Results for "Joss Wiese"

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Strong laser alignment of solvent-solute aggregates in the gas-phaseJan 26 2018Feb 28 2018Strong quasi-adiabatic laser alignment of the indole-water-dimer clusters, an amino-acid chromophore bound to a single water molecule through a hydrogen bond, was experimentally realized. The alignment was visualized through ion and electron imaging following ... More
On modular symbols and the cohomology of Hecke triangle surfacesNov 04 2005Nov 21 2007The aim of this article is to give a concise algebraic treatment of the modular symbols formalism, generalised from modular curves to Hecke triangle surfaces. A sketch is included of how the modular symbols formalism gives rise to the standard algorithms ... More
On the faithfulness of parabolic cohomology as a Hecke module over a finite fieldNov 04 2005Feb 15 2006In this article we prove conditions under which a certain parabolic group cohomology space over a finite field F is a faithful module for the Hecke algebra of Katz modular forms over an algebraic closure of F. These results can e.g. be used to compute ... More
On projective linear groups over finite fields as Galois groups over the rational numbersJun 28 2006Nov 21 2007Ideas and techniques from Khare's and Wintenberger's article on the proof of Serre's conjecture for odd conductors are used to establish that for a fixed prime l infinitely many of the groups PSL_2(F_{l^r}) (for r running) occur as Galois groups over ... More
Computational Arithmetic of Modular Forms (Course notes)Sep 12 2018These course notes are about computing modular forms and some of their arithmetic properties. Their aim is to explain and prove the modular symbols algorithm in as elementary and as explicit terms as possible, and to enable the devoted student to implement ... More
Applying modular Galois representations to the Inverse Galois ProblemFeb 05 2014For many finite groups, the Inverse Galois Problem can be approached through modular/automorphic Galois representations. This is a report explaining the basic strategy, ideas and methods behind some recent results. It focusses mostly on the 2-dimensional ... More
An Application of Maeda's Conjecture to the Inverse Galois ProblemOct 26 2012Oct 03 2013It is shown that Maeda's conjecture on eigenforms of level 1 implies that for every positive even d and every p in a density-one set of primes, the simple group PSL_2(F_{p^d}) occurs as the Galois group of a number field ramifying only at p.
On Galois Representations of Weight OneFeb 11 2011Nov 21 2013A two-dimensional Galois representation into the Hecke algebra of Katz modular forms of weight one over a finite field of characteristic p is constructed and is shown to be unramified at p in most cases.
Dihedral Galois representations and Katz modular formsFeb 10 2004We show that any two-dimensional odd dihedral representation \rho over a finite field of characteristic p>0 of the absolute Galois group of the rational numbers can be obtained from a Katz modular form of level N, character \epsilon and weight k, where ... More
The Status of D-TheoryOct 06 2005Field theories are usually quantized by performing a path integral over configurations of classical fields. This is the case both in perturbation theory and in Wilson's nonperturbative lattice field theory. D-theory is an alternative nonperturbative formulation ... More
Approximation Schemes for Maximum Weight Independent Set of RectanglesJul 06 2013In the Maximum Weight Independent Set of Rectangles (MWISR) problem we are given a set of n axis-parallel rectangles in the 2D-plane, and the goal is to select a maximum weight subset of pairwise non-overlapping rectangles. Due to many applications, e.g. ... More
Strong Secrecy for Multiple Access ChannelsSep 20 2012We show strongly secret achievable rate regions for two different wiretap multiple-access channel coding problems. In the first problem, each encoder has a private message and both together have a common message to transmit. The encoders have entropy-limited ... More
Unramifiedness of Galois representations attached to weight one Hilbert modular eigenforms mod pAug 31 2015May 03 2016The main result of this article states that the Galois representation attached to a Hilbert modular eigenform over F_p^bar of parallel weight one and level prime to p is unramified above p. This includes the important case of eigenforms that do not lift ... More
Bosonization and Cluster Updating of Lattice FermionsOct 16 1992A lattice fermion model is formulated in Fock space using the Jordan-Wigner representation for the fermion creation and annihilation operators. The resulting path integral is a sum over configurations of lattice site occupation numbers $n(x,t) = 0,1$ ... More
Ultracold Quantum Gases and Lattice Systems: Quantum Simulation of Lattice Gauge TheoriesMay 07 2013Abelian and non-Abelian gauge theories are of central importance in many areas of physics. In condensed matter physics, Abelian U(1) lattice gauge theories arise in the description of certain quantum spin liquids. In quantum information theory, Kitaev's ... More
A QPTAS for Maximum Weight Independent Set of Polygons with Polylogarithmically Many VerticesJul 16 2013The Maximum Weight Independent Set of Polygons problem is a fundamental problem in computational geometry. Given a set of weighted polygons in the 2-dimensional plane, the goal is to find a set of pairwise non-overlapping polygons with maximum total weight. ... More
Irregular Sampling of the Radon Transform of Bandlimited FunctionsJul 03 2013We provide conditions for exact reconstruction of a bandlimited function from irregular polar samples of its Radon transform. First, we prove that the Radon transform is a continuous L2-operator for certain classes of bandlimited signals. We then show ... More
Coherent-state path integral versus coarse-grained effective stochastic equation of motion: From reaction diffusion to stochastic sandpilesJan 26 2015Mar 25 2016We derive and study two different formalisms used for non-equilibrium processes: The coherent-state path integral, and an effective, coarse-grained stochastic equation of motion. We first study the coherent-state path integral and the corresponding field ... More
Disordered Systems and the Functional Renormalization Group: A Pedagogical IntroductionMay 07 2002In this article, we review basic facts about disordered systems, especially the existence of many metastable states and and the resulting failure of dimensional reduction. Besides techniques based on the Gaussian variational method and replica-symmetry ... More
Principles of non-local field theories and their application to polymerized membranesJun 19 2001In these lecture notes, we give an overview about non-local field-theories and their application to polymerized membranes, i.e. membranes with a fixed internal connectivity. The main technical tool is the multi-local operator product expansion (MOPE), ... More
The passive polymer problemNov 01 1999Jul 07 2000In this article, we introduce a generalization of the diffusive motion of point-particles in a turbulent convective flow with given correlations to a polymer or membrane. In analogy to the passive scalar problem we call this the passive polymer or membrane ... More
The Arbitrarily Varying Multiple-Access Channel with Conferencing EncodersMay 02 2011Nov 13 2012We derive the capacity region of arbitrarily varying multiple-access channels with conferencing encoders for both deterministic and random coding. For a complete description it is sufficient that one conferencing capacity is positive. We obtain a dichotomy: ... More
On Modular Forms and the Inverse Galois ProblemMay 08 2009In this article new cases of the Inverse Galois Problem are established. The main result is that for a fixed integer n, there is a positive density set of primes p such that PSL_2(F_{p^n}) occurs as the Galois group of some finite extension of the rational ... More
On the Configuration-LP for Scheduling on Unrelated MachinesNov 22 2010One of the most important open problems in machine scheduling is the problem of scheduling a set of jobs on unrelated machines to minimize the makespan. The best known approximation algorithm for this problem guarantees an approximation factor of 2. It ... More
Quantum Spins and Quantum Links: The D-Theory Approach to Field TheoryNov 19 1998A new non-perturbative approach to quantum field theory is proposed. Instead of performing a path integral over configurations of classical fields, D-theory works with discrete quantized variables. Classical spin fields are replaced by quantum spins, ... More
Towards Quantum Simulating QCDSep 25 2014Quantum link models provide an alternative non-perturbative formulation of Abelian and non-Abelian lattice gauge theories. They are ideally suited for quantum simulation, for example, using ultracold atoms in an optical lattice. This holds the promise ... More
Supersymmetry Breaking in Disordered Systems and Relation to Functional Renormalization and Replica-Symmetry BreakingNov 25 2004Jan 24 2005In this article, we study an elastic manifold in quenched disorder in the limit of zero temperature. Naively it is equivalent to a free theory with elasticity in Fourier-space proportional to k^4 instead of k^2, i.e. a model without disorder in two space-dimensions ... More
The Functional Renormalization Group Treatment of Disordered Systems: a ReviewFeb 17 2003We review current progress in the functional renormalization group treatment of disordered systems. After an elementary introduction into the phenomenology, we show why in the context of disordered systems a functional renormalization group treatment ... More
Dynamics of Selfavoiding Tethered Membranes II, Inclusion of Hydrodynamic Interaction (Zimm Model)Feb 03 1997The dynamical scaling properties of selfavoiding polymerized membranes with internal dimension D embedded into d dimensions are studied including hydrodynamical interactions. It is shown that the theory is renormalizable to all orders in perturbation ... More
Why one needs a functional renormalization group to survive in a disordered worldNov 22 2005In these proceedings, we discuss why functional renormalization is an essential tool to treat strongly disordered systems. More specifically, we treat elastic manifolds in a disordered environment. These are governed by a disorder distribution, which ... More
Capillary Waves in Binder's Approach to the Interface TensionSep 03 1992In Binder's approach the reduced interface tension sigma of the Ising model in the broken phase is determined from the finite volume effects of the partition function Z(M) at fixed total magnetization M. For small |M| the partition function of a system ... More
Scheduling Meets Fixed-Parameter TractabilityNov 16 2013Fixed-parameter tractability analysis and scheduling are two core domains of combinatorial optimization which led to deep understanding of many important algorithmic questions. However, even though fixed-parameter algorithms are appealing for many reasons, ... More
Dynamical Selection of Critical ExponentsFeb 01 2016Mar 25 2016In renormalized field theories there are in general one or few fixed points which are accessible by the renormalization-group flow. They can be identified from the fixed-point equations. Exceptionally, an infinite family of fixed points exists, parameterized ... More
Scheduling Unrelated Machines of Few Different TypesMay 04 2012A very well-known machine model in scheduling allows the machines to be unrelated, modelling jobs that might have different characteristics on each machine. Due to its generality, many optimization problems of this form are very difficult to tackle and ... More
Span observables - "When is a foraging rabbit no longer hungry?"Mar 13 2019Be $X_t$ a random walk. We study its span $S$, i.e. the size of the domain visited up to time $t$. We want to know the probability that $S$ reaches $1$ for the first time, as well as the density of the span given $t$. Analytical results are presented, ... More
Unramifiedness of Galois representations attached to weight one Hilbert modular eigenforms mod pAug 31 2015Nov 28 2017The main result of this article states that the Galois representation attached to a Hilbert modular eigenform defined over F_p^bar of parallel weight 1 and level prime to p is unramified above p. This includes the important case of eigenforms that do ... More
Multiplicities of Galois representations of weight one (with an appendix by Niko Naumann)Dec 12 2006In this article we consider mod p modular Galois representations which are unramified at p such that the Frobenius element at p acts through a scalar matrix. The principal result states that the multiplicity of any such representation is bigger than 1. ... More
Topics on modular Galois representations modulo prime powersDec 15 2016Jul 03 2017This article surveys modularity, level raising and level lowering questions for two-dimensional representations modulo prime powers of the absolute Galois group of the rational numbers. It contributes some new results and describes algorithms and a database ... More
The Hector Survey: integral field spectroscopy of 100,000 galaxiesOct 14 2014In March 2013, the Sydney--AAO Multi-object Integral field spectrograph (SAMI) began a major survey of 3400 galaxies at the AAT, the largest of its kind to date. At the time of writing, over a third of the targets have been observed and the scientific ... More
Strong-field photoelectron momentum imaging of OCS at finely resolved incident intensitiesApr 16 2019Photoelectron momentum distributions from strong-field ionization of carbonyl sulfide with 800 nm central-wavelength laser pulses at various peak intensities from $4.6$ to $13\times10^{13}$ W/cm$^2$ were recorded and analyzed regarding resonant Rydberg ... More
Frequency hopping does not increase anti-jamming resilience of wireless channelsDec 21 2015The effectiveness of frequency hopping for anti-jamming protection of wireless channels is analyzed from an information-theoretic perspective. The sender can input its symbols into one of several frequency subbands at a time. Each subband channel is modeled ... More
This House Proves that Debating is Harder than SoccerMay 10 2016During the last twenty years, a lot of research was conducted on the sport elimination problem: Given a sports league and its remaining matches, we have to decide whether a given team can still possibly win the competition, i.e., place first in the league ... More
Dynamics of Selfavoiding Tethered Membranes I Model A Dynamics (Rouse Model)Feb 03 1997Oct 20 1997The dynamical scaling properties of selfavoiding polymerized membranes with internal dimension D are studied using model A dynamics. It is shown that the theory is renormalizable to all orders in perturbation theory and that the dynamical scaling exponent ... More
Classification of Perturbations for Membranes with Bending RigidityJul 26 1996A complete classification of the renormalization-group flow is given for impurity-like marginal operators of membranes whose elastic stress scales like (\Delta r)^2 around the external critical dimension d_c=2. These operators are classified by characteristic ... More
On the Perturbation Expansion of the KPZ-EquationFeb 06 1998Jul 06 1998We present a simple argument to show that the beta-function of the d-dimensional KPZ-equation (d>=2) is to all orders in perturbation theory given by beta(g) = (d-2) g - 2/(8 pi)^(d/2) Gamma(2-d/2) g^2 . Neither the dynamical exponent z nor the roughness-exponent ... More
A Short Note on the Bruinier-Kohnen Sign Equidistribution Conjecture and Halász' TheoremAug 10 2014Mar 30 2015In this note, we improve earlier results towards the Bruinier-Kohnen sign equidistribution conjecture for half-integral weight modular eigenforms in terms of natural density by using a consequence of Hal\'asz' Theorem. Moreover, applying a result of Serre ... More
Equidistribution of Signs for Modular Eigenforms of Half Integral WeightOct 08 2012Sep 24 2013Let f be a cusp form of weight k+1/2 and at most quadratic nebentype character whose Fourier coefficients a(n) are all real. We study an equidistribution conjecture of Bruinier and Kohnen for the signs of a(n). We prove this conjecture for certain subfamilies ... More
Phase Bifurcations of Strongly Correlated Electron Gas at the Conditions of dHvA EffectOct 22 2007In a framework of catastrophe theory we investigate the equilibrium set for the system of strongly correlated electron gas at the conditions of dHvA effect and show that the discontinuities accompanied the diamagnetic phase transition (DPT) is handled ... More
Temperature and Magnetic Field Dependencies of Condon Domain Phase in Lifschitz-Kosevich-Shoenberg ApproximationOct 26 2006The temperature and magnetic field behavior of non-uniform diamagnetic phase of strongly correlated electron gas at the conditions of dHvA effect is analyzed. It is shown, that in the framework of Lifschitz-Kosevich-Shoenberg approximation the magnetic ... More
Temperature and Magnetic Field Dependencies in a Model of Diamagnetic Hysteresis in BerylliumOct 26 2006The model of diamagnetic hysteresis loop of strongly correlated electron gas at the conditions of dHvA effect is developed. It is shown, that in the framework of Rayleigh theory for magnetization loop, the coercive force and remnant magnetization in every ... More
Diamagnetic Phase Transition and Phase Diagrams in BerylliumOct 25 2006The model of diamagnetic phase transition in beryllium which takes into account the quasi 2-dimensional shape of the Fermi surface of beryllium is proposed. It explains correctly the recent experimental data on observation of non-homogeneous phase in ... More
Morphology of Condon Domains Phase in Plate-Like SampleOct 22 2007Based on Shoenberg assumption of magnetic flux density dependence of diamagnetic moments which accounts for an instability of strongly correlated electron gas at the conditions of dHvA effect and diamagnetic phase transition (DPT) to non-uniform phase, ... More
Diamagnetic Length-Scales of Condon Domain Phase in Lifschitz-Kosevich-Shoenberg ApproximationSep 13 2009Equilibrium properties of non-uniform diamagnetic phase in normal metals (Condon domains) are studied theoretically in the framework of Lifschitz-Kosevich-Shoenberg (LKS) approximation. It is found that characteristic diamagnetic lengths of the phase, ... More
Quantum Spin Formulation of the Principal Chiral ModelMay 25 2000We formulate the two-dimensional principal chiral model as a quantum spin model, replacing the classical fields by quantum operators acting in a Hilbert space, and introducing an additional, Euclidean time dimension. Using coherent state path integral ... More
Perfect Lattice Actions for Quarks and GluonsOct 16 1995Oct 23 1995We use perturbation theory to construct perfect lattice actions for quarks and gluons. The renormalized trajectory for free massive quarks is identified by blocking directly from the continuum. We tune a parameter in the renormalization group transformation ... More
A Perturbative Construction of Lattice Chiral FermionsMar 23 1995We perform a renormalization group transformation to construct a lattice theory of chiral fermions. The field variables of the continuum theory are averaged over hypercubes to define lattice fields. Integrating out the continuum variables in perturbation ... More
Quark Confinement in C-periodic Cylinders at Temperatures above T_cFeb 13 1997Due to the Gauss law, a single quark cannot exist in a periodic volume, while it can exist with C-periodic boundary conditions. In a C-periodic cylinder of cross section A = L_x L_y and length L_z >> L_x, L_y containing deconfined gluons, regions of different ... More
Partition Functions of Strongly Correlated Electron Systems as "Fermionants"Aug 11 2011We introduce a new mathematical object, the "fermionant" ${\mathrm{Ferm}}_N(G)$, of type $N$ of an $n \times n$ matrix $G$. It represents certain $n$-point functions involving $N$ species of free fermions. When N=1, the fermionant reduces to the determinant. ... More
SO(10) Unification of Color Superconductivity and Chiral Symmetry Breaking?Mar 22 2000Motivated by the SO(5) theory of high-temperature superconductivity and antiferromagnetism, we ask if an SO(10) theory unifies color superconductivity and chiral symmetry breaking in QCD. The transition to the color superconducting phase would then be ... More
A geometric generalization of field theory to manifolds of arbitrary dimensionMar 23 1998We introduce a generalization of the O(N) field theory to N-colored membranes of arbitrary inner dimension D. The O(N) model is obtained for D->1, while N->0 leads to self-avoiding tethered membranes (as the O(N) model reduces to self-avoiding polymers). ... More
Perfect Lattice Actions with and without Chiral SymmetrySep 15 1995Sep 22 1995We use perturbation theory to construct perfect lattice actions for fermions and gauge fields by blocking directly from the continuum. When one uses a renormalization group transformation that preserves chiral symmetry the resulting lattice action for ... More
The Center symmetry and its spontaneous breakdown at high temperaturesNov 15 2000We examine the role of the center Z(N) of the gauge group SU(N) in gauge theories. In this pedagogical article, we discuss, among other topics, the center symmetry and confinement and deconfinement in gauge theories and associated finite-temperature phase ... More
An Introduction to Chiral Symmetry on the LatticeMay 26 2004The $SU(N_f)_L \otimes SU(N_f)_R$ chiral symmetry of QCD is of central importance for the nonperturbative low-energy dynamics of light quarks and gluons. Lattice field theory provides a theoretical framework in which these dynamics can be studied from ... More
Systematic Field Theory of the RNA Glass TransitionJul 25 2006We prove that the Laessig-Wiese (LW) field theory for the freezing transition of the secondary structure of random RNA is renormalizable to all orders in perturbation theory. The proof relies on a formulation of the model in terms of random walks and ... More
Self-avoiding Tethered Membranes at the Tricritical PointMar 23 1995The scaling properties of self-avoiding tethered membranes at the tricritical point (theta-point) are studied by perturbative renormalization group methods. To treat the 3-body repulsive interaction (known to be relevant for polymers), new analytical ... More
Lattice Fluid Dynamics from Perfect Discretizations of Continuum FlowsSep 12 1997Jul 22 1998We use renormalization group methods to derive equations of motion for large scale variables in fluid dynamics. The large scale variables are averages of the underlying continuum variables over cubic volumes, and naturally live on a lattice. The resulting ... More
Perturbative Linearization of Reaction-Diffusion EquationsSep 23 2002We develop perturbative expansions to obtain solutions for the initial-value problems of two important reaction-diffusion systems, viz., the Fisher equation and the time-dependent Ginzburg-Landau (TDGL) equation. The starting point of our expansion is ... More
Dihedral Universal DeformationsMay 14 2018This article deals with universal deformations of dihedral representations with a particular focus on the question when the universal deformation is dihedral. Results are obtained in three settings: (1) representation theory, (2) algebraic number theory, ... More
Dihedral Universal DeformationsMay 14 2018Apr 26 2019This article deals with universal deformations of dihedral representations with a particular focus on the question when the universal deformation is dihedral. Results are obtained in three settings: (1) representation theory, (2) algebraic number theory, ... More
Fixed Point Actions for Lattice FermionsNov 16 1993The fixed point actions for Wilson and staggered lattice fermions are determined by iterating renormalization group transformations. In both cases a line of fixed points is found. Some points have very local fixed point actions. They can be used to construct ... More
Low-Energy Effective Theories of Quantum Link and Quantum Spin ModelsDec 11 2000Quantum spin and quantum link models provide an unconventional regularization of field theory in which classical fields arise via dimensional reduction of discrete variables. This D-theory regularization leads to the same continuum theories as the conventional ... More
Perfect Actions with Chemical PotentialJan 19 1998We show how to include a chemical potential \mu in perfect lattice actions. It turns out that the standard procedure of multiplying the quark fields \Psi, \bar\Psi at Euclidean time t by \exp(\pm \mu t), respectively, is perfect. As an example, the case ... More
Fixed Point Actions for Wilson FermionsJun 03 1993Iterating renormalization group transformations for lattice fermions the Wilson action is driven to fixed points of the renormalization group. A line of fixed points is found and the fixed point actions are computed analytically. They are local and may ... More
Meron-Cluster Solution of Fermion Sign ProblemsFeb 10 1999Oct 11 1999We present a general strategy to solve the notorious fermion sign problem using cluster algorithms. The method applies to various systems in the Hubbard model family as well as to relativistic fermions. Here it is illustrated for non-relativistic lattice ... More
Large Orders for Self-Avoiding MembranesJul 10 1998We derive the large order behavior of the perturbative expansion for the continuous model of tethered self-avoiding membranes. It is controlled by a classical configuration for an effective potential in bulk space, which is the analog of the Lipatov instanton, ... More
Generalizing the O(N)-field theory to N-colored manifolds of arbitrary internal dimension DMar 31 1998We introduce a geometric generalization of the O(N)-field theory that describes N-colored membranes with arbitrary dimension D. As the O(N)-model reduces in the limit N->0 to self-avoiding polymers, the N-colored manifold model leads to self-avoiding ... More
Perturbative Expansion for the Maximum of Fractional Brownian MotionMar 02 2016Brownian motion is the only random process which is Gaussian, stationary and Markovian. Dropping the Markovian property, i.e. allowing for memory, one obtains a class of processes called fractional Brownian motion, indexed by the Hurst exponent $H$. For ... More
The Maximum of a Fractional Brownian Motion: Analytic Results from Perturbation TheoryJul 22 2015Fractional Brownian motion is a non-Markovian Gaussian process $X_t$, indexed by the Hurst exponent $H$. It generalises standard Brownian motion (corresponding to $H=1/2$). We study the probability distribution of the maximum $m$ of the process and the ... More
Computational complexity and fundamental limitations to fermionic quantum Monte Carlo simulationsAug 16 2004Quantum Monte Carlo simulations, while being efficient for bosons, suffer from the "negative sign problem'' when applied to fermions - causing an exponential increase of the computing time with the number of particles. A polynomial time solution to the ... More
Quantum Link Models: A Discrete Approach to Gauge TheoriesSep 26 1996Dec 31 1996We construct lattice gauge theories in which the elements of the link matrices are represented by non-commuting operators acting in a Hilbert space. These quantum link models are related to ordinary lattice gauge theories in the same way as quantum spin ... More
Field Theory of the RNA Freezing TransitionJun 08 2009Jun 16 2009Folding of RNA is subject to a competition between entropy, relevant at high temperatures, and the random, or random looking, sequence, determining the low- temperature phase. It is known from numerical simulations that for random as well as biological ... More
Scaling of Selfavoiding Tethered Membranes: 2-Loop Renormalization Group ResultsFeb 23 1996The scaling properties of selfavoiding polymerized membranes are studied using renormalization group methods. The scaling exponent \nu is calculated for the first time at two loop order. \nu is found to agree with the Gaussian variational estimate for ... More
Instanton calculus for the self-avoiding manifold modelSep 30 2004Mar 28 2005We compute the normalisation factor for the large order asymptotics of perturbation theory for the self-avoiding manifold (SAM) model describing flexible tethered (D-dimensional) membranes in d-dimensional space, and the epsilon-expansion for this problem. ... More
Field Theory of Disordered Elastic Interfaces at 3-Loop Order: Critical Exponents and Scaling FunctionsJul 31 2017Jul 20 2018For disordered elastic manifolds in the ground state (equilibrium) we obtain the critical exponents for the roughness and the correction-to-scaling up to 3-loop order, i.e. third order in $\epsilon=4-d$, where $d$ is the internal dimension $d$. We also ... More
The Epoch of Assembly of Two Galaxy Groups: A comparative studyAug 02 2013Nearby galaxy groups of comparable mass to the Local Group show global variations that reflect differences in their evolutionary history. Satellite galaxies in groups have higher levels of gas deficiency as the distance to their host decreases. The well ... More
Gas depletion in Local Group dwarfs on ~250 kpc scales: Ram pressure stripping assisted by internal heating at early timesFeb 23 2011A recent survey of the Galaxy and M31 reveals that more than 90% of dwarf galaxies within 270 kpc of their host galaxy are deficient in HI gas. At such an extreme radius, the coronal halo gas is an order of magnitude too low to remove HI gas through ram-pressure ... More
Galactic History: Formation and EvolutionOct 23 2006We explore the motivation behind large stellar surveys in Galactic astronomy, in particular, surveys that measure the photometric, phase space and abundance properties of thousands or millions of stars. These observations are essential to unravelling ... More
The New Galaxy: Signatures of its FormationAug 06 2002The formation and evolution of galaxies is one of the great outstanding problems of astrophysics. Within the broad context of hierachical structure formation, we have only a crude picture of how galaxies like our own came into existence. A detailed physical ... More
Galaxies: The Third Dimension -- Conference SummaryJun 14 2002``Galaxies: the Third Dimension'' continues a tradition which started in Marseilles 1994 with the ``Tridimensional Optical Spectroscopic Methods in Astrophysics'' meeting, followed by ``Imaging the Universe in Three Dimensions'' at Walnut Creek in 1999. ... More
The Galaxy in Context: Structural, Kinematic and Integrated PropertiesFeb 24 2016Jan 05 2017Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies. It is the only galaxy whose formation history can be studied using the full distribution of stars from white dwarfs to supergiants. The oldest components provide us with unique ... More
An empirical formula for the distribution function of a thin exponential discJun 27 2013An empirical formula for a Shu distribution function that reproduces a thin disc with exponential surface density to good accuracy is presented. The formula has two free parameters that specify the functional form of the velocity dispersion. Conventionally, ... More
From Decay to Complete Breaking: Pulling the Strings in SU(2) Yang-Mills TheoryJan 16 2009We study {2Q+1}-strings connecting two static charges Q in (2+1)-d SU(2) Yang-Mills theory. While the fundamental {2}-string between two charges Q = 1/2 is unbreakable, the adjoint {3}-string connecting two charges Q = 1 can break. When a {4}-string is ... More
Exceptional Deconfinement in G(2) Gauge TheoryOct 12 2006The Z(N) center symmetry plays an important role in the deconfinement phase transition of SU(N) Yang-Mills theory at finite temperature. The exceptional group G(2) is the smallest simply connected gauge group with a trivial center. Hence, there is no ... More
The decay of unstable strings in SU(2) Yang-Mills theoryOct 19 2009We investigate the stability of strings connecting charges Q in the representation {2Q+1} of SU(2) Yang-Mills theory in (2+1) dimensions. While the fundamental {2}-string between two charges Q=1/2 is unbreakable and stable, the string connecting static ... More
Quark Confinement in the Deconfined PhaseJan 23 1998In cylindrical volumes with C-periodic boundary conditions in the long direction, static quarks are confined even in the gluon plasma phase due to the presence of interfaces separating the three distinct high-temperature phases. An effective "string tension" ... More
The Freezing of Random RNANov 16 2005Apr 18 2006We study secondary structures of random RNA molecules by means of a renormalized field theory based on an expansion in the sequence disorder. We show that there is a continuous phase transition from a molten phase at higher temperatures to a low-temperature ... More
New Renormalization Group Results for Scaling of Self-Avoiding Tethered MembranesJul 26 1996The scaling properties of self-avoiding polymerized 2-dimensional membranes are studied via renormalization group methods based on a multilocal operator product expansion. The renormalization group functions are calculated to second order. This yields ... More
Extreme-Value Statistics of Fractional Brownian Motion BridgesMay 13 2016Fractional Brownian motion is a self-affine, non-Markovian and translationally invariant generalization of Brownian motion, depending on the Hurst exponent $H$. Here we investigate fractional Brownian motion where both the starting and the end point are ... More
Student project: Of spinning coins and merging black holesOct 31 2016For the past decade, the SAIL labs at the University of Sydney have been challenging students with short research projects that elucidate basic principles of physics. These include the development of instruments launched on cubesats, balloons, on telescopes ... More
The Galaxy in Context: Structural, Kinematic and Integrated PropertiesFeb 24 2016Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies. It is the only galaxy whose formation history can be studied using the full distribution of stars from white dwarfs to supergiants. The oldest components provide us with unique ... More