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Results for "Christian Mai"

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A Qualitative Post-Experience Method for Evaluating Changes in VR Presence Experience Over TimeMay 14 2019A particular measure to evaluate a head-mounted display (HMD) based experience is the state of feeling present in virtual reality. Interruptions of a presence experience - break in presence (BIP) - appearing over time, need to be detected to assess and ... More
The Capacity of MIMO Channels with Per-Antenna Power ConstraintJun 24 2011We establish the optimal input signaling and the capacity of MIMO channels under per-antenna power constraint. While admitting a linear eigenbeam structure, the optimal input is no longer diagonalizable by the channel right singular vectors as with sum ... More
Entropic convergence and the linearized limit for the Boltzmann equation with external forceDec 15 2016The purpose of this note, as a compendium, is to extend the results on entropic convergence and the linearized limit for the Boltzmann equation (without external force) in \cite{Levermore} by Levermore to the case of the Boltzmann equation with external ... More
Frontal Screens on Head-Mounted Displays to Increase Awareness of the HMD Users' State in Mixed Presence CollaborationMay 15 2019In the everyday context, e.g., a household, HMD users remain a part of the social life for Non-HMD users being co-located with them. Due to the social context situations arise that demand interaction between the HMD and the Non-HMD user. We focus on the ... More
Forward-reverse EM algorithm for Markov chains: convergence and numerical analysisJan 28 2015We develop a forward-reverse EM (FREM) algorithm for estimating parameters that determine the dynamics of a discrete time Markov chain evolving through a certain measurable state space. As a key tool for the construction of the FREM method we develop ... More
Tropical Gaussians: A Brief SurveyAug 31 2018We survey ways to define the analogue of the Gaussian measure in the tropical semiring.
Combined Decode-Forward and Layered Noisy Network Coding Schemes for Relay ChannelsMay 20 2012We propose two coding schemes combining decode-forward (DF) and noisy network coding (NNC) with different flavors. The first is a combined DF-NNC scheme for the one-way relay channel which includes both DF and NNC as special cases by performing rate splitting, ... More
Iterative Mode-Dropping for the Sum Capacity of MIMO-MAC with Per-Antenna Power ConstraintFeb 02 2012We propose an iterative mode-dropping algorithm that optimizes input signals to achieve the sum capacity of the MIMO-MAC with per-antenna power constraint. The algorithm successively optimizes each user's input covariance matrix by applying mode-dropping ... More
Decode-forward and Compute-forward Coding Schemes for the Two-Way Relay ChannelAug 17 2011We consider the full-duplex two-way relay channel with direct link between two users and propose two coding schemes: a partial decode-forward scheme, and a combined decode-forward and compute-forward scheme. Both schemes use rate-splitting and superposition ... More
GAdaBoost: Accelerating Adaboost Feature Selection with Genetic AlgorithmsSep 20 2016Boosted cascade of simple features, by Viola and Jones, is one of the most famous object detection frameworks. However, it suffers from a lengthy training process. This is due to the vast features space and the exhaustive search nature of Adaboost. In ... More
Adaptive optimal kernel density estimation for directional dataAug 07 2018We focus on the nonparametric density estimation problem with directional data. We propose a new rule for bandwidth selection for kernel density estimation. Our procedure is automatic, fully data-driven and adaptive to the smoothness degree of the density. ... More
The Finite Matroid-Based Valuation Conjecture is FalseMay 06 2019The matroid-based valuation conjecture of Ostrovsky and Paes Leme states that all gross substitutes valuations on $n$ items can be produced from merging and endowments of weighted ranks of matroids defined on at most $m(n)$ items. We show that if $m(n) ... More
Statistical minimax approach of the Hausdorff moment problemMay 09 2007Apr 23 2009The purpose of this paper is to study the problem of estimating a compactly supported density of probability from noisy observations of its moments. In fact, we provide a statistical approach to the famous Hausdorff classical moment problem. We prove ... More
Detection of Single Molecules Illuminated by a Light-Emitting DiodeJan 14 2011Optical detection and spectroscopy of single molecules has become an indispensable tool in biological imaging and sensing. Its success is based on fluorescence of organic dye molecules under carefully engineered laser illumination. In this paper we demonstrate ... More
Product-Mix Auctions and Tropical GeometryMay 15 2015Oct 24 2017In a recent and ongoing work, Baldwin and Klemperer explored a connection between tropical geometry and economics. They gave a sufficient condition for the existence of competitive equilibrium in product-mix auctions of indivisible goods. This result, ... More
Curvature-Exploiting Acceleration of Elastic Net ComputationsJan 24 2019This paper introduces an efficient second-order method for solving the elastic net problem. Its key innovation is a computationally efficient technique for injecting curvature information in the optimization process which admits a strong theoretical performance ... More
Ultrahigh molecular recognition specificity of competing DNA oligonucleotide strands in thermal equilibriumFeb 15 2016The specificity of molecular recognition is important to molecular self-organization. A prominent example is the biological cell where, within a highly crowded molecular environment, a myriad of different molecular receptor pairs recognize their binding ... More
Combinatorial Types of Tropical EigenvectorsMay 27 2011Jan 23 2012The map which takes a square matrix to its tropical eigenvalue-eigenvector pair is piecewise linear. We determine the cones of linearity of this map. They are simplicial but they do not form a fan. Motivated by statistical ranking, we also study the restriction ... More
Analytically weak solutions to SPDEs with unbounded time-dependent differential operators and an applicationDec 08 2011Jan 30 2013We analyze the concepts of analytically weak solutions of stochastic differential equations (SDEs) in Hilbert spaces with time-dependent unbounded operators and give conditions for existence and uniqueness of such solutions. Our studies are motivated ... More
Yet again on iteration improvement for averaged expected cost control for 1D ergodic diffusionsDec 27 2018Mar 11 2019The paper is a full version of the short presentation in \cite{amv17}. Ergodic control for one-dimensional controlled diffusion is tackled; both drift and diffusion coefficients may depend on a strategy which is assumed markovian. Ergodic HJB equation ... More
Partial decode-forward for quantum relay channelsDec 29 2011A relay channel is one in which a Source and Destination use an intermediate Relay station in order to improve communication rates. We propose the study of relay channels with classical inputs and quantum outputs and prove that a "partial decode and forward" ... More
Energy Minimization for the Half-Duplex Relay Channel with Decode-Forward RelayingAug 13 2011Mar 19 2013We analyze coding for energy efficiency in relay channels at a fixed source rate. We first propose a half-duplex decode-forward coding scheme for the Gaussian relay channel. We then derive three optimal sets of power allocation, which respectively minimize ... More
Modeling and Analysis of Energy Efficiency and Interference for Cellular Relay DeploymentMar 20 2015By relying on a wireless backhaul link, relay stations enhance the performance of cellular networks at low infrastructure cost, but at the same time, they can aggravate the interference issue. In this paper, we analyze for several relay coding schemes ... More
Generalized Post-Widder inversion formula with application to statisticsNov 30 2015In this work we derive an inversion formula for the Laplace transform of a density observed on a curve in the complex domain, which generalizes the well known Post-Widder formula. We establish convergence of our inversion method and derive the corresponding ... More
The Riemann problem for the shallow water equations with discontinuous topographyDec 21 2007We construct the solution of the Riemann problem for the shallow water equations with discontinuous topography. The system under consideration is non-strictly hyperbolic and does not admit a fully conservative form, and we establish the existence of two-parameter ... More
An interpolant in predicate Gödel logicMar 08 2018Feb 12 2019A logic satisfies the interpolation property provided that whenever a formula {\Delta} is a consequence of another formula {\Gamma}, then this is witnessed by a formula {\Theta} which only refers to the language common to {\Gamma} and {\Delta}. That is, ... More
Yet again on iteration improvement for averaged expected cost control for 1D ergodic diffusionsDec 27 2018Apr 06 2019The paper is a full version of the short presentation in \cite{amv17}. Ergodic control for one-dimensional controlled diffusion is tackled; both drift and diffusion coefficients may depend on a strategy which is assumed markovian. Ergodic HJB equation ... More
Translating Answer-Set Programs into Bit-Vector LogicAug 30 2011Answer set programming (ASP) is a paradigm for declarative problem solving where problems are first formalized as rule sets, i.e., answer-set programs, in a uniform way and then solved by computing answer sets for programs. The satisfiability modulo theories ... More
Cooperative Beamforming for Cognitive Radio-Based Broadcasting Systems with Asynchronous InterferencesMay 08 2014In order to address the asynchronous interference issue for a generalized scenario with multiple primary and multiple secondary receivers, in this paper, we propose an innovative cooperative beamforming technique. In particular, the cooperative beamforming ... More
Ultrafast Intersystem Crossing in SO$_2$ and NucleobasesMar 28 2017Mixed quantum-classical dynamics simulations show that intersystem crossing between singlet and triplet states in SO$_2$ and in nucleobases takes place on an ultrafast timescale (few 100~fs), directly competing with internal conversion.
Bot Electioneering Volume: Visualizing Social Bot Activity During ElectionsFeb 06 2019It has been widely recognized that automated bots may have a significant impact on the outcomes of national events. It is important to raise public awareness about the threat of bots on social media during these important events, such as the 2018 US midterm ... More
The minimum entropy principle for fluid flows in a nozzle with discontinuous cross-sectionDec 21 2007We consider the Euler equations for compressible fluids in a nozzle whose cross-section is variable and may contain discontinuities. We view these equations as a hyperbolic system in nonconservative form and investigate weak solutions in the sense of ... More
Assessing Visual Quality of Omnidirectional VideosSep 19 2017Jan 15 2019In contrast with traditional video, omnidirectional video enables spherical viewing direction with support for head-mounted displays, providing an interactive and immersive experience. Unfortunately, to the best of our knowledge, there are few visual ... More
MISO Capacity with Per-Antenna Power ConstraintMar 08 2010Jan 18 2011We establish in closed-form the capacity and the optimal signaling scheme for a MISO channel with per-antenna power constraint. Two cases of channel state information are considered: constant channel known at both the transmitter and receiver, and Rayleigh ... More
Regularity of distributions of Wigner integralsDec 23 2015Mar 07 2016Wigner integrals and the corresponding Wigner chaos were introduced by P. Biane and R. Speicher in 1998 as a non-commutative counterpart of classical Wiener-It\^o integrals and the corresponding Wiener-It\^o chaos, respectively, in free probability. In ... More
Stone duality, topological algebra, and recognitionSep 10 2013Our main result is that any topological algebra based on a Boolean space is the extended Stone dual space of a certain associated Boolean algebra with additional operations. A particular case of this result is that the profinite completion of any abstract ... More
Refolding upon force quench and pathways of mechanical and thermal unfolding of ubiquitinNov 24 2006The refolding from stretched initial conformations of ubiquitin (PDB ID: 1ubq) under the quenched force is studied using the Go model and the Langevin dynamics. It is shown that the refolding decouples the collapse and folding kinetics. The force quench ... More
Renormalization Group Study of a Fragile Fermi liquid in $1+ε$ dimensionsFeb 11 2016Feb 14 2016We present a calculation of the low energy Greens function in $1+\epsilon$ dimensions using the method of extended poor man's scaling, developed here. We compute the wave function renormalization $Z(\omega)$ and also the decay rate near the Fermi energy. ... More
Gelfand-Pinsker coding achieves the interference-free capacityAug 27 2010Sep 03 2010For a discrete memoryless channel with non-causal state information available only at the encoder, it is well-known that Gelfand-Pinsker coding achieves its capacity. In this paper, we analyze Gelfand-Pinsker coding scheme and capacity to bring out further ... More
Constraints on the chiral unitary $\bar KN$ amplitude from $πΣK^+$ photoproduction dataOct 13 2015A chiral unitary approach for antikaon-nucleon scattering in on-shell factorization is studied. We find multiple sets of parameters for which the model describes all existing hadronic data similarly well. We confirm the two-pole structure of the ${\Lambda}(1405)$. ... More
Learning to Decipher Hate SymbolsApr 04 2019Existing computational models to understand hate speech typically frame the problem as a simple classification task, bypassing the understanding of hate symbols (e.g., 14 words, kigy) and their secret connotations. In this paper, we propose a novel task ... More
Hierarchical CVAE for Fine-Grained Hate Speech ClassificationAug 31 2018Existing work on automated hate speech detection typically focuses on binary classification or on differentiating among a small set of categories. In this paper, we propose a novel method on a fine-grained hate speech classification task, which focuses ... More
Phenomenological model for a novel melt-freeze phase of sliding bilayersJan 31 2006Simulations show that sliding bilayers of colloidal particles can exhibit a new phase, the ``melt-freeze'' phase, where the layers stochastically alternate between solidlike and liquidlike states. We introduce a mean field phenomenological model with ... More
Mixing of ultracold atomic clouds by merging of two magnetic trapsJun 15 2006Feb 18 2007We demonstrate a method to make mixtures of ultracold atoms that does not make use of a two-species magneto-optical trap. We prepare two clouds of 87Rb atoms in distinct magnetic quadrupole traps and mix the two clouds by merging the traps. For correctly ... More
Limitations of OpenFlow Topology Discovery ProtocolMay 01 2017May 12 2017OpenFlow Discovery Protocol (OFDP) is the de-facto protocol used by OpenFlow controllers to discover the underlying topology. In this paper, we show that OFDP has some serious security, efficiency and functionality limitations that make it non suitable ... More
Multi-Object Reasoning with Constrained Goal ModelsJan 27 2016Nov 25 2016Goal models have been widely used in Computer Science to represent software requirements, business objectives, and design qualities. Existing goal modelling techniques, however, have shown limitations of expressiveness and/or tractability in coping with ... More
Bounce Universe and Black Holes from Critical Einsteinian Cubic GravityJul 19 2017We show that there exists a critical point for the coupling constants in Einsteinian cubic gravity where the linearized equations on the maximally-symmetric vacuum vanish identically. We construct an exact isotropic bounce universe in the critical theory ... More
Leveraging Intra-User and Inter-User Representation Learning for Automated Hate Speech DetectionApr 09 2018Sep 14 2018Hate speech detection is a critical, yet challenging problem in Natural Language Processing (NLP). Despite the existence of numerous studies dedicated to the development of NLP hate speech detection approaches, the accuracy is still poor. The central ... More
On spatial and temporal multilevel dynamics and scaling effects in epileptic seizuresMar 30 2011Jul 29 2011Epileptic seizures are one of the most well-known dysfunctions of the nervous system. During a seizure, a highly synchronized behavior of neural activity is observed that can cause symptoms ranging from mild sensual malfunctions to the complete loss of ... More
Friction force: from mechanics to thermodynamicsNov 17 2009Jul 01 2010We study some mechanical problems in which a friction force is acting on the system. Using the fundamental concepts of state, time evolution and energy conservation we explain how to extend Newtonian mechanics to thermodynamics. We arrive at the two laws ... More
On the relativistic KMS condition for the P(φ)_2 modelSep 29 2006The relativistic KMS condition introduced by Bros and Buchholz provides a link between quantum statistical mechanics and quantum field theory. We show that for the $P(\phi)_2$ model at positive temperature, the two point function for fields satisfies ... More
Thermal Quantum Fields with Spatially Cut-off Interactions in 1+1 Space-time DimensionsJul 25 2003We construct interacting quantum fields in 1+1 space-time dimensions, representing charged or neutral scalar bosons at positive temperature and zero chemical potential. Our work is based on prior work by Klein and Landau and Hoegh-Krohn. Generalized path ... More
Relaxed Logarithmic Barrier Function Based Model Predictive Control of Linear SystemsMar 11 2015In this paper, we investigate the use of relaxed logarithmic barrier functions in the context of linear model predictive control. We present results that allow to guarantee asymptotic stability of the corresponding closed-loop system, and discuss further ... More
Staggered domain wall fermionsSep 16 2016We construct domain wall fermions with a staggered kernel and investigate their spectral and chiral properties numerically in the Schwinger model. In some relevant cases we see an improvement of chirality by more than an order of magnitude as compared ... More
Removable presymplectic singularities and the local splitting of Dirac structuresOct 20 2014Oct 27 2015We call a singularity of a presymplectic form $\omega$ removable in its graph if its graph extends to a smooth Dirac structure over the singularity. An example for this is the symplectic form of a magnetic monopole. A criterion for the removability of ... More
MPL - a program for computations with iterated integrals on moduli spaces of curves of genus zeroOct 14 2015We introduce the computer program MPL for computations with homotopy invariant iterated integrals on moduli spaces $\mathcal{M}_{0,n}$ of curves of genus 0 with $n$ ordered marked points. The program is an implementation of the algorithms presented in ... More
Predicting zero reductions in Gröbner basis computationsApr 01 2014Since Buchberger's initial algorithm for computing Gr\"obner bases in 1965 many attempts have been taken to detect zero reductions in advance. Buchberger's Product and Chain criteria may be known the most, especially in the installaton of Gebauer and ... More
Discrete Complex Structure on Surfel SurfacesFeb 12 2008This paper defines a theory of conformal parametrization of digital surfaces made of surfels equipped with a normal vector. The main idea is to locally project each surfel to the tangent plane, therefore deforming its aspect-ratio. It is a generalization ... More
No information or horizon paradoxes for Th. SmithsMay 04 2015'Th'e 'S'tatistical 'm'echanician 'i'n 'th'e 's'treet (our Th. Smiths) must be surprised upon hearing popular versions of some of today's most discussed paradoxes in astronomy and cosmology. In fact, rather standard reminders of the meaning of thermal ... More
Many-body theory of degenerate systems: A simple exampleDec 05 2003The hierarchy of Green functions for (quasi)degenerate systems, presented in cond-mat/0308058, is calculated in detail for the case of a system with closed shells plus a single electron in a two-fold degenerate level. The complete hierarchy is derived ... More
Renormalization of QED in an external fieldFeb 08 2002The Schwinger equations of QED are rewritten in three different ways as integral equations involving functional derivatives, which are called weak field, strong field, and SCF quantum electrodynamics. The perturbative solutions of these equations are ... More
Quantum field theory of degenerate systemsJul 22 2003To set up a self-consistent quantum field theory of degenerate systems, the unperturbed state should be described by a density matrix instead of a pure state. This increases the combinatorial complexity of the many-body equations. Hopf algebraic techniques ... More
Vacuum Polarisation Tensors in Constant Electromagnetic Fields: Part IIFeb 25 2000In the second part of this series we apply the ``string-inspired'' technique to the calculation of one-loop amplitudes involving both vectors and axialvectors, as well as a general constant electromagnetic background field. The vector-axialvector two-point ... More
Cataclysmic Variables in Globular ClustersDec 05 2011Feb 10 2012Every massive globular cluster (GC) is expected to harbour a significant population of cataclysmic variables (CVs). In this review, I first explain why GC CVs matter astrophysically, how many and what types are theoretically predicted to exist and what ... More
Far-Ultraviolet Surveys of Globular Clusters: Hunting for the Products of Stellar Collisions and Near MissesJul 02 2004Globular clusters are gravitationally bound stellar systems containing on the order of 100,000 stars. Due to the high stellar densities in the cores of these clusters, close encounters and even physical collisions between stars are inevitable. These dynamical ... More
On the Calculation of QED Amplitudes in a Constant FieldJul 08 1998It is explained how first-quantized worldline path integrals can be used as an efficient alternative to Feynman diagrams in the calculation of QED amplitudes and effective actions. The examples include the one-loop photon splitting amplitude, the two-loop ... More
On the Stability of Contention Resolution Diversity Slotted ALOHAMar 21 2012In this paper a Time Division Multiple Access (TDMA) based Random Access (RA) channel with Successive Interference Cancellation (SIC) is considered for a finite user population and reliable retransmission mechanism on the basis of Contention Resolution ... More
Isotropy of Angular Frequencies and Weak Chimeras With Broken SymmetryDec 04 2015Oct 28 2016The notion of a weak chimeras provides a tractable definition for chimera states in networks of finitely many phase oscillators. Here we generalize the definition weak chimera to a more general class of equivariant dynamical systems by characterizing ... More
The Reeh-Schlieder property for ground statesJan 24 2000Feb 10 2000Recently it has been shown that the Reeh-Schlieder property w.r.t. thermal equilibrium states is a direct consequence of locality, additivity and the relativistic KMS condition. Here we extend this result to ground states.
Cluster Estimates for Modular StructuresApr 02 1998Apr 07 1999The basic ingredients of Tomita-Takesaki modular theory are used to establish cluster estimates. Applications to thermal quantum field theory are discussed.
Magnetoelectric bistabilities in ferromagnetic resonant tunneling structuresJul 28 2008The conditions for the occurrence of pronounced magnetoelectric bistabilities in the resonant tunneling through a ferromagnetic quantum well are theoretically investigated. The bistability appears due to the mutual feedback of the carriers Coulomb interaction ... More
Ricci curvature bounds for warped productsSep 06 2012Nov 09 2013We prove generalized lower Ricci curvature bounds for warped products over complete Finsler manifolds. On the one hand our result covers a theorem of Bacher and Sturm concerning euclidean and spherical cones. On the other hand it can be seen in analogy ... More
Obata's rigidity theorem for metric measure spacesOct 20 2014Apr 13 2015We prove Obata's rigidity theorem for metric measure spaces that satisfy a Riemannian curvature-dimension condition. Additionally, we show that a lower bound $K$ for the generalized Hessian of a sufficiently regular function $u$ holds if and only if $u$ ... More
Nominal Unification RevisitedDec 22 2010Nominal unification calculates substitutions that make terms involving binders equal modulo alpha-equivalence. Although nominal unification can be seen as equivalent to Miller's higher-order pattern unification, it has properties, such as the use of first-order ... More
Orthogonal bundles over curves in characteristic twoNov 11 2008Dec 09 2008Let X be a smooth projective curve of genus g \geq 2 defined over a field of characteristic two. We give examples of stable orthogonal bundles with unstable underlying vector bundles and use them to give counterexamples to Behrend's conjecture on the ... More
The characteristic polynomial of a random unitary matrix and Gaussian multiplicative chaos - The $L^2$-phaseOct 03 2014Oct 02 2015We study the characteristic polynomial of Haar distributed random unitary matrices. We show that after a suitable normalization, as one increases the size of the matrix, powers of the absolute value of the characteristic polynomial as well as powers of ... More
Exact asymptotics of the freezing transition of a logarithmically correlated random energy modelMay 12 2011Aug 26 2011We consider a logarithmically correlated random energy model, namely a model for directed polymers on a Cayley tree, which was introduced by Derrida and Spohn. We prove asymptotic properties of a generating function of the partition function of the model ... More
LHC Phenomenology of the Three-Site Higgsless ModelNov 08 2010We investigate the potential of the LHC for discovering the heavy vector and fermion resonances present in the Three-Site Higgsless Model. To this end, the model was implemented into the WHIZARD parton-level Monte Carlo eventgenerator. The results of ... More
On quasi-normal modes, area quantization and Bohr correspondence principleMar 18 2015Mar 30 2015In Int. Journ. Mod. Phys. D 14, 181 (2005), the author Khriplovich verbatim claims that "the correspondence principle does not dictate any relation between the asymptotics of quasinormal modes and the spectrum of quantized black holes" and that "this ... More
Bohr-like black holesMar 11 2015The idea that black holes (BHs) result in highly excited states representing both the "hydrogen atom" and the "quasi-thermal emission" in quantum gravity is today an intuitive but general conviction. In this paper it will be shown that such an intuitive ... More
Gravitational Waves Astronomy: a cornerstone for gravitational theoriesJun 28 2010Realizing a gravitational wave (GW) astronomy in next years is a great challenge for the scientific community. By giving a significant amount of new information, GWs will be a cornerstone for a better understanding of gravitational physics. In this paper ... More
An oscillating Universe from the linearized R^{2} theory of gravityFeb 18 2008Feb 19 2008An oscillating Universe which arises from the linearized R^{2} theory of gravity is discussed, showing that some observative evidences like the cosmological redshift and the Hubble law are in agreement with the model. In this context Dark Energy is seen ... More
Massive gravitational waves from the R^2 theory of gravity: production and response of interferometersNov 30 2007We show that from the R^{2} high order gravity theory it is possible to produce, in the linearized approch, particles which can be seen like massive modes of gravitational waves (GWs). The presence of the mass generates a longitudinal force in addition ... More
The Virgo - MiniGRAIL cross correlation for the detection of scalar gravitational wavesJun 26 2007Jul 05 2007After a review of the frequency - dependent angular pattern of interferometers in the TT gauge for scalar gravitational waves (SGWs), which has been recently analysed by Capozziello and Corda, in this letter the result is used to study the cross correlation ... More
Extension of the frequency-range of interferometers for the ''magnetic'' components of gravitational waves?Oct 31 2006Mar 26 2007Recently, with an enlighting treatment, Baskaran and Grishchuk have shown the presence and importance of the so-called ``magnetic'' components of gravitational waves (GWs), which have to be taken into account in the context of the total response functions ... More
Quasi-normal modes: the "electrons" of black holes as "gravitational atoms"? Implications for the black hole information puzzleFeb 26 2015Mar 31 2015Some recent important results on black hole (BH) quantum physics concerning the BH effective state and the natural correspondence between Hawking radiation and BH quasi-normal modes (QNMs) are reviewed, clarified and refined. Such a correspondence permits ... More
Quantum transitions of minimum energy for Hawking quanta in highly excited black holes: problems for loop quantum gravity?Dec 03 2012Dec 12 2013By analysing some recent results by Yoon, which arise from loop quantum gravity and from the assumption of the locality of photon emission in a black hole, we argue that they are not consistent with our recent semi-classical results for highly excited ... More
Effective temperature, Hawking radiation and quasinormal modesMay 17 2012Parikh and Wilczek have shown that Hawking radiation's spectrum cannot be strictly thermal. Such a non-strictly thermal character implies that the spectrum is also not strictly continuous and thus generates a natural correspondence between Hawking radiation ... More
General relativity and OPERA ExperimentJan 21 2012Nov 08 2012In his paper "A very simple solution to the OPERA neutrino velocity problem" the author J. Manuel Garcia-Islas claims to have very easily solved and explained within the general theory of relativity that OPERA's neutrinos are not traveling faster than ... More
A clarification on a common misconception about interferometric detectors of gravitational wavesMar 24 2011The aims of this letter are two. First, to show the angular gauge-invariance on the response of interferometers to gravitational waves (GWs). In this process, after resuming for completeness results on the Transverse-Traceless (TT) gauge, where, in general, ... More
Presentation of the Second Big Challenge Symposium - The Big Challenge of Cosmological Understanding: Gravitation, Dark Matter and Dark Energy. Towards New ScenariosJul 23 2010This Symposium is devoted to the Memory of Lev Kofman, June-17-1957-November-12-2009. The accelerated expansion of the Universe, which is today observed, shows that cosmological dynamics is dominated by the so-called Dark Energy field which provides a ... More
Will gravitational waves confirm Einstein's General Relativity?Jul 13 2009Jul 21 2009Even if Einstein's General Relativity achieved a great success and overcame lots of experimental tests, it also showed some shortcomings and flaws which today advise theorists to ask if it is the definitive theory of gravity. In this proceeding paper ... More
Consistent Dyson summation of Higgs propagators in nonlinear parameterizations revisitedJul 05 2004Dec 10 2004As we demonstrate in a process independent way, in a nonlinear parameterization of the scalar sector of the standard model the Dyson summation of the Higgs self energy can be performed without violating the Ward Identities. This implies also the Goldstone ... More
Higgsless fermion masses and unitarityFeb 11 2004Apr 20 2004We discuss the consistency of fermion mass generation by boundary conditions and brane localized terms in higher dimensional Higgsless models of gauge symmetry breaking. The sum rules imposed by tree-level unitarity and Ward Identities are applied to ... More
Twistor-inspired construction of massive quark amplitudesSep 09 2008Oct 30 2008The analog of the Cachazo-Svrvcek-Witten rules for scattering amplitudes with massive quarks is derived following an approach previously employed for amplitudes with massive scalars. A prescription for the external wave-functions is given that leads to ... More
From Tree Unitarity to Top Quark Physics in 5D Higgsless ModelsSep 26 2005In five dimensional models of Higgsless electroweak symmetry breaking, tree level unitarity in gauge boson scattering is restored by the exchange of gauge boson Kaluza-Klein modes instead of a Higgs boson. Unitarity of scattering amplitudes involving ... More
Theory status of four-fermion production at e-e+ collidersDec 17 2015The status of predictions for four-fermion production at e-e+ colliders is reviewed with an emphasis on the developments after the LEP2 era and an outlook to the challenges posed by the precision program at future colliders.
Algebraic quantum theoryApr 08 2004The main objective consists in endowing the elementary particles with an algebraic space-time structure in the perspective of unifying quantum field theory and general relativity: this is realized in the frame of the Langlands global program based on ... More
When is the underlying space of an orbifold a topological manifold?Jul 18 2013We answer the question posed by Davis: "When is the underlying space of an orbifold a topological manifold". It amounts to the classification of finite groups acting linearly on a Euclidean vector space such that the quotient space is homeomorphic to ... More
Warning signs for wave speed transitions of noisy Fisher-KPP invasion frontsDec 03 2012Invasion waves are a fundamental building block of theoretical ecology. In this study we aim to take the first steps to link propagation failure and fast acceleration of traveling waves to critical transitions (or tipping points). The approach is based ... More