov 04 2016We propose a technique to compute the deformation parameter of the generalized uncertainty principle by using the leading quantum corrections to the Newtonian potential. The calculation gives, to first order, an unambiguous numerical result. The physical ... More
Uncertainty Relation on World Crystal and its Applications to Micro Black HolesDec 11 2009Dec 19 2009We formulate generalized uncertainty relations in a crystal-like universe whose lattice spacing is of the order of Planck length -- "world crystal". In the particular case when energies lie near the border of the Brillouin zone, i.e., for Planckian energies, ... More
Inflationary cosmology from quantum Conformal GravityOct 29 2014May 10 2015We analyze the functional integral for quantum Conformal Gravity and show that with the help of a Hubbard-Stratonovich transformation, the action can be broken into a local quadratic-curvature theory coupled to a scalar field. A one-loop effective action ... More
Can quantum mechanics be an emergent phenomenon?Jan 26 2009Feb 11 2009We raise the issue whether conventional quantum mechanics, which is not a hidden variable theory in the usual Jauch-Piron's sense, might nevertheless be a hidden variable theory in the sense recently conjectured by G. 't Hooft in his pre-quantization ... More
Black Hole Remnants in the Early UniverseSep 04 2010Nov 06 2010We consider the production of primordial micro black holes (MBH) remnants in the early universe. These objects induce the universe to be in a matter-dominated era before the onset of inflation. Effects of such an epoch on the CMB power spectrum are discussed ... More
Point-like sources and the scale of quantum gravityApr 22 2009We review the General Relativistic model of a (quasi) point-like particle represented by a massive shell of neutral matter which has vanishing total energy in the small-volume limit. We then show that, by assuming a Generalised Uncertainty Principle, ... More
Quantum hoop conjecture: Black hole formation by particle collisionsNov 22 2013Mar 20 2014We address the issue of (quantum) black hole formation by particle collision in quantum physics. We start by constructing the horizon wave-function for quantum mechanical states representing two highly boosted non-interacting particles that collide in ... More
Modified Unruh effect from Generalized Uncertainty PrincipleApr 14 2018We consider a generalized uncertainty principle (GUP) corresponding to a deformation of the fundamental commutator obtained by adding a term quadratic in the momentum. From this GUP, we compute corrections to the Unruh effect and related Unruh temperature, ... More
Heuristic derivation of the Casimir effect from Generalized Uncertainty PrincipleFeb 06 2019After a short introduction to the generalized uncertainty principle (GUP), we discuss heuristic derivations of the Casimir effect, first from the usual Heisenberg uncertainty principle (HUP), and then from GUP. Results are compared with those obtained ... More
N-body model of magnetic flux tubes reconnecting in the solar atmosphereJan 26 2016The investigation of dynamics of the small scale magnetic field on the Sun photosphere is necessary to understand the physical processes occurring in the higher layers of solar atmosphere due to the magnetic coupling between the photosphere and the corona. ... More
Horizon wave-function for single localized particles: GUP and quantum black hole decayJun 22 2013Oct 20 2013A localised particle in Quantum Mechanics is described by a wave packet in position space, regardless of its energy. However, from the point of view of General Relativity, if the particle's energy density exceeds a certain threshold, it should be a black ... More
Generalized Uncertainty Principle, Extra-dimensions and HolographyJul 18 2003We consider Uncertainty Principles which take into account the role of gravity and the possible existence of extra spatial dimensions. Explicit expressions for such Generalized Uncertainty Principles in 4+n dimensions are given and their holographic properties ... More
Analytic structure of QCD propagators in Minkowski spaceMay 24 2016Analytical functions for the propagators of QCD, including a set of chiral quarks, are derived by a one-loop massive expansion in the Landau gauge, deep in the infrared. By analytic continuation, the spectral functions are studied in Minkowski space, ... More
Variational Quantum ElectrodynamicsAug 13 2013Jan 09 2014A variational method is discussed, based on the principle of minimal variance. The method seems to be suited for gauge interacting fermions, and the simple case of quantum electrodynamics is discussed in detail. The issue of renormalization is addressed, ... More
Higher order extensions of the Gaussian effective potentialAug 08 2013Sep 21 2013A variational method is discussed, extending the Gaussian effective potential to higher orders. The single variational parameter is replaced by trial unknown two-point functions, with infinite variational parameters to be optimized by the solution of ... More
The Principle of Stationary Variance in Quantum Field TheoryAug 19 2013The principle of stationary variance is advocated as a viable variational approach to quantum field theory. The method is based on the principle that the variance of energy should be at its minimum when the state of a quantum system reaches its best approximation ... More
Some Results about FramesJan 30 1997In this paper we discuss some topics related to the general theory of frames. In particular we focus our attention to the existence of different 'reconstruction formulas' for a given vector of a certain Hilbert space and to some refinement of the perturbative ... More
Multi-Resolution Analysis in Arbitrary Hilbert SpacesJan 30 1997We discuss the possibility of introducing a multi-resolution in a Hilbert space which is not necessarily a space of functions. We investigate which of the classical properties can be translated to this more general framework and the way in which this ... More
Study of a Class of Four Dimensional Nonsingular Cosmological BouncesJul 07 2003We study a novel class of nonsingular time-symmetric cosmological bounces. In this class of four dimensional models the bounce is induced by a perfect fluid with a negative energy density. Metric perturbations are solved in an analytic way all through ... More
The lithium problem, a phenomenologist's perspectiveJun 11 2012Jul 09 2012Thirty years after the first observation of the 7Li isotope in the atmosphere of metal-poor halo stars, the puzzle about its origin persists. Do current observations still support the existence of a "plateau": a single value of lithium abundance, constant ... More
The global quantum duality principleDec 22 1999The "quantum duality principle" states that the quantization of a Lie bialgebra --- via a quantum universal enveloping algebra (QUEA) --- provides also a quantization of the dual Lie bialgebra (through its associated formal Poisson group) --- via a quantum ... More
Geometrical Meaning of R-matrix Action for Quantum Groups at Roots of 1Apr 12 1996Nov 06 1996The present work splits in two parts: first, we perform a straightforward generalization of results from [Re], proving autoquasitriangularity of quantum groups U_q(g) and their unrestricted specializations at roots of 1, in particular the function algebra ... More
Quantization of Poisson groups -- IIApr 10 1996Nov 07 1997Let $ G^\tau $ be a connected simply connected semisimple algebraic group, endowed with generalized Sklyanin-Drinfeld structure of Poisson group; let $ H^\tau $ be its dual Poisson group. By means of Drinfeld's double construction and dualization via ... More
Abelian Vectors and Self-Dual Tensors in Six-Dimensional SupergravityOct 29 1999Nov 27 2000In this note we describe the most general coupling of {\it abelian} vector and tensor multiplets to six-dimensional $(1,0)$ supergravity. As was recently pointed out, it is of interest to consider more general Chern-Simons couplings to abelian vectors ... More
An improved model of alliances between political partiesFeb 29 2016We consider an operatorial model of alliances between three political parties which interact with their electors, with the undecided voters, and with the electors of the other parties. This extends what was done in a previous paper, where this last type ... More
Perturbative study of Yang-Mills theory in the infraredSep 19 2015Mar 31 2016Pure Yang-Mills SU(N) theory is studied in four dimensional space and Landau gauge by a double perturbative expansion based on a massive free-particle propagator. By dimensional regularization, all diverging mass terms cancel exactly in the double expansion, ... More
Intertwining operators for non self-adjoint Hamiltonians and bicoherent statesSep 24 2016This paper is devoted to the construction of what we will call {\em exactly solvable models}, i.e. of quantum mechanical systems described by an Hamiltonian $H$ whose eigenvalues and eigenvectors can be explicitly constructed out of some {\em minimal ... More
The ecology of asexual pairwise interactions: A generalized law of mass actionNov 01 2014A general procedure to formulate asexual (unstructured, deterministic) population dynamical models resulting from individual pairwise interactions is proposed. Individuals are characterized by a continuous strategy that represents all their behavioral, ... More
The gluon propagator in Feynman gauge by the method of stationary varianceAug 22 2014The low-energy limit of pure Yang-Mills SU(3) gauge theory is studied in Feynman gauge by the method of stationary variance, a genuine second-order variational method that is suited to deal with the minimal coupling of fermions in gauge theories. In terms ... More
The index of symmetry of a flag manifoldJan 16 2014We study the index of symmetry of a compact generalized flag manifold M=G/H endowed with an invariant Kaehler structure. When the group G is simple we show that the leaves of symmetry are irreducible Hermitian symmetric spaces and we estimate their dimension. ... More
Time to timestamp: opportunistic cooperative localization from reception time measurementsAug 03 2014We present a general framework for improving and extending GNSS-based positioning by leveraging opportunistic measurements from legacy terrestrial radio signals. The proposed approach requires only that participating nodes collect and share reception ... More
Fast and Vectorizable Alternatives to Binary SearchJun 29 2015Given an array X of N+1 strictly ordered floating point numbers and an array Z of M floating point numbers belonging to the interval [X[0],X[N]), a common problem in numerical methods algorithms is to find the indices of the largest numbers in the array ... More
A Harnack's inequality for mixed type evolution equationsAug 31 2015We define a homogeneous parabolic De Giorgi classes of order 2 which suits a mixed type class of evolution equations whose simplest example is $\mu (x) \frac{\partial u}{\partial t} - \Delta u = 0$ where $\mu$ can be positive, null and negative, so in ... More
Theory SummaryOct 11 2013Talk given at the XLVIII Rencontres de Moriond, Electroweak Interactions and Unified Theories, La Thuile, Italy, 2-9 March 2013, to appear in the Proceedings.
KTBoost: Combined Kernel and Tree BoostingFeb 11 2019In this article, we introduce a novel boosting algorithm called `KTBoost', which combines kernel boosting and tree boosting. In each boosting iteration, the algorithm adds either a regression tree or reproducing kernel Hilbert space (RKHS) regression ... More
A duality principle for non-convex optimization in $\mathbb{R}^n$Mar 14 2019This article develops a duality principle for a class of optimization problems in $\mathbb{R}^n$. The results are obtained based on standard tools of convex analysis and on a well known result of Toland for D.C. optimization. Global sufficient optimality ... More
Examples of non-trivial contact mapping classes for overtwisted contact manifolds in all dimensionsApr 24 2017May 19 2017The aim of the article is to construct (infinitely many) examples in all dimensions of contactomorphisms of closed overtwisted contact manifolds that are smoothly isotopic but not contact-isotopic to the identity. Hence, overtwisted contact structures ... More
On some properties of transitions operatorsMar 12 2001Mar 13 2001We study a general transition operator, generated by a random walk on a graph $X$; in particular we give necessary and sufficient condition on the matrix coefficient (1-step transition probablilities) to be a bounded operator from $l^\infty(X)$ into itself. ... More
Alpha decay in electron environments of increasing density: from the bare nucleus to compressed matterSep 30 2015The influence of the electron environment on the alpha decay is elucidated. Within the frame of a simple model based on the generalized Thomas-Fermi theory of the atom, it is shown that the increase of the electron density around the parent nucleus drives ... More
A primal dual variational formulation for a non-linear model of platesApr 03 2019This article develops a new primal dual formulation for the Kirchhoff-Love non-linear plate model. At first we establish a duality principle which includes sufficient conditions of global optimality through the dual formulation. At this point we highlight ... More
Outliers and patterns of outliers in contingency tables with Algebraic StatisticsFeb 04 2011Oct 05 2011In this paper we provide a definition of pattern of outliers in contingency tables within a model-based framework. In particular, we make use of log-linear models and exact goodness-of-fit tests to specify the notions of outlier and pattern of outliers. ... More
A note on compact Markov operatorsFeb 18 2004The analytic properties of the Markov operator associated to a random walk are common tools in the study of the behaviour and some probabilistic features related to the walk. In this paper we consider a class of Markov operators which generalizes the ... More
An inequality for correlated measurable functionsNov 27 2007Nov 30 2007A classical inequality, which is known for families of monotone functions, is generalized to a larger class of families of measurable functions. Moreover we characterize all the families of functions for which the equality holds. We apply this result ... More
Metallicities in the Outer Regions of Spiral GalaxiesDec 15 2016The analysis of the chemical composition of galaxies provides fundamental insights into their evolution. This holds true also in the case of the outer regions of spiral galaxies. This Chapter presents the observational data, accumulated in the past few ... More
A primal dual variational formulation and a multi-duality principle for a non-linear model of platesApr 03 2019Apr 18 2019This article develops a new primal dual formulation for the Kirchhoff-Love non-linear plate model. At first we establish a duality principle which includes sufficient conditions of global optimality through the dual formulation. At this point we highlight ... More
Homogeneous Lagrangian submanifolds of positive Euler characteristicNov 30 2008We fully classify all Lagrangian submanifolds of a complex Grassmannian which are an orbit of a compact group of isometries and have positive Euler characteristic.
Molecular anions in circumstellar envelopes, interstellar clouds and planetary atmospheres: quantum dynamics of formation and evolutionSep 13 2012For decades astronomers and astrophysicists believed that only positively charged ions were worthy of relevance in drawing the networks for possible chemical reactions in the interstellar medium, as well as in modeling the physical conditions in most ... More
Pfaffian representations of cubic surfacesMar 05 2012Feb 04 2014Let K be a field of characteristic zero. We describe an algorithm which requires a homogeneous polynomial F of degree three in K[x_0,x_1,x_2,x_3] and a zero A of F in P^3_K and ensures a linear pfaffian representation of V(F) with entries in K[x_0,x_1,x_2,x_3], ... More
Chevalley Supergroups of type D(2,1;a)Jun 02 2010Sep 03 2012I present a construction "a` la Chevalley" of affine supergroups associated with simple Lie superalgebras of (classical) type D(2,1;a), for any possible value of the parameter a - in particular, including non-integral values of a. This extends the similar ... More
Slicing surfaces and Fourier restriction conjectureApr 23 2008We deal with the restriction phenomenon for the Fourier transform. We prove that each of the restriction conjectures for the sphere, the paraboloid, the elliptic hyperboloid in $\mathbb{R}^n$ implies that for the cone in $\mathbb{R}^{n+1}$. We also prove ... More
Examples of contact mapping classes of infinite order in all dimensionsSep 20 2018In this paper we give examples of tight high dimensional contact manifolds admitting a contactomorphism whose powers are all smoothly isotopic but not contact-isotopic to the identity; this is a generalization of an observation in dimension 3 by Gompf, ... More
Persistent and susceptible bacteria with individual deathsOct 15 2012Apr 12 2013The aim of this paper is to study two models for a bacterial population subject to antibiotic treatments. It is known that some bacteria are sensitive to antibiotics. These bacteria are in a state called persistence and each bacterium can switch from ... More
Enabling Embodied Analogies in Intelligent Music SystemsNov 30 2017The present methodology is aimed at cross-modal machine learning and uses multidisciplinary tools and methods drawn from a broad range of areas and disciplines, including music, systematic musicology, dance, motion capture, human-computer interaction, ... More
Phase space analysis of semilinear parabolic equationsAug 08 2013We present a wave packet analysis of a class of possibly degenerate parabolic equations with variable coefficients. As a consequence, we prove local wellposedness of the corresponding Cauchy problem in spaces of low regularity, namely the modulation spaces, ... More
The global quantum duality principle: theory, examples, and applicationsMar 03 2003Oct 04 2012Let R be an integral domain, h non-zero in R such that R/hR is a field, and HA the category of torsionless (or flat) Hopf algebras over R. We call any H in HA "quantized function algebra" (=QFA), resp. "quantized (restricted) universal enveloping algebra" ... More
The quantum duality principleSep 14 1999Jun 02 2017The "quantum duality principle" states that the quantization of a Lie bialgebra - via a quantum universal enveloping algebra (QUEA) - provides also a quantization of the dual Lie bialgebra (through its associated formal Poisson group) - via a quantum ... More
A PBW basis for Lusztig's form of untwisted affine quantum groupsJun 17 1997May 15 2017Let $ \mathfrak{g} $ be an untwisted affine Kac-Moody algebra over the field $ K \, $, and let $ U_q(\mathfrak{g}) $ be the associated quantum enveloping algebra; let $ \mathfrak{U}_q(g) $ be the Lusztig's integer form of $ U_q(\mathfrak{g}) \, $, generated ... More
Quantization of Poisson GroupsNov 24 1995May 08 2017Let $ G^\tau $ be a connected simply connected semisimple algebraic group, endowed with generalized Sklyanin-Drinfel'd structure of Poisson group, let $ H^\tau $ be its dual Poisson group. By means of quantum double construction and dualization via formal ... More
The role of KLOE and KLOE-2 in the search for a secluded gauge sectorApr 24 2009The hypothesis of the existence of a secluded gauge sector with manifestations at low energies can be tested at low and medium energy e+e- colliders, such as DAFNE.Some signatures are very straightforward and can be relatively easily isolated against ... More
A stochastic version of the Eigen modelJan 23 2009Feb 02 2011We exhibit a stochastic discrete time model that has exactly the Eigen model as its deterministic continuous limit. Such model can be divided into two phases: reproduction followed by neutral selection. This result suggests that Eigen model describes ... More
WIMP Dark Matter and the First Stars: a critical overviewMar 22 2011If Dark Matter (DM) is composed by Weakly Interacting Massive Particles, its annihilation in the halos harboring the earliest star formation episode may strongly influence the first generation of stars (Population III). Whereas DM annihilation at early ... More
Self-annihilating dark matter and the CMB: reionizing the Universe and constraining cross sectionsDec 08 2009I summarize the recent advances in determining the effects of self-annihilating WIMP dark matter on the modification of the recombination history, at times earlier than the formation of astrophysical objects. Depending on mass and self-annihilation cross ... More
Dark Matter capture and annihilation on the First Stars: preliminary estimatesFeb 07 2008Apr 11 2008Assuming that Dark Matter is dominated by WIMPs, it accretes by gravitational attraction and scattering over baryonic material and annihilates inside celestial objects, giving rise to a "Dark Luminosity" which may potentially affect the evolution of stars. ... More
Effects of BBN on Population III starsDec 18 2003The presence (or absence) of CNO elements in the primordial gas determines different behaviours in population III stars formation and evolution: we therefore present an analysis of the main channels for the synthesis of these elements in BBN in order ... More
A sheafification theorem for doctrinesNov 06 2013Sep 04 2014We define the notion of sheaf in the context of doctrines. We prove the associate sheaf functor theorem. We show that grothendieck toposes and toposes obtained by the tripos to topos construction are instances of categories of sheaves for a suitable doctrine. ... More
Monge problem in metric measure spaces with Riemannian curvature-dimension conditionOct 15 2013We prove the existence of solutions for the Monge minimization problem, addressed in a metric measure space $(X,d,m)$ enjoying the Riemannian curvature-dimension condition $\RCD(K,N)$, with $N < \infty$. For the first marginal measure, we assume that ... More
Appearances of pseudo-bosons from Black-Scholes equationMar 09 2016It is a well known fact that the Black-Scholes equation admits an alternative representation as a Schr\"odinger equation expressed in terms of a non self-adjoint hamiltonian. We show how {\em pseudo-bosons}, linear or not, naturally arise in this context, ... More
A tripos based on compact Hausdorff spacesFeb 10 2016The category of compact Hausdorff spaces is the base of tripos. As such it can be freely completed to an elementary topos.
Stacks of ramified Galois coversJul 03 2013Given a finite, flat and finitely presented group scheme $G$ over some base $S$, we introduce the notion of ramified $G$-covers and study the moduli stack $G$-Cov they form. The thesis is divided in three parts. The first one concerns the case when $G$ ... More
Comparison of leading and next-to-leading logarithmic electroweak corrections to Higgs productionMar 13 2013Jul 29 2013Using soft-collinear effective theory, the leading-log radiative electroweak corrections are written in a closed and analytical form for the hadronic cross section of Higgs production through vector boson fusion, qq->qqH, one of the most promising channels ... More
Light Higgs bosons from a strongly interacting Higgs sectorMay 02 2001The mass and the decay width of a Higgs boson in the minimal standard model are evaluated by a variational method in the limit of strong self-coupling interaction. The non-perturbative technique provides an interpolation scheme between strong-coupling ... More
The Stanely-Féray-Śniady formula for the generalized characters of the Symmetric GroupMar 05 2011We show that the explicit formula of Stanley-F\'eray-\'Sniady for the characters of the symmetric group have a natural extension to the generalized characters. These are the spherical functions of the unbalanced Gel'fand pair $(S_n\times S_{n-1},\text{diag}S_{n-1})$. ... More
Optimal transport with branching distance costs and the obstacle problemMar 14 2011Sep 28 2012We address the Monge problem in metric spaces with a geodesic distance: (X, d) is a Polish space and dN is a geodesic Borel distance which makes (X,dN) a possibly branching geodesic space. We show that under some assumptions on the transference plan we ... More
Frequently Asked Questions on the Luminosity--Temperature relation in Groups and ClustersJan 29 2002Jan 31 2002Efforts to understand the deviation of the L--T relation from a simple scaling law valid for clusters and groups have triggered a number of interesting studies on the subject. Techniques and approaches differ widely but most works agree on the important ... More
The Abundance Scatter in M33 from HII Regions: Is There Any Evidence for Azimuthal Metallicity Variations?Feb 01 2011Optical spectra of 25 H II regions in the inner two kpc of the M33 disk have been obtained with the GMOS spectrograph at the Gemini North telescope. The oxygen abundance gradient measured from the detection of the [O III]4363 auroral line displays a scatter ... More
The massive star IMF at high metallicityAug 28 2004The question of the variation of the upper IMF at high metallicity is briefly reviewed. I show recent results suggesting a revision in the definition of `high metallicity' in extragalactic H II regions. I present preliminary results concerning constraints ... More
Blue Supergiants as a Tool for Extragalactic Distances - Empirical DiagnosticsJan 10 2003Blue supergiant stars can be exceptionally bright objects in the optical, making them prime targets for the determination of extragalactic distances. I describe how their photometric and spectroscopic properties can be calibrated to provide a measurement ... More
Low-energy structure of six-dimensional open-string vacuaMar 18 2002This dissertation reviews some properties of the low-energy effective actions for six dimensional open-string models. The first chapter is a pedagogical introduction about supergravity theories. In the second chapter closed strings are analyzed, with ... More
Variations of the Initial Mass Function in Semi-Analytical modelsMay 29 2014Deviations from a universal, MW-like, Stellar Initial Mass Function (IMF) have been reported for distant galaxies, although the physical reason behind the observed variations is still matter of ongoing debate. In this paper, we present an exploratory ... More
A variational formulation for relativistic mechanics based on Riemannian geometry and its application to the quantum mechanics contextDec 07 2018This article develops a variational formulation of relativistic nature applicable to the quantum mechanics context. The main results are obtained through basic concepts on Riemannian geometry. Standards definitions such as vector fields and connection ... More
Duality suitable for a class of non-convex optimization problemsJun 18 2019In this article we develop a duality principle suitable for a large class of problems in optimization. The main result is obtained through basic tools of convex analysis and duality theory. We establish a correct relation between the critical points of ... More