Results for "S. Bianchi"

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Two-loop cusp anomaly in ABJM at strong couplingJul 17 2014Oct 01 2014We compute the null cusp anomalous dimension of ABJM theory at strong coupling up to two-loop order. This is done by evaluating corrections to the corresponding superstring partition function, weighted by the $AdS_4\times \mathbb{CP}^3$ action in AdS ... More
Quantum gravity and black hole spin in gravitational wave observations: a test of the Bekenstein-Hawking entropyDec 12 2018Black hole entropy is a robust prediction of quantum gravity with no observational test to date. We use the Bekenstein-Hawking entropy formula to determine the probability distribution of the spin of black holes at equilibrium in the microcanonical ensemble. ... More
SCUBA observations of NGC 6946Dec 01 1999We present sub-millimetre images of the spiral galaxy NGC 6946 at 450 and 850 um. The observations have been carried out using the scan/map imaging mode of the Sub-millimetre Common User Bolometer Array (SCUBA) at the James Clark Maxwell Telescope (JCMT). ... More
Worldsheet scattering for the GKP stringAug 28 2015We initiate the perturbative study of the S-matrix for the excitations on top of the GKP vacuum at strong coupling. Using the string sigma model action expanded around the null cusp classical solution, we compute the tree-level S-matrix elements and compare ... More
On the scattering of gluons in the GKP stringNov 03 2015We compute the one-loop S-matrix for the light bosonic excitations of the GKP string at strong coupling. These correspond, on the gauge theory side, to gluon insertions in the GKP vacuum. We perform the calculation by Feynman diagrams in the worldsheet ... More
Non-planarity through unitarity in ABJMNov 25 2013May 21 2014We use unitarity techniques to compute the two-loop non-planar corrections to the Sudakov form factor and the four-point amplitude in ABJM theory. We start by reconstructing non-planar integrals from two-particle cuts in three dimensions. This causes ... More
Quantum dispersion relations for the $AdS_4 \times CP^3$ GKP stringMay 04 2015Nov 04 2015We compute the one-loop correction to the dispersion relations of the excitations of the $AdS_4 \times CP^3$ sigma model dual to ABJM theory, expanded around the cusp background. The results parallel those of N = 4 SYM. As in that case, the dispersion ... 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
The covariogram and Fourier-Laplace transform in $\mathbb{C}^n$Dec 30 2013Apr 29 2016The covariogram $g_{K}$ of a convex body $K$ in $\mathbb{R}^n$ is the function which associates to each $x\in\mathbb{R}^n$ the volume of the intersection of $K$ with $K+x$. Determining $K$ from the knowledge of $g_K$ is known as the Covariogram Problem. ... 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
Entropy of Non-Extremal Black Holes from Loop GravityApr 23 2012We compute the entropy of non-extremal black holes using the quantum dynamics of Loop Gravity. The horizon entropy is finite, scales linearly with the area A, and reproduces the Bekenstein-Hawking expression S = A/4 with the one-fourth coefficient for ... More
On the homology of the commutator subgroup of the pure braid groupMay 13 2019We study the homology of $[P_n,P_n]$, the commutator subgroup of the pure braid group on $n$ strands, and show that $H_l([P_n,P_n])$ contains a free abelian group of infinite rank for all $1\leq l\leq n-2$. As a consequence we determine the cohomological ... More
On structure constants with two spinning twist-two operatorsJan 03 2019I consider three-point functions of one protected and two unprotected twist-two operators with spin in N=4 SYM at weak coupling. At one loop I formulate an empiric conjecture for the dependence of the corresponding structure constants on the spins of ... More
Nature of magnetic order in YbInNi4Jan 25 2011Apr 26 2011We have measured field and temperature dependent magnetization of YbInNi4 to elucidate the nature of the magnetic transition at 3 K. For small fields we find magnetic order as previously reported. In contrast to former reports, however, our high resolution ... More
Magneto-optical Kerr effect in $Eu_{1-x}Ca_{x}B_{6}$Jul 18 2003Aug 14 2003We have measured the magneto-optical Kerr rotation of ferromagnetic $Eu_{1-x}Ca_{x}B_{6}$ with x=0.2 and 0.4, as well as of $YbB_{6}$ serving as the non-magnetic reference material. As previously for $EuB_{6}$, we could identify a feature at 1 $eV$ in ... More
The influence of clumping on surface brightness fits of edge-on spiral galaxiesJan 17 2002We have used a Monte Carlo radiative transfer code to produce edge-on images of dusty galactic disks, allowing a fraction of the dust to be distributed in clumps. Synthetic images of edge-on galaxies have been constructed for different amounts of dust, ... More
XMM-Newton observation of the bright Seyfert 1 galaxy, MCG+8-11-11Sep 01 2005We report on the XMM-Newton observation of the bright Seyfert 1 galaxy, MCG+8-11-11. Data from the EPIC/p-n camera, the Reflection Gratings Spectrometers (RGS) and the Optical Monitor (OM) have been analyzed. The p-n spectrum is well fitted by a power ... More
Wilson ratio in Yb-substituted CeCoIn5Dec 01 2009Dec 07 2010We have investigated the effect of Yb substitution on the Pauli limited, heavy fermion superconductor, CeCoIn$_5$. Yb acts as a non-magnetic divalent substituent for Ce throughout the entire doping range, equivalent to hole doping on the rare earth site. ... 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
Evolution of the disc atmosphere in the X-ray binary MXB 1659-298, during its 2015-2017 outburstMay 03 2019We report on the evolution of the X-ray emission of the accreting neutron star (NS) low mass X-ray binary (LMXB), MXB 1659-298, during its most recent outburst in 2015-2017. We detected 60 absorption lines during the soft state (of which 21 at more than ... More
Suzaku Confirms NGC~3660 is an Unabsorbed Seyfert 2Jan 12 2016An enigmatic group of objects, unabsorbed Seyfert 2s may have intrinsically weak broad line regions, obscuration in the line of sight to the BLR but not to the X-ray corona, or so much obscuration that the X-ray continuum is completely suppressed and ... More
A note on multiply wound BPS Wilson loops in ABJMMay 03 2016We consider BPS Wilson loops in planar ABJM theory, wound multiple times around the great circle. We compute the expectation value of the 1/6-BPS and 1/2-BPS Wilson loops to three- and two-loop order in perturbation theory, respectively, dealing with ... More
Dust Formation and Survival in Supernova EjectaApr 04 2007The presence of dust at high redshift requires efficient condensation of grains in SN ejecta, in accordance with current theoretical models. Yet, observations of the few well studied SNe and SN remnants imply condensation efficiencies which are about ... More
A note on three-point functions of unprotected operatorsSep 12 2018Given the recent progress in computing three-point functions in N=4 SYM via integrability, I provide here a novel direct calculation of some structure constants at weak coupling. The main focus is on correlators involving more than one unprotected operator, ... More
A note on scattering amplitudes on the moduli space of ABJMFeb 18 2015Nov 03 2015We compute the simplest one-loop planar amplitudes in Higgsed ABJM theory at a generic point of the moduli space. We explicitly check that they can be expressed in terms of integrals which are invariant under dual conformal symmetry involving masses, ... More
ABJM $θ$-Bremsstrahlung at four loops and beyond: non-planar correctionsSep 28 2017We consider the Bremsstrahlung function associated to a 1/6-BPS Wilson loop in ABJM theory, with a cusp in the couplings to scalar fields. We non-trivially extend its recent four-loop computation at weak coupling to include non-planar corrections. We ... More
ABJM $θ$-Bremsstrahlung at four loops and beyondSep 04 2017Nov 27 2017In ABJ(M) theory a generalized cusp can be constructed out of the 1/6 BPS Wilson line by introducing an angle $\varphi$ in the spacial contour and/or an angle $\theta$ in the internal R-symmetry space. The small angles limits of its anomalous dimension ... More
N=8 SYM vs. N=6 Chern-Simons: Four-point amplitudes at two-loopsOct 17 2012We compute the four-point amplitude in 3d N=8 SYM at two loops, by solving the three dimensional scalar doublebox in dimensional regularization. We compare it to the same result in the ABJM theory, to which maximal SYM should flow in the infrared at strong ... More
Dilogarithm ladders from Wilson loopsNov 18 2014We consider a light-like Wilson loop in N=4 SYM evaluated on a regular n-polygon contour. Sending the number of edges to infinity the polygon approximates a circle and the expectation value of the light-like WL is expected to tend to the localization ... More
A $QQ\to QQ$ planar doublebox in canonical formDec 16 2016We consider a planar doublebox with four massive external momenta and two massive internal propagators. We derive the system of differential equations for the relevant master integrals, cast it in canonical form, write it as a $d\log$ form and solve it ... More
Testing warm Comptonization models for the origin of the soft X-ray excess in AGNOct 13 2017The X-ray spectra of many active galactic nuclei (AGN) show a soft X-ray excess below 1-2 keV on top of the extrapolated high- energy power law. The origin of this component is uncertain. It could be a signature of relativistically blurred, ionized reflection, ... 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
Open Strings on the Neveu-Schwarz PentabraneNov 10 1997We analyze the propagation of open and unoriented strings on the Neveu-Schwarz pentabrane (N5-brane) along the lines of a similar analysis for the SU(2) WZNW models. We discuss the two classes of open descendants of the diagonal models and a series of ... More
Horizon energy as the boost boundary term in general relativity and loop gravityMay 24 2012We show that the near-horizon energy introduced by Frodden, Ghosh and Perez arises from the action for general relativity as a horizon boundary term. Spin foam variables are used in the analysis. The result provides a derivation of the horizon boost Hamiltonian ... More
Real-time optical micro-manipulation using optimized holograms generated on the GPUJul 23 2009Mar 16 2010Holographic optical tweezers allow the three dimensional, dynamic, multipoint manipulation of micron sized dielectric objects. Exploiting the massive parallel architecture of modern GPUs we can generate highly optimized holograms at video frame rate allowing ... More
The canonical form has got baublesDec 22 2016The method of differential equations in canonical form has proven a powerful tool for solving multiloop Feynman integrals. In this note we test this procedure away from four dimensions. Namely, we consider the simple example of a massless doublebox, expanded ... More
An exact limit of ABJMMay 09 2016We study planar ABJM in a limit where one coupling is negligible compared to the other. We provide a recipe for exactly solving the expectation value of bosonic BPS Wilson loops on arbitrary smooth contours, or the leading divergence for cusped ones, ... More
On the ABJM four-point amplitude at three loops and BDS exponentiationMar 13 2014We study the three-loop four-point amplitude in ABJM theory. We determine the dual conformal invariant integrals with highest number of propagators and fix their coefficients by two-particle cuts. Evaluating such a combination of integrals in dimensional ... More
Last gasp of a black hole: unitary evaporation implies non-monotonic mass lossMay 16 2014We show within the usual two-dimensional approximation that unitarity and the restoration of Minkowski vacuum correlations at the end of black hole evaporation impose unexpected constraints on its mass loss rate: before disappearing the black hole emits ... More
The Construction of Spin Foam Vertex AmplitudesJul 19 2012Jan 31 2013Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional ... More
Entanglement entropy and negative energy in two dimensionsApr 02 2014Aug 13 2014It is well known that quantum effects can produce negative energy densities, though for limited times. Here we show in the context of two-dimensional CFT that such negative energy densities are present in any non-trivial conformal vacuum and can be interpreted ... More
Mechanical laws of the Rindler horizonMay 21 2013Gravitational perturbations of flat Minkowski space make the Rindler horizon dynamical: the horizon satisfies mechanical laws analogous to the ones followed by black holes. We describe the gravitational perturbation of Minkowski space using perturbative ... More
Identities and isomorphisms of finite-dimensional graded simple algebrasApr 04 2018Jun 07 2018Let $\mathbb F$ be an algebraically closed field, $G$ be an abelian group, and let $A$ and $B$ be arbitrary finite-dimensional $G$-graded simple algebras over $\mathbb F$. We prove that $A$ and $B$ are isomorphic if, and only if, they satisfy the same ... More
Bases for local Weyl modules for the hyper and truncated current $\mathfrak{sl}_2$-algebrasJun 01 2017Jun 14 2017We use the theory of Gr\"obner-Shirshov bases for ideals to construct linear bases for graded local Weyl modules for the (hyper) current and the truncated current algebras associated to the finite-dimensional complex simple Lie algebra $\mathfrak{sl}_2$. ... More
Uniqueness for an inviscid stochastic dyadic model on a treeJan 30 2013In this paper we prove that the lack of uniqueness for solutions of the tree dyadic model of turbulence is overcome with the introduction of a suitable noise. The uniqueness is a weak probabilistic uniqueness for all $l^2$-initial conditions and is proven ... More
Dynamical behavior of a stochastic forward-backward algorithm using random monotone operatorsAug 12 2015Jul 04 2016The purpose of this paper is to study the dynamical behavior of the sequence produced by a forward-backward algorithm involving two random maximal monotone operators and a sequence of decreasing step sizes. Defining a mean monotone operator as an Aumann ... More
Retrieving convex bodies from restricted covariogram functionsFeb 28 2007The covariogram g_K(x) of a convex body K \subseteq E^d is the function which associates to each x \in E^d the volume of the intersection of K with K+x. Matheron asked whether g_K determines K, up to translations and reflections in a point. Positive answers ... More
The recent star formation in NGC 6822 from HST imagingMay 14 2006We present HST WFPC2 and STIS imaging of the low metallicity galaxy NGC 6822, performed as part of a study of the young stellar populations in the galaxies of the Local Group. Eleven WFPC2 pointings, with some overlap, cover two regions, extending over ... More
Entropy of a subalgebra of observables and the geometric entanglement entropyJan 19 2019The geometric entanglement entropy of a quantum field in the vacuum state is known to be divergent and, when regularized, to scale as the area of the boundary of the region. Here we introduce an operational definition of the entropy of the vacuum restricted ... More
Lift-and-project ranks of the stable set polytope of joined a-perfect graphsApr 29 2015In this paper we study lift-and-project polyhedral operators defined by Lov?asz and Schrijver and Balas, Ceria and Cornu?ejols on the clique relaxation of the stable set polytope of web graphs. We compute the disjunctive rank of all webs and consequently ... More
The reprocessing features in the X-ray spectrum of the NELG MCG-5-23-16Nov 13 2003We present results from the spectral analysis of the Seyfert 1.9 galaxy MCG-5-23-16, based on ASCA, BeppoSAX, Chandra and XMM-Newton observations. The spectrum of this object shows a complex iron Kalpha emission line, which is best modeled by a superposition ... More
A Perturbative QCD Based Study of Polarized Nucleon Structure in the Transition Region and Beyond: "Quarks, Color Neutral Clusters, and Hadrons"Dec 27 2004A large fraction of the world data on both polarized and unpolarized inclusive $ep$ scattering at large Bjorken $x$ lies in the resonance region where a correspondence with the deep inelastic regime, known as Bloom and Gilman's duality, was observed. ... 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
New Meteorological and Geological Study of Taviano (LE)Jul 13 2015This paper contains the result of the elaboration of informations about Solar Irradiation, Geological, Meteorological and Climatic from the point of view of the quantitative data and social interaction recorded in Taviano (LE) over 24 years. These data ... More
Quark-Hadron Duality in Structure FunctionsJan 14 2005Quark-hadron duality is studied in a systematic way for both the unpolarized and polarized structure functions, by taking into account all the available data in the resonance region.In both cases, a detailed perturbative QCD based analysis of the structure ... More
Parton-Hadron Duality in Unpolarised and Polarised Structure FunctionsAug 05 2003We study the phenomenon of parton-hadron duality in both polarised and unpolarised electron proton scattering using the HERMES and the Jefferson Lab data, respectively. In both cases we extend a systematic perturbative QCD based analysis to the integrals ... More
A deep X-ray view of the bare AGN Ark 120. VI. Geometry of the hot corona from spectroscopic and polarization signaturesNov 19 2018The spectral shape of the hard X-ray continuum of Active Galactic Nuclei (AGN) can be ascribed to inverse Compton scattering of optical/UV seed photons from the accretion disc by a hot corona of electrons. This physical process produces a polarization ... More
Surprises from the Resolution of Operator Mixing in N = 4 SYMDec 18 2003We reexamine the problem of operator mixing in N = 4 SYM. Particular attention is paid to the correct definition of composite gauge invariant local operators, which is necessary for the computation of their anomalous dimensions beyond lowest order. As ... More
Minimally helicity violating, maximally simple scalar amplitudes in N=4 SYMAug 01 2012Nov 21 2012In planar N=4 SYM we study a particular class of helicity preserving amplitudes. These are scalar amplitudes whose flavor configuration is chosen in such a way that only a limited number of diagrams is allowed, which exhibit an iterative structure. For ... More
Lyman Continuum Escape from Inhomogeneous ISMNov 28 2001We have studied the effects of gas density inhomogeneities on the escape of ionising Lyman continuum (Lyc) photons from Milky Way-type galaxies via 3D numerical simulations using the Monte Carlo radiative transfer code CRASH (Ciardi et al. 2001). To this ... More
Deep Herschel PACS point spread functionsMay 11 2016Jun 28 2016The knowledge of the point spread function (PSF) of imaging instruments represents a fundamental requirement for astronomical observations. The Herschel PACS PSFs delivered by the instrument control centre are obtained from observations of the Vesta asteroid, ... 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
New Meteorological and Geological Study of Acquapendente (VT)Jun 14 2015In this paper we present an analysis of the geological, meteorological and climatic data recorded in Acquapendente (VT) over 24 years. These data are compared to check local variations,long term trends, and correlation with maen annual temperature. The ... More
Crystalline and electronic structure of single-layer TaS$_2$Jun 19 2016Single-layer TaS$_2$ is epitaxially grown on Au(111) substrates. The resulting two-dimensional crystals adopt the 1H polymorph. The electronic structure is determined by angle-resolved photoemission spectroscopy and found to be in excellent agreement ... More
Algebraic Characterization of the Class of Languages recognized by Measure Only Quantum AutomataJun 08 2012Jul 16 2012We study a model of one-way quantum automaton where only measurement operations are allowed (MOn-1qfa). We give an algebraic characterization of LMO, showing that the syntactic monoids of the languages in LMO are exactly the literal pseudovariety of J-trivial ... More
Spin fluctuations and black hole singularities: the onset of quantum gravity is spacelikeMar 28 2018Jul 06 2018Due to quantum fluctuations, a black hole of mass $M$ represents an average over an ensemble of black hole geometries with angular momentum. This observation is apparently at odds with the fact that the curvature singularity inside a rotating black hole ... More
Laplacian cut-offs, porous and fast diffusion on manifolds and other applicationsJul 20 2016We construct exhaustion and cut-off functions with controlled gradient and Laplacian on manifolds with Ricci curvature bounded from below by a (possibly unbounded) nonpositive function of the distance from a fixed reference point, without any assumptions ... More
Bohr-Sommerfeld Quantization of SpaceAug 10 2012We introduce semiclassical methods into the study of the volume spectrum in loop gravity. The classical system behind a 4-valent spinnetwork node is a Euclidean tetrahedron. We investigate the tetrahedral volume dynamics on phase space and apply Bohr-Sommerfeld ... More
Theory of Radio Propagation in Inhomogeneous Media (The Eikonal Method)May 11 2010The Istituto Nazionale di Geofisica e Vulcanologia has been involved since its foundation in the forecast of the conditions in which a radio link that makes use of propagation by means of ionospheric wave takes place. In the last times it gained interest ... More
Quark-hadron duality and higher twist contributions in structure functionsJan 19 2005Quark-hadron duality is studied in a systematic way for polarized and unpolarized structure functions, by taking into account all the available data in the resonance region. In both cases, a precise perturbative QCD based analysis of the integrals of ... More
Statistics of relativistically broadened Fe K-alpha lines in AGNOct 05 2006We present preliminary results on the properties of relativistically broadened Fe K-alpha lines in a collection of more then 100 Active Galactic Nuclei (AGN) observed by the XMM-Newton EPIC-pn camera. Our main conclusions can be summarized as follows: ... More
An all order identity between ABJM and N=4 SYM four-point amplitudesDec 15 2011We derive an exact algebraic identity between the two-loop four-point amplitude in ABJM theory and the corresponding one-loop amplitude in N=4 SYM theory. This identity generalizes previous partial results to an exact relation valid at all orders in the ... More
Topological complexity of unordered configuration spaces of surfacesDec 19 2017Dec 13 2018We determine the topological complexity of unordered configuration spaces on almost all punctured surfaces (both orientable and non-orientable). We also give improved bounds for the topological complexity of unordered configuration spaces on all aspherical ... More
Luminous star-forming galaxies in the SDSS-GALEX databaseFeb 17 2014We use the combined photometric SDSS + GALEX database to look for populations of luminous blue star-forming galaxies. These were initially identified from such a sample at redshifts near 0.4, using SDSS spectra. We make use of the colour index previously ... More
On the Architecture of Spacetime GeometryDec 20 2012We propose entanglement entropy as a probe of the architecture of spacetime in quantum gravity. We argue that the leading contribution to this entropy satisfies an area law for any sufficiently large region in a smooth spacetime, which, in fact, is given ... More
Exploring the intergalactic medium with VLT/UVESDec 12 2001The remarkable efficiency of the UVES spectrograph at the VLT has made it possible to push high-resolution, high-S/N ground observations of the Ly-a forest down to z~1.5, gaining new insight into the physical conditions of the intergalactic medium and ... More
Exploring the Lyman Forest with VLT/UVESSep 19 2001A sample of 8 QSOs with 1.7 < z_em < 3.7 has been observed with VLT/UVES at a typical resolution 45000 and S/N~40-50. Thanks to the two-arm design of the spectrograph, a remarkable efficiency has been achieved below 400nm and above 800nm, which translates ... More
Green-Schwarz superstring on the latticeMay 05 2016We consider possible discretizations for a gauge-fixed Green-Schwarz action of Type IIB superstring. We use them for measuring the action, from which we extract the cusp anomalous dimension of planar $\mathcal{N}=4$ SYM as derived from AdS/CFT, as well ... More
Lattice and string worldsheet in AdS/CFT: a numerical studyJan 18 2016We consider a possible discretization for the gauge-fixed Green-Schwarz (two-dimensional) sigma-model action for the Type IIB superstring and use it for measuring the cusp anomalous dimension of planar $\mathcal{N}=4$ SYM as derived from string theory. ... More
Photoionized emission and absorption features in the high-resolution X-ray spectra of NGC 3783Nov 28 2018Our Swift monitoring program triggered two joint XMM-Newton, NuSTAR and HST observations on 11 and 21 December 2016 targeting NGC 3783, as its soft X-ray continuum was heavily obscured. Consequently, emission features, including the O VII radiative recombination ... More
Unveiling multiple AGN activity in galaxy mergersNov 02 2016In this paper we present an overview of the MAGNA (Multiple AGN Activity) project aiming at a comprehensive study of multiple supemassive black hole systems. With the main goal to characterize the sources in merging systems at different stages of evolution, ... More
Anomalous dimensions in N=4 SYM theory at order g^4Mar 22 2000We compute four-point correlation functions of scalar composite operators in the N=4 supercurrent multiplet at order g^4 using the N=1 superfield formalism. We confirm the interpretation of short-distance logarithmic behaviours in terms of anomalous dimensions ... More
The role of magnetic field for quiescence-outburst models in CVsDec 19 2014In this paper we present the elementary assumptions of our research on the role of the magnetic field in modelling the quiescence-outbursts cycle in Cataclysmic Variables (CVs). The behaviour of the magnetic field is crucial not only to integrate the ... More
Recurring obscuration in NGC 3783May 09 2018Obscuration of the continuum emission from active galactic nuclei by streams of gas with relatively high velocity (> 1000 km/s) and column density (>3E25 per m2) has been seen in a few Seyfert galaxies. This obscuration has a transient nature. In December ... More
Anatomy of the AGN in NGC 5548 IX. Photoionized emission features in the soft X-ray spectraDec 21 2017The X-ray narrow emission line region (NELR) of the archetypal Seyfert 1 galaxy NGC\,5548 has been interpreted as a single-phase photoionized plasma that is absorbed by some of the warm absorber components. This scenario requires those overlaying warm ... More
Linear growth of the entanglement entropy and the Kolmogorov-Sinai rateSep 01 2017Feb 26 2018The rate of entropy production in a classical dynamical system is characterized by the Kolmogorov-Sinai entropy rate $h_{\mathrm{KS}}$ given by the sum of all positive Lyapunov exponents of the system. We prove a quantum version of this result valid for ... More
Metastability in the reversible inclusion processMay 17 2016We study the condensation regime of the finite reversible inclusion process, i.e., the inclusion process on a finite graph $S$ with an underlying random walk that admits a reversible measure. We assume that the random walk kernel is irreducible and its ... More
New light on gamma-ray burst host galaxies with HerschelFeb 17 2014Feb 19 2014Until recently, dust emission has been detected in very few host galaxies of gamma-ray bursts (GRBHs). With Herschel, we have now observed 17 GRBHs up to redshift z~3 and detected seven of them at infrared (IR) wavelengths. This relatively high detection ... More
An ASM-based Characterization of Starvation-free SystemsJul 20 2017Abstract State Machines (ASMs) have been successfully applied for modeling critical and complex systems in a wide range of application domains. However, unlike other well-known formalisms, e.g. Petri nets, ASMs lack inherent, domain-independent characterisations ... More
Gluing polyhedra with entanglement in loop quantum gravityMay 15 2018Jul 03 2018In a spin-network basis state, nodes of the graph describe un-entangled quantum regions of space, quantum polyhedra. In this paper we show how entanglement between intertwiner degrees of freedom enforces gluing conditions for neighboring quantum polyhedra. ... More
Soft gravitational radiation from ultra-relativistic collisions at sub- and sub-sub-leading orderJan 30 2019Feb 12 2019Using soft-graviton theorems a well-known zero-frequency limit (ZFL) for the gravitational radiation flux $dE^{GW}/d \omega$ is re-derived and extended to order ${{\cal O}}(\omega)$ and ${{\cal O}}(\omega^2)$ for arbitrary massless multi-particle collisions. ... More
Continuous-time random walk between Lévy-spaced targets in the real lineJun 06 2018We consider a continuous-time random walk which is defined as an interpolation of a random walk on a point process on the real line. The distances between neighboring points of the point process are i.i.d. random variables in the normal domain of attraction ... More
Tumor-induced neoneurogenesis and perineural tumor growth: a mathematical approachJul 13 2015Primary tumors infrequently lead to demise of cancer patients; instead, mortality and a significant degree of morbidity result from the growth of secondary tumors in distant organs (metastasis). It is well-known that malignant tumors induce the formation ... More
LQG propagator from the new spin foamsMay 25 2009We compute metric correlations in loop quantum gravity with the dynamics defined by the new spin foam models. The analysis is done at the lowest order in a vertex expansion and at the leading order in a large spin expansion. The result is compared to ... More
Entanglement entropy of squeezed vacua on a latticeJul 06 2015We derive a formula for the entanglement entropy of squeezed states on a lattice in terms of the complex structure J. The analysis involves the identification of squeezed states with group-theoretical coherent states of the symplectic group and the relation ... More
Spinfoams in the holomorphic representationApr 26 2010Nov 25 2010We study a holomorphic representation for spinfoams. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mour\~ao-Thiemann coherent state transform. We derive the expression of the 4d spinfoam vertex for Euclidean and for Lorentzian gravity ... More
Cooperative Spectrum Sensing Using Random Matrix TheoryMar 05 2008In this paper, using tools from asymptotic random matrix theory, a new cooperative scheme for frequency band sensing is introduced for both AWGN and fading channels. Unlike previous works in the field, the new scheme does not require the knowledge of ... More
Does the X-ray emission of the luminous quasar RBS 1124 originate in a mildly relativistic outflowing corona?Sep 16 2009We have observed the luminous (L_x ~ 6x10^44 erg/s) radio-quiet quasar RBS 1124 (z=0.208) with Suzaku. We report the detection of a moderately broad iron (Fe) line and of a weak soft X-ray excess. The X-ray data are very well described by a simple model ... More
XMM-Newton broad-band observations of NGC 7582: Nh variations and fading out of the active nucleusFeb 21 2007We present results from two XMM-Newton observations of the bright classical Seyfert 2 galaxy NGC 7582 taken four years apart (2001 May and 2005 April). We present the analysis of the high-resolution (0.3-1 keV) RGS and low-resolution (0.3-10 keV) EPIC ... More
Novel calibrations of virial black hole mass estimators in active galaxies based on X-ray luminosity and optical/NIR emission linesOct 11 2016Accurately weigh the masses of SMBH in AGN is currently possible for only a small group of local and bright broad-line AGN through reverberation mapping (RM). Statistical demographic studies can be carried out considering the empirical scaling relation ... More