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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

NASA Astrophysics Data System (ADS)

The Dirac equation for the combined Mobius square and inversely quadratic Yukawa potentials including a Coulomb-like interaction term has been investigated in the presence of spin and pseudospin symmetries with arbitrary spin-orbit quantum number ? .We have obtained the explicit energy eigenvalues and the corresponding eigenfunctions by the framework of Nikiforov-Uvarov method.

Ikot, Akpan N.; Maghsoodi, Elham; Zarrinkamar, Saber; Hassanabadi, Hassan

2013-11-01

3

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

4

In this paper, we present the Dirac equation for the Mobius-square-Yukawa potentials including the tensor interaction term within the framework of pseudospin and spin symmetry limit with arbitrary spin-orbit quantum number . We obtained the energy eigenvalues and the corresponding wave functions using the supersymmetry method. The limiting cases of this potential model reduce to the Deng-Fan, Yukawa and Coulomb potentials, respectively

Akpan N. Ikot; E. Maghsoodi; Akaninyene D. Antia; S. Zarrinkamar; H. Hassanabadi

2012-10-30

5

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

6

Using the Screened Coulomb Potential to Illustrate the Variational Method

ERIC Educational Resources Information Center

The screened Coulomb potential, or Yukawa potential, is used to illustrate the application of the single and linear variational methods. The trial variational functions are expressed in terms of Slater-type functions, for which the integrals needed to carry out the variational calculations are easily evaluated in closed form. The variational…

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2012-01-01

7

Yukawa particles in a confining potential

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.

Girotto, Matheus, E-mail: matheus.girotto@ufrgs.br; Levin, Yan, E-mail: levin@if.ufrgs.br [Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil); Santos, Alexandre P. dos, E-mail: alexandreps@ufcspa.edu.br [Departamento de Educação e Informação em Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, 90050-170, Porto Alegre, RS (Brazil); Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, Santa Catarina (Brazil); Colla, Thiago, E-mail: thiago.colla@ufrgs.br [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna (Austria)

2014-07-07

8

Low-temperature structures of Yukawa particles in systems with cylindrical symmetry are analyzed by numerical simulations. Particles are organized into well-defined thin concentric shells forming triangular lattices with defects on each shell and structural parameters are expressed by simple interpolation formulas including the limiting case of Coulomb particles. In outer shells, the local structure can be regarded as three-dimensional closest packing as in the case of the background of uniform spheres. These formulas can be directly compared with fine particle experiments in long cylindrical chambers under microgravity or colloidal suspensions in cylinders and may be useful as a basis of structural analyses in cylindrical systems. PMID:21867249

Totsuji, Hiroo; Totsuji, Chieko

2011-07-01

9

We approximately solve the Dirac equation for the inversely quadratic Yukawa (IQY) potential including a Coulomb-like tensor potential with arbitrary spin-orbit coupling quantum number . In the framework of the spin and pseudospin (pspin) symmetry, we obtain the energy eigenvalue equation and the corresponding eigenfunctions in closed form by using the Nikiforov-Uvarov method. The numerical results show that the Coulomb-like tensor interaction removes degeneracies between spin and pspin state doublets.

Majid Hamzavi; Sameer M. Ikhdair; B. I. Ita

2012-03-30

10

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

11

OBSERVATIONAL EVIDENCE FOR DARK MATTER INTERACTING THROUGH A YUKAWA POTENTIAL

Recent observations in galaxies and clusters indicate that dark matter density profiles exhibit core-like structures which contradict the numerical simulation results of collisionless cold dark matter (CDM). On the other hand, it has been shown that CDM particles interacting through a Yukawa potential could naturally explain the cores in dwarf galaxies. In this Letter, I use the Yukawa potential interacting dark matter model to derive two simple scaling relations on the galactic and cluster scales, respectively, which give excellent agreements with observations. Also, in our model, the masses of the force carrier and dark matter particle can be constrained by the observational data.

Chan, M. H., E-mail: mhchan@phy.cuhk.edu.hk [Department of Physics and Institute of Theoretical Physics, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (Hong Kong)

2013-05-20

12

Accurate momentum transfer cross section for the attractive Yukawa potential

Accurate expression for the momentum transfer cross section for the attractive Yukawa potential is proposed. This simple analytic expression agrees with the numerical results better than to within ±2% in the regime relevant for ion-particle collisions in complex (dusty) plasmas.

Khrapak, S. A., E-mail: Sergey.Khrapak@dlr.de [Forschungsgruppe Komplexe Plasmen, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen (Germany)

2014-04-15

13

Stationary solution of NLFP with coulombic potential

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

14

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

15

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

Huang, Jingfang; Jia, Jun; Zhang, Bo

2009-11-01

16

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

17

Structural arrest transitions in fluids described by two Yukawa potentials.

We study a model colloidal system where particles interact via short-range attractive and long-range repulsive Yukawa potentials. Using the structure factor calculated from the mean-spherical approximation as the input, the kinetic phase diagrams as functions of the attraction depth and the volume fraction are obtained by calculating the Debye-Waller factors in the framework of the mode-coupling theory for three different heights of the repulsive barrier. The glass-glass reentrance phenomenon in the attractive colloidal case is also observed in the presence of the long-range repulsive barrier, which results in the lower and upper glass regimes. Competition between the short-range attraction and the long-range repulsion gives rise to new regimes associated with clusters such as "static cluster glass" and "dynamic cluster glass," which appear in the lower glass regime. Along the liquid-glass transition line between the liquid regime and the lower glass regime, crossover points separating different glass states are identified. PMID:15600578

Wu, Jianlan; Liu, Yun; Chen, Wei-Ren; Cao, Jianshu; Chen, Sow-Hsin

2004-11-01

18

Auxiliary basis sets to approximate Coulomb potentials

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

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

1995-01-01

19

Positron scattering from hydrogen atom with screened Coulomb potentials

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 [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal, India and Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Nayek, Sujay [Department of Mathematics, Burdwan University, Golapbag, Burdwan 713 104, West Bengal (India); Kamali, M. Z. M. [Centre for Foundation Studies in Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ratnavelu, K. [Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2014-03-05

20

For Abelian gauge theory a properly relativistic gauge is developed by supplementing the Lorentz condition with causal determination of the time component of the four-vector potential by retarded Coulomb transformation of the charge density. This causal Lorentz gauge agrees with the Coulomb gauge for static charge densities, but allows the four-vector potential to have a longitudinal component that is determined by the time derivative of the four-vector potential's time component. Just as in Coulomb gauge, the two transverse components of the four-vector potential are its sole dynamical part. The four-vector potential in this gauge covariantly separates into a dynamical transverse four-vector potential and a nondynamical timelike/longitudinal four-vector potential, where each of these two satisfies the Lorentz condition. In fact, analogous partition of the conserved four-current shows each to satisfy a Lorentz-condition Maxwell equation system with its own conserved four-current. Because of this complete separation, either of these four-vector potentials can be tinkered with without affecting its counterpart. Since it satisfies the Lorentz condition, the nondynamical four-vector potential times a constant with dimension of inverse length squared is itself a conserved four-current, and so can be fed back into its own source current, which transforms its time component into an extended Yukawa, with both exponentially decaying and exponentially growing components. The latter might be the mechanism of quark-gluon confinement: in non-Abelian color gauge theory the Yukawa mixture ratio ought to be tied to color, with palpable consequences for "colorful" hot quark-gluon plasmas.

Steven Kenneth Kauffmann

2010-05-06

21

Path integral solution for the Coulomb potential plus sector

NASA Astrophysics Data System (ADS)

The propagator of a particle moving inside a sector and subjected to the action of the Coulomb potential is derived in the Feynman integral formalism. For particular values of the opening angle ? of the sector, ? = ? and ? = 2 ?, it is shown that the propagator depends on a kernel which collapses into an algebraic sum of free terms over the image set.

Chetouani, L.; Chouchaoui, A.; Hammann, T. F.

1991-12-01

22

The Coulomb correction term in proton absorbing optical potentials

NASA Astrophysics Data System (ADS)

The results of phenomenological analyses of nucleon elastic scattering by 40Ca are analyzed, and the Coulomb correction term of the absorbing part of the optical model potential is empirically extracted. The results show general agreement with the theoretical calculations of Jeukenne, Lejeune and Mahaux.

Rapaport, J.

1980-05-01

23

Serber symmetry, large N{sub c}, and Yukawa-like one-boson exchange potentials

The Serber force has relative orbital parity symmetry and requires vanishing NN interactions in partial waves with odd angular momentum. We illustrate how this property is well fulfilled for spin triplet states with odd angular momentum and violated for odd singlet states for realistic potentials but fails for chiral potentials. The analysis is carried out in terms of partial wave sum rules for NN phase shifts, r-space potentials at long distances, and V{sub lowk} potentials. We analyze how Serber symmetry can be accommodated within a large-N{sub c} perspective when interpreted as a long-distance symmetry. A prerequisite for this is the numerical similarity of the scalar and vector meson resonance masses. The conditions under which the resonance exchange potential can be approximated by a Yukawa form are also discussed. Although these masses arise as poles on the second Riemann in {pi}{pi} scattering, we find that within the large-N{sub c} expansion the corresponding Yukawa masses correspond instead to a well-defined large-N{sub c} approximation to the pole that cannot be distinguished from their location as Breit-Wigner resonances.

Calle Cordon, A.; Arriola, E. Ruiz [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)

2009-07-15

24

Macroscopic Screening of Coulomb Potentials From UV/IR-Mixing

We compute the static potential in a non-commutative theory including a term due to UV/IR-mixing. As a result, the potential decays exponentially fast with distance rather than like a power law Coulomb type potential due to the exchange of massless particles. This shows that when quantum effects are taken into account the introduction of non-commutativity not only modifies physics at short distances but has dramatic macroscopic consequences as well. As a result, we give a lower bound on the scale of non-commutativity (if present at all) to be compatible with observations.

Robert C. Helling; Jiangyang You

2008-02-08

25

An infinite family of superintegrable deformations of the Coulomb potential

We introduce a new family of Hamiltonians with a deformed Kepler- Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wave functions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wave functions and give the transformed integrals explicitly for the classical system.

S. Post; P. Winternitz

2010-05-11

26

Heavy quarks, gluons and the confinement potential in Coulomb gauge

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

27

NASA Astrophysics Data System (ADS)

Jancovici derived the exact r 2 term in the expansion of the screening potential of the one-component plasma (OCP) around r = 0, which led to much improved analysis of the simulation data, but the correspondingly important term has never been calculated for electron-screened plasmas. The Onsager molecule approach provides the strong-coupling-limit result for the OCP screening potentials, features the exact Jancovici r 2 term, and gives a comprehensive physical picture of the structure of strongly coupled plasmas. It is used here to derive the Strong-coupling screening potentials of electron-screened plasmas represented by the Yukawa potentials and, in particular, the corresponding Jancovici r 2 term.

Rosenfeld, Yaakov; Chabrier, Gilles

1997-10-01

28

Jancovici derived the exact r{sup 2} term in the expansion of the screening potential of the one-component plasma (OCP) around r = 0, which led to much improved analysis of the simulation data, but the correspondingly important term has never been calculated for electron-screened plasmas. The Onsager molecule approach provides the strong-coupling-limit result for the OCP screening potentials, features the exact Jancovici r{sup 2} term, and gives a comprehensive physical picture of the structure of strongly coupled plasmas. It is used here to derive the Strong-coupling screening potentials of electron-screened plasmas represented by the Yukawa potentials and, in particular, the corresponding Jancovici r{sup 2} term.

Rosenfeld, Y.; Chabrier, G. [Ecole Normale Superieure de Lyon (France)

1997-10-01

29

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

S. L. Yakovlev; V. A. Gradusov

2012-06-25

30

Exact wavefunctions for a time-dependent Coulomb potential

NASA Astrophysics Data System (ADS)

The one-dimensional Schrödinger equation associated with a time-dependent Coulomb potential is studied. The invariant operator method (Lewis and Riesenfeld) and unitary transformation approach are employed to derive quantum solutions of the system. We obtain an ordinary second-order differential equation whose analytical exact solution has been unknown. It is confirmed that the form of this equation is similar to the radial Schrödinger equation for the hydrogen atom in a (arbitrary) strong magnetic field. The qualitative properties for the eigenstates spectrum are described separately for the different values of the parameter ?0 appearing in the x2 term, x being the position, i.e., ?0 > 0, ?0 < 0 and ?0 = 0. For the ?0 = 0 case, the eigenvalue equation of invariant operator reduces to a solvable form and, consequently, we have provided exact eigenstates of the time-dependent Hamiltonian system.

Menouar, S.; Maamache, M.; Saâdi, Y.; Choi, J. R.

2008-05-01

31

Screened Coulomb potentials for astrophysical nuclear fusion reactions

The electron-screening acceleration of laboratory fusion reactions at astrophysical energies is an unsolved problem of great importance to astrophysics. That effect is modeled here by considering the fusion of hydrogen-like atoms whose electron probability density is used in Poisson's equation in order to derive the corresponding screened Coulomb potential energy. That way atomic excitations and deformations of the fusing atoms can be taken into account. Those potentials are then treated semiclassically in order to obtain the screening (accelerating) factor of the reaction. By means of the proposed model the effect of a superstrong magnetic field on laboratory Hydrogen fusion reactions is investigated here for the first time showing that, despite the considerable increase in the cross section of the $% dd$ reaction, the $pp$ reaction is still too slow to justify experimentation. The proposed model is finally applied on the $H^{2}(d,p) H^{3}$ fusion reaction describing satisfactorily the experimental data although some ambiguity remains regarding the molecular nature of the deuteron target. Notably, the present method gives a sufficiently high screening energy for Hydrogen fusion reactions so that the take-away energy of the spectator nucleus can also be taken into account.

Theodore E. Liolios

2000-09-04

32

Hidden-sector correction to Coulomb potential through the photonic portal

We show that in the model of hidden sector of the Universe, interacting with the Standard-Model sector through the photonic portal, the Standard-Model Coulomb potential gets a tiny hidden-sector additive correction that might turn out to be either exciting or fatal for the verification of this model.

Wojciech Krolikowski

2011-01-03

33

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

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

34

Wheeler-DeWitt Equation with a Screened-Coulomb Dilation Potential

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

35

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

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

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

2008-08-15

36

Proton radioactivity with a Yukawa effective interaction

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.

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

2011-04-26

37

Screened Coulomb potential in a flowing magnetized plasma

NASA Astrophysics Data System (ADS)

The electrostatic potential of a moving dust grain in a complex plasma with magnetized ions is computed using linear response theory, thereby extending our previous work for unmagnetized plasmas (Ludwig et al 2012 New J. Phys. 14 053016). In addition to the magnetic field, our approach accounts for a finite ion temperature as well as ion-neutral collisions. Our recently introduced code Kielstream is used for an efficient calculation of the dust potential. Increasing the magnetization of the ions, we find that the shape of the potential crucially depends on the Mach number M. In the regime of subsonic ion flow (M < 1), a strong magnetization gives rise to a potential distribution that is qualitatively different from the unmagnetized limit, while for M > 1 the magnetic field effectively suppresses the plasma wakefield.

Joost, J.-P.; Ludwig, P.; Kählert, H.; Arran, C.; Bonitz, M.

2015-02-01

38

Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy Available online 25 November 2011 Keywords: Clusters Interaction potentials Range of interactions Topography for (KCl)n systems, we study the effects of the range of the Coulombic interactions on the structures

Berry, R. Stephen

39

Screened Coulomb potential in a flowing magnetized plasma

The electrostatic potential of a moving dust grain in a complex plasma with magnetized ions is computed using linear response theory, thereby extending our previous work for unmagnetized plasmas [P. Ludwig et al., New J. Phys. 14, 053016 (2012)]. In addition to the magnetic field, our approach accounts for a finite ion temperature as well as ion-neutral collisions. Our recently introduced code \\texttt{Kielstream} is used for an efficient calculation of the dust potential. Increasing the magnetization of the ions, we find that the shape of the potential crucially depends on the Mach number $M$. In the regime of subsonic ion flow ($M1$ the magnetic field effectively suppresses the plasma wakefield.

Joost, Jan-Philip; Kählert, Hanno; Arran, Christopher; Bonitz, Michael

2014-01-01

40

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

41

Quantum Monte Carlo Method for Attractive Coulomb Potentials

Starting from an exact lower bound on the imaginary-time propagator, we present a Path-Integral Quantum Monte Carlo method that can handle singular attractive potentials. We illustrate the basic ideas of this Quantum Monte Carlo algorithm by simulating the ground state of hydrogen and helium.

J. S. Kole; H. De Raedt

2001-02-06

42

Virial theorem and Gibbs thermodynamic potential for Coulomb systems

Using the grand canonical ensemble and the virial theorem, we show that the Gibbs thermodynamic potential of the non-relativistic system of charged particles is uniquely defined by single-particle Green functions of electrons and nuclei. This result is valid beyond the perturbation theory with respect to the interparticle interaction.

Bobrov, V. B., E-mail: vic5907@mail.ru, E-mail: satron@mail.ru [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya St. 13, Bd. 2, Moscow 125412 (Russian Federation); National Research University “MPEI,” Krasnokazarmennaya str. 14, Moscow 111250 (Russian Federation); Trigger, S. A., E-mail: vic5907@mail.ru, E-mail: satron@mail.ru [Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya St. 13, Bd. 2, Moscow 125412 (Russian Federation); Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, Berlin D-12489 (Germany)

2014-10-15

43

Virial theorem and Gibbs thermodynamic potential for Coulomb systems

NASA Astrophysics Data System (ADS)

Using the grand canonical ensemble and the virial theorem, we show that the Gibbs thermodynamic potential of the non-relativistic system of charged particles is uniquely defined by single-particle Green functions of electrons and nuclei. This result is valid beyond the perturbation theory with respect to the interparticle interaction.

Bobrov, V. B.; Trigger, S. A.

2014-10-01

44

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

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

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

2010-04-26

45

Dependence of Coulomb Sum Rule on the Short Range Correlation by Using Av18 Potential

NASA Astrophysics Data System (ADS)

The Coulomb sum rule (CSR) and structure factor are calculated for inelastic electron scattering from nuclear matter at zero and finite temperature in the nonrelativistic limit. The effect of short-range correlation (SRC) is presented by using lowest order constrained variational (LOCV) method and the Argonne Av18 and ?-Reid soft-core potentials. The effects of different potentials as well as temperature are investigated. It is found that the nonrelativistic version of Bjorken scaling approximately sets in at the momentum transfer of about 1.1 to 1.2 GeV/c and the increase of temperature makes it to decrease. While different potentials do not significantly change CSR, the SRC improves the Coulomb sum rule and we get reasonably close results to both experimental data and others theoretical predictions.

Modarres, M.; Moeini, H.; Moshfegh, H. R.

46

Coulomb-potential effects in nonsequential double ionization under elliptical polarization

NASA Astrophysics Data System (ADS)

Using a semiclassical model, we evaluate the correlated electron momentum distribution from nonsequential double ionization (NSDI) of neon in an elliptically polarized laser field. The momentum distribution pattern exhibits a nontrivial change with the increase of the laser ellipticity, which can be understood as a combined effect of the extra laser electric field and the ionic Coulomb potential on the tunnel-ionized electron trajectory. Especially for large ellipticities (?>0.2), multiple return collision trajectory contributes dominantly to the NSDI yield and determines the correlated electron momentum distribution, revealing an indispensable role of ionic Coulomb potential in NSDI dynamics under elliptical polarization. Moreover, the nontrivial evolution of the correlated electron momentum distribution with the ellipticity revealed in our model should be testable by a realistic experiment.

Wu, MingYan; Wang, YanLan; Liu, XiaoJun; Li, WeiDong; Hao, XiaoLei; Chen, Jing

2013-01-01

47

The positronium negative ion (Ps\\u000a ?) in exponential cosine-screened Coulomb potentials (ECSCP) has been theoretically investigated. Using highly correlated wave\\u000a functions with 525 terms we report binding energies, annihilation rates and several other parameters for various values of\\u000a the screening parameter. Our reported results for the unscreened case are in nice agreement with some of the most accurate\\u000a results in

Arijit Ghoshal; Y. K. Ho

2009-01-01

48

On the Quantization of One-Dimensional Nonstationary Coulomb Potential System

NASA Astrophysics Data System (ADS)

Exact solutions of the one-dimensional Schrödinger equation with a time-dependent Coulomb potential [-z(t)/| x |] are investigated using the invariant method (Lewis and Riesenfeld theorem) together with unitary transformation approach. The eigenfunctions and the corresponding eigenvalues of the system are obtained analytically. When the time dependence of all coefficients vanishes, our results exactly reduce to those known for stationary case.

Menouar, Salah; Maamache, Mustapha; Choi, Jeong Ryeol; Sever, Ramazan

2012-06-01

49

A new perturbation technique for eigenenergies of the screened coulomb potential

The explicit semiclassical treatment of the logarithmic perturbation theory for the bound-state problem of the radial Shrodinger equation with the screened Coulomb potential is developed. Based upon h-expansions and new quantization conditions a novel procedure for deriving perturbation expansions is offered. Avoiding disadvantages of the standard approach, new handy recursion formulae with the same simple form both for ground and excited states have been obtained.

I. V. Dobrovolska; R. S. Tutik

2006-09-19

50

NASA Astrophysics Data System (ADS)

We introduce a new family of Hamiltonians with a deformed Kepler-Coulomb potential dependent on an indexing parameter k. We show that this family is superintegrable for all rational k and compute the classical trajectories and quantum wavefunctions. We show that this system is related, via coupling constant metamorphosis, to a family of superintegrable deformations of the harmonic oscillator given by Tremblay, Turbiner and Winternitz. In doing so, we prove that all Hamiltonians with an oscillator term are related by coupling constant metamorphosis to systems with a Kepler-Coulomb term, both on Euclidean space. We also look at the effect of the transformation on the integrals of the motion, the classical trajectories and the wavefunctions, and give the transformed integrals explicitly for the classical system.

Post, Sarah; Winternitz, Pavel

2010-06-01

51

General Pade Effective Potential for Coulomb Problems in Condensed and Soft Matters

NASA Astrophysics Data System (ADS)

Effective potentials for finding the ground states and physical configurations have essential meaning in many Coulomb problems of condensed and soft matters. The ordinary n-Pade approximation potentials define as the ratio of Pi(r)/Pi+1(r), where Pi(r) are the polynomials of i-th order of charge separation r, give quite good fit and agreement of calculation results and experimental data for Coulomb problems, where screening effects are not important or exchange photons still are massless. In this work we consider a general Pade effective potential by included a factor of exponential form, which could give more accurate results also for above mentioned cases. This general Pade effective potentials with analytical expressions were useful to perform analytical calculations, estimations and to reduce the amount of computational time for future investigations in condensed and soft matter topics. For example of soft matter problems, we study the case of MS2 virus, the general Pade potential gives much more correct results comparing with ordinary Pade approximation.

Quyen, B. L.; Mai, D. N.; Hoa, N. M.; Van, T. T. T.; Hoai, N. L.; Viet, N. A.

2014-09-01

52

NASA Astrophysics Data System (ADS)

Using eight different versions of the nuclear potential, we have calculated the height and position of the Coulomb barrier for reactions induced by loosely bound projectiles, 6Li, 7Li and 9Be. A total of 13 reactions have been studied and by comparing the results with the empirical values, we found the prediction of all the potentials quite satisfactory as they could reproduce the empirical values within 5% on average. The potentials Bass 80, BW 91 and AW 95 can determine the experimental barrier within 2% on average. For the reaction 6Li + 152Sm the deviations from the empirical values are unusually large. On applying the correction of the Coulomb potential for the deformed target 152Sm the new values obtained are found to be closer to the empirical values. Applying Wong's formula the fusion cross-sections for four reactions are compared with the results of single BPM. The fittings of the fusion cross-section for the potentials of CW 76, BW 91 and Bass 80 are better than the rest.

Phookan, C. K.; Kalita, K.

2013-02-01

53

Effect of a relativistic correction to the Coulomb potential on the energy levels of hydrogen atom

Based on classical electrodynamics, it is argued that the Coulomb potential (which is strictly valid for two point charges at rest), commonly used in the study of energy levels of hydrogen atom is not the correct one, because the electron in the hydrogen atom moves with relativistic speeds with respect to the nucleus. Retardation effect has to be considered in accordance with Li\\'{e}nard-Wiechert (or retarded) potential of a moving charge or the relativistic electrodynamics. However, such a consideration introduces a correction to the Coulomb potential, whose quantum mechanical expectation value is estimated at $E_{ret} = - \\frac{mc^2\\alpha ^4}{2n^3(l+1/2)}$, which is of the same order as the fine structure of hydrogen atom and hence added to the standard energy eigenvalue values of H-atom. This correction lifts the $l$-degeneracy in the spectra of H-atom and hence modifies the standard result. The result disturbs the existing agreement between the theory and experiments on H-atom and hence requires further theoretical and experimental re-examination. The implications of this result for the Kepler-problem in general is also discussed in the context of Heaviside's gravity, which seems to offer an alternative explanation for the non-Newtonian perihelion advance of Mercury without invoking the space-time curvature formalism of Einstein's general theory of relativity.

Harihar Behera

2012-01-10

54

Jancovici derived the exactr\\u000a 2 term in the expansion of the screening potential of the one-component plasma (OCP) around r = 0, which led to much improved\\u000a analysis of the simulation data, but the correspondingly important term has never been calculated for electron-screened plasmas.\\u000a The Onsager molecule approach provides the strong-coupling-limit result for the OCP screening potentials, features the exact

Yaakov Rosenfeld; Gilles Chabrier

1997-01-01

55

NASA Astrophysics Data System (ADS)

The liquid-vapor phase diagrams of equal size diameter ? binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fer?andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006), 10.1063/1.2159481; A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006), 10.1063/1.2335453]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length ?. Caballero found stability for values of ?? up to 20 while Fortini reported stability for ?? up to 20 while Fortini reported stability for ?? ? 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of ??. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of ?? > 20 and that the critical temperatures have a maximum value at around ?? = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials.

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

2013-02-01

56

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

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

2013-02-01

57

Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved Quantum Molecular Dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of Y(n)/Y(p). This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Qianghua Wu; Yingxun Zhang; Zhigang Xiao; Rensheng Wang; Yang Zhang; Zhuxia Li; Ning Wang; R. H. Schowalter

2015-01-17

58

Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved Quantum Molecular Dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of Y(n)/Y(p). This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Wu, Qianghua; Xiao, Zhigang; Wang, Rensheng; Zhang, Yang; Li, Zhuxia; Wang, Ning; Schowalter, R H

2015-01-01

59

Two-Coulomb-exchange potential in the presence of open channels

We use the techniques of dispersion theory to study the long-range behavior of the two-Coulomb-exchange potential acting between two atoms, or between an atom and a charged system such as an ion or electron, in the presence of open channels. In contrast to earlier work, we avoid the use of a multipole expansion. We focus on the case of atoms in initial {ital S} states. When one of the systems is in an excited state or the relative kinetic energy is large enough to allow excitation, the potential has an imaginary part that falls off exponentially with distance in the absence of degeneracy and as an inverse power in the presence of degeneracy of the initial state. The asymptotic form of the real part is unchanged from that found in the closed-channel case.

Au, C.K. (Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (US)); Feinberg, G. (Department of Physics, Columbia University, New York, New York 10027 (US)); Sucher, J. (Department of Physics, University of Maryland, College Park, Maryland 20742 (US))

1991-04-01

60

Competition between Coulomb and symmetry potential in semi-peripheral heavy ion collisions

NASA Astrophysics Data System (ADS)

The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system 40Ar+197Au , at b =6 fm and Ebeam=35 , 50, and 100 MeV /nucleon, is investigated by using the improved quantum molecular dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in the projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant neutron to proton yield ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of neutron to proton yield ratio. This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

Wu, Qianghua; Zhang, Yingxun; Xiao, Zhigang; Wang, Rensheng; Zhang, Yan; Li, Zhuxia; Wang, Ning; Showalter, R. H.

2015-01-01

61

A non-quantized flux is introduced claimed to be responsible for the Coulombic potential as well as confinement at intermediate distances. Our calculations show if uncorrelated vortices are not quantized with center elements, the asymptotic string tensions are lost while the ratio of the Coulombic strength and intermediate string tensions are in exact agreement with Casimir scaling. Using uncorrelated quantized and non-quantized fluxes with different contributions in the potential between static color sources result in the correct N-ality dependence at large distances and exact agreement with Casimir scaling at short and intermediate distances.

Alireza Ahmadi; Shahnoosh Rafibakhsh

2015-04-11

62

Coulomb explosion potential sputtering induced by slow highly charged ion impact

We have observed secondary ion emission from a hydrogen-terminated Si(111) 1x1 surface and a native SiO{sub 2} thin film on the Si substrate (SiO{sub 2}/Si) irradiated with slow (v{sub ion}

Tona, Masahide; Takahashi, Satoshi; Nagata, Kazuo; Yoshiyasu, Nobuo; Yamada, Chikashi; Nakamura, Nobuyuki; Ohtani, Shunsuke; Sakurai, Makoto [Institute for Laser Science and Department of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo 182-8585 (Japan); Department of Physics, Kobe University, Kobe, Hyogo 657-8501 (Japan)

2005-11-28

63

Dynamic simulation of sediment films of Yukawa-stabilized particles

NASA Astrophysics Data System (ADS)

The fast lubrication dynamics method is applied to simulate the motion and deposition of charge-stabilized 100-nm-diam particles into sediment films from aqueous dispersions. Colloidal interactions are incorporated with a Yukawa potential and the effects of the screened-Coulomb potential strength and Péclet number (which controls the sedimentation driving force) on particle orientation are quantified with a sixfold bond order parameter. The effect of sediment growth rate on the order parameter is determined and related to a competition between the electrostatic interaction strength and sedimentation driving force. Increasing the electrostatic interaction strength and decreasing the Péclet number lead to lower sediment growth rates and consequently greater sixfold bond order. Our work demonstrates the feasibility of including lubrication interactions in dynamic simulations of sediment films and suggests that these interactions play a central role in the kinetics of film microstructure development and consequently in the degree of order within the film.

Brewer, Damien D.; Kumar, Satish

2015-02-01

64

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

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

65

NASA Astrophysics Data System (ADS)

Molecular dynamics (MD) simulations are performed to investigate the temperature relaxation between electrons and ions in a fully ionized, dense hydrogen plasma. We used HM (J. P. Hansen and I. R. McDonald) potential and introduced a truncated Coulomb interaction, which can avoid Coulomb catastrophe by choosing an appropriate cutting radius. The calculated results are compared with those from theoretical models (LS, GMS, BPS), whose applicability is also discussed. The effect of the interaction between ions and electrons on the temperature relaxation process is also investigated in the strong collision region. Finally, we discuss the effect of exchange interaction of electrons to the temperature relaxation.

Ma, Qian; Dai, Jiayu; Kang, Dongdong; Zhao, Zengxiu; Yuan, Jianmin; Zhao, Xueqing

2014-12-01

66

NASA Astrophysics Data System (ADS)

We present two analytical methods, Taylor expansion and Gegenbauer expansion, to efficiently and accurately calculate the two-electron screened Coulomb potential matrix elements with Slater-type configuration-interaction basis functions. The former permits great advantages in fast computation of the potential matrices at small screening parameters and the latter allows accurate calculation of the matrices at all screening parameters. The bound and resonant states of a He atom embedded in the screening environment are calculated by employing the variational and complex-scaling methods, respectively, and the results are compared with other theoretical predictions. The expectation values of some physical quantities for He ground state are compared with the recent calculation of Ancarani and Rodriguez [Phys. Rev. A 89, 012507 (2014), 10.1103/PhysRevA.89.012507] and extended to stronger screening environment. The energies and widths for the doubly excited resonant states are in good agreement with previous calculations, while the interelectronic angle arccos

Jiao, Li Guang; Ho, Yew Kam

2014-07-01

67

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

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

68

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

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

2011-04-15

69

Strong energy dependence of the optical potential for 32S+58,64Ni near the Coulomb barrier

The elastic scattering of 32S+ 58,64Ni was measured at sulfur beam energies of 82, 88, 91, 93, 98, 102.5, 108, and 150 MeV. Evidence is found for a marked energy dependence of the optical potential at the strong-absorption radii around the Coulomb barrier, in good agreement with parallel information extracted from the fusion cross sections for the same systems.

A. M. Stefanini; D. Bonamini; A. Tivelli; G. Montagnoli; G. Fortuna; Y. Nagashima; S. Beghini; C. Signorini; A. Derosa; G. Inglima; M. Sandoli; G. Cardella; F. Rizzo

1987-01-01

70

We study the effect of spatially dependent mass functions over the solution of the Klein-Gordon equation in the (3 + 1 -dimensions for spinless bosonic particles where the mixed scalar-vector Coulomb-like field potentials and masses are directly proportional and inversely proportional to the distance from the force center. The exact bound-state energy eigenvalues and the corresponding wave functions of the

S. M. Ikhdair

2009-01-01

71

We study the effect of spatially dependent mass functions over the solution of the Klein-Gordon equation in the (3 + 1 -dimensions\\u000a for spinless bosonic particles where the mixed scalar-vector Coulomb-like field potentials and masses are directly proportional\\u000a and inversely proportional to the distance from the force center. The exact bound-state energy eigenvalues and the corresponding\\u000a wave functions of the

Sameer M. Ikhdair

2009-01-01

72

Decrypting gauge-Yukawa cookbooks

NASA Astrophysics Data System (ADS)

For many years, theorists have calculated formulas for useful quantities in general gauge-Yukawa theories. However, these cookbooks are often very difficult to use since the general notation is far removed from practical model building. In this paper, we present the structure delta, which allows us to use a surprisingly convenient notation that bridges the gap between general gauge-Yukawa theories and specific models. This is particularly useful for the computation of beta functions, but can also be extended to handle spontaneous symmetry breaking, the effective potential and a variety of other quantities. We will introduce it using the standard model of particle physics and a toy model with an SU( N c ) gauge symmetry.

Mølgaard, Esben

2014-07-01

73

We model the effect of gravitational settling in the upper chromosphere on O, Fe, Si, and Ne, studying whether Coulomb collisions between ionized low First Ionization Potential (FIP) elements and protons is sufficient to cause abundance enhancements relative to oxygen. We find that low-FIP abundance enhancements comparable to observed values can be obtained provided the hydrogen ionization degree lies in the approximate range 10%-30%, which agrees with chromospheric models. Lower or higher hydrogen ionization causes the FIP-effect to become smaller or absent (depletion of all heavy elements). Iron must be almost fully ionized in order to become enriched relative to high-FIP elements, and this requires a high iron photoionization rate. The time scale necessary to produce the enrichment increases rapidly with increasing H ionization. For iron in a background from a semiempirical chromospheric model, with an H ion fraction of the order of 30%-40% in the upper chromosphere, 1-2 hr of settling is required to produce enhancements comparable to observations. The absolute abundance (relative to H), which monotonically decreases with time during settling, has by that time decreased by less than 50% in the same altitude region. With the same background conditions, the silicon abundance is more strongly enhanced by the settling than the iron abundance. The high-FIP element neon is depleted, relative to O and low-FIP elements, in the same background and altitude region where iron is enhanced, typically by 50% or more relative to O after 1-2 hr of settling.

Bo, Iselin M. Th. [Piazza Europa 16, I-52026 Pian di Sco (Italy); Esser, Ruth [Institute of Science and Technology, University of Tromso, NO-9037 Tromso (Norway); Lie-Svendsen, Oystein, E-mail: iselinbo@online.no, E-mail: ruth.esser@uit.no, E-mail: Oystein.Lie-Svendsen@ffi.no [Norwegian Defence Research Establishment (FFI), P.O. Box 25, NO-2027 Kjeller (Norway)

2013-05-20

74

The potential group method is applied to the n-dimensional Coulomb-Rosochatius potential, whose bound states and scattering states are worked out in detail. As far as scattering is concerned, the S-matrix elements are computed by the method of intertwining operators and an integral representation is obtained for the scattering amplitude. It is shown that the maximal superintegrability of the system is due to the underlying potential group and that the 2n-1 constants of motion are related to Casimir operators of subgroups.

G. A. Kerimov; A. Ventura

2011-07-25

75

Collisional and collisionless expansion of Yukawa balls

NASA Astrophysics Data System (ADS)

The expansion of Yukawa balls is studied by means of molecular dynamics simulations of collisionless and collisional situations. High computation speed was achieved by using the parallel computing power of graphics processing units. When the radius of the Yukawa ball is large compared to the shielding length, the expansion process starts with the blow-off of the outermost layer. A rarefactive wave subsequently propagates radially inward at the speed of longitudinal phonons. This mechanism is fundamentally different from Coulomb explosions, which employ a self-similar expansion of the entire system. In the collisionless limit, the outer layers carry away most of the available energy. The simulations are compared with analytical estimates. In the collisional case, the expansion process can be described by a nonlinear diffusion equation that is a special case of the porous medium equation.

Piel, Alexander; Goree, John A.

2013-12-01

76

Evaluation of Coulomb potential in a triclinic cell with periodic boundary conditions

Lekner and Sperb's work on the evaluation of Coulomb energy and forces under periodic boundary conditions is generalized that makes it possible to use a triclinic unit cell in simulations in 3D rather than just an orthorhombic cell. The expressions obtained are in a similar form as previously obtained by Lekner and Sperb for the especial case of orthorhombic cell.

Sandeep Tyagi

2006-02-02

77

We discuss the arising of bound states solutions of the Schrödinger equation due to the presence of a Coulomb-type potential induced by the interaction between a moving electric quadrupole moment and a magnetic field. Furthermore, we study the influence of the Coulomb-type potential on the harmonic oscillator by showing a quantum effect characterized by the dependence of the angular frequency on the quantum numbers of the system, whose meaning is that not all values of the angular frequency are allowed. -- Highlights: • Interaction between a moving electric quadrupole moment and a magnetic field. • Arising of bound states solutions due to the presence of a Coulomb-type potential. • Influence of the Coulomb-type potential on the harmonic oscillator. • Dependence of the angular frequency on the quantum numbers of the system.

Bakke, K., E-mail: kbakke@fisica.ufpb.br

2014-02-15

78

NASA Astrophysics Data System (ADS)

A detailed investigation of the magnetic dipolar and quadrupolar excitation energies and transition probabilities of helium isoelectronic He, Be2+, C4+, and O6+ have been performed under exponential cosine screened Coulomb potential generated in a plasma environment. The low-lying excited states 1s2:1Se ? 1sns:3Se0, and 1snp:3Po2 (n = 2, 3, 4, and 5) are considered. The variational time-dependent coupled Hartree-Fock scheme has been used. The effect of the confinement produced by the potential on the structural properties is investigated for increasing coupling strength of the plasma. It is noted that there is a gradual destabilization of the energy of the system with the reduction of the ionization potential and the number of excited states. The effect of the screening enhancement on the excitation energies and transition probabilities has also been investigated and the results compared with those available for the free systems and under the simple screened Coulomb potential.

Modesto-Costa, Lucas; Canuto, Sylvio; Mukherjee, Prasanta K.

2015-03-01

79

Based on the series expansion formalism, a relatively simple approach is proposed to solve the eigenvalues problems with partially screened and screened exponential-cosine Coulomb potentials. This approach is used to derive solutions to the Schrödinger equation with the two forms of potentials. The eigenenergies are explicitly deduced from solving the obtained corresponding polynomial equations. For illustration, high accuracy results have been obtained in the entire range of parameter values of these potential forms, with no constraints or adjustable constants. The present approach compares well, with existing methods, the results of which are precisely recovered as particular cases and does allow solutions to eigenvalues problems with any combination of potential parameters. PMID:12636641

Moulay, M; Mansouri, A; Houamer, S

2003-01-01

80

Effective Coulomb logarithm for one component plasma

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

We discuss the arising of bound states solutions of the Schr\\"odinger equation due to the presence of a Coulomb-type potential induced by the interaction between a moving electric quadrupole moment and a magnetic field. Furthermore, we study the influence of the Coulomb-type potential on the harmonic oscillator by showing a quantum effect characterized by the dependence of the angular frequency on the quantum numbers of the system, whose meaning is that not all values of the angular frequency are allowed.

K. Bakke

2014-05-20

82

Solvable rational extensions of the Morse and Kepler-Coulomb potentials

We show that it is possible to generate an infinite set of solvable rational extensions from every exceptional first category translationally shape invariant potential. This is made by using Darboux-B\\"acklund transformations based on unphysical regular Riccati-Schr\\"odinger functions which are obtained from specific symmetries associated to the considered family of potentials.

Yves Grandati

2011-03-25

83

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

Greensite, J.; Olejnik, S.

2003-09-26

84

Microscopic Origin of Shear Relaxation in Strongly Coupled Yukawa Liquids

We report accurate molecular dynamics calculations of the shear stress relaxation in a two-dimensional strongly coupled Yukawa liquid over a wide range of the Coulomb coupling strength $\\Gamma$ and the Debye screening parameter $\\kappa$. Our data on the relaxation times of the ideal- , excess- and total shear stress auto-correlation ($\\tau^{id}_M, \\tau^{ex}_M, \\tau_M$ respectively) along with the lifetime of local atomic connectivity $\\tau_{LC}$ leads us to the following important observation. Below a certain crossover $\\Gamma_c(\\kappa)$, $\\tau_{LC} \\rightarrow \\tau^{ex}_M$, directly implying that here $\\tau_{LC}$ is the microscopic origin of the relaxation of excess shear stress unlike the case for ordinary liquids where it is the origin of the relaxation of the total shear stress. At $\\Gamma >> \\Gamma_c(\\kappa)$ i.e. in the potential energy dominated regime, $\\tau^{ex}_M\\rightarrow \\tau_M$ meaning that $\\tau^{ex}_M$ can fully account for the elastic or "solid like" behavior.

Ashwin J.; Abhijit Sen

2014-08-01

85

The problem of analytical solutions of the 3-dimensional Dirac equation is usually studied via techniques such as The Nikiforov-Uvarov (NU) method. Here, we see that one of the most attractive potentials can be brought into a well-known form of Schroedinger-like problem possessing known solutions via the methodology of supersymmetry (SUSY). Next, using the idea of shape invariance, we calculate exact solutions of Dirac equation for quadratic scalar and vector potentials in the presence of a tensor potential that depends on the radial component either linearly or inversely. The tensor potential itself, besides its applications, removes degeneracy, too.

Zarrinkamar, S., E-mail: zarrinkamar.s@gmail.co [Physics Department, Shahrood University of Technology, P.O. Box 3619995161-316, Shahrood (Iran, Islamic Republic of); Rajabi, A.A.; Hassanabadi, H. [Physics Department, Shahrood University of Technology, P.O. Box 3619995161-316, Shahrood (Iran, Islamic Republic of)

2010-11-15

86

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

Nicolas Michel

2008-02-12

87

Coulomb string tension, asymptotic string tension, and the gluon chain

NASA Astrophysics Data System (ADS)

We compute, via numerical simulations, the nonperturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

Greensite, Jeff; Szczepaniak, Adam P.

2015-02-01

88

An Indirect Handle on the Down-Quark Yukawa Coupling

To measure the Yukawa couplings of the up and down quarks, Y_{u,d}, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a shift of -100% in the down-quark Yukawa Y_d would generically result in ds transitions in conflict with Kaon physics. This could already be seen as evidence for a non-vanishing direct coupling of the down quark to the newly discovered Higgs boson. The non-observation of certain, already well-constrained, processes is thus turned into a powerful indirect measure of physical parameters of the effective Standard-Model, which are so far basically unconstrained from experiment and extremely challenging to access with other methods. In particular, we can already deduce that Y_d should vary at most by ~50% from its Standard Model value, barring an alignment of new physics effects with the SM Yukawa couplings. Such an (orthogonal) alignment scenario is however in general much easier to test at the LHC. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on the physical Yukawa coupling of the up-quark.

Florian Goertz

2014-05-31

89

In this paper we have performed the calculus of the energy states of hydrogen atom by using the Schroedinger equation with a Coulomb potential which is modified by the interaction between the magnetic moments of the proton and the electron, respectively. The important result is that the Lamb shift appears as a natural result of the solution of Schroedinger equation. The obtained results are in a good agreement with experimental data.

Voicu Dolocan

2014-04-06

90

An improved approach is presented for calculating pH-dependent electrostatic effects in proteins using sigmoidally screened Coulomb potentials (SCP). It is hypothesized that a key determinant of seemingly aberrant behavior in pKa shifts is due to the properties of the unique microenvironment around each residue. To help demonstrate this proposal, an approach is developed to characterize the microenvironments using the local hydrophobicity/hydrophilicity around each residue of the protein. The quantitative characterization of the microenvironments shows that the protein is a complex mosaic of differing dielectric regions that provides a physical basis for modifying the dielectric screening functions: in more hydrophobic microenvironments the screening decreases whereas the converse applies to more hydrophilic regions. The approach was applied to seven proteins providing more than 100 measured pKa values and yielded a root mean square deviation of 0.5 between calculated and experimental values. The incorporation of the local hydrophobicity characteristics into the algorithm allowed the resolution of some of the more intractable problems in the calculation of pKa. Thus, the divergent shifts of the pKa of Glu-35 and Asp-66 in hen egg white lysozyme, which are both about 90% buried, was correctly predicted. Mechanistically, the divergence occurs because Glu-35 is in a hydrophobic microenvironment, while Asp-66 is in a hydrophilic microenvironment. Furthermore, because the calculation of the microenvironmental effects takes very little CPU time, the computational speed of the SCP formulation is conserved. Finally, results from different crystal structures of a given protein were compared, and it is shown that the reliability of the calculated pKa values is sufficient to allow identification of conformations that may be more relevant for the solution structure. PMID:10388736

Mehler, E L; Guarnieri, F

1999-01-01

91

NASA Astrophysics Data System (ADS)

The parametric Nikiforov-Uvarov (pNU) and asymptotic iteration method (AIM) are applied to study the approximate analytic bound state eigensolutions (energy levels and wave functions) of the radial Schr¨odinger equation (SE) for the Hellmann potential which represents the superposition of the attractive Coulomb potential (-a/r) and the Yukawa potential bexp(-?/r)/r of arbitrary strength b and screening parameter d in closed form. The analytical expressions to the energy eigenvalues Enl yield quite accurate results for a wide range of n; l in the limit of very weak screening but the results become gradually worse as the strength b and the screening coefficient d increase. The calculated bound state energies have been compared with available numerical data. Special cases of our solution like pure Coulomb and Yukawa potentials are also investigated.

Ikhdair, Sameer M.; Falaye, Babatunde J.

2013-11-01

92

ERIC Educational Resources Information Center

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

Fay, Temple H.

2012-01-01

93

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

94

Shear viscosity and shear thinning in two-dimensional Yukawa liquids

A two-dimensional Yukawa liquid is studied using two different nonequilibrium molecular dynamics simulation methods. Shear viscosity values in the limit of small shear rates are reported for a wide range of Coulomb coupling parameter and screening length. At high shear rates it is demonstrated that this liquid exhibits shear thinning, i.e., the viscosity $\\eta$ diminishes with increasing shear rate. It is expected that two-dimensional dusty plasmas will exhibit this effect.

Z. Donkó; J. Goree; P. Hartmann; K. Kutasi

2006-03-24

95

The spinless relativistic Yukawa problem

NASA Astrophysics Data System (ADS)

Noticing renewed or increasing interest in the possibility to describe semirelativistic bound states (of either spin-zero constituents or, upon confining oneself to spin-averaged features, constituents with nonzero spin) by means of the spinless Salpeter equation generalizing the Schrödinger equation toward incorporation of effects caused by relativistic kinematics, we revisit this problem for interactions between bound-state constituents of Yukawa shape, by recalling and applying several well-known tools enabling to constrain the resulting spectra.

Lucha, Wolfgang; Schöberl, Franz F.

2014-12-01

96

Coulomb string tension, asymptotic string tension, and the gluon chain

We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

Greensite, Jeff; Szczepaniak, Adam P.

2015-02-01

97

NASA Astrophysics Data System (ADS)

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 configurations connected to a sodium reordering transition around 280 K. The distinct magnetic phases are investigated by means of muon spin rotation, resistivity, specific heat and magnetization measurements with a focus on the magnetic moment orientation and the dependence of the transition temperatures on the magnetic field strength and orientation. Resistivity measurements under high pressure allow for comparison of the shifts in the transition temperature to the relative change in lattice parameters along the different crystal directions.

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

2010-03-01

98

Two-dimensional electron layers when placed in perpendicular electric and magnetic fields can have a potential well with two minima for the electronic motion normal to the surface. Such double-minimum potential wells also arise for highly excited Rydberg states of atoms in crossed electric and magnetic fields and in certain molecular potential curves. We develop and apply a WKB formalism to

S. K. Bhattacharya; A. R. P. Rau

1982-01-01

99

NASA Astrophysics Data System (ADS)

The following text will give a brief introduction to the physics of the spatially ordered structures, so-called Coulomb crystals, that appear when confined ions are cooled to sufficiently low temperatures. It will as well briefly comment on the very diverse scientific applications of such crystals, which have emerged the past two decades. While this document lacks figures, it includes a substantial number of references in which more detailed information can be found. It is the hope that the text will stimulate the reader to dig deeper into one or more of the discussed subjects and inspire her/him to think about new potential applications.

Drewsen, Michael

2015-03-01

100

Some Unfinished Thoughts on Strong Yukawa Couplings

Yukawa couplings of electroweak Goldstone bosons can be inferred from experiment, but the existence of an elementary Higgs boson is not yet an established fact. If a sequential chiral quark generation does exist, it would bring us now into the strong Yukawa coupling regime. Guided by a Bethe--Salpeter equation approach, we postulate that the leading collapse state, the (heavy) isotriplet and color-singlet $\\pi_1$ meson, becomes the Goldstone boson $G$ itself. Viewing it as a deeply bound state, a gap equation is constructed. This "`bootstrap" picture for electroweak symmetry breaking relies on strong Yukawa coupling, without providing any theory of the latter.

Wei-Shu Hou

2012-01-29

101

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

102

The traditional photon absorbers Cu{sub 2?x}X (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 Cu{sub 2}X 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 Cu{sub 2}X 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 Cu{sub 2}S and Cu{sub 2}Se 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 [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Peihong, E-mail: wqzhang@mail.sic.ac.cn, E-mail: pzhang3@buffalo.edu [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States) [Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260 (United States); Beijing Computational Science Research Center, Beijing 100084 (China); Zhang, Wenqing, E-mail: wqzhang@mail.sic.ac.cn, E-mail: pzhang3@buffalo.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China) [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); School of Chemistry and Chemical Engineering, and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093 (China)

2014-02-21

103

NASA Astrophysics Data System (ADS)

The optical response of organic compounds has been attracting much attention. The one of the reasons is the huge non-linear and ultrafast optical response [K. Yamamoto et. al., J. Phys. Soc. Jpn. 77, 074709(2008)]. In order to investigate such optical properties, we carry out dynamical DMRG calculations to obtain optical responses in the 1/4-filled one-dimensional Hubbard model including the nearest neighbor Coulomb interaction and the alternating electron hopping. The charge gap [S. Nishimoto, M. Takahashi, and Y. Ohta, J. Phys. Soc. Jpn. 69, 1594(2000)] and the bound state [H. Benthien and E. Jeckelmann, Eur. Phys. J. B 44, 287(2005)] in this model have been discussed based on DMRG calculations. In the present study, we introduce an alternating on-site potential giving the polarization in the system into the dimerized Hubbard model, which breaks the reflection symmetry of the system. In this talk, we discuss the obtained linear and the 2nd order non-linear optical susceptibility in order to make a prediction for non-linear optical experiments in the future.

Sota, Shigetoshi; Tohyama, Takami; Brazovskii, Serguei

2012-02-01

104

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

105

A mean spherical model for soft potentials: The hard core revealed as a perturbation

NASA Technical Reports Server (NTRS)

The mean spherical approximation for fluids is extended to treat the case of dense systems interacting via soft-potentials. The extension takes the form of a generalized statement concerning the behavior of the direct correlation function c(r) and radial distribution g(r). From a detailed analysis that views the hard core portion of a potential as a perturbation on the whole, a specific model is proposed which possesses analytic solutions for both Coulomb and Yukawa potentials, in addition to certain other remarkable properties. A variational principle for the model leads to a relatively simple method for obtaining numerical solutions.

Rosenfeld, Y.; Ashcroft, N. W.

1978-01-01

106

Minimal SUSY SO(10) and Yukawa unification

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

107

Indirect Handle on the Down-Quark Yukawa Coupling

NASA Astrophysics Data System (ADS)

To measure the Yukawa couplings of the up and down quarks, Yu ,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in d s transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain—already well-constrained—processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu.

Goertz, Florian

2014-12-01

108

Indirect handle on the down-quark Yukawa coupling.

To measure the Yukawa couplings of the up and down quarks, Yu,d, seems to be far beyond the capabilities of current and (near) future experiments in particle physics. By performing a general analysis of the potential misalignment between quark masses and Yukawa couplings, we derive predictions for the magnitude of induced flavor-changing neutral currents (FCNCs), depending on the shift in the physical Yukawa coupling of first-generation quarks. We find that a change of more than 50% in Yd would generically result in ds transitions in conflict with kaon physics. This could already be seen as evidence for a nonvanishing direct coupling of the down quark to the newly discovered Higgs boson. The nonobservation of certain--already well-constrained--processes is thus turned into a powerful indirect measure of otherwise basically unaccessible physical parameters of the effective standard model. Similarly, improvements in limits on FCNCs in the up-type quark sector can lead to valuable information on Yu. PMID:25615309

Goertz, Florian

2014-12-31

109

Ion Coulomb crystals (ICC), formed by atomic ions at low temperatures in radiofrequency and Penning ion traps, are structures that have remarkable properties and many applications. Images of Coulomb crystals are striking and reveal the crystal structure, which arises from a balance between the trapping forces acting on the ions and their mutual Coulomb repulsion. Applications of these structures range from frequency standards and quantum simulation through to measurement of the cross sections of chemical reactions of ions.

Richard C. Thompson

2014-11-18

110

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

111

Numerical approach to Coulomb gauge QCD

We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wave function using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wave functional.

Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O. [Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana, 47405 (United States); Centre of Theoretical Chemistry and Physics, Institute of Fundamental Sciences, Massey University (Auckland), Private Bag 102904, NSMSC, Auckland (New Zealand)

2008-07-01

112

Universality in some classical Coulomb systems of restricted dimension

Coulomb systems in which the particles interact through thed-dimensional Coulomb potential but are confined in a flat manifold of dimensiond?1 are considered. The actual Coulomb potential acting is defined by particular boundary conditions involving a characteristic macroscopic distanceW in the direction perpendicular to the manifold: either it is periodic of periodW in that direction, or it vanishes on one ideal

P. J. Forrester; B. Jancovici; G. Téllez

1996-01-01

113

CHAPTER 2. COULOMB COLLISIONS 1 Coulomb Collisions

electric field) around any particular background charged particle in a plasma is collectively shielded out of Coulomb collisions between charged particles in a plasma are very different from those of the more by examining trajectories of neutral and charged particles as they move through a partially ionized gas

Callen, James D.

114

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

NASA Astrophysics Data System (ADS)

In the referred paper, the authors use a numerical method for solving ordinary differential equations and a softened Coulomb potential -1 /?{x2+?2 } to study the one-dimensional Coulomb problem by approaching the parameter ? to zero. We note that even though their numerical findings in the soft potential scenario are correct, their conclusions do not extend to the one-dimensional Coulomb problem (? =0 ). Their claims regarding the possible existence of an even ground state with energy -? with a Dirac-? eigenfunction and of well-defined parity eigenfunctions in the one-dimensional hydrogen atom are questioned.

Carrillo-Bernal, M. A.; Núñez-Yépez, H. N.; Salas-Brito, A. L.; Solis, Didier A.

2015-02-01

115

Comment on "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit".

In the referred paper, the authors use a numerical method for solving ordinary differential equations and a softened Coulomb potential -1/sqrt[x^{2}+?^{2}] to study the one-dimensional Coulomb problem by approaching the parameter ? to zero. We note that even though their numerical findings in the soft potential scenario are correct, their conclusions do not extend to the one-dimensional Coulomb problem (?=0). Their claims regarding the possible existence of an even ground state with energy -? with a Dirac-? eigenfunction and of well-defined parity eigenfunctions in the one-dimensional hydrogen atom are questioned. PMID:25768644

Carrillo-Bernal, M A; Núñez-Yépez, H N; Salas-Brito, A L; Solis, Didier A

2015-02-01

116

Constraining the range of Yukawa gravity interaction from S2 star orbits

NASA Astrophysics Data System (ADS)

We consider possible signatures for Yukawa gravity within the Galactic Central Parsec, based on our analysis of the S2 star orbital precession around the massive compact dark object at the Galactic Centre, and on the comparisons between the simulated orbits in Yukawa gravity and two independent sets of observations. Our simulations resulted in strong constraints on the range of Yukawa interaction ? and showed that its most probable value in the case of S2 star is around 5000 - 7000 AU. At the same time, we were not able to obtain reliable constrains on the universal constant ? of Yukawa gravity, because the current observations of S2 star indicated that it may be highly correlated with parameter ? in the range (0 < ? < 1). For ? > 2 they are not correlated. However, the same universal constant which was successfully applied to clusters of galaxies and rotation curves of spiral galaxies (? = 1/3) also gives a satisfactory agreement with the observed orbital precession of the S2 star, and in that case the most probable value for the scale parameter is ? ? 3000±1500 AU. Also, the Yukawa gravity potential induces precession of S2 star orbit in the same direction as General Relativity for ? > 0 and for ? < -1, and in the opposite direction for -1 < ? < 0. The future observations with advanced facilities, such as GRAVITY or/and European Extremely Large Telescope, are needed in order to verify these claims.

Borka, D.; Jovanovi?, P.; Borka Jovanovi?, V.; Zakharov, A. F.

2013-11-01

117

Multi-meson Yukawa interactions at criticality

The critical behavior of a relativistic $\\mathbb{Z}_2$-symmetric Yukawa model at zero temperature and density is discussed for a continuous number of fermion degrees of freedom and of spacetime dimensions, with emphasis on the role played by multi-meson exchange in the Yukawa sector. We argue that this should be generically taken into account in studies based on the functional renormalization group, either in four-dimensional high-energy models or in lower-dimensional condensed-matter systems. By means of the latter method, we describe the generation of multi-critical models in less then three dimensions, both at infinite and finite number of flavors. We also provide different estimates of the critical exponents of the chiral Ising universality class in three dimensions for various field contents, from a couple of massless Dirac fermions down to the supersymmetric theory with a single Majorana spinor.

Vacca, Gian Paolo

2015-01-01

118

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective ?{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z?2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z?0.01, the crossover temperature is the same as for the RPM. PMID:25019760

Patsahan, O

2014-06-01

119

NASA Astrophysics Data System (ADS)

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective ?4 Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z <0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z ?2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z ?0.01, the crossover temperature is the same as for the RPM.

Patsahan, O.

2014-06-01

120

Nonperturbative Yukawa Couplings from String Instantons

Nonperturbative D-brane instantons can generate perturbatively absent though phenomenologically relevant couplings for type II orientifold compactifications with D-branes. We discuss the generation of the perturbatively vanishing SU(5) GUT Yukawa coupling of type <10 10 5{sub H}>. Moreover, for a simple globally consistent intersecting D6-brane model, we discuss the generation of mass terms for matter fields. This can serve as a mechanism for decoupling exotic matter.

Blumenhagen, Ralph [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany); Cvetic, Mirjam; Richter, Robert; Weigand, Timo [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6996 (United States); Luest, Dieter [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany); Arnold-Sommerfeld-Center, LMU Muenchen, Theresienstrasse 37, 80333 Munich (Germany)

2008-02-15

121

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

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

122

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

123

Yukawa and triscalar processes in electroweak baryogenesis

We derive the contributions to the quantum transport equations for electroweak baryogenesis due to decays and inverse decays induced by triscalar and Yukawa interactions. In the minimal supersymmetric standard model (MSSM), these contributions give rise to couplings between Higgs and fermion supermultiplet densities, thereby communicating the effects of CP-violation in the Higgs sector to the baryon sector. We show that the decay and inverse decay-induced contributions that arise at zeroth order in the strong coupling, {alpha}{sub s}, can be substantially larger than the O({alpha}{sub s}) terms that are generated by scattering processes and that are usually assumed to dominate. We revisit the often-used approximation of fast Yukawa-induced processes and show that for realistic parameter choices it is not justified. We solve the resulting quantum transport equations numerically with special attention to the impact of Yukawa rates and study the dependence of the baryon-to-entropy ratio Y{sub B} on MSSM parameters.

Cirigliano, Vincenzo; Ramsey-Musolf, Michael J.; Tulin, Sean; Lee, Christopher [California Institute of Technology, Pasadena, California 91125 (United States); Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195 (United States)

2006-06-01

124

Yukawa Textures From Heterotic Stability Walls

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

Lara B. Anderson; James Gray; Burt Ovrut

2010-01-13

125

Proton-proton scattering without Coulomb force renormalization

We demonstrate numerically that proton-proton (pp) scattering observables can be determined directly by standard short range methods using a screened pp Coulomb force without renormalization. In examples the appropriate screening radii are given. We also numerically investigate solutions of the 3-dimensional Lippmann-Schwinger (LS) equation for a screened Coulomb potential alone in the limit of large screening radii and confirm analytically predicted properties for off-shell, half-shell and on-shell Coulomb t-matrices. These 3-dimensional solutions will form a basis for a novel approach to include the pp Coulomb interaction into the 3N Faddeev framework.

R. Skibinski; J. Golak; H. Witala; W. Glockle

2009-03-06

126

Variational Bound States of Screened Potentials

NASA Astrophysics Data System (ADS)

Anumber of years ago, a calculational scheme was introduced by Stubbins [Phys. Rev. A48, 220 (1993)] to compute the energies of both the Hulthén and Yukawa potentials. The method introduces a particular ansatz for solving the Schrödinger equation with screened Coulomb type potentials. In this work, we wish to review the method of Stubbins and to show that it is, in fact, equivalent and a subset of a more systematic (and hence more useful) variational scheme [Zhou et al. Phys. Rev. A51, 3337 (1995)]. This variational approach involves the construction of a basis by taking derivatives of the variational parameters of the system. The eigenvalues of the Hamiltonian matrix are then minimized with respect to these parameters yielding a "best guess" upper bound on the energies.

Mancini, Jay D.; Fessatidis, Vassilios; K. Murawski, Robert; Bowen, Samuel P.

2014-08-01

127

Coulomb systems seen as critical systems: Ideal conductor boundaries

When a classical Coulomb system has macroscopic conducting behavior, its grand potential has universal finite-size corrections similar to the ones which occur in the free energy of a simple critical system: the massless Gaussian field. Here, the Coulomb system is assumed to be confined, by walls made of an ideal conductor material; this choice corresponds to simple (Dirichlet) boundary conditions

B. Jancovici; G. Téllez

1996-01-01

128

Classical Coulomb systems: Screening and correlations revisited

From the laws of macroscopic electrostatics of conductors (in particular, the existence of screening), taken as given, one can deduce universal properties for the thermal fluctuations in a classical Coulomb system at equilibrium. The universality is especially apparent in the long-range correlations of the electrical potentials and fields. The charge fluctuations are derived from the field fluctuations. This is a

B. Jancovici

1995-01-01

129

Electron Radiative Transitions in a Coulomb Field

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

130

NSDL National Science Digital Library

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

Schofield, Andrew N.

131

Statics and dynamics of Yukawa cluster crystals on ordered substrates

NASA Astrophysics Data System (ADS)

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

Reichhardt, C.; Olson Reichhardt, C. J.

2012-05-01

132

In order to give a basis to the structure and correlation analysis of fine particle (dusty) plasma and colloidal suspensions, thermodynamic treatment of mixtures of macroscopic and microscopic charged particles within the adiabatic response of the latter is extended to include the case where the system is finite and weakly inhomogeneous. It is shown that the effective potential for macroscopic particles is composed of two elements: mutual Yukawa repulsion and a confining (attractive) Yukawa potential from their `shadow' or the average charge density of macroscopic particles multiplied by the minus sign. The result clarifies the relation between two approaches hitherto taken where either a parabolic one-body potential is assumed or the average distribution is assumed to be flat with finite extension.

Totsuji, Hiroo

2014-01-01

133

Yukawa Interactions and Supersymmetric Electroweak Baryogenesis

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.

Chung, Daniel J. H.; Garbrecht, Bjoern [University of Wisconsin, Madison, Wisconsin 53706-1390 (United States); Ramsey-Musolf, Michael J. [University of Wisconsin, Madison, Wisconsin 53706-1390 (United States); California Institute of Technology, Pasadena, California 91125 (United States); Tulin, Sean [California Institute of Technology, Pasadena, California 91125 (United States)

2009-02-13

134

Yukawa interactions and supersymmetric electroweak baryogenesis.

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

135

Yukawa Textures in Heterotic M-Theory

We examine the structure of the Yukawa couplings in the 11 dimensional Horava-Witten M-theory based on non-standard embeddings. We find that the CKM and quark mass hierarchies can be explained in M Theory without introducing undue fine tuning. A phenomenological example is presented satisfying all CKM and quark mass data requiring the 5-branes cluster near the second orbifold plane, and that the instanton charges of the physical orbifold plane vanish. The latter condition is explicitly realized on a Calabi-Yau manifold with del Pezzo base dP_7.

R. Arnowitt; B. Dutta

2000-11-20

136

Yukawa Interactions and Supersymmetric Electroweak Baryogenesis

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.

Daniel J. H. Chung; Bjorn Garbrecht; Michael J. Ramsey-Musolf; Sean Tulin

2008-08-08

137

Exclusive Window onto Higgs Yukawa Couplings.

We show that both flavor-conserving and flavor-violating Yukawa couplings of the Higgs boson to first- and second-generation quarks can be probed by measuring rare decays of the form h?MV, where M denotes a vector meson and V indicates either ?, W or Z. We calculate the branching ratios for these processes in both the standard model and its possible extensions. We discuss the experimental prospects for their observation. The possibility of accessing these Higgs couplings appears to be unique to the high-luminosity LHC and future hadron colliders, providing further motivation for those machines. PMID:25815924

Kagan, Alexander L; Perez, Gilad; Petriello, Frank; Soreq, Yotam; Stoynev, Stoyan; Zupan, Jure

2015-03-13

138

Exclusive Window onto Higgs Yukawa Couplings

NASA Astrophysics Data System (ADS)

We show that both flavor-conserving and flavor-violating Yukawa couplings of the Higgs boson to first- and second-generation quarks can be probed by measuring rare decays of the form h ?M V , where M denotes a vector meson and V indicates either ? , W or Z . We calculate the branching ratios for these processes in both the standard model and its possible extensions. We discuss the experimental prospects for their observation. The possibility of accessing these Higgs couplings appears to be unique to the high-luminosity LHC and future hadron colliders, providing further motivation for those machines.

Kagan, Alexander L.; Perez, Gilad; Petriello, Frank; Soreq, Yotam; Stoynev, Stoyan; Zupan, Jure

2015-03-01

139

Complex viscosity of 3D Yukawa liquids

NASA Astrophysics Data System (ADS)

The viscoelastic properties of strongly-coupled Yukawa liquids are investigated by computing the complex shear viscosity ?(?) using three methods of molecular dynamics simulation: equilibrium, nonequilibrium, and Langevin dynamics. A change from viscous to elastic response is observed with increasing frequency, as well as a decrease of the magnitude of the viscosity with increasing frequency. The structure of the transverse current autocorrelation functions reveals the onset of a shear mode. These functions also make it possible to derive the wavenumber (length scale) dependence of the shear viscosity.

Donkó, Z.; Goree, J.; Hartmann, P.

2011-11-01

140

Cosmological Constraints in SUSY with Yukawa Unification

The cosmological relic density of the lightest supersymmetric particle of the minimal supersymmetric standard model is calculated under the assumption of gauge and Yukawa coupling unification. We employ radiative electroweak breaking with universal boundary conditions from gravity-mediated supersymmetry breaking. Further constraints are imposed by the experimental bounds on the b-quark mass and the BR(b -> s gamma). We find that coannihilation of the lightest supersymmetric particle, which turns out to be an almost pure bino, with the next-to-lightest supersymmetric particle (the lightest stau) is crucial for reducing its relic density to an acceptable level.

Mario E. Gomez

2001-02-05

141

NASA Astrophysics Data System (ADS)

The structure and thermodynamics of strongly coupled dusty plasmas are investigated with the soft mean spherical approximation. This integral theory approach is analytically solvable for Yukawa pair interactions yielding a closed-form solution for the direct correlation function. The pair correlation function, the structure factor, and basic thermodynamic quantities are calculated for a wide range of parameters. Exact consistency between the "energy"-"virial" thermodynamic routes and approximate consistency between the "energy"-"compressibility" paths is demonstrated. Comparison with extensive molecular dynamics results is carried out and a remarkable agreement from the Coulomb limit to the strongly screened limit is revealed. The soft mean spherical approximation is concluded to be particularly well suited for the study of dusty plasma liquids, uniquely combining simplicity and accuracy.

Tolias, P.; Ratynskaia, S.; de Angelis, U.

2014-11-01

142

The structure and thermodynamics of strongly coupled dusty plasmas are investigated with the soft mean spherical approximation. This integral theory approach is analytically solvable for Yukawa pair interactions yielding a closed-form solution for the direct correlation function. The pair correlation function, the structure factor, and basic thermodynamic quantities are calculated for a wide range of parameters. Exact consistency between the "energy"-"virial" thermodynamic routes and approximate consistency between the "energy"-"compressibility" paths is demonstrated. Comparison with extensive molecular dynamics results is carried out and a remarkable agreement from the Coulomb limit to the strongly screened limit is revealed. The soft mean spherical approximation is concluded to be particularly well suited for the study of dusty plasma liquids, uniquely combining simplicity and accuracy. PMID:25493891

Tolias, P; Ratynskaia, S; de Angelis, U

2014-11-01

143

Fluid approach to evaluate sound velocity in Yukawa systems (complex plasmas)

The conventional fluid description of multi-component plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasi-localized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strengt...

Khrapak, Sergey

2015-01-01

144

Viscoelastic response of Yukawa liquids and P. Hartmann1

Viscoelastic response of Yukawa liquids Z. Donkó,1 J. Goree,2 and P. Hartmann1 1 Research Institute 2009; published 14 May 2010 The viscoelastic properties of strongly coupled Yukawa liquids, 52.25.Fi, 52.27.Lw, 83.60.Bc I. INTRODUCTION Viscoelasticity is the term used to describe how soft ma

Goree, John

145

Momentum eigenfunctions in the complex momentum plane. VI. A local potential function

NASA Astrophysics Data System (ADS)

The square root of the charge density for an atom, or molecule with fixed nuclei, in its lowest electronic state (assumed to be nondegenerate and a singlet) satisfies a Schrödinger type equation with a local potential function. In momentum space the Schrödinger equation becomes: (i) 1/2 (P2+P20)? +?v(Q-P)?(Q)(dQ)=0 with (ii) v(q)=[1/(2?)2]?eiq?r V(dr) and q=Q-P,P0=(-2E)1/2 and ? is the momentum eigenfunction. The potential function V depends on the many-electron eigenfunction and thus provides no means for numerical calculation. However, less direct methods are available for characterizing a function by investigating its singular points. This is not readily applicable to the potential function V but is well suited to the study of the amplitude function v(q). The location and nature of singular points in the complex q plane have been obtained. The positions of the singular points are related by simple formulas to the ionization potentials of the neutral molecule and the positive ion and, except by accident, are branch points. Convergent series expansions in suitable variables are developed and the potential function is recovered by inverting the Fourier integral (ii). V for an atom is expressed as the sum of a Coulomb term, a series of Yukawa potentials e-?ir/r, and a series of functions L/r with L=??m=0(m+1)(-?ir/2)m /?2(m/2+1). The singular points of v(q) occur in pairs, ±i?i, on the imaginary axis. The constants ?i are related to ionization potentials which can be determined by experiment. Singular points have also been located for the one-electron model proposed by Slater. A similar expansion for an atom gives a Coulomb term, a sum of Yukawa potentials, and a series of functions L(?ir)/r. The numerical study of Garvey and Green used one Coulomb and three Yukawa potentials and obtained good agreement in energy calculations. The present research suggests that their potential function be supplemented by the function L(?ir)/r.

Lassettre, Edwin N.

1985-08-01

146

Realistic Yukawa Structures from Orientifold Compactifications

We perform a systematic analysis of globally consistent D-brane quivers which realize the MSSM, and analyze them with respect to their Yukawa couplings. Often, desired couplings are perturbatively forbidden due to the presence of global U(1) symmetries. We investigate the conditions under which D-brane instantons will induce these missing couplings without generating other phenomenological drawbacks, such as R-parity violating couplings or a mu-term which is too large. Furthermore, we systematically analyze which quivers allow for a mechanism that can account for the small neutrino masses and other experimentally observed hierarchies. We show that only a small fraction of the globally consistent D-brane quivers exhibits phenomenology compatible with experimental observations.

Mirjam Cveti?; James Halverson; Robert Richter

2009-09-24

147

This is a response to the comment we received on our recent paper "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit." In that paper, we introduced a computational algorithm that is appropriate for solving stiff initial value problems, and which we applied to the one-dimensional time-independent Schrödinger equation with a soft Coulomb potential. We solved for the eigenpairs using a shooting method and hence turned it into an initial value problem. In particular, we examined the behavior of the eigenpairs as the softening parameter approached zero (hard Coulomb limit). The commenters question the existence of the ground state of the hard Coulomb potential, which we inferred by extrapolation of the softening parameter to zero. A key distinction between the commenters' approach and ours is that they consider only the half-line while we considered the entire x axis. Based on mathematical considerations, the commenters consider only a vanishing solution function at the origin, and they question our conclusion that the ground state of the hard Coulomb potential exists. The ground state we inferred resembles a ?(x), and hence it cannot even be addressed based on their argument. For the excited states, there is agreement with the fact that the particle is always excluded from the origin. Our discussion with regard to the symmetry of the excited states is an extrapolation of the soft Coulomb case and is further explained herein. PMID:25768645

Gebremedhin, Daniel H; Weatherford, Charles A

2015-02-01

148

NASA Astrophysics Data System (ADS)

This is a response to the comment we received on our recent paper "Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit." In that paper, we introduced a computational algorithm that is appropriate for solving stiff initial value problems, and which we applied to the one-dimensional time-independent Schrödinger equation with a soft Coulomb potential. We solved for the eigenpairs using a shooting method and hence turned it into an initial value problem. In particular, we examined the behavior of the eigenpairs as the softening parameter approached zero (hard Coulomb limit). The commenters question the existence of the ground state of the hard Coulomb potential, which we inferred by extrapolation of the softening parameter to zero. A key distinction between the commenters' approach and ours is that they consider only the half-line while we considered the entire x axis. Based on mathematical considerations, the commenters consider only a vanishing solution function at the origin, and they question our conclusion that the ground state of the hard Coulomb potential exists. The ground state we inferred resembles a ? (x ) , and hence it cannot even be addressed based on their argument. For the excited states, there is agreement with the fact that the particle is always excluded from the origin. Our discussion with regard to the symmetry of the excited states is an extrapolation of the soft Coulomb case and is further explained herein.

Gebremedhin, Daniel H.; Weatherford, Charles A.

2015-02-01

149

NASA Astrophysics Data System (ADS)

An efficient algorithm is presented to find the Blum-Høye mean spherical approximation (MSA) solution for mixtures of hard-core fluids interacting through multi-screened Coulomb plus power series (multi-SCPPS) potentials. The solution for hard-sphere mixtures is used as an initial estimate of the variables. From this initial estimate only a few Newton-Raphson iterations are required to reach the final solution. The algorithm is also able to reflect correctly their molecular characteristics into the appropriate macroscopic behaviour. All MSA thermodynamic properties are presented analytically. Our analysis will be applicable to a large variety of fluid mixtures because any smooth, realistic isotropic potential can be well reproduced by the multi-SCPPS closure with arbitrary accuracy. Demonstrations of the power of the algorithm are made for two binary-component systems of Lennard-Jones particles. One is composed of particles with nearly the same sizes, while the other mixture with widely different sizes. We have studied their thermodynamic stabilities based on the compressibility and the isotherms of virial and energy equations of state, and further from microscopic viewpoints in connection with radial distribution functions. The present method is able to detect vapour-liquid transitions and perhaps liquid-glass transitions. The multi-SCPPS closure includes the multi-Yukawa closure as a special case.

Yasutomi, M.

2003-12-01

150

The contribution of different modes of the Coulomb field to decoherence and to the dynamical breakdown of the time reversal invariance is calculated in the one-loop approximation for nonrelativistic electron gas. The dominant contribution was found to come from the usual collective modes in the plasma, namely, the zero-sound and the plasmon oscillations. The length scale of the quantum-classical transition is found to be close to the Thomas-Fermi screening length. It is argued that the extension of these modes to the whole Fock space yields optimal pointer states.

Polonyi, J. [Theoretical Physics Laboratory, Louis Pasteur University, Strasbourg (France)

2008-06-15

151

Ion sphere model for Yukawa systems (dusty plasmas)

NASA Astrophysics Data System (ADS)

Application of the ion sphere model (ISM), well known in the context of the one-component-plasma, to estimate thermodynamic properties of model Yukawa systems is discussed. It is shown that the ISM approximation provides fairly good estimate of the internal energy of the strongly coupled Yukawa systems, in both fluid and solid phases. Simple expressions for the excess pressure and isothermal compressibility are derived, which can be particularly useful in connection to wave phenomena in strongly coupled dusty plasmas. It is also shown that in the regime of strong screening a simple consideration of neighboring particles interactions can be sufficient to obtain quite accurate estimates of thermodynamic properties of Yukawa systems.

Khrapak, S. A.; Khrapak, A. G.; Ivlev, A. V.; Thomas, H. M.

2014-12-01

152

Ion sphere model for Yukawa systems (dusty plasmas)

Application of the ion sphere model (ISM), well known in the context of the one-component-plasma, to estimate thermodynamic properties of model Yukawa systems is discussed. It is shown that the ISM approximation provides fairly good estimate of the internal energy of the strongly coupled Yukawa systems, in both fluid and solid phases. Simple expressions for the excess pressure and isothermal compressibility are derived, which can be particularly useful in connection to wave phenomena in strongly coupled dusty plasmas. It is also shown that in the regime of strong screening a simple consideration of neighboring particles interactions can be sufficient to obtain quite accurate estimates of thermodynamic properties of Yukawa systems.

S. A. Khrapak; A. G. Khrapak; A. V. Ivlev; H. M. Thomas

2014-12-12

153

Interplay between Yukawa and Tomonaga in the Birth of Mesons

Light is shed on the early stage in the birth of Yukawa's meson theory, particularly on the interplay between Yukawa and Tomonaga in 1933. The discovery of the muon by Nishina' group in 1937 is also reviewed. It is pointed out that Heisenberg's attempt to explain the nuclear force in terms of the Heitler-London scheme, overcome by Yukawa and abandoned since then, is now being revived as a mechanism for a super strong nuclear force caused by a migrating real Kbar meson.

Toshimitsu Yamazaki

2008-03-19

154

The relativistic hydrogen atoms in an Euclidean space-time of arbitrary number of space dimensions ($D$) plus one time dimension is revisited. In particular, numerical solutions of the radial Dirac equation for a generalized Coulombian potential proportional to $1/r^{(D-2)}$ are investigated. It is argued that one could not find any physical solution for $D\\geq 4$.

F. Caruso; J. Martins; L. D. Perlingeiro; V. Oguri

2014-11-18

155

Probing Minicharged Particles with Tests of Coulomb's Law

NASA Astrophysics Data System (ADS)

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

Jaeckel, Joerg

2009-08-01

156

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

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

1998-10-22

157

The Effects of Static Coulomb Stress Change on Southern California Earthquake Forecasting

NASA Astrophysics Data System (ADS)

I investigate how inclusion of static Coulomb stress changes, caused by tectonic loading and previous seismicity, contributes to the effectiveness and reliability of prospective earthquake forecasts. Several studies have shown that positive static Coulomb stress changes are associated with increased seismicity, relative to stress shadows. However, it is difficult to avoid bias when the learning and testing intervals are chosen retrospectively. I hypothesize that earthquake forecasts based on static Coulomb stress fields may improve upon existing earthquake forecasts based on historical seismicity. Within southern California, I have confirmed the aforementioned relationship between earthquake location and Coulomb stress change, but found no identifiable triggering threshold based on static Coulomb stress history at individual earthquake locations. I have also converted static Coulomb stress changes into spatially-varying earthquake rates by optimizing an index function and calculating probabilities of cells containing at least one earthquake based on Coulomb stress ranges. Inclusion of Coulomb stress effects gives an improvement in earthquake forecasts that is significant with 95% confidence, compared to smoothed seismicity null forecasts. Because of large uncertainties in Coulomb stress calculations near faults (and aftershock distributions), I combine static Coulomb stress and smoothed seismicity into a hybrid earthquake forecast. Evaluating such forecasts against those in which only Coulomb stress or smoothed seismicity determines earthquake rates indicates that Coulomb stress is more effective in the far field, whereas statistical seismology outperforms Coulomb stress near faults. Additionally, I test effects of receiver plane orientation, stress type (normal and shear components), and declustering receiver earthquakes. While static Coulomb stress shows significant potential in a prospective earthquake forecast, simplifying assumptions compromise its effectiveness. For example, we assume that crustal material within the study region is isotropic and homogeneous and purely elastic, and that pore fluid pressure variations do not significantly affect the static Coulomb stress field. Such assumptions require further research in order to detect direct earthquake triggering mechanisms.

Strader, Anne Elizabeth

158

Interfacial and wetting properties of a binary point Yukawa fluid

We investigate the interfacial phase behavior of a binary fluid mixture composed of repulsive point Yukawa particles. Using a simple approximation for the Helmholtz free energy functional, which yields the random phase approximation (RPA) for the pair direct correlation functions, we calculate the equilibrium fluid density profiles of the two species of particles adsorbed at a planar wall. We show that for a particular choice (repulsive exponential) of the wall potentials and the fluid pair-potential parameters, the Euler-Lagrange equations for the equilibrium fluid density profiles may be transformed into a single ordinary differential equation and the profiles obtained by a simple quadrature. For certain other choices of the fluid pair-potential parameters fluid-fluid phase separation of the bulk fluid is observed. We find that when such a mixture is exposed to a planar hard-wall, the fluid exhibits complete wetting on the species 2 poor side of the binodal, i.e. we observe a thick film of fluid rich in species 2 adsorbed at the hard-wall. The thickness of the wetting film grows logarithmically with the concentration difference between the fluid state-point and the binodal and is proportional to the bulk correlation length of the intruding (wetting) fluid phase. However, for state points on the binodal that are further from the critical point, we find there is no thick wetting film. We determine the accompanying line of first-order (pre-wetting) surface phase transitions which separate a thin and thick adsorbed film. We show that for some other choices of repulsive wall potentials the pre-wetting line is still present, but its location and extent in the phase diagram is strongly dependent on the wall-fluid interaction parameters.

Paul Hopkins; Andrew J. Archer; Robert Evans

2008-10-29

159

Coulomb crystallization of highly charged ions

NASA Astrophysics Data System (ADS)

Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically 40Ar13+) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be+ ions. We also demonstrate cooling of a single Ar13+ ion by a single Be+ ion—the prerequisite for quantum logic spectroscopy with a potential 10?19 accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.

Schmöger, L.; Versolato, O. O.; Schwarz, M.; Kohnen, M.; Windberger, A.; Piest, B.; Feuchtenbeiner, S.; Pedregosa-Gutierrez, J.; Leopold, T.; Micke, P.; Hansen, A. K.; Baumann, T. M.; Drewsen, M.; Ullrich, J.; Schmidt, P. O.; López-Urrutia, J. R. Crespo

2015-03-01

160

Coulomb crystallization of highly charged ions.

Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy. PMID:25766230

Schmöger, L; Versolato, O O; Schwarz, M; Kohnen, M; Windberger, A; Piest, B; Feuchtenbeiner, S; Pedregosa-Gutierrez, J; Leopold, T; Micke, P; Hansen, A K; Baumann, T M; Drewsen, M; Ullrich, J; Schmidt, P O; López-Urrutia, J R Crespo

2015-03-13

161

Confinement made simple in the Coulomb gauge

NASA Astrophysics Data System (ADS)

In Gribov's scenario in Coulomb gauge, confinement of color charge is due to a long-range instantaneous color-Coulomb potential V( R). This may be determined numerically from the instantaneous part of the gluon propagator D44,inst = V( R)?( t). Confinement of gluons is reflected in the vanishing at k = 0 of the equal-time three-dimensionally transverse would-be physical gluon propagator Dtr( k). We present exact analytic results on D44 and Dtr (which have also been investigated numerically, A. Cucchieri, T. Mendes, and D. Zwanziger, this conference), in particular the vanishing of Dtr( k) at k = 0, and the determination of the running coupling constant from x0g2( k) = k2D44,inst, where x0 = 12 N/(11 N - 2 N f).

Cucchieri, Attilio; Zwanziger, Daniel

2002-03-01

162

Confinement made simple in the Coulomb gauge

NASA Astrophysics Data System (ADS)

In Gribov's scenario in Coulomb gauge, confinement of color charge is due to a long-range instantaneous color-Coulomb potential V(R). This may be determined numerically from the instantaneous part of the gluon propagator D44,inst = V(R)?(t). Confinement of gluons is reflected in the vanishing at k = 0 of the equal-time three-dimensionally transverse would-be physical gluon propagator Dtr(k). We present exact analytic results on D44 and Dtr (which have also been investigated numerically, A. Cucchieri, T. Mendes, and D. Zwanziger, this conference), in particular the vanishing of Dtr(k) at k = 0, and the determination of the running coupling constant from x0g2(k) = k2 D44,inst, where x0 = 12N/(11N - 2Nf).

Cucchieri, Attilio; Zwanziger, Daniel

163

NASA Astrophysics Data System (ADS)

The radioactive isotope 107In was studied using sub-barrier Coulomb excitation at the REX-ISOLDE facility at CERN. Two ? rays were observed during the experiment, corresponding to the low-lying 11/2+ and 3/2- states. The reduced transition probability of the 11/2+ state was determined with the semiclassical Coulomb excitation code gosia2. The result is discussed in comparison to large-scale shell-model calculations, previous unified-model calculations, and earlier Coulomb excitation measurements in the odd-mass In isotopes.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Heyde, K.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2013-01-01

164

Casimir forces in a Plasma: Possible Connections to Yukawa Potentials

We present theoretical and numerical results for the screened Casimir effect between perfect metal surfaces in a plasma. We show how the Casimir effect in an electron-positron plasma can provide an important contribution to nuclear interactions. Our results suggest that there is a connection between Casimir forces and nucleon forces mediated by mesons. Correct nuclear energies and meson masses appear to emerge naturally from the screened Casimir-Lifshitz effect.

Barry W. Ninham; Mathias Boström; Clas Persson; Iver Brevik; Stefan Y. Buhmann; Bo E. Sernelius

2014-09-03

165

Classical Coulomb systems: Screening and correlations revisited

From the laws of macroscopic electrostatics of conductors (in particular, the existence of screening), taken as given, one can deduce universal properties for the thermal fluctuations in a classical Coulomb system at equilibrium. The universality is especially apparent in the long-range correlations of the electrical potentials and fields. The charge fluctuations are derived from the field fluctuations. This is a convenient way to study the surface charge fluctuations on a conductor with boundaries. Explicit results are given for simple geometries. The potentials and the fields have Gaussian fluctuations, except for a short-distance cutoff.

Jancovici, B. [Universite de Paris-Sud, Orsay (France)

1995-07-01

166

Coulomb Friction Driving Brownian Motors

NASA Astrophysics Data System (ADS)

We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced.

Alessandro, Manacorda; Andrea, Puglisi; Alessandro, Sarracino

2014-10-01

167

Coulomb's law corrections and fermion field localization in a tachyonic de Sitter thick braneworld

In this work, following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the localization of fermion fields in this model. In order to achieve this aim we consider the Yukawa interaction term between the fermions and the tachyonic condensate scalar field MF(T)barPsiPsi in the action and analyze four different cases corresponding to distinct tachyonic functions F(T(w)). The only condition that this function must satisfy in order to yield 4D chiral fermions upon dimensional reduction is to be odd in the extra dimension w. These functions lead to a different structure of the respective fermionic mass spectrum. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of the Yukawa interaction among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb's law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb's law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb's law for a more general case, on a thick brane scenario, for which we can do estimates consistent with brane phenomenology, i.e. we found that the predicted corrections to the Coulomb law in our model, which are well bounded by the observed experimental photon mass, is far beyond its upper bound, positively testing the viability of our tachyonic braneworld.

R. Cartas-Fuentevilla; Alberto Escalante; Gabriel Germán; Alfredo Herrera-Aguilar; Refugio Rigel Mora-Luna

2014-12-30

168

Vacuum polarization by a Coulomb center and a strong magnetic field. Uehling's correction

NASA Astrophysics Data System (ADS)

The problem of vacuum polarization by the Coulomb field of the nucleus and a constant homogeneous magnetic field is examined by the “proper time” method. For this the magnetic field is exactly taken into account, and the Coulomb field is considered by perturbation theory. In the case of a magnetic field equal to zero, we calculate the change of the Coulomb potential which results from vacuum polarization. The result obtained coincides with the well-known Uehling correction.

Khalilov, V. R.; Maslov, I. N.

1986-09-01

169

Quasi-Coulomb series in a two-dimensional three-body system

We show that the bound states in a three-body system display a Coulomb series with a Gaussian cut-off provided: (i) the system consists of a light particle and two heavy bosonic ones, (ii) the heavy-light short-range potential has a resonance in the $p$-wave scattering amplitude, and (iii) all three particles move in two space dimensions. For a decreasing mass ratio this quasi-Coulomb series merges into a pure Coulombic one.

Maxim A. Efremov; Wolfgang P. Schleich

2014-07-12

170

Test of the Stokes-Einstein relation in a two-dimensional Yukawa liquid

The Stokes-Einstein relation, relating the diffusion and viscosity coefficients D and eta, is tested in two dimensions. An equilibrium molecular-dynamics simulation was used with a Yukawa pair potential. Regimes are identified where motion is diffusive and D is meaningful. The Stokes-Einstein relation, D ~ kT, was found to be violated near the disordering transition; under these conditions collective particle motion exhibits dynamical heterogeneity. At slightly higher temperatures, however, the Stokes-Einstein relation is valid. These results may be testable in strongly-coupled dusty plasma experiments.

Bin Liu; J. Goree

2005-11-08

171

Quark Yukawa pattern from spontaneous breaking of flavour $SU(3)^3$

A $SU(3)_Q \\times SU(3)_u \\times SU(3)_d$ invariant scalar potential breaking spontaneously the quark flavour symmetry can explain the standard model flavour puzzle. The approximate alignment in flavour space of the vacuum expectation values of the up and down `Yukawa fields' results as a dynamical effect. The observed quark mixing angles, the weak CP violating phase, and hierarchical quark masses can be all reproduced at the cost of introducing additional (auxiliary) scalar multiplets, but without the need of introducing hierarchical parameters.

Nardi, Enrico

2015-01-01

172

Quark Yukawa pattern from spontaneous breaking of flavour $SU(3)^3$

A $SU(3)_Q \\times SU(3)_u \\times SU(3)_d$ invariant scalar potential breaking spontaneously the quark flavour symmetry can explain the standard model flavour puzzle. The approximate alignment in flavour space of the vacuum expectation values of the up and down `Yukawa fields' results as a dynamical effect. The observed quark mixing angles, the weak CP violating phase, and hierarchical quark masses can be all reproduced at the cost of introducing additional (auxiliary) scalar multiplets, but without the need of introducing hierarchical parameters.

Enrico Nardi

2015-03-04

173

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

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

174

Yukawa Textures And Horava-Witten M-Theory

The general structure of the matter Kahler metric in the $\\kappa^{2/3}$ expansion of Horava-Witten M-theory with nonstandard embeddings is examined. It is shown that phenomenological models based on this structure can lead to Yukawa and V$_{\\rm CKM}$ hierarchies (consistent with all data) without introducing ad hoc small parameters if the 5-branes lie near the distant orbifold plane and the instanton charges of the physical plane vanish. M-theory thus offers an alternate way of describing these hierarchies, different from the conventional models of Yukawa textures.

R. Arnowitt; B. Dutta

2000-08-30

175

(mercury.yukawa.kyoto-u.ac.jp)ssh Permission denied (publickey).

SSH Q&A (mercury.yukawa.kyoto-u.ac.jp)ssh Permission denied (publickey). (1) ID ID ID (2) ssh -i () ssh -i $HOME/.ssh/id_yitp_rsa (UID)@mercury.yukawa.kyoto-u.ac.jp (3) (1)(2) Permission denied support@yukawa.kyoto-u.ac.jp (mercury

Shimizu, Akira

176

Fluid approach to evaluate sound velocity in Yukawa systems and complex plasmas

NASA Astrophysics Data System (ADS)

The conventional fluid description of multicomponent plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasilocalized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strength in the fluid regime but exhibits a pronounced decrease with the increase of the screening strength. The limitations of the present approach in applications to real complex plasmas are briefly discussed.

Khrapak, Sergey A.; Thomas, Hubertus M.

2015-03-01

177

Fluid approach to evaluate sound velocity in Yukawa systems (complex plasmas)

The conventional fluid description of multi-component plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasi-localized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strength in the fluid regime, but exhibits a pronounced decrease with the increase of the screening strength. The limitations of the present approach in applications to real complex plasmas are briefly discussed.

Sergey Khrapak; Hubertus Thomas

2015-03-02

178

Structure of multi-component\\/multi-Yukawa mixtures

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

L. Blum; M. Arias

2006-01-01

179

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

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

Yasutaka Tanikawa

1981-01-01

180

Two-dimensional Coulomb systems on a surface of constant negative curvature

We study the equilibrium statistical mechanics of classical two-dimensional Coulomb systems living on a pseudosphere (an infinite surface of constant negative curvature). The Coulomb potential created by one point charge exists and goes to zero at infinity. The pressure can be expanded as a series in integer powers of the density (the virial expansion). The correlation functions have a thermodynamic

B. Jancovici; G. Tellez

1998-01-01

181

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

182

Coulomb explosion sputtering of selectively oxidized Si

NASA Astrophysics Data System (ADS)

We have studied the sputtering of a unique system comprising of coexisting silicon and silicon oxide surfaces due to the impact of multiply charged Arq + 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 Arq + 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.

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

2010-05-01

183

We study the coupling parameter dependence of the Higgs boson mass in a chirally invariant lattice Higgs-Yukawa model emulating the same Yukawa coupling structure as in the Higgs-fermion sector of the Standard Model. Eventually, the aim is to establish non-perturbative upper and lower Higgs boson mass bounds derived from first principles, in particular not relying on vacuum stability considerations for the latter case. Here, we present our lattice results for the lower Higgs boson mass bound at several values of the cutoff and compare them to corresponding analytical calculations based on the effective potential as obtained from lattice perturbation theory. Furthermore, we give a brief outlook towards the calculation of the upper Higgs boson mass bound.

P. Gerhold; K. Jansen

2009-02-24

184

Phase structure and Higgs boson mass in a Higgs-Yukawa model with a dimension-6 operator

We investigate the impact of a $\\lambda_6 \\varphi^6$ term included in a chirally invariant lattice Higgs-Yukawa model. Such a term could emerge from BSM physics at some larger energy scale. We map out the phase structure of the Higgs-Yukawa model with positive $\\lambda_6$ and negative quartic self coupling of the scalar fields. To this end, we evaluate the constraint effective potential in lattice perturbation theory and also determine the magnetization of the model via numerical simulations which allow us to reach also non-perturbative values of the couplings. As a result, we find a complex phase structure with first and second order phase transitions identified through the magnetization. Further we analyze the effect of such a $\\varphi^6$ term on the lower Higgs boson mass bound to see, whether the standard model lower mass bound can be altered.

David Y. -J. Chu; Karl Jansen; Bastian Knippschild; C. -J. David Lin; Kei-Ichi Nagai; Attila Nagy

2015-01-01

185

Sputtering due to Coulomb explosion in highly charged ion bombardment

Sputtering processes of silicon in the bombardment of highly charged ions (HCIs) are studied using molecular dynamics simulation. Assuming the potential energy of the HCI transferred to target is stored as the electrostatic energy of Si atoms ionized by the HCI, the Si ions up to 375 are embedded on a Si(100) surface as an initial condition, resulting in Coulomb

M. Terasawa; Z. A. Insepov; T. Sekioka; A. A. Valuev; T. Mitamura

2003-01-01

186

One-dimensional Coulomb problem in Dirac materials

We investigate the one-dimensional Coulomb potential with application to a class of quasirelativistic systems, so-called Dirac-Weyl materials, described by matrix Hamiltonians. We obtain the exact solution of the shifted and truncated Coulomb problems, with the wavefunctions expressed in terms of special functions (namely Whittaker functions), whilst the energy spectrum must be determined via solutions to transcendental equations. Most notably, there are critical bandgaps below which certain low-lying quantum states are missing in a manifestation of atomic collapse.

C. A. Downing; M. E. Portnoi

2014-11-21

187

Measurements of Coulomb blockade with a noninvasive voltage probe

NASA Astrophysics Data System (ADS)

We have investigated the behavior of a laterally confined quantum dot in close proximity to a one-dimensional channel in a separate electrical circuit. When this channel is biased in the tunneling regime the resistance is very sensitive to electric fields, and therefore is sensitive to the potential variations on the dot when it is showing Coulomb blockade oscillations. This effect can be calibrated directly, allowing the Coulomb charging energy to be measured. We also found the activation energy of transport through the dot is much lower than expected.

Field, M.; Smith, C. G.; Pepper, M.; Ritchie, D. A.; Frost, J. E. F.; Jones, G. A. C.; Hasko, D. G.

1993-03-01

188

Dynamical rigidity of stochastic Coulomb systems in infinite-dimensions

This paper is based on the talk in "Probability Symposium" at Research Institute of Mathematical Sciences (Kyoto University) on 2013/12/18, and gives an announcement of some parts of the results in [1,8,10,11]. We show two instances of dynamical rigidity of Ginibre interacting Brownian motion in infinite dimensions. This stochastic dynamics is given by the infinite-dimensional stochastic differential equation describing infinite-many Brownian particles in the plane interacting through two-dimensional Coulomb potential. The first dynamical rigidity is that the Ginibre interacting Brownian motion is a unique, strong solution of two different infinite dimensional stochastic differential equations. The second shows that the tagged particles of Ginibre interacting Brownian motion are sub diffusive. We also propose the notion of "Coulomb random point fields" and the associated "Coulomb interacting Brownian motions".

Hirofumi Osada

2014-05-23

189

Coulomb crystal mass spectrometry in a digital ion trap

We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radiofrequency waveform is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields subsequently applied to the trap electrodes for ion ejection. Excellent detection efficiency is demonstrated for Ca+ and CaF+ ions from bi-component Ca+/CaF+ Coulomb crystals prepared by reaction of Ca+ with CH3F. A quantitative linear relationship is observed between ion number and the corresponding integrated TOF peak, independent of the ionic species. The technique is applicable to a diverse range of multi-component Coulomb crystals - demonstrated here for Ca+/NH3+/NH4+ and Ca+/CaOH+/CaOD+ crystals - and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.

Deb, Nabanita; Smith, Alexander D; Keller, Matthias; Rennick, Christopher J; Heazlewood, Brianna R; Softley, Timothy P

2015-01-01

190

Inflation, leptogenesis, and Yukawa quasiunification within a supersymmetric left-right model

NASA Astrophysics Data System (ADS)

A simple extension of the minimal left-right symmetric supersymmetric grand unified theory model is constructed by adding two pairs of superfields. This naturally violates the partial Yukawa unification predicted by the minimal model. After including supergravity corrections, we find that this extended model naturally supports hilltop F-term hybrid inflation along its trivial inflationary path with only a very mild tuning of the initial conditions. With a convenient choice of signs of the terms in the Kähler potential, we can reconcile the inflationary scale with the supersymmetric grand unified theory scale. All the current data on the inflationary observables are readily reproduced. Inflation is followed by nonthermal leptogenesis via the decay of the right-handed neutrinos emerging from the decay of the inflaton, and any possible washout of the lepton asymmetry is avoided thanks to the violation of partial Yukawa unification. The extra superfields also assist us in reducing the reheat temperature so as to satisfy the gravitino constraint. The observed baryon asymmetry of the universe is naturally reproduced consistently with the neutrino oscillation parameters.

Armillis, R.; Lazarides, G.; Pallis, C.

2014-03-01

191

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

192

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

193

Yukawa model on a lattice in the quenched approximation

NASA Astrophysics Data System (ADS)

The Yukawa model in the quenched approximation is expressed as a disordered statistical mechanics model on a four-dimensional Euclidean lattice. We study this model, giving particular attention to the singularities of the Dirac operator in the phase diagram. A careful analysis of a particular limiting case shows that finite volume effects can be huge and questions the quenched approximation. This is confirmed by numerical simulation performed in this limiting case and without the quenched approximation.

de Soto, Feliciano; Anglès d'Auriac, Jean-Christian

2012-04-01

194

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

We analyze some consequences of grand unification of the third-generation Yukawa couplings, in the context of the minimal supersymmetric standard model. We address two issues: the prediction of the top quark mass, and the generation of the top-bottom mass hierarchy through a hierarchy of Higgs vacuum expectation values. The top mass is strongly dependent on a certain ratio of superpartner masses. And the VEV hierarchy always entails some tuning of the GUT-scale parameters. We study the RG equations and their semi-analytic solutions, which exhibit several interesting features, such as a focusing effect for a large Yukawa coupling in the limit of certain symmetries and a correlation between the A terms (which contribute to b {yields} s{gamma}) and the gaugino masses. This study shows that non-universal soft-SUSY-breaking masses are favored (in particular for splitting the Higgs-doublets via D-terms and for allowing more natural scenarios of symmetry breaking), and hints at features desired in Yukawa-unified models. Several phenomenological implications are also revealed.

Rattazzi, R. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy; Sarid, U. [Stanford Univ., Stanford, CA (United States). Dept. of Physics; Hall, L.J. [Lawrence Berkeley Lab., CA (United States)

1993-05-01

195

Yukawa and Tri-scalar Processes in Electroweak Baryogenesis

We derive the contributions to the quantum transport equations for electroweak baryogenesis due to decays and inverse decays induced by tri-scalar and Yukawa interactions. In the Minimal Supersymmetric Standard Model (MSSM), these contributions give rise to couplings between Higgs and fermion supermultiplet densities, thereby communicating the effects of CP-violation in the Higgs sector to the baryon sector. We show that the decay and inverse decay-induced contributions that arise at zeroth order in the strong coupling, \\alpha_s, can be substantially larger than the O(\\alpha_s) terms that are generated by scattering processes and that are usually assumed to dominate. We revisit the often-used approximation of fast Yukawa-induced processes and show that for realistic parameter choices it is not justified. We solve the resulting quantum transport equations numerically with special attention on the impact of Yukawa rates and study the dependence of the baryon-to-entropy ratio Y_B on MSSM parameters.

Vincenzo Cirigliano; Christopher Lee; Michael J. Ramsey-Musolf; Sean Tulin

2006-04-03

196

NASA Astrophysics Data System (ADS)

Coulomb energies of the ^18Ne mirrors of the levels of ^18O vary considerably from state to state, an effect understood as arising from their different configurations. All the low-lying positive-parity states in these nuclei can be described in terms of two nucleons coupled to an ^16O core plus a collective component (most probably four-particle two-hole (4p-2h)). We have computed Coulomb energies using one such formulation(Lawson, Serduke and Fortune, Phys. Rev. C 14), 1245 (1976).. Two-particle energies arise from coupling a neutron to single-particle states of ^17O, and a proton to the mirror states of ^17F. For the 4p-2h component, we use the ^14O-^14C mass difference, plus a ph Coulomb term(Sherr and Bertsch, Phys. Rev. C 12), 1671 (1975).. Agreement is perhaps slightly better than another such attempt(Nero, Adelberger and Dietrich, Phys. Rev. C 24), 1864 (1981). using wave functions from Benson and Flowers.

Sherr, R.; Fortune, H. T.

1998-10-01

197

Coulomb-corrected propagation equation of femtosecond laser in field-ionized medium

NASA Astrophysics Data System (ADS)

In most strong-field atomic processes, the role of Coulomb potential is dismissively ignored because of the application of strong field approximation reasonably. By introducing it into the propagation equation of laser pulse in the field-ionizing media, we demonstrate that the noteworthy Coulomb effects have the ionized electronic density decreased due to the attraction by the nuclear cores and lead a new energy dissipation mechanism to rise due to the collision of the accelerated electrons by laser field with the Coulomb potential of their parent ions, i.e., the bremsstrahlung process.

Yu, Cheng-Xin; Liu, Shi-Bing; Shu, Xiao-Fang; Song, Hai-Ying; Yang, Zhi

2013-04-01

198

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

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 k(critical), and a positive dispersion when k>k(critical). The negative group velocity of the wave for k

Qiao, K; Hyde, T W

2003-10-01

199

Solution of two-body relativistic bound state equations with confining plus Coulomb interactions

NASA Technical Reports Server (NTRS)

Studies of meson spectroscopy have often employed a nonrelativistic Coulomb plus Linear Confining potential in position space. However, because the quarks in mesons move at an appreciable fraction of the speed of light, it is necessary to use a relativistic treatment of the bound state problem. Such a treatment is most easily carried out in momentum space. However, the position space Linear and Coulomb potentials lead to singular kernels in momentum space. Using a subtraction procedure we show how to remove these singularities exactly and thereby solve the Schroedinger equation in momentum space for all partial waves. Furthermore, we generalize the Linear and Coulomb potentials to relativistic kernels in four dimensional momentum space. Again we use a subtraction procedure to remove the relativistic singularities exactly for all partial waves. This enables us to solve three dimensional reductions of the Bethe-Salpeter equation. We solve six such equations for Coulomb plus Confining interactions for all partial waves.

Maung, Khin Maung; Kahana, David E.; Norbury, John W.

1992-01-01

200

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

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 Fe{sup 25+} ion, as an example.

Xie, L. Y. [Key Laboratory of Atomic and Molecular Physics and Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009-26, Beijing 100088 (China); Wang, J. G. [Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009-26, Beijing 100088 (China); Janev, R. K. [Macedonian Academy of Sciences and Arts, P.O. Box, 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of)

2014-06-15

201

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

202

On the defect induced gauge and Yukawa fields in graphene

We consider lattice deformations (both continuous and topological) in the hexagonal lattice Hubbard model in the tight binding approximation to graphene, involving operators with the range up to next-to-neighbor. In the low energy limit, we find that these deformations give rise to couplings of the electronic Dirac field to an external scalar (Yukawa) and gauge fields. The fields are expressed in terms of original defects. As a by-product we establish that the next-to-nearest order is the minimal range of deformations which produces the complete gauge and scalar fields. We consider an example of Stone--Wales defect, and find the associated gauge field.

Corneliu Sochichiu

2011-03-08

203

Memorial Archival Libraries of Yukawa, Tomonaga, and Sakata

NASA Astrophysics Data System (ADS)

Brief history of the memorial archival libraries of Hideki Yukawa, Sin-itiro Tomonaga, and Shoichi Sakata, the great pioneers of nuclear and particle physics in Japan, is described. A recent project of maintaining the archival libraries is going on and the catalog databases of their documents are now almost ready for public access using Internet. In the project it is tried to make use of recent knowledge and technologies of archival science and the databases, and thus the documents themselves, willbe made accessible easier than before and may attract the interest of much broader range of audiences. Some interesting documents are picked up for demonstration.

Takaiwa, Yoshinobu; Bando, Masako; Gotoh, Haruyoshi; Hayakawa, Hisao; Hirata, Kohji; Ito, Kazuyuki; Ito, Kenji; Kanaya, Kazuyuki; Konagaya, Daisuke; Konuma, Michiji; Kugo, Taichiro; Namba, Chusei; Nishitani, Tadashi; Tanabashi, Masaharu; Tanaka, Kio; Tanaka, Sho; Ukegawa, Fumihiko; Yoshikawa, Tadashi

204

Diffusion coefficient of three-dimensional Yukawa liquids

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

205

Employing numerical diagonalization, we study the optical properties of an electron in a monolayer-graphene magnetic dot bound to an off-center negatively charged Coulomb impurity based on the massless Dirac-Weyl model. Numerical results show that, since the electron-hole symmetry is broken by the Coulomb potential, the optical absorption spectra of the magnetic dot in the presence of a Coulomb impurity are different between the electron states and the hole states. Effects of both the magnetic field and the dot size on the absorption coefficient are presented as functions of the incident photon energies.

Lee, C. M., E-mail: mesimon-hk@yahoo.com.hk, E-mail: apkschan@cityu.edu.hk; Chan, K. S., E-mail: mesimon-hk@yahoo.com.hk, E-mail: apkschan@cityu.edu.hk [Department of Physics and Materials Science and Center for Functional Photonics, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Shenzhen Research Institute, City University of Hong Kong, Shenzhen (China)

2014-07-28

206

Unified analysis of multipole and finite-mass corrections in long-range Coulombic interactions

NASA Technical Reports Server (NTRS)

Simple expressions are derived for all multipole nonadiabatic and finite-nuclear-mass corrections to the long-range effective potential due to two-Coulomb-photon exchange at threshold energy, and also for first-order energy corrections for the scattering between a spinles point charged particle and a spinless Coulombic complex and between two spinless Coulombic complexes. All these corrections are treated on equal footing, and the results are expressed, respectively, in terms of single-center and London-analog two-center atomic-multipole spectral sums.

Au, C. K.

1988-01-01

207

Gravity Dual Corrections to the Heavy Quark Potential at Finite-Temperature

We apply gauge/gravity duality to compute $1/N^2_c$ corrections to the heavy quark potentials of a quark--anti-quark pair ($Q\\bar Q$) and of a quark--quark pair ($QQ$) immersed into the strongly coupled N = 4 SYM plasma. On the gravity side these corrections come from the exchanges of supergravity modes between two string worldsheets stretching from the UV boundary of AdS space to the black hole horizon in the bulk and smeared over $S^5$. We find that the contributions to the $Q\\bar Q$ potential coming from the exchanges of all of the relevant modes (such as dilaton, massive scalar, 2-form field, and graviton) are all attractive, leading to an attractive net $Q\\bar Q$ potential. We show that at large separations $r$ and/or high-temperature $T$ the potential is of Yukawa-type, dominated by the graviton exchange, in agreement with earlier findings. On the other hand, at small-$r T$ the $Q\\bar Q$ potential scales as $\\sim (1/r) \\ln (1/rT)$. In the case of $QQ$ potential the 2-form contribution changes sign and becomes repulsive: however, the net $QQ$ potential remains attractive. At large-$r T$ it is dominated by the graviton exchange, while at small-$r T$ the $QQ$ potential becomes Coulomb-like.

Hovhannes R. Grigoryan; Yuri V. Kovchegov

2011-06-23

208

Probing minicharged particles with tests of Coulomb's law.

Minicharged particles arise in many extensions of the standard model. Their contribution to the vacuum polarization modifies Coulomb's law via the Uehling potential. In this Letter, we argue that tests for electromagnetic fifth forces can therefore be a sensitive probe of minicharged particles. In the low mass range < or approximately equal to microeV existing constraints from Cavendish type experiments provide the best model-independent bounds on minicharged particles. PMID:19792696

Jaeckel, Joerg

2009-08-21

209

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

Using the standard Green-Kubo formalism, we determine the shear viscosity $\\eta$ of a hot and dense Yukawa-Fermi gas. In particular, we study the effect of particle and plasmino excitations on thermal properties of the fermionic part of the shear viscosity, and explore the effects of thermal corrections to particle masses on bosonic and fermionic shear viscosities, $\\eta_b$ and $\\eta_f$. It turns out that the effects of plasminos on $\\eta_f$ become negligible with increasing (decreasing) temperature (chemical potential).

Sadooghi, N

2015-01-01

210

Practical expressions for the internal energy and pressure of Yukawa fluids

NASA Astrophysics Data System (ADS)

Simple practical expressions that allow estimation of thermodynamic properties of Yukawa fluids in a wide range of coupling, up to the fluid-solid phase transition, are presented. These expressions demonstrate excellent agreement with the available results from numerical simulations. The approach provides simple and accurate tools to estimate thermodynamic properties of Yukawa fluids and related systems in a broad range of parameters.

Khrapak, Sergey A.; Thomas, Hubertus M.

2015-02-01

211

Practical expressions for the internal energy and pressure of Yukawa fluids

Simple practical expressions are put forward, which allow to estimate thermodynamic properties of Yukawa fluids in a wide range of coupling, up to the fluid-solid phase transition. These expressions demonstrate excellent agreement with the available results from numerical simulations. The approach provides simple and accurate tool to estimate thermodynamic properties of Yukawa fluids and related systems in a broad range of parameters.

Khrapak, Sergey

2015-01-01

212

Comparison of COULOMB-2, NASCAP-2k and SPIS codes for geostationary spacecrafts charging

NASA Astrophysics Data System (ADS)

In developing of international standards for spacecraft charging, it is necessary to compare results of spacecraft charging modeling obtained with various models. In the paper, electrical potentials for spacecraft 3D models were calculated with COULOMB-2, NASCAP-2k [1] and SPIS [2] software, and the comparison of obtained values was performed. To compare COULOMB-2 and NASCAP-2k codes we used a 3D geometrical model of a spacecraft given in [1]. Parameters of spacecraft surface materials were taken from [1], too. For COULOMB-2 and SPIS cross validation, we carried out calculations with SPIS code through SPENVIS web-interface and with COULOMB-2 software for a spacecraft geometrical model given in SPIS test examples [2]. In both cases, we calculated distributions of electric potentials on the spacecraft surface and visualized the obtained distributions with color code. Pictures of the surface potentials distribution calculated with COULOMB-2 and SPIS software are in good qualitative agreement. Absolute values of surface potentials calculated with these codes for different plasma conditions, are close enough. Pictures of the surface potentials distribution calculated for the spacecraft model [1] with COULOMB-2 software completely correspond to actual understanding of physical mechanisms of differential spacecraft surface charging. In this case, we compared only calculated values of the surface potential for the same space plasma conditions because the potential distributions on the spacecraft surface are absent in [1]. For all the plasma conditions considered, COULOMB-2 model gives higher absolute values of negative potential, than NASCAP-2k model. Differences in these values reach 2-3 kV. The possible explanations of the divergences indicated above are distinctions in calculation procedures of primary plasma currents and secondary emission currents. References 1. Ferguson D.?., Wimberly S.C. 51st AIAA Aerospace Science Meeting 2013 (AIAA 2013-0810). 2. http://dev.spis.org/projects/spine/home/spis

Novikov, Lev; Makletsov, Andrei; Sinolits, Vadim

213

Yukawa bound states of a large number of fermions

NASA Astrophysics Data System (ADS)

We consider the bound state problem for a field theory that contains a Dirac fermion ? that Yukawa couples to a (light) scalar field ?. We are interested in bound states with a large number N of ? particles. A Fermi gas model is used to numerically determine the dependence of the radius R of these bound states on N and also the dependence of the binding energy on N. Since scalar interactions with relativistic ?'s are suppressed two regimes emerge. For modest values of N the state is composed of non-relativistic ? particles. In this regime as N increases R decreases. Eventually the core region becomes relativistic and the size of the state starts to increase as N increases. As a result, for fixed Yukawa coupling and ? mass, there is a minimum sized state that occurs roughly at the value of N where the core region first becomes relativistic. We also compute an elastic scattering form factor that can be relevant for direct detection if the dark matter is composed of such ? particles.

Wise, Mark B.; Zhang, Yue

2015-02-01

214

Nonstandard Yukawa Couplings and Higgs Portal Dark Matter

We study the implications of non-standard Higgs Yukawa couplings to light quarks on Higgs-portal dark matter phenomenology. Saturating the present experimental bounds on up-quark, down-quark, or strange-quark Yukawa couplings, the predicted direct dark matter detection scattering rate can increase by up to four orders of magnitude. The effect on the dark matter annihilation cross section, on the other hand, is subleading unless the dark matter is very light -- a scenario that is already excluded by measurements of the Higgs invisible decay width. We investigate the expected size of corrections in multi-Higgs-doublet models with natural flavor conservation, the type-II two-Higgs-doublet model, the Giudice-Lebedev model of light quark masses, minimal flavor violation new physics models, Randall-Sundrum, and composite Higgs models. We find that an enhancement in the dark matter scattering rate of an order of magnitude is possible. Finally, we point out that a discovery of Higgs-portal dark matter could lead to i...

Bishara, Fady; Uttayarat, Patipan; Zupan, Jure

2015-01-01

215

LHC phenomenology of SO(10) models with Yukawa unification. II.

NASA Astrophysics Data System (ADS)

In this paper we study Yukawa-unified SO(10) supersymmetric (SUSY) grand unified theories (GUTs) with two types of SO(10) boundary conditions: (i) universal gaugino masses and (ii) nonuniversal gaugino masses with effective "mirage" mediation. With these boundary conditions, we perform a global ?2 analysis to obtain the parameters consistent with 11 low energy observables, including the top, bottom, and tau masses. Both boundary conditions have universal scalar masses and "just so" splitting for the up- and down-type Higgs masses. In these models, the third family scalars are lighter than the first two families and the gauginos are lighter than all the scalars. We therefore focus on the gluino phenomenology in these models. In particular, we estimate the lowest allowed gluino mass in our models coming from the most recent LHC data and compare this to limits obtained using simplified models. We find that the lower bound on Mg ˜ in Yukawa-unified SO(10) SUSY GUTs is generically ˜1.2 TEV at the 1? level unless there is considerable degeneracy between the gluino and the lightest supersymmetric particle, in which case the bounds are much weaker. Hence many of our benchmark points are not ruled out by the present LHC data and are still viable models which can be tested at LHC 14.

Anandakrishnan, Archana; Bryant, B. Charles; Raby, Stuart

2014-07-01

216

Classical Coulomb fluids in a confined geometry

It has already been argued that a classical (three-dimensional) Coulomb fluid confined between two parallel walls exhibits ideal gas features when the distance between the walls becomes small; this is confirmed in the present paper. Two-dimensional models of Coulomb fluids (with a logarithmic interaction), confined in a strip, are also studied. These models do not become ideal gases in the

B. Jancovici; G. Manificat

1992-01-01

217

Universality in some classical Coulomb systems of restricted dimension

Coulomb systems in which the particles interact through the d-dimensional Coulomb potential but are confined in a flat manifold of dimension d-1 are considered. The actual Coulomb potential acting is defined by particular boundary conditions involving a characteristic macroscopic distance W in the direction perpendicular to the manifold: either it is periodic of period W in that direction, or it vanishes on one ideal conductor wall parallel to the manifold at a distance W from it, or it vanishes on two parallel walls at a distance W from each other with the manifold equidistant from them. Under the assumptions that classical equilibrium statistical mechanics is applicable and that the system has the macroscopic properties of a conductor, it is shown that the suitably smoothed charge correlation function is universal, and that the free energy and the grand potential have universal dependences on W (universal means independent of the microscopic detail). The cases d=2 are discussed in detail, and the generic results are checked on an exactly solvable model. The case d=3 of a plane parallel to an ideal conductor is also explicitly worked out.

Forrester, P.J. [Univ. of Melbourne, Victoria (Australia); Jancovici, B.; Tellez, G. [Universite de Paris-Sud, Orsay (France)

1996-08-01

218

This is a sequel to a recent work of Gaudin, who studied the classical equilibrium statistical mechanics of the two-dimensional Coulomb gas on a lattice at a special value of the coupling constant Gamma such that the model is exactly solvable. This model is briefly reviewed, and it is shown that the correlation functions obey the sum rules that characterize a conductive phase. A related model in which the particles are constrained to move on an array of equidistant parallel lines has simpler mathematics, and the asymptotic behavior of its correlation functions is studied in some detail. In the low-density limit, the lattice model is expected to have the same properties as a system of charged, hard disks; the correlation functions, internal energy, and specific heat of the latter are discussed.

Cornu, F.; Jancovici, B.

1987-10-01

219

NASA Astrophysics Data System (ADS)

The radioactive isotope 107Sn was studied using Coulomb excitation at the REX-ISOLDE facility at CERN. This is the lightest odd-Sn nucleus examined using this technique. The reduced transition probability of the lowest-lying 3/2+ state was measured and is compared to shell-model predictions based on several sets of single-neutron energies relative to 100Sn . Similar to the transition probabilities for the 2+ states in the neutron-deficient even-even Sn nuclei, the measured value is underestimated by shell-model calculations. Part of the strength may be recovered by considering the ordering of the d_{5/2} and g_{7/2} single-neutron states.

DiJulio, D. D.; Cederkall, J.; Fahlander, C.; Ekström, A.; Hjorth-Jensen, M.; Albers, M.; Bildstein, V.; Blazhev, A.; Darby, I.; Davinson, T.; De Witte, H.; Diriken, J.; Fransen, Ch.; Geibel, K.; Gernhäuser, R.; Görgen, A.; Hess, H.; Iwanicki, J.; Lutter, R.; Reiter, P.; Scheck, M.; Seidlitz, M.; Siem, S.; Taprogge, J.; Tveten, G. M.; Van de Walle, J.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

2012-07-01

220

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

221

Relativistic Coulomb scattering of spinless bosons

NASA Astrophysics Data System (ADS)

The relativistic scattering of spin-0 bosons by spherically symmetric Coulomb fields is analyzed in detail with an arbitrary mixing of vector and scalar couplings. It is shown that the partial wave series reduces the scattering amplitude to the closed Rutherford formula exactly when the vector and scalar potentials have the same magnitude, and as an approximation for weak fields. The behavior of the scattering amplitude near the conditions that furnish its closed form is also discussed. Strong suppressions of the scattering amplitude when the vector and scalar potentials have the same magnitude are observed either for particles or antiparticles with low incident momentum. We point out that such strong suppressions might be relevant in the analysis of the scattering of fermions near the conditions for the spin and pseudospin symmetries. From the complex poles of the partial scattering amplitude the exact closed forms of bound-state solutions for both particles and antiparticles with different scenarios for the coupling constants are obtained. Perturbative breaking of the accidental degeneracy appearing in a pair of special cases is related to the nonconservation of the Runge-Lenz vector.

Garcia, M. G.; de Castro, A. S.

2015-03-01

222

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

223

Coulomb impurity problem of graphene in magnetic fields

Analytical solutions of 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 of this problem by numerical diagonalization of large Hamiltonian matrices. Solutions are qualitatively different from those of zero magnetic field. All energies are discrete and no complex energies allowed. We have computed the finite-size scaling function of the probability density containing s-wave component of 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 exponent $\

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

2014-05-21

224

Coulomb systems seen as critical systems: Finite-size effects in two dimensions

It is known that the free energy at criticality of a finite two-dimensional system of characteristic size L has in general a term which behaves like log L as L {yields} {infinity}; the coefficient of this term is universal. There are solvable models of two-dimensional classical Coulomb systems which exhibit the same finite-size correction (except for its sign) although the particle correlations are short-ranged, i.e., noncritical. Actually, the electrical potential and electrical field correlations are critical at all temperatures (as long as the Coulomb system is a conductor), as a consequence of the perfect screening property of Coulomb systems. This is why Coulomb systems have to exhibit critical finite-size effects.

Jancovici, B.; Manificat, G.; Pisani, C. [Universite de Paris-Sud, Orsay (France)

1994-07-01

225

Investigation of the phase structure of a chirally-invariant Higgs-Yukawa model

We present new data on our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at large bare Yukawa couplings. The data presented last year are extended in terms of statistics, the number of bare Yukawa couplings at existing, and new larger volumes. In addition, this study is extended by a finite temperature project at the physical top quark mass m_t =175 GeV and a hypothetical fourth generation top quark with a mass of m_t' =700 GeV .

John Bulava; Philipp Gerhold; George W. -S. Hou; Karl Jansen; Bastian Knippschild; C. -J. David Lin; Kei-Ichi Nagai; Attila Nagy; Kenji Ogawa

2012-10-31

226

The B(E2; Ii ! If ) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If ) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga...

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

2010-01-01

227

The B(E2; Ii -> If) values for transitions in 71Ga and 73Ga were deduced from a Coulomb excitation experiment at the safe energy of 2.95 MeV/nucleon using post-accelerated beams of 71,73Ga at the REX-ISOLDE on-line isotope mass separator facility. The emitted gamma rays were detected by the MINIBALL-detector array and B(E2; Ii->If) values were obtained from the yields normalized to the known strength of the 2+ -> 0+ transition in the 120Sn target. The comparison of these new results with the data of less neutron-rich gallium isotopes shows a shift of the E2 collectivity towards lower excitation energy when adding neutrons beyond N = 40. This supports conclusions from previous studies of the gallium isotopes which indicated a structural change in this isotopical chain between N = 40 and N = 42. Combined with recent measurements from collinear laser spectroscopy showing a 1/2- spin and parity for the ground state, the extracted results revealed evidence for a 1/2-; 3/2- doublet near the ground state in 73 31Ga42 differing by at most 0.8 keV in energy.

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

2010-11-25

228

Theoretical Studies of the Coulomb Gap.

NASA Astrophysics Data System (ADS)

We have considered the effects of Coulomb interactions between electrons on the ground state configuration of the electrons for two disordered systems. One of these is a model in which the electrons occupy a fraction K of the sites of a two or three dimensional lattice. The lattice sites are characterized by potential energies, E, the distribution of which is assumed to be square, or width W(,0). The site energies are independent of each other. For this system we have calculated the width, E(,g), of the Coulomb Gap, first by minimizing the total energy with respect to single electron transitions of infinite length, then by minimizing the total energy for an idealized site energy occupation function, g(E). These results may be summarized by. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). where E(,c) is equal to e('2)/(kappa)a(,0), a(,0) is the lattice parameter, C(2) = 1.61, C(3) = 1.75 and d is the dimensionality for lightly-doped semiconductors of compensation K we calculate a screening length, R(,0) which we then use to determine the distribution of energies for an arbitrary point in space, W(,a)(E). We calculate a first approximation to N(E), the single electron density of states. We then determine analytic expressions for E(,g) and also for (sigma)(K), the dependence of the width of W(,a)(E) on K. We use (sigma)(K) in the expression for E(,g) for the lattice model, to obtain a result for E(,g) which is appropriate for impurity conduction. Then we use the results of Pollak and Ortuno to relate E(,g), for K = 1/2 to (epsilon)(,3), the activation energy of the dc conductivity as determined experimentally in lightly -doped compensated semicondutors. The results for E(,g) may be expressed as. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI). Experimentally C is found to be roughly .4. Our results from the lattice model as applied to compensated semiconductors yield a result for C of .4 derived directly for compensated semiconductors is .39.

Hunt, Allen Gerhard

229

SLE($?,?$)and Boundary Coulomb Gas

We consider the coulomb gas model on the upper half plane with different boundary conditions, namely Drichlet, Neuman and mixed. We related this model to SLE($\\kappa,\\rho$) theories. We derive a set of conditions connecting the total charge of the coulomb gas, the boundary charges, the parameters $\\kappa$ and $\\rho$. Also we study a free fermion theory in presence of a boundary and show with the same methods that it would lead to logarithmic boundary changing operators.

S. Moghimi-Araghi; M. A. Rajabpour; S. Rouhani

2005-08-07

230

Laser manipulation of dust particles in Coulomb balls

NASA Astrophysics Data System (ADS)

A dusty plasma is a partially ionized gas that contains small particles of solid matter, or dust. Dust particles become charged by collecting electrons and ions from the plasma, which can cause them to interact with a large potential energy in comparison with their thermal energy. This strong coupling causes dust particles to arrange themselves as a solid or liquid. One type of dusty plasma is the recently discovered Coulomb ball (Arp et al., PRL 2004), which is a 3D spherically shaped suspension of dust. The ball becomes trapped due to a balance of three forces: the electric force due to the plasma electric field and a thermophoretic force resulting from a temperature gradient in the gas, which are both directed upward, and gravity. In this experiment, a glow-discharge plasma is used to confine 4.8 ?m microspheres forming a Coulomb ball inside a glass box atop a heated electrode. We report experimental results where radiation pressure, from one or more laser beams, is used to push some of the dust particles, creating a flow and reshaping the Coulomb ball.

Flanagan, Tim; Goree, J.

2007-11-01

231

Coulomb crystal mass spectrometry in a digital ion trap

NASA Astrophysics Data System (ADS)

We present a mass spectrometric technique for identifying the masses and relative abundances of Coulomb-crystallized ions held in a linear Paul trap. A digital radio-frequency wave form is employed to generate the trapping potential, as this can be cleanly switched off, and static dipolar fields are subsequently applied to the trap electrodes for ion ejection. Close to 100% detection efficiency is demonstrated for Ca+ and CaF+ ions from bicomponent Ca+-CaF+ Coulomb crystals prepared by the reaction of Ca+ with CH3F . A quantitative linear relationship is observed between ion number and the corresponding integrated time-of-flight (TOF) peak, independent of the ionic species. The technique is applicable to a diverse range of multicomponent Coulomb crystals—demonstrated here for Ca+-NH 3+ -NH 4+ and Ca+-CaOH +-CaOD + crystals—and will facilitate the measurement of ion-molecule reaction rates and branching ratios in complicated reaction systems.

Deb, Nabanita; Pollum, Laura L.; Smith, Alexander D.; Keller, Matthias; Rennick, Christopher J.; Heazlewood, Brianna R.; Softley, Timothy P.

2015-03-01

232

Higher Dimensional Coulomb Gases and Renormalized Energy Functionals

We consider a classical system of n charged particles in an external confining potential, in any dimension d larger than 2. The particles interact via pairwise repulsive Coulomb forces and the coupling parameter scales like the inverse of n (mean-field scaling). By a suitable splitting of the Hamiltonian, we extract the next to leading order term in the ground state energy, beyond the mean-field limit. We show that this next order term, which characterizes the fluctuations of the system, is governed by a new "renormalized energy" functional providing a way to compute the total Coulomb energy of a jellium (i.e. an infinite set of point charges screened by a uniform neutralizing background), in any dimension. The renormalization that cuts out the infinite part of the energy is achieved by smearing out the point charges at a small scale, as in Onsager's lemma. We obtain consequences for the statistical mechanics of the Coulomb gas: next to leading order asymptotic expansion of the free energy or partition function, characterizations of the Gibbs measures, estimates on the local charge fluctuations and factorization estimates for reduced densities. This extends results of Sandier and Serfaty to dimension higher than two by an alternative approach.

N. Rougerie; S. Serfaty

2015-01-23

233

Quantum magnetotransport in two-dimensional Coulomb liquids

NASA Astrophysics Data System (ADS)

In this article we review recent progress in understanding of many-electron effects on the quantum magnetotransport in two-dimensional (2D) Coulomb liquids in which the interaction potential energy per electron can be approximately a hundred times larger than the mean kinetic energy. The conventional Fermi-liquid approach based on the introduction of weakly interacting excitations being not applicable, it is remarkable that a quantitative theoretical description of the equilibrium and transport properties of the 2D Coulomb liquid appears to be possible. An account of basic properties of the strongly interacting 2D electron system under magnetic field realized on a free surface of liquid helium is given. Due to the high magnetic field applied perpendicular to the system, the electron liquid constituted of strongly interacting electrons can be described as a collection of statistically independent electrons, each of them having the discrete Landau spectrum in a local reference frame moving ultra-fast with regard to the center-of-mass frame of the entire electron liquid. We found it surprising that the narrowing of Landau levels induced by Coulomb forces in local frames is accompanied by a strong Coulomb broadening of the electron dynamical structure factor (DSF) in the laboratory reference frame. We discuss in detail the magnetotransport theories in two-dimensions, especially the force-balance equation method and the memory function formalism which allow to reduce the electron transport problem to the description of the equilibrium electron DSF. We show that the whole body of the DC magnetoconductivity and cyclotron resonance absorption data measured and reported within the last two decades (even previously conflicting with theory) can be very well described by means of a simple model for the electron DSF entering the imaginary part of the memory function or the effective collision frequency of the electrons.

Monarkha, Yu. P.; Teske, E.; Wyder, P.

2002-11-01

234

Renormalization of the Yukawa Theory Physics 230A (Spring 2007), Hitoshi Murayama

Renormalization of the Yukawa Theory Physics 230A (Spring 2007), Hitoshi Murayama We solve Problem matrices {Âµ , } = 2gÂµ and {Âµ , 5 } = 0. Note also (-x, t) = -( )(-x, t) etc. The minus signs appear twice

Murayama, Hitoshi

235

Confronting Four Zero Neutrino Yukawa Textures with $N_2^{}$-dominated Leptogenesis

We consider a restricted Type-I seesaw scenario with four texture zeros in the neutrino Yukawa matrix, in the basis where both the charged-lepton Yukawa matrix and the Majorana mass matrix for right-handed neutrinos are diagonal. Inspired by grand unified theories, we further require the neutrino Yukawa matrix to exhibit a similar hierarchical pattern to that in the up-type quark Yukawa matrix. With such a hierarchy requirement, we find that leptogenesis, which would operate in a $N_2^{}$-dominated scenario with the asymmetry generated by the next-to-lightest right-handed neutrino $N_2^{}$, can greatly reduce the number of allowed textures, and disfavors the scenario that three light neutrinos are quasi-degenerate. Such a quasi-degenerate scenario of light neutrinos may soon be tested in upcoming neutrino experiments.

Jue Zhang

2015-02-13

236

CP invariance of chiral gauge theories and Majorana-Yukawa couplings on the lattice

The construction of CP-invariant lattice chiral gauge theories and the construction of lattice Majorana fermions with chiral Yukawa couplings is subject to topological obstructions. In the present work we suggest lattice extensions of charge and parity transformation for Weyl fermions. This enables us to construct lattice chiral gauge theories that are CP invariant. For the construction of Majorana-Yukawa couplings, we discuss two models with symplectic Majorana fermions: a model with two symplectic doublets, and one with an auxiliary doublet.

Yuji Igarashi; Jan M. Pawlowski

2009-11-11

237

Neutralino Dark Matter and Other LHC Predictions from Quasi Yukawa Unification

We explore the dark matter and LHC implications of t-b-tau quasi Yukawa unification in the framework of supersymmetric models based on the gauge symmetry G=SU(4)_{c}\\times SU(2)_{L}\\times SU(2)_{R}. The deviation from exact Yukawa unification is quantified by a dimensionless parameter C (|C| ~ 2 TeV, while the first two family squarks and sleptons are of order 4-5 TeV and 3 TeV respectively.

Shafi, Qaisar; Un, Cem Salih

2015-01-01

238

Coulomb interaction effects on the Majorana states in quantum wires.

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. PMID:24722427

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

2014-04-30

239

The electronic spectrum of a trimer with a variable number of electrons has been calculated in the Hubbard model by exact diagonalization. The dependences of the chemical potential shift, magnetic moment, and energy level splitting near the chemical potential on the magnetic field, Coulomb interaction between the electrons located at the vertices of the triangle, trimer deformation, and three-center interaction have been established. The removal of magnetic degeneracy in the trimer when the intersite Coulomb and three-center interactions are taken into account and the formation of a singlet pair of electrons under trimer deformation have been detected.

Aplesnin, S. S., E-mail: apl@iph.krasn.ru [Reshetnev Siberian State Aerospace University (Russian Federation); Piskunova, N. I. [Omsk State Agrarian University (Russian Federation)

2011-01-15

240

Fermionic dark matter with pseudo-scalar Yukawa interaction

NASA Astrophysics Data System (ADS)

We consider a renormalizable extension of the standard model whose fermionic dark matter (DM) candidate interacts with a real singlet pseudo-scalar via a pseudo-scalar Yukawa term while we assume that the full Lagrangian is CP-conserved in the classical level. When the pseudo-scalar boson develops a non-zero vacuum expectation value, spontaneous CP-violation occurs and this provides a CP-violated interaction of the dark sector with the SM particles through mixing between the Higgs-like boson and the SM-like Higgs boson. This scenario suggests a minimal number of free parameters. Focusing mainly on the indirect detection observables, we calculate the dark matter annihilation cross section and then compute the DM relic density in the range up to mDM = 300 GeV.We then find viable regions in the parameter space constrained by the observed DM relic abundance as well as invisible Higgs decay width in the light of 125 GeV Higgs discovery at the LHC. We find that within the constrained region of the parameter space, there exists a model with dark matter mass mDM ~ 38 GeV annihilating predominantly into b quarks, which can explain the Fermi-LAT galactic gamma-ray excess.

Ghorbani, Karim

2015-01-01

241

SUSY-Yukawa Sum Rule at the LHC

We propose the "supersymmetric (SUSY) Yukawa sum rule", a relationship between physical masses and mixing angles of the third-generation quarks and squarks. The sum rule follows directly from a relation between quark and squark couplings to the Higgs, enforced by SUSY. It is exactly this relation that ensures the cancellation of the one-loop quadratic divergence in the Higgs mass from the top sector. Testing the sum rule experimentally would thus provide a powerful consistency check on SUSY as the solution to the gauge hierarchy problem. While such a test will most likely have to await a future next-generation lepton collider, the LHC experiments may be able to make significant progress towards this goal. If some of the terms entering the sum rule are measured at the LHC, the sum rule can be used (within SUSY framework) to put interesting constraints on the other terms, such as the mixing angles among third-generation squarks. We outline how the required mass measurements could be performed, and estimate the accuracy that can be achieved at the LHC.

Monika Blanke; David Curtin; Maxim Perelstein

2010-08-03

242

Yukawa Textures in Horava-Witten M-Theory

Recent advances in 11 dimensional Horava-Witten M-theory based on non-standard embeddings with torus fibered Calabi-Yau manifolds have allowed the construction of three generation models with Wilson line breaking to the Standard Model gauge symmetry. Central to these constructions is the existence of a set of 5-branes in the bulk. We examine within this framework the general structure of the matter Yukawa couplings and show that M-theory offers an alternate possible way of achieving the CKM and quark mass hierarchies without introducing undue fine tuning or (as in conventional analysis) small parameters raised to high powers. A phenomenological example is presented in accord with all CKM and quark mass data requiring mainly that the 5-branes cluster near the second orbifold plane, and that the instanton charges of the physical orbifold plane vanish. An explicit example of a three generation model with vanishing physical plane instanton charges based on a torus fibered Calabi-Yau three fold with a del Pezzo base $dP_7$ and Wilson line breaking is constructed.

R. Arnowitt; B. Dutta

2000-06-21

243

A Computer Program for Relativistic Multiple Coulomb and Nuclear Excitation

A computer program is presented by which one may calculate the multiple electric dipole, electric quadrupole and magnetic dipole Coulomb excitation with relativistic heavy ions. The program applies to an arbitrary nucleus, specified by the spins and energies of the levels and by all E1, E2 and M1 matrix elements. Nuclear excitation is calculated optionally for monopole, dipole and quadrupole excitations and needs inputs of optical potentials. For given bombarding conditions, the differential cross sections and statistical tensors (useful to calculate gamma-ray angular distribution functions) are computed.

C. A. Bertulani

1998-04-13

244

Coulomb screening in graphene with topological defects

We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed.

Baishali Chakraborty; Kumar S. Gupta; Siddhartha Sen

2015-02-20

245

Critical fluctuations and anomalous transport in soft Yukawa-Langevin systems

Simulation of a Langevin-dynamics model demonstrates emergence of critical fluctuations and anomalous grain transport which have been observed in experiments on "soft" quasi-two-dimensional dusty plasma clusters. It has been suggested that these anomalies derive from particular non-equilibrium physics, but our model does not contain such physics: the grains are confined by an external potential, interact via static Yukawa forces, and are subject to stochastic heating and dissipation from neutrals. One remarkable feature is emergence of leptokurtic probability distributions of grain displacements $\\xi(\\tau)$ on time-scales $\\tau^{1/2}$ approaches the mean inter-grain distance $\\Delta$. Others are development of humps in the distributions on multiples of $\\Delta$, anomalous Hurst exponents, and transitions from leptokurtic towards Gaussian displacement distributions on time scales $\\tau>\\tau_{\\Delta}$. The latter is a signature of intermittency, here interpreted as a transition from bursty transport associated with hopping on intermediate time scales to vortical flows on longer time scales.

S. Ratynskaia; G. Regnoli; K. Rypdal; B. Klumov; G. Morfill

2009-07-06

246

Coulombic effect and renormalization in nuclear pairing

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

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

2011-03-15

247

Hard pion bremsstrahlung in the Coulomb region

Hard high-energy pion-nucleus bremsstrahlung, $\\pi^- +A\\to\\pi^- +\\gamma +A$, is studied in the Coulomb region, i.e. the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying the pion-Compton amplitude through a model with $\\sigma$, $\\rho$, and a_1 exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.

Göran Fäldt; Ulla Tengblad

2007-08-02

248

Coulomb explosion of a heated cluster

Coulomb explosion of a charged, nonuniform, and spherically symmetric cluster with a finite ion temperature is investigated. The spatial distributions of the density and mean velocity of accelerated ions, as well as their energy spectra, are obtained and analyzed as functions of the initial temperature. It is shown that taking into account the finite ion temperature eliminates singularities emerging during a Coulomb explosion of a spatially nonuniform cold cluster due to multistream ion motion that arises after breaking the velocity profile of the cluster ions. The characteristic temperature is found above which the spatial distribution and energy spectrum of the expanding ions become regular.

Novikov, V. N.; Brantov, A. V.; Bychenkov, V. Yu. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Kovalev, V. F. [Russian Academy of Sciences, Institute for Mathematical Modeling (Russian Federation)

2008-11-15

249

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

250

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

251

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 (? _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 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

252

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

253

Coulomb screening in graphene with topological defects

We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green's function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green's function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb imp...

Chakraborty, Baishali; Sen, Siddhartha

2015-01-01

254

Nonequilibrium dephasing in Coulomb blockaded quantum dots.

We present a theory of zero-bias anomalies and dephasing rates for a Coulomb-blockaded quantum dot, driven out of equilibrium by coupling to voltage biased source and drain leads. We interpret our results in terms of the statistics of voltage fluctuations in the system. PMID:19257305

Altland, Alexander; Egger, Reinhold

2009-01-16

255

On the two-dimensional Coulomb gas

This is a sequel to a recent work of Gaudin, who studied the classical equilibrium statistical mechanics of the two-dimensional Coulomb gas on a lattice at a special value of the coupling constant? such that the model is exactly solvable. This model is briefly reviewed, and it is shown that the correlation functions obey the sum rules that characterize a

Françoise Cornu; Bernard Jancovici

1987-01-01

256

Coulomb Drag in Multiwall Carbon Nanotubes

Coulomb Drag in Multiwall Carbon Nanotubes Master Thesis in Physics Anders Mathias Lunde Niels Bohr the band structure of carbon nanotubes. For discussions about the experimental possibilities I will like drag and how is it studied? . . . . . . . . . . . 2 1.3 What is a Carbon nanotube

NygÃ¥rd, Jesper

257

Coulomb excitation of radioactive 20, 21Na

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

258

Coulomb Explosion in a Cluster Plasma

The energy spectra of particles in a cluster plasma produced during the Coulomb explosion of spherically symmetric clusters with an arbitrary initial density distribution are investigated. A relationship is found between the energy spectrum of the ions and the density profile of the atoms in the cluster.

Bychenkov, V.Yu. [Lebedev Institute of Physics, Russian Academy of Sciences, Leninskii pr. 53, Moscow, 117924 (Russian Federation); Kovalev, V.F. [Institute for Mathematical Modeling, Russian Academy of Sciences, Miusskaya pl. 4a, Moscow, 125047 (Russian Federation)

2005-02-15

259

is a collection of particles interacting through a shielded Coulomb potential. For a point particle of charge Q, and the comparison yields the shielding parameter and the charge on particles. DOI: 10.1103/PhysRevE.65.066402 PACS is the distance from a charged particle and D is the shielding length. When the system is in thermodynamic equi

Goree, John

260

Spherical volume averages of static electric and magnetic fields using Coulomb and Biot-Savart laws

We present derivations of the expressions for the spherical volume averages of static electric and magnetic fields that are virtually identical. These derivations utilize the Coulomb and Biot-Savart laws, and make no use of vector calculus identities or potentials.

Ben Yu-Kuang Hu

2009-01-31

261

Femtosecond ionization and Coulomb explosion of small transition metal carbide clusters

NASA Astrophysics Data System (ADS)

Strong-field ionization and subsequent Coulomb explosion of small group 5 metal carbide clusters are explored using ultrashort pulses centered at 624 nm. More efficient Coulomb explosion was observed according to: Ta > Nb > V due to the larger mass of tantalum, the slower cluster expansion times, and lower ionization potentials of large atoms. Minimum laser intensities required for the onset of each atomic charge state of V, Nb, and Ta were found to be nearly identical between metal carbides and previously observed group 5 metal oxide clusters indicating electron delocalization within the cluster. Ionization enhancement is explored by comparison to semi-classical tunneling theory.

Ross, Matt W.; Castleman, A. W.

2012-09-01

262

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

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

263

Tidally driven Coulomb failure of faults on Enceladus and Europa

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

264

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

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

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

2011-01-01

265

Laser-dressed vacuum polarization in a Coulomb field

NASA Astrophysics Data System (ADS)

We investigate quantum electrodynamic effects under the influence of an external, time-dependent electromagnetic field, which mediates dynamic modifications of the radiative corrections. Specifically, we consider the quantum electrodynamic vacuum-polarization tensor under the influence of two external background fields: a strong laser field and a nuclear Coulomb field. We calculate the charge and current densities induced by a nuclear Coulomb field in the presence of a laser field. We find the corresponding induced scalar and vector potentials. The induced potential, in first-order perturbation theory, leads to a correction to atomic energy levels. The external laser field breaks the rotational symmetry of the system. Consequently, the induced charge density is not spherically symmetric, and the energy correction therefore leads to a “polarized Lamb shift.” In particular, the laser generates an additional potential with a quadrupole moment. The corresponding laser-dressed vacuum-polarization potential behaves like 1/r3 at large distances, unlike the Uehling potential, which vanishes exponentially for large r . The energy corrections are of the same order of magnitude for hydrogenic levels, irrespective of the angular momentum quantum number. The induced current leads to a transition dipole moment which oscillates at the second harmonic of the laser frequency and is mediated by second-order harmonic generation in the vacuum-polarization loop. In the far field, at distances r?1/? from the nucleus ( ? is the laser frequency), the laser induces mutually perpendicular electric and magnetic fields, which give rise to an energy flux that corresponds to photon fusion leading to the generation of real photons, again at the second harmonic of the laser. Our investigation might be useful for other situations where quantum field theoretic phenomena are subjected to external fields of a rather involved structure.

Milstein, A. I.; Terekhov, I. S.; Jentschura, U. D.; Keitel, C. H.

2005-11-01

266

Fermi-Edge Transmission Resonance in Graphene Driven by a Single Coulomb Impurity

NASA Astrophysics Data System (ADS)

The interaction between the Fermi sea of conduction electrons and a nonadiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude ?e2/h at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime.

Karnatak, Paritosh; Goswami, Srijit; Kochat, Vidya; Nath Pal, Atindra; Ghosh, Arindam

2014-07-01

267

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

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

Mazumdar, S.; Campbell, D.K.

1985-01-01

268

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

269

Coulomb impurity scattering in topological insulator thin films

Inter-surface coupling in thin-film topological insulators can reduce the surface state mobility by an order of magnitude in low-temperature transport measurements. The reduction is caused by a reduction in the group velocity and an increased s{sub z} component of the surface-state spin which weakens the selection rule against large-angle scattering. An intersurface potential splits the degenerate bands into a Rashba-like bandstructure. This reduces the intersurface coupling, it largely restores the selection rule against large angle scattering, and the ring-shaped valence band further reduces backscattering by requiring, on average, larger momentum transfer for backscattering events. The effects of temperature, Fermi level, and intersurface potential on the Coulomb impurity scattering limited mobility are analyzed and discussed.

Yin, Gen; Wickramaratne, Darshana; Lake, Roger K., E-mail: rlake@ee.ucr.edu [Department of Electrical Engineering, University of California, Riverside, California 92521 (United States); Zhao, Yuanyuan [Texas Center for Superconductivity and Department of Physics, University of Houston, Houston, Texas 77204 (United States)

2014-07-21

270

Upper Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model

We establish the cutoff-dependent upper Higgs boson mass bound by means of direct lattice computations in the framework of a chirally invariant lattice Higgs-Yukawa model emulating the same chiral Yukawa coupling structure as in the Higgs-fermion sector of the Standard Model. As expected from the triviality picture of the Higgs sector, we observe the upper mass bound to decrease with rising cutoff parameter $\\Lambda$. Moreover, the strength of the fermionic contribution to the upper mass bound is explored by comparing to the corresponding analysis in the pure $\\Phi^4$-theory.

P. Gerhold; K. Jansen

2010-02-23

271

The phase structure of a chirally-invariant Higgs-Yukawa model

We present new results of our ongoing project on the investigation of the phase structure of the Higgs-Yukawa model at small and large bare Yukawa couplings. The critical exponents of the second order bulk phase transitions of this model are determined from finite-size analyses and compared to the pure O(4)-model to test for triviality and the possibility of having a non-Gaussian fixed point. In addition, we will present a first study of Higgs boson masses and fermion correlation functions.

Prasad Hegde; George W. -S. Hou; Karl Jansen; Bastian Knippschild; C. -J. David Lin; Kei-Ichi Nagai; Attila Nagy; Kenji Ogawa

2013-10-22

272

``Coulomb logarithm'' for inverse-bremsstrahlung laser absorption

NASA Astrophysics Data System (ADS)

The ``Coulomb logarithm'' for inverse-bremsstrahlung laser absorption is examined for plasmas of different ionic charge, spanning the classical and quantum-mechanical limits. Previously, this term has not been calculated exactly for the conditions of interest in laser fusion experiments; it has only been estimated from physical considerations. For short-wavelength irradiation (e.g., 0.35 ?m), uncertainties in the ``logarithmic'' factor can produce variations of 20-50 % in the laser absorption coefficient. A more exact treatment of this term is presented here. For low-Z plasmas, a modified Born approximation is used that reproduces previous results for long-range interactions that cannot be described by a single electron-ion collision, and it simultaneously treats the short-range electron-ion encounters. For high-Z plasmas, the Coulomb logarithm is calculated in terms of the classical, nonlinear electron trajectory in a self-consistent electrostatic potential; strong ion-ion correlations are treated by the nonlinear Debye-Hückel model. There are no indeterminate quantities in the calculations.

Skupsky, Stanley

1987-12-01

273

Theory of Coulomb drag for massless Dirac fermions

NASA Astrophysics Data System (ADS)

Coulomb drag between two unhybridized graphene sheets separated by a dielectric spacer has recently attracted considerable theoretical interest. We first review, for the sake of completeness, the main analytical results which have been obtained by other authors. We then illustrate pedagogically the minimal theory of Coulomb drag between two spatially separated two-dimensional systems of massless Dirac fermions which are both away from the charge-neutrality point. This relies on second-order perturbation theory in the screened interlayer interaction and on Boltzmann-transport theory. In this theoretical framework and in the low-temperature limit, we demonstrate that, to leading (i.e. quadratic) order in temperature, the drag transresistivity is completely insensitive to the precise intralayer momentum-relaxation mechanism (i.e. to the functional dependence of the transport scattering time on energy). We also provide analytical results for the low-temperature drag transresistivity for both cases of ‘thick’ and ‘thin’ spacers and for arbitrary values of the dielectric constants of the media surrounding the two Dirac-fermion layers. Finally, we present numerical results for the low-temperature drag transresistivity for the case when one of the media surrounding the Dirac-fermion layers has a frequency-dependent dielectric constant. We conclude by suggesting an experiment that can potentially allow for the observation of departures from the canonical quadratic-in-temperature behavior of the transresistivity.

Carrega, M.; Tudorovskiy, T.; Principi, A.; Katsnelson, M. I.; Polini, M.

2012-06-01

274

Pore fluid pressure, apparent friction, and Coulomb failure

Many recent studies of stress-triggered seismicity rely on a fault failure model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ? ?? ? 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter ?? is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential failure plane. Although specific models of fault zones permit such a relation, neither is it known that fault zones within the Earth behave this way, nor is this behavior expected in all cases. In contrast, for an isotropic homogeneous poroelastic model the pore pressure changes are proportional to changes in mean stress, ?? is not a material constant, and ?? ? ?? ? +?. Analysis of the change in Coulomb failure stress for tectonically loaded reverse and strike-slip faults shows considerable differences between these two pore pressure models, suggesting that such models might be distinguished from one another using observations of triggered seismicity (e.g., aftershocks). We conclude that using the constant apparent friction model exclusively in studies of Coulomb failure stress is unwise and could lead to significant errors in estimated stress change and seismic hazard.

Beeler, N.M.; Simpson, R.W.; Hickman, S.H.; Lockner, D.A.

2000-01-01

275

Coulomb edge effects in graphene nanoribbons

NASA Astrophysics Data System (ADS)

Coulomb effects in graphene nanoribbons with arbitrary edges are investigated with the use of a mean-field Hubbard model. It was recently shown that chiral ribbons with minimal edges, characterized by the translation vector (n,m), have a similar structure of bands localized around the Fermi energy as pure zigzag ribbons (n-m,0). Here we show that these flat bands in both ribbon cases differ in detail due to the perturbation induced by armchair edge nodes. For chiral ribbons the edge bands split at the zone boundary, where the corresponding bands of (n-m,0) zigzag ribbons are degenerate. Coulomb interactions enhance strongly this splitting and at the same time they bring spin into play. We modify each edge keeping global sublattice balance to find that spin degeneracy can be partially lifted. The breaking of spin-degeneracy depends on the asymmetry between the edges and in some cases leads to spin-polarized currents.

Jaskolski, W.; Ayuela, A.

2014-10-01

276

ANALYTIC STRUCTURE OF MANYBODY COULOMBIC WAVE FUNCTIONS

], who proved that # is LipsÂ chitz continuous, i.e., # # C 0,1 , near twoÂparticle coalescence points of nonÂrelativistic SchrË?odinger equations describing Coulombic manyÂ particle systems. We prove with one nucleus fixed at the origin. Then in a neighÂ bourhood of a coalescence point, for which x 1 = 0

277

Chaos near the Coulomb barrier. Nuclear molecules

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

Strayer, M.R.

1984-01-01

278

Large charge fluctuations in classical Coulomb systems

The typical fluctuation of the net electric chargeQ contained in a subregion? of an infinitely extended equilibrium Coulomb system is expected to grow only as vS, whereS is the surface area of?. For some cases it has been previously shown thatQ\\/vS has a Gaussian distribution as ¦?¦?8. Here we study the probability law for larger charge fluctuations (large-deviation problem). We

B. Jancovici; J. L. Lebowitz; G. Manificat

1993-01-01

279

Coulomb collision effects on linear Landau damping

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 ?{sub 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/?{sub eff} during Landau damping of a small amplitude Langmuir wave.

Callen, J. D., E-mail: callen@engr.wisc.edu [University of Wisconsin, Madison, Wisconsin 53706-1609 (United States)

2014-05-15

280

Sliding along Coulombic shear faults in ice

NASA Astrophysics Data System (ADS)

New experiments have been performed on the resistance to inelastic deformation through frictional sliding along naturally-formed Coulombic shear faults in ice Ih. Coulombic faults mark terminal failure of virgin material when loaded rapidly under a moderate degree of confinement. The experiments were performed on S2 fresh-water ice at -10degreesC, proportionally loaded biaxially across the columns along a variety of all-compressive paths. Two kinds of behavior were observed. At higher sliding velocities (8 x 10(-2) and 8 x 10(-1) mm s(-1)) sliding was noisy and the process exhibited velocity weakening. At a lower sliding velocity (8 x 10(-4) mm s(-1)) sliding was quiet and fault healing occurred. The two kinds of sliding are indicative of brittle-like (at higher speeds) and ductile-like (at lower speeds) behavior, and are explained in terms of fracture and creep. Within the brittle regime, a power law describes the relationship between the shear strength of the fault and the normal stress across it at the onset of sliding, while Coulomb's law describes the relationship once sliding has progressed by about 2 mm.

Fortt, A.; Schulson, E. M.; Russell, E.

2003-01-01

281

Itinerant electrons in the Coulomb phase

NASA Astrophysics Data System (ADS)

We study the interplay between magnetic frustration and itinerant electrons. For example, how does the coupling to mobile charges modify the properties of a spin liquid, and does the underlying frustration favor insulating or conducting states? Supported by Monte Carlo simulations, our goal is in particular to provide an analytical picture of the mechanisms involved. The models under consideration exhibit Coulomb phases in two and three dimensions, where the itinerant electrons are coupled to the localized spins via double exchange interactions. Because of the Hund coupling, magnetic loops naturally emerge from the Coulomb phase and serve as conducting channels for the mobile electrons, leading to doping-dependent rearrangements of the loop ensemble in order to minimize the electronic kinetic energy. At low electron density ?, the double exchange coupling mainly tends to segment the very long loops winding around the system into smaller ones while it gradually lifts the extensive degeneracy of the Coulomb phase with increasing ?. For higher doping, the results are strongly lattice dependent, displaying loop crystals with a given loop length for some specific values of ?. By varying ?, they can melt into different mixtures of these loop crystals, recovering extensive degeneracy in the process. Finally, we contrast this to the qualitatively different behavior of analogous models on kagome or triangular lattices.

Jaubert, L. D. C.; Piatecki, Swann; Haque, Masudul; Moessner, R.

2012-02-01

282

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

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

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

2009-02-15

283

Infinite volume limit of the strongly coupled Yukawa/sub 2/ model

Using the FKG inequality, we construct infinite volume expectations of products of boson fields and fermi currents (u-baru)/sub ren/ for the scalar Yukawa/sub 2/ model with arbitrary coupling constant. These expectations satisfy the Osterwalder--Schrader axioms with the possible exception of clustering.

Battle, G.A.; Rosen, L.

1981-04-01

284

Yukawa coupling and anomalous magnetic moment of the muon: An update for the LHC era

We study the interplay between a soft muon Yukawa coupling generated radiatively with the trilinear A-terms of the minimal supersymmetric standard model (MSSM) and the anomalous magnetic moment of the muon. In the absence of a tree-level muon Yukawa coupling the lightest smuon mass is predicted to be in the range between 600 GeV and 2200 GeV at 2{sigma}, if the bino mass M{sub 1} is below 1 TeV. Therefore, a detection of a smuon (in conjunction with a sub-TeV bino) at the LHC would directly imply a nonzero muon Yukawa coupling in the MSSM superpotential. Inclusion of slepton flavor mixing could in principle lower the mass of one smuonlike slepton below 600 GeV. However, the experimental bounds on radiative lepton decays instead strengthen the lower mass bound, with larger effects for smaller M{sub 1}, We also extend the analysis to the electron case and find that a light selectron close to the current experimental search limit may prove the MSSM electron Yukawa coupling to be nonzero.

Crivellin, Andreas [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany); Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, CH-3012 Bern (Switzerland); Girrbach, Jennifer; Nierste, Ulrich [Institut fuer Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

2011-03-01

285

Shear viscosity and shear thinning in two-dimensional Yukawa , J. Goree2

Shear viscosity and shear thinning in two-dimensional Yukawa liquids Z. DonkÂ´o1 , J. Goree2 , P using two different nonequi- librium molecular dynamics simulation methods. Shear viscosity values.e., the viscosity diminishes with increasing shear rate. It is expected that two-dimensional dusty plasmas

Goree, John

286

We demonstrate the feasibility and efficiency of the Coulomb-Sturmian separable expansion method for generating accurate solutions of the Faddeev equations. Results obtained with this method are reported for several benchmark cases of bosonic and fermionic three-body systems. Correct bound-state results in agreement with the ones established in the literature are achieved for short-range interactions. We outline the formalism for the treatment of three-body Coulomb systems and present a bound-state calculation for a three-boson system interacting via Coulomb plus short-range forces. The corresponding result is in good agreement with the answer from a recent stochastic-variational-method calculation. {copyright} {ital 1996 The American Physical Society.}

Papp, Z. [Institute of Nuclear Research of the Hungarian Academy of Sciences, Bem ter 18/c, P.O. Box 51, H--4001 Debrecen (Hungary)] [Institute of Nuclear Research of the Hungarian Academy of Sciences, Bem ter 18/c, P.O. Box 51, H--4001 Debrecen (Hungary); Plessas, W. [Institute for Theoretical Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria)] [Institute for Theoretical Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

1996-07-01

287

Coulomb gauge confinement in the heavy quark limit

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

288

Strong nuclear couplings as a source of Coulomb rainbow suppression

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

289

Finsler-type modification of the Coulomb law

Finsler geometry is a natural generalization of pseudo-Riemannian geometry. It can be motivated e.g. by a modified version of the Ehlers-Pirani-Schild axiomatic approach to space-time theory. Also, some scenarios of quantum gravity suggest a modified dispersion relation which could be phrased in terms of Finsler geometry. On a Finslerian spacetime, the Universality of Free Fall is still satisfied but Local Lorentz Invariance is violated in a way not covered by standard Lorentz Invariance Violation schemes. In this paper we consider a Finslerian modification of Maxwell's equations. The corrections to the Coulomb potential and to the hydrogen energy levels are computed. We find that the Finsler metric corrections yield a splitting of the energy levels. Experimental data provide bounds for the Finsler parameters.

Yakov Itin; Claus Lämmerzahl; Volker Perlick

2014-12-29

290

"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

291

Coulomb Repulsion in Miniature Ion Mobility Spectrometry

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

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

1999-08-08

292

Hyperspherical Coulomb spheroidal basis in the Coulomb three-body problem

A hyperspherical Coulomb spheroidal (HSCS) representation is proposed for the Coulomb three-body problem. This is a new expansion in the set of well-known Coulomb spheroidal functions. The orthogonality of Coulomb spheroidal functions on a constant-hyperradius surface {rho} = const rather than on a constant-internuclear-distance surface R = const, as in the traditional Born-Oppenheimer approach, is a distinguishing feature of the proposed approach. Owing to this, the HSCS representation proves to be consistent with the asymptotic conditions for the scattering problem at energies below the threshold for three-body breakup: only a finite number of radial functions do not vanish in the limit of {rho}{yields}{infinity}, with the result that the formulation of the scattering problem becomes substantially simpler. In the proposed approach, the HSCS basis functions are considerably simpler than those in the well-known adiabatic hyperspherical representation, which is also consistent with the asymptotic conditions. Specifically, the HSCS basis functions are completely factorized. Therefore, there arise no problems associated with avoided crossings of adiabatic hyperspherical terms.

Abramov, D. I., E-mail: abramov472007@yandex.ru [St. Petersburg State University, Fock Institute of Physics (Russian Federation)

2013-02-15

293

NASA Astrophysics Data System (ADS)

The role of Coulomb disorder, either of extrinsic origin or introduced by dopant ions in undoped and lightly doped cuprates, is studied. We demonstrate that charged surface defects in an insulator lead to a Gaussian broadening of the angle-resolved photoemisson spectroscopy (ARPES) lines. The effect is due to the long-range nature of the Coulomb interaction. A tiny surface concentration of defects about a fraction of one percent is sufficient to explain the line broadening observed in Sr2CuO2Cl2 , La2CuO4 , and Ca2CuO2Cl2 . Due to the Coulomb screening, the ARPES spectra evolve dramatically with doping, changing their shape from a broad Gaussian form to narrow Lorentzian ones. To understand the screening mechanism and the line-shape evolution in detail, we perform Hartree-Fock simulations with random positions of surface defects and dopant ions. To check validity of the model we calculate the nuclear quadrupole resonance (NQR) line shapes as a function of doping and reproduce the experimentally observed NQR spectra. Our study also indicates opening of a substantial Coulomb gap at the chemical potential. For a surface CuO2 layer the value of the gap is on the order of 10 meV while in the bulk it is reduced to the value about a few meV.

Chen, Wei; Khaliullin, Giniyat; Sushkov, Oleg P.

2009-09-01

294

Coulomb Collision in Plasmas with Maxwellian and Non-Maxwellian Distributions

NASA Astrophysics Data System (ADS)

Recently, the tokamak experiments show that the measured cross-field diffusion and thermal conductivity can be well below the levels of conventional neoclassical transport theory in the core of reversed magnetic shear plasma. It is necessary to restudy Coulomb collision that is a basic process of the plasma kinetics. The customary approaches use the scattering angle instead of momentum transfer to describe the Coulomb collisions in plasma. It is found that the cutoff on small scattering angle does not fulfill Debye shielding theory. It is reasonable to consider that the collisions are effective only if the kinetic energy is greater than the Coulomb potential energy, and/or the interaction distance is shorter than the Debye radius. It is shown that the Coulomb logarithm should reduce by half according to the cutoff on the velocity increment. The probability function is derived for a type of non-Maxwellian scatters and the completed Fokker-Planck coefficients is obtained for inverse-square force. It is found that the high-energy tail of the distribution function of field particle reduces Fokker-Planck coefficients too. Those effects will affect plasma relaxation times, transport coefficients, and coupling property. These results could partially explain the above-mentioned phenomena and modify the conventional transport theory.

Li, Ding

2000-10-01

295

Dirac Hamiltonian with superstrong Coulomb field

We consider the quantum-mechanical problem of a relativistic Dirac particle moving in the Coulomb field of a point charge $Ze$. In the literature, it is often declared that a quantum-mechanical description of such a system does not exist for charge values exceeding the so-called critical charge with $% Z=\\alpha ^{-1}=137$ based on the fact that the standard expression for the lower bound state energy yields complex values at overcritical charges. We show that from the mathematical standpoint, there is no problem in defining a self-adjoint Hamiltonian for any value of charge. What is more, the transition through the critical charge does not lead to any qualitative changes in the mathematical description of the system. A specific feature of overcritical charges is a non uniqueness of the self-adjoint Hamiltonian, but this non uniqueness is also characteristic for charge values less than the critical one (and larger than the subcritical charge with $Z=(\\sqrt{3}% /2)\\alpha ^{-1}=118$). We present the spectra and (generalized) eigenfunctions for all self-adjoint Hamiltonians. The methods used are the methods of the theory of self-adjoint extensions of symmetric operators and the Krein method of guiding functionals. The relation of the constructed one-particle quantum mechanics to the real physics of electrons in superstrong Coulomb fields where multiparticle effects may be of crucial importance is an open question.

B. L. Voronov; D. M. Gitman; I. V. Tyutin

2006-11-21

296

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

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

2000-07-15

297

Coulomb Systems with Ideal Dielectric Boundaries: Free Fermion Point and Universality

A two-component Coulomb gas confined by walls made of ideal dielectric material is considered. In two dimensions at the special inverse temperature $\\beta = 2$, by using the Pfaffian method, the system is mapped onto a four-component Fermi field theory with specific boundary conditions. The exact solution is presented for a semi-infinite geometry of the dielectric wall (the density profiles, the correlation functions) and for the strip geometry (the surface tension, a finite-size correction of the grand potential). The universal finite-size correction of the grand potential is shown to be a consequence of the good screening properties, and its generalization is derived for the conducting Coulomb gas confined in a slab of arbitrary dimension $\\ge 2$ at any temperature.

B. Jancovici; L. Šamaj

2001-01-04

298

NASA Astrophysics Data System (ADS)

Hideki Yukawa, Sin-itiro Tomonaga and Shoichi Sakata pioneered nuclear and particle physics and left enduring legacies. Their friendly collaboration and severe competition laid the foundation to bring up the active postwar generation of nuclear and particle physicists in Japan. In this presentation we illustrate milestones of nuclear and particle physics in Japan from 1930's to mid-1940's which have been clarified in Yukawa Hall Archival Library, Tomonaga Memorial Room and Sakata Memorial Archival Library.

Konuma, Michiji; Bando, Masako; Gotoh, Haruyoshi; Hayakawa, Hisao; Hirata, Kohji; Ito, Kazuyuki; Ito, Kenji; Kanaya, Kazuyuki; Konagaya, Daisuke; Kugo, Taichiro; Namba, Chusei; Nishitani, Tadashi; Takaiwa, Yoshinobu; Tanabashi, Masaharu; Tanaka, Kio; Tanaka, Sho; Ukegawa, Fumihiko; Yoshikawa, Tadashi

299

Screening long-range Coulomb interactions in 2D hole systems using a bilayer heterostructure

We present a technique for studying the effect of screening long-range Coulomb interactions in a 2D system using a bilayer heterostructure. It allows us to vary the distance between a 2D system and a screening ground plane in the same sample and cooldown, and hence without changing the disorder potential. We implement this technique in a 2D hole system in

L. H. Ho; W. R. Clarke; R. Danneau; O. Klochan; A. P. Micolich; M. Y. Simmons; A. R. Hamilton; M. Pepper; D. A. Ritchie

2008-01-01

300

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

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. [Departamento de Física, Universidad Nacional del Sur, 8000 Bahía Blanca, Buenos Aires (Argentina)] [Departamento de Física, Universidad Nacional del Sur, 8000 Bahía Blanca, Buenos Aires (Argentina); Zaytsev, S. A. [Physics Department, Pacific National University, Khabarovsk 680035 (Russian Federation)] [Physics Department, Pacific National University, Khabarovsk 680035 (Russian Federation); Ancarani, L. U. [Théorie, Modélisation, Simulation, SRSMC, UMR CNRS 7565, Université de Lorraine, 57078 Metz (France)] [Théorie, Modélisation, Simulation, SRSMC, UMR CNRS 7565, Université de Lorraine, 57078 Metz (France)

2014-05-15

301

Algebraic approach to quasi-exact solutions of the Dirac-Coulomb problem

NASA Astrophysics Data System (ADS)

The Dirac equation in the presence of Coulomb electrostatic potential is solved and the quasi-exact solutions are obtained via osp(2, 2) algebraization. The Lie-algebraic approach of quasi-exact solvability is applied to the problem and by constructing the matrix representation of the problem, the energy spectrum and thereby the corresponding spinor wave functions are obtained in terms of the polynomial components of osp(2, 2) superalgebra.

Panahi, H.; Baradaran, M.

2013-04-01

302

Equation satisfied by the energy-density functional for electron-electron mutual Coulomb repulsion

NASA Astrophysics Data System (ADS)

It is shown that the electron-electron mutual Coulomb repulsion energy-density functional Vee?[?] satisfies the equation Vee?[?N1]-Vee?[?N-1?]=?d3r(?Vee?[?N1])/(??N1(r))[?N1(r)-?N-1?(r)],where ?N1(r) and ?N-1?(r) are N-electron and (N-1)-electron densities determined from the same adiabatic scaled external potential of the N-electron system at coupling strength ?.

Joubert, Daniel P.

2011-10-01

303

The Higgs boson resonance width from a chiral Higgs-Yukawa model on the lattice

The Higgs boson is a central part of the electroweak theory and is crucial to generate masses for quarks, leptons and the weak gauge bosons. We use a 4-dimensional Euclidean lattice formulation of the Higgs-Yukawa sector of the electroweak model to compute physical quantities in the path integral approach which is evaluated by means of Monte Carlo simulations thus allowing for fully non perturbative calculations. The chiral symmetry of the model is incorporated by using the Neuberger overlap Dirac operator. The here considered Higgs-Yukawa model does not involve the weak gauge bosons and furthermore, only a degenerate doublet of top- and bottom quarks are incorporated. The goal of this work is to study the resonance properties of the Higgs boson and its sensitivity to the strength of the quartic self coupling.

Philipp Gerhold; Karl Jansen; Jim Kallarackal

2012-03-20

304

Measurement of the top-Higgs Yukawa coupling at a linear e+e- collider

NASA Astrophysics Data System (ADS)

Understanding the mechanism of electroweak symmetry breaking and the origin of boson and fermion masses is among the most pressing questions raised in contemporary particle physics. If these issues involve one (several) Higgs boson(s), a precise measurement of all its (their) properties will be of prime importance. Among those, the Higgs coupling to matter fermions (the Yukawa coupling). At a linear collider, the process e+e-?tt¯H will allow a direct measurement of the top-Higgs Yukawa coupling. We present a realistic feasibility study of the measurement in the context of the TESLA collider. Four channels are studied and the analysis is repeated for several Higgs mass values within the range 120 200 GeV/c 2.

Gay, A.

2007-01-01

305

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

306

Revisiting Top-Bottom-Tau Yukawa Unification in Supersymmetric Grand Unified Theories

Third family Yukawa unification, as suggested by minimal SO(10) unification, is revisited in light of recent experimental measurements and theoretical progress. We characterize unification in a semi-model-independent fashion, and conclude that finite $b$ quark mass corrections from superpartners must be nonzero, but much smaller than naively would be expected. We show that a solution that does not require cancellations of dangerously large tanbeta effects in observables implies that scalar superpartner masses should be substantially heavier than the Z scale, and perhaps inaccessible to all currently approved colliders. On the other hand, gauginos must be significantly lighter than the scalars. We demonstrate that a spectrum of anomaly-mediated gaugino masses and heavy scalars works well as a theory compatible with third family Yukawa unification and dark matter observations.

Kazuhiro Tobe; James D. Wells

2003-01-03

307

Yukawa effects on the clock onboard a drag-free satellite

The Yukawa correction to the Newtonian gravitational force is accepted as a parameterization of deviations from the inverse-square law of gravity which might be caused by new physics beyond the standard model of particles and the general theory of relativity. We investigate these effects on the clock onboard a drag-free satellite: dynamics of the satellite and influence on the time transfer link. We find the Yukawa signal in the time transfer is much harder to detect with current state of clocks than those effects on the dynamics, especially the secular change of periastron, by laser ranging in the case of an artificial Earth satellite carrying a frequency standard with an orbit of $a=10^7$\\,m and $e=0.01$.

Xue-Mei Deng; Yi Xie

2013-03-05

308

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

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

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

2012-07-27

309

Quantum Dynamics of Biological Plasma in the External Coulomb Field

NASA Astrophysics Data System (ADS)

A quantum solution to the truncated Fisher-Kolmogorov-Petrovskii-Piskunov equation with Coulomb convection and linear diffusion is derived. The quantum radiation of biological systems, individual microorganisms (cells, bacteria), and dust plasma particles in the Coulomb field is studied using the foregoing solution.

Lasukov, V. V.; Lasukova, T. V.; Lasukova, O. V.

2013-10-01

310

The Effect of coulomb friction and stiction on force control

We have studied the effect of Coulomb friction and stiction on force control with integral feedback. The force is applied through a compliant transmission by a velocity-controlled motor. Our results show that stiction can cause the applied force to enter a limit cycle. Coulomb friction can extend the system stability bounds but may lead to an input-dependent stability. Under certain

William T. Townsend

1987-01-01

311

Parametrization of the Paris N-N potential

In view of practical nuclear structure calculations the Paris N-N potential is parametrized in a simple analytical form. This parametrization consists of a regularized discrete superposition of Yukawa-type terms. Results for phase shifts and deuteron parameters are presented as well as nuclear matter binding energy obtained with this potential.

Lacombe, M.; Loiseau, B.; Richard, J.M.; Vinh Mau, R.; Cote, J.; Pires, P.; de Tourreil, R.

1980-03-01

312

Parametrization of the Paris N-N potential

In view of practical nuclear structure calculations the Paris N-N potential is parametrized in a simple analytical form. This parametrization consists of a regularized discrete superposition of Yukawa-type terms. Results for phase shifts and deuteron parameters are presented as well as nuclear matter binding energy obtained with this potential.

M. Lacombe; B. Loiseau; J. M. Richard; R. Vinh Mau; J. Côté; P. Pirès; R. de Tourreil

1980-01-01

313

Experimental realization of a Coulomb blockade refrigerator

NASA Astrophysics Data System (ADS)

We present an experimental realization of a Coulomb blockade refrigerator (CBR) based on a single-electron transistor (SET). In the present structure, the SET island is interrupted by a superconducting inclusion to permit charge transport while preventing heat flow. At certain values of the bias and gate voltages, the current through the SET cools one of the junctions. The measurements follow the theoretical model down to ˜80 mK, which was the base temperature of the current measurements. The observed cooling increases rapidly with decreasing temperature, in agreement with the theory, reaching about a 15 mK drop at the base temperature. The CBR appears as a promising electronic cooler at temperatures well below 100 mK.

Feshchenko, A. V.; Koski, J. V.; Pekola, J. P.

2014-11-01

314

Temperature-dependent Coulomb excitations in silicene

NASA Astrophysics Data System (ADS)

The temperature-dependent Coulomb screening and excitation spectrum of electrons in silicene are studied by the tight-binding model and the random-phase approximation. With the spin-orbit interaction, monolayer silicene is a narrow-gap semiconductor. At finite temperatures, the interplay between the intraband and interband transitions could lead to an undamped plasmon mode at low frequencies. The plasmon mode only exists in a limited region of temperature and momentum, corresponding to the constrained gap transition. Beyond that region, another damped plasmon mode dominates the excitation spectrum. The drastic change in the plasmon behavior might be observed experimentally, which could allow for the identification of the spin-orbit energy gap.

Wu, J. Y.; Chen, S. C.; Lin, M. F.

2014-12-01

315

Coulomb interaction of acceptors in Cd{sub 1?x}Mn{sub x}Te/CdTe quantum dot

The investigation on the effect of confining potential like isotropic harmonic oscillator type potential on the binding and the Coulomb interaction energy of the double acceptors in the presence of magnetic field in a Cd{sub 1?x}Mn{sub x}Te/CdTe Spherical Quantum Dot has been made for the Mn ion composition x=0.3 and compared with the results obtained from the square well type potential using variational procedure in the effective mass approximation.

Kalpana, P.; Nithiananthi, P., E-mail: kjkumar-gri@rediffmail.com; Jayakumar, K., E-mail: kjkumar-gri@rediffmail.com [Department of Physics, Gandhigram Rural University, Gandhigram-624302, TamilNadu (India); Reuben, A. Merwyn Jasper D. [Department of Physics, School of Engineering, Saveetha University, Thandalam, Chennai- 600104, TamilNadu (India)

2014-04-24

316

Cholesteric order in systems of helical Yukawa rods

We consider the interaction potential between two chiral rod-like colloids which consist of a thin cylindrical backbone decorated with a helical charge distribution on the cylinder surface. For sufficiently slender coiled rods a simple scaling expression is derived which links the chiral `twisting' potential to the intrinsic properties of the particles such as the coil pitch, charge density and electrostatic screening parameter. To predict the behavior of the macroscopic cholesteric pitch we invoke a simple second-virial theory generalized for weakly twisted director fields. While the handedness of the cholesteric phase for weakly coiled rods is always commensurate with that of the internal coil, more strongly coiled rods display cholesteric order with opposite handedness. The correlation between the symmetry of the microscopic helix and the macroscopic cholesteric director field is quantified in detail. Mixing helices with sufficiently disparate lengths and coil pitches gives rise to a demixing of the uniform cholesteric phase into two fractions with a different macroscopic pitch. Our findings are consistent with experimental results and could be helpful in interpreting experimental observations in systems of cellulose and chitin microfibers, DNA and {\\em fd} virus rods.

H. H. Wensink; G. Jackson

2010-04-13

317

Structural and energetic properties of molecular Coulomb crystals in a surface-electrode ion trap

NASA Astrophysics Data System (ADS)

Cold molecular ions are of great interest for applications in cold collision studies, chemistry, precision spectroscopy and quantum technologies. In this context, sympathetic cooling of molecular ions by the interaction with laser-cooled atomic ions is a powerful method to cool their translational motion and achieve translational temperatures in the millikelvin range. Recently, we implemented this method in a surface-electrode ion trap. The flexibility in shaping the trapping potentials offered by the surface-electrode structure enabled us to generate planar bicomponent Coulomb crystals and spatially separate the molecular from the atomic ions. Here, we present a detailed description of the fabrication and simulation of the trap as well as a theoretical and experimental investigation of the structural and energetic properties of the Coulomb crystals obtained in the device. We discuss in more detail the separation of different ion species using static electric fields and explore the effects of trap anharmoncities on the shape of bicomponent crystals.

Mokhberi, A.; Willitsch, S.

2015-04-01

318

Coulomb gaps in one-dimensional spin-polarized electron systems

NASA Astrophysics Data System (ADS)

We investigate the density of states (DOS) near the Fermi energy of one-dimensional spin-polarized electron systems in the quantum regime where the localization length is comparable to or larger than the interparticle distance. The Wigner lattice gap of such a system, in the presence of weak disorder, can occur precisely at the Fermi energy, coinciding with the Coulomb gap in position. The interplay between the two is investigated by treating the long-range Coulomb interaction and the random disorder potential in a self-consistent Hartree-Fock approximation. The DOS near the Fermi energy is found to be well described by a power law, the exponent of which decreases with increasing disorder strength.

Jeon, Gun Sang; Choi, M. Y.; Yang, S.-R. Eric

1996-09-01

319

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

320

Nonequilibrium relaxation and aging scaling of the Coulomb and Bose glass

NASA Astrophysics Data System (ADS)

We employ Monte Carlo simulations to investigate the nonequilibrium relaxation properties of the two- and three-dimensional Coulomb glass with different long-range repulsive interactions. Specifically, we explore the aging scaling laws in the two-time density autocorrelation function. We find that, in the time window and parameter range accessible to us, the scaling exponents are not universal, depending on the filling fraction and temperature: As either the temperature decreases or the filling fraction deviates more from half filling, the exponents reflect markedly slower relaxation kinetics. In comparison with a repulsive Coulomb potential, appropriate for impurity states in strongly disordered semiconductors, we observe that, for logarithmic interactions, the soft pseudogap in the density of states is considerably broader, and the dependence of the scaling exponents on external parameters is much weaker. The latter situation is relevant for flux creep in the disorder-dominated Bose glass phase of type-II superconductors subject to columnar pinning centers.

Shimer, Matthew T.; Täuber, Uwe C.; Pleimling, Michel

2014-09-01

321

Scattering and stopping of swift diatomic molecules under Coulomb explosion

The scattering and stopping of the fragments of a fast diatomic molecule under Coulomb explosion has been analyzed theoretically. The central assumption in the scheme is the dominance of Coulomb explosion, while electronic stopping (including wake forces) and elastic scattering are treated as perturbations. Charge exchange has been neglected. Coulomb images of penetration phenomena are heavily distorted. For small penetrated layer thicknesses, images appear contracted in the direction of the molecular axis, and expanded perpendicular to it. This distortion is described quantitatively by a linear transformation. General expressions have been derived for the effect of continuous and stochastic forces on the distribution of fragment velocities from Coulomb explosion (the ring pattern''). Moreover, relations have been found that allow to scale velocity distributions valid in the absence of Coulomb explosion into distributions allowing for Coulomb explosion. Applications concern the shift in ring pattern due to electronic stopping, the lateral broadening due to multiple scattering and the effect of zero-point motion on the Coulomb image of a molecule. 14 refs., 5 figs.

Sigmund, P. (Odense Univ. (Denmark). Dept. of Physics Argonne National Lab., IL (United States))

1991-01-01

322

Quantum electrodynamics without potentials

A scheme is proposed for quantizing electrodynamics in terms of the ; electromagnetic fields without the introduction of potentials. The equations are ; relativistically covariant and do not require the introduction of unphysical ; states and an indefinite metric. Calculations carried out according to ; quantization methods in the Coulomb or Lorentz gages are justified in this ; formalism. The

Stanley Mandelstam

1962-01-01

323

Renormalization in the Coulomb gauge and order parameter for confinement in QCD

NASA Astrophysics Data System (ADS)

Renormalization of the Coulomb gauge is studied in the phase space formalism, where one integrates over both the vector potential A, and its canonical momentum ? as well as the usual Faddeev-Popov auxiliary fields. A proof of renormalizability is not attempted. Instead, algebraic identities are derived from BRST invariance which renormalization must satisfy if the Coulomb gauge is renormalizable. In particular, a Ward identity is derived which holds at a fixed time t, and which is an analog of Gauss's law in the BRST formalism, and which we call the Gauss-BRST identity. The familiar Zinn-Justin equation results when this identity is integrated over all t. It is shown that in the Coulomb gauge, g2D0.0 is a renormalization-group invariant, as is its instantaneous part V( R), which we call the color-Coulomb potential. (Here D0.0 is the time-time component of the gluon propagator.) The contribution of V( R) to the Wilson loop exponentiates. It is proposed that the string tension defined by KCoul = lim R?? CV( R)/ R may serve as an order parameter for confinement, where C = (2 N) -1( N2 - 1) for SU( N) gauge theory. A remarkable consequence of the above-mentioned Ward identity is that the Fourier transform V( k) of V( R) is of the product form V( k) = [ k2D C,C ? ( k)] 2L( k) , where D C,C ? ( k) is the ghost propagator, and L( k) is a correlation function of longitudinal gluons. This exact equation combines with a previous analysis of the Gribov problem according to which k2D C,C ? ( k) diverges at k = 0 , to provide a scenario for confinement.

Zwanziger, Daniel

1998-05-01

324

Antilocalization of Coulomb Blockade in a Ge/Si Nanowire

NASA Astrophysics Data System (ADS)

The distribution of Coulomb blockade peak heights as a function of magnetic field is investigated experimentally in a Ge/Si nanowire quantum dot. Strong spin-orbit coupling in this hole-gas system leads to antilocalization of Coulomb blockade peaks, consistent with theory. In particular, the peak height distribution has its maximum away from zero at zero magnetic field, with an average that decreases with increasing field. Magnetoconductance in the open-wire regime places a bound on the spin-orbit length (lso<20 nm), consistent with values extracted in the Coulomb blockade regime (lso<25 nm).

Higginbotham, A. P.; Kuemmeth, F.; Larsen, T. W.; Fitzpatrick, M.; Yao, J.; Yan, H.; Lieber, C. M.; Marcus, C. M.

2014-05-01

325

Scattering of charged particles by a multicenter potential

Exact expressions are obtained for the amplitude and elastic cross section in the case of scattering of charged particles by a multicenter pseudopotential that includes the Coulomb potential and an arbitrary number of short-range potentials (modeled by zero-range potentials). Asymptotic limits are calculated and explicit expressions are found for the amplitudes of scattering by few-nucleon complexes modeled by superpositions of the Coulomb potential and purely point potentials.

Gerasimov, O.I.; Stienko, A.G.

1994-10-01

326

Towards realistic supersymmetric spectra and Yukawa textures from intersecting branes

We study the possible phenomenology of a three-family Pati-Salam model constructed from intersecting D6-branes in type IIA string theory on the T{sup 6}/(Z{sub 2}xZ{sub 2}) orientifold with some desirable semirealistic features. In the model, tree-level gauge-coupling unification is achieved automatically at the string scale, and the gauge symmetry may be broken to the standard model (SM) close to the string scale. The small number of extra chiral exotic states in the model may be decoupled via the Higgs mechanism and strong dynamics. We calculate the possible supersymmetry breaking soft terms and the corresponding low-energy supersymmetric particle spectra which may potentially be tested at the Large Hadron Collider (LHC). We find that for the viable regions of the parameter space the lightest CP-even Higgs boson mass usually satisfies m{sub H}{<=}120 GeV, and the observed dark matter density may be generated. Finally, we find that it is possible to obtain correct SM quark masses and mixings, and the tau lepton mass at the unification scale. Additionally, neutrino masses and mixings may be generated via the seesaw mechanism. Mechanisms to stabilize the open and closed-string moduli, which are necessary for the model to be truly viable and to make definite predictions are discussed.

Chen Chingming; Mayes, V. E. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Li Tianjun [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080 (China); Nanopoulos, D. V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics, Texas A and M University, College Station, TX 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States) and Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)

2008-06-15

327

Analysis of {alpha}-induced reactions on {sup 151}Eu below the Coulomb barrier

Novel measurements of ({alpha},{gamma}) and ({alpha},n) reaction cross sections on the target nucleus {sup 151}Eu, close to the reaction thresholds, support the choice of recently proposed parameters of the {alpha}-particle optical model potential below the Coulomb barrier. A better understanding of the {alpha}-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were measured but not considered within a former model analysis. On this basis we have tentatively assigned a modified J{sup {pi}}=9{sup -} spin and parity to the 22.7-h isomer in {sup 154}Tb.

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

2011-01-15

328

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

329

Multilevel Monte Carlo simulation of Coulomb collisions

NASA Astrophysics Data System (ADS)

We present a new, for plasma physics, highly efficient multilevel Monte Carlo numerical method for simulating Coulomb collisions. The method separates and optimally minimizes the finite-timestep and finite-sampling errors inherent in the Langevin representation of the Landau-Fokker-Planck equation. It does so by combining multiple solutions to the underlying equations with varying numbers of timesteps. For a desired level of accuracy ?, the computational cost of the method is O(?-2) or O(?-2(), depending on the underlying discretization, Milstein or Euler-Maruyama respectively. This is to be contrasted with a cost of O(?-3) for direct simulation Monte Carlo or binary collision methods. We successfully demonstrate the method with a classic beam diffusion test case in 2D, making use of the Lévy area approximation for the correlated Milstein cross terms, and generating a computational saving of a factor of 100 for ?=10-5. We discuss the importance of the method for problems in which collisions constitute the computational rate limiting step, and its limitations.

Rosin, M. S.; Ricketson, L. F.; Dimits, A. M.; Caflisch, R. E.; Cohen, B. I.

2014-10-01

330

Interatomic Coulombic Decay in two coupled Quantum Wells

Interatomic coulombic decay (ICD) is a relaxation process induced by electronic correlation. In this work we study the ICD process in a two coupled Quantum wells (QWs) nano-structure. We study a simple one-dimensional effective potential using experimental parameters of the semiconductor QW layers i.e. using the single band effective-mass approximation . In our calculations we consider the discontinuity of the effective mass of the electron in each of the QW layers. We control the ICD lifetime by changing the distance between the two wells. The expected overall trend is a decrease of ICD lifetime with a decrease in the distance between the wells. We show that the distance can be tuned such that the emitted ICD electron is trapped in a meta-stable state in the continuum i.e. a one electron resonance state. This causes the life time of the ICD to be an order of magnitude smaller even in very long distances, and improves the efficiency of the ICD. For the ICD to be dominant decay mechanism it must prevail over all other possible competitive decay processes. We have found that the lifetime of the ICD is on the timescale of picoseconds. Therefore, based on our results we can design an experiment that will observe the ICD phenomenon in QWs nano-structure for the first time. This work can lead to designing a wavelength sensitive detector which is efficient even in low intensities.

Tamar Goldzak; Liron Gantz; Ido Gilary; Gad Bahir; Nimrod Moiseyev

2015-02-25

331

Multifragmentation: Surface and Coulomb instabilities of sheets, bubbles, and donuts

Disks, bubbles, and donuts have been observed in dynamical calculations of heavy ion collisions. These shapes are subject to a variety of surface and Coulomb instabilities. These instabilities are identified and analyzed in terms of their relevance to multifragmentation.

Moretto, L.G.; Tso, Kin; Wozniak, G.J.

1993-08-01

332

Angular aspects of electron correlation and the Coulomb hole

NASA Astrophysics Data System (ADS)

The simple physical picture of the Coulomb hole due to Coulson and Neilson has been extended to reveal the shape of the Coulomb hole in the ground state of helium. The approach is based on a pair distribution function h(r12,r1,?) which depends on the position of a reference electron and the angle between the nucleus, the reference electron, and a second electron. Following a discussion of the properties of this new function, the angular features of the Coulomb hole are studied in terms of the difference between the values of the pair distribution function obtained from good approximations to the exact and to the Hartree-Fock wave functions. The Coulomb hole is essentially spherically symmetric when the reference electron is close to the nucleus. As the reference electron is removed to larger radial distances, substantial polarization appears. The polarization is greater away from the nucleus than toward the nucleus.

Boyd, Russell J.; Yee, Main C.

1982-10-01

333

Indirect Coulomb energy for two-dimensional atoms

In this paper we provide a family of lower bounds on the indirect Coulomb energy for atomic and molecular systems in two dimensions in terms of a functional of the single particle density with gradient correction terms.

Benguria, Rafael D.; Tusek, Matej [Departamento de Fisica, P. Universidad Catolica de Chile Casilla 306, Santiago 22 (Chile)

2012-09-15

334

We propose a new mass matrix ansatz: At the grand unified (GU) scale, the standard model (SM) Yukawa coupling matrix elements are integer powers of the square root of the GU gauge coupling constant \\varepsilon \\equiv \\sqrt{\\alpha_{\\text{GU}}}, multiplied by order unity random complex numbers. It relates the hierarchy of the SM ermion masses and quark mixings to the gauge coupling constants, greatly reducing the SM parameters, and can give good fitting results of the SM fermion mass, quark mixing and CP violation parameters. This is a neat but very effective ansatz.

Yong-Chao Zhang; De-Hai Zhang

2010-06-05

335

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

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

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

2007-03-01

336

Yukawa textures in string unified models with SU(4){circle_times}O(4) symmetry

We discuss the origin of Yukawa textures in the string-inspired and string-derived models based on the gauge group SU(4){circle_times}SU(2){sub L}{circle_times}SU(2){sub R} supplemented by a U(1){sub X} gauged family symmetry. The gauge symmetries are broken down to those of the minimal supersymmetric standard model which is the effective theory below 10Â¹â¶ GeV. The combination of the U(1){sub X} family symmetry and

B. C. Allanach; S. F. King; G. K. Leontaris; S. Lola

1997-01-01

337

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

338

Collective Modes in Strongly Correlated Yukawa Liquids: Waves in Dusty Plasmas

We determine the collective mode structure of a strongly correlated Yukawa fluid, with the purpose of analyzing wave propagation in a strongly coupled dusty plasma. We identify a longitudinal plasmon and a transverse shear mode. The dispersion is characterized by a low-k acoustic behavior, a frequency maximum well below the plasma frequency, and a high-k merging of the two modes around the Einstein frequency of localized oscillations. The damping effect of collisions between neutrals and dust grains is estimated. (c) 2000 The American Physical Society.

Kalman, G. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States)] [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States); DeWitt, H. E. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2000-06-26

339

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

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

Khrustalyov, Yu V; Vaulina, O S

2012-04-01

340

Yukawas and discrete symmetries in F-theory compactifications without section

In the case of F-theory compactifications on genus-one fibrations without section there are naturally appearing discrete symmetries, which we argue to be associated to geometrically massive U(1) gauge symmetries. These discrete symmetries are shown to induce non-trivial selection rules for the allowed Yukawa couplings in SU(N) gauge theories. The general discussion is exemplified using a concrete Calabi-Yau fourfold realizing an SU(5) GUT model. We observe that M2 instanton effects appear to play a key role in the generation of new superpotential terms and in the dynamics close to phase transition loci.

Iñaki García-Etxebarria; Thomas W. Grimm; Jan Keitel

2014-09-30

341

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

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

2002-09-01

342

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

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

Khrustalyov, Yu. V., E-mail: yuri.khrustalyov@gmail.com; Vaulina, O. S. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2013-05-15

343

Nuclear Fusion induced by Coulomb Explosion of Heteronuclear Clusters

We propose a new mechanism for the production of high-energy ( E>3 keV) deuterons, suitable to induce dd nuclear fusion, based on multielectron ionization and Coulomb explosion of heteronuclear deuterium containing molecular clusters, e.g., (D2O)n, in intense ( 1016-2×1018 W\\/cm2) laser fields. Cluster size equations for E, in conjunction with molecular dynamics simulations, reveal important advantages of Coulomb explosion of

Isidore Last; Joshua Jortner

2001-01-01

344

Renormalization in Coulomb-gauge QCD within the Lagrangian formalism

NASA Astrophysics Data System (ADS)

We study renormalization of Coulomb-gauge QCD within the Lagrangian, second-order, formalism. We derive a Ward identity and the Zinn-Justin equation, and, with the help of the latter, we give a proof of algebraic renormalizability of the theory. Through diagrammatic analysis, we show that, in the strict Coulomb gauge, g2D00 is invariant under renormalization. (D00 is the time-time component of the gluon propagator.)

Niégawa, A.

2006-08-01

345

Diffusion and Coulomb separation of ions in dense matter.

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

346

Laser triggered Coulomb explosion of nanoscale symmetric targets

Approximate kinetic solutions are found for Coulomb explosions of nanostructures in plane (thin foils), cylindrical (nanowires/tubes) and spherical (nanospheres/shells) geometries. The distribution function, mean velocity, density distribution, as well as the energy spectra for accelerated ions are derived. The proposed kinetic model describes physics of multiple flows that occur during Coulomb explosion. Comparison with particle-in-cell numerical simulations shows good agreement with analytical results.

Kovalev, V. F. [Institute for Mathematical Modelling, Russian Academy of Sciences, Moscow 125047 (Russian Federation); Popov, K. I.; Rozmus, W. [Theoretical Physics Institute, University of Alberta, Edmonton T6G 2J1, Alberta (Canada); Bychenkov, V. Yu. [Theoretical Physics Institute, University of Alberta, Edmonton T6G 2J1, Alberta (Canada); P. N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation)

2007-05-15

347

Propagation of Coulomb stress uncertainties in physics-based aftershock models

NASA Astrophysics Data System (ADS)

Stress transfer between earthquakes is recognized as a fundamental mechanism governing aftershock sequences. A common approach to relate stress changes to seismicity rate changes is the rate-and-state constitutive law developed by Dieterich: these elements are the foundation of Coulomb-rate-and-state (CRS) models. Despite the successes of Coulomb hypothesis and of the rate-and-state formulation, such models perform worse than statistical models in an operational forecasting context: one reason is that Coulomb stress is subject to large uncertainties and intrinsic spatial heterogeneity. In this study, we characterize the uncertainties in Coulomb stress inherited from different physical quantities and assess their effect on CRS models. We use a Monte Carlo method and focus on the following aspects: the existence of multiple receiver faults; the stress heterogeneity within grid cells, due to their finite size; and errors inherited from the coseismic slip model. We study two well-recorded sequences from different tectonic settings: the Mw = 6.0 Parkfield and the Mw= 9.0 Tohoku earthquakes. We find that the existence of multiple receiver faults is the most important source of intrinsic stress heterogeneity, and CRS models perform significantly better when this variability is taken into account. The choice of slip model also generates large uncertainties. We construct an ensemble model based on published slip models and find that it outperforms individual models. Our findings highlight the importance of identifying sources of errors and quantifying confidence boundaries in the forecasts; moreover, we demonstrate that consideration of stress heterogeneity and epistemic uncertainty has the potential to improve the performance of operational forecasting models.

Cattania, Camilla; Hainzl, Sebastian; Wang, Lifeng; Roth, Frank; Enescu, Bogdan

2014-10-01

348

Aftershock triggering by complete Coulomb stress changes

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, Debi; Gomberg, J.; Bodin, P.

2002-01-01

349

Upper and lower Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model

Motivated by the advent of the Large Hadron Collider the aim of the present work is the non-perturbative determination of the cutoff-dependent upper and lower mass bounds of the Standard Model Higgs boson based on first principle calculations, in particular not relying on additional information such as the triviality property of the Higgs-Yukawa sector or indirect arguments like vacuum stability considerations. For that purpose the lattice approach is employed to allow for a non-perturbative investigation of a chirally invariant lattice Higgs-Yukawa model, serving here as a reasonable simplification of the full Standard Model, containing only those fields and interactions which are most essential for the intended Higgs boson mass determination. These are the complex Higgs doublet as well as the top and bottom quark fields and their mutual interactions. To maintain the chiral character of the Standard Model Higgs-fermion coupling also on the lattice, the latter model is constructed on the basis of the Neuberger overlap operator, obeying then an exact global lattice chiral symmetry.

P. Gerhold

2010-02-12

350

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

351

Relativistic bound-state problem in the light-front Yukawa model

We study the renormalization problem on the light front for the two-fermion bound state in the (3+1)-dimensional Yukawa model, working within the lowest-order Tamm-Dancoff approximation. In addition to traditional mass and wave-function renormalization, new types of counterterms are required. These are nonlocal and involve arbitrary functions of the longitudinal momenta. Their appearance is consistent with general power-counting arguments on the light front. We estimate the arbitrary function'' in two ways: (1) by using perturbation theory as a guide and (2) by considering the asymptotic large transverse momentum behavior of the kernel in the bound-state equations. The latter method, as it is currently implemented, is applicable only to the helicity-zero sector of the theory. Because of triviality, in the Yukawa model one must retain a finite cutoff [Lambda] in order to have a nonvanishing renormalized coupling. For the range of renormalized couplings (and cutoffs) allowed by triviality, one finds that the perturbative counterterm does a good job in eliminating cutoff dependence in the low-energy spectrum (masses [much lt][Lambda]).

Glazek, S.; Harindranath, A.; Pinsky, S.; Shigemitsu, J.; Wilson, K. (Physics Department, The Ohio State University, Columbus, Ohio 43210 (United States))

1993-02-15

352

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

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

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

2011-04-01

353

Properties of gravitationally equilibrated Yukawa systems—A molecular dynamics study

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, E-mail: ganesh@ipr.res.in; Joy, Ashwin [Institute for Plasma Research, Bhat-Village, Gujarat, Gandhinagar 382428 (India)] [Institute for Plasma Research, Bhat-Village, Gujarat, Gandhinagar 382428 (India)

2014-04-15

354

A study of Schwinger-Dyson equations for Yukawa and Wess-Zumino models

NASA Astrophysics Data System (ADS)

We study Schwinger-Dyson equations for fermions in Yukawa and Wess-Zumino models, in terms of dynamical mass generation and the wavefunction renormalization function. In the Yukawa model with icons/Journals/Common/gamma" ALT="gamma" ALIGN="TOP"/>5-type interaction between scalars and fermions, we find a critical coupling in the quenched approximation above which fermions acquire dynamical mass. This is shown to be true beyond the bare 3-point vertex approximation. In the Wess-Zumino model (Wess J and Zumino B 1974 Nucl. Phys. B 70 39; Wess J and Zumino B 1974 Phys. Lett. B 49 52), there is a neat cancellation of terms leading to no dynamical mass for fermions. We comment on the conditions under which these results are general beyond the rainbow approximation and also on the ones under which supersymmetry is preserved and the scalars do not also acquire mass. The results are in accordance with the non-renormalization theorem at least to order icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> in perturbation theory. In both the models, we also evaluate the wavefunction renormalization function, analytically in the neighbourhood of the critical coupling and numerically, away from it.

Bashir, A.; Diaz-Cruz, J. Lorenzo

1999-09-01

355

Threshold anomaly for the 7Be +58Ni system at near-Coulomb-barrier energies

NASA Astrophysics Data System (ADS)

By using recent fusion cross section measurements for the weakly bound system 7Be+58Ni around the Coulomb barrier, a simultaneous ?2 analysis of elastic scattering and fusion cross section data is performed. The analysis is carried out with optical polarization potentials for the fusion and direct reaction processes. That is, the nuclear polarization potential UN is split into a volume part UF which accounts for fusion reactions and a surface part UD R that is responsible for direct reactions. The parameters of fusion and direct reaction Woods-Saxon polarization potentials are determined by the analysis of the data. The presence of the threshold anomaly is investigated from the energy dependence of these polarization potentials. It is found that, contrary to other weakly bound systems, the 7Be+58Ni reaction presents the usual threshold anomaly.

Gómez Camacho, A.; Aguilera, E. F.

2014-12-01

356

Interplay of Coulomb interactions and rippling of monolayer graphene: RG approach

NASA Astrophysics Data System (ADS)

The effects of electron-electron Coulomb interactions and rippling disorder of a mono-layer graphene are studied at half-filling using renormalization group. It is found that the system flows to an infra-red stable line of fixed points which is accessible perturbatively and along which the zero temperature minimal metallic conductivity is non-universal and enhanced relative to the clean non-interacting fixed point. An estimate of the typical random vector potential representing ripples in graphene brings the theoretical value of the minimal conductivity into the vicinity of 4e^2/h.

Vafek, Oskar; Juricic, Vladimir; Herbut, Igor

2008-03-01

357

Effects of vacuum polarization on sub-coulomb 12C- 12C scattering (l)

NASA Astrophysics Data System (ADS)

In order to investigate the effect of vacuum polarization on the sub-Coulomb interaction between hadrons, the relative differential cross section for elastic 12C- 12C scattering at Elab = 4 MeV was measured with high precision at angles near 45°. Special care was taken to study various sources of systematic errors. The positions of the interference minima are determined to ±0.002°. The data are compared with theoretical calculations taking into account the contribution due to the Uehling potential and various other effects such as nuclear interaction, nuclear polarizability and electronic screening. The results of our experiment constitute a test of the vacuum polarization on the 7% level.

Vetterli, D.; Böglin, W.; Egelhof, P.; Henneck, R.; Jaskòla, M.; Klein, A.; Mühry, H.; Sick, I.; Trautmann, D.; Baur, G.

358

The ice-limit of Coulomb gauge Yang-Mills theory

In this paper we describe gauge invariant multi-quark states generalising 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 llustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark--antiquark potential.

Thomas Heinzl; Anton Ilderton; Kurt Langfeld; Martin Lavelle; David McMullan

2008-07-29

359

Permittivity and one-particle distribution functions in the thermodynamics of a coulomb system

NASA Astrophysics Data System (ADS)

Using the grand canonical distribution and the virial theorem, we show that the Gibbs thermodynamic potential of a nonrelativistic system of charged particles is uniquely determined by its permittivity and the distribution functions of electrons and nuclei without using perturbation theory. This means that consistent approximations for the permittivity and one-particle distribution functions of electrons and nuclei must be used to calculate thermodynamic functions of the Coulomb system. To construct such selfconsistent approximations, we propose using a decoupling procedure based on separating the "connected" and "regular" parts of the temperature Green's functions in the equations of motion. We consider the self-consistent Hartree-Fock approximation corresponding to this procedure.

Bobrov, V. B.

2014-05-01

360

Magneto-Coulomb effect in carbon nanotube quantum dots filled with magnetic nanoparticles.

Electrical transport measurements of carbon nanotubes filled with magnetic iron nanoparticles are reported. Low-temperature (40 mK) magnetoresistance measurements showed conductance hysteresis with sharp jumps at the switching fields of the nanoparticles. Depending on the gate voltage, positive or negative hysteresis was observed. The results are explained in terms of a magneto-Coulomb effect: The spin flip of the iron island at a nonzero magnetic field causes a shift of the chemical potential induced by the change of Zeeman energy; i.e., an effective charge variation is detected by the nanotube quantum dot. PMID:22107663

Datta, S; Marty, L; Cleuziou, J P; Tilmaciu, C; Soula, B; Flahaut, E; Wernsdorfer, W

2011-10-28

361

Modified Coulomb-Dipole Theory for 2e Photoionization

NASA Technical Reports Server (NTRS)

In the light of recent experiment on 2e photoionization of Li near threshold, we have considered a modification of the Coulomb-dipole theory, retaining the basic assumption that the threshold is dominated by asymmetric events in phase space [implies r(sub 1), k(sub 1)) greater than or equal to 2(r(sub 2), k(sub )]. In this region [in a collinear model, 2/r(sub 12) approached + 2/(r(sub 1)+r(sub 2)] the interaction reduces to V(rIsub 1) is greater than or equal to 2r(sub 2) is identically equal to [(-Z/r(sub 2)-(A-1)/r(sub 1)] + [(-2r(sub 2)/r(sub 1 exp 2)] is identically equal to V(sub c)+[V(sub d)]. For two electron emission Z = 2, thus both electrons see a Coulomb potential (V(sub c)) asymptotically, albeit each seeing a different charge. The residual potential (V(sub d)) is dipole in character. Writing the total psi = psi (sub c) + psi(sub d) = delta psi, and noting that. (T+V(sub c)-E)psy(sub c) = 0 and (T+V(sub c))psi(sub d) = 0 can be solved exactly, we find, substituting psi into the complete Schrod. Eq., that delta psi = -(H-E)(exp -1)(V(sub d) psi(sub 0)+V(sub c psi (sub 1). Using the fact that the absolute value of V(sub c) is much more than the absolute value of V(sub d) in almost all of configuration space, we can replace H by H(sub 0) in 9H-E)(exp -1) to obtain an improved approximation psi (improved) = psi(sub c) + psi(sub d) -(H(sub 0)-E)(exp -1) (V(sub c) psi (sub 0) + V(sub c) psi(sub 1). Here's the Green's function (H(sub 0)-E)(exp -1), can be exhibited explicitly, but the last term in psi (improved) is small, compared to the first two terms. Inserting them into the transition matrix element, which one handles in the usual way, we obtain in the limit E approaches 0, the threshold law: Q(E) alpha E + M(E)E(exp 5/4) + higher order (Eq. 1a). The modulation function, M(E), is a well-defined (but very non-trivial integral, but it is expected to be well approximated by a sinusoidal function containing a dipole phase term (M(E) = c sin[alpha log (E) + micron] (Eq. 1b). Experimental results show definite modulations, and are well fitted by Eqs (1).

2004-01-01

362

We study a chirally invariant Higgs-Yukawa model regulated on a space-time lattice. We calculate Higgs boson resonance parameters and mass bounds for various values of the mass of the degenerate fermion doublet. Also, first results on the phase transition temperature are presented. In general, this model may be relevant for BSM scenarios with a heavy fourth generation of quarks.

John Bulava; Philip Gerhold; Karl Jansen; Jim Kallarackal; Attila Nagy

2011-11-11

363

Coulomb branch Hilbert series and Hall-Littlewood polynomials

There has been a recent progress in understanding the chiral ring of 3d $\\mathcal{N}=4$ superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for $T_\\rho(G)$ theories in terms of Hall-Littlewood polynomials. Here $G$ is a classical group and $\\rho$ is a certain partition related to the dual group of $G$. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of $T_\\rho(G)$ theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

Stefano Cremonesi; Amihay Hanany; Noppadol Mekareeya; Alberto Zaffaroni

2014-09-23

364

Quasiparticle Gaps and Exciton Coulomb Energies in Si Nanoshells

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

365

Weak interaction rate Coulomb corrections in big bang nucleosynthesis

We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner big bang nucleosynthesis (BBN) code. We have also added the zero-temperature radiative correction. We find that using this higher accuracy Coulomb correction results in good agreement with previous work, giving only a modest {approx}0.04% increase in helium mass fraction over correction prescriptions applied previously in BBN calculations. We have calculated the effect of these corrections on other light element abundance yields in BBN, and we have studied these yields as functions of electron neutrino lepton number. This has allowed insights into the role of the weak neutron-proton interconversion processes in the setting of the neutron-to-proton ratio during the BBN epoch. We find that the lepton capture processes' contributions to this ratio are only second order in the Coulomb correction.

Smith, Christel J. [Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States); Physics Department, Arizona State University, Tempe, Arizona, 85287-1504 (United States); Fuller, George M. [Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States)

2010-03-15

366

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

NASA Astrophysics Data System (ADS)

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

Iorio, Lorenzo

2008-11-01

367

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

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

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

2010-02-10

368

Proton Decay, Yukawa Couplings and Underlying Gauge Symmetry in String Theory

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{\\bf 5}) in their origins. In this article, we consider a possibility that they come from different irreducible components in $\\mathfrak{g}/\\mathfrak{h}$. 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_7 and E_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.

Radu Tatar; Taizan Watari

2006-03-20

369

Putting Yukawa-like Modified Gravity (MOG) on the test in the Solar System

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

Lorenzo Iorio

2008-11-10

370

Coulomb excitation of 85Rb and 87Rb

Energy levels of 85Rb and 87Rb have been studied via de-excitation gamma-rays following Coulomb excitation with 35Cl ions. In addition to the known negative-parity states at 151.2 keV and 868.2 keV in 85Rb, two states at 281.0 keV and 731.8 keV have been found with fourgamma-ray transitions of 129.8, 281.0, 450.8 and 731.8 keV. Only one Coulomb excited state at

P. D. Bond; G. J. Kumbartzki

1973-01-01

371

Hydrodynamic Coulomb drag of strongly correlated electron liquids

NASA Astrophysics Data System (ADS)

We develop a theory of Coulomb drag in ultraclean double layers with strongly correlated carriers. In the regime where the equilibration length of the electron liquid is shorter than the interlayer spacing the main contribution to the Coulomb drag arises from hydrodynamic density fluctuations. The latter consist of plasmons driven by fluctuating longitudinal stresses, and diffusive modes caused by temperature fluctuations and thermal expansion of the electron liquid. We express the drag resistivity in terms of the kinetic coefficients of the electron fluid. Our results are nonperturbative in interaction strength and do not assume Fermi-liquid behavior of the electron liquid.

Apostolov, S. S.; Levchenko, A.; Andreev, A. V.

2014-03-01

372

Primary Thermometry in the Intermediate Coulomb Blockade Regime

NASA Astrophysics Data System (ADS)

We investigate Coulomb blockade thermometers (CBT) in an intermediate temperature regime, where measurements with enhanced accuracy are possible due to the increased magnitude of the differential conductance dip. Previous theoretical results show that corrections to the half width and to the depth of the measured conductance dip of a sensor are needed, when leaving the regime of weak Coulomb blockade towards lower temperatures. In the present work, we demonstrate experimentally that the temperature range of a CBT sensor can be extended by employing these corrections without compromising the primary nature or the accuracy of the thermometer.

Feshchenko, A. V.; Meschke, M.; Gunnarsson, D.; Prunnila, M.; Roschier, L.; Penttilä, J. S.; Pekola, J. P.

2013-10-01

373

Coulomb impurity effect on electrically induced Dirac bound states in graphene

NASA Astrophysics Data System (ADS)

Using the massless Dirac-Weyl model for monolayer graphene sheet, we study the low-lying spectra of a single Dirac electron system bound to an on-center positively charged Coulomb impurity, under both electrostatic potential and magnetic field. Numerical results obtained from diagonalization show that, the increase of the electrostatic potential causes the low-lying states to evolve from one Landau-type plateau to the higher ones, and the whole spectra exhibit similar features with slight shifts in eigenenergies when the on-center impurity is considered. Electrostatic-potential dependent optical spectra with their corresponding absorption coefficients as functions of incident photon energies for transitions between low-lying states are presented.

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

2015-12-01

374

Coulomb and dipole effects in tunneling ionization of molecules including nuclear motion

NASA Astrophysics Data System (ADS)

We study tunneling ionization in a one-dimensional three-body model of a molecule, treating both electronic and nuclear degrees of freedom exactly. In a recent paper [Phys. Rev. Lett. 111, 153003 (2013), 10.1103/PhysRevLett.111.153003] it was demonstrated using a finite-range potential that the Born-Oppenheimer approximation breaks down for fields weaker than a critical field FBO when describing tunneling ionization of molecules, but works for stronger fields. It was also demonstrated that the weak-field asymptotic theory allows for an accurate description in this weak-field limit. In the present paper, we consider a potential with a Coulomb tail and nonzero dipole moment, modeling polar molecules. Our study shows that the conclusions of the aforementioned paper also hold for this potential.

Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

2015-01-01

375

Towards Stronger Coulomb Coupling in an Ultracold Neutral Plasma

NASA Astrophysics Data System (ADS)

Ultracold neutral plasmas are created by photoionizing laser-cooled atoms in a magneto-optical trap (MOT). Due to their large electrical potential energies and comparatively small kinetic energies, ultracold plasmas fall into a regime of plasma systems which are called "strongly coupled." A priority in the field of ultracold plasmas is to generate plasmas with higher values of the strong coupling parameter Gamma, which is given as the ratio of the nearest-neighbor Coulomb potential energy to the average kinetic energy. The equilibrium strong coupling in ultracold plasmas is limited by the ultrafast relaxation of the ions due to spatial disorder in the initial system. This heating mechanism is called "disorder-induced heating" (DIH) and it limits the ion strong coupling in ultracold plasmas to order unity. This thesis describes experiments that explore ways to generate higher values of the strong coupling parameter in an ultracold neutral calcium plasma. One way to increase Gamma is to mitigate the effects of DIH using electron screening. This thesis describes an experiment in which the initial electron temperature was systematically changed to determine the effect that electron screening has on the ion thermalization. At lower initial electron temperatures, corresponding to a higher degree of electron shielding, it was found that the screening slows the ion thermalization and reduces the equilibrium ion temperature by as much as a factor of two. However, electron screening also reduces the ion interaction strength by the same amount, which has the net effect of leaving the effective Gamma unchanged. Another method for increasing the strong coupling of an ultracold plasma is to excite the plasma ions to a higher ionization state. Simulations predict that doubly ionizing the plasma ions can increase the strong coupling in an ultracold plasma by as much as a factor of 4, with the maximum value of Gamma depending on the timing of the second ionization relative to the DIH process. This thesis describes an experiment designed to test these predictions in a Ca2+ plasma. Measurements of the change in the Ca + ion temperature as a function of the timing of the second ionization pulses were made using laser-induced fluorescence. Results of these measurements show that the heating of the Ca+ ions due to the second ionization depends on the timing of the second ionization pulses, as predicted by MD simulations. Keywords: ultracold plasma, atomic physics, plasma physics, laser cooling, strong coupling.

Lyon, Mary E.

376

Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction

Weak formulations and solution multiplicity of equilibrium configurations with Coulomb friction configurations of elastic struc- tures in contact with Coulomb friction. We obtain a variational formulation configurations with arbitrary small friction coefficients. We illustrate the result in two space dimensions

Bostan, Mihai

377

Coulomb energy of uniformly charged spheroidal shell systems

NASA Astrophysics Data System (ADS)

We provide exact expressions for the electrostatic energy of uniformly charged prolate and oblate spheroidal shells. We find that uniformly charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the formation of spheroidal structures over a sphere of equal area for high values of shell volume fractions.

Jadhao, Vikram; Yao, Zhenwei; Thomas, Creighton K.; de la Cruz, Monica Olvera

2015-03-01

378

Analytic Coulomb matrix elements in a three-dimensional geometry

Using a complete basis set we have obtained an analytic expression for the matrix elements of the Coulomb interaction. These matrix elements are written in a closed form. We have used the basis set of the three-dimensional isotropic quantum armonic oscillator in order to develop our calculations, which can be useful when treating interactions in localized systems.

Jaime Zaratiegui

2005-11-04

379

Analytic Coulomb matrix elements in a three-dimensional geometry

Using a complete basis set we have obtained an analytic expression for the matrix elements of the Coulomb interaction. These matrix elements are written in a closed form. We have used the basis set of the three-dimensional isotropic quantum harmonic oscillator in order to develop our calculations, which can be useful when treating interactions in localized systems.

Garcia, Jaime Zaratiegui [Department of Physical Sciences, P.O. Box 3000, FIN-90014 University of Oulu (Finland)

2005-12-15

380

Coulomb blockade in vertical, bandgap engineered silicon nanopillars

NASA Astrophysics Data System (ADS)

Vertically oriented, bandgap engineered silicon double tunnel junction nanopillars were fabricated and electrically addressed. The devices were tested at liquid nitrogen and room temperatures. Distinctive staircase steps in current were observed at cryogenic temperatures indicative of the Coulomb blockade effect present in asymmetric double tunnel junction structures. These features disappeared when the device was measured at room temperature.

Walavalkar, Sameer; Latawiec, Pawel; Scherer, Axel

2013-05-01

381

Coulomb energy of uniformly-charged spheroidal shell systems

We provide exact expressions for the electrostatic energy of uniformly-charged prolate and oblate spheroidal shells. We find that uniformly-charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly-charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the forma...

Jadhao, Vikram; Thomas, Creighton K; de la Cruz, Monica Olvera

2015-01-01

382

Coulomb energy of uniformly-charged spheroidal shell systems

We provide exact expressions for the electrostatic energy of uniformly-charged prolate and oblate spheroidal shells. We find that uniformly-charged prolate spheroids of eccentricity greater than 0.9 have lower Coulomb energy than a sphere of the same area. For the volume-constrained case, we find that a sphere has the highest Coulomb energy among all spheroidal shells. Further, we derive the change in the Coulomb energy of a uniformly-charged shell due to small, area-conserving perturbations on the spherical shape. Our perturbation calculations show that buckling-type deformations on a sphere can lower the Coulomb energy. Finally, we consider the possibility of counterion condensation on the spheroidal shell surface. We employ a Manning-Oosawa two-state model approximation to evaluate the renormalized charge and analyze the behavior of the equilibrium free energy as a function of the shell's aspect ratio for both area-constrained and volume-constrained cases. Counterion condensation is seen to favor the formation of spheroidal structures over a sphere of equal area for high values of shell volume fractions.

Vikram Jadhao; Zhenwei Yao; Creighton K. Thomas; Monica Olvera de la Cruz

2015-01-15

383

Interpolating the Coulomb Phase of Little String Theory

We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. We also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.

Lin, Ying-Hsuan; Wang, Yifan; Yin, Xi

2015-01-01

384

Computer Simulation of Coulomb Explosion on (111) Silicon Surface

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

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

2002-01-01

385

Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons

ERIC Educational Resources Information Center

This dissertation examines the effect of Coulomb interactions in Hanbury Brown-Twiss (HBT) type experiments with electrons. HBT experiments deal with intensity interference, which is related to the second-order correlation function of the particle field. This is an extension of the usual amplitude interference experiment, such as Young's…

Shen, Kan

2009-01-01

386

For conjugated polymers, the extended Peierls-Hubbard model has been widely accepted as correctly incorporating the effects of both e-p and e-e interactions. In the absence of e-e interactions, the ground state of (CH)/sub x/ is the 2k/sub F/ bond-order wave (BOW) -- dimerization/bond alternation -- predicted by Peierls theorem. It is now well established that for the weak e-p coupling appropriate to (CH)/sub x/, the on-site Coulomb repulsion actually enhances dimerization up to fairly large values (U > 6t/sub 0/). These results are still widely regarded as counter to the conventional wisdom that Coulomb interactions should suppress the build-up of charge anywhere, on the sites or on the bonds. Since the extended Peierls-Hubbard model incorporates only (lattice) site-diagonal parts of the electron-electron interactions (U, V), and omits the off-diagonal bond-charge repulsions (W,X), it is natural to ask whether this model adequately describes the full consequences of e-e interactions. In the specific context of (CH)/sub x/, the potential importance of this omission is readily recognized. Intuitively, the bond-charge repulsion should suppress dimerization, since it opposes the build-up of charge on the bonds. Thus, the absence of W and X terms in the standard extended Peierls-Hubbard models suggests a priori that these models may artificially favor the continuation of dimerization in the half-filled band into the region of intermediate to strong Coulomb interaction. More generally, the omission of terms such as W and X raises significant questions about the appropriateness of Hubbard models for describing e-e interactions in the whole class of novel solid state materials. Thus this issue is extremely important and is, discussed further in this paper. 14 refs., 6 figs.

Campbell, D.K.; Gammel, J.T.; Loh, E.Y. Jr.

1989-01-01

387

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

388

Steady state erosion of critical Coulomb wedges with applications to Taiwan and the Himalaya

Steady state erosion of critical Coulomb wedges with applications to Taiwan and the Himalaya G. E-deformation model for orogenic wedges that are in erosional steady state and deform at their Coulomb failure limit, Taiwan Citation: Hilley, G. E., and M. R. Strecker (2004), Steady state erosion of critical Coulomb

Hilley, George

389

Accretionary prisms in subduction earthquake cycles: The theory of dynamic Coulomb wedge

We expand the theory of critically tapered Coulomb wedge for accretionary prisms by considering stress changes in subduction earthquake cycles. Building on the Coulomb plasticity of the classical theory, we assume an elastic-perfectly Coulomb plastic rheology and derive exact stress solutions for stable and critical wedges. The new theory postulates that the actively deforming, most seaward part of an accretionary

Kelin Wang; Yan Hu

2006-01-01

390

Scattering of electrons by a Coulomb center

NASA Astrophysics Data System (ADS)

New results are obtained from which it follows that systematic use of the one-to-one correspondence between a physical quantity and an operator, which permits the existence of a non-negative quantum distribution function, leads to an “effective” smearing of the potential and to the appearance of a form factor, i.e., to the existence of structure in the scattering center.

Samsonenko, N. V.; Dubkov, S. L.

1980-04-01

391

The driving terms in three-body theories of elastic and inelastic scattering of a charged particle off a bound state of two other charged particles contain the fully off-shell two-body Coulomb T-matrix describing the intermediate-state Coulomb scattering of the projectile with each of the charged target particles. Up to now the latter is usually replaced by the Coulomb potential, either when using the multiple-scattering approach or when solving three-body integral equations. General properties of the exact and the approximate on-shell driving terms are discussed, and the accuracy of this approximation is investigated numerically, both for atomic and nuclear processes including bound-state excitation, for energies below and above the corresponding three-body dissociation threshold, over the whole range of scattering angles.

E. O. Alt; A. S. Kadyrov; A. M. Mukhamedzhanov; M. Rauh

1995-03-16

392

NASA Astrophysics Data System (ADS)

We study flavor-violating processes in the production or decay of a neutral pseudoscalar meson P0 in the framework of a type-III two Higgs doublet model with four-texture Yukawa couplings. We use a version of the model where Yukawa interactions of neutral Higgs bosons allow for flavor change at the tree-level, but conserve CP symmetry. The physical Yukawa couplings respect CP-invariance due to the Hermiticity conditions that we impose on the fermion mass matrices. We focus on all possible ?±?l±P0 and P0?l+l'- decay channels, where l, l' are charged leptons. We find that these processes provide complementary information on quark and lepton flavor-changing neutral current Yukawa couplings. In particular flavor-violating parameters in the quark sector, ?sb and ?db, are significantly constrained by present experimental data, whereas the corresponding parameters in the leptonic sector are less constrained.

Gómez-Bock, M.; López-Castro, G.; López-Lozano, L.; Rosado, A.

2009-09-01

393

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

394

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

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

395

Confluent Heun equations: convergence of solutions in series of coulomb wavefunctions

NASA Astrophysics Data System (ADS)

The Leaver solutions in series of Coulomb wavefunctions for the confluent Heun equation are given by two-sided infinite series, that is, by series where the summation index n runs from minus to plus infinity (Leaver 1986 J. Math. Phys.27 1238). First we show that, in contrast to the D’Alembert test, under certain conditions the Raabe test ensures that the domains of convergence of these solutions include an additional singular point. We also consider solutions for a limit of the confluent Heun equation. For both equations, new solutions are generated by transformations of variables. Finally, we discuss the time dependence of the Klein-Gordon equation in two cosmological models and the spatial dependence of the Schrödinger equation to a family of quasi-exactly solvable potentials. For a subfamily of these potentials, we obtain infinite-series solutions which converge and are bounded for all values of the independent variable, in opposition to a common belief.

Jaccoud El-Jaick, Léa; Figueiredo, Bartolomeu D. B.

2013-03-01

396

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

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

397

Top Yukawa coupling measurement with indefinite CP Higgs in $e^+e^-\\to t\\bar{t}?$

We consider the issue of the top quark Yukawa coupling measurement in a model in dependent and general case with the inclusion of CP-violation in the coupling. Arguably the best process to study this coupling is the associa ted production of Higgs boson along with a $t\\bar t$ pair in a machine like the International Linear Collider (ILC). While detailed analyses of the sensitivity of the measurement assuming a Standard Model (SM) - like coupling are available in the context of ILC, conclude that th e coupling could be pinned down at about 10\\% level with modest luminosity, our investigations show that the scenario could be different in case of a more general coupling. The modified Lorentz structure resulting in a changed functional dependence of the cross section on the couplin g, along with the difference in the cross section itself leads to considerable deviation in the sensitivity. Our studies with an ILC of center of mass energies of 500 GeV, 800 GeV and 1000 GeV show that moderate CP-mixing in the Higgs sector could change the sensitivity to about 20\\ %, while it could be worsened to 75\\% in cases which could accommodate more dramatic changes in the coupling. While detailed considerations of the decay distributions point to a need for a relook at the analysis strategy followed for the case of SM such as for a model independent analysis of the top quark Yukawa coupling measurement. This study strongly suggests that, a joint analysis of the CP properties and the Yukawa coupling measurement would be the way forward at the ILC and that caution must be excercised in the measurem ent of the Yukawa couplings and the conclusions drawn from it.

B. Ananthanarayan; Sumit K. Garg; C. S. Kim; Jayita Lahiri; P. Poulose

2014-05-26

398

We study a lattice Higgs-Yukawa model emulating the same Higgs-fermion coupling structure as in the Higgs sector of the electroweak Standard Model, in particular, obeying a Ginsparg-Wilson version of the underlying SU(2) x U(1) symmetry, being a global symmetry here due to the neglection of gauge fields in this model. In this paper we present our results on the cutoff-dependent upper Higgs boson mass bound at several selected values of the cutoff parameter.

P. Gerhold; K. Jansen

2009-12-02

399

Ion wake effects on the Coulomb ion drag in complex dusty plasmas

The ion wake effects on the Coulomb drag force are investigated in complex dusty plasmas. It is shown that the ion wake effects significantly enhance the Coulomb ion drag force. It is also found that the ion wake effects on the Coulomb drag force increase with an increase in the Debye length. In addition, the ion wake effects on the momentum transfer cross section and Coulomb drag force are found to be increased with increasing thermal Mach number, i.e., decreasing plasma temperature. It is also found that the Coulomb ion drag force would be stronger for smaller dust grains.

Ki, Dae-Han; Jung, Young-Dae [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)

2010-09-06

400

Single-hole tunneling and Coulomb blockade in the strain-relaxation-induced quantum ring

NASA Astrophysics Data System (ADS)

We fabricated an ultrasmall Si/SiGe strained vertical quantum dot in the Coulomb blockade regime, where strain relaxation in the SiGe quantum well creates a ring-like confinement potential.[1] The resonant tunneling characteristics contains features near the threshold due to single-hole tunneling and Coulomb blockade. The features are steps in one bias polarity and peaks in the other, which we attribute to the differences in the dynamic occupation of the dot due to double Si barrier asymmetry. The spacing of the features gives the charging energy of the quantum ring. When magnetic fields are applied parallel to the tunneling direction, the evolution of the single-hole tunneling features with magnetic fields reveals cusps arising from the angular-momentum transition of the single-particle ground state of the quantum ring in the magnetic field, and the periodicity of the cusps in magnetic field is consistent with the calculated one from h/e, the magnetic flux quantum. Unlike single-carrier tunneling into quantum dots, our data on the tunneling into a quantum ring show no evidence of a singlet-triplet transition. [1] J. Liu et al, Phys. Rev. Lett. 89, 096804 (2002).

Wang, Guohua; Tambe, D.; Zaslavsky, A.; Shenoy, V.; Syphers, D.

2006-03-01

401

Two-boson truncation of Pauli-Villars-regulated Yukawa theory

We apply light-front quantization, Pauli-Villars regularization, and numerical techniques to the nonperturbative solution of the dressed-fermion problem in Yukawa theory in 3 + 1 dimensions. The solution is developed as a Fock-state expansion truncated to include at most one fermion and two bosons. The basis includes a negative-metric heavy boson and a negative-metric heavy fermion to provide the necessary cancellations of ultraviolet divergences. The integral equations for the Fock-state wave functions are solved by reducing them to effective one-boson-one-fermion equations for eigenstates with J {sub z} = 1/2. The equations are converted to a matrix equation with a specially tuned quadrature scheme, and the lowest mass state is obtained by diagonalization. Various properties of the dressed-fermion state are then computed from the nonperturbative light-front wave functions. This work is a major step in our development of Pauli-Villars regularization for the nonperturbative solution of four-dimensional field theories and represents a significant advance in the numerical accuracy of such solutions.

Brodsky, Stanley J. [Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 (United States); Hiller, John R. [Department of Physics, University of Minnesota-Duluth, Duluth, MN 55812 (United States)]. E-mail: jhiller@d.umn.edu; McCartor, Gary [Department of Physics, Southern Methodist University, Dallas, TX 75275 (United States)

2006-05-15

402

Two-boson truncation of Pauli-Villars-regulated Yukawa theory

We apply light-front quantization, Pauli-Villars regularization, and numerical techniques to the nonperturbative solution of the dressed-fermion problem in Yukawa theory in 3+1 dimensions. The solution is developed as a Fock-state expansion truncated to include at most one fermion and two bosons. The basis includes a negative-metric heavy boson and a negative-metric heavy fermion in order to provide the necessary cancellations of ultraviolet divergences. The integral equations for the Fock-state wave functions are solved by reducing them to effective one-boson--one-fermion equations for eigenstates with J_z=1/2. The equations are converted to a matrix equation with a specially tuned quadrature scheme, and the lowest mass state is obtained by diagonalization. Various properties of the dressed-fermion state are then computed from the nonperturbative light-front wave functions. This work is a major step in our development of Pauli-Villars regularization for the nonperturbative solution of four-dimensional field theories and represents a significant advance in the numerical accuracy of such solutions.

S. J. Brodsky; J. R. Hiller; G. McCartor

2005-08-29

403

Two-boson truncation of Pauli-Villars-regulated Yukawa theory

We apply light-front quantization, Pauli-Villars regularization, and numerical techniques to the nonperturbative solution of the dressed-fermion problem in Yukawa theory in 3+1 dimensions. The solution is developed as a Fock-state expansion truncated to include at most one fermion and two bosons. The basis includes a negative-metric heavy boson and a negative-metric heavy fermion in order to provide the necessary cancellations of ultraviolet divergences. The integral equations for the Fock-state wave functions are solved by reducing them to effective one-boson--one-fermion equations for eigenstates with J_z=1/2. The equations are converted to a matrix equation with a specially tuned quadrature scheme, and the lowest mass state is obtained by diagonalization. Various properties of the dressed-fermion state are then computed from the nonperturbative light-front wave functions. This work is a major step in our development of Pauli-Villars regularization for the nonperturbative solution of four-dimensional field ...

Brodsky, S J; McCartor, G

2006-01-01

404

Off-diagonal Yukawa Couplings in the s-channel Charged Higgs Production at LHC

The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on the o?ff-shell top pair production process. However, resonance production in s-channel single top events is an important channel to search for this particle. In a previous work, it was shown that this process, i.e., qq' -> H+ -> tb + h.c., can lead to comparable results to what is already obtained from LHC searches through gb -> tH- process. What was obtained was, however, based on diagonal Yukawa couplings between incoming quarks assuming cs as the main incoming pair due to the CKM matrix element being close to unity. The aim of this paper is to show that off-diagonal couplings, like cb, may lead to substantial contributions to the cross section, even if the corresponding CKM matrix element is two orders of magnitude smaller. For this reason, the cross section is calculated for each initial state including all diagonal and off-diagonal terms, and all is finally added together to get the total cross section which is observed to be ~ ...

Hashemi, Majid

2015-01-01

405

Off-diagonal Yukawa Couplings in the s-channel Charged Higgs Production at LHC

The search for the heavy charged Higgs (mH+ > mtop) has been mainly based on the o?ff-shell top pair production process. However, resonance production in s-channel single top events is an important channel to search for this particle. In a previous work, it was shown that this process, i.e., qq' -> H+ -> tb + h.c., can lead to comparable results to what is already obtained from LHC searches through gb -> tH- process. What was obtained was, however, based on diagonal Yukawa couplings between incoming quarks assuming cs as the main incoming pair due to the CKM matrix element being close to unity. The aim of this paper is to show that off-diagonal couplings, like cb, may lead to substantial contributions to the cross section, even if the corresponding CKM matrix element is two orders of magnitude smaller. For this reason, the cross section is calculated for each initial state including all diagonal and off-diagonal terms, and all is finally added together to get the total cross section which is observed to be ~ 2.7 times larger than what is obtained from cs initial state. Results are eventually re?flected into 95% C.L. exclusion and 5?sigma discovery contours at di?fferent integrated luminosities of LHC. A reasonable coverage of the parameter space is obtained by the 95% C.L. exclusion contour.

Majid Hashemi; Seyyed Mohammad Zebarjad; Hossein Bakhshalizadeh

2014-12-24

406

Freezing lines of colloidal Yukawa spheres. II. Local structure and characteristic lengths

Using the Rogers-Young (RY) integral equation scheme for the static pair correlation functions combined with the liquid-phase Hansen-Verlet freezing rule, we study the generic behavior of the radial distribution function and static structure factor of monodisperse charge-stabilized suspensions with Yukawa-type repulsive particle interactions at freezing. In a related article, labeled Paper I [J. Gapinski, G. Nägele, and A. Patkowski, J. Chem. Phys. 136, 024507 (2012)], this hybrid method was used to determine two-parameter freezing lines for experimentally controllable parameters, characteristic of suspensions of charged silica spheres in dimethylformamide. A universal scaling of the RY radial distribution function maximum is shown to apply to the liquid-bcc and liquid-fcc segments of the universal freezing line. A thorough analysis is made of the behavior of characteristic distances and wavenumbers, next-neighbor particle coordination numbers, osmotic compressibility factor, and the Ravaché-Mountain-Streett minimum-maximum radial distribution function ratio.

Gapinski, Jacek, E-mail: gapinski@amu.edu.pl; Patkowski, Adam [Molecular Biophysics Division, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Pozna? (Poland); NanoBioMedical Center, A. Mickiewicz University, Umultowska 85, 61-614 Pozna? (Poland); Nägele, Gerhard [Institute of Complex Systems (ICS-3), Forschungszentrum Jülich, D-52425 Jülich (Germany)

2014-09-28

407

Yukawas, G-flux, and Spectral Covers from Resolved Calabi-Yau's

We use the resolution procedure of Esole and Yau arXiv:1107.0733 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 arXiv:0908.1784 for the Euler character in the process. We comment on the physical implications of the surprising singular fibers in codimension 2 and 3 in arXiv:1107.0733 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 arXiv:1107.1718 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.

Joseph Marsano; Sakura Schafer-Nameki

2011-08-08

408

Dislocation nucleation and motion observed in a 2D Yukawa triangular lattice

NASA Astrophysics Data System (ADS)

Dislocation nucleation and motion were studied experimentally in a 2D Yukawa triangular lattice. Edge dislocations were created in pairs in lattice locations where the internal shear stress exceeded a threshold and then moved apart in the glide plane at a speed higher than the sound speed of shear waves. The early stage of this process is identified as a stacking fault. At a later stage, supersonically moving dislocations generated shear-wave Mach cones. The experimental system, a plasma crystal, allowed observation of this process at an atomistic (kinetic) level. We used a monolayer suspension of microspheres in a plasma, i.e., a complex plasma, which is like a colloidal suspension, but with an extremely low volume fraction and a partially-ionized rarefied gas instead of solvent. At our experimental conditions, the suspension forms a highly ordered 2D triangular lattice. Dislocations were generated in this lattice due to the shear introduced by its differential rotation, with two ``rigid'' domain walls imbedded in it. We used digital video microscopy for direct imaging and particle tracking.

Nosenko, V.; Zhdanov, S.; Morfill, G.

2008-03-01

409

Modelling Coulombic Failure of Sea ice with Leads

NASA Astrophysics Data System (ADS)

Sea ice failure under low confinement compression is modelled with a linear Coulombic criterion that can describe either fracture failure or frictional granular yield along slip lines. To study the effect of anisotropy we consider a simplified anisotropic sea ice model where the sea ice thickness depends on orientation. Accommodation of arbitrary deformation requires failure along at least two intersecting slip lines, which are determined by finding two maxima of the yield criterion. Due to the anisotropy these slip lines generally differ from the standard, Coulombic slip lines that are symmetrically positioned around the compression direction, and therefore different tractions along these slip lines give rise to a non-symmetric stress tensor. We consider the case of two leads initially formed in an isotropic ice cover under compression, and address the question of whether these leads will remain active or new slip lines will form under a rotation of the principal compression direction.

Wilchinsky, A. V.; Feltham, D. L.

2011-12-01

410

Is the ground state of Yang-Mills theory Coulombic?

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

411

A Coulomb collision algorithm for weighted particle simulations

NASA Technical Reports Server (NTRS)

A binary Coulomb collision algorithm is developed for weighted particle simulations employing Monte Carlo techniques. Charged particles within a given spatial grid cell are pair-wise scattered, explicitly conserving momentum and implicitly conserving energy. A similar algorithm developed by Takizuka and Abe (1977) conserves momentum and energy provided the particles are unweighted (each particle representing equal fractions of the total particle density). If applied as is to simulations incorporating weighted particles, the plasma temperatures equilibrate to an incorrect temperature, as compared to theory. Using the appropriate pairing statistics, a Coulomb collision algorithm is developed for weighted particles. The algorithm conserves energy and momentum and produces the appropriate relaxation time scales as compared to theoretical predictions. Such an algorithm is necessary for future work studying self-consistent multi-species kinetic transport.

Miller, Ronald H.; Combi, Michael R.

1994-01-01

412

Light ion induced nuclear reactions close to the Coulomb barrier

NASA Astrophysics Data System (ADS)

The aim of our study is to determine excitation functions for the formation of different reaction products with light ions near the Coulomb barrier and to compare the results with computations according to different reaction mechanisms (compound reactions, direct reactions). In the present study results from experiments with a beam of 9Be on a thin Aluminum target below and around the Coulomb barrier are presented. The formation of several reaction products was determined by the characteristic gamma emissions from these nuclei. Excitation functions of the reactions 27Al(9Be,8Be?2a)28Al, 27Al(9Be,2n)34Cl, 27Al(9Be,pn)34S and 27Al(9Be,a2n)30P with lab energies between 5 and 14 MeV have been determined.

Forstner, O.; Törnström, P.; Friedmann, H.; Hille, P.; Kühtreiber, J.; Pavlik, A.; Priller, A.

2011-09-01

413

Orbital ice: An exact Coulomb phase on the diamond lattice

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.

Chern Giawei [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States); Wu Congjun [Department of Physics, University of California, San Diego, California 92093 (United States)

2011-12-15

414

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

415

Structural phase transitions and topological defects in ion Coulomb crystals

NASA Astrophysics Data System (ADS)

We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed nonadiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.

Partner, Heather L.; Nigmatullin, Ramil; Burgermeister, Tobias; Keller, Jonas; Pyka, Karsten; Plenio, Martin B.; Retzker, Alex; Zurek, Wojciech H.; del Campo, Adolfo; Mehlstäubler, Tanja E.

2015-03-01

416

Regular multicharged transient soft matter in Coulomb explosion of heteroclusters

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. PMID:15665087

Last, Isidore; Jortner, Joshua

2005-01-01

417

Equation of state of classical Coulomb plasma mixtures.

We develop analytic approximations of thermodynamic functions of fully ionized nonideal electron-ion plasma mixtures. In the regime of strong Coulomb coupling, we use our previously developed analytic approximations for the free energy of one-component plasmas with rigid and polarizable electron background and apply the linear mixing rule (LMR). Other thermodynamic functions are obtained through analytic derivation of this free energy. In order to obtain an analytic approximation for the intermediate coupling and transition to the Debye-Hückel limit, we perform hypernetted-chain calculations of the free energy, internal energy, and pressure for mixtures of different ion species and introduce a correction to the LMR, which allows a smooth transition from strong to weak Coulomb coupling, in agreement with the numerical results. PMID:19257152

Potekhin, Alexander Y; Chabrier, Gilles; Rogers, Forrest J

2009-01-01

418

Coulomb excitation of $^{68}$Ni at safe energies

The $B(E2;0^+\\to2^+)$ value in $^{68}$Ni has been measured using Coulomb excitation at safe energies. The $^{68}$Ni radioactive beam was post-accelerated at the ISOLDE facility (CERN) to 2.9 MeV/u. The emitted $\\gamma$ rays were detected by the MINIBALL detector array. A kinematic particle reconstruction was performed in order to increase the measured c.m. angular range of the excitation cross section. The obtained value of 2.8$^{+1.2}_{-1.0}$ 10$^2$ e$^2$fm$^4$ is in good agreement with the value measured at intermediate energy Coulomb excitation, confirming the low $0^+\\to2^+$ transition probability.

N. Bree; I. Stefanescu; P. A. Butler; J. Cederkäll; T. Davinson; P. Delahaye; J. Eberth; D. Fedorov; V. N. Fedosseev; L. M. Fraile; S. Franchoo; G. Georgiev; K. Gladnishki; M. Huyse; O. Ivanov; J. Iwanicki; J. Jolie; U. Köster; Th. Kröll; R. Krücken; B. A. Marsh; O. Niedermaier; P. Reiter; H. Scheit; D. Schwalm; T. Sieber; J. Van de Walle; P. Van Duppen; N. Warr; D. Weisshaar; F. Wenander; S. Zemlyanoy

2008-11-19

419

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

420

Coulomb branch Hilbert series and Three Dimensional Sicilian Theories

We evaluate the Coulomb branch Hilbert series of mirrors of three dimensional Sicilian theories, which arise from compactifying the $6d$ $(2,0)$ theory with symmetry $G$ on a circle times a Riemann surface with punctures. We obtain our result by gluing together the Hilbert series for building blocks $T_{\\mathbf{\\rho}}(G)$, where $\\mathbf{\\rho}$ is a certain partition related to the dual group of $G$, which we evaluated in a previous paper. The result is expressed in terms of a class of symmetric functions, the Hall-Littlewood polynomials. As expected from mirror symmetry, our results agree at genus zero with the superconformal index prediction for the Higgs branch Hilbert series of the Sicilian theories and extend it to higher genus. In the $A_1$ case at genus zero, we also evaluate the Coulomb branch Hilbert series of the Sicilian theory itself, showing that it only depends on the number of external legs.

Stefano Cremonesi; Amihay Hanany; Noppadol Mekareeya; Alberto Zaffaroni

2014-09-23

421

Tryptic y ++ Fragment Ion Distributions Are Guided by Coulombic Repulsion

NASA Astrophysics Data System (ADS)

Ideal tryptic peptides contain only a single basic residue, located at the C-terminus. Collisional fragmentation of their doubly- or triply-protonated ions generates doubly-charged y ++ fragment ions with modest intensities. The size distribution of the y ++ fragments, when averaged over many spectra, corresponds closely to the expectations from charge-directed backbone cleavage and a Coulomb-Boltzmann distribution of mobile protons. This observation should be helpful in developing mechanistic models for y ++ formation.

Irikura, Karl K.; Merle, John K.; Simón-Manso, Yamil

2012-03-01

422

A Maxwell's equations, Coulomb gauge analysis of two scatterers

May 1990 Major Subject: Electrical Engineering A MAXWELL'S EQUATIONS, COULOMB GAUGE ANALYSIS OF TWO SCATTERERS A Thesis by KELLY JEAN CROWELL Approved as to style and content by: Robert D. Nevels (Chairman of Committee) D. R. Halverson.... The gamma function is expressed as a. series as is given in Abramowitz and Stegun[23] by using the first several terms of Stirling's formula. Series with terms converging more slowly than 0( i, ) are obtained for each Bessel function product appearing...

Crowell, Kelly Jean

1990-01-01

423

Classical coulomb systems near a plane wall. I

The equilibrium structure of classical Coulomb systems bounded by a plane wall is studied near that wall. Several models are considered: the two-dimensional one-component plasma at a special value of the coupling constant (which makes the model exactly soluble), the two-dimensional and three-dimensional one-component and two-component plasmas in the weak-coupling limit (a Debye-Hückel type of approach is then used). Along

B. Jancovici

1982-01-01

424

Classical Coulomb systems near a plane wall. II

The equilibrium structure of classical Coulomb systems bounded by a plane hard wall is studied near that wall. A general sum rule is derived for the asymptotic form of the charge-charge correlation function along the wall. The exact results which can be obtained for the two-dimensional one-component plasma provide a test for this new sum rule, as well as for

B. Jancovici

1982-01-01

425

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

426

Reaction rates from Coulomb dissociation: Core excitation effects

A process, involving the 7Be core excitation in the Coulomb breakup of 8B into p + 7Be has been investigated. From the experimental results recently obtained in RIKEN we have derived the mixing amplitude of the | 7Be(1/2-) X (1p_{3/2}); 2+> configuration in the ground state of 8B. Implications on the evaluation of the S17 at stellar energies are discussed.

A. Mengoni; T. Motobayashi; T. Otsuka

1998-09-16

427

Coulomb excitations for a short linear chain of metallic shells

NASA Astrophysics Data System (ADS)

A self-consistent-field theory is given for the electronic collective modes of a chain containing a finite number, N, of Coulomb-coupled spherical two-dimensional electron gases arranged with their centers along a straight line, for simulating electromagnetic response of a narrow-ribbon of metallic shells. The separation between nearest-neighbor shells is arbitrary and because of the quantization of the electron energy levels due to their confinement to the spherical surface, all angular momenta L of the Coulomb excitations, as well as their projections M on the quantization axis, are coupled. However, for incoming light with a given polarization, only one angular momentum quantum number is usually required. Therefore, the electromagnetic response of the narrow-ribbon of metallic shells is expected to be controlled externally by selecting different polarizations for incident light. We show that, when N = 3, the next-nearest-neighbor Coulomb coupling is larger than its value if they are located at opposite ends of a right-angle triangle forming the triad. Additionally, the frequencies of the plasma excitations are found to depend on the orientation of the line joining them with respect to the axis of quantization since the magnetic field generated from the induced oscillating electric dipole moment on one sphere can couple to the induced magnetic dipole moment on another. Although the transverse inter-shell electromagnetic coupling can be modeled by an effective dynamic medium, the longitudinal inter-shell Coulomb coupling, on the other hand, can still significantly modify the electromagnetic property of this effective medium between shells.

Zhemchuzhna, Liubov; Gumbs, Godfrey; Iurov, Andrii; Huang, Danhong; Gao, Bo

2015-03-01

428

``Coulomb logarithm'' for inverse-bremsstrahlung laser absorption

The ``Coulomb logarithm'' for inverse-bremsstrahlung laser absorption is examined for plasmas of different ionic charge, spanning the classical and quantum-mechanical limits. Previously, this term has not been calculated exactly for the conditions of interest in laser fusion experiments; it has only been estimated from physical considerations. For short-wavelength irradiation (e.g., 0.35 mum), uncertainties in the ``logarithmic'' factor can produce variations

1987-01-01

429

Stability characterizations of fixtured rigid bodies with Coulomb friction

This paper formally introduces several stability characterizations of fixtured three-dimensional rigid bodies initially at rest and in unilateral contact with Coulomb friction. These characterizations, weak stability and strong stability, arise naturally from the dynamic model of the system, formulated as a complementarity problem. Using the tools of complementarity theory, these characterizations are studied in detail to understand their properties and to develop techniques to identify the stability classifications of general systems subjected to known external loads.

PANG,J.S.; TRINKLE,JEFFREY C.

2000-02-15

430

Full Coulomb collision operator in the moment expansion

The full Coulomb collision operator and its moments including nonlinear terms are analytically calculated in the moment expansion. In coupling nonlinear terms, the product formula which expresses a product of two harmonic tensors as a series of single harmonic tensors is derived. The collision operators and moments are written in explicit formulas for arbitrary moments and for arbitrary temperature and mass ratios. These expressions easily reduce to formulas for the small mass-ratio approximation or for like species.

Ji, Jeong-Young; Held, Eric D. [Department of Physics, Utah State University, Logan, Utah 84322 (United States)

2009-10-15

431

Coulomb Force in Mirror Nuclei in a Lattice Model

NASA Astrophysics Data System (ADS)

The Coulomb contribution to nuclear binding energies was calculated for 37 pairs of "mirror nuclei" in the fcc nuclear model. For each nucleus, a Monte Carlo technique was used to find the most-densely packed structure with the least electrostatic repulsion consistent with the fcc lattice and giving the known total angular momentum for the nucleus. The lattice dimensions in the fcc model are fixed (a nearest neighbor distance of 2.0262 fm) to give a central nuclear density of 0.17 nucleons/fm^3. This value has previously been shown to reproduce experimental radial values to within 2%. Using no adjustable parameters, the Coulomb force in mirror nuclei can then be calculated exactly in the fcc model and compared with experimental values. The results indicate that the same nucleon build-up procedure and lattice dimensions that reproduce RMS radial values also reproduce the known Coulomb effects. (1) N.D. Cook & V. Dallacasa, J. Phys. G 13, L101, 1987.

Cook, Norman D.

1996-10-01

432

Effects of full Coulomb interactions on electronic structure of ?-Pu

NASA Astrophysics Data System (ADS)

We used the CTQMC method for the realistic simulation of electronic properties of correlated actinides. In particular, we focus on the spectral function of ?-Pu, which is described in terms of a 7-orbital f-impurity model interacting with a metallic bath. Our CTQMC implementation solves this model by calculating a weak coupling expansion of the partition function in the fermionic multiorbital path-integral representation and provides numerically exact results for relatively high temperature. We discussed how different terms in the full on-site Coulomb vertex affect the local density of states. The comparison of CTQMC results with only diagonal density-density like Coulomb interactions and with additional non-diagonal terms in the interaction part of the Hamiltonian related with so-called spin flips terms shows the importance of the full rotationally invariant Coulomb vertex on the electronic structure of ?-Pu. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Gorelov, Eugeny; Wehling, Tim; Hafferman, Hartmut; Lichtenstein, Alexander; Rubtsov, Alexey; Landa, Alexander; Marianetti, Chris; Fluss, Michael; Shorikov, Alexey; Lukoyanov, Alexey; Korotin, Michael; Anisimov, Vladimir

2008-03-01

433

Coulomb excitation of the proton-dripline nucleus Na20

NASA Astrophysics Data System (ADS)

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 ? rays were detected by two TIGRESS HPGe clover detectors set perpendicular to the beam axis. Coulomb excitation from the 2+ ground state to the first excited 3+ and 4+ states was observed, and B(?L) values were determined using the 2+?0+ de-excitation in Ti48 as a reference. The resulting B(?L)? values are B(E2;3+?2+)=55±6e2fm4 (17.0±1.9 W.u.), B(E2;4+?2+)=35.7±5.7e2fm4 (11.1±1.8 W.u.), and B(M1;4+?3+)=0.154±0.030?N2 (0.086±0.017 W.u.). These measurements provide the first experimental determination of B(?L) values for this proton dripline nucleus of astrophysical interest.

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

2009-10-01

434

Energetics at extremes in Coulomb explosion of large finite systems

NASA Astrophysics Data System (ADS)

Novel features of the dynamics and energetics of clusters and nanodroplets driven by ultraintense, femtosecond, near-infrared laser pulses pertain to the establishment of energetic records for Coulomb explosion. Theoretical-computational studies demonstrated the attainment of table-top production of deuterons in the energy range of 1-10 MeV by extreme Coulomb explosion of deuterium nanodroplets/microdroplets with the initial size domain 100-1000 nm (number of constituents 5 × 108-1011), which were driven by superintense lasers with peak intensities of 1017-1020 W cm-2. This ultrahigh energy range establishes an energetic record for chemical dynamics. New aspects of ultraintense laser-nanostructure interactions involve laser intensity attenuation within the nanodroplet/microdroplet, and a proper treatment of the coupled system with the nanostructure size being comparable to the laser wavelength. Attenuation effects determine an upper size limit of 1 ?m of the nanodroplet/microdroplet for useful extreme Coulomb explosion with an energetic upper limit of 10 MeV for deuterons produced by this table-top process.

Last, Isidore; Jortner, Joshua

2012-05-01

435

Coulomb Blockade Oscillations in Coupled Single-Electron Transistors

NASA Astrophysics Data System (ADS)

The system we consider in this work is parallel coupled single-electron transistors (SETs) at strong coupling. For weak coupling, the transport characteristics of our coupled SETs are the same as those of the single SET, with the stability diagram exhibiting usual Coulomb diamonds. When the coupling becomes sufficiently strong, however, electron-hole binding and transport become important. In contrast to the previous works carried out in the cotunneling-dominating Coulomb blockade regime [1,2], we study e-h binding in the sequential-tunneling-dominating conducting regime. The major findings in this work are that the Coulomb diamonds in the conducting regime break up into fine internal structures at strong coupling, and that, although the cotunneling processes are much less frequent, they nonetheless play a crucial role. [1] D. V. Averin, A. N. Korotkov, and Yu. V. Nazarov, Phys. Rev. Lett. 66, 2818 (1991). [2] M. Matters, J. J. Versluys, and J. E. Mooij, Phys. Rev. Lett. 78, 2469 (1997).

Shin, Mincheol; Lee, Seongjae; Park, Kyoung Wan

2000-03-01

436

Instabilities of Coulomb phases and quark confinement in QCD

The Gribov picture to quark confinement is based on the Coulomb phase instability due to the very large values that the effective ?{sub s} coupling constant can reach in the infrared regime. The Gribov instability is driven by a vacuum decay into light quarks beyond a critical value of the coupling constant ?{sub s}3?(1-?(2/3))/4 (for SU(3) gauge group). From first principles it has been shown the existence of an instability of the Coulomb phase in pure gauge theories for ???(2), much beyond the Gribov critical value. In this paper we analyze the effect of dynamical quarks in the instability of the Coulomb phase. We find a critical value of the coupling ??=??(3) where a quark-antiquark pair creation mechanism leads to vacuum instability. However, the new critical value turns out to be larger than the pure gauge critical value ??=??(2), unlike it is expected in the standard Gribov scenario. The result is analytically derived from first principles and provides further consistency to the picture where quark confinement is mainly driven by gluonic fluctuation instabilities.

Asorey, Manuel; Santagata, Alessandro [Departamento de Física Teórica. Facultad de Ciencias, Universidad de Zaragoza. 50005 Zaragoza (Spain)

2014-07-23

437

NASA Astrophysics Data System (ADS)

Fluid injection in and withdrawal from wells are basic procedures in mining activities and deep resources exploitation, such as oil and gas extraction, permeability enhancement for geothermal exploitation and waste fluid disposal. All of these activities have the potential to induce seismicity, as exemplified by the 2006 Basel earthquake (ML 3.4). Despite several decades of experience, the mechanisms of induced seismicity are not known in detail, which prevents effective risk assessment and/or mitigation. In this study, we provide an interpretation of induced seismicity based on computation of Coulomb stress changes that result from fluid injection/withdrawal at depth, mainly focused on the interpretation of induced seismicity due to stimulation of a geothermal reservoir. Seismicity is, theoretically, more likely where Coulomb stress changes are larger. For modeling purposes, we simulate the thermodynamic evolution of a system after fluid injection/withdrawal. The associated changes in pressure and temperature are subsequently considered as sources of incremental stress changes, which are then converted to Coulomb stress changes on favourably oriented faults, taking into account the background regional stress. Numerical results are applied to the water injection that was performed to create the fractured reservoir at the enhanced-geothermal-system site, Soultz-sous-Forets (France). Our approach describes well the observed seismicity, and provides an explanation for the different behaviors of a system when fluids are injected or withdrawn.

Troiano, Antonio; Di Giuseppe, Maria Giulia; Troise, Claudia; Tramelli, Anna; De Natale, Giuseppe

2013-10-01

438

We describe a method for calculating the matrix elements of the Coulomb operator for Gaussian basis sets using an intermediate discrete Fourier transform of the density. Our goals are the same as those of the Gaussian and augmented-plane-wave method of Parrinello and co-workers [M. Krack and M. Parrinello, Phys. Chem. Chem. Phys. 2, 2105 (2000)], but our techniques are quite

Laszlo Fusti-Molnar; Peter Pulay

2002-01-01

439

NASA Astrophysics Data System (ADS)

The Canterbury sequence began with the M = 7.1 Darfield earthquake in September 2010 in an area of moderate known seismic hazard. It was followed in February 2011 by the M = 6.3 Christchurch earthquake which caused significant damage to the city. As of this writing, the sequence is continuing and the probability of future damaging events is still being evaluated. Here we present test results for 3 classes of models - Coulomb, statistical, and combined Coulomb/statistical - which we used to estimate likely aftershock rates following both the Darfield and Christchurch events. The models are constrained by the first 10 days of the aftershock sequences following each main earthquake. In particular, each set of early aftershocks is used to determine the receiver fault orientation for the Coulomb stress calculations, to constrain the rate-state parameters, and to determine the b and p values and the earthquake productivity rate. Rates are forecast for 30 days, and 3, 6, and 9 months into the future and compared to observation.

Steacy, S.; Gerstenberger, M. C.; Williams, C. A.; Rhoades, D.; Christophersen, A.

2011-12-01

440

Direction Controlled Coulomb Drag in Coupled One-Dimensional Quantum Wires

NASA Astrophysics Data System (ADS)

In a one-dimensional electron gas (1DEG) with sufficiently low density at low temperature, Coulomb interaction becomes so dominant that Wigner crystallization can occur. Wigner crystal (WC) is generally characterized by collective motion of electrons and strong incompressibility. Therefore, in the presence of an external electrostatic potential, electrons forming a WC do not contribute to microscopic screening and only respond rigidly, whereas those of a Fermi liquid (FL) freely move to screen the external potential and produce a correlation hole. In this work we show that the difference between WC and FL allows us to control the direction of Coulomb drag in coupled pairs of 1DEG wires, each having two 2DEG leads. We prepare parallel coupled pairs of quantum wires in a 2DEG defined by Schottky gates to study the current drag between the two wires. The distance between the two wires and the electron density in each wire are all tunable with gate voltages. We inject a constant current into one of the wires (drive wire) and measure the induced drag current (or voltage drop for Idrag = 0) in the other wire (drag wire). Electrons in the drive wire usually drag electrons in the drag wire in the same direction because momentum is conserved in Coulombic scattering between the wires. However, when the electron density in the drive wire is sufficiently low that the drive wire has charge inhomogeneity and the electrons in the drag wire are strongly correlated, i.e. at low density, high perpendicular magnetic field and low temperature, the direction of the drag current can be reversed. The sign reversal occurs only when the drive wire is adjacent to the boundary between the drag wire and its lead, and can be controlled by changing the geometry of the coupled wires. These behaviors can be modeled by electron pump from WC in the drag wire to its 2DEG lead, driven by particle-like electrons in the drive wire. The drive wire electrons induce a positive screening charge only in the FL lead, which attracts WC in the drag wire.

Yamamoto, Michihisa

2007-03-01

441

Appearance of interatomic Coulombic decay in Ar, Kr, and Xe homonuclear dimers

Interatomic Coulombic decay (ICD) is observed in the rare gas homonuclear dimers Ar{sub 2}, Kr{sub 2}, and Xe{sub 2} with photoion spectroscopy techniques. Inner valence ionization of the outer ns shell of these systems is known to create a metastable state that dissociates to form a ground state ion and a neutral excited fragment. Inner valence ionization to form ns satellite states leads to similar dissociations, but the neutral fragment gets all the more excited as the internal energy of the ns satellite state increases. When enough excitation energy is transferred to reach the ionization potential, ICD occurs. ICD threshold is observed to coincide with the position of the A{sup +}A{sup +} ground state in the Franck-Condon region.

Lablanquie, P.; Aoto, T.; Hikosaka, Y.; Morioka, Y.; Penent, F.; Ito, K. [LCP-MR, Universite Pierre et Marie Curie--Paris 6 et CNRS (UMR 7614), 11 Rue P et M Curie, 75231 Paris (France); Photon Factory, IMSS, Oho 1-1, Tsukuba 305-0801 (Japan); UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305 (Japan); LCP-MR, Universite Pierre et Marie Curie--Paris 6 et CNRS (UMR 7614), 11 Rue P et M Curie, 75231 Paris (France); Photon Factory, IMSS, Oho 1-1, Tsukuba 305-0801 (Japan)

2007-10-21

442

This article reports on a new charging process and Coulomb-force-directed assembly of nanoparticles onto charged surface areas with sub-100-nm resolution. The charging is accomplished using a flexible nanostructured thin silicon electrode. Electrical nanocontacts have been created as small as 50 nm by placing the nanostructured electrode onto an electret surface. The nanocontacts have been used to inject charge into 50 nm sized areas. Nanoparticles were assembled onto the charge patterns, and a lateral resolution of 60 nm has been observed for the first time. A comparison of the nanoparticle patterns with the surface potential distribution recorded by Kelvin probe force microscopy (KFM) revealed a mismatch in the lateral resolution. One possible explanation is that nanoparticles may visualize charge patterns at a sub-60-nm length scale that is not well resolved using KFM. PMID:16218741

Barry, Chad R; Gu, Jie; Jacobs, Heiko O

2005-10-01

443

Four-body effects on 9Be + 208Pb scattering and fusion around the Coulomb barrier

We investigate the 9Be + 208Pb elastic scattering and fusion at energies around the Coulomb barrier. The $^9$Be nucleus is described in a \\alpha + \\alpha + n three-body model, using the hyperspherical coordinate method. The scattering with $^{208}$Pb is then studied with the Continuum Discretized Coupled Channel (CDCC) method, where the \\alpha + \\alpha + n continuum is approximated by a discrete number of pseudostates. Optical potentials for the $\\alpha+^{208}$Pb and $n+^{208}$Pb systems are taken from the literature. We present elastic-scattering and fusion cross sections at different energies, and investigate the convergence with respect to the truncation of the \\alpha + \\alpha + n continuum. A good agreement with experiment is obtained, considering that there is no parameter fitting. We show that continuum effects increase at low energies.

P. Descouvemont; T. Druet; L. F. Canto; M. S. Hussein

2014-10-23

444

Fermi and Coulomb correlated relativistic local-density method for atoms

NASA Astrophysics Data System (ADS)

A parameter-free local-density method called the ? method was developed earlier for atoms [N. Vaidehi and M. S. Gopinathan, Phys. Rev. A 29, 1679 (1984)]. This method, which considered only the Fermi correlation in the potential, was shown to be close to Hartree-Fock accuracy. Its relativistic extension [V. Selvaraj and M. S. Gopinathan, Phys. Rev. A 29, 3007 (1984)] was also shown to give results that were close to Dirac-Hartree-Fock accuracy. In the present article, the relativistic ? method is modified by incorporating the spin-orbit interaction term in the Hamiltonian and the Coulomb correlation between the electrons of opposite spin. Using this fully correlated relativistic method, total energy, expectation values of rn (n=-1,1,2), and spin-orbit parameters for various atoms are calculated. Correlation energies for all the atoms in the Periodic Table are reported. Ionization energy and electron affinity of atoms are also discussed.

Vijayakumar, M.; Vaidehi, N.; Gopinathan, M. S.

1989-12-01

445

Existence and consequences of Coulomb pairing of electrons in a solid

It is shown from first principles that, in the periodic potential of a crystalline solid, short-range (i.e., screened) binary Coulomb interactions can lead to a two-electron bound state. It is further suggested that these composite bosonic states (charge -2e, and typically spin zero) could mediate an effectively attractive interaction between pairs of conduction electrons close to the Fermi level. This necessarily short range attractive interaction, which is crucially dependent on the band structure of the solid, and is complementary to the phonon-mediated one, may provide a source for the existence and properties of short correlation-length electron pairs (analogous to but distinct from Cooper pairs) needed to understand high temperature superconductivity. Several distinctive and observable characteristics of the proposed pairing scheme are discussed.

Mahajan, S.M. [Univ. of Texas, Austin, TX (United States); Thyagaraja, A. [UKAEA, Abingdon (United Kingdom). Fusion Physics

1996-11-01

446

Flavor constraints on two-Higgs-doublet models with general diagonal Yukawa couplings

We consider constraints from flavor physics on two-Higgs-doublet models (2HDM) with general, flavor-diagonal, Yukawa couplings. Analyzing the charged Higgs contribution to different observables, we find that b{yields}s{gamma} transitions and {Delta}M{sub B{sub d}} restrict the coupling {lambda}{sub tt} of the top quark (corresponding to cot{beta} in models with a Z{sub 2} symmetry) to |{lambda}{sub tt}|<1 for m{sub H}{sup +} < or approx. 500 GeV. Stringent constraints from B meson decays are obtained also on the other third generation couplings {lambda}{sub bb} and {lambda}{sub {tau}{tau},} but with stronger dependence on m{sub H}{sup +}. For the second generation, we obtain constraints on combinations of {lambda}{sub ss}, {lambda}{sub cc}, and {lambda}{sub {mu}{mu}}from leptonic K and D{sub s} decays. The limits on the general couplings are translated to the common 2HDM types I-IV with a Z{sub 2} symmetry, and presented on the (m{sub H}{sup +},tan{beta}) plane. The flavor constraints are most excluding in the type II model which lacks a decoupling limit in tan{beta}. We obtain a lower limit m{sub H}{sup +} > or approx. 300 GeV in models of type II and III, while no lower bound on m{sub H}{sup +} is found for types I and IV.

Mahmoudi, F. [Clermont Universite, Universite Blaise Pascal, CNRS/IN2P3, LPC, BP 10448, 63000 Clermont-Ferrand (France); Staal, O. [High-Energy Physics, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala (Sweden)

2010-02-01

447

We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed. PMID:25381536

Rane, Kaustubh S; Errington, Jeffrey R

2014-11-01

448

NASA Astrophysics Data System (ADS)

We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed.

Rane, Kaustubh S.; Errington, Jeffrey R.

2014-11-01

449

NASA Astrophysics Data System (ADS)

We present a genetic algorithm based investigation of structural fragmentation in dicationic noble gas clusters, Arn+2, Krn+2, and Xen+2, where n denotes the size of the cluster. Dications are predicted to be stable above a threshold size of the cluster when positive charges are assumed to remain localized on two noble gas atoms and the Lennard-Jones potential along with bare Coulomb and ion-induced dipole interactions are taken into account for describing the potential energy surface. Our cutoff values are close to those obtained experimentally [P. Scheier and T. D. Mark, J. Chem. Phys. 11, 3056 (1987)] and theoretically [J. G. Gay and B. J. Berne, Phys. Rev. Lett. 49, 194 (1982)]. When the charges are allowed to be equally distributed over four noble gas atoms in the cluster and the nonpolarization interaction terms are allowed to remain unchanged, our method successfully identifies the size threshold for stability as well as the nature of the channels of dissociation as function of cluster size. In Arn2+, for example, fissionlike fragmentation is predicted for n =55 while for n =43, the predicted outcome is nonfission fragmentation in complete agreement with earlier work [Golberg et al., J. Chem. Phys. 100, 8277 (1994)].

Nandy, Subhajit; Chaudhury, Pinaki; Bhattacharyya, S. P.

2010-06-01

450

Extraction of nucleus-nucleus potential and energy dissipation from dynamical mean-field theory

Nucleus-nucleus interaction potentials in heavy-ion fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory. When the center-of-mass energy is much higher than the Coulomb barrier energy, extracted potentials identify with the frozen density approximation. As the center-of-mass energy decreases to the Coulomb barrier energy, potentials become energy dependent. This dependence indicates dynamical reorganization of internal degrees of freedom and leads to a reduction of the ''apparent'' barrier. Including this effect leads to the Coulomb barrier energy very close to experimental one. Aspects of one-body energy dissipation extracted from the mean-field theory are discussed.

Washiyama, Kouhei; Lacroix, Denis [GANIL, BP55027, 14076 Caen (France)

2009-03-04

451

Cosmological consequences of Yukawa-unified SUSY with mixed axion/axino cold and warm dark matter

Supersymmetric models with t-b-{tau} Yukawa unification at M{sub GUT} qualitatively predict a sparticle mass spectrum including first and second generation scalars at the 3-15 TeV scale, third generation scalars at the (few) TeV scale and gluinos in the sub-TeV range. The neutralino relic density in these models typically turns out to lie far above the measured dark matter abundance, prompting the suggestion that instead dark matter is composed of an axion/axino mixture. We explore the axion and thermal and non-thermal axino dark matter abundance in Yukawa-unified SUSY models. We find in this scenario that (i) rather large values of Peccei-Quinn symmetry breaking scale f{sub a} {approx} 10{sup 12} GeV are favored and (ii) rather large values of GUT scale scalar masses {approx} 10-15 TeV allow for the re-heat temperature T{sub R} of the universe to be T{sub R} {approx}> 10{sup 6} GeV. This allows in turn a solution to the gravitino/Big Bang Nucleosynthesis problem while also allowing for baryogenesis via non-thermal leptogenesis. The large scalar masses for Yukawa-unified models are also favored by data on b {yields} s{gamma} and B{sub s} {yields} {mu}{sup +}{mu}{sup -} decay. Testable consequences from this scenario include a possible axion detection at axion search experiments, but null results from direct and indirect WIMP search experiments.

Baer, Howard; Summy, Heaya [Dept. of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, OK 73019 (United States)] [Dept. of Physics and Astronomy, University of Oklahoma, 440 West Brooks, Norman, OK 73019 (United States); Haider, Markus; Kraml, Sabine [Laboratoire de Physique Subatomique et de Cosmologie, UJF Grenoble 1, CNRS/IN2P3, INPG, 53 Avenue des Martyrs, F-38026 Grenoble (France)] [Laboratoire de Physique Subatomique et de Cosmologie, UJF Grenoble 1, CNRS/IN2P3, INPG, 53 Avenue des Martyrs, F-38026 Grenoble (France); Sekmen, Sezen, E-mail: baer@nhn.ou.edu, E-mail: markus.haider@lpsc.in2p3.fr, E-mail: sabine.kraml@lpsc.in2p3.fr, E-mail: sezen.sekmen@cern.ch, E-mail: heaya@nhn.ou.edu [Department of Physics, Middle East Technical Univ., Inoenue Boulevard, TR-06531 Ankara (Turkey)] [Department of Physics, Middle East Technical Univ., Inoenue Boulevard, TR-06531 Ankara (Turkey)

2009-02-15

452

Imaging of Acoustic Waves in Piezoelectric Ceramics by Coulomb Coupling

NASA Astrophysics Data System (ADS)

The transport properties of bulk and guided acoustic waves travelling in a lead zirconate titanate (PZT) disc, originally manufactured to serve as ultrasonic transducer, have been monitored by scanned Coulomb coupling. The images are recorded by excitation and detection of ultrasound with local electric field probes via piezoelectric coupling. A narrow pulse has been used for excitation. Broadband coupling is achieved since neither mechanical nor electrical resonances are involved. The velocities of the traveling acoustic waves determined from the images are compared with characteristic velocities calculated from material properties listed by the manufacturer of the PZT plate.

Habib, Anowarul; Shelke, Amit; Pluta, Mieczyslaw; Kundu, Tribikram; Pietsch, Ullrich; Grill, Wolfgang

2012-07-01

453

Coulomb entangler and entanglement-testing network for waveguide qubits

We present a small network for the testing of the entanglement of two ballistic electron waveguide qubits. The network produces different output conditional on the presence or absence of entanglement. The structure of the network allows for the determination of successful entanglement operations through the measurement of the output of a single qubit. We also present a simple model of a dynamic Coulomb-like interaction and use it to describe some characteristics of a proposed scheme for the entanglement of qubits in ballistic electron waveguides.

Reichl, Linda E.; Snyder, Michael G. [Center for Studies in Statistical Mechanics and Complex Systems, University of Texas at Austin, Austin, Texas 78712 (United States)

2005-09-15

454

Persistent currents in annuli: effects of disorder and Coulomb interaction

NASA Astrophysics Data System (ADS)

We investigate the persistent current of spinless electrons in a mesoscopic annulus threaded by a magnetic flux. As in the tight-binding systems, the excitations in the radial direction generate additional discontinuities in the persistent current, which are rounded off by disorder. The Coulomb interaction, the effects of which are investigated within the Hartree - Fock approximation, is found to suppress the persistent current in the presence of weak disorder. For strong disorder corresponding to the diffusive regime, the persistent current is enhanced by weak interactions.

Jeon, Gun Sang; Choi, M. Y.

1996-06-01

455

Numerical studies of a simple Coulomb blockade model

simple model of the Coulomb blockade is studied. In this model, two interacting electrons tunnel in a one-dimensional structure with two barriers in series. The two-particle, time-dependent Schrodinger equation is solved numerically. It is found... tunneling by the other, and the inside electron tunnels out only after the outside electron tunnels a second time. The distribution of the charge density for the two electrons is shown in a series of three-dimensional figures as a function of time. Also...

Shao, Jianfeng

1991-01-01

456

A proposal for Coulomb assisted laser cooling of piezoelectric semiconductors

Anti-Stokes laser cooling of semiconductors as a compact and vibration-free method is very attractive. While it has achieved significant milestones, increasing its efficiency is highly desirable. The main limitation is the lack of the pristine material quality with high luminescence efficiency. Here, we theoretically demonstrate that the Coulomb interaction among electrons and holes in piezoelectric heterostructures could lead to coherent damping of acoustic phonons; rendering a significantly higher efficiency that leads to the possibility of cooling a broad range of semiconductors.

Nia, Iman Hassani; Mohseni, Hooman, E-mail: hmohseni@ece.northwestern.edu [Bio-Inspired Sensors and Optoelectronics Laboratory (BISOL), Department of Electrical Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

2014-07-28

457

Statistical correlations in a Coulomb gas with a test charge

A recent paper [Jokela et al, arxiv:0806.1491 9 June 2008] contains a surmise about an expectation value in a Coulomb gas which interacts with an additional charge xi that sits at a fixed position. Here I demonstrate the validity of the surmised expression and extend it to a certain class of higher cumulants. The calculation is based on the analogy to statistical averages in the circular unitary ensemble of random-matrix theory and exploits properties of orthogonal polynomials on the unit circle.

Henning Schomerus

2008-07-01

458

Photodetachment of hydrogen negative ions with screened Coulomb interaction

The effects of Coulomb interaction screening on photodetachment cross sections of hydrogen negative ions below the n =2 excitation threshold is investigated by using the R-matrix method with pseudostates. The contributions of Feshbach and shape resonances to H{sup -} photodetachment cross section are presented when screening length (D) varies from D = {infinity} to D = 4.6 a.u. It is found that the interaction screening has dramatic effects on the photodetachment cross sections of hydrogen negative ions in the photoelectron energy region around the n = 2 excitation threshold by strongly affecting the evolution of near-threshold resonances.

Zhang, Song Bin; Chen, Xiang Jun [Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Wang, Jian Guo [The Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China); Janev, R. K. [Macedonian Academy of Sciences and Arts, PO Box 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Qu, Yi Zhi [College of Material Sciences and Optoelectronic Technology, Graduate School of the Chinese Academy of Sciences, PO Box 4588, Beijing 100049 (China)

2010-06-15

459

Multi electron species and shielding potentials in plasmas

The phenomenon of Debye shielding is investigated in electron ion plasmas using the approach of two temperature electrons. We get different profiles of potential for different parameters and observe that the potentials fall very slowly than the standard Coulomb and Debye potentials. The importance of work is pointed out in the introduction.

Khan, Arroj A.; Murtaza, G. [Salam Chair in Physics, Government College University, Lahore 54000 (Pakistan); Rasheed, A.; Jamil, M. [Department of Physics, Government College University, Faisalabad 38000 (Pakistan)

2012-11-15

460

A possible generalization of the harmonic oscillator potential

NASA Technical Reports Server (NTRS)

A four-parameter potential is analyzed, which contains the three-dimensional harmonic oscillator as a special case. This potential is exactly solvable and retains several characteristics of the harmonic oscillator, and also of the Coulomb problem. The possibility of similar generalizations of other potentials is also pointed out.

Levai, Geza

1995-01-01

461

Modeling Coulombic failure of sea ice with leads

NASA Astrophysics Data System (ADS)

Sea ice failure under low-confinement compression is modeled with a linear Coulombic criterion that can describe either fractural failure or frictional granular yield along slip lines. To study the effect of anisotropy we consider a simplified anisotropic sea ice model where the sea ice thickness depends on orientation. Accommodation of arbitrary deformation requires failure along at least two intersecting slip lines, which are determined by finding two maxima of the yield criterion. Due to the anisotropy these slip lines generally differ from the standard, Coulombic slip lines that are symmetrically positioned around the compression direction, and therefore different tractions along these slip lines give rise to a nonsymmetric stress tensor. We assume that the skewsymmetric part of this tensor is counterbalanced by an additional elastic stress in the sea ice field that suppresses floe spin. We consider the case of two leads initially formed in an isotropic ice cover under compression, and address the question of whether these leads will remain active or new slip lines will form under a rotation of the principal compression direction. Decoupled and coupled models of leads are considered and it is shown that for this particular case they both predict lead reactivation in almost the same way. The coupled model must, however, be used in determining the stress as the decoupled model does not resolve the stress asymmetry properly when failure occurs in one lead and at a new slip line.

Wilchinsky, Alexander V.; Feltham, Daniel L.

2011-08-01

462

Coulomb excitation of a {sup 78}Rb radioactive beam.

In order to test the feasibility of Coulomb excitation of radioactive projectiles with low beam energies and intensities, they have produced a secondary radioactive beam of {sup 78}Rb and