Note: This page contains sample records for the topic coulomb yukawa potentials from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

D-Wave Resonances in Three-Body System Ps- with Pure Coulomb and Screened Coulomb (Yukawa) Potentials  

NASA Astrophysics Data System (ADS)

We have investigated the doubly excited 1 D e resonance states of Ps- interacting with pure Coulomb and screened Coulomb (Yukawa) potentials employing highly correlated wavefunctions. For pure Coulomb interaction, in the framework of stabilization method and complex coordinate rotation method we have obtained two resonances below the n = 2 threshold of the Ps atom. For screened Coulomb interaction, we employ the stabilization method to extract resonance parameters. Resonance energies and widths for the 1 D e resonance states of Ps- for different screening parameter ranging from infinity (pure Coulomb case) to a small value are also reported.

Kar, Sabyasachi; Ho, Y. K.

2009-04-01

2

Ground states and resonance states of Ps- and He interacting with screened Coulomb (Yukawa) potentials  

NASA Astrophysics Data System (ADS)

We present a brief review for the recent investigations on the ground states and resonance states for dense plasma-embedded Ps- and He using screened Coulomb (Yukawa) potentials for the plasma effects. New results for the 1,3Se resonance states of He in plasmas are also reported.

Kar, Sabyasachi; Ho, Y. K.

2007-06-01

3

Effects of screened Coulomb (Yukawa) and exponential-cosine-screened Coulomb potentials on photoionization of H and He+  

NASA Astrophysics Data System (ADS)

The screening effects due to the exponential-cosine-screened Coulomb and screened Coulomb (Yukawa) potentials on photoionization processes are explored within the framework of complex coordinate rotation method. The energy levels of H and He+ in both screened potentials shifted with various Debye screening lengths are presented. The photoionization cross sections illustrate the considerable screening effects on photoionization processes in low energy region. The shape resonances can be found near ionization thresholds for certain of Debye screening lengths. The relations between the appearance of resonances and the existence of quasi-bound states under shielding conditions are discussed.

Lin, C. Y.; Ho, Y. K.

2010-03-01

4

Photodetachment of the positronium negative ion interacting with screened Coulomb (Yukawa) potentials  

NASA Astrophysics Data System (ADS)

The effect of screened Coulomb (Yukawa) potentials on the photodetachment cross sections of the positronium negative ion is investigated by using the asymptotic form of the bound-state wave function and a plane wave form for the final-state wave function. The required normalization constant is determined from highly accurate, completely non-adiabatic wave functions for the three-particle systems. Photodetachment cross sections for the Ps- ion are calculated for different Debye shielding lengths ( D) ranging from infinite (pure Coulomb) to D = 1.81.

Kar, S.; Ho, Y. K.

2008-07-01

5

Folded potentials in cluster physics—a comparison of Yukawa and Coulomb potentials with Riesz fractional integrals  

NASA Astrophysics Data System (ADS)

In cluster physics, a single-particle potential to determine the microscopic part of the total energy of a collective configuration is necessary to calculate the shell and pairing effects. In this paper, we investigate the properties of the Riesz fractional integrals and compare their properties with the standard Coulomb and Yukawa potentials commonly used. It is demonstrated that Riesz potentials may serve as a promising extension of standard potentials and may be reckoned as a smooth transition from Coulomb- to Yukawa-like potentials, depending on the fractional parameter ?. For the macroscopic part of the total energy, the Riesz potentials treat the Coulomb, symmetry and pairing contributions from a generalized point of view, since they turn out to be similar realizations of the same fractional integral at distinct ? values.

Herrmann, Richard

2013-10-01

6

Complex-Scaling Calculations for Doubly Excited Resonances in Ps- Interacting with Screened Coulomb (Yukawa) Potentials  

NASA Astrophysics Data System (ADS)

We have investigated the effect of screened Coulomb potentials on the high-lying doubly excited resonance states of the positronium negative ion in the framework of complex-scaling method. Highly correlated wave functions in Hylleraas coordinates are used. The resonance parameters below the Ps (2s2S) and Ps (3s2S) thresholds, for various screening parameters, are reported.

Ho, Y. K.; Kar, S.

2012-10-01

7

The screened Coulomb (Yukawa) charged hard sphere binary fluid  

NASA Astrophysics Data System (ADS)

The screened Coulomb (Yukawa) restricted primitive model (Y RPM) of a binary fluid is treated within the one-pole generalized mean-spherical approximation (GMSA). Fluid phase behaviour and structure are compared with the corresponding results for the unscreened Coulombic RPM. Screening increases the critical density and temperature above the values for the RPM and decreases the width of the liquid-gas coexistence curves. The asymptotics of pairwise correlation functions and the genesis of disorder lines in the phase diagram are discussed. These lines are where the ultimate decay of total density or concentration (charge) correlations crosses over from monotonic to oscillatory. The location of the disorder lines is strongly dependent on the range of the Yukawa potentials. We show that very shortrange interionic potentials (Yukawa models) can give rise to correlation functions which are difficult to distinguish (at all interionic separations) from those obtained for the long-range Coulombic case for structurally equivalent thermodynamic states, reinforcing the idea that pronounced charge ordering is not unique to Coulombic interactions but can occur whenever the interaction potential between different species (AB) is strongly attractive and the potentials between identical species (AA and BB) are repulsive. Although the GMSA generally improves upon the MSA, we show that it leads to artificial peaks (not found in simulation) for correlations g(r)between identical ionic species at separations r close to ionic contract when the density is high and the temperature is low. This failing, which occurs for both the RPM and Y RPM, reflects the sensitivity of g(r) near contact to approximations.ii

Leote de Carvalho, R. J. F.; Evans, R.

8

Complex-Scaling Treatment for Doubly Excited Inter-Shell Resonances in H- Interacting with Screened Coulomb (Yukawa) Potentials  

NASA Astrophysics Data System (ADS)

The doubly-excited inter-shell resonance states of the hydrogen negative ion with screened Coulomb potentials are investigated in the framework of complex-scaling method. Highly correlated wave functions with terms up to 1078 in Hylleraas coordinates are used. The resonance parameters for the 2 s3 s 1 S e associated with the H ( N = 2) threshold and the 3 s4 s 1 S e state associated with the H ( N = 3) threshold for various screening strengths are reported. Comparisons are made with other available data in the literature.

Ho, Y. K.; Kar, S.

2012-10-01

9

Upper Limits for the Number of Bound States Associated with the Yukawa Potential.  

National Technical Information Service (NTIS)

The number of bound-state solutions of the Schrodinger equation for the screened Coulomb potential (Yukawa potential), --(C/r) exp(-alpha r), occurs frequently in theoretical discussions concerning, for example, gas discharges, nuclear physics, and semico...

H. S. Bennett

1980-01-01

10

A Fast Adaptive Multipole Algorithm for Calculating Screened Coulomb (Yukawa) Interactions  

NASA Astrophysics Data System (ADS)

The screened Coulomb (Yukawa or Debye-Hückel) potential, ?=exp(-?r)/r, whereris the separation distance and ? is the Debye-Hückel screening parameter, gives a good description of the electrostatic interactions in a variety of biologically and physically important charged systems. It is well known that the direct calculation of the energy and forces due to a collection ofNcharged particles involves the pairwise summation of all charged particle interactions and exhibits anO(N2) computational complexity which severely restricts maximum problem size. This has prompted the development of fast summation algorithms that allow the electrostatic energy and forces to be obtained in onlyO(NlogN) operations. To date, however, practically all such implementations have been limited exclusively to pure Coulombic potentials (?=0), and the central contribution of the present method is to extend this capability to the entire range of the inverse Debye length, ?>=0. The basic formulation and computational implementation of the spherical modified Bessel function-based multipole expansions appropriate for the screened Coulomb kernel are first presented. Next, a simple model system consisting of a single source charged particle is studied to show that the maximum electrostatic energy error incurred by anM-order multipole expansion for the Yukawa potential is bounded above by the error of the equivalent multipole expansion for the Coulombic potential. Finally, timing and accuracy studies are presented for a variety of charged systems including polyelectrolyte chains, random distributions of charges inside a cube, and face-centered-cubic lattice charge configurations containing up to 103,823 charges.

Boschitsch, Alexander H.; Fenley, Marcia O.; Olson, Wilma K.

1999-05-01

11

Ewald sums for Yukawa potentials in quasi-two-dimensional systems  

SciTech Connect

In this article, the author derive Ewald sums for Yukawa potential for three-dimensional systems with two-dimensional periodicity. This sums are derived from the Ewald sums for Yukawa potentials with three-dimensional periodicity [G. Salin and J.-M. Caillol, J. Chem. Phys.113, 10459 (2000)] by using the method proposed by Parry for the Coulomb interactions [D. E. Parry, Surf. Sci.49, 433 (1975); 54, 195 (1976)].

Mazars, Martial [Laboratoire de Physique Theorique (UMR 8627), Universite de Paris XI, Batiment 210, 91405 Orsay Cedex (France)

2007-02-07

12

Scattering in the Attractive Yukawa Potential in the Limit of Strong Interaction  

NASA Astrophysics Data System (ADS)

Scattering in the attractive screened Coulomb (Yukawa) potential in the limit of strong interaction is investigated. It is shown that the scattering occurs mostly with large angles. The corresponding momentum-transfer cross section is calculated. The results are applied to estimate the ion drag force acting on an isolated micron-sized grain in low-pressure bulk plasmas.

Khrapak, S. A.; Ivlev, A. V.; Morfill, G. E.; Zhdanov, S. K.

2003-06-01

13

The fcc-bcc transition in screened-Coulomb (Yukawa) systems  

NASA Astrophysics Data System (ADS)

The dominant forces in the DLVO model of charge-stabilized colloidal suspensions are screened-Coulomb repulsions of Yukawa form. Point particles interacting via Yukawa repulsions form two ordered phases in equilibrium, bcc and fcc crystals. We have used calculations of the work required to transform between the two phases to determine the bcc-fcc transition line of point Yukawa systems to considerably higher precision than in previous work. The results and calculations of displacements from lattice sites are used to test a recent phenomenological theory(O.S. Vaulina, S.V. Vladimirov, O.F. Petrov, and V.E. Fortov. Phys. Rev. Lett. 88(24), 2002) for fcc-bcc transitions.

Hoy, Robert S.; Robbins, Mark O.

2004-03-01

14

Revision of FMM-Yukawa: An adaptive fast multipole method for screened Coulomb interactions  

NASA Astrophysics Data System (ADS)

FMM-YUKAWA is a mathematical software package primarily for rapid evaluation of the screened Coulomb interactions of N particles in three dimensional space. Since its release, we have revised and re-organized the data structure, software architecture, and user interface, for the purpose of enabling more flexible, broader and easier use of the package. The package and its documentation are available at http://www.fastmultipole.org/, along with a few other closely related mathematical software packages.New version program summaryProgram title: FMM-YukawaCatalogue identifier: AEEQ_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v2_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: GNU GPL 2.0No. of lines in distributed program, including test data, etc.: 78?704No. of bytes in distributed program, including test data, etc.: 854?265Distribution format: tar.gzProgramming language: FORTRAN 77, FORTRAN 90, and C. Requires gcc and gfortran version 4.4.3 or laterComputer: AllOperating system: AnyClassification: 4.8, 4.12Catalogue identifier of previous version: AEEQ_v1_0Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2331Does the new version supersede the previous version?: YesNature of problem: To evaluate the screened Coulomb potential and force field of N charged particles, and to evaluate a convolution type integral where the Green's function is the fundamental solution of the modified Helmholtz equation.Solution method: The new version of fast multipole method (FMM) that diagonalizes the multipole-to-local translation operator is applied with the tree structure adaptive to sample particle locations.Reasons for new version: To handle much larger particle ensembles, to enable the iterative use of the subroutines in a solver, and to remove potential contention in assignments for parallelization.Summary of revisions: The software package FMM-Yukawa has been revised and re-organized in data structure, software architecture, programming methods, and user interface. The revision enables more flexible use of the package and economic use of memory resources. It consists of five stages. The initial stage (stage 1) determines, based on the accuracy requirement and FMM theory, the length of multipole expansions and the number of quadrature points for diagonalization, and loads the quadrature nodes and weights that are computed off line. Stage 2 constructs the oct-tree and interaction lists, with adaptation to the sparsity or density of particles and employing a dynamic memory allocation scheme at every tree level. Stage 3 executes the core FMM subroutine for numerical calculation of the particle interactions. The subroutine can now be used iteratively as in a solver, while the particle locations remain the same. Stage 4 releases the memory allocated in Stage 2 for the adaptive tree and interaction lists. The user can modify the iterative routine easily. When the particle locations are changed such as in a molecular dynamics simulation, stage 2 to 4 can also be used together repeatedly. The final stage releases the memory space used for the quadrature and other remaining FMM parameters. Programs at the stage level and at the user interface are re-written in the C programming language, while most of the translation and interaction operations remain in FORTRAN. As a result of the change in data structures and memory allocation, the revised package can accommodate much larger particle ensembles while maintaining the same accuracy-efficiency performance. The new version is also developed as an important precursor to its parallel counterpart on multi-core or many core processors in a shared memory programming environment. Particularly, in order to ensure mutual exclusion in concurrent updates without incurring extra latency, we have replaced all the assignment statements at a source box that put its data to multiple target boxes with assignments at every target box that gather data from source boxes. This amounts to replacing the column versi

Zhang, Bo; Huang, Jingfang; Pitsianis, Nikos P.; Sun, Xiaobai

2010-12-01

15

Energies of Screened Coulomb Potentials.  

ERIC Educational Resources Information Center

|This article shows that, by applying the Hellman-Feynman theorem alone to screened Coulomb potentials, the first four coefficients in the energy series in powers of the perturbation parameter can be obtained from the unperturbed Coulomb system. (Author/HM)|

Lai, C. S.

1979-01-01

16

Formation of Coulomb crystal in presence of attractive overlapping Debye sphere potential  

SciTech Connect

The role of attractive overlapping Debye sphere (ODS) potential on dust crystal formation has been investigated by using molecular dynamics code. A comparative study on plasma crystal formation has been made between Yukawa and coupled Yukawa-ODS potential by calculating pair-correlation function, for different values of Coulomb coupling parameter {Gamma} and screening parameter {kappa}. From our study, it is seen that the attractive ODS potential becomes dominant beyond a critical radius than that of the Yukawa potential. This leads to the fact that the effect due to combined Yukawa-ODS potential depends more sensitively on {kappa}. From the comparison of the results for Yukawa and ODS potential with experimental results, it is observed that a close agreement is obtained for attractive ODS potential.

Baruah, Swati; Das, Nilakshi [Department of Physics, Tezpur University, Tezpur, Assam 784 028 (India)

2011-09-15

17

Estimation of Species Diffusivities in Dense Plasma Mixtures Modeled with the Yukawa Interionic Potential  

NASA Astrophysics Data System (ADS)

We employ classical molecular dynamics (MD) to investigate species diffusivity in binary Yukawa mixtures. The Yukawa potential is used to describe the screened Coulomb interaction between the ions, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We use Green-Kubo techniques to calculate self-diffusivities and the Maxwell-Stefan diffusivities, and evaluate the validity of the Darken relation over a range of thermodynamic conditions of the mixture. The inter-diffusivity (or mutual diffusivity) can then be related to the Maxwell-Stefan diffusivities through the thermodynamic factor. The latter requires knowledge of the equation of state of the mixture. To test these Green-Kubo approaches and to estimate the activity contribution we have also employed large-scale non-equilibrium MD. In these simulations we can extract the inter-diffusivity value by calculating the rate of broadening of the interface in a diffusion couple. We also explore thermodynamic conditions for possible non-Fickian diffusivity. The main motivation in this work is to build a model that describes the transport coefficients in binary Yukawa mixtures over a broad range of thermodynamic conditions up to 1keV.

Haxhimali, Tomorr; Rudd, Robert; Jackson, Julie; Surh, Michael; Cabot, William; Caspersen, Kyle; Greenough, Jeffrey; Graziani, Frank; Miller, Paul

2012-10-01

18

Borromean windows for H2+ with screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

We have carried out calculations to search Borromean windows for the bound F and G states of the H2+ system, where the nuclei and the electrons interact through a screened Coulomb (Yukawa-type) potential. The bound F and G state energies for different values of the screening parameters are obtained using correlated exponential wave functions in the framework of the Ritz variational principle. The critical values of the screening parameters for the bound F and G states are reported for which the H2+ system is stable, while all the possible fragments are unbound; that is, it shows windows for Borromean binding.

Kar, Sabyasachi; Ho, Y. K.

2012-07-01

19

Gauge orbits and the Coulomb potential  

SciTech Connect

If the color Coulomb potential is confining, then the Coulomb field energy of an isolated color charge is infinite on an infinite lattice, even if the usual UV divergence is lattice regulated. A simple criterion for Coulomb confinement is that the expectation value of timelike link variables vanishes in the Coulomb gauge, but it is unclear how this criterion is related to the spectrum of the corresponding Faddeev-Popov operator, which can be used to formulate a quite different criterion for Coulomb confinement. The purpose of this article is to connect the two seemingly different Coulomb confinement criteria, and explain the geometrical basis of the connection.

Greensite, J. [Physics and Astronomy Department, San Francisco State University, San Francisco, California 94132 (United States)

2009-08-15

20

Doubly excited nonautoionizing P , D , and F states of helium with Coulomb and screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

We have investigated the doubly excited P1,3e , D1,3o , and F1,3e nonautoionizing states of helium atom with Coulomb and screened Coulomb (Yukawa) potentials in the framework of Ritz variational principle. Highly accurate correlated exponential wave functions with exponents generated by a quasirandom process are used to represent the correlation effect. For the Coulomb case, the metastable bound-excited 2pnp P1e (3?n?5) , 2pnp P3e (2?n?5) , 2pnd D1,3o (3?n?9) , and 2pnf F1,3e (4?n?9) states energies are reported. Our upper-bound results for the 2pnd D1o (3?n?7) , 2pnf F1e (4?n?8) , D3o and F3e states are the lowest values up to this date. For the screened Coulomb case, the lower-lying metastable bound states energies for different screening parameters and for each spin states are also reported.

Kar, Sabyasachi; Ho, Y. K.

2009-06-01

21

FMM-Yukawa: An adaptive fast multipole method for screened Coulomb interactions  

NASA Astrophysics Data System (ADS)

A Fortran program package is introduced for the rapid evaluation of the screened Coulomb interactions of N particles in three dimensions. The method utilizes an adaptive oct-tree structure, and is based on the new version of fast multipole method in which the exponential expansions are used to diagonalize the multipole-to-local translations. The program and its full description, as well as several closely related packages are also available at http://www.fastmultipole.org/. This paper is a brief review of the program and its performance. Catalogue identifier: AEEQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL 2.0 No. of lines in distributed program, including test data, etc.: 12?385 No. of bytes in distributed program, including test data, etc.: 79?222 Distribution format: tar.gz Programming language: Fortran77 and Fortran90 Computer: Any Operating system: Any RAM: Depends on the number of particles, their distribution, and the adaptive tree structure Classification: 4.8, 4.12 Nature of problem: To evaluate the screened Coulomb potential and force field of N charged particles, and to evaluate a convolution type integral where the Green's function is the fundamental solution of the modified Helmholtz equation. Solution method: An adaptive oct-tree is generated, and a new version of fast multipole method is applied in which the "multipole-to-local" translation operator is diagonalized. Restrictions: Only three and six significant digits accuracy options are provided in this version. Unusual features: Most of the codes are written in Fortran77. Functions for memory allocation from Fortran90 and above are used in one subroutine. Additional comments: For supplementary information see http://www.fastmultipole.org/ Running time: The running time varies depending on the number of particles (denoted by N) in the system and their distribution. The running time scales linearly as a function of N for nearly uniform particle distributions. For three digits accuracy, the solver breaks even with direct summation method at about N=750. References:[1] L. Greengard, J. Huang, A new version of the fast multipole method for screened Coulomb interactions in three dimensions, J. Comput. Phys. 180 (2002) 642-658.

Huang, Jingfang; Jia, Jun; Zhang, Bo

2009-11-01

22

Doubly Excited 1,3 P e Resonance States of the Positronium Negative Ion with Coulomb and Screened Coulomb Potentials  

NASA Astrophysics Data System (ADS)

We have investigated the doubly excited 1,3 P e resonance states of positronium negative ion with Coulomb and screened Coulomb potentials using highly accurate correlated exponential wavefunctions. For Coulomb interaction, the stabilization and the complex-rotation methods are employed to extract resonance parameters (resonance positions and widths). We have obtained two 1 P e resonances and three 3 P e resonances below the n = 3 Ps threshold. In addition to Feshbach resonances lying below n = 3 Ps threshold, we have calculated one 3 P e shape resonances lying above the Ps ( n = 2) threshold. For screened Coulomb (Yukawa) interaction, we employ the stabilization method to extract resonance parameters as functions screening parameter. The resonance energies and widths for 1,3 P e resonance states of Ps- below the n = 3 Ps threshold for different screening parameters ranging from infinity (Coulomb case) to small values are reported, along with the Ps(3S) and Ps(3P) threshold energies. The screened Coulomb results for the 1,3 P e resonance states are reported for the first time in the literature.

Kar, Sabyasachi; Ho, Y. K.

2009-09-01

23

The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.  

ERIC Educational Resources Information Center

|Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)|

Francisco, E.; And Others

1988-01-01

24

TESTING YUKAWA-LIKE POTENTIALS FROM f(R)-GRAVITY IN ELLIPTICAL GALAXIES  

SciTech Connect

We present the first analysis of extended stellar kinematics of elliptical galaxies where a Yukawa-like correction to the Newtonian gravitational potential derived from f(R)-gravity is considered as an alternative to dark matter. In this framework, we model long-slit data and planetary nebula data out to 7 R{sub eff} of three galaxies with either decreasing or flat dispersion profiles. We use the corrected Newtonian potential in a dispersion-kurtosis Jeans analysis to account for the mass-anisotropy degeneracy. We find that these modified potentials are able to fit nicely all three elliptical galaxies and the anisotropy distribution is consistent with that estimated if a dark halo is considered. The parameter which measures the 'strength' of the Yukawa-like correction is, on average, smaller than the one found previously in spiral galaxies and correlates both with the scale length of the Yukawa-like term and the orbital anisotropy.

Napolitano, N. R. [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello, 16, 80131-Napoli (Italy); Capozziello, S.; Capaccioli, M. [Dipartimento di Scienze Fisiche, Universita di Napoli 'Federico II', Napoli (Italy); Romanowsky, A. J. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Tortora, C., E-mail: napolita@na.astro.it [Institut fuer Theoretische Physik, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057, Zuerich (Switzerland)

2012-04-01

25

Borromean bindings in H2^+ with screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

The stability of the bound P and D states of the H2^+ molecular ion, where the nuclei and the electrons interacts with a screened Coulomb (Yukawa-type) potential exp(-?r)/r, has been studied for different values of the screening parameters ?. We have determined the values of the bound ^3P^o (?=0, J=1), ^3P^o (?=1, J=1), ^1D^e (?=0, J=2), and ^1D^e (?=1, J=2) states energies for different values of the screening parameters using highly correlated exponential wave-functions in the framework of Ritz variational principle. The critical values of the screening parameters for the bound states are reported for which the H2^+ system is stable, while all the possible fragments are unbound, that is, it shows Borromean binding for the three-body systems [1]. We have determined the range of the Borromean windows for the lower-lying S, P and D states.[4pt] [1] A. Ghoshal and Y. K. Ho, Int. J. Quan. Chem. (2011), published online; and references therein.

Kar, Sabyasachi; Ho, Y. K.

2011-06-01

26

Unnatural parity states of helium with screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

Effect of screened Coulomb (Yukawa) potentials on the doubly excited meta-stable bound states and the resonance states with unnatural parities of the helium atom have been investigated in the framework of stabilization method using CI-type basis functions. A total of 54 resonances (6 each of 1Do and 3Do states, 12 each of 1Fe and 3Fe states, 9 each of 1Go and 3Go states) below the He+(3P) thresholds have been estimated by calculating the density of resonance states using a stabilization method. The resonances belong to the different 3lnlprime (n ge 3) series. We have also calculated the doubly excited 1,3Fe and 1,3Go meta-stable bound states of He atom below the He+ (2P) thresholds. The resonance energies and widths along with the meta-stable bound states energies are reported for various screening parameters. In free atom case, some of the F-wave resonance states and most of the cases, F- and G-wave resonance widths are reported for the first time.

Kar, Sabyasachi; Ho, Y. K.

27

Stark resonances of the Yukawa potential: Energies and widths, crossings and avoided crossings  

SciTech Connect

The resonance energy spectrum of a system interacting with the Yukawa potential and embedded in an external homogeneous and static electric field is investigated. The positions and widths of levels have been computed by using the complex coordinate rotation method. Interesting avoided-crossing and crossing effects appear.

Pawlak, Mariusz; Bylicki, Miroslaw [Instytut Fizyki, Uniwersytet Mikolaja Kopernika, ul. GrudziaPdzka 5, PL-87-100 Torun (Poland)

2011-02-15

28

Zero-range potential for particles interacting via Coulomb potential  

NASA Astrophysics Data System (ADS)

The zero-range potential is constructed for a system of two particles interacting via the Coulomb potential. The singular part of the asymptote of the wavefunction at the origin, which is caused by the common effect of the zero-range potential singularity and of the Coulomb potential, is explicitly calculated by using the Lippmann-Schwinger type integral equation. The singular pseudo potential is constructed from the requirement that it enforces the solution to the Coulomb Schrödinger equation to possess the calculated asymptotic behavior at the origin. This pseudo potential is then used for constructing a model of the imaginary absorbing potential for the positron-electron system. This potential allows us to treat the annihilation process in positron-electron collisions on the basis of the non-relativistic Schrödinger equation. The functional form of the pseudo potential constructed in this paper is analogous to the well known Fermi-Breit-Huang pseudo potential. The generalization of the optical theorem in the case of the imaginary absorbing potential in the presence of the Coulomb force is given in terms of the partial wave series.

Yakovlev, S. L.; Gradusov, V. A.

2013-01-01

29

Complex scaling in Lagrange-mesh calculations for Stark shifts and widths of the screened Coulomb potential  

NASA Astrophysics Data System (ADS)

In recent years, much attention has been drawn to atomic processes influenced by the screened Coulomb/Yukawa potential. In this work, the influence of the static electric field on screened Coulomb potential is investigated using the complex-coordinate rotation method in Lagrange-mesh calculations. The Stark shifts and half-widths of the ground and excited states of the screened Coulomb potentials are reported for a wide range of field strengths in different screening conditions. Comparisons are made with the available data. While the screening effects lead to the continuum lowering and level splitting phenomena, the Stark effects also cause the shifting and splitting of the energy levels. The competition between the screening effect and the external electric field is demonstrated and discussed. The broadening of the half-width due to the screening and Stark effects is observed.

Lin, C. Y.; Ho, Y. K.

2011-09-01

30

Instabilities in strongly coupled Yukawa liquids  

NASA Astrophysics Data System (ADS)

Yukawa systems are systems of charged particles that interact via a screened Coulomb (Yukawa) interaction. If the electrostatic potential energy between neighboring charged particles is much larger than their thermal (kinetic) energy but smaller than that required for crystallization the system is in the strongly coupled liquid phase. Various plasmas such as dusty plasmas or ultracold neutral plasmas can exist in this liquid phase. Here, we investigate several streaming instabilities in the strongly coupled liquid phase of dusty plasmas, including (1) a dust-dust instability and (2) a dust acoustic instability. Applications to possible experimental parameters are discussed.

Rosenberg, M.; Kalman, G. J.; Hartmann, P.

2011-11-01

31

An Analysis of 178Pb to 238U Isotopes with the Universal and Yukawa Proximity Potentials  

NASA Astrophysics Data System (ADS)

The alpha particle preformation and the penetration probability by the Yukawa proximity potential in the even-even nuclei from 178Pb to 238U are studied. Using the experimental values of the alpha decay half-lives and the decay energies, we extract the preformation factors and the penetration probabilities. We also calculate the assault frequencies and the decay constants. The obtained results are motivating.

Javadimanesh, E.; Hassanabadi, H.; Zarrinkamar, S.

2013-07-01

32

Quantum gravity and the Coulomb potential  

SciTech Connect

We apply a singularity-resolution technique utilized in loop quantum gravity to the polymer representation of quantum mechanics on R with the singular -1/|x| potential. On an equispaced lattice, the resulting eigenvalue problem is identical to a finite-difference approximation of the Schroedinger equation. We find numerically that the antisymmetric sector has an energy spectrum that converges to the usual Coulomb spectrum as the lattice spacing is reduced. For the symmetric sector, in contrast, the effect of the lattice spacing is similar to that of a continuum self-adjointness boundary condition at x=0, and its effect on the ground state is significant even if the spacing is much below the Bohr radius. Boundary conditions at the singularity thus have a significant effect on the polymer quantization spectrum even after the singularity has been regularized.

Husain, Viqar; Winkler, Oliver [Department of Mathematics and Statistics, University of New Brunswick, Fredericton, NB E3B 5A3 (Canada); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, N2L 2Y5 ON (Canada); Louko, Jorma [School of Mathematical Sciences, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2007-10-15

33

On the impossibility of defining adhesive hard spheres as sticky limit of a hard-sphere-Yukawa potential.  

PubMed

For fluids of molecules with short-ranged hard-sphere-Yukawa (HSY) interactions, it is proven that the Noro-Frenkel "extended law of corresponding states" cannot be applied down to the vanishing attraction range, since the exact HSY second virial coefficient diverges in such a limit. It is also shown that, besides Baxter's original approach, a fully correct alternative definition of "adhesive hard spheres" can be obtained by taking the vanishing-range-limit (sticky limit) not of a Yukawa tail, as is commonly done, but of a slightly different potential with a logarithmic-Yukawa attraction. PMID:21456673

Gazzillo, Domenico

2011-03-28

34

Auxiliary basis sets to approximate Coulomb potentials  

Microsoft Academic Search

We demonstrate accuracy and computational efficiency resulting from an approximate treatment of Coulomb operators which is based on the expansion of molecular electron densities in atom-centered auxiliary basis sets. This is of special importance in density functional methods which separate the treatment of Coulomb and exchange-correlation terms. Auxiliary basis sets are optimized as much as possible for isolated atoms and

Karin Eichkorn; Oliver Treutler; Holger Öhm; Marco Häser; Reinhart Ahlrichs; Marco Ser

1995-01-01

35

Additional -particle optical potential tests below the Coulomb barrier  

Microsoft Academic Search

New results of (,) and (,n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the -particle optical model potential (OMP) below the Coulomb barrier. Particular features of the -particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only -particle

M. Avrigeanu; V. Avrigeanu

2010-01-01

36

Multipole polarizabilities of helium and the hydrogen negative ion with Coulomb and screened Coulomb potentials  

SciTech Connect

We have carried out calculations of multipole polarizabilities of helium and the hydrogen negative ion interacting with pure Coulomb and screened Coulomb potentials using highly accurate correlated exponential wave functions with exponent generated by a quasirandom process. The dipole, quadrupole, and octupole polarizabilities for the ground 1s{sup 2} {sup 1}S{sup e} state for different screening parameters starting from infinity (pure Coulomb case) to small values of the screening parameters, are reported. The octupole polarizability of the hydrogen negative ion is reported for the first time in the literature. The bound 4 {sup 1}F state energy of helium for different screening parameters are also reported.

Kar, Sabyasachi [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Ho, Y. K. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106 (China)

2009-12-15

37

Potential energy landscapes of Th isotopes within the Lublin Strasbourg drop + Yukawa-folded model  

NASA Astrophysics Data System (ADS)

Advanced calculations of potential energy surfaces in a four-dimensional deformation space were performed for even–even Th isotopes using the macroscopic–microscopic method. The macroscopic part of the total energy was derived from the Lublin Strasbourg drop model. The Yukawa-folded potential was used to generate the single-particle spectra. The asymptotic Strutinsky shell-correction method and the Bardeen–Cooper–Schrieffer theory with approximate particle number projection were used to evaluate the microscopic part of the nuclear energy. Predictions for the ground-state masses and fission-barrier heights agree well with the experimental data. An accurate analysis of the computed multi-dimensional energy maps is in progress. Our preliminary results indicate that the present approach is capable of addressing the evolution of fission modality in the actinide region.

Nerlo-Pomorska, Bo?ena; Pomorski, Krzysztof; Schmitt, Christelle

2013-05-01

38

Semiclassical Simulation of Electron Scattering in Attractive Coulomb Potentials  

NASA Astrophysics Data System (ADS)

We study the performance of semiclassical dynamics simulations of electron scattering in the Wigner-transform time-dependent picture at few attractive Coulomb potentials and a two-slit potential. Heisenberg uncertainty and interference are compared to exact quantum dynamics. Serious numerical problems typically arise in classical and semiclassical simulations involving Coulomb potentials when particles approach each other and potential gradients (or accelerations) diverge. We introduce an accurate and efficient algorithm for dynamics simulations of particles with attractive potentials developed within the multi-institutional Cimarron Project. Rather than avoiding the singularity problem by using a pseudopotential, the algorithm predicts the outcome of close encounter two-body collisions for the true Coulomb potential by solving the Kepler problem analytically and corrects the trajectory for multiscattering with other particles in the system by using standard numerical techniques (e.g., velocity Verlet, or Gear Predictor corrector algorithms).

Markmann, Andreas; Graziani, Frank; Batista, Victor

2011-11-01

39

Spectral sum for the color-Coulomb potential in SU(3) Coulomb gauge lattice Yang-Mills theory  

SciTech Connect

We discuss the essential role of the low-lying eigenmodes of the Faddeev-Popov (FP) ghost operator on the confining color-Coulomb potential using SU(3) quenched lattice simulations in the Coulomb gauge. The color-Coulomb potential is expressed as a spectral sum of the FP ghost operator and has been explored by partially summing the FP eigenmodes. We take into account the Gribov copy effects that have a great impact on the FP eigenvalues and the color-Coulomb potential. We observe that the lowest eigenvalue vanishes in the thermodynamic limit much faster than that in the Landau gauge. The color-Coulomb potential at large distances is governed by the near-zero FP eigenmodes; in particular, the lowest one accounts for a substantial portion of the color-Coulomb string tension comparable to the Wilson string tension.

Nakagawa, Y.; Nakamura, A. [Research Institute for Information Science and Education, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8521 (Japan); Saito, T. [Integrated Information Center, Kochi University, Kochi, 780-8520 (Japan); Toki, H. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka, 567-0047 (Japan)

2010-03-01

40

Planar Massless Fermions in Coulomb and Aharonov-Bohm Potentials  

NASA Astrophysics Data System (ADS)

Solutions to the Dirac equation are constructed for a massless charged fermion in Coulomb and Aharonov-Bohm (AB) potentials in 2+1 dimensions. The Dirac Hamiltonian on this background is singular and needs a one-parameter self-adjoint extension, which can be given in terms of self-adjoint boundary conditions. We show that the virtual (quasistationary) bound states emerge in the presence of an attractive Coulomb potential when the so-called effective charges become overcritical and discuss a restructuring of the vacuum of the quantum electrodynamics when the virtual bound states emerge. We derive equations, which determine the energies and lifetimes of virtual bound states, find solutions of obtained equations for some values of parameters as well as analyze the local density of states (LDOS) as a function of energy in the presence of Coulomb and AB potentials.

Khalilov, V. R.; Lee, K. E.

2012-11-01

41

Classical and quantum scattering by a Coulomb potential  

NASA Astrophysics Data System (ADS)

For relativistic energies the small-angle classical cross section for scattering on a Coulomb potential agrees with the first Born approximation for quantum cross section for scalar particle only in the leading term. The disagreement in other terms can be avoided if the sum of all corrections to the first Born approximation for large enough Coulomb charge contains the classical terms which are independent of that charge. The difference in classical and quantum cross sections may be partly attributed to the fact that the relativistic quantum particle can rush through the field without interaction. We expect that smaller impact parameters and spin facilitate this effect.

Nikishov, A. I.

2009-01-01

42

Modified Hypernetted-Chain Equation for the Screened Coulomb Potential.  

National Technical Information Service (NTIS)

A modified form of the hypernetted-chain (HNC) equation is found that is suitable for the calculation of the pair-correlation function of a classical plasma. The changed equation involves only the short-range screened Coulomb potential and uses no further...

M. S. Cooper

1972-01-01

43

Crystallization limits of the two-term Yukawa potentials based on the entropy criterion  

NASA Astrophysics Data System (ADS)

We examine the fluid-solid transition for the potential with two Yukawa terms (one attractive and the other repulsive) and a hard core by exploration of the parameter space of (K1, Z1, and Z2), i.e., the parameters of interaction strength and interaction ranges, respectively. We apply the single-phase crystallization rule of Giaquinta and Giunta (1992) by searching for the conditions where the residual entropy reaches zero. To obtain accurate entropy properties, we adopt the self-consistent closure theory of the zero-separation genre. This closure gives accurate thermodynamic properties. The Ornstein-Zernike equation is solved to obtain the correlation functions. The structure factor S(q) is examined with respect to its cluster-cluster peak, whose value is another indication of phase transition according to Hansen and Verlet (1969). We discover that the parameter Z1 (which determines the range of attractive forces) is important in crystal formation, so long as sufficient attraction (parameter K1) is present. If the range of attraction is too narrow, strength alone is not adequate to satisfy the Giaquinta rule or to solidify at given concentration and temperature. The control of the range of repulsion rests with the Z2-parameter. Its variations can bring about a high peak in S(q) at zero wave number (i.e., at q=0). Implications for the crystallization of protein and colloidal solutions are discussed.

Lee, Lloyd L.; Hara, Michael C.; Simon, Steven J.; Ramos, Franklin S.; Winkle, Andrew J.; Bomont, Jean-Marc

2010-02-01

44

Calculation of Transport Coefficients in Binary Yukawa Mixtures  

NASA Astrophysics Data System (ADS)

We employ classical molecular dynamics (MD) to estimate species diffusivity and viscosity in binary Yukawa Mixtures. The Yukawa potential is used to describe the screened Coulomb interaction between the ions, providing the basis for models of dense stellar materials, inertial confined plasmas, and colloidal particles in electrolytes. We calculate transport coefficients in equilibrium simulations using the Green-Kubo relation over a range of thermodynamic conditions including the viscosity and the self-diffusivity for each component of the mixture. The inter-diffusivity (or mutual diffusivity) can then be related to the self-diffusivities by using a generalization of the Darken equation. We have also employed non-equilibrium MD to estimate inter-diffusivity during the broadening of the interface between two regions each with a high concentration of either species. The main motivation in this work is to build a model that describes the transport coefficients in binary Yukawa mixtures over a broad range of thermodynamic conditions.

Haxhimali, Tomorr; Rudd, Robert

2012-02-01

45

Self-diffusion in strongly coupled Yukawa systems (complex plasmas)  

NASA Astrophysics Data System (ADS)

We show that the idea of mapping between the Newtonian and Brownian diffusivities proposed and tested on a class of particle systems interacting via soft and ultra-soft potentials (inverse-power-law, Gaussian core, Hertzian, and effective star-polymer) by Pond et al. [Soft Matter 7, 9859 (2011)] is also applicable to the Yukawa (screened Coulomb) interaction. Some consequences of this result with respect to self-diffusion in strongly coupled complex (dusty) plasmas are discussed.

Khrapak, Sergey A.; Vaulina, Olga S.; Morfill, Gregor E.

2012-03-01

46

{alpha}-particle optical potential tests below the Coulomb barrier  

SciTech Connect

The results of two recent papers concerning ({alpha},{gamma}) and ({alpha},n) reaction cross sections close to the reaction thresholds are discussed with regard to predictions of a recent {alpha}-particle regional optical potential. It is found that the new measured cross sections are rather well described especially for the dominant reaction channels. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of a former regional potential obtained by analysis of {alpha}-particle elastic scattering alone at higher energies. Additional limitations of statistical model calculations for minor reaction channels are also discussed.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P. O. Box MG-6, Bucharest-Magurele (Romania)

2009-02-15

47

Heavy quarks, gluons and the confinement potential in Coulomb gauge  

SciTech Connect

We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

Popovici, Carina; Watson, Peter; Reinhardt, Hugo [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-23

48

Closure of orbits and dynamical symmetry of screened Coulomb potential and isotropic harmonic oscillator  

NASA Astrophysics Data System (ADS)

It is shown that for any central potential V(r) there exist a series of conserved aphelion and perihelion vectors R~=p×L-g(r)r, g(r)=rV'(r). However, if and only if V(r) is a pure or screened Coulomb potential, R~ and L constitute an SO4 algebra in the subspace spanned by the degenerate states with a given energy eigenvalue E<0 at the aphelia and perihelia (?=0). For a pure Coulomb potential, R~ is reduced to the Pauli-Runge-Lenz (PRL) vector R and for a screened Coulomb potential R~ is reduced to the extended PRL vector R'. While dR/dt=0 always holds, dR'/dt=0 holds only at the aphelia and perihelia. Moreover, the space spanning the SO4 algebra for a screened Coulomb potential is smaller than that for a pure Coulomb potential. The relation of closed orbits for a screened Coulomb potential with that for a pure Coulomb potential is clarified. The ratio of the radial frequency ?r and angular frequency ??, ?r/??=?=1 for a pure Coulomb potential irrespective of the angular momentum L and energy E(<0). For a screened Coulomb potential ? is determined by the angular momentum L, and when ? is any rational number (?<1), the orbit is closed. The situation for a pure or screened isotropic harmonic oscillator is similar.

Zeng, Bei; Zeng, Jin-Yan

2002-02-01

49

Color Coulomb potential in Yang-Mills theory from Hamiltonian flows  

NASA Astrophysics Data System (ADS)

We consider the Hamiltonian formulation of Yang-Mills theory in the Coulomb gauge and apply the recently developed technique of Hamiltonian flows. We formulate a flow equation for the color Coulomb potential which allows for a scaling solution that results in an almost linearly rising confining potential.

Leder, Markus; Reinhardt, Hugo; Weber, Axel; Pawlowski, Jan M.

2012-11-01

50

Screened Coulomb potentials for astrophysical nuclear fusion reactions  

NASA Astrophysics Data System (ADS)

The electron-screening acceleration of laboratory fusion reactions at astrophysical energies is an unsolved problem of great importance to astrophysics. That effect is modeled here by considering the fusion of hydrogen-like atoms whose electron probability density is used in Poisson's equation in order to derive the corresponding screened Coulomb potential energy. That way atomic excitations and deformations of the fusing atoms can be taken into account. Those potentials are then treated semiclassically in order to obtain the screening (accelerating) factor of the reaction. By means of the proposed model the effect of a superstrong magnetic field on laboratory hydrogen fusion reactions is investigated here for the first time showing that, despite the considerable increase in the cross-section of the dd reaction, the pp reaction is still too slow to justify experimentation. The proposed model is finally applied on the H2 d, p H3 fusion reaction describing satisfactorily the experimental data although some ambiguity remains regarding the molecular nature of the deuteron target. Notably, the present method gives a sufficiently high screening energy for hydrogen fusion reactions so that the take-away energy of the spectator nucleus can also be taken into account.

Liolios, T. E.

51

Phase-integral expressions for continuum wave functions in screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

Formulas for the phase and the normalization of the continuum wave function pertaining to the scattering problem with at most one turning point are obtained in a general form based on a kind of arbitrary-order phase-integral approximation. The accuracy of the formulas is illustrated by application to the Yukawa potential. The phase-integral expressions are analytically simple and have a wider range of applicability than the perturbation-theory formulas for the normalization obtained by J. McEnnan, L. Kissel, and R. H. Pratt [Phys. Rev. A 13, 532 (1976)] and for the phase shift obtained by A. Bechler and R. H. Pratt [Phys. Rev. A 28, 1190 (1983)]. The perturbation-theory phase-shift formula, e.g., for the Yukawa potential, is, however, seen to have some advantages due to its simple structure.

Yngve, Staffan; Linnaeus, Staffan

1988-12-01

52

Additional alpha-particle optical potential tests below the Coulomb barrier  

Microsoft Academic Search

New results of (alpha,gamma) and (alpha,n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the alpha-particle optical model potential (OMP) below the Coulomb barrier. Particular features of the alpha-particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only alpha-particle

M. Avrigeanu; V. Avrigeanu

2010-01-01

53

Perturbed Coulomb potentials in the Klein-Gordon equation via the asymptotic iteration method  

SciTech Connect

The asymptotic iteration method is used to construct the exact energy eigenvalues for a Lorentz vector or a Lorentz scalar, and an equally mixed Lorentz vector and Lorentz scalar Coulombic potentials. Highly accurate and rapidly converging ground-state energies for Lorentz vector Coulomb with a Lorentz vector or a Lorentz scalar linear potential, V(r)=-{lambda}{sub 1}/r+krandV(r)=-{lambda}{sub 1}/randW(r)=kr, respectively, are obtained.

Barakat, T. [Physics Department, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)], E-mail: tbarakat@ksu.edu.sa

2009-03-15

54

Additional {alpha}-particle optical potential tests below the Coulomb barrier  

SciTech Connect

New results of ({alpha},{gamma}) and ({alpha},n) reaction cross section measurements close to the reaction thresholds support the setting up of recent parameters of the {alpha}-particle optical model potential (OMP) below the Coulomb barrier. Particular features of the {alpha}-particle optical potential at energies below the Coulomb barrier explain the failure of using the OMP parameters obtained by analysis of only {alpha}-particle elastic scattering at higher energies.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, RO-077125 Bucharest-Magurele (Romania)

2010-03-15

55

Solutions to the 1d Klein Gordon equation with cut-off Coulomb potentials  

NASA Astrophysics Data System (ADS)

In a recent paper by Barton [G. Barton, J. Phys. A: Math. Gen. 40 (2007) 1011], the 1-dimensional Klein Gordon equation was solved analytically for the non-singular Coulomb-like potential V(|x|)=-?/(|x|+a). In the present Letter, these results are completely confirmed by a numerical formulation that also allows a solution for an alternative cut-off Coulomb potential V(|x|)=-?/|x|, |x|>a, and otherwise V(|x|)=-?/a.

Hall, Richard L.

2007-12-01

56

Bound heavy- and light-quark systems in a non-Coulombic logarithmic-potential model  

SciTech Connect

A previous fit of the charmonium and UPSILON spectra by a simple non-Coulombic logarithmic potential is modified to include systems containing up or down and strange quarks. It is found that the spectra of both light and heavy mesons, particularly, the 1P and 2P state splittings of the UPSILON system can be satisfactorily explained without taking into account the short-distance Coulombic part of the potential as suggested by QCD.

Jena, S.N.; Rath, D.P.

1985-11-01

57

The Coulomb potential and the paradoxes of PT symmetrization  

NASA Astrophysics Data System (ADS)

Besides the standard quantum version of the Coulomb/Kepler problem, an alternative quantum model with not too dissimilar phenomenological (i.e., spectral and scattering) as well as mathematical (i.e., exact-solvability) properties may be formulated and solved. Several aspects of this model are described. The paper is made self-contained by explaining the underlying innovative quantization strategy which assigns an entirely new role to symmetries.

Znojil, Miloslav

2013-10-01

58

Leptonic dynamical Yukawa couplings  

NASA Astrophysics Data System (ADS)

A dynamical origin of the Yukawa couplings is a promising scenario to explain the flavour puzzle. The focus of this letter is set on the role of the neutrino Majorana character: when an O(2)N flavour symmetry acts on the right-handed neutrino sector, the minimum of the scalar potential allows for large mixing angles -in contrast to the simplest quark case- and predicts a maximal Majorana phase. This leads to a strong correlation between neutrino mass hierarchy and mixing pattern. Realistic solutions point to the existence of three heavy right-handed neutrinos.

Alonso, R.; Gavela, M. B.; Hernández, D.; Merlo, L.; Rigolin, S.

2013-08-01

59

Criterion for bulk behavior of a Yukawa disk  

SciTech Connect

A Yukawa disk is a two-dimensional system of n particles interacting through a Yukawa potential (i.e., a screened Coulomb or Debye potential) with Debye length {lambda} and confined in an isotropic parabolic well where the single-particle oscillation frequency is {omega}{sub 0}. One example of a Yukawa disk is a two-dimensional complex (dusty) plasma. The emergence of bulk (macroscopic) behavior in a strongly coupled Yukawa disk is studied by considering the dependence of the normalized, squared breathing frequency {omega}{sub br}{sup 2}/{omega}{sub 0}{sup 2} (i.e., the bulk modulus) on n, {lambda}, the disk radius R{sub 0}, and the nearest-neighbor distance a. An analytical expression for {omega}{sub br}{sup 2}/{omega}{sub 0}{sup 2} is derived for the bulk limit, R{sub 0}>>{lambda}, with a/{lambda} finite. In the plasma regime a < or approx. {lambda}, so that each particle interacts with many other particles, {omega}{sub br}{sup 2}/{omega}{sub 0}{sup 2}{approx_equal}4 independent of a/{lambda}. In the nearest-neighbor regime a > or approx. {lambda}, short-range interactions dominate and {omega}{sub br}{sup 2}/{omega}{sub 0}{sup 2}{approx}a/{lambda}. Computational solutions of the model for n=100-3200 particles approach the theoretical bulk limit as n increases. Solutions with n=3200 and a/{lambda} between 0.25 and 0.5 are found to give the best approximation to an unbounded plasma.

Sheridan, T. E. [Department of Physics and Astronomy, Ohio Northern University, Ada, Ohio 45810 (United States)

2007-03-15

60

Creation of planar charged fermions in Coulomb and Aharonov-Bohm potentials  

NASA Astrophysics Data System (ADS)

The creation of charged fermions from the vacuum by a Coulomb field in the presence of an Aharonov-Bohm (AB) potential are studied in 2+1 dimensions. The process is governed by a (singular) Dirac Hamiltonian that requires the supplementary definition in order for it to be treated as a self-adjoint quantum-mechanical operator. By constructing a one-parameter self-adjoint extension of the Dirac Hamiltonian, specified by boundary conditions, we describe the (virtual bound) quasistationary states with "complex energy" emerging in an attractive Coulomb potential, derive for the first time, complex equations (depending upon the electron spin and the extension parameter) for the quasistationary state "complex energy". The constructed self-adjoint Dirac Hamiltonians in Coulomb and AB potentials are applied to provide a correct description to the low-energy electron excitations, as well as the creation of charged quasiparticles from the vacuum in graphene by the Coulomb impurity in the presence of AB potential. It is shown that the strong Coulomb field can create charged fermions for some range of the extension parameter.

Khalilov, V. R.

2013-08-01

61

Liquid-vapor phase diagram and surface properties in oppositely charged colloids represented by a mixture of attractive and repulsive Yukawa potentials.  

PubMed

The liquid-vapor phase diagrams of equal size diameter ? binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fern?andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006); A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006)]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length ?. Caballero found stability for values of ?? up to 20 while Fortini reported stability for ?? up to 20 while Fortini reported stability for ?? ? 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of ??. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of ?? > 20 and that the critical temperatures have a maximum value at around ?? = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials. PMID:23406133

Chapela, Gustavo A; del Río, Fernando; Alejandre, José

2013-02-01

62

Energy dependence of the nucleus-nucleus potential close to the Coulomb barrier  

SciTech Connect

The nucleus-nucleus interaction potentials in heavy-ion fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory for the mass symmetric reactions {sup 16}O + {sup 16}O, {sup 40}Ca + {sup 40}Ca, and {sup 48}Ca + {sup 48}Ca and the mass asymmetric reactions {sup 16}O + {sup 40,} {sup 48}Ca, {sup 40}Ca + {sup 48}Ca, {sup 16}O + {sup 208}Pb, and {sup 40}Ca + {sup 90}Zr. When the c.m. energy is much higher than the Coulomb barrier energy, potentials deduced with the microscopic theory identify with the frozen density approximation. As the c.m. energy decreases and approaches the Coulomb barrier, potentials become energy dependent. This dependence indicates dynamical reorganization of internal degrees of freedom and leads to a reduction of the 'apparent' barrier felt by the two nuclei during fusion of the order of 2-3% compared to the frozen density case. Several examples illustrate that the potential landscape changes rapidly when the c.m. energy is in the vicinity of the Coulomb barrier energy. The energy dependence is expected to have a significant role on fusion around the Coulomb barrier.

Washiyama, Kouhei [GANIL, CEA and IN2P3, Boite Postale 55027, F-14076 Caen Cedex 5 (France); Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Lacroix, Denis [GANIL, CEA and IN2P3, Boite Postale 55027, F-14076 Caen Cedex 5 (France)

2008-08-15

63

Klein-Gordon Equation for the Coulomb Potential in Noncommutative Space  

NASA Astrophysics Data System (ADS)

In this paper the stationary Klein-Gordon equation is considered for the Coulomb potential in noncommutative space. The energy shift due to noncommutativity is obtained via the perturbation theory. Furthermore, we show that the degeneracy of the initial spectral line is broken in transition from commutative space to noncommutative space.

Motavalli, Hossein; Akbarieh, Amin Rezaei

64

Proton optical potential and scattering matrix for tin nuclei at sub-Coulomb energies  

Microsoft Academic Search

A unified set of parameters of the proton optical potential is sought for tin nuclei at energies below the Coulomb barrier which gives a good description of the set of experimental data on the total cross sections for the pn reaction and the angular distributions of elastically scattered protons for E\\/sub p\\/< or = 10 MeV and which gives reliable

B. Y. Guzhovskii; B. M. Dzyuba

1981-01-01

65

Wheeler-DeWitt Equation with a Screened-Coulomb Dilation Potential  

NASA Astrophysics Data System (ADS)

Wheeler-DeWitt equation for anisotropically expanding homogeneous high-dimension spaces is approximately solved under a screened-coulomb dilation potential via an appropriate approximation. The wave function is reported in terms of the Jacobi polynomials and eigenvalues and eigenfunctions are reported via the Nikiforov-Uvarov technique.

Zarrinkamar, S.; Hassanabadi, H.; Rajabi, A. A.

2013-11-01

66

The algebra of the quantum nondegenerate three-dimensional Kepler-Coulomb potential  

SciTech Connect

The classical generalized Kepler-Coulomb potential, introduced by Verrier and Evans, corresponds to a quantum superintegrable system, with quadratic and quartic integrals of motion. In this paper we show that the algebra of the integrals is a quadratic ternary algebra, i.e a quadratic extension of a Lie triple system.

Tanoudis, Y.; Daskaloyannis, C., E-mail: daskalo@math.auth.gr [Aristotle University of Thessaloniki, Mathematics Department (Greece)

2011-07-15

67

Dimensional phase transition in small Yukawa clusters  

SciTech Connect

We investigate the one- to two-dimensional zigzag transition in clusters consisting of a small number of particles interacting through a Yukawa (Debye) potential and confined in a two-dimensional biharmonic potential well. Dusty (complex) plasma clusters with n<=19 monodisperse particles are characterized experimentally for two different confining wells. The well anisotropy is accurately measured, and the Debye shielding parameter is determined from the longitudinal breathing frequency. Debye shielding is shown to be important. A model for this system is used to predict equilibrium particle configurations. The experiment and model exhibit excellent agreement. The critical value of n for the zigzag transition is found to be less than that predicted for an unshielded Coulomb interaction. The zigzag transition is shown to behave as a continuous phase transition from a one-dimensional to a two-dimensional state, where the state variables are the number of particles, the well anisotropy and the Debye shielding parameter. A universal critical exponent for the zigzag transition is identified for transitions caused by varying the Debye shielding parameter.

Sheridan, T. E.; Wells, K. D. [Department of Physics and Astronomy, Ohio Northern University, Ada, Ohio 45810 (United States)

2010-01-15

68

Phase diagram of Yukawa systems: Model for charge-stabilized colloids  

NASA Astrophysics Data System (ADS)

The phase diagram of particles interacting through a repulsive screened Coulomb (Yukawa) potential has been calculated. Such interactions describe charge-stabilized colloidal suspensions and provide a potential of variable shape which can be used to test general ideas about phase transitions, including the phenomenological Hansen-Verlet and Lindemann rules. Competition between bcc and fcc solid phases was explored through calculations of the free-energy difference. For a range of screening lengths we found a transition from a low-temperature fcc phase to a high-temperature bcc phase.

Kremer, Kurt; Robbins, Mark O.; Grest, Gary S.

1986-11-01

69

Numerical treatment of the long-range Coulomb potential with Berggren bases  

SciTech Connect

The Schroedinger equation incorporating the long-range Coulomb potential takes the form of a Fredholm equation whose kernel is singular on its diagonal when represented by a basis bearing a continuum of states, such as in a Fourier-Bessel transform. Several methods have been devised to tackle this difficulty, from simply removing the infinite range of the Coulomb potential with a screening or cut function to using discretizing schemes which take advantage of the integrable character of Coulomb kernel singularities. However, they have never been tested in the context of Berggren bases, which allow many-body nuclear wave functions to be expanded with halo or resonant properties within a shell-model framework. It is thus the object of this paper to test different discretization schemes of the Coulomb potential kernel in the framework of complex-energy nuclear physics. For that, the Berggren basis expansion of proton states pertaining to the sd shell arising in the A{approx}20 region, being typically resonant, will be effected. Apart from standard frameworks involving a cut function or analytical integration of singularities, a new method will be presented which replaces diagonal singularities by finite off-diagonal terms. It will be shown that this methodology surpasses in precision the two former techniques.

Michel, N. [Department of Physics, Post Office Box 35 (YFL), University of Jyvaeskylae, FI-40014 Jyvaeskylae (Finland)

2011-03-15

70

New form for the coulomb potential in crystals  

SciTech Connect

The Poisson equation is solved by the Green`s function method. A nonstandard approach is used in the calculation of the potential of the electron cloud. It is shown that the lattice contribution to the electron density is given by a universal function of distance. The potential is determined in the whole unit cell and has an expression convenient for practical realization. The corresponding formulas are easily generalized to complex crystals.

Nazhalov, A.I. [Altai State Univ. (Russian Federation)

1995-11-01

71

The {sup 6}He Optical Potential at energies around the Coulomb barrier  

SciTech Connect

We present an Optical Model (OM) study of {sup 6}He on {sup 208}Pb elastic scattering data, measured at laboratory energies around the Coulomb barrier (E{sub lab} = 14, 16, 18, 22, and 27 MeV)[1]. For the projectile-target bare interaction, we use the microscopic Sao Paulo Potential (SPP). This bare interaction is supplemented with a Coulomb Dipole Polarization (CDP) potential, as well as a diffuse complex Woods-Saxon potential. Four-body Continuum-Discretized-Coupled-Channels (CDCC) calculations have been performed in order to support the optical model analysis. We have also studied the alpha channel, which is the dominant reaction process. In the analysis of this channel, we compare the angular and energy distributions of the alpha particles measured at 22 MeV, with Distorted Wave Born Approximation (DWBA) calculations.

Fernandez-Garcia, J. P.; Alvarez, M. A. G. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain); CNA, Universidad de Sevilla, c/Thomas Alva Edison 7, 41092 Sevilla (Spain); Rodriguez-Gallardo, M. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain); Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain); Moro, A. M. [Dpto. de FAMN, Universidad de Sevilla, Apdo. 1065, 41080 Sevilla (Spain)

2010-04-26

72

Potential splitting approach to multichannel Coulomb scattering: The driven Schroedinger equation formulation  

SciTech Connect

In this paper we suggest an approach for the multichannel Coulomb scattering problem. The Schroedinger equation for the problem is reformulated in the form of a set of inhomogeneous equations with a finite-range driving term. The boundary conditions at infinity for this set of equations have been proven to be purely outgoing waves. The formulation presented here is based on splitting the interaction potential into a finite-range core part and a long-range tail part. The conventional matching procedure coupled with the integral Lippmann-Schwinger equations technique is used in the formal theoretical basis of this approach. The reformulated scattering problem is suitable for application in the exterior complex scaling technique: the practical advantage is that after complex scaling, the problem is reduced to a boundary problem with zero boundary conditions. The Coulomb wave functions are used only at a single point; if this point is chosen to be at a sufficiently large distance, on using the asymptotic expansion of Coulomb functions, one may completely avoid the Coulomb functions in the calculations. The theoretical results are illustrated with numerical calculations for two models.

Volkov, M. V. [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Department of Quantum Mechanics, St. Petersburg State University, RU-198504 St Petersburg (Russian Federation); Yakovlev, S. L.; Yarevsky, E. A. [Department of Computational Physics, St. Petersburg State University, RU-198504 St Petersburg (Russian Federation); Elander, N. [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden)

2011-03-15

73

Potential splitting approach to multichannel Coulomb scattering: The driven Schrödinger equation formulation  

NASA Astrophysics Data System (ADS)

In this paper we suggest an approach for the multichannel Coulomb scattering problem. The Schrödinger equation for the problem is reformulated in the form of a set of inhomogeneous equations with a finite-range driving term. The boundary conditions at infinity for this set of equations have been proven to be purely outgoing waves. The formulation presented here is based on splitting the interaction potential into a finite-range core part and a long-range tail part. The conventional matching procedure coupled with the integral Lippmann-Schwinger equations technique is used in the formal theoretical basis of this approach. The reformulated scattering problem is suitable for application in the exterior complex scaling technique: the practical advantage is that after complex scaling, the problem is reduced to a boundary problem with zero boundary conditions. The Coulomb wave functions are used only at a single point; if this point is chosen to be at a sufficiently large distance, on using the asymptotic expansion of Coulomb functions, one may completely avoid the Coulomb functions in the calculations. The theoretical results are illustrated with numerical calculations for two models.

Volkov, M. V.; Yakovlev, S. L.; Yarevsky, E. A.; Elander, N.

2011-03-01

74

Theoretical and observed potential energy curves for neutral 4-unit charge Coulomb systems containing antihydrogen  

Microsoft Academic Search

Comparing observed and theoretical potential energy curves for natural and exotic neutral 4-unit charge Coulomb systems like HH and HantiH leads to new conclusions on the effect of charge-antisymmetry in nature. With singularities in the HantiH PEC as found by Aldrovandi and Puget and by Junker and Bardsley, any cusp in the HantiH PEC significantly affects the annihilation cross section.

G. Van Hooydonk

2005-01-01

75

Coulomb nuclear interference as a tool to investigate the nuclear potential  

Microsoft Academic Search

The sub-barrier excitation function of the octupole vibrational state at 2.615 MeV in Pb208 is analyzed within the coupled-channels framework. It is shown that the position of the minimum in the excitation function, which is due to the destructive interference of the Coulomb and nuclear scattering amplitudes, is very sensitive to the nuclear potential for both the ground state and

M. Evers; D. J. Hinde; M. Dasgupta; D. H. Luong; R. Rafiei; R. Du Rietz

2010-01-01

76

Coulomb nuclear interference as a tool to investigate the nuclear potential  

Microsoft Academic Search

The sub-barrier excitation function of the octupole vibrational state at 2.615 MeV in ²°Pb is analyzed within the coupled-channels framework. It is shown that the position of the minimum in the excitation function, which is due to the destructive interference of the Coulomb and nuclear scattering amplitudes, is very sensitive to the nuclear potential for both the ground state and

M. Evers; D. J. Hinde; M. Dasgupta; D. H. Luong; R. Rafiei; R. du Rietz

2010-01-01

77

Analytic solution of the Schroedinger equation for the Coulomb-plus-linear potential. I. The wave functions  

SciTech Connect

We solve the Schroedinger equation for a quark-antiquark system interacting via a Coulomb-plus-linear potential, and obtain the wave functions as power series, with their coefficients given in terms of the combinatorics functions.

Plante, Guillaume; Antippa, Adel F. [Physics Department, Columbia University, New York, New York 10027 (United States); Departement de Physique, Universite du Quebec a Trois-Rivieres, Trois-Rivieres, Quebec, G9A 5H7 (Canada)

2005-06-01

78

Doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials  

SciTech Connect

We have investigated the doubly excited {sup 1,3}P{sup e} resonance states of helium and the hydrogen negative ion interacting with Coulomb and screened Coulomb potentials using exponential correlated wave functions. In the pure Coulomb case, calculations have been carried out by using the complex-coordinate rotation and the stabilization method. The {sup 1}P{sup e} resonance states of He below the N= 3, 4, and 5 thresholds of He{sup +}, and the {sup 3}P{sup e} resonance states of He below the N= 3 thresholds of He{sup +}, are reported. The 5p{sup 2} {sup 3}P{sup e} state, which has attracted recent interest, is also reported and discussed. In the screened Coulomb case, we have used the stabilization method to obtain two different series (3pnp and 3dnd) of resonance states below the N= 3 He{sup +} threshold as a function of the screening parameters. Resonance widths for the 3dnd series show some interesting behaviors. The resonance parameters (position and width) for helium and the hydrogen negation ion as functions of the screening parameters are reported.

Kar, Sabyasachi [Center for Theoretical Atomic and Molecular Physics, The Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Ho, Y. K. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106 (China)

2011-04-15

79

Arbitrary l-Wave Solutions of the Schrödinger Equation for the Screen Coulomb Potential  

NASA Astrophysics Data System (ADS)

Using improved approximate schemes for centrifugal term and the singular factor 1/r appearing in potential itself, we solve the Schrödinger equation with the screen Coulomb potential for arbitrary angular momentum state l. The bound state energy levels are obtained. A closed form of normalization constant of the wave functions is also found. The numerical results show that our results are in good agreement with those obtained by other methods. The key issue is how to treat two singular points in this quantum system.

Dong, Shishan; Sun, Guo-Hua; Dong, Shi-Hai

2013-06-01

80

Hypervirial 1/N expansion for the bound-state energy spectrum of the generalized exponential-cosine-screened Coulomb potential  

NASA Astrophysics Data System (ADS)

The bound-state energy spectrum of an N-dimensional generalized exponential cosine-screened Coulomb potential is obtained by employing the N-dimensional hypervirial equations and the Hellman-Feynman theorem. The present method is shown to provide a useful 1/N expansion scheme which can be used as an alternative to the method of Mlodinow and Shatz [J. Math. Phys. 25, 943 (1984)] for the determination of the energy eigenvalues of the screened Coulomb potentials.

Chatterjee, Ashok

1987-03-01

81

Theoretical and observed potential energy curves for neutral 4-unit charge Coulomb systems containing antihydrogen  

Microsoft Academic Search

Comparing observed and theoretical potential energy curves for natural and\\u000aexotic neutral 4-unit charge Coulomb systems like HH and HantiH leads to new\\u000aconclusions on the effect of charge-antisymmetry in nature. With singularities\\u000ain the HantiH PEC as found by Aldrovandi and Puget and by Junker and Bardsley,\\u000aany cusp in the HantiH PEC significantly affects the annihilation cross\\u000asection.

G. Van Hooydonk

2005-01-01

82

Polarizabilities of two-electron positive ions with screened Coulomb potentials  

SciTech Connect

We have carried out calculations of the polarizabilities of the two-electron positive ions Li{sup +}, Be{sup 2+}, B{sup 3+}, C{sup 4+}, N{sup 5+}, and O{sup 6+} interacting with screened Coulomb potentials. Highly accurate correlated exponential wave functions are used to represent correlation effects on the charged particles. The dipole, quadrupole, and octupole polarizabilities for the screening parameters in the range 0-1a{sub 0}{sup -1} are reported. Reported results for the unscreened case are comparable with the available results and for the screened case show some interesting behavior with increasing nuclear charge.

Jiang Zishi; Kar, Sabyasachi [Center for Theoretical Atomic and Molecular Physics, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Ho, Y. K. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106 (China)

2011-07-15

83

Biography of Hideki Yukawa  

NASA Astrophysics Data System (ADS)

Life history of Hideki Yukawa is described, together with that of Sin-itiro Tomonaga. They grew upiin Kyoto city and were classmate. Their independency and collaboration had contributed to the growth of physics research in Japan after the end of WWII.

Sato, Humitaka

2008-06-01

84

Fusion and Quasi-elastic scattering around the Coulomb barrier: determination of inter-nucleus potential  

SciTech Connect

We invert experimental data for heavy-ion fusion cross sections at energies well below the Coulomb barrier in order to directly determine the internucleus potential between the colliding nuclei. In contrast to the previous applications of the inversion formula, we explicitly take into account the effect of channel couplings on fusion reactions, by assuming that fusion cross sections at deep subbarrier energies are governed by the lowest barrier in the barrier distribution. The surface region of the internuclear potential is determined from quasi-elastic scattering at deep subbarrier energies, while the inner part is determined with the WKB formula. We apply this procedure to the {sup 16}O+{sup 144}Sm and {sup 16}O+{sup 208}Pb reactions, and find that the inverted internucleus potential are much thicker than phenomenological potentials.

Hagino, K. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

2009-05-04

85

Singularity Structures in Coulomb-Type Potentials in Two-Body Dirac Equations of Constraint Dynamics  

SciTech Connect

Two-body Dirac equations (TBDE) of Dirac's relativistic constraint dynamics have been successfully applied to obtain a covariant nonperturbative description of QED and QCD bound states. Coulomb-type potentials in these applications lead naively in other approaches to singular relativistic corrections at short distances that require the introduction of either perturbative treatments or smoothing parameters. We examine the corresponding singular structures in the effective potentials of the relativistic Schroedinger equation obtained from the Pauli reduction of the TBDE. We find that the relativistic Schroedinger equation leads in fact to well-behaved wave function solutions when the full potential and couplings of the system are taken into account. The most unusual case is the coupled triplet system with S=1 and L={l_brace}(J-1),(J+1){r_brace}. Without the inclusion of the tensor coupling, the effective S-state potential would become attractively singular. We show how including the tensor coupling is essential in order that the wave functions be well-behaved at short distances. For example, the S-state wave function becomes simply proportional to the D-state wave function and dips sharply to zero at the origin, unlike the usual S-state wave functions. Furthermore, this behavior is similar in both QED and QCD, independent of the asymptotic freedom behavior of the assumed QCD vector potential. Light- and heavy-quark meson states can be described well by using a simplified linear-plus-Coulomb-type QCD potential apportioned appropriately between world scalar and vector potentials. We use this potential to exhibit explicitly the origin of the large pi-rho splitting and effective chiral symmetry breaking. The TBDE formalism developed here may be used to study quarkonia in quark-gluon plasma environments.

Crater, H. W. [University of Tennessee Space Institute; Yoon, Jin-Hee [Inha University, Korea; Wong, Cheuk-Yin [ORNL

2009-01-01

86

Spin and pseudospin symmetries in the Dirac equation with central Coulomb potentials  

NASA Astrophysics Data System (ADS)

We analyze in detail the analytical solutions of the Dirac equation with scalar S and vector V Coulomb radial potentials near the limit of spin and pseudospin symmetries (i.e., when those potentials have the same magnitude and either the same sign or opposite signs, respectively). By performing an expansion of the relevant coefficients we also assess the perturbative nature of both symmetries and their relations to the (pseudo)spin-orbit coupling. The former analysis is made for both positive and negative energy solutions and we reproduce the relations between spin and pseudospin symmetries found before for nuclear mean-field potentials. We discuss the node structure of the radial functions and the quantum numbers of the solutions when there is spin or pseudospin symmetry, which we find to be similar to the well-known solutions of hydrogenic atoms.

de Castro, A. S.; Alberto, P.

2012-09-01

87

Coulomb nuclear interference as a tool to investigate the nuclear potential  

SciTech Connect

The sub-barrier excitation function of the octupole vibrational state at 2.615 MeV in {sup 208}Pb is analyzed within the coupled-channels framework. It is shown that the position of the minimum in the excitation function, which is due to the destructive interference of the Coulomb and nuclear scattering amplitudes, is very sensitive to the nuclear potential for both the ground state and the octupole state. A different nuclear potential for the 3{sup -} state may arise from changes in the matter distribution of {sup 208}Pb due to the particle-hole excitations. The present analysis places a strong limit on the 3{sup -} nuclear potential diffuseness, giving a difference of only {Delta}a{sub 0}=0.011+-0.004 fm between the ground state and 3{sup -} state diffuseness.

Evers, M.; Hinde, D. J.; Dasgupta, M.; Luong, D. H.; Rafiei, R.; Rietz, R. du [Department of Nuclear Physics, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia)

2010-01-15

88

Persistent currents in one- and two-dimensional mesoscopic rings: Influence of the Coulomb interaction, impurity scattering, and periodic potential  

NASA Astrophysics Data System (ADS)

We address the discrepancies between measured values of the persistent current in mesoscopic devices in the diffusive regime, and theoretical expectations. We investigate analytically and numerically the influence of the (screened) Coulomb interaction between electrons, of the impurity scattering of electrons, and of the periodic lattice potential acting on each electron, on the persistent current in mesoscopic rings at zero temperature. Our analytical arguments apply to one and two dimensions while the numerical simulation is restricted to one- and two-channel rings. We pay particular attention to the symmetry properties of the many-body wave functions but find that these do not qualitatively influence our results. Without Coulomb interaction, the impurity potential strongly suppresses the current both in the absence and in the presence of a periodic potential. We show that the Coulomb interaction very effectively counteracts the impurity suppression of the persistent current. This is our central result. There is evidence that the Coulomb interaction restores the impurity-suppressed average persistent current to a value close to the one in the absence of impurity scattering. This is a strong effect even for an interaction strength which is quite small compared to realistic estimates of the screened Coulomb interaction. Moreover, we show that in the absence of one-body potentials, the persistent current is exactly [one-dimensional (1D)] or essentially (2D) the same without and with the Coulomb interaction. A periodic potential alone does not affect the persistent current; when combined with the Coulomb interaction, it tends to reduce the current.

Müller-Groeling, Axel; Weidenmüller, Hans A.

1994-02-01

89

Interaction of a model atom exposed to strong laser pulses: Role of the Coulomb potential  

NASA Astrophysics Data System (ADS)

With the help of the solution of the time-dependent Schrödinger equation in momentum space, we study the above-threshold ionization spectrum resulting from the interaction of atomic hydrogen with an infrared and XUV short laser pulses. Our calculations are based on a model where the kernel of the nonlocal Coulomb potential is replaced by a finite sum of N symmetric separable potentials, each of them supporting one bound state of atomic hydrogen. Here, we consider only the case of 1s, 2s, and 2p states. Thus, the theory fully accounting for the important 1s-2p transition, explains the photoelectron spectrum as well as the total ionization probability for the resonant case. We compared the results given by our theory with the numerical solutions of the time-dependent Schrödinger equation.

Tetchou Nganso, Hugues Merlain; Hamido, Aliou; Kwato Njock, Moïse Godfroy; Popov, Yuri Vladimirovich; Piraux, Bernard

2013-01-01

90

Thinking inside the box: Novel linear scaling algorithm for Coulomb potential evaluation  

NASA Astrophysics Data System (ADS)

Beginning with the Poisson equation, and expanding the electronic potential in terms of sine functions, the natural orbitals for describing the particle-in-a-box problem, we find that simple analytic forms can be found for the evaluation of the Coulomb energy for both the interacting and non-interacting system of N-electrons in a box. This method is reminiscent of fast-Fourier transform and scales linearly. To improve the usefulness of this result, we generalize the idea by considering a molecular system, embedded in a box, within which we determine the electrostatic potential, in the same manner as that described for our model systems. Within this general formalism, we consider both periodic and aperiodic recipes with specific application to systems described using Gaussian orbitals; although in principle the method is seen to be completely general.

Thompson, David C.; Ayers, Paul W.

91

Relativistic symmetries with the trigonometric Pöschl—Teller potential plus Coulomb-like tensor interaction  

NASA Astrophysics Data System (ADS)

The Dirac equation is solved to obtain its approximate bound states for a spin-1/2 particle in the presence of trigonometric Pöschl—Teller (tPT) potential including a Coulomb-like tensor interaction with arbitrary spin—orbit quantum number ? using an approximation scheme to substitute the centrifugal terms ?(? ± 1)r-2. In view of spin and pseudo-spin (p-spin) symmetries, the relativistic energy eigenvalues and the corresponding two-component wave functions of a particle moving in the field of attractive and repulsive tPT potentials are obtained using the asymptotic iteration method (AIM). We present numerical results in the absence and presence of tensor coupling A and for various values of spin and p-spin constants and quantum numbers n and ?. The non-relativistic limit is also obtained.

Babatunde, J. Falaye; Sameer, M. Ikhdair

2013-06-01

92

Theory of Excited States of Finite Systems in Coulomb External Potential  

NASA Astrophysics Data System (ADS)

Recently a theory of excited states of Coulomb systems (P. W. Ayers, M. Levy and Á. Nagy, Phys. Rev. A 85, 042518 (2012)) has been been put forward. The talk will present and develop this new theory. It will be shown that the Coulomb density determines the Hamiltonian and the degree of excitation. The definition of a single, universal functional which is enough to describe Coulomb systems is presented. The availability of the theory is discussed.

Nagy, Á.

2013-02-01

93

Analytical potential for the elastic scattering of light halo nuclei below and close to the Coulomb barrier  

SciTech Connect

An analytical expression for the dynamic polarization potential is derived for the elastic scattering of light halo nuclei in the Coulomb field of heavy targets. The derivation is based on the adiabatic motion of the projectile below and close to the Coulomb barrier together with a uniform approximation for the Coulomb functions. Detailed computations have been carried out for the elastic scattering of d+{sup 208}Pb and {sup 6}He+{sup 208}Pb at collision energies of 8 and 17.8 MeV and are compared with measurements as far as available. The obtained expression for the dynamic polarization potential is simple and can be applied for any arbitrary system with a dineutron configuration.

Borowska, L. [Universitaet Bonn, Auf dem Huegel 20, D-53121 Bonn (Germany); Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nauky Prospekt 47, 03680 Kyiv (Ukraine); Terenetsky, K.; Verbitsky, V. [Institute for Nuclear Research, National Academy of Sciences of Ukraine, Nauky Prospekt 47, 03680 Kyiv (Ukraine); Fritzsche, S. [Gesellschaft fuer Schwerionenforschung (GSI), Planckstrasse 1, D-64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies, D-60438 Frankfurt am Main (Germany)

2009-04-15

94

Quantum Field Theory, and Screening the Coulomb Potential by Mobile Deuterons for the Low-Energy Nuclear Reaction  

Microsoft Academic Search

The Coulomb potential is screened by high density mobile deuterons more than the electrons in the PdDx deuteride, and the coherent motion of deuteron might play an important role for analysis of the low-energy nuclear reaction in condensed matter. Together with the group theoretical approach used in nuclear physics, the quantum field theory might provide a sound foundation for analysis

Hiroshi Takahashi

2005-01-01

95

Exact solution of the Landau-Lifshitz equations for a radiating charged particle in the Coulomb potential  

SciTech Connect

We solve exactly the classical non-relativistic Landau-Lifshitz equations of motion for a charged particle moving in a Coulomb potential, including radiation damping. The general solution involves the Painleve transcendent of type II. It confirms our physical intuition that a negatively charged classical particle will spiral into the nucleus, supporting the validity of the Landau-Lifshitz equation.

Rajeev, S.G. [Department of Physics and Astronomy, University of Rochester, Rochester, NY14627 (United States)], E-mail: rajeev@pas.rochester.edu

2008-11-15

96

On the applicability of the exterior complex scaling method for scattering problems including Coulombic potentials  

NASA Astrophysics Data System (ADS)

We study some formal aspects of the exterior complex scaling (ECS) approach when implemented for both short and long-range potentials. In particular, we focus on the inconsistencies related to the requirement of an artificial cut-off of the potential in order to avoid exponential divergencies due to the complex rotation. For the pure two-body Coulomb potential we demonstrate analytically and numerically that the ECS inner solution is indeed the correct one, thus reinforcing the method; the extraction of the transition amplitude, however, remains problematic. We also show that a consistent application of the ECS method requires a distorted wave formulation, and two variants are proposed. Finally, we will propose an approach equivalent to the original ECS but that avoids all formal difficulties. It is based on performing the complex rotation on the basis functions rather than on the driven equation itself, and makes use of Sturmian functions with appropriately chosen outgoing boundary conditions. Our proposal differs from one of the original versions of the ECS method, through the use of physically based basis functions rather than pure numeric ones.

Gasaneo, G.; Ancarani, L. U.; Mitnik, D. M.

2012-04-01

97

Density functional theory for Yukawa fluids.  

PubMed

We develop an approximate field theory for particles interacting with a generalized Yukawa potential. This theory improves and extends a previous splitting field theory, originally developed for counterions around a fixed charge distribution. The resulting theory bridges between the second virial approximation, which is accurate at low particle densities, and the mean-field approximation, accurate at high densities. We apply this theory to charged, screened ions in bulk solution, modeled to interact with a Yukawa potential; the theory is able to accurately reproduce the thermodynamic properties of the system over a broad range of conditions. The theory is also applied to "dressed counterions," interacting with a screened electrostatic potential, contained between charged plates. It is found to work well from the weak coupling to the strong coupling limits. The theory is able to reproduce the counterion profiles and force curves for closed and open systems obtained from Monte Carlo simulations. PMID:22897263

Hatlo, Marius M; Banerjee, Priyanka; Forsman, Jan; Lue, Leo

2012-08-14

98

Sources, potentials and fields in Lorenz and Coulomb gauge: Cancellation of instantaneous interactions for moving point charges  

NASA Astrophysics Data System (ADS)

We investigate the coupling of the electromagnetic sources (charge and current densities) to the scalar and vector potentials in classical electrodynamics, using Green function techniques. As is well known, the scalar potential shows an action-at-a-distance behavior in Coulomb gauge. The conundrum generated by the instantaneous interaction has intrigued physicists for a long time. Starting from the differential equations that couple the sources to the potentials, we here show in a concise derivation, using the retarded Green function, how the instantaneous interaction cancels in the calculation of the electric field. The time derivative of a specific additional term in the vector potential, present only in Coulomb gauge, yields a supplementary contribution to the electric field which cancels the gradient of the instantaneous Coulomb gauge scalar potential, as required by gauge invariance. This completely eliminates the contribution of the instantaneous interaction from the electric field. It turns out that a careful formulation of the retarded Green function, inspired by field theory, is required in order to correctly treat boundary terms in partial integrations. Finally, compact integral representations are derived for the Liénard-Wiechert potentials (scalar and vector) in Coulomb gauge which manifestly contain two compensating action-at-a-distance terms. We investigate action-at-a-distance effects in electrodynamics in detail. We calculate the instantaneous interactions for scalar and vector potentials. The cancellation mechanism involves the retarded Green function. The mechanism is confirmed on the example of moving point charges. The Green function has to be treated with care for nontrivial boundary terms.

Wundt, B. J.; Jentschura, U. D.

2012-04-01

99

Energy eigenvalues of spherical symmetric potentials with relativistic corrections: analytic results  

NASA Astrophysics Data System (ADS)

Based on the investigation of the asymptotic behaviour of the polarization loop function for charged n scalar particles in an external gauge field, we determine the interaction Hamiltonian including the relativistic corrections. The energy eigenvalues of spherical symmetric potentials for two-particle bound state systems with relativistic corrections are analytically derived. The energy spectra of linear and funnel potentials with orbital and radial excitations are determined. The energy spectrum of a superposition of Coulomb and Yukawa potentials is also determined. Our result shows that the energy spectrum with the relativistic corrections for the linear, harmonic oscillator and funnel potentials is smaller than the upper boundaries for the energy spectrum established in the framework of the spinless Salpeter equation for the orbital and radial excited states. The relativistic corrections to the energy spectrum of a superposition of the attractive Coulomb potential and the Yukawa (exponentially screened Coulomb) potentials are very small.

Dineykhan, M.; Zhaugasheva, S. A.; Toinbaeva, N. Sh

2010-01-01

100

Density profile of strongly correlated spherical Yukawa plasmas  

NASA Astrophysics Data System (ADS)

Recently the discovery of 3D-dust crystals [1] excited intensive experimental and theoretical activities [2-4]. Details of the shell structure of these crystals has been very well explained theoretically by a simple model involving an isotropic Yukawa-type pair repulsion and an external harmonic confinement potential [4]. On the other hand, it has remained an open question how the average radial density profile, looks like. We show that screening has a dramatic effect on the density profile, which we derive analytically for the ground state. Interestingly, the result applies not only to a continuous plasma distribution but also to simulation data for the Coulomb crystals exhibiting the above mentioned shell structure. Furthermore, excellent agreement between the continuum model and shell models is found [5]. [1] O. Arp, D. Block, A. Piel, and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005) [3] P. Ludwig, S. Kosse, and M. Bonitz, Phys. Rev. E 71, 046403 (2005) [4] M. Bonitz, D. Block, O. Arp, V. Golubnychiy, H. Baumgartner, P. Ludwig, A. Piel, and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006) [5] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E

Bonitz, M.; Henning, C.; Ludwig, P.; Golubnychiy, V.; Baumgartner, H.; Piel, A.; Block, D.

2006-10-01

101

Lower bound on the coefficient of an exchangelike energy for a single bound electron in a screened Coulomb potential  

SciTech Connect

The spurious self-interaction energy, which is one-half the integrated electrostatic interaction energy of a normalized electronic charge distribution with the potential field generated by itself, is calculated analytically for a 1s-like electron charge distribution governed by an attractive screened Hulthen-type model potential. The exact result obtained is used, via an energetic cancellation constraint and a convenient Hoelder's integral inequality, to deduce an analytical lower bound for the screening-dependent positive coefficient of a negative exchange-like energy term applied routinely in the local-density approximation to density functional theory with Coulomb potentials. The bare Coulomb case is investigated by Sobolev's integral inequality as well.

Nagy, I. [Department of Theoretical Physics, Institute of Physics, Technical University of Budapest, H-1521 Budapest (Hungary); Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, E-20018 San Sebastian (Spain)

2011-04-15

102

Instantaneous interquark potential in generalized Landau gauge in SU(3) lattice QCD: A linkage between the Landau and the Coulomb gauges  

SciTech Connect

We investigate in detail 'instantaneous interquark potentials', interesting gauge-dependent quantities defined from the spatial correlators of the temporal link-variable U{sub 4}, in generalized Landau gauge using SU(3) quenched lattice QCD. The instantaneous QQ potential has no linear part in the Landau gauge, and it is expressed by the Coulomb plus linear potential in the Coulomb gauge, where the slope is 2-3 times larger than the physical string tension. Using the generalized Landau gauge, we find that the instantaneous potential can be continuously described between the Landau and the Coulomb gauges, and its linear part rapidly grows in the neighborhood of the Coulomb gauge. We also investigate the instantaneous 3Q potential in the generalized Landau gauge, and obtain similar results to the QQ case. T-length terminated Polyakov-line correlators and their corresponding ''finite-time potentials'' are also investigated in generalized Landau gauge.

Iritani, Takumi; Suganuma, Hideo [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake, Sakyo, Kyoto 606-8502 (Japan)

2011-03-01

103

Instantaneous interquark potential in generalized Landau gauge in SU(3) lattice QCD: A linkage between the Landau and the Coulomb gauges  

NASA Astrophysics Data System (ADS)

We investigate in detail “instantaneous interquark potentials,” interesting gauge-dependent quantities defined from the spatial correlators of the temporal link-variable U4, in generalized Landau gauge using SU(3) quenched lattice QCD. The instantaneous QQ¯ potential has no linear part in the Landau gauge, and it is expressed by the Coulomb plus linear potential in the Coulomb gauge, where the slope is 2-3 times larger than the physical string tension. Using the generalized Landau gauge, we find that the instantaneous potential can be continuously described between the Landau and the Coulomb gauges, and its linear part rapidly grows in the neighborhood of the Coulomb gauge. We also investigate the instantaneous 3Q potential in the generalized Landau gauge, and obtain similar results to the QQ¯ case. T-length terminated Polyakov-line correlators and their corresponding “finite-time potentials” are also investigated in generalized Landau gauge.

Iritani, Takumi; Suganuma, Hideo

2011-03-01

104

The exact numerical solution of a Schrodinger equation with two-Coulomb centres plus oscillator potential  

Microsoft Academic Search

A numerical technique of solving the Schrodinger equation with two-Coulomb centers plus the oscillator Hamiltonian has been developed. A scheme of evaluating energy levels and wavefunctions of such a Hamiltonian is described in some detail. The proposed algorithm also allows the study of analytical properties of energy levels in a complex plane of the internuclear distance, i.e. to find positions

D. B. Khrebtukov

1992-01-01

105

Increase of the mean inner Coulomb potential in Au clusters induced by surface tension and its implication for electron scattering  

SciTech Connect

Electron holography in a transmission electron microscope was applied to measure the phase shift {delta}{phi} induced by Au clusters as a function of the cluster size. Large {delta}{phi} observed for small Au clusters cannot be described by the well-known equation {delta}{phi}=C{sub E}V{sub 0}t (C{sub E}, interaction constant; V{sub 0}, mean inner Coulomb potential (MIP) of bulk gold; and t, cluster thickness). The rapid increase of the Au MIP with decreasing cluster size derived from {delta}{phi} can be explained by the compressive strain of surface atoms in the cluster.

Popescu, Radian; Mueller, Erich; Wanner, Matthias; Gerthsen, Dagmar; Schowalter, Marco; Rosenauer, Andreas; Boettcher, Artur; Loeffler, Daniel; Weis, Patrick [Laboratorium fuer Elektronenmikroskopie and Center for Functional Nanostructures (CFN), Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Institut fuer Festkoerperphysik, Universitaet Bremen, D-28359 Bremen (Germany); Institut fuer Physikalische Chemie and CFN, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

2007-12-15

106

Yukawa-field approximation of electrostatic free energy and dielectric boundary force  

NASA Astrophysics Data System (ADS)

A Yukawa-field approximation of the electrostatic free energy of a molecular solvation system with an implicit or continuum solvent is constructed. It is argued through the analysis of model molecular systems with spherically symmetric geometries that such an approximation is rational. The construction extends nontrivially that of the Coulomb-field approximation which serves as a basis of the widely used generalized Born model of molecular electrostatics. The electrostatic free energy determines the dielectric boundary force that in turn influences crucially the molecular conformation, stability and dynamics. An explicit formula of such forces with the Yukawa-field approximation is obtained using local coordinates and shape differentiation.

Cheng, Hsiao-Bing; Cheng, Li-Tien; Li, Bo

2011-11-01

107

Unitary pole approximation for the Coulomb-plus-Yamaguchi potential and application to a three-body bound state calculation  

NASA Astrophysics Data System (ADS)

The Unitary Pole Approximation (UPA) is used to construct a separable representation for a potential U which consists of a Coulomb repulsion plus an attractive potential of the Yamaguchi type. The exact bound-state wave function is employed. Um is chosen as the potential which binds the proton in the 1d sub(5/2) single-particle orbit in F-17. Using the separable representation derived for U, and assuming a separable Yamaguchi potential to describe the 1d sub(5/2) neutron in O-17, the energies and wave functions of the ground state, 1(+), and the lowest, o(+), state of F-18 are calculated in the core-plus-nucleons model solving the Faddeev equations.

Ueta, K.; Bund, G. W.

1990-12-01

108

Stimulated two-photon free-free transitions in a Coulomb potential: Formalism  

SciTech Connect

We present a calculation of the cross sections for two-photon free-free transitions of an electron colliding with a Coulomb center of force. The calculation is based on second-order perturbation theory, in the nonrelativistic dipole approximation. The matrix elements for absorption and emission were integrated analytically in momentum space, following a method developed earlier by one of us. This makes use of the Schwinger integral representation for the Coulomb Green's function. The result was expressed in terms of integrals over hypergeometric functions of the Gauss type. Simple limiting forms of these complicated expressions were found in the first Born approximation, and at low and high photon energies. The results derived agree with those obtained by direct calculations done for these limits. Finally, concluding remarks on the analytic part of our work are made. The numerical computation of the two-photon free-free transition cross sections for absorption and emission in various geometries is planned to be presented at a later time.

Gavrila, M. (FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098SJ Amsterdam (The Netherlands)); Maquet, A.; Veniard, V. (Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, F-75231 Paris CEDEX 05 (France))

1990-07-01

109

Longitudinal viscosity of two-dimensional Yukawa liquids.  

PubMed

The longitudinal viscosity ?(l) is obtained for a two-dimensional (2D) liquid using a Green-Kubo method with a molecular dynamics simulation. The interparticle potential used has the Debye-Hückel or Yukawa form, which models a 2D dusty plasma. The longitudinal ?(l) and shear ?(s) viscosities are found to have values that match very closely, with only negligible differences for the entire range of temperatures that is considered. For a 2D Yukawa liquid, the bulk viscosity ?(b) is determined to be either negligibly small or not a meaningful transport coefficient. PMID:23410445

Feng, Yan; Goree, J; Liu, Bin

2013-01-22

110

Exact solutions of the pseudo-Coulomb potential plus ring-shaped potential in the D-dimensional Schrodinger equation by the Nikiforov-Uvarov method  

Microsoft Academic Search

We present analytically the exact energy bound-states solutions of the Schrodinger equation in D-dimensions for an alternative (often used) pseudo-Coulomb potential-plus- ring-shaped potential of the form $V(r)=-% \\\\frac{a}{r}+\\\\frac{b}{r^{2}}+\\\\frac{\\\\beta \\\\cos ^{2}\\\\theta}{r^{2}\\\\sin ^{2}\\\\theta }+c$ by means of the conventional Nikiforov-Uvarov method. We give a clear recipe of how to obtain an explicit solution to the radial and angular parts of the wave

Sameer M. Ikhdair; Ramazan Sever

2007-01-01

111

Phonon spectrum measured in a 1D Yukawa chain  

Microsoft Academic Search

An experiment is reported for a 1D chain of charged microspheres with a Yukawa pair potential. This work is motivated by chains of colloids confined in laser beams and Xe atoms confined in carbon nanotubes. Polymer microspheres are dispersed in a weakly- ionized rarefied gas. The resulting suspension, termed a dusty plasma, is a colloidal crystal. Depending on the confinement

J. Goree

2005-01-01

112

Adventures in Coulomb Gauge  

SciTech Connect

We study the phase structure of SU(2) gauge theories at zero and high temperature, with and without scalar matter fields, in terms of the symmetric/broken realization of the remnant gauge symmetry which exists after fixing to Coulomb gauge. The symmetric realization is associated with a linearly rising color Coulomb potential (which we compute numerically), and is a necessary but not sufficient condition for confinement.

Greensite, J.; Olejnik, S.

2003-09-26

113

Studies of charge neutral FCC Lattice Gas with Yukawa Interaction and Accelerated Cartesian Expansion method  

NASA Astrophysics Data System (ADS)

In this thesis, I present the results of studies of the structural properties and phase transition of a charge neutral FCC Lattice Gas with Yukawa Interaction and discuss a novel fast calculation algorithm---Accelerated Cartesian Expansion (ACE) method. In the first part of my thesis, I discuss the results of Monte Carlo simulations carried out to understand the finite temperature (phase transition) properties and the ground state structure of a Yukawa Lattice Gas (YLG) model. In this model the ions interact via the potential q iqjexp(-kappar> ij)/rij where qi,j are the charges of the ions located at the lattice sites i and j with position vectors R i and Rj; rij = Ri-Rj, kappa is a measure of the range of the interaction and is called the screening parameter. This model approximates an interesting quaternary system of great current thermoelectric interest called LAST-m, AgSbPbmTem+2. I have also developed rapid calculation methods for the potential energy calculation in a lattice gas system with periodic boundary condition bases on the Ewald summation method and coded the algorithm to compute the energies in MC simulation. Some of the interesting results of the MC simulations are: (i) how the nature and strength of the phase transition depend on the range of interaction (Yukawa screening parameter kappa) (ii) what is the degeneracy of the ground state for different values of the concentration of charges, and (iii) what is the nature of two-stage disordering transition seen for certain values of x. In addition, based on the analysis of the surface energy of different nano-clusters formed near the transition temperature, the solidification process and the rate of production of these nano-clusters have been studied. In the second part of my thesis, we have developed two methods for rapidly computing potentials of the form R-nu. Both these methods are founded on addition theorems based on Taylor expansions. Taylor's series has a couple of inherent advantages: (i) it forms a natural framework for developing addition theorem based computational schemes for a range of potentials; (ii) only Cartesian tensors (or products of Cartesian quantities) are used as opposed to special functions. This makes creating a fast scheme possible for potential of the form R-nu . Indeed, it is also possible to generalize the proposed methods to several potentials that are important in mathematical physics. An interesting consequence of the approach has been the demonstration of the equivalence of FMMs that are based on traceless Cartesian tensors to those based on spherical expansions for nu = 1. Two methods are introduced; the first relies on exact translation of the origin of the multipole whereas the second relies on cascaded Taylor's approximations. Finally, we have shown the application of this methodology to computing Coulombic, Lennard-Jones, Yukawa potentials and etc. We have also demonstrated the efficacy of this scheme for other (non-integer) potential functions.

Huang, He

114

On the Supersymmetry of the Dirac-Kepler Problem Plus a Coulomb-Type Scalar Potential in (D+1) Dimensions and the Generalized Lippmann-Johnson Operator  

NASA Astrophysics Data System (ADS)

We will study the Dirac-Kepler problem plus a Coulomb-type scalar potential by generalizing the Lippmann-Johnson operator to D spatial dimensions. From this operator, we construct the supersymmetric generators to obtain the energy spectrum for discrete excited eigenstates and the radial spinor for the SUSY ground state.

Martínez, D.; Salazar-Ramírez, M.; Mota, R. D.; Granados, V. D.

2013-04-01

115

Improved Shell models for screened Coulomb balls  

NASA Astrophysics Data System (ADS)

Spherical Coulomb crystals in dusty plasmas [1] are well described by an isotropic Yukawa-type pair interaction and an external parabolic confinement as was shown by extensive molecular dynamics simulations [2]. A much simpler description is possible with analytical shell models which have been derived for Yukawas plasmas in [3,4]. Here we analyze improved Yukawa shell models which include correlations along the lines proposed for Coulomb crystals in [5]. The shell configurations are efficiently evaluated using a Monte Carlo procedure. [1] O. Arp, A. Piel and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golunychiy, H. Baumgartner, P. Ludwig, A. Piel and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] H. Totsuji, C. Totsuji, T. Ogawa, and K. Tsuruta, Phys. Rev. E 71, 045401 (2005). [4] C. Henning, M. Bonitz, A. Piel, P. Ludwig, H. Baumgartner, V. Golubnichiy, and D. Block, submitted to Phys. Rev. E [5] W.D. Kraeft and M. Bonitz, J. Phys. Conf. Ser. 35, 94 (2006).

Bonitz, M.; Kaehlert, H.; Henning, C.; Baumgartner, H.; Filinov, A.

2006-10-01

116

Mixing parameters of neutral beauty mesons from the Coulomb plus power potential (CPP?)  

NASA Astrophysics Data System (ADS)

The investigation of mixing parameters in neutral B meson systems provides an important testing ground for standard model flavour dynamics. The spectroscopic parameters deduced from the potential model are used to calculate the pseudoscalar decay constant and mixing parameters of the B and Bs mesons.

Patel, Bhavin; Vinodkumar, P. C.

2009-11-01

117

Power law behavior of the zigzag transition in Yukawa clusters  

SciTech Connect

We provide direct experimental evidence that the width of a Yukawa cluster exhibits power law behavior during the one-dimensional (1D) to two-dimensional (2D) zigzag transition. Configurations of small dusty (complex) plasma clusters confined in a biharmonic potential well are characterized as the well anisotropy is varied. When the anisotropy is large the particles are in a 1D straight-line configuration. As the anisotropy is decreased the cluster undergoes a zigzag transition to a 2D configuration. The measured dependence of cluster width on anisotropy follows a power law. A second transition from the zigzag to an elliptical configuration is also observed. The results are in very good agreement with a model of identical particles interacting through a Yukawa potential.

Sheridan, T. E.; Magyar, Andrew L. [Department of Physics and Astronomy, Ohio Northern University, Ada, Ohio 45810 (United States)

2010-11-15

118

Direct demonstration of the completeness of the eigenstates of the Schroedinger equation with local and nonlocal potentials bearing a Coulomb tail  

SciTech Connect

Demonstrating the completeness of wave function solutions of the radial Schroedinger equation is a very difficult task. Existing proofs, relying on operator theory, are often very abstract and far from intuitive comprehension. However, it is possible to obtain rigorous proofs amenable to physical insight, if one restricts the considered class of Schroedinger potentials. One can mention, in particular, unbounded potentials yielding a purely discrete spectrum and short-range potentials. However, those possessing a Coulomb tail, very important for physical applications, have remained problematic due to their long-range character. The method proposed in this paper allows to treat them correctly, provided that the non-Coulomb part of potentials vanishes after a finite radius. Nonlocality of potentials can also be handled. The main idea in the proposed demonstration is that regular solutions behave like sine/cosine functions for large momenta, so that their expansions verify Fourier transform properties. The highly singular point at k=0 of long-range potentials is dealt with properly using analytical properties of Coulomb wave functions. Lebesgue measure theory is avoided, rendering the demonstration clear from a physical point of view.

Michel, N. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa, Kyoto, 606-8502 (Japan)

2008-02-15

119

Yukawa couplings in SO(10) heterotic M-theory vacua  

Microsoft Academic Search

We demonstrate the existence of a class of N=1 supersymmetric nonperturbative vacua of Ho?ava–Witten M-theory compactified on a torus fibered Calabi–Yau 3-fold Z with first homotopy group ?1(Z)=Z2, having the following properties: (1) SO(10) grand unification group, (2) net number of three generations of chiral fermions in the observable sector, and (3) potentially viable matter Yukawa couplings. These vacua correspond

Alon E. Faraggi; Richard S. Garavuso

2003-01-01

120

Yukawa couplings in \\/SO(10) heterotic M-theory vacua  

Microsoft Academic Search

We demonstrate the existence of a class of \\/N=1 supersymmetric nonperturbative vacua of Horava-Witten M-theory compactified on a torus fibered Calabi-Yau 3-fold \\/Z with first homotopy group pi1(Z)=Z2, having the following properties: (1) \\/SO(10) grand unification group, (2) net number of three generations of chiral fermions in the observable sector, and (3) potentially viable matter Yukawa couplings. These vacua correspond

Alon E. Faraggi; Richard S. Garavuso

2003-01-01

121

Coulomb Damping  

ERIC Educational Resources Information Center

|Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

Fay, Temple H.

2012-01-01

122

Coulomb Damping  

ERIC Educational Resources Information Center

Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

Fay, Temple H.

2012-01-01

123

Coulomb Plot  

NSDL National Science Digital Library

This Flash simulation allows you to observe the force on a charge due to an identical charge. The a graph of Coulomb force experienced by one of the charges due to the other charge is shown. The user can move both charges.

Selen, Mats

2010-03-11

124

Coulomb breakup problem.  

PubMed

We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the three-body wave functions. This formulation is valid for both short-range and Coulombic potentials. The post and prior forms of the breakup amplitude are derived without any reference to renormalization procedures. PMID:19113531

Kadyrov, A S; Bray, I; Mukhamedzhanov, A M; Stelbovics, A T

2008-12-05

125

The Coulomb Barrier Transmission Coefficient in Nuclear Reactions  

Microsoft Academic Search

This thesis mainly deals with the Coulomb wavefunctions and their applications in a nuclear fusion theory. When two charged particles come close they interact through a Coulomb potential. As solutions of a Schrodinger equation with the Coulomb potential, we construct the regular and irregular Coulomb wavefunctions. These are used to construct the exterior wavefunctions outside a nucleus that satisfy the

Jin-Hee Yoon

1994-01-01

126

T-branes and Yukawa couplings  

NASA Astrophysics Data System (ADS)

We consider various configurations of T-branes which are non-abelian bound states of branes and were recently introduced by Cecotti, Cordova, Heckman and Vafa. They are a refinement of the concept of monodromic branes featured in phenomenological F-theory models. We are particularly interested in the T-branes corresponding to Z 3 and Z 4 monodromies, which are used to break E 7 or E 8 gauge groups to SU(5) GUT . Our results imply that the up-type and down-type Yukawa couplings for the breaking of E 7 are zero, whereas up-type and down-type Yukawa couplings, together with right handed neutrino Yukawas are non-zero for the case of the breaking of E 8. The dimension four proton decay mediating term is avoided in models with either E 7 or E 8 breaking.

Chiou, Chan-Chi; Faraggi, Alon E.; Tatar, Radu; Walters, William

2011-05-01

127

Yukawa terms in noncommutative SO(10) and E6 GUTs  

NASA Astrophysics Data System (ADS)

We propose a method for constructing Yukawa terms for noncommutative SO(10) and E6 GUTs when these GUTs are formulated within the enveloping-algebra formalism. The most general noncommutative Yukawa term that we propose contains, at first order in ???, the most general Becchi-Rouet-Stora invariant Yukawa contribution whose only dimensionful parameter is the noncommutativity parameter. This noncommutative Yukawa interaction is thus renormalizable at first order in ???.

Martín, C. P.

2010-10-01

128

Coulomb Sink: A Novel Coulomb Effect on Coarsening of Metal Nanoclusters on Semiconductor Surfaces  

Microsoft Academic Search

We propose the concept of a ``Coulomb sink'' to elucidate the effect of Coulomb charging on coarsening of metal mesas grown on semiconductor surfaces. We show that a charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neutral mesas. The theory explains qualitatively the most salient features of coarsening

Y. Han; J. Y. Zhu; Feng Liu; Shao-Chun Li; Jin-Feng Jia; Yan-Feng Zhang; Qi-Kun Xue

2004-01-01

129

Statistical Mechanics of a Coulomb Gas With Finite Size Particles: A Lattice Field Theory Approach.  

National Technical Information Service (NTIS)

A recently proposed lattice field theory approach to the statistical mechanics of a classical Coulomb gas is generalized to treat gas particles of finite size. To do this, a repulsive Yukawa interaction between all pairs of gas particles is added to the u...

R. D. Coalson A. M. Walsh A. Duncan N. Ben-Tal

1995-01-01

130

Test of gauge-Yukawa unification  

NASA Astrophysics Data System (ADS)

Recently it has been proposed that, in the framework of quantum field theory, both the Standard Model gauge and Yukawa interactions arise from a single gauge interaction in higher dimensions with supersymmetry. This leads to the unification of the Standard Model gauge couplings and the third family Yukawa couplings at the GUT scale. In this Letter, we make a detailed study of this unification using the current experimental data, and find a good agreement in a significant region of the parameter space. Similar relations, required in finite grand unification models, are also studied.

Gogoladze, Ilia; Mimura, Yukihiro; Nandi, S.; Tobe, Kazuhiro

2003-11-01

131

Pauli potential in terms of kinetic energy density and electron density in the leading Coulombic term of the nonrelativistic 1/Z expansion of spherical atomic ions  

SciTech Connect

The Pauli potential V{sub P} in density functional theory is known to be the difference between the functional derivative of the single-particle kinetic energy T{sub s}[n] with respect to the electron density n and its von Weizsaecker counterpart. For the leading Coulombic term in the 1/Z expansion for spherical atomic ions, V{sub P}[n] is written in terms of the kinetic energy density plus n(r) and its low-order derivatives. For comparison, the example of an arbitrary number of closed shells with purely harmonic confinement is also treated.

March, N. H. [Department of Physics, University of Antwerp, Antwerp (Belgium); Oxford University, Oxford (United Kingdom); Nagy, A. [Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen (Hungary)

2010-01-15

132

Longitudinal and transverse waves in Yukawa crystals.  

PubMed

A unified theoretical treatment is given of longitudinal (or compressional) and transverse modes in Yukawa crystals, including the effects of damping. Dispersion relations are obtained for hexagonal lattices in two dimensions and bcc and fcc lattices in three dimensions. Theoretical predictions are compared with two recent experiments. PMID:11289982

Wang, X; Bhattacharjee, A; Hu, S

2001-03-19

133

Superstring threshold corrections to Yukawa couplings.  

National Technical Information Service (NTIS)

A general method of computing string corrections to the Kaehler metric and Yukawa couplings is developed at the one-loop level for a general compactification of the heterotic superstring theory. It also provides a direct determination of the so-called Gre...

I. Antoniadis E. Gava K. S. Narain T. R. Taylor

1992-01-01

134

Approximate Bound States Solution of the Hellmann Potential  

NASA Astrophysics Data System (ADS)

The Hellmann potential, which is a superposition of an attractive Coulomb potential ?a/r and a Yukawa potential b e??r/r, is often used to compute bound-state normalizations and energy levels of neutral atoms. By using the generalized parametric Nikiforov—Uvarov (NU) method, we have obtained the approximate analytical solutions of the radial Schrödinger equation (SE) for the Hellmann potential. The energy eigenvalues and corresponding eigenfunctions are calculated in closed forms. Some numerical results are presented, which show good agreement with a numerical amplitude phase method and also those previously obtained by other methods. As a particular case, we find the energy levels of the pure Coulomb potential.

Hamzavi, M.; K. E., Thylwe; A. A., Rajabi

2013-07-01

135

Charge Neutral Yukawa Lattice Gas on a FCC Lattice  

NASA Astrophysics Data System (ADS)

Structural phase transitions associated with the ordering of Ag and Sb ions in the quaternary systems, (AgSbTe2) x(PbTe)2(1 - x) (of current thermoelectric interest) has been investigated using an anti-ferromagnetic 3-state Ising model on a FCC lattice with screened Coulomb interaction (Yukawa lattice gas (YLG) model). We have carried out Monte Carlo simulations (MCs) to study phase transitions (PT) in YLG. The nature and the strength of PT depend on the screening parameter ?. The transition is 1^st order and the transition temperature Tc is a weak function of the concentration x (excepting when x˜0 or 1), in agreement with earlier work for ?=0. We find Tc(x, ?)=f(x)g (?), where g(?)->const when ?->0 and g (?)->0 when ?->?. For x=0.5, there are two special structures, layered and tubular which have the same ground state energy, independent of ?. This is understood by looking at the connectivity and ordering of ions. Above but near Tc, the generation rates of different micro structures have been analyzed using a simple surface energy density picture. MCs results agree with this analysis and show that the energy barriers decide the generation rates of different micro structures.

Huang, He; Mahanti, S. D.

2011-03-01

136

ATOMIC AND MOLECULAR PHYSICS: Generalized Pseudospectral Method for Solving the Time-Dependent Schrödinger Equation Involving the Coulomb Potential  

NASA Astrophysics Data System (ADS)

We present an accurate and efficient generalized pseudospectral method for solving the time-dependent Schrödinger equation for atomic systems interacting with intense laser fields. In this method, the time propagation of the wave function is calculated using the well-known second-order split-operator method implemented by the numerically exact, fast transform between the grid and spectral representations. In the grid representation, the radial coordinate is discretized using the Coulomb wave discrete variable representation (CWDVR), and the angular dependence of the wave function is expanded in the Gauss-Legendre-Fourier grid. In the spectral representation, the wave function is expanded in terms of the eigenfunctions of the field-free zero-order Hamiltonian. Calculations on the high order harmonic generation and ionization dynamics of hydrogen atom in strong laser pulses are presented to demonstrate the accuracy and efficiency of the present method. This new algorithm will be found more computationally attractive than the close-coupled wave packet method using CWDVR and/or methods based on evenly spaced grids.

Zeng, Si-Liang; Zou, Shi-Yang; Yan, Jun

2009-05-01

137

Yukawa textures from heterotic stability walls  

NASA Astrophysics Data System (ADS)

A holomorphic vector bundle on a Calabi-Yau threefold, X, with h 1,1( X) ? 2 can have regions of its Kähler cone where it is slope-stable, that is, where the four-dimensional theory is mathcal{N} = 1 supersymmetric, bounded by “walls of stability”. On these walls the bundle becomes poly-stable, decomposing into a direct sum, and the low energy gauge group is enhanced by at least one anomalous U(1) gauge factor. In this paper, we show that these additional symmetries can strongly constrain the superpotential in the stable region, leading to non-trivial textures of Yukawa interactions and restrictions on allowed masses for vector-like pairs of matter multiplets. The Yukawa textures exhibit a hierarchy; large couplings arise on the stability wall and some suppressed interactions “grow back” off the wall, where the extended U(1) symmetries are spontaneously broken. A number of explicit examples are presented involving both one and two stability walls, with different decompositions of the bundle structure group. A three family standard-like model with no vector-like pairs is given as an example of a class of SU(4) bundles that has a naturally heavy third quark/lepton family. Finally, we present the complete set of Yukawa textures that can arise for any holomorphic bundle with one stability wall where the structure group breaks into two factors.

Anderson, Lara B.; Gray, James; Ovrut, Burt

2010-05-01

138

Analytical Asymptotic Structure of the Pauli, Coulomb, and Correlation-Kinetic Components of the Kohn- Sham Exchange - Correlation Potential in Atoms  

NASA Astrophysics Data System (ADS)

We derive the analytical asymptotic structure in atoms of the Kohn-Sham (KS) exchange-correlation potential via its quantum-mechanical interpretation (V. Sahni, Phys. Rev. A55, 1846 (1997)). In this manner, the components of this structure due to the separate correlations arising from the Pauli exclusion principle, Coulomb repulsion, and correlation-kinetic effects are explicitly determined. The calculations are performed in terms of quasi-particle amplitudes (C.-O. Almbladh and U. von Barth, Phys. Rev. B31, 3231 (1985)), which are the interacting system counterparts of the KS orbitals. The results derived are for the case in which the N-electron system may be orbitally degenerate but where the (N-1)-electron ion is spherically symmetric.

Sahni, V.; Qian, Z.

1998-03-01

139

Ionic Coulomb Blockade in Nanopores  

NASA Astrophysics Data System (ADS)

Understanding the dynamics of ions in nanopores is essential for potential applications in molecule detection, DNA sequencing, and other technologies [1]. We show both analytically and by means of molecular dynamics simulations that ion-ion interactions in nanopores leads to the phenomenon of ionic Coulomb blockade, namely the build-up of ions inside a nanopore with specific capacitance impeding the flow of additional ions due to Coulomb repulsion. This is the classical counterpart of electronic Coulomb blockade in mesoscopic systems. We discuss the analogies and differences with the electronic case as well as experimental situations in which this phenomenon could be detected. [4pt] [1] M. Zwolak, M. Di Ventra, Physical Approaches to DNA sequencing and Detection, Rev. Mod. Phys. 80, 141 (2008).

Krems, Matt; di Ventra, Massimiliano

2011-03-01

140

?13, ?? Symmetry Breaking and Neutrino Yukawa Textures  

NASA Astrophysics Data System (ADS)

Within the type-I seesaw and in the basis where charged lepton and heavy neutrino mass matrices are real and diagonal, ?? symmetric four and three zero neutrino Yukawa textures are perturbed by lowest order ?? symmetry breaking terms. These perturbations are taken to be the most general ones for those textures. For quite small values of those symmetry breaking parameters, permitting a lowest order analysis, current best-fit ranges of neutrino mass squared differences and mixing angles are shown to be accommodable, including a value of ?13 in the observed range, provided all the light neutrinos have an inverted mass ordering.

Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir

2013-09-01

141

Multiple series of shape resonances and near-zero-energy cross section enhancements in photoionization of hydrogen-like ions with screened coulomb interaction  

NASA Astrophysics Data System (ADS)

The recently discovered multiple series of shape resonances and near-zero-energy enhancements in photoionization cross section of hydrogen-like atomic systems with screened Coulomb (Yukawa type) interaction [Phys. Rev. A 80, 063404 (2009)] are studied in detail, in particular their evolution with the variation of the screening strength of the potential. The conditions for appearance of these multiple series of cross section features are identified and related to certain critical screening strengths of the potential. A relation between the appearance of Cooper minima and shape resonaces in the photoionizations cross section has been established. It is also shown that the s-channel of np photoionization for a fixed photoelectron energy exhibits Ramsauer-Townsend minima in the screening length variable.

Qi, Y. Y.; Wang, J. G.; Janev, R. K.

2011-08-01

142

Nonlinear compressional waves in a two-dimensional Yukawa lattice.  

PubMed

A modified Korteweg-de Vries (KdV) equation is obtained for studying the propagation of nonlinear compressional waves and pulses in a chain of particles including the effect of damping. Suitably altering the linear phase velocity makes this equation useful also for the problem of phonon propagation in a two-dimensional (2D) lattice. Assuming a Yukawa potential, we use this method to model compressional wave propagation in a 2D plasma crystal, as in a recent experiment. By integrating the modified KdV equation the pulse is allowed to evolve, and good agreement with the experiment is found. It is shown that the speed of a compressional pulse increases with its amplitude, while the speed of a rarefactive pulse decreases. It is further discussed how the drag due to the background gas has a crucial role in weakening nonlinear effects and preventing the emergence of a soliton. PMID:14683049

Avinash, K; Zhu, P; Nosenko, V; Goree, J

2003-10-08

143

Statics and dynamics of Yukawa cluster crystals on ordered substrates.  

PubMed

We examine the statics and dynamics of particles with repulsive Yukawa interactions in the presence of a two-dimensional triangular substrate for fillings of up to 12 particles per potential minimum. We term the ordered states Yukawa cluster crystals and show that they are distinct from the colloidal molecular crystal states found at low fillings. As a function of substrate and interaction strength at fixed particle density we find a series of novel crystalline states that we characterize using the structure factor. For fillings greater than four, shell and ring structures form at each potential minimum and can exhibit sample-wide orientational order. A disordered state can appear between ordered states as the substrate strength varies. Under an external drive, the onsets of different orderings produce clear changes in the critical depinning force, including a peak effect phenomenon that has generally only previously been observed in systems with random substrates. We also find a rich variety of dynamic ordering transitions that can be observed via changes in the structure factor and features in the velocity-force curves. The dynamical states encompass a variety of moving structures including one-dimensional stripes, smectic ordering, polycrystalline states, triangular lattices, and symmetry locking states. Despite the complexity of the system, we identify several generic features of the dynamical phase transitions which we map out in a series of phase diagrams. Our results have implications for the structure and depinning of colloids on periodic substrates, vortices in superconductors and Bose-Einstein condensates, Wigner crystals, and dusty plasmas. PMID:23004755

Reichhardt, C; Olson Reichhardt, C J

2012-05-02

144

pd Scattering Using a Rigorous Coulomb Treatment  

Microsoft Academic Search

Reliability of the screened Coulomb renormalization method, which was proposed in an elegant way by Alt–Sandhas–Zankel–Ziegelmann\\u000a (ASZZ), is discussed on the basis of “two-potential theory” for the three-body AGS equations with the Coulomb potential. In\\u000a order to obtain ASZZ’s formula, we define the on-shell Møller function, and calculate it by using the Haeringen criterion,\\u000a i.e. “the half-shell Coulomb amplitude is

Y. Hiratsuka; S. Oryu; S. Gojuki

2011-01-01

145

Melting of a repulsive screened Coulomb system in two dimensions: Effect of corrugation  

NASA Astrophysics Data System (ADS)

By use of constant energy molecular dynamics simulations, we have investigated the melting and freezing transitions in a two-dimensional system consisting of a constant density of classical particles interacting with a repulsive screened Coulomb (Yukawa) potential. In particular, we have investigated the role of an incommensurate substrate corrugation potential of sixfold symmetry on these transitions by probing the temperature dependence of the bond orientational order parameter (?6) and the corresponding susceptibility (?6). Other physical quantities such as energy, diffusion constant, and the density of local topological defects have been monitored through the transition region. In the absence of a corrugation potential the system shows a sharp melting transition. In the presence of a corrugation potential the transition temperature increases and the transition becomes smoother. In contrast to the corrugation-free case we find a broad peak in ?6 above the transition temperature. We interpret this behavior in terms of the melting of a domain-wall solid. The detailed nature of this smooth transition depends on the degree of incommensurability. Relevance of these results to stage-2 graphite intercalation compounds is discussed.

Seong, Hyangsuk; Mahanti, S. D.; Sen, Surajit; Ça?in, Tahir

1992-10-01

146

Ground-state stability and criticality of two-electron atoms with screened Coulomb potentials using the B-splines basis set  

NASA Astrophysics Data System (ADS)

We applied the finite-size scaling method using the B-splines basis set to construct the stability diagram for two-electron atoms with a screened Coulomb potential. The results of this method for two-electron atoms are very accurate in comparison with previous calculations based on Gaussian, Hylleraas and finite-element basis sets. The stability diagram for the screened two-electron atoms shows three distinct regions, i.e. a two-electron region, a one-electron region and a zero-electron region, which correspond to stable, ionized and double ionized atoms, respectively. In previous studies, it was difficult to extend the finite-size scaling calculations to large molecules and extended systems because of the computational cost and the lack of a simple way to increase the number of Gaussian basis elements in a systematic way. Motivated by recent studies showing how one can use B-splines to solve Hartree-Fock and Kohn-Sham equations, this combined finite-size scaling using the B-splines basis set might provide an effective systematic way to treat criticality of large molecules and extended systems. As benchmark calculations, the two-electron systems show the feasibility of this combined approach and provide an accurate reference for comparison.

Serra, Pablo; Kais, Sabre

2012-12-01

147

Completeness of the Coulomb scattering wave functions  

NASA Astrophysics Data System (ADS)

The completeness of the eigenfunctions of a self-adjoint Hamiltonian, which is the basic ingredient of quantum mechanics, plays an important role in nuclear reaction and nuclear-structure theory. Here we present the first formal proof of the completeness of the two-body Coulomb scattering wave functions for a repulsive unscreened Coulomb potential using Newton’s method (R. Newton, J. Math. Phys. 1, 319 (1960)). The proof allows us to claim that the eigenfunctions of the two-body Hamiltonian, with the potential given by the sum of the repulsive Coulomb plus short-range (nuclear) potentials, form a complete set. It also allows one to extend Berggren’s approach for the modification of the complete set of eigenfunctions by including the resonances for charged particles. We also demonstrate that the resonant Gamow functions with Coulomb tail can be regularized using Zel’dovich’s regularization method.

Mukhamedzhanov, A. M.; Akin, M.

2008-07-01

148

Temperature dependence of nucleation in Yukawa fluids  

NASA Astrophysics Data System (ADS)

We have studied the temperature dependence of gas-liquid nucleation in Yukawa fluids with gradient theory (GT) and density functional theory (DFT). Each of these nonclassical theories exhibits a weaker (i.e. better) temperature dependence than classical nucleation theory. At a given temperature, the difference between GT and DFT for the reversible work to form a critical nucleus gets smaller with increasing superaturation. For the temperature dependence, the reversible work for GT is very close to that for DFT at high temperatures. The difference between the two theories increases with decreasing temperature and supersaturation. Thus, in contrast to the behavior of a Peng-Robinson fluid, we find that GT can improve the temperature dependence over that of classical nucleation theory, although not always to the same degree as DFT.

Li, J.-S.; Wilemski, G.

2002-03-01

149

Towards a precise measurement of the top quark Yukawa coupling at the ILC  

SciTech Connect

A precise measurement of the top quark Yukawa coupling is of great importance, since it may shed light on the mechanism of EWSB. We study the prospects of such measurement during the first phase of the ILC at {radical}s = 500 GeV, focusing in particular on recent theoretical developments as well as the potential benefits of beam polarization. It is shown that both yield improvements that could possibly lead to a measurement competitive with the LHC.

Juste, A.; /Fermilab

2005-12-01

150

Three Different Approaches to the Same Interaction: The Yukawa Model in Nuclear Physics  

NASA Astrophysics Data System (ADS)

After a brief discussion of the meaning of the potential in quantum mechanics, we shall examine the results of the Yukawa model (scalar meson exchange) for the nucleon-nucleon interaction in three different dynamical frameworks: the non-relativistic dynamics of the Schrodinger equation, the relativistic quantum mechanics of the Bethe-Salpeter and Light-Front equations and the lattice solution of the Quantum Field Theory, obtained in the quenched approximation.

Carbonell, J.; de Soto, F.; Karmanov, V. A.

2012-11-01

151

Testing the relevance of effective interaction potentials between highly-charged colloids in suspension  

NASA Astrophysics Data System (ADS)

Combining cell and Jellium model mean-field approaches, Monte Carlo together with integral equation techniques, and finally more demanding many-colloid mean-field computations, we investigate the thermodynamic behaviour, pressure and compressibility of highly-charged colloidal dispersions, and at a more microscopic level, the force distribution acting on the colloids. The Kirkwood Buff identity provides a useful probe to challenge the self-consistency of an approximate effective screened Coulomb (Yukawa) potential between colloids. Two effective parameter models are put to the test: cell against renormalized Jellium models.

Dobnikar, J.; Castañeda-Priego, R.; von Grünberg, H. H.; Trizac, E.

2006-11-01

152

Application of the optimized Baxter model to the hard-core attractive Yukawa system  

NASA Astrophysics Data System (ADS)

We perform Monte Carlo simulations on the hard-core attractive Yukawa system to test the optimized Baxter model that was introduced by Prinsen and Odijk [J. Chem. Phys. 121, 6525 (2004)] to study a fluid phase of spherical particles interacting through a short-range pair potential. We compare the chemical potentials and pressures from the simulations with analytical predictions from the optimized Baxter model. We show that the model is accurate to within 10% over a range of volume fractions from 0.1 to 0.4, interaction strengths up to three times the thermal energy, and interaction ranges from 6% to 20% of the particle diameter, and performs even better in most cases. We furthermore establish the consistency of the model by showing that the thermodynamic properties of the Yukawa fluid computed via simulations may be understood on the basis of one similarity variable, the stickiness parameter defined within the optimized Baxter model. Finally, we show that the optimized Baxter model works significantly better than an often used, naive method determining the stickiness parameter by equating the respective second virial coefficients based on the attractive Yukawa and Baxter potentials.

Prinsen, Peter; Pàmies, Josep C.; Odijk, Theo; Frenkel, Daan

2006-11-01

153

Application of the optimized Baxter model to the hard-core attractive Yukawa system.  

PubMed

We perform Monte Carlo simulations on the hard-core attractive Yukawa system to test the optimized Baxter model that was introduced by Prinsen and Odijk [J. Chem. Phys. 121, 6525 (2004)] to study a fluid phase of spherical particles interacting through a short-range pair potential. We compare the chemical potentials and pressures from the simulations with analytical predictions from the optimized Baxter model. We show that the model is accurate to within 10% over a range of volume fractions from 0.1 to 0.4, interaction strengths up to three times the thermal energy, and interaction ranges from 6% to 20% of the particle diameter, and performs even better in most cases. We furthermore establish the consistency of the model by showing that the thermodynamic properties of the Yukawa fluid computed via simulations may be understood on the basis of one similarity variable, the stickiness parameter defined within the optimized Baxter model. Finally, we show that the optimized Baxter model works significantly better than an often used, naive method determining the stickiness parameter by equating the respective second virial coefficients based on the attractive Yukawa and Baxter potentials. PMID:17129122

Prinsen, Peter; Pàmies, Josep C; Odijk, Theo; Frenkel, Daan

2006-11-21

154

Comment on ``Exact three-dimensional wave function and the on-shell t matrix for the sharply cut-off Coulomb potential: Failure of the standard renormalization factor''  

NASA Astrophysics Data System (ADS)

The solutions analytically derived by W. Glöckle, J. Golak, R. Skibi?ski, and H. Witala [Phys. Rev. C 79, 044003 (2009)] for the three-dimensional wave function and on-shell t matrix in the case of scattering on a sharply cut-off Coulomb potential appear to be fallacious if finite values of a cut-off radius are concerned. And the analysis carried out for an infinite cut-off radius limit is incomplete.

Kouzakov, Konstantin A.; Popov, Yuri V.; Shablov, Vladimir L.

2010-01-01

155

Coulomb Distortion in the Inelastic Regime  

SciTech Connect

The Coulomb distortion effects have been for a long time neglected in deep inelastic scattering for the good reason that the incident energies were very high. But for energies in the range of earlier data from SLAC or at JLab, the Coulomb distortion could have the potential consequence of affecting the A-dependence of the EMC effect and of the longitudinal to transverse virtual photon absorption cross section ratio $R(x,Q^2)$.

Patricia Solvignon, Dave Gaskell, John Arrington

2009-09-01

156

Kelvin Helmholtz Instability in Strongly Coupled Yukawa Liquids  

SciTech Connect

Using 'first principles' molecular dynamics simulations Kelvin Helmholtz instability has been observed for the first time at the particle level in two-dimensional strongly coupled Yukawa liquids. At a given coupling strength {Gamma} a subsonic shear profile is superposed on an equilibrated Yukawa liquid and instability is observed. Linear growth rates computed directly from MD simulations are seen to increase with strong coupling. Vortex-roll formation in the nonlinear regime is reported.

Ashwin, J.; Ganesh, R. [Institute For Plasma Research, Bhat, Gandhinagar-382428 (India)

2010-05-28

157

Codimension-3 singularities and Yukawa couplings in F-theory  

Microsoft Academic Search

F-theory is one of the frameworks where all the Yukawa couplings of grand unified theories are generated and their computation is possible. The Yukawa couplings of charged matter multiplets are supposed to be generated around codimension-3 singularity points of a base complex 3-fold, and that has been confirmed for the simplest type of codimension-3 singularities in recent studies. However, the

Hirotaka Hayashi; Teruhiko Kawano; Radu Tatar; Taizan Watari

2009-01-01

158

Phenomenology of a nonstandard top quark Yukawa coupling  

SciTech Connect

There are theoretical speculations that the top quark may have different properties from that predicted by the standard model. We use an effective Lagrangian technique to model such a nonstandard top quark scenario. We parametrize the [ital CP]-violating interactions of the top quark with the bubble wall in terms of an effective top quark Yukawa coupling, then study its effects on electroweak baryogenesis. We also discuss the phenomenology of such an effective Yukawa coupling in low and high energy regions.

Zhang, X.; Lee, S.K.; Whisnant, K.; Young, B. (Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States))

1994-12-01

159

Resolutions of the Coulomb Operator  

NASA Astrophysics Data System (ADS)

The ``Resolution of the Identity Operator'' I ?| ?n>= through the introduction of an infinite complete expansion basis ?n. In practical implementations, where the basis set is finite and incomplete, (2) yields systematic approximations to difficult overlap integrals and is widely used in quantum physics and chemistry. We will present an analogous ``Resolution of the Coulomb Operator'' r12-1 ?| ?n>Coulomb matrix elements eq:RC = and we will discuss the potential utility of (4) in the efficient treatment of the matrix elements that arise in quantum chemistry and elsewhere.

Gill, Peter

2007-03-01

160

Subcycle dynamics of Coulomb asymmetry in strong elliptical laser fields.  

PubMed

We measure photoelectron angular distributions of noble gases in intense elliptically polarized laser fields, which indicate strong structure-dependent Coulomb asymmetry. Using a dedicated semiclassical model, we have disentangled the contribution of direct ionization and multiple forward scattering on Coulomb asymmetry in elliptical laser fields. Our theory quantifies the roles of the ionic potential and initial transverse momentum on Coulomb asymmetry, proving that the small lobes of asymmetry are induced by direct ionization and the strong asymmetry is induced by multiple forward scattering in the ionic potential. Both processes are distorted by the Coulomb force acting on the electrons after tunneling. Lowering the ionization potential, the relative contribution of direct ionization on Coulomb asymmetry substantially decreases and Coulomb focusing on multiple rescattering is more important. We do not observe evident initial longitudinal momentum spread at the tunnel exit according to our simulation. PMID:23889395

Li, Min; Liu, Yunquan; Liu, Hong; Ning, Qicheng; Fu, Libin; Liu, Jie; Deng, Yongkai; Wu, Chengyin; Peng, Liangyou; Gong, Qihuang

2013-07-09

161

Coulomb's Law - Synthesis  

NSDL National Science Digital Library

A PhysLet based simulation using a graphical approach to explore Coulomb's law. In this interesting problem, the user has to identify three charges based on the trajectory that a test charge follows and based on the force graph.

Papadopoulos, Costas

2008-06-24

162

Extended optical model analyses of elastic scattering and fusion cross section data for the {sup 12}C+{sup 208}Pb system at near-Coulomb-barrier energies by using a folding potential  

SciTech Connect

Simultaneous {chi}{sup 2} analyses are performed for elastic scattering and fusion cross section data for the {sup 12}C+{sup 208}Pb system at near-Coulomb-barrier energies by using the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and also that both DR and fusion parts of the polarization potential determined from the {chi}{sup 2} analyses satisfy separately the dispersion relation. Furthermore, it is shown that the imaginary parts of both DR and fusion potentials at the strong absorption radius change very rapidly, which results in a typical threshold anomaly in the total imaginary potential as observed with tightly bound projectiles such as {alpha}-particle and {sup 16}O.

So, W. Y. [Department of Physics, University of Texas, Austin, Texas 78712 (United States); Department of Radiological Science, Catholic University of Pusan, Pusan 609-757 (Korea, Republic of); Udagawa, T. [Department of Physics, University of Texas, Austin, Texas 78712 (United States); Hong, S. W.; Kim, B. T. [Department of Physics and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2008-02-15

163

Phonon spectrum measured in a 1D Yukawa chain  

NASA Astrophysics Data System (ADS)

An experiment is reported for a 1D chain of charged microspheres with a Yukawa pair potential. This work is motivated by chains of colloids confined in laser beams and Xe atoms confined in carbon nanotubes. Polymer microspheres are dispersed in a weakly- ionized rarefied gas. The resulting suspension, termed a dusty plasma, is a colloidal crystal. Depending on the confinement geometry, these suspensions can be 1D, 2D, or 3D. Dusty plasma suspensions resemble charge-stabilized colloidal suspensions: they both allow precise tracking of particles with digital video microscopy and manipulation of particles with lasers. The suspension in a dusty plasma is distinguished, however, by its extreme parameters: it is vastly softer, more weakly damped, and more dilute than colloids in water. In this talk, we describe oscillations of a non-bifurcated 1D chain. Using particle tracking to compute velocities of individual microspheres, we find the phonon spectrum. This is done both with and without time-modulated laser manipulation to excite phonons at a specific frequency. The measured spectrum is compared to a theoretical dispersion relation. Work supported by NASA and DOE.

Goree, J.

2005-03-01

164

Binary dusty plasma Coulomb balls.  

PubMed

We investigated the mixing and segregation of a system consisting of two different species of particles, having different charges, interacting through a pure Coulomb potential, and confined in a three-dimensional parabolic trap. The structure of the cluster and its normal mode spectrum are analyzed as a function of the relative charge and the relative number of different types of particles. We found that (a) the system can be in a mixed or segregated state depending on the relative charge ratio parameter and (b) the segregation process is mediated by a first or second order structural phase transition which strongly influences the magic cluster properties of the system. PMID:21599144

Apolinario, S W S; Peeters, F M

2011-04-29

165

Effect of operational parameters on Coulombic efficiency in bioelectrochemical systems.  

PubMed

To create an efficient bioelectrochemical system, a high Coulombic efficiency is required. This efficiency is a direct measure for the competition between electrogens and methanogens when acetate is used as substrate. In this study the Coulombic efficiency in a microbial electrolysis cell was investigated. As a result of an increase in substrate concentration from 1 to 35 mM, the current density increased to 21.1A/m(2), while the Coulombic efficiency decreased to 52%. As a result of an increase in anode potential from -450 to -0.250 mV, the current density increased to 20.9A/m(2), while the Coulombic efficiency increased 21%. Knowledge about the substrate affinity and growth kinetics is crucial to control the Coulombic efficiency. Further research is required to optimize strategies to find a balance between the Coulombic efficiency, current density and removal rate of organic material. PMID:22004593

Sleutels, Tom H J A; Darus, Libertus; Hamelers, Hubertus V M; Buisman, Cees J N

2011-09-29

166

Giant Coulomb blockade magnetoresistance  

SciTech Connect

We show that the Coulomb blockade voltage can be made to depend strongly on the electron spin in a thin magnetic granular layer inserted in the middle of an insulating layer of a tunnel junction. This strong spin dependence is predicted from the spin-dependent inter-granular conductance through any of the following effects within the granular layer, giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), colossal magnetoresistance (CMR), or GMR through a polymer spacer. The resulting Coulomb blockade magnetoresistance (CBMR) ratio can exceed the magnetoresistance ratio of the granular layer itself by orders of magnitude. Unlike other magenetoresistance effects, the CBMR effect does not require magnetic electrodes.

Zhang, Xiaoguang [ORNL; Wen, Z. C. [Institute of Physics, Chinese Academy of Science; Wei, H. X. [Institute of Physics, Chinese Academy of Science; Han, Prof. X. F. [Institute of Physics, Chinese Academy of Science

2010-01-01

167

Nonperturbative Effects on Seven-Brane Yukawa Couplings  

NASA Astrophysics Data System (ADS)

We analyze nonperturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show, in particular, that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem of certain F-theory local models. We provide explicit expressions for the nonperturbative correction to the seven-brane superpotential, and check that it is related to a noncommutative deformation to the tree-level superpotential via a Seiberg-Witten map.

Marchesano, Fernando; Martucci, Luca

2010-06-01

168

Nonperturbative effects on seven-brane Yukawa couplings.  

PubMed

We analyze nonperturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show, in particular, that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem of certain F-theory local models. We provide explicit expressions for the nonperturbative correction to the seven-brane superpotential, and check that it is related to a noncommutative deformation to the tree-level superpotential via a Seiberg-Witten map. PMID:20867226

Marchesano, Fernando; Martucci, Luca

2010-06-07

169

Dark Matter and Yukawa Unification with Massive Neutrinos  

SciTech Connect

We revisit the WMAP dark matter constraints on Yukawa Unification in the presence of massive neutrinos. The large neutrino mixing indicated by the data modifies the predictions for the bottom quark mass, and enables Yukawa also for large tan {beta}, and for positive {mu} that were previously disfavoured. As a result, the allowed parameter space for neutralino dark matter also increases, particularly for areas with resonant enhancement of the neutralino relic density. We also find that the parameter space that is compatible with dark matter, also predicts detectable rates for Lepton Flavour Violation.

Gomez, M. E.; Rodriguez-Quintero, J. [Departamento de Fisica Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Lola, S.; Naranjo, P. [Department of Physics, University of Patras, 26500 Patras (Greece)

2009-04-17

170

Nonperturbative Effects on Seven-Brane Yukawa Couplings  

SciTech Connect

We analyze nonperturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show, in particular, that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem of certain F-theory local models. We provide explicit expressions for the nonperturbative correction to the seven-brane superpotential, and check that it is related to a noncommutative deformation to the tree-level superpotential via a Seiberg-Witten map.

Marchesano, Fernando [CERN PH-TH Division, CH-1211 Geneva (Switzerland); Martucci, Luca [ASC, LMU-Muenchen, Theresienstrasse 37, D-80333 Munich (Germany)

2010-06-11

171

THE "MOHR-COULOMB" ERROR  

NSDL National Science Digital Library

CoulombÃÂs Essay on limiting statics stated that newly remoulded soil has no cohesion. Critical state soil mechanics agrees with this principle, here called CoulombÃÂs law. The Mohr-Coulomb equation wrongly interpreted strength data. The two components of peak strength really are friction and interlocking.

Schofield, Andrew N.

2008-09-23

172

Hideki Yukawa January 23, 1907 - September 8, 1981---  

Microsoft Academic Search

Hideki Yukawa took the first step in his research in 1929 as an associate at Kyoto Imperial University (nowadays called Kyoto University). Most Japanese physicists of those days were isolated far from Western centers of physical science, where the `Sturm und Drang' of astonighing developments in the twentieth century physics had been roaring. There were only a handful of physicists

Yasutaka Tanikawa

1981-01-01

173

Gravitational Corrections to Yukawa and phi{sup 4} Interactions  

SciTech Connect

We consider the lowest order quantum gravitational corrections to Yukawa and phi{sup 4} interactions. Our results show that quantum gravity leads to contributions to the running coupling constants if the particles are massive and therefore alters the scaling behavior of the standard model. Furthermore, we find that the gravitational contributions to the running of the masses vanish.

Rodigast, Andreas; Schuster, Theodor [Institut fuer Physik, Humboldt Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)

2010-02-26

174

Yukawa unification: The good, the bad, and the ugly.  

National Technical Information Service (NTIS)

We analyze some consequences of grand unification of the third-generation Yukawa couplings, in the context of the minimal supersymmetric standard model. We address two issues: the prediction of the top quark mass, and the generation of the top-bottom mass...

R. Rattazzi U. Sarid L. J. Hall

1993-01-01

175

Scalar decay constant and Yukawa coupling in walking gauge theories  

SciTech Connect

We propose an approach for the calculation of the Yukawa coupling through the scalar decay constant and the chiral condensate in the context of the extended technicolor . We perform the nonperturbative computation of the Yukawa coupling based on the improved ladder Schwinger-Dyson equation. It turns out that the Yukawa coupling can be larger or smaller than the standard model value, depending on the number N{sub D} of the weak doublets for each technicolor (TC) index. It is thus nontrivial whether or not the huge enhancement of the production of the scalar via the gluon fusion takes place even for a walking TC model with a colored techni-fermion. For the typical one-family TC model near conformality, it is found that the Yukawa coupling is slightly larger than the standard model one, where the expected mass of the scalar bound state is around 500 GeV. In this case, the production cross section via the gluon fusion is considerably enhanced, as naively expected, and hence such a scalar can be discovered/excluded at the early stage of the LHC.

Hashimoto, Michio [Chubu University, 1200 Matsumoto-cho, Kasugai-shi, Aichi, 487-8501 (Japan)

2011-05-01

176

Is Hideki Yukawa's explanation of the strong force correct?  

Microsoft Academic Search

Reexamining Hideki Yukawa's explanation of the strong force using the principles of the Quark Theory and the Vortex Theory, it was discovered that it is possible for a virtual particle to be passed back and forth between the proton and the neutron. This discovery creates a new and revolutionary explanation of the strong force of nature. The creation of the

Victor Vasiliev; Russell Moon

2006-01-01

177

Coulomb effects in quasielastic electron scattering  

SciTech Connect

Coulomb distortion plays an important role in interpreting both (e,e{prime}) and (e,e,{prime}p) reactions in the quasielastic region. A fully distorted partial wave calculation is presented, and the results are compared with the widely-used plane wave approximation and other distorted-wave calculations. The new calculation seems to give higher occupation numbers in the (e,e{prime}p) reactions. The usefulness of the (e,e{prime}p) reaction in studying different nuclear optical potentials is discussed. Also considered are the effects of electron Coulomb distortion in the separation of longitudinal and transverse structure functions in (e.e{prime}).

Onley, D.S.

1991-12-31

178

Coulomb effects in quasielastic electron scattering  

SciTech Connect

Coulomb distortion plays an important role in interpreting both (e,e{prime}) and (e,e,{prime}p) reactions in the quasielastic region. A fully distorted partial wave calculation is presented, and the results are compared with the widely-used plane wave approximation and other distorted-wave calculations. The new calculation seems to give higher occupation numbers in the (e,e{prime}p) reactions. The usefulness of the (e,e{prime}p) reaction in studying different nuclear optical potentials is discussed. Also considered are the effects of electron Coulomb distortion in the separation of longitudinal and transverse structure functions in (e.e{prime}).

Onley, D.S.

1991-01-01

179

Nonlinear Coulomb Effects in Transport Channels.  

National Technical Information Service (NTIS)

Using the perturbation method the formulae for the particle beam phase volume increase under the nonlinear field effect are derived. Expressions for potential of proper Coulomb field of the beam with elliptical symmetry are obtained. It is shown that in a...

P. R. Zenkevich A. P. Korolev

1987-01-01

180

Coulomb heating behavior of fast light diclusters  

SciTech Connect

In this Brief Report we present data on the Coulomb heating induced by B{sub 2}{sup +} molecular beams channeling along Si<100> direction in a large energy interval (800 up to 2200 keV/atom). The simultaneous detection of Si Kalpha x rays and backscattered particles established the necessary grounds for the calculation of the Coulomb heating, i.e., the molecular transversal energy due to the Coulomb explosion transferred to the target atoms. By combining the present results with those previously published for H{sub 2}{sup +} at 150 keV/atom and for C{sub 2}{sup +} at energies from 800 up to 2200 keV/atom, we were able to obtain two striking results. First, all the experimental values fall on a straight line when they are plotted as a function of the stored potential energy per ion, suggesting some kind of 'universal behavior'. Second, the analysis of the whole set of experimental data shows that the Coulomb heating scales with 2/3 of the stored potential energy per ion, regardless the ion atomic number. This result is in agreement with theoretical predictions.

Fadanelli, R. C.; Behar, M.; Dias, J. F. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, CP 15051, CEP 91501-970 Porto Alegre, RS (Brazil)

2010-04-01

181

Nyström Method for the Coulomb and Screened Coulomb Potentials  

NASA Astrophysics Data System (ADS)

In this paper, we show that the simple Nyström method can yield very accurate eigenvalues and eigenfunctions not only for large principal quantum number but also for large angular momentum quantum number. We demonstrate that the furcation phenomenon emerging in the calculated eigenfunctions can be regarded as an indicator for the bad behavior of the integral equation and the unreliability of the obtained results.

Chen, Jiao-Kai

2013-11-01

182

Nyström Method for the Coulomb and Screened Coulomb Potentials  

NASA Astrophysics Data System (ADS)

In this paper, we show that the simple Nyström method can yield very accurate eigenvalues and eigenfunctions not only for large principal quantum number but also for large angular momentum quantum number. We demonstrate that the furcation phenomenon emerging in the calculated eigenfunctions can be regarded as an indicator for the bad behavior of the integral equation and the unreliability of the obtained results.

Chen, Jiao-Kai

2013-05-01

183

Hideki Yukawa ---January 23, 1907 - September 8, 1981---  

NASA Astrophysics Data System (ADS)

Hideki Yukawa took the first step in his research in 1929 as an associate at Kyoto Imperial University (nowadays called Kyoto University). Most Japanese physicists of those days were isolated far from Western centers of physical science, where the `Sturm und Drang' of astonighing developments in the twentieth century physics had been roaring. There were only a handful of physicists in Japan who had already set to work in quantum physics, but never any one working on the quantum field theory and theoretical nuclear physics. Yukawa had to initiate his study of these frontiers of physical science by himself, without any teacher or senior scholar in this field. In 1935, Yukawa published his first paper with the title ``On the Interaction of Elementary Particles. I'', in which he developed the revolutionary idea of the meson theory. Although even the term `elementary particle' was not so popular in those days, the meson theory was proposed as a unified theory of interactions of elementary particles. His theory opened up a new fundamental view of Nature. This event might be regarded as a miracle in the history of Japanese physics. Through all of his works and thoughts, we are impressed by the simplicity of approach, the unfailing intuition and the creativity of a great master, which are deep-rooted in his culture. A sketch of his life, mainly based on his autobiographical material and partly based on the present writer's personal recollection, is presented to show his thought and activity.

Tanikawa, Y.

1981-10-01

184

Yukawa couplings and fermion mass structure in F-theory GUTs  

Microsoft Academic Search

The calculation of Yukawa couplings in F-theory GUTs is developed. The method is applied to the top and bottom Yukawa couplings\\u000a in an SU(5)? model of fermion masses based on family symmetries coming from the SU(5) factor in the underlying E(8) theory. The remaining Yukawa couplings involving the light quark generations are determined by the Froggatt Nielsen non-renormalisable\\u000a terms generated

G. K. Leontaris; G. G. Ross

2011-01-01

185

An Integral Transform of Coulomb Green's Function via Sturmian Representation and Off-Shell Scattering  

NASA Astrophysics Data System (ADS)

By exploiting the term by term separability of the Sturmian function representation of the Coulomb Green's function an integral transform of the corresponding outgoing wave Green's function, that plays a crucial role in the studies of off-shell properties of the Coulomb and Coulomb-like interactions, is derived. Working in the representation space the off-shell Jost solutions and T-matrices for motion in Coulomb and Coulomb-modified nuclear potentials are expressed in terms of simple expressions involving hypergeometric functions. The effectiveness of our constructed expressions for the T-matrices is examined through a model calculation.

Laha, U.; Bhoi, J.

2013-11-01

186

Two- and Three-Body Coulomb Solution Method in a Momentum Space  

NASA Astrophysics Data System (ADS)

We present a method to calculate two- and three-body amplitudes including the Coulomb potential in a momentum space. Our aim is to obtain the exact two-body Coulomb amplitudes used in three-body calculations, which reproduce the analytic phase shifts. For the purpose, our theory is based on the modified Coulomb potential (MCP) whose Fourier transformation is equivalent to the pure Coulomb potential in a configuration space, and the two-potential theory with an auxiliary potential. Moreover, one can analytically determine a decisive range R dec in the MCP. By using the MCP, we obtain the two-body Coulomb modified nuclear amplitude as well as the pure Coulomb amplitude. The calculated phase shift are very good fitting with the experimental data.

Hiratsuka, Y.; Oryu, S.

2013-03-01

187

Superdiffusion in two-dimensional Yukawa liquids  

SciTech Connect

Superdiffusion of two-dimensional (2D) liquids was studied using an equilibrium molecular dynamics simulation. At intermediate temperatures, the mean-squared displacement, probability distribution function (PDF), and velocity autocorrelation function (VACF) all indicate superdiffusion; the VACF has a long-time tail; and the PDF indicates no Levy flights. These effects are predicted to occur in 2D dusty plasmas and other 2D liquids that can be modeled with a long-range repulsive potential.

Liu Bin; Goree, J. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

2007-01-15

188

Detailed analysis of the three-quark potential in SU(3) lattice QCD  

NASA Astrophysics Data System (ADS)

The static three-quark (3Q) potential is studied in detail using SU(3) lattice QCD with 123×24 at ?=5.7 and 163×32 at ?=5.8, 6.0 at the quenched level. For more than 300 different patterns of the 3Q systems, we perform the accurate measurement of the 3Q Wilson loop with the smearing method, which reduces excited-state contaminations, and present the lattice QCD data of the 3Q ground-state potential V3Q. We perform the detailed fit analysis on V3Q in terms of the Y Ansatz both with the continuum Coulomb potential and with the lattice Coulomb potential, and find that the lattice QCD data of the 3Q potential V3Q are well reproduced within a few percent deviation by the sum of a constant, the two-body Coulomb term and the three-body linear confinement term ?3QLmin, with Lmin the minimal value of the total length of color flux tubes linking the three quarks. From the comparison with the Q-Q¯ potential, we find a universality of the string tension as ?3Q??QQ¯ and the one-gluon-exchange result for the Coulomb coefficients as A3Q?1/2AQQ¯. We investigate also the several fit analyses with the various Ansätze: the Y Ansatz with the Yukawa potential, the ? Ansatz and a more general Ansatz including the Y and the ? Ansätze in some limits. All these fit analyses support the Y Ansatz on the confinement part in the 3Q potential V3Q, although V3Q seems to be approximated by the ? Ansatz with ???0.53?.

Takahashi, T. T.; Suganuma, H.; Nemoto, Y.; Matsufuru, H.

2002-06-01

189

Coulomb clusters in RETRAP  

SciTech Connect

Storage rings and Penning traps are being used to study ions in their highest charge states. Both devices must have the capability for ion cooling in order to perform high precision measurements such as mass spectrometry and laser spectroscopy. This is accomplished in storage rings in a merged beam arrangement where a cold electron beam moves at the speed of the ions. In RETRAP, a Penning trap located at Lawrence Livermore National Laboratory, a sympathetic laser/ion cooling scheme has been implemented. In a first step, singly charged beryllium ions are cooled electronically by a tuned circuit and optically by a laser. Then hot, highly charged ions are merged into the cold {ital Be} plasma. By collisions, their kinetic energy is reduced to the temperature of the {ital Be} plasma. First experiments indicate that the highly charged ions form a strongly coupled plasma with a Coulomb coupling parameter exceeding 1000. {copyright} {ital 1999 American Institute of Physics.}

Steiger, J.; Beck, B.R.; Gruber, L.; Schneider, D. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Holder, J.P. [Texas AM University, College Station, Texas 77843-4242 (United States)

1999-01-01

190

Coulomb clusters in RETRAP  

SciTech Connect

Storage rings and Penning traps are being used to study ions in their highest charge states. Both devices must have the capability for ion cooling in order to perform high precision measurements such as mass spectrometry and laser spectroscopy. This is accomplished in storage rings in a merged beam arrangement where a cold electron beam moves at the speed of the ions. In RETRAP, a Penning trap located at Lawrence Livermore National Laboratory, a sympathetic laser/ion cooling scheme has been implemented. In a first step, singly charged beryllium ions are cooled electronically by a tuned circuit and optically by a laser. Then hot, highly charged ions are merged into the cold Be plasma. By collisions, their kinetic energy is reduced to the temperature of the Be plasma. First experiments indicate that the highly charged ions form a strongly coupled plasma with a Coulomb coupling parameter exceeding 1000.

Steiger, J.; Beck, B. R.; Gruber, L.; Schneider, D. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Church, D. A.; Holder, J. P. [Texas A and M University, College Station, Texas 77843-4242 (United States)

1999-01-15

191

Coulomb clusters in RETRAP  

SciTech Connect

Storage rings and Penning traps are being used to study ions in their highest charge states. Both devices must have the capability for ion cooling in order to perform high precision measurements such as mass spectrometry and laser spectroscopy. This is accomplished in storage rings in a merged beam arrangement where a cold electron beam moves at the speed of the ions. In RETRAP, a Penning trap located at Lawrence Livermore National Laboratory, a sympathetic laser/ion cooling scheme has been implemented. In a first step, singly charged beryllium ions are cooled electronically by a tuned circuit and optically by a laser. Then hot, highly charged ions are merged into the cold Be plasma. By collisions, their kinetic energy is reduced to the temperature of the Be plasma. First experiments indicate that the highly charged ions form a strongly coupled plasma with a Coulomb coupling parameter.

Beck, B. R.; Church, D. A.; Gruber, L.; Holder, J. P.; Schneider, D.; Steiger, J.

1998-10-22

192

Coulomb expansion: analytical solutions.  

PubMed

Exact and approximate analytical solutions are presented, describing expansion of a cloud of charged particles in one, two, and three dimensions (assuming the planar, axial, and spherical symmetries, respectively). The expansion occurs in a gas or dilute plasma, where the screening is unimportant, so that particles interact with each other via Coulomb repulsive forces. It is shown that, irrespective of dimensionality, the density distribution remains homogeneous across the cloud and the velocity increases linearly towards the cloud boundary. The density evolution obeys a universal dependence, asymptotically decreasing with time as t(-1). It is also shown that in the presence of an inhomogeneous external field the interparticle repulsion becomes negligible at an early stage of expansion and then the density decreases with time exponentially. PMID:23496647

Ivlev, A V

2013-02-28

193

Dust grains in plasma with coulomb collisions  

Microsoft Academic Search

Dust-grain charging in a dense plasma with electron and ion concentration up to 1016cm?3, where the electron transport cross section is dominated by Coulomb collisions, was investigated. It was established that\\u000a the charge of an isolated dust grain increases with electron concentration, whereas its potential is almost constant in the\\u000a range 1014–1016cm?3 of electron concentrations studied. It is shown that

A. G. Leonov; A. F. Pal’; A. N. Starostin; A. V. Filippov

2003-01-01

194

Coulomb breakup of 7Li for nuclear astrophysics  

NASA Astrophysics Data System (ADS)

A new Coulomb breakup experiment was performed for 7Li with an improved experimental technique and theoretical treatment. Energy spectra of ? particles and tritons were examined to find the signature of post-Coulomb acceleration in the breakup of 7Li at E?t=0. The data revealed the delayed nature of nonresonant breakup of astrophysical relevance that stems from quantum tunneling. Semiclassical discussions are presented of the lifetime of continuum states in 7Li and distortion of relative kinetic energies between ? and t by post-Coulomb acceleration. Dynamical calculations of Coulomb breakup were performed by solving a time-dependent Schrödinger equation. A simple potential model of 7Li was employed. The dynamical calculations reasonably reproduced experimental cross sections for both resonant and nonresonant breakup with two key ingredients: higher order effects and mixture of E1 and E2 multipoles. Considering the dominant role of the first-order E1 nature in adiabatic Coulomb breakup, cross sections in the v?>=vt branch at 7 °-15 ° for 64Zn and 90Zr were used to deduce astrophysical S factors S(E) for t(?,?)7Li. They exhibit a moderate energy dependence at small energies. The strongly energy-dependent S(E) resulted from the previous Coulomb breakup experiment based on cross sections with v?<=vt they are most likely Coulomb distorted and are revised in the present work.

Tokimoto, Y.; Utsunomiya, H.; Yamagata, T.; Ohta, M.; Lui, Y.-W.; Schmitt, R. P.; Typel, S.; Aoki, Y.; Ieki, K.; Katori, K.

2001-03-01

195

Collective modes of quasi-two-dimensional Yukawa liquids.  

PubMed

Particles in dusty plasmas are often confined to a quasi-two-dimensional arrangement. In such layers--besides the formation of compressional and (in-plane) shear waves--an additional collective excitation may also show up, as small-amplitude oscillations of the particles perpendicular to the plane are also possible. We explore through molecular dynamics simulations the properties (fluctuation spectra, dispersion relation, Einstein frequency) of this out-of-plane transverse mode in the strongly coupled liquid phase of Yukawa systems. PMID:15244656

Donkó, Z; Hartmann, P; Kalman, G J

2004-06-01

196

Active nonlinear microrheology in a glass-forming Yukawa fluid.  

PubMed

A molecular dynamics computer simulation of a glass-forming Yukawa mixture is used to study the anisotropic dynamics of a single particle pulled by a constant force. Beyond linear response, a scaling regime is found where a force-temperature superposition principle of a Peclet number holds. In the latter regime, the diffusion dynamics perpendicular to the force can be mapped on the equilibrium dynamics in terms of an effective temperature, whereas parallel to the force a superdiffusive behavior is seen in the long-time limit. This behavior is associated with a hopping motion from cage to cage and can be qualitatively understood by a simple trap model. PMID:22324717

Winter, D; Horbach, J; Virnau, P; Binder, K

2012-01-11

197

Ionic Coulomb blockade in nanopores  

NASA Astrophysics Data System (ADS)

An understanding of the dynamics of ions in nanopores is essential for applications ranging from single-molecule detection to DNA sequencing. We show both analytically and by means of molecular dynamics simulations that under specific conditions ion-ion interactions in nanopores lead to the phenomenon of ionic Coulomb blockade, namely the build up of ions inside a nanopore with specific capacitance impeding the flow of additional ions due to Coulomb repulsion. This is the counterpart of electronic Coulomb blockade observed in mesoscopic systems. We discuss the analogies with and differences from the electronic case as well as experimental situations in which this phenomenon could be detected.

Krems, Matt; Di Ventra, Massimiliano

2013-02-01

198

Critical parameters of hard-core Yukawa fluids within the structural theory  

NASA Astrophysics Data System (ADS)

A purely statistical mechanical approach is proposed to account for the liquid-vapor critical point based on the mean density approximation (MDA) of the direct correlation function. The application to hard-core Yukawa (HCY) fluids facilitates the use of the series mean spherical approximation (SMSA). The location of the critical parameters for HCY fluid with variable intermolecular range is accurately calculated. Good agreement is observed with computer simulation results and with the inverse temperature expansion (ITE) predictions. The influence of the potential range on the critical parameters is demonstrated and the universality of the critical compressibility ratio is discussed. The behavior of the isochoric and isobaric heat capacities along the equilibrium line and the near vicinity of the critical point is discussed in details.

Bahaa Khedr, M.; Osman, S. M.

2012-10-01

199

Singular Potentials with Short Range.  

National Technical Information Service (NTIS)

Previous works have shown the properties and the possibility of useful approximate methods for the Jost functions, and the radial wave functions in the case of Yukawa generalized potentials, less or equally singular than the centrifugal term. Some of thes...

E. Predazzi H. Cornille

1964-01-01

200

Effective interaction between hard sphere colloidal particles in a polymerizing Yukawa solvent  

Microsoft Academic Search

The effective interaction between colloidal hard sphere particles in a Yukawa solvent that can polymerize with the formation of chains and rings is studied and compared with the corresponding results for colloidal hard sphere particles in a solvent of polymerizing hard spheres. The attractive nature of the polymerizing Yukawa solvent particles induces significant changes in the effective interactions between the

R. H. Gee; D. Henderson; A. Kovalenko

1999-01-01

201

Interatomic Coulombic electron capture  

SciTech Connect

In a previous publication [K. Gokhberg and L. S. Cederbaum, J. Phys. B 42, 231001 (2009)] we presented the interatomic Coulombic electron capture process--an efficient electron capture mechanism by atoms and ions in the presence of an environment. In the present work we derive and discuss the mechanism in detail. We demonstrate thereby that this mechanism belongs to a family of interatomic electron capture processes driven by electron correlation. In these processes the excess energy released in the capture event is transferred to the environment and used to ionize (or to excite) it. This family includes the processes where the capture is into the lowest or into an excited unoccupied orbital of an atom or ion and proceeds in step with the ionization (or excitation) of the environment, as well as the process where an intermediate autoionizing excited resonance state is formed in the capturing center which subsequently deexcites to a stable state transferring its excess energy to the environment. Detailed derivation of the asymptotic cross sections of these processes is presented. The derived expressions make clear that the environment assisted capture processes can be important for many systems. Illustrative examples are presented for a number of model systems for which the data needed to construct the various capture cross sections are available in the literature.

Gokhberg, K.; Cederbaum, L. S. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

2010-11-15

202

Coulomb Energy, Vortices, and Confinement  

SciTech Connect

d on 25 Feb 2003 (v1), last revised 10 Apr 2003 (this version, v2))We estimate the Coulomb energy of static quarks from a Monte Carlo calculation of the correlator of timelike link variables in Coulomb gauge. We find, in agreement with Cucchieri and Zwanziger, that this energy grows linearly with distance at large quark separations. The corresponding string tension, however, is several times greater than the accepted asymptotic string tension, indicating that a state containing only static sources, with no constituent gluons, is not the lowest energy flux tube state. The Coulomb energy is also measured on thermalized lattices with center vortices removed by the de Forcrand-D'Elia procedure. We find that when vortices are removed, the Coulomb string tension vanishes.

Greensite, J.; Olejnik, S.

2003-02-25

203

Early LHC phenomenology of Yukawa-bound heavy QQ¯ mesons  

NASA Astrophysics Data System (ADS)

Current limits from the LHC on fourth generation quarks are already at the unitarity bound of 500 GeV or so. If they exist, the strong Yukawa couplings are turning nonperturbative, and may form bound states. We study the domain of mb' and mt' in the range of 500 to 700 GeV, where we expect binding energies are mainly of Yukawa origin, with QCD subdominant. To be consistent with electroweak precision tests, the t' and b' quarks have to be nearly degenerate, exhibiting a new “isospin.” Comparing relativistic expansion with a relativistic bound state approach, we find the most interesting is the production of a color octet, isosinglet vector meson (a “gluon-prime”) via qq¯??8. Leading decay modes are ?8±W?, ?80Z0, and constituent quark decay, with qq¯ and tt¯' and bb¯' subdominant. The color octet, isovector pseudoscalar ?8 meson decays via constituent quark decay, or to Wg. These decay rates are parameterized by the decay constant, the binding energy and mass differences, and Vtb'. For small Vt'b, one could have a spectacular signal of WWg, where a soft W accompanies a very massive Wg pair. In general, however, one has high multiplicity signals with b, W, and t jet substructures that are not so different from the t't¯' and b'b¯' search.

Enkhbat, Tsedenbaljir; Hou, Wei-Shu; Yokoya, Hiroshi

2011-11-01

204

Is Hideki Yukawa's explanation of the strong force correct?  

NASA Astrophysics Data System (ADS)

Reexamining Hideki Yukawa's explanation of the strong force using the principles of the Quark Theory and the Vortex Theory, it was discovered that it is possible for a virtual particle to be passed back and forth between the proton and the neutron. This discovery creates a new and revolutionary explanation of the strong force of nature. The creation of the strong force appears to be the combination of four processes at work in the nucleus: virtual particles, intrinsic magnetism, ``nuclear gravity'', and gluons. 1. V.V. Vasiliev, R.G. Moon, The bases of the vortex theory, Book of abstracts The 53 International Meeting on Nuclear Spectroscopy and Nuclear structure St. Petersburg, Russia, 2003, p.251. 2. H. Yukawa, Tabibito, (World Scientific, Singapore, 1982), p. 190-202. 3. K. Gridnev, V.V. Vasiliev, R.G. Moon, The Photon Acceleration Effect, Book of abstracts, OMEGA 5 -- Symposium on Origin of Matter and Evolution of Galaxies, Nov 8-11, University of Tokyo, Tokyo Japan. 4. R.G. Moon, V.V. Vasiliev. Explanation of the Conservation of Lepton Number, Book of abstracts LV. National Conference on Nuclear Physics, Frontiers in the Physics of Nucleus, June 28-July 1, 2005, Saint-Petersburg, Russia, 2005, p. 347.5. .

Vasiliev, Victor; Moon, Russell

2006-11-01

205

Is Hideki Yukawa's explanation of the strong force correct?  

NASA Astrophysics Data System (ADS)

Reexamining Hideki Yukawa's explanation of the strong force using the principles of the Quark Theory and the Vortex Theory, it was discovered that it is possible for a virtual particle to be passed back and forth between the proton and the neutron. This discovery creates a new and revolutionary explanation of the strong force of nature. The creation of the strong force appears to be the combination of four processes at work in the nucleus: virtual particles, intrinsic magnetism, ``nuclear gravity'', and gluons. 1. V.V. Vasiliev, R.G. Moon, The bases of the vortex theory, Book of abstracts The 53 International Meeting on Nuclear Spectroscopy and Nuclear structure St. Petersburg, Russia, 2003, p.251. 2. H. Yukawa, Tabibito, (World Scientific, Singapore, 1982), p. 190-202. 3. K. Gridnev, V.V. Vasiliev, R.G. Moon, The Photon Acceleration Effect, Book of abstracts, OMEGA 5 -- Symposium on Origin of Matter and Evolution of Galaxies, Nov 8-11, University of Tokyo, Tokyo Japan. 4. R.G. Moon, V.V. Vasiliev. Explanation of the Conservation of Lepton Number, Book of abstracts LV. National Conference on Nuclear Physics, Frontiers in the Physics of Nucleus, June 28-July 1, 2005, Saint-Petersburg, Russia, 2005, p. 347.5. .

Vasiliev, Victor; Moon, Russell

2006-10-01

206

Empirical formulas for the fermion spectra and Yukawa matrices  

NASA Astrophysics Data System (ADS)

We present empirical relations that connect the dimensionless ratios of low energy fermion masses for the charged lepton, up-type quark and down-type quark sectors and the CKM elements: leftlvert V_{us}rightrvert ? [ md/ms ]^{1/2} ? [ mu/mc ]^{1/4} ? 3 [ me/m_{?} ]^{1/2} and 1/2 leftlvert V_{cb}/V_{us}rightrvert ? [ ms3/m_{b2md} ]^{1/2} ? [ mc3/m_{t2mu} ]^{1/2} ? 1/9 [ m_{?}3/m_{tau2me} ]^{1/2}. Explaining these relations from first principles imposes strong constraints on the search for the theory of flavor. We present a simple set of normalized Yukawa matrices, with only two real parameters and one complex phase, which accounts with precision for these mass relations and for the CKM matrix elements and also suggests a simpler parametrization of the CKM matrix. The proposed Yukawa matrices accommodate the measured CP-violation, giving a particular relation between standard model CP-violating phases, ? = {Arg} [ 2 - mathrm {e}^{-mathrm i?} ]. According to this relation the measured value of ? is close to the maximum value that can be reached, ?_{max} = 30^{circ} for ? = 60^{circ}. Finally, the particular mass relations between the quark and charged lepton sectors find their simplest explanation in the context of grand unified models through the use of the Georgi-Jarlskog factor.

Ferrandis, J.

2004-12-01

207

Mapping Dirac quasiparticles near a single Coulomb impurity on graphene  

NASA Astrophysics Data System (ADS)

The response of Dirac fermions to a Coulomb potential is predicted to differ significantly from how non-relativistic electrons behave in traditional atomic and impurity systems. Surprisingly, many key theoretical predictions for this ultra-relativistic regime have not been tested. Graphene, a two-dimensional material in which electrons behave like massless Dirac fermions, provides a unique opportunity to test such predictions. Graphene's response to a Coulomb potential also offers insight into important material characteristics, including graphene's intrinsic dielectric constant, which is the primary factor determining the strength of electron-electron interactions in graphene. Here we present a direct measurement of the nanoscale response of Dirac fermions to a single Coulomb potential placed on a gated graphene device. Scanning tunnelling microscopy was used to fabricate tunable charge impurities on graphene, and to image electronic screening around them for a Q=+1|e| charge state. Electron-like and hole-like Dirac fermions were observed to respond differently to a Coulomb potential. Comparing the observed electron-hole asymmetry to theoretical simulations has allowed us to test predictions for how Dirac fermions behave near a Coulomb potential, as well as extract graphene's intrinsic dielectric constant: ?g=3.0+/-1.0. This small value of ?g indicates that electron-electron interactions can contribute significantly to graphene properties.

Wang, Yang; Brar, Victor W.; Shytov, Andrey V.; Wu, Qiong; Regan, William; Tsai, Hsin-Zon; Zettl, Alex; Levitov, Leonid S.; Crommie, Michael F.

2012-09-01

208

Regularization of the Coulomb scattering problem  

SciTech Connect

The exact solution of the Schroedinger equation for the Coulomb potential is used within the scope of both stationary and time-dependent scattering theories in order to find the parameters which determine the regularization of the Rutherford cross section when the scattering angle tends to zero but the distance r from the center remains finite. The angular distribution of the particles scattered in the Coulomb field is studied on rather a large but finite distance r from the center. It is shown that the standard asymptotic representation of the wave functions is inapplicable in the case when small scattering angles are considered. The unitary property of the scattering matrix is analyzed and the 'optical' theorem for this case is discussed. The total and transport cross sections for scattering the particle by the Coulomb center proved to be finite values and are calculated in the analytical form. It is shown that the effects under consideration can be important for the observed characteristics of the transport processes in semiconductors which are determined by the electron and hole scattering by the field of charged impurity centers.

Baryshevskii, V.G.; Feranchuk, I.D.; Kats, P.B. [Byelorussian State University, 4, F. Skariny Av., 220050, Minsk (Belarus)

2004-11-01

209

Approximative treatment of the Coulomb exchange interaction of clusters  

NASA Astrophysics Data System (ADS)

In case of the p-? system, the Coulomb exchange potential of the resonating group model and of the fish bone optical model are compared with each other. It is seen that the difference between the two approximations arises mainly from the unrealistic shortdistance behaviour of the proton-proton e 2/ r potential, which has been assumed in both models. In case of the ?-16O system, it is demonstrated that the importance of the Coulomb exchange potential can be very much reduced by an off-shell transformation.

Orlowski, M.; Schmid, E. W.

1982-03-01

210

Collective excitations of a spherically confined Yukawa plasma  

SciTech Connect

The complete spectrum of eigenmodes of a spherically confined Yukawa plasma is presented, based on first-principle molecular dynamics simulations. These results are compared with a recent fluid theory for the multipole modes of this system [H. Kaehlert and M. Bonitz, Phys. Rev. E 82, 036407 (2010)] and with the exact N-particle eigenmodes in the crystalline phase. Simulations confirm the existence of high-order modes found in cold fluid theory. We investigate the influence of screening, coupling, and friction on the mode spectra in detail. Good agreement between theory and simulation is found for weak to moderate screening and low-order modes. In addition, a number of new modes are observed which are missing in the fluid theory. The relations between the breathing mode in the fluid theory, simulation, and the crystal eigenmode are investigated in further detail.

Kaehlert, H.; Bonitz, M. [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts Universitaet zu Kiel, D-24098 Kiel (Germany)

2011-05-15

211

Collective modes in two-dimensional binary Yukawa systems.  

PubMed

We analyze via theoretical approaches and molecular dynamics simulations the collective mode structure of strongly coupled two-dimensional binary Yukawa systems, for selected density, mass, and charge ratios, both in the liquid and crystalline solid phases. Theoretically, the liquid phase is described through the quasilocalized charge approximation (QLCA) approach, while in the crystalline phase we study the centered honeycomb and the staggered rectangular crystal structures through the standard harmonic phonon approximation. We identify "longitudinal" and "transverse" acoustic and optic modes and find that the longitudinal acoustic mode evolves from its weakly coupled counterpart in a discontinuous nonperturbative fashion. The low-frequency acoustic excitations are governed by the oscillation frequency of the average atom, while the high-frequency optic excitation frequencies are related to the Einstein frequencies of the systems. PMID:23679526

Kalman, Gabor J; Hartmann, Peter; Donkó, Zoltán; Golden, Kenneth I; Kyrkos, Stamatios

2013-04-12

212

Early LHC phenomenology of Yukawa-bound heavy QQ mesons  

SciTech Connect

Current limits from the LHC on fourth generation quarks are already at the unitarity bound of 500 GeV or so. If they exist, the strong Yukawa couplings are turning nonperturbative, and may form bound states. We study the domain of m{sub b'} and m{sub t'} in the range of 500 to 700 GeV, where we expect binding energies are mainly of Yukawa origin, with QCD subdominant. To be consistent with electroweak precision tests, the t' and b' quarks have to be nearly degenerate, exhibiting a new 'isospin'. Comparing relativistic expansion with a relativistic bound state approach, we find the most interesting is the production of a color octet, isosinglet vector meson (a 'gluon-prime') via qq-bar{yields}{omega}{sub 8}. Leading decay modes are {pi}{sub 8}{sup {+-}}W{sup {+-}}, {pi}{sub 8}{sup 0}Z{sup 0}, and constituent quark decay, with qq and tt-bar' and bb' subdominant. The color octet, isovector pseudoscalar {pi}{sub 8} meson decays via constituent quark decay, or to Wg. These decay rates are parameterized by the decay constant, the binding energy and mass differences, and V{sub tb'}. For small V{sub t'b}, one could have a spectacular signal of WWg, where a soft W accompanies a very massive Wg pair. In general, however, one has high multiplicity signals with b, W, and t jet substructures that are not so different from the t't-bar' and b'b-bar' search.

Enkhbat, Tsedenbaljir [Department of Physics, National Taiwan University, Taipei, Taiwan 10617 (China); Hou, Wei-Shu; Yokoya, Hiroshi [Department of Physics, National Taiwan University, Taipei, Taiwan 10617 (China); National Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan 10617 (China)

2011-11-01

213

Coulomb blockade in quantum boxes  

NASA Astrophysics Data System (ADS)

The charging of a quantum box connected to a lead by a single-mode point contact is solved for arbitrary temperatures, tunneling amplitudes, and gate voltages, using a variant of Wilson’s numerical renormalization group. The charge inside the box and the capacitance of the junction are calculated on equal footing for all physical regimes, including weak tunneling, near perfect transmission, and the crossover regime in between. At the charge plateaus, perturbation theory is found to break down at fairly small tunneling amplitudes. Near perfect transmission, we confirm Matveev’s scenario for the smearing of the Coulomb-blockade staircase. A surprising reentrance of the Coulomb-blockade staircase is found for large tunneling amplitudes. At the degeneracy points, we obtain two-channel Kondo behavior directly from the Coulomb-blockade Hamiltonian, without the restriction to two charge configurations or the introduction of an effective cutoff.

Lebanon, Eran; Schiller, Avraham; Anders, Frithjof B.

2003-07-01

214

On the Coulomb shifts of nuclear resonances at low energies  

SciTech Connect

The relationship between the shift of a resonance and the interacion potential is obtained in the frame of coupling constant evolution method. Analysis of the Coulomb shifts of resonance energies and widths has been carried out for nuclear cluster systems at low energies. The nature of these shifts is investigated in the examples of p, {alpha} and p,6Li scatterings. For simplicity a model using separable potentials describing two-body nuclear scattering resonances. The results of the calculation are in accordance with experimental data. In the case of the two {alpha}-particles system the relationship shows that the Coulomb shift of {alpha}, {alpha}-resonance remains small.

Takibayev, N. [Center of Basic and Ecological Research, 99-35 Abaya Ave, 480072 Almaty (Kazakhstan)

2005-05-06

215

Studies of Coulomb Gauge QCD  

SciTech Connect

Here we will discuss how the nonabelian Coulomb kernel exhibits confinement already at the mean field level. In the heavy quark limit residual interactions between heavy quarks and transverse gluons are spin dependent i.e., relativistic and can be calculated using the Foldy-Wouthuysen transformation. This makes the Coulomb gauge suitable for studying the nonrelativistic limit. Finally it is possible to use standard mean field techniques to define quasiparticle excitations, which, as we discuss below, have similar properties to what is usually assumed about constituent quarks in the light quark sector.

Adam P. Szczepaniak; Eric S. Swanson

2000-12-12

216

Coulomb interactions in particle beams  

SciTech Connect

This book develops analytical and computer models for beams in which Coulomb interactions are important. The research into the different phenomena of Coulomb interactions in particle beams is stimulated by developments in the field of electron beam lithography for VLSI electronics. The standard theory of charged particle optics breaks down for intense beams in which interactions between particles are significant. This monograph is devoted to the theory of these intense beams, which are not only used in VLSI electronics but also in scanning electron microscopes. The theory is also applicable to focused ion beams, which are used in VLSI mask repair.

Jansen, G.H. (Royal Dutch Shell Lab., Amsterdam (NL))

1990-01-01

217

Renormalization in Coulomb gauge QCD  

SciTech Connect

Research Highlights: > The Hamiltonian in the Coulomb gauge of QCD contains a non-linear Christ-Lee term. > We investigate the UV divergences from higher order graphs. > We find that they cannot be absorbed by renormalization of the Christ-Lee term. - Abstract: In the Coulomb gauge of QCD, the Hamiltonian contains a non-linear Christ-Lee term, which may alternatively be derived from a careful treatment of ambiguous Feynman integrals at 2-loop order. We investigate how and if UV divergences from higher order graphs can be consistently absorbed by renormalization of the Christ-Lee term. We find that they cannot.

Andrasi, A., E-mail: aandrasi@irb.hr ['Rudjer Boskovic' Institute, Zagreb (Croatia); Taylor, John C., E-mail: J.C.Taylor@damtp.cam.ac.uk [Department of Applied Mathematics and Theoretical Physics, University of Cambridge (United Kingdom)

2011-04-15

218

Yukawa independent constraints for two-Higgs-doublet models with a 125 GeV Higgs boson  

NASA Astrophysics Data System (ADS)

In this paper various constraints for the parameter spaces of two variants of the two-Higgs-doublet model with a Z2-symmetric potential are reconsidered, including the LHC data on existence of a 125 GeV Higgs-like boson. We analyze the model in which only one of the doublets develops a nonzero vacuum expectation value (VEV)—the inert doublet model (IDM) and the mixed model where both of the doublets have nonzero VEVs. Positivity constraints, conditions determining the type of the vacuum, perturbative unitarity condition, constraints following from electroweak precision tests together with the LEP bounds on masses of the scalars are included in the analysis. The analysis is performed without specific assumptions regarding the Yukawa sector. For the IDM constraints on quartic couplings and masses of the scalars as well as their implications for dark matter scenarios are presented. A new type of bound on the mass parameter of the potential coming from the condition for the existence of the inert vacuum is given. In the mixed model a strong bound on the value of tan??, 0.18?tan???5.59, is found. It depends on the mass of the Higgs boson and is independent of the Yukawa interactions. Also standard model (SM)-like scenarios with either h or H playing the role of the SM-like Higgs boson are analyzed.

?wie?ewska, Bogumi?a

2013-09-01

219

Interplay of universality classes in a three-dimensional Yukawa model  

SciTech Connect

We investigate numerically on the lattice the interplay of universality classes of the three-dimensional Yukawa model with U(1) chiral symmetry, using the Binder method of finite size scaling. At zero Yukawa coupling the scaling related to the magnetic Wilson-Fisher fixed point is confirmed. At sufficiently strong Yukawa coupling the dominance of the chiral fixed point associated with the 3D Gross-Neveu model is observed for various values of the coupling parameters, including infinite scalar self-coupling. In both cases the Binder method works consistently in a broad range of lattice sizes. However, when the Yukawa coupling is decreased the finite size behavior gets complicated and the Binder method gives inconsistent results for different lattice sizes. This signals a crossover between the universality classes of the two fixed points. {copyright} {ital 1996 The American Physical Society.}

Focht, E.; Jersak, J.; Paul, J. [Institute of Theoretical Physics E, RWTH Aachen, D-52056 Aachen (Germany)]|[HLRZ c/o KFA Juelich, D-52425 Juelich (Germany)

1996-04-01

220

Coulomb Excitation of 231Pa  

Microsoft Academic Search

The nucleus 231Pa was studied by Coulomb-excitation. New states were identified by particle-gamma gamma coincidences using the NORDBALL array in coincidence with two different particle detector systems. A regular band-structure is observed in the 3\\/2[651] band for levels above 9\\/2+ fed by strong E1 transitions from the ground-state band.

M. Wuerkner; J. de Boer; J. Choinski; T. Czosnyka; C. Guenther; J. Iwanicki; M. Kisielinski; A. Kordyasz; M. Kowalczyk; H. Kusakari; J. Kvasil; A. I. Levon; M. Loewe; P. J. Napiorkowski; T. Shizuma; G. Sletten; J. Srebrny; M. Sugawara; T. Weber; Y. Yoshizawa

1999-01-01

221

Coulomb Blockade in Graphene Nanoribbons  

Microsoft Academic Search

We propose that recent transport experiments revealing the existence of an energy gap in graphene nanoribbons may be understood in terms of Coulomb blockade. Electron interactions play a decisive role at the quantum dots which form due to the presence of necks arising from the roughness of the graphene edge. With the average transmission as the only fitting parameter, our

F. Sols; F. Guinea; A. H. Castro Neto

2007-01-01

222

Coulomb confinement from the Yang-Mills vacuum state in 2+1 dimensions  

SciTech Connect

The Coulomb-gauge ghost propagator and the color-Coulomb potential are computed in an ensemble of configurations derived from our recently proposed Yang-Mills vacuum wave functional in 2+1 dimensions. The results are compared to the corresponding values obtained by standard Monte Carlo simulations in three Euclidean dimensions. The agreement is quite striking for the Coulomb-gauge ghost propagator. The color-Coulomb potential rises linearly at large distances, but its determination suffers from rather large statistical fluctuations, due to configurations with very low values of {mu}{sub 0}, the lowest eigenvalue of the Coulomb-gauge Faddeev-Popov operator. However, if one imposes cuts on the data, effectively leaving out configurations with very low {mu}{sub 0}, the agreement of the potential in both sets of configurations is again satisfactory, although the error bars grow systematically as the cutoff is eliminated.

Greensite, Jeff [Physics and Astronomy Department, San Francisco State University, San Francisco, California 94132 (United States); Olejnik, Stefan [Institute of Physics, Slovak Academy of Sciences, SK-845 11 Bratislava (Slovakia)

2010-04-01

223

3D dust clouds (Yukawa Balls) in strongly coupled dusty plasmas  

SciTech Connect

Three-dimensional finite systems of charged dust particles confined to concentric spherical shells in a dusty plasma, so-called 'Yukawa balls', have been studied with respect to their static and dynamic properties. Here, we review the charging of particles in a dusty plasma discharge by computer simulations and the respective particle arrangements. The normal mode spectrum of Yukawa balls is measured from the 3D thermal Brownian motion of the dust particles around their equilibrium positions.

Melzer, A.; Passvogel, M.; Miksch, T.; Ikkurthi, V. R.; Schneider, R. [Institute of Physics, Ernst-Moritz-Arndt-University Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald (Germany); Block, D.; Piel, A. [IEAP, Christian-Albrechts-University Kiel, Olshausenstr. 40-60, 24098 Kiel (Germany)

2010-06-16

224

Yukawa structure from U(1) fluxes in F-theory Grand unification  

Microsoft Academic Search

In F-theory GUT constructions Yukawa couplings necessarily take place at the intersection of three matter curves. For generic geometric configurations this gives rise to problematic Yukawa couplings unable to reproduce the observed hierarchies. We point out that if the U(1)B-L\\/U(1)Y flux breaking the SO(10)\\/SU(5) GUT symmetry is allowed to go through pairs of matter curves with the same GUT representation,

L. E. Ibáñez

2009-01-01

225

Yukawa Couplings in F-theory and Non-Commutative Geometry  

Microsoft Academic Search

We consider Yukawa couplings generated by a configuration of intersecting seven-branes in F-theory. In configurations with a single interaction point and no fluxes turned on, the Yukawa matrices have rank one. This is no longer true when the three-form H-flux is turned on, which is generically the case for F-theory compactifications on Calabi-Yau fourfolds. In the presence of H-fluxes, the

Sergio Cecotti; Miranda C. N. Cheng; Jonathan J. Heckman; Cumrun Vafa

2009-01-01

226

Short-time dynamics of correlated quantum Coulomb systems  

NASA Astrophysics Data System (ADS)

Strong correlations in dense Coulomb systems are attracting increasing interest in many fields ranging from dense astrophysical plasmas, dusty plasmas and semiconductors to metal clusters and ultracold trapped ions [1]. Examples are bound states in dense plasmas (atoms, molecules, clusters) and semiconductors (excitons, trions, biexcitons) and many-particle correlations such as Coulomb and Yukawa liquids and crystals. Of particular current interest is the response of these systems to short excitations generated e.g. by femtosecond laser pulses and giving rise to ultrafast relaxation processes and build up of binary correlations. The proper theoretical tool are non-Markovian quantum kinetic equations [1,2] which can be derived from Nonequilibrium Green's Functions (NEGF) and are now successfully solved numerically for dense plasmas and semiconductors [3], correlated electrons [4] and other many-body systems with moderate correlations [5]. This method is well suited to compute the nonlinear response to strong fields selfconsistently including many-body effects [6]. Finally, we discuss recent extensions of the NEGF-computations to the dynamics of strongly correlated Coulomb systems, such as single atoms and molecules [7] and electron and exciton Wigner crystals in quantum dots [8,9]. [1] H. Haug and A.-P. Jauho, Quantum Kinetics in Transport and Optics of Semiconductors, Springer 1996; M. Bonitz Quantum Kinetic Theory, Teubner, Stuttgart/Leipzig 1998; [2] Progress in Nonequilibrium Green's Functions III, M. Bonitz and A. Filinov (Eds.), J. Phys. Conf. Ser. vol. 35 (2006); [3] M. Bonitz et al. Journal of Physics: Condensed Matter 8, 6057 (1996); R. Binder, H.S. K"ohler, and M. Bonitz, Phys. Rev. B 55, 5110 (1997); [4] N.H. Kwong, and M. Bonitz, Phys. Rev. Lett. 84, 1768 (2000); [5] Introduction to Computational Methods for Many-Body Systems, M. Bonitz and D. Semkat (eds.), Rinton Press, Princeton (2006); [6] H. Haberland, M. Bonitz, and D. Kremp, Phys. Rev. E 64, 026405 (2001); [7] N.E. Dahlen, A. Stan and R. van Leeuwen, p. 324 in Ref. 2.; [8] A. Filinov, M. Bonitz, and Yu. Lozovik, Phys. Rev. Lett. 86, 3851 (2001); [9] K. Balzer, N.E. Dahlen, R. van Leeuwen, and M. Bonitz, to be published

Bonitz, Michael

2007-03-01

227

Nonasymptotic analysis of relativistic electron scattering in the Coulomb field  

SciTech Connect

It is shown that the conventional Born series for relativistic electron scattering in the Coulomb field cannot be used for calculating the scattering characteristics. The differential cross section at small scattering angles is found on the basis of the Furry-Sommerfeld-Maue solution of the Dirac equation. Propagation of the electron wave packet is considered in order to separate the incident and scattered fluxes. It is shown that the total scattering cross section proves to be finite but depends on the distance r between the scattering center and the observation point. It is also shown that the polarization characteristics of the scattered beam are changed due to the long-range character of the Coulomb potential. The results can be important because Coulomb scattering is often used for normalization of experimental data in high-energy physics.

Feranchuk, I. D.; Skoromnik, O. D. [Belarusian State University, 4 Nezavisimosty Avenue, BY-220030 Minsk (Belarus)

2010-11-15

228

Laser Coulomb-explosion imaging of small molecules  

SciTech Connect

We use intense few-cycle laser pulses to ionize molecules to the point of Coulomb explosion. We use Coulomb's law or ab initio potentials to reconstruct the molecular structure of D{sub 2}O and SO{sub 2} from the correlated momenta of exploded fragments. For D{sub 2}O, a light and fast system, we observed about 0.3 A and 15 deg. deviation from the known bond length and bond angle. By simulating the Coulomb explosion for equilibrium geometry, we showed that this deviation is mainly caused by ion motion during ionization. Measuring three-dimensional structure with half bond length resolution is sufficient to observe large-scale rearrangements of small molecules such as isomerization processes.

Legare, F. [National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada); Departement de Chimie, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Lee, Kevin F.; Dooley, P.W. [National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada); Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada); Litvinyuk, I.V. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Wesolowski, S.S.; Bunker, P.R.; Villeneuve, D.M.; Corkum, P.B. [National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 (Canada); Dombi, P.; Krausz, F. [Technische Universitaet Wien, Vienna (Austria); Bandrauk, A.D. [Departement de Chimie, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)

2005-01-01

229

Coulomb screening in low-energy nuclear reactions.  

National Technical Information Service (NTIS)

Coulomb screening effects are studied in very low-energy nuclear reactions. The two-potential formalism is shown to be a convenient method for the separation of long-range (molecular) and short-range (nuclear) dynamics. As specific applications, electron ...

G. Bencze C. Chandler

1991-01-01

230

Coulomb law in the pure gauge U(1) theory on a lattice  

SciTech Connect

We study the heavy charge potential in the Coulomb phase of pure gauge compact U(1) theory on the lattice. We calculate the static potential V{sub W}(T,{rvec R}) from Wilson loops on a 16{sup 3}{times}32 lattice and compare with the predictions of lattice perturbation theory. We investigate finite size effects and, in particular, the importance of non-Coulomb contributions to the potential. We also comment on the existence of a maximal coupling in the Coulomb phase of pure gauge U(1) theory. {copyright} {ital 1997} {ital The American Physical Society}

Cella, G.; Vicere, A. [INFN in Pisa and Dipartimento di Fisica dell`Universita di Pisa (Italy); Heller, U.M. [SCRI, Florida State University, Tallahassee, Florida 32306-4130 (United States); Mitrjushkin, V.K. [Humboldt-Universitaet zu Berlin, Institut fuer Physik, 10115 Berlin (Germany)

1997-10-01

231

Small Yukawa couplings from type-I string theory and the inflationary solution to the strong CP and mu problems  

Microsoft Academic Search

We investigate the origin of phenomenologically interesting small Yukawa couplings in type-I string theory. Utilising the framework of intersecting sets of D9 and orthogonal D5 branes we demonstrate the connection between extra dimensional volumes and Yukawa couplings. For example, we show that extra dimensions with inverse lengths of 108 GeV can lead to 10-10 Yukawa couplings. String selection rules, arising

Oliver J. Eyton-Williams; Steve F. King

2005-01-01

232

Coulomb interactions in charged fluids  

NASA Astrophysics Data System (ADS)

The use of Ewald summation schemes for calculating long-range Coulomb interactions, originally applied to ionic crystalline solids, is a very common practice in molecular simulations of charged fluids at present. Such a choice imposes an artificial periodicity which is generally absent in the liquid state. In this paper we propose a simple analytical O(N2) method which is based on Gauss’s law for computing exactly the Coulomb interaction between charged particles in a simulation box, when it is averaged over all possible orientations of a surrounding infinite lattice. This method mitigates the periodicity typical of crystalline systems and it is suitable for numerical studies of ionic liquids, charged molecular fluids, and colloidal systems with Monte Carlo and molecular dynamics simulations.

Vernizzi, Graziano; Guerrero-García, Guillermo Iván; Olvera de La Cruz, Monica

2011-07-01

233

Coulomb Energy of Single-Proton Halo Systems  

NASA Astrophysics Data System (ADS)

Halo nuclei have unusually large spatial extension because one or more nucleons are weakly bound to a ``core.'' For a single-neutron halo, the behavior of the radial wave function, as well as its dependence on binding energy and angular momentum can be calculated using a square-well as a model for the nuclear potential [1]. This model facilitates predictions for experimental measurements of the radii, photodisintegration cross sections, etc of these halo systems. A similar square-well model can be employed for nuclei which have a single-proton halo, such as ^17F [2]. We have used such a model to compute the Coulomb energies of halo systems. We have done this both to all orders in the Coulomb potential, and in Born approximation. The dependence of the Coulomb energy on the ``halo parameter,'' i.e. the ratio of the range of the nuclear potential to the size of the system, has been examined. This allows us to determine the range of this parameter where the Born approximation is an accurate way to compute the Coulomb energy in halo nuclei.

Acharya, Bijaya; Phillips, Daniel

2010-10-01

234

Ordering in classical Coulombic systems.  

SciTech Connect

The author discusses the properties of classical Coulombic matter at low temperatures. It has been well known for some time [1,2] that infinite Coulombic matter will crystallize in body-centered cubic form when the quantity {Lambda} (the dimensionless ratio of the average two-particle Coulomb energy to the kinetic energy per particle) is larger than {approximately}175. But the systems of such particles that have been produced in the laboratory in ion traps, or ion beams, are finite with surfaces defined by the boundary conditions that have to be satisfied. This results in ion clouds with sharply defined curved surfaces, and interior structures that show up as a set of concentric layers that are parallel to the outer surface. The ordering does not appear to be cubic, but the charges on each shell exhibit a ''hexatic'' pattern of equilateral triangles that is the characteristic of liquid crystals. The curvature of the surfaces prevents the structures on successive shells from interlocking in any simple fashion. This class of structures was first found in simulations [3] and later in experiments [4].

Schiffer, J. P.

1998-01-22

235

LHC phenomenology of SO(10) models with Yukawa unification  

NASA Astrophysics Data System (ADS)

In this paper we study an SO(10) SUSY GUT with Yukawa unification for the third generation. We perform a global ?2 analysis given to obtain the GUT boundary conditions consistent with 11 low-energy observables, including the top, bottom and tau masses. We assume a universal mass, m16, for squarks and sleptons and a universal gaugino mass, M1/2. We then analyze the phenomenological consequences for the LHC for 15 benchmark models with fixed m16=20TeV and with varying values of the gluino mass. The goal of the present work is to (i) evaluate the lower bound on the gluino mass in our model coming from the most recent published data of CMS and (ii) to compare this bound with similar bounds obtained by CMS using simplified models. The bottom line is that the bounds coming from the same-sign dilepton analysis are comparable for our model and the simplified model studied assuming B(g˜?tt¯?˜10)=100%. However the bounds coming from the purely hadronic analyses for our model are 10%-20% lower than obtained for the simplified models. This is due to the fact that for our models the branching ratio for the decay g˜?g?˜1,20 is significant. Thus there are significantly fewer b-jets. We find a lower bound on the gluino mass in our models with Mg˜?1000GeV. Finally, there is a theoretical upper bound on the gluino mass which increases with the value of m16. For m16?30TeV, the gluino mass satisfies Mg˜?2.8TeV at 90% C.L. Thus, unless we further increase the amount of fine-tuning, we expect gluinos to be discovered at LHC 14.

Anandakrishnan, Archana; Bryant, B. Charles; Raby, Stuart; Wingerter, Ak?n

2013-10-01

236

Non-perturbative effects and Yukawa hierarchies in F-theory SU(5) unification  

NASA Astrophysics Data System (ADS)

Local SU(5) F-theory models lead naturally to Yukawa couplings for the third generation of quarks and leptons, but inducing Yukawas for the lighter generations has proven elusive. Corrections coming from gauge fluxes fail to generate the required couplings, and naively the same applies to instanton effects. We nevertheless revisit the effect of instantons in F-theory GUT constructions and find that contributions previously ignored in the literature induce the leading non-perturbative corrections to the Yukawa couplings. We apply our results to the case of 10× overline{5}× overline{5} couplings in local SU(5) F-theory GUTs, showing that non-perturbative effects naturally lead to hierarchical Yukawas. The hypercharge flux required to break SU(5) down to the SM does not affect the holomorphic Yukawas but does modify the profile of the wavefunctions, explaining the difference between the D-quark and lepton couplings at the unification scale. The combination of non-perturbative corrections and magnetic fluxes allows to describe the measured lepton and D-quark masses of second and third generations in the SM.

Font, A.; Ibáñez, L. E.; Marchesano, F.; Regalado, D.

2013-03-01

237

Multiple Coulomb excitation experiment of 68Zn  

NASA Astrophysics Data System (ADS)

Coulomb excitation experiment was carried out with a 68Zn beam bombarding a natPb target. Two E2 matrix elements and the quadrupole moment of the 21+ state were newly derived with the least-squares search code GOSIA. The potential energy surface (PES) was calculated with the Nilsson-Strutinsky model, showing two shallow minima: the first minimum does not contain the 1g9/2 orbit below the Fermi surface, while the second minimum does. The ground state band and the intruder band seem to be constructed on the first and the second minimum, respectively. As for the ground state band, the asymmetric rotor model and the IBM in O(6) limit reproduced the experimental values rather well. The shallow PES may suggest instability of the shape. The ground state band structure may be explained assuming a soft triaxial deformation.

Koizumi, M.; Seki, A.; Toh, Y.; Osa, A.; Utsuno, Y.; Kimura, A.; Oshima, M.; Hayakawa, T.; Hatsukawa, Y.; Katakura, J.; Matsuda, M.; Shizuma, T.; Czosnyka, T.; Sugawara, M.; Morikawa, T.; Kusakari, H.

2004-01-01

238

Multicritical behavior of Z2×O(2) Gross-Neveu-Yukawa theory in graphene  

NASA Astrophysics Data System (ADS)

Multicritical behavior of interacting fermions in graphene's honeycomb lattice is presented. In particular, we considered the spin triplet insulating orders, where the spin rotational symmetry of the order parameter is explicitly broken. By casting the problem in terms of Gross-Neveu-Yukawa theory, we show that such symmetry-breaking terms are irrelevant near the metal-insulator critical point. A finite Yukawa coupling among bosons and fermions improves the stability of such critical point against the symmetry-breaking perturbations. Physical sources of such symmetry-breaking terms are pointed out. Critical exponents are calculated near the transitions as well.

Roy, Bitan

2011-09-01

239

Nonlinear instability of the one-dimensional Vlasov-Yukawa system  

SciTech Connect

We discuss the nonlinear instability of some class of stationary solutions to the one-dimensional Vlasov-Yukawa system with a mass parameter m. The Vlasov-Yukawa system corresponds to the short-range correction of the repulsive Vlasov-Poisson system arising from plasma physics. We show that the stationary solutions satisfying the Penrose condition are nonlinearly unstable in small mass regime. In a large mass regime, the massiveness of force carrier particles acts as stabilizer in a finite time interval. We present several numerical results to confirm our analytical results.

Ha, Seung-Yeal; Lee, Ho [Department of Mathematical Sciences, Seoul National University, Seoul 151-747 (Korea, Republic of); Ha, Taeyoung [Division of Computational Sciences in Mathematics, National Institute for Mathematical Sciences, Daejon 305-390 (Korea, Republic of); Hwang, Chi-Ok [School of General Studies, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

2011-03-15

240

Coulomb Excitation of exp 226 Ra.  

National Technical Information Service (NTIS)

The isotope exp 226 Ra was studied by multiple Coulomb excitation with a 135 MeV e.g. 150 MeV exp 32 S-beam and with a 243 MeV exp 58 Ni beam. Using particle gamma coincidences the gamma decay of the levels populated at the Coulomb excitation can be obser...

R. Zimmermann

1980-01-01

241

Coulomb field of an accelerated charge: Physical and mathematical aspects  

NASA Astrophysics Data System (ADS)

The Coulomb field of a charge static in an accelerated frame has properties that suggest features of electromagnetism which are different from those in an inertial frame. An illustrative calculation shows that the Larmor radiation reaction equals the electrostatic attraction between the accelerated charge and the charge induced on the surface whose history is the event horizon. A spectral decomposition of the Coulomb potential in the accelerated frame suggests the possibility that the distortive effects of this charge on the Rindler vacuum are akin to those of a charge on a crystal lattice. The necessary Maxwell field equations relative to the accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge-invariant potentials.

Alexander, Francis J.; Gerlach, Ulrich H.

1991-12-01

242

Properties of color-Coulomb string tension  

SciTech Connect

We study the properties of the color-Coulomb string tension obtained from the instantaneous part of gluon propagators in Coulomb gauge using quenched SU(3) lattice simulation. In the confinement phase, the dependence of the color-Coulomb string tension on the QCD coupling constant is smaller than that of the Wilson loop string tension. On the other hand, in the deconfinement phase, the color-Coulomb string tension does not vanish even for T/T{sub c}=1{approx}5, the temperature dependence of which is comparable with the magnetic scaling, dominating the high temperature QCD. Thus, the color-Coulomb string tension is not an order parameter of quark-gluon plasma phase transition.

Nakagawa, Y.; Saito, T.; Toki, H. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Nakamura, A. [Research Institute for Information Science and Education, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Zwanziger, D. [Physics Department, New York University, New York, New York 10003 (United States)

2006-05-01

243

Addendum to Effects of transverse photon exchange in helium Rydberg states: Corrections beyond the Coulomb-Breit interactions''  

SciTech Connect

We present numerical results for the correction potential beyond the Coulomb-Breit and the Araki-Sucher interaction potentials due to transverse photon exchange between the Rydberg electron and the core in helium Rydberg atoms.

Au, C.K.; Mesa, M.A. (Department of Physics, University of South Carolina, Columbia, South Carolina 29208 (USA) Department of Astronomy, University of South Carolina, Columbia, South Carolina 29208 (USA))

1990-03-01

244

Giant fluctuations of Coulomb drag  

NASA Astrophysics Data System (ADS)

We have observed reproducible fluctuations of the Coulomb drag resistivity, originating from coherent scattering of electrons in two layers. The fluctuations are observed as functions of both the carrier density of each layer, and perpendicular magnetic field. The magnitude of the fluctuations is much larger than expected from the theory of ‘diffusive’ drag and the temperature dependence is stronger than theoretically predicted. We account for this enhancement by considering the ‘ballistic’ nature of the drag in our system. We also present results on the fluctuations at large magnetic fields, where the lowest Landau level is half filled so that coherent drag occurs between composite fermions. The magnitude of fluctuations is seen to be greatly enhanced compared with the small field case, although fluctuations of composite fermion drag show much better agreement with the theory developed for the ‘diffusive’ drag regime.

Price, A. S.; Savchenko, A. K.; Allison, G.; Ritchie, D. A.

2008-03-01

245

Coulomb excitation of 31Mg  

NASA Astrophysics Data System (ADS)

The ground state properties of 31Mg indicate a change of nuclear shape at N=19 with a deformed J?=1/2+ intruder state as a ground state, implying that 31Mg is part of the "island of inversion". The collective properties of excited states were the subject of a Coulomb excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam. De-excitation ?-rays were detected by the MINIBALL ?-spectrometer in coincidence with scattered particles in a segmented Si-detector. The level scheme of 31Mg was extended. Spin and parity assignment of the 945 keV state yielded 5/2+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration.

Seidlitz, M.; Mücher, D.; Reiter, P.; Bildstein, V.; Blazhev, A.; Bree, N.; Bruyneel, B.; Cederkäll, J.; Clement, E.; Davinson, T.; van Duppen, P.; Ekström, A.; Finke, F.; Fraile, L. M.; Geibel, K.; Gernhäuser, R.; Hess, H.; Holler, A.; Huyse, M.; Ivanov, O.; Jolie, J.; Kalkühler, M.; Kotthaus, T.; Krücken, R.; Lutter, R.; Piselli, E.; Scheit, H.; Stefanescu, I.; van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wiens, A.

2011-06-01

246

Complete and incomplete Coulomb blockade  

NASA Astrophysics Data System (ADS)

In 1995 K. A. Matveev [Phys. Rev. B 51, 1743 (1995)] introduced a one-dimensional model to describe the physics of the Coulomb blockade in a quantum dot connected to a bulk lead by a single-mode quantum point contact. We study the equilibrium properties of this model, and show that the parameter space of the system consists of two regions. In one of them the average dot charge is a nonanalytical function of the gate voltage (complete blockade), and there are first-order phase transitions corresponding to the discontinuous change of the dot charge. These first-order transitions end at critical points belonging to the universality class of the classical one-dimensional Ising model with interactions decaying as inverse square of distance. Beyond these critical points the dot charge is a continuous function of the gate voltage (incomplete blockade). Similar conclusions hold for other equilibrium properties of the system.

Kolomeisky, Eugene

2001-11-01

247

Coulomb screening in low-energy nuclear reactions  

Microsoft Academic Search

Coulomb screening effects are studied in very-low-energy nuclear reactions. The two-potential formalism is shown to be a convenient method for the separation of long-range (molecular) and short-range (nuclear) dynamics. As specific applications, electron screening effects and muon catalysis in nuclear reactions are investigated. In the case of electron screening in very-low-energy nuclear reactions a method is elaborated for calculation of

Gy. Bencze; C. Chandler

1992-01-01

248

Approximate Treatment of 3-Body Coulomb Systems: Discrete Spectrum  

NASA Astrophysics Data System (ADS)

We present a method for treatment of three charged particles. The proposed method has universal character and is applicable both for bound and continuum states. A finite-rank approximation is used for Coulomb potential in the Lippman-Schwinger equation, that results in a system of one-dimensional coupled integral equations. Preliminary numerical results for three-body atomic and molecular systems like H -, He, pp? and other are presented.

Belyaev, V. B.; Naumkin, A. A.

2011-05-01

249

Coulomb Excitation of Stable Even-Even zn Isotopes  

Microsoft Academic Search

Multiple Coulomb excitation of 66,68Zn was carried out. The experimental data were analyzed with the least-squares search code GOSIA. E2 matrix elements and quadrupole moments of 21^ + states were obtained. The ground band structures are explained to some extent with the asymmetric rotor model (ARM) and the interacting boson model (IBM) in O(6) limit. Potential energy surfaces (PES) calculated

M. Koizumi; A. Seki; Y. Toh; M. Oshima; A. Osa; Y. Utuno; A. Kimura; Y. Hatsukawa; T. Hayakawa; T. Shizuma; J. Katakura; M. Matsuda; M. Sugawara; T. Morikawa; H. Kusakari; T. Czosnyka

2004-01-01

250

Probing Minicharged Particles with Tests of Coulomb's Law  

SciTech Connect

Minicharged particles arise in many extensions of the standard model. Their contribution to the vacuum polarization modifies Coulomb's law via the Uehling potential. In this Letter, we argue that tests for electromagnetic fifth forces can therefore be a sensitive probe of minicharged particles. In the low mass range < or approx. mueV existing constraints from Cavendish type experiments provide the best model-independent bounds on minicharged particles.

Jaeckel, Joerg [Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE (United Kingdom)

2009-08-21

251

SU(5) and SO(10) models from F-theory with natural Yukawa couplings  

NASA Astrophysics Data System (ADS)

We construct the SU(5) and SO(10) models from F-theory. Turning on the U(1) fluxes, we can break the SU(5) gauge symmetry down to the standard model (SM) gauge symmetry, and break the SO(10) gauge symmetry down to the SU(3)C×SU(2)L×SU(2)R×U(1)B-L gauge symmetry. In particular, all the SM fermion Yukawa couplings preserve the enhanced U(1)a×U(1)b gauge or global symmetries at the triple intersections of the SM fermion and Higgs curves. And the SM fermion masses and mixings can be generated in the presence of background fluxes. In our models, the doublet-triplet splitting problem can be solved naturally. The additional vectorlike particles can obtain heavy masses via the instanton effects or Higgs mechanism and then decouple at the high scale. The SM gauge couplings at the string scale, which are split due to the U(1) flux effects, can be explained by considering heavy threshold corrections from the extra vectorlike particles. Moreover, in the SU(5) model, we have the Yukawa coupling unification for the bottom quark and tau lepton. In the SO(10) models, we have the Yukawa coupling unification for the top and bottom quarks, and the Yukawa coupling unification for the tau lepton and tau neutrino.

Li, Tianjun

2010-03-01

252

Entanglement in S states of two-electron quantum dots with Coulomb impurities at the center  

NASA Astrophysics Data System (ADS)

We study a system of two Coulombically interacting electrons in an external harmonic potential in the presence of an on-centre Coulomb impurity. Detailed results for the dependencies of the reduced von Neumann entropy on the control parameters of the system are provided for both the ground state and the triplet S states with the lowest energy. Among other features, it is found that in the weak confinement regime the entanglement is strongly affected by the presence of an acceptor impurity.

Ko?cik, Przemys?aw

2013-11-01

253

Extended Kepler-Coulomb quantum superintegrable systems in three dimensions  

NASA Astrophysics Data System (ADS)

The quantum Kepler-Coulomb system in three dimensions is well known to be second order superintegrable, with a symmetry algebra that closes polynomially under commutators. This polynomial closure is also typical for second order superintegrable systems in 2D and for second order systems in 3D with nondegenerate (four-parameter) potentials. However, the degenerate three-parameter potential for the 3D Kepler-Coulomb system (also second order superintegrable) is an exception, as its symmetry algebra does not close polynomially. The 3D four-parameter potential for the extended Kepler-Coulomb system is not even second order superintegrable, but Verrier and Evans (2008 J. Math. Phys. 49 022902) showed it was fourth order superintegrable, and Tanoudis and Daskaloyannis (2011 arXiv:11020397v1) showed that, if a second fourth order symmetry is added to the generators, the symmetry algebra closes polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider an infinite class of quantum extended Kepler-Coulomb three- and four-parameter systems indexed by a pair of rational numbers (k1, k2) and reducing to the usual systems when k1 = k2 = 1. We show these systems to be superintegrable of arbitrarily high order and determine the structure of their symmetry algebras. We demonstrate that the symmetry algebras close algebraically; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering operators, not themselves symmetry operators or even defined independent of basis, that can be employed to construct the symmetry operators and their structure relations.

Kalnins, E. G.; Kress, J. M.; Miller, W., Jr.

2013-03-01

254

Dynamics of topological defects in ion Coulomb crystals  

NASA Astrophysics Data System (ADS)

We study experimentally and theoretically the properties of structural defects (kink solitons) in two-dimensional ion Coulomb crystals. We show how different types of kink solitons with different physical properties can be realized, and transformed from one type into another by varying the aspect ratio of the trap confinement. Further, we discuss how impurities in ion Coulomb crystals, such as mass defects, can modify the dynamics of kink creation and their stability. For both pure and impure crystals, the experimentally observed kink dynamics are analysed in detail and explained theoretically by numerical simulations and calculations of the Peierls–Nabarro potential. Finally, we demonstrate that static electric fields provide a handle to vary the influence of mass defects on kinks in a controlled way and allow for deterministic manipulation and creation of kinks.

Partner, H. L.; Nigmatullin, R.; Burgermeister, T.; Pyka, K.; Keller, J.; Retzker, A.; Plenio, M. B.; Mehlstäubler, T. E.

2013-10-01

255

Role of the Permanent Dipole Moment in Coulomb Explosion  

NASA Astrophysics Data System (ADS)

By numerically solving the non-Born—Oppenheimer time-dependent Schrödinger equation in a few-cycle chirped laser field (5-fs, 800-nm), the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the “virtual detector" method. The results indicate that with the effect of the permanent dipole moment, different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state (1s?g) to the first excited state (2p?u), and then move along the excited potential curve, and finally charge-resonant enhanced ionization occurs at critical internuclear distance. As a result, despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameter ?, the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.

Zhang, Cai-Ping; Miao, Xiang-Yang

2013-10-01

256

Direct evidence for a Coulombic phase in monopole-suppressed SU(2) lattice gauge theory  

NASA Astrophysics Data System (ADS)

Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)–Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near ?=3.2. The theory with both Z2 vortices and monopoles and SO(3)–Z2 monopoles eliminated is simulated in the strong-coupling (?=0) limit on lattices up to 604. Here, as in the high-? phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any ?. Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of ?˜1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data.

Grady, Michael

2013-11-01

257

Beyond the Rayleigh instability limit for multicharged finite systems: From fission to Coulomb explosion  

PubMed Central

We address the stability of multicharged finite systems driven by Coulomb forces beyond the Rayleigh instability limit. Our exploration of the nuclear dynamics of heavily charged Morse clusters enabled us to vary the range of the pair potential and of the fissibility parameter, which results in distinct fragmentation patterns and in the angular distributions of the fragments. The Rayleigh instability limit separates between nearly binary (or tertiary) spatially unisotropic fission and spatially isotropic Coulomb explosion into a large number of small, ionic fragments. Implications are addressed for a broad spectrum of dynamics in chemical physics, radiation physics of ultracold gases, and biophysics, involving the fission of clusters and droplets, the realization of Coulomb explosion of molecular clusters, the isotropic expansion of optical molasses, and the Coulomb instability of “isolated” proteins.

Last, Isidore; Levy, Yaakov; Jortner, Joshua

2002-01-01

258

Charge fluctuations in Coulomb systems  

NASA Astrophysics Data System (ADS)

It was shown by Martin and Yalcin that the mean-square fluctuation in the net electric charge Q? contained in a subregion ? of an infinitely extended equilibrium Coulomb system (plasma, electrolytes, etc.) grows only as the surface area S? (not the volume) of ? and that Q?S? has a Gaussian distribution as ?-->?. We extend these results to joint charge fluctuations in different spatial regions: Let space be divided into disjoint regions ?i, i=1,2,..., say, cubes of length L. We show that as L-->?, the covariance in Q?iL behaves as L-2=-16K if ?i and ?j are adjacent, and is zero if they do not have a common face. Furthermore, the variables Q?L approach, as L-->?, a jointly Gaussian distribution. These results can be proven rigorously whenever the correlations in the system decay faster than the fourth power of the distance, which is known to happen in many cases. This behavior of charge fluctuations is shown to be required for the consistency of the usual statistical-mechanical treatment of neutralmolecular systems.

Lebowitz, Joel L.

1983-03-01

259

Coulomb excitation of Ga73  

NASA Astrophysics Data System (ADS)

The B(E2;Ii?If) values for transitions in 3171Ga40 and 3173Ga42 were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of Ga71,73 at the REX-ISOLDE on-line isotope mass separator facility. The emitted ? rays were detected by the MINIBALL ?-detector array, and B(E2;Ii?If) values were obtained from the yields normalized to the known strength of the 2+?0+ transition in the Sn120 target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity toward lower excitation energy when adding neutrons beyond N=40. This supports conclusions from previous studies of the gallium isotopes, which indicated a structural change in this isotopic chain between N=40 and 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-,3/2- doublet near the ground state in 3173Ga42 differing by at most 0.8 keV in energy.

Diriken, J.; Stefanescu, I.; Balabanski, D.; Blasi, N.; Blazhev, A.; Bree, N.; Cederkäll, J.; Cocolios, T. E.; Davinson, T.; Eberth, J.; Ekström, A.; Fedorov, D. V.; Fedosseev, V. N.; Fraile, L. M.; Franchoo, S.; Georgiev, G.; Gladnishki, K.; Huyse, M.; Ivanov, O. V.; Ivanov, V. S.; Iwanicki, J.; Jolie, J.; Konstantinopoulos, T.; Kröll, Th.; Krücken, R.; Köster, U.; Lagoyannis, A.; Lo Bianco, G.; Maierbeck, P.; Marsh, B. A.; Napiorkowski, P.; Patronis, N.; Pauwels, D.; Reiter, P.; Seliverstov, M.; Sletten, G.; van de Walle, J.; van Duppen, P.; Voulot, D.; Walters, W. B.; Warr, N.; Wenander, F.; Wrzosek, K.

2010-12-01

260

New summation rules for coulomb wave functions  

PubMed

Sums of products of the Coulomb wave functions over degenerate manifolds have been obtained in a closed form. These sums appear in many atomic and molecular problems. The sums have been obtained making use of the properties of the Coulomb Green's function G(r, r('),E), in the limit E-->E(n), where E(n) is the eigenenergy of the hydrogenlike atomic ion. The closed Hostler-Pratt form of G in the coordinate representation has been used. The sums calculated are a consequence of the n degeneracy of the Coulomb atomic energy levels. This itself, as is well known, follows from the four-dimensional symmetry of the Coulomb problem for the hydrogen atom. PMID:11015936

Chibisov; Ermolaev; Brouillard; Cherkani

2000-01-17

261

Quarks in Coulomb gauge perturbation theory  

SciTech Connect

Coulomb gauge quantum chromodynamics within the first order functional formalism is considered. The quark contributions to the Dyson-Schwinger equations are derived and one-loop perturbative results for the two-point functions are presented.

Popovici, C.; Watson, P.; Reinhardt, H. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2009-02-15

262

On the modelling of Coulomb friction  

NASA Astrophysics Data System (ADS)

This paper analyses two different representations of Coulomb friction in the context of a dynamic simulation of the torsional vibrations of a driven drill-string. A simple model is used to compare the relative merits of a piecewise analytic approach using a discontinuous friction profile to a numerical integration using a smooth nonlinear representation of the Coulomb friction. In both cases the effects of viscous damping on the excitation of torsional relaxation oscillations are exhibited.

Cull, S. J.; Tucker, R. W.

1999-03-01

263

Solution of the associative mean spherical approximation for a multicomponent dimerizing hard-sphere multi-Yukawa fluid  

SciTech Connect

The analytical solution of the associative mean spherical approximation (AMSA) for a Yukawa dimerizing multicomponent hard-sphere fluid is derived. The general multi-Yukawa case is discussed. The simpler one-Yukawa case with factorizable coefficients is explicitly solved. As in the previously discussed electrolyte case the solution of the AMSA reduces to the solution of only one nonlinear algebraic equation for the scaling parameter {gamma}{sup B}. The analytical results for the AMSA closure is illustrated by numerical examples and computer simulation for the one-component one-Yukawa dimerizing fluid. Good agreement between theoretical and computer simulation results was found for both the thermodynamic properties and the structure of the system. (c) 2000 American Institute of Physics.

Kalyuzhnyi, Yu. V. [Institute for Condensed Matter Physics, Svientsitskoho 1, 290011 Lviv, (Ukraine); Blum, L. [Department of Physics, University of Puerto Rico, Rio Piedras, Puerto Rico 00931 (Puerto Rico); Rescic, J. [Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1001 Ljubljana, (Slovenia); Stell, G. [Department of Chemistry, State University of New York at Stony Brook, New York 11794-3400 (United States)

2000-07-15

264

Coulomb Excitation of Stable Even-Even zn Isotopes  

NASA Astrophysics Data System (ADS)

Multiple Coulomb excitation of 66,68Zn was carried out. The experimental data were analyzed with the least-squares search code GOSIA. E2 matrix elements and quadrupole moments of 21^ + states were obtained. The ground band structures are explained to some extent with the asymmetric rotor model (ARM) and the interacting boson model (IBM) in O(6) limit. Potential energy surfaces (PES) calculated with the Nilsson-Strutinsky model show ?-unstability for 66Zn and shallow two minima for 68Zn. According to the experimental results and induction from the theoretical calculations, it seems that 66,68Zn would be explained with such a model with soft triaxial potential.

Koizumi, M.; Seki, A.; Toh, Y.; Oshima, M.; Osa, A.; Utuno, Y.; Kimura, A.; Hatsukawa, Y.; Hayakawa, T.; Shizuma, T.; Katakura, J.; Matsuda, M.; Sugawara, M.; Morikawa, T.; Kusakari, H.; Czosnyka, T.

2004-10-01

265

Thermodynamic properties and static structure factor for a Yukawa fluid in the mean spherical approximation.  

PubMed

This work presents the full analytic expressions for the thermodynamic properties and the static structure factor for a hard sphere plus 1-Yukawa fluid within the mean spherical approximation. To obtain these properties of the fluid type Yukawa analytically it was necessary to solve an equation of fourth order for the scaling parameter on a large scale. The physical root of this equation was determined by imposing physical conditions. The results of this work are obtained from seminal papers of Blum and Høye. We show that is not necessary the use the series expansion to solve the equation for the scaling parameter. We applied our theoretical result to find the thermodynamic and the static structure factor for krypton. Our results are in good agreement with those obtained in an experimental form or by simulation using the Monte Carlo method. PMID:22179758

Montes-Perez, J; Cruz-Vera, A; Herrera, J N

2011-12-18

266

Raising the Higgs mass with Yukawa couplings for isotriplets in vectorlike extensions of minimal supersymmetry  

SciTech Connect

Extra vectorlike matter with both electroweak-singlet masses and large Yukawa couplings can significantly raise the lightest Higgs boson mass in supersymmetry through radiative corrections. I consider models of this type that involve a large Yukawa coupling between weak isotriplet and isodoublet chiral supermultiplets. The particle content can be completed to provide perturbative gauge coupling unification, in several different ways. The impact on precision electroweak observables is shown to be acceptably small, even if the new particles are as light as the current experimental bounds of order 100 GeV. I study the corrections to the lightest Higgs boson mass, and discuss the general features of the collider signatures for the new fermions in these models.

Martin, Stephen P. [Department of Physics, Northern Illinois University, DeKalb, Illinois 60115 (United States) and Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois 60510 (United States)

2010-09-01

267

Chiral symmetry at finite temperatures and densities in the Coulomb gauge  

SciTech Connect

The gap equation at finite temperatures and densities obtained from the Schwinger-Dyson equation in the ladder approximation to the QCD Hamiltonian in the Coulomb gauge is solved numerically for several potential models. Critical temperatures for chiral-symmetry restoration and critical lines in the T-..mu.. plane are obtained showing the conditions for symmetry restoration. The order parameter is evaluated for various potentials and the agreement with experiment is found to be within 15% for the case of a confining plus an attractive Coulomb potential when the string tension ..sqrt..sigma is taken to be 350 MeV.

Galina, V.; Viswanathan, K.S.

1988-09-15

268

Infrared asymptotic freedom for the pseudoscalar Yukawa model at the critical point  

NASA Astrophysics Data System (ADS)

We consider the pseudoscalar Yukawa model on a four dimensional Euclidean lattice. The fermions are integrated out giving an effective boson interaction. We show that for weak coupling this interaction is in the class covered by the Gawedzki-Kupiainen renormalization group analysis. It follows that one can adjust parameters so that the flow of the renormalization group is toward a free massless boson theory. This establishes the existence of the critical theory and controls its long distance behavior.

Dimock, J.

1987-09-01

269

Matter wave functions and Yukawa couplings in F-theory grand unification  

Microsoft Academic Search

We study the local structure of zero mode wave functions of chiral matter fields in F-theory unification. We solve the differential equations for the zero modes derived from local Higgsing in the 8-dimensional parent action of F-theory 7-branes. The solutions are found as expansions both in powers and derivatives of the magnetic fluxes. Yukawa couplings are given by an overlap

L. E. Ibáñez

2009-01-01

270

Higgs boson mass and sparticle spectroscopy in Yukawa unified SUSY SO(10)  

SciTech Connect

We employ third family Yukawa unification, predicted by simple supersymmetric SO(10) models, to estimate the lightest MSSM Higgs boson mass. For {mu} > 0 (or {mu} < 0) and m{sub t} = 173.1GeV, the Higgs mass is estimated to lie close to 123-124 GeV. The theoretical uncertainty in this estimate is {+-}3 GeV. We highlight some LHC testable benchmark points which also display the presence of neutralino-stau coannihilation channel.

Shafi, Qaisar [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

2012-07-27

271

Pair structure of the hard-sphere Yukawa fluid: an improved analytic method versus simulations, Rogers-Young scheme, and experiment.  

PubMed

We present a comprehensive study of the equilibrium pair structure in fluids of nonoverlapping spheres interacting by a repulsive Yukawa-like pair potential, with special focus on suspensions of charged colloidal particles. The accuracy of several integral equation schemes for the static structure factor, S(q), and radial distribution function, g(r), is investigated in comparison to computer simulation results and static light scattering data on charge-stabilized silica spheres. In particular, we show that an improved version of the so-called penetrating-background corrected rescaled mean spherical approximation (PB-RMSA) by Snook and Hayter [Langmuir 8, 2880 (1992)], referred to as the modified PB-RMSA (MPB-RMSA), gives pair structure functions which are in general in very good agreement with Monte Carlo simulations and results from the accurate but nonanalytical and therefore computationally more expensive Rogers-Young integral equation scheme. The MPB-RMSA preserves the analytic simplicity of the standard rescaled mean spherical (RMSA) solution. The combination of high accuracy and fast evaluation makes the MPB-RMSA ideally suited for extensive parameter scans and experimental data evaluation, and for providing the static input to dynamic theories. We discuss the results of extensive parameter scans probing the concentration scaling of the pair structure of strongly correlated Yukawa particles, and we determine the liquid-solid coexistence line using the Hansen-Verlet freezing rule. PMID:21280773

Heinen, Marco; Holmqvist, Peter; Banchio, Adolfo J; Nägele, Gerhard

2011-01-28

272

Effect of size polydispersity on the crystal-fluid and crystal-glass transition in hard-core repulsive Yukawa systems  

NASA Astrophysics Data System (ADS)

We investigated the effect of size polydispersity on the crystal-fluid transition in hard-core repulsive Yukawa systems by means of Monte Carlo simulations for several state points in the Yukawa parameter space. Size polydispersity was introduced in the system only with respect to the hard particle cores; particles with different diameters had the same surface potential ?0, but the charge per particle was not varied with packing fraction or distance. We observed a shift to higher packing fraction of the crystal-fluid transition of bulk crystals with a fixed log-normal size distribution upon increasing the polydispersity, which was more pronounced for weakly charged particles (?0 ~ 23 mV) compared to more highly charged particles (?0 ~ 46 mV), and also more pronounced for larger Debye screening length. At high polydispersities (>=0.13) parts of the more highly charged systems that were initially crystalline became amorphous. The amorphous parts had a higher polydispersity than the crystalline parts, indicating the presence of a terminal polydispersity beyond which the homogeneous crystal phase was no longer stable.

van der Linden, Marjolein N.; van Blaaderen, Alfons; Dijkstra, Marjolein

2013-03-01

273

Yukawa structure from U(1) fluxes in F-theory Grand unification  

NASA Astrophysics Data System (ADS)

In F-theory GUT constructions Yukawa couplings necessarily take place at the intersection of three matter curves. For generic geometric configurations this gives rise to problematic Yukawa couplings unable to reproduce the observed hierarchies. We point out that if the U(1)B-L/U(1)Y flux breaking the SO(10)/SU(5) GUT symmetry is allowed to go through pairs of matter curves with the same GUT representation, the quark/lepton content is redistributed in such a way that all quark and leptons are allowed to have hierarchical Yukawas. This reshuffling of fermions is quite unique and is particularly elegant for the case of three generations and SO(10). Specific local F-theory models with SO(10) or SU(5) living on a del Pezzo surface with appropriate bundles and just the massless content of the MSSM are described. We point out that the smallness of the 3rd generation quark mixing predicted by this scheme (together with gauge coupling unification) could constitute a first hint of an underlying F-theory grand unification.

Font, A.; Ibáñez, L. E.

2009-02-01

274

Non-invasive determination of the parameters of strongly coupled 2D Yukawa liquids  

SciTech Connect

We derive a method for identifying the Yukawa model parameters of two-dimensional (2D) strongly coupled dusty plasmas. The method is based on non-invasive observation of the dust component of the plasma and comparison with a large body of simulation data in the form of simple analytical formulas. This approach requires only input from a time-series of configuration snapshots and particle velocities with no recourse to additional information about the system. In addition, we derive an effective coupling parameter for 2D Yukawa systems based on the height of the first maximum of the pair distribution function. Two variants--one valid in the high-coupling range, the other for arbitrary couplings of the liquid--are derived. Comparison to previous approaches to Yukawa coupling parameters shows that the present concept is more general and more accurate. Our results should be directly applicable as a simple, yet reliable diagnostic method for a variety of experiments, including dusty plasmas, colloidal suspensions, and ions in traps, and can be employed to facilitate comparisons between experiments, theory, and simulations.

Ott, T.; Bonitz, M. [Christian-Albrechts-Universitaet zu Kiel, Institut fuer Theoretische Physik und Astrophysik, Leibnizstrasse 15, 24098 Kiel (Germany); Stanley, M. [Department of Physics, University of Cambridge, J. J. Thomson Avenue, CB3 0HE Cambridge (United Kingdom)

2011-06-15

275

Spin-1/2 Particle in Scalar-Vector-Pseudoscalar Spatially Dependent Mass Coulomb Fields: 1 + 1 Dimensions  

NASA Astrophysics Data System (ADS)

In this letter, we present exact solutions of the Dirac equation with the mixed scalar-vector-pseudoscalar spatially dependent mass Coulomb potential under spin and pseudospin (p-spin) symmetry limits in 1+1 dimensions.

Rajabi, A. A.; Hamzavi, M.

2013-11-01

276

On the importance of thermodynamic self-consistency for calculating clusterlike pair correlations in hard-core double Yukawa fluids  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features.

Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J.

2011-02-01

277

On the importance of thermodynamic self-consistency for calculating clusterlike pair correlations in hard-core double Yukawa fluids.  

PubMed

Understanding the mechanisms of clustering in colloids, nanoparticles, and proteins is of significant interest in material science and both chemical and pharmaceutical industries. Recently, using an integral equation theory formalism, Bomont et al. [J. Chem. Phys. 132, 184508 (2010)] studied theoretically the temperature dependence, at a fixed density, of the cluster formation in systems where particles interact with a hard-core double Yukawa potential composed of a short-range attraction and a long-range repulsion. In this paper, we provide evidence that the low-q peak in the static structure factor, frequently associated with the formation of clusters, is a common behavior in systems with competing interactions. In particular, we demonstrate that, based on a thermodynamic self-consistency criterion, accurate structural functions are obtained for different choices of closure relations. Moreover, we explore the dependence of the low-q peak on the particle number density, temperature, and potential parameters. Our findings indicate that enforcing thermodynamic self-consistency is the key factor to calculate both thermodynamic properties and static structure factors, including the low-q behavior, for colloidal dispersions with both attractive and repulsive interactions. Additionally, a simple analysis of the mean number of neighboring particles provides a qualitative description of some of the cluster features. PMID:21322731

Kim, Jung Min; Castañeda-Priego, Ramón; Liu, Yun; Wagner, Norman J

2011-02-14

278

Scattering theory for arbitrary potentials  

SciTech Connect

The fundamental quantities of potential scattering theory are generalized to accommodate long-range interactions. Definitions for the scattering amplitude and wave operators valid for arbitrary interactions including potentials with a Coulomb tail are presented. It is shown that for the Coulomb potential the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure.

Kadyrov, A.S.; Bray, I.; Stelbovics, A.T. [Centre for Atomic, Molecular and Surface Physics, Division of Science and Engineering, Murdoch University, Perth 6150 (Australia); Mukhamedzhanov, A.M. [Cyclotron Institute, Texas A and M University, College Station, Texas 77843 (United States)

2005-09-15

279

Studies in statistical mechanics of Coulombic systems. IV. The screened-Coulomb charged hard sphere system and its relation to the restricted primitive model  

NASA Astrophysics Data System (ADS)

Monte Carlo results are reported for three liquid states of a model consisting of two species (anions and cations) of charged hard spheres of equal diameter, which interact with a screened Coulomb potential. Results of the mean spherical approximation, the truncated ?2 approximation, and the EXP approximation are compared with the MC results. Numerical and theoretical relationships between this model and the restricted primitive model (RPM) are established. The effect of the methodological errors involved in MC simulations of the RPM is studied by comparing the MC radial distribution functions (rdf's) for the RPM with the rdf's obtained from a perturbation theory, using the screened Coulomb system as the reference system.

Larsen, B.; Rogde, S. A.

1980-02-01

280

A Practical Method of Solving Cutoff Coulomb Problems in Momentum Space --- Application to the Lippmann-Schwinger Resonating-Group Method and the pd Elastic Scattering ---  

NASA Astrophysics Data System (ADS)

A practical method of solving cutoff Coulomb problems of two-cluster systems in momentum space is given. When a sharply cut-off Coulomb force with a cutoff radius ? is introduced at the level of constituent particles, the two-cluster direct potential of the Coulomb force becomes in general a local screened Coulomb potential. The asymptotic Hamiltonian yields two types of asymptotic waves; one is an approximate Coulomb wave with ? in the middle-range region, and the other a free (no-Coulomb) wave in the longest-range region. The constant Wronskians of this Hamiltonian can be calculated in either region. We can evaluate the Coulomb-modified nuclear phase shifts for the screened Coulomb problem using the matching condition proposed by Vincent and Phatak for the sharply cut-off Coulomb problem. We apply this method first to an exactly solvable model of the ? ? scattering with the Ali-Bodmer potential and confirm that a complete solution is obtained with a finite ?. The stability of nuclear phase shifts with respect to the change in ? within some appropriate range is demonstrated in the ? ? resonating-group method (RGM) calculation using the Minnesota three-range force. An application to the pd elastic scattering is also discussed.

Fujiwara, Y.; Fukukawa, K.

2012-08-01

281

Coulomb-corrected Volkov-type solution for an electron in an intense circularly polarized laser field  

NASA Astrophysics Data System (ADS)

A simple analytical approximation exists for the wavefunction of an unbound electron interacting both with a strong circularly polarized laser field and an atomic Coulomb potential (Reiss and Krainov 1994 Phys. Rev. A 50 R910). This wavefunction is the Volkov state with a first-order Coulomb correction coming from some perturbative expansion of the potential in the Kramers-Henneberger reference frame. The expansion is valid, if the distance from the centre of the Coulomb force is smaller than the classical radius of motion of a free electron in a plane-wave field. We improve the approximate Coulomb-Volkov wavefunction by including the next term in the perturbative expansion of the atomic potential.

Bauer, Jaroslaw

2001-04-01

282

Coulombic effect and renormalization in nuclear pairing  

SciTech Connect

We investigate the effects of the Coulomb force on the nuclear pairing properties by performing the Gogny Hartree-Fock-Bogolyubov calculations for the N=20, 28, 50, 82, and 126 nuclei. The Coulomb force reduces the proton pair energy and the even-odd mass difference by about 25%, except for nuclei at and around the proton shell or subshell closure. We then propose a renormalization scheme via a reduction factor {gamma}{sub p} for the proton pairing channel. It is found that a single value {gamma}{sub p}=0.90 accounts well for the Coulombic effect for nuclei covering a wide range of the mass number and the neutron excess, including the nuclei around the shell or subshell closure.

Nakada, H.; Yamagami, M. [Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522 (Japan); Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8580 (Japan)

2011-03-15

283

"Safe" Coulomb excitation of 30Mg.  

PubMed

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion." PMID:15904283

Niedermaier, O; Scheit, H; Bildstein, V; Boie, H; Fitting, J; von Hahn, R; Köck, F; Lauer, M; Pal, U K; Podlech, H; Repnow, R; Schwalm, D; Alvarez, C; Ames, F; Bollen, G; Emhofer, S; Habs, D; Kester, O; Lutter, R; Rudolph, K; Pasini, M; Thirolf, P G; Wolf, B H; Eberth, J; Gersch, G; Hess, H; Reiter, P; Thelen, O; Warr, N; Weisshaar, D; Aksouh, F; Van den Bergh, P; Van Duppen, P; Huyse, M; Ivanov, O; Mayet, P; Van de Walle, J; Aystö, J; Butler, P A; Cederkäll, J; Delahaye, P; Fynbo, H O U; Fraile, L M; Forstner, O; Franchoo, S; Köster, U; Nilsson, T; Oinonen, M; Sieber, T; Wenander, F; Pantea, M; Richter, A; Schrieder, G; Simon, H; Behrens, T; Gernhäuser, R; Kröll, T; Krücken, R; Münch, M; Davinson, T; Gerl, J; Huber, G; Hurst, A; Iwanicki, J; Jonson, B; Lieb, P; Liljeby, L; Schempp, A; Scherillo, A; Schmidt, P; Walter, G

2005-05-04

284

``Safe'' Coulomb Excitation of 30Mg  

NASA Astrophysics Data System (ADS)

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient ? spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin natNi target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation ?-ray yields the B(E2;0+gs?2+1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the “island of inversion.”

Niedermaier, O.; Scheit, H.; Bildstein, V.; Boie, H.; Fitting, J.; von Hahn, R.; Köck, F.; Lauer, M.; Pal, U. K.; Podlech, H.; Repnow, R.; Schwalm, D.; Alvarez, C.; Ames, F.; Bollen, G.; Emhofer, S.; Habs, D.; Kester, O.; Lutter, R.; Rudolph, K.; Pasini, M.; Thirolf, P. G.; Wolf, B. H.; Eberth, J.; Gersch, G.; Hess, H.; Reiter, P.; Thelen, O.; Warr, N.; Weisshaar, D.; Aksouh, F.; van den Bergh, P.; van Duppen, P.; Huyse, M.; Ivanov, O.; Mayet, P.; van de Walle, J.; Äystö, J.; Butler, P. A.; Cederkäll, J.; Delahaye, P.; Fynbo, H. O.; Fraile, L. M.; Forstner, O.; Franchoo, S.; Köster, U.; Nilsson, T.; Oinonen, M.; Sieber, T.; Wenander, F.; Pantea, M.; Richter, A.; Schrieder, G.; Simon, H.; Behrens, T.; Gernhäuser, R.; Kröll, T.; Krücken, R.; Münch, M.; Davinson, T.; Gerl, J.; Huber, G.; Hurst, A.; Iwanicki, J.; Jonson, B.; Lieb, P.; Liljeby, L.; Schempp, A.; Scherillo, A.; Schmidt, P.; Walter, G.

2005-05-01

285

1/f Noise in a Coulomb Glass.  

NASA Astrophysics Data System (ADS)

Low frequency 1/f noise is found in Coulomb glasses, among other systems with slow relaxation. It has been recently studied in detail in Si:B in the experimental work of Massey and Lee [1]. They concluded that their findings were inconsistent with the single-particle mechanisms proposed earlier. We show that the observed noise can be produced by charge fluctuations due to electrons hopping between isolated sites and a percolating network at low temperatures [2]. Coulomb interactions are included through the Coulomb gap in the density of states. The low frequency noise spectrum goes as ?^-? with ? slightly larger than 1. This result, together with the temperature dependence of ? and the noise amplitude are in good agreement with the experiments of Massey and Lee. [1] J. G. Massey and Mark Lee, Phys. Rev. Lett. 79, 3986 (1997). [2] Kirill Shtengel and Clare C. Yu (2001), cond-mat/0111302.

Yu, Clare C.; Shtengel, Kirill

2002-03-01

286

alpha-particle nuclear surface absorption below the Coulomb barrier in heavy nuclei  

SciTech Connect

An analysis of all available alpha-particle-induced reaction cross sections on nuclei within the mass number range 121<=A<=197, below the Coulomb barrier, is carried out. This analysis leads to an optical potential that describes the alpha-particle elastic scattering at low energies as well and both elastic-scattering and reaction data for 45<=A<=124. The energy dependence of the surface imaginary potential depth is proved to be essential for understanding alpha-particle interaction behavior below the Coulomb barrier.

Avrigeanu, M.; Avrigeanu, V. ['Horia Hulubei' National Institute for Physics and Nuclear Engineering, Post Office Box MG-6, R-077125 Bucharest-Magurele (Romania)

2010-07-15

287

Molecular motor based entirely on the Coulomb interaction.  

PubMed

A molecular motor is introduced which is composed of charges only and which does not contain any potential or interaction besides the Coulomb one. The motor is shown to transform efficiently a driven random rotation into a directed translational motion. The direction of translational motion can be chosen dynamically, so that a "forward gear," a "reverse gear," and even a "neutral gear" exist. The high efficiency stems from the fact that this motor only steps in the direction determined by the chosen gear. PMID:11308618

Porto, M

2001-02-27

288

Coulomb correlation effects in zinc monochalcogenides  

NASA Astrophysics Data System (ADS)

Electronic structure and band characteristics for zinc monochalcogenides with zinc-blende- and wurtzite-type structures are studied by first-principles density-functional-theory calculations with different approximations. It is shown that the local-density approximation underestimates the band gap and energy splitting between the states at the top of the valence band, misplaces the energy levels of the Zn-3d states, and overestimates the crystal-field-splitting energy. The spin-orbit-coupling energy is found to be overestimated for both variants of ZnO, underestimated for ZnS with wurtzite-type structure, and more or less correct for ZnSe and ZnTe with zinc-blende-type structure. The order of the states at the top of the valence band is found to be anomalous for both variants of ZnO, but is normal for the other zinc monochalcogenides considered. It is shown that the Zn-3d electrons and their interference with the O-2p electrons are responsible for the anomalous order. The effective masses of the electrons at the conduction-band minimum and of the holes at the valence-band maximum have been calculated and show that the holes are much heavier than the conduction-band electrons in agreement with experimental findings. The calculations, moreover, indicate that the effective masses of the holes are much more anisotropic than the electrons. The typical errors in the calculated band gaps and related parameters for ZnO originate from strong Coulomb correlations, which are found to be highly significant for this compound. The local-density approximation with multiorbital mean-field Hubbard potential approach is found to correct the strong correlation of the Zn-3d electrons, and thus to improve the agreement between the experimentally established location of the Zn-3d levels and that derived from pure LDA calculations.

Karazhanov, S. Zh.; Ravindran, P.; Kjekshus, A.; Fjellva?G, H.; Grossner, U.; Svensson, B. G.

2006-08-01

289

Reactions of halo states: Coulomb excitations  

SciTech Connect

Coulomb dissociation is a relatively clean probe of the structures of one- and two-nucleon halo nuclei. This is illustrated by the breakup of {sup 11}Be, {sup 8}B and {sup 11}Li and is discussed in terms of first order perturbation theory. First-order dipole transitions usually dominate the Coulomb dissociation but quadrupole transitions are not insignificant for a proton halo (e.g. {sup 8}B). Higher-order processes can also distort the observables, such as the momentum distributions of the fragments and the excitation energy spectrum.

Esbensen, H.

1997-09-01

290

Hard pion bremsstrahlung in the Coulomb region  

SciTech Connect

Hard high-energy pion-nucleus bremsstrahlung, {pi}{sup -}+A{yields}{pi}{sup -}+{gamma}+A, is studied in the Coulomb region, i.e., the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying pion-Compton amplitude through a model with {sigma},{rho}, and a{sub 1} exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.

Faeldt, Goeran; Tengblad, Ulla [Department of Nuclear and Particle Physics, Uppsala University, Box 535, S-751 21 Uppsala (Sweden)

2007-12-15

291

Coulomb force as an entropic force  

SciTech Connect

Motivated by Verlinde's theory of entropic gravity, we give a tentative explanation to the Coulomb's law with an entropic force. When trying to do this, we find the equipartition rule should be extended to charges and the concept of temperature should be reinterpreted. If one accepts the holographic principle as well as our generalizations and reinterpretations, then Coulomb's law, the Poisson equation, and the Maxwell equations can be derived smoothly. Our attempt can be regarded as a new way to unify the electromagnetic force with gravity, from the entropic origin. Possibly some of our postulates are related to the D-brane picture of black hole thermodynamics.

Wang Tower [Center for High-Energy Physics, Peking University, Beijing 100871 (China)

2010-05-15

292

Upper-division student understanding of Coulomb's law: Difficulties with continuous charge distributions  

NASA Astrophysics Data System (ADS)

Utilizing the integral expression of Coulomb's Law to determine the electric potential from a continuous charge distribution is a canonical exercise in Electricity and Magnetism (E&M). In this study, we use both think-aloud interviews and responses to traditional exam questions to investigate student difficulties with this topic at the upper-division level. Leveraging a theoretical framework for the use of mathematics in physics, we discuss how students activate, construct, execute and reflect on the integral form of Coulomb's Law when solving problems with continuous charge distributions. We present evidence that junior-level E&M students have difficulty mapping physical systems onto the mathematical expression for the Coulomb potential. Common challenges include difficulty expressing the difference vector in appropriate coordinates as well as determining expressions for the differential charge element and limits of integration for a specific charge distribution. We discuss possible implications of these findings for future research directions and instructional strategies.

Wilcox, Bethany R.; Caballero, Marcos D.; Pepper, Rachel E.; Pollock, Steven J.

2013-01-01

293

Physlets Tour 7: Coulomb's Law  

NSDL National Science Digital Library

The first simulation shows charges with arrows and represents the total force acting on each charge. The second simulation shows the potential energy of each charge. As you move the charges, these visual clues change appropriately.

Christian, Wolfgang; Belloni, Mario

2006-01-13

294

Short-time rheology and diffusion in suspensions of Yukawa-type colloidal particles  

NASA Astrophysics Data System (ADS)

A comprehensive study is presented on the short-time dynamics in suspensions of charged colloidal spheres. The explored parameter space covers the major part of the fluid-state regime, with colloid concentrations extending up to the freezing transition. The particles are assumed to interact directly by a hard-core plus screened Coulomb potential, and indirectly by solvent-mediated hydrodynamic interactions. By comparison with accurate accelerated Stokesian Dynamics (ASD) simulations of the hydrodynamic function H(q), and the high-frequency viscosity ??, we investigate the accuracy of two fast and easy-to-implement analytical schemes. The first scheme, referred to as the pairwise additive (PA) scheme, uses exact two-body hydrodynamic mobility tensors. It is in good agreement with the ASD simulations of H(q) and ??, for smaller volume fractions up to about 10% and 20%, respectively. The second scheme is a hybrid method combining the virtues of the ?? scheme by Beenakker and Mazur with those of the PA scheme. It leads to predictions in good agreement with the simulation data, for all considered concentrations, combining thus precision with computational efficiency. The hybrid method is used to test the accuracy of a generalized Stokes-Einstein (GSE) relation proposed by Kholodenko and Douglas, showing its severe violation in low salinity systems. For hard spheres, however, this GSE relation applies decently well.

Heinen, Marco; Banchio, Adolfo J.; Nägele, Gerhard

2011-10-01

295

Asymptotic Expansion of the Irregular Coulomb Function  

Microsoft Academic Search

It is shown that the irregular Coulomb Function GL can be expanded as an asymptotic power series in the energy, with coefficients which are expressible in terms of the modified Bessel function of the second kind. The form of the coefficients is the same as obtained by Yost, Wheeler, and Breit in an expansion of the regular function FL with

G. Breit; M. H. Hull

1950-01-01

296

Coulomb relaxation of electron-temperature anisotropy  

Microsoft Academic Search

Hyatt et al. (1987) have carried out an experiment on the collisional relaxation of electron-temperature anisotropy in a laboratory plasma containing singly ionized ions. They observed equalization of the longitudinal and transverse temperature with respect to the external magnetic field as a result of Coulomb electron collisions. A theoretical examination of electron-temperature anisotropy relaxation is carried out in the present

Iu. V. Konikov

1990-01-01

297

Coulomb's Electrical Measurements. Experiment No. 14.  

ERIC Educational Resources Information Center

|Presented is information related to the life and work of Charles Coulomb as well as detailed notes of his measurements of the distribution of electricity on conductors. The two methods that he used (the large torsion balance, and the timing of "force" oscillations) are described. (SA)|

Devons, Samuel

298

Coulomb-driven convection in electrohydrodynamics  

Microsoft Academic Search

The Coulomb-driven EHD instabilities, chaos, and turbulence generated by unipolar injection in insulating liquids are reviewed. Only systems of the greatest simplicity, well suited for a fundamental study, are considered. As the paper is intended to be introductory, the emphasis is on the physical mechanisms responsible for EHD phenomena

A. Castellanos

1991-01-01

299

Coulomb Coupling Between Quantum Dots and Waveguides.  

National Technical Information Service (NTIS)

This AASERT award augmented and provided additional support for the parent grant entitled 'Quantum Cellular Automata' (QCA), ONR grant N00014-93-1- 1084. Initially, the main focus of this research was the study of Coulombic coupling effects in semiconduct...

W. Porod C. S. Lent G. H. Bernstein

2000-01-01

300

Coulomb Explosion of Large Penetrating Molecular Clusters.  

National Technical Information Service (NTIS)

The main purpose of these Coulomb explosion measurements is to determine what kind of structure these and other complex molecules may have and also to determine what other special phenomena may come into play as these complex molecules pass through matter...

H. E. Wegner P. Thieberger

1981-01-01

301

Coulomb excitation of radioactive 20, 21Na  

NASA Astrophysics Data System (ADS)

The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ˜ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for ? -ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B ( ? L) values were determined using the 2+ rightarrow 0+ de-excitation in 48Ti as a reference. The resulting B( E2) ? value for 21Na is 137±9 e^2fm^4, while the resulting B( ? L) ? values for 20Na are 55±6 e^2fm^4 for the 3+ rightarrow 2+ , 35.7±5.7 e^2 fm^4 for the 4+ rightarrow 2+ , and 0.154±0.030 ?_ N^2 for the 4+ rightarrow 3+ transitions. This analysis significantly improves the measurement of the 21Na B( E2) value, and provides the first experimental determination of B( ? L) values for the proton dripline nucleus 20Na .-1

Schumaker, M. A.; Cline, D.; Hackman, G.; Pearson, C.; Svensson, C. E.; Wu, C. Y.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Buchmann, L.; Churchman, R.; Cifarelli, F.; Cooper, R. J.; Cross, D. S.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T. E.; Finlay, P.; Gallant, A. T.; Garrett, P. E.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Lisetskiy, A. F.; Leach, K. G.; Lee, G.; Maharaj, R.; Martin, J.-P.; Moisan, F.; Morton, A. C.; Mythili, S.; Nelson, L.; Newman, O.; Nolan, P. J.; Orce, J. N.; Padilla-Rodal, E.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Roy, R.; Ruiz, C.; Sarazin, F.; Scraggs, D. P.; Waddington, J. C.; Wan, J. M.; Whitbeck, A.; Williams, S. J.; Wong, J.

2009-12-01

302

Coulombic Effects on Ion Mobility Spectrometry  

SciTech Connect

The ion mobility spectrometry (IMS) is now taking its place among widely applied analytical methods. When coupled with mass spectrometers (MS), IMS becomes a powerful analytical tool for separating complex samples and investigating molecular structure, and improvements of IMS-MS instrumentation, e.g. to IMS resolving power and sensitivity, are highly desirable. Implementation of an ion trap for accumulation and pulsed ion injection to IMS based on the ion funnel has provided considerably increased ion currents, and thus a basis for improved sensitivity and (indirectly) measurement throughput. However, large ion populations may manifest Coulombic effects contributing to the spatial dispersion of ions traveling in the IMS drift tube, and thus affect IMS resolving power. In this study we present an analysis of Coulombic effects on IMS resolution. Basic relationships have been obtained for the spatial evolution of ion packets due to Coulombic repulsion. The theoretical relationships were compared with results of a computer model that simulates IMS operation based on a first principles approach. Initial experimental results reported here are consistent with the computer modeling and these relationships. A noticeable decrease of the IMS resolving power was observed for specific ion populations of >10,000 elementary charges. IMS operation conditions to minimize Coulombic effects, while minimizing sacrifices to performance, are discussed.

Tolmachev, Aleksey V.; Clowers, Brian H.; Belov, Mikhail E.; Smith, Richard D.

2009-06-15

303

Stretched exponential relaxation in the Coulomb glass  

Microsoft Academic Search

The relaxation of the specific heat and the entropy to their equilibrium values is investigated numerically for the three-dimensional Coulomb glass at very low temperatures. The long time relaxation follows a stretched exponential function, f(t) = f0 exp ? ?(t\\/?)? ? , with the exponentincreasing with the temperature. The relaxation time follows an Arrhenius behavior divergence when T ? 0.

A. D ´ õaz-Sanchez; A. Perez-Garrido

304

Molecular Dynamics Simulations of Coulomb Explosion.  

National Technical Information Service (NTIS)

A swift ion creates a track of electronic excitations in the target material. A net repulsion inside the track can cause a 'Coulomb Explosion', which can lead to damage and sputtering of the material. Here we report results from molecular-dynamics (MD) si...

E. M. Bringa

2002-01-01

305

Above-threshold ionization with highly charged ions in superstrong laser fields. I. Coulomb-corrected strong-field approximation  

NASA Astrophysics Data System (ADS)

Aiming at the investigation of above-threshold ionization in superstrong laser fields with highly charged ions, we develop a Coulomb-corrected strong-field approximation (SFA). The influence of the Coulomb potential of the atomic core on the ionized electron dynamics in the continuum is taken into account via the eikonal approximation, treating the Coulomb potential perturbatively in the phase of the quasiclassical wave function of the continuum electron. In this paper the formalism of the Coulomb-corrected SFA for the nonrelativistic regime is discussed, employing velocity and length gauge. Direct ionization of a hydrogenlike system in a strong linearly polarized laser field is considered. The relation of the results in the different gauges to the Perelomov-Popov-Terent'ev imaginary-time method is discussed.

Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.

2013-02-01

306

Nonperturbative formulation of relativistic two-particle states in the scalar Yukawa model  

SciTech Connect

We investigate a variational approach to the study of two-particle bound states in quantum field theory. The scalar Yukawa model, in which scalar {open_quotes}nucleons{close_quotes} interact via {open_quotes}meson{close_quotes} exchange, is considered. A variational trial state that contains one or two scalar nucleons with any number of mediating scalar mesons is used to derive integral equations for the one- and two-nucleon systems. Numerical solutions of these equations are obtained in 1+1 dimensions. Comparison is made with perturbative and nonrelativistic approximations that have been used in earlier calculations. {copyright} {ital 1997 American Institute of Physics.}

Darewych, J.W.; Shapoval, D.V.; Simenog, I.V.; Sitenko, A.G. [Department of Physics and Astronomy, York University, Toronto, Ontario M3J 1P3 (Canada)

1997-08-01

307

Geometrical defects in two-dimensional melting of many-particle Yukawa systems.  

PubMed

We present a theoretical polygon construction analysis of two-dimensional melting and freezing transitions in many-particle Yukawa systems. Two-dimensional melting transitions can be characterized as proliferation of geometrical defects--nontriangular polygons, obtained by removing unusually long bonds in the triangulation of particle positions. A liquid state is characterized by the temperature-independent number of quadrilaterals and linearly increasing number of pentagons. We analyze specific types of vertices, classified by the type and distribution of polygons surrounding them, and determine temperature dependencies of their concentrations. Solid-liquid phase transitions are followed by the peaks in the abundances of certain types of vertices. PMID:23214742

Radzvilavi?ius, Ar?nas

2012-11-09

308

Dark Matter from SUGRA GUTs: mSUGRA, NUSUGRA and Yukawa-unified SUGRA  

SciTech Connect

Gravity-mediated SUSY breaking models with R-parity conservation give rise to dark matter in the universe. I review neutralino dark matter in the minimal supergravity model (mSUGRA), models with non-universal soft SUSY breaking terms (NUSUGRA) which yield a well-tempered neutralino, and models with unified Yukawa couplings at the GUT scale (as may occur in an SO(10) SUSY GUT theory). These latter models have difficulty accomodating neutralino dark matter, but work very well if the dark matter particles are axions and axinos.

Baer, Howard [Dep't of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

2009-09-08

309

Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems.  

PubMed

Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed. PMID:22680584

Khrustalyov, Yu V; Vaulina, O S

2012-04-04

310

SU(5) and SO(10) models from F-theory with natural Yukawa couplings  

Microsoft Academic Search

We construct the SU(5) and SO(10) models from F-theory. Turning on the U(1) fluxes, we can break the SU(5) gauge symmetry down to the standard model (SM) gauge symmetry, and break the SO(10) gauge symmetry down to the SU(3)C×SU(2)L×SU(2)R×U(1)B-L gauge symmetry. In particular, all the SM fermion Yukawa couplings preserve the enhanced U(1)a×U(1)b gauge or global symmetries at the triple

Tianjun Li

2010-01-01

311

SU(5) and SO(10) models from F-theory with natural Yukawa couplings  

Microsoft Academic Search

We construct the SU(5) and SO(10) models from F-theory. Turning on the U(1) fluxes, we can break the SU(5) gauge symmetry down to the standard model (SM) gauge symmetry, and break the SO(10) gauge symmetry down to the SU(3){sub C}xSU(2){sub L}xSU(2){sub R}xU(1){sub B-L} gauge symmetry. In particular, all the SM fermion Yukawa couplings preserve the enhanced U(1){sub a}xU(1){sub b} gauge

Li Tianjun

2010-01-01

312

Schwinger-Dyson approach for a Lifshitz-type Yukawa model  

SciTech Connect

We consider a 3+1 dimensional field theory at a Lifshitz point for a dynamical critical exponent z=3, with a scalar and a fermion field coupled via a Yukawa interaction. Using the nonperturbative Schwinger-Dyson approach we calculate quantum corrections to the effective action. We demonstrate that a first order derivative kinetic term as well as a mass term for the fermion arise dynamically. This signals the restoration of Lorentz symmetry in the IR regime of the single fermion model, although for theories with more than one fermionic species such a conclusion will require fine-tuning of couplings. The limitations of the model and our approach are discussed.

Alexandre, J. [Department of Physics, King's College London, WC2R 2LS (United Kingdom); Farakos, K.; Pasipoularides, P. [Department of Physics, National Technical University of Athens Zografou Campus, 157 80 Athens (Greece); Tsapalis, A. [Department of Physics, National Technical University of Athens Zografou Campus, 157 80 Athens (Greece); Hellenic Naval Academy, Hatzikyriakou Avenue, Pireaus 185 39 (Greece)

2010-02-15

313

Heat transfer coefficients in two-dimensional Yukawa systems (numerical simulations)  

NASA Astrophysics Data System (ADS)

New data on heat transfer in two-dimensional Yukawa systems have been obtained. The results of a numerical study of the thermal conductivity for equilibrium systems with parameters close to the conditions of laboratory experiments in dusty plasma are presented. The Green-Kubo relations are used to calculate the heat transfer coefficients. The influence of dissipation (internal friction) on the heat transfer processes in nonideal systems is studied. New approximations are proposed for the thermal conductivity and diffusivity for nonideal dissipative systems. The results obtained are compared with the existing experimental and numerical data.

Khrustalyov, Yu. V.; Vaulina, O. S.

2013-05-01

314

Examining the identity of Yukawa with gauge couplings in supersymmetric QCD at LHC  

SciTech Connect

The identity of the quark-squark-gluino Yukawa coupling with the corresponding quark-quark-gluon QCD coupling in supersymmetric theories can be examined experimentally at the Large Hadron Collider (LHC). Extending earlier investigations of like-sign di-lepton final states, we include jets in the analysis of the minimal supersymmetric standard model, adding squark-gluino and gluino-pair production to squark-pair production. Moreover we expand the method towards model-independent analyses which cover more general scenarios. In all cases, squark decays to light charginos and neutralinos persist to play a dominant role.

Freitas, Ayres; /Zurich U.; Skands, Peter Z.; /Fermilab; Spira, M.; /PSI, Villigen; Zerwas, P.M.; /DESY

2007-03-01

315

Leading two-loop Yukawa corrections to the pole masses of SUSY fermions in the MSSM  

NASA Astrophysics Data System (ADS)

We have calculated the leading Yukawa corrections to the chargino, neutralino and gluino pole masses in the DR scheme in the minimal supersymmetric Standard Model (MSSM) with the full set of complex parameters. We have performed a numerical analysis for a particular point in the parameter space and found typical corrections of a few tenths of a percent thus exceeding the experimental resolution as expected at the ILC. We provide a computer program which calculates two-loop pole masses for SUSY fermions with complex parameters up to O(??,Y,?Y).

Schöfbeck, R.; Eberl, H.

2008-07-01

316

Determining the chirality of Yukawa couplings via single charged Higgs boson production in polarized photon collisions.  

PubMed

When the charged Higgs boson is too heavy to be produced in pairs, the predominant production mechanism at linear colliders is via the single charged Higgs boson production processes, such as e(-)e(+)-->bcH+,taunuH+ and gammagamma-->bcH+,taunuH+. We show that the yield of a heavy charged Higgs boson at a gammagamma collider is typically 1 or 2 orders of magnitude larger than that at an e(-)e(+) collider. Furthermore, a polarized gammagamma collider can determine the chirality of the Yukawa couplings of fermions with charged Higgs boson via single charged Higgs boson production and, thus, discriminate models of new physics. PMID:12225184

He, Hong-Jian; Kanemura, Shinya; Yuan, C-P

2002-08-15

317

Tunable Coulomb blockade and giant Coulomb blockade magnetoresistance in a double quantum dot array  

SciTech Connect

We propose a Hubbard model to illuminate the tunneling effect of electrons in a double quantum dot array connected in the parallel circuit configuration to electrodes. The change in the interdot coupling is shown to dramatically influence the Coulomb blockade properties, consistent with earlier experimental observations. For magnetic double dots, the interdot coupling can be tuned by the external magnetic field, leading to a giant Coulomb blockade magnetoresistance.

Zhang, Xiaoguang [ORNL; Xiang, T. [Chinese Academy of Sciences

2011-01-01

318

Three-Center Coulombic Over-Barrier Model for Multiple Electron Capture by Slow Highly Charged Ions from Diatomic Molecules  

Microsoft Academic Search

A three-center Coulombic over-barrier model is proposed for the process of multiple electron capture from homonuclear diatomic molecules in collisions with slow highly charged ions. The present model, based on the over-barrier model for atomic targets given by Niehaus, takes further into account the two-center nature of molecular targets by introducing a three-center Coulomb potential for respective electrons. Cross sections

A. Ichimura; T. Ohyama-Yamaguchi

1999-01-01

319

Certain properties of an electrically insulated Coulomb plasma. Numerical simulation of microfields and thermodynamic properties. the problem of ball lightning  

Microsoft Academic Search

Many-body dynamics is used to study the (quasi-)steady state of a classical Coulomb plasma. The shortest relaxation time in such a plasma, for both the Debye screening and the thermodynamic properties, is the electron transit time over the average distance between ions. The steady-state energy of the Coulomb interaction of the particles and the steady-state potential near a fixed charge

S. A. Maiorov; A. N. Tkachev; S. I. Yakovlenko

1992-01-01

320

Laser-induced processes during the Coulomb explosion of H2 in a Ti-sapphire laser pulse  

Microsoft Academic Search

Theoretical simulations of processes leading to the complete Coulomb explosion of H2 under a 150-fs, 800-nm Ti:sapphire laser pulse are made using two approaches. The first approach consists of purely nuclear, multichannel wave-packet calculations while the second approach involves electronic-nuclear, three-body wave-packet propagations on one-dimensional Coulomb-type potentials. The calculations that give proton kinetic energy spectra in qualitative agreement with the

T. D. Walsh; F. A. Ilkov; S. L. Chin; F. Châteauneuf; T. T. Nguyen-Dang; S. Chelkowski; A. D. Bandrauk; O. Atabek

1998-01-01

321

Tidally driven Coulomb failure of faults on Enceladus and Europa  

NASA Astrophysics Data System (ADS)

The icy fractured surfaces of both Enceladus and Europa offer many candidate faults for studying both past and potentially present tectonic activity. Here we investigate the role of both diurnal and non-synchronous rotation (NSR) tidal stresses in the development of Enceladus’s tiger stripes and fractures on Europa, notably Agenor Linea. For Enceladus, our objectives are to constrain ice shell thickness, and thus its implied water ocean depth, through assessment of the conditions which permit tidally driven (diurnal) Coulomb failure of the tiger stripe fractures. We find that thin to moderate ice shell thicknesses (< 40 km) support failure along the Enceladus tiger stripes, assuming low ice coefficients of friction (0.1 - 0.3) and shallow fracture depths (< 3 km). In contrast, diurnal tidal stresses on Europa may be insufficient to cause Coulomb failure; thus, we consider the role of NSR as a secular stress source for strike-slip faulting. Preliminary application of the Coulomb failure criterion, assuming ?f = 0.2 and a fault depth of 6 km, reveals that a combination of NSR (104 - 105 yr period) and diurnal tidal stresses are required for Agenor Linea to succumb to right-lateral shear failure at specific portions of the orbital cycle. We further explore the relationship of NSR to Agenor Linea’s east-west orientation and find that if the fault were instead oriented in the north-south direction, NSR would generate only left-lateral shear and compressive normal stress, neither of which could constructively combine to produce the inferred right-lateral shear. Together, these tidally driven failure models for Enceladus and Europa are providing key insights into the frictional and material properties, and their variation and orientation with depth, of active fault systems on icy satellites.

Olgin, J. G.; Smith-Konter, B. R.; Pappalardo, R. T.; Icy Moons Tectonics Team

2010-12-01

322

Yukawa fluids in the mean scaling approximation: I. The general solutionWe dedicate this paper to Yasha Rosenfeld, a giant in condensed matter physics  

Microsoft Academic Search

A new general form of the multi-Yukawa, multicomponent closure of the Ornstein–Zernike equation for factored interactions is derived. The general solution is given in terms of an M × M scaling matrix obtained by solving M (equal to the number of Yukawa terms in the closure) equations together with M(M ? 1) symmetry conditions where ??( n) is of higher

L Blum; J A Hernando

2002-01-01

323

Hamiltonian approach to 1 + 1 dimensional Yang-Mills theory in Coulomb gauge  

SciTech Connect

We study the Hamiltonian approach to 1 + 1 dimensional Yang-Mills theory in Coulomb gauge, considering both the pure Coulomb gauge and the gauge where in addition the remaining constant gauge field is restricted to the Cartan algebra. We evaluate the corresponding Faddeev-Popov determinants, resolve Gauss' law and derive the Hamiltonians, which differ in both gauges due to additional zero modes of the Faddeev-Popov kernel in the pure Coulomb gauge. By Gauss' law the zero modes of the Faddeev-Popov kernel constrain the physical wave functionals to zero colour charge states. We solve the Schroedinger equation in the pure Coulomb gauge and determine the vacuum wave functional. The gluon and ghost propagators and the static colour Coulomb potential are calculated in the first Gribov region as well as in the fundamental modular region, and Gribov copy effects are studied. We explicitly demonstrate that the Dyson-Schwinger equations do not specify the Gribov region while the propagators and vertices do depend on the Gribov region chosen. In this sense, the Dyson-Schwinger equations alone do not provide the full non-abelian quantum gauge theory, but subsidiary conditions must be required. Implications of Gribov copy effects for lattice calculations of the infrared behaviour of gauge-fixed propagators are discussed. We compute the ghost-gluon vertex and provide a sensible truncation of Dyson-Schwinger equations. Approximations of the variational approach to the 3 + 1 dimensional theory are checked by comparison to the 1 + 1 dimensional case.

Reinhardt, H. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)], E-mail: hugo.reinhardt@uni-tuebingen.de; Schleifenbaum, W. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)], E-mail: wschleifenbaum@web.de

2009-04-15

324

Elastic scattering of 9Li on 208Pb at energies around the Coulomb barrier  

NASA Astrophysics Data System (ADS)

We have studied the dynamical effects of the halo structure of 11Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated 11Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. 9Li on 208Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

Cubero, M.; Fernández-García, J. P.; Lay, J. A.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Borge, M. J. G.; Buchmann, L.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gómez-Camacho, J.; Martel, I.; Moro, A. M.; Mukha, I.; Nilsson, T.; Sánchez-Benítez, A. M.; Shotter, A.; Tengblad, O.; Walden, P.

2011-10-01

325

Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier  

SciTech Connect

We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

Cubero, M. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); CICANUM, Universidad de Costa Rica, Apdo. 2060, San Jose (Costa Rica); Fernandez-Garcia, J. P.; Alvarez, M. A. G. [Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Centro Nacional de Aceleradores, Avda. Thomas A. Edison, E-41092, Sevilla (Spain); Lay, J. A.; Moro, A. M. [Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Acosta, L.; Martel, I.; Sanchez-Benitez, A. M. [Departamento de Fisica Aplicada, Facultad de Ciencias, Universidad de Huelva (Spain); Alcorta, M.; Borge, M. J. G.; Tengblad, O. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Buchmann, L.; Shotter, A.; Walden, P. [TRIUMF, V6T2A3 Vancouver B.C. (Canada); Diget, D. G.; Fulton, B. [Department of Physics, University of York, YO10 5DD Heslington, York (United Kingdom); Fynbo, H. O. U. [Department of Physics and Astronomy, University ofAarhus, DK-8000, Aarhus (Denmark); Galaviz, D. [Centro de Fisica Nuclear da Universidade de Lisboa, 1649-003 Lisbon (Portugal); Gomez-Camacho, J. [Centro Nacional de Aceleradores, Avda. Thomas A. Edison, E-41092, Sevilla (Spain); Departamento de FAMN, Universidad de Sevilla, Apdo. 1065, E-41080 Sevilla (Spain); Mukha, I. [Instituto de Fisica Corpuscular, CSIC-Universidadde Valencia (Spain)

2011-10-28

326

Bond alternation in the infinite polyene: effect of long range Coulomb interactions  

SciTech Connect

We investigate the effects of long-range Coulomb interactions on bond and site dimerizations in a one-dimensional half-filled band. It is shown that the ground state broken symmetry is determined by two sharp inequalities involving the Coulomb parameters. Broken symmetry with periodicity 2k/sub F/ is guaranteed only if the first inequality (downward convexity of the intersite potential) is obeyed, while the second inequality gives the phase boundary between the bond-dimerized and site-dimerized phases. Application of these inequalities to the Pariser-Parr-Pople model for linear polyenes shows that the infinite polyene has enhanced bond alternation for both Ohno and Mataga-Nishimoto parametrizations of the intersite Coulomb terms. The possible role of distant neighbor interactions in photogeneration experiments is discussed. 26 refs., 3 figs.

Mazumdar, S.; Campbell, D.K.

1985-01-01

327

Artificial carrier heating due to the introduction of ab initio Coulomb scattering in Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

Accurately treating ionised impurity scattering in a way suitable to describe the influence of random dopant fluctuations on device characteristics is important in next generation MOSFETs. Statistical variations are unobservable using a continuous treatment of the doping, requiring a discrete representation of impurities. In particle-based simulations the P3M method, which resolves the Coulomb interaction into long- and short-range components, is in principle capable of describing Coulomb scattering through propagation in this accurately resolved potential. However, numerically the integration of the equations of motion is inaccurate and controlling the errors in practical simulations is vital. In this paper we investigate the effect of the choice of short-range correction strategy and integration time step on accuracy in a 3D self-consistent ensemble Monte Carlo simulations featuring random discrete dopants. We illustrate the importance of the `ab initio' Coulomb scattering comparing the effect of a single trapped charge in drift-diffusion and Monte Carlo simulations.

Alexander, C.; Watling, J. R.; Brown, A. R.; Asenov, A.

2003-09-01

328

Path integral treatment for a Coulomb system constrained on D-dimensional sphere and hyperboloid  

SciTech Connect

The propagator relating to the evolution of a particle on the D-sphere and the D-pseudosphere, subjected to the Coulomb potential, was reconsidered in the Faddeev-Senjanovic formalism. The mid-point is privileged. The space-time transformations used make it possible to regularize the singularity and to bring back the problem to its dynamical symmetry SU (1, 1)

Lecheheb, A. [Departement de Physique, Faculte des Sciences, Universite Mentouri, 25000 Constantine (Algeria)]. E-mail: lecheheb@caramail.com; Merad, M. [Departement de Physique, Centre Universitaire de Oum-El-Bouaghi, 04000 Oum-El-Bouaghi (Algeria); Boudjedaa, T. [Laboratoire de Physique Theorique, Faculte des Sciences, Universite de Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria)

2007-05-15

329

bbH production at the CERN LHC: Yukawa corrections and the leading Landau singularity  

SciTech Connect

At tree-level Higgs production in association with a b-quark pair proceeds through the small Yukawa bottom coupling in the standard model. Even in the limit where this coupling vanishes, electroweak one-loop effects, through the top-Higgs Yukawa coupling, in particular, can still trigger this reaction. This contribution is small for Higgs masses around 120 GeV but it quickly picks up for higher Higgs masses especially because the one-loop amplitude develops a leading Landau singularity and new thresholds open up. These effects can be viewed as the production of a pair of top quarks which rescatter to give rise to Higgs production through WW fusion. We study the leading Landau singularity in detail. Since this singularity is not integrable when the one-loop amplitude is squared, we regulate the cross section by taking into account the width of the internal top and W particles. This requires that we extend the usual box one-loop function to the case of complex masses. We show how this can be implemented analytically in our case. We study in some detail the cross section at the CERN LHC as a function of the Higgs mass and show how some distributions can be drastically affected compared to the tree-level result.

Boudjema, F.; Duc Ninh Le [LAPTH, Universite de Savoie, CNRS, BP 110, F-74941 Annecy-le-Vieux Cedex (France)

2008-11-01

330

Effective Yukawa couplings and flavor-changing Higgs boson decays at linear colliders  

SciTech Connect

We analyze the advantages of a linear-collider program for testing a recent theoretical proposal where the Higgs boson Yukawa couplings are radiatively generated, keeping unchanged the standard-model mechanism for electroweak-gauge-symmetry breaking. Fermion masses arise at a large energy scale through an unknown mechanism, and the standard model at the electroweak scale is regarded as an effective field theory. In this scenario, Higgs boson decays into photons and electroweak gauge-boson pairs are considerably enhanced for a light Higgs boson, which makes a signal observation at the LHC straightforward. On the other hand, the clean environment of a linear collider is required to directly probe the radiative fermionic sector of the Higgs boson couplings. Also, we show that the flavor-changing Higgs boson decays are dramatically enhanced with respect to the standard model. In particular, we find a measurable branching ratio in the range (10{sup -4}-10{sup -3}) for the decay H{yields}bs for a Higgs boson lighter than 140 GeV, depending on the high-energy scale where Yukawa couplings vanish. We present a detailed analysis of the Higgs boson production cross sections at linear colliders for interesting decay signatures, as well as branching-ratio correlations for different flavor-conserving/nonconserving fermionic decays.

Gabrielli, E. [CERN, PH-TH, CH-1211 Geneva 23 (Switzerland); Mele, B. [INFN, Sezione di Roma, c/o Dipartimento di Fisica, Universita di Roma 'La Sapienza', Piazzale A. Moro 2, I-00185 Rome (Italy)

2011-04-01

331

Measuring the top Yukawa coupling at the ILC at s=500GeV  

NASA Astrophysics Data System (ADS)

We report on the feasibility of the direct measurement of the top Yukawa coupling gt at the International Linear Collider during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the nonrelativistic QCD corrections which enhance the production cross section near the tt¯ threshold. The e+e-?tt¯H signal is reconstructed in the 6-jet+lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e-?tb¯W-/t¯bW+ (which includes e+e-?tt¯), e+e-?tt¯Z, and e+e-?tt¯g*?tt¯bb¯. We use a realistic fast Monte Carlo detector simulation. Signal events are selected using event shape variables, through jet clustering, and by identifying heavy flavor jets. Assuming a Higgs mass of 120 GeV, polarized electron and positron beams with (Pe-,Pe+)=(-0.8,+0.3), and an integrated luminosity of 1ab-1, we estimate that the e+e-?tt¯H events can be seen with a statistical significance of 5.2?, corresponding to the relative top Yukawa coupling measurement accuracy of |?gt/gt|=10%.

Yonamine, Ryo; Ikematsu, Katsumasa; Tanabe, Tomohiko; Fujii, Keisuke; Kiyo, Yuichiro; Sumino, Yukinari; Yokoya, Hiroshi

2011-07-01

332

A study of the pair and triplet structures of the quantum hard-sphere Yukawa fluid.  

PubMed

The pair and triplet structures of the quantum hard-sphere Yukawa fluid, evaluated for equilateral and isosceles correlations in both the r and the k spaces for a range of conditions and with a particular focus on a region where the onset of increasing number fluctuations takes place (for densities 0.4Yukawa attractions and the quantum diffraction effects in hard-sphere fluids. PMID:19239299

Sesé, Luis M

2009-02-21

333

Bionic Coulomb phase on the pyrochlore lattice  

NASA Astrophysics Data System (ADS)

A class of three-dimensional classical lattice systems with macroscopic ground state degeneracies, most famously the spin ice system, are known to exhibit “Coulomb” phases wherein long wavelength correlations within the ground state manifold are described by an emergent Maxwell electrodynamics. We discuss a more elaborate example of this phenomenon—the four-state Potts model on the pyrochlore lattice—where the long wavelength description now involves three independent gauge fields, as we confirm via simulation. The excitations above the ground state manifold are bions, defects that are simultaneously charged under two of the three gauge fields, and they exhibit an entropic interaction dictated by these charges. We also show that the distribution of flux loops exhibits a scaling with loop length and system size previously identified as characteristic of Coulomb phases.

Khemani, V.; Moessner, R.; Parameswaran, S. A.; Sondhi, S. L.

2012-08-01

334

Statistical description of Coulomb-like systems.  

PubMed

The solution of the problem of the partition function calculation for a Coulomb-like system is proposed. The quantum-field-theory approach is used to give a statistical description of a system of interacting particles with due regard to arbitrary spatially inhomogeneous configurations. Formation of structures in a Coulomb-like system is analyzed and applied to the case of of dusty crystals and two-dimensional colloidal crystals. In the one-dimensional case, an exact solution for the spatial distribution of charged particles is obtained. In the two- dimensional case, the exact partition function for homogeneous distribution of particles is presented. We have analytically derived the necessary condition for the crystal formation in a system of interacting particles in the three-dimensional case. PMID:22304048

Lev, B I; Zagorodny, A G

2011-12-08

335

COULOMB EFFECTS IN RELATIVISTIC NUCLEAR COLLISIONS  

SciTech Connect

We derive simple analytical formulas for Coulomb final state interactions and apply them to the analysis of recent data on nuclear collisions. The {pi}{sup -}/{pi}{sup +} ratio, the {pi}{sup +} inclusive cross section, and the n/p ratio are studied. A relativistic field theoretic model is used to derive the formulas to first order in Z{alpha}. Then, based on certain well known non-perturbative results, we recast those formulas in an approximate non-perturbative form to increase their domain of applicability and remove unphysical singularities arising from perturbation theory. The final formulas are covariant and take into account multiple independently moving charged fragments of finite size and finite thermal expansion velocities. Our studies demonstrate analytically the complexity and importance of Coulomb distortions in nuclear collisions.

Gyulassy, M.; Kaufmann, S.K.

1980-03-01

336

Rings and Coulomb boxes in dissipative environments  

NASA Astrophysics Data System (ADS)

We study a particle on a ring in the presence of a dissipative Caldeira-Leggett environment and derive its response to a dc field. We show how this non-equilibrium response is related to a flux averaged equilibrium response. We find, through a two-loop renormalization group analysis, that a large dissipation parameter ? flows to a fixed point ?R=?/(2?). We also reexamine the mapping of this problem to that of the Coulomb box and show that the relaxation resistance, of recent interest, is quantized for large ?. For finite ?>?R we find that a certain average of the relaxation resistance is quantized. We propose a Coulomb-box experiment to measure a quantized noise.

Etzioni, Yoav; Horovitz, Baruch; Le Doussal, Pierre

2012-12-01

337

Trapping of topological-structural defects in Coulomb crystals.  

PubMed

We study experimentally and theoretically structural defects which are formed during the transition from a laser cooled cloud to a Coulomb crystal, consisting of tens of ions in a linear radio frequency trap. We demonstrate the creation of predicted topological defects ("kinks") in purely two-dimensional crystals and also find kinks which show novel dynamical features in a regime of parameters not considered before. The kinks are always observed at the center of the trap, showing a large nonlinear localized excitation, and the probability of their occurrence saturates at ?0.5. Simulations reveal a strong anharmonicity of the kink's internal mode of vibration, due to the kink's extension into three dimensions. As a consequence, the periodic Peierls-Nabarro potential experienced by a discrete kink becomes a globally confining potential, capable of trapping one cooled defect at the center of the crystal. PMID:23581315

Mielenz, M; Brox, J; Kahra, S; Leschhorn, G; Albert, M; Schaetz, T; Landa, H; Reznik, B

2013-03-28

338

Multiple Coulomb Excitation of 167Er  

NASA Astrophysics Data System (ADS)

The ground-state rotational band in 167Er has been investigated through multiple Coulomb excitation with a 160-MeV 35Cl beam, Excited states up to 25/2+ were established by measuring ?-? coincidences and ?-ray angular distributions. Nuclear lifetimes for levels up to spin 23/2 have been determined by analysis of Doppler broadened ?-ray lineshapes. Considerable signature dependence was observed in level energies and M1 transition probabilities.

Ohshima, Masumi; Minehara, Eisuke; Ishii, Mitsuhiko; Inamura, Takashi; Hashizume, Akira

1983-09-01

339

Multiple Coulomb Excitation of 167Er  

Microsoft Academic Search

The ground-state rotational band in 167Er has been investigated through multiple Coulomb excitation with a 160-MeV 35Cl beam, Excited states up to 25\\/2+ were established by measuring gamma-gamma coincidences and gamma-ray angular distributions. Nuclear lifetimes for levels up to spin 23\\/2 have been determined by analysis of Doppler broadened gamma-ray lineshapes. Considerable signature dependence was observed in level energies and

Masumi Ohshima; Eisuke Minehara; Mitsuhiko Ishii; Takashi Inamura; Akira Hashizume

1983-01-01

340

Coulomb Barrier Transmission Resonance for Astrophysical Problems  

Microsoft Academic Search

In estimating the nonresonance nuclear reaction cross sections sigma(E) at low energies (≲20 keV) needed for astrophysical calculations, it is customary to extrapolate higher energy (≳20 keV) data for sigma(E) to low energies using the Gamow transmission coefficient representing the probability of bringing two charged particles to zero separation distance, which is unphysical and unrealistic since the Coulomb barrier does

Yeong E. Kim; Alexander L. Zubarev

1993-01-01

341

Screening of Coulomb Impurities in Graphene  

Microsoft Academic Search

We calculate exactly the vacuum polarization charge density in the field of a\\u000asubcritical Coulomb impurity, $Z|e|\\/r$, in graphene. Our analysis is based on\\u000athe exact electron Green's function, obtained by using the operator method, and\\u000aleads to results that are exact in the parameter $Z\\\\alpha$, where $\\\\alpha$ is\\u000athe \\

Ivan S. Terekhov; Alexander I. Milstein; Valeri N. Kotov; Oleg P. Sushkov

2008-01-01

342

Coulomb dissociation of {sup 27} P  

SciTech Connect

The {sup 26}Al nucleus has a shorter life-time than the Universe showing that the nucleosynthesis of this element might be an ongoing process in stars. The reaction {sup 26}Si(p,gamma){sup 27} P competes with the production of {sup 26}Al. Coulomb dissociation of {sup 27} P is an indirect method to measure that reaction. An experiment was performed at GSI with a {sup 36}Ar primary beam at 500 MeV to measure this reaction.

Beceiro, S.; Cortina-Gil, D. [Universidade de Santiago de Compostela (Spain); Suemmerer, K. [GSI (Germany)

2010-04-26

343

Ultra-cold molecules in Coulomb crystals  

Microsoft Academic Search

Ultracold molecular hydrogen (D2+) is produced by sympathetic cooling in a linear Paul trap. With this method the translational degrees of freedom of the molecules are cooled by Coulomb interaction with laser-cooled 9Be+. This work shows that sympathetic cooling and crystallization is possible down to mass ratios of 0.45. Using molecular dynamics simulations, the mass range for sympathetic cooliing is

B. Roth; U. Frohlich; A. Ostendorf; C. Lammerzahl; S. Schiller

2003-01-01

344

Nanoplasmonic renormalization and enhancement of Coulomb interactions  

NASA Astrophysics Data System (ADS)

In this paper, we propose a general and powerful theory of the plasmonic enhancement of the many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. We illustrate this theory by computing the dressed interaction explicitly for an important example of metal dielectric nanoshells which exhibits a rich resonant behavior in magnitude and phase. This interaction is used to describe the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between nanocrystal quantum dots near a nanoshell.

Durach, M.; Rusina, A.; Klimov, V. I.; Stockman, M. I.

2008-10-01

345

Multiple Coulomb excitation experiment of 66 Zn  

NASA Astrophysics Data System (ADS)

A Coulomb excitation experiment was carried out with a 66Zn beam bombarding a {}^natPb target. Four E2 matrix elements and the quadrupole moment of the 21 + state were derived with the least-squares search code GOSIA. According to the B( E2) values, the ground band can be interpreted as a quasirotational band. It was found that the 21 + level has a positive quadrupole moment, which may be interpreted as a soft triaxial deformation.

Koizumi, M.; Seki, A.; Toh, Y.; Oshima, M.; Osa, A.; Kimura, A.; Hatsukawa, Y.; Shizuma, T.; Hayakawa, T.; Matsuda, M.; Katakura, J.; Czosnyka, T.; Sugawara, M.; Morikawa, T.; Kusakari, H.

2003-10-01

346

Coulomb excitation of 74Ge beam  

NASA Astrophysics Data System (ADS)

74Ge beam was Coulomb-excited on a natPb target. Ten E2 matrix elements including diagonal matrix elements for 5 low-lying states have been determined using the least-squares search code GOSIA. The expectation values of the rotational invariants and show the small and triaxial deformation of the two lowest members of the ground-state band , while the 02+ and 22+ states are found to be almost spherical.

Toh, Y.; Czosnyka, T.; Oshima, M.; Hayakawa, T.; Kusakari, H.; Sugawara, M.; Hatsukawa, Y.; Katakura, J.; Shinohara, N.; Matsuda, M.

347

Stretched exponential relaxation in the Coulomb glass  

Microsoft Academic Search

:   The relaxation of the specific heat and the entropy to their equilibrium values is investigated numerically for the three-dimensional\\u000a Coulomb glass at very low temperatures. The long time relaxation follows a stretched exponential function, f (t) = f\\u000a 0exp - (t\\/?)?\\u000a , with the exponent ? increasing with the temperature. The relaxation time diverges as an Arrhenius law when

A. Díaz-Sánchez; A. Pérez-Garrido

2001-01-01

348

Chaos near the Coulomb barrier. Nuclear molecules  

SciTech Connect

The present work examines in detail the classical behavior of the ..cap alpha.. + /sup 14/C and the /sup 12/C + /sup 12/C(O/sup +/) collison at energies near the Coulomb barrier. The long-time motion of the compound nuclear system is identified in terms of its classical quasiperiodic and chaotic behavior. The consequences of this motion are discussed and interpreted in terms of the evolution of the system along a dynamical energy surface. 45 references.

Strayer, M.R.

1984-01-01

349

Dynamics of fission and Coulomb explosion of multicharged large finite systems  

NASA Astrophysics Data System (ADS)

This paper reports on studies of the fragmentation dynamics of multicharged (A+)55 Morse clusters, where the variation of the range of the Morse potential parameters induces cluster fission for a long-range potential and Coulomb explosion for a short-range potential. The multidimensional energy landscapes for these fragmentation processes were explored by constructing reduced coordinates utilizing the principal component analysis (PCA), which was previously applied for the energy landscapes and folding dynamics of biomolecules. The distance-matrix based PCA was applied to study the effects of the potential on the fragmentation dynamics and to explore the structural diversity of the fragmentation processes. The first principal coordinate (which captures 95% of the dynamic information content for each trajectory) constitutes an appropriate reaction coordinate for both fission and Coulomb explosion and was used to determine the temperature-dependent fragmentation rates. These obey the Arrhenius law, with the barrier for fission (0.36 eV) being higher than for Coulomb explosion (0.22 eV). Structural and energetic information on the radius of gyration and on the potential energy for small values of the reaction coordinate manifest considerably larger fluctuations for fission than for Coulomb explosion, indicating that in the former case the cluster shrinks and swells prior to dissociation. The joint projection of multiple trajectories for each fragmentation process allows for the description of the energy landscapes and fragmentation pathways in terms of two principal coordinates, which manifest a form of 'ski slopes'. Different collective coordinates describe the spatially isotropic Coulomb explosion and the spatially unisotropic fission.

Levy, Y.; Last, I.; Jortner, J.

350

Coulomb explosion of large penetrating molecular clusters  

SciTech Connect

The main purpose of these Coulomb explosion measurements is to determine what kind of structure these and other complex molecules may have and also to determine what other special phenomena may come into play as these complex molecules pass through matter. Although the first preliminary measurements involving the Coulomb explosion of these molecules was reported at this workshop last year, the results are briefly summarized before going on to the more recent measurements obtained with a completely new kind of detector system. This new image intensifier detector system, coupled with a microcomputer, has proven to be a valuable tool in the study of the Coulomb explosion of complex molecules that penetrate matter. In the future, with some additional improvements in the system, and much better statistics for most of the molecules studied to date, it is expected that much new information will be gained about the structure of many kinds of complex molecular ions including the special effects that may be encountered when these fast molecular ions penetrate matter.

Wegner, H.E.; Thieberger, P.

1981-01-01

351

Coulomb excitation of 105Pd with protons  

NASA Astrophysics Data System (ADS)

Twelve known low-lying positive parity levels in 105Pd up to 962 keV excitation energy were investigated by measuring, in singles mode, with a high resolution 57 cm3Ge(Li) detector, the yields and angular anisotropies of the deexcitation ? rays following Coulomb excitation with 2 to 4 MeV protons. Out of the seven of these levels which have been populated for the first time through Coulomb excitation with protons, the 696.2 keV level is proposed to be Coulomb excited for the first time. Level energies, the branching ratios, the multipole mixing ratios, B(E2) and B(M1) transition probabilities, and half-lives were deduced. The angular distributions support (5/2)+, (3/2)+, (7/2)+, (5/2)+, and (3/2)+ spin-parity assignments, for the 560.6, 673.2, 696.2, 781.8, and 961.9 keV levels, respectively. The present results have been discussed in view of the existing experimental data, as well as in terms of various core-particle coupling models.

Tayal, D. C.; Singh, K. P.; Mittal, V. K.; Singh, Gulzar; Hans, H. S.

1985-12-01

352

Coulomb Oscillations in Partially Open Quantum Dots  

NASA Astrophysics Data System (ADS)

Coulomb blockade conductance oscillations in quantum dots are ordinarily observed with weak dot-to-lead tunneling. Recent theoryfootnote A. Furusaki and K.A. Matveev, Phys. Rev. Lett. 75 (1995), 709. examines the effect of strong tunneling on Coulomb oscillations. We have measured the zero magnetic field conductance through a 500 × 800 nm^2 quantum dot connected to leads through tunable tunnel barriers, defined in a high mobility near-surface two-dimensional electron gas by four independently tunable split gates on a GaAs/AlGaAs heterostructure. We set the conductance of one barrier much less than e^2/h and vary the conductance of the other (G_open) between e^2/h and 6e^2/h. We observe well-defined Coulomb oscillations at 50 mK for the entire range of G_open, except when G_open ? 2e^2/h, where the oscillations are suppressed. The temperature at which the oscillations disappear decreases with increasing G_open; for G_ open>2e^2/h, the oscillations are suppressed at temperatures above the single-particle level spacing.

Crouch, C. H.; Livermore, C.; Westervelt, R. M.; Campman, K. L.; Gossard, A. C.

1996-03-01

353

Diquonia and potential models  

Microsoft Academic Search

We present four new quark-quark potentials, developed in the framework of the nonrelativistic quark model (NRQM), which can reproduce quite well the spectra of mesons and baryons. They contain a central part which is of type “Coulomb+linear” or “Coulomb +2\\/3-power”, and a strong but smooth hyperfine term. With these four potentials and the one proposed by Bhaduri et al., we

C. Semay; B. Silvestre-Brac

1994-01-01

354

Singular potentials with short range  

Microsoft Academic Search

Summary  Previous works have shown the properties and the possibility of useful approximate methods for the Jost functions, and the\\u000a radial wave functions in the case of Yukawa generalized potentials, less or equally singular than the centrifugal term. Here\\u000a we extend some of these results to a larger class of short-range potentials which, near the origin, can be represented as\\u000a a

H. Cornille; Enrico Predazzi

1965-01-01

355

New type of cross section singularity in backward scattering: the Coulomb glory  

SciTech Connect

For classical scattering by a central potential that exhibits Coulomb behavior (i.e., that is attractive) at small distances, the scattering angle theta tends to ..pi.. as the orbital angular momentum L decreases. The differential cross section for scattering through angles close to ..pi.. can be characterized by the power series expansion of the difference theta(L)--..pi.. in small L, only odd powers of L being present in this expansion. Expressions are found for the coefficients in the linear (c/sub 1/) and cubic (c/sub 3/): in L: terms. It is shown that, for a broad class of screened Coulomb potentials, the coefficient c/sub 1/ vanishes at some value of the collision energy E/sub 0/. At the energy E = E/sub 0/ the classical cross section diverges in the case of backward scattering (the Coulomb glory); in wave mechanics the cross section possesses a maximum. The behavior of the cross section for energies close to E/sub 0/ is computed. The application of the theory to electron scattering by atoms, in which the Coulomb interaction at small distances is determined by the interaction with the nucleus (charge Z) and E/sub 0/ = 0.0103Z/sup 4//sup ///sup 3/ keV, is discussed.

Demkov, Y.N.; Ostrovskii, V.N.; Tel'nov, D.A.

1984-02-01

356

Solitonic lattice and Yukawa forces in the rare-earth orthoferrite TbFeO3.  

PubMed

The random fluctuations of spins give rise to many interesting physical phenomena, such as the 'order-from-disorder' arising in frustrated magnets and unconventional Cooper pairing in magnetic superconductors. Here we show that the exchange of spin waves between extended topological defects, such as domain walls, can result in novel magnetic states. We report the discovery of an unusual incommensurate phase in the orthoferrite TbFeO(3) using neutron diffraction under an applied magnetic field. The magnetic modulation has a very long period of 340?Å at 3?K and exhibits an anomalously large number of higher-order harmonics. These domain walls are formed by Ising-like Tb spins. They interact by exchanging magnons propagating through the Fe magnetic sublattice. The resulting force between the domain walls has a rather long range that determines the period of the incommensurate state and is analogous to the pion-mediated Yukawa interaction between protons and neutrons in nuclei. PMID:22728320

Artyukhin, Sergey; Mostovoy, Maxim; Jensen, Niels Paduraru; Le, Duc; Prokes, Karel; de Paula, Vinícius G; Bordallo, Heloisa N; Maljuk, Andrey; Landsgesell, Sven; Ryll, Hanjo; Klemke, Bastian; Paeckel, Sebastian; Kiefer, Klaus; Lefmann, Kim; Kuhn, Luise Theil; Argyriou, Dimitri N

2012-06-24

357

Solitonic lattice and Yukawa forces in the rare-earth orthoferrite TbFeO3  

NASA Astrophysics Data System (ADS)

The random fluctuations of spins give rise to many interesting physical phenomena, such as the ‘order-from-disorder’ arising in frustrated magnets and unconventional Cooper pairing in magnetic superconductors. Here we show that the exchange of spin waves between extended topological defects, such as domain walls, can result in novel magnetic states. We report the discovery of an unusual incommensurate phase in the orthoferrite TbFeO3 using neutron diffraction under an applied magnetic field. The magnetic modulation has a very long period of 340?Å at 3?K and exhibits an anomalously large number of higher-order harmonics. These domain walls are formed by Ising-like Tb spins. They interact by exchanging magnons propagating through the Fe magnetic sublattice. The resulting force between the domain walls has a rather long range that determines the period of the incommensurate state and is analogous to the pion-mediated Yukawa interaction between protons and neutrons in nuclei.

Artyukhin, Sergey; Mostovoy, Maxim; Jensen, Niels Paduraru; Le, Duc; Prokes, Karel; de Paula, Vinícius G.; Bordallo, Heloisa N.; Maljuk, Andrey; Landsgesell, Sven; Ryll, Hanjo; Klemke, Bastian; Paeckel, Sebastian; Kiefer, Klaus; Lefmann, Kim; Kuhn, Luise Theil; Argyriou, Dimitri N.

2012-08-01

358

Four-zero neutrino Yukawa textures in the minimal seesaw framework  

SciTech Connect

We investigate, within the type I seesaw framework, the physical implications of zero textures in the Yukawa couplings which generate the neutrino Dirac mass matrix m{sub D}. It is shown that four is the maximal number of texture zeros compatible with the observed leptonic mixing and the assumption that no neutrino mass vanishes. We classify all allowed four-zero textures of m{sub D} into two categories with three classes each. We show that the different classes, in general, admit CP violation both at low and high energies. We further present the constraints obtained for low energy physics in each case. The role of these zero textures in establishing a connection between leptogenesis and low energy data is analyzed in detail. It is shown that it is possible in all cases to completely specify the parameters relevant for leptogenesis in terms of light neutrino masses and leptonic mixing together with the unknown heavy neutrino masses.

Branco, Gustavo C.; Emmanuel-Costa, David [Departamento de Fisica and Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico (IST), Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); Rebelo, M. N. [Departamento de Fisica and Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico (IST), Avenida Rovisco Pais, 1049-001 Lisboa (Portugal); CERN, Department of Physics, Theory Division, CH-1211 Geneva 23 (Switzerland); Roy, Probir [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India); Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata 700 064 (India)

2008-03-01

359

Cutoff wave number for shear waves and Maxwell relaxation time in Yukawa liquids.  

PubMed

Because liquids cannot resist shear except over very short distances comparable to the atomic spacing, shear sound waves (i.e., transverse phonons) propagate only for very short wavelengths. A measure of this limit is the cutoff wave number k(c), which is sometimes called the critical wave number. Previously k(c) was determined in molecular dynamics (MD) simulations by obtaining the dispersion relation. Another approach is developed in this paper by identifying the wave number at the onset of a negative peak in the transverse current correlation function. This method is demonstrated using a three-dimensional MD simulation of a Yukawa fluid, which mimics dusty plasmas. In general, k(c) is an indicator of conditions where elastic and dissipative effects are approximately balanced. Additionally, the crossover frequency for the real and imaginary terms of the complex viscosity of a dusty plasma is obtained; this crossover frequency corresponds to the Maxwell relaxation time. PMID:23005223

Goree, J; Donkó, Z; Hartmann, P

2012-06-11

360

Absence of Rapid Proton Decay and Origin of Low-Energy Particlesand Yukawa Couplings  

SciTech Connect

In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that ({bar D},L) are different from {bar H}({bar 5}) in their origins. In this article, we consider a possibility that they come from different irreducible components in g/h. Requiring that all the Yukawa coupling constants of quarks and leptons be generated from the super Yang-Mills interactions of G, we found in the context of Georgi-Glashow H = SU(5) unification that the minimal choice of G is E{sub 7} and E{sub 8} is the only alternative. This idea is systematically implemented in Heterotic String, M theory and F theory, confirming the absence of dimension 4 proton decay operators. Not only H = SU(5) but also G constrain operators of effective field theories, providing non-trivial information.

Tatar, Radu; Watari, Taizan

2006-01-01

361

Putting Yukawa-Like Modified Gravity (MOG) on the Test in the Solar System  

NASA Astrophysics Data System (ADS)

We deal with a Yukawa-like long-range modified model of gravity (MOG) which recently allowed to successfully accommodate many astrophysical and cosmological features without resorting to dark matter. On Solar System scales, MOG predicts anomalous retrograde secular precessions of the planetary longitudes of the perihelia ?. Their existence has been put on the test here by taking the ratios of the observationally estimated Pitjeva's corrections to the standard Newtonian/ Einsteinian perihelion precessions for different pairs of planets. It turns out that MOG, in the present form which turned out to be phenomenologically successful on astrophysical scales, is ruled out at more than 3? level in the Solar System. If and when other teams of astronomers will independently estimate their own corrections to the usual precessions of the perihelia, it will be possible to repeat such a test.

Iorio, Lorenzo

2008-11-01

362

Mixed Axion/Axino Dark Matter in mSUGRA and Yukawa-unified SUSY  

NASA Astrophysics Data System (ADS)

Axion/axino dark matter (DM) is explored in the minimal supergravity (mSUGRA) and Yukawa-unified supersymmetric grand-unified theory (SUSY GUT) models with surprising results. For this type of scenario, relic DM abundance has three components: i.) cold axions, ii.) warm axinos from neutralino decay, and iii.) cold or warm thermally produced axinos. Reheat temperatures TR exceeding 106 GeV are required in order to solve the gravitino/Big Bang Nucleosynthesis (BBN) problem while also allowing for baryogensis via non-thermal leptogenesis. In order to attain high enough reheat temperatures, we also need high values of the Peccei-Quinn (PQ) breaking scale fa on the order 1011-1012 GeV.

Summy, Heaya Ann

2010-02-01

363

Mixed Axion/Axino Dark Matter in mSUGRA and Yukawa-unified SUSY  

SciTech Connect

Axion/axino dark matter (DM) is explored in the minimal supergravity (mSUGRA) and Yukawa-unified supersymmetric grand-unified theory (SUSY GUT) models with surprising results. For this type of scenario, relic DM abundance has three components: i.) cold axions, ii.) warm axinos from neutralino decay, and iii.) cold or warm thermally produced axinos. Reheat temperatures T{sub R} exceeding 10{sup 6} GeV are required in order to solve the gravitino/Big Bang Nucleosynthesis (BBN) problem while also allowing for baryogensis via non-thermal leptogenesis. In order to attain high enough reheat temperatures, we also need high values of the Peccei-Quinn (PQ) breaking scale f{sub a} on the order 10{sup 11}-10{sup 12} GeV.

Ann Summy, Heaya [Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

2010-02-10

364

Proton decay, Yukawa couplings and underlying gauge symmetry in string theory  

NASA Astrophysics Data System (ADS)

In string theory, massless particles often originate from a symmetry breaking of a large gauge symmetry G to its subgroup H. The absence of dimension-4 proton decay in supersymmetric theories suggests that (D¯,L) are different from H¯(5¯) in their origins. In this article, we consider a possibility that they come from different irreducible components in g/h. Requiring that all the Yukawa coupling constants of quarks and leptons be generated from the super-Yang Mills interactions of G, we found in the context of Georgi Glashow H=SU(5) unification that the minimal choice of G is E and E is the only alternative. This idea is systematically implemented in heterotic String, M theory and F theory, confirming the absence of dimension 4 proton decay operators. Not only H=SU(5) but also G constrain operators of effective field theories, providing non-trivial information.

Tatar, Radu; Watari, Taizan

2006-07-01

365

Self-adjoint extensions of Coulomb systems in 1, 2 and 3 dimensions  

SciTech Connect

We study the nonrelativistic quantum Coulomb hamiltonian (i.e., inverse of distance potential) in R{sup n}, n=1,2,3. We characterize their self-adjoint extensions and, in the unidimensional case, present a discussion of controversies in the literature, particularly the question of the permeability of the origin. Potentials given by fundamental solutions of Laplace equation are also briefly considered.

Oliveira, Cesar R. de [Departamento de Matematica-UFSCar, Cx. P. 676, 13560-970 Sao Carlos, SP (Brazil)], E-mail: oliveira@dm.ufscar.br; Verri, Alessandra A. [Departamento de Matematica-UFSCar, Cx. P. 676, 13560-970 Sao Carlos, SP (Brazil)], E-mail: alessandraverri@yahoo.com.br

2009-02-15

366

Confining solution of the Dyson-Schwinger equations in Coulomb gauge  

SciTech Connect

The Dyson-Schwinger equations arising from minimizing the vacuum energy density in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge are solved numerically. A new solution is presented which gives rise to a strictly linearly rising static quark potential and whose existence was previously observed in the infrared analysis of the Dyson-Schwinger equations. For the new solution we also present the static quark potential and calculate the running coupling constant from the ghost-gluon vertex.

Epple, D.; Reinhardt, H.; Schleifenbaum, W. [Institut fuer Theoretische Physik, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2007-02-15

367

alpha-particle nuclear surface absorption below the Coulomb barrier in heavy nuclei  

Microsoft Academic Search

An analysis of all available alpha-particle-induced reaction cross sections on nuclei within the mass number range 121<=A<=197, below the Coulomb barrier, is carried out. This analysis leads to an optical potential that describes the alpha-particle elastic scattering at low energies as well and both elastic-scattering and reaction data for 45<=A<=124. The energy dependence of the surface imaginary potential depth is

M. Avrigeanu; V. Avrigeanu

2010-01-01

368

BRIEF COMMUNICATION: A note on the Coulomb collision operator in curvilinear coordinates  

NASA Astrophysics Data System (ADS)

The dynamic friction force, diffusion tensor, flux density in velocity space and Coulomb collision term are expressed in curvilinear coordinates via Trubnikov potential functions corresponding to each species of a background plasma. For comparison, explicit formulae are given for the dynamic friction force, diffusion tensor and collisional flux density in velocity space in curvilinear coordinates via Rosenbluth potential functions summed over all species of the background plasma.

Goncharov, P. R.

2010-10-01

369

Perturbation theory in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge  

SciTech Connect

We study the Hamiltonian approach to Yang-Mills theory in Coulomb gauge in Rayleigh-Schroedinger perturbation theory. The static gluon and ghost propagator as well as the potential between static color sources are calculated to one-loop order. Furthermore, the one-loop {beta} function is calculated from both the ghost-gluon vertex and the static potential and found to agree with the result of covariant perturbation theory.

Campagnari, Davide R.; Reinhardt, Hugo; Weber, Axel [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany); Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria, A. Postal 2-82, 58040 Morelia, Michoacan (Mexico)

2009-07-15

370

Fractal Tomlinson model for mesoscopic friction: From microscopic velocity-dependent damping to macroscopic Coulomb friction  

NASA Astrophysics Data System (ADS)

A modified Tomlinson equation with fractal potential is studied. The effective potential is numerically generated and its mesoscopic structure is gradually adjusted to different scales by a number of Fourier modes. It is shown that with the change of scale the intensity of velocity-dependent damping in an effective Langevin equation can be gradually substituted by an equivalent constant “dry friction.” For smooth macrosopic surfaces the effective equation completely reduces to the well known Coulomb law.

Filippov, A. E.; Popov, V. L.

2007-02-01

371

Network Forming Fluids: Yukawa Square-Well m-Point Model  

NASA Astrophysics Data System (ADS)

Thermal and connectivity properties of the Yukawa square-well m-point (YSWmP) model of the network forming fluid are studied using solution of the multidensity Ornstein-Zernike and connectedness Ornstein-Zernike equations supplemented by the associative mean spherical approximation (AMSA). The model is represented by the multicomponent mixture of Yukawa hard spheres with msa square-well sites, located on the surface of each hard sphere. To validate the accuracy of the theory, computer simulation is used to calculate the structure, thermodynamic and connectivity properties of the one-component YSW4P version of the model which is compared against corresponding theoretical data. In addition, connectivity properties of the model were studied using Flory-Stockmayer (FS) theory. Predictions of the AMSA for the thermal properties of the model (radial distribution functions (RDF), internal energy, pressure, fractions of the particles in different bonding states) are in good agreement with computer simulation predictions. Similarly, good agreement was found for the connectedness RDF (CRDF), except for the statepoints located close to the percolation threshold, where the theory fails to reproduce the long-range behavior of the CRDF. Results of both theories (AMSA and FS) for the mean cluster size are reasonably accurate only at low degrees of association. Predictions of the FS theory for the percolation lines are in a good agreement with computer simulation predictions. AMSA predictions of percolation are much less accurate, where corresponding percolation lines are located at a temperatures approximately 25% lower then those calculated using computer simulation.

Kalyuzhnyi, Y. V.; Iacovella, C. R.; Docherty, H.; Holovko, M.; Cummings, P. T.

2011-10-01

372

Generalized quantum mechanical two-Coulomb-center problem (Demkov problem)  

NASA Astrophysics Data System (ADS)

We present a new exactly solvable quantum problem for which the Schrödinger equation allows for separation of variables in oblate spheroidal coordinates. Namely, this is the quantum mechanical two-Coulomb-center problem for the case of an imaginary intercenter parameter and complex conjugate charges are considered. Since the potential is defined by the two-sheeted mapping whose singularities are concentrated on a circle rather than at separate points, there arise additional possibilities in the choice of boundary conditions. A detailed classification of the various types of boundary-value problems is given. The quasi-radial equation leads to a new type of boundary value problem which has never been considered before. Results of the numerical calculations, which allow conclusions to be drawn about the structure of the energy spectrum, are shown. Possible physical applications are discussed.

M. Puchkov, A.; V. Kozedub, A.; O. Bodnia, E.

2013-09-01

373

Strong nuclear couplings as a source of Coulomb rainbow suppression  

NASA Astrophysics Data System (ADS)

A recent measurement of the Be11+Zn64 quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to He6+Zn64 elastic scattering but similar to that for the elastic scattering of He6 from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of Be11 is caused by the much greater importance of nuclear coupling to the continuum in Be11 compared to He6, where Coulomb dipole coupling is mainly responsible for the non-Fresnel-like shape, when present. We also show that the dynamic polarization potentials derived from the CDCC calculations seem to follow a universal form as a function of radius.

Keeley, N.; Alamanos, N.; Kemper, K. W.; Rusek, K.

2010-09-01

374

Coulomb asymmetry in strong field multielectron ionization of diatomic molecules.  

PubMed

We measure the angular distribution of an electron emitted by a strong elliptically polarized two-color laser field from exploding doubly charged molecular nitrogen. This angular distribution is vastly different for emission of the electron from the up-field core of the molecule as compared to that from the down-field core. The emission from the down-field core leads to a slight rotation with respect to the internuclear axis in the direction expected by the Coulomb effect of the remaining ion, while, for the emission from the up-field core, this direction is inversed. Our semiclassical simulations suggest that this unexpected angular distribution is caused by an initial longitudinal momentum of the electron freed by over-the-barrier ionization above the inner barrier in the molecule. The initial kinetic energy is in the range of the potential energy of the Stark-shifted orbital above the barrier. PMID:22400834

Wu, J; Meckel, M; Voss, S; Sann, H; Kunitski, M; Schmidt, L Ph H; Czasch, A; Kim, H; Jahnke, T; Dörner, R

2012-01-24

375

Multiple coulomb excitation of 167Er  

Microsoft Academic Search

The ground-state rotational band in 167Er has been investigated through multiple Coulomb excitation with a 160 MeV 35Cl beam. Excited states up to 25\\/2+ were established by measuring gammagamma coincidences and gamma-ray angular distributions. Gamma-gamma angular correlations were also measured. Nuclear lifetimes of levels up to spin 23\\/2 have been determined from Doppler-broadened gamma-ray lineshapes, and B(M1) and B(E2) values

Masumi Ohshima; Eisuke Minehara; Mitsuhiko Ishii; Takashi Inamura; Akira Hashizume

1985-01-01

376

Quenching molecular photodissociation by intermolecular Coulombic decay  

NASA Astrophysics Data System (ADS)

In this paper we study the impact of interatomic Coulombic decay (ICD) on molecular photodissociation. The investigation reveals the hitherto unrecognized ability of ICD to quench processes involving nuclear rearrangements. Numerical computations of the nuclear dynamics, initiated by photoexciting the B1?+ Rydberg state of CO in CO.Mg complexes, are carried out. The efficiencies of ICD and photoinduced predissociation are compared for the four lowest vibrational levels of the corresponding electronic state. We also show the impact of CO vibrations on the ICD electron spectrum. Finally, we discuss the growing efficiency of ICD to quench the dissociation as the number of neighboring Mg atoms is increased.

Kopelke, S.; Chiang, Y.-C.; Gokhberg, K.; Cederbaum, L. S.

2012-07-01

377

Mathematical structure of relativistic Coulomb integrals  

SciTech Connect

We show that the diagonal matrix elements , where O=(1,{beta},i{alpha}n{beta}) are the standard Dirac matrix operators and the angular brackets denote the quantum-mechanical average for the relativistic Coulomb problem, may be considered as difference analogs of the radial wave functions. Such structure provides an independent way of obtaining closed forms of these matrix elements by elementary methods of the theory of difference equations without explicit evaluation of the integrals. Three-term recurrence relations for each of these expectation values are derived as a by-product. Transformation formulas for the corresponding generalized hypergeometric series are discussed.

Suslov, Sergei K. [School of Mathematical and Statistical Sciences and Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, Arizona 85287-1804 (United States)

2010-03-15

378

Capacitance enhancement in Coulomb blockade tunnel barriers  

NASA Astrophysics Data System (ADS)

We study the capacitance of tunnel barriers in well-controlled, very small, silicon single-electron transistors. We observe a decrease of the charging energy of the Coulomb island as the quantum dot is filled from a few to more than 200 electrons. Since the gate capacitance in our devices is, in average, constant all over this electron-density range, we can attribute the observed variation to the source and drain capacitances, made of a doped semiconductor. The capacitance data can be translated into a variation of the electronic polarizability and localization length, in excellent agreement with an independent and simultaneous estimation based on the conductance.

Hofheinz, M.; Jehl, X.; Sanquer, M.; Molas, G.; Vinet, M.; Deleonibus, S.

2007-06-01

379

Coulomb Repulsion in Miniature Ion Mobility Spectrometry  

SciTech Connect

We have undertaken a study of ion mobility resolution in a miniature ion mobility spectrometer with a drift channel 1.7 mm in diameter and 35 mm in length. The device attained a maximum resolution of 14 in separating ions of NO, O{sub 2}, and methyl iodine. The ions were generated by pulses from a frequency-quadrupled Nd:YAG laser. Broadening due to Coulomb repulsion was modeled theoretically and shown experimentally to have a major effect on the resolution of the miniature device.

Xu, J.; Whitten, W.B.; Ramsey, J.M.

1999-08-08

380

Multifractality at Anderson Transitions with Coulomb Interaction  

NASA Astrophysics Data System (ADS)

We explore mesoscopic fluctuations and correlations of the local density of states (LDOS) near localization transition in a disordered interacting electronic system. It is shown that the LDOS multifractality survives in the presence of the Coulomb interaction. We calculate the spectrum of multifractal dimensions in 2+? spatial dimensions and show that it differs from that in the absence of interaction. The multifractal character of fluctuations and correlations of the LDOS can be studied experimentally by scanning tunneling microscopy of two-dimensional and three-dimensional disordered structures.

Burmistrov, I. S.; Gornyi, I. V.; Mirlin, A. D.

2013-08-01

381

Reaction mechanisms involving weakly bound {sup 6}Li and {sup 209}Bi at energies near the Coulomb barrier  

SciTech Connect

The elastic, inelastic, and transfer cross sections are measured for the {sup 6}Li+{sup 209}Bi reaction at energies around the Coulomb barrier. The optical model analysis of elastic scattering shows a breakup threshold anomaly in the energy dependence of the real and imaginary potentials. The observed energy dependence is found to be consistent with the dynamic polarization potential obtained from the coupled-channels calculations that explain the above measured reaction channels simultaneously. A comparison of different reaction probabilities reveals that the relative contribution of breakup starts increasing at energies below the Coulomb barrier, in contrast to the behavior of other reaction channels, which get closed as energy is lowered. The large probability of projectile breakup at sub-Coulomb energies leads to the observation of a nonzero imaginary potential even at E{sub lab}{<=}0.8V{sub B}.

Santra, S.; Kailas, S.; Ramachandran, K.; Parkar, V. V.; Jha, V.; Roy, B. J.; Shukla, P. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2011-03-15

382

Approximate 3-body Coulomb corrections for HBT interferometry  

SciTech Connect

We have used solutions to the quantum continuum 3-body Coulomb problem in the limits of high and low relative momentum to examine {open_quotes}candidate{close_quotes} corrections for Coulomb interactions in three pion Hanbury-Brown-Twiss interferometry. We suggest this new form of 3-body Coulomb where G({eta}{sub ij}) is a Gamow penetrability, {eta}{sub ij} is the Sommerfeld parameter, and C is an arbitrary constant assigned a value of 1.0. We compare this form with Monte Carlo calculations of 3-particle correlation functions using approximate symmetrized 3-particle Coulomb wave functions.

Cramer, J.G.; Efimov, V.; Sacksteder, V.E. IV

1993-10-01

383

Evaluation of Certain Radial Coulomb Integrals Using Symmetry Properties of the Coulomb Field.  

National Technical Information Service (NTIS)

The symmetry properties of the nonrelativistic Coulomb field problem allow one to construct an operator calculus for evaluating matrix elements of the multipole operator r sup(-q). By means of this operator calculus an explanation is given for the vanishi...

L. C. Biedenharn N. V. V. J. Swamy R. K. Kulkarni

1969-01-01

384

Oscillator-Morse-Coulomb mappings and algebras for constant or position-dependent mass  

SciTech Connect

The bound-state solutions and the su(1,1) description of the d-dimensional radial harmonic oscillator, the Morse, and the D-dimensional radial Coulomb Schroedinger equations are reviewed in a unified way using the point canonical transformation method. It is established that the spectrum generating su(1,1) algebra for the first problem is converted into a potential algebra for the remaining two. This analysis is then extended to Schroedinger equations containing some position-dependent mass. The deformed su(1,1) construction recently achieved for a d-dimensional radial harmonic oscillator is easily extended to the Morse and Coulomb potentials. In the last two cases, the equivalence between the resulting deformed su(1,1) potential algebra approach and a previous deformed shape invariance one generalizes to a position-dependent mass background a well-known relationship in the context of constant mass.

Quesne, C. [Physique Nucleaire Theorique et Physique Mathematique, Universite Libre de Bruxelles, Campus de la Plaine, CP 229, Boulevard du Triomphe, B-1050 Brussels (Belgium)

2008-02-15

385

Transport Through a Coulomb Blockaded Majorana Nanowire  

NASA Astrophysics Data System (ADS)

In one-dimensional (1D) quantum wires with strong spin-orbit coupling and a Zeeman field, a superconducting substrate can induce zero-energy Majorana bound states located near the ends of the wire. We study electronic properties when such a wire is contacted by normal metallic or superconducting electrodes. A special attention is devoted to Coulomb blockade effects. We analyze the "Majorana single-charge transistor" (MSCT), i.e., a floating Majorana wire contacted by normal metallic source and drain contacts, where charging effects are important. We describe Coulomb oscillations in this system and predict that Majorana fermions could be unambiguously detected by the emergence of sideband peaks in the nonlinear differential conductance. We also study a superconducting variant of the MSCT setup with s-wave superconducting (instead of normal-conducting) leads. In the noninteracting case, we derive the exact current-phase relation (CPR) and find ?-periodic behavior with negative critical current for weak tunnel couplings. Charging effects then cause the anomalous CPR I(\\varphi ) = Ic\\cos \\varphi, where the parity-sensitive critical current I c provides a signature for Majorana states.

Zazunov, Alex; Egger, Reinhold; Yeyati, Alfredo Levy; Hützen, Roland; Braunecker, Bernd

386

Distorted Coulomb field of the scattered electron  

SciTech Connect

Experimental results for the radiation emission from ultrarelativistic electrons in targets of 0.03%-5% radiation length is presented. For the thinnest targets, the radiation emission is in accordance with the Bethe-Heitler formulation of bremsstrahlung, the target acting as a single scatterer. In this regime, the radiation intensity is proportional to the thickness. As the thickness increases, the distorted Coulomb field of the electron that is the result of the first scattering events, leads to a suppressed radiation emission per interaction, upon subsequent scattering events. In that case, the radiation intensity becomes proportional to a logarithmic function of the thickness, due to the suppression. Eventually, once the target becomes sufficiently thick, the entire radiation process becomes influenced by multiple scattering and the radiation intensity is again proportional to the thickness, but with a different constant of proportionality. The observed logarithmic thickness dependence of radiation intensity at intermediate values of the thickness can be directly interpreted as a manifestation of the distortion of the electron Coulomb field resulting from a scattering event. The Landau-Pomeranchuk-Migdal effect is explored with high primary energy using materials with low nuclear charge (Z). Also, targets that should give rise to the claimed interference effect in high-energy radiation emission from a structured target of thin foils are investigated.

Thomsen, H. D.; Esberg, J.; Andersen, K. K.; Lund, M. D.; Knudsen, H.; Uggerhoej, U. I. [Department of Physics and Astronomy, University of Aarhus (Denmark); Sona, P. [University of Florence, Florence (Italy); Mangiarotti, A. [Universidade de Coimbra (Portugal); Ketel, T. J. [Free University, Amsterdam (Netherlands); Dizdar, A. [University of Istanbul, Istanbul (Turkey); Ballestrero, S.; Connell, S. H. [University of Johannesburg, Johannesburg (South Africa)

2010-03-01

387

Positive and negative Coulomb drag in vertically integrated one-dimensional quantum wires  

NASA Astrophysics Data System (ADS)

Electron interactions in and between wires become increasingly complex and important as circuits are scaled to nanometre sizes, or use reduced-dimensional conductors such as carbon nanotubes, nanowires and gated high-mobility two-dimensional electron systems. This is because the screening of the long-range Coulomb potential of individual carriers is weakened in these systems, which can lead to phenomena such as Coulomb drag, where a current in one wire induces a voltage in a second wire through Coulomb interactions alone. Previous experiments have demonstrated Coulomb electron drag in wires separated by a soft electrostatic barrier of width >~80 nm (ref. 12), which was interpreted as resulting entirely from momentum transfer. Here, we measure both positive and negative drag between adjacent vertical quantum wires that are separated by ~15 nm and have independent contacts, which allows their electron densities to be tuned independently. We map out the drag signal versus the number of electron sub-bands occupied in each wire, and interpret the results both in terms of momentum-transfer and charge-fluctuation induced transport models. For wires of significantly different sub-band occupancies, the positive drag effect can be as large as 25%.

Laroche, D.; Gervais, G.; Lilly, M. P.; Reno, J. L.

2011-12-01

388

Effective Coulomb Barriers for Charged-Particle-Induced Nuclear Reactions.  

National Technical Information Service (NTIS)

Values for the effective Coulomb barrier were obtained from experimental excitations for p, d, exp 3 He and alpha reactions. The dependence of the effective Coulomb barrier on the proton number of the target nuclide can be described satisfactorily with th...

H. Muenzel

1978-01-01

389

Structure and reactions at Coulomb-barrier energies  

Microsoft Academic Search

A variety of nuclear reactions at energies close to the Coulomb barrier are used to populate residual nuclei in order to study their structure through methods such as ?-ray spectroscopy. The most common of these is the fusion-evaporation reaction. Recent detailed studies of heavy-ion fusion have shown how this reaction proceeds not through a single Coulomb barrier but through a

Neil Rowley

1998-01-01

390

The Effect of coulomb friction and stiction on force control  

Microsoft Academic Search

We have studied the effect of Coulomb friction and stiction on force control with integral feedback. The force is applied through a compliant transmission by a velocity-controlled motor. Our results show that stiction can cause the applied force to enter a limit cycle. Coulomb friction can extend the system stability bounds but may lead to an input-dependent stability. Under certain

William T. Townsend

1987-01-01

391

Interplay of Coulomb and electron-phonon interactions in graphene  

Microsoft Academic Search

We consider mutual effect of the electron-phonon and strong Coulomb\\u000ainteractions on each other by summing up leading logarithmic corrections via\\u000athe renormalization group approach. We find that the Coulomb interaction\\u000aenhances electron coupling to the intervalley A1 optical phonons, but not to\\u000athe intravalley E2 phonons.

D. M. Basko; I. L. Aleiner

2008-01-01

392

The Coulomb relaxation of the photoelectron spectrum fine structure  

Microsoft Academic Search

The Coulomb relaxation of fine structure in photoelectron spectra is studied and the scope of applicability of the Landau collision integral is determined. It is shown that in using the Landau collision integral an upper cut-off of large scattering angles is required, which reduces the Coulomb logarithm value by 20-22 percent. The decrease of the logarithm is comparable in magnitude

Iu. V. Konikov; G. V. Khazanov

1985-01-01

393

Quantum Dynamics of Biological Plasma in the External Coulomb Field  

NASA Astrophysics Data System (ADS)

A quantum solution to the truncated Fisher-Kolmogorov-Petrovskii-Piskunov equation with Coulomb convection and linear diffusion is derived. The quantum radiation of biological systems, individual microorganisms (cells, bacteria), and dust plasma particles in the Coulomb field is studied using the foregoing solution.

Lasukov, V. V.; Lasukova, T. V.; Lasukova, O. V.

2013-10-01

394

Postacceleration effects in the Coulomb dissociation of neutron halo nuclei  

Microsoft Academic Search

We study the breakup of one-neutron halo nuclei in the Coulomb field of a target nucleus. In the post-form distorted wave Born approximation theory of this reaction, with only Coulomb distortions in the entrance and outgoing channels, an analytic solution for the breakup T matrix is known. We study this T matrix and the corresponding cross sections numerically. This formula

Prabir Banerjee; Gerhard Baur; Kai Hencken; Radhey Shyam; Dirk Trautmann

2002-01-01

395

Known-to-Unknown Approach to Teach about Coulomb's Law  

ERIC Educational Resources Information Center

|Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to…

Thamburaj, P. K.

2007-01-01

396

Parabolic sturmians approach to the three-body continuum Coulomb problem  

NASA Astrophysics Data System (ADS)

The three-body continuum Coulomb problem is treated in terms of the generalized parabolic coordinates. Approximate solutions are expressed in the form of a Lippmann-Schwinger-type equation, where the Green's function includes the leading term of the kinetic energy and the total potential energy, whereas the potential contains the non-orthogonal part of the kinetic energy operator. As a test of this approach, the integral equation for the ( e -, e -, He++) system has been solved numerically by using the parabolic Sturmian basis representation of the (approximate) potential. Convergence of the expansion coefficients of the solution has been obtained as the basis set used to describe the potential is enlarged.

Zaytsev, S. A.; Popov, Yu. V.; Piraux, B.

2013-03-01

397

The Coulomb branch of the Leigh-Strassler deformation and matrix models  

NASA Astrophysics Data System (ADS)

The Dijkgraaf-Vafa approach is used in order to study the Coulomb branch of the Leigh-Strassler massive deformation of N=4 SYM with gauge group U(N). The theory has N=1 SUSY and an N-dimensional Coulomb branch of vacua, which can be described by a family of ``generalized'' Seiberg-Witten curves. The matrix model analysis is performed by adding a tree level potential that selects particular vacua. The family of curves is found: it consists of order N branched coverings of a base torus, and it is described by multi-valued functions on the latter. The relation between the potential and the vacuum is made explicit. The gauge group SU(N) is also considered. Finally the resolvents from which expectation values of chiral operators can be extracted are presented.

Francesco, Benini

2004-12-01

398

Modification of Coulomb law and energy levels of the hydrogen atom in a superstrong magnetic field  

NASA Astrophysics Data System (ADS)

We obtain the following analytical formula which describes the dependence of the electric potential of a pointlike charge on the distance away from it in the direction of an external magnetic field B: ?(z)=e/|z|[1-exp?(-6me2|z|)+exp?(-(2/?)e3B+6me2|z|)]. The deviation from Coulomb’s law becomes essential for B>3?Bcr/?=3?me2/e3?6×1016G. In such superstrong fields, electrons are ultrarelativistic except those which occupy the lowest Landau level (LLL) and which have the energy ?02=me2+pz2. The energy spectrum on which LLL splits in the presence of the atomic nucleus is found analytically. For B>3?Bcr/? it differs substantially from the one obtained without accounting for the modification of the atomic potential.

Machet, B.; Vysotsky, M. I.

2011-01-01

399

Yukawa corrections to the charged Higgs boson production in association with the top quark at hadron colliders  

Microsoft Academic Search

We calculate the Yukawa corrections of order O(alpha_{{ew}}m_{t(b)}2\\/mW2) to charged Higgs boson production in association with a top quark at the Tevatron and the LHC. The corrections are not very sensitive to the mass of the charged Higgs boson and can exceed -20% for low values of tanbeta, where the contribution of the top quark is large, and high values

L. G. Jin; C. S. Li; R. J. Oakes; S. H. Zhu

2000-01-01

400

Analytic Coulomb approximations for dynamic multipole polarizabilities and dispersion forces  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive and unified treatment of atomic multipole oscillator strengths, dynamic multipole polarizabilities, and dispersion force constants in a variety of Coulomb-like approximations. A theoretically and computationally superior modification of the original Bates-Damgaard (BD) procedure, referred to here simply as the Coulomb approximation (CA), is introduced. An analytic expression for the dynamic multipole polarizability is found which contains as special cases this quantity within the CA, the extended Coulomb approximation (ECA) of Adelman and Szabo, and the quantum defect orbital (QDO) method of Simons. This expression contains model-dependent parameters determined from ground and excited state ionization potentials and is derived using a powerful approach based on the sturmian representation of a generalized Coulomb Green's function. In addition, this result is obtained within the ECA and QDO models through an extension of the novel algebraic procedure previously used in obtaining the static polarizability within the ECA, thus demonstrating the equivalence of the two approaches. Static quadrupole and scalar and tensor dipole polarizabilities for a variety of mono and divalent ground and excited state systems within the CA, ECA, and QDO models are compared, when possible, with recent experimental and accurate theoretical work. Except for quadrupole polarizabilities of light divalent systems, agreement for all models is very good. For ground state systems, best accuracy is obtained using the ECA. Illustrative calculation for the dynamic dipole polarizability at real and imaginary frequencies for the He 11S and 21S systems within the ECA is presented and compared with the definitive results of Glover and Weinhold (GW). For He 11S, despite an 8% error in the predicted static polarizability, scaling the dynamic polarizability to the GW static value shows the frequency dependence to be accurately represented. The analytic nature of the ECA allows a wide variety of dispersion force coefficients to be easily calculated. Extensive, but not exhaustive, tabulations of C6, C8, C10, and D9 (three-body) coefficients are given. C6 coefficients involving the He 11S, 21S, 23S systems are compared with the accurate results of GW and, except for interactions of He 12S, excellent agreement is obtained. The discrepancies for He 11S are removed by a simple scaling procedure utilizing the static polarizability. To facilitate scaling of dispersion coefficients, normalized dispersion coefficients are defined. Normalized dipole and quadrupole dispersion coefficients are given for all alkaline earth-alkaline earth pairs. Accurate results for C6 and C8 coefficients are presented for all alkali-alkali pairs and C6 coefficients for alkali-alkaline earth interactions given. Sample C10 and D9 coefficients are listed for the alkalis and hydrogen. Coupling the ECA dynamic dipole polarizability to available discrete oscillator strength distribution data allows C6 coefficients to be obtained for the interaction of alkali, alkaline earth, and metastable helium atoms with the following systems: He, Ne, Ar, Kr, Xe, N, O, H2, N2, O2, NO, N2O, H2O, NH3, and CH4. Finally, C8 coefficients for He-alkali interactions are presented. A significant number of the dispersion coefficients obtained here are not available in the literature. Based on the success of ECA static multipole polarizability predictions, we feel the results presented here are generally the most reliable to date.

Lamm, Gene; Szabo, Attila

1980-03-01

401

Multiple coulomb excitation of 167Er  

NASA Astrophysics Data System (ADS)

The ground-state rotational band in 167Er has been investigated through multiple Coulomb excitation with a 160 MeV 35Cl beam. Excited states up to 25/2+ were established by measuring ?? coincidences and ?-ray angular distributions. Gamma-gamma angular correlations were also measured. Nuclear lifetimes of levels up to spin 23/2 have been determined from Doppler-broadened ?-ray lineshapes, and B(M1) and B(E2) values of intra-band transitions deduced. Considerable signature dependence was observed for level energies and M1 transition probabilities. A Coriolis band-mixing calculation was carried our for comparison with the experimental results. The measured M1 transition probabilities are compared to calculations based on a particle-rotor model, a cranking model, and a microscopic model with quantum-number projection.

Ohshima, Masumi; Minehara, Eisuke; Ishii, Mitsuhiko; Inamura, Takashi; Hashizume, Akira

1985-04-01

402

Simulating Coulomb collisions in a magnetized plasma  

NASA Astrophysics Data System (ADS)

The problem of simulating ion-ion Coulomb collisions in a plasma in a strong magnetic field is considered. No assumption is made about the ion distribution function except that it is independent of the gyrophase angle, consistent with the assumption that the ion gyrofrequency is much larger than the ion-ion collision frequency. A Langevin method is presented which time-advances the components of a particle's velocity parallel and perpendicular to the magnetic field, without following the rapidly changing gyrophase. Although the standard Monte Carlo procedure, which uses random sampling, can be used, it is also possible to use a deterministic sampling procedure, where the samples are determined by the points which would be used in a numerical quadrature formula for moments of the Fokker-Planck Green's function. This should reduce the sampling noise compared with the Monte Carlo collision method.

Hinton, Fred L.

2008-04-01

403

Screening of coulomb impurities in graphene.  

PubMed

We calculate exactly the vacuum polarization charge density in the field of a subcritical Coulomb impurity, Z|e|/r, in graphene. Our analysis is based on the exact electron Green's function, obtained by using the operator method, and leads to results that are exact in the parameter Zalpha, where alpha is the "fine-structure constant" of graphene. Taking into account also electron-electron interactions in the Hartree approximation, we solve the problem self-consistently in the subcritical regime, where the impurity has an effective charge Z(eff), determined by the localized induced charge. We find that an impurity with bare charge Z=1 remains subcritical, Z(eff)alpha<1/2, for any alpha, while impurities with Z=2, 3 and higher can become supercritical at certain values of alpha. PMID:18352585

Terekhov, Ivan S; Milstein, Alexander I; Kotov, Valeri N; Sushkov, Oleg P

2008-02-22

404

The ghost propagator in Coulomb gauge  

SciTech Connect

We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until 'forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

Watson, P.; Reinhardt, H. [Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2011-05-23

405

Theoretical description of Coulomb balls: Fluid phase  

SciTech Connect

A theoretical description for the radial density profile of a finite number of identical charged particles confined in a harmonic trap is developed for application over a wide range of Coulomb coupling (or, equivalently, temperatures) and particle numbers. A simple mean-field approximation neglecting correlations yields a density profile which is monotonically decreasing with radius for all temperatures, in contrast to molecular dynamics simulations and experiments showing shell structure at lower temperatures. A more complete theoretical description including charge correlations is developed here by an extension of the hypernetted chain approximation, developed for bulk fluids, to the confined charges. The results reproduce all of the qualitative features observed in molecular dynamics simulations and experiments. These predictions are then tested quantitatively by comparison with benchmark Monte Carlo simulations. Quantitative accuracy of the theory is obtained by correcting the hypernetted chain approximation with a representation for the associated bridge functions.

Wrighton, J.; Dufty, J. W.; Kaehlert, H.; Bonitz, M. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts Universitaet zu Kiel, 24098 Kiel (Germany)

2009-12-15

406

Projectile Coulomb excitation of 78Se  

NASA Astrophysics Data System (ADS)

The excited states of a 78Se nucleus were studied via a multiple Coulomb excitation experiment. A natural lead target was irradiated by the 78Se beam and ? rays in coincidence with the scattered projectiles were collected. Resulting yields were used as an input for the least squares analysis code GOSIA. Four known excited states were observed and nine matrix elements including three diagonal ones were derived from this analysis. The deformation parameter was deduced by a sum rule. The results showed good agreement with the calculation by the asymmetric rotor model with triaxial deformation parameter ??23° 28°. The quadrupole moments of the 2+1 and 2+2 states analyzed by this model suggested that both levels had the same intrinsic state.

Hayakawa, T.; Toh, Y.; Oshima, M.; Osa, A.; Koizumi, M.; Hatsukawa, Y.; Utsuno, Y.; Katakura, J.; Matsuda, M.; Morikawa, T.; Sugawara, M.; Kusakari, H.; Czosnyka, T.

2003-06-01

407

The ghost propagator in Coulomb gauge  

NASA Astrophysics Data System (ADS)

We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until `forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

Watson, P.; Reinhardt, H.

2011-05-01

408

Competition between binary reactions and fusion in heavy-ion collisions at the Coulomb barrier  

Microsoft Academic Search

Mass and charge distributions for binary reaction channels have been measured for the reactions86Kr with76Ge,104Ru and130Te at the Coulomb barrier using chemical separations and?-ray spectroscopy. These systems span the region where dynamical hindrance to complete fusion sets in. The binary reactions can be subdivided into two components associated withi) reflection from the outer potential barrier (quasielastic), andii) reseparation after passing

W. Reisdorf; J. V. Kratz; R. Bellwied; W. Brüchle; H. Keller; K. Lützenkirchen; M. Schädel; K. Sümmerer; G. Wirth

1992-01-01

409

New type of cross section singularity in backward scattering: the Coulomb glory  

Microsoft Academic Search

For classical scattering by a central potential that exhibits Coulomb behavior (i.e., that is attractive) at small distances, the scattering angle theta tends to ..pi.. as the orbital angular momentum L decreases. The differential cross section for scattering through angles close to ..pi.. can be characterized by the power series expansion of the difference theta(L)--..pi.. in small L, only odd

Y. N. Demkov; V. N. Ostrovskii; D. A. Telnov

1984-01-01

410

Physical interpretation and assessment of the Coulomb-hole and screened-exchange approximation for molecules  

Microsoft Academic Search

Hedin's Coulomb-hole and screened-exchange (COHSEX) approximation for the one-electron Green-function self-energy is examined for small molecules through second order in the bare interaction (COHSEX2). Numerical examples suggest that the COHSEX2 approximation works better for ionization potentials and generalized overlaps (Dyson amplitudes) than does either Koopman's theorem or the usual second-order Green-function (GF2) approximation. This result has been traced to the

Mark E. Casida; Delano P. Chong

1989-01-01

411

Asymmetric Coulomb blockade and Kondo temperature of single-molecule transistors  

NASA Astrophysics Data System (ADS)

Recent experiments on single-molecule transistors made of cobalt complexes exhibited anomalously weak gate voltage dependence of the Kondo temperature accompanied by a strong asymmetry in the Coulomb blockade peaks. We show that these observations can both be explained by strong electron vibron interactions when including anharmonicities of the molecular potential surfaces. The strong electron vibron interactions may originate from a tendency of the cobalt complexes toward Jahn Teller distortion.

Elste, Florian; von Oppen, Felix

2008-06-01

412

Elastic scattering of the halo nucleus 6He from 208Pb above the Coulomb barrier  

NASA Astrophysics Data System (ADS)

Elastic scattering of 6He at Elab=27 MeV with 208Pb has been measured in the angular range of 6°-72° in the laboratory system employing LEDA and LAMP detection systems. Optical Model calculations have been performed using dynamic polarisation potential. The role of Coulomb dipole polarisability has been investigated. Large values of the imaginary diffuseness parameter are required in order to fit the data.

Kakuee, O. R.; Rahighi, J.; Sánchez-Benítez, A. M.; Andrés, M. V.; Cherubini, S.; Davinson, T.; Galster, W.; Gómez-Camacho, J.; Laird, A. M.; Lamehi-Rachti, M.; Martel, I.; Shotter, A. C.; Smith, W. B.; Vervier, J.; Woods, P. J.

2003-12-01

413

Coulomb blockade gap and coulomb staircase of a new type in various tunnel-junction arrays with two branches  

Microsoft Academic Search

In various tunnel-junction arrays having two conducting branches between the source and the drain electrodes, a new type of Coulomb blockade gap and Coulomb staircase are observed. We attribute their appearance to the topology of the arrays which induces multiple electrons to become trapped. When the number of trapped electrons is varied by external sources, the current may flow during

M. Shin; S. Lee; K. W. Park; E.-H. Lee

1999-01-01

414

The Coulomb Blockade in Coupled Quantum Dots  

NASA Astrophysics Data System (ADS)

Individual quantum dots are often referred to as ``artificial atoms''. Two tunnel-coupled quantum dots may be considered an ``artificial molecule''. One advantage of studying quantum dot molecules is that the amount of coupling between the dots may be experimentally varied. We present measurements of conductance through a double quantum dot with adjustable interdot tunneling rate that show the evolution from two separate ``atoms'' to one composite ``molecule''.(C. Livermore, C.H. Crouch, R.M. Westervelt, K.L. Campman, and A.C. Gossard, Science) 274, 1332 (1996). The quantum dots are defined in a two-dimensional electron gas in a GaAs/AlGaAs heterostructure by ten independent electrostatic surface gates. The gates are used to separately control the total induced charge on the double dot, the induced charge difference between the dots, and the interdot tunnel conductance. We measure the double dot conductance as a function of the total induced charge and the induced charge difference to measure the charging diagram and probe the minimum energy surface of the double dot; we repeat this measurement for a series of conductances ranging from near zero to 2e^2/h. For weak interdot tunneling each dot is individually governed by the Coulomb blockade. As interdot tunnel conductance increases, the charging diagram departs from simple Coulomb blockade theory and evolves to that of a single large dot. The evolution is controlled by quantum mechanical charge sharing between dots. The results are in excellent quantitative agreement with recent theory.(J.M. Golden and B.I. Halperin, Phys. Rev. B), in press (1996); K.A. Matveev, L.I. Glazman and H.U. Baranger, Phys. Rev. B 54, 5637 (1996).

Livermore, C.

1997-03-01

415

Quantifying the {sup 12}C+{sup 12}C sub-Coulomb fusion with the time-dependent wave-packet method  

SciTech Connect

This contribution provides a preliminary study of the {sup 12}C+{sup 12}C sub-Coulomb fusion reaction using the time-dependent wave-packet method within a nuclear molecular picture. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.

Diaz-Torres, Alexis; Wiescher, Michael [ECT, Strada delle Tabarelle 286, I-38123 Villazzano, Trento (Italy); JINA and Department of Physics, University of Notre Dame, IN 46656 (United States)

2012-10-20

416

Freezing lines of colloidal Yukawa spheres. I. A Rogers-Young integral equation study  

NASA Astrophysics Data System (ADS)

Using the Rogers-Young (RY) integral equation scheme for the static structure factor combined with the one-phase Hansen-Verlet (HV) freezing rule, we study the equilibrium structure and two-parameter freezing lines of colloidal particles with Yukawa-type pair interactions representing charge-stabilized silica spheres suspended in dimethylformamide (DMF). Results are presented for a vast range of concentrations, salinities and effective charges covering particles with masked excluded-volume interactions. The freezing lines were obtained for the low-charge and high-charge solutions of the static structure factor, for various two-parameter sets of experimentally accessible system parameters. All RY-HV based freezing lines can be mapped on a universal fluid-solid coexistence line in good agreement with computer simulation predictions. The RY-HV calculations extend the freezing lines obtained in earlier simulations to a broader parameter range. The experimentally observed fluid-bcc-fluid reentrant transition of charged silica spheres in DMF can be explained using the freezing lines obtained in this work.

Gapinski, Jacek; Nägele, Gerhard; Patkowski, Adam

2012-01-01

417

Radiative symmetry breaking in minimal N = 1 supergravity with large Yukawa couplings  

NASA Astrophysics Data System (ADS)

We systematically study the radiative breaking of the electroweak gauge symmetry in minimal N = 1 supergravity models with a heavy top quark, mt >= 90 GeV, emphasizing the case of large tan ? for which the Yukawa couplings for bottom and tau play an important role. We found that three differnt solutions fore tan ? can exist for fixed values of mt and the soft supersymmetry breaking parameters. Two of these solutions have large tan ? and lead to a large mass splitting and mixing for all third-generation sfermions, as well as a light Higgs spectrum, giving rise to rich phenomenological consequences. The reduced masses of the light b~- and t~-eigenstates lead to large enhancements of gluino branching ratios into b- and t-quarks, which can easily be the dominant gluino decay modes. We also show that combinations of soft breaking parameters that lead to unacceptably large neutralo relic densities for small tan ? are cosmologically safe if there is a light ~? or a light pseudoscalar Higgs boson; both of these particles can be arbitrarily light for solutions with large tan ?. Work supported in part by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, no. 02952050.

Drees, Manuel; Nojiri, Mihoko M.

1992-01-01

418

Space-time properties of a boson-dressed fermion for the Yukawa model  

SciTech Connect

We analyze the interaction of fermions and bosons through a one-dimensional Yukawa model. We numerically compute the energy eigenstates that represent a physical fermion, which is a superposition of bare fermionic and bosonic eigenstates of the uncoupled Hamiltonian. It turns out that even fast bare fermions require only low-momentum dressing bosons, which attach themselves to the fast fermion through quantum correlations. We compare the space-time evolution of a physical fermion with that of its bare counterpart and show the importance of using dressed observables. The time evolution of the center of mass as well as the wave packet's spatial width suggests that the physical particle has a lower mass than the sum of the masses of its bare constituents. The numerically predicted dressed mass agrees with that from lowest-order perturbation theory as well as with the renormalized mass obtained from the corresponding Feynman graphs. For a given momentum, this lower mass leads to a faster physical particle and a different relativistic spreading behavior of the wave packet.

Wagner, R. E.; Ware, M. R.; Su, Q.; Grobe, R. [Intense Laser Physics Theory Unit and Department of Physics, Illinois State University, Normal, Illinois 61790-4560 (United States)

2010-09-15

419

Structure and thermodynamics of hard-core Yukawa fluids: Thermodynamic perturbation approaches  

NASA Astrophysics Data System (ADS)

The thermodynamic perturbation theories, which are based on the power series of a coupling constant (?-expansion), have been proposed for studying the structural and thermodynamic properties of a hard-core Yukawa (HCY) fluid: one (A1-approximation) is the perturbation theory based on the hard-sphere repulsion as a reference system. The other (A2-approximation) is the perturbation theory based on the reference system which incorporates both the repulsive and short-range attractive interactions. The first-order mean-spherical approximation (FMSA) provided by Tang and Lu [J. Chem. Phys. 99, 9828 (1993)] has been employed for investigating the thermodynamic properties of a HCY fluid using the alternative method via the direct correlation function. The calculated results show that (i) the A1 and A2 approximations are in excellent agreements with previous computer simulation results in the literature and compare with the semi-empirical works of Shukla including the higher-order free energy terms, (ii) the A1 and A2 approximations are better than the FMSA and the mean-spherical approximation, (iii) the A2-approximation compares with the A1-approximation, even though the perturbation effect of an A2-approximation is much smaller than that of an A1-approximation, and that (iv) the FMSA study is particularly of advantage in providing the structure and thermodynamics in a simple and analytic manner.

Kim, Eun-Young; Kim, Soon-Chul; Seong, Baek-Seok

2011-07-01

420

Sparticle spectroscopy with neutralino dark matter from t-b-{tau} quasi-Yukawa unification  

SciTech Connect

We consider two classes of t-b-{tau} quasi-Yukawa unification scenarios which can arise from realistic supersymmetric SO(10) and SU(4){sub C}xSU(2){sub L}xSU(2){sub R} models. We show that these scenarios can be successfully implemented in the nonuniversal Higgs model with m{sub H{sub u}}=m{sub H{sub d}}{ne}m{sub 0} and the constrained minimal sumersymmetric model frameworks, and they yield a variety of sparticle spectra with Wilkinson Microwave Anisotropy Probe compatible neutralino dark matter. In the nonuniversal Higgs model with m{sub H{sub u}}=m{sub H{sub d}}{ne}m{sub 0}, we find bino-Higgsino dark matter as well as the stau coannihilation and A-funnel solutions. The constrained minimal sumersymmetric model case yields the stau coannihilation and A-funnel solutions. The gluino and squark masses are found to lie in the TeV range.

Dar, Shahida [Mohawk Valley Community College, 1101 Sherman Drive Utica, New York 13501 (United States); Gogoladze, Ilia; Shafi, Qaisar; Uen, Cem Salih [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2011-10-15

421

SU(5) D-brane realizations, Yukawa couplings and proton stability  

NASA Astrophysics Data System (ADS)

We discuss SU(5) Grand Unified Theories in the context of orientifold compactifications. Specifically, we investigate two and three D-brane stack realizations of the Georgi-Glashow and the flipped SU(5) model and analyze them with respect to their Yukawa couplings. As pointed out in [1] the most economical Georgi-Glashow realization based on two stacks generically suffers from a disastrous large proton decay rate. We show that allowing for an additional U(1) D-brane stack this as well as other phenomenological problems can be resolved. We exemplify with globally consistent Georgi-Glashow models based on RCFT that these D-brane quivers can be indeed embedded in a global setting. These globally consistent realizations admit rigid O(1) instantons inducing the perturbatively missing coupling 10105 H. Finally we show that flipped SU(5) D-brane realizations even with multiple U(1) D-brane stacks are plagued by severe phenomenological drawbacks which generically cannot be overcome.

Anastasopoulos, P.; Leontaris, G. K.; Richter, R.; Schellekens, A. N.

2010-12-01

422

Yukawa corrections from four-point functions in intersecting D6-brane models  

SciTech Connect

We discuss corrections to the Yukawa matrices of the standard model (SM) fermions in intersecting D-brane models due to four-point interactions. Recently, an intersecting D-brane model has been found where it is possible to obtain correct masses and mixings for all quarks as well as the tau lepton. However, the masses for the first two charged leptons come close to the right values but are not quite correct. Since the electron and muon are quite light, it is likely that there are additional corrections to their masses which cannot be neglected. With this in mind, we consider contributions to the SM fermion mass matrices from four-point interactions. In an explicit model, we show that it is indeed possible to obtain the SM fermion masses and mixings which are a better match to those resulting from experimental data extrapolated at the unification scale when these corrections are included. These corrections may have broader application to other models.

Chen, C.-M.; Mayes, V. E. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States); Li Tianjun [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080 (China); Nanopoulos, D. V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, Texas 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, Texas 77381 (United States); Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)

2008-11-15

423

Dynamic Potentials in Gyrotropic Plasmas.  

National Technical Information Service (NTIS)

Wave equations are derived for the scalar and vector potentials of guided electromagnetic waves propagating in a laterally bounded magnetized plasma along the axis of the static magnetic field. Solutions are given in the Coulomb and the Lorentz gauge. The...

V. Bevc

1969-01-01

424

Structure Theory for Extended Kepler-Coulomb 3D Classical Superintegrable Systems  

NASA Astrophysics Data System (ADS)

The classical Kepler-Coulomb system in 3 dimensions is well known to be 2nd order superintegrable, with a symmetry algebra that closes polynomially under Poisson brackets. This polynomial closure is typical for 2nd order superintegrable systems in 2D and for 2nd order systems in 3D with nondegenerate (4-parameter) potentials. However the degenerate 3-parameter potential for the 3D extended Kepler-Coulomb system (also 2nd order superintegrable) is an exception, as its quadratic symmetry algebra doesn't close polynomially. The 3D 4-parameter potential for the extended Kepler-Coulomb system is not even 2nd order superintegrable. However, Verrier and Evans (2008) showed it was 4th order superintegrable, and Tanoudis and Daskaloyannis (2011) showed that in the quantum case, if a second 4th order symmetry is added to the generators, the double commutators in the symmetry algebra close polynomially. Here, based on the Tremblay, Turbiner and Winternitz construction, we consider a! n infinite class of classical extended Kepler-Coulomb 3- and 4-parameter systems indexed by a pair of rational numbers (k1,k2) and reducing to the usual systems when k1=k2=1. We show these systems to be superintegrable of arbitrarily high order and work out explicitly the structure of the symmetry algebras determined by the 5 basis generators we have constructed. We demonstrate that the symmetry algebras close rationally; only for systems admitting extra discrete symmetries is polynomial closure achieved. Underlying the structure theory is the existence of raising and lowering constants of the motion, not themselves polynomials in the momenta, that can be employed to construct the polynomial symmetries and their structure relations.

Kalnins, Ernie G.; Miller, Willard, Jr.

2012-06-01

425

The Thermodynamic Limit for Matter Interacting with Coulomb Forces and with the Quantized Electromagnetic Field: I. The Lower Bound  

Microsoft Academic Search

The proof of the existence of the thermodynamic limit for electrons and nuclei interacting via the Coulomb potential, was accomplished decades ago in the framework of non-relativistic quantum mechanics, . This result did not take account of interactions caused by magnetic fields, however, (the spin-spin interaction, in particular) or of the quantized nature of the electromagnetic field. Recent progress has

Elliott H. Lieb; Michael Loss

2005-01-01

426

Static Coulomb stress changes on faults caused by the 2008 Mw 7.9 Wenchuan, China earthquake  

Microsoft Academic Search

The 12 May 2008 Mw 7.9 Wenchuan earthquake has changed the regional tectonic stress field significantly. It is important to know how such a change affects the tectonic loading processes of the faults and therefore the seismic potential of the region. Utilizing the slip distribution of the Wenchuan earthquake as the driving source we compute the changes of Coulomb failure

Yongge Wan; Zheng-Kang Shen

2010-01-01

427

Vacuum structure of the Coulomb gas in two dimensions  

NASA Astrophysics Data System (ADS)

We study the plasma phase of the two-dimensional Coulomb gas in the small density limit. The analysis is done using the correspondence of the Coulomb gas with the 1 + 1 sine-Gordon model, which has been exactly solved by the quantum inverse method. We construct the correct vacuum of the field theory, improving the former results. We obtain exact results for the Coulomb gas, which confirm the previous perturbative calculations. Address after 1 March 82: Universität Essen, Gesamthochschule, Postfach 103764, 4300 Essen 1, Fed. Rep. of Germany.

Saglio, Adriana M.

1982-10-01

428

Verification of Coulomb order in a storage ring  

NASA Astrophysics Data System (ADS)

We verify theoretically that the anomalous longitudinal temperature reduction of strongly electron cooled heavy ions in the ESR at very low density is explained by the fact that there is no intrabeam scattering and that the particles by their Coulomb repulsion cannot pass each other any more. At the achievable momentum spreads Coulomb order is reached at particle distances of the order of centimeters. It is also shown that under the given experimental conditions in the proton NAP-M experiment of 1980 intrabeam heating counteracts Coulomb order.

Hasse, Rainer W.

1999-12-01

429

Verification of Coulomb Order in a Storage Ring  

SciTech Connect

We verify theoretically that the anomalous longitudinal temperature reduction of strongly electron cooled heavy ions in the ESR at very low density is explained by the fact that there is no intrabeam scattering and that the particles by their Coulomb repulsion cannot pass each other any more. At the achievable momentum spreads Coulomb order is reached at particle distances of the order of centimeters. It is also shown that under the given experimental conditions in the proton NAP-M experiment of 1980 intrabeam heating counteracts Coulomb order.

Rainer W. Hasse

1999-12-31

430

Verification of Coulomb order in a storage ring  

SciTech Connect

We verify theoretically that the anomalous longitudinal temperature reduction of strongly electron cooled heavy ions in the ESR at very low density is explained by the fact that there is no intrabeam scattering and that the particles by their Coulomb repulsion cannot pass each other any more. At the achievable momentum spreads Coulomb order is reached at particle distances of the order of centimeters. It is also shown that under the given experimental conditions in the proton NAP-M experiment of 1980 intrabeam heating counteracts Coulomb order.

Hasse, Rainer W. [GSI Darmstadt, D-64291 Darmstadt (Germany)

1999-12-10

431

High energy negative ion generation by Coulomb implosion mechanism  

SciTech Connect

Generation of high energy negative ions from laser plasmas by Coulomb implosion mechanism is investigated. When clusters or underdense plasmas are irradiated by an intense laser pulse, positive ions are accelerated inside the clusters or in the self-focusing channel by the Coulomb explosion. This could lead to the acceleration of negative ions toward target center. The maximum energy of negative ions is typically several times lower than that of positive ions. A theoretical description and corresponding particle-in-cell simulations of Coulomb implosion mechanism are presented. We show the evidence of the negative ion acceleration observed in our experiments using high intensity laser pulse and the cluster-gas targets.

Nakamura, T.; Fukuda, Y.; Yogo, A.; Tampo, M.; Kando, M.; Hayashi, Y.; Kameshima, T.; Pirozhkov, A. S.; Esirkepov, T. Zh.; Daido, H. [Kansai Photon Science Institute, JAEA, Kyoto 619-0215 (Japan); Pikuz, T. A.; Faenov, A. Ya. [Kansai Photon Science Institute, JAEA, Kyoto 619-0215 (Japan); Joint Institute of High Temperature, RAS, Moscow 125412 (Russian Federation); Bulanov, S. V. [Kansai Photon Science Institute, JAEA, Kyoto 619-0215 (Japan); A.M. Prokhorov Institute of General Physics, RAS, Moscow 119991 (Russian Federation)

2009-11-15

432

Coulomb breakup of 6Li into ?+d in the field of a 208Pb ion  

NASA Astrophysics Data System (ADS)

The triple differential cross section of the 208Pb(6Li,?d)208Pb quasielastic breakup is calculated at a collision energy of 156 MeV and a scattering angle range of 2?-6?. We fit the parameters of the Woods-Saxon potential using the experimental ?-d phase shifts for different states to describe the relative motion of the ? particle and deuteron. To check the validity of the two particle approach for the ?-d system, we apply a potential model to describe the 2H(?,?)6Li radiative capture. We calculate the Coulomb breakup using the semiclassical method while an estimation of the nuclear breakup is made on the basis of the diffraction theory. A comparison of our calculation with the experimental data of Kiener [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.44.2195 44, 2195 (1991)] gives evidence for the dominance of the Coulomb dissociation mechanism and the contribution of nuclear distortion, but is essentially smaller than the value reported by Hammache [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.82.065803 82, 065803 (2010)]. The results of our calculation for the triple cross sections (contributed by the Coulomb and nuclear mechanisms) of the 6Li breakup hint toward a forward-backward asymmetry in the relative direction of the ? particle and deuteron emission, especially at smaller scattering angles, in the 6Li center-of-mass (c.m.) system.

Irgaziev, B. F.; Nabi, Jameel-Un; Khan, Darwaish

2011-12-01

433

Localizing gauge fields on a topological Abelian string and the Coulomb law  

SciTech Connect

The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than 5{beta}/4{pi}e{sup 2}v{sup 2} and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a (R{sub o}/{beta}R{sup 2}) correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today's measurable distances.

Torrealba S, Rafael S. [Departamento de Fisica., Universidad Centro Occidental 'Lisandro Alvarado' (Venezuela, Bolivarian Republic of)

2010-07-15

434

Linear-scaling multipole-accelerated Gaussian and finite-element Coulomb method  

NASA Astrophysics Data System (ADS)

A linear-scaling implementation of the Gaussian and finite-element Coulomb (GFC) method is presented for the rapid computation of the electronic Coulomb potential. The current work utilizes the fast multipole method (FMM) for the evaluation of the Poisson equation boundary condition. The FMM affords significant savings for small- and medium-sized systems and overcomes the bottleneck in the GFC method for very large systems. Compared to an exact analytical treatment of the boundary, more than 100-fold speedups are observed for systems with more than 1000 basis functions without any significant loss of accuracy. We present CPU times to demonstrate the effectiveness of the linear-scaling GFC method for both one-dimensional polyalanine chains and the challenging case of three-dimensional diamond fragments.

Watson, Mark A.; Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

2008-02-01

435

Coulomb blockade effect of molecularly suspended graphene nanoribbons investigated with scanning tunneling microscopy  

NASA Astrophysics Data System (ADS)

We present the study of the quantum tunneling through a vertical two-barrier structure sandwiching a graphene nanoribbon quantum object. Scanning tunneling microscopy measurements of the graphene nanoribbon show staircase I-U characteristics and oscillating dI/dU spectra. To identify the physical origin of the observed effect, we varied the tunneling resistance of the tip-ribbon junction and found a tip-to-ribbon distance dependent oscillating period change. Together with the numerical analysis, we confirm that the resonances in the spectroscopy arise from the Coulomb blockade effect. The study of the Coulomb blockade effect in graphene nanoribbons may be of potential usages for the fabrication of superthin quantum dot devices.

Zhong, Z. F.; Shen, H. L.; Cao, R. X.; Sun, L.; Li, K. P.; Hu, J.; Liu, Z.; Wu, D.; Wang, X. R.; Ding, H. F.

2013-09-01

436

Coulomb crystals in the magnetic field  

NASA Astrophysics Data System (ADS)

The body-centered-cubic Coulomb crystal of ions in the presence of a uniform magnetic field is studied using the rigid electron background approximation. The phonon mode spectra are calculated for a wide range of magnetic-field strengths and for several orientations of the field in the crystal. The phonon spectra are used to calculate the phonon contribution to the crystal energy, entropy, specific heat, Debye-Waller factor of ions, and the rms ion displacements from the lattice nodes for a broad range of densities, temperatures, chemical compositions, and magnetic fields. Strong magnetic field dramatically alters the properties of quantum crystals. The phonon specific heat increases by many orders of magnitude. The ion displacements from their equilibrium positions become strongly anisotropic. The results can be relevant for dusty plasmas, ion plasmas in Penning traps, and especially for the crust of magnetars (neutron stars with superstrong magnetic fields B?1014G ). The effect of the magnetic field on ion displacements in a strongly magnetized neutron star crust can suppress the nuclear reaction rates and make them extremely sensitive to the magnetic-field direction.

Baiko, D. A.

2009-10-01

437

Coulomb excitation of {sup 73}Ga  

SciTech Connect

The B(E2;I{sub i}{yields}I{sub f}) values for transitions in {sub 31}{sup 71}Ga{sub 40} and {sub 31}{sup 73}Ga{sub 42} were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of {sup 71,73}Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted {gamma} rays were detected by the MINIBALL {gamma}-detector array, and B(E2;I{sub i}{yields}I{sub f}) values were obtained from the yields normalized to the known strength of the 2{sup +}{yields}0{sup +} transition in the {sup 120}Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity toward lower excitation energy when adding neutrons beyond N=40. This supports conclusions from previous studies of the gallium isotopes, which indicated a structural change in this isotopic chain between N=40 and 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2{sup -} spin and parity for the ground state, the extracted results revealed evidence for a 1/2{sup -},3/2{sup -} doublet near the ground state in {sub 31}{sup 73}Ga{sub 42} differing by at most 0.8 keV in energy.

Diriken, J.; Bree, N.; Cocolios, T. E.; Huyse, M.; Ivanov, O. V.; Patronis, N.; Pauwels, D.; Van Duppen, P. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Stefanescu, I. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742 (United States); Balabanski, D. [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy); INRNE, Bulgarian Academy of Science, BG-1784 Sofia (Bulgaria); Blasi, N.; Lo Bianco, G. [Dipartimento di Fisica, Universita di Camerino, I-62032 Camerino (Italy); Blazhev, A.; Eberth, J.; Jolie, J.; Reiter, P.; Warr, N. [IKP, University of Cologne, D-50937 Cologne (Germany); Cederkaell, J. [ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); Physics Department, University of Lund, Box-118, SE-22100 Lund (Sweden); Davinson, T. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Ekstroem, A. [Physics Department, University of Lund, Box-118, SE-22100 Lund (Sweden)

2010-12-15

438

Coulomb gauge ghost Dyson-Schwinger equation  

NASA Astrophysics Data System (ADS)

A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative boundary condition (the value of the inverse ghost propagator dressing function at zero momentum), which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until forced to freeze out in the infrared to the value of the boundary condition. The renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.

Watson, P.; Reinhardt, H.

2010-12-01

439

Coulomb excitation of radioactive nuclear beams in inverse kinematics  

SciTech Connect

Techniques for the measurement of B (E2:0{sub 1}{sup +} {r_arrow} 2{sub 1}{sup +}) values by Coulomb excitation of Radioactive Nuclear Beams in inverse kinematics are described. Using a thin, low Z target, the Coulomb excited beam nuclei will decay in flight downstream of the target. For long lifetimes (nanosecond range) these nuclei decay centimeters downstream of the target and for shorter lifetimes (picoseconds or less) they decay near the target. Corresponding to these two lifetime regimes two methods have been developed to measure {gamma} rays from the Coulomb excited nuclei: the lifetime method in which the lifetime of the excited state is deduced from the decay curve and the integral method in which the B(E2) value is extracted from the measured total Coulomb excitation cross section.

Zamfir, N.V. [Brookhaven National Lab., Upton, NY (United States)]|[Yale Univ., New Haven, CT (United States)]|[Clark Univ., Worcester, MA (United States)]|[Inst. of Atomic Physics, Bucharest Magurele (Romania); Barton, C.J.; Brenner, D.S. [Clark Univ., Worcester, MA (United States); Casten, R.F. [Brookhaven National Lab., Upton, NY (United States)]|[Yale Univ., New Haven, CT (United States); Gill, R.L. [Brookhaven National Lab., Upton, NY (United States); Zilges, A. [Yale Univ., New Haven, CT (United States)]|[Univ. zu Koeln (Germany). Inst. fuer Kernphysik

1996-12-31

440

Coulomb effects on cold kaons from Vlasov dynamics  

SciTech Connect

We compute the influence of Coulomb effects on kaon distribution at low momentum in high energy nucleus-nucleus collisions. This is accomplished by solving the Vlasov equation in the presence of an expanding, highly charged, fireball.

Ayala, Alejandro [Department of Physics, University of Illinois at Urbana-Champaign, Urbana Illinois 61801-3080 (United States)

1997-03-15

441

Multifragmentation: Surface and Coulomb instabilities of sheets, bubbles, and donuts  

SciTech Connect

Disks, bubbles, and donuts have been observed in dynamical calculations of heavy ion collisions. These shapes are subject to a variety of surface and Coulomb instabilities. These instabilities are identified and analyzed in terms of their relevance to multifragmentation.

Moretto, L.G.; Tso, Kin; Wozniak, G.J.

1993-08-01

442

Coulomb “Blockade” of Nuclear Spin Relaxation in Quantum Dots  

Microsoft Academic Search

We study the mechanism of nuclear spin relaxation in quantum dots due to the\\u000aelectron exchange with 2D gas. We show that the nuclear spin relaxation rate is\\u000adramatically affected by the Coulomb blockade and can be controlled by gate\\u000avoltage. In the case of strong spin-orbit coupling the relaxation rate is\\u000amaximal in the Coulomb blockade valleys whereas for

Y. B. Lyanda-Geller; I. L. Aleiner; B. L. Altshuler

2002-01-01

443

Ginzburg criterion for ionic fluids: The effect of Coulomb interactions.  

PubMed

The effect of the Coulomb interactions on the crossover between mean-field and Ising critical behavior in ionic fluids is studied using the Ginzburg criterion. We consider the charge-asymmetric primitive model supplemented by short-range attractive interactions in the vicinity of the gas-liquid critical point. The model without Coulomb interactions exhibiting typical Ising critical behavior is used to calibrate the Ginzburg temperature of the systems comprising electrostatic interactions. Using the collective variables method, we derive a microscopic-based effective Hamiltonian for the full model. We obtain explicit expressions for all the relevant Hamiltonian coefficients within the framework of the same approximation, i.e., the one-loop approximation. Then we consistently calculate the reduced Ginzburg temperature t_{G} for both the purely Coulombic model (a restricted primitive model) and the purely nonionic model (a hard-sphere square-well model) as well as for the model parameters ranging between these two limiting cases. Contrary to the previous theoretical estimates, we obtain the reduced Ginzburg temperature for the purely Coulombic model to be about 20 times smaller than for the nonionic model. For the full model including both short-range and long-range interactions, we show that t_{G} approaches the value found for the purely Coulombic model when the strength of the Coulomb interactions becomes sufficiently large. Our results suggest a key role of Coulomb interactions in the crossover behavior observed experimentally in ionic fluids as well as confirm the Ising-like criticality in the Coulomb-dominated ionic systems. PMID:24032770

Patsahan, O

2013-08-05

444

Nuclear Fusion induced by Coulomb Explosion of Heteronuclear Clusters  

Microsoft Academic Search

We propose a new mechanism for the production of high-energy ( E>3 keV) deuterons, suitable to induce dd nuclear fusion, based on multielectron ionization and Coulomb explosion of heteronuclear deuterium containing molecular clusters, e.g., (D2O)n, in intense ( 1016-2×1018 W\\/cm2) laser fields. Cluster size equations for E, in conjunction with molecular dynamics simulations, reveal important advantages of Coulomb explosion of

Isidore Last; Joshua Jortner

2001-01-01

445

One-Dimensional 3Craft Coulomb Structure Control  

Microsoft Academic Search

A Coulomb structure is a cluster of satellites that can maintain or change its shape through inter-vehicle electrostatic forces generated by on-board charge control de- vices. This paper investigates the charged dynamics of a linear 3-craft cluster. The 1D-restricted control of a three-body coulomb structure is developed. This control can be used to stabilize the motion of charged spheres on

S. Wang; H. Schaub

446

Diffusion and Coulomb Separation of Ions in Dense Matter  

NASA Astrophysics Data System (ADS)

We analyze diffusion equations in strongly coupled Coulomb mixtures of ions in dense stellar matter. Strong coupling of ions in the presence of gravitational forces and electric fields (induced by plasma polarization in the presence of gravity) produces a specific diffusion current which can separate ions with the same A/Z (mass to charge number) ratios but different Z. This Coulomb separation of ions can be important for the evolution of white dwarfs and neutron stars.

Beznogov, M. V.; Yakovlev, D. G.

2013-10-01

447

Coulomb explosion of propane in intense femtosecond laser fields  

Microsoft Academic Search

Femtosecond laser-induced Coulomb explosion of C3H8 is investigated experimentally by means of time-of-flight mass spectrometry at different intensities. The mass spectrum of C3H8 presents much more abundant fragments than obtained through electron-impact ionization. The appearance of intermediate daughter molecular ions with a double-peak structure shows that Coulomb explosion of C3H8 undergoes a two-step process. One C-C bond of the C3

Jianxin Chen; Ri Ma; Xia Li; Haizhen Ren; Hong Yang; Qihuang Gong

2004-01-01

448

Study of 9Be + 12C elastic scattering at energies near the Coulomb barrier  

NASA Astrophysics Data System (ADS)

In this work, angular distribution measurements for the elastic channel were performed for the 9Be + 12C reaction at the energies E=13.0, 14.5, 17.3, 19.0 and 21.0 MeV, near the Coulomb barrier. The data have been analyzed in the framework of the double folding São Paulo potential. The experimental elastic scattering angular distributions were well described by the optical potential at forward angles for all measured energies. However, for the three highest energies, an enhancement was observed for intermediate and backward angles. This can be explained by the elastic transfer mechanism.

Oliveira, R. A. N.; Carlin, N.; Neto, R. Liguori; de Moura, M. M.; Munhoz, M. G.; del Santo, M. G.; Souza, F. A.; Szanto, E. M.; Szanto de Toledo, A.; Suaide, A. A. P.

2011-04-01

449

Coulomb and nuclear-induced break-up of halo nuclei at bombarding energies around the Coulomb barrier  

Microsoft Academic Search

We investigate the relative importance of the Coulomb and nuclear fields to induce the break-up of neutron-rich nuclei such as 11Li at energies close to the Coulomb barrier. We assume that the mechanism that leads to the separation is the excitation of a low-lying dipole mode in which the weakly-bound neutron halo performs a collective oscillation against the residual nuclear

C. H. Dasso; J. L. Guisado; S. M. Lenzi; A. Vitturi

1996-01-01

450

Secular Stress Accumulation, Coulomb Stress Changes, and Clock Changes on Los Angeles Regional Faults: Preliminary Results  

NASA Astrophysics Data System (ADS)

Coulomb stress changes are commonly calculated after large earthquake events to determine regions that are brought closer to failure. History has shown that regions of increased Coulomb stress are commonly candidates for large future events. We propose to improve on the standard static Coulomb stress change calculations in the Los Angeles region by incorporating analysis of secular tectonic stress accumulation rates. With knowledge of both the stress changes and the secular stress accumulation rates one can calculate clock advances and delays on affected faults. To elucidate the rates of secular tectonic stress accumulation along faults in the Los Angeles region, we use an established three-dimensional Boundary Element Method deformation model of the Los Angeles region based on the Southern California Earthquake Center (SCEC) Community Fault Model. Rock properties in the model are derived from the SCEC Community Velocity Model and indicate a relatively uniform rheology at seismogenic depths (~15-18km). We calculate secular stressing rates, by applying a regional geodetic strain rate determined from corrected GPS velocities to a model with all fault elements locked. We then calculate the area-weighted average shear stress on each fault surface. Because stress drops may be relatively invariant for a large range of earthquake magnitudes, knowledge of secular stressing rates could be useful for estimating recurrence rates and maximum potential magnitudes of future events.

Marshall, S. T.; Cooke, M. L.

2009-12-01

451

Aftershock triggering by complete Coulomb stress changes  

USGS Publications Warehouse

We examine the correlation between seismicity rate change following the 1992, M7.3, Landers, California, earthquake and characteristics of the complete Coulomb failure stress (CFS) changes (??CFS(t)) that this earthquake generated. At close distances the time-varying "dynamic" portion of the stress change depends on how the rupture develops temporally and spatially and arises from radiated seismic waves and from permanent coseismic fault displacement. The permanent "static" portion (??CFS) depends only on the final coseismic displacement. ??CFS diminishes much more rapidly with distance than the transient, dynamic stress changes. A common interpretation of the strong correlation between ??CFS and aftershocks is that load changes can advance or delay failure. Stress changes may also promote failure by physically altering properties of the fault or its environs. Because it is transient, ??CFS(t) can alter the failure rate only by the latter means. We calculate both ??CFS and the maximum positive value of ??CFS(t) (peak ??CFS(t)) using a reflectivity program. Input parameters are constrained by modeling Landers displacement seismograms. We quantify the correlation between maps of seismicity rate changes and maps of modeled ??CFS and peak ??CFS(t) and find agreement for both models. However, rupture directivity, which does not affect ??CFS, creates larger peak ??CFS(t) values northwest of the main shock. This asymmetry is also observed in seismicity rate changes but not in ??CFS. This result implies that dynamic stress changes are as effective as static stress changes in triggering aftershocks and may trigger earthquakes long after the waves have passed.

Kilb, D.; Gomberg, J.; Bodin, P.

2002-01-01

452

Coulomb excitation of {sup 156}Gd  

SciTech Connect

Multiple Coulomb-excitation experiments for {sup 156}Gd were made with a 118 MeV {sup 32}S beam and a 225 MeV {sup 58}Ni beam. The ground-state band, the {beta} band (K=0{sup +}), another K=0{sup +} band, and the {gamma} band (K=2{sup +}) were observed up to the 18{sup +}, 14{sup +}, 8{sup +}, and 12{sup +} states, respectively, while the octupole band (K=1{sup -}) was observed up to the 15{sup -} state, through the analysis of particle-{gamma}-{gamma} data. Compared with the results of the in-beam {gamma}-ray spectroscopy previously obtained, the present result suggests that a band crossing occurs in the {gamma} band. As for the {beta} band, the excitation energy of the 12{sup +} state was revised and the 14{sup +} state was newly observed in the present experiment. The intrinsic matrix elements entering the generalized intensity relations were obtained so as to reproduce the spin dependence of the E2 matrix elements extracted from the experimental results of particle-{gamma} angular correlation for the transitions within each band and between each band and the ground-state band by the least-squares search code gosia. The change of characters in the {beta} and {gamma} bands is discussed as a possible cause for the variation of the E2 matrix elements in the higher-spin region. The intrinsic matrix elements were also obtained for the E1 and E3 transitions from the ground-state band to the octupole band with K=1{sup -} through analysis by gosia.

Sugawara, M. [Chiba Institute of Technology, Narashino, Chiba 275-0023 (Japan); Kusakari, H. [Faculty of Education, Chiba University, Chiba 263-8522 (Japan); Yoshizawa, Y.; Inoue, H. [Faculty of Science, Hiroshima University, Higashi-hiroshima 739-8526 (Japan); Morikawa, T. [Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan); Shizuma, T. [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); Srebrny, J. [Heavy Ion Laboratory, Warsaw University, Pasteura 5A, PL-02-093 Warsaw (Poland)

2011-06-15

453

Leading Yukawa corrections to Higgs production associated with a tagged bottom-antibottom pair in the standard model at the CERN LHC  

SciTech Connect

Considering the large value of the top Yukawa coupling, we investigate the leading one-loop Yukawa electroweak corrections that can be induced by the top quark in a process such as Higgs production in association with a tagged bottom-antibottom pair at the LHC. At next-to-leading order these contributions are found to be small at the LHC both for the total cross section and for the distributions. In the limit of vanishing bottom Yukawa coupling where the leading order contribution vanishes, the process can still be induced at one-loop through the top quark transition. Though this contribution which can be counted as part of the next-to-next-to-leading order correction is small for Higgs masses around 120 GeV, it quickly picks up for higher Higgs masses. This contribution represents the rescattering of the top quarks and their decay into W's leading to Higgs production through WW fusion.

Boudjema, F. [LAPTH, Universite de Savoie, CNRS, BP 110, F-74941 Annecy-le-Vieux Cedex (France); Duc Ninh Le [LAPTH, Universite de Savoie, CNRS, BP 110, F-74941 Annecy-le-Vieux Cedex (France); Theory Division, CERN, CH-1211 Geneva 23 (Switzerland)

2008-02-01

454

Yukawa couplings and masses of non-chiral states for the Standard Model on D6-branes on {T^{{6}}}/{Z}_{{6}}^' }  

NASA Astrophysics Data System (ADS)

The perturbative leading order open string three-point couplings for the Standard Model with hidden USp(6) on fractional D6-branes on {T^{{6}}}/{Z}_{{6}}^' } from [1, 2] are computed. Physical Yukawa couplings consisting of holomorphic Wilsonian superpotential terms times a non-holomorphic prefactor involving the corresponding classical open string Kähler metrics are given, and mass terms for all non-chiral matter states are derived. The lepton Yukawa interactions are at leading order flavour diagonal, while the quark sector displays a more intricate pattern of mixings. While {N} = 2 supersymmetric sectors acquire masses via only two D6-brane displacements — which also provide the hierarchies between up and down-type Yukawas within one quark or lepton generation, — the remaining vector like states receive masses via perturbative three-point couplings to some Standard Model singlet fields with vev s along flat directions. Couplings to the hidden sector and messengers for supersymmetry breaking are briefly discussed.

Honecker, Gabriele; Vanhoof, Joris

2012-04-01

455

Pseudospin Symmetry in Position-Dependent Mass Dirac-Coulomb Problem by Using Laplace Transform and Convolution Integral  

NASA Astrophysics Data System (ADS)

The exact pseudospin symmetry solutions of Dirac equation with position-dependent mass (PDM) Coulomb potential in the presence of Colulomb-like tensor potential are obtained by using Laplace transform (LT) approach. The energy eigenvalue equation of the Dirac particles is found and some numerical results are given. By using Laplace convolution integral, the corresponding radial wave functions are presented in terms of confluent hypergeometric functions.

Ortakaya, Sami

2013-11-01

456

Pseudospin Symmetry in Position-Dependent Mass Dirac-Coulomb Problem by Using Laplace Transform and Convolution Integral  

NASA Astrophysics Data System (ADS)

The exact pseudospin symmetry solutions of Dirac equation with position-dependent mass (PDM) Coulomb potential in the presence of Colulomb-like tensor potential are obtained by using Laplace transform (LT) approach. The energy eigenvalue equation of the Dirac particles is found and some numerical results are given. By using Laplace convolution integral, the corresponding radial wave functions are presented in terms of confluent hypergeometric functions.

Ortakaya, Sami

2013-04-01

457

Mean-field analysis of the Coulomb phase in lattice gauge theory coupled to Higgs matter fields  

NASA Astrophysics Data System (ADS)

The phase diagram of lattice gauge theory coupled to a Higgs field is obtained from a mean-field analysis of the effective potential for the pure gauge theory. Large non-perturbative fluctuations around the mean-field result for the effective potential dynamically generate a Coulomb phase in the phase diagram. Laboratoire associé au Centre National de la Recherche Scientifique. Postal Address: Université de Paris-Sud, Bâtiment 211, 91405 Orsay Cedex, France.

Boucaud, Ph.

1984-02-01

458

Cold chemistry with electronically excited Ca{sup +} Coulomb crystals  

SciTech Connect

Rate constants for chemical reactions of laser-cooled Ca{sup +} ions and neutral polar molecules (CH{sub 3}F, CH{sub 2}F{sub 2}, or CH{sub 3}Cl) have been measured at low collision energies (/k{sub B}=5-243 K). Low kinetic energy ensembles of {sup 40}Ca{sup +} ions are prepared through Doppler laser cooling to form ''Coulomb crystals'' in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca{sup +} ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of {sup 40}Ca{sup +} involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state ({sup 2}S{sub 1/2}) and the combined excited states ({sup 2}D{sub 3/2} and {sup 2}P{sub 1/2}) of {sup 40}Ca{sup +}. These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

Gingell, Alexander D.; Bell, Martin T.; Oldham, James M.; Softley, Timothy P. [Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA (United Kingdom); Harvey, Jeremy N. [Department of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)

2010-11-21

459

Predicting Freezing for Some Repulsive Potentials  

SciTech Connect

We propose a simple method to approximately predict the freezing (fluid-solid) phase transition in systems of particles interacting via purely repulsive potentials. The method is based on the striking universality of the freezing curve for the model Yukawa and inverse-power-law interactions. This method is applied to draw an exemplary phase diagram of complex plasmas. We suggest that it can also be used to locate freezing transition in other substances with similar properties of interaction.

Khrapak, S. A.; Morfill, G. E. [Max-Planck-Institut fuer extraterrestrische Physik, D-85741 Garching (Germany)

2009-12-18

460

Heavy standard model-like Higgs boson and a light stop from Yukawa-deflected gauge mediation  

NASA Astrophysics Data System (ADS)

To obtain a standard model-like Higgs boson around 125 GeV in the minimal supersymmetric standard model with minimal gauge mediation of supersymmetry breaking (GMSB), a heavy stop at multi-TeV level is needed and incurs severe fine-tuning, which can be ameliorated in the framework of the deformed GMSB with visible-hidden direct Yukawa interactions (YGMSB). We examine some general features of the YGMSB and focus on the scenario with Higgs-messenger couplings (HYGMSB) which can automatically maintain the minimal flavor violation. It turns out that such a Yukawa mediation scenario can give a large -At and -mt˜L,R2, leading to a maximal stop mixing, and thus can readily give a light stop (t˜1) below the TeV scale. However, we find that in the minimal HYGMSB scenario, mHu2 is too large and then the electroweak symmetry breaking is inconsistent with the large stop mixing. To solve this problem, we modify the hidden sectors in two ways, adding a new strong gauge dynamics or introducing the (10,10¯) messengers. For each case we present some numerical studies.

Kang, Zhaofeng; Li, Tianjun; Liu, Tao; Tong, Chunli; Yang, Jin Min

2012-11-01