Results for "Daniel Cer"

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ReQA: An Evaluation for End-to-End Answer Retrieval ModelsJul 10 2019Popular QA benchmarks like SQuAD have driven progress on the task of identifying answer spans within a specific passage, with models now surpassing human performance. However, retrieving relevant answers from a huge corpus of documents is still a challenging ... More
Multilingual Universal Sentence Encoder for Semantic RetrievalJul 09 2019We introduce two pre-trained retrieval focused multilingual sentence encoding models, respectively based on the Transformer and CNN model architectures. The models embed text from 16 languages into a single semantic space using a multi-task trained dual-encoder ... More
SemEval-2017 Task 1: Semantic Textual Similarity - Multilingual and Cross-lingual Focused EvaluationJul 31 2017Semantic Textual Similarity (STS) measures the meaning similarity of sentences. Applications include machine translation (MT), summarization, generation, question answering (QA), short answer grading, semantic search, dialog and conversational systems. ... More
Learning Cross-Lingual Sentence Representations via a Multi-task Dual-Encoder ModelOct 30 2018Dec 21 2018A significant roadblock in multilingual neural language modeling is the lack of labeled non-English data. One potential method for overcoming this issue is learning cross-lingual text representations that can be used to transfer the performance from training ... More
Hierarchical Document Encoder for Parallel Corpus MiningJun 20 2019Jun 30 2019We explore using multilingual document embeddings for nearest neighbor mining of parallel data. Three document-level representations are investigated: (i) document embeddings generated by simply averaging multilingual sentence embeddings; (ii) a neural ... More
Improving Multilingual Sentence Embedding using Bi-directional Dual Encoder with Additive Margin SoftmaxFeb 22 2019In this paper, we present an approach to learn multilingual sentence embeddings using a bi-directional dual-encoder with additive margin softmax. The embeddings are able to achieve state-of-the-art results on the United Nations (UN) parallel corpus retrieval ... More
Hierarchical Document Encoder for Parallel Corpus MiningJun 20 2019We explore using multilingual document embeddings for nearest neighbor mining of parallel data. Three document-level representations are investigated: (i) document embeddings generated by simply averaging multilingual sentence embeddings; (ii) a neural ... More
Improving Multilingual Sentence Embedding using Bi-directional Dual Encoder with Additive Margin SoftmaxFeb 22 2019Jun 14 2019In this paper, we present an approach to learn multilingual sentence embeddings using a bi-directional dual-encoder with additive margin softmax. The embeddings are able to achieve state-of-the-art results on the United Nations (UN) parallel corpus retrieval ... More
Effective Parallel Corpus Mining using Bilingual Sentence EmbeddingsJul 31 2018Aug 02 2018This paper presents an effective approach for parallel corpus mining using bilingual sentence embeddings. Our embedding models are trained to produce similar representations exclusively for bilingual sentence pairs that are translations of each other. ... More
Learning Semantic Textual Similarity from ConversationsApr 20 2018We present a novel approach to learn representations for sentence-level semantic similarity using conversational data. Our method trains an unsupervised model to predict conversational input-response pairs. The resulting sentence embeddings perform well ... More
Universal Sentence EncoderMar 29 2018Apr 12 2018We present models for encoding sentences into embedding vectors that specifically target transfer learning to other NLP tasks. The models are efficient and result in accurate performance on diverse transfer tasks. Two variants of the encoding models allow ... More
Formalizing and Checking Thread Refinement for Data-Race-Free Execution Models (Extended Version)Oct 24 2015When optimizing a thread in a concurrent program (either done manually or by the compiler), it must be guaranteed that the resulting thread is a refinement of the original thread. Most theories of valid optimizations are formulated in terms of valid syntactic ... More
Desensitizing Inflation from the Planck ScaleApr 21 2010A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale ... More
Signatures of Supersymmetry from the Early UniverseSep 01 2011Oct 11 2011Supersymmetry plays a fundamental role in the radiative stability of many inflationary models. Spontaneous breaking of the symmetry inevitably leads to fields with masses of order the Hubble scale during inflation. When these fields couple to the inflaton ... More
The symmetric Radon-Nikodým property for tensor normsMay 15 2010We introduce the symmetric-Radon-Nikod\'ym property (sRN property) for finitely generated s-tensor norms $\beta$ of order $n$ and prove a Lewis type theorem for s-tensor norms with this property. As a consequence, if $\beta$ is a projective s-tensor norm ... More
Five basic lemmas for symmetric tensor products of normed spacesMay 18 2011We give the symmetric version of five lemmas which are essential for the theory of tensor products (and norms). These are: the approximation, extension, embedding, density and local technique lemmas. Some application of these tools to the metric theory ... More
Long-Range Correlations in Self-Gravitating N-Body SystemsJan 29 2002Observed self-gravitating systems reveal often fragmented non-equilibrium structures that feature characteristic long-range correlations. However, models accounting for non-linear structure growth are not always consistent with observations and a better ... More
Lumpy Structures in Self-Gravitating DisksMay 29 2001Following Toomre & Kalnajs (1991), local models of slightly dissipative self-gravitating disks show how inhomogeneous structures can be maintained over several galaxy rotations. Their basic physical ingredients are self-gravity, dissipation and differential ... More
Equilateral Non-Gaussianity and New Physics on the HorizonFeb 25 2011Mar 23 2011We examine the effective theory of single-field inflation in the limit where the scalar perturbations propagate with a small speed of sound. In this case the non-linearly realized time-translation symmetry of the Lagrangian implies large interactions, ... More
Natural symmetric tensor normsFeb 22 2010Dec 14 2010In the spirit of the work of Grothendieck, we introduce and study natural symmetric n-fold tensor norms. We prove that there are exactly six natural symmetric tensor norms for $n\ge 3$, a noteworthy difference with the 2-fold case in which there are four. ... More
Casimir force in O(n) lattice models with a diffuse interfaceJun 23 2008On the example of the spherical model we study, as a function of the temperature $T$, the behavior of the Casimir force in O(n) systems with a diffuse interface and slab geometry $\infty^{d-1}\times L$, where $2<d<4$ is the dimensionality of the system. ... More
Fragmentation in Kinematically Cold DisksJan 16 2001Gravity is scale free. Thus gravity may form similar structures in self-gravitating systems on different scales. Indeed, observations of the interstellar medium, spiral disks and cosmic structures, reveal similar characteristics. The structures in these ... More
A Field Range Bound for General Single-Field InflationNov 13 2011We explore the consequences of a detection of primordial tensor fluctuations for general single-field models of inflation. Using the effective theory of inflation, we propose a generalization of the Lyth bound. Our bound applies to all single-field models ... More
Extending polynomials in maximal and minimal idealsOct 20 2009Feb 08 2010Given an homogeneous polynomial on a Banach space $E$ belonging to some maximal or minimal polynomial ideal, we consider its iterated extension to an ultrapower of $E$ and prove that this extension remains in the ideal and has the same ideal norm. As ... More
Unconditionality in tensor products and ideals of polynomials, multilinear forms and operatorsJun 17 2009Feb 08 2010We study tensor norms that destroy unconditionality in the following sense: for every Banach space $E$ with unconditional basis, the $n$-fold tensor product of $E$ (with the corresponding tensor norm) does not have unconditional basis. We establish an ... More
Review of lattice studies of resonancesNov 26 2012I review recent progress in extracting resonance parameters using lattice field theory, with an emphasis on determining hadron resonances from lattice quantum chromodynamics. Until recently, the \rho-meson channel was the only one considered, while, during ... More
Penner Type Ensemble for Gauge Theories RevisitedSep 26 2012The Penner type beta-ensemble for Omega-deformed N=2 SU(2) gauge theory with two massless flavors arising as a limiting case from the AGT conjecture is considered. The partition function can be calculated perturbatively in a saddle-point approximation. ... More
Wall Crossing Phenomenology of OrientifoldsJan 28 2010We initiate the study of wall crossing phenomena in orientifolds of local toric Calabi-Yau 3-folds from a topological string perspective. For this purpose, we define a notion of real Donaldson-Thomas partition function at the large volume, orbifold and ... More
And the winner is: galaxy massFeb 24 2011The environment is known to affect the formation and evolution of galaxies considerably best visible through the well-known morphology-density relationship. We study the effect of environment on the evolution of early-type galaxies for a sample of 3,360 ... More
An Application of Topological Data Analysis to Hockey AnalyticsSep 25 2014This paper applies the major computational tool from Topological Data Analysis (TDA), persistent homology, to discover patterns in the data related to professional sports teams. I will use official game data from the North-American National Hockey League ... More
Solenoidal attractors with bounded combinatorics are shyMar 21 2016Mar 25 2016We show that in a generic finite-dimensional real-analytic family of real-analytic multimodal maps, the subset of parameters on which the corresponding map has a solenoidal attractor with bounded combinatorics is a set with zero Lebesgue measure.
Multiplicative structures on homotopy spectral sequences IMay 12 2003This mostly expository paper records some basic facts about towers of homotopy fiber sequences. We give a proof that a pairing of towers induces a pairing of associated spectral sequences, for towers of spaces and towers of spectra.
Effects of the continuous spontaneous localization model in the regime of large localization length scaleOct 02 2013Working in the limit in which the localization length scale is large compared to other relevant length scales we examine three experimental situations with the continuous spontaneous localization (CSL) model---a well-motivated alternative to standard ... More
Single particle energy diffusion from relativistic spontaneous localizationJun 24 2013Energy diffusion due to spontaneous localization (SL) for a relativistically-fast moving particle is examined. SL is an alternative to standard quantum theory in which quantum state reduction is treated as a random physical process which is incorporated ... More
Explaining Ramanujan's "Unclosed" Comment in His Last Letter to HardyDec 23 2015Jan 01 2016We study the $q$-series $F(q) = \sum q^{m(m+1)/2}/(q)_m^2$ and offer some commentary on why Ramanujan may have thought $F(q)$ does not "close."
Wormholes, Emergent Gauge Fields, and the Weak Gravity ConjectureOct 27 2015Dec 04 2015This paper revisits the question of reconstructing bulk gauge fields as boundary operators in AdS/CFT. In the presence of the wormhole dual to the thermofield double state of two CFTs, the existence of bulk gauge fields is in some tension with the microscopic ... More
Aspects of the Papadodimas-Raju Proposal for the Black Hole InteriorMay 08 2014Jun 17 2014In this note I elaborate on some features of a recent proposal of Papadodimas and Raju for a CFT description of the interior of a one-sided AdS black hole in a pure state. I clarify the treatment of 1/N corrections, and explain how the proposal is able ... More
Crystals and intersecting branesJul 05 2006We show that the index of BPS bound states of D4, D2 and D0 branes in IIA theory compactified on a toric Calabi Yau are encoded in the combinatoric counting of restricted three dimensional partitions. Using the torus symmetry, we demonstrate that the ... More
The seeds of cosmic structures as a door to Quantum Gravity PhenomenaDec 17 2007This paper contains a critique of the standard inflationary account of the origin of cosmological structures from quantum fluctuations in the early universe. This critique can be thought to be purely philosophical in nature, but I prefer to view it, rather, ... More
Perspectives on Quantum Gravity PhenomenologyDec 01 2005The idea that quantum gravity manifestations would be associated with a violation of Lorentz invariance is very strongly bounded and faces serious theoretical challenges. Other related ideas seem to be drowning in interpretational quagmires. This leads ... More
PSL(2,C), the exponential and some new free groupsSep 02 2015We prove a normal form result for the groupoid of germs generated by PSL(2,C) and the exponential map. As consequences, we generalize a result of Cohen about the group of translations and powers, and prove that the subgroup of Homeo(R,+infinity) generated ... More
SN 1987A at High ResolutionJan 04 2013Handed the baton from ROSAT, early observations of SN 1987A with the Chandra HETG and the XMM-Newton RGS showed broad lines with a FWHM of 10^4 km/s: the SN blast wave was continuing to shock the H II region around SN 1987A. Since then, its picturesque ... More
On the asymptotics of the Aubin-Yau functionalFeb 19 2015We derive an explicit formula for the asymptotic slope of the Aubin-Yau functional along Bergman geodesics. The result gives a way to check directly whether a projective variety is Chow-Mumford stable.
Embedding types and canonical affine maps between Bruhat-Tits buildings of classical groups (Thesis)Apr 23 2010Aug 24 2010P. Broussous and S. Stevens studied maps between enlarged Bruhat-Tits buildings to construct types for p-adic unitary groups. They needed maps which respect the Moy-Prasad filtrations. That property is called (CLF), i.e. compatibility with the Lie algebra ... More
Modeling Chebyshev's Bias in the Gaussian Primes as a Random WalkAug 30 2016Sep 05 2016One aspect of Chebyshev's bias is the phenomenon that a prime number, $ q $, modulo another prime number, $ p$, experimentally seems to be slightly more likely to be a nonquadratic residue than a quadratic residue. We thought it would be interesting to ... More
Holophrasm: a neural Automated Theorem Prover for higher-order logicAug 08 2016Aug 10 2016I propose a system for Automated Theorem Proving in higher order logic using deep learning and eschewing hand-constructed features. Holophrasm exploits the formalism of the Metamath language and explores partial proof trees using a neural-network-augmented ... More
All-Order Theory of Continuous Quantum Noise Measurements: Application to Spin Noise SpectroscopyNov 07 2016Nov 08 2016The stochastic detector output $z(t)$ of a general continuously measured quantum system is calculated using a stochastic master equation approach. The resulting continuous quantum noise formula (CQNF) is valid in all orders of the measurement strength. ... More
Three attempts at two axioms for quantum mechanicsNov 24 2010Nov 04 2011The axioms of nonrelativistic quantum mechanics lack clear physical meaning. In particular, they say nothing about nonlocality. Yet quantum mechanics is not only nonlocal, it is twice nonlocal: there are nonlocal quantum correlations, and there is the ... More
Equation of State of Gluon Plasma from Local ActionOct 02 2006Oct 15 2007We review recent analytic and numerical results concerning the confinement scenario in Coulomb gauge. We then consider a local, renormalizable, BRST-invariant action for QCD in Coulomb gauge that contains auxiliary bose and fermi ghost fields and sources. ... More
Continued Fractions and the Rabi ModelMay 15 2012Apr 10 2013Techniques based on continued fractions to compute numerically the spectrum of the quantum Rabi model are reviewed. They are of two essentially different types. In the first case, the spectral condition is implemented using a representation in the infinite-dimensional ... More
Comment on "Optical Response of Gas-Phase Atoms at Less than lambda/80 from a Dielectric Surface" published by K. A. Whittaker et al.Dec 24 2014Comment on "Optical Response of Gas-Phase Atoms at Less than lambda/80 from a Dielectric Surface" published by K. A. Whittaker, J. Keaveney, I. G. Hughes, A. Sargsyan, D. Sarkisyan, C. S. Adams in Phys. Rev. Lett. Lett 112 253201 (2014)
Comment on "Spin-1 aggregation model in one dimension"Sep 19 2001M. Girardi and W. Figueiredo have proposed a simple model of aggregation in one dimension to mimic the self-assembly of amphiphiles in aqueous solution [Phys. Rev. E 62, 8344 (2000)]. We point out that interesting results can be obtained if a different ... More
Optimal adaptive control of cascading power grid failuresDec 17 2010We present theoretical results and experiments with parallel algorithms for computing an adaptive, online control with the objective of attenuating a power grid cascading failure.
Evidence for chemical equilibration at RHICDec 13 2001This contribution focuses on the results of statistical model calculations at RHIC energies, including recently available experimental data. Previous calculations of particle yield ratios showed good agreement with measurements at SPS and lower energies, ... More
Revisiting the scattering greenhouse effect of CO2 ice cloudsJan 06 2016Carbon dioxide ice clouds are thought to play an important role for cold terrestrial planets with thick CO2 dominated atmospheres. Various previous studies showed that a scattering greenhouse effect by carbon dioxide ice clouds could result in a massive ... More
Information Theory and Statistics: an overviewNov 03 2015We give an overview of the role of information theory in statistics, and particularly in biostatistics. We recall the basic quantities in information theory; entropy, cross-entropy, conditional entropy, mutual information and Kullback-Leibler risk. Then ... More
Statistical models, likelihood, penalized likelihood and hierarchical likelihoodAug 29 2008We give an overview of statistical models and likelihood, together with two of its variants: penalized and hierarchical likelihood. The Kullback-Leibler divergence is referred to repeatedly, for defining the misspecification risk of a model, for grounding ... More
Not Only Because of Theory: Dyson, Eddington and the Competing Myths of the 1919 Eclipse ExpeditionSep 05 2007Sep 05 2007The 1919 Eclipse Expedition to test the light-bending prediction of General Relativity remains one of the most famous physics experiments of the 20th century. However, in recent decades it has been increasingly often alleged that the data-analysis of ... More
Stability under radiation reaction of circular equatorial orbits around Kerr black holesMay 29 1998We examine the evolution, under gravitational radiation reaction, of slightly eccentric equatorial orbits of point particles around Kerr black holes. Our method involves numerical integration of the Sasaki-Nakamura equation. It is discovered that such ... More
Multitype Contact Process on $\Z$: Extinction and InterfaceApr 12 2010We consider a two-type contact process on $\Z$ in which both types have equal finite range and supercritical infection rate. We show that a given type becomes extinct with probability 1 if and only if, in the initial configuration, it is confined to a ... More
Tight-binding branch-point energies and band offsets for cubic InN, GaN, AlN and AlGaN alloysFeb 07 2013Starting with empirical tight-binding band structures, the branch-point (BP) energies and resulting valence band offsets (VBOs) for the zincblende phase of InN, GaN and AlN are calculated from their k-averaged midgap energy. Furthermore, the directional ... More
Isogenies of Elliptic Curves: A Computational ApproachOct 28 2009Isogenies, the mappings of elliptic curves, have become a useful tool in cryptology. These mathematical objects have been proposed for use in computing pairings, constructing hash functions and random number generators, and analyzing the reducibility ... More
Advanced Data Processing in the Business Network SystemDec 28 2013The discovery, representation and reconstruction of Business Networks (BN) from Network Mining (NM) raw data is a difficult problem for enterprises. This is due to huge amounts of e.g. complex business processes within and across enterprise boundaries, ... More
Strongly quasi-proper maps and the f-flattening theoremApr 07 2015We complete and precise the results of [B.13] and we prove a strong version of the semi-proper direct image theorem with values in the space C f n (M) of finite type closed n--cycles in a complex space M. We describe the strongly quasi-proper maps as ... More
Complement to algebraic differential equations ...Feb 26 2014We complete the study of some periods of polynomials in (n+1) variables with (n+2) monomials in computing the behavior of these periods in the natural parameter for such a polynomial.
Contruction of quasi-invariant holomorphic parameters for the Gauss-Manin connection of a holomorphic map to a curve (second version)Mar 27 2012In this paper we consider holomorphic families of frescos (i.e. filtered differential equations with a regular singularity) and we construct a locally versal holomorphic family for every fixed Bernstein polynomial. We construct also several holomorphic ... More
Asymptotics of a vanishing period : General existence theorem and basic properties of frescosJan 13 2012In this paper we introduce the word "fresco" to denote a \ $[\lambda]-$primitive monogenic geometric (a,b)-module. The study of this "basic object" (generalized Brieskorn module with one generator) which corresponds to the minimal filtered (regular) differential ... More
An Extended Note on the Comparison-optimal Dual Pivot QuickselectJul 18 2016In this note the precise minimum number of key comparisons any dual-pivot quickselect algorithm (without sampling) needs on average is determined. The result is in the form of exact as well as asymptotic formul\ae{} of this number of a comparison-optimal ... More
Screening Genome Sequences for Known RNA Genes and MotifsDec 22 2015This methods paper presents computational protocols for the identification of non-coding RNA genes or RNA motifs within genomic sequences. An application to bacterial small RNA is proposed.
Syntax-Semantics Interaction Parsing Strategies. Inside SYNTAGMAJan 21 2016This paper discusses SYNTAGMA, a rule based NLP system addressing the tricky issues of syntactic ambiguity reduction and word sense disambiguation as well as providing innovative and original solutions for constituent generation and constraints management. ... More
P vs. NPJan 07 2016The method for analyzing algorithmic runtime complexity using decision trees is discussed using the sorting algorithm. This method is then extended to optimal algorithms which may find all cliques of size q in network N, or simply the first clique of ... More
Minimization of Büchi Automata using Fair SimulationMar 03 2016We present an algorithm, which reduces the size of B\"uchi automata using fair simulation. Its time complexity is $\mathcal{O}(|Q|^4 \cdot |\Delta|^2)$, the space complexity is $\mathcal{O}(|Q| \cdot |\Delta|)$. Simulation is a common approach for minimizing ... More
Asteroseismology of Exoplanet Host StarsNov 23 2015Nov 29 2015Asteroseismology is among the most powerful observational tools to determine fundamental properties of stars. Space-based photometry has recently enabled the systematic detection of oscillations in exoplanet host stars, allowing a combination of asteroseismology ... More
Noetherianity and rooted treesSep 14 2015Let T be the category whose objects are rooted trees and morphisms are order embeddings preserving the root. We prove that finitely generated representations of T are Noetherian using techniques developed by Sam and Snowden which generalize classical ... More
Spin Systems and Computational ComplexityNov 30 2009I give a very brief non-technical introduction to the intersection of the fields of spin systems and computational complexity. The focus is on spin glasses and their relationship to NP-complete problems.
An Introduction to Quantum Error CorrectionApr 18 2000Quantum states are very delicate, so it is likely some sort of quantum error correction will be necessary to build reliable quantum computers. The theory of quantum error-correcting codes has some close ties to and some striking differences from the theory ... More
Quantum Statistics with Classical ParticlesNov 08 2005Dec 29 2005Indistinguishability of particles is normally considered to be an inherently quantum property which cannot be possessed by a classical theory. However, Saunders has argued that this is incorrect, and that classically indistinguishable particles are possible. ... More
Uncloneable EncryptionOct 09 2002Sep 03 2004Quantum states cannot be cloned. I show how to extend this property to classical messages encoded using quantum states, a task I call "uncloneable encryption." An uncloneable encryption scheme has the property that an eavesdropper Eve not only cannot ... More
Fault-Tolerant Quantum Computation with Local GatesMar 30 1999I discuss how to perform fault-tolerant quantum computation with concatenated codes using local gates in small numbers of dimensions. I show that a threshold result still exists in three, two, or one dimensions when next-to-nearest-neighbor gates are ... More
Stabilizer Codes and Quantum Error CorrectionMay 28 1997Controlling operational errors and decoherence is one of the major challenges facing the field of quantum computation and other attempts to create specified many-particle entangled states. The field of quantum error correction has developed to meet this ... More
A Class of Quantum Error-Correcting Codes Saturating the Quantum Hamming BoundApr 29 1996Jul 24 1996I develop methods for analyzing quantum error-correcting codes, and use these methods to construct an infinite class of codes saturating the quantum Hamming bound. These codes encode $k=n-j-2$ qubits in $n=2^j$ qubits and correct $t=1$ error.
Traversable Wormholes and Black Hole ComplementarityApr 15 1994Black hole complementarity is incompatible with the existence of traversable wormholes. In fact, traversable wormholes cause problems for any theory where information comes out in the Hawking radiation.
On the additive chromatic number of several families of graphsFeb 24 2016Feb 27 2016Let $f:V \rightarrow \{1,\ldots,k\}$ be a labeling of the vertices of a graph $G = (V,E)$ and denote with $f(N(v))$ the sum of the labels of all vertices adjacent to $v$. The least value $k$ for which a graph $G$ admits a labeling satisfying $f(N(u)) ... More
Cocycle superrigidity for coinduced actionsNov 30 2015We prove a cocycle superrigidity theorem for a large class of coinduced actions. In particular, if $\Lambda$ is a subgroup of a countable group $\Gamma$, we consider a probability measure preserving action $\Lambda\curvearrowright X_0$ and let $\Gamma\curvearrowright ... More
A global Torelli theorem for hyperkaehler manifolds (after Verbitsky)Jun 28 2011Compact hyperkaehler manifolds are higher-dimensional generalizations of K3 surfaces. The classical Global Torelli theorem for K3 surfaces, however, does not hold in higher dimensions. More precisely, a compact hyperkaehler manifold is in general not ... More
The asymptotic dimension of quotients by finite groupsMay 14 2016Let $X$ be a proper metric space and let $F$ be a finite group acting on $X$ by isometries. We show that the asymptotic dimension of $F\backslash X$ is the same as the asymptotic dimension of $X$.
On circuits and serial symmetric basis-exchange in matroidsOct 24 2011Oct 04 2012The way circuits, relative to a basis, are affected as a result of exchanging a basis element, is studied. As consequences, it is shown that three consecutive symmetric exchanges exist for any two bases of a matroid, and that a full serial symmetric exchange, ... More
On how much X-ray and UV radiation processes are coupled in accretion disks: AGN caseJul 06 2005Within the standard accretion disk theory for active galactic nuclei (AGN), the observed X-rays are often modeled by Compton up-scattering of ultraviolet (UV) disk photons inside a hot disk corona. Here, we point out that for many AGN, radiation pressure ... More
Comparison of theoretical radiation-driven winds from stars and discsJan 04 1999We compare models of line-driven winds from accretion discs and single spherical stars. We look at the problem of scaling mass-loss rates and velocities of stellar and disc winds with model parameters. We find that stellar and disc winds driven by radiation, ... More
Numerical Studies of Hamiltonian Systems and Application to Galactic PotentialsNov 17 2014The talk consisted mainly in commenting in a linear way the seminal paper in 1964 by Michel Henon and graduate student Carl Heiles at Princeton University: "The applicability of the third integral of motion: Some numerical experiments" in the field of ... More
Systèmes lagrangiens et fonction $β$ de MatherFeb 07 2011We review the author's results on Mather's $\beta$ function : non-strict convexity of $\beta$ when the configuration space has dimension two, link between the size of the Aubry set and the differentiability of $\beta$, correlation between the rationality ... More
Angular dependences in inclusive two-hadron production at BELLEApr 15 2008May 07 2008A collection of results is presented relevant for the analysis of azimuthal asymmetries in inclusive two-hadron production at BELLE. The aim of this overview is to provide theoretical ingredients necessary to extract the Collins effect fragmentation function. ... More
Aspects of TMD evolution of azimuthal asymmetriesAug 20 2013In this contribution TMD evolution of azimuthal asymmetries, in particular of the Sivers and double Collins asymmetries, is addressed. A comparison of the scale dependence is made between asymmetries described with TMD factorization at low transverse ... More
Handedness inside the protonNov 05 2002The transversity of quarks inside unpolarized hadrons and its phenomenology are discussed. Several experimental suggestions are proposed that would allow further study of this intrinsic handedness.
New Lower Bounds for van der Waerden Numbers Using Distributed ComputingMar 09 2016Mar 24 2016This project found improved lower bounds for van der Waerden numbers. The number $W(k,r)$ is the length of the shortest sequence of colors with $r$ different colors that guarantees an evenly-spaced subsequence (or arithmetic progression) of the same color ... More
Algebraic approach to q-deformed supersymmetric variants of the Hubbard model with pair hoppingsNov 03 1997Jan 16 1998We construct two quantum spin chains Hamiltonians with quantum sl(2|1) invariance. These spin chains define variants of the Hubbard model and describe electron models with pair hoppings. A cubic algebra that admits the Birman-Wenzl-Murakami algebra as ... More
On The Origin Of High Energy Correlations in Gamma-ray BurstsOct 27 2011I investigate the origin of the observed correlation between a GRB's nuFnu spectral peak Epk and its isotropic equivalent energy Eiso through the use of a population synthesis code to model the prompt gamma-ray emission from GRBs. By using prescriptions ... More
Spontaneous symmetry breaking in inflationary cosmology: on the fate of Goldstone BosonsMay 16 2012Jul 11 2012We argue that in an inflationary cosmology a consequence of the lack of time translational invariance is that spontaneous breaking of a continuous symmetry and Goldstone's theorem \emph{do not} imply the existence of \emph{massless} Goldstone modes. We ... More
Space-time evolution of heavy sterile neutrinos in cascade decaysJun 22 2014Aug 25 2014Heavy sterile-like neutrinos may be produced resonantly from the decay of pseudoscalar mesons and may decay into several different channels in a cascade $\Phi \rightarrow L^\alpha \nu_h;\nu_h\rightarrow \{X\}$. In general these are rare events with displaced ... More
Test elements in torsion-free hyperbolic groupsFeb 17 2012Aug 08 2012We prove that in a torsion-free hyperbolic group, an element is a test element if and only if it is not contained in a proper retract.