Results for "Giuseppe Vacca"

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Virtual Element Methods for hyperbolic problems on polygonal meshesFeb 18 2016In the present paper we develop the Virtual Element Method for hyperbolic problems on polygonal meshes, considering the linear wave equations as our model problem. After presenting the semi-discrete scheme, we derive the convergence estimates in H^1 semi-norm ... More
Virtual Element Method for Second Order Elliptic Eigenvalue ProblemsOct 12 2016Oct 13 2016We introduce the Virtual Element Method (VEM) for elliptic eigenvalue problems. The main result of the paper states that VEM provides an optimal order approximation of the eigenmodes. A wide set of numerical tests confirm the theoretical analysis.
Mass-varying neutrino in light of cosmic microwave background and weak lensingMay 28 2012Dec 05 2013We aim to constrain mass-varying neutrino models using large scale structure observations and produce forecast for the Euclid survey. We investigate two models with different scalar field potential and both positive and negative coupling parameters \beta. ... More
The nonconforming virtual element method for eigenvalue problemsFeb 08 2018We analyse the nonconforming Virtual Element Method (VEM) for the approximation of elliptic eigenvalue problems. The nonconforming VEM allow to treat in the same formulation the two- and three-dimensional case.We present two possible formulations of the ... More
Mildly mixed coupled models vs. WMAP7 dataJan 11 2011Mildly mixed coupled models include massive neutrinos and CDM--DE coupling. We present new tests of their likelihood vs. recent data including WMAP7, confirming it to exceed LCDM, although at ~2\sigma's. We then show the impact on the physics of the dark ... More
Mimetic Finite Difference methods for Hamiltonian wave equations in 2DMay 05 2015Aug 03 2016In this paper we consider the numerical solution of the Hamiltonian wave equation in two spatial dimension. We use the Mimetic Finite Difference (MFD) method to approximate the continuous problem combined with a symplectic integration in time to integrate ... More
Constraints on Dark Energy state equation with varying pivoting redshiftNov 30 2012Dec 20 2013We assume the DE state equations w(a) = w_0+w_a(a_p-a), and study the dependence of the constraints on w_0 and w_a coefficients on the pivoting redshift 1+z_p=1/a_p. Coefficients are fitted to data including WMAP7, SNIa (Union 2.1), BAO's (including WiggleZ ... More
Dark energy from dark radiation in strongly coupled cosmologies with no fine tuningJun 11 2012Aug 14 2012A dual component made of non-relativistic particles and a scalar field, exchanging energy, naturally falls onto an attractor solution, making them a (sub)dominant part of the cosmic energy during the radiation dominated era, provided that the constant ... More
Probing the rotation curve of the outer accretion disk in FU Orionis objects with long-wavelength spectroscopyJul 07 2003Studies of the Spectral Energy Distribution of Young Stellar Objects suggest that the outer disk of FU Orionis objects might be self-gravitating. In this paper we propose a method to test directly whether, in these objects, significant deviations from ... More
Tomographic weak lensing shear spectra from large N-body and hydrodynamical simulationsMar 23 2012May 11 2012Forthcoming experiments will enable us to determine tomographic shear spectra at a high precision level. Most predictions about them have until now been biased on algorithms yielding the expected linear and non-linear spectrum of density fluctuations. ... More
Dark Matter - Dark Energy coupling biasing parameter estimates from CMB dataApr 02 2008Nov 17 2008When CMB data are used to derive cosmological parameters, their very choice does matter: some parameter values can be biased if the parameter space does not cover the "true" model. This is a problem, because of the difficulty to parametrize Dark Energy ... More
Non-linear weak lensing forecastsFeb 18 2011Mar 17 2011We investigate the impact of non-linear corrections on dark energy parameter estimation from weak lensing probes. We find that using halofit expressions, suited to LCDM models, implies substantial discrepancies with respect to results directly obtained ... More
Jet Physics at TevatronJan 15 2004An overview of Run I jet physics at the ppbar Fermilab Tevatron Collider with a particular emphasis on inclusive jet cross section measurements is given. The impact of these studies on PDFs constrain from global fits is underlined. Preliminary results ... More
Topological defects, fractals and the structure of quantum field theoryJul 13 2008Aug 11 2008In this paper I discuss the formation of topological defects in quantum field theory and the relation between fractals and coherent states. The study of defect formation is particularly useful in the understanding of the same mathematical structure of ... More
Coherent states, fractals and brain wavesJun 02 2009I show that a functional representation of self-similarity (as the one occurring in fractals) is provided by squeezed coherent states. In this way, the dissipative model of brain is shown to account for the self-similarity in brain background activity ... More
Commutation relations for the electromagnetic field in the presence of dielectrics and conductorsFeb 26 2009We determine the commutation relations satisfied by the quantized electromagnetic field in the presence of macroscopic dielectrics and conductors, with arbitrary dispersive and dissipative properties. We consider in detail the case of two plane-parallel ... More
Accurate prediction of electroweak observables and impact on the Higgs mass boundJul 08 1998I discuss the importance of the $O(g^4 m_t^2/\mw^2)$ corrections to the effective electroweak angle and Mw in the indirect determination of the Higgs mass. I emphasize the r\^ole of a very precise Mw measurement on the Mh estimate.
QCD corrections to Higgs physics at the LHCSep 18 2006Sep 21 2006We summarize the status of QCD corrections for SM Higgs boson production at hadron colliders and briefly sketch the main search strategies at the LHC.
Deformation quantization on a Hilbert spaceJun 28 2004We study deformation quantization on an infinite-dimensional Hilbert space $W$ endowed with its canonical Poisson structure. The standard example of the Moyal star-product is made explicit and it is shown that it is well defined on a subalgebra of $C^\infty(W)$. ... More
Diffractive phenomenaNov 23 2001Nov 27 2001The most recent theoretical and experimental results in the field of diffractive scattering are reviewed. A parallel between the two current theoretical approaches to diffraction, the DIS picture in the Breit frame and the dipole picture in the target ... More
Wave-scattering from a gently curved surfaceJun 24 2016We study wave scattering from a gently curved surface. We show that the recursive relations, implied by shift invariance, among the coefficients of the perturbative series for the scattering amplitude allow to perform an infinite resummation of the perturbative ... More
Some remarks on a viscous regularization of the nonlinear diffusion equationMay 29 2015We illustrate an alternative derivation of the viscous regularization of the diffusion equation which was studied in [A. Novick-Cohen and R. L. Pego. {\em Trans. Amer. Math. Soc.}, 324:331--351]. We provide an alternative proof of existence of solutions, ... More
Seasonal Linear Predictivity in National Football ChampionshipsNov 19 2015Predicting the results of sport matches and competitions is an arising research field, benefiting from the growing amount of available data and the novel data analytics techniques. Excellent forecasts can be achieved by advanced machine learning methods ... More
The fractional Fisher information and the central limit theorem for stable lawsApr 27 2015A new information-theoretic approach to the central limit theorem for stable laws is presented. The main novelty is the concept of relative fractional Fisher information, which shares most of the properties of the classical one, included Blachman-Stam ... More
A blind method to detrend instrumental systematics in exoplanetary light-curvesMar 18 2015Jun 02 2015The study of the atmospheres of transiting exoplanets requires a photometric precision, and repeatability, of one part in $\sim 10^4$. This is beyond the original calibration plans of current observatories, hence the necessity to disentangle the instrumental ... More
Apparatus for measuring the thermal Casimir force at large distancesOct 16 2014Nov 12 2014We describe a Casimir apparatus based on a differential force measurement between a Au-coated sphere and a planar slab divided in two regions, one of which is made of high-resistivity (dielectric) Si, and the other of Au. The crucial feature of the setup ... More
The role of the top quark in the stability of the SM Higgs potentialMay 27 2014I discuss the stability of the SM scalar potential in view of the discovery of a Higgs boson with mass around 125 GeV. The role played by the top quark mass in the choice between the full stability and the metastability conditions is analyzed in detail. ... More
Wigner-Eckart theorem and Jordan-Schwinger representation for infinite-dimensional representations of the Lorentz groupSep 18 2015The Wigner-Eckart theorem is a well known result for tensor operators of SU(2) and, more generally, any compact Lie group. This paper generalises it to arbitrary Lie groups, possibly non-compact. The result relies on knowledge of recoupling theory between ... More
Metric projection for dynamic multiplex networksJan 08 2016Evolving multiplex networks are a powerful model for representing the dynamics along time of different phenomena, such as social networks, power grids, biological pathways. However, exploring the structure of the multiplex network time series is still ... More
Entropy inequalities for stable densities and strengthened central limit theoremsDec 18 2015We consider the central limit theorem for stable laws in the case of the standardized sum of independent and identically distributed random variables with regular probability density function. By showing decay of different entropy functionals along the ... More
On the isotropic-biaxial phase transition in nematic liquid crystalsNov 29 2015We apply a recently developed technique to determine adapted coordinates for the sixth degree Landau-deGennes potential, in which the potential is specially simple, to analyze the possibility of a direct transition between the fully symmetric state and ... More
Homotopy of posets, net-cohomology and superselection sectors in globally hyperbolic spacetimesDec 05 2004Aug 29 2005We study sharply localized sectors, known as sectors of DHR-type, of a net of local observables, in arbitrary globally hyperbolic spacetimes with dimension $\geq 3$. We show that these sectors define, has it happens in Minkowski space, a $\mathrm{C}^*-$category ... More
Group Theoretical Settling of Spin Zero Relativistic Particle TheoriesMar 07 2019In order to avoid the difficulties encountered by relativistic quantum theory of single particles, we pursue a deductive development of the theory from physical principles, without canonical quantization, by making use of group-theoretical methods. Our ... More
Arf good semigroupsOct 09 2017In this paper we study the property of the Arf good subsemigroups of $\mathbb{N}^n$, with $n\geq2$. We give a way to compute all the Arf semigroups with a given collection of multiplicity branches. We also deal with the problem of determining the Arf ... More
New results on Initial State and Quarkonia with ALICESep 13 2017The study of quarkonia in heavy-ion collisions has been the subject of intense experimental and theoretical effort, ever since their production was predicted to be sensitive to the formation of a deconfined state of strongly-interacting matter, known ... More
Self-improvement of the Bakry-Émery condition and Wasserstein contraction of the heat flow in RCD(K,\infty) metric measure spacesApr 02 2013May 17 2013We prove that the linear heat flow in a RCD(K,\infty) metric measure space (X,d,m) satisfies a contraction property with respect to every L^p-Kantorovich-Rubinstein-Wasserstein distance. In particular, we obtain a precise estimate for the optimal W_\infty-coupling ... More
A sharpened Strichartz inequality for the wave equationFeb 12 2018We disprove a conjecture of Foschi, regarding extremizers for the Strichartz inequality with data in the Sobolev space $\dot{H}^{1/2}\times\dot{H}^{-1/2}(\mathbb R^d)$, for even $d\ge 2$. On the other hand, we provide evidence to support the conjecture ... More
Johnson noise and the thermal Casimir effectMay 16 2007Jul 26 2007We study the thermal interaction between two nearby thin metallic wires, at finite temperature. It is shown that the Johnson currents in the wires give rise, via inductive coupling, to a repulsive force between them. This thermal interaction exhibits ... More
Bohr-van Leeuwen theorem and the thermal Casimir effect for conductorsMar 05 2009Apr 06 2009The problem of estimating the thermal corrections to Casimir and Casimir-Polder interactions in systems involving conducting plates has attracted considerable attention in the recent literature on dispersion forces. Alternative theoretical models, based ... More
Weak Homology of Bright Elliptical GalaxiesFeb 21 2003Studies of the Fundamental Plane of early-type galaxies, from small to intermediate redshifts, are often carried out under the guiding principle that the Fundamental Plane reflects the existence of an underlying mass-luminosity relation for such galaxies, ... More
Generic vanishing, gaussian maps, and Fourier-Mukai transformOct 02 2003Jul 04 2012In the first part of this paper we prove a vanishing criterion for higher direct images of projective families of line bundles on a Cohen-Macaulay variety X. The result involves certain first-order deformations of certain curves on X, and makes essential ... More
QCD coherence in the structure function and associated distributions at small $x$Dec 20 1994We recall the origin of angular ordering of soft parton emission in the region of small $x$ and show that this coherent structure can be detected in associated distributions. For structure functions at small $x$ and at fixed transverse momentum the angular ... More
QCD ReviewNov 09 2006This review is focused on QCD theoretical issues and their phenomenological relevance specially for LHC. It is incomplete and mostly neglects the phenomenology of long distance physics
On certain positive integer sequencesApr 30 2004A survey of recent results in elementary number theory is presented in this paper. Special attention is given to structure and asymptotic properties of certain families of positive integers.
Selected Items in Jet AlgorithmsAug 06 2008I provide a very brief overview of recent developments in jet algorithms, mostly focusing on the issue of infrared-safety.
Soft-gluon resummation for Higgs differential distributions at the Large Hadron ColliderOct 12 2007We study the transverse-momentum (q_T) and rapidity (y) distributions of the Higgs boson in perturbative QCD, including the most advanced theoretical information presently available: fixed-order perturbation theory at Next-to-Leading Order (NLO) in the ... More
Structure Functions and Large Q^2 Cross Sections at HERAJun 07 2000The data collected with the H1 and ZEUS detectors during the running period 1994-99 are used to give an experimental review on the proton structure functions and the neutral current and charged current large Q^2 cross sections in e^\pm p scattering at ... More
The necessity of wheels in universal quantization formulasAug 20 2013Sep 15 2013In the context of formal deformation quantization, we provide an elementary argument showing that any universal quantization formula necessarily involves graphs with wheels.
A Quantum Logic Gate Representation of Quantum Measurement: Reversing and Unifying the Two Steps of von Neumann's ModelDec 06 1999In former work, quantum computation has been shown to be a problem solving process essentially affected by both the reversible dynamics leading to the state before measurement, and the logical-mathematical constraints introduced by quantum measurement ... More
Surfaces of general type with p_g=q=0 having a pencil of hyperelliptic curves of genus 3Jul 12 2004We prove that the bicanonical map of a surfaces of general S type with p_g=q=0 is non birational if there exists a pencil on S whose general member is an hyperelliptic curve of genus 3.
The Hilbert function of bigraded algebras in $k[\mathbb{P}^1\times\mathbb{P}^1]$Sep 22 2016Sep 23 2016We classify the Hilbert functions of bigraded algebras in $k[x_1, x_2, y_1, y_2]$ introducing a numerical function called Ferrers function.
An exact relation between number of black box computations required to solve an oracle problem quantumly and quantum retrocausalityAug 03 2015Oct 22 2015We investigate the reason for the quantum speedup -- quantum algorithms requiring fewer computation steps than their classical counterparts. We extend their representation to the process of setting the problem. The initial measurement selects a setting ... More
An historical prolegomenon to the occurrence of the resonance dual models: the Watson-Sommerfeld transformMay 10 2015We would like to discuss, within the inherent historical context, upon one of the main works of fundamental physics which has led to the formulation of the early resonance dual models prior to string theory. In fact, we shall focus on certain aspects ... More
Simple and collective twisted symmetriesOct 29 2014After the introduction of $\lambda$-symmetries by Muriel and Romero, several other types of so called "twisted symmetries" have been considered in the literature (their name refers to the fact they are defined through a deformation of the familiar prolongation ... More
On the Dynamics of XY Spin Chains with ImpuritiesAug 27 2014Feb 06 2015We provide a theoretical set up for studying the dynamics in quantum spin chain models with inhomogeneous two-body interaction. We frame in our formalism models that can be mapped into a fermion system with a quadratic Hamiltonian. Local and global existence ... More
Degeneration of Hodge structures over Picard modular surfacesMar 20 2014We study variations of Hodge structures over a Picard modular surface, and compute the weights and types of their degenerations through the cusps of the Baily-Borel compactification. The main tool is a theorem of Burgos and Wildeshaus.
A probabilistic tour of visual attention and gaze shift computational modelsJul 05 2016In this paper a number of problems are considered which are related to the modelling of eye guidance under visual attention in a natural setting. From a crude discussion of a variety of available models spelled in probabilistic terms, it appears that ... More
Hide it to see it better: a robust setup to probe the thermal Casimir effectFeb 14 2014Jun 04 2014We describe a Casimir setup consisting of two aligned sinusoidally corrugated Ni surfaces, one of which is "hidden" by a thin opaque layer of gold with a flat exposed surface. The gold layer acts as a low-pass filter that allows for a clean observation ... More
Consequences of a Goedel's misjudgmentMar 10 2015Aug 07 2015The fundamental aim of the paper is to correct an harmful way to interpret a Goedel's erroneous remark at the Congress of Koenigsberg in 1930. Despite the Goedel's fault is rather venial, its misreading has produced and continues to produce dangerous ... More
A model for massless higher spin field interacting with a geometrical backgroundFeb 02 2015Feb 05 2015We study a very general four dimensional Field Theory model describing the dynamics of a massless higher spin $N$ symmetric tensor field particle interacting with a geometrical background.This model is invariant under the action of an extended linear ... More
On the properties of Circular-BeamsJan 28 2015Apr 07 2015Circular-Beams were introduced as a very general solution of the paraxial wave equation carrying Orbital Angular Momentum. Here we study their properties, by looking at their normalization and their expansion in terms of Laguerre-Gauss modes. We also ... More
Least quartic Regression Criterion with Application to FinanceMar 17 2014This article proposes a new method for the estimation of the parameters of a simple linear regression model which accounts for the role of co-moments in non-Gaussian distributions being based on the minimization of a quartic loss function. Although the ... More
On the classification of surfaces of general type with non-birational bicanonical map and Du Val Double planesDec 18 2003Jan 05 2004We classify surfaces of general type whose bicanonical map is composed with a rational map of degree 2 onto a rational or ruled surface.
An integration of Euler's pentagonal partitionSep 19 2010A recurrent formula is presented, for the enumeration of the compositions of positive integers as sums over multisets of positive integers, that closely resembles Euler's recurrence based on the pentagonal numbers, but where the coefficients result from ... More
Evolution models for mass transportation problemsApr 07 2012We present a survey on several mass transportation problems, in which a given mass dynamically moves from an initial configuration to a final one. The approach we consider is the one introduced by Benamou and Brenier in [5], where a suitable cost functional ... More
Arf good semigroups with fixed genusFeb 07 2018In this paper we give an algorithm for the computation of all the Arf numerical semigroups with a given genus. Moreover, we generalize the concept of genus of a numerical semigroup to good semigroups of $\mathbb{N}^r$ and we give a procedure to calculate ... More
Arf good semigroups with fixed conductorFeb 02 2018In this paper we present a new algorithm to calculate the set of Arf numerical semigroups with given conductor. Moreover, we extend the previous problem to the class of good semigroups, presenting procedures to compute the set of the Arf good semigroups ... More
Inverse mean curvature flow in complex hyperbolic spaceOct 06 2016Mar 27 2018We consider the evolution by inverse mean curvature flow of a closed, mean convex and star-shaped hypersurface in the complex hyperbolic space. We prove that the flow is defined for any positive time, the evolving hypersurface stays star-shaped and mean ... More
Well-posedness for a class of nonlinear degenerate parabolic equationsSep 18 2015In this paper we obtain well-posedness for a class of semilinear weakly degenerate reaction-diffusion systems with Robin boundary conditions. This result is obtained through a Gagliardo-Nirenberg interpolation inequality and some embedding results for ... More
Heat equation and the sharp Young's inequalityApr 10 2012Apr 11 2012We show that the sharp Young's inequality for convolutions first obtained by Bechner and Brascamp-Lieb can be derived from the monotone in time evolution of a Lyapunov functional of the convolution of two solutions to the heat equation, with different ... More
The Unusual Object IC 2144/MWC 778Sep 24 2008IC 2144 is a small reflection nebula located in the zone of avoidance near the Galactic anticenter. It has been investigated here largely on the basis of Keck/HIRES optical spectroscopy (R ~ 48,000) and a SpeX spectrogram in the near-IR (R = 2000) obtained ... More
Accounting for both electron--lattice and electron--electron coupling in conjugated polymers: minimum total energy calculations on the Hubbard--Peierls hamiltonianDec 14 1993Minimum total energy calculations, which account for both electron--lattice and electron--electron interactions in conjugated polymers are performed for chains with up to eight carbon atoms. These calculations are motivated in part by recent experimental ... More
Gauged Supergravities and the Physics of Extra DimensionsOct 08 2012This thesis analyses gauged supergravities in various dimensions and their possible origin from compactifications of string theory. In the effective description the fluxes appear in the theory as deformation parameters generating a potential for the scalar ... More
Measuring test mass acceleration noise in space-based gravitational wave astronomySep 29 2014The basic constituent of interferometric gravitational wave detectors -- the test mass to test mass interferometric link -- behaves as a differential dynamometer measuring effective differential forces, comprising an integrated measure of gravity curvature, ... More
On the conversion of neutron stars into quark starsDec 04 2013The possible existence of two families of compact stars, neutron stars and quark stars, naturally leads to a scenario in which a conversion process between the two stellar objects occurs with a consequent release of energy of the order of $10^{53}$ erg. ... More
Isolelectronic apparatus to probe the thermal Casimir forceMar 16 2015Isoelectronic differential force measurements provide a unique opportunity to probe controversial features of the thermal Casimir effect, that are still much debated in the current literature. Isolectronic setups offer two major advantages over conventional ... More
Group theoretical foundations of the Quantum Theory of an interacting particleNov 15 2014Oct 20 2016{We point out some obstacles raised by the lost of symmetry against the extension to the case of an interacting particle of the approach that {\sl deductively} establishes the Quantum Theory of a free particle according to the group theoretical methods ... More
The early historical roots of Lee-Yang theoremOct 21 2014Nov 02 2014A deep and detailed historiographical analysis of a particular case study concerning the so-called Lee-Yang theorem of theoretical statistical mechanics of phase transitions, has emphasized what real historical roots underlie such a case study. To be ... More
Advanced statistical methods for eye movement analysis and modeling: a gentle introductionJun 23 2015Dec 27 2015In this Chapter we show that by considering eye movements, and in particular, the resulting sequence of gaze shifts, a stochastic process, a wide variety of tools become available for analyses and modelling beyond conventional statistical methods. Such ... More
Confidence intervals for the encircled energy fraction and the half energy widthMay 27 2015Sep 12 2015The Encircled Energy Fraction and its quantiles, notably the Half Energy Width, are routinely used to characterize the quality of X-ray optical systems. They are however always quoted without a statistical error. We show how non-parametric statistical ... More
On the Doppler effect for photons in rotating systemsFeb 02 2015The analysis of the Doppler effect for photons in rotating systems, studied using the M\"ossbauer effect, confirms the general conclusions of a previous paper dedicated to experiments with photons emitted/absorbed by atoms/nuclei in inertial flight. The ... More
Conservation laws and laser cooling of atomsFeb 01 2015Apr 24 2015The straightforward application of energy and linear momentum conservation to the absorption/emission of photons by atoms allows to establish the essential features of laser cooling of two levels atoms at low laser intensities. The lowest attainable average ... More
Symmetry and Lie-Frobenius reduction of differential equationsOct 29 2014Twisted symmetries, widely studied in the last decade, proved to be as effective as standard ones in the analysis and reduction of nonlinear equations. We explain this effectiveness in terms of a Lie-Frobenius reduction; this requires to focus not just ... More
Non-compact groups, tensor operators and applications to quantum gravitySep 25 2016This work focuses on non-compact groups and their applications to quantum gravity, mainly through the use of tensor operators. First, the mathematical theory of tensor operators for a Lie group is recast in a new way which is used to generalise the Wigner-Eckart ... More
Bound States of Majorana Fermions in Semi-classical ApproximationAug 24 2015We derive a semi-classical formula for computing the spectrum of bound states made of Majorana fermions in a generic non-integrable 2d quantum field theory with a set of degenerate vacua. We illustrate the application of the formula in a series of cases, ... More
Pathways of History of Elementary Particle PhysicsFeb 01 2014In this first paper, we briefly retrace some historical pathways of modern physics of 20th Century. In particular, we have considered some moments of cosmic ray physics and, above all, the early theoretical and experimental bases which will lead to the ... More
Rényi entropies and nonlinear diffusion equationsJan 17 2014Since their introduction in the early sixties, the R\'enyi entropies have been used in many contexts, ranging from information theory to astrophysics, turbulence phenomena and others. In this note, we enlighten the main connections between R\'enyi entropies ... More
Inverse mean curvature flow in complex hyperbolic spaceOct 06 2016We consider the evolution by inverse mean curvature flow of a closed, mean convex and star-shaped hypersurface in the complex hyperbolic space. We prove that the flow is defined for any positive time, the evolving hypersurface stays star-shaped and mean ... More
Exact Casimir interaction of perfectly conducting three-spheres in four euclidean dimensionsJul 11 2016Exploiting conformal symmetry, we derive a simple exact formula for the classical electromagnetic Casimir interaction of two perfectly conducting three-spheres, including the sphere-plate geometry as a special case, in four euclidean dimensions. We verify ... More
Complete off-shell effects for top-antitop + jet production with leptonic decays at the LHCJun 30 2016A brief summary of the calculation of the NLO QCD corrections to the process pp -> e+ ve mu- v_mu bb~ j + X is reported. This provides a complete description of the process of t-tbar + jet production with leptonic decays beyond the narrow-width approximation. ... More
Numerical functors on Voevodsky's motivesMar 17 2016We study mixed versions of the classical quotient functor from Chow motives to numerical motives. We compare two natural definitions, which turn out to be very different. We investigate fullness, conservativity and exactness of these two functors.
On simultaneous binary expansions of $n$ and $n^2$Feb 27 2004Mar 02 2004A new family of sequences is proposed. An example of sequence of this family is more accurately studied. This sequence is composed by the integers $n$ for which the sum of binary digits is equal to the sum of binary digits of $n^2$. Some structure and ... More
The fine structure constant and numerical alchemySep 09 2010We comment on past and more recent efforts to derive a formula yielding the fine structure constant in terms of integers and transcendent numbers. We analyse these "exoteric" attitudes and describe the myths regarding {\alpha}, which seems to have very ... More
Twisted symmetries of differential equationsFeb 07 2010We review the basic ideas lying at the foundation of the recently developed theory of twisted symmetries of differential equations, and some of its developments.
The Poincare'-Nekhoroshev mapJun 29 2002Sep 05 2003We study a generalization of the familiar Poincar\'e map, first implicitely introduced by N.N. Nekhoroshev in his study of persistence of invariant tori in hamiltonian systems, and discuss some of its properties and applications. In particular, we apply ... More
Twistor Spaces, Mirror Symmetry and Self-dual Kahler ManifoldsDec 02 2005We present the evidence for two conjectures related to the twistor string. The first conjecture states that two super-Calabi Yaus -- the supertwistor space and the superambitwistor space -- form a mirror pair. The second conjecture is that the B-model ... More
A generalized Kramers-Kronig transform for Casimir effect computationsFeb 12 2010May 11 2010Recent advances in experimental techniques now permit to measure the Casimir force with unprecedented precision. In order to achieve a comparable precision in the theoretical prediction of the force, it is necessary to accurately determine the electric ... More
Comment on " Low-frequency character of the Casimir force between metallic films"Mar 01 2006In Phys. Rev. {\bf E 70}, 047102 (2004), J.R. Torgerson and S.K. Lamoreaux investigated for the first time the real-frequency spectrum of finite temperature correction to the Casimir force, for metallic plates of finite conductivity. The very interesting ... More
A theory of electromagnetic fluctuations for metallic surfaces and van der Waals interactions between metallic bodiesNov 28 2005Apr 21 2006A new general expression is derived for the fluctuating electromagnetic field outside a metal surface, in terms of its surface impedance. It provides a generalization to real metals of Lifshitz theory of molecular interactions between dielectric solids. ... More
The Rise and Fall of Satellites in Galaxy ClustersNov 11 1996Feb 23 1998We use N-body simulations to study the infall of dark matter haloes onto rich clusters of galaxies. After identification of all cluster progenitors in the simulations, we select those haloes which accrete directly onto the main cluster progenitor. We ... More