Results for "Mathias Fischer"

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Vincia for Hadron CollidersMay 19 2016Jun 14 2016We present the first public implementation of antenna-based QCD initial- and final-state showers. The shower kernels are $2\to 3$ antenna functions, which capture not only the collinear dynamics but also the leading soft (coherent) singularities of QCD ... More
The VINCIA Antenna Shower for Hadron CollidersSep 23 2016We summarise the main features of VINCIA's antenna-based treatment of QCD initial- and final-state showers, which includes iterated tree-level matrix-element corrections and automated evaluations of perturbative shower uncertainties. The latter are computed ... More
Vincia for Hadron CollidersMay 19 2016Nov 11 2016We present the first public implementation of antenna-based QCD initial- and final-state showers. The shower kernels are $2\to 3$ antenna functions, which capture not only the collinear dynamics but also the leading soft (coherent) singularities of QCD ... More
Symplectic Lie algebras with degenerate centerSep 12 2016Every symplectic Lie algebra with degenerate (including non-abelian nilpotent symplectic Lie algebras) has the structure of a quadratic extension. We give a standard model and describe the equivalence classes on the level of corresponding quadratic cohomology ... More
Metric Symplectic Lie AlgebrasSep 12 2016Every metric symplectic Lie algebra has the structure of a quadratic extension. We give a standard model and describe the equivalence classes on the level of corresponding quadratic cohomology sets. Finally, we give a scheme to classify the isomorphism ... More
Lattices of oscillator groupsMar 08 2013Aug 01 2013This paper is concerned with discrete, uniform subgroups (lattices) of oscillator groups, which are certain semidirect products of the Heisenberg group and the additive group of real numbers. The present paper rectifies the uncertainties in [1] of Medina ... More
Discrete chain graph modelsSep 04 2009The statistical literature discusses different types of Markov properties for chain graphs that lead to four possible classes of chain graph Markov models. The different models are rather well understood when the observations are continuous and multivariate ... More
Multiple solutions to the likelihood equations in the Behrens-Fisher problemMay 31 2007The Behrens-Fisher problem concerns testing the equality of the means of two normal populations with possibly different variances. The null hypothesis in this problem induces a statistical model for which the likelihood function may have more than one ... More
The differential structure of the Brieskorn latticeJun 05 2003Dec 01 2004We describe an algorithm to compute M. Saito's matrices A0 and A1 for an isolated hypersurface singularity. They determine the differential structure of the Brieskorn lattice, the spectral pairs and Hodge numbers, and the complex monodromy of the singularity. ... More
Combinatorial duality of Hilbert schemes of points in the affine planeDec 31 2013Jul 02 2014The Hilbert scheme of $n$ points in the affine plane contains the open subscheme parametrizing $n$ distinct points in the affine plane, and the closed subscheme parametrizing ideals of codimension $n$ supported at the origin of the affine plane. Both ... More
Form Factors in $D_n^{(1)}$ Affine Toda Field TheoriesDec 12 1996May 02 1997We derive closed recursion equations for the symmetric polynomials occuring in the form factors of $D_n^{(1)}$ affine Toda field theories. These equations follow from kinematical- and bound state residue equations for the full form factor. We also discuss ... More
q-Deformed Relativistic Wave EquationsOct 15 1993Based on the representation theory of the $q$-deformed Lorentz and Poincar\'e symmeties $q$-deformed relativistic wave equation are constructed. The most important cases of the Dirac-, Proca-, Rarita-Schwinger- and Maxwell- equations are treated explicitly. ... More
Probing Pauli Blocking Factors in Quantum Pumps with Broken Time-Reversal SymmetryJun 21 2000A recently demonstrated quantum electron pump is discussed within the framework of photon-assisted tunneling. Due to lack of time-reversal symmetry, different results are obtained for the pump current depending on whether or not final-state Pauli blocking ... More
Maximal multihomogeneity of algebraic hypersurface singularitiesNov 08 2006From the degree zero part of logarithmic vector fields along an algebraic hypersurface singularity we indentify the maximal multihomogeneity of a defining equation in form of a maximal algebraic torus in the embedded automorphism group. We show that all ... More
An ultrafilter approach to Jin's TheoremAug 20 2009It is well known and not difficult to prove that if $C$ of integers has positive upper Banach density, the set of differences $C-C$ is syndetic, i.e. the length of gaps is uniformly bounded. More surprisingly, Renling Jin showed that whenever $A$ and ... More
Using ZDDs in the mapping of quantum circuitsJan 08 2019In quantum compilation, one step translates a technology-independent quantum circuit into a technology-dependent quantum circuit for a targeted device. Besides mapping quantum gates into the supported gate set, it is necessary to map pseudo qubits in ... More
Equivariant K-homology of Bianchi groups with non-trivial class groupJan 06 2013May 13 2013We compute the equivariant K-homology of the groups PSL_2 of imaginary quadratic integers with trivial and non-trivial class-group. This was done before only for cases of trivial class number. We rely on reduction theory in the form of the $\Gamma$-CW-complex ... More
Finite sets of $d$-planes in affine spaceMar 21 2008Oct 13 2008Let $A$ be a subvariety of affine space $\mathbb{A}^n$ whose irreducible components are $d$-dimensional linear or affine subspaces of $\mathbb{A}^n$. Denote by $D(A)\subset\mathbb{N}^n$ the set of exponents of standard monomials of $A$. We show that the ... More
Finite subsets of projective space, and their idealsNov 07 2007Nov 19 2007Let $\mathscr{A}$ be a finite set of closed rational points in projective space, let $\mathscr{I}$ be the vanishing ideal of $\mathscr{A}$, and let $\mathscr{D}(\mathscr{A})$ be the set of exponents of those monomials which do not occur as leading monomials ... More
Information bounds for inverse problems with application to deconvolution and Lévy modelsJul 24 2013May 06 2014If a functional in an inverse problem can be estimated with parametric rate, then the minimax rate gives no information about the ill-posedness of the problem. To have a more precise lower bound, we study semiparametric efficiency in the sense of H\'ajek-Le ... More
Monodromy of Hypersurface SingularitiesAug 21 2001Dec 01 2004We describe algorithmic methods for the Gauss-Manin connection of an isolated hypersurface singularity based on the microlocal structure of the Brieskorn lattice. They lead to algorithms for computing invariants like the monodromy, the spectrum, and the ... More
Rayleigh-Taylor instability for the two-phase Navier-Stokes equations with surface tension in cylindrical domainsMar 15 2017This article is concerned with the dynamic behaviour of two immiscible and incompressible fluids in a cylindrical domain, which are separated by a sharp interface. In case that the heavy fluid is situated on top of the light fluid, one expects that the ... More
Alternative modelling and inference methods for claim size distributionsFeb 08 2019The upper tail of a claim size distribution of a property line of business is frequently modelled by Pareto distribution. However, the upper tail does not need to be Pareto distributed, extraordinary shapes are possible. Here, the opportunities for the ... More
Correlations of Quantum Fields on Robertson-Walker SpacetimesNov 09 1995It is a well known fact that quantum fields on Minkowski spacetime are correlated for each pair of spacetime regions. In Robertson-Walker spacetimes there are spacelike separated regions with disjoint past horizons but the absence of correlations in that ... More
On the deformability of Heisenberg algebrasAug 24 1995Based on the vanishing of the second Hochschild cohomology group of the enveloping algebra of the Heisenberg algebra it is shown that differential algebras coming from quantum groups do not provide a non-trivial deformation of quantum mechanics. For the ... More
B-L-symmetric Baryogenesis with Leptonic QuintessenceDec 12 2006We discuss a toy model where baryogenesis and cosmic acceleration are driven by a leptonic quintessence field coupled to the standard model sector via a massive mediating scalar field. It does not require the introduction of B-L-violating interactions ... More
Freeness and multirestriction of hyperplane arrangementsMar 03 2010Feb 16 2012Generalizing a result of Yoshinaga in dimension 3, we show that a central hyperplane arrangement in 4-space is free exactly if its restriction with multiplicities to a fixed hyperplane of the arrangement is free and its reduced characteristic polynomial ... More
Gröbner strata in the Hilbert scheme of pointsJul 02 2009Jan 22 2011The present paper shall provide a framework for working with Gr\"obner bases over arbitrary rings $k$ with a prescribed finite standard set $\Delta$. We show that the functor associating to a $k$-algebra $B$ the set of all reduced Gr\"obner bases with ... More
Performance comparison between iSCSI and other hardware and software solutionsMay 30 2003We report on our investigations on some technologies that can be used to build disk servers and networks of disk servers using commodity hardware and software solutions. It focuses on the performance that can be achieved by these systems and gives measured ... More
Quantum Corrections in Quintessence ModelsJun 12 2006Sep 12 2006We investigate the impact of quantum fluctuations on a light rolling quintessence field from three different sources, namely, from a coupling to the standard model and dark matter, from its self-couplings and from its coupling to gravity. We derive bounds ... More
Sur la rigidité de polyèdres hyperboliques en dimension 3 : cas de volume fini, cas hyperidéal, cas fuchsienNov 18 2002A hyperbolic semi-ideal polyedron is a polyedron whose vertices lie inside the hyperbolic space $\mathbf{H}^{3}$ or at infinity. A hyperideal polyedron is, in the projective model, the intersection of $\mathbf{H}^{3}$ with a projective polyhedron whose ... More
Replica-deformation of the SU(2)-invariant Thirring model via solutions of the qKZ equationJul 17 1999The response of an integrable QFT under variation of the Unruh temperature has recently been shown to be computable from an S-matrix preserving (`replica') deformation of the form factor approach. We show that replica-deformed form factors of the SU(2)-invariant ... More
Polynomial Recursion Equations in Form Factors of ADE Toda Field TheoriesMay 20 1997It is shown that the problem of calculating form factors in ADE affine Toda field theories can be reduced to the nonperturbative recursive calculation of polynomials symmetric in each sort of variables. We determine these recursion equations explicitly ... More
Selfdual 2-form formulation of gravity and classification of energy-momentum tensorsApr 17 1995Dec 17 1996It is shown how the different irreducibility classes of the energy-momentum tensor allow for a Lagrangian formulation of the gravity-matter system using a selfdual 2-form as a basic variable. It is pointed out what kind of difficulties arise when attempting ... More
A determinant-like formula for the Kostka numbersJan 10 2005Sep 01 2005Young tableaux are ubiquitous in various branches of mathematics. There are two counting formulas for standard Young tableaux. The first involves a determinant and goes back to Frobenius and Young, and the second is the hook formula by Frame, Robinson ... More
A KMS-like state of Hadamard type on Robertson-Walker spacetimes and its time evolutionSep 09 1997In this work we define a new state on the Weyl algebra of the free massive scalar Klein-Gordon field on a Robertson-Walker spacetime and prove that it is a Hadamard state. The state is supposed to approximate a thermal equilibrium state on a Robertson-Walker ... More
Cyclic Cohomology and Higher Rank LatticesDec 01 2006Jun 18 2007We give a new proof of the absence of non-trivial idempotents in the group ring of torsion-free cocompact lattices in SL(n,C). It is based on the following procedure. We lift the class of the trace in the cyclic cohomology of the group ring to the crossed ... More
Relation ideals and the Buchberger--Möller algorithmNov 11 2004We construct a Gr\"obner Basis of the relation ideal of a polynomial, give an interpolation formula for the basis elements and explain the connection of the interpolation formula to the Buchberger--M\"oller algorithm. We present a situation in which the ... More
$L_p$-theory for a Cahn-Hilliard-Gurtin systemMar 20 2012In this paper we study a generalized Cahn-Hilliard equation which was proposed by Gurtin. We prove the existence and uniqueness of a local-in-time solution for a quasilinear version, that is, if the coefficients depend on the solution and its gradient. ... More
Vincia for Hadron CollidersMay 19 2016Nov 07 2016We present the first public implementation of antenna-based QCD initial- and final-state showers. The shower kernels are $2\to 3$ antenna functions, which capture not only the collinear dynamics but also the leading soft (coherent) singularities of QCD ... More
Tracking Users across the Web via TLS Session ResumptionOct 16 2018User tracking on the Internet can come in various forms, e.g., via cookies or by fingerprinting web browsers. A technique that got less attention so far is user tracking based on TLS and specifically based on the TLS session resumption mechanism. To the ... More
QUICker connection establishment with out-of-band validation tokensApr 12 2019QUIC is a secure transport protocol and aims to improve the performance of HTTPS traffic. It is a design goal of QUIC to reduce the delay overhead of its connection establishment. However, an initial handshake enforcing strict validation of the client's ... More
Enhanced Performance for the encrypted Web through TLS Resumption across HostnamesFeb 07 2019TLS can resume previous connections via abbreviated resumption handshakes that significantly decrease the delay and save expensive cryptographic operations. For that, cryptographic TLS state from previous connections is reused. TLS version 1.3 recommends ... More
Model-Based Development of Distributed Embedded Systems by the Example of the Scicos/SynDEx FrameworkOct 19 2010The embedded systems engineering industry faces increasing demands for more functionality, rapidly evolving components, and shrinking schedules. Abilities to quickly adapt to changes, develop products with safe design, minimize project costs, and deliver ... More
Photonics Explorer - An European program to foster science education with hands-on experimentsMay 04 2012The Photonics Explorer program aims to equip science teachers at Europe's secondary schools free-of-charge with up-to-date educational material to really engage, excite and educate students about the fascination of working with light.
Absence of the Mott transition in infinite dimensionsMar 16 1999Mar 17 1999It is shown that the half filled Hubbard model does not display the Mott metal-insulator transition, in the limit of infinite dimensions. The proposed transition on the Bethe lattice is proved to be an artifact. In the atomic limit, the model is always ... More
The Zetafast algorithm for computing zeta functionsMar 04 2017Jun 08 2017We express the Riemann zeta function $\zeta\left(s\right)$ of argument $s=\sigma+i\tau$ with imaginary part $\tau$ in terms of three absolutely convergent series. The resulting simple algorithm allows to compute, to arbitrary precision, $\zeta\left(s\right)$ ... More
Diagrammatic method for investigating universal behavior of impurity systemsJul 09 1998The universal behavior of magnetic impurities in a metal is proved with the help of skeleton diagrams. The energy scales are derived from the structure of the skeleton diagrams. A minimal set of skeleton diagrams is sorted out that scales exactly. For ... More
Search for neutrinoless double-beta decay with SNO+Sep 17 2018The SNO+ experiment, located in SNOLAB, 2 kilometers underground in the Creighton mine, near Sudbury, Canada, is a large scale neutrino detector whose main purpose is to search for neutrinoless double-beta decay and thus probe the Majorana nature of the ... More
Generalized linear statistics for near epoch dependent processes with application to EGARCH-processesMay 12 2017The class of Generalized $L$-statistics ($GL$-statistics) unifies a broad class of different estimators, for example scale estimators based on multivariate kernels. $GL$-statistics are functionals of $U$-quantiles and therefore the dimension of the kernel ... More
Sequences of labeled trees related to Gelfand-Tsetlin patternsApr 04 2011By rewriting the famous hook-content formula it easily follows that there are $\prod\limits_{1 \le i < j \le n} \frac{k_j - k_i + j -i}{j-i}$ semistandard tableaux of shape $(k_n,k_{n-1},...,k_1)$ with entries in $\{1,2,...,n\}$ or, equivalently, Gelfand-Tsetlin ... More
Refined enumerations of alternating sign matrices: monotone (d,m)-trapezoids with prescribed top and bottom rowJul 02 2009Monotone triangles are plane integer arrays of triangular shape with certain monotonicity conditions along rows and diagonals. Their significance is mainly due to the fact that they correspond to $n \times n$ alternating sign matrices when prescribing ... More
Minimal elements of stopping time $σ$-algebrasDec 12 2011Jun 19 2012We show how minimal elements of a stopping time $\sigma$-algebra can be expressed in terms of the minimal elements of the $\sigma$-algebra of the underlying filtration. This facilitates an intuitive interpretation of stopping time $\sigma$-algebras. An ... More
Stopping times are hitting times: a natural representationDec 07 2011Jun 19 2012There exists a simple, didactically useful one-to-one relationship between stopping times and adapted c\`agl\`ad (LCRL) processes that are non-increasing and take the values 0 and 1 only. As a consequence, stopping times are always hitting times.
The beta function of the multichannel Kondo modelNov 17 1998The beta function of the multichannel Kondo model is calculated exactly in the limit of large spin N and channel number M=gamma*N, with constant gamma. There are no corrections in any finite order of 1/N. One zero is found at a finite coupling strength, ... More
A primer on reflexivity and price dynamics under systemic riskJan 27 2013A simple quantitative example of a reflexive feedback process and the resulting price dynamics after an exogenous price shock to a financial network is presented. Furthermore, an outline of a theory that connects financial reflexivity, which stems from ... More
No-arbitrage pricing under cross-ownershipMay 05 2010We generalize Merton's asset valuation approach to systems of multiple financial firms where cross-ownership of equities and liabilities is present. The liabilities, which may include debts and derivatives, can be of differing seniority. We derive equations ... More
Clues on the Majorana scale from scalar resonances at the LHCJul 01 2016In order to address the observation of the neutrino oscillations and the metastability of the Standard Model, we extend the fermion sector with two right-handed (i.e. sterile) neutrinos, and the scalar sector of the SM with a real scalar, the Hill field. ... More
The number of monotone triangles with prescribed bottom rowJan 07 2005We show that the number of monotone triangles with prescribed bottom row (k_1,...,k_n) is given by a simple product formula which remarkably involves (shift) operators. Monotone triangles with bottom row (1,2,...,n) are in bijection with $n \times n$ ... More
The Heisenberg OscillatorAug 16 2011Jun 14 2012In this short note, we determine the spectrum of the Heisenberg oscillator which is the operator defined as $L + |z|^2$ on the 3-dimensional Heisenberg group $H_1=\mathbb C \times \mathbb R$ where $L$ stands for the positive sublaplacian and $z$ for the ... More
High-order behaviour and summation methods in perturbative QCDDec 11 1995After reviewing basic facts about large-order behaviour of perturbation expansions in various fields of physics, I consider several alternatives to the Borel summation method and discuss their relevance to different physical situations. Then I convey ... More
Unicity Concepts for SudokuOct 02 2014This paper deals with a generalized Sudoku problem and investigates the unicity of a given solution. We introduce constraint sets, which is a generalization of the rows, columns and blocks of a classical Sudoku puzzle. The unicity property is characterized ... More
On the uniqueness of the maximum parsimony tree for data with up to two substitutions: an extension of the classic Buneman theorem in phylogeneticsAug 21 2018Mar 21 2019One of the main aims of phylogenetics is the reconstruction of the correct evolutionary tree when data concerning the underlying species set are given. These data typically come in the form of DNA, RNA or protein alignments, which consist of various characters ... More
On the form of the large deviation rate function for the empirical measures of weakly interacting systemsAug 02 2012Oct 16 2014A basic result of large deviations theory is Sanov's theorem, which states that the sequence of empirical measures of independent and identically distributed samples satisfies the large deviation principle with rate function given by relative entropy ... More
Intrinsic pseudodifferential calculi on any compact Lie groupSep 27 2014Mar 16 2015In this paper, we define in an intrinsic way operators on a compact Lie group by means of symbols using the representations of the group. The main purpose is to show that these operators form a symbolic pseudo-differential calculus which coincides or ... More
A Necessary Solution Condition for SudokuOct 23 2012We develop a new discrete mathematical model which includes the classical Sudoku puzzle, Latin Squares and gerechte designs. This problem is described by integer equations and a special type of inequality constraint. We consider solutions of this generalized ... More
Differential structure on the dual of a compact lie groupOct 20 2016Jun 11 2018In this paper we define difference operators and homogeneous Sobolev-type spaces on the dual of a compact Lie group. As an application and to show that this defines a relevant differential structure, we state and prove multiplier theorems of H\"ormander, ... More
Wee LCPOct 16 2009Feb 19 2010We prove that longest common prefix (LCP) information can be stored in much less space than previously known. More precisely, we show that in the presence of the text and the suffix array, o(n) additional bits are sufficient to answer LCP-queries asymptotically ... More
The true colours of white light: hands-on optical spectrometryApr 26 2012Although the observation of optical spectra is common practice in physics classes, students are usually limited to a passive, qualitative observation of nice colours. This article discusses a diffraction-based spectrometer that allows students to take ... More
Linear relations of refined enumerations of alternating sign matricesAug 03 2010In recent papers we have studied refined enumerations of alternating sign matrices with respect to a fixed set of top and bottom rows. The present paper is a first step towards extending these considerations to alternating sign matrices where in addition ... More
A new proof of the refined alternating sign matrix theoremJul 13 2005In the early 1980s, Mills, Robbins and Rumsey conjectured, and in 1996 Zeilberger proved a simple product formula for the number of $n \times n$ alternating sign matrices with a 1 at the top of the $i$-th column. We give an alternative proof of this formula ... More
Another refinement of the Bender-Knuth (ex-)ConjectureJan 19 2004We compute the generating function of column-strict plane partitions with parts in {1,2,...,n}, at most c columns, p rows of odd length and k parts equal to n. This refines both, Krattenthaler's ["The major counting of nonintersecting lattice paths and ... More
A method for proving polynomial enumeration formulasJan 10 2003Sep 17 2003We present an elementary method for proving enumeration formulas which are polynomials in certain parameters if others are fixed and factorize into distinct linear factors over Z. Roughly speaking the idea is to prove such formulas by ``explaining'' their ... More
A symmetry theorem on a modified jeu de taquinDec 23 2001For their bijective proof of the hook-length formula for the number of standard tableaux of a fixed shape Novelli, Pak and Stoyanovskii define a modified jeu de taquin which transforms an arbitrary filling of the Ferrers diagram with $1,2,...,n$ (tabloid) ... More
Moments of inertia associated with the lozenge tilings of a hexagonDec 15 2000Consider the probability that an arbitrary chosen lozenge tiling of the hexagon with side lengths a, b, c, a, b, c contains the horizontal lozenge with lowest vertex (x,y) as if it described the distribution of mass in the plane. We compute the horizontal ... More
Role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung - Impact on the protoneutron star deleptonizationAug 17 2016Aug 23 2016In this article the neutrino-pair production from nucleon-nucleon (NN) bremsstrahlung is explored via medium-modifications of the strong interactions at the level of the one-pion exchange approximation. It governs the bulk part of the NN interaction at ... More
Equilibria in Quitting Games - BasicsJan 12 2011Quitting games are one of the simplest stochastic games in which at any stage each player has only two possible actions, continue and quit. The game ends as soon as at least one player chooses to quit. The players then receive a payoff, which depends ... More
Local and global symbols on compact Lie groupsNov 08 2017Oct 03 2018On the torus, it is possible to assign a global symbol to a pseudodifferential operator using Fourier series. In this paper we investigate the relations between the local and global symbols for the operators in the classical H\"ormander calculus and describe ... More
Real trace expansionsOct 03 2018In this paper, we show that the trace of the operators $A\eta(t\mathcal{L})$ where $A$ and $\mathcal {L}$ are classical pseudo-differential operators on a compact manifold $M$ and $\mathcal {L}$ is elliptic and self-adjoint admits an expansion in powers ... More
Weak-strong uniqueness of solutions to entropy-dissipating reaction-diffusion equationsMar 02 2017We establish a weak-strong uniqueness principle for solutions to entropy-dissipating reaction-diffusion equations: As long as a strong solution to the reaction-diffusion equation exists, any weak solution and even any renormalized solution must coincide ... More
Some New Bounds on the Entropy Numbers of Diagonal OperatorsMar 01 2019Entropy numbers are an important tool for quantifying the compactness of operators. Besides establishing new upper bounds on the entropy numbers of diagonal operators $D_\sigma$ from $\ell_p$ to $\ell_q$, where $p\not=q$, we investigate the optimality ... More
Robust graphical modeling of gene networks using classical and alternative T-distributionsSep 19 2010Aug 09 2011Graphical Gaussian models have proven to be useful tools for exploring network structures based on multivariate data. Applications to studies of gene expression have generated substantial interest in these models, and resulting recent progress includes ... More
Mesoscopic fluctuations in the spin-electric susceptibility due to Rashba spin-orbit interactionMay 27 2008We investigate mesoscopic fluctuations in the spin polarization generated by a static electric field and by Rashba spin-orbit interaction in a disordered 2D electron gas. In a diagrammatic approach we find that the out-of-plane polarization -- while being ... More
Note on bipartite graph tilingsJun 06 2008Jan 11 2010Let s<t be two fixed positive integers. We study what are the minimum degree conditions for a bipartite graph G, with both color classes of size n=k(s+t), which ensure that G has a K_{s,t}-factor. Exact result for large n is given. Our result extends ... More
Localization by bichromatic potentials versus Anderson localizationMay 14 2009Jul 07 2009The one-dimensional propagation of waves in a bichromatic potential may be modeled by the Aubry-Andr\'e Hamiltonian. The latter presents a delocalization-localization transition, which has been observed in recent experiments using ultracold atoms or light. ... More
Fractional White Noise Perturbations of Parabolic Volterra EquationsJul 12 2010Aim of this work is to extend the results of Cl\'ement, Da Prato & Pr\"uss on the fractional white noise perturbation with Hurst parameter 0<H<1. We will obtain similar results and it will turn out that the regularity of the solution u(t) of the stochastic ... More
Maximal regularity and global existence of solutions to a quasilinear thermoelastic plate systemNov 14 2012We consider a quasilinear PDE system which models nonlinear vibrations of a thermoelastic plate defined on a bounded domain in R^n. Well-posedness of solutions reconstructing maximal parabolic regularity in nonlinear thermoelastic plates is established. ... More
Exact and non-stiff sampling of highly oscillatory systems: an implicit mass-matrix penalization approachMay 08 2008Nov 04 2008We propose and analyze an implicit mass-matrix penalization (IMMP) technique which enables efficient and exact sampling of the (Boltzmann/Gibbs) canonical distribution associated to Hamiltonian systems with fast degrees of freedom (fDOFs). The penalty ... More
Complexes, duality and Chern classes of logarithmic forms along hyperplane arrangementsApr 23 2010We describe dualities and complexes of logarithmic forms and differentials for central affine and corresponding projective arrangements. We generalize the Borel-Serre formula from vector bundles to sheaves on projective d-space with locally free resolutions ... More
Thermalization of quantum systems by finite bathsNov 03 2005We consider a discrete quantum system coupled to a finite bath, which may consist of only one particle, in contrast to the standard baths which usually consist of continua of oscillators, spins, etc. We find that such finite baths may nevertheless equilibrate ... More
From Pure Schroedingerian to Statistical DynamicsAug 26 2005Many processes in nature seem to be entirely controlled by transition rates and the corresponding statistical dynamics. Some of them are in essence quantum, like the decay of excited states, the tunneling through barriers or the decay of unstable nuclei. ... More
Mechanical limits of viral capsidsMar 14 2007We study the elastic properties and mechanical stability of viral capsids under external force-loading with computer simulations. Our approach allows the implementation of specific geometries corresponding to specific phages such as $\phi$29 and CCMV. ... More
Probing photon helicity in radiative B decays via charmonium resonance interferenceSep 05 2005Mar 08 2006We investigate a new method to probe the helicity of the photon emitted in the b -> s gamma transition. The method relies on the observation of interference effects between two resonance contributions, B -> K*(K gamma) gamma and B -> eta_c(gamma gamma) ... More
Aggregating density estimators: an empirical studyJul 20 2012We present some new density estimation algorithms obtained by bootstrap aggregation like Bagging. Our algorithms are analyzed and empirically compared to other methods found in the statistical literature, like stacking and boosting for density estimation. ... More
Decaying vs Annihilating Dark Matter in Light of a Tentative Gamma-Ray LineJun 29 2012Jan 14 2014Recently reported tentative evidence for a gamma-ray line in the Fermi-LAT data is of great potential interest for identifying the nature of dark matter. We compare the implications for decaying and annihilating dark matter taking the constraints from ... More
ACGreGate: A Framework for Practical Access Control for Applications using Weakly Consistent DatabasesJan 22 2018Scalable and highly available systems often require data stores that offer weaker consistency guarantees than traditional relational databases systems. The correctness of these applications highly depends on the resilience of the application model against ... More
A residual duality over Gorenstein rings with application to logarithmic differential formsDec 23 2017Oct 19 2018Kyoji Saito's notion of a free divisor was generalized by the first author to reduced Gorenstein spaces and by Delphine Pol to reduced Cohen-Macaulay spaces. Starting point is the Aleksandrov-Terao theorem: A hypersurface is free if and only if its Jacobian ... More
Gravitational collapse in the Schrödinger-Poisson systemOct 13 2017Jan 23 2018We perform a quantitative comparison between N-body simulations and the Schr\"odinger-Poisson system in 1+1 dimensions. In particular, we study halo formation with different initial conditions. We observe the convergence of various observables in the ... More
Thermodynamics and Superradiant Phase Transitions in a three-level Dicke ModelOct 25 2016We analyse the thermodynamic properties of a generalised Dicke model, i.e. a collection of three-level systems interacting with two bosonic modes. We show that at finite temperatures the system undergoes first-order phase transitions only, which is in ... More
How to ask sensitive multiple choice questionsMar 28 2018Motivated by recent failures of polling to estimate populist party support, we propose and analyse two methods for asking sensitive multiple choice questions where the respondent retains some privacy and therefore might answer more truthfully. The first ... More