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Jet quenching as a probe of the initial stages in heavy-ion collisionsFeb 08 2019Jet quenching provides a very flexible variety of observables which are sensitive to different energy- and time-scales of the strongly interacting matter created in heavy-ion collisions. Exploiting this versatility would make jet quenching an excellent ... More

Addendum to "Travelling waves for a non-local Korteweg-de Vries-Burgers equation" [J. Differential Equations 257 (2014), no. 3, 720--758]Apr 19 2016We add a theorem to [J. Differential Equations 257 (2014), no. 3, 720--758] by F. Achleitner, C.M. Cuesta and S. Hittmeir. In that paper we studied travelling wave solutions of a Korteweg-de Vries-Burgers type equation with a non-local diffusion term. ... More

Extracting $\hat{q}$ from single inclusive data at RHIC and at the LHC for different centralities: a new puzzle?Dec 20 2016We present here an extraction of the jet transport coefficient, $\hat{q}$, using RHIC and LHC single-inclusive high-$p_T$ data for different centralities. We fit a $K$-factor that determines the deviation of this coefficient from an ideal estimate, $K ... More

Extracting $\hat{q}$ in event-by-event hydrodynamics and the centrality/energy puzzleMay 03 2017In our analysis, we combine event-by-event hydrodynamics, within the EKRT formulation, with jet quenching -ASW Quenching Weights- to obtain high-$p_T$ $R_{\rm AA}$ for charged particles at RHIC and LHC energies for different centralities. By defining ... More

Energy loss as the origin of an universal scaling law of the elliptic flowSep 13 2016It is shown that the excellent scaling of the elliptic flow found for all centralities, species and energies from RHIC to the LHC for $p_{T}$ less than the saturation momentum is a consequence of the energy lost by a parton interacting with the color ... More

Self-similar lifting and persistent touch-down points in the thin-film equationAug 01 2017We study self-similar solutions of the thin-film equation, with mobility exponent m in (0,4], that describe the lifting of an isolated touch-down point given by an initial profile of the form |x|. This provides a mechanism for non-uniqueness of the thin-film ... More

A Periodicity Theorem for the Octahedron RecurrenceApr 12 2006Oct 26 2006We investigate a variant of the octahedron recurrence which lives in a 3-dimensional lattice contained in [0,n] x [0,m] x R. Generalizing results of David Speyer math.CO/0402452, we give an explicit non-recursive formula for the values of this recurrence ... More

Logic Blog 2015fFeb 14 2016The 2015 Logic Blog contains a large variety of results connected to logic, some of them unlikely to be submitted to a journal. For the first time there is a group theory part. There are results in higher randomness, and in computable ergodic theory.

Microlocal lifts of eigenfunctions on hyperbolic surfaces and trilinear invariant functionalsApr 16 2004S. Zelditch introduced an equivariant version of a pseudo-differential calculus on a hyperbolic Riemann surface. We recast his construction in terms of trilinear invariant functionals on irreducible unitary representations of PGL(2,R). This allows us ... More

Norms of geodesic restrictions for eigenfunctions on hyperbolic surfaces and representation theoryMar 25 2004Mar 24 2010We consider restrictions along closed geodesics and geodesic circles for eigenfunctions of the Laplace-Beltrami operator on a compact hyperbolic Riemann surface. We obtain a non-trivial bound on the L^2-norm of such restrictions as the eigenvalue tends ... More

Review of SU(2)-CalibrationsOct 27 2005The purpose of this article is to provide a review of SU(2)-calibrations. The focus is on developing all techniques in full detail by studying selected examples. The supergravity point of view and the string theoretic one are explained.

Scale invariant cosmology II: model equations and propertiesMay 19 2016We want to establish the basic properties of a scale invariant cosmology, that also accounts for the hypothesis of scale invariance of the empty space at large scales. We write the basic analytical properties of the scale invariant cosmological models. ... More

A New Track Reconstruction Algorithm suitable for Parallel Processing based on Hit Triplets and Broken LinesNov 05 2016Track reconstruction in high track multiplicity environments at current and future high rate particle physics experiments is a big challenge and very time consuming. The search for track seeds and the fitting of track candidates are usually the most time ... More

Heavy-flavour production in pp and Pb-Pb collisions at ALICEJun 06 2011In this contribution, recent ALICE measurements of the production cross section of single electrons, single muons and open charmed mesons in proton-proton collisions at sqrt(s) = 7 TeV are reported. The data are compared to next-to-leading-order perturbative ... More

Towards a Comprehensive Fueling-Controlled Theory on the Growth of Massive Black Holes and Host SpheroidsMay 30 2007We study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using AMR numerical simulations, we analyze how gas is transported in the nuclear (central kpc) regions of galaxies. We study the gas fueling onto ... More

On the Fueling of Massive Black Holes and the Properties of their Host SpheroidsApr 24 2006Aug 31 2006We study the relation between nuclear massive black holes and their host spheroid gravitational potential. Using simple models, we analyze how gas is expected to be transported in the nuclear regions of galaxies. When we couple it with the expected gas ... More

On the "equivalence" of the Maxwell and Dirac equationsJan 25 2002Apr 04 2002It is shown that Maxwell's equation cannot be put into a spinor form that is equivalent to Dirac's equation. First of all, the spinor \psi in the representation \vec{F} = \psi \vec{u} \bar{\psi} of the electromagnetic field bivector depends on only three ... More

Explicit closed-form parametrization of SU(3) and SU(4) in terms of complex quaternions and elementary functionsNov 22 2002Nov 22 2002Remarkably simple closed-form expressions for the elements of the groups SU(n), SL(n,R), and SL(n,C) with n=2, 3, and 4 are obtained using linear functions of biquaternions instead of n x n matrices. These representations do not directly generalize to ... More

Genetic Algorithms for the Imitation of Genomic Styles in Protein BacktranslationApr 05 2003Several technological applications require the translation of a protein into a nucleic acid that codes for it (``backtranslation''). The degeneracy of the genetic code makes this translation ambiguous; moreover, not every translation is equally viable. ... More

Stability of rotating spherical stellar systemsAug 30 2002The stability of rotating isotropic spherical stellar systems is investigated by using N-body simulations. Four spherical models with realistic density profiles are studied: one of them fits the luminosity profile of globular clusters, while the remaining ... More

Quantum Theory of Self-Induced TransparencyMay 15 1995It is known that classical electromagnetic radiation at a frequency in resonance with energy splittings of atoms in a dielectric medium can be described using the classical sine-Gordon equation. In this paper we quantize the electromagnetic field and ... More

On the stability of four legged tablesOct 17 2005Aug 15 2006We prove that a perfect four-feet square table, posed in a continuous irregular ground with a local slope of at most 15 degrees can be put in equilibrium on the ground by a "rotation" of less than 90 degrees. We also discuss the case of non-square tables ... More

Highlights of Current Higgs Boson SearchesNov 02 2010Over the last years the Tevatron Run-II has extended several limits on Higgs boson masses and coupling which were pioneered during the LEP accelerator operation between 1989 and 2000. Higgs boson searches will also be at the forefront of research at the ... More

Search for New Particles at LEPNov 23 1999The latest preliminary results of the searches for Higgs bosons and Supersymmetric particles at LEP are reviewed. The results include the data-taking in 1999 up to center-of-mass energies of 196 GeV. The combination of the results from the four LEP experiments ... More

Kinetic Theory of Soft Matter. The Penetrable-Sphere ModelJan 05 2005The penetrable-sphere model has been introduced in the literature to describe the peculiar thermodynamic behavior of some colloidal systems. In this model the interaction potential is $\phi(r)=\epsilon>0$ if the two spheres are overlapped ($r<\sigma$) ... More

Singularities of Lagrangian mean curvature flow: monotone caseAug 15 2006We study the formation of singularities for the mean curvature flow of monotone Lagrangians in $\C^n$. More precisely, we show that if singularities happen before a critical time then the tangent flow can be decomposed into a finite union of area-minimizing ... More

The orbital counting problem for hyperconvex representationsMar 01 2012Jul 12 2014We give a precise counting result on the symmetric space of a noncompact real algebraic semisimple group $G,$ for a class of discrete subgroups of $G$ that contains, for example, representations of a surface group on $\textrm{PSL}(2,\mathbb R)\times\textrm{PSL}(2,\mathbb ... More

Exact Black Holes and Universality in the Backreaction of non-linear Sigma Models with a potential in (A)dS4Apr 12 2012May 22 2012The aim of this paper is to construct accelerated, stationary and axisymmetric exact solutions of the Einstein theory with self interacting scalar fields in (A)dS4. To warm up, the backreaction of the (non)-minimally coupled scalar field is solved, the ... More

La conjecture du facteur directSep 01 2016Building on his reduction to the case of an unramified complete regular local ring R of mixed characteristic, we propose a proof in the framework of P. Scholze's perfectoid theory. The main ingredients are the perfectoid "Abhyankar lemma" and an analysis ... More

Simulations of the Temperature Dependence of the Charge Transfer Inefficiency in a High-Speed CCDDec 27 2007Results of detailed simulations of the charge transfer inefficiency of a prototype serial readout CCD chip are reported. The effect of radiation damage on the chip operating in a particle detector at high frequency at a future accelerator is studied, ... More

Conformal nets are factorization algebrasNov 17 2016We prove that conformal nets of finite index are an instance of the notion of a factorization algebra. This result is an ingredient in our proof that, for $G=SU(n)$, the Drinfel'd center of the category of positive energy representations of the based ... More

Invariance Principle for the Random Conductance Model with dynamic bounded ConductancesFeb 03 2012Oct 11 2012We study a continuous time random walk X in an environment of dynamic random conductances. We assume that the conductances are stationary ergodic, uniformly bounded and bounded away from zero and polynomially mixing in space and time. We prove a quenched ... More

Logic Blog 2012Feb 15 2013The 2012 logic blog has focussed on the following: Randomness and computable analysis/ergodic theory; Systematizing algorithmic randomness notions; Traceability; Higher randomness; Calibrating the complexity of equivalence relations from computability ... More

Calibrating the complexity of Delta 2 sets via their changesFeb 03 2013The computational complexity of a Delta 2 set will be calibrated by the amount of changes needed for any of its computable approximations. Firstly, we study Martin-Loef random sets, where we quantify the changes of initial segments. Secondly, we look ... More

BYOD and the Mobile Enterprise - Organisational challenges and solutions to adopt BYODDec 12 2015Bring Your Own Device, also known under the term BOYD refers to the trend in employees bringing their personal mobile devices into organisations to use as a primary device for their daily work activities. With the rapid development in computing technology ... More

Probabilistic Tagging with Feature StructuresOct 25 1994The described tagger is based on a hidden Markov model and uses tags composed of features such as part-of-speech, gender, etc. The contextual probability of a tag (state transition probability) is deduced from the contextual probabilities of its feature-value-pairs. ... More

An Ab Initio Study of the Structures and Relative Stabilities of Doubly Charged [(NaCl)m(Na)2]2+ Cluster IonsJan 26 2001We present ab initio perturbed ion calculations on the structures and relative stabilities of doubly charged [(NaCl)_m(Na)_2]2+ cluster ions. The obtained stabilities show excellent agreement with experimental abundances obtained from mass spectra. Those ... More

A Complete Axiomatization of Quantified Differential Dynamic Logic for Distributed Hybrid SystemsJun 15 2012Nov 22 2012We address a fundamental mismatch between the combinations of dynamics that occur in cyber-physical systems and the limited kinds of dynamics supported in analysis. Modern applications combine communication, computation, and control. They may even form ... More

Fermion Back-Reaction and the SphaleronJan 10 1994Using a simple model, a new sphaleron solution which incorporates finite fermionic density effects is obtained. The main result is that the height of the potential barrier (sphaleron energy) decreases as the fermion density increases. This suggests that ... More

The infrared behavior of lattice QCD Green's functionsSep 08 2006We investigate different aspects of lattice QCD in Landau gauge using Monte Carlo simulations. In particular, we focus on the low momentum behavior of gluon and ghost propagators. The gauge group is SU(3). Different systematic effects on the gluon and ... More

Thermodynamics of the two-dimensional Hubbard model in the two-body scattering approximationJul 07 2010Jan 27 2012A new analytic treatment of the two-dimensional Hubbard model at finite temperature and chemical potential is presented. A next nearest neighbor hopping term of strength t' is included. This analysis is based upon a formulation of the statistical mechanics ... More

Behaviour of the wave function near the origin in the radial caseNov 29 2004Jul 13 2005We give one more proof in two and three space dimensions that the irregular solution of the Schrodinger equation, for zero angular momentum, is in fact the solution of an equation containing an extra 'delta function'. We propose another criterium to eliminate ... More

Searches for Higgs Bosons Beyond the Standard ModelAug 03 2004Latest results from the combined data of the four LEP experiments ALEPH, DELPHI, L3 and OPAL on Higgs boson searches in extensions of the Standard Model (SM) are presented.

MSSM Constraints from Higgs Boson SearchesDec 05 2001The LEP era has brought immense progress in searches for Higgs bosons over the last 12 years which will guide searches at future colliders. The evolution of the Higgs boson mass limits are reviewed with the focus on results from general parameter scans ... More

Aspects of Higgs Boson Searches at LEP2Jul 31 1998A preliminary combined mass limit of about 90 GeV has been reported for the Minimal Standard Model Higgs boson from the 183 GeV data taken in 1997, with a total luminosity of about 200 pb-1. Similar mass limits have been reported from the individual LEP ... More

The complexity of isomorphism between countably based profinite groupsApr 03 2016A topological group G is profinite if it is compact and totally disconnected. Equivalently, G is the inverse limit of a surjective system of finite groups carrying the discrete topology. We discuss how to represent a countably based profinite group as ... More

Jet-like correlations of heavy-flavor particles - from RHIC to LHCJul 26 2011Measurements at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory have revealed strong modification of the jet structure in high-energy heavy-ion collisions, which can be attributed to the interaction of hard scattered partons ... More

Overview on heavy flavour measurements in lead-lead collisions at the CERN-LHCJan 31 2013High energy collisions of heavy atomic nuclei allow to create and carefully study a high-density, colour-deconfined state of strongly-interacting matter. According to calculations from lattice Quantum-Chromodynamics, under the conditions of high energy ... More

A new correlation method to identify and separate charm and bottom production processes at RHICJul 08 2008Jan 10 2009Electrons from semileptonic decays of heavy-flavor mesons (D and B) allow to study the energy loss of heavy-quarks in nuclear collisions at sqrt(s) = 200 GeV at RHIC. Since pQCD calculations have shown that the crossing point where bottom decay electrons ... More

About Geometric Scaling and Small-x Evolution at RHIC and LHCJun 25 2008We show that the whole range of RHIC data for hadron production in d-Au collisions is compatible with geometric scaling. To establish the scaling violations expected from small-x evolution a larger kinematic range in transverse momentum and rapidity would ... More

Constraints for non-zero secondary loadings in confirmatory factor analysisMar 11 2015Dec 20 2015In the context of confirmatory factor analysis, the independent clusters model has been found to be overly restrictive in several research contexts. Therefore, a less restrictive criterion for parsimony of non-salient loadings in confirmatory factor analysis ... More

Orbispaces and Orbifolds from the Point of View of the Borel Construction, a new DefinitionDec 01 2001``An orbifold is a space which is locally modeled on the quotient of a vector space by a finite group.'' This sentence is so easily said or written that more than one person has missed some of the subtleties hidden by orbifolds. Orbifolds were first introduced ... More

Exact bulk correlation functions in one-dimensional nonadditive hard-core mixturesDec 03 2007In a recent paper [Phys. Rev. E \textbf{76}, 031202 (2007)], Schmidt has proposed a Fundamental Measure Density Functional Theory for one-dimensional nonadditive hard-rod fluid mixtures and has compared its predictions for the bulk structural properties ... More

Standard Model FitsJun 24 2002Recent results of tests of the Standard Model of electroweak interactions are presented. Data are used from the four LEP experiments, ALEPH, DELPHI, L3, OPAL, the SLD experiment at SLC, the TEVATRON p-pbar experiments CDF and D0 and the NuTeV neutrino ... More

Process chain approach to high-order perturbation calculus for quantum lattice modelsNov 14 2008Jun 29 2009A method based on Rayleigh-Schroedinger perturbation theory is developed that allows to obtain high-order series expansions for ground-state properties of quantum lattice models. The approach is capable of treating both lattice geometries of large spatial ... More

Exact Hairy Black HolesNov 12 2012Nov 13 2012This proceeding reviews the recent finding of a certain class of, regular on and outside the horizon, exact hairy black hole solutions in four dimensional general relativity. Their construction follow from the integrability of a cohomogeneity two Weyl ... More

Observational diagnostics of gas in protoplanetary disksNov 11 2009Protoplanetary disks are composed primarily of gas (99% of the mass). Nevertheless, relatively few observational constraints exist for the gas in disks. In this review, I discuss several observational diagnostics in the UV, optical, near-IR, mid-IR, and ... More

On the equivalence of the SO(2,1) gauged WZW form and Liouville theoryApr 14 2009Jul 25 2011It is proved that Liouville theory and the two dimensional SO(2,1) gauged Wess-Zumino-Witten term are on-shell equivalent. This shed light on a possible higher dimensional generalization of the former theory.

Moving Five-Branes and CosmologyOct 03 2002We discuss low-energy heterotic M-theory with five-branes in four and five dimensions and its application to moving brane cosmology.

Radiation Hardness Studies in a CCD with High-Speed Column Parallel ReadoutNov 22 2007Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The ... More

On group averaging for non-compact groupsDec 05 2000We review some aspects of the use of a technique known as group averaging, which provides a tool for the study of constrained systems. We focus our attention on the case where the gauge group is non-compact, and a `renormalized' group averaging method ... More

Weak functoriality of Cohen-Macaulay algebrasJan 30 2018We prove the weak functoriality of (big) Cohen-Macaulay algebras, which controls the whole skein of "homological conjectures" in commutative algebra [H1][HH2]. Namely, for any local homomorphism $ R\to R'$ of complete local domains, there exists a compatible ... More

Left Invariant Contact Structures on Lie GroupsMar 31 2004Sep 24 2004A result from Gromov ensures the existence of a contact structure on any connected non-compact odd dimensional Lie group. But in general such structures are not invariant under left translations of the Lie group. The problem of finding which Lie groups ... More

Look-Back and Look-Ahead in the Conversion of Hidden Markov Models into Finite State TransducersFeb 02 1998This paper describes the conversion of a Hidden Markov Model into a finite state transducer that closely approximates the behavior of the stochastic model. In some cases the transducer is equivalent to the HMM. This conversion is especially advantageous ... More

Finite State Transducers Approximating Hidden Markov ModelsJul 17 1997This paper describes the conversion of a Hidden Markov Model into a sequential transducer that closely approximates the behavior of the stochastic model. This transformation is especially advantageous for part-of-speech tagging because the resulting transducer ... More

The Structure of Differential Invariants and Differential Cut EliminationApr 11 2011Nov 23 2012The biggest challenge in hybrid systems verification is the handling of differential equations. Because computable closed-form solutions only exist for very simple differential equations, proof certificates have been proposed for more scalable verification. ... More

The factor paradox: Common factors can be correlated with the variance not accounted for by the common factors!Aug 19 2013The case that the factor model does not account for all the covariances of the observed variables is considered. This is a quite realistic condition because some model error as well as some sampling error should usually occur with empirical data. It is ... More

Coding Methods in Computability Theory and Complexity TheoryAug 29 2013A major part of computability theory focuses on the analysis of a few structures of central importance. As a tool, the method of coding with first-order formulas has been applied with great success. For instance, in the c.e. Turing degrees, it has been ... More

A power law for the lowest eigenvalue in localized massive gravityNov 17 2000Nov 27 2000This short note contains a detailed analysis to find the right power law the lowest eigenvalue of a localized massive graviton bound state in a four dimensional AdS background has to satisfy. In contrast to a linear dependence of the cosmological constant ... More

Quantum Solitons in Non-Linear Optics: Resonant Dielectric MediaOct 06 1994It is known that classical electromagnetic radiation at a frequency in resonance with energy splittings of atoms in a dielectric medium can be described using the classical sine-Gordon equation. In this paper we quantize the electromagnetic field and ... More

Strong Coupling Fixed Points of Current Interactions and Disordered Fermions in 2DNov 23 2000Apr 05 2001The all-orders beta function is used to study disordered Dirac fermions in 2D. The generic strong coupling fixed `points' of anisotropic current-current interactions at large distances are actually isotropic manifolds corresponding to subalgebras of the ... More

Gauge Invariance and the Critical Properties of Quantum Hall Plateaux TransitionsApr 28 1999May 14 1999A model consisting of a single massless scalar field with a topological coupling to a pure gauge field is defined and studied. It possesses an SL(2,Z) symmetry as a consequence of the gauge invariance. We propose that by adding impurities the model can ... More

QED for a Fibrillar Medium of Two-Level AtomsApr 17 1996May 31 1996We consider a fibrillar medium with a continuous distribution of two-level atoms coupled to quantized electromagnetic fields. Perturbation theory is developed based on the current algebra satisfied by the atomic operators. The one-loop corrections to ... More

Spectrum Generating Affine Lie Algebras in Massive Field TheoryMay 21 1993Nov 01 1993We present a new application of affine Lie algebras to massive quantum field theory in 2 dimensions, by investigating the $q\to 1$ limit of the q-deformed affine $\hat{sl(2)}$ symmetry of the sine-Gordon theory, this limit occuring at the free fermion ... More

Universality and Decidability of Number-Conserving Cellular AutomataJun 17 2003Number-conserving cellular automata (NCCA) are particularly interesting, both because of their natural appearance as models of real systems, and because of the strong restrictions that number-conservation implies. Here we extend the definition of the ... More

Status of Higgs Boson Searches at the TevatronMar 25 2009Over the last years the Tevatron Run-II has extended several limits on Higgs boson masses and coupling which were pioneered during the LEP accelerator operation between 1989 and 2000. Higgs boson searches will also be at the forefront of research at the ... More

Higgs Physics: from LEP to a Future Linear ColliderFeb 01 2005New preliminary combined results from the LEP experiments on searches for the Higgs boson beyond the Standard Model are presented. The new determination of the top quark mass at the Tevatron in 2004 influences the interpretations of the LEP results in ... More

Highlights of Higgs Physics at LEPFeb 22 2004Final results from the combined data of the four LEP experiments ALEPH, DELPHI, L3 and OPAL on Standard Model (SM) Higgs boson searches are presented. New preliminary results of searches in extended models are reviewed.

Cross-sections and branching ratios for charged Higgs searchesJul 09 2009For the preparation of the experimental search for charged Higgs bosons at the LHC detailed studies have been made to determine the expected charged Higgs boson production cross-sections and decay branching ratios at sqrts = 14 TeV. In the mass regime ... More

Alignment of the Central D-Zero DetectorApr 25 2006The alignment procedure of the Silicon Microstrip Tracker, SMT, and the Central Fiber Tracker, CFT, is described. Alignment uncertainties and resulting systematic errors in physics analyses are addressed.

Higgs physics at a high luminosity e+e- linear colliderSep 30 2002Since the TESLA Technical Design Report (TDR) was published in 2001, the physics programme of an electron-positron linear collider (LC) has been further developed and a wide consensus has been reached on the physics case and the need for a high luminosity ... More

Complete LEP Data: Status of Higgs Boson SearchesDec 05 2001The LEP experiments completed data-taking in November 2000. New preliminary combined results of the four LEP experiments ALEPH, DELPHI, L3 and OPAL are presented for various Higgs boson searches.

Higgs Boson Searches at LEP Up To sqrt(s) = 202 GeVApr 03 2000The latest preliminary combined results of the Higgs boson searches from the LEP experiments ALEPH, DELPHI, L3 and OPAL are presented. A general scan of the MSSM parameters is performed and leads to stringent lower mass limits and for the first time excludes ... More

Heavy-flavour production in hot quark matterNov 23 2010Recent results from RHIC and first measurements from the ALICE experiment at the CERN-Large Hadron Collider (LHC) on open heavy-flavour are presented. We focus on RHIC measurements of single electrons and jet-like heavy-flavour particle correlations. ... More

Recent high pT measurements in STARApr 12 2005Apr 14 2005After five years of data taking, the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory provides precise measurements of particle production at high transverse momentum in p-p, d-Au, and Au-Au collisions at ... More

Scale invariant cosmology III: dynamical models and comparisons with observationsMay 19 2016We examine the properties of the scale invariant cosmological models, also making the specific hypothesis of the scale invariance of the empty space at large scales. Numerical integrations of the cosmological equations for different values of the curvature ... More

Scale invariant cosmology I: the vacuum and the cosmological constantMay 19 2016The source of the acceleration of the expansion of the Universe is still unknown. We examine some consequences of the possible scale invariance of the empty space at large scales. The central hypothesis of this work is that, at macroscopic and large scales ... More

Depleted-Uranium Weapons: the Whys and WhereforesJan 23 2003May 08 2003The only military application in which depleted-uranium (DU) alloys out-perform present-day tungsten alloys is long-rod penetration into a main battle-tank's armor. However, this advantage is only on the order of 10%, and it disappears when the comparison ... More

Can one improve the Froissart bound?Dec 03 2008Feb 20 2009We explain why we hope that the Froissart bound can be improved, either qualitatively or, more likely, quantitatively, by making a better use of unitarity, in particular elastic unitarity. In other instances (Gribov's theorem) elastic unitarity played ... More

The status of the heavy quark systemsMay 15 2007We review various inequalities on the order and the spacing of energy levels, wave function at the origin, etc... which were obtained since 1977 in the framework of the Schrodinger equation and applied to quarkonium and also to muonic atoms and alcaline ... More

A simple model kinetic equation for inelastic Maxwell particlesAug 29 2006The model of inelastic Maxwell particles (IMP) allows one to derive some exact results which show the strong influence of inelasticity on the nonequilibrium properties of a granular gas. The aim of this work is to propose a simple model kinetic equation ... More

Granular fluid thermostatted by a bath of elastic hard spheresJan 20 2003Feb 28 2003The homogeneous steady state of a fluid of inelastic hard spheres immersed in a bath of elastic hard spheres kept at equilibrium is analyzed by means of the first Sonine approximation to the (spatially homogeneous) Enskog--Boltzmann equation. The temperature ... More

Transport coefficients of d-dimensional inelastic Maxwell modelsApr 03 2002Oct 17 2002Due to the mathematical complexity of the Boltzmann equation for inelastic hard spheres, a kinetic model has recently been proposed whereby the collision rate (which is proportional to the relative velocity for hard spheres) is replaced by an average ... More

Does the Chapman-Enskog expansion for viscous granular flows converge?Apr 16 2008This paper deals with the convergence/divergence issue of the Chapman-Enskog series expansion of the shear and normal stresses for a granular gas of inelastic hard spheres. From the exact solution of a simple kinetic model in the uniform shear and longitudinal ... More

Singularities of Lagrangian mean curvature flow: zero-Maslov class caseAug 15 2006We study singularities of Lagrangian mean curvature flow in $\C^n$ when the initial condition is a zero-Maslov class Lagrangian. We start by showing that, in this setting, singularities are unavoidable. More precisely, we construct Lagrangians with arbitrarily ... More

Three-tier CFTs from Frobenius algebrasApr 27 2013Dec 23 2013These are lecture notes of a course given at the Summer School on Topology and Field Theories held at the Centre for Mathematics of the University of Notre Dame, Indiana, from May 29 to June 2, 2012. The idea of extending quantum field theories to manifolds ... More

Observational properties of the open cluster system of the Milky Way and what they tell us about our GalaxyNov 09 2009Almost 80 years have passed since Trumpler's analysis of the Galactic open cluster system laid one of the main foundations for understanding the nature and structure of the Milky Way. Since then, the open cluster system has been recognised as a key source ... More

Geodesic restrictions for the Casimir operatorDec 13 2010Jul 27 2011We consider the hyperbolic Casimir operator C defined on the tangent sphere bundle SY of a compact hyperbolic Riemann surface Y. We prove a nontrivial bound on the L^2-norm of the restriction of eigenfunctions of C to certain natural hypersurfaces in ... More

On the global triggering mechanism of star formation in galaxiesSep 23 2009We study the large-scale triggering of star formation in galaxies. We find that the largest mass-scale not stabilized by rotation, a well defined quantity in a rotating system and with clear dynamical meaning, strongly correlates with the star formation ... More

Longitudinal Viscous Flow in Granular GasesSep 10 2008The flow characterized by a linear longitudinal velocity field $u_x(x,t)=a(t)x$, where $a(t)={a_0}/({1+a_0t})$, a uniform density $n(t)\propto a(t)$, and a uniform temperature $T(t)$ is analyzed for dilute granular gases by means of a BGK-like model kinetic ... More