Results for "Daniel Lohmann"

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Families of canonically polarized manifolds over log Fano varietiesJul 22 2011Let (X,D) be a dlt pair, where X is a normal projective variety. Let S denote the support of the rounddown of D, and K the canonical divisor of X. We show that any smooth family of canonically polarized varieties over X\S is isotrivial if the divisor ... More
A New Framework for $\mathcal{H}_2$-Optimal Model ReductionSep 21 2017In this contribution, a new framework for H2-optimal reduction of multiple-input, multiple- output linear dynamical systems by tangential interpolation is presented. The framework is motivated by the local nature of both tangential interpolation and H2-optimal ... More
The List is the Process: Reliable Pre-Integration Tracking of Commits on Mailing ListsFeb 08 2019A considerable corpus of research on software evolution focuses on mining changes in software repositories, but omits their pre-integration history. We present a novel method for tracking this otherwise invisible evolution of software changes on mailing ... More
Observing Custom Software Modifications: A Quantitative Approach of Tracking the Evolution of Patch StacksJul 04 2016Modifications to open-source software (OSS) are often provided in the form of "patch stacks" - sets of changes (patches) that modify a given body of source code. Maintaining patch stacks over extended periods of time is problematic when the underlying ... More
A Graph-Partition-Based Scheduling Policy for Heterogeneous ArchitecturesFeb 26 2015In order to improve system performance efficiently, a number of systems choose to equip multi-core and many-core processors (such as GPUs). Due to their discrete memory these heterogeneous architectures comprise a distributed system within a computer. ... More
Deformations along subsheavesMay 17 2009Mar 29 2010Let f : Y -> X be a morphism of complex projective manifolds, and let F be a subsheaf of the tangent bundle which is closed under the Lie bracket, but not necessarily a foliation. This short paper contains an elementary and very geometric argument to ... More
Model reduction of linear time-varying systems with applications for moving loadsJul 11 2016In this paper we consider different model reduction techniques for systems with moving loads. Due to the time-dependency of the input and output matrices, the application of time-varying projection matrices for the reduction offers new degrees of freedom, ... More
Critical two-point function for long-range $O(n)$ models below the upper critical dimensionMay 23 2017Sep 20 2017We consider the $n$-component $|\varphi|^4$ lattice spin model ($n \ge 1$) and the weakly self-avoiding walk ($n=0$) on $\mathbb{Z}^d$, in dimensions $d=1,2,3$. We study long-range models based on the fractional Laplacian, with spin-spin interactions ... More
$\mathcal{H}_2$ Pseudo-Optimal Reduction of Structured DAEs by Rational InterpolationApr 23 2018In this contribution, we extend the concept of $\mathcal{H}_2$ inner product and $\mathcal{H}_2$ pseudo-optimality to dynamical systems modeled by differential-algebraic equations (DAEs). To this end, we derive projected Sylvester equations that characterize ... More
Boolean Dependence Logic and Partially-Ordered ConnectivesJun 27 2014We introduce a new variant of dependence logic called Boolean dependence logic. In Boolean dependence logic dependence atoms are of the type =(x_1,...,x_n,\alpha), where \alpha is a Boolean variable. Intuitively, with Boolean dependence atoms one can ... More
Thermodynamics of the pyrochlore-lattice quantum Heisenberg antiferromagnetJan 26 2019We use the rotation-invariant Green's function method (RGM) and the high-temperature expansion (HTE) to study the thermodynamic properties of the Heisenberg antiferromagnet on the pyrochlore lattice. We discuss the excitation spectra as well as various ... More
Electromagnetic and Weak Moments of the Tau-LeptonJan 25 2005Feb 04 2005The electromagnetic and weak dipole moments of the Tau-lepton have been measured by experiments at e+e- colliders. Data samples of e+e- --> tau+tau-, e+e- --> tau+tau- gamma and e+e- --> e+e-tau+tau- events collected at centre-of-mass energies between ... More
Task-related edge density (TED) - a new method for revealing large-scale network formation in fMRI data of the human brainDec 14 2015The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we ... More
R&D for Very Forward Calorimeters at the ILC DetectorFeb 19 2009Special calorimeters are needed to instrument the very forward region of an ILC detector. These devices will improve the hermeticity being important for new particle searches. A luminometer is foreseen to measure the rate of low angle Bhabha scattering ... More
e^+e^- Physics at LEP and a Future Linear ColliderFeb 01 2002A summary of results obtained from e^+e^- annihilations at LEP is given. The precision measurements around the Z resonance, the results from charged gauge boson production and searches for new particles are reviewed. Particular emphasis is devoted to ... More
Practicable Simulation-Free Model Order Reduction by Nonlinear Moment MatchingJan 30 2019In this paper, a practicable simulation-free model order reduction method by nonlinear moment matching is developed. Based on the steady-state interpretation of linear moment matching, we comprehensively explain the extension of this reduction concept ... More
Complexity of Model Checking for Modal Dependence LogicApr 06 2011Jan 27 2012Modal dependence logic (MDL) was introduced recently by V\"a\"an\"anen. It enhances the basic modal language by an operator =(). For propositional variables p_1,...,p_n the atomic formula =(p_1,...,p_(n-1),p_n) intuitively states that the value of p_n ... More
Complexity Results for Modal Dependence LogicApr 04 2011Modal dependence logic was introduced recently by V\"a\"an\"anen. It enhances the basic modal language by an operator =(). For propositional variables p_1,...,p_n, =(p_1,...,p_(n-1);p_n) intuitively states that the value of p_n is determined by those ... More
Structure-preserving constrained optimal trajectory planning of a wheeled inverted pendulumNov 29 2018The Wheeled Inverted Pendulum (WIP) is an underactuated, nonholonomic mechanical system, and has been popularized commercially as the Segway. Designing a control law for motion planning, that incorporates the state and control constraints, while respecting ... More
Measurement of the Higgs Cross Section and Mass with Linear CollidersAug 30 1999We report on the accuracy of the measurement of the Higgs boson mass and the total cross section of the process e+e- -> ZH that would be achieved in a linear collider operating at a centre-of-mass energy of 350 GeV, assuming an integrated luminosity of ... More
Notes on non-trivial and logarithmic CFTs with c=0Oct 12 2005We examine the properties of two-dimensional conformal field theories (CFTs) with vanishing central charge based on the extended Kac-table for c_(9,6)=0 using a general ansatz for the stress energy tensor residing in a Jordan cell of rank two. Within ... More
Proposal for a CFT interpretation of Watts' differential equation for percolationJul 21 2005Nov 21 2005G. M. T. Watts derived that in two dimensional critical percolation the crossing probability Pi_hv satisfies a fifth order differential equation which includes another one of third order whose independent solutions describe the physically relevant quantities ... More
Eighth-order high-temperature expansion for general Heisenberg HamiltoniansDec 05 2011We explicitly calculate the moments $t_n$ of general Heisenberg Hamiltonians up to eighth order. They have the form of finite sums of products of two factors. The first factor is represented by a (multi-)graph which has to be evaluated for each particular ... More
Measurement of the Higgs Boson Mass with a Linear e+e- ColliderMay 30 2005The potential of a linear e+e- collider operated at a centre-of-mass energy of 350 GeV is studied for the measurement of the Higgs boson mass. An integrated luminosity of 500 fb-1 is assumed. For Higgs boson masses of 120, 150 and 180 GeV the uncertainty ... More
Moments of general Heisenberg Hamiltonians up to sixth orderDec 19 2010Jun 30 2011We explicitly calculate the moments t_n of general Heisenberg Hamiltonians up to sixth order. They have the form of finite sums of products of two factors, the first factor being represented by a multigraph and the second factor being a polynomial in ... More
Tenth-order high-temperature expansion for the susceptibility and the specific heat of spin-s Heisenberg models with arbitrary exchange patterns: Application to pyrochlore and kagome magnetsSep 04 2013Jan 20 2014We present the high-temperature expansion (HTE) up to 10th order of the specific heat C and the uniform susceptibility \chi for Heisenberg models with arbitrary exchange patterns and arbitrary spin quantum number s. We encode the algorithm in a C++ program ... More
The Impact of BeamCal Performance at Different ILC Beam Parameters and Crossing Angles on \tilde{tau} searchesOct 19 2006The ILC accelerator parameters and detector concepts are still under discussion in the world-wide community. As will be shown, the performance of the BeamCal, the calorimeter in the very forward area of the ILC detector, is very sensitive to the beam ... More
Inflating with BaryonsSep 15 2010We present a field theory solution to the eta problem. By making the inflaton field the phase of a baryon of SU(N_c) supersymmetric Yang-Mills theory we show that all operators that usually spoil the flatness of the inflationary potential are absent. ... More
Supergravity for Effective TheoriesSep 01 2011Higher-derivative operators are central elements of any effective field theory. In supersymmetric theories, these operators include terms with derivatives in the K\"ahler potential. We develop a toolkit for coupling such supersymmetric effective field ... More
Scaling Laws in Self-Gravitating DisksApr 16 1999The interstellar medium (ISM) reveals strongly inhomogeneous structures at every scale. These structures do not seem completely random since they obey certain power laws. Larson's law (\citeyear{Larson81}) $\sigma \propto R^{\delta}$ and the plausible ... More
Five basic lemmas for symmetric tensor products of normed spacesMay 18 2011We give the symmetric version of five lemmas which are essential for the theory of tensor products (and norms). These are: the approximation, extension, embedding, density and local technique lemmas. Some application of these tools to the metric theory ... More
Long-Range Correlations in Self-Gravitating N-Body SystemsJan 29 2002Observed self-gravitating systems reveal often fragmented non-equilibrium structures that feature characteristic long-range correlations. However, models accounting for non-linear structure growth are not always consistent with observations and a better ... More
Lumpy Structures in Self-Gravitating DisksMay 29 2001Following Toomre & Kalnajs (1991), local models of slightly dissipative self-gravitating disks show how inhomogeneous structures can be maintained over several galaxy rotations. Their basic physical ingredients are self-gravity, dissipation and differential ... More
Natural symmetric tensor normsFeb 22 2010Dec 14 2010In the spirit of the work of Grothendieck, we introduce and study natural symmetric n-fold tensor norms. We prove that there are exactly six natural symmetric tensor norms for $n\ge 3$, a noteworthy difference with the 2-fold case in which there are four. ... More
Equilateral Non-Gaussianity and New Physics on the HorizonFeb 25 2011Mar 23 2011We examine the effective theory of single-field inflation in the limit where the scalar perturbations propagate with a small speed of sound. In this case the non-linearly realized time-translation symmetry of the Lagrangian implies large interactions, ... More
Formalizing and Checking Thread Refinement for Data-Race-Free Execution Models (Extended Version)Oct 24 2015When optimizing a thread in a concurrent program (either done manually or by the compiler), it must be guaranteed that the resulting thread is a refinement of the original thread. Most theories of valid optimizations are formulated in terms of valid syntactic ... More
The symmetric Radon-Nikodým property for tensor normsMay 15 2010We introduce the symmetric-Radon-Nikod\'ym property (sRN property) for finitely generated s-tensor norms $\beta$ of order $n$ and prove a Lewis type theorem for s-tensor norms with this property. As a consequence, if $\beta$ is a projective s-tensor norm ... More
Signatures of Supersymmetry from the Early UniverseSep 01 2011Oct 11 2011Supersymmetry plays a fundamental role in the radiative stability of many inflationary models. Spontaneous breaking of the symmetry inevitably leads to fields with masses of order the Hubble scale during inflation. When these fields couple to the inflaton ... More
Desensitizing Inflation from the Planck ScaleApr 21 2010A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale ... More
Casimir force in O(n) lattice models with a diffuse interfaceJun 23 2008On the example of the spherical model we study, as a function of the temperature $T$, the behavior of the Casimir force in O(n) systems with a diffuse interface and slab geometry $\infty^{d-1}\times L$, where $2<d<4$ is the dimensionality of the system. ... More
Fragmentation in Kinematically Cold DisksJan 16 2001Gravity is scale free. Thus gravity may form similar structures in self-gravitating systems on different scales. Indeed, observations of the interstellar medium, spiral disks and cosmic structures, reveal similar characteristics. The structures in these ... More
Extending polynomials in maximal and minimal idealsOct 20 2009Feb 08 2010Given an homogeneous polynomial on a Banach space $E$ belonging to some maximal or minimal polynomial ideal, we consider its iterated extension to an ultrapower of $E$ and prove that this extension remains in the ideal and has the same ideal norm. As ... More
Unconditionality in tensor products and ideals of polynomials, multilinear forms and operatorsJun 17 2009Feb 08 2010We study tensor norms that destroy unconditionality in the following sense: for every Banach space $E$ with unconditional basis, the $n$-fold tensor product of $E$ (with the corresponding tensor norm) does not have unconditional basis. We establish an ... More
A Field Range Bound for General Single-Field InflationNov 13 2011We explore the consequences of a detection of primordial tensor fluctuations for general single-field models of inflation. Using the effective theory of inflation, we propose a generalization of the Lyth bound. Our bound applies to all single-field models ... More
Four-terminal magneto-transport in graphene p-n junctions created by spatially selective dopingMar 31 2009In this paper we describe a graphene p-n junction created by chemical doping. We find that chemical doping does not reduce mobility in contrast to top-gating. The preparation technique has been developed from systematic studies about influences on the ... More
Prospects to Measure the Higgs Boson Mass and Cross Section in ee-->ZH Using the Recoil Mass SpectrumOct 13 2007The process ee-->ZH allows to measure the Higgs boson in the recoil mass spectrum against the Z boson without any assumptions on the Higgs boson decay. We performed a full simulation and reconstruction of ee-->ZH using the MOKKA and MARLIN packages describing ... More
Tachyons in Classical de Sitter VacuaMar 29 2016We revisit the possibility of de Sitter vacua and slow-roll inflation in type II string theory at the level of the classical two-derivative supergravity approximation. Previous attempts at explicit constructions were plagued by ubiquitous tachyons with ... More
Precision Stellar Astrophysics in the Kepler EraApr 25 2016The study of fundamental properties (such as temperatures, radii, masses, and ages) and interior processes (such as convection and angular momentum transport) of stars has implications on various topics in astrophysics, ranging from the evolution of galaxies ... More
N-Body Simulations of Open, Self-Gravitating SystemsJan 16 2001Astrophysical systems differ often in two points from classical thermodynamical systems: 1.) They are open and 2.) gravity is a dominant factor. Both modifies the homogeneous equilibrium structure, known from classical thermodynamics. In order to study ... More
Null Polarities as Generators of the Projective GroupJun 02 2014It is well-known that the group of regular projective transformations of $\mathbb{P}^3(\mathbb{R})$ is isomorphic to the group of projective automorphisms of Klein's quadric $M_2^4\subset\mathbb{P}^5(\mathbb{R})$. We introduce the Clifford algebra $\mathcal{C}\ell_{(3,3)}$ ... More
A Criticism of "Gas Mode" Reinterpretations of the Michelson-Morley and Similar ExperimentsApr 24 2014It has been argued by R. T. Cahill and others that a Michelson interferometer in "gas mode" - in which the light paths are through an included gaseous medium - are able to detect and have detected an absolute frame of reference. It is shown here that ... More
A Case for Lorentzian RelativityJan 18 2014Mar 06 2015The Lorentz transformation (LT) is explained by changes occurring in the wave characteristics of matter as it changes inertial frame. This explanation is akin to that favoured by Lorentz, but informed by later insights, due primarily to de Broglie, regarding ... More
Syntagma Lexical DatabaseMar 19 2015This paper discusses the structure of Syntagma's Lexical Database (focused on Italian). The basic database consists in four tables. Table Forms contains word inflections, used by the POS-tagger for the identification of input-words. Forms is related to ... More
What is dimensional reduction really telling us?Sep 25 2015Oct 12 2015Numerous approaches to quantum gravity report a reduction in the number of spacetime dimensions at the Planck scale. However, accepting the reality of dimensional reduction also means accepting its consequences, including a variable speed of light. We ... More
Generalized amalgamation and homogeneityMar 31 2016May 05 2016In this paper we shall prove that any $2$-transitive finitely homogeneous structure with a supersimple theory satisfying a generalized amalgamation property is a random structure. In particular, this adapts a result of Koponen for binary homogeneous structures ... More
Towards a Theory of Affect and Software Developers' PerformanceJan 12 2016Jan 23 2016For more than thirty years, it has been claimed that a way to improve software developers' productivity and software quality is to focus on people. The underlying assumption seems to be that "happy and satisfied software developers perform better". More ... More
Logic and linear algebra: an introductionJul 09 2014Aug 24 2015We give an introduction to logic tailored for algebraists, explaining how proofs in linear logic can be viewed as algorithms for constructing morphisms in symmetric closed monoidal categories with additional structure. This is made explicit by showing ... More
Green open access in computer science - an exploratory study on author-based self-archiving awareness, practice, and inhibitorsMay 05 2015Access to the work of others is something that is too often taken for granted, yet problematic and difficult to be obtained unless someone pays for it. Green and gold open access are claimed to be a solution to this problem. While open access is gaining ... More
Meromorphic quotients for some holomorphic G-actionsMay 26 2015Using mainly tools from [B.13] and [B.15] we give a necessary and sufficient condition in order that a holomorphic action of a connected complex Lie group $G$ on a reduced complex space $X$ admits a strongly quasi-proper meromorphic quotient. We apply ... More
Some examples due to H. HironakaJan 06 2015Mar 26 2015The aim of this paper is to explain the construction by H. Hironaka [H.61] of a holomorphic (in fact "algebraic") family of compact complex manifolds parametrized by $\C$ such for all $s \in \C\setminus \{0\}$ the fiber is projective, but such that the ... More
Asymptotics of a vanishing period : characterization of semi-simplicityJan 31 2013In this paper we introduce the word {\em fresco} to denote a monogenic geometric (a,b)-module. This "basic object" (generalized Brieskorn module with one generator) corresponds to the formal germ of the minimal filtered (regular) differential equation. ... More
The theme of a vanishing periodOct 06 2011Let \ $\lambda \in \mathbb{Q}^{*+}$ \ and consider a multivalued formal function of the type $$ \phi(s) : = \sum_{j=0}^k \ c_j(s).s^{\lambda + m_j}.(Log\, s)^j $$ where \ $c_j \in \C[[s]], m_j \in \mathbb{N}$ \ for \ $j \in [0,k-1]$. The {\bf theme} associated ... More
Holomorphic families of $[λ]-$primitive themesAug 12 2015This article is the continuation of [B. 13-b] where we show how the isomorphism class of a $[\lambda]-$primitive theme with a given Bernstein polynomial may be characterized by a (small) finite number of complex parameters. We construct here a corresponding ... More
Algebraic differential equations associated to some polynomialsMay 29 2013Mar 01 2014We compute the Gauss-Manin differential equation for any period of a polynomial in \ $\C[x_{0},\dots, x_{n}]$ \ with \ $(n+2)$ \ monomials. We give two general factorizations theorem in the algebra \ $\C< z, (\frac{\partial}{\partial z})^{-1}>$ \ for ... More
Changements de variable pour un th`eme.Mar 26 2010We study the behaviour of the notion of "thema", introduced in our previous article [B.09b], by a change of variable. We show not only that the fundamental invariants of such a thema, corresponding to the Bernstein polynomial, are stable by a change of ... More
Tau lepton reconstruction at collider experiments using impact parametersJul 07 2015Nov 06 2015We present a novel method for the reconstruction of events containing pairs of hadronically decaying tau leptons at collider experiments. This method relies on accurate knowledge of the tau production vertex and precise measurement of its charged decay ... More
A polynomial invariant of diffeomorphisms of 4-manifoldsNov 23 1999We use a 1-parameter version of gauge theory to investigate the topology of the diffeomorphism group of 4-manifolds. A polynomial invariant, analogous to the Donaldson polynomial, is defined, and is used to show that the diffeomorphism group of certain ... More
Quantum Error Correction and Fault-ToleranceJul 18 2005I give an overview of the basic concepts behind quantum error correction and quantum fault tolerance. This includes the quantum error correction conditions, stabilizer codes, CSS codes, transversal gates, fault-tolerant error correction, and the threshold ... More
The Heisenberg Representation of Quantum ComputersJul 01 1998Since Shor's discovery of an algorithm to factor numbers on a quantum computer in polynomial time, quantum computation has become a subject of immense interest. Unfortunately, one of the key features of quantum computers - the difficulty of describing ... More
A Theory of Fault-Tolerant Quantum ComputationFeb 12 1997Feb 18 1997In order to use quantum error-correcting codes to actually improve the performance of a quantum computer, it is necessary to be able to perform operations fault-tolerantly on encoded states. I present a general theory of fault-tolerant operations based ... More
Pasting Quantum CodesJul 31 1996I describe a method for pasting together certain quantum error-correcting codes that correct one error to make a single larger one-error quantum code. I show how to construct codes encoding 7 qubits in 13 qubits using the method, as well as 15 qubits ... More
An obstruction to smooth isotopy in dimension 4Jul 09 1998Dec 14 1998Techniques of gauge theory are used to define and compute an invariant of certain diffeomorphisms of 4-manifolds. The invariant vanishes for any diffeomorphism which is smoothly isotopic to the identity. As an application, we give the first example of ... More
The model of interacting spatial permutations and its relation to the Bose gasDec 14 2007Mar 15 2008The model of spatial permutations is related to the Feynman-Kac representation of the Bose gas. The transition to infinite cycles corresponds to Bose-Einstein condensation. We review the general setting and some results, and we derive a multi-body interaction ... More
Dévissages des F-complexes de D-modules arithmétiques en F-isocristaux surconvergentsMar 28 2005Apr 12 2005Nous d\'efinissons et \'etudions les d\'evissages des $F$-complexes de $\mathcal{D}$-modules arithm\'etiques en $F$-isocristaux surconvergents. Nous prouvons que les $F$-complexes surholonomes sont d\'evissables en $F$-isocristaux surconvergents. On \'etablit ... More
Infinitesimal contraction of the Feigenbaum renormalization operator in the horizontal directionMay 18 2002In this short note, we give a sketch of a new proof of the exponential contraction of the Feigenbaum renormalization operator in the hybrid class of the Feigenbaum fixed point. The proof uses the non existence of invariant line fields in the Feigenbaum ... More
Transverse polarization distribution and fragmentation functionsDec 11 1999Apr 27 2000We discuss transverse polarization distribution and fragmentation functions, in particular, T-odd functions with transverse momentum dependence, which might be relevant for the description of single transverse spin asymmetries. The role of intrinsic tranverse ... More
Transverse Lambda Polarization at LHCJul 09 2009Transverse polarization of Lambda hyperons produced in p p and p Pb collisions is discussed. A factorized description in the intermediate to high p_T region is considered that involves transverse momentum and spin dependence in the fragmentation process. ... More
Gluon saturation effects on single spin asymmetriesNov 29 2006We consider forward pion production in p p collisions at RHIC energies,which probes the so-called Extended Geometric Scaling region. Upon inclusion of small-x effects via an anomalous dimension within the Color Glass Condensate formalism at leading order ... More
Hadron structure from gamma^* p scattering: interpreting hadronic matrix elementsSep 30 2004Oct 05 2004Hadron structure from high-Q^2 gamma^* p scattering processes is often expressed in terms of hadronic matrix elements of nonlocal operators. Properly defining and interpreting these quantities is very important in light of experiments aiming to extract ... More
Transversely polarized Lambda productionJul 05 2000Transversely polarized Lambda production in hard scattering processes is discussed in terms of a leading twist T-odd fragmentation function which describes the fragmentation of an unpolarized quark into a transversely polarized Lambda. We focus on the ... More
The K3 category of a cubic fourfoldMay 07 2015Sep 12 2016Smooth cubic fourfolds are linked to K3 surfaces via their Hodge structures, due to work of Hassett, and via Kuznetsov's K3 category A. The relation between these two viewpoints has recently been elucidated by Addington and Thomas. In this paper, both ... More
Introduction to stability conditionsNov 07 2011Oct 25 2012These are notes of a course given at the 'school on moduli spaces' at the Newton Institute in January 2011. The abstract theory of stability conditions (due to Bridgeland and Douglas) on abelian and triangulated categories is developed via tilting and ... More
Derived and abelian equivalence of K3 surfacesApr 06 2006Tom Bridgeland constructed explicit stability conditions on K3 surfaces. This paper attempts to shed more light on these particular examples, especially on the hearts of the underlying t-structures. We prove that two K3 surfaces X and X' are derived equivalent ... More
The Kaehler cone of a compact hyperkaehler manifoldSep 19 1999Jun 03 2001This is an attempt towards the understanding of the (birational) Kaehler cone of a compact hyperkaehler manifold in terms of the Beauville-Bogomolov form on its second cohomology. We discuss birational correspondences between hyperkaehler manifolds and ... More
Birational symplectic manifolds and their deformationsJan 17 1996Jan 17 1996The known counterexamples to the global Torelli theorem for higher-dimensional hyperkahler manifolds are provided by birational manifolds. We address the question whether two birational hyperkahler manifolds (i.e. irreducible symplectic) manifolds always ... More
Dynamics of Accretion Flows Irradiated by a QuasarFeb 21 2007We present the results from axisymmetric time-dependent HD calculations of gas flows which are under the influence of gravity of a black hole in quasars. We assume that the flows are non-rotating and exposed to quasar radiation. We take into account X-ray ... More
Theory of winds in AGNsJan 04 2007I present a brief review of theory of winds in active galactic nuclei (AGN). Magnetic, radiation, and thermal driving likely operate in AGN. In many cases, it is difficult to distinguish, both from observational and theoretical point of view, which of ... More
Virial statistical description of non-extensive hierarchical systemsMay 26 2006In a first part the scope of classical thermodynamics and statistical mechanics is discussed in the broader context of formal dynamical systems, including computer programmes. In this context classical thermodynamics appears as a particular theory suited ... More
Novel type of orbital ordering: complex orbitals in doped Mott insulatorsApr 04 2000Apr 05 2000An orbital ordering, often observed in Mott insulators with orbital degeneracy, is usually supposed to disappear with doping, e.g. in the ferromagnetic metallic phase of manganites. We propose that the orbital ordering of a novel type may exist in such ... More
Aubry sets vs Mather sets in two degrees of freedomMar 18 2008Sep 04 2009We study autonomous Tonelli Lagrangians on closed surfaces. We aim to clarify the relationship between the Aubry set and the Mather set, when the latter consists of periodic orbits which are not fixed points. Our main result says that in that case the ... More
Nature's softwareApr 20 2014I bring forward some arguments to support the thesis that nature is fundamentally discrete, and present my own thoughts about the direction in which one could look for a possible, consistent "theory of everything" describing gravitation and quantum particles. ... More
Local Geometry of Singular Real Analytic SurfacesJan 15 1999Let V be a compact real analytic surface with isolated singularities embedded in $R^N$, and assume its smooth part is equipped with a Riemannian metric that is induced from some analytic Riemannian metric on $R^N$. We prove: 1. Each point of V has a neighborhood ... More
A Strong Edge-Coloring of Graphs with Maximum Degree 4 Using 22 ColorsJan 25 2006In 1985, Erd\H{o}s and Ne\'{s}etril conjectured that the strong edge-coloring number of a graph is bounded above by ${5/4}\Delta^2$ when $\Delta$ is even and ${1/4}(5\Delta^2-2\Delta+1)$ when $\Delta$ is odd. They gave a simple construction which requires ... More
Warm dark matter at small scales: peculiar velocities and phase space densityNov 09 2010May 03 2011We study the scale and redshift dependence of the power spectra for density perturbations and peculiar velocities, and the evolution of a coarse grained phase space density for (WDM) particles that decoupled during the radiation dominated stage. The (WDM) ... More
Limit groups for relatively hyperbolic groups, I: The basic toolsDec 24 2004Mar 20 2008We begin the investigation of Gamma-limit groups, where Gamma is a torsion-free group which is hyperbolic relative to a collection of free abelian subgroups. Using the results of Drutu and Sapir, we adapt the results from math.GR/0404440 to this context. ... More
Quantum Brownian representation for the quantum field modesNov 02 2007May 26 2009When analyzing the particle-like excitations in quantum field theory it is natural to regard the field mode corresponding to the particle momentum as an open quantum system, together with the opposite momentum mode. Provided that the state of the field ... More
On Lower Bound Methods for Tree-like Cutting Plane ProofsJan 05 2013In the book Boolean Function Complexity by Stasys Jukna, two lower bound techniques for Tree-like Cutting Plane proofs (henceforth, "Tree-CP proofs") using Karchmer-Widgerson type communication games (henceforth, "KW games") are presented: The first, ... More
Chiral 1/M^2 corrections to B^(*) -> D^(*) at Zero Recoil in Quenched Chiral Perturbation TheoryOct 14 2002Heavy quark effective theory can be used to calculate the values of the semileptonic B^(*) -> D^(*) decays in the limit that the heavy quark masses are infinite. We calculate the lowest order chiral corrections, which are of O(1/M^2), from the breaking ... More
How a quark-gluon plasma phase modifies the bounds on extra dimensions from SN 1987aFeb 16 2001Jul 23 2001The shape of the neutrino pulse from the supernova SN1987a provides one of the most stringent constraints on the size of large, compact, "gravity-only" extra dimensions. Previously, calculations have been carried out for a newly-born proto-neutron star ... More
Black Hole Entropy and Entropy of EntanglementMar 03 1995Jul 20 1995We compare the one-loop corrections to the entropy of a black hole, from quantum fields of spin zero, one-half, and one, to the entropy of entanglement of the fields. For fields of spin zero and one-half the black hole entropy is identical to the entropy ... More