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: August 15, 2014.
1

Bound eigenstates for the superposition of the Coulomb and the Yukawa potentials  

NASA Astrophysics Data System (ADS)

The eigenvalue problem for two particles interacting through the potential being the superposition of the attractive Coulomb potential (-A/r) and the Yukawa potential B exp(-Cr)/r of arbitrary strength B and screening parameter C is solved by variational means. The energy levels Enl for the states 1s through 7i are calculated as functions of B and C. It is shown that for a given principal quantum number n the energy eigenvalues increase (decrease) with increasing azimuthal quantum number l if the Yukawa potential is attractive (repulsive), i.e., for l>l': Enl>=Enl' if B<0, and Enl<=Enl' if B>0. It leads to the crossing of the energy levels with n>=2. For B>0 the levels with larger n and l become lower than those with smaller n and l, e.g., E3d

Adamowski, Janusz

1985-01-01

2

Dirac equation for the generalized Deng-Fan potential with coulomb and Yukawa tensor interactions  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the bound-state solutions of the Dirac equation with the generalized Deng-Fan potential within the framework of spin and pseudospin symmetries and with Coulomblike and Yukawa-like tensor interactions by using a supersymmetric quantum-mechanics (SUSYQM) formulation. We obtain the energy eigenvalue equations and the corresponding upper and lower spinor wave functions for both the spin and the pseudospin cases. We also report some numerical results and figures to show the effect of the tensor interaction.

Ikot, A. N.; Hassanabadi, H.; Yazarloo, B. H.; Zarrinkamar, S.

2013-10-01

3

Fourier transform of the multicenter product of 1s hydrogenic orbitals and Coulomb or Yukawa potentials and the analytically reduced form for subsequent integrals that include plane waves  

NASA Technical Reports Server (NTRS)

The Fourier transform of the multicenter product of N 1s hydrogenic orbitals and M Coulomb or Yukawa potentials is given as an (M+N-1)-dimensional Feynman integral with external momenta and shifted coordinates. This is accomplished through the introduction of an integral transformation, in addition to the standard Feynman transformation for the denominators of the momentum representation of the terms in the product, which moves the resulting denominator into an exponential. This allows the angular dependence of the denominator to be combined with the angular dependence in the plane waves.

Straton, Jack C.

1989-01-01

4

Nonperturbative dynamical-group approach to screened Coulomb potentials  

Microsoft Academic Search

In this paper we consider screened Coulomb potentials of the Yukawa type and treat them using a scaling variational method based on the SO(2, 1) subgroup of the full SO(4,2) dynamical group of the point Coulomb problem. In this formulation the tilting angle is treated as a variational parameter and the relevant matrix elements of the Yukawa potential can be

Christopher C. Gerry; Jeffrey Laub

1984-01-01

5

Bound states of screened coulomb potentials  

NASA Astrophysics Data System (ADS)

We propose an extension of the Ecker-Weizel approximation to treat the non-zero angular momentum bound states of a class of screened Coulomb potentials. As an illustration of our prescription, we have calculated the discrete energies Enl of the Yukawa potential, which are in excellent agreement with those of Rogers et al.

Dutt, Ranabir; Ray, Aparna; Ray, Pritam P.

1981-05-01

6

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

7

Nonlinear magnetoplasmons in strongly coupled Yukawa and Coulomb plasmas  

NASA Astrophysics Data System (ADS)

The wave spectra of magnetized and strongly coupled 2D-Yukawa plasmas have recently been computed numerically [1]. Good agreement between existing theories and the simulation was found. The magnetized Yukawa plasma sustains two modes, the magnetoplasmon and the magnetophonon, the frequencies of which are of the order of the Einstein or cyclotron frequency. In this contribution, we report on the existence of additional high-frequency plasma oscillations at multiples of the magnetoplasmon, based on extensive molecular dynamics simulations. The emergent modes are reminiscent of the well-known Bernstein modes but are renormalized by the strong interparticle correlations. We present detailed numerical results and an analytical explanation of the observed features [2].[4pt] [1] Hou et al., Phys. Plas., 16, 73704 (2009)[0pt] [2] Bonitz et al., Phys. Rev. Lett., in print (2010)

Ott, Torben; Bonitz, Michael; Donkó, Zoltan; Hartmann, Peter

2010-11-01

8

Yukawa particles in a confining potential.  

PubMed

We study the density distribution of repulsive Yukawa particles confined by an external potential. In the weak coupling limit, we show that the mean-field theory is able to accurately account for the particle distribution. In the strong coupling limit, the correlations between the particles become important and the mean-field theory fails. For strongly correlated systems, we construct a density functional theory which provides an excellent description of the particle distribution, without any adjustable parameters. PMID:25005276

Girotto, Matheus; Dos Santos, Alexandre P; Colla, Thiago; Levin, Yan

2014-07-01

9

Envelope representations for screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

We study the discrete eigenvalues Enl of the Schrödinger Hamiltonian H=-(1/2)?+V(r), where V(r)=g(-1/r) is an increasing concave transformation of the Coulomb potential, and n is the principal (radial) quantum number. It is demonstrated by the method of potential envelopes that upper bounds are provided by the simple formula Enl<= mins>0 \\{(1/2)s+V((n+l)/s1/2)\\}, where s is a real variable. Numerical results are compared with previous work for two specific screened Coulomb potentials. In the case of the Yukawa potential V(r)=-(v/r)exp(-?r), it is shown that the inequality (n+l)2?/v<2/e is sufficient to guarantee the existence of the eigenvalue Enl: In the case of S states, sharp upper and lower bounds are also provided by a different method.

Hall, Richard L.

1985-07-01

10

Analytic phase shifts for Yukawa potentials  

SciTech Connect

The Yukawa or Debye-Hueckel potential, by a suitable choice of scale factor (d) and the use of the corresponding energy unit (h/sup 2//2md/sup 2/), may be written in the form V(r:Z) = -(2Z/r)e/sup -r/. For Z much less than 1 or l much greater than 1 or E = k/sup 2/ sufficiently large the partial wave phase shifts are given by the Born approximation which mathematically vanishes at E = 0. On the other hand, Levinson's theorem indicates that a phase shift, in units of ..pi.., is equal to n(Z,l), the integral number of bound states sustainable by the potential. In this work an optical model code written by Relyea for molecular potentials is adapted to be suitable for singular attractive potentials such as the Yukawa potential. This modified code is used to obtain the numerical Schroedinger phase shifts for a broad range of Z and l values. By the addition of integers to assure continuity of the phase shifts and the satisfaction of Levinson's theorem the authors obtain an array of continuous functions which, in effect, interpolate between the Levinson limit and the Born limit. Next, they find an accurate analytic characterization of the number of bound states n/sub a/ (Z,l) suggested by the Sommerfeld model. Finally, they develop a simple two-term analytic formula which interpolates between the Levinson limit and the Born limit and fits the rectified set of Schroedinger phase shifts quite well. In effect, they arrive at a four-dimensional function delta(E,l,Z,d) that should be useful as a convenient approximation in atomic, nuclear, particle, and plasma physics. 12 references, 9 figures, 2 tables.

Green, A.E.S.; Rio, D.E.; Schippnick, P.F.; Schwartz, J.M.; Ganas, P.S.

1982-01-01

11

Analytic phase shifts for Yukawa potentials  

SciTech Connect

The Yukawa or Debye-Hueckel potential, by a suitable choice of scale factor (d) and the use of the corresponding energy unit (h/sup 2//2md/sup 2/), may be written in the form V(r:Z) = -(2Z/r)e/sup -r/. For Z much less than 1 or l much greater than 1 or E = k/sup 2/ sufficiently large the partial wave phase shifts are given by the Born approximation which mathematically vanishes at E = 0. On the other hand, Levinson's theorem indicates that a phase shift, in units of ..pi.., is equal to n(Z,l), the integral number of bound states sustainable by the potential. In this work we first adapt an optical model code written by Relyea for molecular potentials to be suitable for singular attractive potentials such as the Yukawa potential. This modified code is used to obtain the numerical Schroedinger phase shifts for a broad range of Z and l values. By the addition of integers to assure continuity of the phase shifts and the satisfaction of Levinson's theorem we obtain an array of continuous functions which, in effect, interpolate between the Levinson limit and the Born limit. Next we find an accurate analytic characterization of the number of bound states N/sub a/(Z,l) suggested by the Sommerfeld model. Finally we develop a simple two-term analytic formula which interpolates between the Levinson limit and the Born limit and fits the rectified set of Schroedinger phase shifts quite well. In effect we arrive at a four-dimensional function delta(E,l,Z,d) which should be useful as a convenient approximation in atomic, nuclear, particle, and plasma physics.

Green, A.E.S.; Rio, D.E.; Schippnick, P.F.; Schwartz, J.M.; Ganas, P.S.

1982-01-01

12

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. Program summaryProgram title: FMM-Yukawa 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

13

The Yukawa potential in semirelativistic formulation via supersymmetry quantum mechanics  

NASA Astrophysics Data System (ADS)

We apply an approximation to the centrifugal term and solve the two-body spinless-Salpeter equation (SSE) with the Yukawa potential via the supersymmetric quantum mechanics (SUSYQM) for arbitrary quantum numbers. Useful figures and tables are also included.

Hassanabadi, S.; Ghominejad, M.; Zarrinkamar, S.; Hassanabadi, H.

2013-06-01

14

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

15

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-Yukawa Catalogue identifier: AEEQ_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEEQ_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 2.0 No. of lines in distributed program, including test data, etc.: 78 704 No. of bytes in distributed program, including test data, etc.: 854 265 Distribution format: tar.gz Programming language: FORTRAN 77, FORTRAN 90, and C. Requires gcc and gfortran version 4.4.3 or later Computer: All Operating system: Any Classification: 4.8, 4.12 Catalogue identifier of previous version: AEEQ_v1_0 Journal reference of previous version: Comput. Phys. Comm. 180 (2009) 2331 Does the new version supersede the previous version?: Yes 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: 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 t

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

2010-12-01

16

Restricted Problem of Three Bodies with Newtonian + Yukawa Potential  

NASA Astrophysics Data System (ADS)

Trajectories of the third body in the Restricted Problem of Three Bodies including a Yukawa term to the Newtonian gravitational potential are analyzed. It is shown that this modified gravitational potential changes some important aspects of the Restricted Problem of Three Bodies. Depending of coupling constant ?, motions obtained in the pure Newtonian case are qualitatively different when Yukawa term is included. Depending of coupling parameters ?, the nature of dynamics change from regular to chaotic (?<0) or from chaotic to regular (?>0) and in both cases using the same length scales ?.

Kokubun, Fernando

17

Stationary solution of NLFP with coulombic potential  

SciTech Connect

In a previous paper, Grassi (2012) [39], a new entropy form has been proposed for which it is possible to obtain a stationary solution of the Non-Linear Fokker-Planck equation (referred as NLFP) with coulombic-like potentials. In this paper we analyze the stationary solution of NLFP obtained by using pure coulombic potentials and we will use this solution to study an 'atomic-like' system. - Highlights: Black-Right-Pointing-Pointer The entropy introduced in a previous work has been studied for a coulombic potential. Black-Right-Pointing-Pointer From this entropy form a NLFP has been derived for a pure coulombic potential. Black-Right-Pointing-Pointer The stationary solution of the NLFP for an 'atomic-like' system has been obtained. Black-Right-Pointing-Pointer A comparison with Boltzmann entropy has been proposed.

Grassi, A., E-mail: agrassi@unict.it

2013-02-15

18

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

19

Polaron Bound in a Coulomb Potential.  

National Technical Information Service (NTIS)

The authors have calculated the shift in ground-state energy of an electron bound in a Coulomb potential in a crystal, to second order in the electron-phonon coupling and for arbitrary values of the electron-impurity coupling. (Author)

M. H. Engineer N. Tzoar

1971-01-01

20

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

21

Hydrogen atom with a Yukawa potential: Perturbation theory and continued-fractions--Pade approximants at large order  

SciTech Connect

A simple power-series method is developed to calculate to large order the Rayleigh-Schroedinger perturbation expansions for energy levels of a hydrogen atom with a Yukawa-type screened Coulomb potential. Perturbation series for the 1s, 2s, and 2p levels, shown not to be of the Stieltjes type, are calculated to 100th order. Nevertheless, the poles of the Pade approximants to these series generally avoid the region of the positive real axis 0 < lambda < lambda(, where lambda( represents the coupling constant threshold. As a result, the Pade sums afford accurate approximations to E(lambda) in this domain. The continued-fraction representations to these perturbation series have been accurately calculated to large (100th) order and demonstrate a curious ''quasioscillatory,'' but non-Stieltjes, behavior. Accurate values of E(lambda) as well as lambda( for the 1s, 2s, and 2p levels are reported.

Vrscay, E.R.

1986-02-01

22

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

23

Bound eigenstates for two truncated Coulomb potentials  

NASA Astrophysics Data System (ADS)

The eigenvalue problem for two particles interacting through the attractive truncated Coulomb potential, V(r)=-Ze2/(rp+?p)1/p, for p=1 and 2 is solved numerically. Energy eigenvalues accurate to within eight to six significant figures for the states 1s to 4f are calculated as a function of the truncation parameter ?. It is found that the level ordering satisfies Enl>Enl' for l

Singh, David; Varshni, Y. P.; Dutt, Ranabir

1985-07-01

24

Discrete perturbation theory for the hard-core attractive and repulsive Yukawa potentials  

NASA Astrophysics Data System (ADS)

In this work we apply the discrete perturbation theory [A. L. Benavides and A. Gil-Villegas, Mol. Phys. 97, 1225 (1999)] to obtain an equation of state for the case of two continuous potentials: the hard-core attractive Yukawa potential and the hard-core repulsive Yukawa potential. The main advantage of the presented equation of state is that it is an explicit analytical expression in the parameters that characterize the intermolecular interactions. With a suitable choice of their inverse screening length parameter one can model the behavior of different systems. This feature allows us to make a systematic study of the effect of the variation in the parameters on the thermodynamic properties of this system. We analyze single phase properties at different conditions of density and temperature, and vapor-liquid phase diagrams for several values of the reduced inverse screening length parameter within the interval ?*=0.1-5.0. The theoretical predictions are compared with available and new Monte Carlo simulation data. Good agreement is found for most of the cases and better predictions are found for the long-range ones. The Yukawa potential is an example of a family of hard-core plus a tail (attractive or repulsive) function that asymptotically goes to zero as the separations between particles increase. We would expect that similar results could be found for other potentials with these characteristics.

Torres-Arenas, J.; Cervantes, L. A.; Benavides, A. L.; Chapela, G. A.; Del Río, F.

2010-01-01

25

Logarithmic perturbation theory for a screened Coulomb potential and a charmonium potential  

SciTech Connect

Logarithmic perturbation theory (PT) for screened Coulomb potential is considered. Calculation of higher PT orders of the level energy E/sub h/ is reduced to recurrence relations that are valid for any type of screening and are very convenient for computer calculations. They are employed to calculate the PT coefficient of E/sub h/ up to k = 100 for a number of physically interesting cases such as the Yukawa potential, the quarkonium potential, etc. The approach of E/sub h/ as k..-->..infinity to the asymptotic form of E/sub h/, defined by the quasiclassical approximation, is discussed. The problem of summation of the divergent PT series is considered. By employing the Pade approximants and the asymptotic form of E/sub h/ it is possible to determine with a high accuracy the energy level E(g) for the potentials mentioned above in a range that exceeds considerably the range of applicability of PT, including the strong coupling region.

Vainberg, V.M.; Eletskii, V.L.; Popov, V.S.

1981-11-01

26

Positron scattering from hydrogen atom with screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

Elastic positron-hydrogen collisions with screened Coulomb potentials have been investigated using a second-order distorted wave Born approximation in the momentum space. Two types of potentials have been considered, namely, static screened Coulomb potential and exponential cosine-screened Coulomb potential. Using a simple variationally determined hydrogenic wave function it has been possible to obtain the scattering amplitude in a closed form. A detailed study has been made on the differential and total cross sections in the energy range 20-300 eV.

Ghoshal, Arijit; Nayek, Sujay; Kamali, M. Z. M.; Ratnavelu, K.

2014-03-01

27

Dirac electron in the two-dimensional Debye–Yukawa potential  

NASA Astrophysics Data System (ADS)

Spectra of the two-dimensional H-like screened atoms are investigated in the framework of nonrelativistic and relativistic models. The Schrödinger and the Dirac equation for the 2D Debye–Yukawa potential are solved analytically up to the first-order in the perturbation theory with the Debye screening as the perturbation. We also present the nonperturbative solution to the Schrödinger equation obtained by the expansion of the wavefunction in a basis of Sturmian functions. The nonrelativistic solutions are used as the zero-order approximation in the direct perturbation approach to the Dirac equation.

Poszwa, A.

2014-06-01

28

Liquid-Vapor Coexistence in the Screened Coulomb (Yukawa) Hard Sphere Binary Mixture in Disordered Porous Media: The Mean Spherical Approximation.  

PubMed

The thermodynamics of a two-component fluid with a hard core interaction and screened Coulomb (Yukawa) interaction between particles, similar to the primitive model of an electrolyte solution, adsorbed in a disordered matrix of hard spheres, is studied by using replica Ornstein-Zernike integral equations and the mean spherical approximation (MSA). The gas-liquid transition is localized. The coexistence curve is investigated dependent on the range of interaction between fluid species, on matrix density, and on fluid-matrix attraction. We have observed shrinking of the coexistence envelope with increasing matrix density. The critical temperature of adsorbed mixture decreases with increasing matrix density. The critical density is less affected; however, it also decreases slightly. The critical temperature is sensitive to the fluid species-matrix attraction and depends nonmonotonously on their strength. For a given matrix microporosity, it increases slightly and then decreases with augmenting strength of fluid-matrix attraction. The critical density is less affected by this attraction. However, it decreases for the model with a sufficiently long-range tail of fluid-matrix attraction. Copyright 1998 Academic Press. PMID:9792783

Trokhymchuk; Orozco; Pizio; Vlachy

1998-11-15

29

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

30

Above Threshold Ionization and the Role of the Coulomb Potential  

NASA Astrophysics Data System (ADS)

Within the single-active-electron approximation (SAE), an ab initio formulation of above threshold ionization (ATI) including rescattering that accounts for the long-range Coulomb potential is presented. From this ab initio formulation, an ad hoc formulation is developed in which the effect of the laser field is to split the atomic potential into two parts: a short range one responsible for rescattering producing the photoelectron high energy plateau, and a long-range Coulomb potential that affects the low energy electrons. Furthermore, the role of the Coulomb potential is investigated by looking at the low energy two dimensional momentum distributions, the momentum distributions along the polarization axis, and the low energy photoelectron energy spectra. Moreover, a formulation that considers the simultaneous transfer of both linear and angular momenta in the ionization process is developed. Finally, a formulation of high harmonic generation (HHG) is presented.

Titi, Atef S.

31

Borromean binding in H{sub 2} with Yukawa potential: A nonadiabatic quantum Monte Carlo study  

SciTech Connect

The stability of the ground state of the H{sub 2}{sup +} and H{sub 2} systems, where nuclei and electrons interact through a Yukawa potential e{sup -{lambda}}{sup r}/r, has been studied for different values of the screening parameter {lambda} using quantum Monte Carlo techniques. Nonadiabatic calculations using explicitly correlated trial wave functions were carried out, obtaining exact results within the statistical errors. H{sub 2}{sup +} and H{sub 2} appear to be stable species for values of {lambda} as large as 1.35 and 1.38 bohr{sup -1}. So in the range 1.35{<=}{lambda}{<=}1.38 bohr{sup -1} H{sub 2} is stable, while all the possible fragments are unbound, that is, it shows Borromean binding.

Bertini, Luca; Mella, Massimo; Bressanini, Dario; Morosi, Gabriele [Istituto di Scienze e Tecnologie Molecolari (ISTM), Via Camillo Golgi 19, 20133 Milan (Italy); Central Chemistry Laboratory, Department of Chemistry, University of Oxford, South Park Road, Oxford OX1 3QH (United Kingdom); Dipartimento di Scienze Chimiche e Ambientali, Universita dell'Insubria, via Lucini 3, 22100 Como (Italy)

2004-04-01

32

Analytical computation of amplification of coupling in relativistic equations with Yukawa potential  

SciTech Connect

The approximate analytic solutions to the Klein-Gordon and Dirac equations with the Yukawa potential were derived by using the quasilinearization method (QLM). The accurate analytic expressions for the ground state energies and wave functions were presented. These high-precision approximate analytic representations are obtained by first casting the proper relativistic equation into a nonlinear Riccati form and then solving that nonlinear equation in the first QLM iteration. The choice of zero iteration is based on general features of the exact solutions near the origin and infinity. To estimate the accuracy of the QLM solutions, the exact numerical solutions were found, as well. The analytical QLM solutions are found to be extremely accurate for a small exponent parameter w of the Yukawa potential. The reasonable accuracy is kept for the medium values of w. When w approaches the critical values, the precision of the QLM results falls down markedly. However, the approximate analytic QLM solution to the Dirac equation corresponding to the maximum relativistic effect turned out to be very accurate even for w close to the exact critical w{sub ex}{sup Dir}=1.6767, whereas the QLM calculations yield w{sub qlm}{sup Dir}=1.6763. This effect of 'amplification' in compare with the Schroedinger equation critical parameter w{sub ex}{sup Sch}=1.1906 was investigated earlier [S. De Leo, P. Rotelli, Phys. Rev. D 69 (2004) 034006]. In this work, it was found that the 'amplification' for the Klein-Gordon equation became all the more evident. The exact numerical value is w{sub ex}{sup KG}{approx_equal}2.25, whereas the QLM approximation yields w{sub qlm}{sup KG}{approx_equal}2.15.

Liverts, E.Z. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)], E-mail: liverts@phys.huji.ac.il; Mandelzweig, V.B. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

2009-02-15

33

A double Yukawa potential for the van der Waals interaction of molecules: application to a determination of the critical temperature  

Microsoft Academic Search

A double Yukawa (DY) potential, fitted on the carbon - carbon (CC) van der Waals (vdW) Lennard-Jones 12,6 (LJ) potential and integrated on two facing spheres, yields another DY function, whose parameters are simply related to those of the original CC LJ. We exploit this fact to obtain a new analytic expression of the DY type that describes the high-temperature

1998-01-01

34

Implementation of screened hybrid functionals based on the Yukawa potential within the LAPW basis set  

NASA Astrophysics Data System (ADS)

The implementation of screened hybrid functionals into the wien2k code, which is based on the linearized augmented plane wave (LAPW) basis set, is reported. The Hartree-Fock exchange energy and potential are screened by means of the Yukawa potential as proposed by Bylander and Kleinman [D. M. Bylander and L. Kleinman, Phys. Rev. BPLRBAQ1098-012110.1103/PhysRevB.41.7868 41, 7868 (1990)] for the calculation of the electronic structure of solids with the screened-exchange local density approximation. Details of the formalism, which is based on the method of Massidda, Posternak, and Baldereschi [S. Massidda, M. Posternak, and A. Baldereschi, Phys. Rev. BPLRBAQ1098-012110.1103/PhysRevB.48.5058 48, 5058 (1993)] for the unscreened Hartree-Fock exchange are given. The results for the transition-energy and structural properties of several test cases are presented. The results of calculations of the Cu electric-field gradient in Cu2O are also presented, and it is shown that the hybrid functionals are much more accurate than the standard local-density or generalized gradient approximations.

Tran, Fabien; Blaha, Peter

2011-06-01

35

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

36

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

PubMed

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 (K(1), Z(1), and Z(2)), 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 Z(1) (which determines the range of attractive forces) is important in crystal formation, so long as sufficient attraction (parameter K(1)) 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 Z(2)-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. PMID:20170235

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

2010-02-21

37

Effect of wake potential on Coulomb crystallization in the presence of magnetic field  

SciTech Connect

The formation of dust crystal in plasma under the influence of repulsive Yukawa (Debye-Hueckel) potential is a well known phenomenon. The regular structure of dust particles is affected by anisotropic ion flow near the sheath region. The bombardment of the ions over dust grains distorts their Debye sphere by overshielding the dust cloud and gives rise to an attractive oscillatory wake potential. In this paper, we have obtained an expression for wake potential along with the Yukawa type of potential in a complex plasma in the presence of magnetic field, for subsonic ion flow towards the plasma sheath. In the presence of magnetic field, interaction potential gets modified and becomes anisotropic. We have studied the combined effect of the attractive wake potential as well as repulsive Yukawa potential on a 2D dust crystal, both in the presence and absence of magnetic field, using molecular dynamic simulation.

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

2012-10-15

38

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

39

Heavy tetraquark confining potential in Coulomb gauge QCD  

NASA Astrophysics Data System (ADS)

We present an analytic nonperturbative solution of the Yakubovsky equation for tetraquark states in the case of equal separations and energies, and demonstrate a direct connection between the tetraquark confinement potential and the temporal gluon propagator. To this end we employ a leading-order heavy quark mass expansion of the Coulomb gauge QCD action, and use the dressed two-point functions of the Yang-Mills sector only. As a result, we find a bound state energy that rises linearly with distance and a string tension twice as large as in a qq¯-system.

Popovici, Carina; Fischer, Christian S.

2014-06-01

40

Quantum-Mechanics of a Spinless Particle in Combined Coulomb and Harmonic Oscillator Potentials  

Microsoft Academic Search

In this dissertation the quantum mechanics of a spinless particle in a combined Coulomb and harmonic oscillator potential is discussed. The particular potential considered is a 2:1 anisotropic harmonic oscillator combined with a concentric Coulomb potential. These two potentials are the two most studied potentials in mathematical physics. It is shown that this combined potential gives a Schrodinger equation which

Samuel Ernest Stansfield

1986-01-01

41

Application of the Yukawa potential to the auto-controlled mechanism of the ovalbumin molecule in aqueous systems  

NASA Astrophysics Data System (ADS)

The rigidity of ovalbumin (OA) aqueous colloids remains almost constant over a wide range of OA concentration c from ?0.1 to ?17 wt%; this is called the auto-controlled mechanism. The Yukawa potential was applied to explain the auto-controlled mechanism and revealed that the effective charge Z* of the OA molecule is relatively small. Further, The Z* value is almost constant at extremely low concentrations and is proportional to c- 1/4 in the concentration range where the rigidity remains approximately constant.

Matsumoto, Takayoshi; Inoue, Hiroshi

1992-10-01

42

Higher-order perturbation theory for the bound states of the Dirac equation with a Yukawa-type potential  

SciTech Connect

The method of calculating higher orders of perturbation theory based on perturbation of the Fock operator with a purely discrete spectrum is generalized to the case of the Dirac equation with a potential of the Yukawa type. Corrections to any order of perturbation theory in the energy of an arbitrary bound state are given as finite polynomials which are determined through recurrence relations derived from the dynamical symmetry of the unperturbed problem. We propose a modified Pade approximant method which can be used to transform a divergent perturbation series into a rapidly convergent sequence for all bound and quasistationary states of the system.

Sergeev, A.V.; Sherstyuk, A.I.

1984-05-01

43

Zero-temperature phase diagram of Yukawa bosons  

NASA Astrophysics Data System (ADS)

We study the zero-temperature phase diagram of bosons interacting via screened Coulomb (Yukawa) potential by means of the diffusion Monte Carlo method. The Yukawa potential is used as a model interaction in the neutron matter, dusty plasmas, and charged colloids. As shown by Petrov [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.99.130407 99, 130407 (2007)], interactions between weakly bound molecules of heavy and light fermionic atoms are described by an effective Yukawa potential with a strength related to the heavy-light mass ratio M/m, which might lead to crystallization in a two-dimensional geometry if the mass ratio of heavy-light fermions exceeds a certain critical value. In the present work we do a thorough study of the quantum three-dimensional Yukawa system. For strong interactions (equivalently, large mass ratios) the system experiences several phase transitions as the density is increased, passing from gas to solid and to gas phase again. Weakly interacting Yukawa particles do not crystallize at any density. We find the minimal interaction strength at which the crystallization happens. In terms of the two-component fermionic system, this strength corresponds to a heavy-light mass ratio of M/m˜180, so that it is impossible to realize the gas-crystal transition in a conventional bulk system. For the Yukawa model of fermionic mixtures we also analyze the possibility of building molecular systems with very large effective mass ratios by confining the heavy component to a sufficiently deep optical lattice. We show how the effective mass of the heavy component can be made arbitrarily large by increasing the lattice depth, thus leading to a tunable effective mass ratio that can be used to realize a molecular superlattice.

Osychenko, O. N.; Astrakharchik, G. E.; Mazzanti, F.; Boronat, J.

2012-06-01

44

Improved Shell models for screened Coulomb balls  

Microsoft Academic Search

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

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

2006-01-01

45

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

46

Proton radioactivity with a Yukawa effective interaction  

NASA Astrophysics Data System (ADS)

The half-lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite-range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron-rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.

Routray, T. R.; Tripathy, S. K.; Dash, B. B.; Behera, B.; Basu, D. N.

2011-08-01

47

Calculation of radar signal delays in the vicinity of the Sun due to the contribution of a Yukawa correction term in the gravitational potential  

NASA Astrophysics Data System (ADS)

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton's "inverse-square law" of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. Therefore the existence of such a force would only coexist with gravity, and in principle could only be detected as a deviation from the inverse square law, or in the "universality of free fall" experiments. New experimental techniques such that of Sagnac interferometry can help explore the range of the Yukawa correction ??1014 m where such forces might be present. It may be, that future space missions might be operating in this range which has been unexplored for very long time. To study the effect of the Yukawa correction to the gravitational potential and its corresponding signal delay in the vicinity of the Sun, we use a spherically symmetric modified space time metric where the Yukawa correction its added to the gravitational potential. Next, the Yukawa correction contribution to the signal delay is evaluated. In the case where the distance of closest approach is much less than the range ?, it results to a signal time delay that satisfies the relation t( b< ?)?37.7 t( b= ?).

Haranas, Ioannis; Ragos, Omiros

2011-07-01

48

LETTER TO THE EDITOR: A double Yukawa potential for the van der Waals interaction of ? molecules: application to a determination of the critical temperature  

Microsoft Academic Search

A double Yukawa (DY) potential, fitted on the carbon - carbon (CC) van der Waals (vdW) Lennard-Jones 12,6 (LJ) potential and integrated on two facing spheres, yields another DY function, whose parameters are simply related to those of the original CC LJ. We exploit this fact to obtain a new analytic expression of the DY type that describes the high-temperature

Hervé Guérin

1998-01-01

49

Theoretical studies of the long-range Coulomb potential effect on photoionization by strong lasers  

SciTech Connect

Using the second-order Coulomb-corrected Volkov function as a continuum state, we derive quantum mechanically analytical formulas for the photoionization rate of hydrogen atoms irradiated by a linearly polarized electric field in the tunneling regime. From the analytical formula is directly drawn the important conclusion that the role of the first-order Coulomb correction is to reduce the ionization potential. As a result, the photoionization rate is enhanced compared with that in the absence of the Coulomb correction. In addition, the second-order correction modifies the Keldysh parameter, decreases the binding energy, and increases the photoionization rates relative to those of the first-order Coulomb correction. We estimate the effects of the respective Coulomb corrections on the resonance structure of the photoionization rate, Keldysh parameter, and ponderomotive energy.

Mishima, K.; Yi, J.; Lin, S.H. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 10764, Taiwan (China); Hayashi, M. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan (China); Selzle, H.L.; Schlag, E.W. [Institute of Physical and Theoretical Chemistry, Technical University of Munich, Garching (Germany)

2002-11-01

50

A short proof that the Coulomb-gauge potentials yield the retarded fields  

Microsoft Academic Search

A short demonstration that the potentials in the Coulomb gauge yield the retarded electric and magnetic fields is presented. This demonstration is relatively simple and can be presented in an advanced undergraduate course of electromagnetic theory.

José A. Heras

2011-01-01

51

Relativistic Vector Bosons Under PÖSCHL-TELLER Double-Ring Coulomb Potential  

NASA Astrophysics Data System (ADS)

We study the relativistic Duffin-Kemmer-Petiau equation with the Pöschl-Teller double-ring-shaped Coulomb potential in (1+3) dimensions for spin-1 particles and the exact analytical eigenfunctions and eigenenergies are reported.

Hassanabadi, H.; Molaee, Z.; Zrrinkamar, S.

2012-12-01

52

Scaling of Coulomb pseudo-potential in narrow-band superconductors  

Microsoft Academic Search

The standard Eliashberg theory is extended to incorporate the narrow-band effects, that is, the vertex corrections and frequency dependence of the effective interaction between electrons. From the extended Eliashberg equation, the Coulomb pseudo-potential ?* is extracted. It is shown that even for narrow-band superconductors, where the Fermi energy ?F is comparable with the phonon frequency ?ph, the Coulomb pseudo-potential is

Tae-Ho Park; Han-Yong Choi

2001-01-01

53

GENERAL: Temperature Effects of Parabolic Linear Bound Potential and Coulomb Bound Potential Quantum Dot Qubit  

NASA Astrophysics Data System (ADS)

On the condition of electric-LO phonon strong coupling in a parabolic quantum dot, we obtain the eigenenergy and the eigenfunctions of the ground state and the first-excited state using the variational method of Pekar type. This system in a quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition state of the ground state and the first-excited state, we obtain the time evolution of the electron density. The relations of the probability density of electron on the temperature and the electron-LO-phonon coupling constant and the relations of the period of oscillation on the temperature, the electron-LO-phonon coupling constant, the Coulomb binding parameter and the confinement length are derived. The results show that the probability density of electron oscillates with a period when the electron is in the superposition state of the ground and the first-excited state, and show that there are different laws that the probability density of electron and the period of oscillation change with the temperature and the electron-LO-phonon coupling constant when the temperature is lower or higher. And it is obtained that the period of oscillation decreases with increasing the Coulomb bound potential and increases with increasing the confinement length not only at lower temperatures but also at higher temperatures.

Chen, Ying-Jie; Xiao, Jing-Lin

2009-10-01

54

Structure and correlations in two-dimensional classical artificial atoms confined by a Coulomb potential  

Microsoft Academic Search

The ordering of N equally charged particles (-e) moving in two dimensions and confined by a Coulomb potential, resulting from a displaced positive charge Ze is discussed. This is a classical model system for atoms. We obtain the configurations of charged particles which, depending on the value of N and Z, may result in ring structures, hexagonal-type configurations, and for

W. P. Ferreira; A. Matulis; G. A. Farias; F. M. Peeters

2003-01-01

55

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

56

Symmetrization of the Coulomb pairing potential by electron-phonon interaction  

NASA Astrophysics Data System (ADS)

It is shown that the Coulomb superconducting pairing in systems with the Fermi contour nesting can be described by a quasi-one-dimensional potential oscillating in real space. The supplement of this repulsive potential with an isotropic pairing attraction corresponding to the phonon superconductivity mechanism and including the effect of predominant forward scattering upon electron-phonon interaction leads to symmetrization of this potential and a considerable increase in the superconducting transition temperature.

Belyavsky, V. I.; Kapaev, V. V.; Kopaev, Yu. V.; Mikhailyan, D. I.

2012-08-01

57

Simple eigenvalue formula for the Coulomb-plus-linear potential  

NASA Astrophysics Data System (ADS)

The eigenvalues Enl(?) of the Hamiltonian H=-?-1r+?r are analyzed with the help of potential envelopes and kinetic potentials. The result is the following simple approximate eigenvalue formula: ?={2(?E)3-?E2[(1+3?2E)12-1]}?[(1+3?2E)12-1]3, where E>=-14?2 is a lower bound to Enl(?) if ?=?=(n+l), an upper bound if ?=?=(2n+l-12), and a good approximation when ?=(n+l) and ?=(1.794n+l-0.418).

Hall, Richard L.

1984-07-01

58

Thick- Center- Vortex- Model and the Coulombic Potential  

NASA Astrophysics Data System (ADS)

The potentials for various SU(3) representations are calculated by means of an analytical model for thick center vortices. We discuss the influence of fluctuations of non-quantized, closed magnetic flux lines of short range on the potential. We fit the model parameters to lattice data by G.S.Bali [1]. We will show that the Casimir scaling of this data can only be fitted, if the vortices are never fully contained in the Wilson loop in time-direction. Therefore, we conclude that Casimir scaling for large R is an effect due to the finite range of the Wilson loop in time-direction. If we include this effect in our model by a change of the vortex profile, we obtain the fit, which is illustrated in the following picture. G.S.Bali’s data are connected with full lines and are shown with the modified error bars. In dashed lines, one can see the fitted data. 1.6 1.4 1.2 1 Vr (R) 0.8 0.6 0.4 0.2 1 2 3 4 5 6 7 R

Neudecker, D.

59

Sturmian functions for two Coulomb centers plus oscillator potential.  

NASA Astrophysics Data System (ADS)

Numerical techniques were developed to calculate the Sturmian functions S_n(? q) defined by the equation -1/2nabla^2_q+ ?_n(?)V(q)-? S_n(? q)=0, where ? is a parameter. Sturmian functions are crucial for a consistent formulation of dynamic theories of many atomic processes, such as ion-atom collisions(S.Yu. Ovchinnikov and J.H. Macek, Phys. Rev. Lett. 75), 2474 (1995), Wannier theory(J.H. Macek and S.Yu. Ovchinnikov, Phys. Rev. Lett. 74), 4631 (1995), photoionization(R. Shakeshaft, J. Phys. B 18), L611 (1985); Phys. Rev A 34, 244 (1986). We calculate Sturmians for the potential V(q)= -fracZ_1|q-hatk/2| -fracZ_2|q+hatk/2| +frac?^22q^2, which appears in the Solov'ev-Vinitsky formulation of collision theory(E.A. Solov'ev and S.I. Vinitsky, J. Phys. B 18) L557 (1985). The solution is facilitated by separation of variables in prolate ellipsoidal coordinates. The calculated Sturmian functions are important components of a complete semiclassical theory of ion-atom collisions. Such a theory includes all dynamic effects, and it has been already constructed for the important particular case of zero impact parameter (no oscillator). The Sturmians calculated in this work allow us to extend the theory to the general case of arbitrary impact parameters.

Khrebtukov, D. B.; Macek, J. H.

1997-04-01

60

Dynamics of a particle in a superposition of a Coulomb potential and certain anisotropic harmonic-oscillator potentials  

Microsoft Academic Search

The Hamilton-Jacobi and Schrödinger equations for a particle moving in N (>1) dimensions in a concentric superposition of a Coulomb potential and an anisotropic 2:1 axially symmetric harmonic-oscillator potential together with an axial linear potential separate in parabolic coordinates. The separation constant is an eigenvalue of an operator which is a generalization of the axial component of the Runge-Lenz vector

L. L. Foldy; S. E. Stansfield

1987-01-01

61

Numerical study of a binary Yukawa model in regimes characteristic of globular proteins in solutions  

SciTech Connect

The main goal of this paper is to assess the limits of validity, in the regime of low concentration and strong Coulomb coupling (high molecular charges), of a simple perturbative approximation to the radial distribution functions (RDF's), based upon a low-density expansion of the potential of mean force and proposed to describe protein-protein interactions in a recent small-angle-scattering (SAS) experimental study. A highly simplified Yukawa (screened Coulomb) model of monomers and dimers of a charged globular protein ({beta}-lactoglobulin) in solution is considered. We test the accuracy of the RDF approximation, as a necessary complementary part of the previous experimental investigation, by comparison with the fluid structure predicted by approximate integral equations and exact Monte Carlo (MC) simulations. In the MC calculations, an Ewald construction for Yukawa potentials has been used to take into account the long-range part of the interactions in the weakly screened cases. Our results confirm that the perturbative first-order approximation is valid for this system even at strong Coulomb coupling, provided that the screening is not too weak (i.e., for Debye length smaller than monomer radius). A comparison of the MC results with integral equation calculations shows that both the hypernetted-chain (HNC) and Percus-Yevick closures have a satisfactory behavior under these regimes, with the HNC being superior throughout. The relevance of our findings for interpreting SAS results is also discussed.

Giacometti, Achille; Gazzillo, Domenico; Pastore, Giorgio; Das, Tushar Kanti [Istituto Nazionale per la Fisica della Materia and Dipartimento di Chimica Fisica, Universita di Venezia, S. Marta DD 2137, I-30123 Venice (Italy); Dipartimento di Fisica Teorica, Universita di Trieste and INFM-DEMOCRITOS, National Simulation Center, Strada Costiera 11, Miramare, I-34100 Trieste (Italy); ICTP, Diploma Course, Strada Costiera 11, Miramare P.O Box 586, I-34100 Trieste (Italy)

2005-03-01

62

Continuum resonances with shielded Coulomb-like potential and Efimov effect  

NASA Astrophysics Data System (ADS)

Motivated by the possibility of the second energy level (0{2/+}) of 12C (in a three-alpha model) to turn into an Efimov state, we study a simple non-realistic toy model formed by three bosons interacting by the phenomenological s-wave Ali-Bodmer potential plus a Coulomb interaction. An artificial three-body potential was used to create a resonance with energy close to the energy of the 0{2/+} of 12C, 0.38 MeV. The strength of the Coulomb potential is decreased until the energies of the two alpha pairs are zero. The system was placed inside a harmonic trap and a stabilization method has been used to calculate the energies of the resonances. We found that the shielded-Coulomb potential, which keeps the long tail, is not able to produce the Efimov effect. The energy of the three alphas decreases only to 0.19 MeV when the two-body energy crosses the threshold to become bound.

Tusnski, D. S.; Yamashita, M. T.; Frederico, T.; Tomio, L.

2014-04-01

63

Liquid-gas phase behavior of an argon-like fluid modelled by the hard-core two-Yukawa potential  

NASA Astrophysics Data System (ADS)

We study a model for an argon-like fluid parameterized in terms of a hard-core repulsion and a two-Yukawa potential. The liquid-gas phase behavior of the model is obtained from the thermodynamically Self-Consistent Ornstein-Zernike Approximation (SCOZA) of Høye and Stell, the solution of which lends itself particularly well to a pair potential of this form. The predictions for the critical point and the coexistence curve are compared to new high resolution simulation data and to other liquid-state theories, including the hierarchical reference theory (HRT) of Parola and Reatto. Both SCOZA and HRT deliver results that are considerably more accurate than standard integral-equation approaches. Among the versions of SCOZA considered, the one yielding the best agreement with simulation successfully predicts the critical point parameters to within 1%.

Pini, D.; Stell, G.; Wilding, N. B.

2001-08-01

64

Quantum mechanics of a spinless particle in combined coulomb and harmonic oscillator potentials  

SciTech Connect

In this dissertation the quantum mechanics of a spinless particle in a combined Coulomb and harmonic oscillator potential is discussed. The particular potential considered is a 2:1 anisotropic harmonic oscillator combined with a concentric Coulomb potential. These two potentials are the two most studied potentials in mathematical physics. It is shown that the combined potential gives a Schroedinger equation that separates in a parabolic coordinate system. The energy eigenfunctions for the pure oscillator is given by the product of polynomials in the parabolic coordinates and gaussians in these same coordinates. These eigenfunctions form a complete set. The discussion of the oscillator is closed with a short discussion of the algebraic aspects of the pure oscillator problem. When the Schroedinger equation for the combined potential is separated, two equations of identical form arise. The single equation obtained is one that has received very little attention in the past. The eigenvalues of the resulting pairs of equations are found numerically. The results for these eigenvalues are presented graphically, although a method for finding them explicitly is described. Once the eigenvalues are found, the wavefunctions may then be easily found.

Stansfield, S.E.

1986-01-01

65

Energy Spectra of the Coulomb Perturbed Potential in N-Dimensional Hilbert Space  

NASA Astrophysics Data System (ADS)

We deal with the solutions to the radial Schrödinger equation for the Coulomb perturbed potential in N-dimensional Hilbert space by using two methods, i.e. the power series technique via a suitable ansatz to the wavefunction and the Virial theorem. Analytic expressions for eigenvalues and normalized eigenfunctions are derived. A recursion relation among series expansion coefficients, a condition for convergence of series and inter-dimensional degeneracies are also investigated. As special cases, the problem is solved in 3 and 4 dimensions with some specific parameter values. The obtained analytical and numerical results are in good agreement with the results of other studies.

Ramesh, Kumar; Fakir, Chand

2012-06-01

66

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

NASA Astrophysics Data System (ADS)

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 16O+144Sm and 16O+208Pb reactions, and find that the inverted internucleus potential are much thicker than phenomenological potentials.

Hagino, K.

2009-05-01

67

Calculations of wavefunctions and energies of electron system in Coulomb potential by variational method without a basis set  

NASA Astrophysics Data System (ADS)

A new variational method without a basis set for calculation of the eigenvalues and eigenfunctions of Hamiltonians is suggested. The expansion of this method for the Coulomb potentials is given. Calculation of the energy and charge distribution in the two-electron system for different values of the nuclear charge Z is made. It is shown that at small Z the Coulomb forces disintegrate the electron cloud into two clots.

Bykov, V. P.; Gerasimov, A. V.

1992-08-01

68

Exchange-coulomb potential energy curves for He-He, and related physical properties  

NASA Astrophysics Data System (ADS)

The investigation of the reliability of the original simple overall damped form of the XC (exchange-Coulomb) potential is extended to the He-He interaction, and a new multidamped version of the XC potential is introduced. New one and two parameter overall damped, and one and two parameter multidamped XC potentials for He-He are constructed. The results obtained from these potentials for the second virial coefficients (1·4 < T < 623 K) and transport properties of dilute He gas, and for integral collision cross-sections for He-He collisions, are compared with experiment and with those obtained with the (reference) HFD-B2 potential. The various XC potentials are explicitly compared, over a wide range of interatomic distances R, with the HFD-B2 potential, with ab initio results and with a very accurate (R ? 3a0) quantum Monte Carlo potential. While the one parameter versions of the XC potentials generally yield very good results, the two parameter overall and individually damped XC potentials, and the HFD-B2 potential, are of comparable quality and are apparently the most reliable representatives of the He-He interaction available.

Aziz, Ronald A.; Slaman, M. J.; Koide, A.; Allnatt, A. R.; Meath, William J.

69

An effective coulomb potential obtained by using the extended elastic model III for the sub-barrier fusion  

Microsoft Academic Search

Summary  An effective Coulomb potential is defined in the framework of the extended elastic model III for the sub-barrier fusion. By\\u000a using this effective potential the singularity of Rutherford differential cross-section atE=0 disappears. The differential cross-section relative to the new potential attains a maximum value at low energy.

A. Scalia

1991-01-01

70

Structure and correlations in two-dimensional classical artificial atoms confined by a Coulomb potential.  

PubMed

The ordering of N equally charged particles (-e) moving in two dimensions and confined by a Coulomb potential, resulting from a displaced positive charge Ze is discussed. This is a classical model system for atoms. We obtain the configurations of charged particles which, depending on the value of N and Z, may result in ring structures, hexagonal-type configurations, and for N/Z approximately 1 in an inner structure of particles which is separated by an outer ring of particles. For N/Z<1, the Hamiltonian of the parabolic confinement case is recovered. For N/Z approximately 1, the configurations are very different from those found in the case of a parabolic confinement potential. A hydrodynamic analysis is presented in order to highlight the correlations effects. PMID:12786503

Ferreira, W P; Matulis, A; Farias, G A; Peeters, F M

2003-04-01

71

Symmetric potentials of gauged supergravities in diverse dimensions and Coulomb branch of gauge theories  

NASA Astrophysics Data System (ADS)

A class of conformally flat and asymptotically anti-de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parametrize the SL(N,R)/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal form. These geometries descend via consistent truncation from distributions of D3-branes, M2-branes, or M5-branes in ten or eleven dimensions. We exhibit analogous solutions asymptotic to AdS6 which descend from the D4-D8-brane system. We obtain the related six-dimensional theory by consistent reduction from massive type IIA supergravity. All our geometries correspond to states in the Coulomb branch of the dual conformal field theories. We analyze linear fluctuations of minimally coupled scalars and find both discrete and continuous spectra, but always bounded below.

Cveti?, M.; Gubser, S. S.; Lü, H.; Pope, C. N.

2000-10-01

72

Symmetric potentials of gauged supergravities in diverse dimensions and Coulomb branch of gauge theories  

SciTech Connect

A class of conformally flat and asymptotically anti--de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parametrize the SL(N,R)/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal form. These geometries descend via consistent truncation from distributions of D3-branes, M2-branes, or M5-branes in ten or eleven dimensions. We exhibit analogous solutions asymptotic to AdS{sub 6} which descend from the D4-D8-brane system. We obtain the related six-dimensional theory by consistent reduction from massive type IIA supergravity. All our geometries correspond to states in the Coulomb branch of the dual conformal field theories. We analyze linear fluctuations of minimally coupled scalars and find both discrete and continuous spectra, but always bounded below.

Cvetic, M.; Gubser, S. S.; Lu'', H.; Pope, C. N.

2000-10-15

73

Yukawa textures and anomalies  

Microsoft Academic Search

We augment the Minimal Supersymmetric Standard Model with a gauged family-dependent U(1) to reproduce Yukawa textures compatible with experiment. In the simplest model with one extra chiral electroweak singlet field, acceptable textures require this U(1) to be anomalous. The cancellation of its anomalies by a generic Green-Schwarz mechanism requires sin2?w = 38 at the string scale, suggesting a supersting a

Pierre Binétruy; Pierre Ramond

1995-01-01

74

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

75

Light charged particle accompanied ternary fission of 242Cm using the Coulomb and proximity potential  

NASA Astrophysics Data System (ADS)

The cold ternary fission of 242Cm with 4He , 10Be and 14C as light charged particle has been studied by taking the interacting barrier as the sum of Coulomb and proximity potential with the fragments in equatorial configuration. The favorable fragment combinations are obtained from the cold valley plot (plot of driving potential vs. mass number of fragments) and by calculating the yield for charge minimized fragments. The maximum yield in the 4He accompanied ternary fission is obtained for the fragmentation channel 104Mo + 134Te + 4He and for the 10Be accompanied ternary fission, the maximum yield is found for the fragmentation channel 98Zr + 134Te + 10Be . It is to be noted that, in the case of 14C accompanied ternary fission, the maximum yield is obtained for the fragmentation channel 94Sr + 134Te + 14C and the next higher yield is found for the fragmentation channel 96Zr + 132Sn + 14C . Thus, the fragment combinations with maximum yields reveal the role of doubly magic and near doubly magic nuclei in cold ternary fission.

Santhosh, K. P.; Krishnan, Sreejith; Priyanka, B.

2014-04-01

76

Three-Nucleon Interactions in Yukawa Theory  

Microsoft Academic Search

The method of Salpeter and Bethe is applied to the three-nucleon bound state problem. In a first approximation involving only multiple ladder-type diagrams, and neglecting retardation effects altogether, an equivalent Hamiltonian is derived which contains as potential energy merely the static Yukawa potentials of the three nucleon pairs. If the retardation corrections are treated as small perturbations, e.g., in a

G. Wentzel

1953-01-01

77

Diffraction at a time grating in above-threshold ionization: The influence of the Coulomb potential  

SciTech Connect

We analyze the photoelectron emission spectrum in atomic above-threshold ionization by a linearly polarized short-laser pulse. Direct electrons can be characterized by both intracycle and intercycle interferences. The former results from the coherent superposition of two different electron trajectories released in the same optical cycle, whereas the latter is the consequence of the superposition of multiple trajectories released in different cycles. In the present article, a semiclassical analytical expression for the complete (both intracycle and intercycle) interference pattern is derived. We show that the recently proposed semiclassical description in terms of a diffraction process at a time grating remains qualitatively unchanged in the presence of the long-range Coulomb potential. The latter causes only a phase shift of the intracycle interference pattern. We verify the predictions of the semiclassical model by comparison with full three-dimensional (3D) time-dependent Schroedinger equation (TDSE) solutions. One key finding is that the subcycle interference structures originating from trajectories launched within a time interval of less than 1 femtosecond should be experimentally observable also in low-resolution spectra for longer multicycle pulses.

Arbo, Diego G. [Institute for Astronomy and Space Physics, IAFE (CONICET-UBA), CC 67, Suc. 28 (1428) Buenos Aires (Argentina); Department of Physics, FCEN, University of Buenos Aires (Argentina); Ishikawa, Kenichi L. [Photon Science Center, Graduate School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Schiessl, Klaus; Persson, Emil; Burgdoerfer, Joachim [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/136, A-1040 Vienna (Austria)

2010-10-15

78

Analytic structure of the multichannel Jost matrix for potentials with Coulombic tails  

SciTech Connect

A quantum system is considered that can move in N two-body channels with the potentials that may include the Coulomb interaction. For this system, the Jost matrix is constructed in such a way that all its dependencies on the channel momenta and Sommerfeld parameters are factorized in the form of explicit analytic expressions. It is shown that the two remaining unknown matrices are single-valued analytic functions of the energy and therefore can be expanded in the Taylor series near an arbitrary point within the domain of their analyticity. It is derived a system of first-order differential equations whose solutions determine the expansion coefficients of these series. Alternatively, the unknown expansion coefficients can be used as fitting parameters for parametrizing experimental data similarly to the effective-range expansion. Such a parametrization has the advantage of preserving proper analytic structure of the Jost matrix and can be done not only near the threshold energies, but around any collision or even complex energy. As soon as the parameters are obtained, the Jost matrix (and therefore the S-matrix) is known analytically on all sheets of the Riemann surface, and thus enables one to locate possible resonances.

Rakityansky, S. A. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)] [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Elander, N. [Division of Chemical Physics, Department of Physics, Stockholm University, Stockholm, SE-106 91 (Sweden)] [Division of Chemical Physics, Department of Physics, Stockholm University, Stockholm, SE-106 91 (Sweden)

2013-12-15

79

Effective Coulomb logarithm for one component plasma  

NASA Astrophysics Data System (ADS)

An expression for the effective Coulomb logarithm in one-component-plasma is proposed, which allows to extend the applicability of the classical formula for the self-diffusion coefficient to the strongly coupled regime. The proposed analytical approximation demonstrates reasonable agreement with previous numerical simulation results. Relevance to weakly screened Yukawa systems (and, in particular, complex plasmas) is discussed.

Khrapak, Sergey A.

2013-05-01

80

Effective Coulomb logarithm for one component plasma  

SciTech Connect

An expression for the effective Coulomb logarithm in one-component-plasma is proposed, which allows to extend the applicability of the classical formula for the self-diffusion coefficient to the strongly coupled regime. The proposed analytical approximation demonstrates reasonable agreement with previous numerical simulation results. Relevance to weakly screened Yukawa systems (and, in particular, complex plasmas) is discussed.

Khrapak, Sergey A. [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany)] [Max-Planck-Institut für extraterrestrische Physik, D-85741 Garching (Germany)

2013-05-15

81

Electron in the Aharonov-Bohm potential and in the Coulomb field in 2+1 dimensions  

NASA Astrophysics Data System (ADS)

We obtain exact solutions of the Dirac equation in 2+1 dimensions and the electron energy spectrum in the superposition of the Aharonov-Bohm and Coulomb potentials, which are used to study the Aharonov-Bohm effect for states with continuous and discrete energy spectra. We represent the total scattering amplitude as the sum of amplitudes of scattering by the Aharonov-Bohm and Coulomb potentials. We show that the gauge-invariant phase of the wave function or the energy of the electron bound state can be observed. We obtain a formula for the scattering cross section of spin-polarized electrons scattered by the Aharonov-Bohm potential. We discuss the problem of the appearance of a bound state if the interaction between the electron spin and the magnetic field is taken into account in the form of the two-dimensional Dirac delta function.

Khalilov, V. R.

2006-12-01

82

Auxiliary basis sets for main row atoms and transition metals and their use to approximate Coulomb potentials  

Microsoft Academic Search

.   We present auxilliary basis sets for the atoms H to At – excluding the Lanthanides – optimized for an efficient treatment\\u000a of molecular electronic Coulomb interactions. For atoms beyond Kr our approach is based on effective core potentials to describe\\u000a core electrons. The approximate representation of the electron density in terms of the auxilliary basis has virtually no effect

Karin Eichkorn; Florian Weigend; Oliver Treutler; Reinhart Ahlrichs

1997-01-01

83

Three-potential formalism for the three-body scattering problem with attractive Coulomb interactions  

NASA Astrophysics Data System (ADS)

A three-body scattering process in the presence of Coulomb interaction can be decomposed formally into two-body single channel scattering, two-body multichannel scattering, and genuine three-body scattering. The corresponding integral equations are coupled Lippmann-Schwinger and Faddeev-Merkuriev integral equations. We solve these by applying the Coulomb-Sturmian separable expansion method. We present elastic scattering and reaction cross sections of the e++H system both below and above the H(n=2) threshold. We find excellent agreements with previous calculations in most cases.

Papp, Z.; Hu, C.-Y.; Hlousek, Z. T.; Kónya, B.; Yakovlev, S. L.

2001-06-01

84

Resonant states in semiconductors in a strong magnetic field due to Coulombic impurity potential  

Microsoft Academic Search

The authors have given a method of calculation of the energy ER and width Gamma R of the lowest resonant energy state lying below the bottom of the Landau sub-bands in the presence of a Coulombic impurity (negligible screening). Coupled equations for the longitudinal part of the wavefunction are obtained and integrated numerically for the case of one open and

O. P. Gupta; P. R. Wallace; M. Singh

1986-01-01

85

An "accidental" Symmetry Operator for the Dirac Equation in the Coulomb Potential  

NASA Astrophysics Data System (ADS)

On the basis of the generalization of the theorem about K-odd operators (K is the Dirac's operator), certain linear combination is constructed, which appears to commute with the Dirac Hamiltonian for Coulomb field. This operator coincides with the Johnson and Lippmann operator and is closely connected to the familiar Laplace-Runge-Lenz vector. Our approach guarantees not only derivation of Johnson-Lippmann operator, but simultaneously commutativity with the Dirac Hamiltonian.

Khachidze, Tamari T.; Khelashvili, Anzor A.

86

Parabolic Behavior of Melting and Boiling Points versus Coulomb Potential in Ionic Substances  

Microsoft Academic Search

Melting points and boiling points of alkali fluorides, alkali chlorides, alkali bromides and alkali iodides, have been found to form parabolas as a function of Coulomb energy x{=}q2\\/(rc+ra). Melting points versus x for oxides of cations with rare gas-type outer electronic shells have been found to behave similarly. A primary explanation of such parabolic behaviors of melting points versus x

Tetsuro Nakamura; Yoshiki Takagi

1980-01-01

87

Spin and pseudospin symmetric Dirac particles in the field of Tietz—Hua potential including Coulomb tensor interaction  

NASA Astrophysics Data System (ADS)

Approximate analytical solutions of the Dirac equation for Tietz—Hua (TH) potential including Coulomb-like tensor (CLT) potential with arbitrary spin—orbit quantum number ? are obtained within the Pekeris approximation scheme to deal with the spin—orbit coupling terms ?(? ± 1)r-2. Under the exact spin and pseudospin symmetric limitation, bound state energy eigenvalues and associated unnormalized two-component wave functions of the Dirac particle in the field of both attractive and repulsive TH potential with tensor potential are found using the parametric Nikiforov—Uvarov (NU) method. The cases of the Morse oscillator with tensor potential, the generalized Morse oscillator with tensor potential, and the non-relativistic limits have been investigated.

Sameer, M. Ikhdair; Majid, Hamzavi

2013-09-01

88

The Coulomb static gauge  

Microsoft Academic Search

The existence of gauge conditions involving second-order derivatives of\\u000apotentials is not well known in classical electrodynamics. We introduce one of\\u000athese gauges, the Coulomb static gauge, in which the scalar potential is given\\u000aby the Coulomb static potential. We obtain an explicit expression for the\\u000aassociated vector potential and show how the scalar and vector potentials in\\u000athis gauge

Jose? A. Heras; Mexico D. F. Mexico

2007-01-01

89

Insensitivity to the long-range Coulomb potential in laser-induced elastic scattering of electrons with ions  

NASA Astrophysics Data System (ADS)

Recently, laser-induced electron diffraction has been used to image molecular structures with subangstrom precision and exposure times of a few femtoseconds by Blaga et al. [Nature (London) 483, 194 (2012), 10.1038/nature10820], who treated molecular ions as neutral molecules in the calculation of differential cross section (DCS) for elastic scattering of electrons by molecular ions. In this work, we investigate the long-range and short-range potential effects in elastic scattering of electrons with ions and atoms. It has been found that for incident electron energies above 100 eV and scattering angles greater than 40?, the DCSs of long-range Coulomb potential scattering can be neglected and the DCSs for elastic scattering of electrons with atomic ions and neutral atoms agree well. Therefore, the validity of the treatment in Blaga et al. is verified.

Chen, Zhangjin; Xu, Junliang; Yang, Weifeng; Song, Xiaohong

2013-12-01

90

On the corresponding states law of the Yukawa fluid.  

PubMed

We have analyzed the currently available simulation results as well as performed some additional Monte Carlo simulation for the hard-core attractive Yukawa fluid in order to study its corresponding state behavior. We show that the values of reduced surface tension map onto the master curve and a universal equation of state can be obtained in the wide range of the attractive Yukawa tail length after a certain rescaling of the number density. Some comparisons with other nonconformal potentials are presented and discussed. PMID:18397078

Orea, Pedro; Duda, Yurko

2008-04-01

91

Dynamics of e+ + H(ns) ? e+ + H(n?s) with exponential cosine-screened Coulomb potentials  

NASA Astrophysics Data System (ADS)

The dynamics of ns ? n?s excitations of hydrogen by positron impact with exponential cosine-screened Coulomb potentials (ECSCPs) has been investigated using a distorted-wave theory in momentum space. Making use of a simple variationally determined wave function for the hydrogen atom, it has been possible to obtain the distorted-wave scattering amplitude in a closed analytical form. A detailed study has been made on differential and total cross sections in the energy range 20-250 eV. To the best of our knowledge, such a study on the differential and total cross sections for inelastic positron-hydrogen collisions with ECSCPs is the first reported in the literature.

Nayek, Sujay; Ghoshal, Arijit

2012-03-01

92

Reversible switching of magnetic transitions in NaxCoO2 (x 0.83) by altering the Coulomb potential background  

Microsoft Academic Search

In sodium cobaltate the electrons in the CoO2 layers are subject to a complex Coulomb potential landscape produced by the adjacent sodium ions which, due to their partial mobility, form various ordering patterns. In recent studies we could reversibly switch between distinct magnetic transitions with a Tc of 8 K and 16 K. This was accomplished by preparing different sodium

J. Kanter; Ch. Niedermayer; K. Mattenberger; B. Batlogg

2010-01-01

93

Probing the top-Yukawa coupling in associated Higgs production with a single top quark  

NASA Astrophysics Data System (ADS)

Associated production of the Higgs boson with a single top quark proceeds through Feynman diagrams, which are either proportional to the hW W , top-Yukawa, or the bottom-Yukawa couplings. It was shown in literature that the interference between the top-Yukawa and the gauge-Higgs diagrams can be significant, and thus the measurement of the cross sections can help pin down the sign and the size of the top-Yukawa coupling. Here we perform a detailed study with full detector simulations of such a possibility at the LHC-14 within the current allowed range of hW W and top-Yukawa couplings, using h ? b , ?? , ? + ? - , ZZ * ? 4 ? modes. We found that the LHC-14 has the potential to distinguish the size and the sign of the top-Yukawa coupling. Among the channels the h ? b mode provides the best chance to probe the signal, followed by the h ? ?? mode, which has the advantage of a narrow reconstructed mass peak. We also pointed out that the spatial separation among the final-state particles has the potential in differentiating among various values of the top-Yukawa coupling.

Chang, Jung; Cheung, Kingman; Lee, Jae Sik; Lu, Chih-Ting

2014-05-01

94

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

95

Symmetric potentials of gauged supergravities in diverse dimensions and Coulomb branch of gauge theories  

Microsoft Academic Search

A class of conformally flat and asymptotically anti-de Sitter geometries involving profiles of scalar fields is studied from the point of view of gauged supergravity. The scalars involved in the solutions parametrize the SL(N,R)\\/SO(N) submanifold of the full scalar coset of the gauged supergravity, and are described by a symmetric potential with a universal form. These geometries descend via consistent

M. Cvetic; S. S. Gubser; H. Lü; C. N. Pope

2000-01-01

96

Relativistic Landau–He–McKellar–Wilkens quantization and relativistic bound states solutions for a Coulomb-like potential induced by the Lorentz symmetry breaking effects  

SciTech Connect

In this work, we discuss the relativistic Landau–He–McKellar–Wilkens quantization and relativistic bound states solutions for a Dirac neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present new possible scenarios of studying Lorentz symmetry breaking effects by fixing the space-like vector field background in special configurations. It is worth mentioning that the criterion for studying the violation of Lorentz symmetry is preserving the gauge symmetry. -- Highlights: •Two new possible scenarios of studying Lorentz symmetry breaking effects. •Coulomb-like potential induced by the Lorentz symmetry breaking effects. •Relativistic Landau–He–McKellar–Wilkens quantization. •Exact solutions of the Dirac equation.

Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-970, João Pessoa, PB (Brazil); Belich, H. [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)] [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)

2013-06-15

97

Coulomb crystallization in classical and quantum systems  

NASA Astrophysics Data System (ADS)

Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently a three-dimensional spherical confinement could be created [1] which allows to produce spherical dust crystals containing concentric shells. I will give an overview on our recent results for these ``Yukawa balls'' and compare them to experiments. The shell structure of these systems can be very well explained by using an isotropic statically screened pair interaction. Further, the thermodynamic properties of these systems, such as the radial density distribution are discussed based on an analytical theory [3]. I then will discuss Coulomb crystallization in trapped quantum systems, such as mesoscopic electron and electron hole plasmas in coupled layers [4,5]. These systems show a very rich correlation behavior, including liquid and solid like states and bound states (excitons, biexcitons) and their crystals. On the other hand, also collective quantum and spin effects are observed, including Bose-Einstein condensation and superfluidity of bound electron-hole pairs [4]. Finally, I consider Coulomb crystallization in two-component neutral plasmas in three dimensions. I discuss the necessary conditions for crystals of heavy charges to exist in the presence of a light component which typically is in the Fermi gas or liquid state. It can be shown that their exists a critical ratio of the masses of the species of the order of 80 [5] which is confirmed by Quantum Monte Carlo simulations [6]. Familiar examples are crystals of nuclei in the core of White dwarf stars, but the results also suggest the existence of other crystals, including proton or ?-particle crystals in dense matter and of hole crystals in semiconductors. [1] O. Arp, D. Block, A. Piel, and A. Melzer, Phys. Rev. Lett. 93, 165004 (2004). [2] M. Bonitz, D. Block, O. Arp, V. Golubnychiy, H. Baumgartner, P. Ludwig, A. Piel, and A. Filinov, Phys. Rev. Lett. 96, 075001 (2006). [3] C. Henning, H. Baumgartner, A. Piel, P. Ludwig, V. Golubnychiy, M. Bonitz, and D. Block, Phys. Rev. E 74, 056403 (2006) and Phys. Rev. E (2007). [4] A. Filinov, M. Bonitz, and Yu. Lozovik, Phys. Rev. Lett. 86, 3851 (2001). [5] M. Bonitz, V. Filinov, P. Levashov, V. Fortov, and H. Fehske, Phys. Rev. Lett. 95, 235006 (2005) and J. Phys. A: Math. Gen. 39, 4717 (2006). [6] Introduction to Computational Methods for Many-Body Systems, M. Bonitz and D. Semkat (eds.), Rinton Press, Princeton (2006)

Bonitz, Michael

2007-11-01

98

Relativistic Landau-He-McKellar-Wilkens quantization and relativistic bound states solutions for a Coulomb-like potential induced by the Lorentz symmetry breaking effects  

NASA Astrophysics Data System (ADS)

In this work, we discuss the relativistic Landau-He-McKellar-Wilkens quantization and relativistic bound states solutions for a Dirac neutral particle under the influence of a Coulomb-like potential induced by the Lorentz symmetry breaking effects. We present new possible scenarios of studying Lorentz symmetry breaking effects by fixing the space-like vector field background in special configurations. It is worth mentioning that the criterion for studying the violation of Lorentz symmetry is preserving the gauge symmetry.

Bakke, K.; Belich, H.

2013-06-01

99

Transverse current fluctuations in the Yukawa one-component plasma  

NASA Astrophysics Data System (ADS)

Using numerical simulations, we investigate the wave number and frequency dependent transverse current correlation function CT(k,?) of a single-component fluid with Yukawa interaction potential, also known as the Yukawa one-component plasma. The transverse current correlation function is an important quantity because it contains the microscopic details of the viscoelastic behavior of the fluid. We show that, in the region of densities and temperatures in which shear waves do not propagate, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. As either the density is increased or the temperature decreased, the transverse current correlation function shows additional structure that the simple models fail to capture.

Mithen, James P.

2014-01-01

100

Structure of finite two-dimensional Yukawa lattices: dust crystals.  

PubMed

Dust particles in plasmas are often confined near the boundary between the plasma bulk and the sheath where the gravitation is balanced by electrostatic force. To keep dust particles from running away horizontally, an electrostatic potential is usually applied to the electrode surrounding these dusty plasmas and, under appropriate conditions, we have finite two-dimensional lattices of dust particles. Modeling the interaction between dust particles as the isotropic Yukawa interaction, structures of finite two-dimensional Yukawa systems at low temperatures have been analyzed both by numerical simulations and variational methods. The effect of the correlation energy between dust particles is shown to play an important role in the formation of the one-body distribution in these systems. PMID:11736277

Totsuji, H; Totsuji, C; Tsuruta, K

2001-12-01

101

Minimal SUSY SO(10) and Yukawa unification  

SciTech Connect

The minimal supersymmetric (SUSY) SO(10) model, where only two Higgs multiplets {l_brace}10 Circled-Plus 126-bar{r_brace} are utilized for Yukawa couplings with matter fields, can nicely fit the neutrino oscillation parameters as well as charged fermion masses and mixing angles. In the fitting of the fermion mass matrix data, the largest element in the Yukawa coupling with the 126-bar -plet Higgs (Y{sup 126}) is found to be of order one, so that the right see-saw scale should be provided by Higgs vacuum expectation values (VEVs) of {beta}(10{sup 14}GeV). This fact causes a serious problem, namely, the gauge coupling unification is spoiled because of the presence of many exotic Higgs multiples emerging at the see-saw scale. In order to solve this problem, we consider a unification between bottom-quark and tau Yukawa couplings (b - {tau} Yukawa coupling unification) at the grand unified theory (GUT) scale, due to threshold corrections of superpartners to the Yukawa couplings at the 1 TeV scale. When the b - {tau} Yukawa coupling unification is very accurate, the largest element in Y{sub 126} can become {beta}(0.01), so that the right see-saw scale is realized by the GUT scale VEV and the usual gauge coupling unification is maintained. Since the b - {tau} Yukawa unification alters the Yukawa coupling data at the GUT scale, we re-analyze the fitting of the fermion mass matrix data by taking all the relevant free parameters into account. Unfortunately, we find that no parameter region shows up to give a nice fit for the current neutrino oscillation data and therefore, the usual picture of the gauge coupling unification cannot accommodate the fermion mass matrix data fitting in our procedure.

Okada, Nobuchika [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, Alabama 35487 (United States)

2013-05-23

102

COULOMB CLUSTER DYNAMICS: NUMERICAL SIMULATIONS  

Microsoft Academic Search

Coulomb clusters are complex plasma systems in which the maximum number of macro-sized particles are limited (N 50) and the particles are constrained by an electric potential, usually parabolic, forcing the particles to form \\\\clusters\\

K. W. Smith; L. S. Matthews

103

Bcc crystal-fluid interfacial free energy in Yukawa systems  

NASA Astrophysics Data System (ADS)

We determine the orientation-resolved interfacial free energy between a body-centered-cubic (bcc) crystal and the coexisting fluid for a many-particle system interacting via a Yukawa pair potential. For two different screening strengths, we compare results from molecular dynamics computer simulations, density functional theory, and a phase-field-crystal approach. Simulations predict an almost orientationally isotropic interfacial free energy of 0.12kBT/a2 (with kBT denoting the thermal energy and a the mean interparticle spacing), which is independent of the screening strength. This value is in reasonable agreement with our Ramakrishnan-Yussouff density functional calculations, while a high-order fitted phase-field-crystal approach gives about 2-3 times higher interfacial free energies for the Yukawa system. Both field theory approaches also give a considerable anisotropy of the interfacial free energy. Our result implies that, in the Yukawa system, bcc crystal-fluid free energies are a factor of about 3 smaller than face-centered-cubic crystal-fluid free energies.

Heinonen, V.; Mijailovi?, A.; Achim, C. V.; Ala-Nissila, T.; Rozas, R. E.; Horbach, J.; Löwen, H.

2013-01-01

104

Phase behavior of the modified-Yukawa fluid and its sticky limit  

NASA Astrophysics Data System (ADS)

Simple model systems with short-range attractive potentials have turned out to play a crucial role in determining theoretically the phase behavior of proteins or colloids. However, as pointed out by D. Gazzillo [J. Chem. Phys. 134, 124504 (2011)], one of these widely used model potentials, namely, the attractive hard-core Yukawa potential, shows an unphysical behavior when one approaches its sticky limit, since the second virial coefficient is diverging. However, it is exactly this second virial coefficient that is typically used to depict the experimental phase diagram for a large variety of complex fluids and that, in addition, plays an important role in the Noro-Frenkel scaling law [J. Chem. Phys. 113, 2941 (2000)], which is thus not applicable to the Yukawa fluid. To overcome this deficiency of the attractive Yukawa potential, D. Gazzillo has proposed the so-called modified hard-core attractive Yukawa fluid, which allows one to correctly obtain the second and third virial coefficients of adhesive hard-spheres starting from a system with an attractive logarithmic Yukawa-like interaction. In this work we present liquid-vapor coexistence curves for this system and investigate its behavior close to the sticky limit. Results have been obtained with the self-consistent Ornstein-Zernike approximation (SCOZA) for values of the reduced inverse screening length parameter up to 18. The accuracy of SCOZA has been assessed by comparison with Monte Carlo simulations.

Schöll-Paschinger, Elisabeth; Valadez-Pérez, Néstor E.; Benavides, Ana L.; Castañeda-Priego, Ramón

2013-11-01

105

One-range addition theorems for generalized integer and noninteger ? Coulomb, and exponential type correlated interaction potentials with hyperbolic cosine in position, momentum, and four-dimensional spaces  

NASA Astrophysics Data System (ADS)

The formulae are established in position, momentum, and four-dimensional spaces for the one-range addition theorems of generalized integer and noninteger ? Coulomb, and exponential type correlated interaction potentials with hyperbolic cosine (GCTCP and GETCP HC). These formulae are expressed in terms of one-range addition theorems of complete orthonormal sets of ??-exponential type orbitals (??-ETO), phi?-momentum space orbitals (phi?-MSO), and z?-hyperspherical harmonics (z?-HSH) introduced. The one-range addition theorems obtained can be useful in the electronic structure calculations of atoms and molecules when the GCTCP and GETCP HC in position, momentum, and four-dimensional spaces are employed.

I. Guseinov, I.

2012-06-01

106

A Potential Elastohydrodynamic Origin of Load-Support and Coulomb-Like Friction in Lung/Chest Wall Lubrication.  

PubMed

BACKGROUND: During normal breathing, the mesothelial surfaces of the lung and chest wall slide relative to one another. Experimentally, the shear stresses induced by such reciprocal sliding motion are very small, consistent with hydrodynamic lubrication, and relatively insensitive to sliding velocity, similar to Coulomb-type dry friction. Here we explore the possibility that shear-induced deformation of surface roughness in such tissues could result in bidirectional load supporting behavior, in the absence of solid-solid contact, with shear stresses relatively insensitive to sliding velocity. METHOD OF APPROACH: We consider a lubrication problem with elastic blocks (including the rigid limit) over a planar surface sliding with velocity U , where the normal force is fixed (hence the channel thickness is a dependent variable). One block shape is continuous piecewise linear (V block), the other continuous piecewise smoothly quadratic (Q block). The undeformed elastic blocks are spatially symmetric; their elastic deformation is simplified by taking it to be affine, with the degree of shape asymmetry linearly increasing with shear stress. RESULTS: We find that the V block exhibits nonzero Coulomb-type starting friction in both the rigid and elastic case, and that the smooth Q block exhibits approximate Coulomb friction in the sense that the rate of change of shear force with U is unbounded as U ? 0 ; shear force ?U(1/ 2) in the rigid asymmetric case and ?U(1/ 3) in the (symmetric when undeformed) elastic case. Shear-induced deformation of the elastic blocks results in load supporting behavior for both directions of sliding. CONCLUSIONS: This mechanism could explain load-supporting behavior of deformable surfaces that are symmetrical when undeformed, and may be the source of the weak velocity dependence of friction seen in the sliding of lubricated, but rough, surfaces of elastic media such as the visceral and parietal pleural surfaces of the lung and chest wall. PMID:20890380

Butler, James P; Loring, Stephen H

2008-10-01

107

Analytical evaluation of Coulomb potential generated by multielectron molecule at arbitrary positions in space using one-range addition theorems of Slater type orbitals.  

PubMed

By the use of unsymmetrical one-range addition theorems for Slater type orbitals (STO) and Coulomb potential introduced by the author, the analytical formulae in terms of two- and three-center nuclear attraction integrals, and linear combination coefficients of molecular orbitals are derived for the potential produced by the charges of molecule. These formulae can be useful for the study of interaction between atomic-molecular systems containing any number of closed and open shells when the STO are used in the combined Hartree-Fock-Roothaan (HFR) theory suggested by the author. It should be noted that the symmetry of the potential obtained is the same as the symmetry of the molecule. As an example of application, the calculations have been performed for the potential produced by the ground state of BH (3) molecule[Formula: see text]. PMID:21409569

Guseinov, Israfil I

2011-12-01

108

Coulombic contribution and fat center vortex model  

SciTech Connect

The fat (thick) center vortex model is one of the phenomenological models which is fairly successful to interpret the linear potential between static sources. However, the Coulombic part of the potential has not been investigated by the model yet. In an attempt to get the Coulombic contribution and to remove the concavity of the potentials, we are studying different vortex profiles and vortex sizes.

Rafibakhsh, Shahnoosh; Deldar, Sedigheh [Department of Physics, University of Tehran, P.O. Box 14395/547, Tehran 1439955961 (Iran, Islamic Republic of)

2007-02-27

109

Transverse optical mode in a one-dimensional Yukawa chain.  

PubMed

A transverse optical mode was observed in a one-dimensional Yukawa chain. Charged particles, suspended in a strongly coupled dusty plasma, were arranged in a 1D periodic structure. Particle displacement in the direction perpendicular to the chain was restored by the confining potential. The dispersion relation of phonons was measured, verifying that the optical mode has negative dispersion, with phase and group velocities that are oppositely directed. A theoretical dispersion relation is presented and compared to the experiment and a molecular dynamics simulation. PMID:14754122

Liu, Bin; Avinash, K; Goree, J

2003-12-19

110

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

111

Equation of state and liquid-vapor equilibria of one- and two-Yukawa hard-sphere chain fluids: theory and simulation.  

PubMed

The accuracy of several theories for the thermodynamic properties of the Yukawa hard-sphere chain fluid are studied. In particular, we consider the polymer mean spherical approximation (PMSA), the dimer version of thermodynamic perturbation theory (TPTD), and the statistical associating fluid theory for potentials of variable attractive range (SAFT-VR). Since the original version of SAFT-VR for Yukawa fluids is restricted to the case of one-Yukawa tail, we have extended SAFT-VR to treat chain fluids with two-Yukawa tails. The predictions of these theories are compared with Monte Carlo (MC) simulation data for the pressure and phase behavior of the chain fluid of different length with one- and two-Yukawa tails. We find that overall the PMSA and TPTD give more accurate predictions than SAFT-VR, and that the PMSA is slightly more accurate than TPTD. PMID:15485277

Kalyuzhnyi, Yurij V; McCabe, Clare; Whitebay, Eric; Cummings, Peter T

2004-10-22

112

An exchange-Coulomb model potential energy surface for the Ne-CO interaction. I. Calculation of Ne-CO van der Waals spectra  

NASA Astrophysics Data System (ADS)

Exchange-Coulomb model potential energy surfaces have been developed for the Ne-CO interaction. The initial model is a three-dimensional potential energy surface based upon computed Heitler-London interaction energies and literature results for the long-range induction and dispersion energies, all as functions of interspecies distance, the orientation of CO relative to the interspecies axis, and the bond length of the CO molecule. Both a rigid-rotor model potential energy surface, obtained by setting the CO bond length equal to its experimental spectroscopic equilibrium value, and a vibrationally averaged model potential energy surface, obtained by averaging the stretching dependence over the ground vibrational motion of the CO molecule, have been constructed from the full data set. Adjustable parameters in each model potential energy surface have been determined through fitting a selected subset of pure rotational transition frequencies calculated for the 20Ne-12C12O isotopolog to precisely known experimental values. Both potential energy surfaces provide calculated results for a wide range of available experimental microwave, millimeter-wave, and midinfrared Ne-CO transition frequencies that are generally far superior to those obtained using the best current literature potential energy surfaces. The vibrationally averaged CO ground state potential energy surface, employed together with a potential energy surface obtained from it by replacing the ground vibrational state average of the CO stretching dependence of the potential energy surface by an average over the first excited CO vibrational state, has been found to be particularly useful for computing and/or interpreting mid-IR transition frequencies in the Ne-CO dimer.

Dham, Ashok K.; McCourt, Frederick R. W.; Meath, William J.

2009-06-01

113

Nonlinear Magnetoplasmons in Strongly Coupled Yukawa Plasmas  

NASA Astrophysics Data System (ADS)

The existence of plasma oscillations at multiples of the magnetoplasmon frequency in a strongly coupled two-dimensional magnetized Yukawa plasma is reported, based on extensive molecular dynamics simulations. These modes are the analogues of Bernstein modes which are renormalized by strong interparticle correlations. Their properties are theoretically explained by a dielectric function incorporating the combined effect of a magnetic field, strong correlations and finite temperature.

Bonitz, M.; Donkó, Z.; Ott, T.; Kählert, H.; Hartmann, P.

2010-07-01

114

Mach Cones in Three-Dimensional Yukawa Crystals  

NASA Astrophysics Data System (ADS)

Mach cones have been observed in two-dimensional dusty plasma experiments (D. Samsonov et al., Phys. Rev. Lett., 83, 3649, 1999) and molecular dynamics (MD) simulations assuming that the dust particles interact via a Yukawa potential (Z. W. Ma and A. Bhattacharjee, Phys. Plasmas, 9, 3349, 2002). We present new simulation results of Mach cones in three-dimensional Yukawa crystals excited by external laser forcing. As is well known, these crystals can be of the bcc and fcc type, and experiments have produced crystals with both types coexisting. Under a variety of conditions, our simulations show stable three-dimensional Mach cones with a tent structure. While the two-dimensional projection of these cones resemble the multiple cone structure of two-dimensional cones, they need larger dust charge and higher-amplitude forcing for their excitation. We present results on the effect of melting on these Mach cones, and their structures in the near-field and far-field regions.

Qian, Xin; Bhattacharjee, Amitava

2006-10-01

115

Coulombic charge ice  

NASA Astrophysics Data System (ADS)

We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.

McClarty, P. A.; O'Brien, A.; Pollmann, F.

2014-05-01

116

Entropic Corrections to Coulomb's Law  

NASA Astrophysics Data System (ADS)

Two well-known quantum corrections to the area law have been introduced in the literatures, namely, logarithmic and power-law corrections. Logarithmic corrections, arises from loop quantum gravity due to thermal equilibrium fluctuations and quantum fluctuations, while, power-law correction appears in dealing with the entanglement of quantum fields in and out the horizon. Inspired by Verlinde's argument on the entropic force, and assuming the quantum corrected relation for the entropy, we propose the entropic origin for the Coulomb's law in this note. Also we investigate the Uehling potential as a radiative correction to Coulomb potential in 1-loop order and show that for some value of distance the entropic corrections of the Coulomb's law is compatible with the vacuum-polarization correction in QED. So, we derive modified Coulomb's law as well as the entropy corrected Poisson's equation which governing the evolution of the scalar potential ?. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.

Hendi, S. H.; Sheykhi, A.

2012-04-01

117

Bound state solutions of the Dirac equation with the Deng—Fan potential including a Coulomb tensor interaction  

NASA Astrophysics Data System (ADS)

Approximate analytical solutions of the Dirac equation in the case of pseudospin and spin symmetry limits are investigated under the Deng—Fan potential by applying the asymptotic iteration method for the arbitrary quantum numbers n and ?. Some of the numerical results are also represented in both pseudospin symmetry and spin symmetry limits.

Ortakaya, S.; Hassanabadi, H.; H. Yazarloo, B.

2014-03-01

118

Crystalline multilayers of the confined Yukawa system  

NASA Astrophysics Data System (ADS)

The phase diagram of Yukawa particles confined between two parallel hard walls is calculated at zero temperature beyond the bilayer regime by lattice-sum-minimization. Tuning the screening, a rich phase behavior is found in the regime bounded by stable two triangular layers and three square layers. In this regime, alternating prism phases with square and triangular basis, structures derived from a hcp bulk lattice, and a structure with two outer layers and two inner staggered rectangular layers, reminiscent of a Belgian waffle iron, are stable. These structures are verifiable in experiments on charged colloidal suspensions and dusty plasma sheets.

O?uz, E. C.; Messina, R.; Löwen, H.

2009-04-01

119

Ab initio nonperturbative calculations in Yukawa model  

NASA Astrophysics Data System (ADS)

We give a brief review of a nonperturbative approach to field theory based on the decomposition of the state vector in Fock components, and on the covariant formulation of light-front dynamics, together with the Fock sector dependent renormalization scheme. The approach is applied to the calculation, in the three-body Fock space truncation, of electromagnetic form factors of a fermion in the Yukawa model (in particular, of anomalous magnetic moment). Once the renormalization conditions are properly taken into account, the anomalous magnetic moment does not depend on the regularization scale, when the latter is much larger than the physical masses.

Karmanov, V. A.

2014-06-01

120

Light stop from b- ? Yukawa unification  

NASA Astrophysics Data System (ADS)

We show that b- ? Yukawa unification can be successfully implemented in the constrained minimal supersymmetric model and it yields the stop co-annihilation scenario. The lightest supersymmetric particle is a bino-like dark matter neutralino, which is accompanied by a 10-20% heavier stop of mass ?100-330 GeV. We highlight some benchmark points which show a gluino with mass ?0.6-1.7 TeV, while the first two family squarks and all sleptons have masses in the multi-TeV range.

Gogoladze, Ilia; Raza, Shabbar; Shafi, Qaisar

2012-01-01

121

Yukawa interactions and supersymmetric electroweak baryogenesis.  

PubMed

We analyze the quantum transport equations for supersymmetric electroweak baryogenesis including previously neglected bottom and tau Yukawa interactions and show that they imply the presence of a previously unrecognized dependence of the cosmic baryon asymmetry on the spectrum of third generation quark and lepton superpartners. For fixed values of the CP-violating phases in the supersymmetric theory, the baryon asymmetry can vary in both magnitude and sign as a result of the squark and slepton mass dependence. For light, right-handed top and bottom quark superpartners, the baryon number creation can be driven primarily by interactions involving third generation leptons and their superpartners. PMID:19257576

Chung, Daniel J H; Garbrecht, Björn; Ramsey-Musolf, Michael J; Tulin, Sean

2009-02-13

122

Electronic structure of antifluorite Cu2X (X = S, Se, Te) within the modified Becke-Johnson potential plus an on-site Coulomb U  

NASA Astrophysics Data System (ADS)

The traditional photon absorbers Cu2-xX (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu2X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu2X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu2S and Cu2Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials.

Zhang, Yubo; Wang, Youwei; Xi, Lili; Qiu, Ruihao; Shi, Xun; Zhang, Peihong; Zhang, Wenqing

2014-02-01

123

Density fluctuations in the Yukawa one-component plasma: an accurate model for the dynamical structure factor.  

PubMed

Using numerical simulations, we investigate the equilibrium dynamics of a single-component fluid with Yukawa interaction potential. We show that, for a wide range of densities and temperatures, the dynamics of the system are in striking agreement with a simple model of generalized hydrodynamics. Since the Yukawa potential can describe the ion-ion interactions in a plasma, our results have significant applicability for both analyzing and interpreting the results of x-ray scattering data from high-power lasers and fourth-generation light sources. PMID:22181277

Mithen, James P; Daligault, Jérôme; Crowley, Basil J B; Gregori, Gianluca

2011-10-01

124

Equation of state and liquid-vapor equilibria of one- and two-Yukawa hard-sphere chain fluids: Theory and simulation  

Microsoft Academic Search

The accuracy of several theories for the thermodynamic properties of the Yukawa hard-sphere chain fluid are studied. In particular, we consider the polymer mean spherical approximation (PMSA), the dimer version of thermodynamic perturbation theory (TPTD), and the statistical associating fluid theory for potentials of variable attractive range (SAFT-VR). Since the original version of SAFT-VR for Yukawa fluids is restricted to

Yurij V. Kalyuzhnyi; Clare McCabe; Eric Whitebay; Peter T. Cummings

2004-01-01

125

Noncommutative Coulombic monopole  

SciTech Connect

We have constructed the appropriate Hamiltonian of the noncommutative Coulombic monopole (i.e. the noncommutative hydrogen atom with a monopole). The energy levels of this system have been calculated, discussed, and compared with the noncommutative hydrogen atom ones. The main emphasis is put on the ground state. In addition, the Stark effect for the noncommutative Coulombic monopole has been studied.

Bellucci, Stefano [INFN-Laboratori Nazionali di Frascati, P. O. Box 13, I-00044, Frascati (Italy); Yeranyan, Armen [Yerevan State University, Alex Manoogian St., 1, Yerevan, 375025 (Armenia)

2005-10-15

126

Noncommutative Coulombic monopole  

Microsoft Academic Search

We have constructed the appropriate Hamiltonian of the noncommutative Coulombic monopole (i.e. the noncommutative hydrogen atom with a monopole). The energy levels of this system have been calculated, discussed, and compared with the noncommutative hydrogen atom ones. The main emphasis is put on the ground state. In addition, the Stark effect for the noncommutative Coulombic monopole has been studied.

Stefano Bellucci; Armen Yeranyan

2005-01-01

127

Thermodynamic and structural properties of mixed colloids represented by a hard-core two-Yukawa mixture model fluid: Monte Carlo simulations and an analytical theory  

NASA Astrophysics Data System (ADS)

The interaction between colloidal particles is well represented by a hard-core two-Yukawa potential. In order to assess the accuracy of theoretical predictions for the thermodynamic and structural properties of mixed colloids, standard Monte Carlo simulations are carried out for the hard-core two-Yukawa mixtures. In the simulations, one range parameter in the two-Yukawa potential is taken as 1.8 or 2.8647, and another is taken as 4, 8, or 13.5485. Both attractive and repulsive dominant cases of the potential outside the hard core are considered. The effects of temperature, density, composition, size and energy parameter ratios on internal energy, compressibility factor, and radial distribution function are investigated extensively. Theoretical calculations are performed in the framework of analytical solution for the Ornstein-Zernike equation with the first-order mean spherical approximation (FMSA). Our analysis shows that the FMSA is very accurate for the prediction of the compressibility factor of the hard-core two-Yukawa mixtures at all conditions studied. The FMSA generally predicts accurate internal energy, but overestimates the internal energy of the systems at lower temperatures. Furthermore, we found that a simplified exponential version of the FMSA predicts fairly good radial distribution function at contact for the mixed two-Yukawa fluids. The comparison of the theoretical compressibility factor with that from the Monte Carlo simulations suggests that the FMSA can be used to investigate the fluid-fluid equilibria of hard-core two-Yukawa mixtures.

Yu, Yang-Xin; Jin, Lin

2008-01-01

128

Diffusion in Coulomb crystals.  

PubMed

Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter ?=175 to Coulomb parameters up to ?=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous. PMID:21867316

Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

2011-07-01

129

Gaussian and finite-element Coulomb method for the fast evaluation of Coulomb integrals  

NASA Astrophysics Data System (ADS)

The authors propose a new linear-scaling method for the fast evaluation of Coulomb integrals with Gaussian basis functions called the Gaussian and finite-element Coulomb (GFC) method. In this method, the Coulomb potential is expanded in a basis of mixed Gaussian and finite-element auxiliary functions that express the core and smooth Coulomb potentials, respectively. Coulomb integrals can be evaluated by three-center one-electron overlap integrals among two Gaussian basis functions and one mixed auxiliary function. Thus, the computational cost and scaling for large molecules are drastically reduced. Several applications to molecular systems show that the GFC method is more efficient than the analytical integration approach that requires four-center two-electron repulsion integrals. The GFC method realizes a near linear scaling for both one-dimensional alanine ?-helix chains and three-dimensional diamond pieces.

Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

2007-04-01

130

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

131

Computation of negative-energy Coulomb functions  

Microsoft Academic Search

Two new uniform semiclassical methods are presented for calculating negative-energy Coulomb functions, a highly accurate uniform Airy approximation in the vicinity of the outer classical turning point, and a parabolic uniform approximation to cover energy ranges close to and below the minimum in the centrifugally corrected Coulomb potential-energy curve. Test calculations at half-integer quantum numbers show excellent agreement with numerical

Miyabi Hiyama; Mark S. Child

2001-01-01

132

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

133

Kelvin Helmholtz instability in strongly coupled Yukawa liquids.  

PubMed

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 ? 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. PMID:20867109

J, Ashwin; Ganesh, R

2010-05-28

134

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

135

Effect of external drive on strongly coupled Yukawa systems: A nonequilibrium molecular dynamics study  

NASA Astrophysics Data System (ADS)

Using nonequilibrium molecular dynamics (MD) simulations behavior of three-dimensional (3D) Yukawa system has been studied in the presence of a small amplitude drive along one direction (say ? ). This drive has the general form V=V0cos(kLz)?(t-t0) , where ?(t-t0) is a Heaviside step function in time at t=t0 and kL=2?/L , L being the size of the system; V0 is considered small compared to average interparticle potential energy. In particular, a 3D equilibrated Yukawa crystal (bcc) near solid-liquid transition is subjected to an external drive at times t?t0 at the largest possible scale. For a given kL it is observed that there exists a critical amplitude (V0c) of the external drive below which the crystalline order is preserved and above which (V0?V0c) the transition from bcc to strongly coupled Yukawa liquid is observed. This critical amplitude (V0c) is sensitive to the location of the Yukawa solid in the (?,?) phase space. Various signatures of melting, transients, and steady state in the presence of this drive are elucidated using extensive MD diagnostics such as loss of long-range crystalline order, change in diffusion from subnormal to normal, and the fall of transversal shear peak in the Fourier transform of the velocity autocorrelation function. The mechanism of heating in the transient state is attributed to the local heating of the system where the forces are maximum. It is shown that these local hot regions dissipate heat into surrounding regions ultimately leading to a uniform temperature throughout the system. Ion streaming due to external field has been neglected.

Ashwin, J.; Ganesh, R.

2009-11-01

136

Effect of external drive on strongly coupled Yukawa systems: a nonequilibrium molecular dynamics study.  

PubMed

Using nonequilibrium molecular dynamics (MD) simulations behavior of three-dimensional (3D) Yukawa system has been studied in the presence of a small amplitude drive along one direction (say z[over ] ). This drive has the general form V=V_{0} cos(k_{L}z)Theta(t-t_{0}) , where Theta(t-t_{0}) is a Heaviside step function in time at t=t_{0} and k_{L}=2pi/L , L being the size of the system; V0 is considered small compared to average interparticle potential energy. In particular, a 3D equilibrated Yukawa crystal (bcc) near solid-liquid transition is subjected to an external drive at times t> or =t_{0} at the largest possible scale. For a given k_{L} it is observed that there exists a critical amplitude (V_{0};{c}) of the external drive below which the crystalline order is preserved and above which (V_{0}> or =V_{0};{c}) the transition from bcc to strongly coupled Yukawa liquid is observed. This critical amplitude (V_{0};{c}) is sensitive to the location of the Yukawa solid in the (kappa,Gamma) phase space. Various signatures of melting, transients, and steady state in the presence of this drive are elucidated using extensive MD diagnostics such as loss of long-range crystalline order, change in diffusion from subnormal to normal, and the fall of transversal shear peak in the Fourier transform of the velocity autocorrelation function. The mechanism of heating in the transient state is attributed to the local heating of the system where the forces are maximum. It is shown that these local hot regions dissipate heat into surrounding regions ultimately leading to a uniform temperature throughout the system. Ion streaming due to external field has been neglected. PMID:20365084

J, Ashwin; Ganesh, R

2009-11-01

137

Extended optical model analyses of elastic scattering and fusion cross sections for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies using a folding potential  

SciTech Connect

Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous {chi}{sup 2} analyses are performed for elastic scattering and fusion cross section data for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies. A folding potential is used as the bare potential. It is found that the real part of the resultant DR part of the polarization potential is repulsive, which is consistent with the results from the continuum discretized coupled channel (CDCC) calculations and the normalization factors needed for the folding potentials. Further, it is found that both DR and fusion parts of the polarization potential satisfy separately the dispersion relation.

So, W. Y.; Udagawa, T.; Kim, K. S.; Hong, S. W.; Kim, B. T. [Department of Physics, University of Texas, Austin, Texas 78712 (United States); Department of Liberal Arts and Science, Hankuk Aviation University, Koyang 412-791 (Korea, Republic of); Department of Physics and Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2007-02-15

138

Binary dusty plasma Coulomb balls  

NASA Astrophysics Data System (ADS)

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.

Apolinario, S. W. S.; Peeters, F. M.

2011-04-01

139

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

2011-04-01

140

Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method.  

PubMed

We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach. PMID:20590181

Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko

2010-06-28

141

Efficient evaluation of the Coulomb force in the Gaussian and finite-element Coulomb method  

NASA Astrophysics Data System (ADS)

We propose an efficient method for evaluating the Coulomb force in the Gaussian and finite-element Coulomb (GFC) method, which is a linear-scaling approach for evaluating the Coulomb matrix and energy in large molecular systems. The efficient evaluation of the analytical gradient in the GFC is not straightforward as well as the evaluation of the energy because the SCF procedure with the Coulomb matrix does not give a variational solution for the Coulomb energy. Thus, an efficient approximate method is alternatively proposed, in which the Coulomb potential is expanded in the Gaussian and finite-element auxiliary functions as done in the GFC. To minimize the error in the gradient not just in the energy, the derived functions of the original auxiliary functions of the GFC are used additionally for the evaluation of the Coulomb gradient. In fact, the use of the derived functions significantly improves the accuracy of this approach. Although these additional auxiliary functions enlarge the size of the discretized Poisson equation and thereby increase the computational cost, it maintains the near linear scaling as the GFC and does not affects the overall efficiency of the GFC approach.

Kurashige, Yuki; Nakajima, Takahito; Sato, Takeshi; Hirao, Kimihiko

2010-06-01

142

Attosecond molecular Coulomb explosion  

NASA Astrophysics Data System (ADS)

Molecular Coulomb explosion has been utilized as a precise temporal clock for probing ultrafast motion of nucleus and electrons during chemical reactions. With an intense attosecond pulse train in the extreme ultraviolet region, we were able to image attosecond molecular Coulomb explosion via two photon double ionization process. The present autocorrelation measurement, from which the duration of the attosecond pulse train was determined to be 300 as, serves as the first step toward a pump-and-probe measurement of molecular dynamics with attosecond temporal resolution.

Okino, Tomoya; Yamanouchi, Kaoru; Shimizu, Toshihiko; Furusawa, Kentaro; Hasegawa, Hirokazu; Nabekawa, Yasuo; Midorikawa, Katsumi

2006-12-01

143

Heavy-ion fusion cross sections of weakly bound 9Be on 27Al, 64Zn and tightly bound 16O on 64Zn target using Coulomb and proximity potential  

NASA Astrophysics Data System (ADS)

The total fusion cross sections for the fusion of weakly bound 9Be on 27Al and 64Zn targets at near and above the barrier have been calculated using one dimensional barrier penetration model, taking scattering potential as the sum of Coulomb and proximity potential and the calculated values are compared with experimental data. For the purpose of comparison of the fusion of weakly bound projectiles and strongly bound projectiles, the total fusion cross sections for the reaction of tightly bound nucleus 16O on 64Zn have also been computed using a similar procedure. The calculated values of total fusion cross sections in all cases are compared with coupled channel calculations using the code CCFULL. The computed cross sections using Coulomb and proximity potential explain the fusion reactions well in both cases of weakly bound and strongly bound projectiles. Reduced reaction cross sections for the systems Be9+Al27, Be9+Zn64 and O16+Zn64 have also been described.

Santhosh, K. P.; Bobby Jose, V.

2014-02-01

144

Nondecoupling of Heavy Fermions and a Special Yukawa Texture  

NASA Astrophysics Data System (ADS)

Talk based on work entitled “Yukawa textures, new physics and nondecoupling,” done in collaboration with G. C. Branco and J. I. Silva-Marcos, arXiv:hep-ph/0612252, to appear in Phys. Rev. D. In this work we pointed out that New Physics can play an important rôle in rescuing some of the Yukawa texture zero ansätze which would otherwise be eliminated by the recent, more precise measurements of VCKM. We have shown that the presence of an isosinglet vector-like quark which mixes with standard quarks, can render viable a particularly interesting four texture zero Yukawa ansatz. The crucial point is the nondecoupling of the effects of the isosinglet quark, even for arbitrary large values of its mass.

Rebelo, M. N.

145

Coulomb Friction Damper  

NASA Technical Reports Server (NTRS)

Standard hydraulic shock absorber modified to form coulomb (linear friction) damper. Device damps very small velocities and is well suited for use with large masses mounted on soft springs. Damping force is easily adjusted for different loads. Dampers are more reliable than fluid dampers and also more economical to build and to maintain.

Appleberry, W. T.

1983-01-01

146

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

2010-06-11

147

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

148

Higgs and sparticle spectroscopy with Gauge-Yukawa unification  

NASA Astrophysics Data System (ADS)

We explore the Higgs and sparticle spectroscopy of supersymmetric SU(4) c × SU(2) L × SU(2) R models in which the three MSSM gauge couplings and third family ( t- b- ?) Yukawa couplings are all unified at M GUT. This class of models can be obtained via compactification of a higher dimensional theory. Allowing for opposite sign gaugino masses and varying m t within 1 ? of its current central value yields a variety of gauge-Yukawa unification as well as WMAP compatible neutralino dark matter solutions. They include mixed bino-Higgsino dark matter, stau and gluino coannihilation scenarios, and the A-resonance solution.

Gogoladze, Ilia; Khalid, Rizwan; Raza, Shabbar; Shafi, Qaisar

2011-06-01

149

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

150

Yukawa and the Birth of Meson Theory: Fiftieth Anniversary for Nuclear Forces.  

ERIC Educational Resources Information Center

In 1935 physicist Hideki Yukawa proposed the meson theory of nuclear forces. Background, influences, and chronology of Yukawa's work are presented and discussed. Yukawa was supported in his meson idea by Japan's strong emphasis on intuitive and creative approaches which are also evident in subsequent developments in that country. (DH)

Spradley, Joseph L.

1985-01-01

151

Thermodynamic behavior of the generalized scalar Yukawa model in a magnetic background  

NASA Astrophysics Data System (ADS)

We study the thermodynamic behavior of the generalized scalar Yukawa model, composed of a complex scalar field interacting with scalar and vector fields. Thermal effects are treated in the framework of generalized zeta-functions. For the case of vanishing effective chemical potential, we find a vanishing contribution from the vector field. We focus on the analysis of the phase structure of this model at effective chemical equilibrium, under change of values of the relevant parameters of the model, looking specially to the influence of the magnetic background on the phase structure.

Abreu, L. M.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Nery, E. S.; Rodrigues da Silva, R.

2014-04-01

152

Vapor-liquid surface tension of strong short-range Yukawa fluid.  

PubMed

The thermodynamic properties of strong short-range attractive Yukawa fluids, ? = 10, 9, 8, and 7, are determined by combining the slab technique with the standard and the replica exchange Monte Carlo (REMC) methods. A good agreement was found among the coexistence curves of these systems calculated by REMC and those previously reported in the literature. However, REMC allows exploring the coexistence at lower temperatures, where dynamics turns glassy. To obtain the surface tension we employed, for both methods, a procedure that yields the pressure tensor components for discontinuous potentials. The surface tension results obtained by the standard MC and REMC techniques are in good agreement. PMID:21513403

Odriozola, G; Bárcenas, M; Orea, P

2011-04-21

153

Electron Radiative Transitions in a Coulomb Field  

Microsoft Academic Search

Free-free, bound-free, and bound-bound Gaunt factors and oscillator ; strengths were computed for electrons in a pure Coulomb potential. Numerical ; results are presented for a wide range of electron and photon energies. In ; addition, for the free-free case, average Gaunt factors and the rate of ; bremsstrahlung production were obtained as functions of temperature for a ; Boltzmann

W. J. Karzas; R. Latter

1961-01-01

154

Coulomb crystallization in classical and quantum systems  

Microsoft Academic Search

Coulomb crystallization occurs in one-component plasmas when the average interaction energy exceeds the kinetic energy by about two orders of magnitude. A simple road to reach such strong coupling consists in using external confinement potentials the strength of which controls the density. This has been succsessfully realized with ions in traps and storage rings and also in dusty plasma. Recently

Michael Bonitz

2007-01-01

155

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

156

Predictions from an anomalous U(1) model of Yukawa hierarchies  

Microsoft Academic Search

We present a supersymmetric standard model with three gauged Abelian symmetries of a type commonly found in superstrings. One is anomalous; the other two are E6 family symmetries. It has a vacuum in which only these symmetries are broken by stringy effects. It reproduces all observed quark and charged lepton Yukawa hierarchies and the value of the Weinberg angle. It

Nikolaos Irges; Stéphane Lavignac; Pierre Ramond

1998-01-01

157

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

158

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

159

Hyperphysics -- Coulomb's Law  

NSDL National Science Digital Library

This web page, authored by Rod Nave of Georgia State University, provides a concise, yet thorough explanation of Coulomb's Law and how it it is used to determine the electric force between charges. A Javascript calculator is available to compute forces between charges. Links are available for users to access related items or delve more deeply into electromagnetic forces. This item is part of a large hyper-linked resource that covers most of physics, with extensive use of concept maps.

Nave, Rod

2009-12-10

160

Phase diagram and surface tension of the hard-core attractive Yukawa model of variable range: Monte Carlo simulations.  

PubMed

The liquid-vapor phase diagram and surface tension for hard-core Yukawa potential with 4

Duda, Yurko; Romero-Martínez, Ascención; Orea, Pedro

2007-06-14

161

Interfacial and coexistence properties of soft spheres with a short-range attractive Yukawa fluid: Molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations have been carried out to obtain the interfacial and coexistence properties of soft-sphere attractive Yukawa (SAY) fluids with short attraction range, ? = 10, 9, 8, 7, 6, and 5. All our simulation results are new. These data are also compared with the recently reported results in the literature of hard-core attractive Yukawa (HAY) fluids. We show that the interfacial and coexistence properties of both potentials are different. For the surveyed systems, here we show that all coexistence curves collapse into a master curve when we rescale with their respective critical points and the surface tension curves form a single master curve when we plot ?* vs. T/Tc.

González-Melchor, Minerva; Hernández-Cocoletzi, Gregorio; López-Lemus, Jorge; Ortega-Rodríguez, Alejandro; Orea, Pedro

2012-04-01

162

Coulomb explosion of nitrogen and oxygen molecules through non-Coulombic states.  

PubMed

We have systematically studied Coulomb explosion of nitrogen and oxygen molecules in intense 8 and 24 fs laser pulses. In the experiment, we explicitly separated all explosion pathways through coincident measurements. The high resolution kinetic energy releases (KERs) and the exotic angular distributions of atomic ions provide direct evidence that Coulomb explosion occurs through non-Coulombic states. In the theory, we calculated dissociation potential energy curves (PECs) of nitrogen and oxygen molecules and their multicharged molecular ions using multiconfiguration second-order perturbation theory. The results indicate that Coulomb potentials are close to the accurate PECs of multicharged molecular ions only when the internuclear distance is larger than 3 Å. In comparison with the experimental observations and the theoretical calculations, we determined the internuclear distance when Coulombic explosion occurs. It is near the equilibrium distance of the neutral molecules in the case of 8 fs laser pulses and expands gradually with the increase of the charge state of the molecular ions in the case of 24 fs laser pulses. PMID:21881654

Wu, Chengyin; Yang, Yudong; Wu, Zhifeng; Chen, Bozhen; Dong, Hua; Liu, Xianrong; Deng, Yongkai; Liu, Hong; Liu, Yunquan; Gong, Qihuang

2011-11-01

163

The Coulomb Luttinger liquid  

NASA Astrophysics Data System (ADS)

The effect of long-ranged Coulomb interaction on the low energy properties (momentum distribution function, density of states, electron spectral function, and 4kF correlation function) of one-dimensional electron systems is determined theoretically. Over a wide, physically relevant energy range the behavior is found to be well described by the conventional, short-ranged interacting, Luttinger liquid results, with a scale-dependent effective exponent. An accurate empirical formula for the effective exponent is presented. We also discuss the qualitative line shape of the electron spectral function. (D. W. Wang, A. J. Millis, and S. Das Sarma, cond-mat/0010241 (2000))

Wang, Daw-Wei; Millis, Andrew J.; Das Sarma, S.

2001-03-01

164

Renormalization-group flows and fixed points in Yukawa theories  

NASA Astrophysics Data System (ADS)

We study renormalization-group flows in Yukawa theories with massless fermions, including determination of fixed points and curves that separate regions of different flow behavior. We assess the reliability of perturbative calculations for various values of Yukawa coupling y and quartic scalar coupling ? by comparing the properties of flows obtained with the beta functions of these couplings calculated to different orders in the loop expansion. The results provide a determination of the region in y and ? where calculations up to two loops can yield reasonably reliable results. In the regime of weak couplings where the perturbative calculations are most reliable, we find that the theories have no nontrivial fixed points, and the flow is toward a free theory in the infrared.

Mølgaard, Esben; Shrock, Robert

2014-05-01

165

Effective Hamiltonian for bound states in Yukawa theory  

SciTech Connect

A generalization of the Gell-Mann–Low theorem is applied to lowest nontrivial order to determine an effective Hamiltonian for two-fermion states in relativistic Yukawa theory. The consistency of the corresponding effective Schrödinger equation is thoroughly investigated in various aspects, among others the nonrelativistic and one-body limits, and the small-distance or large-momentum regime of the bound state solutions is discussed in detail. -- Highlights: •A generalization of the Gell-Mann–Low theorem is applied to Yukawa theory. •The effective Hamiltonian for two-fermion states is derived to lowest order. •The nonrelativistic and one-body limits are consistent. •The large-momentum behavior of the bound-state solutions is analyzed. •A critical value for the coupling constant is determined.

Weber, Axel, E-mail: axel@ifm.umich.mx

2013-07-15

166

Non-renormalizable Yukawa interactions and Higgs physics  

NASA Astrophysics Data System (ADS)

We explore a scenario in the Standard Model in which dimension-four Yukawa couplings are forbidden by a symmetry, and the Yukawa interactions are dominated by effective dimension-six interactions. In this case, the Higgs interactions to the fermions are enhanced in a large way, whereas its interaction with the gauge bosons remains the same as in the Standard Model. In hadron colliders, Higgs boson production via gluon-gluon fusion increases by a factor of nine. Higgs decay widths to fermion-antifermion pairs also increase by the same factor, whereas the decay widths to photon-photon and ?Z are reduced. Current Tevatron exclusion range for the Higgs mass increases to ?146-222 GeV in our scenario, and new physics must appear at a scale below a TeV.

Murdock, Z.; Nandi, S.; Rai, Santosh Kumar

2011-10-01

167

Contribution of plasminos to the shear viscosity of a hot and dense Yukawa-Fermi gas  

NASA Astrophysics Data System (ADS)

We determine the shear viscosity of a hot and dense Yukawa-Fermi gas, using the standard Green-Kubo relation, according to which the shear viscosity is given by the retarded correlator of the traceless part of the viscous energy-momentum tensor. We approximate this retarded correlator using a one-loop skeleton expansion, and express the bosonic and fermionic shear viscosities, ?b and ?f, in terms of bosonic and fermionic spectral widths, ?b and ?±. Here, the subscripts ± correspond to normal and collective (plasmino) excitations of fermions. We study, in particular, the effect of these excitations on thermal properties of ?f[?±]. To do this, we determine first the dependence of ?b and ?± on momentum p, temperature T, chemical potential ? and ?0?mb0/mf0, in a one-loop perturbative expansion in the orders of the Yukawa coupling. Here, mb0 and mf0 are T- and ?-independent bosonic and fermionic masses, respectively. We then numerically determine ?b[?b] and ?f[?±], and study their thermal properties. It turns out that whereas ?b and ?+ decrease with increasing T or ?, ?- increases with increasing T or ?. This behavior qualitatively changes by adding thermal corrections to mb0 and mf0, while the difference between ?+ and ?- keeps increasing with increasing T or ?. Moreover, ?b (?f) increases (decreases) with increasing T or ?. We show that the effect of plasminos on ?f becomes negligible with increasing (decreasing) T (?).

Sadooghi, N.; Taghinavaz, F.

2014-06-01

168

Exponentially spread dynamical Yukawa couplings from nonperturbative chiral symmetry breaking in the dark sector  

NASA Astrophysics Data System (ADS)

We propose a new paradigm for generating exponentially spread standard model Yukawa couplings from a new U(1)F gauge symmetry in the dark sector. Chiral symmetry is spontaneously broken among dark fermions that obtain nonvanishing masses from a nonperturbative solution to the mass gap equation. The necessary ingredient for this mechanism to work is the existence of higher-derivative terms in the dark U(1)F theory, or equivalently the existence of Lee-Wick ghosts, that (i) allow for a nonperturbative solution to the mass gap equation in the weak coupling regime of the Abelian theory and (ii) induce exponential dependence of the generated masses on dark fermion U(1)F quantum numbers. The generated flavor and chiral symmetry breaking in the dark sector is transferred to the standard model Yukawa couplings at the one-loop level via Higgs portal-type scalar messenger fields. The latter carry quantum numbers of squarks and sleptons. A new intriguing phenomenology is predicted that could be potentially tested at the LHC, provided the characteristic mass scale of the messenger sector is accessible at the LHC as is suggested by naturalness arguments.

Gabrielli, Emidio; Raidal, Martti

2014-01-01

169

Beam-Plasma Interaction and Instabilities in a 2D Yukawa Plasma  

NASA Astrophysics Data System (ADS)

In a complex plasma, penetrating charged particle beams may lead to beam-plasma instabilities. When either the plasma, the beam, or both, are strongly interacting [1], the features of the instability are different from those in a weakly coupled plasma. We consider the case when a 2D dusty plasma forms a lattice, and the beam is moving in the lattice plane. Both the grains and the beam particles interact through a Yukawa potential; the beam particles are weakly coupled to each other and to the lattice. The system develops both a longitudinal and a transverse instability. Based on the phonon spectrum of a 2D hexagonal Yukawa lattice [2], we determine and compare the transverse and longitudinal growth rates. As a function of the wavenumber, the growth rates exhibit remarkable gaps, where no instability is excited. The gap locations are governed by the ratio of the lattice and the beam plasma frequencies. The behavior of the growth rates also depends on the direction of the beam and on the relationship between the beam speed and the longitudinal and transverse sound speeds. [1] GJ Kalman, M Rosenberg, JPA 36, 5963 (2003). [2] T Sullivan, GJ Kalman, S Kyrkos, P Bakshi, M Rosenberg, Z Donko, JPA 39, 4607 (2006).

Kyrkos, S.; Kalman, G.; Rosenberg, M.

2008-11-01

170

Potential Gradient Parametrization in a Langevin Type Dissipative Dynamics  

NASA Astrophysics Data System (ADS)

A parametrization of the conservative force in the dynamical coalescence and reseparation model is proposed. This model with one body dissipation formula, Yukawa plus exponential finite range potential, and shell effects included was recently adopted to follow Langevin trajectories for a collision of two very heavy nuclei which can end up as a compound system or reseparate. With our parametrization it is possible to speed up model calculations by a factor of 10 without loosing accuracy of trajectory integration. This can be of some importance in a case of Langevin trajectories calculation where many of them have to be traced in order to estimate probability for a process of interest, namely a fusion of two very heavy nuclei at beam energies close to the Coulomb barrier. Few examples of fusion excitation functions of heavy nuclei calculated with this faster version of the computer code are presented.

Wieloch, A.; Sosin, Z.; Blocki, J.

1999-04-01

171

Local logarithmic correlators as limits of Coulomb gas integrals  

NASA Astrophysics Data System (ADS)

We will describe how logarithmic singularities arise as limits of Coulomb Gas integrals. Our approach will combine analytic properties of the time-like Liouville structure constants, together with the recursive formula of the Virasoro conformal blocks. Although the Coulomb Gas formalism forces a diagonal coupling between the chiral and anti-chiral sectors of the Conformal Field Theory (CFT), we present new results for the multi-screening integrals which are potentially interesting for applications to critical statistical systems described by Logarithmic CFTs. In particular our findings extend and complement previous results, derived with Coulomb Gas methods, at c=0 and c=-2.

Santachiara, Raoul; Viti, Jacopo

2014-05-01

172

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

173

Superdiffusion in two-dimensional Yukawa liquids  

NASA Astrophysics Data System (ADS)

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 Lévy 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.

2007-01-01

174

Heavy-ion fusion using a parabolic barrier with Coulomb interaction  

Microsoft Academic Search

In this work, we describe the fusion mechanism between two heavy ions as penetration through a parabolic barrier in the presence of a proper Coulomb interaction with appropriate boundary conditions. The parabolic potential is matched to the Coulomb potential in order to avoid any discontinuity of the potential surface. The Schrödinger equations in the exterior and interior regions containing, respectively,

Q. Haider; F. Bary Malik

1982-01-01

175

Thermodynamics of strongly coupled repulsive Yukawa particles in ambient neutralizing plasma: Thermodynamic instability and the possibility of observation in fine particle plasmas  

SciTech Connect

The thermodynamics is analyzed for a system composed of particles with hard cores, interacting via the repulsive Yukawa potential (Yukawa particulates), and neutralizing ambient (background) plasma. An approximate equation of state is given with proper account of the contribution of ambient plasma and it is shown that there exists a possibility for the total isothermal compressibility of Yukawa particulates and ambient plasma to diverge when the coupling between Yukawa particulates is sufficiently strong. In this case, the system undergoes a transition into separated phases with different densities and we have a critical point for this phase separation. Examples of approximate phase diagrams related to this transition are given. It is emphasized that the critical point can be in the solid phase and we have the possibility to observe a solid-solid phase separation. The applicability of these results to fine particle plasmas is investigated. It is shown that, though the values of the characteristic parameters are semiquantitative due to the effects not described by this model, these phenomena are expected to be observed in fine particle plasmas, when approximately isotropic bulk systems are realized with a very strong coupling between fine particles.

Totsuji, Hiroo [Graduate School of Natural Science and Technology and Faculty of Engineering, Okayama University, Tsushimanaka 3-1-1, Okayama 700-8530 (Japan)

2008-07-15

176

Pseudospin symmetry of the Dirac equation for a Möbius square plus Mie type potential with a Coulomb-like tensor interaction via SUSYQM  

NASA Astrophysics Data System (ADS)

We investigate the approximate solution of the Dirac equation for a combination of Möbius square and Mie type potentials under the pseudospin symmetry limit by using supersymmetry quantum mechanics. We obtain the bound-state energy equation and the corresponding spinor wave functions in an approximate analytical manner. We comment on the system via various useful figures and tables.

Akpan, N. Ikot; Zarrinkamar, S.; Eno, J. Ibanga; Maghsoodi, E.; Hassanabadi, H.

2014-01-01

177

Coulomb half-shell t matrix  

SciTech Connect

The lth--partial-wave Coulomb half-off-shell t matrix t/sub l//sup c/(k,q,k/sup 2/) is expressed in terms of hypergeometric functions which are polynomials. The expression is used to compute t/sub l//sup c/(k,q,k/sup 2/) as a function of the off-shell momentum q for two laboratory energies E/sub lab/( = 2k/sup 2/) = 10 and 20 MeV. Results are presented for l = 0 to 10. Our numbers refer to repulsive Coulomb potential encountered in the case of p-p scattering. It is found that in addition to the on-shell discontinuity t/sub l//sup c/(k,q,k/sup 2/) exhibits a singularity as q..-->..0 for higher partial waves.

Talukdar, B.; Ghosh, D.K.; Sasakawa, T.

1984-04-01

178

Diffusion coefficient of three-dimensional Yukawa liquids  

SciTech Connect

The purpose of this work is an investigation of the diffusion coefficient of the dust component in complex plasma. The computer simulation of the Yukawa liquids was made on the basis of the Langevin equation, which takes into account the influence of buffer plasma on the dust particles dynamics. The Green–Kubo relation was used to calculate the diffusion coefficient. Calculations of the diffusion coefficient for a wide range of the system parameters were performed. Using obtained numerical data, we constructed the interpolation formula for the diffusion coefficient. We also show that the interpolation formula correctly describes experimental data obtained under microgravity conditions.

Dzhumagulova, K. N.; Ramazanov, T. S.; Masheeva, R. U. [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)] [IETP, Al Farabi Kazakh National University, 71, al Farabi ave., Almaty 050040 (Kazakhstan)

2013-11-15

179

Thermodynamic properties of short-range attractive Yukawa fluid: simulation and theory.  

PubMed

Coexistence properties of the hard-core attractive Yukawa potential with inverse-range parameter kappa=9, 10, 12, and 15 are calculated by applying canonical Monte Carlo simulation. As previously shown for longer ranges, we show that also for the ranges considered here the coexistence curves scaled by the critical density and temperature obey the law of corresponding states, and that a linear relationship between the critical density and the reciprocal of the critical temperature holds. The simulation results are compared to the predictions of the self-consistent Ornstein-Zernike approximation, and a good agreement is found for both the critical points and the coexistence curves, although some slight discrepancies are present. PMID:20331282

Orea, Pedro; Tapia-Medina, Carlos; Pini, Davide; Reiner, Albert

2010-03-21

180

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

181

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

182

Accurate treatment of coulomb contribution in nucleus-nuclues bremsstrahlung  

NASA Astrophysics Data System (ADS)

Partial-wave expansions of nucleus-nucleus bremsstrahlung cross sections converge very slowly as a function of orbital momentum, especially at small deflection angles. While nuclear effects can easily be restricted to a limited number of partial waves, Coulomb effects contribute to much higher partial waves because of the long range of the force. We accurately solve this problem by separating the bremsstrahlung matrix element into a purely Coulomb part and a fast-convergin series. The Coulomb contribution is calculated by numerically integrating analytical expressions of the Coulomb bremsstrahlung matrix element. The accuracy of the results and the importance of the corrections are studied in a potential-model description of the ?(?, ??)? reaction.

Baye, D.; Sauwens, C.; Descouvemont, P.; Keller, S.

1991-07-01

183

Coulomb gaps and Hubbard gaps  

Microsoft Academic Search

There is a strong unscreened Coulomb repulsion between the electrons in the impurity band of a lightly doped compensated semiconductor. This can be divided into a long-ranged 1\\/r part and a short-ranged part between two electrons on the same site. Both of these interactions may lead to gaps in the density of single-particle states, the Coulomb gap and the Hubbard

J. H. Davies

1984-01-01

184

Split sfermion families, Yukawa unification and muon g - 2  

NASA Astrophysics Data System (ADS)

We consider two distinct classes of Yukawa unified supersymmetric SO(10) models with non-universal and universal soft supersymmetry breaking (SSB) gaugino masses at M GUT. In both cases, we assume that the third family SSB sfermion masses at M GUT are different from the corresponding sfermion masses of the first two families (which are equal). For the SO(10) model with essentially arbitrary (non-universal) gaugino masses at M GUT, it is shown that t- b- ? Yukawa coupling unification is compatible, among other things, with the 125 GeV Higgs boson mass, the WMAP relic dark matter density, and with the resolution of the apparent muon g - 2 anomaly. The colored sparticles in this case all turn out to be quite heavy, of order 5 TeV or more, but the sleptons (smuon and stau) can be very light, of order 200 GeV or so. For the SO(10) model with universal gaugino masses and NUHM2 boundary conditions, the muon g - 2 anomaly cannot be resolved. However, the gluino in this class of models is not too heavy, ? 3 TeV, and therefore may be found at the LHC.

Ajaib, M. Adeel; Gogoladze, Ilia; Shafi, Qaisar; Ün, Cem Salih

2014-05-01

185

Near-edge band structures and band gaps of Cu-based semiconductors predicted by the modified Becke-Johnson potential plus an on-site Coulomb U  

NASA Astrophysics Data System (ADS)

Diamond-like Cu-based multinary semiconductors are a rich family of materials that hold promise in a wide range of applications. Unfortunately, accurate theoretical understanding of the electronic properties of these materials is hindered by the involvement of Cu d electrons. Density functional theory (DFT) based calculations using the local density approximation or generalized gradient approximation often give qualitative wrong electronic properties of these materials, especially for narrow-gap systems. The modified Becke-Johnson (mBJ) method has been shown to be a promising alternative to more elaborate theory such as the GW approximation for fast materials screening and predictions. However, straightforward applications of the mBJ method to these materials still encounter significant difficulties because of the insufficient treatment of the localized d electrons. We show that combining the promise of mBJ potential and the spirit of the well-established DFT + U method leads to a much improved description of the electronic structures, including the most challenging narrow-gap systems. A survey of the band gaps of about 20 Cu-based semiconductors calculated using the mBJ + U method shows that the results agree with reliable values to within ±0.2 eV.

Zhang, Yubo; Zhang, Jiawei; Gao, Weiwei; Abtew, Tesfaye A.; Wang, Youwei; Zhang, Peihong; Zhang, Wenqing

2013-11-01

186

Near-edge band structures and band gaps of Cu-based semiconductors predicted by the modified Becke-Johnson potential plus an on-site Coulomb U.  

PubMed

Diamond-like Cu-based multinary semiconductors are a rich family of materials that hold promise in a wide range of applications. Unfortunately, accurate theoretical understanding of the electronic properties of these materials is hindered by the involvement of Cu d electrons. Density functional theory (DFT) based calculations using the local density approximation or generalized gradient approximation often give qualitative wrong electronic properties of these materials, especially for narrow-gap systems. The modified Becke-Johnson (mBJ) method has been shown to be a promising alternative to more elaborate theory such as the GW approximation for fast materials screening and predictions. However, straightforward applications of the mBJ method to these materials still encounter significant difficulties because of the insufficient treatment of the localized d electrons. We show that combining the promise of mBJ potential and the spirit of the well-established DFT + U method leads to a much improved description of the electronic structures, including the most challenging narrow-gap systems. A survey of the band gaps of about 20 Cu-based semiconductors calculated using the mBJ + U method shows that the results agree with reliable values to within ±0.2 eV. PMID:24320290

Zhang, Yubo; Zhang, Jiawei; Gao, Weiwei; Abtew, Tesfaye A; Wang, Youwei; Zhang, Peihong; Zhang, Wenqing

2013-11-14

187

Equation of state and thermodynamic functions for the fcc soft-core multiple-Yukawa solid and application to fullerenes with compressible molecular radius  

NASA Astrophysics Data System (ADS)

The generalized free volume theory is applied to the soft-core multiple-Yukawa solid, and the hard-core multiple-Yukawa is included in as a special case. The expressions for equation of state and internal energy are derived. The formalism developed is applied to the C60 , C76 , and C84 solids. The effective diameter of C60 molecule is taken as the experimental value; the parameters of the double Yukawa (DY) potential for carbon-carbon atoms are determined through fitting the experimental data of cohesive energy, the lattice constant, and the compression curve of C60 solid at ambient temperature. The effective diameter of C76 and C84 molecules are determined through fitting the experimental lattice constants at ambient temperature. The numerical results of C60 solid from the soft-core DY potential are in good agreement with the experiments, including the lattice constant and compression curve. The lattice constant versus temperature relationship for C76 and C84 solids calculated from the DY potential is qualitatively in accordance with experimental data as same as the Girifalco potential. The compression curve of the C84 solid calculated from the DY potential deviates from and is softer than the experimental data available. The reason for deviation is discussed, and it is concluded that the influence of compressibility of fullerene molecules to thermophysical quantities is important at high-pressure conditions.

Sun, Jiu-Xun

2007-01-01

188

Low-energy fission within the Lublin–Strasbourg drop and Yukawa folded model  

NASA Astrophysics Data System (ADS)

The evolution of fragment mass distribution in low-energy fission is studied as a function of the composition of the fissioning system over a wide range, from Hg to Fm isotopes. The relative importance of symmetric and asymmetric fission modes is investigated within a static picture based on elaborate, four-dimensional potential energy spaces using the modified Funny–Hills deformation coordinates. The potential energy is computed with the macroscopic-microscopic method. The Lublin–Strasbourg drop model is used to calculate the macroscopic part of the potential energy, while the Yukawa folded single-particle potential with an improved Strutinsky method and the Bardeen–Cooper–Schrieffer theory are employed to evaluate the shell and pairing contributions to the macroscopic energy. From the analysis of the potential energy surfaces, equilibrium deformations and saddle-point shapes are determined. A coexistence of symmetric and asymmetric fission valleys is observed. The relative depth of these valleys depends on the fissioning nucleus. The valleys' competition is used to explain the evolution of the fission-fragment mass distribution, from asymmetric fission in ^{180}Hg to symmetric fission in ^{260}Fm. Good qualitative agreement is found with the experiment.

Nerlo-Pomorska, B.; Pomorski, K.; Schmitt, Ch; Bartel, J.

2014-05-01

189

Neutrino Masses, Cosmological Bound and Four Zero Yukawa Textures  

NASA Astrophysics Data System (ADS)

Four zero neutrino Yukawa textures in a specified weak basis, combined with ?? symmetry and type-I seesaw, yield a highly constrained and predictive scheme. Two alternately viable 3×3 light neutrino Majorana mass matrices m?A/m?B result with inverted/normal mass ordering. Neutrino masses, Majorana in character and predicted within definite ranges with laboratory and cosmological inputs, will have their sum probed cosmologically. The rate for 0??? decay, though generally below the reach of planned experiments, could approach it in some parameter region. Departure from ?? symmetry due to RG evolution from a high scale and consequent CP violation, with a Jarlskog invariant whose magnitude could almost reach 6×10-3, are explored.

Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir

190

Ultraviolet Properties of the Spinless, One-Particle Yukawa Model  

NASA Astrophysics Data System (ADS)

We consider the one-particle sector of the spinless Yukawa model, which describes the interaction of a nucleon with a real field of scalar massive bosons (neutral mesons). The nucleon as well as the mesons have relativistic dispersion relations. In this model we study the dependence of the nucleon mass shell on the ultraviolet cut-off . For any finite ultraviolet cut-off the nucleon one-particle states are constructed in a bounded region of the energy-momentum space. We identify the dependence of the ground state energy on and the coupling constant. More importantly, we show that the model considered here becomes essentially trivial in the limit regardless of any (nucleon) mass and self-energy renormalization. Our results hold in the small coupling regime.

Deckert, D.-A.; Pizzo, A.

2014-05-01

191

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

192

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

193

Coulomb Explosion and Thermal Spikes  

NASA Astrophysics Data System (ADS)

A fast ion can electronically excite a solid producing a track of damage, a process initially used to detect energetic particles but now used to alter materials. From the seminal paper by Fleischer et al. [Phys. Rev. 156, 353 (1967)] to the present, ``Coulomb explosion'' and thermal spike models have been often treated as competing models for describing ion track effects. Here molecular dynamics simulations of electronic sputtering, a surface manifestation of track formation, show that in the absence of significant quenching Coulomb explosion in fact produces a spike at high excitation density, but the standard spike models are incorrect.

Bringa, E. M.; Johnson, R. E.

2002-04-01

194

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

195

GUT predictions for quark-lepton Yukawa coupling ratios with messenger masses from non-singlets  

NASA Astrophysics Data System (ADS)

We propose new predictions from grand unified theories (GUTs) [applicable to both supersymmetric (SUSY) and non-SUSY models] for the ratios of quark and lepton Yukawa couplings. These new predictions arise from splitting the masses of the messenger fields for the GUT-scale Yukawa operators by Clebsch-Gordan factors from GUT symmetry breaking. This has the effect that these factors enter inversely in the predicted quark-lepton Yukawa coupling ratios, leading to new possible GUT predictions. We systematically construct the new predictions that can be realized in this way in SU(5) GUTs and Pati-Salam unified theories and discuss model building applications.

Antusch, Stefan; King, Stephen F.; Spinrath, Martin

2014-03-01

196

Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit  

NASA Astrophysics Data System (ADS)

An efficient way of evolving a solution to an ordinary differential equation is presented. A finite element method is used where we expand in a convenient local basis set of functions that enforce both function and first derivative continuity across the boundaries of each element. We also implement an adaptive step-size choice for each element that is based on a Taylor series expansion. This algorithm is used to solve for the eigenpairs corresponding to the one-dimensional soft Coulomb potential, 1/?x2+?2 , which becomes numerically intractable (because of extreme stiffness) as the softening parameter (?) approaches zero. We are able to maintain near machine accuracy for ? as low as ? =10-8 using 16-digit precision calculations. Our numerical results provide insight into the controversial one-dimensional hydrogen atom, which is a limiting case of the soft Coulomb problem as ? ?0.

Gebremedhin, Daniel H.; Weatherford, Charles A.

2014-05-01

197

Dispersion properties of the out-of-plane transverse wave in a two-dimensional Coulomb crystal  

NASA Astrophysics Data System (ADS)

The formation of a two-dimensional (2D) Coulomb crystal in a typical experimental environment was simulated with a computer code called BOX_TREE. The dispersion properties of a novel dust lattice wave (DLW) mode, the out-of-plane transverse wave, were obtained. The dispersion relation was determined to be an opticlike inverse dispersion when wave number k is lower than a critical value kcritical, and a positive dispersion when k>kcritical. The negative group velocity of the wave for kkcritical depends on the propagation direction. The value of kcritical depends on both ? and propagation direction, but changes very little for all propagation directions and the range of ? investigated. An analytical method has also been used to derive the dispersion relations assuming a hexagonal 2D lattice and Yukawa interparticle potential. These dispersion relations compare favorably with the simulation results. The dispersion relation for a 1D string was also obtained via BOX_TREE simulation and shown to agree with the analytical result given by Vladimirov [Physica A 315, 222 (2002)]. Comparison shows that the out-of-plane transverse DLW in a 2D lattice when k

Qiao, K.; Hyde, T. W.

2003-10-01

198

Structure of mesoscopic Coulomb balls  

Microsoft Academic Search

An analysis of the structural properties of three-dimensional Coulomb clusters confined in a spherical parabolic trap is presented. Based on extensive high accuracy computer simulations the shell configurations and energies for particle numbers in the range $60 \\\\le N\\\\le 160$ are reported. Further, the intrashell symmetry and the lowest metastable configurations are analyzed for small clusters and a novel type

P. Ludwig; S. Kosse; M. Bonitz

2004-01-01

199

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

200

Coulomb explosion sputtering of selectively oxidized Si.  

PubMed

We have studied the sputtering of a unique system comprising of coexisting silicon and silicon oxide surfaces due to the impact of multiply charged Ar(q+) ions. Such surfaces are produced by oblique angle oxygen ion bombardment on Si(100), which results in one side oxidized ripple formation due to preferential oxygen implantation. It is observed by atomic force microscopy and conducting atomic force microscopy studies that the higher the potential energy of the Ar(q+) ion, the higher the sputtering yield of the nonconducting (oxide) side of the ripple as compared to the semiconducting side while ensuring an identical irradiation and measurement condition. It also shows experimentally the potential of highly charged ions in the gentle cleaning or tailoring of nanostructures. The results are explained in terms of the Coulomb explosion model, where potential sputtering depends on the conductivity of the ion impact sites. PMID:21393663

Karmakar, P; Bhattacharjee, S; Naik, V; Sinha, A K; Chakrabarti, A

2010-05-01

201

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

202

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

203

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

204

Relativistic effects in the photoionization of hydrogen-like ions with screened Coulomb interaction  

NASA Astrophysics Data System (ADS)

The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in the characteristic features of photoionization cross section for electric dipole nl ??,l±1 transitions: shape resonances, Cooper minima and cross section enhancements due to near-zero-energy states. It is shown that the main source of relativistic effects in these cross section features is the fine-structure splitting of bound state energy levels. The relativistic effects are studied in the photoionization of Fe25+ ion, as an example.

Xie, L. Y.; Wang, J. G.; Janev, R. K.

2014-06-01

205

Near-prospective test of Coulomb stress triggering  

NASA Astrophysics Data System (ADS)

studies retrospectively observed a strong association between earthquake location and increased static Coulomb stress. In addition to confirming these results for southern California seismicity, we observed prospective forecasting potential in static stress evolution. With 141 seismic and 98 aseismic stress sources, we considered alternate choices of stress components and receiver fault orientations, examined the effect of Coulomb triggering on earthquake magnitude, calculated stress histories for receiver quakes to see if some occurred after their stress had peaked, examined whether stress changes from the Hector Mine earthquake alone changed the earthquake rate as expected, and estimated the conditional distribution of earthquake occurrence given resolved Coulomb stress change. We found that with 95% confidence, M ? 2.8 receiver earthquakes nucleate in areas of shear or Coulomb stress change increase. On average, 59% of earthquakes occurred within stress-enhanced zones, regardless of the choice of rupture plane or type of stress change. The 1999 Hector Mine, California, earthquake increased the seismicity in regions of positive and negative stress change but more so in the positive regions. Earthquakes frequently occur after their calculated peak stress has occurred, indicating that elastic calculations do not tell the whole story. We found no significant evidence that stress change affects the magnitude of receiver quakes. Thus, instantaneous Coulomb and shear stress change apparently influence the locations but not the magnitudes of future earthquakes.

Strader, Anne; Jackson, David D.

2014-04-01

206

Modeling of Coulomb interaction in parabolic quantum wires  

Microsoft Academic Search

We study the exciton states in a parabolic quantum wire. An exactly solvable model is introduced for calculating the exciton state and the binding energy as a function of the radius of the quantum wire within the envelope-function approximation. In the calculation, we replace the actual Coulomb interaction between the electron and the hole by a Gaussian nonlocal separable potential

C. González-Santander; F. Domínguez-Adame

2009-01-01

207

Entropic gravity resulting from a Yukawa type of correction to the metric for a solar mass black hole  

NASA Astrophysics Data System (ADS)

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton's "inverse-square law" of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. In this paper we study the entropic gravity correction to the gravitational force on the horizon of a black hole whose metric has been modified by a Yukawa term. We find that the gravitational radius of such a black hole is given in-terms of the Lambert function, and the entropic force introduces a extra term that depends on the square of the coupling constant ? of the Yukawa potential. In the case alpha equals zero we recover the Newtonian gravitational force on the horizon. In a first effort to obtain a relation between geometry and information, we calculate the Ricci scalar and through entropy we establish a relation to the number of information N where this is given in nats. Finally, we calculate a critical entropy value as well as a critical information number N c for which the curvature becomes identically zero which implies that the space becomes flat.

Haranas, Ioannis; Gkigkitzis, Ioannis

2013-09-01

208

Hard core Yukawa fluid with temperature and density dependent interaction: Phase diagram of the AOT/water/decane microemulsion  

NASA Astrophysics Data System (ADS)

A fluid with an interaction potential consisting of a hard core and an attractive Yukawa tail is considered. The strength of the attraction is taken to depend both on density and temperature in order to take into account the state dependence of the effective interaction suggested by the analysis of structural data of several colloidal suspensions, in particular microemulsions of AOT reverse micelles. The thermodynamics of this fluid is investigated starting from the inverse temperature expansion of the free energy in the mean spherical approximation. The temperature and density dependence of the interaction is incorporated in consistent expressions for the pressure, isothermal compressibility, and chemical potential. The phase diagram predicted by this method is in agreement with experimental data on AOT reverse micelles analyzed in the effective one component approach.

Bouaskarne, M.; Amokrane, S.; Regnaut, C.

1999-08-01

209

Structure of multi-component/multi-Yukawa mixtures  

NASA Astrophysics Data System (ADS)

Recent small angle scattering experiments reveal new peaks in the structure function S(k) of colloidal systems (Liu et al 2005 J. Chem. Phys. 122 044507), in a region that was inaccessible with older instruments. It has been increasingly evident that a single (or double) Yukawa MSA-closure cannot account for these observations, and three or more terms are needed. On the other hand the MSA is not sufficiently accurate (Broccio et al 2005 Preprint); more accurate theories such as the HNC have been tried. But while the MSA is asymptotically exact at high densities (Rosenfield and Blum 1986 J. Chem. Phys. 85 1556), it does not satisfy the low density asymptotics. This has been corrected in the soft MSA (Blum et al 1972 J. Chem. Phys. 56 5197, Narten et al 1974 J. Chem. Phys. 60 3378) by adding exponential type terms. The results compared to experiment and simulation for liquid sodium by Rahman and Paskin (as shown in Blum et al 1972 J. Chem. Phys. 56 5197) are remarkably good. We use here a general closure of the Ornstein-Zernike equation, which is not necessarily the MSA closure (Blum and Hernando 2001 Condensed Matter Theories vol 16 ed Hernandez and Clark (New York: Nova) p 411). \\begin{equation} \\fl c_{ij}(r)=\\sum_{n=1}^{M}{\\cal{K}}_{ij}^{(n)}\\rme^{-z_{n}r}/r\\tqs {\\cal{K}}_{ij}^{(n)}=K^{(n)}\\delta_{i}^{(n)}\\delta_{j}^{(n)}\\tqs r\\geq \\sigma_{ij} \\label{eq1} \\end{equation} with the boundary condition for gij(r) = 0 for r<=?ij. This general closure of the Ornstein-Zernike equation will go well beyond the MSA since it has been tested by Monte Carlo simulation for tetrahedral water (Blum et al 1999 Physica A 265 396), toroidal ion channels (Enriquez and Blum 2005 Mol. Phys. 103 3201) and polyelectrolytes (Blum and Bernard 2004 Proc. Int. School of Physics Enrico Fermi, Course CLV vol 155, ed Mallamace and Stanley (Amsterdam: IOS Press) p 335). For this closure we get for the Laplace transform of the pair correlation function an explicitly symmetric result \\begin{equation} \\fl 2 \\pi \\tilde{g}_{ij}(s)=-\\frac{\\rme^{-s \\sigma_{ij}}}{D_{\\tau}(s)} \\left\\{{1\\over s^2}+{1\\over s}Q^{\\prime}_{ij}(\\sigma_{ij})+\\sum_{m=1}^{M}{{ z_m \\tilde{\\cal{X}}}_i^{(m)}{f}_j^{(m)}\\over{s+z_m}}\\right\\}. \\label{eq2} \\end{equation} This function is also easily transformed into S(k) by replacing s\\Rightarrow \\rmi k . For low density situations (dilute colloids) D_{\\tau } (s)\\sim 1+{\\cal {O}(\\rho)} and S(k) is a sum of M Lorentzians. For hard sphere PY mixtures we get the simple (compare Lebowitz 1964 Phys. Rev. 133 A895 and Blum and Stell 1979 J. Chem. Phys. 71 42) \\[ 2 \\pi \\tilde{g}_{ij}(s)=-\\frac{\\rme^{-s \\sigma_{ij}}}{s^2 D_{\\tau}(s)} \\left\\{1+s\\left[(Q^{HS})^{\\prime}_{ij}(\\sigma_{ij})\\right]\\right\\} \\] where D?(s) is a scalar function. For polydisperse electrolytes in the MSA a simpler expression is also obtained (compare Blum and Hoye 1977 J. Phys. Chem. 81 1311). An explicit continued fraction solution of the one component multi-Yukawa case is also given.

Blum, L.; Arias, M.

2006-09-01

210

Effect of off-center positively charged Coulomb impurity on Dirac states in graphene magnetic dot  

NASA Astrophysics Data System (ADS)

Using numerical diagonalization, we study the effect of the position of an off-center positively charged Coulomb impurity in a graphene magnetic dot, whose magnetic field profile is chosen as a Gaussian type. Numerical results show that the electron-hole symmetry is broken by the Coulomb potential and the originally zero energy states become nondegenerate and split into hole-like states. For the higher Landau levels shown, owing to the competition between the repulsive Coulomb potential and the magnetic confinement, the level orderings are reversed in the hole states at critical magnetic fields. Similar results are also obtained in the dot-size dependence of the low-lying spectra.

Lee, C. M.; Chan, K. S.

2014-05-01

211

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

212

Magneto-Optical Transitions in a Coulomb Coupled Pair of Quantum Dots (Abstract Only).  

National Technical Information Service (NTIS)

Optical transitions for a pair of Coulomb coupled quantum dots in a magnetic field are investigated. It is shown that for a parabolic confinement potential, the electric dipole transition energies reveal interesting anticrossing behavior which is due to t...

T. Chakraborty V. Halonen P. Pietilainen

1991-01-01

213

PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems  

NASA Astrophysics Data System (ADS)

This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas, condensed matter and ultra-cold plasmas. One hundred and thirty participants came from twenty countries and four continents to participate in the conference. Those giving presentations were asked to contribute to this special issue to make a representative record of an interesting conference. We thank the International Advisory Board and the Programme Committee for their support and suggestions. We thank the Local Organizing Committee (Stefania De Palo, Vittorio Pellegrini, Andrea Perali and Pierbiagio Pieri) for all their efforts. We highlight for special mention the dedication displayed by Andrea Perali, by Rocco di Marco for computer support, and by our tireless conference secretary Fiorella Paino. The knowledgeable guided tour of the historic centre of Camerino given by Fiorella Paino was appreciated by many participants. It is no exaggeration to say that without the extraordinary efforts put in by these three, the conference could not have been the success that it was. For their sustained interest and support we thank Fulvio Esposito, Rector of the University of Camerino, Fabio Beltram, Director of NEST, Scuola Normale Superiore, Pisa, and Daniel Cox, Co-Director of ICAM, University of California at Davis. We thank the Institute of Complex and Adaptive Matter ICAM-I2CAM, USA for providing a video record of the conference on the web (found at http://sccs2008.df.unicam.it/). Finally we thank the conference sponsors for their very generous support: the University of Camerino, the Institute of Complex and Adaptive Matter ICAM-I2CAM, USA, the International Centre for Theoretical Physics ICTP Trieste, and CNR-INFM DEMOCRITOS Modeling Center for Research in Atomistic Simulation, Trieste. Participants at the International Conference on Strongly Coupled Coulomb Systems (SCCS) (University of Camerino, Italy, 29 July-2 August 2008).

Neilson, David; Senatore, Gaetano

2009-05-01

214

An entropic understanding of Coulomb force  

NASA Astrophysics Data System (ADS)

Exploiting Verlinde's proposal on the entropic understanding of Newton's law, we show that Coulomb force could also be understood as an entropically emergent force (rather than as a fundamental force). We apply Kaluza-Klein idea to Verlinde's formalism to obtain Coulomb interaction in the lower dimensions. The kinematics concerning the Kaluza-Klein momenta separates the interaction due to the momentum flow from the gravitational interaction. The momentum-charge conversion relation results in the precise form of Coulomb interaction.

Cho, Jin-Ho; Kim, Hyosung

2012-02-01

215

The Coulomb Barrier Transmission Coefficient in Nuclear Reactions  

NASA Astrophysics Data System (ADS)

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 boundary conditions at the nuclear surface. We also derive their recurrence relations and asymptotic forms. Some forms of the Coulomb wavefunctions are useful in analytic calculations but are cumbersome in most numerical calculations. A computer code is developed to calculate the values of the Coulomb wavefunctions using power series expansions. The Coulomb wavefunctions are used to calculate the transmission coefficient which plays a crucial role in the calculation of cross sections. Several methods are used to calculate the transmission coefficient in an attempt to fit experimental data both including and excluding a resonance peak. The conventional formula for the transmission coefficient, which is widely used, will be compared with our new formulae which include a realistic nuclear potential inside a nucleus. They provide information both at the nuclear surface and in the inside of the nucleus. Our new methods may be applied to the low energy nuclear fusion reactions involved in the magnetic confinement and inertial fusions and also in astrophysical problems. The results for the nuclear reactions, D(D, p)^3 He, D(D, n)T,^3 He(D, p)^4 He,T(D, n)^4 He, and ^7 Be(p, gamma)^8 B are presented. All the results are consistent with the conventional results within 10%. However, our newly formulated coefficient improve the nuclear reaction data analyses by producing good fits with less physical assumptions without an arbitrary fitting parameter. In this work we confine ourselves to S-waves assuming that the energies interested are low enough to insure our confinement. Finally, it is recommended to include several more angular momentum waves. By including higher angular momentum terms, more plausible fits for the experimental data are expected.

Yoon, Jin-Hee

216

Coulomb force as an entropic force  

NASA Astrophysics Data System (ADS)

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

2010-05-01

217

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

218

t - b - ? Yukawa unification for ? < 0 with a sub-TeV sparticle spectrum  

NASA Astrophysics Data System (ADS)

We show compatibility with all known experimental constraints of t - b - ? Yukawa coupling unification in supersymmetric SU(4) c × SU(2) L × SU(2) R which has non-universal gaugino masses and the MSSM parameter ? < 0. In particular, the relic neutralino abundance satisfies the WMAP bounds and ?( g - 2) ? is in good agreement with the observations. We identify benchmark points for the sparticle spectra which can be tested at the LHC, including those associated with gluino and stau coannihilation channels, mixed bino-Higgsino state and the A-funnel region. We also briefly discuss prospects for testing Yukawa unification with the ongoing and planned direct detection experiments.

Gogoladze, Ilia; Khalid, Rizwan; Raza, Shabbar; Shafi, Qaisar

2010-12-01

219

Lattice QCD analysis for Faddeev-Popov eigenmodes in terms of gluonic momentum components in the Coulomb gauge  

NASA Astrophysics Data System (ADS)

We analyze the relation between Faddeev-Popov eigenmodes and gluon-momentum components in the Coulomb gauge using SU(3) lattice QCD. In the Coulomb gauge, the color-Coulomb energy is largely enhanced by near-zero Faddeev-Popov eigenmodes, which would lead to the confining potential. By the ultraviolet-momentum gluon cut, the color-Coulomb energy and the Faddeev-Popov spectrum are almost unchanged. In contrast to the ultraviolet insensitivity, the color-Coulomb energy and the Faddeev-Popov eigenmodes drastically change by infrared-momentum gluon cut. Without infrared gluons, the color-Coulomb energy tends to become nonconfining, and near-zero Faddeev-Popov eigenmodes vanish. We also investigate the full Faddeev-Popov eigenmodes, and find that infrared gluons widely influence both high and low Faddeev-Popov eigenmodes.

Iritani, Takumi; Suganuma, Hideo

2012-10-01

220

Coulomb blockade in silicon nano-pillars  

NASA Astrophysics Data System (ADS)

We have investigated the current-voltage characteristics of nano-pillars of polycrystalline silicon with two 2-3 nm thick silicon nitride tunnel barriers. Pillars with diameters between 45 and 100 nm showed a Coulomb blockade region and Coulomb staircase at 4.2 K.

Pooley, D. M.; Ahmed, H.; Mizuta, H.; Nakazato, K.

1999-04-01

221

Quantum solution for the one-dimensional Coulomb problem  

SciTech Connect

The one-dimensional hydrogen atom has been a much studied system with a wide range of applications. Since the pioneering work of Loudon [R. Loudon, Am. J. Phys. 27, 649 (1959).], a number of different features related to the nature of the eigenfunctions have been found. However, many of the claims made throughout the years in this regard are not correct--such as the existence of only odd eigenstates or of an infinite binding-energy ground state. We explicitly show that the one-dimensional hydrogen atom does not admit a ground state of infinite binding energy and that the one-dimensional Coulomb potential is not its own supersymmetric partner. Furthermore, we argue that at the root of many such false claims lies the omission of a superselection rule that effectively separates the right side from the left side of the singularity of the Coulomb potential.

Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A. [Departamento de Fisica, Universidad Autonoma Metropolitana, Unidad Iztapalapa, Apartado Postal 55-534, Iztapalapa CP 09340 D. F. (Mexico); Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Apartado Postal 21-267, Coyoacan CP 04000 D. F. (Mexico); Facultad de Matematicas, Universidad Autonoma de Yucatan, Periferico Norte Tablaje C. 13615, Merida, Yucatan (Mexico)

2011-06-15

222

Coulomb drag mechanisms in graphene.  

PubMed

Recent measurements revealed an anomalous Coulomb drag in graphene, hinting at new physics at charge neutrality. The anomalous drag is explained by a new mechanism based on energy transport, which involves interlayer energy transfer, coupled to charge flow via lateral heat currents and thermopower. The old and new drag mechanisms are governed by distinct physical effects, resulting in starkly different behavior, in particular for drag magnitude and sign near charge neutrality. The new mechanism explains the giant enhancement of drag near charge neutrality, as well as its sign and anomalous sensitivity to the magnetic field. Under realistic conditions, energy transport dominates in a wide temperature range, giving rise to a universal value of drag which is essentially independent of the electron-electron interaction strength. PMID:23834416

Song, J C W; Abanin, D A; Levitov, L S

2013-08-14

223

Coulomb excitation of ruthenium isotopes  

NASA Astrophysics Data System (ADS)

The B(E2) values of the 89.4, 340.4, 575.5, 617.4 and 719.2 keV states of 99Ru and 127.2, 306.8, 422.0 and 544.9 keV states of 101Ru have been deduced by measuring the yields of gamma-rays following Coulomb excitation of a metallic ruthenium target with 3.0 MeV protons at Variable Energy Cyclotron, Chandigarh. The gamma-ray spectra were measured at 55° to the beam line using a 50 cm 3 Ge(Li) detector (resolution: 2.5 keV at 1332 keV). The present B(E2) values for different states in 99Ru and 101Ru are compared with the values available in the literature.

Arora, B. K.; Mehta, D.; Rani, Rakesh; Cheema, T. S.; Trehan, P. N.

1987-04-01

224

PREFACE: Strongly Coupled Coulomb Systems  

NASA Astrophysics Data System (ADS)

This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from `Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within each area new results from theory, simulations and experiments were presented. In addition, a special symposium was held one evening to explore the questions on high-energy-density matter generated by intense heavy ion beams and to discuss the outlook for applications to industry. As this special issue illustrates, the field remains vibrant and challenging, being driven to a great extent by new experimental tools and access to new strongly coupled conditions. This is illustrated by the inclusion of developments in the areas of warm matter, dusty plasmas, condensed matter and ultra-cold plasmas. In total, 200 participants from 17 countries attended the conference, including 42 invited speakers. The individuals giving presentations at the conference, including invited plenary and topical talks and posters, were asked to contribute to this special issue and most have done so. We trust that this special issue will accurately record the contents of the conference, and provide a valuable resource for researchers in this rapidly evolving field. We would like to thank the members of the International Advisory Board and all members of the Programme Committee for their contributions to the conference. Of course, nothing would have been possible without the dedicated efforts of the Local Organizing Committee, in particular Igor Morozov and Valery Sultanov. We wish to thank the Russian Academy of Sciences, the Institute for High Energy Densities, the Institute of Problems of Chemical Physics, the Moscow Institute of Physics and Technology, the Ministry of Education and Science of the Russian Federation, the Russian Foundation for Basic Research, the Moscow Committee of Science and Technologies, the Russian Joint Stock Company `Unified Energy System of Russia', and The International Association for the Promotion of Co-operation with Scientists from the New Independent States (NIS) of the Former Soviet Union for sponsoring this conference.

Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.

2006-04-01

225

Angular normal modes of a circular Coulomb cluster  

NASA Astrophysics Data System (ADS)

We investigate the angular normal modes for small oscillations about an equilibrium of a single-component Coulomb cluster confined by a radially symmetric external potential to a circle. The dynamical matrix for this system is a Laplacian symmetrically circulant matrix and this result leads to an analytic solution for the eigenfrequencies of the angular normal modes. We also show the limiting dependence of the largest eigenfrequency for large numbers of particles.

Lupinski, L. W.; Madsen, M. J.

2009-11-01

226

Advances in Dusty Plasmas 5.Strongly Coupled Dusty Plasmas  

NASA Astrophysics Data System (ADS)

We review thermodynamical and dynamical properties of strongly coupled dusty plasmas, focusing on the recent development of molecular dynamics (MD) simulations. In the present paper, dusty plasmas are modeled by the Yukawa system, which is a collection of particles interacting through Yukawa (i.e., screened Coulomb) potentials. The phase diagram, wave dispersion relations and some transport coefficients of Yukawa systems are discussed.

Hamaguchi, Satoshi

227

Running of the Yukawa Couplings in a Two Higgs Doublet Model  

SciTech Connect

We solve the one loop Renormalization Group Equations (RGE) for the Yukawa couplings in the Standard Model with two Higgs doublets. In the RGE we include the contributions of the up and down quarks. In this approximation we explore universality and unification assumptions to study the mass-hierarchy problem through the running of the vacuum expectation values.

Montes de Oca Y, J. H.; Juarez W, S. R. [Depto. de Fis., Esc. Sup. de Fis. y Mat., Instituto Politecnico Nacional, U.P. 'Adolfo Lopez Mateos' Edif. 9, C.P. 07738, Mexico, D.F. (Mexico); Kielanowski, P. [Dpto. de Fisica, CINVESTAV, Av. IPN 2508, C.P. 07360, Mexico, D.F. (Mexico)

2008-07-02

228

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

229

Nonlinear evolution of Yukawa couplings in the double Higgs and supersymmetric extensions of the standard model  

Microsoft Academic Search

The nonlinear evolution equations for Yukawa coupling matrices are discussed in the context of the standard, double Higgs and supersymmetric model of electroweak interactions. In each case, even in the presence of a very heavy top quark the approximate analytical solutions for the nonlinear evolution of masses and mixing angles are found. Comparison of the analytical approach with numerical solutions

B. Grzadkowski; M. Lindner; S. Theisen

1987-01-01

230

Radiative corrections to the Yukawa coupling constants in two Higgs doublet models  

NASA Astrophysics Data System (ADS)

We calculate one-loop corrected Yukawa coupling constants hffbar for the standard model-like Higgs boson h in two Higgs doublet models. We focus on the models with the softly-broken Z2 symmetry, which is imposed to avoid the flavor changing neutral current. Under the Z2 symmetry, there are four types of Yukawa interactions. We find that one-loop contributions from extra Higgs bosons modify the hffbar couplings to be maximally about 5% under the constraint from perturbative unitarity and vacuum stability. Our results show that the pattern of tree-level deviations by the mixing effect in each type of Yukawa couplings from the SM predictions does not change even including radiative corrections. Moreover, when the gauge couplings hVV (V=W,Z) are found to be slightly (with a percent level) different from the SM predictions, the hffbar couplings also deviate but more largely. Therefore, in such a case, not only can we determine the type of Yukawa couplings but also we can obtain information on the extra Higgs bosons by comparing the predictions with precisely measured hffbar and hVV couplings at future electron-positron colliders.

Kanemura, Shinya; Kikuchi, Mariko; Yagyu, Kei

2014-04-01

231

Coulomb impurity problem of graphene in magnetic fields  

NASA Astrophysics Data System (ADS)

Analytical solutions to the Coulomb impurity problem of graphene in the absence of a magnetic field show that when the dimensionless strength of the Coulomb potential g reaches a critical value the solutions become supercritical with imaginary eigenenergies. Application of a magnetic field is a singular perturbation, and no analytical solutions are known except at a denumerably infinite set of magnetic fields. We find solutions to this problem by numerical diagonalization of the large Hamiltonian matrices. Solutions are qualitatively different from those of zero magnetic field. All energies are discrete and no complex energies are allowed. We have computed the finite-size scaling function of the probability density containing an s-wave component of the Dirac wavefunctions. This function depends on the coupling constant, regularization parameter, and the gap. In the limit of vanishing regularization parameter our findings are consistent with the expected values of the exponent ? which determines the asymptotic behavior of the wavefunction near r=0.

Kim, S. C.; Eric Yang, S.-R.

2014-08-01

232

Effect of Coulomb screening length on nuclear "pasta" simulations  

NASA Astrophysics Data System (ADS)

We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as a screened Coulomb potential in the spirit of the Thomas-Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the nonhomogeneous nuclear structures known as "nuclear pasta." As the screening length increases, we can see a transition from a one-per-cell pasta regime (due exclusively to finite-size effects) to a more appealing multiple pasta per simulation box. This qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

Alcain, P. N.; Giménez Molinelli, P. A.; Nichols, J. I.; Dorso, C. O.

2014-05-01

233

Capacitance, Charge Fluctuations and Dephasing in Coulomb Coupled Conductors  

NASA Astrophysics Data System (ADS)

The charge fluctuations of two nearby mesoscopic conductors coupled only via the long range Coulomb force are discussed and used to find the dephasing rate which one conductor exerts on the other. The discussion is based on a formulation of the scattering approach for charge densities and the density response to a fluctuating potential. Coupling to the Poisson equation results in an electrically self-consistent description of charge fluctuations. At equilibrium the low-frequency noise power can be expressed with the help of a charge relaxation resistance (which together with the capacitance determines the RC-time of the structure). In the presence of transport the low frequency charge noise power is determined by a resistance which reflects the presence of shot noise. We use these results to derive expressions for the dephasing rates of Coulomb coupled conductors and to find a self-consistent expression for the measurement time.

Büttiker, Markus

234

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

235

Eulerian Bound States: 5D Coulomb Problem.  

National Technical Information Service (NTIS)

The Eulerian coordinates are applied for analyzing the 5D hydrogen atom's bound states problem. We calculate the spherical and parabolic bases of the 5D Coulomb problem, derive the Park's and Tarter's representations for the coefficients of the spherical-...

K. Karayan L. G. Mardoyan V. M. Ter-Antonyan

1994-01-01

236

Coulomb Glass: a Mean Field Study  

NASA Astrophysics Data System (ADS)

We study the Coulomb glass model of disordered localized electrons with long-range Coulomb interaction, which describes systems such as disordered insulators, granular metals, amorphous semiconductors, or doped crystalline semiconductors. Long ago Efros and Shklovskii showed that the long-range repulsion induces a soft Coulomb gap in the single particle density of states at low temperatures. Recent works suggested that this gap is associated to a transition to a glass phase, similar to the Almeida-Thouless transition in spin glasses. In this work, we use a mean field approach to characterize several physical properties of the Coulomb glass. In particular, following a seminal work of Bray and Moore, we show that the Edward-Anderson parameter qEA and the spin glass susceptibility ?SG are directly related to spectrum distribution of the Hessian matrix around free energy minima. Using this result, we show that no glass transition is associated to the gap formation.

Mandra, Salvatore; Palassini, Matteo

2012-02-01

237

Coulomb excitation of radioactive 20, 21 Na  

Microsoft Academic Search

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

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

2009-01-01

238

Experimental Proof of a Magnetic Coulomb Phase  

Microsoft Academic Search

Spin ice materials are magnetic substances in which the spin directions map\\u000aonto hydrogen positions in water ice. Recently this analogy has been elevated\\u000ato an electromagnetic equivalence, indicating that the spin ice state is a\\u000aCoulomb phase, with magnetic monopole excitations analogous to ice's mobile\\u000aionic defects. No Coulomb phase has yet been proved in a real magnetic\\u000amaterial,

Tom Fennell; P. P. Deen; A. R. Wildes; K. Schmalzl; D. Prabhakaran; A. T. Boothroyd; R. J. Aldus; D. F. McMorrow; S. T. Bramwell

2009-01-01

239

Laser Coulomb explosion imaging of molecular dynamics  

NASA Astrophysics Data System (ADS)

The goal of this dissertation project was to study the dynamics of nuclear motion in diatomic (H2, N2, O2, CO) and triatomic (CO2) molecules initiated by the ionization and/or excitation of these molecules with near-IR few-cycle laser pulses. This dynamics includes vibrational and rotational motion on the electronic potential surfaces of the molecules and their molecular ions. The experimental techniques used included the pump-probe approach, laser Coulomb explosion imaging and the COLTRIMS technique. The results are presented in four chapters. A study of rotational and vibrational nuclear dynamics in H2 and D2 molecules and ions initiated by 8 fs near-IR pulses is presented in Chapter 4. Transient alignment of the neutral molecules was observed and simulated; rotational frequency components contributing to the rotational wavepacket dynamics were recovered. Chapter 5 is dedicated to revealing the contribution of excited dissociative states of D2+ ions to the process of fragmentation by electron recollision. It was shown that it is possible to isolate the process of resonant excitation and estimate the individual contributions of the 2Sigmau+ and 2? u states. In Chapter 6 the subject of investigation is the nuclear dynamics of N2, O2 and CO molecules initiated by ionization of a neutral molecule by a short intense laser pulse. It was shown that the kinetic energy release of the Coulomb explosion fragments, measured as a function of the delay time between pump and probe pulses, reveals the behavior of nuclear wave packet evolution on electronic states of the molecular ions. It was shown that information on the dissociation and excitation pathways can be extracted from the experimental spectra and the relative contributions of particular electronic states can be estimated. Chapter 7 is focused on studying the fragmentation of CO2 following the interaction of this molecule with the laser field. The most important result of this study was that it presented direct experimental evidence of charge-resonant enhanced ionization (CREI), a phenomenon well-studied for diatomic molecules and predicted theoretically for triatomic molecules. The critical internuclear distance, the relevant ionic charge state and a pair of charge-resonant states responsible for the CREI were also found.

Bocharova, Irina A.

240

Interplay of nuclear and Coulomb effects in proton breakup from exotic nuclei  

NASA Astrophysics Data System (ADS)

This paper gives new insight to the study of dynamical effects in proton breakup as compared to neutron breakup from a weakly bound state in an exotic nucleus. To clarify and assess quantitatively which mechanism would dominate the measured observables, we study here several reaction mechanisms separately but also their total effect, including interference. These mechanisms are (i) the recoil effect of the core-target Coulomb potential which we distinguish from the direct proton-target Coulomb potential, and (ii) nuclear breakup, which consists of stripping and diffraction. Direct Coulomb breakup typically gives cross sections about an order of magnitude larger than the recoil term, and the amount of nuclear diffraction vs Coulomb depends on the target. Thus for each mechanism the absolute values of breakup cross sections and parallel momentum distributions for 8B and 17F projectiles calculated on a light and a heavy target in a range of intermediate incident energies (40A-80A MeV) are presented. Furthermore we study in detail the interference among the two Coulomb effects and nuclear diffraction. The calculation of the direct and recoil Coulomb effects separately and of their interference is the new and most relevant aspect of this paper.

Kumar, Ravinder; Bonaccorso, Angela

2012-12-01

241

Heavy-ion fusion using a parabolic barrier with Coulomb interaction  

SciTech Connect

In this work, we describe the fusion mechanism between two heavy ions as penetration through a parabolic barrier in the presence of a proper Coulomb interaction with appropriate boundary conditions. The parabolic potential is matched to the Coulomb potential in order to avoid any discontinuity of the potential surface. The Schroedinger equation in the exterior and interior regions containing, respectively, the Coulomb and the parabolic potentials are solved and the penetrability function is calculated from the logarithmic derivative at the matching radius. The theory is then applied to calculate the fusion cross sections for the reactions /sup 16/O+ /sup 16/O, /sup 12/C+ /sup 28en-dash30/Si, /sup 16/O+ /sup 24,26/Mg, /sup 16/O+/sup 28en-dash30/Si, and /sup 40/Ca+ /sup 40/Ca and are found to reproduce the data quite well. The theory is valid for energies both below and above the barrier.

Haider, Q.; Malik, F.B.

1982-07-01

242

WMAP dark matter constraints and Yukawa unification in supergravity models with CP phases  

SciTech Connect

The compatibility of producing the observed amount of dark matter, as indicated by the Wilkinson Microwave Anisotropy Probe (WMAP) data, through the relic abundance of neutralinos with Yukawa unification and with the measured rate of b{yields}s{gamma} is analyzed in mSUGRA and extended SUGRA unified models with the inclusion of CP phases. The CP phases affect the analysis in several ways, e.g., through the threshold corrections to the b-quark mass, via their effects on the neutralino relic density and through the supersymmetry (SUSY) contribution to the BR(b{yields}s{gamma}) which is sensitive to the CP phases. We present some specific models with large SUSY phases, which can accommodate the fermion electric dipole moment constraints and give a neutralino relic density in agreement with observations as well as with the b-{tau} unification constraint. The possibility of achieving WMAP relic density constraints with full Yukawa unification is also explored.

Gomez, Mario E. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain); Ibrahim, Tarek [Department of Physics, Northeastern University, Boston, Massachusetts 02115-5000 (United States); Nath, Pran [Department of Physics, Northeastern University, Boston, Massachusetts 02115-5000 (United States); Max Planck Institute for Physics, Fohringer Ring 6, D-80805, Munich (Germany); Skadhauge, Solveig [Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil)

2005-11-01

243

Coevolution of inverse cascade and nonlinear heat front in shear flows of strongly coupled Yukawa liquids  

SciTech Connect

Using classical molecular dynamics (MD) simulations, we report on the development and propagation of a nonlinear heat front in parallel shear flows of a strongly coupled Yukawa liquid. At a given coupling strength, a subsonic shear profile is superposed on an equilibrated Yukawa liquid and Kelvin Helmholtz (KH) instability is observed. Coherent vortices are seen to emerge towards the nonlinear regime of the instability. It is seen that while inverse cascade leads to a continuous transfer of flow energy towards the largest scales, there is also a simultaneous transfer of flow energy into the thermal velocities of grains at the smallest scale. The latter is an effect of velocity shear and thus leads to the generation of a nonlinear heat front. In the linear regime, the heat front is seen to propagate at speed much lesser than the adiabatic sound speed of the liquid. Spatio-temporal growth of this heat front occurs concurrently with the inverse cascade of KH modes.

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

2011-08-15

244

Random walk approximation in a chiral Yukawa-model and global symmetries  

NASA Astrophysics Data System (ADS)

The fermion propagator is investigated in a chiral Yukawa-model with explicit mirror fermions applying the random walk approximation to the hopping parameter expansion. It is shown that the global SU(2) L ? SU(2) R symmetry breaking due to the mass splitting within fermion doublets does influence the critical behaviour of the fermion spectrum in the continuum limit. In particular, in the case of a mirror pair of split doublets, where SU(2) L ? SU(2) R is broken to SU(2) L , no evidence is found for a dynamical spectrum doubling at infinitely strong bare Yukawa-couplings, in contrast to the case with degenerate doublets and SU(2) L ? SU(2) R symmetry.

Farakos, K.; Koutsoumbas, G.; Montvay, I.

1990-12-01

245

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

246

Application of the proximity force approximation to gravitational and Yukawa-type forces  

SciTech Connect

We apply the proximity force approximation, which is widely used for the calculation of the Casimir force between bodies with nonplanar boundary surfaces, to gravitational and Yukawa-type interactions. It is shown that for the gravitational force in a sphere-plate configuration the general formulation of the proximity force approximation is well applicable. For a Yukawa-type interaction we demonstrate the validity of both the general formulation of the proximity force approximation and a simple mapping between the sphere-plate and plate-plate configurations. The claims to the contrary in some recent literature are thus incorrect. Our results justify the constraints on the parameters of non-Newtonian gravity previously obtained from the indirect dynamic measurements of the Casimir pressure.

Decca, R. S. [Department of Physics, Indiana University--Purdue University Indianapolis, Indianapolis, Indiana 46202 (United States); Fischbach, E. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Klimchitskaya, G. L. [North-West Technical University, Millionnaya Street 5, St. Petersburg, 191065 (Russian Federation); Krause, D. E. [Physics Department, Wabash College, Crawfordsville, Indiana 47933 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Lopez, D. [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Mostepanenko, V. M. [Noncommercial Partnership 'Scientific Instruments', Tverskaya Street 11, Moscow, 103905 (Russian Federation)

2009-06-15

247

Coulomb-Oscillator Duality and Scattering Problem in 5Dimensional Coulomb Field  

Microsoft Academic Search

It is shown that the Hurwitz transformation connects the eight-dimensional repulsive oscillator problem with the five-dimensional Coulomb problem for continuous spectrum. The hyperspherical and parabolic bases for this system are calculated. The quantum mechanical scattering problem of charged particles in the 5-dimensional Coulomb field is solved.

Levon Mardoyan; Alex Manoogian

2003-01-01

248

Implications of Yukawa textures in the neutral Higgs decays within the 2HDM–III  

NASA Astrophysics Data System (ADS)

We discuss the implications of assuming a four–zero Yukawa ansatz for the neutral Higgs decays, within the context of the general 2–Higgs Doublet Model of type III. We begin by presenting a detailed analysis of the neutral Higgs boson couplings with fermions and gauge bosons and the resulting effects on its decays. In particular, we are interested on the possibility of the neutral Higgs boson production in current colliders.

Barradas–Guevara, J. E.; Bello–Martínez, H.; Félix–Beltrán, O.; Hernández–Sánchez, J.

2014-03-01

249

Description of strongly coupled Yukawa fluids using the variational modified hypernetted chain approach.  

PubMed

The variational modified hypernetted chain approach as proposed by J. Stat. Phys. 42, 437 (1986)] is used to describe strongly coupled Yukawa fluids. The integral equations of interest can be solved using the spherical harmonic oscillator wave functions as a seed. Comparisons are done with simulation results for equation of state and transport coefficients over the entire fluid domain for a wide range of the system parameters. PMID:15244740

Faussurier, G

2004-06-01

250

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

251

Evolution of Yukawa Couplings and Quark Flavour Mixings in the 5D MSSM  

NASA Astrophysics Data System (ADS)

The evolution equations of the Yukawa couplings and quark mixings are derived for the one-loop renormalization group equations in the 5D Minimal Supersymmetric Standard Model on an S1/Z2 orbifold. Different possibilities for the matter fields are discussed such as the cases of bulk propagating or brane localised fields. We discuss in both cases the evolution of the mass ratios and the implications for the mixing angles.

Abdalgabar, Ammar; Cornell, A. S.

2013-08-01

252

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

253

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

254

Sparticle mass spectra from SU(5) SUSY GUT models with b - ? Yukawa coupling unification  

NASA Astrophysics Data System (ADS)

Supersymmetric grand unified models based on the gauge group SU(5) often require in addition to gauge coupling unification, the unification of b-quark and ? -lepton Yukawa couplings. We examine SU(5) SUSY GUT parameter space under the condition of b - ? Yukawacouplingunificationusing2-loopMSSMRGEsincludingfull1-loopthreshold effects. The Yukawa-unified solutions break down into two classes. Solutions with low tan ? 3 - 11 are characterized by {m_{{mathop{g}limits^{˜ } }}} 1 - 4 TeV and {m_{{mathop{q}limits^{˜ } }}} 1 - 5 TeV. Many of these solutions would be beyond LHC reach, although they contain a light Higgs scalar with m h < 123 GeV and so may be excluded should the LHC Higgs hint persist. The second class of solutions occurs at large tan ? ˜ 35 - 60, and are a subset of t - b - ? unified solutions. Constraining only b - ? unification to ˜ 5% favors a rather light gluino with {m_{{mathop{g}limits^{˜ } }}} ˜ 0.5 - 2 TeV, which should ultimately be accessible to LHC searches. While our b - ? unified solutions can be consistent with a picture of neutralino-only cold dark matter, invoking additional moduli or Peccei-Quinn superfields can allow for all of our Yukawa-unified solutions to be consistent with the measured dark matter abundance.

Baer, Howard; Gogoladze, Ilia; Mustafayev, Azar; Raza, Shabbar; Shafi, Qaisar

2012-03-01

255

A heavier gluino from t-b-? Yukawa-unified SUSY  

NASA Astrophysics Data System (ADS)

Supersymmetric models with t-b-? Yukawa coupling unification and unified gaugino masses at the GUT scale-with ?>0-show a mild preference for light gluino masses m?500 GeV. This range of m is now essentially ruled out by LHC searches. We show that a heavier gluino with m?0.5-3 TeV can also be compatible with excellent t-b-? Yukawa coupling unification in supersymmetric models with non-universal Higgs masses (NUHM2). The gluino in such models is the lightest colored sparticle, while the squark sector displays an inverted mass hierarchy with m?5-20 TeV. We present some LHC testable benchmark points for which the lightest Higgs boson mass mh?125 GeV. We also discuss LHC signatures of Yukawa-unified models with heavier gluinos. We expect gluino pair production followed by decay to final states containing four b-jets plus four W-bosons plus missing ET to occur at possibly observable rates at LHC.

Baer, Howard; Raza, Shabbar; Shafi, Qaisar

2012-06-01

256

Coulomb interaction effects on the Majorana states in quantum wires  

NASA Astrophysics Data System (ADS)

The stability of the Majorana modes in the presence of a repulsive interaction is studied in the standard semiconductor wire–metallic superconductor configuration. The effects of short-range Coulomb interaction, which is incorporated using a purely repulsive ?-function to model the strong screening effect due to the presence of the superconductor, are determined within a Hartree–Fock approximation of the effective Bogoliubov–De Gennes Hamiltonian that describes the low-energy physics of the wire. Through a numerical diagonalization procedure we obtain interaction corrections to the single particle eigenstates and calculate the extended topological phase diagram in terms of the chemical potential and the Zeeman energy. We find that, for a fixed Zeeman energy, the interaction shifts the phase boundaries to a higher chemical potential, whereas for a fixed chemical potential this shift can occur either at lower or higher Zeeman energies. These effects can be interpreted as a renormalization of the g-factor due to the interaction. The minimum Zeeman energy needed to realize Majorana fermions decreases with the increasing strength of the Coulomb repulsion. Furthermore, we find that in wires with multi-band occupancy this effect can be enhanced by increasing the chemical potential, i.e. by occupying higher energy bands.

Manolescu, A.; Marinescu, D. C.; Stanescu, T. D.

2014-04-01

257

Influence of Coulomb interaction on the anisotropic Dirac cone in graphene  

NASA Astrophysics Data System (ADS)

Anisotropic Dirac cones can appear in a number of correlated electron systems, such as cuprate superconductors and deformed graphene. We study the influence of long-range Coulomb interaction on the physical properties of an anisotropic graphene by using the renormalization group method and 1/N expansion, where N is the flavor of Dirac fermions. Our explicit calculations reveal that the anisotropic fermion velocities flow monotonously to an isotropic fixed point in the lowest energy limit in clean graphene. We then incorporate three sorts of disorders, including random chemical potential, random gauge potential, and random mass, and show that the interplay of Coulomb interaction and disorders can lead to rich and unusual behaviors. In the presence of strong Coulomb interaction and a random chemical potential, the fermion velocities are driven to vanish at low energies and the system turns out to be an exotic anisotropic insulator. In the presence of Coulomb interaction and other two types of disorders, the system flows to an isotropic low-energy fixed point more rapidly than the clean case, and exhibits non-Fermi liquid behaviors. We also investigate the nonperturbative effects of Coulomb interaction, focusing on how the dynamical gap is affected by the velocity anisotropy. It is found that the dynamical gap is enhanced (suppressed) as the fermion velocities decrease (increase), but is suppressed as the velocity anisotropy increases.

Wang, Jing-Rong; Liu, Guo-Zhu

2014-05-01

258

Bethe-Salpeter equation at leading order in Coulomb gauge  

NASA Astrophysics Data System (ADS)

The Bethe-Salpeter equation and leptonic decay constants for pseudoscalar and vector quark-antiquark mesons with arbitrary quark masses are studied in Coulomb gauge, under a leading order truncation. As input, we use a pure linear rising potential, supplemented by a contact term arising from the conservation of total color charge. It is shown how the equations can be written in terms of manifestly finite functions, despite the infrared singular interaction. The resulting equations are solved numerically. Both the pattern of dynamical chiral symmetry breaking and the leading order heavy quark limit are visible.

Watson, P.; Reinhardt, H.

2012-12-01

259

Modeling of Coulomb interaction in parabolic quantum wires  

NASA Astrophysics Data System (ADS)

We study the exciton states in a parabolic quantum wire. An exactly solvable model is introduced for calculating the exciton state and the binding energy as a function of the radius of the quantum wire within the envelope-function approximation. In the calculation, we replace the actual Coulomb interaction between the electron and the hole by a Gaussian nonlocal separable potential and obtain closed expressions for both the envelope-function and the binding energy. Results are compared with those obtained by perturbative methods.

González-Santander, C.; Domínguez-Adame, F.

2009-09-01

260

Entanglement of spin-orbit qubits induced by Coulomb interaction  

NASA Astrophysics Data System (ADS)

Spin-orbit qubit (SOQ) is the dressed spin by the orbital degree of freedom through a strong spin-orbit coupling (SOC). We show that Coulomb interaction between two electrons in quantum dots located separately in two nanowires can efficiently induce quantum entanglement between two SOQs. But to achieve the highest possible value for two SOQs concurrence, strength of SOC and confining potential for the quantum dots should be tuned to an optimal ratio. The physical mechanism to achieve such quantum entanglement is based on the feasibility of the SOQ responding to the external electric field via an intrinsic electric dipole spin resonance.

Fang, Yinan; Turek, Yusuf; You, Jianqiang; Sun, Changpu

2014-06-01

261

Ice limit of Coulomb gauge Yang-Mills theory  

SciTech Connect

In this paper we describe gauge invariant multiquark states generalizing the path integral framework developed by Parrinello, Jona-Lasinio, and Zwanziger to amend the Faddeev-Popov approach. This allows us to produce states such that, in a limit which we call the ice limit, fermions are dressed with glue exclusively from the fundamental modular region associated with Coulomb gauge. The limit can be taken analytically without difficulties, avoiding the Gribov problem. This is illustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark-antiquark potential.

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom)

2008-10-01

262

Influence of the Coulomb-distortion effect on proton-proton observables  

NASA Astrophysics Data System (ADS)

The effect of the Coulomb distortion of the strong interaction is studied on the basis of nucleon-nucleon observables. In particular, cross sections, polarizations, spin-correlation parameters, and spin-transfer coefficients are considered for proton-proton as well as neutron-neutron scattering at laboratory kinetic energies Elab=10, 20, and 50 MeV. The calculations are performed for the meson-theoretical Paris potential, the nonlocal separable Graz potential, and also using the Arndt-Hackman-Roper parametrization of proton-proton scattering phase shifts. NUCLEAR REACTIONS N-N interaction; Coulomb corrections in polarization observables.

Plessas, W.; Mathelitsch, L.; Pauss, F.

1981-04-01

263

Nonlocal formulation of spin Coulomb drag  

NASA Astrophysics Data System (ADS)

The spin Coulomb drag (SCD) effect occurs in materials and devices where charged carriers with different spins exchange momentum via Coulomb scattering. This causes frictional forces between spin-dependent currents that lead to intrinsic dissipation, which may limit spintronics applications. A nonlocal formulation of SCD is developed which is valid for strongly inhomogeneous systems such as nanoscale spintronics devices. This nonlocal formulation of SCD is successfully applied to linewidths of intersubband spin plasmons in semiconductor quantum wells, where experiments have shown that the local approximation fails.

D'Amico, I.; Ullrich, C. A.

2013-10-01

264

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

265

Reconciling Coulomb Dissociation and Radiative Capture Measurements  

NASA Astrophysics Data System (ADS)

We calculate the energy spectrum for 8B dissociation on a Pb target to all orders in the Coulomb and nuclear fields, and show that the slope of S17(E) obtained in previous analyses of Coulomb dissociation data is too steep, due to deficiencies in the conventional first-order analysis that was used. With a more complete theory that avoids the far-field approximation and includes E2, nuclear and dynamical projectile polarization, the disagreement between indirect and direct methods for determining the S17(E) slope and the extrapolated S17(0) values is reduced significantly.

Esbensen, H.; Bertsch, G. F.; Snover, K. A.

2005-01-01

266

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

267

Coulombic Effects in Ion Mobility Spectrometry  

PubMed Central

Ion mobility spectrometry (IMS) has been increasingly employed in a number of applications. When coupled to mass spectrometry (MS), IMS becomes a powerful analytical tool for separating complex samples and investigating molecular structure. Therefore, improvements in IMS-MS instrumentation, e.g. 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 measurement throughput. However, large ion populations may manifest Coulombic effects contributing to the spatial dispersion of ions traveling in the IMS drift tube, and reduction in the 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 analytical 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. A noticeable decrease in the IMS resolving power was observed for ion populations of >10,000 elementary charges. The optimum IMS operation conditions which would minimize the Coulombic effects are discussed.

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

2009-01-01

268

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

269

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

270

Tables of mesoscopic 3D Coulomb balls  

Microsoft Academic Search

Detailed numerical results for the structural properties of three-dimensional classical Coulomb clusters confined in a spherical parabolic trap are presented. Based on extensive high accuracy computer simulations the shell configurations and energies for particle numbers in the range $2 \\\\le N\\\\le 160$ are reported. Further, the mean shell radii and shell widths are calculated.

P. Ludwig; S. Kosse; V. Golubnychiy; M. Bonitz; H. Fehske

2004-01-01

271

Discrete Coulomb Friction Problem: Solutions Stability  

NASA Astrophysics Data System (ADS)

A discrete contact problem with static Coulomb friction is considered. It is known that the problem may not have a unique solution. The aim is to investigate the solutions stability. To this end, we explore continuation (path-following) techniques for the numerical solution. In bioengineering, the application can arise in mathematical models of artificial joints.

Janovský, Vladimír

2010-09-01

272

The accuracy of the Gaussian-and-finite-element-Coulomb (GFC) method for the calculation of Coulomb integrals.  

PubMed

We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (?(H) = 2) and eight (?(1st) = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (?min (G)=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d(4) with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step-namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems; however, this scaling can be reduced to linear by introducing more effective techniques for recognizing significant three-center overlap distributions. PMID:23927250

Przybytek, Michal; Helgaker, Trygve

2013-08-01

273

The accuracy of the Gaussian-and-finite-element-Coulomb (GFC) method for the calculation of Coulomb integrals  

NASA Astrophysics Data System (ADS)

We analyze the accuracy of the Coulomb energy calculated using the Gaussian-and-finite-element-Coulomb (GFC) method. In this approach, the electrostatic potential associated with the molecular electronic density is obtained by solving the Poisson equation and then used to calculate matrix elements of the Coulomb operator. The molecular electrostatic potential is expanded in a mixed Gaussian-finite-element (GF) basis set consisting of Gaussian functions of s symmetry centered on the nuclei (with exponents obtained from a full optimization of the atomic potentials generated by the atomic densities from symmetry-averaged restricted open-shell Hartree-Fock theory) and shape functions defined on uniform finite elements. The quality of the GF basis is controlled by means of a small set of parameters; for a given width of the finite elements d, the highest accuracy is achieved at smallest computational cost when tricubic (n = 3) elements are used in combination with two (?H = 2) and eight (?1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (?minG=0.5). The error in the calculated Coulomb energy divided by the number of atoms in the system depends on the system type but is independent of the system size or the orbital basis set, vanishing approximately like d4 with decreasing d. If the boundary conditions for the Poisson equation are calculated in an approximate way, the GFC method may lose its variational character when the finite elements are too small; with larger elements, it is less sensitive to inaccuracies in the boundary values. As it is possible to obtain accurate boundary conditions in linear time, the overall scaling of the GFC method for large systems is governed by another computational step--namely, the generation of the three-center overlap integrals with three Gaussian orbitals. The most unfavorable (nearly quadratic) scaling is observed for compact, truly three-dimensional systems; however, this scaling can be reduced to linear by introducing more effective techniques for recognizing significant three-center overlap distributions.

Przybytek, Michal; Helgaker, Trygve

2013-08-01

274

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

275

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

276

Computer Simulation of Coulomb Explosion on (111) Silicon Surface.  

NASA Astrophysics Data System (ADS)

Coulomb explosion initiated by a highly charged Xe^+40 ion collision with a silicon (111) surface were studied by Molecular Dynamics. Time and space distributions of the silicon target density, hydrostatic pressure and instantaneous temperature within the Si sample were calculated. Time and velocity dependencies of sputtering yield for the secondary ions and neutral silicon atoms were studied. Calculated velocity distribution of Si sputtering yield was compared with available experimental data. The Si particles (up to 200,000) are placed initially in the nodes of the diamond-like lattice inside the sample of either 3D rectangular or hemispherical shape. The particles initially inside the hemisphere with its equator lying on the upper plane of the sample (up to 400 particles) are considered to be ions bearing the charge +e each. Realistic interaction potentials were used for the interactions between different kinds of particles. A parallel algorithm for calculation on cluster-type massive-parallel systems was developed for the simulation and used along with the consecutive one. The scalability analysis was performed for the consecutive and parallel computation speed with varying total number of particles for the two initial sample shapes. It shows that in both cases the parallel computations are preferable for larger samples than consecutive ones inspite of the fact that the three used potentials (Stillinger-Weber, ZBL-polarization and pure repulsive Coulomb) have very different spatial ranges of action.

Valuev, A.; Valuev, I.; Insepov, Z.; Sekioka, T.; Terasawa, A.

2002-08-01

277

Effective Coulomb force modeling for spacecraft in Earth orbit plasmas  

NASA Astrophysics Data System (ADS)

Coulomb formation flight is a concept that utilizes electrostatic forces to control the separations of close proximity spacecraft. The Coulomb force between charged bodies is a product of their size, separation, potential and interaction with the local plasma environment. A fast and accurate analytic method of capturing the interaction of a charged body in a plasma is shown. The Debye-Hückel analytic model of the electrostatic field about a charged sphere in a plasma is expanded to analytically compute the forces. This model is fitted to numerical simulations with representative geosynchronous and low Earth orbit (GEO and LEO) plasma environments using an effective Debye length. This effective Debye length, which more accurately captures the charge partial shielding, can be up to 7 times larger at GEO, and as great as 100 times larger at LEO. The force between a sphere and point charge is accurately captured with the effective Debye length, as opposed to the electron Debye length solutions that have errors exceeding 50%. One notable finding is that the effective Debye lengths in LEO plasmas about a charged body are increased from centimeters to meters. This is a promising outcome, as the reduced shielding at increased potentials provides sufficient force levels for operating the electrostatically inflated membrane structures concept at these dense plasma altitudes.

Seubert, Carl R.; Stiles, Laura A.; Schaub, Hanspeter

2014-07-01

278

Quantum partner-dance in the 12C + 12C system yields sub-Coulomb fusion resonances  

NASA Astrophysics Data System (ADS)

A preliminary study of the 12C + 12C sub-Coulomb fusion reaction using the time-dependent wave-packet method is presented. 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

2014-03-01

279

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

280

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

281

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

NASA Astrophysics Data System (ADS)

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.

Radzvilavi?ius, Ar?nas

2012-11-01

282

Solution of the mean spherical approximation for polydisperse multi-Yukawa hard-sphere fluid mixture using orthogonal polynomial expansions.  

PubMed

The Blum-Hoye [J. Stat. Phys. 19 317 (1978)] solution of the mean spherical approximation for a multicomponent multi-Yukawa hard-sphere fluid is extended to a polydisperse multi-Yukawa hard-sphere fluid. Our extension is based on the application of the orthogonal polynomial expansion method of Lado [Phys. Rev. E 54, 4411 (1996)]. Closed form analytical expressions for the structural and thermodynamic properties of the model are presented. They are given in terms of the parameters that follow directly from the solution. By way of illustration the method of solution is applied to describe the thermodynamic properties of the one- and two-Yukawa versions of the model. PMID:16555903

Kalyuzhnyi, Yurij V; Cummings, Peter T

2006-03-21

283

Solution of the mean spherical approximation for polydisperse multi-Yukawa hard-sphere fluid mixture using orthogonal polynomial expansions  

NASA Astrophysics Data System (ADS)

The Blum-Høye [J. Stat. Phys. 19 317 (1978)] solution of the mean spherical approximation for a multicomponent multi-Yukawa hard-sphere fluid is extended to a polydisperse multi-Yukawa hard-sphere fluid. Our extension is based on the application of the orthogonal polynomial expansion method of Lado [Phys. Rev. E 54, 4411 (1996)]. Closed form analytical expressions for the structural and thermodynamic properties of the model are presented. They are given in terms of the parameters that follow directly from the solution. By way of illustration the method of solution is applied to describe the thermodynamic properties of the one- and two-Yukawa versions of the model.

Kalyuzhnyi, Yurij V.; Cummings, Peter T.

2006-03-01

284

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

285

A general method to obtain Sturmian functions for continuum and bound state problems with Coulomb interactions  

Microsoft Academic Search

In this article, we investigate discretization schemes to represent Sturmian functions for both positive and negative energies in the presence of a long range Coulomb potential. We explore two methods to obtain Sturmian functions for positive energy. The first one involves the expansion of the radial wave function in a L2 finite basis set, whereas the second one introduces the

A. L. Frapiccini; J. M. Randazzo; G. Gasaneo; F. D. Colavecchia

2010-01-01

286

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

287

Semiclassical wave functions and semiclassical dynamics for the Kepler/Coulomb problem  

NASA Astrophysics Data System (ADS)

We investigate the semiclassical Kepler/Coulomb problem using the classical constants of the motion in the framework of Nelson’s stochastic mechanics. This is done by considering the eigenvalue relations for a family of coherent states (known as the atomic elliptic states) whose wave functions are concentrated on the elliptical orbit corresponding to the associated classical problem. We show that these eigenvalue relations lead to identities for the semiclassical energy, angular momentum and Hamilton–Lenz–Runge vectors in the elliptical case. These identities are then extended to include the cases of circular, parabolic and hyperbolic motions. We show that in all cases the semiclassical wave function is determined by our identities and so our identities can be seen as defining a semiclassical Kepler/Coulomb problem. The results are interpreted in terms of two dynamical systems: one a complex valued solution to the classical mechanics for a Coulomb potential and the other the drift field for a semiclassical Nelson diffusion.

Neate, Andrew; Truman, Aubrey

2014-06-01

288

Effect of topological defects and Coulomb charge on the low energy quantum dynamics of gapped graphene  

NASA Astrophysics Data System (ADS)

We study the combined effect of a conical topological defect and a Coulomb charge impurity on the dynamics of Dirac fermions in gapped graphene. Beyond a certain strength of the Coulomb charge, quantum instability sets in, which demarcates the boundary between sub- and supercritical values of the charge. In the subcritical regime, for certain values of the system parameters, the allowed boundary conditions in a gapped graphene cone can be classified in terms of a single real parameter. We show that the observables such as local density of states, scattering phase shifts and the bound state spectra are sensitive to the value of this real parameter, which is interesting from an empirical point of view. For a supercritical Coulomb charge, we analyze the system with a regularized potential as well as with a zigzag boundary condition and find the effect of the sample topology on the observable features of the system.

Chakraborty, Baishali; Gupta, Kumar S.; Sen, Siddhartha

2013-02-01

289

Renormalization of Coulomb interactions in s-wave superconductor NaCoO2  

NASA Astrophysics Data System (ADS)

We study the renormalized Coulomb interactions due to retardation effect in NaCoO2. Although the Morel Anderson's pseudo-potential for a1g orbital ?a1g* is relatively large because the direct Coulomb repulsion U is large, that for interband transition between a1g and eg? orbitals ?a1g,eg?* is very small since the renormalization factor for pair hopping J is square of that for U. Therefore, the s-wave superconductivity due to valence-band Suhl Kondo mechanism will survive against strong Coulomb interactions. The interband hopping of Cooper pairs due to shear phonons is essential to understand the superconductivity in NaCoO2.

Yada, Keiji; Kontani, Hiroshi

2007-03-01

290

Renormalization of Coulomb interactions in s-wave superconductor NaxCoO2  

NASA Astrophysics Data System (ADS)

We study the renormalized Coulomb interactions due to retardation effect in NaxCoO2. Although the Morel Anderson's pseudo-potential for a1g orbital ?a1g* is relatively large because the direct Coulomb repulsion U is large, that for interband transition between a1g and eg' orbitals ?a1g,eg'* is very small since the renormalization factor for pair hopping J is square of that for U. Therefore, the s-wave superconductivity due to valence-band Suhl-Kondo mechanism will survive against strong Coulomb interactions. The interband hopping of Cooper pairs due to shear phonons is essential to understand the superconductivity in NaxCoO2.

Yada, Keiji; Kontani, Hiroshi

291

Feynman rules for Coulomb gauge QCD  

SciTech Connect

The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.

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

2012-10-15

292

Dynamical Coulomb Blockade of Shot Noise  

NASA Astrophysics Data System (ADS)

We observe the suppression of the finite frequency shot noise produced by a voltage biased tunnel junction due to its interaction with a single electromagnetic mode of high impedance. The tunnel junction is embedded in a ? /4 resonator containing a dense SQUID array providing it with a characteristic impedance in the k? range and a resonant frequency tunable in the 4-6 GHz range. Such high impedance gives rise to a sizable Coulomb blockade on the tunnel junction (˜30% reduction in the differential conductance) and allows an efficient measurement of the spectral density of the current fluctuations at the resonator frequency. The observed blockade of shot noise is found in agreement with an extension of the dynamical Coulomb blockade theory.

Altimiras, Carles; Parlavecchio, Olivier; Joyez, Philippe; Vion, Denis; Roche, Patrice; Esteve, Daniel; Portier, Fabien

2014-06-01

293

The Coulomb sum rule of 40Ca  

NASA Astrophysics Data System (ADS)

We investigate the Coulomb sum rule of40Ca for the momentum transfer q=2.0 fm-1 in the framework of traditional nuclear many-body theory, namely, by using the G-matrix and the extended RPA theory. We have evaluated the one-body part (total chargeZ and the two-body part (two-body correlation function) of the Coulomb sum rule separately. A considerable part of the missing charge in the existing experimental data is found to be explained maily by the ground state correlations induced by the tensor force. It was also found that the one-body part (charge Z) is not in the existing experimental data.

Takayanagi, Kazuo

1989-10-01

294

Dynamical coulomb blockade of shot noise.  

PubMed

We observe the suppression of the finite frequency shot noise produced by a voltage biased tunnel junction due to its interaction with a single electromagnetic mode of high impedance. The tunnel junction is embedded in a ?/4 resonator containing a dense SQUID array providing it with a characteristic impedance in the k? range and a resonant frequency tunable in the 4-6 GHz range. Such high impedance gives rise to a sizable Coulomb blockade on the tunnel junction (?30% reduction in the differential conductance) and allows an efficient measurement of the spectral density of the current fluctuations at the resonator frequency. The observed blockade of shot noise is found in agreement with an extension of the dynamical Coulomb blockade theory. PMID:24972223

Altimiras, Carles; Parlavecchio, Olivier; Joyez, Philippe; Vion, Denis; Roche, Patrice; Esteve, Daniel; Portier, Fabien

2014-06-13

295

Trapping of Topological-Structural Defects in Coulomb Crystals  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

296

Coulomb collision effects on linear Landau damping  

NASA Astrophysics Data System (ADS)

Coulomb collisions at rate ? produce slightly probabilistic rather than fully deterministic charged particle trajectories in weakly collisional plasmas. Their diffusive velocity scattering effects on the response to a wave yield an effective collision rate ?eff ? ? and a narrow dissipative boundary layer for particles with velocities near the wave phase velocity. These dissipative effects produce temporal irreversibility for times t ? 1/?eff during Landau damping of a small amplitude Langmuir wave.

Callen, J. D.

2014-05-01

297

Unification, KK-thresholds and the top Yukawa coupling in F-theory GUTs  

NASA Astrophysics Data System (ADS)

In a class of F-theory SU(5) GUTs the low energy chiral mass spectrum is obtained from rank one fermion mass textures with a hierarchical structure organized by U(1) symmetries embedded in the exceptional E 8 group. In these theories chiral fields reside on matter `curves' and the tree-level masses are computed from integrals of overlapping wave functions of the particles at the triple intersection points. This calculation requires knowledge of the exact form of the wave functions. In this work we propose a way to obtain a reliable estimate of the various quantities which determine the strength of the Yukawa couplings. We use previous analysis of KK-threshold effects to determine the (ratios of) heavy mass scales of the theory which are involved in the normalization of the wave functions. We consider similar effects from the chiral spectrum of these models and discuss possible constraints on the emerging matter content. In this approach, we find that the Yukawa couplings can be determined solely from the U(1) charges of the states in the `intersection' and the torsion which is a topological invariant quantity. We apply the results to a viable SU(5) model with minimal spectrum which satisfies all the constraints imposed by our analysis. We use renormalization group analysis to estimate the top and bottom masses and find that they are in agreement with the experimental values.

Leontaris, G. K.; Tracas, N. D.; Tsamis, G.

2011-10-01

298

Bounding the top Yukawa coupling with Higgs-associated single-top production  

NASA Astrophysics Data System (ADS)

After the discovery of the 125 GeV scalar boson with gauge properties similar to the Standard Model (SM) Higgs, the search for beyond the SM interactions will focus on studying the discovered particles' coupling properties more precisely and shedding light on the relation of fermion masses with the electroweak vacuum. The large mass of the top quark and the SM-predicted order one top Yukawa coupling is a natural candidate for beyond the SM physics, though experimentally challenging to constrain. In this paper, we argue that investigating angular correlations in pp?tHj production provides an excellent handle to constrain the top Yukawa coupling yt via direct measurements, even when we focus on rare exclusive final states. We perform a hadron-level analysis and show that we may expect to constrain yt?0.5ytSM at 95%-99% confidence level at the high luminosity LHC using semileptonic top decays and H??? alone, by employing a two-channel measurement approach.

Englert, Christoph; Re, Emanuele

2014-04-01

299

Properties of gravitationally equilibrated Yukawa systems-A molecular dynamics study  

NASA Astrophysics Data System (ADS)

Using 2D Molecular Dynamics simulation, the equilibrium and dynamical properties of a gravitationally equilibrated Yukawa liquid are investigated. We observe that due to asymmetry introduced in one direction by gravity, several interesting features arise. For example, for a given value of coupling parameter ?, screening parameter ?, and according to a chosen value of gravitational force g (say in y-direction), the system is seen to exhibit super-, sub- or normal diffusion. Interestingly, x-averaged density profiles, unlike a barotropic fluid, acquires sharp, free surface with scale free linear y-dependence. As can be expected for a system with macroscopic gradients, self-diffusion calculated from Green-Kubo's formalism does not agree with that obtained from Einstein-Smoluchowski diffusion. A 2D angular-radial pair correlation function g(r, ?) clearly indicates asymmetric features induced by gravity. We observe that due to compression in y-direction, though in liquid state for all values of gravity considered, the transverse mode is found to predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid.

Charan, Harish; Ganesh, Rajaraman; Joy, Ashwin

2014-04-01

300

Quark sector of the QCD groundstate in Coulomb gauge  

NASA Astrophysics Data System (ADS)

The variational approach to Yang-Mills theory in Coulomb gauge is extended to full QCD. For the quark sector we use a trial wave functional, which goes beyond the previously used BCS-type state and which explicitly contains the coupling of the quarks to transverse gluons. This quark wave functional contains two variational kernels: one is related to the quark condensate and occurs already in the BCS-type states; the other represents the form factor of the coupling of the quarks to the transverse gluons. Minimization of the energy density with respect to these kernels results in two coupled integral (gap) equations. These equations are solved numerically using the confining part of the non-Abelian color Coulomb potential and the lattice static gluon propagator as input. With the additional coupling of quarks to transverse gluons included, the low energy chiral properties increase substantially towards their phenomenological values. We obtain a reasonable description of the chiral condensate, which for a vanishing current quark mass is obtained in the range of 190-235 MeV. The coupling of the quarks to the transverse gluons enhances the constituent quark mass by about 60% in comparison to the pure BCS Ansatz.

Pak, M.; Reinhardt, H.

2013-12-01

301

Coulomb drag between ballistic quantum wires  

NASA Astrophysics Data System (ADS)

We develop a kinetic equation description of Coulomb drag between ballistic one-dimensional electron systems, which enables us to demonstrate that equilibration processes between right- and left-moving electrons are crucially important for establishing dc drag. In one-dimensional geometry, this type of equilibration requires either backscattering near the Fermi level or scattering with small-momentum transfer near the bottom of the electron spectrum. Importantly, pairwise forward scattering in the vicinity of the Fermi surface alone is not sufficient to produce a nonzero dc drag resistivity ?D, in contrast to a number of works that have studied Coulomb drag due to this mechanism of scattering before. We show that slow equilibration between two subsystems of electrons of opposite chirality, “bottlenecked” by inelastic collisions involving cold electrons near the bottom of the conduction band, leads to a strong suppression of Coulomb drag, which results in an activation dependence of ?D on temperature, instead of the conventional power law. We demonstrate the emergence of a drag regime in which ?D does not depend on the strength of interwire interactions, while depending strongly on the strength of interactions inside the wires.

Dmitriev, A. P.; Gornyi, I. V.; Polyakov, D. G.

2012-12-01

302

Coulomb Interaction Effect in Cell Projection Lithography  

NASA Astrophysics Data System (ADS)

In cell projection lithography, critical dimension (CD) control is one of the important issues for device fabrication as well as resolution. Because plural patterns are exposed in one shot under the same dose, the proximity effect correction is more difficult than in the conventional variable-shaped beam (VSB) lithography. We have analyzed the CD deviation in order to obtain high CD accuracy of less than 0.02 µ m (range) which is sufficient for manufacturing 1 G dynamic randam access memory (DRAM). We have found that the Coulomb interaction effect plays an important role in CD deviation. We have proposed a new exposure intensity distribution (EID) function which contains a factor introduced for the first time to compensate the proximity effect and the Coulomb interaction effect simultaneously. The results indicate that the new EID function is very effective to compensate the Coulomb interaction effect and improve the CD deviation from 12% (0.03 µ m) to 6% (0.015 µ m) for 0.25 µ m lines-and-spaces (L/S) patterns.

Yamashita, Hiroshi; Tamura, Takao; Nomura, Eiichi; Nozue, Hiroshi

1995-12-01

303

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

304

Exciton condensation and perfect Coulomb drag.  

PubMed

Coulomb drag is a process whereby the repulsive interactions between electrons in spatially separated conductors enable a current flowing in one of the conductors to induce a voltage drop in the other. If the second conductor is part of a closed circuit, a net current will flow in that circuit. The drag current is typically much smaller than the drive current owing to the heavy screening of the Coulomb interaction. There are, however, rare situations in which strong electronic correlations exist between the two conductors. For example, double quantum well systems can support exciton condensates, which consist of electrons in one well tightly bound to holes in the other. 'Perfect' drag is therefore expected; a steady transport current of electrons driven through one quantum well should be accompanied by an equal current of holes in the other. Here we demonstrate this effect, taking care to ensure that the electron-hole pairs dominate the transport and that tunnelling of charge between the quantum wells, which can readily compromise drag measurements, is negligible. We note that, from an electrical engineering perspective, perfect Coulomb drag is analogous to an electrical transformer that functions at zero frequency. PMID:22914164

Nandi, D; Finck, A D K; Eisenstein, J P; Pfeiffer, L N; West, K W

2012-08-23

305

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.

306

Particle interaction measurements in a Coulomb crystal using caged-particle motion.  

PubMed

A technique for characterizing the particle interaction potential of a Coulomb crystal is developed. The mean-square displacement (MSD) is measured, showing both caged- and superdiffusive-particle motions. By subtracting the center of mass of neighboring particles in computing MSD, only short-wavelength particle motions are retained. This yields the lattice Einstein frequency, which contains information about the interparticle forces and potentials. Video measurements of particle motions in a complex (dusty) plasma are used to demonstrate the technique. PMID:12005638

Quinn, R A; Goree, J

2002-05-13

307

Parabolic Sturmians approach to the three-body continuum Coulomb problem  

Microsoft Academic Search

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

S. A. Zaytsev; Yu. V. Popov; B. Piraux

2011-01-01

308

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

309

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications  

NASA Technical Reports Server (NTRS)

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion. It is predicted that this will lead to an increase

Marshall, J. R.

1999-01-01

310

Steps Towards Cavity QED experiments with cold ion Coulomb Crystals  

NASA Astrophysics Data System (ADS)

Clouds of ions present an interesting alternative to traditional single neutral atom based experiments to study CQED. Ions can be easily trapped and cooled for long times and in sufficient number to potentially access the strong coupling regime even with a physically realizable finesse (mode volume) of the cavity. In the present experiment thousands of ^40Ca^+ ions are trapped in a linear Paul trap incorporating a high finesse (F˜3200) optical cavity. We will show results which indicate that the number of ions inside the cavity mode is in principle high enough to achieve strong collective coupling. Near term plans include fundamental studies of cavity QED, and exploring the possibility of using cavity interactions to aid in cooling of neutral molecular species. Briefly discussed will be a planned experiment which will employ an optical field to further investigate and control the nature of the ion Coulomb crystal structures formed.

Marler, J. P.; Herskind, P.; Dantan, A.; Albert, M.; Drewsen, M.

2008-05-01

311

Strong nuclear couplings as a source of Coulomb rainbow suppression  

SciTech Connect

A recent measurement of the {sup 11}Be+{sup 64}Zn quasielastic scattering angular distribution exhibits a non-Fresnel-type pattern, in contrast to {sup 6}He+{sup 64}Zn elastic scattering but similar to that for the elastic scattering of {sup 6}He from heavy targets. We show by means of continuum discretized coupled-channels (CDCC) calculations that this unusual behavior of {sup 11}Be is caused by the much greater importance of nuclear coupling to the continuum in {sup 11}Be compared to {sup 6}He, 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. [Department of Nuclear Reactions, The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, PL-00-681 Warsaw (Poland); Alamanos, N. [CEA Saclay DSM/IRFU/DIR, F-91 191 Gif-sur-Yvette Cedex (France); Kemper, K. W. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Rusek, K. [Heavy Ion Laboratory, University of Warsaw, ul. Pasteura 5A, PL-02-093 Warsaw (Poland); Department of Nuclear Reactions, The Andrzej Soltan Institute for Nuclear Studies, ul. Hoza 69, PL-00-681 Warsaw (Poland)

2010-09-15

312

Spectrum of classical two-dimensional Coulomb clusters.  

PubMed

The frequency spectrum of a system of classical charged particles interacting through a Coulomb repulsive potential and which are confined in a two-dimensional parabolic trap is studied. It is shown that, apart from the well-known center-of-mass and breathing modes, which are independent of the number of particles in the cluster, there are more "universal" modes whose frequencies depend only slightly on the number of particles. To understand these modes the spectrum of excitations as a function of the number of particles is compared with the spectrum obtained in the hydrodynamic approach. The modes are classified according to their averaged vorticity and it is shown that these "universal" modes have the smallest vorticity and follow the hydrodynamic behavior. PMID:16486295

Nelissen, K; Matulis, A; Partoens, B; Kong, M; Peeters, F M

2006-01-01

313

Coulomb gauge confinement in the heavy quark limit  

SciTech Connect

The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.

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

2010-05-15

314

Equation of state for magnetized Coulomb plasmas  

NASA Astrophysics Data System (ADS)

We have developed an analytical equation of state (EOS) for magnetized fully-ionized plasmas that cover a wide range of temperatures and densities, from low-density classical plasmas to relativistic, quantum plasma conditions. This EOS directly applies to calculations of structure and evolution of strongly magnetized white dwarfs and neutron stars. We review available analytical and numerical results for thermodynamic functions of the nonmagnetized and magnetized Coulomb gases, liquids, and solids. We propose a new analytical expression for the free energy of solid Coulomb mixtures. Based on recent numerical results, we have constructed analytical approximations for the thermodynamic functions of harmonic Coulomb crystals in quantizing magnetic fields. The analytical description ensures a consistent evaluation of all astrophysically important thermodynamic functions based on the first, second, and mixed derivatives of the free energy. Our numerical code for calculation of thermodynamic functions based on these approximations has been made publicly available. Using this code, we calculate and discuss the effects of electron screening and magnetic quantization on the position of the melting point in a range of densities and magnetic fields relevant to white dwarfs and outer envelopes of neutron stars. We consider also the thermal and mechanical structure of a magnetar envelope and argue that it can have a frozen surface which covers the liquid ocean above the solid crust. The Fortran code that realizes the analytical approximations described in this paper is available at http://www.ioffe.ru/astro/EIP/ and at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A43

Potekhin, A. Y.; Chabrier, G.

2013-02-01

315

Ultrathin foils for Coulomb-explosion experiments  

SciTech Connect

We have examined the properties of very thin foils used for electron stripping of MeV molecular ions in Coulomb-explosion experiments. Carbon foils with a nominal thickness of 0.2 ..mu..g/cm/sup 2/ proved to be thicker than 1 ..mu..g/cm/sup 2/. It was not possible to reduce their thickness by bombardment with 2-MeV Kr/sup +/ or H/sub 2/O/sup +/ ions or by heating to a red glow. We succeeded in producing Formvar films of about 0.5 ..mu..g/cm/sup 2/, which are supported by a nickel mesh.

Both, G.; Kanter, E.P.; Vager, Z.; Zabransky, B.J.; Zajfman, D.

1987-03-01

316

Coulombic dragging of molecular assemblies on nanotubes  

NASA Astrophysics Data System (ADS)

We show by molecular dynamics simulations that polar molecules, ions and their assemblies could be Coulombically dragged on the surfaces of single-wall carbon and boron-nitride nanotubes by ionic solutions or individual ions moving inside the nanotubes [1,2]. We also briefly discuss highly selective ionic sieves based on graphene monolayers with nanopores [3]. These phenomena could be applied in molecular delivery, separation and desalination.[3pt] [1] Boyang Wang and Petr Kral, JACS 128, 15984 (2006). [0pt] [2] Boyang Wang and Petr Kral, Phys. Rev. Lett. 101, 046103 (2008). [0pt] [3] Kyaw Sint, Boyang Wang and Petr Kral, JACS, ASAP (2008).

Kral, Petr; Sint, Kyaw; Wang, Boyang

2009-03-01

317

Coulomb excitation of atoms by fast protons  

SciTech Connect

A Green's function technique is developed for calculating the dependence of the energy loss of heavy charged particles on the impact parameter in the quasiclassical approximation. Formulas are derived for the probabilities of bound-bound transitions in hydrogenlike atoms, and for their asymptotic values in the dipole approximation and in the strong coupling approximation. Simpler expressions than those previously derived are obtained for bound-free transitions. An analysis of the contributions of various Coulomb excitation channels is carried out on the basis of the results. An exact calculation of the energy losses shows that the mean-frequency approximation is not valid for the inner shell electrons.

Ryabov, V.A.; Yudin, G.L.

1980-02-01

318

Two-body Coulomb problems with sources  

SciTech Connect

The two-body Coulomb Schroedinger equation with different types of nonhomogeneities are studied. The particular solution of these nonhomogeneous equations is expressed in closed form in terms of a two-variable hypergeometric function. A particular representation of the latter allows one to study efficiently the solution in the asymptotic limit of large values of the coordinate and hence the associated physics. Simple sources are first considered, and a complete analysis of scattering and bound states is performed. The solutions corresponding to more general (arbitrary) sources are then provided and written in terms of more general hypergeometric functions.

Gasaneo, G. [Departamento de Fisica, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8000 Bahia Blanca, Buenos Aires (Argentina); Ancarani, L. U. [Laboratoire de Physique Moleculaire et des Collisions, Universite Paul Verlaine-Metz, F-57078 Metz (France)

2010-10-15

319

Phase of the Coulomb Amplitude in the Second Born Approximation  

NASA Astrophysics Data System (ADS)

The method of calculating the Coulomb phase in the second Born order with allowance for the hadron form factor is presented. The phase of the modified Coulomb amplitude can be calculated exactly by taking account of the form factor of hadrons. The phase with the dipole form factor is estimated; as a result, the behavior of the total phase of the Coulomb-hadron interference changes as a function of the transfer momentum.

Selyugin, O. V.

320

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

321

Equilibrium properties and phase diagram of two-dimensional Yukawa systems.  

PubMed

Properties of two-dimensional strongly coupled Yukawa systems are explored through molecular dynamics simulations. An effective coupling coefficient gamma* for the liquid phase is introduced on the basis of the constancy of the first peak amplitude of the pair-correlation functions. Thermodynamic quantities are calculated from the pair-correlation function. The solid-liquid transition of the system is investigated through the analysis of the bond-angular order parameter. The static structure function satisfies consistency relation, attesting to the reliability of the computational method. The response is shown to be governed by the correlational part of the inverse compressibility. An analysis of the velocity autocorrelation demonstrates that this latter also exhibits a universal behavior. PMID:16196720

Hartmann, P; Kalman, G J; Donkó, Z; Kutasi, K

2005-08-01

322

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

2012-08-01

323

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

324

Hyperspherical Coulomb spheroidal representation in the Coulomb three-body problem  

NASA Astrophysics Data System (ADS)

A new representation of the Coulomb three-body wavefunction via the well-known solutions of the separable Coulomb two-centre problem phij(?, ?) = Xj(?)Yj(?) is obtained, where Xj(?) and Yj(?) are the Coulomb spheroidal functions. Its distinguishing characteristic is the coordination with the asymptotic conditions of the scattering problem below the three-particle breakup. That is, the wavefunction of two colliding clusters in any open channel is the asymptotics of the single, corresponding to that channel, term of the suggested expansion. The effect is achieved due to a new relation between three internal coordinates of a three-body system and the parameters of phij(?, ?). It ensures the orthogonality of phij(?, ?) on a sphere of constant hyperradius, ? = const, in place of the surface R = |x2 - x1| = const appearing in the traditional Born-Oppenheimer approach. The independent variables ? and ? are the orthogonal coordinates on this sphere with three poles in the coalescence points. They are connected with the elliptic coordinates on the plane by means of a stereographic projection. For the total angular momentum J >= 0 the products of phij and the Wigner D-functions form a hyperspherical Coulomb spheroidal (HSCS) basis on a five-dimensional hypersphere, ? being a parameter. The system of the differential equations and the boundary conditions for the radial functions fJi(?), the coefficients of the HSCS decomposition of the three-body wavefunction, are presented.

Abramov, D. I.

2008-09-01

325

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

326

Coulomb's Law and Electric Field Package  

NSDL National Science Digital Library

The EJS Coulomb's Law and Electric Field Package is a collection of models for electrostatics. Users can move charges around and see the force, observe the electric field generated by charge configurations, and observe the motion of test particles in electric fields. Also included are student worksheets in pdf format to supplement each simulation. Users can inspect and modify any simulation in the package by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Coulomb's Law and Electric Field Package was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_electric_sampler.jar file will launch the package if Java is installed. Navigate within the package and click on a green triangle to run a particular simulation. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Cox, Anne; Christian, Wolfgang; Franciscouembre

2009-12-07

327

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

328

Coulomb Reacceleration Studies of ^11Be ^1  

NASA Astrophysics Data System (ADS)

The breakup reaction of the halo nucleus ^11Be has been the subject of several recent studies, including a recent experiment footnote T. Nakamura et al., Phys. Lett. B 33, 296 (1994) which reported significant Coulomb reacceleration effects. The results were interpreted as supporting instantaneous breakup, in contrast to strong theoretical arguments footnote T. Kido, et al., Phys. Rev. C 50, R1276 (1994), for example that reacceleration effects should not be present due to the weak ^11Be binding energy. Here we report a new, precise measurement of the Coulomb reacceleration in the dissociation of 42 MeV/nucleon beam of ^11Be on a gold target. The ^10Be fragments and the elastic scattering from the beam were observed at four angles between 0^circ and 5^circ with the S320 magnetic spectrograph at MSU. Our results will be contrasted with those of Ref. [1] and with comparison measurements made with a light target and with a ^10Be beam. A unique aspect of this measurement is that the ? rays from the target and from the excited state of the ^10Be fragments were measured in coincidence with the breakup by an array of BaF2 detectors which surrounded the target.

Bush, J. E.; Balamuth, D. P.; Hausladen, P.; Pohl, K. R.; Bazin, D.; Brown, J.; Caggiano, J. A.; Chen, L.; Davids, B.; Morrissey, D. J.; Sherrill, B. M.; Thoennessen, M.

1996-05-01

329

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

330

Effects of Coulomb Interactions on Disordered Two-Dimensional Systems.  

NASA Astrophysics Data System (ADS)

This dissertation is divided into two parts. Part I examines the effects of screening by a metallic electrode on the Coulomb gap, and related properties. The computer model restricts electrons to the lattice points of a two -dimensional square lattice. Disorder results from a random potential energy assigned to each lattice site. Screening is by image charges resulting from a simulated metal plate placed at a distance h/2 from the electron surface, with image charges a distance h from the electrons. The results show the single-particle density of states and the single-particle density of excitations as a function of the distance h. Part II relates to recent experiments on mesoscopic metal-oxide semiconductor field effect transistors ^* (MOSFETs). The experimental results show sharp peaks in the source-drain current as a function of the gate voltage. The peaks are believed to be due to coherent tunneling between the source and drain electrodes, via a localized state near the center. The structure of such peaks at low temperatures is expected to be Lorentzian, but the observed peaks had a non-Lorentzian character, and also exhibited resolvable secondary peaks on the shoulders of the main peak. These features were interpreted as due to Coulomb interactions between the tunneling site and electrons which may enter or exit the localized states during the experiment and excitations internal to the system. We have performed computer simulations based upon the above model. The results, while not entirely conclusive, seemed to verify the approach taken. ftn^dag Supported in part by the San Diego Supercomputer Center. ^SSupported in part by TRW, Space and Defense Sector. *A. B. Fowler, G. L. Timp, J. J. Wainer and R. A. Webb, Phys. Rev. Lett. 57, 138 (1986).

Green, Mark Christopher

331

Generalized Kepler-Coulomb system: inter basis expansions.  

National Technical Information Service (NTIS)

This paper deals with a dynamic system that generalizes the Kepler-Coulomb system and the Hartmann system. It is shown that the Schroedinger equation for this generalized Kepler-Coulomb system can be separated in prolate spheroidal coordinates. The coeffi...

M. Kibler L. G. Mardoyan G. S. Pogosyan

1994-01-01

332

On a generalized Kepler-Coulomb system: Inter basis expansions  

Microsoft Academic Search

This paper deals with a dynamic system that generalizes the Kepler-Coulomb system and the Hartmann system. It is shown that the Schroedinger equation for the generalized Kepler-Coulomb system can be separated in prolate spheroidal coordinates. The coefficients of the inter basis expansions between three bases (spherical, parabolic and spheroidal) are studied in detail. It is found that the coefficients for

M. Kibler; L. G. Mardoyan; G. S. Pogosyan

1994-01-01

333

Coulomb-interacting Dirac fermions in disordered graphene  

Microsoft Academic Search

We study such experimentally relevant characteristics of the Coulomb-interacting Dirac quasiparticles in disordered graphene as the quasiparticle width and density of states that can be probed by photoemission, magnetization, and tunneling measurements. We find that an interplay between the unscreened Coulomb interactions and pseudorelativistic quasiparticle kinematics can be best revealed in the ballistic regime, whereas in the diffusive limit the

D. V. Khveshchenko

2006-01-01

334

The Hahn polynomials in the nonrelativistic and relativistic Coulomb problems  

Microsoft Academic Search

We derive closed formulas for mean values of all powers of r in nonrelativistic and relativistic Coulomb problems in terms of the Hahn and Chebyshev polynomials of a discrete variable. A short review on special functions and solution of the Coulomb problems in quantum mechanics is given.

Sergei K. Suslov; Benjamin Trey

2008-01-01

335

Dynamical effects in the Coulomb expansion following nuclear fragmentation  

SciTech Connect

The effects of the Coulomb expansion on the fragment kinetic energy spectrum for a fragmentating hot nuclear system is investigated. In particular, /sup 12/C-fragment spectra are calculated and compared with those predicted by the uniform expansion approximation. The results indicate that the energy spectra of fragments are quite sensitive to the details of the Coulomb expansion treatment.

Chung, K.C.; Donangelo, R.; Schechter, H.

1987-09-01

336

Spin transport through atomic scale chromium Coulomb islands  

Microsoft Academic Search

Electrical current through metallic islands coupled via tunnel barriers to external leads is governed by the Coulomb repulsion and can be brought down to single electron transport. The spin-degeneracy of the electrons can be lifted by choosing both the leads and the islands to be magnetic. The combination of spin-splitting and Coulomb blockade creates a device geometry capable of resonant

Marc van Veenhuizen; Jagadeesh Moodera

2006-01-01

337

The Hahn polynomials in the nonrelativistic and relativistic Coulomb problems  

SciTech Connect

We derive closed formulas for mean values of all powers of r in nonrelativistic and relativistic Coulomb problems in terms of the Hahn and Chebyshev polynomials of a discrete variable. A short review on special functions and solution of the Coulomb problems in quantum mechanics is given.

Suslov, Sergei K.; Trey, Benjamin [Department of Mathematics and Statistics, Arizona State University, Tempe, Arizona 85287 (United States); Department of Physics and Astronomy, University of Hawaii at Manoa, 2505 Correa Road, Honolulu, Hawaii 96822 (United States)

2008-01-15

338

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

339

Coulomb gauge model for hidden charm tetraquarks  

NASA Astrophysics Data System (ADS)

The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (( singlet-singlet (molecule) and the (( triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with ((cc) states about half a GeV lighter than ((. The lightest 1 and 1 predictions are in agreement with the observed X(3872) and Y(4008) masses suggesting they are molecules with ?J/? and ?hc, rather than D*D and DDbar, type structure, respectively. Similarly, the lightest isovector 1 molecule, having a ?J/? flavor composition, has mass near the recently observed charged Zc(3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to ??J/?.

Xie, W.; Mo, L. Q.; Wang, Ping; Cotanch, Stephen R.

2013-08-01

340

Cluster Dynamics: Fast Reactions and Coulomb Explosion  

NASA Astrophysics Data System (ADS)

One of the enduring mysteries of chemistry is exactly what happens during the few femtoseconds it takes for a chemical reaction to transpire. We see what goes in and what comes out, but the in between happens so fast it has proved devilishly hard to study. One promising area of investigation involves the use of clusters—tiny atomic or molecular assemblages with weak bonding. Clusters can be rapidly ionized using laser pulses of very short duration, producing like charges of sufficient intensity and closeness to cause explosive repulsion, called Coulomb explosion. By carefully adjusting the delivery interval between femtosecond-duration laser pulses to clusters, the authors have begun to reveal the secrets of reaction dynamics.

Poth, Lutz; Wisniewski, Eric S.; Welford Castleman, A., Jr.

2002-07-01

341

Coulomb energy differences in isobaric multiplets  

SciTech Connect

By comparing the excitation energies of analogue states in isobaric multiplets, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. In particular, the mirror nuclei 35Ar and 35Cl show large differences between the excitation energies of analogue negative-parity states at high spin, confirming the important contribution of the relativistic electromagnetic spin-orbit interaction to the Coulomb energy. The single-particle character of the configuration of these states is reproduced with very good accuracy by shell model calculations in the sd and pf shells valence space. In addition, evidence of isospin mixing is deduced from the El transitions linking positive and negative parity states.

Lenzi, S. M.; Farnea, E.; Bazzacco, D.; Brandolini, F.; Lunardi, S.; Mason, P.; Menegazzo, R.; Nespolo, M.; Ur, C. A. [Dipartimento di Fisica dell' Universita, Padova (Italy); INFN, Padova (Italy); Della Vedova, F.; Marginean, N.; Napoli, D. R.; De Angelis, G.; Axiotis, M.; Gadea, A. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Italy); Ionescu-Bujor, M.; Bucurescu, D.; Iordachescu, A. [National Institute for Physics and Nuclear Engineering, Bucharest (Romania); Bizzeti-Sona, A. M.; Bizzeti, P. G. [Dipartimento di Fisica dell' Universita, Florence (Italy); INFN, Florence (Italy)] (and others)

2007-02-12

342

Ferroelectric Instability Under Screened Coulomb Interactions  

NASA Astrophysics Data System (ADS)

We explore the effect of charge carrier doping on ferroelectricity using density functional calculations and phenomenological modeling. By considering a prototypical ferroelectric material, BaTiO3, we demonstrate that ferroelectric displacements are sustained up to the critical concentration of 0.11 electron per unit cell volume. This result is consistent with experimental observations and reveals that the ferroelectric phase and conductivity can coexist. Our investigations show that the ferroelectric instability requires only a short-range portion of the Coulomb force with an interaction range of the order of the lattice constant. These results provide a new insight into the origin of ferroelectricity in displacive ferroelectrics and open opportunities for using doped ferroelectrics in novel electronic devices.

Wang, Yong; Liu, Xiaohui; Burton, J. D.; Jaswal, Sitaram S.; Tsymbal, Evgeny Y.

2012-12-01

343

Thermodynamic functions of magnetized Coulomb crystals  

NASA Astrophysics Data System (ADS)

Free energy, internal energy and specific heat for each of the three phonon spectrum branches of a magnetized Coulomb crystal with body-centred cubic lattice are calculated by numerical integration over the Brillouin zone in the range of magnetic fields B and temperatures T, such that 0 ? ?B/?p ? 103 and 10-4 ? T/Tp ? 104. In this case, ?B is the ion cyclotron frequency, ?p and Tp are the ion plasma frequency and plasma temperature, respectively. The results of numerical calculations are approximated by simple analytical formulas. For illustration, these formulas are used to analyse the behaviour of the heat capacity in the crust of a neutron star with strong magnetic field. Thermodynamic functions of magnetized neutron star crust are needed for modelling various observational phenomena in magnetars and high magnetic field pulsars.

Baiko, D. A.; Yakovlev, D. G.

2013-08-01

344

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

345

Coulomb Gauge Hamiltonian: Advances and Applications  

NASA Astrophysics Data System (ADS)

Theoretical developments and applications of an effective QCD Hamiltonian in the Coulomb gauge are summarized. BCS, TDA and RPA many-body diagonalizations in the quark and gluon sectors are reported for meson and glueball spectra, respectively. The model glueball Regge trajectories are in good agreement with the established pomeron and a recently observed odd signature daughter. Using the pomeron-glueball connection and vector meson dominance, glueball photoproduction cross sections and decays are calculated and a glueball experimental signature is predicted. The pseudoscalar-vector meson mass splittings are also investigated using a hyperfine interaction based upon transverse gluon exchange. An improved meson spectrum is obtained and the dominant role of chiral symmetry in the p-r mass difference is confirmed.

Cotanch, Stephen R.

346

Chiral symmetry patterns of excited mesons with the Coulomb-like linear confinement  

Microsoft Academic Search

The spectrum of $\\\\bar q q$ mesons in a model where the only interaction is a\\u000alinear Coulomb-like instantaneous confining potential is studied. The\\u000asingle-quark Green function as well as the dynamical chiral symmetry breaking\\u000aare obtained from the Schwinger-Dyson (gap) equation. Given the dressed quark\\u000apropagator, a complete spectrum of \\

R. F. Wagenbrunn; L. Ya. Glozman

2007-01-01

347

Dynamical screening of the Coulomb interaction for two confined electrons in a magnetic field  

Microsoft Academic Search

We show that a difference in time scales of vertical and lateral dynamics\\u000apermits one to analyze the problem of interacting electrons confined in an\\u000aaxially symmetric three-dimensional potential with a lateral oscillator\\u000aconfinement by means of the effective two-dimensional Hamiltonian with a\\u000ascreened Coulomb interaction. Using an adiabatic approximation based on\\u000aaction-angle variables, we present solutions for the effective

N. Simonovi?; R. G. Nazmitdinov

2008-01-01

348

Dynamical screening of the Coulomb interaction for two confined electrons in a magnetic field  

Microsoft Academic Search

We show that a difference in time scales of vertical and lateral dynamics permits one to analyze the problem of interacting electrons confined in an axially symmetric three-dimensional potential with a lateral oscillator confinement by means of the effective two-dimensional Hamiltonian with a screened Coulomb interaction. Using an adiabatic approximation based on action-angle variables, we present solutions for the effective

N. S. Simonovic; R. G. Nazmitdinov

2008-01-01

349

Accuracy of Coulomb Stripping for Measuring SingleParticle Reduced Widths in Nuclei  

Microsoft Academic Search

A finite-range n-p potential and the effect of deuteron stretch have been introduced into a distorted-wave Born-approximation (DWBA) analysis of the d-p stripping process for the case in which both deuteron and proton have energies below the Coulomb barrier. This energy region was chosen because it permits an estimate of the experimental reduced width which does not depend significantly on

Faison P. Gibson; Arthur K. Kerman

1966-01-01

350

Non-homogeneous solutions of a Coulomb Schrödinger equation as basis set for scattering problems  

NASA Astrophysics Data System (ADS)

We introduce and study two-body Quasi Sturmian functions which are proposed as basis functions for applications in three-body scattering problems. They are solutions of a two-body non-homogeneous Schrödinger equation. We present different analytic expressions, including asymptotic behaviors, for the pure Coulomb potential with a driven term involving either Slater-type or Laguerre-type orbitals. The efficiency of Quasi Sturmian functions as basis set is numerically illustrated through a two-body scattering problem.

Del Punta, J. A.; Ambrosio, M. J.; Gasaneo, G.; Zaytsev, S. A.; Ancarani, L. U.

2014-05-01

351

Nonadiabatic Coulomb effects in strong-field ionization in circularly polarized laser fields  

NASA Astrophysics Data System (ADS)

We develop the recently proposed analytical R-matrix (ARM) method to encompass strong-field ionization by circularly polarized fields, for atoms with arbitrary binding potentials. Through the ARM method, the effect of the core potential can now be included consistently both during and after ionization. We find that Coulomb effects modify the ionization dynamics in several ways, including modification of (i) the ionization times, (ii) the initial conditions for the electron continuum dynamics, (iii) the “tunneling angle” at which the electron “enters” the barrier, and (iv) the electron drift momentum. We derive analytical expressions for the Coulomb-corrected ionization times, initial velocities, momentum shifts, and ionization rates in circularly polarized fields, for arbitrary angular momentum of the initial state. We also analyze how nonadiabatic Coulomb effects modify (i) the calibration of the attoclock in the angular streaking method and (ii) the ratio of ionization rates from p- and p+ orbitals, predicted by Barth and Smirnova [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.84.063415 84, 063415 (2011)] for short-range potentials.

Kaushal, Jivesh; Smirnova, Olga

2013-07-01

352

Experimental tests of Coulomb's Law and the photon rest mass  

NASA Astrophysics Data System (ADS)

Coulomb's Law is a fundamental principle describing the electric force between isolated charges, and represents the first quantitative law achieved in electromagnetism. The degree of confidence with which the law is experimentally known to hold was investigated after the law was put forth by Coulomb in 1785. The electrodynamics for massive particles suggests that a photon with a finite rest mass will cause a deviation from the inverse square law. So, modern interpretations of the possible deviation from Coulomb's inverse square law are usually associated with the non-zero photon mass. In this article, we first give a historical review of the foundation of Coulomb's inverse square law. Then, the experimental searches for validity of Coulomb's Law, particularly in its inverse square nature, are generally introduced. Based on Proca's equations, the unique simplest relativistic generalization of Maxwell's equations, the link between the deviation from Coulomb's Law and the upper limit on the photon rest mass based on the concentric-spheres apparatus established in the classical experiment of Cavendish is reviewed. Up to now, all the experiments show no evidence for a positive value, and the experimental result was customarily expressed as an upper limit on the deviation or on the photon rest mass. As a representative method with the double mission of testing of the validity of Coulomb's Law and of the photon rest mass, possible improvements for this kind of experiment are discussed.

Tu, Liang-Cheng; Luo, Jun

2004-10-01

353

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

354

Freezing lines of colloidal Yukawa spheres. I. A Rogers-Young integral equation study.  

PubMed

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. PMID:22260603

Gapinski, Jacek; Nägele, Gerhard; Patkowski, Adam

2012-01-14

355

Structure and thermodynamics of hard-core Yukawa fluids: thermodynamic perturbation approaches.  

PubMed

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. PMID:21787011

Kim, Eun-Young; Kim, Soon-Chul; Seong, Baek-Seok

2011-07-21

356

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

357

Yukawa corrections to {gamma}{gamma}{yields}bb in the topcolor assisted technicolor models  

SciTech Connect

We study the Yukawa corrections to the {gamma}{gamma}{yields}bb cross section in the topcolor assisted technicolor models at the photon-photon colliders. We find that, for the favorable parameters, the relative corrections from pseudo-Goldstone bosons give out a 3.2%{approx}5.9% decrement of the cross section from the tree level when {radical}(s)=500 GeV, the contributions from new extended technicolor gauge bosons Z* and colored gauge bosons B are negligibly small, and the relative correction arising from new color-singlet heavy gauge boson Z{sup '} is less than -3.2%. Therefore, the total relative corrections are significantly larger than the corresponding corrections in the standard model, the general two Higgs doublet model, and the minimal supersymmetric standard model. Since these corrections are obvious for the International Linear Colliders, the process {gamma}{gamma}{yields}bb is really interesting in testing the standard model and searching for the signs of technicolor.

Huang Jinshu [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Department of Physics, Nanyang Normal University, Nanyang 473061 (China); Lu Gongru [Department of Physics, Henan Normal University, Xinxiang 453007 (China)

2008-08-01

358

Yukawas, G-flux, and spectral covers from resolved Calabi-Yau's  

NASA Astrophysics Data System (ADS)

We use the resolution procedure of Esole and Yau [1] to study Yukawa couplings, G-flux, and the emergence of spectral covers from elliptically fibered Calabi-Yau's with a surface of A 4 singularities. We provide a global description of the Esole-Yau resolution and use it to explicitly compute Chern classes of the resolved 4-fold, proving the conjecture of [2] for the Euler character in the process. We comment on the physical implications of the surprising singular fibers in codimension 2 and 3 in [1] and emphasize a group theoretic interpretation based on the A 4 weight lattice. We then construct explicit G-fluxes by brute force in one of the 6 birationally equivalent Esole-Yau resolutions, quantize them explicitly using our result for the second Chern class, and compute the spectrum and flux-induced 3-brane charges, finding agreement with results and conjectures of local models in all cases. Finally, we provide a precise description of the spectral divisor formalism in this setting and sharpen the procedure described in [3] in order to explicitly demonstrate how the Higgs bundle spectral cover of the local model emerges from the resolved Calabi-Yau geometry. Along the way, we demonstrate explicitly how the quantization rules for fluxes in the local and global models are related.

Marsano, Joseph; Schäfer-Nameki, Sakura

2011-11-01

359

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

360

Probing wrong-sign Yukawa couplings at the LHC and a future linear collider  

NASA Astrophysics Data System (ADS)

We consider the two-Higgs-doublet model as a framework in which to evaluate the viability of scenarios in which the sign of the coupling of the observed Higgs boson to down-type fermions (in particular, b-quark pairs) is opposite to that of the Standard Model (SM), while at the same time all other tree-level couplings are close to the SM values. We show that, whereas such a scenario is consistent with current LHC observations, both future running at the LHC and a future e+e- linear collider could determine the sign of the Higgs coupling to b-quark pairs. Discrimination is possible for two reasons. First, the interference between the b-quark and the t-quark loop contributions to the ggh coupling changes sign. Second, the charged-Higgs loop contribution to the ??h coupling is large and fairly constant up to the largest charged-Higgs mass allowed by tree-level unitarity bounds when the b-quark Yukawa coupling has the opposite sign from that of the SM (the change in sign of the interference terms between the b-quark loop and the W and t loops having negligible impact).

Ferreira, P. M.; Santos, Rui; Gunion, John F.; Haber, Howard E.

2014-06-01

361

3D Oscillator and Coulomb Systems reduced from Kahler spaces  

Microsoft Academic Search

We define the oscillator and Coulomb systems on four-dimensional spaces with\\u000aU(2)-invariant Kahler metric and perform their Hamiltonian reduction to the\\u000athree-dimensional oscillator and Coulomb systems specified by the presence of\\u000aDirac monopoles. We find the Kahler spaces with conic singularity, where the\\u000aoscillator and Coulomb systems on three-dimensional sphere and two-sheet\\u000ahyperboloid are originated. Then we construct the superintegrable

Armen Nersessian; Armen Yeranyan

2003-01-01

362

Influence of proton beam Coulomb explosion in laser proton acceleration  

NASA Astrophysics Data System (ADS)

To further understand proton acceleration driven by the interaction between ultra-intense laser pulse and foil targets, the influence of proton beam Coulomb explosion has been analyzed theoretically and investigated using two-dimensional particle-in-cell (2D-PIC) simulations. Employing different proton layer sizes in the simulations, it is found that proton beam Coulomb explosion plays an important role on proton acceleration, in particular on proton cut off energy. Proton dynamics including the effect of both sheath field and proton beam Coulomb explosion was proposed and discussed in detail. This work may serve to improve the understanding of proton acceleration driven by intense laser-foil interactions.

Yu, Jinqing; Jin, Xiaolin; Zhou, Weimin; Gu, Yuqiu; Zhan, Rongxin; Zhao, Zongqing; Cao, Leifeng; Li, Bin

2013-12-01

363

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

364

Coulomb crystals in the magnetic field.  

PubMed

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 > or approximately equal 10(14) G ). 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. PMID:19905459

Baiko, D A

2009-10-01

365

Unstable System with Coulomb Interaction Distorted Near the Origin.  

National Technical Information Service (NTIS)

An unstable system with Coulomb interaction distorted at small distances is considered. The results are applicable to hadronic atoms analysis. A detailed investigation of the model which can be solved exactly is presented. This model contains the separabl...

B. O. Kerbikov

1981-01-01

366

A position sensitive gas detector system for Coulomb excitation experiments  

NASA Astrophysics Data System (ADS)

A position sensitive parallel-plate avalanche counter for detection of heavy ions, primarily from Coulomb excitation experiments, is presented. The angular region is 40° < ? < 140°, with a division in ? of 2°.

Varnestig, Björn; Bäcklin, Anders; Fahlander, Claes; Kavka, Alexander E.; Lenke, Tomas; Svensson, Lars Erik

1986-08-01

367

Quark model of nuclear matter and the Coulomb sum rule  

SciTech Connect

Subnucleonic degrees of freedom of nucleons, e.g., delta resonances, quark confinement, and dibaryons, are described in terms of the quark model of hadrons. Also, Coulomb sum rules from electron scattering from nuclei are discussed. (AIP)

Horowitz, C.J.; Panoff, R.

1984-11-15

368

Computational assignment of redox states to Coulomb blockade diamonds.  

PubMed

With the advent of molecular transistors, electrochemistry can now be studied at the single-molecule level. Experimentally, the redox chemistry of the molecule manifests itself as features in the observed Coulomb blockade diamonds. We present a simple theoretical method for explicit construction of the Coulomb blockade diamonds of a molecule. A combined quantum mechanical/molecular mechanical method is invoked to calculate redox energies and polarizabilities of the molecules, including the screening effect of the metal leads. This direct approach circumvents the need for explicit modelling of the gate electrode. From the calculated parameters the Coulomb blockade diamonds are constructed using simple theory. We offer a theoretical tool for assignment of Coulomb blockade diamonds to specific redox states in particular, and a study of chemical details in the diamonds in general. With the ongoing experimental developments in molecular transistor experiments, our tool could find use in molecular electronics, electrochemistry, and electrocatalysis. PMID:25020007

Olsen, Stine T; Arcisauskaite, Vaida; Hansen, Thorsten; Kongsted, Jacob; Mikkelsen, Kurt V

2014-07-30

369

Atomic multipole polarizabilities in the extended Coulomb approximation  

Microsoft Academic Search

A new and computationally convenient exact analytic expression for the 2l-pole static polarizabilities of mono and divalent atoms and ions is obtained within the extended Coulomb approximation of Adelman and Szabo. In this approximation the valence electron wavefunction is represented by an asymptotically valid Whittaker function with hydrogenic normalization and the l-symmetry excited orbitals are eigenfunctions of a Coulombic Hamiltonian

Gene Lamm; Attila Szabo

1977-01-01

370

Electronic Correlation Effects and the Coulomb Gap at Finite Temperature  

Microsoft Academic Search

We have investigated the effect of the long-range Coulomb interaction on the one-particle excitation spectrum of n-type germanium, using tunneling spectroscopy on mechanically controllable break junctions. At low temperatures, the tunnel conductance shows a minimum at zero bias voltage due to the Coulomb gap. Above 1 K, the gap is filled by thermal excitations. This behavior is reflected in the

B. Sandow; K. Gloos; R. Rentzsch; A. N. Ionov; W. Schirmacher

2001-01-01

371

The generalized parabolic Coulomb wavefunction in spherical coordinates  

Microsoft Academic Search

In this work we present a detailed study of the recently introduced Deltam,n basis for three Coulomb particles. We show that the scattering and generalized Coulomb problems as well as a Phi2 approach can be viewed as particular cases of this basis. We derive a partial wave expansion for Deltam,n functions and analyse the reduction to some of the precedent

G. Gasaneo; F. D. Colavecchia; S. Otranto; C. R. Garibotti

2001-01-01

372

Diffusion and Coulomb separation of ions in dense matter.  

PubMed

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. PMID:24182248

Beznogov, M V; Yakovlev, D G

2013-10-18

373

Coulomb excitation of radioactive ²¹Na and its stable mirror ²¹Ne  

Microsoft Academic Search

The low-energy structures of the mirror nuclei ²¹Ne and radioactive ²¹Na have been examined by using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of 5x10 ions\\/s were accelerated to 1.7 MeV\\/A and Coulomb excited in a 0.5 mg\\/cm² {sup nat}Ti target. Scattered beam and target particles were detected by the segmented Si detector BAMBINO, while rays were

M. A. Schumaker; C. E. Svensson; G. A. Demand; P. Finlay; P. E. Garrett; K. L. Green; G. F. Grinyer; K. G. Leach; A. A. Phillips; J. Wong; D. Cline; A. B. Hayes; A. Whitbeck; G. Hackman; A. C. Morton; C. J. Pearson; A. Andreyev; G. C. Ball; L. Buchmann; R. Churchman

2008-01-01

374

Coulomb exchange contribution in nuclear Hartree-Fock calculations  

Microsoft Academic Search

The validity of commonly used approximations for Coulomb exchange terms is checked by an exact calculation of the total Coulomb contribution to the Hartree-Fock field. The Skyrme SIII effective force has been chosen for the nuclear part of the interaction. Calculated nuclei range from 16O to 56Ni through deformed s-d shell nuclei. Laboratoire associé au C.N.R.S.

C. Titin-Schnaider; Ph. Quentin

1974-01-01

375

Relativistic semiclassical theory of the Coulomb excitation of atoms  

SciTech Connect

The processes of Coulomb excitation and ionization of atoms by fast charged particles moving along classical trajectories are considered. The target electrons are described by the Dirac equation and the field of the incoming particle is described by the Lienard-Wiechert potential. The theory is formulated in a form most convenient for the description of all the characteristics of semiclassical atomic collisions. Analytic expressions are obtained in the cases of small and large momentum transfers for K-shell ionization cross sections and for the probabilities and cross sections for the 1S/sub 1/2/..-->..2S/sub 1/2/, 1S/sub 1/2/..-->..2P/sub 1/2/, and 2S/sub 1/2/..-->..2P/sub 1/2/ transitions in a heavy hydrogen-like atom. The stimulated multiphoton emission and absorption processes that occur in inelastic scattering of relativistic electrons by light atoms in an external electromagnetic field are considered. Universal relations are derived in the low-frequency approximation for the total cross section for stimulated absorption in all the inelastic channels.

Yudin, G.L.

1982-09-01

376

Defect-driven phase transitions out of the Coulomb phase  

NASA Astrophysics Data System (ADS)

Lattice models constrained by a local "conservation law," such as close-packed dimer models on 3D bipartite lattices, exhibit an emergent "Coulomb phase" with characteristic power-law correlations. We have studied, by Monte Carlo simulations, phase transitions out of the Coulomb phase induced by introducing a finite fugacity of defect excitations in dimer models. We report two cases. (1) In the simple cubic dimer covering, we admit non- bipartite dimers (connecting sites in the same sublattice), which appear as effective charges with Coulomb-like interactions. Non- bipartite defects induce a transition immediately out of the Coulomb phase, exponentially damping the critical correlations via Debye screening. We characterize this transition by extracting the screening length from our numerical calculation of the dimer structure factor.(2) In the diamond lattice, we initially restrict the dimers to a 2D layer forming a (bipartite) honeycomb lattice, and then admit interlayer dimers. These bipartite dimers appear as dipoles and do not destroy the Coulomb phase, but induce an immediate transition from a 2D to 3D Coulomb phase.

Ju, Hyejin; Trebst, Simon; Henley, Christopher

2011-03-01

377

Fast and accurate Coulomb calculation with Gaussian functions  

NASA Astrophysics Data System (ADS)

Coulomb interaction is one of the major time-consuming components in a density functional theory (DFT) calculation. In the last decade, dramatic progresses have been made to improve the efficiency of Coulomb calculation, including continuous fast multipole method (CFMM) and J-engine method, all developed first inside Q-Chem. The most recent development is the advent of Fourier transform Coulomb method developed by Fusti-Molnar and Pulay, and an improved version of the method has been recently implemented in Q-Chem. It replaces the least efficient part of the previous Coulomb methods with an accurate numerical integration scheme that scales in O(N2) instead of O(N4) with the basis size. The result is a much smaller slope in the linear scaling with respect to the molecular size and we will demonstrate through a series of benchmark calculations that it speeds up the calculation of Coulomb energy by several folds over the efficient existing code, i.e., the combination of CFMM and J-engine, without loss of accuracy. Furthermore, we will show that it is complementary to the latter and together the three methods offer the best performance for Coulomb part of DFT calculations, making the DFT calculations affordable for very large systems involving thousands of basis functions.

Füsti-Molnár, László; Kong, Jing

2005-02-01

378

The equation-transform model for Dirac–Morse problem including Coulomb tensor interaction  

SciTech Connect

The approximate solutions of Dirac equation with Morse potential in the presence of Coulomb-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 obtained. By using convolution integral, the corresponding radial wave functions are presented in terms of confluent hypergeometric functions. -- Highlights: •The Dirac equation with tensor interaction is solved by using Laplace transform. •For solving this equation, we introduce the equation-transform model. •Numerical results and plots for pseudospin and spin symmetric solutions are given. •The obtained numerical results by using transform method are compared with orthogonal polynomial method.

Ortakaya, Sami, E-mail: sami.ortakaya@yahoo.com

2013-11-15

379

Quantum Simulator for the Hubbard Model with Long-Range Coulomb Interactions Using Surface Acoustic Waves  

NASA Astrophysics Data System (ADS)

An experimental scheme for a quantum simulator of strongly correlated electrons is proposed. Our scheme employs electrons confined in a two-dimensional electron gas in a GaAs/AlGaAs heterojunction. Two surface acoustic waves are then induced in the substrate, creating a two-dimensional “egg-carton” potential. The dynamics of the electrons in this potential are described by a Hubbard model with long-range Coulomb interactions. Estimates of the Hubbard parameters suggest that observations of quantum phase transition phenomena are within experimental reach.

Byrnes, Tim; Recher, Patrik; Kim, Na Young; Utsunomiya, Shoko; Yamamoto, Yoshihisa

2007-07-01

380

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

381

Final state interaction and Coulomb effect for neutrino-nucleus scattering in the quasielastic region  

SciTech Connect

We study the effect of final state interaction between outgoing nucleons and residual nuclei through total cross sections of neutrino-nucleus scattering within the framework of a relativistic single-particle model in the quasielastic region. To investigate the effect of the FSI, a relativistic phenomenological optical potential and a real potential for final nucleons are used. The real potential refers to no loss of flux while the optical potential indicates an absorption. We calculate both neutral-current reaction such as (v, v') and charged-current reactions like (v{sub e}, e{sup -}) and (v{sub {mu}}, {mu}{sup -}). In these calculations, {sup 12}C is used as a target nucleus and the incident neutrino (antineutrino) energies are exploited up to 2 GeV. We find that the effect of the FSI by the optical potential reduces cross sections about 50% and about 15% for the real potential. Furthermore, in the case of the charged-current reaction, we also calculate the Coulomb distortion of the outgoing leptons for {sup 12}C, {sup 40}Ca, and {sup 208}Pb. As a consequence, the effect of the Coulomb distortion is about a half by comparing with the case of electron scattering.

Kim, K. S. [School of Liberal Arts and Science, Korea Aerospace University, Koyang, 412-791 (Korea, Republic of); Cheoun, M. K. [Department of Physics, Soongsil University, Seoul, 156-743 (Korea, Republic of)

2009-11-25

382

The role of Coulomb interaction in thermoelectric effects of an Aharonov-Bohm interferometer  

NASA Astrophysics Data System (ADS)

We investigate the thermoelectric effects of an Aharonov-Bohm (AB) interferometer with a quantum dot (QD) embedded in each of its arms, where the intra-dot Coulomb interaction between electrons in each QD is taken into account. Using Green's function methods and the equation of motion (EOM) technique, we find that the Seebeck coefficient and Lorenz number can be strongly enhanced when the chemical potential sweeps the molecular states associated with the Fano line-shapes in the transmission spectra, due to quantum interference effects between the bonding and antibonding molecular states. It is found that enhancement of the thermoelectric effects occurs between the two groups of conductance peaks in the presence of strong intra-dot Coulomb interaction—the reason being that a transmission node is developed in the Coulomb blockade regime. In this case, the maximum value of the Lorenz number approaches 10?2kB2/(3e2). Its thermoelectric conversion efficiency in the absence of phonon thermal conductance, described by the figure of merit ZT, approaches 2 at room temperature. Therefore, it may be used as a high-efficiency solid-state thermoelectric conversion device under certain circumstances.

Liu, Yu-Shen; Zhang, De-Bao; Yang, Xi-Feng; Feng, Jin-Fu

2011-06-01

383

Crossover from impurity to valence band in diluted magnetic semiconductors: Role of Coulomb attraction by acceptors  

NASA Astrophysics Data System (ADS)

The crossover between an impurity band (IB) and a valence band (VB) regime as a function of the magnetic impurity concentration in a model for diluted magnetic semiconductors (DMSs) is studied systematically by taking into consideration the Coulomb attraction between the carriers and the magnetic impurities. The density of states and the ferromagnetic transition temperature of a spin-fermion model applied to DMSs are evaluated using dynamical mean-field theory and Monte Carlo (MC) calculations. It is shown that the addition of a square-well-like attractive potential can generate an IB at small enough Mn doping x for values of the p - d exchange J that are not strong enough to generate one by themselves. We observe that the IB merges with the VB when x?xc where xc is a function of J and the Coulomb strength V . Using MC simulations, we demonstrate that the range of the Coulomb attraction plays an important role. While the on-site attraction, which has been used in previous numerical simulations, effectively renormalizes J for all values of x , an unphysical result, a nearest-neighbor range attraction renormalizes J only at very low dopings, i.e., until the bound holes wave functions start to overlap. Thus, our results indicate that the Coulomb attraction can be neglected to study Mn-doped GaSb , GaAs , and GaP in the relevant doping regimes, but it should be included in the case of Mn-doped GaN , which is expected to be in the IB regime.

Popescu, F.; ?en, C.; Dagotto, E.; Moreo, A.

2007-08-01

384

Two-loop top-Yukawa-coupling corrections to the Higgs boson masses in the complex MSSM  

NASA Astrophysics Data System (ADS)

Results for the leading two-loop corrections of O(?t2) from the Yukawa sector to the Higgs-boson masses of the MSSM with complex parameters are presented. The corresponding self-energies and their renormalization have been obtained in a Feynman-diagrammatic approach. A numerical analysis of the new contributions is performed for the mass of the lightest Higgs boson, supplemented by the full one-loop result and the O(?t?s) terms including complex phases. In the limit of the real MSSM a previous result is confirmed.

Hollik, Wolfgang; Paßehr, Sebastian

2014-06-01

385

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

386

Measuring the Relative CP-Even and CP-ODD Yukawa Couplings of a Higgs Boson at a Muon-Collider Higgs Factory  

Microsoft Academic Search

We study a possibility of a measurement of muon Yukawa couplings in s-channel\\u000aHiggs boson production at a muon collider with transversely polarized beams. We\\u000ainvestigate sensitivity to the relative size of the CP-odd and CP-even muon\\u000aYukawa couplings. Provided the event rate observed justify the operation of the\\u000a$\\\\mu^+\\\\mu^-$ Higgs boson factory, we have found that polarization degree 40%

J. Pliszka; J. F. GUNION

2000-01-01

387

Basic thermodynamic parameters of a black hole resulting from a Yukawa type of correction to the metric  

NASA Astrophysics Data System (ADS)

There has been a renewed interest in the recent years in the possibility of deviations from the predictions of Newton's "inverse-square law" of universal gravitation. One of the reasons for renewing this interest lies in various theoretical attempts to construct a unified elementary particle theory, in which there is a natural prediction of new forces over macroscopic distances. Therefore the existence of such a force would only coexist with gravity, and in principle could only be detected as a deviation from the inverse square law, or in the "universality of free fall" experiments. New experimental techniques such that of Sagnac interferometry can help explore the range of the Yukawa correction ??1014 m where such forces might be present. It may be, that future space missions might be operating in this range which has been unexplored for very long time. In this paper we derive the basic thermodynamic parameters of such a Yukawa stationary spherically symmetric black hole. First, the expression for the event horizon of such a black hole is derived, with the help of which the temperature, entropy and heat capacity of this particular black hole are obtained. We have also obtained analytical expressions for the change of mass of such black hole, and also its corresponding evaporation time.

Haranas, Ioannis; Gkigkitzis, Ioannis

2012-02-01

388

Imaging quantum Hall Coulomb islands inside a quantum ring  

NASA Astrophysics Data System (ADS)

In the quantum Hall regime near integer filling factors, electrons are transmitted through edge states confined at the borders of the device. In mesoscopic samples, however, edge states may be sufficiently close to allow electrons to tunnel, or to be transmitted through localized states ("Coulomb islands") [1]. Here, we use the biased tip of a low temperature scanning gate microscope to alter tunneling through quantum Hall Coulomb islands localized inside a quantum ring patterned in an InGaAs/InAlAs heterostructure. Simultaneously, we map the quantum ring resistance and observe different sets of concentric resistance fringes, due to charging/discharging of each Coulomb island. Tuning the magnetic field and the tip voltage, we reveal the rich and complex behaviour of these fringes [2].[4pt] [1] B. Rosenow and B. I. Halperin, PRL 98, 106801 (2007).[0pt] [2] B. Hackens et al., Nature Communications 1, 39 (2010).

Martins, Frederico; Hackens, Benoit; Faniel, Sebastien; Bayot, Vincent; Pala, Marco; Sellier, Hermann; Huant, Serge; Desplanque, Ludovic; Wallart, Xavier

2011-03-01

389

Quasiparticle Gaps and Exciton Coulomb Energies in Si Nanoshells  

SciTech Connect

Quasiparticle gaps and exciton Coulomb energies of H-passivated spherical Si nanoshells are computed using rst principles SCF and GW methods. We nd that the quasiparticle gap of a nanoshell depends on both its inner radius R1 (weakly) and outer radius R2 (strongly). These dependences on R1 and R2 are mostly consistent with electrostatics of a metallic shell. We also nd that the unscreened Coulomb energy ECoul in Si nanoshells has a somewhat unexpected size dependence at xed outer radius R2: ECoul decreases as the nanoshell becomes more conning, contrary to what one would expect from quantum connement eects. We show that this is a consequence of an increase in the average electron-hole distance, giving rise to reduced exciton Coulomb energies in spite of the reduction in the conning nanoshell volume.

Frey, K. [University of Illinois, Chicago; Idrobo Tapia, Juan C [ORNL; Tiago, Murilo L [ORNL; Reboredo, Fernando A [ORNL; Ogut, Serdar [University of Illinois, Chicago

2009-01-01

390

Elementary excitations and avalanches in the Coulomb glass  

NASA Astrophysics Data System (ADS)

We study numerically the statistics of elementary excitations and charge avalanches in the classical Coulomb glass model of localized charges with unscreened Coulomb interaction and disorder. We compute the single-particle density of states with an energy minimization algorithm for systems of up to 1003 sites. The shape of the Coulomb gap is consistent with a power-law with exponent ? simeq 2.4 and marginally consistent with exponential behavior. The results are also compared with a recently proposed self-consistent approach. We then analyze the size distribution of the charge avalanches produced by a small perturbation of the system. We show that the distribution decays as a power law in the limit of large system size, and explain this behavior in terms of the elementary excitations. Similarities and differences with the scale-free avalanches observed in mean-field spin glasses are discussed.

Palassini, Matteo; Goethe, Martin

2012-07-01

391

Coulomb breakup mechanism of neutron drip-line nuclei  

SciTech Connect

The mechanism of the Coulomb breakup reaction of the projectile nuclei with neutron halo structure is investigated by the time-dependent Schroedinger equation in three-dimensional space. The time evolution of the internal wave function between the core nucleus and the halo neutron is calculated in the target Coulomb field treated as the time-dependent external field. Calculations are done for the [sup 11]Be+[sup 208]Pb system for which an experiment has been done recently. The calculated results support the picture of free-particle breakup mechanism: Only the core nucleus is affected by the target Coulomb field, while the halo neutron moves independently. As a result, we obtain large transverse and small longitudinal difference in the relative velocity between the core and the neutron after the breakup. The origin of the longitudinal velocity difference observed experimentally is left unresolved in our approach.

Kido, T. (Graduate School of Science and Technology, Niigata University, Niigata 950-21 (Japan)); Yabana, K.; Suzuki, Y. (Department of Physics, Niigata University, Niigata 950-21 (Japan))

1994-09-01

392

Testing the Predictive Power of Coulomb Stress on Aftershock Sequences  

NASA Astrophysics Data System (ADS)

Empirical and statistical models of clustered seismicity are usually strongly stochastic and perceived to be uninformative in their forecasts, since only marginal distributions are used, such as the Omori-Utsu and Gutenberg-Richter laws. In contrast, so-called physics-based aftershock models, based on seismic rate changes calculated from Coulomb stress changes and rate-and-state friction, make more specific predictions: anisotropic stress shadows and multiplicative rate changes. We test the predictive power of models based on Coulomb stress changes against statistical models, including the popular Short Term Earthquake Probabilities and Epidemic-Type Aftershock Sequences models: We score and compare retrospective forecasts on the aftershock sequences of the 1992 Landers, USA, the 1997 Colfiorito, Italy, and the 2008 Selfoss, Iceland, earthquakes. To quantify predictability, we use likelihood-based metrics that test the consistency of the forecasts with the data, including modified and existing tests used in prospective forecast experiments within the Collaboratory for the Study of Earthquake Predictability (CSEP). Our results indicate that a statistical model performs best. Moreover, two Coulomb model classes seem unable to compete: Models based on deterministic Coulomb stress changes calculated from a given fault-slip model, and those based on fixed receiver faults. One model of Coulomb stress changes does perform well and sometimes outperforms the statistical models, but its predictive information is diluted, because of uncertainties included in the fault-slip model. Our results suggest that models based on Coulomb stress changes need to incorporate stochastic features that represent model and data uncertainty.

Woessner, J.; Lombardi, A.; Werner, M. J.; Marzocchi, W.

2009-12-01

393

Relativistic symmetry of position-dependent mass particles in a Coulomb field including tensor interaction  

NASA Astrophysics Data System (ADS)

The spatially-dependent mass Dirac equation is solved exactly for attractive scalar and repulsive vector Coulomb potentials, including a tensor interaction under the spin and pseudospin symmetric limits. Closed forms of the energy eigenvalue equation and wave functions are obtained for arbitrary spin—orbit quantum number ?. Some numerical results are also given, and the effect of tensor interaction on the bound states is presented. It is shown that tensor interaction removes the degeneracy between two states in the spin doublets. We also investigate the effects of the spatially-dependent mass on the bound states under spin symmetric limit conditions in the absence of tensor interaction.

Eshghi, M.; Hamzavi, M.; M. Ikhdair, S.

2013-03-01

394

Variational solution of the Yang-Mills Schroedinger equation in Coulomb gauge  

SciTech Connect

The Yang-Mills Schroedinger equation is solved in Coulomb gauge for the vacuum by the variational principle using an Ansatz for the wave functional, which is strongly peaked at the Gribov horizon. A coupled set of Schwinger-Dyson equations for the gluon and ghost propagators in the Yang-Mills vacuum as well as for the curvature of gauge orbit space is derived and solved in one-loop approximation. We find an infrared suppressed gluon propagator, an infrared singular ghost propagator, and an almost linearly rising confinement potential.

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

2004-11-15

395

Accuracy of a density-wave theory for Coulomb solids  

NASA Astrophysics Data System (ADS)

The accuracy of a density-wave theory for Coulomb solids is examined in light of ``exact'' Monte Carlo data; a classical one-component plasma (OCP) and a binary ionic mixture (BIM) of carbon and oxygen are studied. For the OCP, the theory reproduces the solid free energy with excellent accuracy in a broad range of the Coulomb coupling parameter covering the crystallization conditions. For the BIM, we find local charge neutrality, which was not taken into account in previous calculations, plays a crucial role in describing the alloying nature; a phase diagram for the mixture is presented.

Iyetomi, Hiroshi; Ichimaru, Setsuo

1992-01-01

396

Nature of Coulomb Shifts of Nuclear Scattering Resonances  

SciTech Connect

Relations determining the shift of energies and widths of scattering resonances are obtained within the method of evolution in the coupling constant. These relations generalize the well-known relations for the shift of levels in a discrete spectrum. The problem of determining the Coulomb shifts of low-energy resonances manifesting themselves in the cross section for the scattering of some light nuclei is solved. Examples that are of importance for nuclear astrophysics and examples of problems that are associated with the production of chemical elements are considered. The character of Coulomb shifts is studied within simple nuclear models. Respective numerical estimates are given, which agree satisfactorily with experimental data.

Takibayev, N.Zh. [Kazakh National Pedagogical University, Almaty (Kazakhstan)

2005-07-01

397

Coulomb excitation of the proton-dripline nucleus Na20  

Microsoft Academic Search

The low-energy structure of the proton dripline nucleus Na20 has been studied using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. A 1.7-MeV\\/nucleon Na20 beam of ~5×106 ions\\/s was Coulomb excited by a 0.5-mg\\/cm2natTi target. Scattered beam and target particles were detected by the BAMBINO segmented Si detector while gamma rays were detected by two TIGRESS HPGe clover detectors

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

2009-01-01

398

Lifetime Measurements and Coulomb Excitation of Light Hg Nuclei  

NASA Astrophysics Data System (ADS)

Two complementary experimental programs have taken place to investigate the origin and evolution of shape coexistence in the light mercury region. Recoil Distance Doppler-shift measurements were performed at the University of Jyväskylä utilizing the Köln plunger device in conjunction with the JUROGAM+RITU+GREAT setup. In addition, Coulomb excitation measurements of 184,186,188Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to I? = 10+ in 182Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.

Petts, A.; Butler, P. A.; Grahn, T.; Blazhev, A.; Bree, N.; Bruyneel, B.; Cederkäll, J.; Clement, E.; Cocolios, T. E.; Dewald, A.; Eberth, J.; Fraile, L.; Fransen, C.; Hornillos, M. B. Gómez; Greenlees, P. T.; Görgen, A.; Guttormsen, M.; Hadynska, K.; Helariutta, K.; Herzberg, R.-D.; Huyse, M.; Jenkins, D. G.; Jolie, J.; Jones, P.; Julin, R.; Juutinen, S.; Ketelhut, S.; Knapen, S.; Kröll, T.; Krücken, R.; Larsen, A. C.; Leino, M.; Ljungvall, J.; Maierbeck, P.; Marley, P. L.; Melon, B.; Napiorkowski, P. J.; Nyman, M.; Page, R. D.; Pakarinen, J.; Pascovici, G.; Patronis, N.; Peura, P. J.; Piselli, E.; Pissulla, Th.; Rahkila, P.; Reiter, P.; Sarén, J.; Scheck, M.; Scholey, C.; Semchenkov, A.; Siem, S.; Stefanescu, I.; Sorri, J.; Uusitalo, J.; van de Walle, J.; van Duppen, P.; Voulot, D.; Wadsworth, R.; Warr, N.; Weisshaar, D.; Wenander, F.; Zielinska, M.

2009-01-01

399

Quantum Kinetics of Coulomb Scattering with Screening in QUASI-2D Semiconductors  

NASA Astrophysics Data System (ADS)

We investigate a microscopic non-Markovian Coulomb quantum kinetic theory of relaxation and dephasing of an electron-hole gas in a GaAs quantum well excited by coherent femtosecond laser pulses. Our theory is based on the full two-time-dependent RPA-screened Coulomb potential which is calculated self-consistently and evolves from a bare potential to the well-known dynamically screened RPA potential for long times. The longitudinal optical phonons also yield an efficient cooling mechanism and are considered by a thermal bath. The calculations are applied to a Four-Wave-Mixing experiment and are shown to reproduce the time-resolved, as well as time-integrated signals. In the case of the time-resolved signal we obtain from our calculations the shift of the echo signal to earlier times as in the experiment. Simplified scattering terms do not yield this feature. Prom the time-integrated signals we obtain the decay time ? at high densities by using the parameters of the GaAs quantum well. The density-dependent decay time ? of the time-integrated signals cannot be associated with a single unique phase relaxation time T2.

Mieck, B.; Haug, H.

2000-04-01

400

Normal product states for fermions and twisted duality for CCR and CAR-type algebras with application to the Yukawa 2 quantum field model  

Microsoft Academic Search

We present sufficient conditions that imply duality for the algebras of local observables in all Abelian sectors of all locally normal, irreducible representations of a field algebra if twisted duality obtains in one of these representations. It is verified that the Yukawa2 model satisfies these conditions, yielding the first proof of duality for the observable algebra in all coherent charge

Stephen J. Summers; Universitfit Osnabrfick

1982-01-01

401

The Coulomb problem on a 3-sphere and Heun polynomials  

SciTech Connect

The paper studies the quantum mechanical Coulomb problem on a 3-sphere. We present a special parametrization of the ellipto-spheroidal coordinate system suitable for the separation of variables. After quantization we get the explicit form of the spectrum and present an algebraic equation for the eigenvalues of the Runge-Lentz vector. We also present the wave functions expressed via Heun polynomials.

Bellucci, Stefano [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy)] [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Yeghikyan, Vahagn [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy) [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Yerevan State University, Alex-Manoogian st. 1, 00025 Yerevan (Armenia)

2013-08-15

402

The structure of small molecules with the Coulomb Explosion method  

SciTech Connect

The content of this paper is divided into two parts: (1) achievements of the last two years in studying molecular ion structure with the aid of the newly developed Coulomb-Explosion (CE) method, and (2) the understanding of the modern CE data in terms of an invariant density of nuclear coordinates of the studied molecule.

Vager, Z.; Kanter, E.P.

1987-01-01

403

LTU Physlet: Coulomb's Law With Multiple Discrete Charges  

NSDL National Science Digital Library

This simple applet shows two fixed charges and a moveable test charge. The total Coulomb force on the test charge is displayed. The user can toggle between the fixed charges having like unequal charges or unlike unequal charges. A brief explanation is provided. This is part of a large collection of Physlet-based (Physics Java Applet) illustrations and tutorials covering introductory physics.

Schneider, Scott

2007-06-13

404

Dislocation waves in a two-dimensional Coulomb lattice  

Microsoft Academic Search

We calculate the properties of dislocation waves in a two-dimensional Coulomb lattice. Hybridization of states with core location at different points in the lattice leads to a substantial lowering of the dislocation energy. At rs=37, this lowering is comparable to the elastic core energy. The mass of the dislocation waves for motion in the direction of the Burgers vector is

K. Esfarjani; S. T. Chui; Xiu Qiu

1992-01-01

405

Limits to Electron Beam Emittance from Stochastic Coulomb Interactions  

SciTech Connect

Dense electron beams can now be generated on an ultrafast timescale using laser driven photo-cathodes and these are used for a range of applications from ultrafast electron defraction to free electron lasers. Here we determine a lower bound to the emittance of an electron beam limited by fundamental stochastic Coulomb interactions.

Coleman-Smith, Christopher; Padmore, Howard A.; Wan, Weishi

2008-08-22

406

Coulomb Interaction in Quantum Dot with a Precessing Magnetic Field  

Microsoft Academic Search

We study electronic transport through a quantum dot (QD) with a precessing magnetic field. By using the Keldysh nonequilibrium Green function method, formulas of local density of states (LDOS) and conductance of QD are derived self-consistently. It shows that the LDOS and conductance have obvious changes with the Coulomb blockade interaction. The intensity and angle of the magnetic field or

Wu Liu-Po; Zhou Shi-Ping; Song Hong-Yan; Shi Yao-Ming

2007-01-01

407

Quantum Calculations of Coulomb Reorientation for Sub-Barrier Fusion  

Microsoft Academic Search

Classical mechanics and time dependent Hartree-Fock (TDHF) calculations of heavy ions collisions are performed to study the rotation of a deformed nucleus in the Coulomb field of its partner. This reorientation is shown to be independent of the charges and relative energy of the partners. It only depends upon the deformations and inertias. TDHF calculations predict an increase by 30%

Cedric Simenel; Philippe Chomaz; G. de France

2004-01-01

408

Ginzburg-Landau Vortices, Coulomb Gases, and Renormalized Energies  

NASA Astrophysics Data System (ADS)

This is a review about a series of results on vortices in the Ginzburg-Landau model of superconductivity on the one hand, and point patterns in Coulomb gases on the other hand, as well as the connections between the two topics.

Serfaty, Sylvia

2014-02-01

409

Coulomb blockade in a coupled nanomechanical electron shuttle.  

PubMed

We demonstrate single electron shuttling through two coupled nanomechanical pendula. The pendula are realized as nanopillars etched out of the semiconductor substrate. Coulomb blockade is found at room temperature, allowing metrological applications. By controlling the mechanical shuttling frequency we are able to validate the different regimes of electron shuttling. PMID:22201451

Kim, Chulki; Prada, Marta; Blick, Robert H

2012-01-24

410

Charge diffusion versus Coulomb repulsion in finite amplitude electroconvection  

Microsoft Academic Search

The influence of charge diffusion on the nonlinear stability criterion and subsequent finite-amplitude electroconvection of an isothermal liquid layer subjected to weak unipolar injection is examined. It is shown that the solution, determined using a two-dimensional flux corrected transport algorithm, is a function of a nondimensional parameter, namely, the ratio of Coulombic repulsion to charge diffusion. Unless the parameter is

A. CASTELLANOST; A. T. Perez; P. Atten

1989-01-01

411

Coulomb repulsion and the electron beam directed energy weapon  

NASA Astrophysics Data System (ADS)

Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era "Star Wars" study of an electron beam directed energy weapon as an orbiting antiballistic missile device. After much analysis, it was considered physically impossible to focus a 1000-amp 1-GeV beam into a 1-cm diameter spot 1000-km from the beam generator. The main reason was that a 1-cm diameter beam would spread to 5-m diameter at 1000-km due to Coulomb repulsion. Since this could not be overcome, the idea was abandoned. But is this true? What if the rays were reversed? That is, start with a 5-m beam converging slightly with the same nonuniform angular and energy distribution as the electrons from the original problem were spreading at 1000-km distance. Could Coulomb repulsion be overcome? Looking at the terms in computational studies, some are reversible while others are not. Based on estimates, the nonreversible terms should be small - of the order of 0.1 mm. If this is true, it is possible to design a practical electron beam directed weapon not limited by Coulomb repulsion.

Retsky, Michael W.

2004-09-01

412

Coulomb repulsion and the electron beam directed energy weapon  

Microsoft Academic Search

Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into small spots at large distances from defining apertures. A classic example is the 1970s era \\

Michael W. Retsky

2004-01-01

413

Can Coulomb repulsion for charged particle beams be overcome?  

Microsoft Academic Search

Mutual repulsion of discrete charged particles or Coulomb repulsion is widely considered to be an ultimate hard limit in charged particle optics. It prevents the ability to finely focus high current beams into a small spots at large distances from the defining apertures. A classic example is the 1970s era \\

Michael W. Retsky

2004-01-01

414

Nuclear binding effects in relativistic Coulomb sum rules  

Microsoft Academic Search

We extend the formulation of relativistic Coulomb sum rules to account for the average effects of nuclear binding on the initial and final states of ejected nucleons. Relativistic interactions are included by using a Dirac representation adapted from a vector-scalar field theory. The scalar field reduces the effective nucleons mass M* and increases the relativistic effects of recoil and Fermi

D. S. Koltun; T. C. Ferrée

1995-01-01

415

Nuclear binding effects in relativistic Coulomb sum rules  

Microsoft Academic Search

We extend the formulation of relativistic Coulomb sum rules to account for the average effects of nuclear binding on the initial and final states of ejected nucleons. Relativistic interactions are included by using a Dirac representation adapted from a vector-scalar field theory. The scalar field reduces the effective nucleons mass {ital M}{sup *} and increases the relativistic effects of recoil

D. S. Koltun; T. C. Ferree

1995-01-01

416

Existence of the thermodynamic limit for disordered quantum Coulomb systems  

NASA Astrophysics Data System (ADS)

Following a recent method introduced by Hainzl, Solovej, and Lewin, we prove the existence of the thermodynamic limit for a system made of quantum electrons, and classical nuclei whose positions and charges are randomly perturbed in an ergodic fashion. All the particles interact through Coulomb forces.

Blanc, Xavier; Lewin, Mathieu

2012-09-01

417

A measurement procedure for viscous and coulomb friction  

Microsoft Academic Search

This paper presents a viscous and coulomb friction measurement procedure for mechanical systems equipped with high-precision velocity sensors. The proposed method exploits the structure of the velocity response predicted by several standard friction models when a force or torque is applied in a ramp fashion. Experimental results show the high accuracy of the proposed measurement procedure

Rafael Kelly; Jesús Llamas; Ricardo Campa

2000-01-01

418

Structure and Madelung Energy of Coulomb Clusters.  

National Technical Information Service (NTIS)

The ground state of the system of charged particles of one species confined by the three dimensional, isotropic, and parabolic potential is investigated by molecular dynamics simulations. It is shown that, with the increase of the system size or the numbe...

C. Totsuji H. Totsuji K. Tsuruta T. Kishimoto

2002-01-01

419

The simulation of the spin ground states of the coulomb clusters in a broad 2D parabolic well  

Microsoft Academic Search

By variational Monte-Carlo method developed Ceperley et al. for the simulation of fermi systems in macroscopic confining potential well we simulate various spin ground states of the coulomb clusters with 2,3 and 4 particles in a broad two-dimensional (2D) parabolic well. In this method quantum state numbers determining the variational wave function are not the numbers of well quantum states

B. Abdullaev; A. D. Kidisyuk; M. M. Musakhanov

2001-01-01

420

Effect of magnetic field on the velocity autocorrelation and the caging of particles in two-dimensional Yukawa liquids.  

PubMed

We investigate the effect of an external magnetic field on the velocity autocorrelation function and the "caging" of the particles in a two-dimensional strongly coupled Yukawa liquid, via numerical simulations. The influence of the coupling strength on the position of the dominant peak in the frequency spectrum of the velocity autocorrelation function confirms the onset of a joint effect of the magnetic field and strong correlations at high coupling. Our molecular dynamics simulations quantify the decorrelation of the particles' surroundings: the magnetic field is found to increase significantly the caging time, which reaches values well beyond the time scale of plasma oscillations. The observation of the increased caging time is in accordance with findings that the magnetic field decreases diffusion in similar systems. PMID:24730953

Dzhumagulova, K N; Masheeva, R U; Ramazanov, T S; Donkó, Z

2014-03-01

421

Parallel shear flow instabilities in strongly coupled Yukawa liquids: A comparison of generalized hydrodynamic model and molecular dynamics results  

SciTech Connect

Using a generalized hydrodynamic (GH) model, the growth rate spectra of Kelvin-Helmholtz (KH) instability has been obtained analytically for a step shear profile in strongly coupled Yukawa liquids. The class of shear flows studied is assumed to be incompressible in nature. The growth rate spectra calculated exhibit viscous damping at high mode numbers, destabilization at stronger coupling, and in the limit {tau}{sub m} (viscoelastic relaxation time){yields}0, reduce to the regular Navier-Stokes growth rate spectra. A direct comparison is made with previous molecular dynamics (MD) simulations [Ashwin J. and R. Ganesh, Phys. Rev. Lett. 104, 215003 (2010)] of KH instability. We find that for a given value of Reynolds number R and coupling parameter 1<{Gamma}<100, the GH and MD growth rates are in a qualitative agreement. The inclusion of the effect of shear heating as an effective coupling parameter {Gamma}{sub e} appears to improve the quantitative comparison as well.

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

2010-10-15

422

Rate/state Coulomb stress transfer model for the CSEP Japan seismicity forecast  

NASA Astrophysics Data System (ADS)

Numerous studies retrospectively found that seismicity rate jumps (drops) by coseismic Coulomb stress increase (decrease). The Collaboratory for the Study of Earthquake Prediction (CSEP) instead provides us an opportunity for prospective testing of the Coulomb hypothesis. Here we adapt our stress transfer model incorporating rate and state dependent friction law to the CSEP Japan seismicity forecast. We demonstrate how to compute the forecast rates of large shocks in 2009 using the large earthquakes during the past 120 years. The time dependent impact of the coseismic stress perturbations explains qualitatively well the occurrence of the recent moderate size shocks. Such ability is partly similar to that of statistical earthquake clustering models. However, our model differs from them as follows: the off-fault aftershock zones can be simulated using finite fault sources; the regional areal patterns of triggered seismicity are modified by the dominant mechanisms of the potential sources; the imparted stresses due to large earthquakes produce stress shadows that lead to a reduction of the forecasted number of earthquakes. Although the model relies on several unknown parameters, it is the first physics based model submitted to the CSEP Japan test center and has the potential to be tuned for short-term earthquake forecasts.

Toda, S.; Enescu, B.

2011-03-01

423

Structural and dynamical aspects of small three-dimensional spherical Coulomb clusters  

Microsoft Academic Search

An analysis of the structural and dynamical properties of small size three-dimensional clusters of classical charged particles confined in a spherical parabolic trap is presented. The ground state and the lowest metastable configurations are identified for Coulomb clusters consisting of N=4 100 particles. The eigenmode frequencies are investigated both for clusters with Coulomb and screened Coulomb interparticle interaction. The breathing

S. W. S. Apolinario; B. Partoens; F. M. Peeters

2007-01-01

424

GENERAL: Temperature Effects of Parabolic Linear Bound Potential and Coulomb Bound Potential Quantum Dot Qubit  

Microsoft Academic Search

On the condition of electric-LO phonon strong coupling in a parabolic quantum dot, we obtain the eigenenergy and the eigenfunctions of the ground state and the first-excited state using the variational method of Pekar type. This system in a quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition state of the ground

Ying-Jie Chen; Jing-Lin Xiao

2009-01-01

425

Properties of Parabolic Linear Bound Potential and Coulomb Bound Potential Quantum Dot Qubit  

Microsoft Academic Search

On the condition of electric-LO phonon strong-coupling in a parabolic quantum dot, we obtain the eigenenergy of the ground-state and the first-excited state, the eigenfunctions of the ground-state and the first- excited state by using variational method of Pekar type. This system in quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition

Zi-Wu Wang; Wei-Ping Li; Ji-Wen Yin; Jing-Lin Xiao

2008-01-01

426

Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions  

SciTech Connect

Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q {approx} 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement.

Cleland, A.N.

1991-04-01

427

Potential model for the bottomonium  

NASA Astrophysics Data System (ADS)

We use a Euclidean propagator obtained from lattice simulations in Landau gauge to arrive at a potential model for the bottomonium. Following this non-relativistic approach, we then find the spectrum of the bottomonium numerically and compare it with the spectrum obtained using a Coulomb plus linear potential.

Serenone, Willian M.; Mendes, Tereza

2013-03-01

428

The Coulomb law and atomic levels in a superstrong B. Talk at the 1st International Conference on New Frontiers in Physics  

NASA Astrophysics Data System (ADS)

The spectrum of atomic levels of hydrogen-like ions originating from the lowest Landau level in an external homogeneous superstrong magnetic field is obtained. The influence of the screening of the Coulomb potential on the values of critical nuclear charges is studied.

Vysotsky, M. I.

2014-04-01

429

Semi-Empirical Approximations for the Coulomb and Bond Integrals in Simple Lcao-Mo Methods. I. Alternant and Non-Alternant Hydrocarbons.  

National Technical Information Service (NTIS)

It is suggested that the Coulomb integral in simple LCAO-MO methods is given by Alpha-r = -(Ir + (Nmax)Es), where Ir is the valence state ionization potential of atom r, Es is the average of the valence state electron-affinities of the nearest neighbors o...

R. Ferreira

1964-01-01

430

Coulomb Suppression of the Stellar Enhancement Factor  

SciTech Connect

It is commonly assumed that reaction measurements for astrophysics should be preferably performed in the direction of a positive Q value to minimize the impact of the stellar enhancement factor, i.e., the difference between the laboratory rate and the actual stellar rate. We show that the stellar effects can be minimized in the charged particle channel, even when the reaction Q value is negative. As a demonstration, the cross section of the astrophysically relevant {sup 85}Rb(p,n){sup 85}Sr reaction has been measured by activation between 2.16{<=}E{sub c.m.}{<=}3.96 MeV and the astrophysical reaction rate for (p, n) as well as (n, p) is directly inferred from the data. The presented arguments are also relevant for other {alpha}- and proton-induced reactions in the p and rp processes. Additionally, our results confirm a previously derived modification of a global optical proton potential.

Kiss, G. G.; Gyuerky, Gy.; Simon, A.; Fueloep, Zs.; Somorjai, E. [Institute of Nuclear Research (ATOMKI), H-4001 Debrecen, POB.51. (Hungary); Rauscher, T. [Department of Physics, University of Basel, CH-4056 Basel (Switzerland)

2008-11-07

431

'Screening' of universal van der Waals Casimir terms by Coulomb gases in a fully finite two-dimensional geometry  

NASA Astrophysics Data System (ADS)

This paper is a continuation of a previous one (Jancovici and Samaj, 2004 J. Stat. Mech. P08006) dealing with classical Casimir phenomena in semi-infinite wall geometries. In that paper, using microscopic Coulomb systems, the long-ranged Casimir force due to thermal fluctuations in conducting walls was shown to be screened by the presence of an electrolyte between the walls into some residual short-ranged force. Here, we aim to extend the study of the screening (cancellation) phenomena to universal Casimir terms appearing in the large-size expansions of the grand potentials for microscopic Coulomb systems confined in fully finite 2D geometries, in particular the disc geometry. Two cases are solved exactly: the high-temperature (Debye-Hückel) limit and the Thirring free-fermion point. Similarities and fundamental differences between fully finite and semi-finite geometries are pointed out.

Jancovici, B.; Samaj, L.

2005-05-01

432

Elastic Scattering and Reaction Cross Section of the 6He+27Al System Close to the Coulomb Barrier  

SciTech Connect

The RIBRAS (Radioactive Ion Beams Brazil) facility recently installed at the Pelletron Laboratory of the University of Sao Paulo consists of two superconducting solenoids used to produce and focalize beams of light radioactive nuclei, as 6He, 7Be,8Li etc. The low energy, light, radioactive beams available are used to study reactions close to the Coulomb barrier. The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier. Reaction cross sections were extracted from the optical model fits, using the Sao Paulo Potential (SPP). The reduced reaction cross sections of 6He on 27Al were compared to reduced reaction cross sections for other projectiles as 6,7Li, 9Be and 16O on 27Al and they are larger than those for stable projectiles by an amount similar to the calculated nuclear break-up cross section for this system.

Lepine-Szily, A.; Benjamim, E. A.; Lichtenthaeler, R.; Guimaraes, V.; Chamon, L. C.; Hussein, M. S.; Alcantara Nunez, J.; Assuncao, M.; Barioni, A.; Camargo, O. Jr.; Denke, R. Z.; Faria, P. N. de; Mendes Junior, D. R.; Pires, K. C. C. [Instituto de Fisica-Universidade de Sao Paulo, C.P.66318, 05389-970 Sao Paulo (Brazil); Gomes, P. R. S. [Instituto de Fisica-Universidade Federal Fluminense, Niteroi, R.J., 24210-340 (Brazil); Arazi, A. [Laboratorio Tandar, Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250 (1429), Buenos Aires (Argentina); Padron, I. [CEADEN, P.O. Box 6122, Havana (Cuba)

2006-08-14

433

Orbital ice: an exact Coulomb phase on the diamond lattice.  

PubMed

We demonstrate the existence of an orbital Coulomb phase as the exact ground state of a p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar correlations and a gauge structure resulting from local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constraints are a direct consequence of minimizing the energy of each individual tetrahedron. On the contrary, the orbital ice rules are emergent phenomena resulting from the quantum orbital dynamics. We show that the orbital ice model exhibits an emergent geometrical frustration by mapping the degenerate quantum orbital ground states to the spin-ice states obeying the 2-in-2-out constraints on the pyrochlore lattice. We also discuss possible realization of the orbital ice model in optical lattices with p-band fermionic cold atoms. PMID:22304060

Chern, Gia-Wei; Wu, Congjun

2011-12-01

434

``Perfect'' Coulomb Drag in a Bilayer Quantum Hall System  

NASA Astrophysics Data System (ADS)

We report Coulomb drag measurements in Corbino geometry which reveal that equal but oppositely directed electrical currents can freely propagate across the insulating bulk of the bilayer quantized Hall state at ?T=1 even when the two 2D layers are electrically isolated and interlayer tunneling has been heavily suppressed by an in-plane magnetic field. This effect, which we dub ``perfect'' Coulomb drag, reflects the transport of charge neutral excitons across the bulk of the 2D system. The equal magnitude of the drive and drag currents is lost at high current and when either the temperature or effective separation between the two 2D layers is increased. In each of these cases, ordinary quasiparticle charge transport across the annulus has grown to dominate over exciton transport.

Nandi, D.; Finck, A. D. K.; Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

2012-02-01

435

Coulomb effects in low-energy nuclear fragmentation  

NASA Astrophysics Data System (ADS)

Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

1993-08-01

436

Revision of the Coulomb logarithm in the ideal plasma  

NASA Astrophysics Data System (ADS)

The standard picture of the Coulomb logarithm in the ideal plasma is controversial, the arguments for the lower cut off need revision. The two cases of far subthermal and of far superthermal electron drift motions are accessible to a rigorous analytical treatment. We show that the lower cut off bmin is a function of symmetry and shape of the shielding cloud, it is not universal. In the subthermal case, shielding is spherical and bmin is to be identified with the de Broglie wavelength; at superthermal drift the shielding cloud exhibits cylindrical (axial) symmetry and bmin is the classical parameter of perpendicular deflection. In both situations, the cut offs are determined by the electron-ion encounters at large collision parameters. This is in net contrast to the governing standard interpretation that attributes bmin to the Coulomb singularity at vanishing collision parameters b and, consequently, assigns it universal validity. The origin of the contradictions in the traditional picture is analyzed.

Mulser, P.; Alber, G.; Murakami, M.

2014-04-01

437

Current through a cluster: STM and Coulomb blockade  

NASA Astrophysics Data System (ADS)

The resonant tunneling (Anderson) model is employed to investigate the fundamental physics of scanning tunneling microscopy (STM) and spectroscopy (STS). A stationary current through a cluster of orbitals between two electrodes with finite bias voltage is considered. We point out problems concerning a possible pathway of obtaining the current through surface-localized states and the fact that fruitful information can possibly be obtained on the pathway as well as on the effect of inelastic scattering. Also considered is the effect of Coulomb interaction on the current through such localized states. The study can be regarded as that of the Coulomb or spin blockade phenomenon from a small system-size limit, or practically possible using the STM tip for atom manipulation.

Makoshi, Kenji; Shima, Nobuyuki; Mii, Takashi

1997-10-01

438

Coulomb Effect in Nucleon-Deuteron Elastic Scattering  

NASA Astrophysics Data System (ADS)

We have applied the quark-model nucleon-nucleon interaction fss2 to the nucleon-deuteron scattering. The screened cutoff Coulomb force in the momentum space has been incorporated to the proton-deuteron scattering by extending the matching condition, which is proposed by Vincent and Phatak for the sharply cutoff Coulomb problem. The model fss2 can reproduce the overall characteristics of the experimental data. It is found that fss2 partially incorporates the attractive feature, which accords with the good reproduction of the triton binding energy and neutron-deuteron doublet scattering length. This attractive feature is due to the off-shell effect related to the quark-model description of the short-range repulsion of the two-nucleon force.

Fukukawa, K.; Fujiwara, Y.

2013-08-01

439

Coulomb effects in low-energy nuclear fragmentation  

NASA Technical Reports Server (NTRS)

Early versions of the Langley nuclear fragmentation code NUCFRAG (and a publicly released version called HZEFRG1) assumed straight-line trajectories throughout the interaction. As a consequence, NUCFRAG and HZEFRG1 give unrealistic cross sections for large mass removal from the projectile and target at low energies. A correction for the distortion of the trajectory by the nuclear Coulomb fields is used to derive fragmentation cross sections. A simple energy-loss term is applied to estimate the energy downshifts that greatly alter the Coulomb trajectory at low energy. The results, which are far more realistic than prior versions of the code, should provide the data base for future transport calculations. The systematic behavior of charge-removal cross sections compares favorably with results from low-energy experiments.

Wilson, John W.; Chun, Sang Y.; Badavi, Francis F.; John, Sarah

1993-01-01

440

Silicon-based Coulomb blockade thermometer with Schottky barriers  

NASA Astrophysics Data System (ADS)

A hybrid Coulomb blockade thermometer (CBT) in form of an array of intermittent aluminum and silicon islands connected in series via tunnel junctions was fabricated on a thin silicon-on-insulator (SOI) film. Tunnel barriers in the micrometer size junctions were formed by metal-semiconductor Schottky contacts between aluminium electrodes and heavily doped silicon. Differential conductance through the array vs. bias voltage was found to exhibit characteristic features of competing thermal and charging effects enabling absolute temperature measurements over the range of ˜65 to ˜500 mK. The CBT performance implying the primary nature of the thermometer demonstrated for rather trivial architecture attempted in this work paves a route for introduction of Coulomb blockade thermometry into well-developed contemporary SOI technology.

Tuboltsev, V.; Savin, A.; Rogozin, V. D.; Räisänen, J.

2014-04-01

441

Is the ground state of Yang-Mills theory Coulombic?  

SciTech Connect

We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-Abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.

Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Lutz, W. [School of Mathematics and Statistics, University of Plymouth, Plymouth, PL4 8AA (United Kingdom); Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2008-08-01

442

Regular multicharged transient soft matter in Coulomb explosion of heteroclusters  

PubMed Central

Nanointerfaces of mobile, thin spherical shells of light ions that expand on the femtosecond time scale, can be produced by Coulomb explosion of extremely ionized molecular heteroclusters consisting of light and heavy ions, e.g., (D+Iq+)n (q = 7-35), which are generated in ultraintense laser fields (intensity, I, = 1016 to 1020 W·cm-2). Modeling, together with molecular dynamics simulations, reveals the expansion of 2D monolayers with high energies and narrow energy distributions [e.g., Eav ? 23 keV and ?E/Eav = 0.16 for D+ from (D+I25+)2171] arising from kinematic run-over effects. The expanding regular, monoionic, spherical nanointerfaces manifest the attainment of transient self-organization in complex systems driven by repulsive Coulomb interactions.

Last, Isidore; Jortner, Joshua

2005-01-01

443

Statistical theory of rarified gases in the coulomb model of substance: Adiabatic approximation and initial atoms  

NASA Astrophysics Data System (ADS)

In the framework of the adiabatic approximation for a subsystem of nuclei with the average distance between them significantly exceeding the dimensions of the initial atom, we consider a nonrelativistic Coulomb system consisting of electrons and nuclei of one type for the temperature range where we can restrict ourself to using the ground state to describe the electron subsystem. We show that the equilibrium properties of such a system are equivalent to the thermodynamic properties of the one-component system of initial atoms interacting between themselves via a short-range potential that is the effective potential of the nucleus-nucleus interaction. In the framework of the applicability of Boltzmann statistics, we present quantum group expansions for the thermodynamic properties of a chemically reacting rarified gas that correspond to the method of initial atoms.

Bobrov, V. B.

2014-03-01

444

Thermoelectric current and Coulomb-blockade plateaus in a quantum dot  

NASA Astrophysics Data System (ADS)

A Generalized Master Equation (GME) is used to study the thermoelectric currents through a quantum dot in both the transient and steady-state regime. The two semi-infinite leads are kept at the same chemical potential but at different temperatures to produce a thermoelectric current which has a varying sign depending on the chemical potential. The Coulomb interaction between the electrons in the sample is included via the exact diagonalization method. We observe a saw-teeth like profile of the current alternating with plateaus of almost zero current. Our calculations go beyond the linear response with respect to the temperature gradient, but are compatible with known results for the thermopower in the linear response regime.

Torfason, Kristinn; Manolescu, Andrei; Erlingsson, Sigurdur I.; Gudmundsson, Vidar

2013-09-01

445

Control of the conformations of ion Coulomb crystals in a Penning trap.  

PubMed

Laser-cooled atomic ions form ordered structures in radiofrequency ion traps and in Penning traps. Here we demonstrate in a Penning trap the creation and manipulation of a wide variety of ion Coulomb crystals formed from small numbers of ions. The configuration can be changed from a linear string, through intermediate geometries, to a planar structure. The transition from a linear string to a zigzag geometry is observed for the first time in a Penning trap. The conformations of the crystals are set by the applied trap potential and the laser parameters, and agree with simulations. These simulations indicate that the rotation frequency of a small crystal is mainly determined by the laser parameters, independent of the number of ions and the axial confinement strength. This system has potential applications for quantum simulation, quantum information processing and tests of fundamental physics models from quantum field theory to cosmology. PMID:24096901

Mavadia, Sandeep; Goodwin, Joseph F; Stutter, Graham; Bharadia, Shailen; Crick, Daniel R; Segal, Daniel M; Thompson, Richard C

2013-01-01

446

Topological defect motifs in two-dimensional Coulomb clusters  

Microsoft Academic Search

We study the distribution of topological defects in two-dimensional Coulomb clusters with parabolic lateral confinement. The minima hopping algorithm based on molecular dynamics is used to efficiently locate the ground- and low-energy metastable states, and their structure is analysed by means of the Delaunay triangulation. The size, structure and distribution of geometry-induced lattice imperfections strongly depends on the system size

A. Radzvilavicius; E. Anisimovas

2011-01-01

447

On the coulomb scattering of ?-mesons by light nuclei  

Microsoft Academic Search

Summary  Using a «one particle model» of the nucleus, the coulomb scattering of ?-mesons by light nuclei is treated in Born approximation.\\u000a One has to distinguish a coherent scattering and an incoherent scattering as in the case of X-rays or slow electrons scattered\\u000a by atoms. Using a parabolic well model one can derive, in an elementary way, an expression of the

E. Amaldi; G. Fidecaro; F. Mariani

1950-01-01

448

Structure of spherical three-dimensional Coulomb crystals.  

PubMed

An analysis of the structural properties of three-dimensional Coulomb clusters confined in a spherical parabolic trap is presented. Based on extensive high-accuracy computer simulations the shell configurations and energies for particle numbers in the range 60 < or = N < or = 160 are reported. Further, the intrashell symmetry and the lowest metastable configurations are analyzed for small clusters and a different type of excited state that does not involve a change of shell configuration is identified. PMID:15903790

Ludwig, P; Kosse, S; Bonitz, M

2005-04-01

449

Nonrelativistic Coulomb Green’s function in parabolic coordinates  

Microsoft Academic Search

The nonrelativistic Coulomb Green’s function G(+)(r1,r2,k) is evaluated by explicit summation over discrete and continuum eigenstates in parabolic coordinates. This completes the derivation of Meixner, who was able to obtain only the r1=0 and r2?? limiting forms of the Green’s function. Further progress is made possible by an integral representation for a product of two Whittaker functions given by Buchholz.

S. M. Blinder

1981-01-01

450

Structure of spherical three-dimensional Coulomb crystals  

SciTech Connect

An analysis of the structural properties of three-dimensional Coulomb clusters confined in a spherical parabolic trap is presented. Based on extensive high-accuracy computer simulations the shell configurations and energies for particle numbers in the range 60{<=}N{<=}160 are reported. Further, the intrashell symmetry and the lowest metastable configurations are analyzed for small clusters and a different type of excited state that does not involve a change of shell configuration is identified.

Ludwig, P. [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstrasse 15, 24098 Kiel (Germany); Fachbereich Physik, Universitaet Rostock, l8051 Rostock (Germany); Kosse, S. [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstrasse 15, 24098 Kiel (Germany); Sektion Physik, Ernst-Moritz-Arndt Universitaet Greifswald, Domstrasse 10a, l7487 Greifswald (Germany); Bonitz, M. [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet zu Kiel, Leibnizstrasse 15, 24098 Kiel (Germany)

2005-04-01

451

Fusion cross section at sub-Coulomb energies  

Microsoft Academic Search

The effective barrier at low energies is approximated by a Coulomb and parabolic barriers. A simple closed formula is obtained for the total reaction cross section which is the natural extension of Wong's results into the low energy domain. Theoretical predictions of averaged energy behaviour agree fairly well with various experimental results. The relation??0?p(2kh2Z1Z2e2\\/µ)1\\/2R0-3\\/2 between the curvature and the extremum

Y. Avishai

1978-01-01

452

Structure of spherical three-dimensional Coulomb crystals  

Microsoft Academic Search

An analysis of the structural properties of three-dimensional Coulomb clusters confined in a spherical parabolic trap is presented. Based on extensive high-accuracy computer simulations the shell configurations and energies for particle numbers in the range 60<=N<=160 are reported. Further, the intrashell symmetry and the lowest metastable configurations are analyzed for small clusters and a different type of excited state that

P. Ludwig; S. Kosse; M. Bonitz

2005-01-01

453

Sympathetic cooling in a multi-isotope Sr+ Coulomb crystal  

Microsoft Academic Search

This paper reports on trapping and laser-cooling of singly-ionized strontium ions in a linear Paul trap. We demonstrate loading of large ion clouds containing as much as 106 ions and laser cooling down to the Coulomb crystal transition. We observe the spatial segregation of the different Sr+ isotopes due to the mass-dependent Paul trap stiffness. Sympathetic cooling of the different

S. Removille; Q. Glorieux; T. Coudreau; L. Guidoni; J.-P. Likforman; S. Guibal

2010-01-01

454

Reactions of halo nuclei at energies around the Coulomb barrier  

NASA Astrophysics Data System (ADS)

Along the last few decades a large number of exotic nuclei have become available at low energies in a number of radioactive beam facilities. Close to the drip lines, the loosely bound valence nucleons and their extended wave functions produce new phenomena, like exotic cluster structures, pigmy dipole resonances and the formation of skins and haloes. In this paper we review present data on the scattering of 6He on heavy targets in a range of energies around the Coulomb barrier.

Martel, I.; Aguilera, E. F.; Acosta, L.; Sánchez-Benítez, A. M.; Wolski, R.

2012-02-01

455

Effect of Coulomb Collisions on Low Gas Pressure Plasmas  

NASA Astrophysics Data System (ADS)

A recent trend in material processing plasmas is the use of a low gas pressure and high plasma density. In such plasmas, Coulomb collisions among charged particles has been considered to have a significant effect on plasma structure. By use of Bobylev and Nanbu's theory [Phy. Rev. E, 61(2000), 4576], this effect on argon plasmas and oxygen plasmas generated by a capacitive discharge is examined. It is found that the effect is appreciable only for oxygen plasmas.

Nanbu, K.; Furubayashi, T.

2006-05-01

456

Equivalence of dipole correction and Coulomb cutoff techniques in supercell calculations  

NASA Astrophysics Data System (ADS)

In ab initio calculations of surfaces or nonperiodic systems, one frequently relies on the supercell approximation, where the periodic replicas of the system are separated by enough empty space to avoid spurious interactions between the successive images. However, a vacuum separation is not sufficient to screen the dipolar interaction that appears in asymmetrically charged or polar systems. The dipole correction and Coulomb cutoff methods are often used to eliminate such interactions between the periodic replicas. In this work, these methods are compared under the same conditions in the framework of plane-wave based density-functional theory. The dipole correction method is shown to be equivalent to the rigorous Coulomb cutoff formalism in the calculations of total energy, force, charge density, and self-consistent potential. We demonstrate that the band structures obtained by these methods coincide for the localized bound states and that the corrections have essentially no influence on the occupied energy bands, only substantially affecting the unoccupied bands. By comparing the results of the two methods, the localized bound states of interest can be easily distinguished from the highly delocalized unoccupied states using a relatively small supercell. This comparison offers substantial savings in the computational time when ascertaining convergence with supercell size. The accuracy of the dipole correction method is also confirmed by comparing the results for a model ferroelectric BaTiO3 slab with a Berry-phase calculation of polarization for the bulk system.

Yu, Liping; Ranjan, V.; Lu, W.; Bernholc, J.; Nardelli, M. Buongiorno

2008-06-01