Results for "Antonios Varvitsiotis"

total 7145took 0.13s
Minimum Dimension of a Hilbert Space Needed to Generate a Quantum CorrelationJul 01 2015Oct 25 2016Consider a two-party correlation that can be generated by performing local measurements on a bipartite quantum system. A question of fundamental importance is to understand how many resources, which we quantify by the dimension of the underlying quantum ... More
Computing the Grothendieck constant of some graph classesJun 10 2011Given a graph $G=([n],E)$ and $w\in\R^E$, consider the integer program ${\max}_{x\in \{\pm 1\}^n} \sum_{ij \in E} w_{ij}x_ix_j$ and its canonical semidefinite programming relaxation ${\max} \sum_{ij \in E} w_{ij}v_i^Tv_j$, where the maximum is taken over ... More
A new graph parameter related to bounded rank positive semidefinite matrix completionsApr 03 2012The Gram dimension $\gd(G)$ of a graph $G$ is the smallest integer $k\ge 1$ such that any partial real symmetric matrix, whose entries are specified on the diagonal and at the off-diagonal positions corresponding to edges of $G$, can be completed to a ... More
The Gram dimension of a graphDec 27 2011Apr 03 2012The Gram dimension $\gd(G)$ of a graph is the smallest integer $k \ge 1$ such that, for every assignment of unit vectors to the nodes of the graph, there exists another assignment of unit vectors lying in $\oR^k$, having the same inner products on the ... More
Linear conic formulations for two-party correlations and values of nonlocal gamesJun 24 2015Aug 30 2016In this work we study the sets of two-party correlations generated from a Bell scenario involving two spatially separated systems with respect to various physical models. We show that the sets of classical, quantum, no-signaling and unrestricted correlations ... More
Correlation matrices, Clifford algebras, and completely positive semidefinite rankFeb 21 2017Sep 28 2018We introduce a notion of matrix valued Gram decompositions for correlation matrices whose study is motivated by quantum information theory. We show that for extremal correlations, the matrices in such a factorization generate a Clifford algebra and thus, ... More
On the minimum dimension of a Hilbert space needed to generate a quantum correlationJul 01 2015Oct 07 2015Consider a two-party correlation that can be generated by performing local measurements on a bipartite quantum system. A question of fundamental importance is to understand how many resources, which we quantify by the dimension of the underlying quantum ... More
Device-independent dimension tests in the prepare-and-measure scenarioJun 13 2016Analyzing the dimension of an unknown quantum system in a device-independent manner, i.e., using only the measurement statistics, is a fundamental task in quantum physics and quantum information theory. In this paper, we consider this problem in the prepare-and-measure ... More
Structure of the set of quantum correlators via semidefinite programmingSep 28 2018Quantum information leverages properties of quantum behaviors in order to perform useful tasks such as secure communication and randomness certification. Nevertheless, not much is known about the intricate geometric features of the set quantum behaviors. ... More
Forbidden minor characterizations for low-rank optimal solutions to semidefinite programs over the elliptopeMay 09 2012Jan 09 2014We study a new geometric graph parameter $\egd(G)$, defined as the smallest integer $r\ge 1$ for which any partial symmetric matrix which is completable to a correlation matrix and whose entries are specified at the positions of the edges of $G$, can ... More
Device-independent dimension tests in the prepare-and-measure scenarioJun 13 2016Oct 25 2016Analyzing the dimension of an unknown quantum system in a device-independent manner, i.e., using only the measurement statistics, is a fundamental task in quantum physics and quantum information theory. In this paper, we consider this problem in the prepare-and-measure ... More
Deciding the existence of perfect entangled strategies for nonlocal gamesJun 24 2015First, we consider the problem of deciding whether a nonlocal game admits a perfect entangled strategy that uses projective measurements on a maximally entangled shared state. Via a polynomial-time Karp reduction, we show that independent set games are ... More
Complexity of the positive semidefinite matrix completion problem with a rank constraintMar 29 2012Sep 18 2012We consider the decision problem asking whether a partial rational symmetric matrix with an all-ones diagonal can be completed to a full positive semidefinite matrix of rank at most $k$. We show that this problem is $\NP$-hard for any fixed integer $k\ge ... More
Completely positive semidefinite rankApr 25 2016An $n\times n$ matrix $X$ is called completely positive semidefinite (cpsd) if there exist $d\times d$ Hermitian positive semidefinite matrices $\{P_i\}_{i=1}^n$ (for some $d\ge 1$) such that $X_{ij}= {\rm Tr}(P_iP_j),$ for all $i,j \in \{ 1, \ldots, ... More
Algebraic methods for counting Euclidean embeddings of rigid graphsJun 08 2009Aug 27 2009The study of (minimally) rigid graphs is motivated by numerous applications, mostly in robotics and bioinformatics. A major open problem concerns the number of embeddings of such graphs, up to rigid motions, in Euclidean space. We capture embeddability ... More
The excluded minors for isometric realizability in the planeNov 25 2015Sep 16 2016Let $G$ be a graph and $p \in [1, \infty]$. The parameter $f_p(G)$ is the least integer $k$ such that for all $m$ and all vectors $(r_v)_{v \in V(G)} \subseteq \mathbb{R}^m$, there exist vectors $(q_v)_{v \in V(G)} \subseteq \mathbb{R}^k$ satisfying $$\|r_v-r_w\|_p=\|q_v-q_w\|_p, ... More
Analysis of Optimization Algorithms via Sum-of-SquaresJun 11 2019In this work, we introduce a new framework for unifying and systematizing the performance analysis of first-order black-box optimization algorithms for unconstrained convex minimization over finite-dimensional Euclidean spaces. The low-cost iteration ... More
Graph Homomorphisms via Vector ColoringsOct 31 2016Jun 27 2017A vector $t$-coloring of a graph $G$ is an assignment of unit vectors $i\mapsto p_i$ to its vertices such that $\langle p_i, p_j\rangle\le -1/(t-1),$ for all $i\sim j$. The vector chromatic number of $G$, denoted by $\chi_v(G)$, is the smallest real number ... More
Quantum and non-signalling graph isomorphismsNov 29 2016We introduce a two-player nonlocal game, called the $(G,H)$-isomorphism game, where classical players can win with certainty if and only if the graphs $G$ and $H$ are isomorphic. We then define the notions of quantum and non-signalling isomorphism, by ... More
Vector Coloring the Categorical Product of GraphsJan 24 2018A vector $t$-coloring of a graph is an assignment of real vectors $p_1, \ldots, p_n$ to its vertices such that $p_i^Tp_i = t-1$ for all $i=1, \ldots, n$ and $p_i^Tp_j \le -1$ whenever $i$ and $j$ are adjacent. The vector chromatic number of $G$ is the ... More
Universal completability, least eigenvalue frameworks, and vector coloringsDec 15 2015An embedding $i \mapsto p_i\in \mathbb{R}^d$ of the vertices of a graph $G$ is called universally completable if the following holds: For any other embedding $i\mapsto q_i~\in \mathbb{R}^{k}$ satisfying $q_i^T q_j = p_i^T p_j$ for $i = j$ and $i$ adjacent ... More
Characterising the correlations of prepare-and-measure quantum networksMar 13 2018Aug 19 2018Prepare-and-measure (P&M) quantum networks are the basic building blocks of quantum communication and cryptography. These networks crucially rely on non-orthogonal quantum encodings to distribute quantum correlations, thus enabling superior communication ... More
Graph Homomorphisms via Vector ColoringsOct 31 2016A vector $t$-coloring of a graph $G$ is an assignment of unit vectors $i\mapsto p_i$ to its vertices such that $\langle p_i, p_j\rangle\le -1/(t-1),$ for all $i\sim j$. The vector chromatic number of $G$, denoted by $\chi_v(G)$, is the smallest real number ... More
Quantum and non-signalling graph isomorphismsNov 29 2016Jun 01 2017We introduce a two-player nonlocal game, called the $(G,H)$-isomorphism game, where classical players can win with certainty if and only if the graphs $G$ and $H$ are isomorphic. We then define the notions of quantum and non-signalling isomorphism, by ... More
Robust self-testing of quantum systems via noncontextuality inequalitiesDec 18 2018Dec 20 2018Self-testing unknown quantum states and measurements is a fundamental problem in quantum information processing. Here, we introduce an approach for studying this problem via the use of noncontextuality inequalities. We show that the celebrated Klyachko-Can-Binicio\ifmmode ... More
Graph Homomorphisms via Vector ColoringsOct 31 2016Mar 28 2019In this paper we study the existence of homomorphisms $G\to H$ using semidefinite programming. Specifically, we use the vector chromatic number of a graph, defined as the smallest real number $t \ge 2$ for which there exists an assignment of unit vectors ... More
Positive Semidefinite Matrix Completion, Universal Rigidity and the Strong Arnold PropertyJan 28 2013This paper addresses the following three topics: positive semidefinite (psd) matrix completions, universal rigidity of frameworks, and the Strong Arnold Property (SAP). We show some strong connections among these topics, using semidefinite programming ... More
Cosmic $ΔB$ from Lepton Violating Interactions at the Electroweak Phase TransitionJun 05 1992We propose a new mechanism for late cosmological baryon asymmetry in models with first order electroweak phase transition. Lepton asymmetry arises through the decay of particles produced out of equilbrium in bubble collisions and is converted into baryon ... More
Existence and convexity of solutions of the fractional heat equationJun 01 2016Aug 22 2017We prove that the initial-value problem for the fractional heat equation admits a solution provided that the (possibly unbounded) initial datum has a conveniently moderate growth at infinity. Under the same growth condition we also prove that the solution ... More
The QCD potential at O(1/m^2): Complete spin-dependent and spin-independent resultSep 12 2000Apr 11 2001Within an effective field theory framework, we obtain an expression, with O(1/m^2) accuracy, for the energies of the gluonic excitations between heavy quarks, which holds beyond perturbation theory. For the singlet heavy quark--antiquark energy, in particular, ... More
Sign-changing solutions of the fractional heat equation: existence and convexityJun 01 2016We prove that the initial-value problem for the fractional heat equation admits a solution provided that the (possibly unbounded) initial datum has a conveniently moderate growth at infinity. Under the same growth condition we also prove that the solution ... More
Factorisation of two-variable p-adic L-functionsApr 28 2013Let $f$ be a modular form which is non-ordinary at $p$. Kim and Loeffler have recently constructed two-variable $p$-adic $L$-functions associated to $f$. In the case where $a_p=0$, they showed that, as in the one-variable case, Pollack's plus and minus ... More
Critical phenomena of thick branes in warped spacetimesNov 22 2001Apr 15 2002We have investigated the effects of a generic bulk first-order phase transition on thick Minkowski branes in warped geometries. As occurs in Euclidean space, when the system is brought near the phase transition an interface separating two ordered phases ... More
Integral identities for 3d dualities with SP(2N) gauge groupsSep 07 2015Sep 13 2015In this note we study the reduction of 4d Seiberg duality to 3d for SP(2N) SQCD with an adjoint field. We follow a general prescription that consists in compactifying the dual 4d theories on the circle. This generates an effective 3d duality. The pure ... More
Optimization in the Loop: Implementing and Testing Scheduling Algorithms with SimuLTESep 11 2015One of the main purposes of discrete event simulators such as OMNeT++ is to test new algorithms or protocols in realistic environments. These often need to be benchmarked against optimal/theoretical results obtained by running commercial optimization ... More
3-flavor and 4-flavor implications of the latest T2K and NO$ν$A electron (anti-)neutrino appearance resultsSep 10 2015Mar 22 2016The two long-baseline experiments T2K and NO$\nu$A have recently presented new findings. T2K has shown the first $\bar \nu_e$ appearance data while NO$\nu$A has released the first $\nu_e$ appearance results. These data are of particular importance because ... More
Many body quantum physics in XANES of highly correlated materials, mixed valence oxides and high temperature superconductorsMay 22 2016The x-ray absorption near edge structure (XANES), developed in these last 40 years using synchrotron radiation, is a unique tool probing electronic correlations in complex systems via quantum many body final state effects. Multi electron excitations have ... More
An elementary introduction to the Holographic PrincipleJun 03 2005In this work we review at an elementary level the origin, main ideas and present status of the so called holographic principle. This principle, even in the absence of a precise formulation, is seen by many people as a major clue for the understanding ... More
Light neutral mesons production in p-A collisions at $\sqrt{s} = 27.5$ GeV with the NA60 ExperimentDec 31 2011The NA60 experiment has studied low-mass muon pair production in proton-nucleus (p-A) collisions with a system of Be, Cu, In, W, Pb and U targets using a 400 GeV/$c$ proton beam at the CERN SPS. Thanks to the collected data sample of 180\,000 low mass ... More
Aspects of particle mixing in Quantum Field TheoryAug 30 2004Sep 06 2004The results obtained on the particle mixing in Quantum Field Theory are reviewed. The Quantum Field Theoretical formulation of fermion and boson mixed fields is analyzed in detail and new oscillation formulas exhibiting corrections with respect to the ... More
New results on inclusive quarkonium decaysMay 13 2002I review some recent progress, leading to a substantial reduction in the number of non-perturbative parameters, in the calculation of inclusive quarkonium decay widths in the framework of non-relativistic effective field theories.
Scalar perturbations in DGP braneworld cosmologyMay 16 2008We solve for the behaviour of cosmological perturbations in the Dvali-Gabadadze-Porrati (DGP) braneworld model using a new numerical method. Unlike some other approaches in the literature, our method uses no approximations other than linear theory and ... More
Superstripes in the Low Energy Physics of Complex Quantum Matter at the MesoscaleMar 10 2015Mar 12 2015Quantum physics in the 20th century was proposed to understand the phenomenology of atomic world at short length scale (below one nanometer) and it was developed to study nuclear and subnuclear world at the lowest possible spatial scale and at the highest ... More
On the Beauville form of the known irreducible symplectic varietiesJun 16 2006We study the global geometry of the ten dimensional O'Grady irreducible symplectic variety. We determine its second Betti number, its Beauville form and its Fujiki constant.
A real viewpoint on the intersection of complex quadrics and its topologyJun 09 2011We study the relation between a complex projective set C in CP^n and the set R in RP^(2n+1) defined by viewing each equation of C as a pair of real equations. Once C is presented by quadratic equations, we can apply a spectral sequence to efficiently ... More
More about Electroweak Baryogenesis in the Minimal Supersymmetric Standard ModelSep 08 1997We compute the baryon asymmetry generated at the electroweak phase transition by the Higgs scalar sector of the minimal supersymmetric standard model. Because of large enhancement effects from low momentum modes, Higgs particles may be responsible for ... More
Towards a Nonequilibrium Quantum Field Theory Approach to Electroweak BaryogenesisOct 11 1995We propose a general method to compute $CP$-violating observables from extensions of the standard model in the context of electroweak baryogenesis. It is alternative to the one recently developed by Huet and Nelson and relies on a nonequilibrium quantum ... More
Radiative transitions and the quarkonium magnetic momentAug 30 2006I discuss heavy quarkonium radiative transitions and the related issue of the quarkonium magnetic moment inside effective field theories. Differences in set up and conclusions with respect to typical phenomenological approaches are outlined.
The heavy quark potential in pNRQCDSep 20 1999The heavy quarkonium static potential is discussed within the framework of potential NRQCD. Some quantitative statements are made in the kinematical situation $mv >> \Lambda_{\rm QCD}$ at the level of accuracy of the next-to-leading order in the multipole ... More
The Barbieri-Remiddi solution of the bound state problem in QEDJul 22 1998We derive the so-called Barbieri-Remiddi solution of the Bethe-Salpeter equation in QED in its general form and discuss its application to the bound state energy spectrum.
The quark-antiquark Wilson loop formalism in the NRQCD power counting schemeSep 02 1998The quark-antiquark interaction from the NRQCD Lagrangian is studied in the Wilson loop formalism.
Singular integrals and maximal functions: the disk multiplier revisitedOct 23 2013Dec 18 2013Several estimates for singular integrals, maximal functions and the spherical summation operator are given in the spaces $L^p_{\text{rad}}L^2_{\text{ang}}(\mathbb{R}^n)$, $n\geq 2$.
Testing the very-short-baseline neutrino anomalies at the solar sectorMay 09 2011Jun 07 2011Motivated by the accumulating hints of new sterile neutrino species at the eV scale, we explore the consequences of such an hypothesis on the solar sector phenomenology. After introducing the theoretical formalism needed to describe the MSW conversion ... More
Um Erro Com Um SeculoOct 03 2008The "rigid bodies" must be in Relativity the "deformable bodies" where the longitudinal waves propagate with the maximun speed $c$. In 1909, Born studied the "relativistic underformable body" but made the mistake of calling it "rigid". The "rigid body" ... More
A theoretical review of heavy quarkonium inclusive decaysNov 24 2003Jan 22 2004In this brief review, I summarize the current theoretical knowledge of heavy quarkonium inclusive decays, with emphasis on recent progress made in the framework of QCD effective field theories. In appendix, I list the imaginary parts of the matching coefficients ... More
New universal attractor in nonmininally coupled gravity: Linear inflationJan 26 2018Jul 17 2018Once quantum corrections are taken into account, the strong coupling limit of the $\xi$-attractor models (in metric gravity) might depart from the usual Starobinsky solution and move into linear inflation. Furthermore, it is well known that the metric ... More
The CUORE experiment at the LNGSApr 28 2017May 09 2017CUORE is the first ton-scale experiment based on the bolometric technique to search for neutrinoless double-beta decay. Its core is made of 988 $\mathrm{TeO_{2}}$ crystals cooled down to $10~\mathrm{mK}$. The temperature must be as stable as possible ... More
Mean pt scaling with m/nq at the LHC: Absence of (hydro) flow in small systems?Jun 01 2015Aug 28 2015In this work, a study of the average transverse momentum (pt) as a function of the mid-rapidity charged hadron multiplicity (Nch) and hadron mass (m) in p-Pb and Pb-Pb collisions at LHC energies is presented. For the events producing low Nch, the average ... More
Nested-set inconsistencyApr 26 2010Jan 25 2012This paper examines a denumerable version of the nested-set theorem and derives from it a contradiction involving the formal consistency of the actual infinity assumed by the Axiom of Infinity.
Living beings as informed systems: towards a physical theory of informationSep 19 2006I propose here a new concept of information based on two relevant aspects of its expression. The first related to the undeniable fact that the expression of information modifies the physical state of its receiver. The second to the arbitrariness of such ... More
Light flavor results in p-Pb collisions with ALICEDec 22 2015Particle ratios provide insight into the hadrochemistry of the event and the mechanisms for particle production. In Pb-Pb collisions the relative multi-strange baryon yields exhibit an enhancement with respect to pp collisions, whereas the short-lived ... More
Strong Sector in non-minimal SUSY modelNov 26 2016We investigate the squark sector of a supersymmetric theory with an extended Higgs sector. We give the mass matrices of stop and sbottom, comparing the Minimal Supersymmetric Standard Model (MSSM) case and the non-minimal case. We discuss the impact of ... More
Weakly countably determined spaces of high complexityMar 04 2009We prove that there exist weakly countably determined spaces of complexity higher than coanalytic. On the other hand, we also show that coanalytic sets can be characterized by the existence of a cofinal adequate family of closed sets. Therefore the Banach ... More
Automatic norm continuity of weak* homeomorphismsMar 01 2009We prove that in a certain class E of nonseparable Banach spaces the norm topology of the dual ball is definable in terms of its weak* topology. Thus, any weak* homeomorphism between duals balls of spaces in E is automatically norm-continuous.
Coleman Maps for Modular Forms at Supersingular Primes over Lubin-Tate ExtensionsAug 01 2009Jul 12 2010Given an elliptic curve with supersingular reduction at an odd prime p, Iovita and Pollack have generalised results of Kobayashi to define even and odd Coleman maps at p over Lubin-Tate extensions given by a formal group of height 1. We generalise this ... More
Unipotent representations of Lie incidence geometriesJul 25 2013If a geometry $\Gamma$ is isomorphic to the residue of a point $A$ of a shadow geometry of a spherical building $\Delta$, a representation $\varepsilon_\Delta^A$ of $\Gamma$ can be given in the unipotent radical $U_{A^*}$ of the stabilizer in $\mathrm{Aut}(\Delta)$ ... More
Countable products of spaces of finite setsFeb 28 2009We consider the compact spaces sigma_n(I) of subsets of an uncountable set I of cardinality at most n and their countable products. We give a complete classification of their Banach spaces of continuous functions and a partial topological classification. ... More
Implementation of functions in R tool in parallel environmentMay 08 2019Drug promiscuity and polypharmacology are much discussed topics in pharmaceutical research. Drug repositioning applies established drugs to new disease indications with increasing success. As polypharmacology, defined a drug's ability to bind to several ... More
Fundamentals of the Holomorphic Embedding Load-Flow MethodSep 08 2015The Holomorphic Embedding Load-Flow Method (HELM) was recently introduced as a novel technique to constructively solve the power-flow equations in power grids, based on advanced complex analysis. In this paper, the theoretical foundations of the method ... More
Height estimates for constant mean curvature graphs in $\mathrm{Nil}_3$ and $\widetilde{PSL}_2(\mathbb{R})$Mar 18 2018Mar 18 2019In this paper we obtain height estimates for compact, constant mean curvature vertical graphs in the homogeneous spaces $\mathrm{Nil}_3$ and $\widetilde{PSL}_2(\mathbb{R})$. As a straightforward consequence, we announce a structure-type result for proper ... More
A Delaunay-type classification result for prescribed mean curvature surfaces in $\mathbb{M}^2(κ)\times\mathbb{R}$Jul 26 2018May 15 2019The purpose of this paper is to study immersed surfaces in the product spaces $\mathbb{M}^2(\kappa)\times\mathbb{R}$, whose mean curvature is given as a $C^1$ function depending on their angle function. This class of surfaces extends widely, among others, ... More
On the Existence of Absolutely Maximally Entangled States of Minimal Support IIJun 30 2018Absolutely maximally entangled, AME, states are pure multipartite states that give rise to the maximally mixed states when half or more of the parties are traced out. AME states find applications in fields like teleportation or quantum secret sharing, ... More
Total and geometric phases, Majorana and Dirac neutrinosApr 11 2019The analysis of the total and geometric phases generated by the neutrino oscillation shows that these phases for Majorana neutrinos are depending on the representation of the mixing matrix and they are different from those of Dirac neutrinos.
R&D studies on eco-friendly gas mixtures for the ALICE Muon IdentifierJun 05 2018Resistive Plate Chambers (RPCs), used for the Muon Spectrometer of the ALICE experiment at CERN LHC, are currently operated in maxi-avalanche mode with a low threshold value and without amplification in the front-end electronics. RPC detectors have shown ... More
Limb and gravity-darkening coefficients for the TESS satellite at several metallicities, surface gravities, and microturbulent velocitiesApr 26 2018We present new gravity and limb-darkening coefficients for a wide range of effective temperatures, gravities, metallicities, and microturbulent velocities. These coefficients can be used in many different fields of stellar physics as synthetic light curves ... More
Prediction in Cyber Security: Complications and ConsolationsApr 23 2018Apr 25 2018Uncertainty, error, and similar complications add to the many challenges of cyber security. Various disciplines have developed methods for managing these complications, but applying these methods involves disambiguating overlapping terminology and determining ... More
Equations for polar grassmanniansMay 07 2015Given an $N$-dimensional vector space $V$ over a field $\mathbb{F}$ and a trace-valued $(\sigma,\varepsilon)$-sesquilinear form $f:V\times V\rightarrow \mathbb{F}$, with $\varepsilon = \pm 1$ and $\sigma^2 = \mathrm{id}_{\mathbb{F}}$, let ${\cal S}$ be ... More
Estimating class numbers over metabelian extensionsMar 30 2017Let $p$ be an odd prime and $L/K$ a $p$-adic Lie extension whose Galois group is of the form $\mathbb{Z}_p^{d-1}\rtimes \mathbb{Z}_p$. Under certain assumptions on the ramification of $p$ and the structure of an Iwasawa module associated to $L$, we study ... More
A Birkhoff type transitivity theorem for non-separable completely metrizable spaces with applications to Linear DynamicsMay 12 2011Jan 30 2013In this note we prove a Birkhoff type transitivity theorem for continuous maps acting on non-separable completely metrizable spaces and we give some applications for dynamics of bounded linear operators acting on complex Fr\'{e}chet spaces. Among them ... More
On a prescribed mean curvature equation in Lorentz-Minkowski spaceJun 25 2015We are interested in providing new results on a prescribed mean curvature equation in Lorentz-Minkowski space set in the whole R^N, with N >2. We study both existence and multiplicity of radial ground state solutions for p>1, emphasizing the fundamental ... More
On the canonical discussion of polynomial systems with parametersJan 27 2006May 09 2007Given a parametric polynomial ideal I, the algorithm DISPGB, introduced by the author in 2002, builds up a binary tree describing a dichotomic discussion of the different reduced Groebner bases depending on the values of the parameters, whose set of terminal ... More
Topological invariants of O'Grady's six dimensional irreducible symplectic varietyJun 02 2004Aug 08 2004We study O'Grady examples of irreducible symplectic varieties: we establish that both of them can be deformed into lagrangian fibrations. We analyse in detail the topology of the six dimensional example: in particular we compute its Euler characteristic ... More
Distributed Space-Time Coding of Over-the-Air Superimposed Packets in Wireless NetworksMar 14 2013In this paper we propose a new cooperative packet transmission scheme that allows independent sources to superimpose over-the-air their packet transmissions. Relay nodes are used and cooperative diversity is combined with distributed space-time block ... More
General Covariance, Diffeomorphism Invariance, and Background Independence in 5 DimensionsOct 04 2014Apr 10 2015The paper considers the "GR-desideratum", that is, the way general relativity implements general covariance, diffeomorphism invariance, and background independence. Two cases are discussed where $5$-dimensional generalizations of general relativity run ... More
Darboux polynomial matrices: the classical Massive Thirring Model as study caseNov 28 2014One way of constructing explicit expressions of solutions of integrable systems of Partial Differential Equations (PDEs) goes via the Darboux method. This requires the construction of Darboux matrices. Here we introduce a novel algorithm to obtain such ... More
Plenty of Morse functions by perturbing with sums of squaresNov 16 2011Given a smooth function f on R^n and a submanifold M, we prove that the set of diagonal quadratic forms q such that the restriction of f+q to M is Morse is a dense set (in the n-dimensional space of diagonal quadratic forms). The standard transversality ... More
Convex pencils of real quadratic formsJun 23 2011Sep 06 2012We study the topology of the set X of the solutions of a system of two quadratic inequalities in the real projective space RP^n (e.g. X is the intersection of two real quadrics). We give explicit formulae for its Betti numbers and for those of its double ... More
Inflation and the Theory of Cosmological PerturbationsOct 10 2002These lectures provide a pedagogical introduction to inflation and the theory of cosmological perturbations generated during inflation which are thought to be the origin of structure in the universe.
The More Relaxed Supersymmetric Electroweak BaryogenesisMar 15 1998We reanalyze the issue of generation of the baryon asymmetry at the electroweak phase transition in the MSSM and compute the baryon asymmetry assuming the presence of non-trivial CP-violating phases in the parameters associated with the left-right stop ... More
Effective field theories for baryons with two- and three-heavy quarksAug 26 2010Oct 28 2010Baryons made of two or three heavy quarks can be described in the modern language of non-relativistic effective field theories. These, besides allowing a rigorous treatment of the systems, provide new insight in the nature of the three-body interaction ... More
Non-relativistic bound states: the long way back from the Bethe-Salpeter to the Schroedinger equationFeb 19 2009Apr 06 2009I review, in a personal perspective, the history of the theory of non-relativistic bound states in QED and QCD from the Bethe-Salpeter equation to the construction of effective field theories.
Heavy quarkonium decays and transitions in the language of effective field theoriesDec 30 2005Heavy quarkonium decays and transitions are discussed in the framework of non-relativistic effective field theories. Emphasis is put on the matching procedure in the non-perturbative regime. Some exact results valid for the magnetic dipole couplings are ... More
Open Problems in Heavy Quarkonium PhysicsDec 22 2004Some recent progress and a personal selection of open problems in heavy quarkonium physics (spectroscopy, decay and production) inspired by the activity of the Quarkonium Working Group are reviewed.
The QCD potentialSep 21 2007After reviewing the definition of the heavy quark-antiquark potential in pNRQCD, we discuss recent advances in the calculation.
Asymmetric random walks in a discrete spacetime as a model for quantum mechanicsDec 20 2013Jan 25 2015This paper presents a simple model that mimics quantum mechanics (QM) results in terms of probability fields of free particles subject to self-interference, without using Schr\"{o}dinger equation or wavefunctions. Unlike the standard QM picture, the proposed ... More
Dynamics and (de)localization in a one-dimensional tight-binding chainJul 18 2006A simple tight-binding model is used to illustrate how the time dependence of a state vector can be obtained from all the eigenvalues and eigenvectors of the Hamiltonian. The behavior of the eigenvalues and eigenvectors is studied for various parameters ... More
Energies of sp2 carbon shapes with pentagonal disclinations and elasticity theoryMar 28 2006Jun 26 2006Energies of a certain class of fullerene molecules (elongated, contracted, and regular icosahedral fullerenes) are numerically calculated using a microscopic description of carbon-carbon bonding. It is shown how these results can be interpreted and comprehended ... More
Adsorption of He atoms in external grooves of single wall carbon nanotube bundlesNov 15 2002I calculate the quantum states for He atom in the potential of an external groove of the single wall carbon nanotube bundle. The calculated ground state energy is found to be in fair agreement with the experimental estimate which suggests that the outer ... More
Icosadeltahedral geometry of fullerenes, viruses and geodesic domesNov 22 2007I discuss the symmetry of fullerenes, viruses and geodesic domes within a unified framework of icosadeltahedral representation of these objects. The icosadeltahedral symmetry is explained in details by examination of all of these structures. Using Euler's ... More
Constraining hybrid inflation models with WMAP three-year resultsOct 03 2006Jan 11 2007We reconsider the original model of quadratic hybrid inflation in light of the WMAP three-year results and study the possibility of obtaining a spectral index of primordial density perturbations, $n_s$, smaller than one from this model. The original hybrid ... More