Results for "Andrea Bonfanti"

total 17389took 0.13s
Age consistency between exoplanet hosts and field starsNov 05 2015Nov 12 2015Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases ... More
Revising the ages of planet-hosting starsNov 16 2014Dec 05 2014This article aims to measure the age of planet-hosting stars (SWP) through stellar tracks and isochrones computed with the \textsl{PA}dova \& T\textsl{R}ieste \textsl{S}tellar \textsl{E}volutionary \textsl{C}ode (PARSEC). We developed algorithms based ... More
On the Paramagnetic Impurity Concentration of Silicate Glasses from Low-Temperature PhysicsApr 22 2015The concentration of paramagnetic trace impurities in glasses can be determined via precise SQUID measurements of the sample's magnetization in a magnetic field. However the existence of quasi-ordered structural inhomogeneities in the disordered solid ... More
On the cohomology of regular surfaces isogenous to a product of curves with $χ(\mathcal{O}_S)=2$Dec 10 2015Let $S$ be a surface isogenous to a product of curves of unmixed type. After presenting several results useful to study the cohomology of $S$ we prove a structure theorem for the cohomology of regular surfaces isogenous to a product of unmixed type with ... More
Methods to locate Saddle Points in Complex LandscapesJan 05 2017We present a class of simple algorithms that allows to find the reaction path in systems with a complex potential energy landscape. The approach does not need any knowledge on the product state and does not require the calculation of any second derivatives. ... More
Abelian surfaces with an automorphism and quaternionic multiplicationAug 06 2014We construct one dimensional families of Abelian surfaces with quaternionic multiplication which also have an automorphism of order three or four. Using Barth's description of the moduli space of (2,4)-polarized Abelian surfaces, we find the Shimura curve ... More
Realistic Tunneling States for the Magnetic Effects in Non-Metallic Real GlassesAug 10 2015The discovery of magnetic and compositional effects in the low temperature properties of multi-component glasses has prompted the need to extend the standard two-level systems (2LSs) tunneling model. A possible extension \cite{Jug2004} assumes that a ... More
Density scaling in the mechanics of a disordered mechanical meta-materialNov 27 2018Nature provides examples of self-assemble lightweight disordered network structures with remarkable mechanical properties which are desirable for many applications purposes but challenging to reproduce artificially. Previous experimental and computational ... More
Global existence for a nonlocal model for adhesive contactApr 01 2017In this paper we address the analytical investigation of a model for adhesive contact, which includes nonlocal sources of damage on the contact surface, such as the elongation. The resulting PDE system features various nonlinearities rendering the unilateral ... More
Analysis of a temperature-dependent model for adhesive contact with frictionJul 20 2012We propose a model for unilateral contact with adhesion between a viscoelastic body and a rigid support, encompassing thermal and frictional effects. Following the approach by M. Fremond, adhesion is described in terms of a surface damage parameter. The ... More
Analysis of a model coupling volume and surface processes in thermoviscoelasticityFeb 09 2014We focus on a highly nonlinear evolutionary abstract PDE system describing volume processes coupled with surfaces processes in thermoviscoelasticity, featuring the quasi-static momentum balance, the equation for the unidirectional evolution of an internal ... More
Long-time behaviour of a thermomechanical model for adhesive contactSep 14 2009This paper deals with the large-time analysis of a PDE system modelling contact with adhesion, in the case when thermal effects are taken into account. The phenomenon of adhesive contact is described in terms of phase transitions for a surface damage ... More
A Super-Earth and two sub-Neptunes transiting the bright, nearby, and quiet M-dwarf TOI-270Mar 14 2019We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three small planets transiting one of the brightest (K-mag 8.3) and nearest (22.5 parsec) M-dwarf hosts to date, TOI-270 (TIC 259377017). The system is observationally favourable, ... More
Thermal effects in adhesive contact: modelling and analysisSep 11 2009In this paper, we consider a contact problem with adhesion between a viscoelastic body and a rigid support, taking thermal effects into account. The PDE system we deal with is derived within the modelling approach proposed by M. Fremond and, in particular, ... More
Spectrophotometry of galaxies in the Virgo cluster.II: The dataJan 30 2004Drift-scan mode (3600-6800 A) spectra with 500<R<1000 resolution are presented for 333 galaxies members to nearby clusters, covering the whole Hubble sequence. The majority (225) were obtained for galaxies in the Virgo cluster where a completeness of ... More
Optical spectroscopy of galaxies in the direction of the Virgo clusterJul 11 2000Optical spectroscopy of 76 galaxies, 48 of which are projected in the direction of the Virgo cluster and 28 onto the Coma-A1367 supercluster, is reported. Adding these new measurements to those found in the literature, the redshift completeness in the ... More
Star formation and dust extinction in nearby star forming and starburst galaxiesJan 17 2002We study the star formation rate and dust extinction properties of a sample of nearby star forming galaxies as derived from Halpha and UV (2000 A) observations and we compare them to those of a sample of starburst galaxies. The dust extinction in Halpha ... More
Spectro-photometry of galaxies in the Virgo clusterMay 06 2002As a result of an extensive observational campaign targeting the Virgo cluster, we obtained integrated (drift-scan mode) optical spectra and multiwavelength (UV,U,B,V,H) photometry for 124 and 330 galaxies, respectively, spanning the whole Hubble sequence, ... More
Equivariant characteristic forms in the Cartan model and Borel equivariant cohomologyAug 31 2015Nov 10 2015We show the compatibility of the differential geometric and the topological construction of equivariant characteristic classes for compact Lie groups. Our analysis motivates a differential geometric construction for equivariant characteristic classes ... More
Band-edge BCS-BEC crossover in a two-band superconductor: physical properties and detection parametersJul 11 2014Superconductivity in iron-based, magnesium diborides, and other novel superconducting materials has a strong multi-band and multi-gap character. Recent experiments support the possibillity for a BCS-BEC crossover induced by strong-coupling and proximity ... More
Ethemba Trusted Host EnvironmentMainly Based on AttestationJan 28 2009Ethemba provides a framework and demonstrator for TPM applications.
Thermodynamic properties and thermal correlation lengths of a Hubbard model with bond-charge interactionFeb 27 2004We investigate the thermodynamics of a one-dimensional Hubbard model with bond-charge interaction X using the transfer matrix renormalization group method (TMRG). Numerical results for various quantities like spin and charge susceptibilities, particle ... More
Domestic Corpuscular InflatonJun 28 2018The aim of this paper is to provide a more precise description of the paradigm of corpuscular slow-roll inflation, which was previously introduced by Casadio et al. in [1]. Specifically, we start by expanding the Starobinsky theory on a curved background ... More
Inverse wave scattering in the time domain: a factorization method approachMar 14 2019Let $\Delta_{\Lambda}\le \lambda_{\Lambda}$ be a semi-bounded self-adjoint realization of the Laplace operator with boundary conditions assigned on the Lipschitz boundary of a bounded obstacle $\Omega$. Let $u^{\Lambda}_{f}$ and $u^{0}_{f}$ be the solutions ... More
Numerical analysis for time-dependent advection-diffusion problems with random discontinuous coefficientsFeb 06 2019Subsurface flows are commonly modeled by advection-diffusion equations. Insufficient measurements or uncertain material procurement may be accounted for by random coefficients. To represent, for example, transitions in heterogeneous media, the parameters ... More
Gauge-invariant Green's functions for the bosonic sector of the standard modelDec 18 1998Jun 21 2000There are many applications in gauge theories where the usually employed framework involving gauge-dependent Green's functions leads to considerable problems. In order to overcome the difficulties invariably tied to gauge dependence, we present a manifestly ... More
Equivariant Differential CohomologyOct 21 2015Nov 10 2015The construction of characteristic classes via the curvature form of a connection is one motivation for the refinement of integral cohomology by de Rham cocycles -- known as differential cohomology. We will discuss the analog in the case of a group action ... More
Status of sub-GeV Hidden Particle SearchesAug 26 2010Hidden sector particles with sub-GeV masses like hidden U(1) gauge bosons, the NMSSM CP-odd Higgs, and other axion-like particles are experimentally little constrained as they interact only very weakly with the visible sector. For masses below the muon ... More
The electroweak chiral Lagrangian reanalyzedJul 09 1999Oct 26 2000In this paper we reanalyze the electroweak chiral Lagrangian with particular focus on two issues related to gauge invariance. Our analysis is based on a manifestly gauge-invariant approach that we introduced recently. It deals with gauge-invariant Green's ... More
A universal ionization threshold for strongly driven Rydberg statesApr 21 2004We observe a universal ionization threshold for microwave driven one-electron Rydberg states of H, Li, Na, and Rb, in an {\em ab initio} numerical treatment without adjustable parameters. This sheds new light on old experimental data, and widens the scene ... More
Residual Symmetries in the Spectrum of Periodically Driven Alkali Rydberg StatesNov 25 1999We identify a fundamental structure in the spectrum of microwave driven alkali Rydberg states, which highlights the remnants of the Coulomb symmetry in the presence of a non-hydrogenic core. Core-induced corrections with respect to the hydrogen spectrum ... More
Inverse Scattering for the Laplace operator with boundary conditions on Lipschitz surfacesJan 26 2019Feb 17 2019We provide a general scheme, in the combined frameworks of Mathematical Scattering Theory and Factorization Method, for inverse scattering for the couple of self-adjoint operators $(\widetilde\Delta,\Delta)$, where $\Delta$ is the free Laplacian in $L^{2}({\mathbb ... More
Tanaka structures modeled on extended Poincaré algebrasJan 03 2012Oct 04 2012Let (V,(.,.)) be a pseudo-Euclidean vector space and S an irreducible Cl(V)-module. An extended translation algebra is a graded Lie algebra m = m_{-2}+m_{-1} = V+S with bracket given by ([s,t],v) = b(v.s,t) for some nondegenerate so(V)-invariant reflexive ... More
Particle-particle ladder based basis-set corrections applied to atoms and molecules using coupled-cluster theoryMar 13 2019Mar 14 2019We investigate the basis-set convergence of coupled cluster electronic correlation energies using a recently proposed finite basis-set correction technique. The correction is applied to atomic and molecular systems and is based on a diagrammatically decomposed ... More
Particle-particle ladder based basis-set corrections applied to atoms and molecules using coupled-cluster theoryMar 13 2019We investigate the basis-set convergence of coupled cluster electronic correlation energies using a recently proposed finite basis-set correction technique. The correction is applied to atomic and molecular systems and is based on a diagrammatically decomposed ... More
Lipschitz functions with prescribed blowups at many pointsDec 15 2016In this paper we prove generalizations of Lusin-type theorems for gradients due to Giovanni Alberti, where we replace the Lebesgue measure with any Radon measure $\mu$. We apply this to go beyond the known result on the existence of Lipschitz functions ... More
A Multilevel Monte Carlo Algorithm for Parabolic Advection-Diffusion Problems with Discontinuous CoefficientsFeb 06 2019The Richards' equation is a model for flow of water in unsaturated soils. The coefficients of this (nonlinear) partial differential equation describe the permeability of the medium. Insufficient or uncertain measurements are commonly modeled by random ... More
PT-symmetrically deformed shock wavesJan 27 2012We investigate for a large class of nonlinear wave equations, which allow for shock wave formations, how these solutions behave when they are PT-symmetrically deformed. For real solutions we find that they are transformed into peaked solutions with a ... More
Numerical analysis of detection-mechanism models of SNSPDAug 27 2013Nov 12 2013The microscopic mechanism of photon detection in superconducting nanowire single-photon detectors is still under debate. We present a simple, but powerful theoretical model that allows us to identify essential differences between competing detection mechanisms. ... More
The antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic fieldDec 17 2008Mar 16 2009We study the field dependence of the antiferromagnetic spin-1/2 Heisenberg model on the square lattice by means of exact diagonalizations. In a first part, we calculate the spin-wave velocity, the spin-stiffness, and the magnetic susceptibility and thus ... More
Solving DC programs with polyhedral component utilizing a multiple objective linear programming solverOct 18 2016A class of non-convex optimization problems with DC objective function and linear constraints is studied, where DC stands for being representable as the difference $f=g-h$ of two convex functions $g$ and $h$. In particular, we deal with the special case ... More
Formality of $\mathbb{P}$-objectsSep 19 2017We show that a $\mathbb{P}$-object and simple configurations of $\mathbb{P}$-objects have a formal derived endomorphism algebra. Hence the triangulated category (classically) generated by such objects is independent of the ambient triangulated category. ... More
(a,b)-Koszul algebrasJul 20 2010Let $a$ and $b$ be two integers such that $2\le a<b$. In this article we define the notion of $(a,b)$-Koszul algebra as a generalization of $N$-Koszul algebras. We also exhibit examples and we provide a minimal graded projective resolution of the algebra ... More
A Grothendieck-type inequality for local maximaMar 13 2016A large number of problems in optimization, machine learning, signal processing can be effectively addressed by suitable semidefinite programming (SDP) relaxations. Unfortunately, generic SDP solvers hardly scale beyond instances with a few hundreds variables ... More
Graphical Models Concepts in Compressed SensingNov 18 2010Mar 15 2011This paper surveys recent work in applying ideas from graphical models and message passing algorithms to solve large scale regularized regression problems. In particular, the focus is on compressed sensing reconstruction via ell_1 penalized least-squares ... More
Two Lectures on Iterative Coding and Statistical MechanicsDec 14 2005These are the notes for two lectures delivered at the Les Houches summer school Mathematical Statistical Mechanics, held in July 2005. I review some basic notions on sparse graph error correcting codes with emphasis on `modern' aspects, such as, iterative ... More
Turbo codes: the phase transitionMar 13 2000Turbo codes are a very efficient method for communicating reliably through a noisy channel. There is no theoretical understanding of their effectiveness. In [1] they are mapped onto a class of disordered spin models. The analytical calculations concerning ... More
Cooper-Mesons in the Color-Flavor-Locked Superconducting Phase of Dense QCDSep 01 2000QCD superconductors in the color-flavor-locked (CFL) phase sustain excitations (``Cooper'' mesons) that can be described as pairs of particles or holes around a gapped Fermi surface. In weak coupling and to leading logarithm accuracy the masses, decay ... More
A note on normal generation and generation of groupsFeb 03 2014In this note we study sets of normal generators of finitely presented residually $p$-finite groups. We show that if an infinite, finitely presented, residually $p$-finite group $G$ is normally generated by $g_1,\dots,g_k$ with order $n_1,\dots,n_k \in ... More
Low degree bounded cohomology and l^2-invariants for negatively curved groupsOct 23 2007Oct 13 2008We study the subgroup structure of discrete groups which share cohomological properties which resemble non-negative curvature. Examples include all Gromov hyperbolic groups. We provide strong restrictions on the possible s-normal subgroups of a Gromov ... More
L^2-cohomology for von Neumann algebrasJan 18 2006Mar 15 2006We study L^2-Betti numbers for von Neumann algebras, as defined by D. Shlyakhtenko and A. Connes. We give a definition of L^2-cohomology and show how the study of the first L^2-Betti number can be related with the study of derivations with values in a ... More
The origin of the Frey elliptic curve in a too narrow marginApr 13 2016May 27 2016It is shown that an appropriate use of so-called double equations by Diophantus provides the origin of the Frey elliptic curve and from it we can deduce an elementary proof of Fermat's Last Theorem.
The Parton Structure of Real PhotonsSep 15 1997The QCD treatment of the photon structure is recalled. Emphasis is given to the recently derived momentum sum rule, and to the proper choice of the factorization scheme and/or boundary conditions for the evolution equations beyond the leading order. Parametrizations ... More
Spectral Invariance of Besov-Bessel SubalgebrasDec 15 2010Using principles of the theory of smoothness spaces we give systematic constructions of scales of inverse-closed subalgebras of a given Banach algebra with the action of a d-parameter automorphism group. In particular we obtain the inverse-closedness ... More
Theory of Light Sail Acceleration by Intense Lasers: an OverviewMar 25 2014A short overview of the theory of acceleration of thin foils driven by the radiation pressure of superintense lasers is presented. A simple criterion for radiation pressure dominance at intensities around $5 \times 10^{20} \mbox{W cm}^{-2}$ is given, ... More
Spherical Casimir effect for a massive scalar field on the three dimensional ballOct 28 2014The zeta function regularization technique is used to study the Casimir effect for a scalar field of mass $m$ satisfying Dirichlet boundary conditions on a spherical surface of radius $a$. In the case of large scalar mass, $ma\gg1$, simple analytic expressions ... More
Neutrino self-energy in external magnetic fieldAug 28 2009Nov 23 2009Using the exact propagators in a constant magnetic field, the neutrino self-energy has been calculated to all orders in the field strength B within the minimal extension of the Weinberg-Salam model with massive Dirac neutrinos. A simple and very accurate ... More
Noise induced stability in fluctuating, bistable potentialsDec 14 1999The over-damped motion of a Brownian particle in an asymmetric, bistable, fluctuating potential shows noise induced stability: For intermediate fluctuation rates the mean occupancy of minima with an energy above the absolute minimum is enhanced. The model ... More
Stability of Ferromagnetism in Hubbard models with degenerate single-particle ground statesOct 25 1999A Hubbard model with a N_d-fold degenerate single-particle ground state has ferromagnetic ground states if the number of electrons is less or equal to N_d. It is shown rigorously that the local stability of ferromagnetism in such a model implies global ... More
Similarity renormalization of the electron--phonon couplingSep 06 1996Dec 17 1996We study the problem of the phonon-induced electron-electron interaction in a solid. Starting with a Hamiltonian that contains an electron-phonon interaction, we perform a similarity renormalization transformation to calculate an effective Hamiltonian. ... More
Calculating critical temperatures of superconductivity from a renormalized HamiltonianSep 16 1997It is shown that one can obtain quantitatively accurate values for the superconducting critical temperature within a Hamiltonian framework. This is possible if one uses a renormalized Hamiltonian that contains an attractive electron-electron interaction ... More
Pion photoproduction in a nonrelativistic theorySep 16 2009The pion and nucleon mass differences generate a very pronounced cusp in the photoproduction reaction of a single pion on the nucleon. A nonrelativistic effective field theory to describe this reaction is constructed. The approach is rigorous in the sense ... More
Top-quark mass at hadron collidersApr 14 2014Sep 02 2014Top quarks can be produced abundantly at hadron colliders like the Tevatron at Fermilab and the Large Hadron Collider at CERN, and a variety of measurements of top-quark properties have been gathered in the recent years from four experiments: CDF and ... More
Probing the Low-Energy Electronic Structure of Complex Systems by ARPESJul 03 2003Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct methods of studying the electronic structure of solids. By measuring the kinetic energy and angular distribution of the electrons photoemitted from a sample illuminated with sufficiently ... More
Measuring Dark Matter at CollidersSep 20 2005Sep 26 2005We investigate the need and prospects for measuring dark matter properties at particle collider experiments. We discuss the connections between the inferred properties of particle dark matter and the physics that is expected to be uncovered by the Large ... More
The geometry and origin of ultra-diffuse ghost galaxiesAug 31 2016Sep 02 2016The geometry and intrinsic ellipticity distribution of ultra diffuse galaxies (UDGs) is determined from the line-of-sight distribution of axial ratios q of a large sample of UDGs, detected by Koda et al. (2015) in the Coma cluster. With high significance ... More
Point kinetic model of the early phase of a spherically symmetric nuclear explosionJun 06 2016A concise point kinetic model of the explosion of a prompt supercritical sphere driven by a nuclear fission chain reaction is presented. The findings are in good agreement with the data available for Trinity, the first detonation of a nuclear weapon conducted ... More
On the precision of a data-driven estimate of hadronic light-by-light scattering in the muon g-2: pseudoscalar-pole contributionFeb 10 2016The evaluation of the numerically dominant pseudoscalar-pole contribution to hadronic light-by-light scattering in the muon g-2 involves the pseudoscalar-photon transition form factor F_{P gamma^* gamma^*}(-Q_1^2, -Q_2^2) with P = pi^0, eta, eta^\prime ... More
Star products on graded manifolds and $α'$-corrections to double field theoryNov 12 2015Originally proposed as an $O(d,d)$-invariant formulation of classical closed string theory, double field theory (DFT) offers a rich source of mathematical structures. Most prominently, its gauge algebra is determined by the so-called C-bracket, a generalization ... More
Thermodynamics of Deconfined QCD at Small and Large Chemical PotentialAug 31 2004We present large $N_f$ QCD/QED as a test bed for improved pressure calculations, show how to apply the hints obtained on optimized renormalization scales at large $N_f$ to finite $N_f=2$, and compare the results to recent lattice data.
Quantum Corrections to Thermodynamic Properties in the Large $N_f$ Limit of the Quark Gluon PlasmaMay 13 2004In this doctoral thesis we present the exact large $N_f$ calculation at next-to-leading order of the thermal interaction pressure of deconfined QCD for small and large quark chemical potential where the presence of the Landau pole is negligible numerically. ... More
Correspondence Theorems via Tropicalizations of Moduli SpacesJun 08 2014We show that the moduli spaces of irreducible labeled parametrized marked rational curves in toric varieties can be embedded into algebraic tori such that their tropicalizations are the analogous tropical moduli spaces. These embeddings are shown to respect ... More
Galois theory for iterative connections and nonreduced Galois groupsDec 21 2007Aug 26 2009This article presents a theory of modules with iterative connection. This theory is a generalisation of the theory of modules with connection in characteristic zero to modules over rings of arbitrary characteristic. We show that these modules with iterative ... More
A trace-like invariant for representations of Hopf algebrasOct 29 2009In this paper we introduce a trace-like invariant for the irreducible representations of a finite dimensional complex Hopf algebra H. We do so by considering the trace of the map induced by the antipode S on the endomorphisms End(V) of a self-dual module ... More
Stone spectra of von Neumann algebras of type $I_{n}$Jan 18 2005The Stone spectrum of a von Neumann algebra is a generalization of the Gelfand spectrum, as was shown by de Groote. In this article we clarify the structure of the Stone spectra of von Neumann algebras of type $I_{n}$.
Sur l'effectivite du theoreme de Siegel et la conjecture abcJan 19 2005Apr 23 2006Nous montrons qu'un raffinement du th\'eor\`eme de Siegel sur les points entiers de courbes alg\'ebriques impliquerait la conjecture abc de Masser-Oesterl\'e. Nous formulons une hypoth\`ese "Siegel uniforme" qui est une majoration de la hauteur des points ... More
Correlation of internal representations in feed-forward neural networksApr 11 1996Feed-forward multilayer neural networks implementing random input-output mappings develop characteristic correlations between the activity of their hidden nodes which are important for the understanding of the storage and generalization performance of ... More
Laboratory Studies of Astrophysical JetsMar 02 2009Jets and outflows produced during star-formation are observed on many scales: from the "micro-jets" extending a few hundred Astronomical Units to the "super-jets" propagating to parsecs distances. Recently, a new "class" of short-lived (hundreds of nano-seconds) ... More
Status of the global electroweak fit of the Standard ModelSep 07 2009Sep 09 2009Results from the global Standard Model fit to electroweak precision data, including newest Tevatron measurements, are reviewed and discussed. The complete fit using also the constraints from the direct Higgs boson searches yields an upper limit on the ... More
The finite infinite range Heisenberg model and microcanonical black hole statisticsFeb 03 2015Jan 21 2016The Gelfand pattern of the reduction of the N-fold tensor product of the fundamental representation of the special unitary group SU(2) by itself is studied in the framework of a finite Heisenberg model with infinite range, where N spins couple to each ... More
The position of the quasielastic peak and electron Coulomb distortion in (e,e') scatteringNov 29 2006The position of the quasielastic peak for (e,e') scattering off 208-Pb extracted from a selected data set measured at Saclay is related to a heuristic theoretical description. An analysis of the data shows that the peak position can be described very ... More
Causal construction of the massless vertex diagramJul 17 2006Sep 28 2006The massless one-loop vertex diagram is constructed by exploiting the causal structure of the diagram in configuration space, which can be translated directly into dispersive relations in momentum space.
Perturbative quantum gauge invariance: Where the ghosts come fromJan 23 2004Oct 07 2004A condensed introduction to quantum gauge theories is given in the perturbative S-matrix framework; path integral methods are used nowhere. This approach emphasizes the fact that it is not necessary to start from classical gauge theories which are then ... More
Fock Vacuum Instability and CausalityApr 02 2001Apr 04 2001The vacuum diagram is calculated at second order for theories with self-interacting massless fields in the framework of finite causal perturbation theory. It is pointed out that the infrared behaviour of the vacuum diagram leads to unstable Fock vacua ... More
Twisted cotangent sheaves and a Kobayashi-Ochiai theorem for foliationsJul 12 2013Let X be a normal projective variety, and let A be an ample Cartier divisor on X. We prove that the twisted cotangent sheaf \Omega_X \otimes A is generically nef with respect to the polarisation A unless X is a projective space. As an application we prove ... More
Tauonic $B$ decays and Higgs mediated flavour violationOct 30 2014Nov 05 2014In these proceedings we review the impact of the tauonic $B$ decays $B\to\tau\nu$, $B\to D\tau\nu$ and $B\to D^*\tau\nu$ on Higgs mediated flavour violation. For this purpose we study a 2HDM with generic flavour structure (of type III). We find that despite ... More
Chiral Enhancement in the MSSM -- An OverviewJun 06 2011In this article I review the origin and the effects of chirally enhanced loop-corrections in the MSSM based on Refs. [1-3]. Chiral enhancement is related to fermion-Higgs couplings (or self-energies when the Higgs field is replaced by its vev). I describe ... More
Effective Higgs Vertices in the generic MSSMDec 21 2010Jun 12 2012In this article we consider chirally enhanced corrections to Higgs vertices in the most general MSSM. We include the contributions stemming from bilinear-terms, from the trilinear A-terms and their non-holomorphic analogues, the A'-terms, which couple ... More
Charged Higgs: Interpretation of $B$-physics resultsDec 08 2014In these proceedings we review the impact of additional Higgs bosons on $B$ physics observables. For this purpose, we consider first the 2HDM of type II which respects natural flavour conservation. Afterwards, we study a 2HDM with generic flavour structure ... More
Rare decays and MSSM phenomenologyMay 22 2012In this article I review some aspects of flavour phenomenology in the MSSM. After an overview of various flavour observables I discuss the constraints on the off-diagonal elements of the squark mass matrices. In this context I present the Fortran code ... More
Chirally enhanced corrections in the MSSMJul 18 2011In the general MSSM, chirally-enhanced corrections (to Yukawa couplings) are induced by gluino-squark, chargino-sfermion and neutralino-sfermion loops and can numerically compete with, or even dominate over, tree-level contributions, due to their chiral ... More
Relaxation phenomena at criticalityDec 07 2007The collective behaviour of statistical systems close to critical points is characterized by an extremely slow dynamics which, in the thermodynamic limit, eventually prevents them from relaxing to an equilibrium state after a change in the thermodynamic ... More
Chameleonic dilaton and conformal transformationsJun 20 2012We recently proposed a chameleonic solution to the cosmological constant problem - Phys. Rev. D82 (2010) 044006. One of the results of that paper is a non-equivalence of different conformal frames at the quantum level. In this letter we further discuss ... More
Chameleonic dilaton, nonequivalent frames, and the cosmological constant problem in quantum string theoryJul 31 2010The chameleonic behaviour of the String theory dilaton is suggested. Some of the possible consequences of the chameleonic string dilaton are analyzed in detail. In particular, (1) we suggest a new stringy solution to the cosmological constant problem ... More
Dilaton stabilization and composite dark matter in the string frame of heterotic-M-theoryOct 14 2012In this paper we further elaborate on our recently proposed solution to the cosmological constant problem - Phys. Rev. D82 (2010) 044006. One of the elements of the solution is the chameleonic behaviour of the Einstein frame dilaton: the mass of the dilaton ... More
Yang-Mills connections of cohomogeneity one on SO(n)-bundles over Euclidean spheresJul 29 2011We construct Yang-Mills connections on SO(n)-bundles over spheres equipped with the Euclidean metric. We use a cohomogeneity one group action on the bundle to reduce the Yang-Mills-equation to a system of ordinary differential equations. The system is ... More
Microstructure Effects on Daily Return Volatility in Financial MarketsNov 17 2000We simulate a series of daily returns from intraday price movements initiated by microstructure elements. Significant evidence is found that daily returns and daily return volatility exhibit first order autocorrelation, but trading volume and daily return ... More
Non-linear Oscillations of Compact Stars and Gravitational WavesJul 31 2006This thesis investigates in the time domain a particular class of second order perturbations of a perfect fluid non-rotating compact star: those arising from the coupling between first order radial and non-radial perturbations. This problem has been treated ... More
The special function "shin", IIJan 05 2005Sep 09 2013This Paper (one first and draft version) contains some small imperfections, one its correct and definitive version has been already submitted to one prestigious review of mathematics. More precisely "the Special Function SHIN, II" will be published in ... More
Cellular Automaton Approach to Pedestrian Dynamics - TheoryDec 07 2001We present a 2-dimensional cellular automaton model for the simulation of pedestrian dynamics. The model is extremely efficient and allows simulations of large crowds faster than real time since it includes only nearest-neighbour interactions. Nevertheless ... More