Results for "Fabio Viola"

total 2941took 0.22s
Learning and Querying Fast Generative Models for Reinforcement LearningFeb 08 2018A key challenge in model-based reinforcement learning (RL) is to synthesize computationally efficient and accurate environment models. We show that carefully designed generative models that learn and operate on compact state representations, so-called ... More
Random decoupling schemes for quantum dynamical control and error suppressionNov 12 2005We present a general control-theoretic framework for constructing and analyzing random decoupling schemes, applicable to quantum dynamical control of arbitrary finite-dimensional composite systems. The basic idea is to design the control propagator according ... More
Partition Functions of Non-Abelian Quantum Hall StatesJul 10 2010Dec 26 2010Partition functions of edge excitations are obtained for non-Abelian Hall states in the second Landau level, such as the anti-Read-Rezayi state, the Bonderson-Slingerland hierarchy and the Wen non-Abelian fluid, as well as for the non-Abelian spin-singlet ... More
A unified approach to linear probing hashing with bucketsOct 22 2014We give a unified analysis of linear probing hashing with a general bucket size. We use both a combinatorial approach, giving exact formulas for generating functions, and a probabilistic approach, giving simple derivations of asymptotic results. Both ... More
Subsampling scaling: a theory about inference from partly observed systemsJan 16 2017In real-world applications, observations are often constrained to a small fraction of a system. Such spatial subsampling can be caused by the inaccessibility or the sheer size of the system, and cannot be overcome by longer sampling. Spatial subsampling ... More
Tunable Weyl and Dirac states in the nonsymmorphic compound $\rm\mathbf{CeSbTe}$Jul 11 2017Recent interest in topological semimetals has lead to the proposal of many new topological phases that can be realized in real materials. Next to Dirac and Weyl systems, these include more exotic phases based on manifold band degeneracies in the bulk ... More
On a Subfactor Construction of a Factor Non Anti-Isomorphic to ItselfOct 15 2001Jul 22 2004We give a subfactor construction for a $II_{1}$ factor M which is not anti-isomorphic to itself. The $II_{1}$ factor we consider is essentially the same as the example previously given by Connes. However, our construction uses the recently developed theory ... More
Constraints on the fundamental topological parameters of spatial tessellationsJun 25 2013Tessellations of $R^3$ that use convex polyhedral cells to fill the space can be extremely complicated, especially if they are not facet-to-facet, that is, if the facets of a cell do not necessarily coincide with the facets of that cell's neighbours. ... More
Non-Outer Conjugate $\mathbb{Z}_{p^2}$ --Actions on Free Product FactorsNov 24 2004Nov 27 2004We show that for any prime p and for any II$_1$ factor N there exist two $mathbb{Z}_{p^2}$-- actions on the free product factor $*_{1} ^{p}N$ that have the same outer invariant but are not outer conjugate. Therefore, in the case of free product factors, ... More
Randomized Dynamical Decoupling Techniques for Coherent Quantum ControlFeb 21 2006Oct 13 2006The need for strategies able to accurately manipulate quantum dynamics is ubiquitous in quantum control and quantum information processing. We investigate two scenarios where randomized dynamical decoupling techniques become more advantageous with respect ... More
Advantages of Randomization in Coherent Quantum Dynamical ControlApr 06 2008Control scenarios have been identified where the use of randomized design may substantially improve the performance of dynamical decoupling methods [L. F. Santos and L. Viola, Phys. Rev. Lett. {\bf 97}, 150501 (2006)]. Here, by focusing on the suppression ... More
Enhanced Convergence and Robust Performance of Randomized Dynamical DecouplingFeb 21 2006Oct 13 2006We demonstrate the advantages of randomization in coherent quantum dynamical control. For systems which are either time-varying or require decoupling cycles involving a large number of operations, we find that simple randomized protocols offer superior ... More
Dynamical control of qubit coherence: Random versus deterministic schemesNov 12 2005We revisit the problem of switching off unwanted phase evolution and decoherence in a single two-state quantum system in the light of recent results on random dynamical decoupling methods [L. Viola and E. Knill, Phys. Rev. Lett. {\bf 94}, 060502 (2005)]. ... More
Dynamical Generation of Noiseless Quantum SubsystemsFeb 25 2000We present control schemes for open quantum systems that combine decoupling and universal control methods with coding procedures. By exploiting a general algebraic approach, we show how appropriate encodings of quantum states result in obtaining universal ... More
Analysis of the Continued Logarithm AlgorithmJan 30 2018Feb 01 2018The Continued Logarithm Algorithm - CL for short- introduced by Gosper in 1978 computes the gcd of two integers; it seems very efficient, as it only performs shifts and subtractions. Shallit has studied its worst-case complexity in 2016 and showed it ... More
A Simple Separable Exact C*-Algebra not Anti-isomorphic to ItselfJan 21 2010Jan 21 2014We give an example of an exact, stably finite, simple. separable C*-algebra D which is not isomorphic to its opposite algebra. Moreover, D has the following additional properties. It is stably finite, approximately divisible, has real rank zero and stable ... More
WIMP Dark Matter and the First Stars: a critical overviewMar 22 2011If Dark Matter (DM) is composed by Weakly Interacting Massive Particles, its annihilation in the halos harboring the earliest star formation episode may strongly influence the first generation of stars (Population III). Whereas DM annihilation at early ... More
Self-annihilating dark matter and the CMB: reionizing the Universe and constraining cross sectionsDec 08 2009I summarize the recent advances in determining the effects of self-annihilating WIMP dark matter on the modification of the recombination history, at times earlier than the formation of astrophysical objects. Depending on mass and self-annihilation cross ... More
Dark Matter capture and annihilation on the First Stars: preliminary estimatesFeb 07 2008Apr 11 2008Assuming that Dark Matter is dominated by WIMPs, it accretes by gravitational attraction and scattering over baryonic material and annihilates inside celestial objects, giving rise to a "Dark Luminosity" which may potentially affect the evolution of stars. ... More
Effects of BBN on Population III starsDec 18 2003The presence (or absence) of CNO elements in the primordial gas determines different behaviours in population III stars formation and evolution: we therefore present an analysis of the main channels for the synthesis of these elements in BBN in order ... More
A sheafification theorem for doctrinesNov 06 2013Sep 04 2014We define the notion of sheaf in the context of doctrines. We prove the associate sheaf functor theorem. We show that grothendieck toposes and toposes obtained by the tripos to topos construction are instances of categories of sheaves for a suitable doctrine. ... More
Monge problem in metric measure spaces with Riemannian curvature-dimension conditionOct 15 2013We prove the existence of solutions for the Monge minimization problem, addressed in a metric measure space $(X,d,m)$ enjoying the Riemannian curvature-dimension condition $\RCD(K,N)$, with $N < \infty$. For the first marginal measure, we assume that ... More
Appearances of pseudo-bosons from Black-Scholes equationMar 09 2016It is a well known fact that the Black-Scholes equation admits an alternative representation as a Schr\"odinger equation expressed in terms of a non self-adjoint hamiltonian. We show how {\em pseudo-bosons}, linear or not, naturally arise in this context, ... More
A tripos based on compact Hausdorff spacesFeb 10 2016The category of compact Hausdorff spaces is the base of tripos. As such it can be freely completed to an elementary topos.
Heavy-flavour production in pp collisions and correlations in pp and p-Pb collisions measured with ALICE at the LHCSep 27 2016Oct 19 2016Thanks to its excellent tracking and particle identification performance, the ALICE detector is capable of measuring D mesons at central rapidity via their hadronic decay channels down to very low transverse momentum. We show an extension of the prompt ... More
Stacks of ramified Galois coversJul 03 2013Given a finite, flat and finitely presented group scheme $G$ over some base $S$, we introduce the notion of ramified $G$-covers and study the moduli stack $G$-Cov they form. The thesis is divided in three parts. The first one concerns the case when $G$ ... More
Comparison of leading and next-to-leading logarithmic electroweak corrections to Higgs productionMar 13 2013Jul 29 2013Using soft-collinear effective theory, the leading-log radiative electroweak corrections are written in a closed and analytical form for the hadronic cross section of Higgs production through vector boson fusion, qq->qqH, one of the most promising channels ... More
Light Higgs bosons from a strongly interacting Higgs sectorMay 02 2001The mass and the decay width of a Higgs boson in the minimal standard model are evaluated by a variational method in the limit of strong self-coupling interaction. The non-perturbative technique provides an interpolation scheme between strong-coupling ... More
The Stanely-Féray-Śniady formula for the generalized characters of the Symmetric GroupMar 05 2011We show that the explicit formula of Stanley-F\'eray-\'Sniady for the characters of the symmetric group have a natural extension to the generalized characters. These are the spherical functions of the unbalanced Gel'fand pair $(S_n\times S_{n-1},\text{diag}S_{n-1})$. ... More
Optimal transport with branching distance costs and the obstacle problemMar 14 2011Sep 28 2012We address the Monge problem in metric spaces with a geodesic distance: (X, d) is a Polish space and dN is a geodesic Borel distance which makes (X,dN) a possibly branching geodesic space. We show that under some assumptions on the transference plan we ... More
Frequently Asked Questions on the Luminosity--Temperature relation in Groups and ClustersJan 29 2002Jan 31 2002Efforts to understand the deviation of the L--T relation from a simple scaling law valid for clusters and groups have triggered a number of interesting studies on the subject. Techniques and approaches differ widely but most works agree on the important ... More
The Abundance Scatter in M33 from HII Regions: Is There Any Evidence for Azimuthal Metallicity Variations?Feb 01 2011Optical spectra of 25 H II regions in the inner two kpc of the M33 disk have been obtained with the GMOS spectrograph at the Gemini North telescope. The oxygen abundance gradient measured from the detection of the [O III]4363 auroral line displays a scatter ... More
The massive star IMF at high metallicityAug 28 2004The question of the variation of the upper IMF at high metallicity is briefly reviewed. I show recent results suggesting a revision in the definition of `high metallicity' in extragalactic H II regions. I present preliminary results concerning constraints ... More
Blue Supergiants as a Tool for Extragalactic Distances - Empirical DiagnosticsJan 10 2003Blue supergiant stars can be exceptionally bright objects in the optical, making them prime targets for the determination of extragalactic distances. I describe how their photometric and spectroscopic properties can be calibrated to provide a measurement ... More
Orbifold Cohomology of ADE-singularitiesOct 25 2005We study Ruan's "cohomological crepant resolution conjecture" (see math.AG/0108195) for orbifolds with transversal ADE singularities. Let [Y] be such an orbifold, Y its coarse moduli space and Z the crepant resolution of Y. Following Ruan [math.AG/0108195], ... 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
Boundedness of Fourier integral operators on Fourier Lebesgue spaces and affine fibrationsMay 27 2008We carry on the study of Fourier integral operators of H{\"o}rmander's type acting on the spaces $(\mathcal{F}L^p)_{comp}$, $1\leq p\leq\infty$, of compactly supported distributions whose Fourier transform is in $L^p$. We show that the sharp loss of derivatives ... More
Global splittings and super Harish-Chandra pairs for affine supergroupsAug 02 2013Sep 17 2015This paper dwells upon two aspects of affine supergroup theory, investigating the links among them. First, I discuss the "splitting" properties of affine supergroups, i.e. special kinds of factorizations they may admit - either globally, or pointwise. ... More
Massless scalar free Field in 1+1 dimensions I: Weyl algebras Products and Superselection SectorsNov 21 2005Jul 25 2009This is the first of two papers on the superselection sectors of the conformal model in the title, in a time zero formulation. A classification of the sectors of the net of observables as restrictions of solitonic (twisted) and non-solitonic (untwisted) ... More
Nonnegatively curved 5-manifolds with non-abelian symmetryDec 20 2012We classify compact simply-connected 5-dimensional manifolds which admit a metric of nonnegative curvature with a connected non-abelian group acting by isometries. We show that they are diffeomorphic to either S^5, S^3 x S^2, the nontrivial S^3-bundle ... More
Arbitrarily Accurate Dynamical Control in Open Quantum SystemsAug 11 2009Mar 22 2010We show that open-loop dynamical control techniques may be used to synthesize unitary transformations in open quantum systems in such a way that decoherence is perturbatively compensated for to a desired (in principle arbitrarily high) level of accuracy, ... More
GPU computing for 2-d spin systems: CUDA vs OpenGLNov 13 2008In recent years the more and more powerful GPU's available on the PC market have attracted attention as a cost effective solution for parallel (SIMD) computing. CUDA is a solid evidence of the attention that the major companies are devoting to the field. ... More
Spatial STIT Tessellations -- Distributional Results for I-SegmentsAug 08 2011Dec 11 2011Three-dimensional random tessellations that are stable under iteration (STIT tessellations) are considered. They arise as a result of subsequent cell division, which implies that their cells are not face-to-face. The edges of the cell-dividing polygons ... More
Incorporating fermions in the Gaussian Effective Potential: the Higgs-Top SectorAug 17 2012Oct 10 2012The Higgs-Top model is studied by a non-perturbative variational extension of the Gaussian Effective Potential that incorporates fermions. In the limit of a very strong Yukawa coupling the one-loop result is shown to follow a single-parameter scaling ... More
Grand unification in the minimal left-right symmetric extension of the standard modelAug 17 2012The simplest minimal left-right symmetric extension of the standard model is studied in the high energy limit, and some consequences of the grand unification hypothesis are explored assuming that the parity breaking scale is the only relevant energy between ... More
A note on a residual subset of Lipschitz functions on metric spacesJun 20 2013Let (X, d) be a quasi-convex, complete and separable metric space with reference probability measure m. We prove that the set of of real valued Lipschitz function with non zero point-wise Lipschitz constant m-almost everywhere is residual, and hence dense, ... More
Multi-Resolution Analysis and Fractional Quantum Hall Effect: an Equivalence ResultMay 03 2001In this paper we prove that any multi-resolution analysis of $\Lc^2(\R)$ produces, for some values of the filling factor, a single-electron wave function of the lowest Landau level (LLL) which, together with its (magnetic) translated, gives rise to an ... More
Revisiting the abundance gradient in the maser host galaxy NGC 4258Jan 01 2011New spectroscopic observations of 36 HII regions in NGC 4258 obtained with the Gemini telescope are combined with existing data from the literature to measure the radial oxygen abundance gradient in this galaxy. The [OIII]4363 auroral line was detected ... More
The oxygen abundance in the inner HII regions of M101. Implications for the calibration of strong-line metallicity indicatorsOct 23 2006I present deep spectroscopy of four HII regions in the inner, metal-rich zone of the spiral galaxy M101 obtained with the LRIS spectrograph at the Keck telescope. From the analysis of the collisionally excited lines in two of the target HII regions, H1013 ... More
Chen-Ruan cohomology of ADE singularitiesMay 08 2006Jan 09 2007We study Ruan's \textit{cohomological crepant resolution conjecture} for orbifolds with transversal ADE singularities. In the $A_n$-case we compute both the Chen-Ruan cohomology ring $H^*_{\rm CR}([Y])$ and the quantum corrected cohomology ring $H^*(Z)(q_1,...,q_n)$. ... More
Second order gluon polarization for SU(N) theory in linear covariant gaugeJul 01 2015The gluon polarization functional is evaluated for a generic linear covariant gauge and for any space dimension in pure Yang-Mills SU(N) theory up to second order in a generalized perturbation theory, where the zeroth order action is freely chosen and ... More
Copula based hierarchical risk aggregation - Tree dependent sampling and the space of mild tree dependenceJun 11 2015Jun 19 2015The ability to adequately model risks is crucial for insurance companies. The method of "Copula-based hierarchical risk aggregation" by Arbenz et al. offers a flexible way in doing so and has attracted much attention recently. We briefly introduce the ... More
On the time slicing approximation of Feynman path integrals for non-smooth potentialsJun 03 2015We consider the time slicing approximations of Feynman path integrals, constructed via piecewice classical paths. A detailed study of the convergence in the norm operator topology, in the space $\mathcal{B}(L^2(\mathbb{R}^d))$ of bounded operators on ... More
On the distribution of stellar remnants around massive black holes: slow mass segregation, star cluster inspirals and correlated orbitsFeb 20 2014Aug 29 2014We study the long term dynamical evolution of stellar mass black holes (BHs) at the Galactic center (GC) and put constraints on their number and central mass distribution. Models of the GC are considered that have not yet achieved a steady state under ... More
Introduction to quantum information theory and outline of two applications to physics: the black hole information paradox and the renormalization group information flowJul 03 2015Jul 06 2015This review paper is intended for scholars with different backgrounds, possibly in only one of the subjects covered, and therefore little background knowledge is assumed. The first part is an introduction to classical and quantum information theory (CIT, ... More
Analytical study of Yang-Mills theory in the infrared from first principlesNov 03 2015Mar 29 2016Pure Yang-Mills SU(N) theory is studied in the Landau gauge and four dimensional space. While leaving the original Lagrangian unmodified, a double perturbative expansion is devised, based on a massive free-particle propagator. In dimensional regularization, ... More
Consistent transformations of belief functionsJul 30 2014Consistent belief functions represent collections of coherent or non-contradictory pieces of evidence, but most of all they are the counterparts of consistent knowledge bases in belief calculus. The use of consistent transformations cs[.] in a reasoning ... More
On the operation of X-ray polarimeters with a large field of viewDec 09 2013The measurement of the linear polarization is one of the hot topics of High Energy Astrophysics. Gas detectors based on photoelectric effect have paved the way for the design of sensitive instruments and mission proposals based on them have been presented ... More
Dispersion relations for unphysical particlesJun 12 2016Jun 30 2016Generalized dispersion relations are discussed for unphysical particles, e.g. confined degrees of freedom that are not present in the physical spectra but can give rise to observable bound states. While in general the propagator of the unphysical particles ... More
Analytic structure of QCD propagators in Minkowski spaceMay 24 2016Oct 05 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
An introduction to integrable techniques for one-dimensional quantum systemsSep 07 2016Sep 20 2016This monograph introduces the reader to basic notions of integrable techniques for one-dimensional quantum systems. In a pedagogical way, a few examples of exactly solvable models are worked out to go from the coordinate approach to the Algebraic Bethe ... More
The R-matrix action of untwisted affine quantum groups at roots of 1May 04 1998Sep 13 1999Let $\hat{\frak g}$ be an untwisted affine Kac-Moody algebra. The quantum group $U_h(\hat{\frak g})$ (over $C[[h]]$) is known to be a quasitriangular Hopf algebra: in particular, it has a universal R-matrix, which yields an R-matrix for each pair of representations ... More
Quantum function algebras as quantum enveloping algebrasJan 10 1997Nov 07 1997Inspired by a result in the same author's previous work q-alg/9604009, we locate two $ k[q,q^{-1}] $--integer forms of $ F_q[SL(n+1)] $, along with a presentation by generators and relations, and prove that for $ q=1 $ they specialize to $ U({\frak h}) ... More
A PBW theorem for O_e(M_n), O_e(GL_n) and O_e(SL_n) over O(M_n), O(GL_n) and O(SL_n)Aug 01 2006Oct 23 2006This paper has been withdrawn by the author. Its natural evolution is preprint math.QA/0610691, which is different enough to bear a different title (though they share about 2/3s of common content).
Dark photon searches using displaced vertices at low energy e+e- collidersOct 30 2013Jan 31 2014The existence of a new, photon-like, massive particle, the gamma' or dark photon, is postulated in several extensions of the Standard Model. These models are often advocated to explain some recent puzzling astrophysical observations, as well as to solve ... More
Robust Three-axis Attitude Stabilization for Inertial Pointing Spacecraft Using MagnetorquersNov 11 2014In this work feedback control laws are designed for achieving three-axis attitude stabilization of inertial pointing spacecraft using only magnetic torquers. The designs are based on an almost periodic model of geomagnetic field along the spacecraft's ... More
On the genus of a cyclic plane curve over a finite fieldMar 20 2008Cyclic curves, i.e. curves fixed by a cyclic collineation group, play a central role in the investigation of cyclic arcs in Desarguesian projective planes. In this paper, the genus of a cyclic curve arising from a cyclic k-arc of Singer type is computed. ... More
Strong and weak mean value properties on treesOct 14 2001We consider the mean value properties for finite variation measures with respect to a Markov operator in a discrete environnement. We prove equivalent conditions for the weak mean value property in the case of general Markov operators and for the strong ... More
Cooling a vibrational mode coupled to a molecular single-electron transistorJan 15 2009We consider a molecular single electron transistor coupled to a vibrational mode. For some values of the bias and gate voltage transport is possible only by absorption of one ore more phonons. The system acts then as a cooler for the mechanical mode at ... More
Quantum ProteomicsJul 29 2011We put forward the idea of establishing a novel interdisciplinary field of research at the interface between quantum mechanics and proteomics. The new field, called quantum proteomics, is defined as the large-scale study of the electronic structure of ... More
A quantum mechanical analysis of the light-harvesting complex 2 from purple photosynthetic bacteria. Insights into the electrostatic effects of transmembrane helicesJun 25 2010We perform a quantum mechanical study of the peptides that are part of the LH2 complex from Rhodopseudomonas acidophila, a non-sulfur purple bacteria that has the ability of producing chemical energy from photosynthesis. The electronic structure calculations ... More
The electronic structure and dipole moment of charybdotoxin, a scorpion venom peptide with K+ channel blocking activityMay 21 2010The electronic structure of charybdotoxin (ChTX), a scorpion venom peptide that is known to act as a potassium channel blocker, is investigated with the aid of quantum mechanical calculations. The dipole moment vector (145 D) of ChTX can be stirred by ... More
The Higgs puzzle: experiment and theoryDec 10 2001The present experimental and theoretical knowledge of the physics of electroweak symmetry breaking is reviewed. Data still favor a light Higgs boson, of a kind that can be comfortably accommodated in the Standard Model or in its Minimal Supersymmetric ... More
The SUSY WorldJul 19 1993Summary Talk of the Workshop `Properties of SUSY particles' Erice, September 28 -- October 4, 1992.
Algebraic supergroups of Cartan typeSep 03 2011Oct 29 2015I present a construction of connected affine algebraic supergroups G_V associated with simple Lie superalgebras g of Cartan type and with g-modules V. Conversely, I prove that every connected affine algebraic supergroup whose tangent Lie superalgebra ... More
Survival, extinction and approximation of discrete-time branching random walksMar 18 2010Jan 17 2011We consider a general discrete-time branching random walk on a countable set X. We relate local, strong local and global survival with suitable inequalities involving the first-moment matrix M of the process. In particular we prove that, while the local ... More
Lie supergroups vs. super Harish-Chandra pairs: a new equivalenceSep 09 2016This paper presents a new contribution to the study of Lie supergroups - of real smooth, real analytic or complex holomorphic type - by means of super Harish-Chandra pairs. Namely, one knows that there exists a natural functor \Phi\ from Lie supergroups ... More
On some examples and constructions of contact manifoldsNov 27 2017The first goal of this paper is to construct examples of higher dimensional contact manifolds with specific properties. Our main results in this direction are the existence of tight virtually overtwisted closed contact manifolds in all dimensions and ... 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}.
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
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
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
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
Massless scalar free Field in 1+1 dimensions, II: Net Cohomology and Completeness of Superselection SectorsNov 28 2008May 06 2010As an application of Roberts' cohomology (net cohomology), we prove the completeness of the DHR sectors of the local observables of the model in the title, detailed in [8]. This result is achieved via the triviality of the net 1-cohomology, with values ... 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
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
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
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