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On the classical and quantum momentum mapMar 19 2012In this thesis we study the classical and quantum momentum maps and the theory of reduction. We focus on the notion of momentum map in Poisson geometry and we discuss the classification of the momentum map in this framework. Furthermore, we describe the ... More

Infinite energy solutions to vortex equations governing the fractional quantum Hall effectOct 30 2018In this paper, we utilize weighted Sobolev spaces to establish an existence theory for infinite energy solutions to a coupled non-linear elliptic system. This system describes the fractional quantum Hall effect in two-dimensional double-layered systems. ... More

An introduction to quantum gravityAug 16 2011Quantum gravity was born as that branch of modern theoretical physics that tries to unify its guiding principles, i.e., quantum mechanics and general relativity. Nowadays it is providing new insight into the unification of all fundamental interactions, ... More

A new application of non-canonical maps in quantum mechanicsSep 07 2001Oct 22 2001A proof is given that an invertible and a unitary operator can be used to reproduce the effect of a q-deformed commutator of annihilation and creation operators. In other words, the original annihilation and creation operators are mapped into new operators, ... More

Towards a Spectral Proof of the Mass Gap in QCD?Jul 09 2001Nov 26 2001Yang--Mills theory in four dimensions is studied by using the Coulomb gauge. The Coulomb gauge Hamiltonian involves integration of matrix elements of an operator P built from the Laplacian and from a first-order differential operator. The operator P is ... More

Local Boundary Conditions in Quantum SupergravityAug 12 1996When quantum supergravity is studied on manifolds with boundary, one may consider local boundary conditions which fix on the initial surface the whole primed part of tangential components of gravitino perturbations, and fix on the final surface the whole ... More

Non-Local Properties in Euclidean Quantum GravityAug 28 1995Sep 24 1995In the one-loop approximation for Euclidean quantum gravity, the boundary conditions which are completely invariant under gauge transformations of metric perturbations involve both normal and tangential derivatives of the metric perturbations $h_{00}$ ... More

The Geometry of Complex Space-Times with TorsionAug 14 1995The necessary and sufficient condition for the existence of $\alpha$-surfaces in complex space-time manifolds with nonvanishing torsion is derived. For these manifolds, Lie brackets of vector fields and spinor Ricci identities contain explicitly the effects ... More

Singularity Theory in Classical CosmologyJul 01 1995This paper compares recent approaches appearing in the literature on the singularity problem for space-times with nonvanishing torsion.

A classification result for the quasi-linear Liouville equationSep 12 2016Entire solutions of the $n-$Laplace Liouville equation in $\mathbb{R}^n$ with finite mass are completely classified.

A spinorial perspective on massless photonsJan 02 2007We exploit the fact that, in Minkowski space-time, gamma matrices are possibly more fundamental than the metric to describe how gauge invariance at perturbative level enforces a Lagrangian for spinor electrodynamics with massless photons. The term quadratic ... More

New Photon Propagators in Quantum ElectrodynamicsNov 25 2005A Lagrangian for quantum electrodynamics is found which makes it explicit that the photon mass is eventually set to zero in the physical part on observational ground. It remains possible to obtain a counterterm Lagrangian where the only non-gauge-invariant ... More

Quantum cosmology from three different perspectivesMay 10 2006Our review is devoted to three promising research lines in quantum cosmology and the physics of the early universe. The nonperturbative renormalization programme is making encouraging progress that we here assess from the point of view of cosmological ... More

From Spinor Geometry to Complex General RelativityApr 11 2005May 23 2005An attempt is made of giving a self-contained (although incomplete) introduction to holomorphic ideas in general relativity, following work over the last thirty years by several authors. The main topics are complex manifolds, two-component spinor calculus, ... More

Spectral Properties of Yang-Mills TheorySep 21 2001Jun 16 2005This paper was withdrawn. It has been superseded by the latest version of hep-th/0107069.

Boundary Operators in Quantum Field TheoryJan 14 2000Apr 19 2000The fundamental laws of physics can be derived from the requirement of invariance under suitable classes of transformations on the one hand, and from the need for a well-posed mathematical theory on the other hand. As a part of this programme, the present ... More

Quantization and Regularization in Perturbative Quantum CosmologyAug 15 1995Reduction to physical degrees of freedom before quantization leads to predictions for one-loop amplitudes in quantum cosmology in the presence of boundaries which disagree with the results obtained from Faddeev-Popov theory and boundary-counterterms technique. ... More

Dirac Operator and Eigenvalues in Riemannian GeometryJul 24 1995The aim of the lectures is to introduce first-year Ph.D. students and research workers to the theory of the Dirac operator, spinor techniques, and their relevance for the theory of eigenvalues in Riemannian geometry. Topics: differential operators on ... More

New Kernels in Quantum GravityJun 22 1999Aug 23 1999Recent work in the literature has proposed the use of non-local boundary conditions in Euclidean quantum gravity. The present paper studies first a more general form of such a scheme for bosonic gauge theories, by adding to the boundary operator for mixed ... More

Nonlocal Ghost Formalism for Quantum GravitySep 29 1998Jul 11 1999The quantum theory of a free particle on a portion of two-dimensional Euclidean space bounded by a circle and subject to non-local boundary conditions gives rise to bulk and surface states. Starting from this well known property, a counterpart for gravity ... More

Dirac Operator and Spectral GeometryApr 02 1997Dec 16 2000This paper is devoted to mathematical and physical properties of the Dirac operator and spectral geometry. Spin-structures in Lorentzian and Riemannian manifolds, and the global theory of the Dirac operator, are first analyzed. Elliptic boundary-value ... More

Quantization of Field Theories in the Presence of BoundariesJun 23 1995This paper reviews the progress made over the last five years in studying boundary conditions and semiclassical properties of quantum fields about 4-real-dimensional Riemannian backgrounds. For massless spin-${1\over 2}$ fields one has a choice of spectral ... More

Analysis of Motion Planning by Sampling in Subspaces of Progressively Increasing DimensionJan 30 2018Despite the performance advantages of modern sampling-based motion planners, solving high dimensional planning problems in near real-time remains a challenge. Applications include hyper-redundant manipulators, snake-like and humanoid robots. Based on ... More

Variability of the transitional T Tauri star T ChamaeleontisApr 01 2009Apr 14 2009We characterize the physical properties of T Chamaeleontis, a transitional T Tauri star showing UX Ori-type variability, and of its associated disc, and probe possible effects of disc clearing processes. Different spectral diagnostics are examined, based ... More

BS Indi: An enigmatic objectDec 13 2004BS Ind is a young K0V star in the Tucana association. Photometric observations with the Hipparcos satellite show an eclipse-like light-curve with primary and secondary eclipse. The eclipsing binary has a period of 0.435338 days and a circular orbit. Our ... More

Five years of SGR 1900+14 observations with BeppoSAXSep 04 2006We present a systematic analysis of all the BeppoSAX data of the soft gamma-ray repeater SGR 1900+14: these observations allowed us to study the long term properties of the source quiescent emission. In the observation carried out before the 1998 giant ... More

Discovery of a 6.4 h black hole binary in NGC 4490Sep 24 2013Oct 10 2013We report on the discovery with Chandra of a strong modulation (~90% pulsed fraction) at ~6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular companion NGC 4485. ... More

New fully empirical calibrations of strong-line metallicity indicators in star forming galaxiesOct 21 2016We derive new empirical calibrations for strong-line diagnostics of gas phase metallicity in local star forming galaxies by uniformly applying the Te method over the full metallicity range probed by the Sloan Digital Sky Survey (SDSS). To measure electron ... More

On a quasilinear mean field equation with exponential nonlinearityOct 24 2014The mean field equation involving the $N$-Laplace operator and an exponential nonlinearity is considered in dimension $N\geq2$ on bounded domains with homogenoeus Dirichlet boundary condition. By a detailed asymptotic analysis we derive a quantization ... More

Non-Markovianity and negative entropy production ratesJun 24 2018Nov 08 2018Entropy production plays a fundamental role in nonequilibrium thermodynamics to quantify the irreversibility of open systems. Its positivity can be ensured for a wide class of setups, but the entropy production rate can become negative sometimes. This ... More

A pedagogical introduction to the Slavnov formulation of quantum Yang-Mills theorySep 21 2010Over the last few years, Slavnov has proposed a formulation of quantum Yang-Mills theory in the Coulomb gauge which preserves simultaneously manifest Lorentz invariance and gauge invariance of the ghost field Lagrangian. This paper presents in detail ... More

Scalar Casimir effect with non-local boundary conditionsApr 13 2006Apr 18 2006Non-local boundary conditions have been considered in theoretical high-energy physics with emphasis on one-loop quantum cosmology, one-loop conformal anomalies, Bose-Einstein condensation models and spectral branes. We have therefore studied the Wightman ... More

Chiral bag boundary conditions on the ballJul 11 2002Local boundary conditions for spinor fields are expressed in terms of a 1-parameter family of boundary operators, and find applications ranging from (supersymmetric) quantum cosmology to the bag model in quantum chromodynamics. The present paper proves ... More

Non-Locality and Ellipticity in a Gauge-Invariant QuantizationJul 29 1999The quantum theory of a free particle in two dimensions with non-local boundary conditions on a circle is known to lead to surface and bulk states. Such a scheme is here generalized to the quantized Maxwell field, subject to mixed boundary conditions. ... More

New Supplementary Conditions for a Non-Linear Field Theory: General RelativityJun 26 1999The Einstein theory of general relativity provides a peculiar example of classical field theory ruled by non-linear partial differential equations. A number of supplementary conditions (more frequently called gauge conditions) have also been considered ... More

Inflationary Solutions in Quantum CosmologySep 02 1995We prove that in the Hartle-Hawking approach to quantum cosmology the existence of an inflationary phase is a general property of minisuperspace models given by a closed Friedmann-Robertson-Walker universe containing a massless scalar field with a $\lambda\phi^{n}$ ... More

Twistors and Spin 3/2 Potentials in Quantum GravityJun 27 1995Local boundary conditions involving field strengths and the normal to the boundary, originally studied in anti-de Sitter space-time, have been recently considered in one-loop quantum cosmology. This paper derives the conditions under which spin-lowering ... More

Universality in driven Potts modelsNov 14 2018Feb 26 2019We study the stochastic dynamics of infinitely many globally interacting $q$-state units on a ring that is externally driven. While repulsive interactions always lead to uniform occupations, attractive interactions give rise to much richer phenomena: ... More

Affine hyperplane arrangements and Jordan classesJul 27 2018We study the geometry of the stratification induced by an affine hyperplane arrangement $H$ on the quotient of a complex affine space by the action of a group preserving $H$. We give conditions ensuring normality of strata. As an application, we determine ... More

Majorana, Pauling and the quantum theory of the chemical bondJun 26 2013We discuss in detail very little known results obtained by Majorana as early as 1931, regarding the quantum theory of the chemical bond in homopolar molecules, based on the key concept of exchange interaction. After a brief historical overview of the ... More

Pseudo-differential operators with nonlinear quantizing functionsMar 17 2018In this paper we develop the calculus of pseudo-differential operators corresponding to the quantizations of the form $$ Au(x)=\int_{\mathbb{R}^n}\int_{\mathbb{R}^n}e^{i(x-y)\cdot\xi}\sigma(x+\tau(y-x),\xi)u(y)dyd\xi, $$ where $\tau:\mathbb{R}^n\to\mathbb{R}^n$ ... More

Nonlocal quantum field theory without acausality and nonunitarity at quantum level: is SUSY the key?Feb 05 2015Mar 13 2015The realization of a nonlocal quantum field theory without losing unitarity, gauge invariance and causality is investigated. It is commonly retained that such a formulation is possible at tree level, but at quantum level acausality reappears at one loop. ... More

Highlights of Symmetry GroupsNov 21 2005The concepts of symmetry and symmetry groups are at the heart of several developments in modern theoretical and mathematical physics. The present paper is devoted to a number of selected topics within this framework: Euclidean and rotation groups; the ... More

The Role of Elliptic Operators in the Initial-Value Problem for General RelativityDec 18 2000The Arnowitt-Deser-Misner (ADM) equations are deeply intertwined with discrete spectral resolutions of an elliptic operator of Laplace type associated with the spacelike hypersurfaces which foliate the space-time manifold, and the non-linearities of the ... More

New Gauge Conditions in General Relativity: What Can We Learn from Them?Oct 08 1999The construction of conformally invariant gauge conditions for Maxwell and Einstein theories on a manifold M is found to involve two basic ingredients. First, covariant derivatives of a linear gauge (e.g. Lorenz or de Donder), completely contracted with ... More

A New Family of Gauges in Linearized General RelativityDec 12 1998Aug 24 1999For vacuum Maxwell theory in four dimensions, a supplementary condition exists (due to Eastwood and Singer) which is invariant under conformal rescalings of the metric, in agreement with the conformal symmetry of the Maxwell equations. Thus, starting ... More

Rigidity of infinitesimal momentum mapsOct 20 2014Sep 11 2015In this paper we prove rigidity theorems for Poisson Lie group actions on Poisson manifolds. In particular, we prove that close infinitesimal momentum maps associated to Poisson Lie group actions are equivalent using a normal form theorem for SCI spaces. ... More

Towards obtaining Green functions for a Casimir cavity in de Sitter spacetimeSep 22 2014Dec 02 2014Recent work in the literature has studied rigid Casimir cavities in a weak gravitational field, or in de Sitter spacetime, or yet other spacetime models. The present review paper studies the difficult problem of direct evaluation of scalar Green functions ... More

SXP7.92: A Recently Rediscovered Be/X-ray Binary in the Small Magellanic Cloud, Viewed Edge OnJan 06 2017We present a detailed optical and X-ray study of the 2013 outburst of the Small Magellanic Cloud Be/X-ray binary SXP7.92, as well as an overview of the last 18 years of observations from OGLE, RXTE, Chandra and XMM-Newton. We revise the position of this ... More

Work producing reservoirs: Stochastic thermodynamics with generalized Gibbs ensemblesJul 29 2016We develop a consistent stochastic thermodynamics for environments composed of thermodynamic reservoirs in an external conservative force field, that is environments described by the Generalized or Gibbs canonical ensemble. We demonstrate that small systems ... More

Thermodynamics with continuous information flowFeb 13 2014Jun 30 2014We provide a unified thermodynamic formalism describing information transfers in autonomous as well as nonautonomous systems described by stochastic thermodynamics. We demonstrate how information is continuously generated in an auxiliary system and then ... More

Geometry and physics of pseudodifferential operators on manifoldsSep 18 2015Mar 08 2016A review is made of the basic tools used in mathematics to define a calculus for pseudodifferential operators on Riemannian manifolds endowed with a connection: esistence theorem for the function that generalizes the phase; analogue of Taylor's theorem; ... More

Magnetar-like X-ray bursts suppress pulsar radio emissionOct 10 2017Rotation-powered pulsars and magnetars are two different observational manifestations of neutron stars: rotation powered pulsars are rapidly spinning objects that are mostly observed as pulsating radio sources, while magnetars, neutron stars with the ... More

Calibration of the cross-resonance two-qubit gate between directly-coupled transmonsMay 14 2019Quantum computation requires the precise control of the evolution of a quantum system, typically through application of discrete quantum logic gates on a set of qubits. Here, we use the cross-resonance interaction to implement a gate between two superconducting ... More

Averaging procedure in variable-G cosmologiesMay 08 2008Oct 20 2008Previous work in the literature had built a formalism for spatially averaged equations for the scale factor, giving rise to an averaged Raychaudhuri equation and averaged Hamiltonian constraint, which involve a backreaction source term. The present paper ... More

Revisited version of Weyl's limit point-limit circle criterion for essential self-adjointnessOct 08 2018Mar 14 2019A new proof of the Weyl limit point-limit circle criterion is obtained, with systematic emphasis on Sobolev-space methods.

Universal Functions in Euclidean Quantum GravityFeb 20 1997A key problem in the attempt to quantize the gravitational field is the choice of boundary conditions. These are mixed, in that spatial and normal components of metric perturbations obey different sets of boundary conditions. In the covariant quantization ... More

Quadrature With Respect to Binomial MeasuresDec 07 2006Mar 19 2008This work is devoted to the study of integration with respect to binomial measures. We develop interpolatory quadrature rules and study their properties. Local error estimates for these rules are derived in a general framework.

Planets of young starsJan 10 2007Since the first massive planet in a short period orbit was discovered, the question arised how such an object could have formed. There are basically two formation scenarios: migration due to planet-disk or planet-planet interaction. Which of the two scenarios ... More

One-loop analysis with nonlocal boundary conditionsDec 10 2018Feb 13 2019In the eighties, Schroder studied a quantum mechanical model where the stationary states of Schrodinger's equation obey nonlocal boundary conditions on a circle in the plane. For such a problem, we perform a detailed one-loop calculation for three choices ... More

An introduction to quantum gravityNov 15 2007After an overview of the physical motivations for studying quantum gravity, we reprint THE FORMAL STRUCTURE OF QUANTUM GRAVITY, i.e. the 1978 Cargese Lectures by Professor B.S. DeWitt, with kind permission of Springer. The reader is therefore introduced, ... More

Ellipticity Conditions for the Lax Operator of the KP EquationsApr 07 2000The Lax pseudo-differential operator plays a key role in studying the general set of KP equations, although it is normally treated in a formal way, without worrying about a complete characterization of its mathematical properties. The aim of the present ... More

Equilibria of point-vortices on closed surfacesFeb 19 2015We discuss the existence of equilibrium configurations for the Hamiltonian point-vortex model on a closed surface $\Sigma$. The topological properties of $\Sigma$ determine the occurrence of three distinct situations, corresponding to $\mathbb{S}^2$, ... More

Radiation Induced Fermion ResonanceMar 27 1998The Dirac equation is solved for two novel terms which describe the interaction energy between the half integral spin of a fermion and the classical, circularly polarized, electromagnetic field. A simple experiment is suggested to test the new terms and ... More

On the relation between event-based and time-based current statisticsSep 23 2009Mar 01 2010Current statistics can be calculated in various ways. Event-based approaches use the statistics of the number of events occuring during a given time. Time-based approaches use the statistics of the time needed to reach a given number of events. By analyzing ... More

Phase time and transmission probability in the traversal of a PT-symmetric potential: the case of an electromagnetic waveguideOct 02 2017We study the unconventional transmission properties of a wave-packet through a PT-symmetric potential region, as describing actual electromagnetic wave propagation along a waveguide filled with gain and loss media. The non-trivial behavior of the transmission ... More

Zirconia UV-curable colloids for additive manufacturing via hybrid inkjet printing-stereolithographyMar 18 2019Currently, additive manufacturing of ceramics by stereolithography (SLA) is limited to single materials and by a poor thickness resolution that strongly depends on the ceramic particles-UV light interaction. Combining selective laser curing with inkjet ... More

Ultrafast transient increase of oxygen octahedral rotations in a perovskiteJan 24 2019The ability to control the structure of a crystalline solid on ultrafast timescales bears enormous potential for information storage and manipulation or generating new functional states of matter [1]. In many materials where the ultrafast control of crystalline ... More

Majorana and the theoretical problem of photon-electron scatteringJan 27 2015Relevant contributions by Majorana regarding Compton scattering off free or bound electrons are considered in detail, where a (full quantum) generalization of the Kramers-Heisenberg dispersion formula is derived. The role of intermediate electronic states ... More

Energy-momentum tensor of a Casimir apparatus in a weak gravitational field: scalar caseMar 06 2008Recent work in the literature had evaluated the energy-momentum tensor of a Casimir apparatus in a weak gravitational field, for an electromagnetic field subject to perfect conductor boundary conditions on parallel plates. The Casimir apparatus was then ... More

Energy-momentum tensor for a scalar Casimir apparatus in a weak gravitational field: Neumann conditionsOct 16 2008Nov 03 2008We consider a Casimir apparatus consisting of two perfectly conducting parallel plates, subject to the weak gravitational field of the Earth. The aim of this paper is the calculation of the energy-momentum tensor of this system for a free, real massless ... More

Energy Deposition and Radiation to ElectronicsMay 26 2017Chapter 10 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered ... More

The photoinduced transition in magnetoresistive manganites: a comprehensive viewOct 27 2017We use femtosecond x-ray diffraction to study the structural response of charge and orbitally ordered Pr$_{1-x}$Ca$_x$MnO$_3$ thin films across a phase transition induced by 800 nm laser pulses. By investigating the dynamics of both superlattice reflections ... More

Optical control of vibrational coherence triggered by an ultrafast phase transitionFeb 01 2019Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of the periodic lattice distortion (PLD) associated with the charge-density-wave (CDW) in K0.3MoO3. Using a multi-pulse scheme we show the ability to extend the lifetime of ... More

Domain size effects on the dynamics of a charge density wave in 1T-TaS2Aug 29 2017Recent experiments have shown that the high temperature incommensurate (I) charge density wave (CDW) phase of 1T-TaS2 can be photoinduced from the lower temperature, nearly commensurate (NC) CDW state. Here we report a time-resolved x-ray diffraction ... More

MagAO: Status and ScienceSep 25 2016"MagAO" is the adaptive optics instrument at the Magellan Clay telescope at Las Campanas Observatory, Chile. MagAO has a 585-actuator adaptive secondary mirror and 1000-Hz pyramid wavefront sensor, operating on natural guide stars from $R$-magnitudes ... More

Coupling between a charge density wave and magnetism in an Heusler materialJun 06 2017The Prototypical magnetic memory shape alloy Ni$_2$MnGa undergoes various phase transitions as a function of temperature, pressure, and doping. In the low-temperature phases below 260 K, an incommensurate structural modulation occurs along the [110] direction ... More

A New Approach to Adaptive Data Analysis and Learning via Maximal LeakageMar 05 2019There is an increasing concern that most current published research findings are false. The main cause seems to lie in the fundamental disconnection between theory and practice in data analysis. While the former typically relies on statistical independence, ... More

Equilibrium Fluctuations for Lattice GasesDec 26 2000The authors in a previous paper proved the hydrodynamic incompressible limit in $d\ge 3$ for a thermal lattice gas, namely a law of large numbers for the density, velocity field and energy. In this paper the equilibrium fluctuations for this model are ... More

Gribov Problem for Gauge Theories: a Pedagogical IntroductionApr 29 2004May 03 2004The functional-integral quantization of non-Abelian gauge theories is affected by the Gribov problem at non-perturbative level: the requirement of preserving the supplementary conditions under gauge transformations leads to a non-linear differential equation, ... More

Best constants in Poincaré inequalities for convex domainsOct 13 2011We prove a Payne-Weinberger type inequality for the $p$-Laplacian Neumann eigenvalues ($p\ge 2$). The inequality provides the sharp upper bound on convex domains, in terms of the diameter alone, of the best constants in Poincar\'e inequality. The key ... More

Non-commutative Einstein equations and Seiberg-Witten mapMar 17 2011Jun 15 2011The Seiberg--Witten map is a powerful tool in non-commutative field theory, and it has been recently obtained in the literature for gravity itself, to first order in non-commutativity. This paper, relying upon the pure-gravity form of the action functional ... More

Solution of Maxwell's equations on a de Sitter backgroundDec 10 2008Apr 08 2009The Maxwell equations for the electromagnetic potential, supplemented by the Lorenz gauge condition, are decoupled and solved exactly in de Sitter space-time studied in static spherical coordinates. There is no source besides the background. One component ... More

Gravitational amplitudes in black-hole evaporation: the effect of non-commutative geometryJul 21 2006Sep 21 2006Recent work in the literature has studied the quantum-mechanical decay of a Schwarzschild-like black hole, formed by gravitational collapse, into almost-flat space-time and weak radiation at a very late time. The relevant quantum amplitudes have been ... More

Late-time evolution of cosmological models with fluids obeying a Shan-Chen-like equation of stateJan 16 2016Classical as well as quantum features of the late-time evolution of cosmological models with fluids obeying a Shan-Chen-like equation of state are studied. The latter is of the type $p=w_{\rm eff}(\rho)\,\rho$, and has been used in previous works to describe, ... More

Bicharacteristics and Fourier integral operators in Kasner spacetimeOct 15 2014Mar 18 2015The scalar wave equation in Kasner spacetime is solved, first for a particular choice of Kasner parameters, by relating the integrand in the wave packet to the Bessel functions. An alternative integral representation is also displayed, which relies upon ... More

Spherically symmetric ADM gravity with variable G and Lambda(c)Sep 10 2007Oct 18 2007This paper investigates the Arnowitt--Deser--Misner (hereafter ADM) form of spherically symmetric gravity with variable Newton parameter G and cosmological term Lambda(c). The Newton parameter is here treated as a dynamical variable, rather than being ... More

Arnowitt-Deser-Misner gravity with variable G and Lambda and fixed point cosmologies from the renormalization groupMar 30 2004Sep 27 2004Models of gravity with variable G and Lambda have acquired greater relevance after the recent evidence in favour of the Einstein theory being nonperturbatively renormalizable in the Weinberg sense. The present paper applies the Arnowitt-Deser-Misner (ADM) ... More

Collective power: Minimal model for thermodynamics of nonequilibrium phase transitionsFeb 01 2018Aug 30 2018We propose a thermodynamically consistent minimal model to study synchronization which is made of driven and interacting three-state units. This system exhibits at the mean-field level two bifurcations separating three dynamical phases: a single stable ... More

Parabolic orbits of $2$-nilpotent elements for classical groupsFeb 18 2018Feb 08 2019We consider the conjugation-action of the Borel subgroup of the symplectic or the orthogonal group on the variety of nilpotent complex elements of nilpotency degree $2$ in its Lie algebra. We translate the setup to a representation-theoretic context in ... More

The effect of linear perturbations on the Yamabe problemOct 30 2012In conformal geometry, the Compactness Conjecture asserts that the set of Yamabe metrics on a smooth, compact, aspherical Riemannian manifold (M,g) is compact. Established in the locally conformally flat case by Schoen [43,44] and for n\leq 24 by Khuri-Marques-Schoen ... More

Quantum phase excitations in Ginzburg-Landau superconductorsNov 15 2004We give a straightforward generalization of the Ginzburg-Landau theory for superconductors where the scalar phase field is replaced by an antisymmetric Kalb-Ramond field. We predict that at very low temperatures, where quantum phase effects are expected ... More

On the foundations of general relativistic celestial mechanicsJul 14 2017Towards the end of nineteenth century, Celestial Mechanics provided the most powerful tools to test Newtonian gravity in the solar system, and led also to the discovery of chaos in modern science. Nowadays, in light of general relativity, Celestial Mechanics ... More

The scalar wave equation in a non-commutative spherically symmetric space-timeMay 02 2007Recent work in the literature has studied a version of non-commutative Schwarzschild black holes where the effects of non-commutativity are described by a mass function depending on both the radial variable r and a non-commutativity parameter theta. The ... More

Peierls Brackets in Theoretical PhysicsSep 18 2002Peierls brackets are part of the space-time approach to quantum field theory, and provide a Poisson bracket which, being defined for pairs of observables which are group invariant, is group invariant by construction. It is therefore well suited for combining ... More

A Class of Renormalization Group Invariant Scalar Field CosmologiesMar 18 2003Sep 12 2003We present a class of scalar field cosmologies with a dynamically evolving Newton parameter $G$ and cosmological term $\Lambda$. In particular, we discuss a class of solutions which are consistent with a renormalization group scaling for $G$ and $\Lambda$ ... More

Strengthened Information-theoretic Bounds on the Generalization ErrorMar 09 2019The following problem is considered: given a joint distribution $P_{XY}$ and an event $E$, bound $P_{XY}(E)$ in terms of $P_XP_Y(E)$ (where $P_XP_Y$ is the product of the marginals of $P_{XY}$) and a measure of dependence of $X$ and $Y$. Such bounds have ... More

Commissioning and operation of the Cherenkov detector for proton Flux Measurement of the UA9 ExperimentApr 12 2019The UA9 Experiment at CERN-SPS investigates channeling processes in bent silicon crystals with the aim to manipulate hadron beams. Monitoring and characterization of channeled beams in the high energy accelerators environment ideally requires in-vacuum ... More

Planets of young stars: the TLS radial velocity surveyOct 14 2005We report on the search for planets orbiting 46 nearby young stars performed at the State Observatory of Turingia (TLS) by means of a radial velocity survey. The aim of this program is to test the theories of formation/evolution of planetary systems. ... More

Web portals, instant messaging and web communities: new tools for online collaborationMay 26 2003Web portals are nowadays very popular. This type of web sites let users to share information, request advice or help in a particular field, and furthermore allow them to create and extend sites content. Combined with instant messaging systems, used to ... More