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Pulses from a mid-infrared quantum cascade laser frequency comb using an external compressorMay 14 2019A Martinez-type stretcher-compressor is used to modify the spectral phases of a high-power (~1 W) QCL comb emitted at 8.2 {\mu}m with more than 100 cm-1 spectral bandwidth. Using this scheme, we demonstrate a compression of the QCL output from a 134 ps ... More

Evidence of Linear Chirp in Mid-Infrared Quantum Cascade LasersApr 11 2018We measure the inter-modal phase relation of a quantum cascade laser frequency comb operating at 8 um using a coherent beatnote spectroscopy. We find these phases to be reproducible after cycling the power of the device, and to be smoothly varying with ... More

Coexisting frequency combs spaced by an octave in a monolithic quantum cascade laserOct 24 2018Quantum cascade lasers are proving to be instrumental in the development of compact frequency comb sources at mid-infrared and terahertz frequencies. Here we demonstrate a heterogeneous terahertz quantum cascade laser with two active regions spaced exactly ... More

Asymptotic freedom of general relativity and its possible consequencesMay 24 2000The formation of singularities in certain situations, such as the collapse of massive stars, is one of the unresolved issues in classical general relativity. Although no complete theory of quantum gravity exists it is often suggested that quantum gravity ... More

Yang-Mills Inspired Solutions for General RelativityMar 21 1996Several exact, cylindrically symmetric solutions to Einstein's vacuum equations are given. These solutions were found using the connection between Yang-Mills theory and general relativity. Taking known solutions of the Yang-Mills equations (e.g. the topological ... More

Exact Schwarzschild-Like Solution for Yang-Mills TheoriesJan 13 1995Drawing on the parallel between general relativity and Yang-Mills theory we obtain an exact Schwarzschild-like solution for SU(2) gauge fields coupled to a massless scalar field. Pushing the analogy further we speculate that this classical solution to ... More

Infinite Energy Dyon SolutionsFeb 18 1996Three dyon solutions to the SU(2) Yang-Mills-Higgs system are presented. These solutions are obtained from the BPS dyon by allowing the gauge fields to be complex, or by letting the free parameter of the BPS solution become imaginary. In all cases however ... More

Glueball SpinDec 15 1999Apr 02 2001The spin of a glueball is usually taken as coming from the spin (and possibly the orbital angular momentum) of its constituent gluons. In light of the difficulties in accounting for the spin of the proton from its constituent quarks, the spin of glueballs ... More

Topological Electric ChargeJan 10 1997By treating magnetic charge as a gauge symmetry through the introduction of a ``magnetic'' pseudo four-vector potential, it is shown that it is possible, using the 't Hooft-Polyakov construction, to obtain a topological electric charge. The mass of this ... More

Gravitational trapping potential with arbitrary extra dimensionsMar 28 2004Jul 27 2004We extend a recently discovered, non-singular 6 dimensional brane, solution to D=4+n dimensions. As with the previous 6D solution the present solution provides a gravitational trapping mechanism for fields of spin 0, 1/2, 1 and 2. There is an important ... More

Exact Schwarzschild-Like Solution for SU(N) Gauge TheoryJan 20 1995In this paper we extend our previously discovered exact solution for an SU(2) gauge theory coupled to a massless, non-interacting scalar field, to the general group SU(N+1). Using the first-order formalism of Bogomolny, an exact, spherically symmetric ... More

Superconformal quantum mechanics and the exterior algebraMar 19 2014Sep 11 2014We extend the differential form representation of N = (n,n) supersymmetric quantum mechanics to the superconformal case. We identify the superalgebras occurring for n = 1,2,4, give necessary and sufficient conditions for their existence, and give explicit ... More

``Electromagnetic'' Contributrion to the Nucleon SpinOct 01 1997May 25 1998A possible resolution to the question of where the nucleon gets some portion of its internal angular momentum, not carried by the valence quarks, is given in terms of the electromagnetic field angular momentum of the nucleon. This field angular momentum ... More

Can Magnetic Charge and Quantum Mechanics Co-exist ?Apr 05 1997Jun 01 1997It is proven that if more than a single magnetic charge exists it is impossible to define a proper quantum mechanical angular momentum operator for an electrically charged particle in the field of the magnetic charges. Assuming that quantum mechanics ... More

Restrictions on Magnetic Charge from Quantized Angular MomentumJan 18 1997Using the result that an electric charge - magnetic charge system carries an internal field angular momentum of $e g / 4 \pi$ we arrive at two restrictions on magnetic monopoles via the requirement of angular momentum quantization and/or conservation. ... More

Electromagnetism with Magnetic Charge and Two PhotonsJun 08 2011The Dirac approach to include magnetic charge in Maxwell's equations places the magnetic charge at the end of a string on which the the fields of the theory develop a singularity. In this paper an alternative formulation of classical electromagnetism ... More

General relativistic analog solutions for Yang-Mills theoryApr 18 1999Finding solutions to non-linear field theories, such as Yang-Mills theories or general relativity, is usually difficult. The field equations of Yang-Mills theories and general relativity are known to share some mathematical similarities, and this connection ... More

Magnetic Charge as a ``Hidden'' Gauge SymmetryJan 10 1997A theory containing both electric and magnetic charges is formulated using two vector potentials, $A_{\mu}$ and $C_{\mu}$. This has the aesthetic advantage of treating electric and magnetic charges both as gauge charges, but it has the experimental disadvantage ... More

Axially Symmetric Solutions for SU(2) Yang-Mills TheoryFeb 19 1995By casting the Yang-Mills-Higgs equations of an SU(2) theory in the form of the Ernst equations of general relativity, it is shown how the known exact solutions of general relativity can be used to give similiar solutions for Yang-Mills theory. Thus all ... More

Does Magnetic Charge Imply a Massive Photon ?Sep 27 1995In Abelian theories of monopoles the magnetic charge is required to be enormous. Using the electric-magnetic duality of electromagnetism it is argued that the existence of such a large, non-perturbative magnetic coupling should lead to a phase transition ... More

A simple transport model for the temperature-dependent linear magnetoresistance of high-temperature superconductorsOct 03 2018Taken in conjunction with the temperature ($T$) dependence of the zero-field resistivity, a simple transport model invoking realistic variations in charge-carrier density is shown to be sufficient to explain the linear magnetoresistance and field-temperature ... More

A General Relativistic Model for Confinement in SU(2) Yang-Mills TheoryMay 25 1995In this paper we present a model of confinement based on an analogy with the confinement mechanism of the Schwarzschild solution of general relativity. Using recently discovered exact, Schwarzschild-like solutions of the SU(2) Yang-Mills-Higgs equations ... More

Monopole-like Configuration from Quantized SU(3) Gauge FieldsFeb 15 2001Dec 23 2001Monopole field configurations have been extensively studied in both Abelian and non-Abelian gauge theories. The question of the quantum corrections to these systems is a difficult one, since the classical monopoles have non-perturbatively large couplings, ... More

Orbital and field angular momentum in the nucleonJul 03 1998Oct 02 2000The nucleon spin problem raises experimental and theoretical questions regarding the contribution of the orbital angular momentum of the quarks to the total spin of the nucleon. In this article we examine the commutation relationships of various operators ... More

Algorithmic Complexity in Cosmology and Quantum GravityAug 13 2001In this article we use the idea of algorithmic complexity (AC) to study various cosmological scenarios, and as a means of quantizing the gravitational interaction. We look at 5D and 7D cosmological models where the Universe begins as a higher dimensional ... More

Hawking radiation, Unruh radiation and the equivalence principleFeb 28 2011Jul 30 2011We compare the response function of an Unruh-DeWitt detector for different space-times and different vacua and show that there is a {\it detailed} violation of the equivalence principle. In particular comparing the response of an accelerating detector ... More

On the de Haas-van Alphen effect in inhomogeneous alloysMar 23 2001We show that Landau level broadening in alloys occurs naturally as a consequence of random variations in the local quasiparticle density, without the need to consider a relaxation time. This approach predicts Lorentzian-broadened Landau levels similar ... More

Cubic maximal nontraceable graphsJul 16 2004We determine a lower bound for the number of edges of a 2-connected maximal nontraceable graph, and present a construction of an infinite family of maximal nontraceable graphs that realize this bound.

Is a time symmetric interpretation of quantum theory possible without retrocausality?Jul 26 2016Huw Price has proposed an argument that suggests a time-symmetric ontology for quantum theory must necessarily be retrocausal, i.e. it must involve influences that travel backwards in time. One of Price's assumptions is that the quantum state is a state ... More

Totally Asynchronous Distributed Quadratic Programming with Independent Stepsizes and RegularizationsMar 20 2019Quadratic programs arise in robotics, communications, smart grids, and many other applications. As these problems grow in size, finding solutions becomes much more computationally demanding, and new algorithms are needed to efficiently solve them. Targeting ... More

Field-induced canting of magnetic moments in GdCo5 at finite temperature: first-principles calculations and high-field measurementsJul 25 2018We present calculations and experimental measurements of the temperature-dependent magnetization of a single crystal of GdCo$_5$ in magnetic fields of order 60 T. At zero temperature the calculations, based on density-functional theory in the disordered-local-moment ... More

A Unified Model of Phantom Energy and Dark MatterJan 30 2008To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/\rho <-1/3$. This form of mass-energy ... More

The time-dependent Aharonov-Casher effectDec 08 2015In this paper we give a covariant expression for Aharonov-Casher phase. This expression is a combination of the canonical electric field, Aharonov-Casher phase plus a magnetic field phase shift. We use this covariant expression for the Aharonov-Casher ... More

Confining solutions of SU(3) Yang-Mills theoryFeb 11 1999Spherically and cylindrically symmetric solutions of SU(3) Yang-Mills theory are found, whose gauge potentials have confining properties. The spherically symmetric solutions give field distributions which have a spherical surface on which the gauge fields ... More

Gauging dual symmetryJun 29 2001Jan 10 2003The idea of gauging (i.e. making local) symmetries of a physical system is a central feature of many modern field theories. Usually, one starts with a Lagrangian for some scalar or spinor matter fields, with the Lagrangian being invariant under a global ... More

Stokes' theorem, gauge symmetry and the time-dependent Aharonov-Bohm effectDec 05 2013Mar 11 2014Stokes' theorem is investigated in the context of the time-dependent Aharonov-Bohm effect -- the two-slit quantum interference experiment with a time varying solenoid between the slits. The time varying solenoid produces an electric field which leads ... More

Effective 't Hooft-Polyakov monopoles from pure SU(3) gauge theoryJun 22 2003Nov 30 2004The well known topological monopoles originally investigated by 't Hooft and Polyakov are known to arise in classical Yang-Mills-Higgs theory. With a pure gauge theory it is known that the classical Yang-Mills field equation do not have such finite energy ... More

Non-differentiable Degrees of Freedom : Fluctuating Metric SignatureMay 29 2000Feb 01 2001In this article we investigate the metric signature as a non-differentiable ({\it i.e.} discrete as opposed to continuous) degree of freedom. The specific model is a vacuum 7D Universe on the principal bundle with an SU(2) structural group. An analytical ... More

London's Equation from Abelian ProjectionApr 05 2002Confinement in non-Abelian gauge theories, such as QCD, is often explained using an analogy to type II superconductivity. In this analogy the existence of the ``Meissner'' effect for quarks with respect to the QCD vacuum is an important element. Here ... More

Quantization of classical singular solutions in Yang-Mills theoryDec 21 1999In this paper we apply a variant of Heisenberg's quantization method for strongly interacting, non-linear fields, to solutions of the classical Yang-Mills field equations which have bad asymptotic behavior. After quantization we find that the bad features ... More

Experimental test for 5th dimension in Kaluza-Klein gravityNov 30 1999Several electric/magnetic charged solutions (dyons) to 5D Kaluza-Klein gravity on the principal bundle are reviewed. Here we examine the possibility that these solutions can act as quantum virtual wormholes in spacetime foam models. By applying a sufficently ... More

Wormholes and Flux Tubes in Kaluza-Klein TheoryMar 19 1999In this work spherically symmetric solutions to 5D Kaluza-Klein theory, with "electric" and/or "magnetic" fields are examined. Different relative strengths of the "electric" and "magnetic" charges of the solutions are studied by varying certain parameters ... More

Flux Tube Solution in 5D Kaluza-Klein TheoryMay 29 1998Feb 09 1999Spherically symmetric, vacuum solutions in 5D and 7D Kaluza-Klein theory are obtained. These solutions are flux tubes with constant cross-sectional size, located between (+) and (-) Kaluza-Klein's ``electrical'' and ``magnetic'' charges disposed respectively ... More

Phantom energy from graded algebrasMar 20 2006Nov 30 2006We construct a model of phantom energy using the graded Lie algebra SU(2/1). The negative kinetic energy of the phantom field emerges naturally from the graded Lie algebra, resulting in an equation of state with w<-1. The model also contains ordinary ... More

Connecting horizon pixels and interior voxels of a black holeSep 17 2014Oct 03 2014In this paper we discuss to what extent one can infer details of the interior structure of a black hole based on its horizon. Recalling that black hole thermal properties are connected to the non-classical nature of gravity, we circumvent the restrictions ... More

Gravitons to Photons -- attenuation of gravitational wavesMay 19 2015Dec 08 2015In this essay we examine the response of an Unruh-DeWitt detector (a quantum two-level system) to a gravitational wave background. The spectrum of the Unruh-Dewitt detector is of the same form as some scattering processes or three body decays such as ... More

The Planar Sandwich and Other 1D Planar Heat Flow Test Problems in ExactPackJan 25 2017This report documents the implementation of several related 1D heat flow problems in the verification package ExactPack. In particular, the planar sandwich class defined by Dawes et al., as well as the classes PlanarSandwichHot, PlanarSandwichHalf, and ... More

Inferring Concise Specifications of APIsMay 16 2019Modern software relies on libraries and uses them via application programming interfaces (APIs). Correct API usage as well as many software engineering tasks are enabled when APIs have formal specifications. In this work, we analyze the implementation ... More

Industrial Strength Formal Using AbstractionsJun 07 2016Jun 09 2016Verification of concurrent systems with thousands of multiple threads and transactions is a challenging problem not just for simulation or emulation but also for formal. To get designs to work correctly and provide optimal PPA the designers often use ... More

Quasi-two-dimensional organic superconductors: a reviewFeb 25 2002We present a review of quasi-two-dimensional organic superconductors. These systems exhibit many interesting phenomena, including reduced dimensionality, strong electron-electron and electron-phonon interactions and the proximity of antiferromagnetism, ... More

Time dependent electromagnetic fields and 4-dimensional Stokes' theoremAug 24 2016Stokes' theorem is central to many aspects of physics -- electromagnetism, the Aharonov-Bohm effect, and Wilson loops to name a few. However, the pedagogical examples and research work almost exclusively focus on situations where the fields are time-independent ... More

The time-dependent non-Abelian Aharonov-Bohm effectJan 16 2015Apr 08 2015In this article, we study the time-dependent Aharonov-Bohm effect for non-Abelian gauge fields. We use two well known time-dependent solutions to the Yang-Mills field equations to investigate the Aharonov-Bohm phase shift. For both of the solutions, we ... More

Nonsingular Increasing Gravitational Potential for the Brane in 6DOct 06 2003Oct 13 2003We present a new (1+3)-brane solution to Einstein equations in (1+5)-space. As distinct from previous models this solution is free of singularities in the full 6-dimensional space-time. The gravitational potential transverse to the brane is an increasing ... More

Brane in 6D with increasing gravitational trapping potentialMay 27 2003Nov 02 2003A new solution to Einstein equations in (1+5)-spacetime with an embedded (1+3) brane is given. This solution localizes the zero modes of all kinds of matter fields and 4-gravity on the (1+3) brane by an increasing, transverse gravitational potential. ... More

Relativistic polytropic spheres embedded in a chameleon scalar fieldDec 08 2011Apr 02 2012In this paper we investigate gravitationally bound, spherically symmetric equilibrium configurations consisting of ordinary (polytropic) matter nonminimally coupled to an external chameleon scalar field. We show that this system has static, regular, asymptotically ... More

Ginzburg - Landau equation from SU(2) gauge field theoryOct 30 2002The dual superconductor picture of the QCD vacuum is thought to describe various aspects of the strong interaction including confinement. Ordinary superconductivity is described by the Ginzburg-Landau (GL) equation. In the present work we show that it ... More

Quantization of strongly interacting fieldsJun 09 1998While perturbative techniques work extremely well for weakly interacting field theories (e.g. QED), they are not useful when studying strongly interacting field theories (e.g. QCD at low energies). In this paper we review Heisenberg's idea about quantizing ... More

Monopoles in Lattice QCD with Abelian Projection as Quantum MonopolesJan 22 2002Within the context of the Abelian Projection of QCD monopole-like quantum excitations of gauge fields are studied. We start with certain classical solutions, of the SU(2) Yang-Mills field equations, which are not monopole-like and whose energy density ... More

Einstein-Cartan-Heisenberg Theory of Gravity with Dynamical TorsionOct 15 1998Jun 21 1999On the basis of an algebraic relation between torsion and a classical spinor field a new interpretation of Einstein-Cartan gravity interacting with classical spinor field is proposed. In this approach the spinor field becomes an auxiliary field and the ... More

Quantization of spherically symmetric solution of SU(3) Yang-Mills theoryOct 14 1998A recent investigation of the SU(3) Yang-Mills field equations found several classical solutions which exhibited a type of confinement due to gauge fields which increased without bound as $r \to \infty$. This increase of the gauge fields gave these solutions ... More

Electromagnetic field angular momentum in condensed matter systemsSep 05 2000Various electromagnetic systems can carry an angular momentum in their {\bf E} and {\bf B} fields. The electromagnetic field angular momentum (EMAM) of these systems can combine with the spin angular momentum to give composite fermions or composite bosons. ... More

A test of the circular Unruh effect using atomic electronsOct 05 2011Sep 03 2012We propose a test for the circular Unruh effect using certain atoms - fluorine and oxygen. For these atoms the centripetal acceleration of the outer shell electrons implies an effective Unruh temperature in the range 1000 - 2000 K. This range of Unruh ... More

Superconformal Quantum Mechanics and the Discrete Light-Cone Quantisation of N=4 SUSY Yang-MillsSep 30 2014We study the quantum mechanical sigma model arising in the discrete light-cone quantisation of N=4 supersymmetric Yang-Mills theory. The target space is a certain torus fibration over a scale-invariant special Kahler manifold. We show that the expected ... More

An Index for Superconformal Quantum MechanicsDec 31 2018We study quantum mechanical systems with $\mathfrak{osp}(4^{*}|4)$ superconformal symmetry. We classify unitary lowest-weight representations of this superconformal algebra and define an index which receives contributions from short and semi-short multiplets ... More

Lower bound for the size of maximal nontraceable graphsJul 16 2004Let g(n) denote the minimum number of edges of a maximal nontraceable graph of order n. Dudek, Katona and Wojda (2003) showed that g(n)\geq\ceil{(3n-2)/2}-2 for n\geq 20 and g(n)\leq\ceil{(3n-2)/2} for n\geq 54 as well as for n\in I={22,23,30,31,38,39, ... More

Anti-de-Sitter Island-Universes from 5D Standing WavesApr 18 2009May 07 2010We construct simple standing wave solutions in a 5D space-time with a ghost scalar field. The nodes of these standing waves are 'islands' of 4D Minkowski space-time. For the 5D model with increasing (decreasing) warp factor there are a finite (infinite) ... More

Increasing Potentials in Non-Abelian and Abelian Gauge TheoriesSep 10 1995An exact solution for an SU(2) Yang-Mills field coupled to a scalar field is given. This solution has potentials with a linear and Coulomb part. This may have some physical importance since many phenomenological QCD studies assume a linear plus Coulomb ... More

Experimental test for extra dimensions in Kaluza-Klein gravityMay 28 1999Feb 07 20005D Kaluza-Klein gravity has several nonasymptotically flat solutions which generally, possessed both electric and magnetic charges. In this paper we suggest that these solutions can act as quantum virtual handles (wormholes) in spacetime foam models. ... More

Wormholes and Flux Tubes in 5D Kaluza-Klein TheoryJul 31 1998Feb 09 1999In this paper spherically symmetric solutions to 5D Kaluza-Klein theory, with ``electric'' and/or ``magnetic'' fields are investigated. It is shown that the global structure of the spacetime depends on the relation between the ``electrical'' and ``magnetic'' ... More

Global versus Local -- Mach's Principle versus the Equivalence PrincipleJul 06 2016The equivalence principle is the conceptual basis for general relativity. In contrast Mach's principle, although said to have been influential on Einstein in his formulation of general relativity, has not been shown to be central to the structure of general ... More

Fermion generations, masses and mixings in a 6D brane modelFeb 22 2006Apr 21 2006We study the motion of higher dimensional fermions in a non-singular 6D brane background with an increasing warp factor. This background acts as a potential well trapping fermions and fields of other spins near a 3+1 dimensional brane. By adjusting the ... More

Instantons, Integrability and Discrete Light-Cone QuantisationDec 16 2014We study supersymmetric quantum mechanics on the moduli space of Yang-Mills instantons on R^2 x T^2 and its application to the discrete light-cone quantisation (DLCQ) of N=4 SUSY Yang-Mills. In the presence of a target space magnetic field, the model ... More

Dirty Peierls transition to stripe phase in manganitesOct 10 2006The nature of the phase transitions in La$_{1-x}$Ca$_x$MnO$_3$ and Pr$_{0.48}$Ca$_{0.52}$MnO$_3$ has been probed using heat capacity and magnetisation measurements. The phase transition associated with the onset of the stripe phase has been identified ... More

Anomalous quantum oscillations and evidence for a non-trivial Berry phase in SmSbJul 09 2018May 04 2019Topologically non-trivial electronic structures can give rise to a range of unusual physical phenomena, and the interplay of band topology with other effects such as electronic correlations and magnetism requires further exploration. The rare earth monopnictides ... More

Composite Electric $s$-Brane Solutions with Maximal Charge DensitiesJul 29 2005In this paper we consider $(n+1)$-dimensional cosmological model with scalar field and antisymmetric $(p+2)$-form. Using an electric composite $Sp$-brane ansatz the field equations for the original system reduce to the equations for a Toda-like system ... More

Numerical Approaches to High Energy Electroweak Baryon Number Violation Above and Below the Sphaleron BarrierJun 19 1997We review some promising numerical techniques for calculating high energy baryon number violating cross sections in the standard model. As these lectures are designed to be self- contained, we present in some detail the formalism of Rubakov, Son, and ... More

Effect of circular Unruh radiation on bound nucleons and a possible answer to the Lithium 7 puzzleJul 13 2013Aug 07 2013In the shell model of nuclei, protons and neutrons move in a phenomenological nuclear potential much in the same manner as electrons move in Coulomb based potential in the shell model of atoms. As in the atomic case, the protons and neutrons of certain ... More

The Extreme Ends of the Metallicity Distribution in dSph GalaxiesNov 01 2004This paper reviews recent abundance results of local dSph giants. All dSph systems seem to show evidence of slow star formation rates, compared to the Milky Way, based on the most metal-rich stars exhibiting low [even-Z/Fe] ratios and high [s-process/r-process] ... More

v4 for identified particles at RHIC from viscous hydrodynamicsSep 30 2010Using ideal and viscous hydrodynamics, the ratio of azimuthal moments v4/(v2)^2 is calculated for pions, protons, and kaons in sqrt{s}=200 A*GeV Au+Au collisions. For any value of viscosity here is little dependence on particle species. Ideal hydrodynamics ... More

Collective flow and long-range correlations in relativistic heavy ion collisionsNov 26 2010Jan 11 2011Making use of recently released data on dihadron correlations by the STAR collaboration, I analyze the long-range ("ridge-like") part of these data and show that the dependence on both transverse momentum as well as orientation with respect to the event ... More

The Implications of Gunn-Peterson Troughs in the HeII Lyman-alpha ForestMay 05 2009Sep 24 2009Many experts believe that the z ~ 3 HeII Ly-alpha forest will suffer from the same saturation issues as the z ~ 6 HI Ly-alpha forest and, therefore, will not be a sensitive probe of HeII reionization. However, there are several factors that make HeII ... More

Constraints on X-ray Emissions from the Reionization EraJun 06 2012Aug 21 2012We examine the constraints on soft X-ray emissions from the reionization era. It has generally been assumed that the Universe was reionized by ultraviolet photons from massive stars. However, it has been argued that X-ray photons associated with the death ... More

Promising Observational Methods for Detecting the Epoch of ReionizationMar 08 2010Sep 24 2010It has been several years since the first detection of Gunn-Peterson troughs in the z > 6 Ly-alpha forest and since the first measurement of the Thomson scattering optical depth through reionization from the cosmic microwave background (CMB). Present ... More

Quantum Control TheoryJun 20 2014This paper explains some fundamental ideas of {\em feedback} control of quantum systems through the study of a relatively simple two-level system coupled to optical field channels. The model for this system includes both continuous and impulsive dynamics. ... More

Schwarz functions and dualityJul 18 2016Schwarz triangle functions play a fundamental role in the solutions of the generalised Chazy equation. Chazy has shown that for the parameters $k=2$ and $3$, the equations can be linearised. We determine the Schwarz triangle functions that represent the ... More

A Bayesian approach to type-specific conic fittingNov 19 2016A perturbative approach is used to quantify the effect of noise in data points on fitted parameters in a general homogeneous linear model, and the results applied to the case of conic sections. There is an optimal choice of normalisation that minimises ... More

Equivalents of disjunctive Markov's principleNov 08 2016The purpose of this short note is to point out a rich source of natural equivalents of the weak semi-intuitionistic principle MP$^\vee$ in reverse constructive mathematics: many simple theorems from Euclidean geometry when read classically (for example ... More

Constructing the demand function of a strictly convex preference relationNov 08 2016We give conditions under which the demand function of a strictly convex preference relation can be constructed.

Almost all Steiner triple systems have perfect matchingsNov 07 2016We show that for any n divisible by 3, almost all order-n Steiner triple systems have a perfect matching (also known as a parallel class or resolution class). In fact, we prove a general upper bound on the number of perfect matchings in a Steiner triple ... More

The Duffin-Schaeffer theorem in number fieldsOct 24 2016Oct 26 2016The Duffin-Schaeffer theorem is a well-known result from metric number theory, which generalises Khinchin's theorem from monotonic functions to a wider class of approximating functions. In recent years, there has been some interest in proving versions ... More

Ordinary Connectedness Implies Internal Connectedness and Integrability for Lie GroupoidsJun 20 2016Jun 29 2016We generalise some fundamental definitions and constructions in the established multi-object generalisation of Lie theory involving Lie groupoids by reformulating them in terms of groupoids internal to a well-adapted model of synthetic differential geometry. ... More

Weak König's lemma implies the uniform continuity theorem: a direct proofNov 08 2016We show in Bishop's constructive mathematics---in particular, using countable choice---that weak K\"{o}nig's lemma implies the uniform continuity theorem.

Lorentz Violation, Electrodynamics, and the Cosmic Microwave BackgroundApr 01 2008Vacuum birefringence is a signature of Lorentz-symmetry violation. Here we report on a recent search for birefringence in the cosmic microwave background. Polarization data is used to place constraints on certain forms of Lorentz violation.

Constraining Lorentz Violation Using Spectropolarimetry of Cosmological SourcesNov 27 2001Spectropolarimetry of distant sources of electromagnetic radiation at wavelengths ranging from infrared to ultraviolet are used to constrain Lorentz violation. A bound of 3x10^{-32} is placed on coefficients for Lorentz violation.

Experimental determination of $V_{us}$ from kaon decaysNov 19 2014During the last few years, new experimental and theoretical results have allowed ever-more-stringent tests of the Standard Model to be performed using kaon decays. This overview of recent progress includes updated results for the evaluation of the CKM ... More

New Directions in Kaon PhysicsMar 02 2009Recent measurements of kaon decays provide new information about CKM unitarity, lepton universality, and discrete symmetries. KLOE-2, the proposed extension of the kaon physics program at Frascati, will extend the world data set on kaon decays and conduct ... More

Shortfall from Maximum ConvexityOct 04 2015We review the dynamics of the returns of Leveraged Exchange Traded Funds (LETFs) and propose a new measure of realized volatility: Shortfall from Maximum Convexity. We show that SMC has a more intuitive interpretation and provides more statistical information ... More

Hochschild cohomology of $U(\mathfrak{sl}_2(k))$Apr 25 2015We calculate the Hochschild cohomology of $U(\mathfrak{sl}_2(k))$, where $k$ is a field of characteristic $p>2$.

A historical overview of pro cdh descent in algebraic $K$-theory and its relation to rigid analytic varietiesDec 01 2016This note was prepared after the workshop on cdh descent and algebraic $K$-theory in Hara-mura, Japan (1 - 5 Sept. 2016), to complement the author's talk on the history and applications of pro cdh descent. In the final section pro cdh descent is used ... More

Canonical Artin Stacks over Log Smooth SchemesNov 11 2009Jan 08 2013We develop a theory of toric Artin stacks extending the theories of toric Deligne-Mumford stacks developed by Borisov-Chen-Smith, Fantechi-Mann-Nironi, and Iwanari. We also generalize the Chevalley-Shephard-Todd theorem to the case of diagonalizable group ... More