Results for "Matthew J. Hamer"

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Photo-gating Carbon Nanotube TransistorsOct 05 2007Optoelectronic measurements of carbon nanotube transistors have shown a wide variety of sensitivites to the incident light. Direct photocurrent processes compete with a number of extrinsic mechanisms. Here we show that visible light absorption in the ... More
Finite-Size Scaling in the transverse Ising Model on a Square LatticeJul 05 2000Energy eigenvalues and order parameters are calculated by exact diagonalization for the transverse Ising model on square lattices of up to 6x6 sites. Finite-size scaling is used to estimate the critical parameters of the model, confirming universality ... More
The Fate of the Two-Magnon Bound State in the Heisenberg AntiferromagnetApr 27 2009The energy spectrum of the two-magnon bound states in the Heisenberg-Ising antiferromagnet on the square lattice are calculated using series expansion methods. The results confirm an earlier spin-wave prediction of Oguchi and Ishikawa, that the bound ... More
Critical Behaviour of Structure Factors at a Quantum Phase TransitionSep 17 2008We review the theoretical behaviour of the total and one-particle structure factors at a quantum phase transition for temperature T=0. The predictions are compared with exact or numerical results for the transverse Ising model, the alternating Heisenberg ... More
Optical second harmonic generation in encapsulated single-layer InSeAug 17 2018We report the observation of optical second harmonic generation (SHG) in single-layer indium selenide (InSe). We measure a second harmonic signal of $>10^3$ $\textrm{cts/s}$ under nonresonant excitation using a home-built confocal microscope and a standard ... More
The Spin-1 Heisenberg Antiferromagnet: New Results from Series ExpansionsApr 08 2008We calculate ground state properties (energy, magnetization, susceptibility) and one-particle spectra for the $S = 1$ Heisenberg antiferromagnet with easy-axis or easy-plane single site anisotropy, on the square lattice. Series expansions are used, in ... More
The Quantum Compass Model on the Square and Simple Cubic LatticesOct 19 2010We use high-temperature series expansions to obtain thermodynamic properties of the quantum compass model, and to investigate the phase transition on the square and simple cubic lattices. On the square lattice we obtain evidence for a phase transition, ... More
Two-Hole and Four-Hole Bound States in a t-J Ladder at half-fillingApr 24 2002The two-hole excitation spectrum of the t-J ladder at half-filling is studied using linked-cluster series expansion methods. A rich spectrum of bound states emerges, particularly at small $t/J$. Their dispersion relations and coherence lengths are computed, ... More
Two-particle bound states and one-particle structure factor in a Heisenberg bilayer systemJun 04 2008The S=1/2 Heisenberg bilayer spin model at zero temperature is studied in the dimerized phase using analytic triplet-wave expansions and dimer series expansions. The occurrence of two-triplon bound states in the S=0 and S=1 channels, and antibound states ... More
Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube Growth on Silicon Using Thin SiO2 Diffusion BarriersOct 09 2007The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand the range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth ... More
Spin-Wave Theory and Finite-Size Scaling for the Heisenberg AntiferromagnetDec 14 1992Spin-wave perturbation theory for the Heisenberg antiferromagnet at zero temperature is used to compute the finite-lattice corrections to the ground state energy, the staggered magnetization and the energy gap. The dispersion relation, the spin-wave velocity ... More
Meta-Plaquette Expansion for the Triplet Excitation Spectrum in CaV$_4$O$_9$Jul 17 1998We study antiferromagnetic, $S=1/2$ Heisenberg models with nearest and second neighbor interactions on the one-fifth depleted square lattice which describes the spin degrees of freedom in the spin-gap system CaV$_4$O$_9$. The meta-plaquette expansion ... More
Series Expansions for three-dimensional QEDOct 02 1997Strong-coupling series expansions are calculated for the Hamiltonian version of compact lattice electrodynamics in (2+1) dimensions, with 4-component fermions. Series are calculated for the ground-state energy per site, the chiral condensate, and the ... More
The Phase Diagram of the Shastry-Sutherland AntiferromagnetJul 02 2001The Shastry-Sutherland model, which provides a representation of the magnetic properties of SrCu$_2$(BO$_3$)$_2$, has been studied by series expansion methods at T=0. Our results support the existence of an intermediate phase between the N\'eel long-range ... More
Studies of the t-J two-leg ladder via series expansionsSep 19 1999Nov 03 1999Series expansions at T=0 are used to study properties of the half-filled $t-J$ ladder doped with one or two holes, and at quarter filling. Dispersion curves are obtained for one-hole symmetric and antisymmetric (bonding and antibonding) excitations and ... More
Nanometer Resolution Elemental Mapping in Graphene-based TEM Liquid CellsOct 18 2017We demonstrate a new design of graphene liquid cell consisting of a thin lithographically patterned hexagonal boron nitride crystal encapsulated from both sides with graphene windows. The ultra-thin window liquid cells produced have precisely controlled ... More
Series Expansions for the Massive Schwinger Model in Hamiltonian lattice theoryJan 30 1997Feb 04 1997It is shown that detailed and accurate information about the mass spectrum of the massive Schwinger model can be obtained using the technique of strong-coupling series expansions. Extended strong-coupling series for the energy eigenvalues are calculated, ... More
Further Series Studies of the Spin-1/2 Heisenberg Antiferromagnet at T=0: Magnon Dispersion and Structure FactorsDec 08 2004Feb 18 2005We have extended our previous series studies of quantum antiferromagnets at zero temperature by computing the one-magnon dispersion curves and various structure factors for the linear chain, square and simple cubic lattices. Many of these results are ... More
The effect of ozone oxidation on single-walled carbon nanotubesOct 03 2007Exposing single-walled carbon nanotubes to room temperature UV-generated ozone leads to an irreversible increase in their electrical resistance. We demonstrate that the increased resistance is due to ozone oxidation on the sidewalls of the nanotubes rather ... More
Studies of one- and two-hole states in the 2D t-J model via series expansionsJun 30 1998Jul 13 1998We study one and two hole properties of the t-J model at half-filling on the square lattice using series expansion methods at T=0. The dispersion curve for one hole excitations is calculated and found to be qualitatively similar to that obtained by other ... More
A Frustrated 3-Dimensional Antiferromagnet: Stacked $J_{1}-J_{2}$ LayersMar 09 2011We study a frustrated 3D antiferromagnet of stacked $J_1 - J_2$ layers. The intermediate 'quantum spin liquid' phase, present in the 2D case, narrows with increasing interlayer coupling and vanishes at a triple point. Beyond this there is a direct first-order ... More
Various series expansions for a Heisenberg antiferromagnet model for SrCu$_2$(BO$_3$)$_2$Nov 03 1998We use a variety of series expansion methods at both zero and finite temperature to study an antiferromagnetic Heisenberg spin model proposed recently by Miyahara and Ueda for the quasi two-dimensional material SrCu$_2$(BO$_3$)$_2$. We confirm that this ... More
A New Finite-lattice study of the Massive Schwinger ModelNov 16 1999Dec 07 1999A new finite lattice calculation of the low lying bound state energies in the massive Schwinger model is presented, using a Hamiltonian lattice formulation. The results are compared with recent analytic series calculations in the low mass limit, and with ... More
Observing imperfection in atomic interfaces for van der Waals heterostructuresJul 25 2017Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities and defects at the interfaces. ... More
The Coupled Cluster Method in Hamiltonian Lattice Field TheoryMar 30 1996The coupled cluster or exp S form of the eigenvalue problem for lattice Hamiltonian QCD (without quarks) is investigated. A new construction prescription is given for the calculation of the relevant coupled cluster matrix elements with respect to an orthogonal ... More
A modified triplet-wave expansion method applied to the alternating Heisenberg chainMay 30 2006Aug 25 2006An alternative triplet-wave expansion formalism for dimerized spin systems is presented, a modification of the 'bond operator' formalism of Sachdev and Bhatt. Projection operators are used to confine the system to the physical subspace, rather than constraint ... More
Ground state parameters, finite-size scaling, and low-temperature properties of the two-dimensional S=1/2 XY modelApr 15 1999We present high-precision quantum Monte Carlo results for the S=1/2 XY model on a two-dimensional square lattice, in the ground state as well as at finite temperature. The energy, the spin stiffness, the magnetization, and the susceptibility are calculated ... More
Numerical Studies of the two-leg Hubbard ladderJul 25 2000The Hubbard model on a two-leg ladder structure has been studied by a combination of series expansions at T=0 and the density-matrix renormalization group. We report results for the ground state energy $E_0$ and spin-gap $\Delta_s$ at half-filling, as ... More
Green's Function Monte Carlo study of correlation functions in the (2+1)D U(1) lattice gauge theoryFeb 01 2000A ``forward walking'' Quantum Monte Carlo (QMC) algorithm has been developed to calculate correlation functions for the Hamiltonian lattice formulation of U(1) Yang-Mills theory in (2+1) dimensions. It is shown that Wilson loops can be calculated with ... More
Phase diagram of a Heisenberg spin-Peierls model with quantum phononsDec 29 1998May 31 1999Using a new version of the density-matrix renormalization group we determine the phase diagram of a model of an antiferromagnetic Heisenberg spin chain where the spins interact with quantum phonons. A quantum phase transition from a gapless spin-fluid ... More
Phase diagram of the one-dimensional Holstein model of spinless fermionsFeb 20 1998Jun 13 1998The one-dimensional Holstein model of spinless fermions interacting with dispersionless phonons is studied using a new variant of the density matrix renormalisation group. By examining various low-energy excitations of finite chains, the metal-insulator ... More
The t-Jz ladderNov 22 2005The phase diagram of the two-leg t-Jz ladder is explored, using the density matrix renormalization group method. Results are obtained for energy gaps, electron density profiles and correlation functions for the half-filled and quarter-filled cases. The ... More
Spin-S bilayer Heisenberg models: Mean-field arguments and numerical calculationsMay 20 1997Spin-S bilayer Heisenberg models (nearest-neighbor square lattice antiferromagnets in each layer, with antiferromagnetic interlayer couplings) are treated using dimer mean-field theory for general S and high-order expansions about the dimer limit for ... More
Critical Behaviour of One-particle Spectral Weights in the Transverse Ising ModelJul 24 2006We investigate the critical behaviour of the spectral weight of a single quasiparticle, one of the key observables in experiment, for the particular case of the transverse Ising model.Series expansions are calculated for the linear chain and the square ... More
Green's Function Monte Carlo approach to SU(3) Yang-Mills theory in (3+1)DJul 21 2000A 'forward walking' Green's Function Monte Carlo algorithm is used to obtain expectation values for SU(3) lattice Yang-Mills theory in (3+1) dimensions. The ground state energy and Wilson loops are calculated, and the finite-size scaling behaviour is ... More
Density Matrix Renormalisation Group Approach to the Massive Schwinger ModelFeb 11 2002The massive Schwinger model is studied, using a density matrix renormalisation group approach to the staggered lattice Hamiltonian version of the model. Lattice sizes up to 256 sites are calculated, and the estimates in the continuum limit are almost ... More
Infrared-to-violet tunable optical activity in atomic films of GaSe, InSe, and their heterostructuresOct 03 2018Two-dimensional semiconductors - atomic layers of materials with covalent intra-layer bonding and weak (van der Waals or quadrupole) coupling between the layers - are a new class of materials with great potential for optoelectronic applications. Among ... More
Density Matrix Renormalization Group Approach to the Massive Schwinger ModelJan 07 2002The massive Schwinger model is studied, using a density matrix renormalization group approach to the staggered lattice Hamiltonian version of the model. Lattice sizes up to 256 sites are calculated, and the estimates in the continuum limit are almost ... More
Green's Function Monte Carlo study of SU(3) lattice gauge theory in (3+1)DMay 12 2000A `forward walking' Green's Function Monte Carlo algorithm is used to obtain expectation values for SU(3) lattice Yang-Mills theory in (3+1) dimensions. The ground state energy and Wilson loops are calculated, and the finite-size scaling behaviour is ... More
Quantum Phase Diagram and Excitations for the One-Dimensional S=1 Heisenberg Antiferromagnet with Single-Ion AnisotropyNov 05 2008Feb 12 2009We investigate the zero-temperature phase diagram of the one-dimensional S=1 Heisenberg antiferromagnet with single-ion anisotropy. By employing high-order series expansions and quantum Monte Carlo simulations we obtain accurate estimates for the critical ... More
Spectral weight contributions of many-particle bound states and continuumNov 16 2002Cluster expansion methods are developed for calculating the spectral weight contributions of multiparticle excitations - continuum and bound states - to high orders. A complete 11th order calculation is carried out for the alternating Heisenberg chain. ... More
Quantum Monte Carlo study of the one-dimensional Holstein model of spinless fermionsDec 07 1995Jan 31 1996The Holstein model of spinless fermions interacting with dispersionless phonons in one dimension is studied by a Green's function Monte Carlo technique. The ground state energy, first fermionic excited state, density wave correlations, and mean lattice ... More
Niobium diselenide superconducting photodetectorsMar 06 2019We report the photoresponse of niobium diselenide (NbSe$_2$), a transition metal dichalcogenide (TMD) which exhibits superconducting properties down to a single layer. Devices are built by using micro-mechanically cleaved 2 to 10 layers and tested under ... More
Dynamical Structure Factor for the Alternating Heisenberg Chain: A Linked Cluster CalculationJul 22 2003We develop a linked cluster method to calculate the spectral weights of many-particle excitations at zero temperature. The dynamical structure factor is expressed as a sum of exclusive structure factors, each representing contributions from a given set ... More
Universality for SU(2) Yang-Mills Theory in (2+1)DNov 25 1995The Green's Function Monte Carlo method of Chin et al is applied to SU(2) Yang-Mills theory in (2+1)D. Accurate measurements are obtained for the ground-state energy and mean plaquette value, and for various Wilson loops. The results are compared with ... More
Magnon and Hole Excitations in the Two-Dimensional Half-filled Hubbard ModelJan 03 2005Spin and hole excitation spectra and spectral weights are calculated for the half-filled Hubbard model, as a function of $t/U$. We find that the high energy spin spectra are sensitive to charge fluctuations. The energy difference $\Delta(\pi,0)- \Delta(\pi/2,\pi/2)$, ... More
Convergent expansions for properties of the Heisenberg model for CaV$_4$O$_9$Mar 04 1996We have carried out a wide range of calculations for the $S=1/2$ Heisenberg model with nearest- and second-neighbor interactions on a two-dimensional lattice which describes the geometry of the vanadium ions in the spin-gap system CaV$_4$O$_9$. The methods ... More
Order and disorder in the triangular-lattice t-J-V model at 2/3 electron densityMar 30 2004Motivated by the recent discovery of superconductivity in Na$_x$CoO$_2\cdot y$H$_2$O, we use series expansion methods and cluster mean-field theory to study spontaneous charge order, Neel order, ferromagnetic order, dimer order and phase-separation in ... More
Series Expansions for Variable Electron DensityDec 20 2001We have developed a series expansion method for calculating the zero-temperature properties of lattice electron models for variable electron density, i.e. for finite doping away from the half-filled case. This is done by introducing particle fluctuation ... More
The Union Jack model: a quantum spin model with frustration on the square latticeNov 18 2005A new quantum spin model with frustration, the `Union Jack' model on the square lattice, is analyzed using spin-wave theory. For small values of the frustrating coupling $\alpha$, the system is N{\' e}el ordered as usual, while for large $\alpha$ the ... More
Persistent Currents in the Heisenberg chain with a weak linkMay 08 2002May 14 2002The Heisenberg chain with a weak link is studied, as a simple example of a quantum ring with a constriction or defect. The Heisenberg chain is equivalent to a spinless electron gas under a Jordan-Wigner transformation. Using density matrix renormalization ... More
A closer look at symmetry breaking in the collinear phase of the $J_1-J_2$ Heisenberg ModelMar 05 2003The large $J_2$ limit of the square-lattice $J_1-J_2$ Heisenberg antiferromagnet is a classic example of order by disorder where quantum fluctuations select a collinear ground state. Here, we use series expansion methods and a meanfield spin-wave theory ... More
Dimer Order with Striped Correlations in the J_1-J_2 Heisenberg ModelApr 06 1999Ground state energies for plaquette and dimer order in the $J_1-J_2$ square-lattice spin-half Heisenberg model are compared using series expansion methods. We find that these energies are remarkably close to each other at intermediate values of $J_2/J_1$, ... More
Linked Cluster Series Expansions for Two-Particle Bound StatesOct 23 2000We develop strong-coupling series expansion methods to study two-particle spectra of quantum lattice models. At the heart of the method lies the calculation of an effective Hamiltonian in the two-particle subspace. We explicitly consider an orthogonality ... More
Deconfinement Transition and Bound States in Frustrated Heisenberg Chains: Regimes of Forced and Spontaneous DimerizationOct 18 2000Oct 23 2000We use recently developed strong-coupling expansion methods to study the two-particle spectra for the frustrated alternating Heisenberg model, consisting of an alternating nearest neighbor antiferromagnetic exchange and a uniform second neighbor antiferromagnetic ... More
An Application of Feynman-Kleinert Approximants to the Massive Schwinger Model on a LatticeMar 07 2003A trial application of the method of Feynman-Kleinert approximants is made to perturbation series arising in connection with the lattice Schwinger model. In extrapolating the lattice strong-coupling series to the weak-coupling continuum limit, the approximants ... More
Indirect to direct gap crossover in two-dimensional InSe revealed by ARPESJan 21 2019Atomically thin films of III-VI post-transition metal chalcogenides (InSe and GaSe) form an interesting class of two-dimensional semiconductor that feature strong variations of their band gap as a function of the number of layers in the crystal [1-4] ... More
Resonantly hybridised excitons in moiré superlattices in van der Waals heterostructuresApr 12 2019Atomically-thin layers of two-dimensional materials can be assembled in vertical stacks held together by relatively weak van der Waals forces, allowing for coupling between monolayer crystals with incommensurate lattices and arbitrary mutual rotation. ... More
Strong-Coupling Expansions for Multiparticle Excitations: Continuum and Bound StatesJul 11 2000We present a new linked cluster expansion for calculating properties of multiparticle excitation spectra to high orders. We use it to obtain the two-particle spectra for systems of coupled spin-half dimers. We find that even for weakly coupled dimers ... More
Ab-initio modeling of electrolyte molecule Ethylene Carbonate decomposition reaction on Li(Ni,Mn,Co)O2 cathode surfaceJun 19 2017Electrolyte decomposition reactions on Li-ion battery electrodes contribute to the formation of solid electrolyte interphase (SEI) layers. These SEI layers are one of the known causes for the loss in battery voltage and capacity over repeated charge/discharge ... More
Hamiltonian Study of Improved $U(1$ Lattice Gauge Theory in Three DimensionsJul 22 2003Apr 06 2004A comprehensive analysis of the Symanzik improved anisotropic three-dimensional U(1) lattice gauge theory in the Hamiltonian limit is made. Monte Carlo techniques are used to obtain numerical results for the static potential, ratio of the renormalized ... More
Shrinking orbits in hierarchical quadruple star systemsOct 22 2018Nov 06 2018The distribution of the inner orbital periods of solar-type main-sequence (MS) triple star systems is known to be peaked at a few days, and this has been attributed to tidal evolution combined with eccentricity excitation due to Lidov-Kozai oscillations. ... More
On the formation of hot and warm Jupiters via secular high-eccentricity migration in stellar triplesJan 06 2017Hot Jupiters (HJs) are Jupiter-like planets orbiting their host star in tight orbits of a few days. They are commonly believed not to have formed in situ, requiring inwards migration towards the host star. One of the proposed migration scenarios is secular ... More
On the rates of type Ia supernovae originating from white dwarf collisions in quadruple star systemsApr 16 2018We consider the evolution of stellar hierarchical quadruple systems in the 2+2 (two binaries orbiting each other's barycentre) and 3+1 (triple orbited by a fourth star) configurations. In our simulations, we take into account the effects of secular dynamical ... More
Secular dynamics of hierarchical multiple systems composed of nested binaries, with an arbitrary number of bodies and arbitrary hierarchical structure. II. External perturbations: flybys and supernovaeFeb 15 2018We extend the formalism of a previous paper to include the effects of flybys and instantaneous perturbations such as supernovae on the long-term secular evolution of hierarchical multiple systems with an arbitrary number of bodies and hierarchy, provided ... More
Hints for hidden planetary companions to hot Jupiters in stellar binariesJan 16 2017Searches for stellar companions to hot Jupiters (HJs) have revealed that planetary systems hosting a HJ are approximately three times more likely to have a stellar companion with a semimajor axis between 50 and 2000 AU, compared to field stars. This correlation ... More
Phase diagram and magnetocaloric effect of CoMnGe_{1-x}Sn_{x} alloysAug 01 2007We propose the phase diagram of a new pseudo-ternary compound, CoMnGe_{1-x}Sn_{x}, in the range x less than or equal to 0.1. Our phase diagram is a result of magnetic and calometric measurements. We demonstrate the appearance of a hysteretic magnetostructural ... More
High quality factor graphene-based 2D heterostructure mechanical resonatorSep 17 2018Ultralight mechanical resonators based on low-dimensional materials are well suited as exceptional transducers of minuscule forces or mass changes. However, the low dimensionality also provides a challenge to minimize resistive losses and heating. Here, ... More
Observational Constraints on Planet Nine: Astrometry of Pluto and Other Trans-Neptunian ObjectsMar 30 2016We use astrometry of Pluto and other TNOs to constrain the sky location, distance, and mass of the possible additional planet (Planet Nine) hypothesized by Batygin and Brown (2016). We find that over broad regions of the sky, the inclusion of a massive, ... More
Observational Constraints on Planet Nine: Cassini Range ObservationsApr 12 2016We significantly constrain the sky position, distance, and mass of a possible additional, distant planet in the solar system by examining its influence on the distance between Earth and the Cassini Spacecraft. Our preferred region is approximately centered ... More
Hot Jupiters driven by high-eccentricity migration in globular clustersSep 29 2017Nov 29 2017Hot Jupiters (HJs) are short-period giant planets that are observed around ~ 1% of solar-type field stars. One possible formation scenario for HJs is high-eccentricity (high-e) migration, in which the planet forms at much larger radii, is excited to high ... More
Analytic computation of the secular effects of encounters on a binary: third-order perturbation, octupole, and post-Newtonian terms; steady-state distributionJun 20 2019Dense stellar systems such as globular clusters are believed to harbor merging binary black holes (BHs). The evolution of such binaries is driven by interactions with other stars, most notably, binary-single interactions. Traditionally, so-called `strong' ... More
The 8Li Calibration Source for the Sudbury Neutrino ObervatoryFeb 27 2002A calibration source employing 8Li (t_1/2 = 0.838s) has been developed for use with the Sudbury Neutrino Observatory (SNO). This source creates a spectrum of beta particles with an energy range similar to that of the SNO 8B solar neutrino signal. The ... More
On the Phenomenology of Hidden Valleys with Heavy FlavorJun 14 2008A preliminary investigation of a large class of Hidden Valley models is presented. These models are more challenging than those considered in arXiv:0712.2041 [hep-ph]; although they produce a new light resonance which decays to heavy standard model fermions, ... More
On Phases of Gauge Theories and the Role of Non-BPS Solitons in Field TheoryAug 12 1998As shown in hep-th/9709081, non-BPS saturated solitons play an important role in the duality transformations of N=1 supersymmetric gauge theories. In particular, a massive spinor in an SO(N) gauge theory with massless matter in the vector representation ... More
On Renormalization Group Flows and Exactly Marginal Operators in Three DimensionsOct 27 1998As in two and four dimensions, supersymmetric conformal field theories in three dimensions can have exactly marginal operators. These are illustrated in a number of examples with N=4 and N=2 supersymmetry. The N=2 theory of three chiral multiplets X,Y,Z ... More
On Many-Minds Interpretations of Quantum TheoryMar 06 1997Nov 30 1997This paper is a response to some recent discussions of many-minds interpretations in the philosophical literature. After an introduction to the many-minds idea, the complexity of quantum states for macroscopic objects is stressed. Then it is proposed ... More
Algorithms for computing the optimal Lipschitz constant of interpolants with Lipschitz derivativeJul 11 2013Apr 13 2016One classical measure of the quality of an interpolating function is its Lipschitz constant. In this paper we consider interpolants with additional smoothness requirements, in particular that their derivatives be Lipschitz. We show that such a measure ... More
A Composition Formula for Asymptotic MorphismsJun 25 2010For graded $C^*$-algebras $A$ and $B$, we construct a semigroup ${\cal AP}(A,B)$ out of asymptotic pairs. This semigroup is similar to the semigroup $\Psi(A,B)$ of unbounded KK-modules defined by Baaj and Julg and there is a map $\Psi(A,B) \to {\cal AP}(A,B)$ ... More
PHENIX results on system size dependence of J/$ψ$ nuclear modification in $p$,$~d$, $^{3}$He+A collisions at $\sqrt{s_{NN}}$=200 GeVDec 20 2018The dissociation of quarkonia in the medium created in heavy ion collisions is still one of the most debated topics in the heavy ion community. Progress in understanding the effect relies on a broad range of measurements in collisions with different nuclear ... More
Analytic computation of the secular effects of encounters on a binary: features arising from second-order perturbation theoryApr 21 2019Binary-single interactions play a crucial role in the evolution of dense stellar systems such as globular clusters. In addition, they are believed to drive black hole (BH) binary mergers in these systems. A subset of binary-single interactions are secular ... More
Analytic computation of the secular effects of encounters on a binary: features arising from second-order perturbation theoryApr 21 2019Apr 23 2019Binary-single interactions play a crucial role in the evolution of dense stellar systems such as globular clusters. In addition, they are believed to drive black hole (BH) binary mergers in these systems. A subset of binary-single interactions are secular ... More
Analytic computation of the secular effects of encounters on a binary: features arising from second-order perturbation theoryApr 21 2019Jun 11 2019Binary-single interactions play a crucial role in the evolution of dense stellar systems such as globular clusters. In addition, they are believed to drive black hole (BH) binary mergers in these systems. A subset of binary-single interactions are secular ... More
On the Work of Henry P. StappNov 24 2003For many years, Henry Stapp and I have been working separately and independently on mind-centered interpretations of quantum theory. In this review, I discuss his work and contrast it with my own. There is much that we agree on, both in the broad problems ... More
Which quantum theory must be reconciled with gravity? (And what does it mean for black holes?)Jul 13 2016We consider the nature of quantum properties in non-relativistic quantum mechanics (QM) and relativistic QFTs, and examine the connection between formal quantization schemes and intuitive notions of wave-particle duality. Based on the map between classical ... More
Graph CompartmentalizationJul 10 2014Aug 28 2014This article introduces a concept and measure of graph compartmentalization. This new measure allows for principled comparison between graphs of arbitrary structure, unlike existing measures such as graph modularity. The proposed measure is invariant ... More
Simulation of Self-Assembly in the Abstract Tile Assembly Model with ISU TASJan 27 2011Since its introduction by Erik Winfree in 1998, the abstract Tile Assembly Model (aTAM) has inspired a wealth of research. As an abstract model for tile based self-assembly, it has proven to be remarkably powerful and expressive in terms of the structures ... More
Why Unparticle Models with Mass Gaps are Examples of Hidden ValleysJan 04 2008Jan 07 2008Hidden valleys, hidden sectors with multi-particle dynamics and a mass gap, can produce striking and unusual final states at the LHC. Unparticle models, hidden-sectors with conformal dynamics and no (or a very small) mass gap, can result in unusual kinematic ... More
The Duality CascadeMay 17 2005The duality cascade, and its dual description as string theory on the warped deformed conifold, brings together several sophisticated topics, some of which are not widely known. These lectures, which contain a number of previously unpublished results, ... More
Millenial Messages for QCD from the Superworld and from the StringSep 15 2003Supersymmetric gauge theories have had a significant impact on our understanding of QCD and of field theory in general. The phases of N=1 supersymmetric QCD (SQCD) are discussed, and the possibility of similar phases in non-supersymmetric QCD is emphasized. ... More
Non-Supersymmetric Theories with Light Scalar Fields and Large HierarchiesSep 11 2003Various nonsupersymmetric theories at large but finite $N$ are argued to permit light scalars and large hierarchies without fine-tuning. In a dual string description, the hierarchy results from competition between classical and quantum effects. In some ... More
Confining Phase of Three Dimensional Supersymmetric Quantum ElectrodynamicsDec 16 1999Abelian theories in three dimensions can have linearly confining phases as a result of monopole-instantons, as shown, for SU(2) Yang-Mills theory broken to its abelian subgroup, by Polyakov. In this article the generalization of this phase for N=2 supersymmetric ... More
A Counterexample to the Forward Recursion in Fuzzy Critical Path Analysis Under Discrete Fuzzy SetsMay 09 2016Fuzzy logic is an alternate approach for quantifying uncertainty relating to activity duration. The fuzzy version of the backward recursion has been shown to produce results that incorrectly amplify the level of uncertainty. However, the fuzzy version ... More
Compactness of derivations from commutative Banach algebrasOct 30 2009We consider the compactness of derivations from commutative Banach algebras into their dual modules. We show that if there are no compact derivations from a commutative Banach algebra, $A$, into its dual module, then there are no compact derivations from ... More
A Direct Way to Find the Right Key of a Semistandard Young TableauOct 27 2011The right and left key of a semistandard Young tableau were introduced by Lascoux and Schutzenberger in 1990. Most prominently, the right key is a tool used to find Demazure characters for sl(n,C). Previous methods used to compute these keys require introducing ... More
Recent PHENIX Results on Open Heavy FlavorAug 30 2011Throughout the history of the RHIC physics program, questions concerning the dynamics of heavy quarks have generated much experimental and theoretical investigation. A major focus of the PHENIX experiment is the measurement of these quarks through their ... More
QCD, Supersymmetric QCD, Lattice QCD and String Theory: Synthesis on the Horizon?Oct 27 1998Supersymmetric gauge theories in four dimensions have taught us many important physics lessons. These can both inform and be informed by future work on the lattice. I focus on three issues: the properties of supersymmetric Yang-Mills theory and its relation ... More
A Note on Measuring Charm and Bottom Forward-Backward Asymmetries at the TevatronFeb 03 2011The forward-backward asymmetry A_{FB}^t in top quark production at the Tevatron has been seen to be anomalously large both by CDF and D0. Parton-level asymmetries as large as 50%, with a large error bar, have been extracted from the data. It is important ... More
Manifolds of Fixed Points and Duality in Supersymmetric Gauge TheoriesFeb 05 1996There are many physically interesting superconformal gauge theories in four dimensions. In this talk I discuss a common phenomenon in these theories: the existence of continuous families of infrared fixed points. Well-known examples include finite ${\cal ... More
Finitary and Infinitary Mathematics, the Possibility of Possibilities and the Definition of ProbabilitiesJun 30 2003Some relations between physics and finitary and infinitary mathematics are explored in the context of a many-minds interpretation of quantum theory. The analogy between mathematical ``existence'' and physical ``existence'' is considered from the point ... More