Results for "Alessandro Tomasi"

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Binary linear code weight distribution estimation by random bit stream compressionJun 06 2018A statistical estimation algorithm of the weight distribution of a linear code is shown, based on using its generator matrix as a compression function on random bit strings.
Two-tier blockchain timestamped notarization with incremental securityFeb 08 2019Digital notarization is one of the most promising services offered by modern blockchain-based solutions. We present a digital notary design with incremental security and cost reduced with respect to current solutions. A client of the service receives ... More
Polycomp: efficient and configurable compression of astronomical timelinesApr 27 2016This paper describes the implementation of polycomp, a open-sourced, publicly available program for compressing one-dimensional data series in tabular format. The program is particularly suited for compressing smooth, noiseless streams of data like pointing ... More
Colour image segmentation by the vector-valued Allen-Cahn phase-field model: a multigrid solutionOct 03 2007We propose a new method for the numerical solution of a PDE-driven model for colour image segmentation and give numerical examples of the results. The method combines the vector-valued Allen-Cahn phase field equation with initial data fitting terms. This ... More
Code generator matrices as RNG conditionersFeb 05 2015Mar 02 2017We quantify precisely the distribution of the output of a binary random number generator (RNG) after conditioning with a binary linear code generator matrix by showing the connection between the Walsh spectrum of the resulting random variable and the ... More
A weight-distribution bound for entropy extractors using linear binary codesMay 12 2014We consider a bound on the bias reduction of a random number generator by processing based on binary linear codes. We introduce a new bound on the total variation distance of the processed output based on the weight distribution of the code generated ... More
Code generator matrices as entropy extractorsFeb 05 2015We show the connection between the Walsh spectrum of the output of a binary random number generator (RNG) and the bias of individual bits, and use this to show how previously known bounds on the performance of linear binary codes as entropy extractors ... More
Convolutional Neural Networks on the HEALPix sphere: a pixel-based algorithm and its application to CMB data analysisFeb 11 2019We describe a novel method for the application of Convolutional Neural Networks (CNNs) to fields defined on the sphere, using the HEALPix tessellation scheme. Specifically, We have developed a pixel-based approach to implement convolutional layers on ... More
Form factor ratio from unpolarized elastic electron proton scatteringApr 08 2016Nov 07 2016A reanalysis of unpolarized electron-proton elastic scattering data is done in terms of the electric to magnetic form factor squared ratio. This observable is in principle more robust against experimental correlations and global normalizations. The present ... More
Outlier Robust ICP for Minimizing Fractional RMSDJun 22 2006We describe a variation of the iterative closest point (ICP) algorithm for aligning two point sets under a set of transformations. Our algorithm is superior to previous algorithms because (1) in determining the optimal alignment, it identifies and discards ... More
A Cesàro Average of Hardy-Littlewood numbersJun 01 2012Let $\Lambda$ be the von Mangoldt function and (r_{\textit{HL}}(n) = \sum_{m_1 + m_2^2 = n} \Lambda(m_1),) be the counting function for the Hardy-Littlewood numbers. Let $N$ be a sufficiently large integer. We prove that \sum_{n \le N} r_{\textit{HL}}(n) ... More
Sum of one prime and two squares of primes in short intervalsJun 13 2014Jul 30 2015Assuming the Riemann Hypothesis we prove that the interval $[N, N + H]$ contains an integer which is a sum of a prime and two squares of primes provided that $H \ge C (\log N)^{4}$, where $C > 0$ is an effective constant.
Computing the Mertens and Meissel-Mertens constants for sums over arithmetic progressionsJun 11 2009We give explicit numerical values with 100 decimal digits for the Mertens constant involved in the asymptotic formula for $\sum\limits_{\substack{p\leq x p\equiv a \bmod{q}}}1/p$ and, as a by-product, for the Meissel-Mertens constant defined as $\sum_{p\equiv ... More
Cesàro average in short intervals for Goldbach numbersJun 02 2016We prove that a suitable explicit formula for the Cesaro-averaged number of representations of an integer as a sum of two primes holds in short intervals.
Sums of many primesJan 18 2011Assuming that the Generalized Riemann Hypothesis (GRH) holds, we prove an explicit formula for the number of representations of an integer as a sum of $k\geq 5$ primes. Our error terms in such a formula improve by some logarithmic factors an analogous ... More
A Diophantine problem with prime variablesJun 01 2012We study the distribution of the values of the form $\lambda_1 p_1 + \lambda_2 p_2 + \lambda_3 p_3^k$, where $\lambda_1$, $\lambda_2$ and $\lambda_3$ are non-zero real number not all of the same sign, with $\lambda_1 / \lambda_2$ irrational, and $p_1$, ... More
Mean-field quantum dynamics for a mixture of Bose-Einstein condensatesMar 08 2016Sep 12 2016We study the effective time evolution of a large quantum system consisting of a mixture of different species of identical bosons in interaction. If the system is initially prepared so as to exhibit condensation in each component, we prove that condensation ... More
On the constant in the Mertens product for arithmetic progressions. I. IdentitiesJun 19 2007Sep 26 2008The aim of the paper is the proof of new identities for the constant in the Mertens product for arithmetic progressions. We deal with the problem of the numerical computation of these constants in another paper.
A Cesàro Average of Goldbach numbersJun 01 2012Let $\Lambda$ be the von Mangoldt function and (r_G(n) = \sum_{m_1 + m_2 = n} \Lambda(m_1) \Lambda(m_2)) be the counting function for the Goldbach numbers. Let $N \geq 2$ be an integer. We prove that &\sum_{n \le N} r_G(n) \frac{(1 - n/N)^k}{\Gamma(k ... More
Short intervals asymptotic formulae for binary problems with primes and powers, II: density $1$Apr 18 2015Nov 28 2015We prove that suitable asymptotic formulae in short intervals hold for the problems of representing an integer as a sum of a prime square and a square, or a prime square. Such results are obtained both assuming the Riemann Hypothesis and in the unconditional ... More
Short intervals asymptotic formulae for binary problems with primes and powers, I: density $3/2$Apr 09 2015Nov 28 2015We prove that suitable asymptotic formulae in short intervals hold for the problems of representing an integer as a sum of a prime and a square, or a prime square. Such results are obtained both assuming the Riemann Hypothesis and in the unconditional ... More
The number of Goldbach representations of an integerNov 14 2010We prove the following result: Let $N \geq 2$ and assume the Riemann Hypothesis (RH) holds. Then \[ \sum_{n=1}^{N} R(n) =\frac{N^{2}}{2} -2 \sum_{\rho} \frac{N^{\rho + 1}}{\rho (\rho + 1)} + O(N \log^{3}N), \] where $\rho=1/2+i\gamma$ runs over the non-trivial ... More
Explicit relations between primes in short intervals and exponential sums over primesDec 22 2012Dec 29 2012Under the assumption of the Riemann Hypothesis (RH), we prove explicit quantitative relations between hypothetical error terms in the asymptotic formulae for truncated mean-square average of exponential sums over primes and in the mean-square of primes ... More
Blowdown of hydrocarbons pressure vessel with partial phase separationJan 05 2011We propose a model for the simulation of the blowdown of vessels containing two-phase (gas-liquid) hydrocarbon fluids, considering non equilibrium between phases. Two phases may be present either already at the beginning of the blowdown process (for instance ... More
On a ternary Diophantine problem with mixed powers of primesJun 01 2012Jul 30 2012Let $1 < k < 33 / 29$. We prove that if $\lambda_1$, $\lambda_2$ and $\lambda_3$ are non-zero real numbers, not all of the same sign and that $\lambda_1 / \lambda_2$ is irrational and $\varpi$ is any real number, then for any $\eps > 0$ the inequality ... More
A Diophantine problem with a prime and three squares of primesJun 01 2012We prove that if $\lambda_1$, $\lambda_2$, $\lambda_3$ and $\lambda_4$ are non-zero real numbers, not all of the same sign, $\lambda_1 / \lambda_2$ is irrational, and $\varpi$ is any real number then, for any $\eps > 0$ the inequality $ \bigl|\lambda_1 ... More
Generalized Dyson model: nature of zero mode and its implication in dynamicsMay 24 2016Oct 11 2016We study the role of the anomalous $E=0$ state in dynamical properties of non-interacting fermionic chains with chiral symmetry and correlated bond disorder in one dimension. These models posses a diverging density of states at zero energy leading to ... More
Free fall and self-force: an historical perspectiveMay 04 2010Free fall has signed the greatest markings in the history of physics through the leaning Pisa tower, the Cambridge apple tree and the Einstein lift. The perspectives offered by the capture of stars by supermassive black holes are to be cherished, because ... More
Ground state energy of the low density Hubbard model. An upper boundNov 14 2006May 04 2007We derive an upper bound on the ground state energy of the three-dimensional (3D) repulsive Hubbard model on the cubic lattice agreeing in the low density limit with the known asymptotic expression of the ground state energy of the dilute Fermi gas in ... More
Time-reversal odd distribution functions in chiral models with vector mesonsJan 30 2005The so-called time-reversal odd distribution functions are known to be non-vanishing in QCD due to the presence of the link operator in the definition of these quantities. I show that T-odd distributions can be non-vanishing also in chiral models, if ... More
Models for transverse-momentum distributions and transversityNov 28 2011I present a short review of models for transverse-momentum distributions and transversity, with a particular attention on general features common to many models. I compare some model results with experimental extractions. I discuss the existence of relations ... More
GLACIER and related R&DJul 05 2011Liquid argon detectors, with mass up to 100 kton, are being actively studied in the context of proton decay searches, neutrino astrophysics and for the next generation of long baseline neutrino oscillation experiments to study the neutrino mass hierarchy ... More
Variational approximations for stationary states of Ising-like modelsJul 25 2013We introduce a new variational approach to the stationary state of kinetic Ising-like models. The approach is based on the cluster expansion of the entropy term appearing in a functional which is minimized by the system history. We rederive a known mean-field ... More
Deriving exact results for Ising-like models from the cluster variation methodSep 24 1999The cluster variation method (CVM) is an approximation technique which generalizes the mean field approximation and has been widely applied in the last decades, mainly for finding accurate phase diagrams of Ising-like lattice models. Here we discuss in ... More
Bubble propagation in a helicoidal molecular chainJul 26 2000We study the propagation of very large amplitude localized excitations in a model of DNA that takes explicitly into account the helicoidal structure. These excitations represent the ``transcription bubble'', where the hydrogen bonds between complementary ... More
On a Rigorous Proof of the Joos-Zeh Formula for Decoherence in a Two-Body ProblemJul 30 2003We consider a simple one dimensional system consisting of two particles interacting with a $\delta$-potential and we discuss a rigorous derivation of the asymptotic wave function of the system in the limit of small mass ratio. We apply the result to the ... More
Applications of some exponential sums on prime powers: a surveyJun 02 2016A survey paper on some recent results on additive problems with prime powers.
A Formal Framework for Modeling Trust and Reputation in Collective Adaptive SystemsJul 08 2016Trust and reputation models for distributed, collaborative systems have been studied and applied in several domains, in order to stimulate cooperation while preventing selfish and malicious behaviors. Nonetheless, such models have received less attention ... More
Many Haken Heegaard splittingsOct 31 2016We give a simple criterion for a Heegaard splitting to yield a Haken manifold. As a consequence, we construct many Haken manifolds, in particular homology spheres, with prescribed properties, namely Heegaard genus, Heegaard distance and Casson invariant. ... More
Quantum Dynamics in Classical Spin BathsJun 14 2013A formalism for studying the dynamics of quantum systems embedded in classical spin baths is introduced. The theory is based on generalized antisymmetric brackets and predicts the presence of open-path off-diagonal geometric phases in the evolution of ... More
Non-Hamiltonian Commutators in Quantum MechanicsNov 08 2005The symplectic structure of quantum commutators is first unveiled and then exploited to introduce generalized non-Hamiltonian brackets in quantum mechanics. It is easily recognized that quantum-classical systems are described by a particular realization ... More
Phase space flows for non-Hamiltonian systems with constraintsAug 08 2005In this paper, non-Hamiltonian systems with holonomic constraints are treated by a generalization of Dirac's formalism. Non-Hamiltonian phase space flows can be described by generalized antisymmetric brackets or by general Liouville operators which cannot ... More
Geometry of non-compact minimal and marginally outer-trapped surfaces in asymptotically flat manifoldsOct 18 2013Apr 07 2014In this article we extend several foundational results of the theory of complete minimal surfaces of finite index in the Euclidean space to minimal surfaces in asymptotically flat manifolds and, more generally, to marginally outer-trapped surfaces in ... More
A $K$-theoretical invariant and bifurcation for a parameterized family of functionalsMay 24 2009Jul 24 2013For a family of functionals defined on a Hilbert manifold and smoothly depending on a compact finite dimensional manifold, we give a sufficient condition on the parameter space in such a way the family bifurcate from the trivial branch.
Hilbert++ ManualJun 28 2007Mar 01 2009We present here an installation guide, a hand-on mini-tutorial through examples, and the theoretical foundations of the Hilbert++ code.
The world underground scientific facilities. A compendiumDec 07 2007Underground laboratories provide the low radioactive background environment necessary to explore the highest energy scales that cannot be reached with accelerators, by searching for extremely rare phenomena. I have requested to the Directors of the Laboratories ... More
Universal Enveloping Algebras of PBW TypeAug 26 2010Dec 23 2010We continue our investigation of the general notion of universal enveloping algebra introduced in [A. Ardizzoni, \emph{A Milnor-Moore Type Theorem for Primitively Generated Braided Bialgebras}, J. Algebra \textbf{327} (2011), no. 1, 337--365]. Namely ... More
Apolar Ideal and Normal Bundle of Rational CurvesMar 22 2012As in our previous work [1] we address the problem to determine the splitting of the normal bundle of rational curves. With apolarity theory we are able to characterize some particular subvarieties in some Hilbert scheme of rational curves, defined by ... More
Implications of first LHC resultsJul 06 2011We discuss implications of first LHC results for models motivated by the hierarchy problem: large extra dimensions and supersymmetry. We present bounds, global fits and implications for naturalness.
The fine-tuning price of the early LHCJan 11 2011Jul 26 2011LHC already probed and excluded half of the parameter space of the Constrained Minimal Supersymmetric Standard Model allowed by previous experiments. Only about 0.3% of the CMSSM parameter space survives. This fraction rises to about 0.9% if the bound ... More
Radiatively induced light right-handed stopSep 08 1996Sep 10 1996A right-handed stop not much heavier or even lighter than the Z boson has today desirable phenomenological consequences. We study how it can result within the usual radiative scenario of electroweak symmetry breaking. A restriction on the gaugino mass ... More
Interpreting the 750 GeV digamma excess: a reviewMay 30 2016Aug 05 2016We summarise the main experimental, phenomenological and theoretical issues related to the 750 GeV digamma excess
Towards the Modeling of Behavioral Trajectories of Users in Online Social MediaNov 17 2016In this paper, we introduce a methodology that allows to model behavioral trajectories of users in online social media. First, we illustrate how to leverage the probabilistic framework provided by Hidden Markov Models (HMMs) to represent users by embedding ... More
Quaternionic regularity and the dibar-Neumann problem in C^2Dec 04 2006Dec 13 2006Let D be a domain in the quaternionic space H. We prove a differential criterion that characterizes Fueter-regular quaternionic functions f:bD -> H of class C^1. We find differential operators T and N, with complex coefficients, such that a function f ... More
Review of AdS/CFT Integrability, Chapter VI.2: Yangian AlgebraDec 17 2010Nov 07 2011We review the study of Hopf algebras, classical and quantum R-matrices, infinite-dimensional Yangian symmetries and their representations in the context of integrability for the N=4 vs AdS5xS5 correspondence.
Post-merger analytic templates for GW150914Jun 13 2016Following the new analytic description of the postmerger (ringdown) waveform of coalescing, nonprecessing, spinning, black hole binaries (BBHs) introduced in Phys.~Rev.~D~90, 024054 (2014), we propose an analytic, closed form, time-domain, representation ... More
Brief communication. An indefinite Sturm theoryDec 10 2008Sturm theory for second order differential equations was generalized to systems and higher order equations with positive leading coefficient by several authors. Here we propose a Sturm oscillation theorem for indefinite systems of even order and with ... More
Epigenetic Tracking: a Model for Multicellular BiologyApr 08 2013Jul 04 2015Epigenetic Tracking is a mathematical model of biological cells, originally conceived to study embryonic development. Computer simulations proved the capacity of the model to generate complex 3-dimensional cellular structures, and the potential to reproduce ... More
Epigenetic Tracking, a Method to Generate Arbitrary Shapes By Using Evolutionary-Developmental TechniquesMay 16 2008This paper describes an Artificial Embryology method (called ``Epigenetic Tracking'') to generate predefined arbitrarily shaped 2-dimensional arrays of cells by means of evolutionary techniques. It is based on a model of development, whose key features ... More
Steinitz classes of some abelian and nonabelian extensions of even degreeJan 15 2010The Steinitz class of a number field extension K/k is an ideal class in the ring of integers O_k of k, which, together with the degree [K:k] of the extension determines the O_k-module structure of O_K. We call R_t(k,G) the classes which are Steinitz classes ... More
Examples of Hodge Laplacians on quantum spheresSep 07 2011Using a non canonical braiding over the 3d left covariant calculus we present a family of Hodge operators on the quantum SU(2) and its homogeneous quantum two-sphere.
Tree-graded asymptotic conesApr 03 2012We study the bilipschitz equivalence type of tree-graded spaces, showing that asymptotic cones of relatively hyperbolic groups (resp. asymptotic cones of groups containing a cut-point) only depend on the bilipschitz equivalence types of the pieces in ... More
3-manifold groups have unique asymptotic conesSep 21 2011We describe the (minimal) tree-graded structure of asymptotic cones of non-geometric graph manifold groups, and as a consequence we show that all said asymptotic cones are bilipschitz equivalent. Combining this with geometrization and other known results ... More
Projections and relative hyperbolicityOct 21 2010Apr 03 2012We give an alternative definition of relative hyperbolicity based on properties of closest-point projections on peripheral subgroups. We also derive a distance formula for relatively hyperbolic groups, similar to the one for mapping class groups.
Cluster Variation Method in Statistical Physics and Probabilistic Graphical ModelsAug 09 2005The cluster variation method (CVM) is a hierarchy of approximate variational techniques for discrete (Ising--like) models in equilibrium statistical mechanics, improving on the mean--field approximation and the Bethe--Peierls approximation, which can ... More
CVM ANALYSIS OF CROSSOVER IN THE SEMI-INFINITE ISING MODELFeb 03 1995Feb 06 1995The crossover behavior of the semi--infinite three dimensional Ising model is investigated by means of Pad\'e approximant analysis of cluster variation method results. We give estimates for ordinary critical as well as for multicritical exponents, which ... More
Black Holes in Galactic Nuclei: the Promise and the FactsJan 30 2002It has long been suspected that Active Galactic Nuclei are powered by accretion of matter onto massive black holes and this belief implies their presence in the nuclei of most nearby galaxies as "relics" of past activity. Just a few years ago this was ... More
Lattice Integrals of Motion of the Ising Model on the CylinderOct 21 2010Mar 27 2012We consider the 2D critical Ising model with spatially periodic boundary conditions. It is shown that for a suitable reparametrization of the known Boltzmann weights the transfer matrix becomes a polynomial in the variable $\csc(4u)$, being $u$ the spectral ... More
The Baxter Q Operator of Critical Dense PolymersMay 04 2009Sep 07 2009We consider critical dense polymers ${\cal L}_{1,2}$, corresponding to a logarithmic conformal field theory with central charge $c=-2$. An elegant decomposition of the Baxter $Q$ operator is obtained in terms of a finite number of lattice integrals of ... More
Free Field realization of the $\hat{\mathcal{D}}_q$ Algebra for the $η$-$ξ$ system, Integrals of Motion and CharactersNov 12 2012We introduce a free field realization of the central extension of the Lie algebra $\mathcal{D}_q$ of difference operators on the circle in terms of the fermionic $\eta$-$\xi$ system. This realization admits a nontrivial Jordan block structure. We also ... More
Classical behavior in quantum systems: the case of straight tracks in a cloud chamberMay 10 2009The aim of this review is to discuss in a pedagogical way the problem of the emergence of a classical behavior in certain physical systems which, in principle, are correctly described by quantum mechanics. It is stressed that the limit $\hbar \to 0$ is ... More
On metric relative hyperbolicityOct 30 2012We show the equivalence of several characterizations of relative hyperbolicity for metric spaces, and obtain extra information about geodesics in a relatively hyperbolic space. We apply this to characterize hyperbolically embedded subgroups in terms of ... More
On the computation of the entropy in the microcanonical ensemble for mean-field-like systemsMar 28 2006Two recently proposed expressions for the computation of the entropy in the microcanonical ensemble are compared, and their equivalence is proved. These expressions are valid for a certain class of statistical mechanics systems, that can be called mean-field-like ... More
Multiple Peaks in the CMBJan 15 2002Recent measurements of the Cosmic Microwave Background Anisotropy have provided evidence for the presence of oscillations in the angular power spectrum. These oscillations are a wonderful confirmation of the standard cosmological scenario and allow us ... More
The existence of a minimum wavelength for photonsAug 25 2011The holographic property of entropy plays a key role in the thermodynamic description of gravitational field equations. It remains unclear, we argue, whether this property is necessarily interwoven with gravity itself or can be understood instead as a ... More
Gravity from the entropy of lightFeb 05 2010Jan 25 2011The holographic principle, considered in a semiclassical setting, is shown to have direct consequences on physics at a fundamental level. In particular, a certain relation is pointed out to be the expression of holography in basic thermodynamics. It is ... More
A stability result for Neumann problems in dimension $N \ge 3$May 08 2002We give a sufficient condition in dimension $N \ge 3$ in order to obtain the stability of a sequence of Neumann problems on fractured domains.
K-Theory, D-Branes and Ramond-Ramond FieldsDec 03 2008This thesis is dedicated to the study of K-theoretical properties of D-branes and Ramond-Ramond fields. We construct abelian groups which define a homology theory on the category of CW-complexes, and prove that this homology theory is equivalent to the ... More
Personality Traits and Echo Chambers on FacebookJun 15 2016In online social networks, users tend to select information that adhere to their system of beliefs and to form polarized groups of like minded people. Polarization as well as its effects on online social interactions have been extensively investigated. ... More
Minimal hyperspheres of arbitrarily large Morse indexApr 08 2015We show that the Morse index of a closed minimal hypersurface in a four-dimensional Riemannian manifold cannot be bound in terms of the volume and the topological invariants of the hypersurface itself by presenting a method for constructing Riemannian ... More
Two samples test for discrete power-law distributionsMar 02 2015Power-law distributions occur in wide variety of physical, biological, and social phenomena. In this paper, we propose a statistical hypothesis test based on the log-likelihood ratio to assess whether two samples of discrete data are drawn from the same ... More
Null-null components of the generalized Einstein tensor for Lovelock modelsMar 06 2015Jun 14 2016For spherical symmetry, we provide expressions for the radial null-null components of the generalized Einstein tensor $E_{ab}$ for Lovelock models for diagonal $E_{ab}$ in terms of the metric and of the radial null-null components of the Ricci tensor. ... More
D-instantons on orbifolds and gauge/gravity correspondenceJan 15 2002Jan 24 2002D-instantons are used to probe the near-horizon geometry of D3-branes systems on orbifold spaces. For fractional D3-branes, D-instanton calculus correctly reproduces the gauge beta-function and U(1)_R anomaly of the corresponding N=2 non-conformal Super ... More
Separable Functors and Formal SmoothnessJul 07 2004May 08 2007The natural problem we approach in the present paper is to show how the notion of formally smooth (co)algebra inside monoidal categories can substitute that of (co)separable (co)algebra in the study of splitting bialgebra homomorphisms. This is performed ... More
A Milnor-Moore Type Theorem for Primitively Generated Braided BialgebrasMar 04 2010A braided bialgebra is called primitively generated if it is generated as an algebra by its space of primitive elements. We prove that any primitively generated braided bialgebra is isomorphic to the universal enveloping algebra of its infinitesimal braided ... More
Green's function Monte Carlo calculations of the electromagnetic and neutral-weak response functions in the quasi-elastic sectorFeb 12 2016A quantitative understanding of neutrino-nucleus interactions is demanded to achieve precise measurement of neutrino oscillations, and hence the determination of their masses. In addition, next generation detectors will be able to detect supernovae neutrinos, ... More
Neutrino anomaliesApr 29 2003Solar and atmospheric evidences have been established and can be explained by neutrino masses. Furthermore, other experiments claim a few unconfirmed neutrino anomalies. We critically reanalyze the 0nu2beta, LSND and NuTeV anomalies.
Interpreting the LSND anomaly: sterile neutrinos or CPT-violation or...?Jan 15 2002Feb 20 2003We first study how sterile neutrinos can fit the 5sigma bar-nu_mu --> bar-nu_e LSND anomaly: 2+2 solutions are strongly disfavoured by solar and atmospheric data, while 3+1 solutions can still give a poor fit (for a specific range of oscillation parameters, ... More
Distinguishing gauge-mediated from unified-supergravity spectraMay 13 1997We show that gauge-mediation and unified-supergravity give sufficiently firm and different predictions for the spectrum of supersymmetric particles to make it possible to discriminate the two scenarios even if the messenger mass is close to the unification ... More
Smooth Projective Symmetric Varieties with Picard Number equal to oneFeb 12 2007Sep 26 2008We classify the smooth projective symmetric G-varieties with Picard number one (and G semisimple). Moreover we prove a criterion for the smoothness of the simple (normal) symmetric varieties whose closed orbit is complete. In particular we prove that, ... More
The Wishart short rate modelMar 25 2012May 07 2014We consider a short rate model, driven by a stochastic process on the cone of positive semidefinite matrices. We derive sufficient conditions ensuring that the model replicates normal, inverse or humped yield curves.
Quasi-convexity of hyperbolically embedded subgroupsOct 29 2013We show that any infinite order element $g$ of a virtually cyclic hyperbolically embedded subgroup of a group $G$ is Morse, that is to say any quasi-geodesic connecting points in the cyclic group $C$ generated by $g$ stays close to $C$. This answers a ... More
Laplacians and gauged Laplacians on a quantum Hopf bundleMar 29 2010This paper presents an analysis of the set of connections and covariant derivatives on a U(1) quantum Hopf bundle on the standard Podles sphere, whose total space quantum SU(2) is equipped with the 3d left covariant differential calculus by Woronowicz. ... More
Steinitz classes of tamely ramified nonabelian extensions of odd prime power orderJan 19 2010The Steinitz class of a number field extension K/k is an ideal class in the ring of integers O_k of k, which, together with the degree [K:k] of the extension determines the O_k-module structure of O_K. We call R_t(k,G) the classes which are Steinitz classes ... More
Neutron Stars, Supernova Explosions and the Transition to Quark MatterApr 09 1999The transition to quark matter can take place in neutron stars. The structure of a hybrid star, containing a core made of quark matter is discussed. The maximum mass of the non-rotating hybrid star turns out to be 1.6 M_s. Possible signatures of the quark ... More
Trends in Fast Feedback R&DJun 11 2008In this paper, starting from the basic description of the equation that governs the bunch motion and looking at the advances of the technology, three examples of feedback designs versus technology trend are presented and discussed. In particular the author ... More
The nematic phase of a system of long hard rods - ICMP12 talk, Aalborg, August 2012Sep 13 2012In this talk I consider a two-dimensional lattice model for liquid crystals consisting of long rods interacting via purely hard core interactions, with two allowed orientations defined by the underlying lattice. I report a rigorous proof of the existence ... More
Cohomology of groups in o-minimal structures: acyclicity of the infinitesimal subgroupNov 15 2007By recent work on some conjectures of Pillay, each definably compact group in a saturated o-minimal structure is an expansion of a compact Lie group by a torsion free normal divisible subgroup, called its infinitesimal subgroup. We show that the infinitesimal ... More
On the low-temperature phase of the three-state antiferromagnetic Potts model on the simple cubic latticeNov 25 1996The three-state antiferromagnetic Potts model on the simple cubic lattice is investigated using the cluster variation method in the cube and the star-cube approximations. The broken-sublattice-symmetry phase is found to be stable in the whole low-temperature ... More
Single-spin asymmetries and Qiu-Sterman effect(s)Nov 08 2005Nov 15 2005I discuss the relation between the Qiu-Sterman effects on one hand and the Collins, Sivers and Boer-Mulders effects on the other hand. It was suggested before that some of these effects are in fact the same, thus providing interesting connections between ... More