Results for "Niklas Georg"

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The Analytic Bethe Ansatz for a Chain with Centrally Extended su(2|2) SymmetryOct 09 2006Jan 02 2007We investigate the integrable structure of spin chain models with centrally extended su(2|2) and psu(2,2|4) symmetry. These chains have their origin in the planar AdS/CFT correspondence, but they also contain the one-dimensional Hubbard model as a special ... More
An SU(1|1)-Invariant S-Matrix with Dynamic RepresentationsNov 01 2005Nov 07 2005The spin chains originating from large-N conformal gauge theories are of a special kind: The Hamiltonian is not invariant under the symmetry algebra, it is rather a part of it. This leads to interesting properties within the asymptotic Bethe ansatz. Here ... More
Spin Chain for Quantum StringsSep 03 2004Sep 14 2004We review and compare the integrable structures in N=4 gauge theory and string theory on AdS5xS5. Recently, Bethe ansaetze for gauge theory/weak coupling and string theory/strong coupling were proposed to describe scaling dimensions in the su(2) subsector. ... More
The su(2|2) Dynamic S-MatrixNov 07 2005Sep 19 2006We derive and investigate the S-matrix for the su(2|3) dynamic spin chain and for planar N=4 super Yang-Mills. Due to the large amount of residual symmetry in the excitation picture, the S-matrix turns out to be fully constrained up to an overall phase. ... More
Electricity Theft Detection using Machine LearningAug 19 2017Non-technical losses (NTL) in electric power grids arise through electricity theft, broken electric meters or billing errors. They can harm the power supplier as well as the whole economy of a country through losses of up to 40% of the total power distribution. ... More
On Yangian Symmetry in Planar N=4 SYMApr 30 2010Apr 10 2011Planar N=4 supersymmetric Yang-Mills theory appears to be perturbatively integrable. This work reviews integrability in terms of a Yangian algebra and compares the application to the problems of anomalous dimensions and scattering amplitudes.
Designing Sound Collaboratively - Perceptually Motivated Audio SynthesisJun 23 2014In this contribution, we will discuss a prototype that allows a group of users to design sound collaboratively in real time using a multi-touch tabletop. We make use of a machine learning method to generate a mapping from perceptual audio features to ... More
Hadronic Production of Gamma Rays and Starburst GalaxiesOct 01 2008The Milky Way has been estabished to emit gamma rays. These gamma rays are presumably dominated by decays of neutral pions, although inverse Compton scatterings and bremsstrahlung also contribute. It is plausible that other galaxies can be diffuse sources ... More
The su(2|3) Undynamic Spin ChainJul 01 2008Apr 17 2009The integrable spin chain found in perturbative planar N=4 supersymmetric gauge theory is dynamic. Here we propose a reformulation which removes the dynamic effects in order to make the model more accessible to an algebraic treatment.
Higher-Loop Integrability in N=4 Gauge TheorySep 14 2004Oct 28 2004The dilatation operator measures scaling dimensions of local operator in a conformal field theory. Algebraic methods of constructing the dilatation operator in four-dimensional N=4 gauge theory are reviewed. These led to the discovery of novel integrable ... More
The Dilatation Operator of N=4 Super Yang-Mills Theory and IntegrabilityJul 30 2004Oct 22 2005The dilatation generator measures the scaling dimensions of local operators in a conformal field theory. In this thesis we consider the example of maximally supersymmetric gauge theory in four dimensions and develop and extend techniques to derive, investigate ... More
On the Scattering Phase for AdS_5 x S^5 StringsJun 22 2006Feb 05 2007We propose a phase factor of the worldsheet S-matrix for strings on AdS_5 x S^5 apparently solving Janik's crossing relation.
The su(2|3) Dynamic Spin ChainOct 28 2003Dec 09 2003The complete one-loop, planar dilatation operator of the N=4 superconformal gauge theory was recently derived and shown to be integrable. Here, we present further compelling evidence for a generalisation of this integrable structure to higher orders of ... More
The Complete One-Loop Dilatation Operator of N=4 Super Yang-Mills TheoryJul 01 2003Feb 27 2011We continue the analysis of hep-th/0303060 in the one-loop sector and present the complete psu(2,2|4) dilatation operator of N=4 Super Yang-Mills theory. This operator generates the matrix of one-loop anomalous dimensions for all local operators in the ... More
Uncertainty Quantification for Geometry Deformations of Superconducting Cavities using Eigenvalue TrackingFeb 08 2018The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities are sensitive to small geometry deformations. The occurring variations are motivated by measurements of an available set of resonators ... More
Push Forward: Global Fixed-Priority Scheduling of Arbitrary-Deadline Sporadic Task SystemsFeb 28 2018The sporadic task model is often used to analyze recurrent execution of identical tasks in real-time systems. A sporadic task defines an infinite sequence of task instances, also called jobs, that arrive under the minimum inter-arrival time constraint. ... More
Uncertainty Quantification for Maxwell's Eigenproblem based on Isogeometric Analysis and Mode TrackingFeb 08 2018Mar 06 2019The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities used in particle accelerators for example are sensitive to small geometry deformations. The occurring variations are motivated by measurements ... More
Uncertainty Quantification for Maxwell's Eigenproblem using Isogeometric AnalysisFeb 08 2018May 30 2018The electromagnetic field distribution as well as the resonating frequency of various modes in superconducting cavities used in particle accelerators for example are sensitive to small geometry deformations. The occurring variations are motivated by measurements ... More
Local spin-wave dispersion and damping in thin yttrium-iron-garnet filmsMar 13 2018Using ultrafast magneto-optic sampling microscopy, we investigate the spin-wave dispersion and spin-wave damping in yttrium-iron-garnet films. With the aid of the inhomogeneous magnetic field generated by coplanar waveguides spin-waves are excited at ... More
Uncertainty quantification for an optical grating coupler with an adjoint-based Leja adaptive collocation methodJul 19 2018This paper addresses uncertainties arising in the nano-scale fabrication of optical devices. The stochastic collocation method is used to propagate uncertainties in material and geometry to the scattering parameters of the system. A dimension-adaptive ... More
Coulomb Branches of Star-Shaped QuiversAug 15 2018Dec 07 2018We study the Coulomb branches of 3d N=4 `star-shaped' quiver gauge theories and their deformation quantizations, by applying algebraic techniques that have been developed in the mathematics and physics literature over the last few years. The algebraic ... More
Finite-frequency noise of interacting single-electron emitters: spectroscopy with higher noise harmonicsMay 08 2018We derive the symmetrized current-noise spectrum of a quantum dot, which is weakly tunnel-coupled to an electron reservoir and driven by a slow time-dependent gate voltage. This setup can be operated as an on-demand emitter of single electrons into a ... More
Searching for degeneracies of real Hamiltonians using homotopy classification of loops in SO($n$)Jun 15 2004Jan 25 2005Topological tests to detect degeneracies of Hamiltonians have been put forward in the past. Here, we address the applicability of a recently proposed test [Phys. Rev. Lett. {\bf 92}, 060406 (2004)] for degeneracies of real Hamiltonian matrices. This test ... More
A flexible multidimensional rectangular mesh administration and refinement technique with application in cancer invasion modelsJun 19 2017We present a mesh-structure data administration technique for the bookkeeping of adaptive mesh refinement, in particular h-refinement, of rectangular parallelepiped meshes. Our technique is a unified approach for 1-, 2- and 3D domains, that can be extended ... More
Universal Quantum Computing with Spin and ValleyMar 22 2012We investigate a two-electron double quantum dot with both spin and valley degrees of freedom as they occur in graphene, carbon nanotubes, or silicon, and regard the 16-dimensional space with one electron per dot as a four-qubit logic space. In the spin-only ... More
Scaling property of the critical hopping parameters for the Bose-Hubbard modelSep 17 2009Recently precise results for the boundary between the Mott insulator phase and the superfluid phase of the homogeneous Bose-Hubbard model have become available for arbitrary integer filling factor g and any lattice dimension d > 1. We use these data for ... More
Bose-Einstein condensates in a double well: mean-field chaos and multi-particle entanglementNov 07 2008A recent publication [Phys. Rev. Lett. 100, 140408 (2008)] shows that there is a relation between mean-field chaos and multi-particle entanglement for BECs in a periodically shaken double well. 'Schrodinger-cat' like mesoscopic superpositions in phase-space ... More
Instability in cosmological topologically massive gravity at the chiral pointMay 19 2008Oct 22 2009We consider cosmological topologically massive gravity at the chiral point with positive sign of the Einstein-Hilbert term. We demonstrate the presence of a negative energy bulk mode that grows linearly in time. Unless there are physical reasons to discard ... More
World-line formulation of chiral kinetic theory in topological background gauge fieldsDec 11 2017In heavy-ion collisions, an interesting question of phenomenological relevance is how the chiral imbalance generated at early times persists through a fluctuating background of sphalerons in addition to other "non-anomalous" interactions with the QGP. ... More
A Fault-Tolerant Sequentially Consistent DSM With a Compositional Correctness ProofAug 08 2016We present the SC-ABD algorithm that implements sequentially consistent distributed shared memory (DSM). The algorithm tolerates that less than half of the processes are faulty (crash-stop). Compared to the multi-writer ABD algorithm, SC-ABD requires ... More
Tomography scheme for two spin-1/2 qubits in a double quantum dotApr 10 2013We present a scheme for full quantum state tomography tailored for two spin qubits in a double quantum dot. A set of 15 quantum states allows to determine the density matrix in this two-qubit space by projective measurement. In this paper we choose a ... More
Constructing phase space distributions with internal symmetriesJan 29 2019Feb 22 2019We discuss an ab initio world-line approach to constructing phase space distributions in systems with internal symmetries. Starting from the Schwinger-Keldysh real time path integral in quantum field theory, we derive the most general extension of the ... More
Generation of mesoscopic superpositions of a binary Bose-Einstein condensate in a slightly asymmetric double wellJul 27 2007A previous publication [Europhysics Letters 78, 10009 (2007)] suggested to coherently generate mesoscopic superpositions of a two-component Bose-Einstein condensate in a double well under perfectly symmetric conditions. However, already tiny asymmetries ... More
Conformal regularization of Einstein's field equationsApr 14 2005Jul 15 2005To study asymptotic structures, we regularize Einstein's field equations by means of conformal transformations. The conformal factor is chosen so that it carries a dimensional scale that captures crucial asymptotic features. By choosing a conformal orthonormal ... More
Consistent boundary conditions for cosmological topologically massive gravity at the chiral pointAug 19 2008Oct 28 2010We show that cosmological topologically massive gravity at the chiral point allows not only Brown-Henneaux boundary conditions as consistent boundary conditions, but slightly more general ones which encompass the logarithmic primary found in 0805.2610 ... More
Parameterization of the Angular Distribution of Gamma Rays Produced by p-p Interaction in Astronomical EnvironmentSep 03 2007Dec 12 2007We present the angular distribution of gamma rays produced by proton-proton interactions in parameterized formulae to facilitate calculations in astrophysical environments. The parameterization is derived from Monte Carlo simulations of the up-to-date ... More
Springer MotivesDec 12 2018We show that the motive of a Springer fiber is pure Tate. We then consider a category of equivariant Springer motives on the nilpotent cone and construct an equivalence to the derived category of graded modules over the graded affine Hecke algebra.
Enhancing nanomechanical squeezing by atomic interactions in a hybrid atom-optomechanical systemNov 13 2018In a hybrid atom-optomechanical system, the optical coupling of a mechanical mode of a nanomembrane in an optical cavity with a distant interacting atom gas permits highly non-classical quantum many-body states. We show that the mechanical mode can be ... More
On linear representation of $\ast$-regular rings having representable ortholattice of projectionsNov 04 2018This paper aims at the following results: \begin{enumerate} \item The class of all $*$-regular rings forms a variety. \item A subdirectly irreducible $*$-regular ring $R$ is faithfully representable (i.e. isomorphic to a subring of an endomorphisms ring ... More
The boundary Harnack inequality for variable exponent $p$-Laplacian, Carleson estimates, barrier functions and $p(\cdot)$-harmonic measuresMay 12 2014We investigate various boundary decay estimates for $p(\cdot)$-harmonic functions. For domains in $\mathbb{R}^n, n\geq 2$ satisfying the ball condition ($C^{1,1}$-domains) we show the boundary Harnack inequality for $p(\cdot)$-harmonic functions under ... More
Comment on "Motion of a helical vortex filament in superfluid 4He under the extrinsic form of the local induction approximation"Oct 01 2013We comment on the paper by Van Gorder ["Motion of a helical vortex filament in superfluid ${}^4$He under the extrinsic form of the local induction approximation", Phys. Fluids 25, 085101 (2013)]. We point out that the flow of the normal fluid component ... More
Construction of Lax Connections by ExponentiationJul 13 2012We propose a method for constructing the Lax connection of two-dimensional relativistic integrable sigma models on coset spaces by means of exponentiation of a suitable operator. We derive a simple quadratic relation that this operator must satisfy for ... More
Yangian Algebra and Correlation Functions in Planar Gauge TheoriesApr 24 2018Jul 02 2018In this work we consider colour-ordered correlation functions of the fields in integrable planar gauge theories such as N=4 supersymmetric Yang-Mills theory with the aim to establish Ward-Takahashi identities corresponding to Yangian symmetries. To this ... More
Optimization of electron pumping by harmonic mixingDec 21 2010Mar 22 2011For a symmetric bridge coupled to infinite leads, in the presence of a dipole-coupled external ac-field with harmonic mixing, we solve the Schr\"odinger equation in the time-domain using open boundary conditions as well as in the energy-domain using Floquet ... More
Gravity duals for logarithmic conformal field theoriesDec 30 2009Mar 09 2010Logarithmic conformal field theories with vanishing central charge describe systems with quenched disorder, percolation or dilute self-avoiding polymers. In these theories the energy momentum tensor acquires a logarithmic partner. In this talk we address ... More
Long-Range PSU(2,2|4) Bethe Ansaetze for Gauge Theory and StringsApr 25 2005Sep 26 2005We generalize various existing higher-loop Bethe ansaetze for simple sectors of the integrable long-range dynamic spin chain describing planar N=4 Super Yang-Mills Theory to the full psu(2,2|4) symmetry and, asymptotically, to arbitrary loop order. We ... More
Optimal Topological Test for Degeneracies of Real HamiltoniansOct 03 2003Jan 09 2004We consider adiabatic transport of eigenstates of real Hamiltonians around loops in parameter space. It is demonstrated that loops that map to nontrivial loops in the space of eigenbases must encircle degeneracies. Examples from Jahn-Teller theory are ... More
Graded and Geometric Parabolic Induction for Category $\mathcal{O}$Mar 01 2016Sep 13 2018We prove that the parabolic induction functor on BGG-category $\mathcal{O}$ associated to a complex reductive Lie algebra is gradable, that is, lifts to graded category $\mathcal{O}$ as constructed by Beilinson-Ginzburg-Soergel. Graded category $\mathcal{O}$ ... More
Phragmén-Lindelöf theorems and p-harmonic measures for sets near low-dimensional hyperplanesMar 18 2015Dec 03 2015We prove estimates of a $p$-harmonic measure, $p \in (n-m, \infty]$, for sets in $\mathbf{R}^n$ which are close to an $m$-dimensional hyperplane $\Lambda \subset \mathbf{R}^n$, $m \in [0,n-1]$. Using these estimates, we derive results of Phragm\'en-Lindel\"of ... More
On Symmetry Enhancement in the psu(1,1|2) Sector of N=4 SYMJul 06 2007Sep 19 2007Strong evidence indicates that the spectrum of planar anomalous dimensions of N=4 super Yang-Mills theory is given asymptotically by Bethe equations. A curious observation is that the Bethe equations for the psu(1,1|2) subsector lead to very large degeneracies ... More
Mixed Motives and Geometric Representation Theory in Equal CharacteristicSep 19 2016Apr 12 2019Let $\mathbb{k}$ be a field of characteristic $p$. We introduce a formalism of mixed sheaves with coefficients in $\mathbb{k}$ and showcase its use in representation theory. More precisely, we construct for all quasi-projective schemes $X$ over an algebraic ... More
A simple and accurate approximation for the Q stability parameter in multi-component and realistically thick discsFeb 18 2013May 08 2013In this paper, we propose a Q stability parameter that is more realistic than those commonly used, and is easy to evaluate [see Eq. (19)]. Using our Q_N parameter, you can take into account several stellar and/or gaseous components as well as the stabilizing ... More
Magnetic catalysis and inverse magnetic catalysis in QCDFeb 27 2015May 13 2015We investigate the effects of strong magnetic fields on the QCD phase structure at vanishing density by solving the gluon and quark gap equations, and by studying the dynamics of the quark scattering with the four-fermi coupling. The chiral crossover ... More
Realization of Shor's Algorithm at Room TemperatureJun 10 2017Shor's algorithm can find prime factors of a large number more efficiently than any known classical algorithm. Understanding the properties that gives the speedup is essential for a general and scalable construction. Here we present a realization of Shor's ... More
Weyl Groups with Coxeter Presentation and Presentation by ConjugationJul 22 2006We investigate which Weyl groups have a Coxeter presentation and which of them at least have the presentation by conjugation with respect to their root system. For most concepts of root systems the Weyl group has both. In the context of extended affine ... More
On reduced stable pair invariantsMay 16 2016Let $X = S \times E$ be the product of a K3 surface $S$ and an elliptic curve $E$. Reduced stable pair invariants of $X$ can be defined via (1) cutting down the reduced virtual class with incidence conditions or (2) the Behrend function weighted Euler ... More
A Serre derivative for even weight Jacobi FormsSep 25 2012Jun 11 2014Using deformed or twisted Eisenstein Series, we construct a Jacobi-Serre derivative on even-weight Jacobi forms that generalizes the classical Serre derivative on modular forms. As an application, we obtain Ramanujan equations for the index $1$ Eisenstein ... More
Duality Construction of Moduli SpacesAug 29 1997We show for the moduli space of rank-2 coherent sheaves on an algebraic surface that there exists a 'dual' moduli space. This dual space allows a construction of the first one without using the GIT construction. Furthermore, we obtain a Barth-morphism, ... More
On Newton-Okounkov bodies of Graded Linear SeriesJan 14 2018We generalize the theory of Newton-Okounkov bodies of big divisors to the case of graded linear series. One of the results is the generalization of slice formulas and the existence of generic Newton-Okounkov bodies for birational graded linear series. ... More
Generalized Albanese morphismsApr 04 2003Sep 27 2004We define generalizations of the Albanese variety for a projective variety X. The generalized Albanese morphisms X --> Alb_r(X) contract those curves C in X for which the induced morphism Hom(\pi_1(X),U(r)) --> Hom(\pi_1(C),U(r)) has a finite image. Thus, ... More
Accelerated Portfolio Optimization with Conditional Value-at-Risk Constraints using a Cutting-Plane MethodAug 12 2014Financial portfolios are often optimized for maximum profit while subject to a constraint formulated in terms of the Conditional Value-at-Risk (CVaR). This amounts to solving a linear problem. However, in its original formulation this linear problem has ... More
Fixed Point Theorem for Non-Self Maps of Regions in the PlaneDec 15 2011May 03 2013Let X and Y be compact, simply connected and locally connected subsets of R^2, and let f : X -> Y be a homeomorphism isotopic to the identity on X. Generalizing Brouwer's plane translation theorem for self-maps of the plane, we prove that f has no recurrent ... More
Explicit thermostatics of certain classical one-dimensional lattice models by harmonic analysisMar 28 1994A certain class of one-dimensional classical lattice models is considered. Using the method of abstract harmonic analysis explicit thermostatic properties of such models are derived. In particular, we discuss the low-temperature behavior of some of these ... More
Exchange currents in radiative hyperon decays and hyperon charge radiiOct 06 1998Radiative decays of decuplet hyperons and octet hyperon charge radii are evaluated in a chiral constituent quark model emphasizing the role of exchange currents. Exchange currents largely cancel for the M1 decay amplitudes, while they dominate the E2 ... More
An extension theorem for hermitian line bundlesJul 22 2015May 11 2016We prove a general extension theorem for holomorphic line bundles on reduced complex spaces, equipped with singular hermitian metrics, whose curvature currents can be extended as positive, closed currents. The result has applications to various moduli ... More
Complex-Valued Random Vectors and Channels: Entropy, Divergence, and CapacityMay 04 2011Recent research has demonstrated significant achievable performance gains by exploiting circularity/non-circularity or propeness/improperness of complex-valued signals. In this paper, we investigate the influence of these properties on important information ... More
Silent Transitions in Automata with StorageFeb 15 2013We consider the computational power of silent transitions in one-way automata with storage. Specifically, we ask which storage mechanisms admit a transformation of a given automaton into one that accepts the same language and reads at least one input ... More
On the capabilities of grammars, automata, and transducers controlled by monoidsMar 17 2011During the last decades, classical models in language theory have been extended by control mechanisms defined by monoids. We study which monoids cause the extensions of context-free grammars, finite automata, or finite state transducers to exceed the ... More
Compactifications of the Drinfeld half space over a Finite FieldApr 18 2018When considered as a Deligne-Lusztig variety, the Drinfeld half space $\Omega_V$ over a finite field $k$ has a compactification whose boundary divisor is normal crossing and which can be obtained by successively blowing-up projective space along linear ... More
A Brascamp-Lieb type covariance estimateFeb 20 2014In this article, we derive a new covariance estimate. The estimate has a similar structure as the Brascamp-Lieb inequality and is optimal for ferromagnetic Gaussian measures. It can be naturally applied to deduce decay of correlations of lattice systems ... More
Arithmetics with multiple testing proceduresJul 14 2016Statistical discoveries are often obtained through multiple hypothesis testing. A variety of procedures exists to evaluate multiple hypotheses, for instance the ones of Benjamini-Hochberg, Bonferroni, Holm or Sidak. We are particularly interested in multiple ... More
Importance sampling for the simulation of reinsurance lossesMar 30 2013Importance sampling is a well developed method in statistics. Given a random variable $X$, the problem of estimating its expected value $\mu$ is addressed. The standard approach is to use the sample mean as an estimator $\bar x$. In importance sampling, ... More
Deciding Monotone Duality and Identifying Frequent Itemsets in Quadratic LogspaceDec 09 2012Aug 22 2013The monotone duality problem is defined as follows: Given two monotone formulas f and g in iredundant DNF, decide whether f and g are dual. This problem is the same as duality testing for hypergraphs, that is, checking whether a hypergraph H consists ... More
AXIONS IN ASTROPHYSICS AND COSMOLOGYFeb 21 1995Mar 23 1995If axions exist they are efficiently produced in the hot and dense interior of stars, providing a novel energy-loss mechanism. In order to avoid a conflict with the observed properties of stars, one can derive a lower limit on the Peccei-Quinn scale (an ... More
Abstract tropical linear programmingDec 06 2016Analogously to classical oriented matroid programming, we give the first feasibility algorithm for signed tropical oriented matroids, which encode the structure of tropical linear inequality systems. The feasibility problem for tropical linear inequality ... More
On Minimal Constraint NetworksMar 08 2011Jul 25 2012In a minimal binary constraint network, every tuple of a constraint relation can be extended to a solution. The tractability or intractability of computing a solution to such a minimal network was a long standing open question. Dechter conjectured this ... More
Karoubi's relative Chern character, the rigid syntomic regulator, and the Bloch-Kato exponential mapNov 17 2011Jul 21 2014We construct a variant of Karoubi's relative Chern character for smooth, separated schemes over the ring of integers in a p-adic field and prove a comparison with the rigid syntomic regulator. For smooth projective schemes we further relate the relative ... More
L-stable functorsApr 19 2007We generalize and greatly simplify the approach of Lydakis and Dundas-R\"ondigs-{\O}stv{\ae}r to construct an L-stable model structure for small functors from a closed symmetric monoidal model category V to a V-model category M, where L is a small cofibrant ... More
Positivity of relative canonical bundles for families of canonically polarized manifoldsAug 25 2008Oct 19 2010Given an effectively parameterized family of canonically polarized manifolds the Kaehler-Einstein metrics on the fibers induce a hermitian metric on the relative canonical bundle. We use a global elliptic equation to show that this metric is strictly ... More
Exchange Currents in Radiative Hyperon DecaysJun 15 1998A short overview of motivations and successes of two-body exchange currents between constituent quarks for electromagnetic hadron observables like charge radii, magnetic and quadrupole moments is given. We then predict and analyze exchange current effects ... More
Climate Modelling of Mass-Extinction Events: A ReviewJun 18 2009Despite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including ... More
On the Throughput/Bit-Cost Tradeoff in CSMA Based Cooperative NetworksJun 05 2009Nov 04 2009Wireless local area networks (WLAN) still suffer from a severe performance discrepancy between different users in the uplink. This is because of the spatially varying channel conditions provided by the wireless medium. Cooperative medium access control ... More
Particle production sources at LHC energiesJan 09 2013Feb 18 2013Particle production sources at RHIC and LHC energies are investigated in pseudorapidity space. A nonequilibrium-statistical relativistic diffusion model (RDM) with three sources is applied to the analysis of charged-hadron distributions in AuAu collisions ... More
Optimal Non-Uniform Mapping for Probabilistic ShapingAug 06 2012Jul 07 2014The construction of optimal non-uniform mappings for discrete input memoryless channels (DIMCs) is investigated. An efficient algorithm to find optimal mappings is proposed and the rate by which a target distribution is approached is investigated. The ... More
On the Relation between Solar Activity and Clear-Sky Terrestrial IrradianceSep 04 2012Oct 09 2012The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958-2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance ... More
Limits on a CP-violating scalar axion-nucleon interactionMay 08 2012Jul 29 2012Axions or similar hypothetical pseudoscalar bosons may have a small CP-violating scalar Yukawa interaction g_s(N) with nucleons, causing macroscopic monopole-dipole forces. Torsion-balance experiments constrain g_p(e) g_s(N), whereas g_p(N) g_s(N) is ... More
Neutrinos and the starsJan 08 2012May 19 2012The role of neutrinos in stars is introduced for students with little prior astrophysical exposure. We begin with neutrinos as an energy-loss channel in ordinary stars and conversely, how stars provide information on neutrinos and possible other low-mass ... More
CP violation in $B^0_s$ mixing with LHCbDec 05 2011The determination of the CP-violating phase $\phi_s$ in $B^0_s \rightarrow J/\psi \phi$ decays is one of the key goals of the LHCb experiment. Its value is predicted to be very small in the Standard Model but can be significantly enhanced in many models ... More
Supersymmetry on the lattice and the status of the Super-Yang-Mills simulationsNov 03 2010Supersymmetry (SUSY) and supersymmetric field theories are an interesting topic for numerical lattice simulations. Similar to the chiral symmetry there is also no local realization of (interacting) supersymmetry on the lattice. I briefly review the basic ... More
Gromov-Witten theory of K3 x P1 and quasi-Jacobi formsMay 17 2016Let $S$ be a K3 surface with primitive curve class $\beta$. We completely solve the relative Gromov-Witten theory of $S \times \mathbb{P}^1$ in classes $(\beta,1)$ and $(\beta,2)$. The generating series are quasi-Jacobi forms and equal to a corresponding ... More
The complexity of downward closure comparisonsMay 10 2016The downward closure of a language is the set of all (not necessarily contiguous) subwords of its members. It is well-known that the downward closure of every language is regular. Moreover, recent results show that downward closures are computable for ... More
Gromov-Witten theory of $\mathrm{K3} \times \mathbb{P}^1$ and quasi-Jacobi formsMay 17 2016Oct 12 2017Let $S$ be a K3 surface with primitive curve class $\beta$. We solve the relative Gromov-Witten theory of $S \times \mathbb{P}^1$ in classes $(\beta,1)$ and $(\beta,2)$. The generating series are quasi-Jacobi forms and equal to a corresponding series ... More
On reduced stable pair invariantsMay 16 2016Sep 23 2017Let $X = S \times E$ be the product of a K3 surface $S$ and an elliptic curve $E$. Reduced stable pair invariants of $X$ can be defined via (1) cutting down the reduced virtual class with incidence conditions or (2) the Behrend function weighted Euler ... More
Ultraviolet energy dependence of particle production sources in relativistic heavy-ion collisionsJan 13 2015The energy dependence of particle production sources in relativistic heavy-ion collisions is investigated from RHIC to LHC energies. Whereas charged-hadron production in the fragmentation sources follows a ln(s_NN/s_0) law, particle production in the ... More
An extension theorem for hermitian line bundlesJul 22 2015Mar 30 2017We prove a general extension theorem for holomorphic line bundles on reduced complex spaces, equipped with singular hermitian metrics, whose curvature currents can be extended as positive, closed currents. The result has applications to various moduli ... More
An approach to computing downward closuresMar 03 2015Jun 01 2015The downward closure of a word language is the set of all (not necessarily contiguous) subwords of its members. It is well-known that the downward closure of any language is regular. While the downward closure appears to be a powerful abstraction, algorithms ... More
Kinematic interpretation of the Study quadric's ambient spaceJul 31 2017It is well known that real points of the Study quadric (sliced along a 3-dimensional generator space) correspond to displacements of the Euclidean 3-space. But we still lack of a kinematic meaning for the points of the ambient 7-dimensional projective ... More
EXPODE -- Advanced Exponential Time Integration Toolbox for MATLABApr 17 2014We present a MATLAB toolbox for five different classes of exponential integrators for solving (mildly) stiff ordinary differential equations or time-dependent partial differential equations. For the efficiency of such exponential integrators it is essential ... More
Probabilistic Signal Shaping for Bit-Metric DecodingJan 23 2014Apr 20 2014A scheme is proposed that combines probabilistic signal shaping with bit-metric decoding. The transmitter generates symbols according to a distribution on the channel input alphabet. The symbols are labeled by bit strings. At the receiver, the channel ... More
Fitting and Analysis Technique for Inconsistent Nuclear DataMar 02 2018Consistent experiment data are crucial to adjust parameters of physics models and to determine best estimates of observables. However, often experiment data are not consistent due to unrecognized systematic errors. Standard methods of statistics such ... More