Physics Commons^™

Sum Rule For The Adm Mass And Tensions In Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen

David Kastor

An asymptotically planar AdS spacetimes is characterized by its ADM mass and tensions. We define an additional ADM charge Q associated with the scaling Killing vector of AdS, show that Q is given by a certain sum over the ADM mass and tensions and that Q vanishes on solutions to the Einstein equation with negative cosmological constant. The sum rule for the mass and tensions thus established corresponds in an AdS/CFT context to the vanishing of the trace of the boundary stress tensor. We also show that an analogous sum rule holds for local planar sources of stress-energy sources in …

Conformal Tensors Via Lovelock Gravity, David Kastor

David Kastor

Constructs from conformal geometry are important in low dimensional gravity models, while in higher dimensions the higher curvature interactions of Lovelock gravity are similarly prominent. Considering conformal invariance in the context of Lovelock gravity leads to natural, higher-curvature generalizations of the Weyl, Schouten, Cotton and Bach tensors, with properties that straightforwardly extend those of their familiar counterparts. As a first application, we introduce a new set of conformally invariant gravity theories in D=4k dimensions, based on the squares of the higher curvature Weyl tensors.

Gravitational Wave Production Through Decay Of The Inflaton Into Intermediary Fields During Slow Roll Inflation, Jessica Lauren Cook

Open Access Dissertations

This dissertation looks for possible observable signals of tensor metric perturbations sourced during slow roll inflation from decay of the inflaton field into other intermediary fields. We focus on two main scenarios, one of explosive production of intermediary fields for a short period during inflation and another of prolonged production of vectors due to a derivative coupling of the vectors with the inflaton field. We only find a possible observable signal of tensor perturbations in the second case.

Conditional Gaussian Fluctuations And Refined Asymptotics Of The Spin In The Phase-Coexistence Region, Jingran Li

Open Access Dissertations

In this dissertation four results are presented on the fluctuations of the spin per site around the thermodynamic magnetization in the mean-field Blume-Capel model, a basic model in statistical mechanics. The first two results refine the main theorem in a 2010 paper by R. S. Ellis, J. Machta, and P. T. Otto published in Annals of Applied Probability 20 (2010) 2118-2161. This paper provides the first rigorous confirmation of the statistical mechanical theory of finite-size scaling for a mean-field model. The first main result studies the asymptotics of the centered, finite-size magnetization, giving its precise rate of convergence to 0 …

Replica Exchange Monte Carlo Simulations Of The Ising Spin Glass: Static And Dynamic Properties, Burcu Yucesoy

Open Access Dissertations

Spin glasses have been the subject of intense study and considerable controversy for decades, and the low-temperature phase of short-range spin glasses is still poorly understood. Our main goal is to improve our understanding in this area and find an answer to the following question: Are there only a single pair or a countable infinity of pure states in the low temperature phase of the EA spin glass? To that aim we first start by introducing spin glasses and provide a brief history of their research, then proceed to describe our method of simulation, the parallel tempering Monte Carlo algorithm. …

Self-Assembly On A Cylinder: A Model System For Understanding The Constrain Of Commensurability, D. A. Wood, Christian Santangelo, A. D. Dinsmore

Christian Santangelo

A crystal lattice, when confined to the surface of a cylinder, must have a periodic structure that is commensurate with the cylinder circumference. This constraint can frustrate the system, leading to oblique crystal lattices or to structures with a chiral seam known as a ‘line slip’ phase, neither of which is stable for isotropic particles in equilibrium on flat surfaces. In this study, we use molecular dynamics simulations to find the steady-state structure of spherical particles with short-range repulsion and long-range attraction far below the melting temperature. We vary the range of attraction using the Lennard-Jones and Morse potentials and …

On The Universality Of Inner Black Hole Mechanics And Higher Curvature Gravity, Alejandra Castro, Nima Dehmami, Gaston Giribet, David Kastor

David Kastor

Black holes are famous for their universal behavior. New thermodynamic relations have been found recently for the product of gravitational entropies over all the horizons of a given stationary black hole. This product has been found to be independent of the mass for all such solutions of Einstein-Maxwell theory in d=4,5. We study the universality of this mass independence by introducing a number of possible higher curvature corrections to the gravitational action. We consider finite temperature black holes with both asymptotically flat and (A)dS boundary conditions. Although we find examples for which mass independence of the horizon entropy product continues …

Gravitational Tension And Thermodynamics Of Planar Ads Spacetimes, Basem M. El-Menoufi, Benjamin Ett, David Kastor, Jennie Traschen

David Kastor

We derive new thermodynamic relations for asymptotically planar AdS black hole and soliton solutions. In addition to the ADM mass, these spacetimes are characterized by gravitational tensions in each of the planar spatial directions. We show that with planar AdS asymptotics, the sum of the ADM mass and tensions necessarily vanishes, as one would expect from the AdS /CFT correspondence. Each Killing vector of such a spacetime leads to a Smarr formula relating the ADM mass and tensions, the black hole horizon and soliton bubble areas, and a set of thermodynamic volumes that arise due to the non-vanishing cosmological constant. …

Thermodynamic Volumes And Isoperimetric Inequalities For De Sitter Black Holes, Brian P. Dolan, David Kastor, David KubiznˇA´K, Robert B. Mann, Jennie Traschen

David Kastor

We consider the thermodynamics of rotating and charged asymptotically de Sitter black holes. Using Hamiltonian perturbation theory techniques, we derive three different first law relations including variations in the cosmological constant, and associated Smarr formulas that are satisfied by such spacetimes. Each first law introduces a different thermodynamic volume conjugate to the cosmological constant. We examine the relation between these thermodynamic volumes and associated geometric volumes in a number of examples, including Kerr-dS black holes in all dimensions and Kerr-Newman-dS black holes in D=4. We also show that the Chong-Cvetic-Lu-Pope solution of D=5 minimal supergravity, analytically continued to positive cosmological …

Charge Transport Studies Of Proton And Ion Conducting Materials, Craig William Versek

Open Access Dissertations

The development of a high-throughput impedance spectroscopy instrumentation platform for conductivity characterization of ion transport materials is outlined. Collaborative studies using this system are summarized. Charge conduction mechanisms and conductivity data for small molecule proton conducting liquids, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, and select mixtures of these compounds are documented. Furthermore, proton diffusivity measurements using a Pulse Field Gradient Nuclear Magnetic Resonance (PFG NMR) technique for imidazole and 1,2,3-triazole binary mixtures are compared. Studies of azole functionalized discotic and linear mesogens with conductivity, structural, and thermal characterizations are detailed.

The Effect Of Vesicle Shape, Line Tension, And Lateral Tension On Membrane-Binding Proteins, Jaime Bosart Hutchison

Open Access Dissertations

Model membranes allow for the exploration of complex biological phenomena with simple, controllable components. In this thesis we employ model membranes to determine the effect of vesicle properties such as line tension, lateral tension, and shape on membrane-binding proteins. We find that line tension at the boundary between domains in a phase separated vesicle can accumulate model membrane-binding proteins (green fluorescent protein with a histidine tag), and that those proteins can, in turn, alter vesicle shape. These results suggest that domains in biological membranes may enhance the local concentration of membrane-bound proteins and thus alter protein function. We also explore …

A Measurement Of The W/Z Cross Section Ratio As A Function Of Hadronic Activity With The Atlas Detector, Andrew Robert Meade

Open Access Dissertations

Hadronic collisions at the LHC at CERN probe particle interactions at the highest energy scale of any experiment to date. We present a research program measuring R_jet = &sigma_WBR(W&rarr&mu&nu) / (&sigma_ZBR(Z&rarr&mu&mu)) as a function of a number of hadronic variables. The measurements are performed with the ATLAS detector at the LHC, using the 2011 data set, consisting of 4.64 fb-1 of pp collisions at a center of mass energy of 7 TeV. This measurement is a robust way to test the Standard Model and the modeling of perturbative QCD, and is sensitive to a wide …

On Random Time And On The Relation Between Wave And Telegraph Equations, Ramakrishna Janaswamy

Ramakrishna Janaswamy

Kac’s conjecture relating the solution of wave and telegraph equations in higher dimensions through a Poisson process-driven random time is established through the concepts of stochastic calculus. New expression is derived for the probability density function of the random time. We demonstrate how the relationship between the solution of a lossy wave- and that of a lossless wave equation can be exploited to derive some statistical identities. Relevance of the results presented to the study of pulse propagation in a dispersive medium characterized by a Lorentz or Drude model is discussed and new evolution equations for 2D Maxwell’s equations are …

Nambu-Goldstone Modes And Diffuse Deformations In Elastic Shells, Christian Santangelo

Christian Santangelo

I consider the shape of a deformed elastic shell. Using the fact that the lowest-energy, small deformations are along infinitesimal isometries of the shell's mid-surface, I describe a class of weakly stretching deformations for thin shells based on the Nambu–Goldstone modes associated with those isometries. The main result is an effective theory to describe the diffuse deformations of thin shells that incorporate stretching and bending energies. The theory recovers previous results for the propagation of a “pinch” on a cylinder. A cone, on the other hand, has two length scales governing the persistence of a pinch: one governing the relaxation …

Investigations Of Surface-Tension Effects Due To Small-Scale Complex Boundaries, Jiansheng Feng

Open Access Dissertations

The earliest man-made irrigation systems in recorded history date back to the ancient Egypt and Mesopotamia era. After thousands of years of experience, exploration, and experimenting, mankind have learned how to construct canals and dams and use pipes and pumps to direct and control water flow, but till this day, there are still some behaviors of water and other simple fluids that surprise us. One such example is the lotus effect: a surface-tension effect which allows raindrops to roll freely on a lotus leaf as if they were drops of mercury. One of the key factors that determine how a …

Pattern Formation In Floating Sheets, Hunter King

Open Access Dissertations

This thesis presents a study of two basic modes of deformation of a thin sheet: wrinkling and crumpling, viewed primarily in the context of an elastic sheet confined by capillary forces on a drop of liquid.

First, it provides a brief conceptual background in the relevant physics of thin sheet mechanics and capillarity and introduces the general principles of wrinkling and crumpling.

The problem of confining a circular sheet on an increasingly curved spherical drop is presented as a vehicle to explore these principles. At finite curvature, the sheet is seen to wrinkle around its outer edge. At large confinement, …

Measuring Proton Spin Polarizabilities With Polarized Compton Scattering, Philippe Paul Martel

Open Access Dissertations

Polarized nuclear Compton scattering on a proton target provides a test of low energy QCD. The beam-target asymmetries of a circularly polarized Bremsstrahlung photon beam on a transversely polarized butanol target (&Sigma_2x) and on a longitudinally polarized butanol target (&Sigma_2z), and the beam asymmetry of a linearly polarized Bremsstrahlung beam on an unpolarized hydrogen target (&Sigma₃) are sensitive to the proton spin polarizabilities, third order terms in the energy expansion of the Compton scattering amplitude. This experiment consisted of the &Sigma_2x measurement, both just below and above two-pion threshold.

A Non-Linear Eigensolver-Based Alternative To Traditional Self-Consistent Electronic Structure Calculation Methods, Brendan E. Gavin

Masters Theses 1911 - February 2014

This thesis presents a means of enhancing the iterative calculation techniques used in electronic structure calculations, particularly Kohn-Sham DFT. Based on the subspace iteration method of the FEAST eigenvalue solving algorithm, this nonlinear FEAST algorithm (NLFEAST) improves the convergence rate of traditional iterative methods and dramatically improves their robustness. A description of the algorithm is given, along with the results of numerical experiments that demonstrate its effectiveness and offer insight into the factors that determine how well it performs.

Department Of Physics Newsletter: Spring 2013, Dan Candela

Physics Newsletters

No abstract provided.

Everyday Particle Physics, Andrea Pocar

Science and Engineering Saturday Seminars

No abstract provided.

Chiral Cp^2 Skyrmions In Three-Band Superconductors, Garaud Julien, Johan CarlstrOm, Egor Babaev, Martin Speight

Egor Babaev

No abstract provided.

Stripe, Gossamer, And Glassy Phases In Systems With Strong Non-Pairwise Interactions, Karl A. H. Sellin, Egor Babaev

Egor Babaev

We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of nonpairwise interaction.

Hierarchical Structure Formation In Layered Superconducting Systems With Multi-Scale Inter-Vortex Interactions, Christopher N. Varney, Karl A. H. Sellin, Qing-Ze Wang, Hans Fangohr, Egor Babaev

Egor Babaev

We demonstrate the formation of hierarchical structures in two-dimensional systems with multiple length scales in the inter-particle interaction. These include states such as clusters of clusters, concentric rings, clusters inside a ring, and stripes in a cluster. We propose to realize such systems in vortex matter (where a vortex is mapped onto a particle with multi-scale interactions) in layered superconducting systems with varying inter-layer thicknesses and different layer materials.

Freezing Of An Unconventional Two-Dimensional Plasma, Egil V. Herland, Egor Babaev, Parsa Bonderson, Victor Gurarie, Chetan Nayak, Leo Radzihovsky, Asle Sudbo

Egor Babaev

No abstract provided.

Correlations Between The Dynamics Of Parallel Tempering And The Free Energy Landscape In Spin Glasses, Burcu Yucesoy, Jonathan Machta, Helmut G. Katzgraber

Jonathan Machta

We present the results of a large-scale numerical study of the equilibrium three-dimensional Edwards-Anderson Ising spin glass with Gaussian disorder. Using parallel tempering (replica exchange) Monte Carlo we measure various static, as well as dynamical quantities, such as the autocorrelation times and round-trip times for the parallel tempering Monte Carlo method. The correlation between static and dynamic observables for 5000 disorder realizations and up to 1000 spins down to temperatures at 20% of the critical temperature is examined. Our results show that autocorrelation times are directly correlated with the roughness of the free-energy landscape.

Classification Of Ground States And Normal Modes For Phase-Frustrated, Daniel Weston, Egor Babaev

Egor Babaev

No abstract provided.

Phase Structure And Phase Transitions In A Three Dimensional Su(2) Superconductor, Egil V. Herland, Troels A. Bojesen, Egor Babaev, Asle Sudb

Egor Babaev

No abstract provided.

Nature Vs. Nurture: Predictability In Low-Temperature Ising Dynamics, J. Ye, Jonathan Machta, C. M. Newman, D. L. Stein

Jonathan Machta

Consider a dynamical many-body system with a random initial state subsequently evolving through stochastic dynamics. What is the relative importance of the initial state (“nature”) versus the realization of the stochastic dynamics (“nurture”) in predicting the final state? We examined this question for the two-dimensional Ising ferromagnet following an initial deep quench from T=∞ to T=0. We performed Monte Carlo studies on the overlap between “identical twins” raised in independent dynamical environments, up to size L=500. Our results suggest an overlap decaying with time as t−θh with θh=0.22±0.02; the same exponent holds for a quench to low but nonzero temperature. …

Time Reversal Symmetry Breakdown In Normal And Superconducting States In Frustrated Three-Band Systems, Troels Arnfred Bojesen, Egor Babaev, Asle Sudbo

Egor Babaev

We discuss the phase diagram and phase transitions in U(1)×Z2 three-band superconductors with broken time reversal symmetry. We find that beyond mean-field approximation and for sufficiently strong frustration of interband interactions there appears an unusual metallic state precursory to a superconducting phase transition. In that state, the system is not superconducting. Nonetheless, it features a spontaneously broken Z2 time reversal symmetry. By contrast, for weak frustration of interband coupling the energy of a domain wall between different Z2 states is low and thus fluctuations restore broken time reversal symmetry in the superconducting state at low temperatures.

Unusual Mechanism Of Vortex Viscosity Generated By Mixed Normal Modes In Superconductors With Broken Time Reversal Symmetry, Mihail Silaev, Egor Babaev

Egor Babaev

We show that under certain conditions, multiband superconductors with broken time reversal symmetry have a vortex viscosity-generating mechanism which is different from that in conventional superconductors. It appears due to the existence of a mixed superfluid phase-density mode inside the vortex core. This contribution is dominant near the time reversal symmetry-breaking phase transition. The results could be relevant for the three-band superconductor Ba1−xKxFe2As2.