Results for "Fabio Riccioni"

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Tensor Multiplets in Six-Dimensional (2,0) SupergravityDec 17 1997We construct the complete coupling of $(2,0)$ supergravity in six dimensions to $n$ tensor multiplets, extending previous results to all orders in the fermi fields. The truncation to $(1,0)$ supergravity coupled to tensor multiplets exactly reproduces ... More
Low-energy structure of six-dimensional open-string vacuaMar 18 2002This dissertation reviews some properties of the low-energy effective actions for six dimensional open-string models. The first chapter is a pedagogical introduction about supergravity theories. In the second chapter closed strings are analyzed, with ... More
The very-extended tromboneJan 11 2010Mar 24 2010Starting from the very-extended Kac-Moody algebra $E_{11}$, we consider the algebra $E_{11,D}^{local}$, obtained by adding to the non-negative level $E_{11}$ generators the $D$-dimensional momentum operator and an infinite set of additional generators ... More
Abelian Vectors and Self-Dual Tensors in Six-Dimensional SupergravityOct 29 1999Nov 27 2000In this note we describe the most general coupling of {\it abelian} vector and tensor multiplets to six-dimensional $(1,0)$ supergravity. As was recently pointed out, it is of interest to consider more general Chern-Simons couplings to abelian vectors ... More
Local E(11) and the gauging of the trombone symmetryJan 08 2010Mar 17 2010In any dimension, the positive level generators of the very-extended Kac-Moody algebra $E_{11}$ with completely antisymmetric spacetime indices are associated to the form fields of the corresponding maximal supergravity. We consider the local $E_{11}$ ... More
Truncations of the D9-brane action and type-I stringsJan 06 2003Jan 17 2003The low-energy effective action of type-I superstring theory in ten dimensions is obtained performing a truncation of type-IIB supergravity in a background where D9-branes are present. The open sector corresponds to the first order in the low-energy expansion ... More
All Couplings of Minimal Six-dimensional SupergravityJan 11 2001We describe the complete coupling of $(1,0)$ six-dimensional supergravity to tensor, vector and hypermultiplets. The generalized Green-Schwarz mechanism implies that the resulting theory embodies factorized gauge and supersymmetry anomalies, to be disposed ... More
The E_{11} origin of all maximal supergravitiesMay 07 2007Starting from the eleven dimensional E_{11} non-linear realisation of M-theory we compute all possible forms, that is objects with totally antisymmetrised indices, that occur in four dimensions and above as well as all the 1-forms and 2-forms in three ... More
Dual fields and E_{11}Dec 01 2006We show that the adjoint representation of E_{11} contains generators corresponding to the infinite possible dual descriptions of the bosonic on-shell degrees of freedom of eleven dimensional supergravity. We also give an interpretation for the fields ... More
Non-geometric orbifolds and wrapping rulesJul 21 2014We show that the number of half-supersymmetric p-branes in the Type II theories compactified on orbifolds is determined by the wrapping rules recently introduced, provided that one accounts correctly for both geometric and non-geometric T-dual configurations. ... More
E(11)-extended spacetime and gauged supergravitiesDec 11 2007Feb 19 2008We formulate all the five dimensional gauged maximal supergravity theories as non-linear realisations of the semi-direct product of E_{11} and a set of generators which transform according to the first fundamental representation l of E_{11}. The latter ... More
Self-dual Tensors in Six-Dimensional SupergravityDec 04 1998Jan 25 1999We review some properties of the field equations of six-dimensional (1,0) supergravity coupled to tensor and vector multiplets, and in particular their relation to covariant and consistent anomalies and a peculiar Noether identity for the energy-momentum ... More
Local E(11)Feb 26 2009Mar 16 2009We give a method of deriving the field-strengths of all massless and massive maximal supergravity theories in any dimension starting from the Kac-Moody algebra $E_{11}$. Considering the subalgebra of $E_{11}$ that acts on the fields in the non-linear ... More
Consistent and covariant anomalies in six-dimensional supergravityJun 16 1998Jul 03 1998In this note we clarify some issues in six-dimensional (1,0) supergravity coupled to vector and tensor multiplets. In particular, we show that, while the low-energy equations embody tensor-vector couplings that contribute only to gauge anomalies, the ... More
Some Properties of Tensor Multiplets in Six-Dimensional SupergravityNov 11 1997We review some results on the complete coupling between tensor and vector multiplets in six-dimensional $(1,0)$ supergravity.
Massive higher spins and holographyJan 11 2006We review recent progress towards the understanding of higher spin gauge symmetry breaking in AdS space from a holographic vantage point. According to the AdS/CFT correspondence, N=4 SYM theory at vanishing coupling constant should be dual to a theory ... More
Geometric Couplings and Brane Supersymmetry BreakingJul 11 2001Sep 20 2001Orientifold vacua allow the simultaneous presence of supersymmetric bulks, with one or more gravitinos, and non-supersymmetric combinations of BPS branes. This ``brane supersymmetry breaking'' raises the issue of consistency for the resulting gravitino ... More
Dual doubled geometryJun 01 2011We probe doubled geometry with dual fundamental branes, i.e. solitons. Restricting ourselves first to solitonic branes with more than two transverse directions we find that the doubled geometry requires an effective wrapping rule for the solitonic branes ... More
The D-brane U-scanSep 08 2011We consider the D-branes that occur in IIA/IIB string theory compactified on a torus. We review how a general expression for the Wess-Zumino term of such branes is derived. We also review the method to determine the D-brane Wess-Zumino term in a U-duality ... More
Branes and wrapping rulesAug 25 2011We show that the branes of ten-dimensional IIA/IIB string theory must satisfy, upon toroidal compactification, specific wrapping rules in order to reproduce the number of supersymmetric branes that follows from a supergravity analysis. The realization ... More
Heterotic wrapping rulesOct 04 2012Oct 18 2012We show that the same wrapping rules that have been derived for the branes of IIA and IIB string theory also apply to the branes of the toroidally compactified heterotic string theory. Moreover, we show that applying these wrapping rules to the IIA theory ... More
String Solitons and T-dualityFeb 04 2011Jun 23 2011We construct for arbitrary dimensions a universal T-duality covariant expression for the Wess-Zumino terms of supersymmetric String Solitons in toroidally compactified string theories with 32 supercharges. The worldvolume fields occurring in the effective ... More
D-Brane Wess-Zumino Terms and U-DualitySep 23 2010Oct 20 2010We construct gauge-invariant and U-duality covariant expressions for Wess-Zumino terms corresponding to general Dp-branes (for any p<D) in arbitrary 2<D<11 dimensions. A distinguishing feature of these Wess-Zumino terms is that they contain twice as many ... More
On the fermionic Grande Bouffe: more on higher spin symmetry breaking in AdS/CFTAug 11 2005Aug 25 2005We discuss fermionic higher spin gauge symmetry breaking in AdS space from a holographic perspective. Analogously to the recently discussed bosonic case, the higher spin Goldstino mode responsible for the symmetry breaking has a non-vanishing mass in ... More
Real forms of very extended Kac-Moody algebras and theories with eight supersymmetriesJan 17 2008Feb 19 2008We consider all theories with eight supersymmetries whose reduction to three dimensions gives rise to scalars that parametrise symmetric manifolds. We conjecture that these theories are non-linear realisations of very-extended Kac-Moody algebras for suitable ... More
Real weights, bound states and duality orbitsJan 27 2015Nov 13 2015We show that the duality orbits of extremal black holes in supergravity theories with symmetric scalar manifolds can be derived by studying the stabilizing subalgebras of suitable representatives, realized as bound states of specific weight vectors of ... More
Space-filling branes & gaugingsMar 19 2018We consider in any dimension the supersymmetric $\mathbb{Z}_2$ truncations of the maximal supergravity theories. In each dimension and for each truncation we determine all the sets of 1/2-BPS space-filling branes that preserve the supersymmetry of the ... More
Brane orbitsJan 27 2012We complete the classification of half-supersymmetric branes in toroidally compactified IIA/IIB string theory in terms of representations of the T-duality group. As a by-product we derive a last wrapping rule for the space-filling branes. We find examples ... More
Exceptional ReductionsDec 28 2010Mar 11 2011Starting from basic identities of the group E8, we perform progressive reductions, namely decompositions with respect to the maximal and symmetric embeddings of E7xSU(2) and then of E6xU(1). This procedure provides a systematic approach to the basic identities ... More
Branes, Weights and Central ChargesMar 01 2013Dec 18 2014We study the properties of half-supersymmetric branes in string theory with 32 supercharges from a purely group-theoretical point of view using the U-duality symmetry of maximal supergravity and the R-symmetry of the corresponding supersymmetry algebra. ... More
Exotic Dual of Type II Double Field TheoryDec 08 2016We perform an exotic dualization of the Ramond-Ramond fields in type II double field theory, in which they are encoded in a Majorana-Weyl spinor of O(D,D). Starting from a first-order master action, the dual theory in terms of a tensor-spinor of O(D,D) ... More
Towards a classification of branes in theories with eight superchargesFeb 11 2014We provide a classification of half-supersymmetric branes in quarter-maximal supergravity theories with scalars parametrising coset manifolds. Guided by the results previously obtained for the half-maximal theories, we are able to show that half-supersymmetric ... More
The E(11) origin of all maximal supergravities - the hierarchy of field-strengthsJun 05 2009Oct 01 2009Starting from $E_{11}$ and the space-time translations we construct an algebra that promotes the global $E_{11}$ symmetries to local ones, and consider all its possible massive deformations. The Jacobi identities imply that such deformations are uniquely ... More
Duality Symmetries and G^{+++} TheoriesJun 25 2007Feb 26 2008We show that the non-linear realisations of all the very extended algebras G^{+++}, except the B and C series which we do not consider, contain fields corresponding to all possible duality symmetries of the on-shell degrees of freedom of these theories. ... More
$P$ fluxes and exotic branesOct 25 2016We consider the ${\cal N}=1$ superpotential generated in type-II orientifold models by non-geometric fluxes. In particular, we focus on the family of $P$ fluxes, that are related by T-duality transformations to the S-dual of the $Q$ flux. We determine ... More
Supersymmetric Domain WallsJun 25 2012We classify the half-supersymmetric "domain walls", i.e. branes of codimension one, in toroidally compactified IIA/IIB string theory and show to which gauged supergravity theory each of these domain walls belong. We use as input the requirement of supersymmetric ... More
Dual Double Field TheoryMar 23 2016Jun 02 2016We present the dual formulation of double field theory at the linearized level. This is a classically equivalent theory describing the duals of the dilaton, the Kalb-Ramond field and the graviton in a T-duality or O(D,D) covariant way. In agreement with ... More
The different faces of branes in Double Field TheoryMar 13 2019We show how the Wess-Zumino terms of the different branes in string theory can be embedded within double field theory. Crucial ingredients in our construction are the identification of the correct brane charge tensors {and the use of the} double field ... More
The different faces of branes in Double Field TheoryMar 13 2019Mar 27 2019We show how the Wess-Zumino terms of the different branes in string theory can be embedded within double field theory. Crucial ingredients in our construction are the identification of the correct brane charge tensors and the use of the double field theory ... More
IIB Supergravity RevisitedJun 01 2005Jan 17 2006We show in the SU(1,1)-covariant formulation that IIB supergravity allows the introduction of a doublet and a quadruplet of ten-form potentials. The Ramond-Ramond ten-form potential which is associated with the SO(32) Type I superstring is in the quadruplet. ... More
SL(2,R)-invariant IIB Brane ActionsNov 03 2006Jan 18 2007We give a universal SL(2,R)-invariant expression for all IIB p-brane actions with p=-1,1,3,5,7,9. The Wess-Zumino terms in the brane actions are determined by requiring (i) target space gauge invariance and (ii) the presence of a single Born-Infeld vector. ... More
Dual Gravity and MatterMar 13 2008Mar 27 2008We consider the problem of finding a dual formulation of gravity in the presence of non-trivial matter couplings. In the absence of matter a dual graviton can be introduced only for linearised gravitational interactions. We show that the coupling of linearised ... More
IIA Ten-forms and the Gauge Algebras of Maximal Supergravity TheoriesFeb 27 2006Jul 11 2006We show that IIA supergravity can be extended with two independent 10-form potentials. These give rise to a single BPS IIA 9-brane. We investigate the bosonic gauge algebra of both IIA and IIB supergravity in the presence of 10-form potentials and point ... More
IIB Nine-branesJan 18 2006Jul 11 2006We calculate the tensions of all half-supersymmetric nine-branes in IIB string theory. In particular, we point out the existence of a solitonic IIB nine-brane. We find that the D9-brane and its duality transformations parametrize a two-dimensional surface ... More
Spacetime-Filling Branes in Ten and Nine DimensionsOct 18 2004Mar 11 2005Type-IIB supergravity in ten dimensions admits two consistent $Z_2$ truncations. After the insertion of D9-branes, one of them leads to the low-energy action of type-I string theory, and it can be performed in two different ways, in correspondence with ... More
On a mathematical relation between the Eigen model and the asexual Wright-Fisher modelFeb 01 2011We show that the Eigen model and the asexual Wright-Fisher model can be obtained as different limit cases of a unique stochastic model. This derivation makes clear which are the exact differences between these two models. The two key concepts introduced ... More
Tunable Flux Qubit manipulated by fast pulses: operating requirements, dissipation and decoherenceFeb 20 2006A double SQUID manipulated by fast magnetic flux pulses can be used as a tunable flux qubit. In this paper we study the requirements for the qubit operation, and evaluate dissipation and decoherence due to the manipulation for a typical system. Furthermore, ... More
Extensions of the Standard ModelJan 19 1996Rapporteur talk at the International Europhysics Conference on High Energy Physics, Brussels (Belgium), July 27-August 2, 1995. This talk begins with a brief general introduction to the extensions of the Standard Model, reviewing the ideology of effective ... More
Effective interactions of a light gravitinoJan 02 1998Jan 26 1998We review some recent results on the effective interactions of a light gravitino with ordinary particles. In particular, we discuss on a simple example a novel aspect of the low-energy theorems for broken supersymmetry: in the effective lagrangian describing ... More
Dipole-dipole interactions in protein-protein complexes: a quantum mechanical study of the ubiquitin-Dsk2 complexAug 14 2013Quantum mechanical calculations are performed on the proteins that constitute the ubiquitin-Dsk2 complex whose atomic structure has been experimentally determined by NMR spectroscopy (PDB id 1WR1). The results indicate that the dipole moment vectors of ... More
Protein conformational dynamics and electronic structureAug 18 2013Quantum mechanical calculations are performed on 116 conformers of the protein ubiquitin (Lange et al., Science 2008, 320, 1471-1475). The results indicate that the heat of formation (HOF), dipole moment, energy of the frontier orbitals HOMO and LUMO, ... More
A factorization method for q-Racah polynomialsJan 10 2011Jul 14 2011We develop a factorization method for q-Racah polynomials. It is inspired to the approach to q-Hahn polynomials based on the q-Johnson scheme but we do not use association scheme theory nor Gel'fand pairs, but only manipolation of q-difference operators. ... More
FreeIMU: An Open Hardware Framework for Orientation and Motion SensingMar 20 2013Orientation and Motion Sensing are widely implemented on various consumer products, such as mobile phones, tablets and cameras as they enable immediate interaction with virtual information. The prototyping phase of any orientation and motion sensing capable ... More
Condensation of gauge interacting mass-less fermionsJan 28 2004A single mass-less fermionic field with an abelian U(1) gauge interaction (electrodynamics of a mass-less Dirac fermion) is studied by a variational method. Even without the insertion of any extra interaction the vacuum is shown to be unstable towards ... More
A Truly Minimal Left-Right Symmetric Extension of the Standard ModelJul 25 2003By invoking the existence of a general custodial O(2) symmetry, a minimal Left-Right symmetric model based on the gauge group G=SU(2)L SU(2)R U(1)BL is shown to require the existence of only two physical Higgs bosons. The lighter Higgs is predicted to ... More
Low Dimensional Ordering on a Lattice ModelJan 08 1997A simple d-dimensional lattice model is proposed, incorporating some degree of frustration and thus capable of describing some aspects of molecular orientation in covalently bound molecular solids. For d=2 the model is shown to be equivalent to the standard ... More
The Monge problem in Wiener SpaceMar 14 2011Mar 24 2011We address the Monge problem in the abstract Wiener space and we give an existence result provided both marginal measures are absolutely continuous with respect to the infinite dimensional Gaussian measure {\gamma}.
Particle production in DIS off a shockwave in AdSDec 09 2009Sep 01 2010Within the AdS/CFT correspondence, the shockwave metric has been widely used as a gravity dual for a fast moving nucleus. Here we propose a picture for particle production in deep inelastic scattering off a shockwave with the projectile represented by ... More
Massive stars in the nuclei and arms of spiralsMay 09 2008Many of the properties of massive stars in external galaxies, such as chemical compositions, mass functions, and ionizing fluxes, can be derived from the study of the associated clouds of ionized gas. Moreover, the signatures of Wolf-Rayet stars are often ... More
Monoids and Maximal CodesAug 18 2011In recent years codes that are not Uniquely Decipherable (UD) are been studied partitioning them in classes that localize the ambiguities of the code. A natural question is how we can extend the notion of maximality to codes that are not UD. In this paper ... More
A categorical semantic for the Typed Epsilon CalculusSep 08 2014We show that every boolean category satisfying AC provides a categorical semantic of the typed Epsilon calculus.
Incommensurability effects on dipolar bosons in optical latticesOct 29 2015We present a study that investigated a quantum dipolar gas in continuous space where a potential lattice was imposed. Employing exact quantum Monte Carlo techniques, we analysed the ground state properties of the scrutinised system, varying the lattice ... More
A quantum-like view to a generalized two players gameMar 03 2015This paper consider the possibility of using some quantum tools in decision making strategies. In particular, we consider here a dynamical open quantum system helping two players, $\G_1$ and $\G_2$, to take their decisions in a specific context. We see ... More
Perturbation theory of non-perturbative QCDJul 20 2015Perturbation theory is shown to be working in the IR limit of pure SU(3) Yang-Mills theory in Landau gauge by an unconventional setting of the perturbative expansion. A dynamical mass is predicted for the gluon and the lattice data are reproduced fairly ... More
A PBW basis for Lusztig's form of untwisted affine quantum groupsJun 17 1997Apr 03 1998Let g be an untwisted affine Kac-Moody algebra over the field K, and let U_q(g) be the associated quantum enveloping algebra; let \hat{U}_q(g) be the Lusztig's integer form of U_q(g), generated by q-divided powers of Chevalley generators over a suitable ... More
The ERC ENUBET Project: high precision neutrino flux measurements in conventional neutrino beamsApr 29 2017The challenges of precision neutrino physics require measurements of absolute neutrino cross sections at the GeV scale with exquisite (1%) precision. This precision is presently limited by the uncertainties on neutrino flux at the source; their reduction ... More
Visions of a generalized probability theoryOct 18 2018In this Book we argue that the fruitful interaction of computer vision and belief calculus is capable of stimulating significant advances in both fields. From a methodological point of view, novel theoretical results concerning the geometric and algebraic ... More
Vocal Access to a Newspaper Archive: Design Issues and Preliminary InvestigationDec 10 1998This paper presents the design and the current prototype implementation of an interactive vocal Information Retrieval system that can be used to access articles of a large newspaper archive using a telephone. The results of preliminary investigation into ... More
Sheafification functors and Tannaka's reconstructionSep 14 2014We introduce "sheafification" functors from categories of (lax monoidal) linear functors to cat- egories of quasi-coherent sheaves (of algebras) of stacks. They generalize the homogeneous sheafification of graded modules for projective schemes and have ... More
On the one fluid limit for vortex sheetAug 24 2009We consider the interface problem between two incompressible and inviscid fluids in the presence of surface tension. Following the geometric approach of [Shatah,J.;Zeng,C. A priori estimates for Fluid Interface Problems. CPAM, vol.16, no.6, June 2008] ... More
On the limit as the surface tension and density ratio tend to zero for the two-phase Euler equationsDec 17 2009Mar 06 2011We consider the free-boundary motion of two perfect incompressible fluids with different densities $\rho_+$ and $\rho_-$, separated by a surface of discontinuity along which the pressure experiences a jump proportional to the mean curvature by a factor ... More
Degeneracy loci of twisted differential forms and linear line complexesDec 17 2014We prove that the Hilbert scheme of degeneracy loci of pairs of global sections of Omega(2), the twisted cotangent bundle on P^(n-1), is unirational and dominated by the Grassmannian of lines in the projective space of skew-symmetric forms over a vector ... More
A Luenberger-style Observer for Robot Manipulators with Position MeasurementsJul 04 2005This paper presents a novel Luenberger-style observer for robot manipulators with position measurements. Under the assumption that the state evolutions that are to be observed have bounded velocities, it is shown that the origin of the observation error ... More
A duality principle for a semi-linear model in micro-magnetismDec 13 2017This article develops a duality principle for a semi-linear model in micro-magnetism. The results are obtained through standard tools of convex analysis and the Legendre transform concept. We emphasize the dual variational formulation presented is concave ... More
A duality principle for non-linear elasticityDec 07 2017Dec 03 2018This article develops a duality principle for non-linear elasticity. The results are obtained through standard tools of convex analysis and the Legendre transform concept. We emphasize the dual variational formulation is concave. Moreover, sufficient ... More
Global existence results and duality for non-linear models of plates and shellsDec 05 2017Nov 24 2018In this article firstly we develop a new proof for global existence of minimizers for the Kirchhoff-Love plate model. We also present a duality principle and relating sufficient optimality conditions for such a variational plate model. In a second step, ... More
On the methodologies for the assessment of the impact of parameters in acoustophoretic separation devicesApr 20 2019In this communication I reconcile the kinematic method illustrated by some authors~\cite{yang2018,vitali2018} in studying the impact of system and suspension parameters on acoustophoretic separations with the statistical method formerly proposed by Garofalo~\cite{garofalo2014,garofalo2014_2} ... More
A note on optimization in $\mathbb{R}^n$Feb 23 2019In this article, we develop an algorithm suitable for constrained optimization in $\mathbb{R}^n$. The results are developed through standard tools of n-dimensional real analysis and basic concepts of optimization. Indeed, the well known Banach fixed point ... More
Quantization of Poisson groups -- IIApr 10 1996May 08 2017Let $ G^\tau $ be a connected simply connected semisimple algebraic group, endowed with generalized Sklyanin-Drinfeld structure of Poisson group; let $ H^\tau $ be its dual Poisson group. By means of Drinfeld's double construction and dualization via ... More
Modified scattering for the Boson Star EquationAug 29 2013We consider the question of scattering for the boson star equation in three space dimensions. This is a semi-relativistic Klein-Gordon equation with a cubic nonlinearity of Hartree type. We combine weighted estimates, obtained by exploiting a special ... More
The global quantum duality principle: theory, examples, applicationsAug 02 2001Oct 04 2012The "quantum duality principle" states that a quantisation of a Lie bialgebra provides also a quantisation of the dual formal Poisson group and, conversely, a quantisation of a formal Poisson group yields a quantisation of the dual Lie bialgebra as well. ... More
The global quantum duality principleDec 22 1999May 04 2017Let R be an integral domain, let a non-zero h in R be such that k := R/hR is a field, and let HA be the category of torsionless (or flat) Hopf algebras over R. We call H in HA a "quantized function algebra" (=QFA), resp. "quantized restricted universal ... More
Analytic structure of QCD propagators in Minkowski spaceMay 24 2016Analytical functions for the propagators of QCD, including a set of chiral quarks, are derived by a one-loop massive expansion in the Landau gauge, deep in the infrared. By analytic continuation, the spectral functions are studied in Minkowski space, ... More
Variational Quantum ElectrodynamicsAug 13 2013Jan 09 2014A variational method is discussed, based on the principle of minimal variance. The method seems to be suited for gauge interacting fermions, and the simple case of quantum electrodynamics is discussed in detail. The issue of renormalization is addressed, ... More
Higher order extensions of the Gaussian effective potentialAug 08 2013Sep 21 2013A variational method is discussed, extending the Gaussian effective potential to higher orders. The single variational parameter is replaced by trial unknown two-point functions, with infinite variational parameters to be optimized by the solution of ... More
The Principle of Stationary Variance in Quantum Field TheoryAug 19 2013The principle of stationary variance is advocated as a viable variational approach to quantum field theory. The method is based on the principle that the variance of energy should be at its minimum when the state of a quantum system reaches its best approximation ... More
Some Results about FramesJan 30 1997In this paper we discuss some topics related to the general theory of frames. In particular we focus our attention to the existence of different 'reconstruction formulas' for a given vector of a certain Hilbert space and to some refinement of the perturbative ... More
Multi-Resolution Analysis in Arbitrary Hilbert SpacesJan 30 1997We discuss the possibility of introducing a multi-resolution in a Hilbert space which is not necessarily a space of functions. We investigate which of the classical properties can be translated to this more general framework and the way in which this ... More
Study of a Class of Four Dimensional Nonsingular Cosmological BouncesJul 07 2003We study a novel class of nonsingular time-symmetric cosmological bounces. In this class of four dimensional models the bounce is induced by a perfect fluid with a negative energy density. Metric perturbations are solved in an analytic way all through ... More
The lithium problem, a phenomenologist's perspectiveJun 11 2012Jul 09 2012Thirty years after the first observation of the 7Li isotope in the atmosphere of metal-poor halo stars, the puzzle about its origin persists. Do current observations still support the existence of a "plateau": a single value of lithium abundance, constant ... More
The global quantum duality principleDec 22 1999The "quantum duality principle" states that the quantization of a Lie bialgebra --- via a quantum universal enveloping algebra (QUEA) --- provides also a quantization of the dual Lie bialgebra (through its associated formal Poisson group) --- via a quantum ... More
Geometrical Meaning of R-matrix Action for Quantum Groups at Roots of 1Apr 12 1996Nov 06 1996The present work splits in two parts: first, we perform a straightforward generalization of results from [Re], proving autoquasitriangularity of quantum groups U_q(g) and their unrestricted specializations at roots of 1, in particular the function algebra ... More
Quantization of Poisson groups -- IIApr 10 1996Nov 07 1997Let $ G^\tau $ be a connected simply connected semisimple algebraic group, endowed with generalized Sklyanin-Drinfeld structure of Poisson group; let $ H^\tau $ be its dual Poisson group. By means of Drinfeld's double construction and dualization via ... More
An improved model of alliances between political partiesFeb 29 2016We consider an operatorial model of alliances between three political parties which interact with their electors, with the undecided voters, and with the electors of the other parties. This extends what was done in a previous paper, where this last type ... More
Perturbative study of Yang-Mills theory in the infraredSep 19 2015Mar 31 2016Pure Yang-Mills SU(N) theory is studied in four dimensional space and Landau gauge by a double perturbative expansion based on a massive free-particle propagator. By dimensional regularization, all diverging mass terms cancel exactly in the double expansion, ... More
Intertwining operators for non self-adjoint Hamiltonians and bicoherent statesSep 24 2016This paper is devoted to the construction of what we will call {\em exactly solvable models}, i.e. of quantum mechanical systems described by an Hamiltonian $H$ whose eigenvalues and eigenvectors can be explicitly constructed out of some {\em minimal ... More
The ecology of asexual pairwise interactions: A generalized law of mass actionNov 01 2014A general procedure to formulate asexual (unstructured, deterministic) population dynamical models resulting from individual pairwise interactions is proposed. Individuals are characterized by a continuous strategy that represents all their behavioral, ... More
The gluon propagator in Feynman gauge by the method of stationary varianceAug 22 2014The low-energy limit of pure Yang-Mills SU(3) gauge theory is studied in Feynman gauge by the method of stationary variance, a genuine second-order variational method that is suited to deal with the minimal coupling of fermions in gauge theories. In terms ... More
The index of symmetry of a flag manifoldJan 16 2014We study the index of symmetry of a compact generalized flag manifold M=G/H endowed with an invariant Kaehler structure. When the group G is simple we show that the leaves of symmetry are irreducible Hermitian symmetric spaces and we estimate their dimension. ... More
Time to timestamp: opportunistic cooperative localization from reception time measurementsAug 03 2014We present a general framework for improving and extending GNSS-based positioning by leveraging opportunistic measurements from legacy terrestrial radio signals. The proposed approach requires only that participating nodes collect and share reception ... More