Results for "Roberto Scaramella"

total 4689took 0.10s
Increasing the Lensing Figure of Merit through Higher Order Convergence MomentsFeb 08 2018The unprecedented quality, the increased dataset, and the wide area of ongoing and near future weak lensing surveys allows to move beyond the standard two points statistics thus making worthwhile to investigate higher order probes. As an interesting step ... More
Euclid & SKA SynergiesJan 16 2015Over the past few years two of the largest and highest fidelity experiments conceived have been approved for construction: Euclid is an ESA M-Class mission that will map three-quarters of the extra galactic sky with Hubble Space Telescope resolution optical ... More
Constraining the ages of the fireballs in the wake of the dIrr galaxy VCC1217 / IC3418Nov 07 2010A complex of Halpha emitting blobs with strong FUV excess is associated to the dIrr galaxy VCC1217 / IC3418 (Hester et al. 2010), and extends up to 17 Kpc in the South-East direction. These outstanding features can be morphologically divided into diffuse ... More
Testing the distance duality relation with present and future dataMay 09 2012The assumptions that "light propagates along null geodesics of the spacetime metric" and "the number of photons is conserved along the light path" lead to the distance duality relation (DDR), $\eta = D_L(z) (1 + z)^{-2}/D_A(z) = 1$, with $D_L(z)$ and ... More
Improving lensing cluster mass estimate with flexionJul 20 2016Gravitational lensing has long been considered as a valuable tool to determine the total mass of galaxy clusters. The shear profile as inferred from the statistics of ellipticity of background galaxies allows to probe the cluster intermediate and outer ... More
Constraining Modified Gravity with EuclidOct 27 2010Future proposed satellite missions as Euclid can offer the opportunity to test general relativity on cosmic scales through mapping of the galaxy weak lensing signal. In this paper we forecast the ability of these experiments to constrain modified gravity ... More
Calibration of colour gradient bias in shear measurement using HST/CANDELS dataAug 21 2017Apr 19 2018Accurate shape measurements are essential to infer cosmological parameters from large area weak gravitational lensing studies. The compact diffraction-limited point-spread function (PSF) in space-based observations is greatly beneficial, but its chromaticity ... More
Large Scale Peculiar Velocities: Effects from SuperclustersJul 25 1995We study the gravitational influence of very large scale structures, as traced by clusters of galaxies, on the Local Group [LG] motion and the large scale flows. We derive from the distribution of Abell clusters within $300~$Mpc/h the overdensity field ... More
On the solutions of the Cartan equation in Metric Affine GravitySep 28 2000In the Tucker-Wang approach to Metric Affine gravity we review some particular solutions of the Cartan equation for the non-riemannian part of the connection. As application we show how a quite general non Riemannian model gives a Proca type equation ... More
Non-Invariant Ground States, Thermal Average, and generalized Fermionic StatisticsOct 11 1999Nov 09 1999We present an approach to generalised fermionic statistics which relates the existence of a generalised statistical behaviour to non-invariant ground states. Considering the thermal average of an operatorial generalization of the Heisenberg algebra, we ... More
The Prabhakar or three parameter Mittag--Leffler function: theory and applicationAug 24 2017Oct 11 2017The Prabhakar function (namely, a three parameter Mittag-Leffler function) is investigated. This function plays a fundamental role in the description of the anomalous dielectric properties in disordered materials and heterogeneous systems manifesting ... More
Superconformal Vacua in N=2 Usp(4) Gauge TheoriesFeb 26 2004We study the dynamics of a confining vacuum in N=2 USp(4) gauge theory with n_f=4. The vacuum appears to be a deformed conformal theory with nonabelian gauge symmetry. The low-energy degrees of freedom consist of four nonabelian magnetic monopole doublets ... More
The Picard group of the universal abelian variety and the Franchetta conjecture for abelian varietiesMar 30 2016Apr 04 2016We compute the Picard group of the universal abelian variety over the moduli stack $\mathscr A_{g,n}$ of principally polarized abelian varieties over $\mathbb{C}$ with a symplectic principal level $n$-structure. We then prove that over $\mathbb{C}$ the ... More
Numerical simulations of flow reversal in Rayleigh--Bénard convectionDec 20 2006We investigate numerically the statistical properties of the large scale flow in Rayleigh--B\'enard convection. By using an external random perturbation on the temperature field, we were able to decrease the effective Prandtl number of the flow while ... More
Nonclassical dynamics of Bose condensates in an optical lattice in the superfluid regimeJun 14 2007A condensate in an optical lattice, prepared in the ground state of the superfluid regime, is stimulated first by suddenly increasing the optical lattice amplitude and then, after a waiting time, by abruptly decreasing this amplitude to its initial value. ... More
Majorana and the Infinite Component Wave EquationsOct 23 2006I review the paper of Majorana about relativistic particles with arbitrary spin written in 1932. The main motivation for this papers was the dissatisfaction about the negative energy solutions of the Dirac equation. As such, the paper became immediately ... More
Color Superconductivity in High Density QCDDec 15 2005Jan 18 2006We describe the effects of the strange quark mass and of color and electric neutrality on the superconducing phases of QCD. We discuss various phases pointing out the corresponding problems, typically arising from a chromomagnetic instability. We show ... More
Neumark Operators and Sharp Reconstructions, the finite dimensional caseMay 17 2010A commutative POV measure $F$ with real spectrum is characterized by the existence of a PV measure $E$ (the sharp reconstruction of $F$) with real spectrum such that $F$ can be interpreted as a randomization of $E$. This paper focuses on the relationships ... More
Bounded cohomology of discrete groupsOct 26 2016Bounded cohomology of groups was first defined by Johnson and Trauber during the seventies in the context of Banach algebras. As an independent and very active research field, however, bounded cohomology started to develop in 1982, thanks to the pioneering ... More
Automorphisms of the UHF algebra that do not extend to the Cuntz algebraMar 09 2010Automorphisms of the canonical core UHF-subalgebra F_n of the Cuntz algebra O_n do not necessarily extend to automorphisms of O_n. Simple examples are discussed within the family of infinite tensor products of (inner) automorphisms of the matrix algebras ... More
New Physics at the LHC: Strong vs Weak symmetry breakingAug 25 2009What kind of New Physics, if any, we expect to discover at the LHC? I will try to address this formidable question by re-formulating it as follows: is the breaking of the electroweak symmetry strong or weak ?
A topological approach to leading monomial idealsAug 02 2010Jun 01 2011We introduce a very natural topology on the set of total orderings of monomials of any algebra having a countable basis over a field. This topological space and some notable subspaces are compact. This topological framework allows us to deduce some finiteness ... More
Neutrino mass variability due to nonminimal coupling to spacetime curvature in neutrinophilic two-Higgs-doublet modelsOct 18 2013In neutrinophilic two-Higgs-doublet models, neutrinos acquire mass due to a Higgs field with vacuum expectation value of the order of 10^{-2} eV, corresponding to a Compton wavelength in the 10 micrometer range. This creates a situation in which nonminimal ... More
Are quantum measurements on macroscopic bodies feasible?Mar 26 2010Mar 29 2010The possibility to test quantum measurement theories is discussed in the more phenomenological framework of the quantum nondemolition theory. A simple test of the hypothesis of the state vector collapse is proposed by looking for deviations from the Boltzmann ... More
BlackfoldsJun 10 2011This is an introduction to the blackfold effective worldvolume theory for the dynamics of black branes, as well as its use as an approximate method for the construction of new black hole solutions. We also explain how the theory is useful for the analysis ... More
Black Hole Production at a TeVFeb 25 2003In this talk I briefly discuss some features of a striking signature of TeV quantum gravity/strings and large extra dimensions: the production of exotic objects such as black holes, and their stringy precursors, the string resonances at large masses which ... More
Black Hole Radiation On and Off the BraneSep 18 2000Sep 26 2000After a brief review of the description of black holes on branes, we examine the evaporation of a small black hole on a brane in a world with large extra dimensions. We show that, contrary to previous claims, most of the energy is radiated into the modes ... More
Black hole entropy as entanglement entropy: a holographic derivationMar 10 2006Apr 26 2006We study the possibility that black hole entropy be identified as entropy of entanglement across the horizon of the vacuum of a quantum field in the presence of the black hole. We argue that a recent proposal for computing entanglement entropy using AdS/CFT ... More
Bn-generalized geometry and G2(2)-structuresJan 15 2013Jul 29 2013We introduce the concept of G2(2)-structure on an orientable 3-manifold M using the setting of generalized geometry of type Bn, study their local deformation by making use of a Moser-type argument, and give a description of the cone of G2(2)-structures. ... More
Probing dark energy with future surveysJul 21 2006I review the observational prospects to constrain the equation of state parameter of dark energy and I discuss the potential of future imaging and redshift surveys. Bayesian model selection is used to address the question of the level of accuracy on the ... More
Cosmic Microwave Background Anisotropies: Beyond Standard ParametersOct 05 2004In the first part of this work, I review the theoretical framework of cosmological perturbation theory necessary to understand the generation and evolution of cosmic microwave background (CMB) anisotropies. Using analytical and numerical techniques, in ... More
Optical correlation techniques for the investigation of colloidal systemsJun 06 2013This review aims to provide a simple introduction to the application of optical correlation methods in colloidal science. In particular, I plan to show that full appraisal of the intimate relation between light scattering and microscopy allows designing ... More
X-ray properties of spiral galaxiesNov 01 2002X-ray studies of nearby spiral galaxies with star formation allow us to investigate temperature and spatial distribution of the hot diffuse plasma, and to carry out individual and statistical studies of different classes of discrete sources (low- and ... More
The optical emission lines as a probe of state transitions in black-hole candidatesJan 17 2001Optical spectroscopic studies of emission lines in black-hole candidates can help us investigate state transitions in those systems. Changes in the optical line profiles reflect changes in the geometry of the accretion flow, usually associated with X-ray ... More
Microcanonical Entropy and Dynamical Measure of Temperature for Systems with Two First IntegralsApr 30 2010Jul 19 2011We consider a generic classical many particle system described by an autonomous Hamiltonian $H(x^{_1},...,x^{_{N+2}})$ which, in addition, has a conserved quantity $V(x^{_1},...,x^{_{N+2}})=v$, so that the Poisson bracket $\{H,V \}$ vanishes. We derive ... More
Galactic positrons and electrons from astrophysical sources and dark matterOct 14 2009A very interesting puzzle about the origin of electron and positron cosmic rays is deduced from the latests experimental results. We model the propagation of such cosmic rays in terms of a successfully tested two--zone propagation model. Several theoretical ... More
Power Consumption of Virtualization Technologies: an Empirical InvestigationNov 04 2015Virtualization is growing rapidly as a result of the increasing number of alternative solutions in this area, and of the wide range of application field. Until now, hypervisor-based virtualization has been the de facto solution to perform server virtualization. ... More
Computing Quasidegrees of A-graded ModulesOct 26 2015We describe the main functions of the Macaulay2 package Quasidegrees. The purpose of this package is to compute the quasidegree set of a finitely generated A-graded module presented as the cokernel of a monomial matrix. We provide examples with motivation ... More
Relaxation models for Single Helical Reversed Field Pinch plasmasSep 24 2015Oct 26 2016In this paper a relaxation theory, proposed several years ago for plasmas where a single dominant mode is present, is revisited. The solutions of the related eigenvalue problem are numerically calculated and discussed. Although these solutions are very ... More
Measuring Inequality and SegregationAug 05 2015In this paper, I introduce the Divergence Index, a conceptually intuitive and methodologically rigorous measure of inequality and segregation. The index measures the difference between a distribution of interest and another empirical, theoretical, or ... More
On higher holonomy invariants in higher gauge theory IMay 08 2015This is the first of a series of two technical papers devoted to the analysis of holonomy invariants in strict higher gauge theory with end applications in higher Chern--Simons theory. For a flat 2--connection, we define the 2-holonomy of surface knots ... More
Cosmic Rays: What Gamma Rays Can SayDec 23 2014We will review the main channels of gamma ray emission due to the acceleration and propagation of cosmic rays, discussing the cases of both galactic and extra-galactic cosmic rays and their connection with gamma rays observations.
High-energy density implications of a gravitoweak unification scenarioDec 15 2014We discuss how a scenario recently proposed for the morphing of macroscopic gravitation into weak interactions at the attometer scale affects our current understanding of high-energy density phenomena. We find that the Yukawa couplings of the fundamental ... More
Cohomological invariants of hyperelliptic curves of genus 3Sep 08 2016We compute the cohomological invariants with coefficients in $\mathbb{Z}/p\mathbb{Z}$ of the stack $\mathscr{H}_3$ of hyperelliptic curves of genus $3$ over an algebraically closed field.
The Principle of Minimal Resistance in Non-Equilibrium ThermodynamicsJan 21 2015Analytical models describing the motion of colloidal particles in given velocity fields are presented. In addition to local approaches, leading to well known master equations such as the Langevin and the Fokker-Planck equations, a global description based ... More
A Lie based 4-dimensional higher Chern-Simons theoryDec 18 2015Feb 22 2016We present and study a model of 4-dimensional higher Chern-Simons theory, special Chern-Simons (SCS) theory, instances of which have appeared in the string literature, whose symmetry is encoded in a skeletal semistrict Lie 2-algebra constructed from a ... More
Bubbles and Knots in the Kinematical Structure of the Bipolar Planetary Nebula NGC 2818Mar 27 2012High-resolution Hubble Space Telescope (HST) archive imaging and high-dispersion spectroscopy are used to study the complex morphological and kinematical structure of the planetary nebula, NGC 2818. We analyze narrow band H{\alpha}, [O III], [N II], [S ... More
Matching electroweak fermion loops onto the Fermi theory without higher dimensional operatorsFeb 05 2019We match, at the one-fermion-loop accuracy, the electroweak theory onto the nonrenormalizable four-fermion Fermi model. The matching is performed without introducing higher dimensional interaction terms in the Fermi Lagrangian. As a result, an effective ... More
Entropy of Coherent ExcitationsJan 08 2019We provide a rigorous, explicit formula for the vacuum relative entropy of a coherent state on wedge local von Neumann algebras associated with a free, neutral quantum field theory on the Minkowski spacetime of arbitrary spacetime dimension. The second ... More
Scaling Distances on Finitely Ramified FractalsAug 31 2015Nov 06 2015In previous papers by A. Kameyama and by J. Kigami distances on fractals have been discussed having two different but similar properties. One property is that the maps defining the fractal are Lipschitz of prescribed constants less than 1, the other is ... More
Anisotropic Color SuperconductivityJan 20 2003We discuss the possibility that in finite density QCD an anisotropic phase is realized. This case might arise for quarks with different chemical potential and/or different masses. In this phase crystalline structures may be formed. We consider this possibility ... More
Uniform continuity of POVMsJul 22 2013Recently a characterization of uniformly continuous POVMs and a necessary condition for a uniformly continuous POVM $F$ to have the norm-1 property have been provided. Moreover it was proved that in the commutative case, uniform continuity corresponds ... More
KAM for quasi-linear forced hamiltonian NLSFeb 03 2016In this paper we prove the existence of quasi-periodic, small-amplitude, solutions for quasi-linear Hamiltonian perturbations of the non-linear Schoedinger equation on the torus in presence of a quasi-periodic forcing. In particular we prove that such ... More
Z', Z_KK, Z* and all that: current bounds and theoretical prejudices on heavy neutral vector bosonsApr 20 2008I review the current experimental bounds and theoretical predictions for different kinds of heavy neutral vector bosons.
Universal Groebner Bases in Weyl AlgebrasNov 23 2010Jun 01 2011A topological space TO(S) of total orderings on any given set S is introduced and it is shown that TO(S) is compact if S is countable. The set NO(N) of all normal orderings of the nth Weyl algebra W is a closed subspace of TO(N), where N is the set of ... More
AdS/CFT Duals of Topological Black Holes and the Entropy of Zero-Energy StatesJun 04 1999Jun 09 1999The horizon of a static black hole in Anti-deSitter space can be spherical, planar, or hyperbolic. The microscopic dynamics of the first two classes of black holes have been extensively discussed recently within the context of the AdS/CFT correspondence. ... More
Absorption of Scalars by Extended ObjectsJun 27 1997We derive the low energy absorption cross section of minimal scalars for a very generic class of geometries, that includes, among others, black holes, strings, $p$-branes, as well as intersecting brane configurations. The scalar field can be absorbed ... More
Black Holes as Fundamental Strings: Comparing the Absorption of ScalarsApr 29 1997Jul 16 1997The recently proposed ``correspondence principle'' of Horowitz and Polchinski provides a concrete means to relate (among others) black holes with electric NS-NS charges to fundamental strings and correctly match their entropies. We test further this correspondence ... More
Tubular Branes in FluxbranesMay 07 2001May 10 2001We describe the construction of new configurations of self-gravitating p-branes with worldvolume geometries of the form R^{1,p-s} x S^s, with 1\leq s\leq p, ie, tubular branes. Since such branes are typically unstable against collapse of the sphere, they ... More
AdS Membranes Wrapped on Surfaces of Arbitrary GenusApr 03 1998Apr 13 1998We present and analyze solutions of D=11 supergravity describing the ``near-horizon'' (i.e., asymptotically AdS_4 x S^7) geometry of M2-branes wrapped on surfaces of arbitrary genus. We study the forces experienced by test M2-branes in such backgrounds, ... More
Higgs-induced spectroscopic shifts near strong gravity sourcesNov 12 2010We explore the consequences of the mass generation due to the Higgs field in strong gravity astrophysical environments. The vacuum expectation value of the Higgs field is predicted to depend on the curvature of spacetime, potentially giving rise to peculiar ... More
Massless radiation from Strings: quantum spectrum average statistics and cusp-kink configurationsFeb 13 2006May 10 2006We derive general formulae for computing the average spectrum for Bosonic or Fermionic massless emission from generic or particular sets of closed superstring quantum states, among the many occurring at a given large value of the number operator. In particular ... More
Geometric Microcanonical Thermodynamics for Systems with First IntegralsApr 27 2012May 11 2012In the general case of a many-body Hamiltonian system, described by an autonomous Hamiltonian $H$, and with $K\geq 0$ independent conserved quantities, we derive the microcanonical thermodynamics. By a simple approach, based on the differential geometry, ... More
Congruences involving the reciprocals of central binomial coefficientsJun 28 2009Dec 20 2009We present several congruences modulo a power of prime $p$ concerning sums of the following type $\sum_{k=1}^{p-1}{m^k\over k^r}{2k\choose k}^{-1}$ which reveal some interesting connections with the analogous infinite series.
A needlet-based approach to the full-sky data analysisDec 01 2011In cosmic-ray physics, large field of view experiments are triggered by a number of signals laying on different angular scales: point-like and extended gamma-ray sources, diffuse emissions, as well as large and intermediate scale cosmic-ray anisotropies. ... More
A Study on Learnability for Rigid Lambek GrammarsAug 06 2006We present basic notions of Gold's "learnability in the limit" paradigm, first presented in 1967, a formalization of the cognitive process by which a native speaker gets to grasp the underlying grammar of his/her own native language by being exposed to ... More
Countable Borel equivalence relations and quotient Borel spacesDec 28 2005We consider countable Borel equivalence relations on quotient Borel spaces. We prove a generalization of the Feldman-Moore representation theorem, but provide some examples showing that other very simple properties of countable equivalence relations on ... More
AKSZ models of semistrict higher gauge theoryDec 13 2011Nov 10 2012In the first part of this paper, we work out a perturbative Lagrangian formulation of semistrict higher gauge theory, that avoids the subtleties of the relationship between Lie 2-groups and algebras by relying exclusively on the structure semistrict Lie ... More
Exact invariant measures: How the strength of measure settles the intensity of chaosJun 10 2015Jun 23 2015The aim of this paper is to show how extracting dynamical behavior and ergodic properties from deterministic chaos with the assistance of exact invariant measures. On the one hand, we provide an approach to deal with the inverse problem of finding nonlinear ... More
Local trace formulae for commuting Hamiltonians in Töplitz quantizationDec 12 2014Oct 20 2016Let $(M,J,\omega)$ be a quantizable compact K\"ahler manifold, with quantizing Hermitian line bundle $(A,h)$, and associated Hardy space $H(X)$, where $X$ is the unit circle bundle. Given a collection of $r$ Poisson commuting quantizable Hamiltonian functions ... More
A Performance Evaluation of Container Technologies on Internet of Things DevicesMar 09 2016The use of virtualization technologies in different contexts - such as Cloud Environments, Internet of Things (IoT), Software Defined Networking (SDN) - has rapidly increased during the last years. Among these technologies, container-based solutions own ... More
Neutrinos at extreme energiesJan 19 2016We will review the production of neutrinos with PeV energies and above. Discussing two possible sources of this radiation: the propagation of ultra high energy cosmic rays and the decay of super heavy dark matter. The discussion will focus on the theoretical ... More
Wish-list for Run II top quark measurements (for BSM)Jan 11 2016In this contribution I will highlight the new challenges for top quark physics at LHC Run II, focusing in particular on the interplay between precision studies on the top quark and searches for new physics. A new strategy to search for subtle scenarios ... More
A Factorization Approach to Inertial Affine Structure from MotionAug 09 2016We consider the problem of reconstructing a 3-D scene from a moving camera with high frame rate using the affine projection model. This problem is traditionally known as Affine Structure from Motion (Affine SfM), and can be solved using an elegant low-rank ... More
The Critical Current of Point Symmetric Josephson Tunnel JunctionsJun 08 2016The physics of Josephson tunnel junctions drastically depends on their geometrical configurations. The shape of the junction determines the specific form of the magnetic-field dependence of the its Josephson current. Here we address the magnetic diffraction ... More
Galactic positrons and electrons from dark matter and astrophysical sourcesJul 25 2009The electron and positron cosmic rays observations have impulsed a hot debate regarding the origin of such particles. Their propagation in the galactic medium is modeled according to a successfully tested two--zone propagation model. The theoretical uncertainties ... More
Spatial Boundaries and the Local Context of Residential SegregationSep 08 2015Spatial boundaries are a defining feature of a city's social and spatial organization. Rivers, highways, and train tracks create excess distance between nearby locations and often mark social separation -- they become dividing lines that are well known ... More
Some $q$-analogs of congruences for central binomial sumsJan 30 2012We establish $q$-analogs for four congruences involving central binomial coefficients. The $q$-identities necessary for this purpose are shown via the $q$-WZ method.
An elementary proof of a Rodriguez-Villegas supercongruenceNov 22 2009We give a short proof of the following known congruence: for every odd prime $p$ $$\sum_{k=0}^{p-1}{2k\choose k}^2 16^{-k}\equiv (-1)^{{p-1\over 2}}\pmod{p^2}.$$ Moreover, we provide some new results connected with the above congruence.
Cohomological invariants of hyperelliptic curves of even genusNov 26 2014May 17 2016Let $g$ be an even positive integer, and $p$ be a prime number. We compute the cohomological invariants with coefficients in $\mathbb{Z}/p\mathbb{Z}$ of the stacks of hyperelliptic curves $\mathscr{H}_g$ over an algebraically closed field $k_0$.
On deformations of hyperbolic 3-manifolds with geodesic boundaryApr 06 2005Mar 06 2009Let M be a complete finite-volume hyperbolic 3-manifold with compact non-empty geodesic boundary and k toric cusps, and let T be a geometric partially truncated triangulation of M. We show that the variety of solutions of consistency equations for T is ... More
Scalar field-perfect fluid correspondence and nonlinear perturbation equationsJun 03 2008The properties of dynamical Dark Energy (DE) and, in particular, the possibility that it can form or contribute to stable inhomogeneities, have been widely debated in recent literature, also in association to a possible coupling between DE and Dark Matter ... More
The connection between combinatorics and cohomology of elliptic arrangementsMay 13 2018Jan 07 2019We prove that the cohomology algebra of elliptic arrangements depends only on the poset of layers. In the particular case of braid elliptic arrangements, we study the cohomology as representation and we compute some Hodge numbers. Finally, we discuss ... More
A supercongruence involving cubes of Catalan numbersJun 28 2018Jul 31 2018We mainly show a supercongruence for a truncated series with cubes of Catalan numbers which extends a result by Zhi-Wei Sun.
Notes for a Quantum Index TheoremMar 14 2000Nov 14 2005We view DHR superselection sectors with finite statistics as Quantum Field Theory analogs of elliptic operators where KMS functionals play the role of the trace composed with the heat kernel regularization. We extend our local holomorphic dimension formula ... More
On Landauer's principle and bound for infinite systemsOct 02 2017Jan 15 2018Landauer's principle provides a link between Shannon's information entropy and Clausius' thermodynamical entropy. We set up here a basic formula for the incremental free energy of a quantum channel, possibly relative to infinite systems, naturally arising ... More
Gravitational collapse of homogeneous perfect fluid in HOG theoriesNov 27 2008This paper investigates the evolution of collapsing FRW models with a scalar field having the potential which arises in the conformal frame of high order gravity theories, coupled to matter described by a perfect fluid with energy density $\rho$ and pressure ... More
Gravitational collapse of homogeneous scalar fieldsJan 05 2005May 27 2005Conditions under which gravity coupled to self interacting scalar field determines singularity formation are found and discussed. It is shown that, under a suitable matching with an external space, the boundary, if collapses completely, may give rise ... More
On the independence of a generalized statement of Egoroff's theorem from ZFC, after T.WeissDec 23 2005We consider a generalized version (GES) of the wellknown Severini-Egoroff theorem in real analysis, first shown to be undecidable in ZFC by Tomasz Weiss. This independence is easily derived from suitable hypotheses on some cardinal characteristics of ... More
The impact of atomic precision measurements in high energy physicsJul 11 2000Jul 14 2000In this talk I discuss the relevance of atomic physics in understanding some important questions about elementary particle physics. A particular attention is devoted to atomic parity violation measurements which seem to suggest new physics beyond the ... More
On a conjecture of VarchenkoMar 26 1995In this note we generalize and prove a recent conjecture of Varchenko concerning the number of critical points of a (multivalued) meromorphic function $\phi$ on an algebraic manifold. Under certain conditions, this number turns out to coincide with the ... More
Casimir forces and non-Newtonian gravitationDec 19 2006The search for non-relativistic deviations from Newtonian gravitation can lead to new phenomena signalling the unification of gravity with the other fundamental interactions. Various recent theoretical frameworks indicate a possible window for non-Newtonian ... More
Exact Microscopic Entropy of Non-Supersymmetric Extremal Black RingsMar 12 2008Apr 16 2008In this brief note we show that the horizon entropy of the largest known class of non-supersymmetric extremal black rings, with up to six parameters, is exactly reproduced for all values of the ring radius using the same conformal field theory of the ... More
Applications of Bayesian model selection to cosmological parametersApr 01 2005May 09 2007Bayesian model selection is a tool to decide whether the introduction of a new parameter is warranted by data. I argue that the usual sampling statistic significance tests for a null hypothesis can be misleading, since they do not take into account the ... More
Computing the R^4 term at two Superstring LoopsFeb 09 2002We use a previously derived integral representation for the four graviton amplitude at two loops in Superstring theory, whose leading term for vanishing momenta gives the two-loop contribution to the R^4 term in the Effective Action. We find by an explicit ... More
A note on measure homologyApr 27 2012Measure homology was introduced by Thurston in order to compute the simplicial volume of hyperbolic manifolds. Berlanga endowed measure homology with a structure of graded locally convex (possibly non-Hausdorff) topological vector space. In this note ... More
Lorentzian LQG vertex amplitudeOct 26 2007Dec 08 2009We generalize a model recently proposed for Euclidean quantum gravity to the case of Lorentzian signature. The main features of the Euclidean model are preserved in the Lorentzian one. In particular, the boundary Hilbert space matches the one of SU(2) ... More
Hard and soft spectral states of ULXsSep 29 2010I discuss some differences between the observed spectral states of ultraluminous X-ray sources (ULXs) and the canonical scheme of spectral states defined in Galactic black holes. The standard interpretation of ULXs with a curved spectrum, or a moderately ... More
Runaway core collapse and cluster survival: where are the parent clusters of ULXs?Mar 16 2005Accreting intermediate-mass black holes (IMBHs) have been proposed as an explanation for ultraluminous X-ray sources (ULXs). Runaway core collapse inside a massive cluster is a possible mechanism for IMBH formation. But if so, why are ULXs only rarely ... More
A note on diastatic entropy and balanced metricsMar 13 2013Oct 19 2014We give un upper bound Ent(\Omega, g)<\lambda\ of the diastatic entropy Ent(\Omega, g) of a complex bounded domain (\Omega, g) in terms of the balanced condition (in Donaldson terminology) of the Kaehler metric \lambda g. When (\Omega, g) is a homogeneous ... More