Results for "Mathieu Boudaud"

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Voyager 1 $e^\pm$ Further Constrain Primordial Black Holes as Dark MatterJul 09 2018Jan 14 2019Primordial Black Holes (PBHs) with a mass $M \lesssim {10^{17}}$g are expected to inject sub-GeV electrons and positrons in the Galaxy via Hawking radiation. These cosmic rays are shielded by the solar magnetic field for Earth-bound detectors, but not ... More
A fussy revisitation of antiprotons as a tool for Dark Matter searchesOct 26 2015Oct 27 2015Antiprotons are regarded as a powerful probe for Dark Matter (DM) indirect detection and indeed current data from \PAMELA\ have been shown to lead to stringent constraints. However, in order to exploit their constraining/discovery power properly, great ... More
A new look at the cosmic ray positron fractionOct 26 2015The positron fraction in cosmic rays was found to be steadily increasing in function of energy, above $\sim$10 GeV. This behaviour contradicts standard astrophysical mechanisms, in which positrons are secondary particles, produced in the interactions ... More
Robust cosmic-ray constraints on $p$-wave annihilating MeV dark matterOct 03 2018Apr 01 2019We recently proposed a method to constrain $s$-wave annihilating MeV dark matter from a combination of the Voyager 1 and the AMS-02 data on cosmic-ray electrons and positrons. Voyager 1 actually provides an unprecedented probe of dark matter annihilation ... More
AMS-02 antiprotons, at last! Secondary astrophysical component and immediate implications for Dark MatterApr 16 2015Sep 09 2015Using the updated proton and helium fluxes just released by the AMS-02 experiment we reevaluate the secondary astrophysical antiproton to proton ratio and its uncertainties, and compare it with the ratio preliminarly reported by AMS-02. We find no unambiguous ... More
Indications for a high-rigidity break in the cosmic-ray diffusion coefficientJun 29 2017Jan 10 2018Using cosmic-ray boron to carbon ratio (B/C) data recently released by the AMS-02 experiment, we find tantalizing indications ({\it decisive evidence}, in Bayesian terms) in favor of a diffusive origin for the broken power-law spectra found in protons ... More
Novel cosmic-ray electron and positron constraints on MeV dark matter particlesDec 22 2016Jun 27 2017MeV dark matter (DM) particles annihilating or decaying to electron-positron pairs cannot, in principle, be observed via local cosmic-ray (CR) measurements because of the shielding solar magnetic field. In this letter, we take advantage of spacecraft ... More
A fussy revisitation of antiprotons as a tool for Dark Matter searchesDec 18 2014Mar 16 2015Antiprotons are regarded as a powerful probe for Dark Matter (DM) indirect detection and indeed current data from PAMELA have been shown to lead to stringent constraints. However, in order to exploit their constraining/discovery power properly and especially ... More
Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretationApr 18 2019Apr 25 2019This article aims at establishing new benchmark scenarios for Galactic cosmic-ray propagation in the GV-TV rigidity range, based on fits to the AMS-02 B/C data with the USINE v3.5 propagation code. We employ a new fitting procedure, cautiously taking ... More
Robust estimation on a parametric model via testingAug 13 2013Mar 30 2016We are interested in the problem of robust parametric estimation of a density from $n$ i.i.d. observations. By using a practice-oriented procedure based on robust tests, we build an estimator for which we establish non-asymptotic risk bounds with respect ... More
W[1]-hardness of some domination-like problems parameterized by tree-widthApr 15 2010Apr 03 2014The concept of generalized domination unifies well-known variants of domination-like and independence problems, such as Dominating Set, Independent Set, Perfect Code, etc. A generalized domination (also called $[\sigma,\rho]$-Dominating Set}) problem ... More
Toric varieties and spherical embeddings over an arbitrary fieldDec 03 2009Apr 14 2011We are interested in two classes of varieties with group action, namely toric varieties and spherical embeddings. They are classified by combinatorial objects, called fans in the toric setting, and colored fans in the spherical setting. We characterize ... More
Paths and partitions: combinatorial descriptions of the parafermionic statesMar 20 2009Jun 12 2009The Z_k parafermionic conformal field theories, despite the relative complexity of their modes algebra, offer the simplest context for the study of the bases of states and their different combinatorial representations. Three bases are known. The classic ... More
Open problems for the superKdV equationsMay 03 2000After a review of the basic results concerning the $N=1,2$ supersymmetric extensions of the Korteweg-de Vries equation, with a pedagogical presentation of the superspace techniques, we discuss some basic open problems mainly in relation with the N=2 extensions. ... More
Scaling approach to existence of long cycles in Casimir boxesOct 22 2008Apr 27 2009We analyse the concept of generalized Bose-Einstein condensation (g-BEC), known since 1982 for the perfect Bose gas (PBG) in the Casimir (or anisotropic) boxes. Our aim is to establish a relation between this phenomenon and two concepts: the concept of ... More
On the flow-level stability of data networks without congestion control: the case of linear networks and upstream treesJun 11 2010Sep 07 2011In this paper, flow models of networks without congestion control are considered. Users generate data transfers according to some Poisson processes and transmit corresponding packet at a fixed rate equal to their access rate until the entire document ... More
Quantum extremal loop weight modules and monomial crystalsJul 13 2012May 01 2013In this paper we construct a new family of representations for the quantum toroidal algebras of type $A_n$, which are $\ell$-extremal in the sense of Hernandez [24]. We construct extremal loop weight modules associated to level 0 fundamental weights $\varpi_\ell$ ... More
Structural, vibrational and thermal properties of densified silicates : insights from Molecular DynamicsMar 27 2012Apr 03 2012Structural, vibrational and thermal properties of densified sodium silicate (NS2) are investigated with classical molecular dynamics simulations of the glass and the liquid state. A systematic investigation of the glass structure with respect to density ... More
Notes on linearly H-closed spaces and od-selection principlesSep 03 2016A space is called linearly H-closed iff any chain cover possesses a dense member. This property lies strictly between feeble compactness and H-closedness. While regular H-closed spaces are compact, there are linearly H-closed spaces which are even collectionwise ... More
Kleinberg's Grid ReloadedDec 17 2016One of the key features of small-worlds is the ability to route messages with few hops only using local knowledge of the topology. In 2000, Kleinberg proposed a model based on an augmented grid that asymptotically exhibits such property. In this paper, ... More
Heterogeneity in Distributed Live Streaming: Blessing or Curse?Sep 09 2009Distributed live streaming has brought a lot of interest in the past few years. In the homogeneous case (all nodes having the same capacity), many algorithms have been proposed, which have been proven almost optimal or optimal. On the other hand, the ... More
Non-Global Logarithms in Filtered Jet AlgorithmsFeb 24 2010May 10 2010We analytically and numerically study the effect of perturbative gluons emission on the "Filtering analysis", which is part of a subjet analysis procedure proposed two years ago to possibly identify a low-mass Higgs boson decaying into b\bar{b} at the ... More
Light Higgs searches at the LHC using jet substructureMay 13 2009Jun 26 2009It is widely believed that searching for a light Higgs boson (with a mass around 120 GeV) in the WH and ZH channels, where H decays into $b\bar{b}$, will be very challenging at the LHC. These proceedings describe how this channel can be recovered as a ... More
Remarks on the space of volume preserving embeddingsApr 14 2012Let (N,g) be a Riemannian manifold. For a compact, connected and oriented submanifold M of N. we define the space of volume preserving embeddings Emb_{\mu}(M,N) as the set of smooth embeddings f:M \rightarrow N such that f*\mu^{f}=\mu, where \mu^{f} (resp. ... More
Information geometry and the hydrodynamical formulation of quantum mechanicsApr 03 2012Let (M,g) be a compact, connected and oriented Riemannian manifold. We denote D the space of smooth probability density functions on M. In this paper, we show that the Frechet manifold D is equipped with a Riemannian metric g^{D} and an affine connection ... More
The group of unimodular automorphisms of a principal bundle and the Euler-Yang-Mills equationsApr 24 2012Given a principal bundle G \rightarrow P \rightarrow B (each being compact, connected and oriented) and a G-invariant metric h^{P} on P which induces a volume form \mu^{P}, we consider the group of all unimodular automorphisms SAut(P,\mu^{P}):={\varphi\in ... More
Bifurcation vers l'etat d'Abrikosov et diagramme des phasesDec 15 1999Sep 27 2000Nous \'etudions dans cette th\`ese la fonctionnelle de Ginzburg-Landau dans $\R^3$ sur des couples de fonctions $(\phi, \overrightarrow{A})$ qui v\'erifient des conditions de p\'eriodicit\'e de jauge en $x_3$ et selon un r\'eseau discret de $(x_1,x_2)$. ... More
Model selection for Poisson processes with covariatesDec 23 2011Jun 13 2013We observe $n$ inhomogeneous Poisson processes with covariates and aim at estimating their intensities. We assume that the intensity of each Poisson process is of the form $s (\cdot, x)$ where $x$ is the covariate and where $s$ is an unknown function. ... More
The automorphism group of accessible groupsSep 30 2008Feb 08 2010In this article, we study the outer automorphism group of a group G decomposed as a finite graph of group with finite edge groups and finitely generated vertex groups with at most one end. We show that Out(G) is essentially obtained by taking extensions ... More
Splitting trees with neutral mutations at birthMay 14 2013May 17 2014We consider a population model where individuals behave independently from each other and whose genealogy is described by a chronological tree called splitting tree. The individuals have i.i.d. (non-exponential) lifetime durations and give birth at constant ... More
Lévy processes conditioned on having a large height processJun 11 2011Mar 20 2012In the present work, we consider spectrally positive L\'evy processes $(X_t,t\geq0)$ not drifting to $+\infty$ and we are interested in conditioning these processes to reach arbitrarily large heights (in the sense of the height process associated with ... More
Limit theorems for supercritical age-dependent branching processes with neutral immigrationJul 30 2010Dec 01 2010We consider a branching process with Poissonian immigration where individuals have inheritable types. At rate theta, new individuals singly enter the total population and start a new population which evolves like a supercritical, homogeneous, binary Crump-Mode-Jagers ... More
Semi-classical limit of the Levy-Lieb functional in Density Functional TheoryJun 07 2017Mar 07 2018In a recent work, Bindini and De Pascale have introduced a regularization of $N$-particle symmetric probabilities which preserves their one-particle marginals. In this short note, we extend their construction to mixed quantum fermionic states. This enables ... More
Extremal loop weight modules and tensor products for quantum toroidal algebrasMay 15 2013Jan 23 2015We define integrable representations of quantum toroidal algebras of type A by tensor product, using the Drinfeld "coproduct". This allow us to recover the vector representations recently introduced by Feigin-Jimbo-Miwa-Mukhin [6] and constructed by the ... More
The dimension of ergodic random sequencesJul 06 2011Jul 21 2011Let \mu be a computable ergodic shift-invariant measure over the Cantor space. Providing a constructive proof of Shannon-McMillan-Breiman theorem, V'yugin proved that if a sequence x is Martin-L\"of random w.r.t. \mu then the strong effective dimension ... More
Grothendieck topologies from unique factorisation systemsFeb 06 2009Oct 22 2009This work presents a way to associate a Grothendieck site structure to a category endowed with a unique factorisation system of its arrows. In particular this recovers the Zariski and Etale topologies and others related to Voevodsky's cd-structures. As ... More
Comment on `Solutions to quasi-relativistic multi-configurative Hartree-Fock equations in quantum chemistry', by C. Argaez & M. MelgaardNov 18 2011In a recent paper published in Nonlinear Analysis: Theory, Methods & Applications, C. Argaez and M. Melgaard studied excited states for pseudo-relativistic multi-configuration methods. Their paper follows a previous work of mine in the non-relativistic ... More
Renormalization of Dirac's Polarized VacuumOct 01 2010We review recent results on a mean-field model for relativistic electrons in atoms and molecules, which allows to describe at the same time the self-consistent behavior of the polarized Dirac sea. We quickly derive this model from Quantum Electrodynamics ... More
Ideomotor feedback control in a recurrent neural networkFeb 14 2014Jan 18 2015The architecture of a neural network controlling an unknown environment is presented. It is based on a randomly connected recurrent neural network from which both perception and action are simultaneously read and fed back. There are two concurrent learning ... More
Notes on the od-Lindelöf propertyJun 04 2012Mar 22 2015A space is od-compact (resp. od-Lindel\"of) provided any cover by open dense sets has a finite (resp. countable) subcover. We first show with simple examples that these properties behave quite poorly under finite or countable unions. We then investigate ... More
On Using Seeders for P2P Live StreamingApr 26 2011Seeders (peers that do not request anything but contribute to the system) are a powerful concept in peer-to-peer (P2P). They allow to leverage the capacities of a P2P system. While seeding is a natural idea for filesharing or video-on-demand applications, ... More
La Grassmannienne non-linéaire comme variété fréchétique homogèneApr 28 2012Let (M,g) be a compact Riemannian manifold of dimension n. For k \in {0,...,n}, we denote Gr_{k}(M) the set of compact, connected and oriented submanifolds of M of dimension k. This set is called the non-linear Grassmannian. In this article, we endow ... More
Pixel detector R&D for the Compact Linear ColliderFeb 23 2019Apr 15 2019The physics aims at the proposed future CLIC high-energy linear $e^+ e^-$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness ... More
Estimation of the transition density of a Markov chainOct 18 2012We present two data-driven procedures to estimate the transition density of an homogeneous Markov chain. The first yields to a piecewise constant estimator on a suitable random partition. By using an Hellinger-type loss, we establish non-asymptotic risk ... More
Exponential families, Kahler geometry and quantum mechanicsMar 09 2012Exponential families are a particular class of statistical manifolds which are particularly important in statistical inference, and which appear very frequently in statistics. For example, the set of normal distributions, with mean {\mu} and deviation ... More
Remarks on the statistical origin of the geometrical formulation of quantum mechanicsFeb 06 2012A quantum system can be entirely described by the K\"ahler structure of the projective space P(H) associated to the Hilbert space H of possible states; this is the so-called geometrical formulation of quantum mechanics. In this paper, we give an explicit ... More
A new construction of p-adic Rankin convolutions in the case of positive slopeMar 02 2009May 19 2009Given two newforms $f$ and $g$ of respective weights $k$ and $l$ with $k<l$, Hida constructed a $p$-adic $L$-function interpolating the values of the Rankin convolution of $f$ and $g$ in the critical strip $l \leq s \leq k$. However, this construction ... More
Exact computations in topological abelian Chern-Simons and BF theoriesMay 28 2017Jun 20 2017We introduce Deligne cohomology that classifies U(1) fibre bundles over 3-manifolds endowed with connections. We show how the structure of Deligne cohomology classes provides a way to perform exact (non-perturbative) computations in U(1) Chern-Simons ... More
How to define co-occurrence in different domains of study?Apr 16 2019This position paper presents a comparative study of co-occurrences. Some similarities and differences in the definition exist depending on the research domain (e.g. linguistics, NLP, computer science). This paper discusses these points, and deals with ... More
Fitting B/C cosmic-ray data in the AMS-02 era: a cookbookApr 17 2019AMS-02 on the ISS has been releasing data of unprecedented accuracy. This poses new challenges for their interpretation. We refine the methodology to get a statistically sound determination of the cosmic-ray propagation parameters. We inspect the numerical ... More
The quantum SKdV$_{1,4}$ equation at $c=3$Oct 28 1996At $c=3$, two of the three integrable quantum $N=2$ supersymmetric Korteweg-de Vries equations become identical (SKdV$_1$ and SKdV$_4$). Quite remarkably, all their conservation laws can be written in closed form, which provides thus a simple constructive ... More
Pixel detector R&D for the Compact Linear ColliderFeb 23 2019Apr 09 2019The physics aims at the proposed future CLIC high-energy linear $e^+ e^-$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness ... More
Probing sub-eV particles with polarized Helium 3Oct 01 2014Proceeding of the "Journ\'{e}es de Rencontre Jeunes Chercheurs" 2013. Measuring the depolarization rate of a $^3$He hyperpolarized gas is a sensitive method to probe hypothetical short-range spin-dependent forces. A dedicated experiment is being set up ... More
Model independent analysis of heavy vector-like top partnersMay 11 2014Searches for new fermionic states heavier than the top quark are being pursued by the CMS & ATLAS collaborations, pushing the mass bounds towards the TeV scale. Although a chiral fourth generation of quarks is now excluded by the LHC results, models going ... More
Special reductive groups over an arbitrary fieldMar 18 2014A linear algebraic group G defined over a field k is called special if every G-torsor over every field extension of k is trivial. In 1958 Grothendieck classified special groups in the case where the base field is algebraically closed. In this paper we ... More
Gaussian distributions, Jacobi group and Siegel-Jacobi spaceSep 28 2014Let $\mathcal{N}$ be the space of Gaussian distribution functions over $\mathbb{R}$, regarded as a 2-dimensional statistical manifold parameterized by the mean $\mu$ and the deviation $\sigma$. In this paper we show that the tangent bundle of $\mathcal{N}$, ... More
Changement de base pour les foncteurs TorMar 14 2003We give in this paper an isomorphism theorem between derived functors over categories of modules.There is a nice class of categories that gives examples in which this theorem applies for a special construction. This leads us to a new interpretation of ... More
Commability of groups quasi-isometric to treesDec 01 2013Dec 17 2014Commability is the finest equivalence relation between locally compact groups such that $G$ and $H$ are equivalent whenever there is a continuous proper homomorphism $G \to H$ with cocompact image. Answering a question of Cornulier, we show that all non-elementary ... More
Mixed Hodge Structures on the rational homotopy type of intersection spacesApr 19 2016Let $X$ a complex projective variety of complex dimension $n$ with only isolated singularities of simply connected links. We show that we can endow the rational cohomology of the family of the $\overline{p}$-perverse intersection spaces $\{ I^{\overline{p}}X ... More
Some steps on short bridges: Non-metrizable surfaces and CW-complexesMar 18 2011Sep 16 2011Among the classical variants of the Pr\"ufer surface, some are homotopy equivalent to a CW-complex (namely, a point or a wedge of a continuum of circles) and some are not. The obstruction comes from the existence of uncountably many `infinitesimal bridges' ... More
Carne--Varopoulos bounds for centered random walksSep 12 2005Jun 30 2006We extend the Carne--Varopoulos upper bound on the probability transitions of a Markov chain to a certain class of nonreversible processes by introducing the definition of a ``centering measure.'' In the case of random walks on a group, we study the connections ... More
Abelian categories in dimension 2Sep 10 2008The goal of this thesis is to define a 2-dimensional version of abelian categories, where symmetric 2-groups play the role that abelian groups played in 1-dimensional algebra. Abelian and 2-abelian groupoid enriched categories are defined and it is proved ... More
Géométrie birationnelle équivariante des grassmanniennesJan 26 2010Let k be a field, and A a finite-dimensional k-algebra. Let d be an integer. Denote by Gr(d,A) the Grassmannian of d-subspaces of A (viewed as a k-vector space), and by GL_1(A) the algebraic k-group whose points are invertible elements of A. The group ... More
An exact particle splitting algorithm for PIC codesMay 16 2018Dec 03 2018Splitting and merging are long standing issues in PIC codes. I propose a novel algorithm devoted to exact splitting for Particle-In-Cell (PIC) codes relying on Adaptive Mesh Refinement (AMR) grids. AMR grids have - by definition - a constant refinement ... More
A priori error for unilateral contact problems with augmented Lagrange multipliers and IsoGeometric AnalysisMar 30 2018The aim of the present work is to extend the a priori error for contact problems with an augmented Lagrangian method. We focus on unilateral contact problem without friction between an elastic body and a rigid one. We consider the pushforward of a NURBS ... More
Existence of Hartree-Fock excited states for atoms and moleculesAug 01 2017Oct 18 2017For neutral and positively charged atoms and molecules, we prove the existence of infinitely many Hartree-Fock critical points below the first energy threshold (that is, the lowest energy of the same system with one electron removed). This is the equivalent, ... More
Probability of hitting a distant point for the voter model started with a single oneSep 28 2006The goal of this work is to find the asymptotics of the hitting probability of a distant point for the voter model on the integer lattice started from a single 1 at the origin. In dimensions 2 or 3, we obtain the precise asymptotic behavior of this probability. ... More
Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretationApr 18 2019This article aims at establishing new benchmark scenarios for Galactic cosmic-ray propagation in the GV-TV rigidity range, based on fits to the AMS-02 B/C data with the USINE v3.5 propagation code. We employ a new fitting procedure, cautiously taking ... More
Estimating the conditional density by histogram type estimators and model selectionDec 22 2015Feb 02 2016We propose a new estimation procedure of the conditional density for independent and identically distributed data. Our procedure aims at using the data to select a function among arbitrary (at most countable) collections of candidates. By using a deterministic ... More
Quenched invariance principles for random walks with random conductancesNov 20 2006Oct 16 2007We prove an almost sure invariance principle for a random walker among i.i.d. conductances in $\Z^d$, $d\geq 2$. We assume conductances are bounded from above but we dot require they are bounded from below.
Dissipation and nonlocality in a general expanding braneworld universeJul 26 2008Feb 18 2009We study the evolution of both scalar and tensor cosmological perturbations in a Randall-Sundrum braneworld having an arbitrary expansion history. We adopt a four dimensional point of view where the degrees of freedom on the brane constitute an open quantum ... More
Integrated volatility and round-off errorSep 04 2009We consider a microstructure model for a financial asset, allowing for price discreteness and for a diffusive behavior at large sampling scale. This model, introduced by Delattre and Jacod, consists in the observation at the high frequency $n$, with round-off ... More
Moduli of linear and abelian categoriesJul 17 2006Linear categories naturally have several identification relations : isomorphisms, categorical equivalences and Morita equivalences. In this thesis, we construct the classifying stacks for these three relations ($\ukcatiso$, $\ukcateq$, $\ukcatmor$) together ... More
The Powers of 9 and Related Mathematical Tables from BabylonJun 25 2013Jul 17 2014Late-Babylonian mathematics (450-100 BC), represented by some 60 cuneiform tablets from Babylon and Uruk, is incompletely known compared to its abundantly preserved, well-studied Old-Babylonian predecessor (1800-1600 BC). With the present paper, 16 fragments ... More
Regge Amplitudes for Two-to-Two ReactionsNov 25 2013We present a fit based on Regge theory of two-to-two reactions at high energies particulary focused on leading non-strange positive naturality exchanges. Factorization of the residues is assumed between beam and target vertices. This study is a first ... More
Extremal loop weight modules for $U_q(\hat{sl}_\infty)$Sep 17 2013We construct by fusion product new irreducible representations of the quantum affinization $U_q(\hat{sl}_\infty)$. The action is defined via the Drinfeld coproduct and is related to the crystal structure of semi-standard tableaux of type $A_\infty$. We ... More
Differentiating the entropy of random walks on hyperbolic groupsSep 10 2012Jan 09 2015We show that the asymptotic entropy of a random walk on a nonelementary hyperbolic group, with symmetric and bounded increments, is differentiable and we identify its derivative as a correlation. We also prove similar results for the rate of escape.
A nonlinear variational problem in relativistic quantum mechanicsSep 13 2012We describe several recent results obtained in collaboration with P. Gravejat, C. Hainzl, E. S\'er\'e and J.P. Solovej, concerning a nonlinear model for the relativistic quantum vacuum in interaction with a classical electromagnetic field.
Pixel detector R&D for the Compact Linear ColliderFeb 23 2019The physics aims at the proposed future CLIC high-energy linear $e^+ e^-$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness ... More
MotàMot project: conversion of a French-Khmer published dictionary for building a multilingual lexical systemMay 22 2014Economic issues related to the information processing techniques are very important. The development of such technologies is a major asset for developing countries like Cambodia and Laos, and emerging ones like Vietnam, Malaysia and Thailand. The MotAMot ... More
Log homogeneous compactifications of some classical groupsMar 18 2014We generalize in positive characteristics some results of Bien and Brion on log homogeneous compactifications of a homogeneous space under the action of a connected reductive group. We also construct an explicit smooth log homogeneous compactification ... More
Directions in Type I spacesApr 04 2014A direction in a Type I space $X=\cup_{\alpha<\omega_1}X_\alpha$ is a closed and unbounded subset $D$ of $X$ such that given any continuous $f:X\to\mathbb{L}_{\ge 0}$ (the closed long ray), if $f$ is unbounded on $D$ then $f$ is unbounded on each unbounded ... More
On a symmetric space attached to polyzeta valuesOct 02 2008Quickly convergent series are given to compute polyzeta numbers. The formula involves an intricate combination of (generalized) polylogarithms at 1/2. However, the combinatorics has a very simple geometric interpretation: it corresponds with the square ... More
Curves of constant diameter and inscribed polygonsApr 14 2005Feb 10 2012A simple closed curve in the Euclidean plane is said to have property C_n(R) if at each point we can inscribe a unique regular $n$-gon with edges length $R$. C_2(R) is equivalent to having constant diameter. We show that smooth curves satisfying C_n(R) ... More
A Collection of Problems on Spectrally Bounded OperatorsOct 15 2008We discuss several open problems on spectrally bounded operators, some new, some old, adding in a few new insights.
BB_twtr at SemEval-2017 Task 4: Twitter Sentiment Analysis with CNNs and LSTMsApr 20 2017In this paper we describe our attempt at producing a state-of-the-art Twitter sentiment classifier using Convolutional Neural Networks (CNNs) and Long Short Term Memory (LSTMs) networks. Our system leverages a large amount of unlabeled data to pre-train ... More
Pixel detector R&D for the Compact Linear ColliderFeb 23 2019May 10 2019The physics aims at the proposed future CLIC high-energy linear $e^+ e^-$ collider pose challenging demands on the performance of the detector system. In particular the vertex and tracking detectors have to combine precision measurements with robustness ... More
Poincaré duality for spaces with isolated singularitiesJul 27 2015Sep 24 2016In this paper we assign, under reasonable hypothesis, to each pseudomanifold with isolated singularities a rational Poincar\'e duality space. These spaces are constructed with the formalism of intersections spaces defined by Markus Banagl and are indeed ... More
Virtually splitting the map from Aut(G) to Out(G)Jan 18 2013We give an elementary criterion on a group G for the map from Aut(G) to Out(G) to split virtually. This criterion applies to many residually finite CAT(0) groups and hyperbolic groups, and in particular to all finitely generated Coxeter groups. As a consequence ... More
The W_k structure of the Z_k^(3/2) modelsJun 04 2009Generalized Z_k^(r/2) parafermionic theories - characterized by the dimension (r/2)(1-1/k) of the basic parafermionic field - provide potentially interesting quantum-Hall trial wavefunctions. Such wavefunctions reveal a W_k structure. This suggests the ... More
Evolution of cosmological perturbations in braneworld universesMar 03 2009In this thesis we mainly explore the evolution of both scalar and tensor cosmological perturbations in a Randall-Sundrum braneworld having an arbitrary expansion history. We adopt a four-dimensional perspective in which the localized degrees of freedom ... More
Conservation laws for colliding branes with induced gravitySep 26 2013Apr 29 2015We derive conservation laws for collisions of self-gravitating $n$-branes (or $n$-dimensional shells) in an $(n+2)$ dimensional spacetime including induced gravity on the brane. Previous work has shown how geometrical identities in general relativity ... More
Abelian 1-factorizations of complete multipartite graphsOct 03 2012An automorphism group G of a 1-factorization of the complete multipartite graph $K_{m\times n}$ consists in permutations of the vertices of the graph mapping factors to factors. In this paper, we give a complete answer to the existence or non-existence ... More
Comment on higher derivative Lagrangians in relativistic theoryMay 24 2013Aug 17 2013We discuss the consequences of higher derivative Lagrangians of the form $\alpha_1 A_{\mu}(x)\dot{x}^\mu$, $\alpha_2 G_{\mu}(x)\ddot{x}^\mu$, $\alpha_3 B_{\mu}(x)\dddot{x}^\mu$, $\alpha_4 K_{\mu}(x)\ddddot{x}^\mu$, $\cdots$, $U_{(n)\mu}(x)x^{(n)\mu}$ ... More
Feynman Path Integral approach to electron diffraction for one and two slits, analytical resultsOct 11 2011Mar 15 2012In this article we present an analytic solution of the famous problem of diffraction and interference of electrons through one and two slits (for simplicity, only the one-dimensional case is considered). In addition to exact formulas, we exhibit various ... More
Geometric methods for nonlinear many-body quantum systemsSep 15 2010Dec 10 2010Geometric techniques have played an important role in the seventies, for the study of the spectrum of many-body Schr\"odinger operators. In this paper we provide a formalism which also allows to study nonlinear systems. We start by defining a weak topology ... More
Notes on linearly H-closed spaces and od-selection principlesSep 03 2016Feb 28 2019A space is called linearly H-closed iff any chain cover possesses a dense member. This property lies strictly between feeble compactness and H-closedness. While regular H-closed spaces are compact, there are linearly H-closed spaces which are even collectionwise ... More
Identification of Mars gully activity types associated with ice compositionDec 16 2015The detection of geologically recent channels at the end of the twentieth century rapidly suggested that liquid water could have been present on Mars up to recent times. A mechanism involving melting of water ice during ice ages in the last several million ... More
Mean-field limit of Bose systems: rigorous resultsOct 15 2015We review recent results about the derivation of the Gross-Pitaevskii equation and of the Bogoliubov excitation spectrum, starting from many-body quantum mechanics. We focus on the mean-field regime, where the interaction is multiplied by a coupling constant ... More
Topological Constraints and Rigidity of Network Glasses from Molecular Dynamics SimulationsJun 22 2015Due to its non-crystalline nature, the glassy state has remained one the most exciting scientific challenges. To study such materials, Molecular Dynamics (MD) simulations have been extensively used because they provide a direct view into its microscopic ... More