Results for "acob Madsen"

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A deep learning approach to identify local structures in atomic-resolution transmission electron microscopy imagesFeb 08 2018Recording atomic-resolution transmission electron microscopy (TEM) images is becoming increasingly routine. A new bottleneck is then analyzing this information, which often involves time-consuming manual structural identification. We have developed a ... More
Cosmic ray strangeletsNov 22 2004Searching for strangelets in cosmic rays may be the best way to test the possible stability of strange quark matter. I review calculations of the astrophysical strangelet flux in the GV--TV rigidity range, which will be investigated from the Alpha Magnetic ... More
Color-flavor locked strangelets and their detectionDec 11 2001Strange quark matter in a color-flavor locked state is significantly more bound than ``ordinary'' strange quark matter. This increases the likelihood of strangelet metastability or even absolute stability. Properties of color-flavor locked strangelets ... More
Physical Properties of StrangeletsFeb 07 1995Low-baryon number lumps of strange quark matter, strangelets, are presently searched for in ultra-relativistic heavy-ion experiments at CERN and Brookhaven. This paper gives an overview of the physical properties of strangelets with emphasis on experimental ... More
On a common generalization of Koszul duality and tilting equivalenceJul 19 2010We propose a new definition of Koszulity for graded algebras where the degree zero part has finite global dimension, but is not necessarily semi-simple. The standard Koszul duality theorems hold in this setting. We give an application to algebras arising ... More
An integral Riemann-Roch theorem for surface bundlesJan 27 2009This paper proves an integral version of the Riemann-Roch theorem for surface bundles, comparing the standard cohomology classes with the cohomology classes coming from the symplectic group.
Universal Charge-Radius Relation for Subatomic and Astrophysical Compact ObjectsApr 14 2008Electron-positron pair creation in supercritical electric fields limits the net charge of any static, spherical object, such as superheavy nuclei, strangelets, and Q-balls, or compact stars like neutron stars, quark stars, and black holes. For radii between ... More
Strangelets, Nuclearites, Q-balls--A Brief OverviewDec 27 2006Astrophysical bounds on the properties and abundances of primordial quark nuggets and cosmic ray strangelets are reviewed. New experiments to search for cosmic ray strangelets in lunar soil and from the International Space Station are described. Analogies ... More
Finite Mass Isothermal Spheres and the Structure of Globular ClustersJan 23 1996Utilizing a recently derived extension of the Maxwell-Boltzmann distribution to low occupation numbers (Simons 1994) this investigation discusses the structure of stellar dynamical isothermal spheres. The resulting models, which resemble King models, ... More
Reply to Comment on Strangelets as Cosmic Rays beyond the Greisen-Zatsepin-Kuzmin CutoffMar 22 2004It is argued that strangelets are viable candidates for ultrahigh energy cosmic rays that circumvent the acceleration and energy-loss problems facing protons and nuclei, in spite of concerns raised in a comment by Balberg.
Intermediate mass strangelets are positively chargedAug 21 2000Nov 16 2000For a limited range of parameters, stable strange quark matter may be negatively charged in bulk due to one gluon exchange interactions. However, the reduction in strange quark occupation in the surface layer, which is responsible for surface tension, ... More
Dark matter phase space densitiesJun 06 2000May 14 2001The low velocity part of a kinetic equilibrium dark matter distribution has higher phase space density and is more easily incorporated in formation of a low mass galaxy than the high velocity part. For relativistically decoupling fermions (bosons), this ... More
Physics of StrangeletsDec 19 1994After a brief introduction to the physics of bulk strange quark matter (SQM) this review focuses on the properties of low baryon number strangelets presently searched for in ultra-relativistic heavy-ion experiments at CERN and Brookhaven. Shell-model ... More
Strangelets in Cosmic RaysDec 29 2006The properties of strangelets are reviewed and two experiments searching for them in cosmic rays are described. The prospects for strangelets as ultra-high energy cosmic rays beyond the classical GZK-cutoff are discussed.
Stable quark matter in cosmic rays?Dec 20 2005Stable lumps of quark matter may be present in cosmic rays at a flux level, which can be detected by high precision cosmic ray experiments sensitive to anomalous "nuclei" with high mass-to-charge ratio. The properties of these lumps, called strangelets, ... More
Color-flavor locking in strange stars, strangelets, and cosmic raysNov 29 2001Three topics with relation to color superconductivity in strange quark matter are discussed. 1) The r-mode instability in strange stars, which is consistent with the existence of ``ordinary'' strange quark matter stars but inconsistent with strange stars ... More
Shell model versus liquid drop model for strangeletsJul 18 1994An ansatz for the curvature contribution to the density of states for massive quarks in a bag is given and shown to reproduce exact mode-filling calculations. A mass-formula for spherical lumps of 3-flavor quark matter is derived self-consistently from ... More
Cavitation from bulk viscosity in neutron stars and quark starsSep 21 2009Sep 30 2009The bulk viscosity in quark matter is sufficiently high to reduce the effective pressure below the corresponding vapor pressure during density perturbations in neutron stars and strange stars. This leads to mechanical instability where the quark matter ... More
Physics and Astrophysics of Strange Quark MatterSep 03 19983-flavor quark matter (strange quark matter; SQM) can be stable or metastable for a wide range of strong interaction parameters. If so, SQM can play an important role in cosmology, neutron stars, cosmic ray physics, and relativistic heavy-ion collisions. ... More
Detecting supersymmetric Q-balls with neutron starsJun 22 1998Supersymmetric Q-balls trapped in neutron stars or white dwarfs may cause the stars to explode. Trapping of Q-balls in neutron stars is shown to be less likely, but trapping in neutron star progenitors more likely than hitherto assumed, making neutron ... More
Equations of Rees algebras of ideals in two variablesNov 12 2015Let I be an ideal of height two in R=k[x_0,x_1] generated by forms of the same degree, and let K be the ideal of defining equations of the Rees algebra of I. Suppose that the second largest column degree in the syzygy matrix of I is e. We give an algorithm ... More
The Koszul dual of a weakly Koszul moduleFeb 02 2007We study the so-called weakly Koszul modules and characterise their Koszul duals. We show that the (adjusted) associated graded module of a weakly Koszul module exactly determines the homology modules of the Koszul dual. We give an example of a quasi-Koszul ... More
Reply to Comment [arXiv:0809.2310] on Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects [arXiv:0804.2140, PRL100 (2008) 151102]Oct 14 2008A reply to arXiv:0809.2310, "Comment on Universal Charge-Radius Relation for Subatomic and Astrophysical Compact Objects" [arXiv:0804.2140,PRL100(2008)151102]
Is Her X-1 a strange star?Jan 23 1996The possible identification of Her X-1 with a strange star (Li et al. 1995) is shown to be incorrect.
Strangelet propagation and cosmic ray fluxNov 18 2004Feb 03 2005The galactic propagation of cosmic ray strangelets is described and the resulting flux is calculated for a wide range of parameters as a prerequisite for strangelet searches in lunar soil and with an Earth orbiting magnetic spectrometer, AMS-02. While ... More
Color-flavor locked strangeletsAug 03 2001Oct 08 2001Finite lumps of color-flavor locked strange quark matter (CFL-strangelets) are significantly more stable than strangelets without color-flavor locking for wide ranges of parameters, increasing the likelihood of strangelet metastability, or even absolute ... More
How to identify a Strange StarJun 02 1998Contrary to young neutron stars, young strange stars are not subject to the r-mode instability which slows rapidly rotating, hot neutron stars to rotation periods near 10 ms via gravitational wave emission. Young millisecond pulsars are therefore likely ... More
Probing strange stars and color superconductivity by r-mode instabilities in millisecond pulsarsDec 20 1999Jun 06 2000R-mode instabilities in rapidly rotating quark matter stars (strange stars) lead to specific signatures in the evolution of pulsars with periods below 2.5 msec, and may explain the apparent lack of very rapid pulsars. Existing data seem consistent with ... More
Multiwavelength WHAM Observations of Extra-planar Warm Ionized Gas in the GalaxySep 20 2004We report on observations of several optical emission lines toward a variety of newly revealed faint, large-scale H-alpha-emitting structures in the warm ionized medium (WIM) of the Galaxy. The lines include [N II] 6583, [N II] 5755, [S II] 6716, [O III] ... More
Deterministic Capacity of MIMO Relay NetworksApr 01 2009The deterministic capacity of a relay network is the capacity of a network when relays are restricted to transmitting \emph{reliable} information, that is, (asymptotically) deterministic function of the source message. In this paper it is shown that the ... More
Rational homotopy theory of automorphisms of highly connected manifoldsJan 16 2014We study the rational homotopy types of classifying spaces of automorphism groups of 2d-dimensional (d-1)-connected manifolds (d > 2). We prove that the rational homology groups of the homotopy automorphisms and the block diffeomorphisms of the manifold ... More
Spin(7)-manifolds with three-torus symmetryApr 15 2011Metrics of exceptional holonomy are vacuum solutions to the Einstein equation. In this paper we describe manifolds with holonomy contained in Spin(7) preserved by a three-torus symmetry in terms of tri-symplectic geometry of four-manifolds. These complement ... More
Theoretical studies of high-harmonic generation: Effects of symmetry, degeneracy and orientationJun 22 2007Using a quantum mechanical three-step model we present numerical calculations on the high-harmonic generation from four polyatomic molecules. Ethylene (C$_2$H$_4$) serves as an example where orbital symmetry directly affects the harmonic yield. We treat ... More
High-harmonic generation from arbitrarily oriented diatomic molecules including nuclear motion and field-free alignmentMay 25 2006Jun 29 2006We present a theoretical model of high-harmonic generation from diatomic molecules. The theory includes effects of alignment as well as nuclear motion and is used to predict results for N$_2$, O$_2$, H$_2$ and D$_2$. The results show that the alignment ... More
A Differential Semantics of Lazy AR PropagationJul 04 2012In this paper we present a differential semantics of Lazy AR Propagation (LARP) in discrete Bayesian networks. We describe how both single and multi dimensional partial derivatives of the evidence may easily be calculated from a junction tree in LARP ... More
Nucleosynthesis and the mass of the tau neutrino---ERRATUMJun 27 1996Our results for the primordial abundance of a massive Majorana tau neutrino (hep-ph/9603201) published in PRL76, 2848 (1996) were incorrect due to a trivial (but annoying) error in the numerical code. In this ERRATUM we present the corrected results.
Consistency between deep crustal heating of strange stars in superbursters and soft X-ray transientsMar 21 2006Oct 11 2006Both superbursters and soft X-ray transients probe the process of deep crustal heating in compact stars. It was recently shown that the transfer of matter from crust to core in a strange star can heat the crust and ignite superbursts provided certain ... More
The WHAM Northern Sky Survey and the Nature of the Warm Ionized Medium in the GalaxyOct 13 2003The Wisconsin H-Alpha Mapper (WHAM) has completed a velocity-resolved map of diffuse H-alpha emission of the entire northern sky, providing the first comprehensive picture of both the distribution and kinematics of diffuse ionized gas in the Galaxy. WHAM ... More
Quasi-hereditary algebras and generalized Koszul dualityJan 02 2012Feb 17 2012We present an easily applicable sufficient condition for standard Koszul algebras to be Koszul with respect to $\Delta$. If a quasi-hereditary algebra $\L$ is Koszul with respect to $\Delta$, then $\L$ and the Yoneda extension algebra of $\Delta$ are ... More
Programs as proofsSep 14 2015The Curry-Howard correspondence is about a relationship between types and programs on the one hand and propositions and proofs on the other. The implications for programming language design and program verification is an active field of research. Transformer-like ... More
The moduli space of generalized Morse functionsApr 16 2010We study the moduli and determine a homotopy type of the space of all generalized Morse functions on d-manifolds for given d. This moduli space is closely connected to the moduli space of all Morse functions studied in the paper math.AT/0212321, and the ... More
An Empirical Evaluation of Possible Variations of Lazy PropagationJul 11 2012As real-world Bayesian networks continue to grow larger and more complex, it is important to investigate the possibilities for improving the performance of existing algorithms of probabilistic inference. Motivated by examples, we investigate the dependency ... More
Small Deviations from the R^1/4 Law, the Fundamental Plane, and Phase Densities of Elliptical GalaxiesDec 20 1994The light profiles of elliptical (E) galaxies are known to display small systematic deviations (0.1-0.2 mag.) from the R^1/4 law. In this paper we show that the senses and amplitudes of these departures can be naturally accounted for by a simple distribution ... More
Unbiased Cultural Transmission in Time-Averaged Archaeological AssemblagesApr 10 2012Nov 24 2012Unbiased models are foundational in the archaeological study of cultural transmission. Applications have as- sumed that archaeological data represent synchronic samples, despite the accretional nature of the archaeological record. I document the circumstances ... More
The cobordism category and Waldhausen's K-theoryFeb 21 2011This paper examines the category C^k_{d,n} whose morphisms are d-dimensional smooth manifolds that are properly embedded in the product of a k-dimensional cube with an (d+n-k)-dimensional Euclidean space. There are k directions to compose k-dimensional ... More
Belief Update in CLG Bayesian Networks With Lazy PropagationJun 27 2012In recent years Bayesian networks (BNs) with a mixture of continuous and discrete variables have received an increasing level of attention. We present an architecture for exact belief update in Conditional Linear Gaussian BNs (CLG BNs). The architecture ... More
Gaps below strange star crustsDec 06 2005The gap caused by a strong electric field between the quark surface and nuclear crust of a strange star is studied in an improved model including gravity and pressure as well as electrostatic forces. The transition from gap to crust is followed in detail. ... More
Does the quark-gluon plasma contain stable hadronic bubbles?Mar 17 2000We calculate the thermodynamic potential of bubbles of hadrons embedded in quark-gluon plasma, and of droplets of quark-gluon plasma embedded in hadron phase. This is a generalization of our previous results to the case of non-zero chemical potentials. ... More
Nucleosynthesis and the mass of the tau neutrinoMar 01 1996The primordial abundance of long-lived heavy Majorana neutrinos is calculated from the full Boltzmann equation. Inclusion of scattering reactions drastically change the predicted abundance of a heavy neutrino species. This loosens the well known mass ... More
Functional form of the generalized gradient approximation for exchange: The PBE$α$ functionalSep 15 2006Nov 14 2006A new functional form for the exchange enhancement in the generalized gradient approximation within density functional theory is given. The functional form satisfies the constraints used to construct the Perdew-Burke-Ernzerhof (PBE) functional but can ... More
The Evolutionary Biology of Ourselves: Unit Requirements and Organizational Change in United States HistoryJan 04 1999Researchers have proposed that the distinction between so-called "simple" and "complex" societies can be expressed by an increase in the number of levels at which functional organization, interaction, and thus selection, operate. In spite of the obvious ... More
Homological stability of diffeomorphism groupsMar 19 2012Sep 04 2012In this paper we prove a stability theorem for block diffeomorphisms of 2d-dimensional manifolds that are connected sums of S^d x S^d. Combining this with a recent theorem of S. Galatius and O. Randal-Williams and Morlet's lemma of disjunction, we determine ... More
On the K-theory of local fieldsOct 22 1999Jan 22 2004The authors establish a connection between the Quillen K-theory of certain local fields and the de Rham-Witt complex of their rings of integers with logarithmic poles at the maximal ideal. They consider fields K that are complete discrete valuation fields ... More
Free energy of bubbles and droplets in the quark-hadron phase transitionJul 07 1998Aug 02 1999Using the MIT bag model, we calculate the free energy of droplets of quark-gluon plasma in a bulk hadronic medium, and of hadronic bubbles in a bulk quark-gluon plasma, under the assumption of vanishing chemical potentials. We investigate the validity ... More
Neutrino decoupling in the early UniverseJun 02 1995A calculation of neutrino decoupling in the early Universe, including full Fermi-Dirac statistics and electron mass dependence in the weak reaction rates, is presented. We find that after decoupling, the electron neutrinos contribute 0.83\% more to the ... More
A Cosmological Three Level Neutrino LaserFeb 14 1997We present a calculation of a neutrino decay scenario in the early Universe. The specific decay is \nu_{2} \to \nu_{1} + \phi, where \phi is a boson. If there is a neutrino mass hierarchy, m_{\nu_{e}} < m_{\nu_{\mu}} < m_{\nu_{\tau}}, we show that it ... More
Inducing elliptically polarized high-order harmonics from aligned molecules with linearly polarized femtosecond pulsesOct 08 2009Dec 10 2009A recent paper reported elliptically polarized high-order harmonics from aligned N$_2$ using a linearly polarized driving field [X. Zhou \emph{et al.}, Phys. Rev. Lett. \textbf{102}, 073902 (2009)]. This observation cannot be explained in the standard ... More
Characterization of Molecular Breakup by Very Intense Femtosecond XUV Laser PulsesFeb 24 2015Apr 10 2016We study the breakup of $\text{H}_2^+$ exposed to super-intense, femtosecond laser pulses with frequencies greater than that corresponding to the ionization potential. By solving the time-dependent Schr\"odinger equation in an extensive field parameter ... More
Time-dependent restricted-active-space self-consistent field theory for laser-driven many-electron dynamicsApr 22 2013May 21 2014We present the time-dependent restricted-active-space self-consistent field (TD-RASSCF) theory as a new framework for the time-dependent many-electron problem. The theory generalizes the multiconfigurational time-dependent Hartree-Fock (MCTDHF) theory ... More
Continuous measurements on continuous variable quantum systems: The Gaussian descriptionNov 16 2005The Gaussian state description of continuous variables is adapted to describe the quantum interaction between macroscopic atomic samples and continuous-wave light beams. The formalism is very efficient: a non-linear differential equation for the covariance ... More
Dissociative ionization of H2+ using intense femtosecond XUV laser pulsesOct 07 2014Feb 24 2015The dissociative ionization of H2+ interacting with intense, femtosecond extreme-ultraviolet laser pulses is investigated theoretically. This is done by numerical propagation of the time-dependent Schr\"{o}dinger equation for a colinear one-dimensional ... More
Linearization of W algebras and W superalgebrasOct 10 1995Oct 16 1995In a recent paper, the authors have shown that the secondary reduction of W-algebras provides a natural framework for the linearization of W-algebras. In particular, it allows in a very simple way the calculation of the linear algebra $W(G,H)_{\geq0}$ ... More
Secondary Quantum Hamiltonian ReductionMar 07 1995Jan 18 1996Recently, it has been shown how to perform the quantum hamiltonian reduction in the case of general $sl(2)$ embeddings into Lie (super)algebras, and in the case of general $osp(1|2)$ embeddings into Lie superalgebras. In another development it has been ... More
Quantum Hamiltonian Reduction in Superspace FormalismMar 02 1994Recently the quantum hamiltonian reduction was done in the case of general $s\ell(2)$ embeddings into Lie algebras and superalgebras. In this paper we extend the results to the quantum hamiltonian reduction of $N=1$ affine Lie superalgebras in the superspace ... More
Strangelets as Cosmic Rays beyond the Greisen-Zatsepin-Kuzmin CutoffNov 27 2002Mar 20 2003Strangelets (stable lumps of quark matter) can have masses and charges much higher than those of nuclei, but have very low charge-to-mass ratios. This is confirmed in a relativistic Thomas-Fermi model. The high charge allows astrophysical strangelet acceleration ... More
Mixed dark matter with neutrino chemical potentialsFeb 09 1995Jul 24 1995Mixed dark matter models with one low-mass (e.g. 2.4eV) neutrino flavor are shown to be in good agreement with observations if the neutrinos have non-zero chemical potentials. This agreement holds (except for the problem with a low-age Universe) even ... More
Hamiltonian Reduction and Classical Extended Superconformal AlgebrasFeb 18 1992We present a systematic construction of classical extended superconformal algebras from the hamiltonian reduction of a class of affine Lie superalgebras, which include an even subalgebra $sl(2)$. In particular, we obtain the doubly extended $N=4$ superconformal ... More
Closed forms and multi-moment mapsOct 29 2011We extend the notion of multi-moment map to geometries defined by closed forms of arbitrary degree. We give fundamental existence and uniqueness results and discuss a number of essential examples, including geometries related to special holonomy. For ... More
The odd side of torsion geometryJul 12 2012Dec 10 2012We introduce and study a notion of `Sasaki with torsion structure' (ST) as an odd-dimensional analogue of K\"ahler with torsion geometry (KT). These are normal almost contact metric manifolds that admit a unique compatible connection with 3-form torsion. ... More
Half-flat structures on S^3xS^3Nov 29 2012Mar 26 2013We describe left-invariant half-flat SU(3)-structures on S^3xS^3 using the representation theory of SO(4) and matrix algebra. This leads to a systematic study of the associated cohomogeneity one Ricci-flat metrics with holonomy G_2 obtained on 7-manifolds ... More
Homogeneous spaces, multi-moment maps and (2,3)-trivial algebrasDec 02 2010For geometries with a closed three-form we briefly overview the notion of multi-moment maps. We then give concrete examples of multi-moment maps for homogeneous hypercomplex and nearly Kaehler manifolds. A special role in the theory is played by Lie algebras ... More
Surfaces in a background space and the homology of mapping class groupsJan 31 2006Sep 04 2008In this paper we study the topology of the space of Riemann surfaces in a simply connected space X, S_{g,n} (X, \gamma). This is the space consisting of triples, (F_{g,n}, \phi, f), where F_{g,n} is a Riemann surface of genus g and n-boundary components, ... More
Fidelities for transformations of unknown quantum statesDec 01 2005Mar 10 2006We present a general theoretical formalism to compute the fidelity of transformations of unknown quantum states. We then focus on the case of Gaussian transformations of continuous variable quantum systems, where, for the case of a Gaussian distribution ... More
Multi-moment mapsDec 09 2010Mar 17 2011We introduce a notion of moment map adapted to actions of Lie groups that preserve a closed three-form. We show existence of our multi-moment maps in many circumstances, including mild topological assumptions on the underlying manifold. Such maps are ... More
Large nucleation distances from impurities in the cosmological quark-hadron transitionFeb 15 1996We calculate the mean nucleation distance, $d_{nuc}$, in a first order cosmological quark-hadron phase transition. For homogeneous nucleation we find that self-consistent inclusion of curvature energy reduces $d_{nuc}$ to $\lesssim 2$cm. However, impurities ... More
Laser-induced dissociative ionization of H$_{2}$ from the near-infrared to the mid-infrared regimeDec 06 2016We apply the Monte Carlo Wave Packet (MCWP) approach to investigate the kinetic energy release (KER) spectra of the protons following double ionization in H$_{2}$ when interacting with laser pulses with central wavelengths ranging from the near-IR (800 ... More
Exterior time scaling with stiffness-free Lanczos time propagator: formulation and application to atoms interacting with strong mid-infrared lasersDec 21 2015Mar 30 2016Aiming at efficient numerical treatment of tunneling ionization of atoms and molecules by mid-infrared (IR) lasers, exterior time scaling (ETS) theory is formulated as a generalization of the time-scaled coordinate approach. The key idea of ETS is the ... More
Inter- and intracycle interference effects in strong-field dissociative ionizationDec 04 2015Mar 13 2016We theoretically study dissociative ionization of H$_2^+$ exposed to strong linearly polarized few-cycle visible, near-infrared and midinfrared laser pulses. We find rich energy-sharing structures in the combined electron and nuclear kinetic energy spectra ... More
Time-dependent restricted-active-space self-consistent-field singles method for many-electron dynamicsMay 21 2014The time-dependent restricted-active-space self-consistent-field singles (TD-RASSCF-S) method is presented for investigating TD many-electron dynamics in atoms and molecules. Adopting the SCF notion from the muticonfigurational TD Hartree-Fock (MCTDHF) ... More
Quantitative analysis of quantum dot dynamics and emission spectra in cavity quantum electrodynamicsOct 28 2012Dec 04 2012We present detuning-dependent spectral and decay-rate measurements to study the difference between spectral and dynamical properties of single quantum dots embedded in micropillar and photonic-crystal cavities. For the micropillar cavity, the dynamics ... More
Entanglement between remote continuous variable quantum systems: effects of transmission lossMar 29 2006We study the effects of losses on the entanglement created between two separate atomic gases by optical probing and homodyne detection of the transmitted light. The system is well-described in the Gaussian state formulation. Analytical results quantifying ... More
Solving Influence Diagrams using HUGIN, Shafer-Shenoy and Lazy PropagationJan 10 2013In this paper we compare three different architectures for the evaluation of influence diagrams: HUGIN, Shafer-Shenoy, and Lazy Evaluation architecture. The computational complexity of the architectures are compared on the LImited Memory Influence Diagram ... More
Strangelets with finite entropyJul 14 1995Strangelets with non-zero entropy are studied within the MIT bag model. Explicit account is taken of the constraints that strangelets must be color neutral and have a fixed total momentum. In general, masses increase with increasing entropy per baryon, ... More
Harmonic structures and intrinsic torsionAug 19 2013Nov 19 2014We discuss the construction of Sp(2)Sp(1)-structures whose fundamental form is closed. In particular, we find 10 new examples of 8-dimensional nilmanifolds that admit an invariant closed 4-form with stabiliser Sp(2)Sp(1). Our constructions entail the ... More
High-order harmonic generation from polyatomic molecules including nuclear motion and a nuclear modes analysisJan 27 2010Mar 26 2010We present a generic approach for treating the effect of nuclear motion in the high-order harmonic generation from polyatomic molecules. Our procedure relies on a separation of nuclear and electron dynamics where we account for the electronic part using ... More
Dissociation and dissociative ionization of H2+ using the time-dependent surface flux methodOct 07 2014The time-dependent surface flux method developed for the description of electronic spectra [L. Tao and A. Scrinzi, New J. Phys. 14, 013021 (2012); A. Scrinzi, New J. Phys. 14, 085008 (2012)] is extended to treat dissociation and dissociative ionization ... More
Spin squeezing and precision probing with light and samples of atoms in the gaussian approximationJun 21 2004We consider an ensemble of trapped atoms interacting with a continuous wave laser field. For sufficiently polarized atoms and for a polarized light field, we may approximate the non-classical components of the collective spin angular momentum operator ... More
Stability for closed surfaces in a background spaceFeb 12 2010In this paper we present a new proof of the homological stability of the moduli space of closed surfaces in a simply connected background space $K$, which we denote by $S_g (K)$. The homology stability of surfaces in $K$ with an arbitrary number of boundary ... More
The Wideband Slope of Interference Channels: The Large Bandwidth CaseOct 27 2010Nov 11 2011It is well known that minimum received energy per bit in the interference channel is -1.59dB as if there were no interference. Thus, the best way to mitigate interference is to operate the interference channel in the low-SNR regime. However, when the ... More
"Nonrelativistic" kinematics: Particles or waves?May 11 2010The kinematics of particles refer to events and tangent vectors, while that of waves refer to dual gradient planes. Special relativity [1-3] applies to both objects alike. Here we show that spacetime exchange symmetry [7] implicit in the SIdefinition ... More
STRANGELETS AT NON-ZERO TEMPERATUREJan 17 1995A description of strange quark matter at finite temperature is given, with emphasis on the inclusion of finite size effects. For massless quarks all thermodynamic quantities can be evaluated analytically, while the case of massive quarks must be treated ... More
Nucleation of quark matter bubbles in neutron starsJan 03 1994The thermal nucleation of quark matter bubbles inside neutron stars is examined for various temperatures which the star may realistically encounter during its lifetime. It is found that for a bag constant less than a critical value, a very large part ... More
Toroidal Orbifold Models with a Wess-Zumino TermSep 16 1993Closed bosonic string theory on toroidal orbifolds is studied in a Lagrangian path integral formulation. It is shown that a level one twisted WZW action whose field value is restricted to Cartan subgroups of simply-laced Lie groups on a Riemann surface ... More
Hochschild homology and global dimensionMar 25 2008We prove that for certain classes of graded algebras (Koszul, local, cellular), infinite global dimension implies that Hochschild homology does not vanish in high degrees, provided the characteristic of the ground field is zero. Our proof uses Igusa's ... More
Invariant torsion and G_2-metricsOct 22 2014Oct 20 2015We introduce and study a notion of invariant intrinsic torsion geometry which appears, for instance, in connection with the Bryant-Salamon metric on the spinor bundle over S^3. This space is foliated by six-dimensional hypersurfaces, each of which carries ... More
Time-dependent restricted-active-space self-consistent-field theory for laser-driven many-electron dynamics. II. Extended formulation and numerical analysisMay 21 2014Jun 25 2014The time-dependent restricted-active-space self-consistent-field (TD-RASSCF) method is formulated based on the TD variational principle. In analogy with the configuration-interaction singles (CIS), singles-and-doubles (CISD), singles-doubles-and-triples ... More
Invariant strong KT geometry on four-dimensional solvable Lie groupsNov 03 2009A strong KT (SKT) manifold consists of a Hermitian structure whose torsion three-form is closed. We classify the invariant SKT structures on four-dimensional solvable Lie groups. The classification includes solutions on groups that do not admit compact ... More
The stable moduli space of Riemann surfaces: Mumford's conjectureDec 23 2002Jul 14 2004The main result of this paper amounts to a complete evaluation of the integral cohomological structure of the stable mapping class group. In particular it verifies the conjecture of D.Mumford about the rational cohomology of the stable mapping class group. ... More
Estimation of a classical parameter with gaussian probes: magnetometry with collective atomic spinsFeb 23 2004Mar 01 2004We present a theory for the estimation of a classical magnetic field by an atomic sample with a gaussian distribution of collective spin components. By incorporating the magnetic field and the probing laser field as quantum variables with gaussian distributions ... More
The Wideband Slope of Interference Channels: The Small Bandwidth CaseJul 18 2012This paper studies the low-SNR regime performance of a scalar complex K -user interference channel with Gaussian noise. The finite bandwidth case is considered, where the low-SNR regime is approached by letting the input power go to zero while bandwidth ... More