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Full-Text Articles in Physical Sciences and Mathematics

Directional Limits On Persistent Gravitational Waves Using Ligo S5 Science Data, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Dec 2011

Directional Limits On Persistent Gravitational Waves Using Ligo S5 Science Data, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2 - 20 x 10-50 strain2 Hz-1 and 5 - 35 x 10-49 strain2Hz-1sr-1 for pointlike and extended sources, respectively. The latter result is the first ...


Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr Dec 2011

Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr

Physics Faculty Research & Creative Works

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when ...


Prospects For Determination Of Thermal History After Inflation With Future Gravitational Wave Detectors, Sachiko Kuroyanagi, Kazunori Nakayama, Shun Saito Dec 2011

Prospects For Determination Of Thermal History After Inflation With Future Gravitational Wave Detectors, Sachiko Kuroyanagi, Kazunori Nakayama, Shun Saito

Physics Faculty Research & Creative Works

Thermal history of the Universe between inflation and big-bang nucleosynthesis has not yet been revealed observationally. It will be probed by the detection of primordial gravitational waves generated during inflation, which contain information on the reheating temperature as well as the equation of state of the Universe after inflation. Based on the Fisher information formalism, we examine how accurately the tensor-to-scalar ratio and reheating temperature after inflation can be simultaneously determined with space-based gravitational wave detectors such as the DECI-hertz Interferometer Gravitational-wave Observatory and the Big-Bang Observer. We show that the reheating temperature is best determined if it is around ...


Infinite-Randomness Criticality In A Randomly Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Thomas Vojta Nov 2011

Infinite-Randomness Criticality In A Randomly Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Thomas Vojta

Physics Faculty Research & Creative Works

We study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte Carlo simulations. Our results provide numerical evidence for the infinite-randomness scenario recently predicted within a strong-disorder renormalization-group approach. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility, which is characterized by a nonuniversal power-law divergence in the Griffiths phase. We also study the perpendicular and parallel spin-wave stiffnesses in the Griffiths phase. In agreement with the theoretical predictions, the parallel stiffness is nonzero for all temperatures T < Tc. In contrast, the perpendicular stiffness remains zero in part of the ordered phase, giving rise ...


Quantum Phase Transition Of The Sub-Ohmic Rotor Model, Manal Al-Ali, Thomas Vojta Nov 2011

Quantum Phase Transition Of The Sub-Ohmic Rotor Model, Manal Al-Ali, Thomas Vojta

Physics Faculty Research & Creative Works

We investigate the behavior of an N-component quantum rotor coupled to a bosonic dissipative bath having a sub-Ohmic spectral density J (ω) ∝ ωs with s < 1.With increasing dissipation strength, this system undergoes a quantum phase transition from a delocalized phase to a localized phase.We determine the exact critical behavior of this transition in the large-N limit. For 1 > s > 1/2, we find nontrivial critical behavior corresponding to an interacting renormalization group fixed point, while we find mean-field behavior for s < 1/2. The results agree with those of the corresponding long-range interacting classical model ...


Influence Of Gas Pressure On High-Order-Harmonic Generation Of Ar And Ne, Guoli Wang, Cheng Jin, Anh-Thu Le, C. D. Lin Nov 2011

Influence Of Gas Pressure On High-Order-Harmonic Generation Of Ar And Ne, Guoli Wang, Cheng Jin, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

We study the effect of gas pressure on the generation of high-order harmonics where harmonics due to individual atoms are calculated using the recently developed quantitative rescattering theory, and the propagation of the laser and harmonics in the medium is calculated by solving the Maxwell's wave equation. We illustrate that the simulated spectra are very sensitive to the laser focusing conditions at high laser intensity and high pressure since the fundamental laser field is severely reshaped during the propagation. By comparing the simulated results with several experiments we show that the pressure dependence can be qualitatively explained. The lack ...


Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin Oct 2011

Generation Of Isolated Attosecond Pulses In The Far Field By Spatial Filtering With An Intense Few-Cycle Mid-Infrared Laser, Cheng Jin, Anh-Thu Le, Carlos A. Trallero-Herrero, C. D. Lin

Physics Faculty Research & Creative Works

We report theoretical calculations of high-order harmonic generation (HHG) of Xe with the inclusion of multielectron effects and macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. By using the time-frequency analysis we show that the reshaping of the fundamental laser field is responsible for the continuum structure in the HHG spectra. We further suggest a method for obtaining an isolated attosecond pulse (IAP) by using a filter centered on axis to select the harmonics in the far field with different divergence. We also discuss the carrier-envelope-phase dependence of an IAP and the possibility to optimize the ...


Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke Oct 2011

Orientation Dependence Of The Ionization Of Co And No In An Intense Femtosecond Two-Color Laser Field, H. Li, D. Ray, S. De, I. Znakovskaya, W. Cao, G. Laurent, Z. Wang, M. F. Kling, Anh-Thu Le, C. L. Cocke

Physics Faculty Research & Creative Works

Two-color (800- and 400-nm) short (45-fs) linearly polarized pulses are used to ionize and dissociate CO and NO. The emission of Cq+, Nq+, and O⁺ fragments indicates that the higher ionization rate occurs when the peak electric field points from C to O in CO and from N to O in NO. This preferred direction is in agreement with that predicted by Stark-corrected strong-field-approximation calculations.


Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'", Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray Oct 2011

Reply To "Comment On 'Counterintuitive Consequence Of Heating In Strongly-Driven Intrinsic Junctions Of Bi₂Sr₂Cacu₂O 8+Δ Mesas'", Cihan Kurter, Lutfi Ozyuzer, Thomas Proslier, John F. Zasadzinski, David G. Hinks, Kenneth E. Gray

Physics Faculty Research & Creative Works

The main criticism raised in the preceding Comment concerns our suggestion that sharp conduction peaks in Bi2Sr2CaCu2O 8+δ mesas, along with absent dip-hump features, may, in general, be a result of self-heating. The author points to the variety of experimental configurations, matrix-element effects, and doping dependencies that might allow a diversity of conductance spectra. We argue that numerous mesa studies (with fixed matrix elements) firmly establish the systematic development of sharp conductance peaks with increased self-heating, and thus, the issue of nonuniversality of tunneling characteristics is not relevant. The author mentions a number of studies ...


Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta Sep 2011

Transport Properties In Antiferromagnetic Quantum Griffiths Phases, David Nozadze, Thomas Vojta

Physics Faculty Research & Creative Works

We study the electrical resistivity in the quantum Griffiths phase associated with the antiferromagnetic quantum phase transition in a metal. The resistivity is calculated by means of the semi-classical Boltzmann equation. We show that the scattering of electrons by locally ordered rare regions leads to a singular temperature dependence. The rare-region contribution to the resistivity varies as Tλ with temperature T, where λ is the usual Griffiths exponent which takes the value zero at the critical point and increases with distance from criticality. We find similar singular contributions to other transport properties such as thermal resistivity, thermopower and the ...


Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz Sep 2011

Double Ionization Of Helium By Highly-Charged-Ion Impact Analyzed Within The Frozen-Correlation Approximation, Marcelo F. Ciappina, Tom Kirchner, Michael Schulz

Physics Faculty Research & Creative Works

We apply the frozen-correlation approximation (FCA) to analyze double ionization of helium by energetic highly charged ions. In this model the double ionization amplitude is represented in terms of single ionization amplitudes, which we evaluate within the continuum distorted wave-eikonal initial state (CDW-EIS) approach. Correlation effects are incorporated in the initial and final states, but are neglected during the time the collision process takes place. We implement the FCA using the Monte Carlo event generator technique, which allows us to generate theoretical event files and to compare theory and experiment using the same analysis tools. The comparison with previous theoretical ...


Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage Sep 2011

Microscopic Examination Of Hot Spots Giving Rise To Nonlinearity In Superconducting Resonators, Cihan Kurter, Alexander P. Zhuravel, Alexey V. Ustinov, Steven M. Anlage

Physics Faculty Research & Creative Works

We investigate the microscopic origins of nonlinear rf response in superconducting electromagnetic resonators. Strong nonlinearity appearing in the transmission spectra at high input powers manifests itself through the emergence of jumplike features near the resonant frequency that evolve toward lower quality factor with higher insertion loss as the rf input power is increased. We directly relate these characteristics to the dynamics of localized normal regions (hot spots) caused by microscopic features in the superconducting material making up the resonator. A clear observation of hot-spot formation inside a Nb thin film self-resonant structure is presented by employing the microwave laser scanning ...


Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin Aug 2011

Strong-Field Nonsequential Double Ionization Of Ar And Ne, Zhangjin Chen, Yaqiu Liang, Don H. Madison, Chiidong Lin

Physics Faculty Research & Creative Works

We investigate the nonsequential double ionization (NSDI) of Ar and Ne based on quantitative rescattering theory (QRS). According to QRS theory, each elementary NSDI process can be calculated by multiplying the returning electron wave packet with appropriate differential electron-ion scattering cross sections. We include (e, 2e) and electron-impact excitation cross sections of Ar+ to obtain the correlated electron momentum spectra for the NSDI of Ar by few-cycle pulses to check the dependence of NSDI on the carrier-envelope phase. The results are compared to the ion momentum spectra from the recent experiment of Johnson [Phys. Rev. APLRAAN1050-294710.1103/ PhysRevA.83.013412 ...


Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer Aug 2011

Mutual Projectile And Target Ionization In 1-Mev/Amu N⁴⁺ And N₅⁺+ He Collisions, Xincheng Wang, Katharina R. Schneider, Aditya H. Kelkar, Gunterschul Brenner, Michael Schulz, B. Najjari, Alexander B. Voitkiv, M. Gundmundsson, Manfred Grieser, Claude Krantz, Michael Lestinsky, Andreas R. Wolf, Siegbert Hagmann, Robert Moshammer, Joachim Hermann Ullrich, Daniel Fischer

Physics Faculty Research & Creative Works

We have studied mutual projectile and target ionization in 1-MeV/amu N4+ and N5++He collisions in kinematically complete experiments by measuring the momenta of the recoil ion and both ejected electrons in coincidence with the charge-changed projectiles. By means of four-particle Dalitz plots, in which multiple differential cross sections are presented as a function of the momenta of all four particles, experimental spectra are compared with theoretical results from various models. The experimental data are qualitatively reproduced by higher-order calculations, where good agreement is achieved for N5++He collisions, while some discrepancies persist for N4 ...


Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis Jul 2011

Classical Analogue Of Electromagnetically Induced Transparency With A Metal-Superconductor Hybrid Metamaterial, Cihan Kurter, Philippe Tassin, Lei Zhang, Thomas Koschny, Alexander P. Zhuravel, Alexey V. Ustinov, Steven Mark Anlage, Costas M. Soukoulis

Physics Faculty Research & Creative Works

Metamaterials are engineered materials composed of small electrical circuits producing novel interactions with electromagnetic waves. Recently, a new class of metamaterials has been created to mimic the behavior of media displaying electromagnetically induced transparency (EIT). Here we introduce a planar EIT metamaterial that creates a very large loss contrast between the dark and radiative resonators by employing a superconducting Nb film in the dark element and a normal-metal Au film in the radiative element. Below the critical temperature of Nb, the resistance contrast opens up a transparency window along with a large enhancement in group delay, enabling a significant slowdown ...


Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura Jul 2011

Relativistic Reduced-Mass And Recoil Corrections To Vacuum Polarization In Muonic Hydrogen, Muonic Deuterium, And Muonic Helium Ions, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

The reduced-mass dependence of relativistic and radiative effects in simple muonic bound systems is investigated. The spin-dependent nuclear recoil correction of order (Zα)4μ3/m2N is evaluated for muonic hydrogen and deuterium and muonic helium ions (μ is the reduced mass and mN is the nuclear mass). Relativistic corrections to vacuum polarization of order α(Zα)4μ are calculated, with a full account of the reduced-mass dependence. The results shift theoretical predictions. The radiative-recoil correction to vacuum polarization of order α(Zα)5-ln2(Zα) μ2/mN is obtained in leading ...


Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta Jun 2011

Evidence For Power-Law Griffiths Singularities In A Layered Heisenberg Magnet, Fawaz Hrahsheh, Hatem Barghathi, Priyanka Mohan, Rajesh Narayanan, Thomas Vojta

Physics Faculty Research & Creative Works

We study the ferromagnetic phase transition in a randomly layered Heisenberg model. A recent strong-disorder renormalization group approach [Phys. Rev. B 81, 144407 (2010)] predicted that the critical point in this system is of exotic infinite-randomness type and is accompanied by strong power-law Griffiths singularities. Here, we report results of Monte-Carlo simulations that provide numerical evidence in support of these predictions. Specifically, we investigate the finite-size scaling behavior of the magnetic susceptibility which is characterized by a non-universal power-law divergence in the Griffiths phase. In addition, we calculate the time autocorrelation function of the spins. It features a very slow ...


Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta Jun 2011

Composition-Tuned Smeared Phase Transitions, Fawaz Hrahsheh, David Nozadze, Thomas Vojta

Physics Faculty Research & Creative Works

Phase transitions in random systems are smeared if individual spatial regions can order independently of the bulk system. In this paper, we study such smeared phase transitions (both classical and quantum) in substitutional alloys A 1-xB x that can be tuned from an ordered phase at composition x=0 to a disordered phase at x=1. We show that the ordered phase develops a pronounced tail that extends over all compositions x<1. Using optimal fluctuation theory, we derive the composition dependence of the order parameter and other quantities in the tail of the smeared phase transition. We also compare our results to computer simulations of a toy model, and we discuss experiments.


Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov Jun 2011

Young-Type Interference In Projectile-Electron Loss In Energetic Ion-Molecule Collisions, Alexander B. Voitkiv, B. Najjari, Daniel Fischer, Anton N. Artemyev, Andrey S. Surzhykov

Physics Faculty Research & Creative Works

Under certain conditions an electron bound in a fast projectile ion, colliding with a molecule, interacts mainly with the nuclei and inner shell electrons of atoms forming the molecule. Because of their compact localization in space and distinct separation from each other, these molecular centers play in such collisions a role similar to that of optical slits in light scattering leading to pronounced interference in the spectra of the electron emitted from the projectile.


Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2011

Search For Gravitational Wave Bursts From Six Magnetars, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ∼1kpc from Earth, an order of ...


Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website. Jun 2011

Search For Gravitational Waves From Binary Black Hole Inspiral, Merger, And Ringdown, J. Abadie, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.

Physics Faculty Research & Creative Works

We present the first modeled search for gravitational waves using the complete binary black-hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data, taken between November 2005 and September 2007, for systems with component masses of 1-99M and total masses of 25-100M. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for 19M ≤m 1, m2 ...


Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin May 2011

Analysis Of Effects Of Macroscopic Propagation And Multiple Molecular Orbitals On The Minimum In High-Order Harmonic Generation Of Aligned Co₂, Cheng Jin, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

We report theoretical calculations of the effect of the multiple-orbital contribution in high-order harmonic generation (HHG) of aligned CO₂ with the inclusion of macroscopic propagation of harmonic fields in the medium. Our results show very good agreement with recent experiments for the dynamics of the minimum in HHG spectra as laser intensity or alignment angle changes. Calculations are carried out to check how the position of the minimum in HHG spectra depends on the degrees of molecular alignment, laser-focusing conditions, and the effects of alignment-dependent ionization rates of the different molecular orbitals. These analyses help to explain why the minima ...


Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi May 2011

Forecasting The Cosmological Constraints With Anisotropic Baryon Acoustic Oscillations From Multipole Expansion, Atsushi Taruya, Shun Saito, Takahiro Nishimichi

Physics Faculty Research & Creative Works

Baryon acoustic oscillations imprinted in the galaxy power spectrum can be used as a standard ruler to determine the angular diameter distance and Hubble parameter from high-redshift galaxies. Combining redshift distortion effect which apparently distorts the galaxy clustering pattern, we can also constrain the growth rate of large-scale structure formation. Usually, future forecasts for constraining these parameters from galaxy redshift surveys are made with the full 2D power spectrum characterized as a function of wave number k and directional cosine µ between line-of-sight direction and wave vector, i.e., P(k,µ). Here, we apply the multipole expansion to the ...


Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura May 2011

Self-Energy Correction To The Hyperfine Splitting For Excited States, Benedikt J. Wundt, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Zα, where Z is the nuclear-charge number and α is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13≤n≤16, and orbital angular momenta =n-2 and =n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with ≥2 and arbitrary n, , and total angular momentum j. The low-energy ...


Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison May 2011

Low Energy (E,2e) Studies From Ch₄: Results From Symmetric Coplanar Experiments And Molecular Three-Body Distorted Wave Theory, Kate L. Nixon, Andrew James Murray, Hari Chaluvadi, Chuangang Ning, Don H. Madison

Physics Faculty Research & Creative Works

Low energy experimental and theoretical triply differential cross sections are presented for electron impact ionization of methane (CH4) for both the highest occupied molecular orbital (HOMO) and next highest occupied molecular orbital (NHOMO). The HOMO is a predominantly p-type orbital which is labeled 1t2 and the NHOMO is predominantly s-type labeled 2a 1. Coplanar symmetric (symmetric both in final state electron energies and observation angles) are presented for final state electron energies ranging from 2.5 to 20 eV. The theoretical M3DW (molecular three-body distorted wave) results are in surprisingly good agreement with experiment for the HOMO state ...


Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley May 2011

Relativistic Tight-Binding Model: Application To Pt Surfaces, Aleksandr V. Chernatynskiy, J. Woods Halley

Physics Faculty Research & Creative Works

We report a parametrization of a previous self-consistent tight-binding model, suitable for metals with a high atomic number in which nonscalar-relativistic effects are significant in the electron physics of condensed phases. The method is applied to platinum. The model is fitted to density functional theory band structures and cohesive energies and spectroscopic data on platinum atoms in five oxidation states, and is then shown without further parametrization to correctly reproduce several low index surface structures. We also predict reconstructions of some vicinal surfaces.


Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch Apr 2011

Hydrogen-Deuterium Isotope Shift: From The 1s-2s-Transition Frequency To The Proton-Deuteron Charge-Radius Difference, Ulrich D. Jentschura, Arthur N. Matveev, Christian G. Parthey, Janis Alnis, Randolf Pohl, Th H. Udem, Nikolai N. Kolachevsky, Theodor Wolfgang Hansch

Physics Faculty Research & Creative Works

We analyze and review the theory of the hydrogen-deuterium isotope shift for the 1S-2S transition, which is one of the most accurately measured isotope shifts in any atomic system, in view of a recently improved experiment. A tabulation of all physical effects that contribute to the isotope shift is given. These include the Dirac binding energy, quantum electrodynamic effects, including recoil corrections, and the nuclear-size effect, including the pertaining relativistic and radiative corrections. From a comparison of the theoretical result Δfth=670999566.90(66)(60)kHz (exclusive of the nonrelativistic nuclear-finite-size correction) and the experimental result Δfexpt=670994334605 ...


Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito Apr 2011

Tracing The Redshift Evolution Of Hubble Parameter With Gravitational-Wave Standard Sirens, Atsushi J. Nishizawa, Atsushi Taruya, Shun Saito

Physics Faculty Research & Creative Works

Proposed space-based gravitational-wave detectors such as BBO and DECIGO can detect ~ 106 neutron star (NS) binaries and determine the luminosity distance to the binaries with high precision. Combining the luminosity distance and electromagnetically derived redshift, one would be able to probe cosmological expansion out to high redshift. In this paper, we show that the Hubble parameter as a function of redshift can be directly measured with monopole and dipole components of the luminosity distance on the sky. As a result, the measurement accuracies of the Hubble parameter in each redshift bin up to z=1 are 3-14%, 1.5-8 ...


Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz Apr 2011

Manipulating Atomic Fragmentation Processes By Controlling The Projectile Coherence, Kisra N. Egodapitiya, Sachin D. Sharma, Ahmad Hasan, Aaron C. Laforge, Don H. Madison, Robert Moshammer, Michael Schulz

Physics Faculty Research & Creative Works

We have measured the scattering angle dependence of cross sections for ionization in p+H2 collisions for a fixed projectile energy loss. Depending on the projectile coherence, interference due to indistinguishable diffraction of the projectile from the two atomic centers was either present or absent in the data. This shows that, due to the fundamentals of quantum mechanics, the preparation of the beam must be included in theoretical calculations. The results have far-reaching implications on formal atomic scattering theory because this critical aspect has been overlooked for several decades.


Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr Apr 2011

Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr

Physics Faculty Research & Creative Works

The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric ...