Results for "Silvia Bianchi"
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On dominating set polyhedra of circular interval graphsDec 19 2017Feb 20 2018Clique-node and closed neighborhood matrices of circular interval graphs are circular matrices. The stable set polytope and the dominating set polytope on these graphs are therefore closely related to the set packing polytope and the set covering polyhedron ... More Circuits and circulant minorsFeb 08 2019Circulant contraction minors play a key role for characterizing ideal circular matrices in terms of minimally non ideal structures. In this article we prove necessary and sufficient conditions for a circular matrix $A$ to have circulant contraction minors ... More ABJM amplitudes and WL at finite NJun 13 2013Jul 25 2013We evaluate ABJM observables at two loops, for any value of the rank N of the gauge group. We compute the color subleading contributions to the four-point scattering amplitude in ABJM at two loops. Contrary to the four dimensional case, IR divergent N-subleading ... More The Conformal Manifold of Chern-Simons Matter TheoriesSep 30 2010Oct 25 2010We determine perturbatively the conformal manifold of N=2 Chern-Simons matter theories with the aim of checking in the three dimensional case the general prescription based on global symmetry breaking, recently introduced. We discuss in details few remarkable ... More Infrared stability of ABJ-like theoriesOct 27 2009Nov 11 2009We consider marginal deformations of the superconformal ABJM/ABJ models which preserve N=2 supersymmetry. We determine perturbatively the spectrum of fixed points and study their infrared stability. We find a closed line of fixed points which is IR stable. ... More Infrared Stability of N=2 Chern-Simons Matter TheoriesDec 22 2009Feb 04 2010According to the AdS4/CFT3 correspondence, N=2 supersymmetric Chern-Simons matter theories should have a stable fixed point in the infrared. In order to support this prediction we study RG flows of two-level Chern-Simons matter theories with/without flavors ... More Determining QCD Low-Energy Couplings from lattice simulationsOct 12 2007Different strategies for the computation of QCD low-energy couplings by matching lattice QCD with the chiral effective theory are reviewed. After recalling the main features of the chiral effective theory in the epsilon- and p- regimes, the current status ... More On the construction of variant supergravities in D=11, D=10Jul 09 2002We construct with a geometric procedure the supersymmetry transformation laws and Lagrangian for all the ``variant'' D=11 and D=10 Type IIA supergravities. We identify into our classification the D=11 and D=10 Type IIA ``variant'' theories first introduced ... More Modelling the Far-Infrared emission in spyral galaxiesNov 22 1999This thesis presents an original model for the FIR emission in spirals, developed from an existing radiative transfer code (Bianchi, Ferrara & Giovanardi, 1996, ApJ, 465, 127). The model's main features are: a complete treatment of multiple scattering ... More Black hole entropy from graviton entanglementNov 02 2012Jan 07 2013We argue that the entropy of a black hole is due to the entanglement of matter fields and gravitons across the horizon. While the entanglement entropy of the vacuum is divergent because of UV correlations, we show that low-energy perturbations of the ... More Black Hole Entropy, Loop Gravity, and Polymer PhysicsNov 25 2010Loop Gravity provides a microscopic derivation of Black Hole entropy. In this paper, I show that the microstates counted admit a semiclassical description in terms of shapes of a tessellated horizon. The counting of microstates and the computation of ... More Homotopy type of symplectomorphism groups of S^2 X S^2Sep 25 2000May 02 2002In this paper we discuss the topology of the symplectomorphism group of a product of two 2-dimensional spheres when the ratio of their areas lies in the interval (1,2]. More precisely we compute the homotopy type of this symplectomorphism group and we ... More The 1/2 BPS Wilson loop in ABJ(M) at two loops: The detailsJul 02 2013Jul 14 2013We compute the expectation value of the 1/2 BPS circular Wilson loop operator in ABJ(M) theory at two loops in perturbation theory. Our result turns out to be in exact agreement with the weak coupling limit of the prediction coming from localization, ... More Light-like Wilson loops in ABJM and maximal transcendentalityApr 22 2013We revisit the computation of the two-loop light-like tetragonal Wilson loop for three dimensional pure Chern-Simons and N=6 Chern-Simons-matter theory, within dimensional regularization with dimensional reduction scheme. Our examination shows that, contrary ... More The 1/2 BPS Wilson loop in ABJM theory at two loopsMar 27 2013We compute the expectation value of the 1/2 BPS circular Wilson loop in ABJM theory at two loops in perturbation theory. The result shows perfect agreement with the prediction from localization and the proposed framing factor. Lovász-Schrijver PSD-operator on Claw-Free GraphsDec 06 2016The subject of this work is the study of $\LS_+$-perfect graphs defined as those graphs $G$ for which the stable set polytope $\stab(G)$ is achieved in one iteration of Lov\'asz-Schrijver PSD-operator $\LS_+$, applied to its edge relaxation $\estab(G)$. ... More Universality and scaling behavior of RG gauge actionsSep 04 2003We study universality and scaling properties of RG gauge actions (Iwasaki and DBW2). In the first part we consider the critical temperature T_{c} and compute the reference energy scale r_{0} for critical couplings \beta_{c} corresponding to N_{t}=3,4,6,8. ... More N=4 supergravity for Type IIB on T^6/Z_2 in presence of fluxesDec 16 2003Dec 22 2003We report on the construction of four dimensional gauged supergravity models that can be interpreted as type IIB orientifold compactification in presence of 3-form fluxes and D3--branes. We mainly address our attention to the symplectic embedding of the ... More Universality and RG-improved gauge actionsAug 26 2002Aug 30 2002The reference energy scale r_0 is evaluated for RG-improved Iwasaki and DBW2 gauge actions (N_f = 0), at values of the deconfinement coupling beta_c corresponding to N_t = 3,4,6,8. The universality of r_0 T_c between Iwasa ki and Wilson action is confirmed; ... More Perturbation theory for string sigma modelsApr 06 2016Apr 07 2016In this thesis we investigate quantum aspects of the Green-Schwarz superstring in various AdS backgrounds relevant for the AdS/CFT correspondence, providing several examples of perturbative computations in the corresponding integrable sigma-models. We ... More The length operator in Loop Quantum GravityJun 28 2008Sep 11 2008The dual picture of quantum geometry provided by a spin network state is discussed. From this perspective, we introduce a new operator in Loop Quantum Gravity - the length operator. We describe its quantum geometrical meaning and derive some of its properties. ... More Splitting of the homology of the punctured mapping class groupMar 14 2019Let $\Gamma_{g,1}^m$ be the mapping class group of the orientable surface $\Sigma_{g,1}^m$ of genus $g$ with one parametrised boundary curve and $m$ permutable punctures; when $m=0$ we omit it from the notation. Let $\beta_{m}(\Sigma_{g,1})$ be the braid ... More Radiative Transfer in Spiral GalaxiesSep 16 2003The internal dust extinction in spiral galaxies can affect our understanding of their structure and morphology, as well as our perception of the distant universe in the background. The intrinsic properties of the stellar and dust components can be studied ... More Loop Quantum Gravity a la Aharonov-BohmJul 24 2009Sep 10 2009The state space of Loop Quantum Gravity admits a decomposition into orthogonal subspaces associated to diffeomorphism equivalence classes of spin-network graphs. In this paper I investigate the possibility of obtaining this state space from the quantization ... More The NA62 Experiment at CERNOct 01 2015Oct 19 2015The main physics goal of the NA62 experiment at CERN is to precisely measure the branching ratio of the kaon rare decay $K^+\rightarrow \pi^+ \nu \bar\nu$. This decay is strongly suppressed in the Standard Model and its branching ratio is theoretically ... More Behavioural Types for Actor SystemsJun 08 2012Recent mainstream programming languages such as Erlang or Scala have renewed the interest on the Actor model of concurrency. However, the literature on the static analysis of actor systems is still lacking of mature formal methods. In this paper we present ... More Umbral Calculus, a Different Mathematical LanguageFeb 24 2018This thesis is intended to provide an account of the theory and applications of Operational Methods that allow the "translation" of the theory of special functions and polynomials into a "different" mathematical language. The language we are referring ... Moremath.CA05A40, 44A99, 47B99, 33C52, 33C65, 33C99, 33B10, 33B15, 33C45,
11K99, etc Trakhtenbrot theorem and first-order axiomatic extensions of MTLMar 04 2014Jul 09 2014In 1950, B.A. Trakhtenbrot showed that the set of first-order tautologies associated to finite models is not recursively enumerable. In 1999, P. H\'ajek generalized this result to the first-order versions of \L ukasiewicz, G\"odel and Product logics. ... More First-order Nilpotent Minimum Logics: first stepsMar 30 2011Jul 02 2012Following the lines of the analysis done in [BPZ07, BCF07] for first-order G\"odel logics, we present an analogous investigation for Nilpotent Minimum logic NM. We study decidability and reciprocal inclusion of various sets of first-order tautologies ... More Ergodic convergence of a stochastic proximal point algorithmApr 21 2015Jul 25 2016The purpose of this paper is to establish the almost sure weak ergodic convergence of a sequence of iterates $(x_n)$ given by $x_{n+1} = (I+\lambda_n A(\xi_{n+1},\,.\,))^{-1}(x_n)$ where $(A(s,\,.\,):s\in E)$ is a collection of maximal monotone operators ... More A Logic for True ConcurrencyOct 18 2011Jan 17 2014We propose a logic for true concurrency whose formulae predicate about events in computations and their causal dependencies. The induced logical equivalence is hereditary history preserving bisimilarity, and fragments of the logic can be identified which ... More Profiles of Strong Permitted Lines in Classical T Tauri StarsJan 18 2000We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published supporting the model, ... More The local power of the gradient testApr 30 2010Jul 12 2010The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate $n^{-1/2}$, $n$ being the sample size. Comparisons ... More New convergence results for the scaled gradient projection methodJun 25 2014Feb 26 2015The aim of this paper is to deepen the convergence analysis of the scaled gradient projection (SGP) method, proposed by Bonettini et al. in a recent paper for constrained smooth optimization. The main feature of SGP is the presence of a variable scaling ... More Counting rises, levels, and drops in compositionsOct 14 2003A composition of $n\in\NN$ is an ordered collection of one or more positive integers whose sum is $n$. The number of summands is called the number of parts of the composition. A palindromic composition of $n$ is a composition of $n$ in which the summands ... More On topological properties of positive complexity one spacesMay 30 2019Motivated by work of Fine and Panov, and of Lindsay and Panov, we prove that every closed symplectic complexity one space that is positive (e.g. positive monotone) enjoys topological properties that Fano varieties with a complexity one holomorphic torus ... More Quantum anomalies in A^{(1)}_r Toda theories with defectsFeb 27 2019We study quantum integrability of affine Toda theories with a line of defect. In particular, we focus on the problem of constructing quantum higher-spin conserved currents in models defined by two A_r^{(1)} Toda theories separated by a non-trivial tipe-I ... More A study on users' privacy perception with smart devicesSep 02 2018Nowadays, privacy has become a very serious issue with smart and mobile platforms. Users tend to allow intrusive apps access much sensible information without really knowing the potential threats. To solve this issue several solutions (e.g. GDPR) have ... More Operators ideals and approximation propertiesNov 30 2012Dec 13 2012We use the notion of $\A$-compact sets, which are determined by a Banach operator ideal $\A$, to show that most classic results of certain approximation properties and several Banach operator ideals can be systematically studied under this framework. ... More Operational vs. Umbral Methods and Borel TransformAug 12 2019Differintegral methods, currently exploited in calculus, provide a fairly unexhausted source of tools to be applied to a wide class of problems involving the theory of special functions and not only. The use of integral transforms of Borel type and the ... Moremath.CA05A40, 44A99, 47B99, 47A62, 33C52, 33C65, 33C99, 33B10, 33B15,
44A99, 45P05, 47G10, 97I50, 33B15 The perturbative Regge-calculus regime of Loop Quantum GravitySep 13 2007Dec 11 2007The relation between Loop Quantum Gravity and Regge calculus has been pointed out many times in the literature. In particular the large spin asymptotics of the Barrett-Crane vertex amplitude is known to be related to the Regge action. In this paper we ... More Kicked neutron stars and microlensingSep 02 1996Due to the large kick velocities with which neutron stars are born in supernovae explosions, their spatial distribution is more extended than that of their progenitor stars. The large scale height of the neutron stars above the disk plane makes them potential ... More A characteristic subgroup for fusion systemsNov 22 2008As a counterpart for the prime 2 to Glauberman's $ZJ$-theorem, Stellmacher proves that any nontrivial 2-group $S$ has a nontrivial characteristic subgroup $W(S)$ with the following property. For any finite $\Sigma_4$-free group $G$, with $S$ a Sylow 2-subgroup ... More Big Data Computing and Clouds: Trends and Future DirectionsDec 17 2013Aug 22 2014This paper discusses approaches and environments for carrying out analytics on Clouds for Big Data applications. It revolves around four important areas of analytics and Big Data, namely (i) data management and supporting architectures; (ii) model development ... More Scattering Amplitudes/Wilson Loop Duality In ABJM TheoryJul 15 2011Oct 05 2011For N=6 superconformal Chern-Simons-matter theories in three dimensions, by a direct superspace Feynman diagram approach, we compute the two-loop four-point scattering amplitude with external chiral matter fields. We find that the result is in perfect ... More One Loop Amplitudes In ABJMApr 19 2012Jul 10 2012For three dimensional N=6 superconformal field theories we compute one-loop scattering amplitudes for any number of external particles. We focus on a particular subsector of N=2 invariant superamplitudes for which the ordinary perturbative evaluation ... More A matrix model for the latitude Wilson loop in ABJM theoryFeb 21 2018Aug 13 2018In ABJ(M) theory, we propose a matrix model for the exact evaluation of BPS Wilson loops on a latitude circular contour, so providing a new weak-strong interpolation tool. Intriguingly, the matrix model turns out to be a particular case of that computing ... More Framing and localization in Chern-Simons theories with matterApr 01 2016Jun 23 2016Supersymmetric localization provides exact results that should match QFT computations in some regularization scheme. The agreement is particularly subtle in three dimensions where complex answers from localization procedure sometimes arise. We investigate ... More Towards the exact Bremsstrahlung function of ABJM theoryMay 30 2017We present the three-loop calculation of the Bremsstrahlung function associated to the 1/2-BPS cusp in ABJM theory, including color subleading corrections. Using the BPS condition we reduce the computation to that of a cusp with vanishing angle. We work ... More Scattering in ABJ theoriesOct 04 2011We study the correspondence between scattering amplitudes and Wilson loops in three-dimensional Chern-Simons matter theories. In particular, using N=2 superspace formalism, we compute at one loop the whole spectrum of four-point superamplitudes for generic ... More Attractive forces between circular polyions of the same chargeDec 19 2001We study two models of ringlike polyions which are two-dimensional versions of simple models for colloidal particles (model A) and for rodlike segments of DNA (model B), both in solution with counterions. The counterions may condensate on Z sites of the ... More Recovering true metal abundances of the ICMJul 03 2001Recovering the true average abundance of the intracluster medium (ICM) is crucial for estimates of its global metal content, which in turn is linked to its past evolution and to the star formation history of the stellar component of the cluster. We analyze ... More A unit-level small area model with misclassified covariatesNov 09 2016Small area models are mixed effects regression models that link the small areas and borrow strength from similar domains. When the auxiliary variables used in the models are measured with error, small area estimators that ignore the measurement error ... More Superspace approach to anomalous dimensions in {\cal N}=4 SYMJul 09 2001Jul 26 2001In a {\cal N}=1 superspace setup and using dimensional regularization, we give a general and simple prescription to compute anomalous dimensions of composite operators in {\cal N}=4, SU(N) supersymmetric Yang-Mills theory, perturbatively in the coupling ... More Testing perturbation theory on the nf=0 static quark potentialSep 11 2001Sep 28 2001The perturbative expansion of static force and potential is reanalyzed concerning its practical applicability. A well behaved perturbative prediction is given by the integration of the renormalization group equation for the coupling $\alpha_{qq}(\mu=1/r)=(C_f)^{-1} ... More A viewpoint on amalgamation classesSep 09 2010We provide a self-contained introduction to the classical theory of universal-homogeneous models (also known as generic structures, rich models, or Fra\"iss\'e limits). In the literature, most treatments restrict consideration to embeddings among finite ... More On the segmentation of astronomical images via level-set methodsApr 09 2019Astronomical images are of crucial importance for astronomers since they contain a lot of information about celestial bodies that can not be directly accessible. Most of the information available for the analysis of these objects starts with sky explorations ... More