Sample records for coulomb yukawa potentials

  1. Folded potentials in cluster physics - a comparison of Yukawa and Coulomb potentials with Riesz fractional integrals

    E-print Network

    R. Herrmann

    2013-09-20

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

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

    Microsoft Academic Search

    Janusz Adamowski

    1985-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Adamowski, Janusz

    1985-01-01

    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

  4. Amplification of coupling for Yukawa potentials

    E-print Network

    S. De Leo; P. Rotelli

    2004-11-09

    It is well known that Yukawa potentials permit bound states in the Schrodinger equation only if the ratio of the exchanged mass to bound mass is below a critical multiple of the coupling constant. However, arguments suggested by the Darwin term imply a more complex situation. By numerically studying the Dirac equation with a Yukawa potential we investigate this amplification effect.

  5. Approximate -state Solutions to the Dirac Mobius Square-Yukawa and Mobius Square-quasi Yukawa Problems under Pseudospin and Spin Symmetry limits with Coulomb-like Tensor Interaction

    E-print Network

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

    2012-10-30

    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

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

    SciTech Connect

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

    2007-02-07

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

  7. Yukawa particles in a confining potential

    SciTech Connect

    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

    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.

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

    SciTech Connect

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

    2011-09-15

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

  9. Approximate spin and pseudospin solutions of the Dirac equation for the inversely quadratic Yukawa potential and tensor interaction

    E-print Network

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

    2012-03-30

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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

  11. OBSERVATIONAL EVIDENCE FOR DARK MATTER INTERACTING THROUGH A YUKAWA POTENTIAL

    SciTech Connect

    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

    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.

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

    ERIC Educational Resources Information Center

    Francisco, E.; And Others

    1988-01-01

    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)

  13. Three-dimensional stereoscopy of Yukawa (Coulomb) balls in dusty plasmas

    SciTech Connect

    Kaeding, Sebastian; Melzer, Andre [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, 17489 Greifswald (Germany)

    2006-09-15

    A stereoscopic approach with standard video cameras for positioning and tracking of micrometer sized polymer particles in a radio-frequency gas discharge is presented. The stereoscopy is applied to simultaneously determine the positions of all particles in a three-dimensional strongly coupled spherical dusty plasma (Yukawa ball). The accuracy of the stereoscopic method is discussed. The shell structure and the occupation number of various Yukawa balls are determined and compared to recent simulations and models.

  14. Quantum gravity and the Coulomb potential

    SciTech Connect

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

    2007-10-15

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

  15. Positron scattering from hydrogen atom with screened Coulomb potentials

    SciTech Connect

    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

    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.

  16. Kinematics-free angular momentum trajectories. II. Yukawa-potential numerical examples

    Microsoft Academic Search

    Robert A. Leacock; Russell L. Martin

    1979-01-01

    The kinematics-free angular momentum trajectory, called the gamma trajectory, is illustrated numerically in nonrelativistic potential scattering using Yukawa and exponential potentials of various strengths. The gamma trajectory, in contrast to the alpha (Regge) trajectory, is free of elastic kinematics and so is real for all energies above threshold and real for certain energies below threshold. Resonances are caused when the

  17. Kinematics-free angular momentum trajectories. II. Yukawa-potential numerical examples

    Microsoft Academic Search

    Robert Leacock; Russell Martin

    1979-01-01

    The kinematics-free angular momentum trajectory, called the ..gamma.. trajectory, is illustrated numerically in nonrelativistic potential scattering using Yukawa and exponential potentials of various strengths. The ..gamma.. trajectory, in contrast to the ..cap alpha.. (Regge) trajectory, is free of elastic kinematics and so is real for all energies above threshold and real for certain energies below threshold. Resonances are caused when

  18. Superintegrability of (generalized) Calogero models with oscillator or Coulomb potential

    E-print Network

    Tigran Hakobyan; Olaf Lechtenfeld; Armen Nersessian

    2014-09-29

    We deform N-dimensional (Euclidean, spherical and hyperbolic) oscillator and Coulomb systems, replacing their angular degrees of freedom by those of a generalized rational Calogero model. Using the action-angle description, it is established that maximal superintegrability is retained. For the rational Calogero model with Coulomb potential, we present all constants of motion via matrix model reduction. In particular, we construct the analog of the Runge-Lenz vector.

  19. Analytic Solution of Ground State for Coulomb Plus Linear Potential

    E-print Network

    W. Q. Chao; C. S. Ju

    2001-11-26

    The newly developed single trajectory quadrature method is applied to solve the ground state quantum wave function for Coulomb plus linear potential. The general analytic expressions of the energy and wave function for the ground state are given. The convergence of the solution is also discussed. The method is applied to the ground state of the heavy quarkonium system.

  20. Modified Coulomb potential of QED in a strong magnetic field

    Microsoft Academic Search

    Néda Sadooghi

    2007-01-01

    The static Coulomb potential of Quantum Electrodynamics is calculated in the presence of a strong magnetic field by computing perturbatively the vacuu m expectation value of the cor- responding Wilson loop in the lowest Landau level (LLL) approximation. In the LLL, two different regimes of dynamical mass, mdyn., can be distinguished. These two regimes are |q2k | ? m 2

  1. Nonlinear compressional waves in a two-dimensional Yukawa lattice K. Avinash, P. Zhu, V. Nosenko, and J. Goree*

    E-print Network

    Goree, John

    transitions, phonon propagation, and sublimation. Typical examples of 1D systems are quantum wires 4 , one interact with each other via a Yukawa or screened-Coulomb potential. Most commonly, particles are levitated

  2. Cores in Dwarf Galaxies from Dark Matter with a Yukawa Potential

    E-print Network

    Abraham Loeb; Neal Weiner

    2010-11-29

    We show that cold dark matter particles interacting through a Yukawa potential could naturally explain the recently observed cores in dwarf galaxies without affecting the dynamics of objects with a much larger velocity dispersion, such as clusters of galaxies. The velocity dependence of the associated cross-section as well as the possible exothermic nature of the interaction alleviates earlier concerns about strongly interacting dark matter. Dark matter evaporation in low-mass objects might explain the observed deficit of satellite galaxies in the Milky Way halo and have important implications for the first galaxies and reionization.

  3. Cores in dwarf galaxies from dark matter with a Yukawa potential.

    PubMed

    Loeb, Abraham; Weiner, Neal

    2011-04-29

    We show that cold dark matter particles interacting through a Yukawa potential could naturally explain the recently observed cores in dwarf galaxies without affecting the dynamics of objects with a much larger velocity dispersion, such as clusters of galaxies. The velocity dependence of the associated cross section as well as the possible exothermic nature of the interaction alleviates earlier concerns about strongly interacting dark matter. Dark matter evaporation in low-mass objects might explain the observed deficit of satellite galaxies in the Milky Way halo and have important implications for the first galaxies and reionization. PMID:21635025

  4. Cores in Dwarf Galaxies from Dark Matter with a Yukawa Potential

    NASA Astrophysics Data System (ADS)

    Loeb, Abraham; Weiner, Neal

    2011-04-01

    We show that cold dark matter particles interacting through a Yukawa potential could naturally explain the recently observed cores in dwarf galaxies without affecting the dynamics of objects with a much larger velocity dispersion, such as clusters of galaxies. The velocity dependence of the associated cross section as well as the possible exothermic nature of the interaction alleviates earlier concerns about strongly interacting dark matter. Dark matter evaporation in low-mass objects might explain the observed deficit of satellite galaxies in the Milky Way halo and have important implications for the first galaxies and reionization.

  5. Heavy quarks, gluons and the confinement potential in Coulomb gauge

    SciTech Connect

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

    2011-05-23

    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.

  6. Zero range potential for particles interacting via Coulomb potential: application to electron positron annihilation

    E-print Network

    S. L. Yakovlev; V. A. Gradusov

    2012-06-25

    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.

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

    NASA Astrophysics Data System (ADS)

    Liverts, E. Z.; Mandelzweig, V. B.

    2009-02-01

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

  8. Effective Mass Quantum Systems with Displacement Operator: Inverse Square plus Coulomb-like Potential

    E-print Network

    Altug Arda; Ramazan Sever

    2015-05-28

    The Schr\\"odinger-like equation written in terms of the displacement operator is solved analytically for a inverse square plus Coulomb-like potential. Starting from the new Hamiltonian, the effects of the spatially dependent mass on the bound states and normalized wave functions of the "usual" inverse square plus Coulomb interaction are discussed.

  9. On the Klein-Gordon oscillator subject to a Coulomb-type potential

    E-print Network

    K. Bakke; C. Furtado

    2014-11-25

    By introducing the scalar potential as modification in the mass term of the Klein-Gordon equation, the influence of a Coulomb-type potential on the Klein-Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein-Gordon oscillator on the quantum numbers of the system is shown.

  10. On the Klein-Gordon oscillator subject to a Coulomb-type potential

    NASA Astrophysics Data System (ADS)

    Bakke, K.; Furtado, C.

    2015-04-01

    By introducing the scalar potential as modification in the mass term of the Klein-Gordon equation, the influence of a Coulomb-type potential on the Klein-Gordon oscillator is investigated. Relativistic bound states solutions are achieved to both attractive and repulsive Coulomb-type potentials and the arising of a quantum effect characterized by the dependence of angular frequency of the Klein-Gordon oscillator on the quantum numbers of the system is shown.

  11. Approximate bound-state solutions of the Dirac equation for the generalized yukawa potential plus the generalized tensor interaction

    NASA Astrophysics Data System (ADS)

    Ikot, Akpan N.; Maghsoodi, Elham; Hassanabadi, Hassan; Obu, Joseph A.

    2014-05-01

    In this paper, we obtain the approximate analytical bound-state solutions of the Dirac particle with the generalized Yukawa potential within the framework of spin and pseudospin symmetries for the arbitrary ? state with a generalized tensor interaction. The generalized parametric Nikiforov-Uvarov method is used to obtain the energy eigenvalues and the corresponding wave functions in closed form. We also report some numerical results and present figures to show the effect of the tensor interaction.

  12. 'Spectrum generating algebras' of classical systems: the Kepler-Coulomb potential

    NASA Astrophysics Data System (ADS)

    Kuru, ?.; Negro, J.

    2012-02-01

    We construct the classical 'spectrum generating algebra' for the Kepler-Coulomb potential and find a type of constants of motion depending explicitly on time. Such constants give rise to the motion of this system in an algebraic way.

  13. Three-layer dielectric models for generalized Coulomb potential calculation in ellipsoidal geometry

    Microsoft Academic Search

    Changfeng Xue; Shaozhong Deng

    2011-01-01

    This paper concerns a basic electrostatic problem: how to calculate generalized Coulomb and self-polarization potentials in heterogeneous dielectric media. In particular, with simulations of ellipsoidal semiconductor quantum dots and elongated biomacromolecules being its target applications, this paper extends the so-called three-layer dielectric models for generalized Coulomb and self-polarization potential calculation from the spherical and the spheroidal geometries to the triaxial

  14. A Simple Efficient Method for Obtaining the Binding Energy of Lithium Nucleus under the Hulthén and Inversely Quadratic Yukawa Potentials

    E-print Network

    Nasrin. Salehi; Mahsa. Ghazvini

    2015-04-28

    In this paper, the binding energy of Lithium nucleus in a nonrelativistic model is obtained for the Hulth\\'en and the Inversely Quadratic Yukawa Potential. In order to that, we used the concept of supersymmetry to solving the Schr\\"odinger equation exact analytically. These potentials, due to their physical interpretations, are of interest within many areas of theoretical physics. The results of our model for all calculations show that the ground state binding energy of Lithium nucleus with these potentials are very close to the ones obtained in experiments.

  15. Instabilities in strongly coupled Yukawa liquids

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    Yukawa systems are systems of charged particles that interact via a screened Coulomb (Yukawa) interaction. If the electrostatic potential energy between neighboring charged particles is much larger than their thermal (kinetic) energy but smaller than that required for crystallization the system is in the strongly coupled liquid phase. Various plasmas such as dusty plasmas or ultracold neutral plasmas can exist in this liquid phase. Here, we investigate several streaming instabilities in the strongly coupled liquid phase of dusty plasmas, including (1) a dust-dust instability and (2) a dust acoustic instability. Applications to possible experimental parameters are discussed. Work partially supported by NSF Grant PHY-0903808 and NASA Grant NNX10AR54G.

  16. Calculation of Transport Coefficients in Binary Yukawa Mixtures

    NASA Astrophysics Data System (ADS)

    Haxhimali, Tomorr; Rudd, Robert

    2012-02-01

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

  17. Optimized periodic 1/r Coulomb potential in two dimensions Markus Holzmann *, Bernard Bernu

    E-print Network

    Optimized periodic 1/r Coulomb potential in two dimensions Markus Holzmann *, Bernard Bernu potential is calculated for a two dimensional system with periodic boundary conditions. Using polynomial allow us efficient calculations of any periodic (long-ranged) potential up to high precision. We discuss

  18. Pseudospin and spin symmetries in 1+1 dimensions: The case of the Coulomb potential

    NASA Astrophysics Data System (ADS)

    Castro, Luis B.; de Castro, Antonio S.; Alberto, Pedro

    2015-05-01

    The problem of fermions in 1+1 dimensions in the presence of a pseudoscalar Coulomb potential plus a mixing of vector and scalar Coulomb potentials which have equal or opposite signs is investigated. We explore all the possible signs of the potentials and discuss their bound-state solutions for fermions and antifermions. We show the relation between spin and pseudospin symmetries by means of charge-conjugation and ?5 chiral transformations. The cases of pure pseudoscalar and mixed vector-scalar potentials, already analyzed in previous works, are obtained as particular cases. The results presented can be extended to 3+1 dimensions.

  19. Dynamic polarization potential induced by the Coulomb excitation of deformed heavy ions: Geometric scattering approach

    SciTech Connect

    Takigawa, N. (Department of Physics, Tohoku University, 980 Sendai, Japan (JP)); Michel, F. (Faculte des Sciences, Universite de Mons-Hainaut, B-7000 Mons, (Belgium)); Balantekin, A.B. (Physics Department, University of Wisconsin, Madison, Wisconsin 53706 (USA)); Reidemeister, G. (Faculte des Sciences, Universite Libre de Bruxelles, B-1050 Bruxelles, (Belgium))

    1991-07-01

    The geometric scattering theory and the Wentzel-Kramers-Brillouin (WKB) approximation are used to derive explicit expressions for the dynamic polarization potential induced by Coulomb excitation in heavy-ion collisions involving strongly deformed targets. We build two phase-equivalent potentials with very different radial and angular-momentum behaviors, which are discussed in the context of polarization potentials obtained previously within different frameworks. This correspondence provides a recipe for approximately correcting the deficiencies of the geometric scattering approach, which tends to overemphasize the effects of Coulomb coupling.

  20. Periodically driven dynamics of a particle moving in the field of Coulomb plus confining potential

    E-print Network

    D. U. Matrasulov; P. K. Khabibullaev; F. C. Khanna; D. M. Otajanov

    2011-06-24

    Periodically driven dynamics of a particle moving in the field Coulomb plus confining potential is treated for one and three dimensional cases. Critical value of the external field strength at which chaotization will occur is evaluated analytically based on the resonance overlap criterion. The analysis of the phase-space dynamics is presented.

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

    E-print Network

    Kouhei Washiyama; Denis Lacroix

    2008-08-12

    The nucleus-nucleus interaction potentials in heavy-ion fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory for mass symmetric reactions $^{16}$O${}+^{16}$O, $^{40}$Ca${}+^{40}$Ca, $^{48}$Ca${}+^{48}$Ca and mass asymmetric reactions $^{16}$O$ +^{40,48}$Ca, $^{40}$Ca${}+^{48}$Ca, $^{16}$O+$^{208}$Pb, $^{40}$Ca+$^{90}$Zr. When the center-of-mass energy is much higher than the Coulomb barrier energy, potentials deduced with the microscopic theory identify with the frozen density approximation. As the center-of-mass energy decreases and approaches the Coulomb barrier, potentials become energy dependent. This dependence signs 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 center-of-mass 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.

  2. Analytic solutions of the double ring-shaped Coulomb potential in quantum mechanics

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Yuan; Lu, Fa-Lin; Sun, Dong-Sheng; Dong, Shi-Hai

    2013-10-01

    The exact solutions of the Schrödinger equation with the double ring-shaped Coulomb potential are presented, including the bound states, continuous states on the “?/2? scale", and the calculation formula of the phase shifts. The polar angular wave functions are expressed by constructing the so-called super-universal associated Legendre polynomials. Some special cases are discussed in detail.

  3. The Klein-Gordon Equation for the Coulomb Potential in Non-commutative Space

    E-print Network

    Amin Rezaei Akbarieh; Hossein Motavalli

    2009-11-25

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

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

    SciTech Connect

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

    2011-07-15

    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.

  5. Range effects of the Coulombic forces on structures, thermodynamic properties and potential energy landscapes: (KCl)32 and related systems

    E-print Network

    Berry, R. Stephen

    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

  6. Virial theorem and Gibbs thermodynamic potential for Coulomb systems

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  7. Continuum resonances with shielded Coulomb-like potential and Efimov effect

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  8. New look at the modified Coulomb potential in a strong magnetic field

    Microsoft Academic Search

    N. Sadooghi; A. Sodeiri Jalili

    2007-01-01

    The static Coulomb potential of quantum electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass m{sub dyn}, i.e., |q{sub parallel}²|<

  9. New look at the modified Coulomb potential in a strong magnetic field

    Microsoft Academic Search

    N. Sadooghi; A. Sodeiri Jalili

    2007-01-01

    The static Coulomb potential of quantum electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass mdyn, i.e., |q||2|≪mdyn2≪|eB| and mdyn2≪|q||2|≪|eB|, where q|| is the longitudinal component of

  10. Unfamiliar trajectories for a relativistic particle in a Kepler or Coulomb potential

    E-print Network

    Timothy H. Boyer

    2004-05-17

    Relativistic particles in the Kepler and Coulomb potentials may have trajectories that are qualitatively different from the trajectories found in nonrelativistic mechanics. Spiral scattering trajectories were pointed out by C. G. Darwin in 1913 in connection with the relativistic Rutherford scattering of classical charged particles. Relativistic trajectories are of current interest in connection with Cole and Zou's computer simulation of the hydrogen ground state in classical physics.

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

    SciTech Connect

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

    2005-06-01

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

  12. Nuclear mass formula with a finite-range droplet model and a folded-Yukawa single-particle potential

    SciTech Connect

    Moeller, P.; Myers, W.D.; Swiatecki, W.J.; Treiner, J.

    1988-07-01

    We calculate ground-state masses for 4678 nuclei ranging from /sup 16/O to /sup 318/122 by use of a macroscopic-microscopic model, which incorporates several new features. For the macroscopic model we use the finite-range droplet model which we introduced in 1984. The microscopic contribution is taken from a calculation based on a folded-Yukawa single-particle potential. Some new features now incorporated are a new model for the average pairing strength and the solution of the microscopic pairing equations by use of the Lipkin-Nogami method with approximate particle number conservation. To estimate the parameters of the macroscopic model we use an approach that starts by defining the error of a mass formula in a rigorous way, which leads naturally to the use of experimental uncertainties and of the maximum-likelihood method to derive a set of equations for estimating the parameters and error of the theoretical model. By considering 1593 experimental masses from /sup 16/O to /sup 263/106 we estimate the error of the theoretical model to be 0.769 MeV. The model retains its accuracy far from stability and the values of the model parameters are very insensitive to details of the adjustment procedure. copyright 1988 Academic Press, Inc.

  13. A new look at the modified Coulomb potential in a strong magnetic field

    E-print Network

    N. Sadooghi; A. Sodeiri Jalili

    2007-07-17

    The static Coulomb potential of Quantum Electrodynamics (QED) is calculated in the presence of a strong magnetic field in the lowest Landau level (LLL) approximation using two different methods. First, the vacuum expectation value of the corresponding Wilson loop is calculated perturbatively in two different regimes of dynamical mass $m_{dyn.}$, {\\it i.e.}, $|{\\mathbf{q}}_{\\|}^{2}|\\ll m_{dyn.}^{2}\\ll |eB|$ and $m_{dyn.}^{2}\\ll |\\mathbf{q}_{\\|}^{2}|\\ll|eB|$, where $\\mathbf{q}_{\\|}$ is the longitudinal components of the momentum relative to the external magnetic field $B$. The result is then compared with the static potential arising from Born approximation. Both results coincide. Although the arising potentials show different behavior in the aforementioned regimes, a novel dependence on the angle $\\theta$ between the particle-antiparticle's axis and the direction of the magnetic field is observed. In the regime $|{\\mathbf{q}}_{\\|}^{2}|\\ll m_{dyn.}^{2}\\ll |eB|$, for strong enough magnetic field and depending on the angle $\\theta$, a qualitative change occurs in the Coulomb-like potential; Whereas for $\\theta=0,\\pi$ the potential is repulsive, it exhibits a minimum for angles $\\theta\\in]0,\\pi[$.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    SciTech Connect

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

    2009-01-01

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

  16. A Simple Efficient Method for Obtaining the Binding Energy of Lithium Nucleus under the Hulth\\'en and Inversely Quadratic Yukawa Potentials

    E-print Network

    Salehi, Nasrin

    2015-01-01

    In this paper, the binding energy of Lithium nucleus in a nonrelativistic model is obtained for the Hulth\\'en and the Inversely Quadratic Yukawa Potential. In order to that, we used the concept of supersymmetry to solving the Schr\\"odinger equation exact analytically. These potentials, due to their physical interpretations, are of interest within many areas of theoretical physics. The results of our model for all calculations show that the ground state binding energy of Lithium nucleus with these potentials are very close to the ones obtained in experiments.

  17. Three-layer dielectric models for generalized Coulomb potential calculation in ellipsoidal geometry.

    PubMed

    Xue, Changfeng; Deng, Shaozhong

    2011-05-01

    This paper concerns a basic electrostatic problem: how to calculate generalized Coulomb and self-polarization potentials in heterogeneous dielectric media. In particular, with simulations of ellipsoidal semiconductor quantum dots and elongated biomacromolecules being its target applications, this paper extends the so-called three-layer dielectric models for generalized Coulomb and self-polarization potential calculation from the spherical and the spheroidal geometries to the triaxial ellipsoidal geometry. Compared to the simple steplike dielectric model, these three-layer dielectric models can overcome the mathematical divergence in the self-polarization energy by employing continuous radial dielectric functions. More specifically, in this paper, the quasiharmonic three-layer dielectric model for the ellipsoidal geometry is discussed, and the explicit analytical series solutions of the corresponding electrostatic problem are obtained in terms of the ellipsoidal harmonics. Then a robust numerical procedure working for general three-layer dielectric models is developed. The key component of the numerical method is to subdivide the transition layer of the underlying three-layer model into multiple sublayers and then in each one of them approximate the select dielectric function of the transition layer by one of the quasiharmonic functional form rather than simply by a constant value as one would normally do. As a result, the numerical method has no numerical divergence. PMID:21728695

  18. Three-layer dielectric models for generalized Coulomb potential calculation in ellipsoidal geometry

    NASA Astrophysics Data System (ADS)

    Xue, Changfeng; Deng, Shaozhong

    2011-05-01

    This paper concerns a basic electrostatic problem: how to calculate generalized Coulomb and self-polarization potentials in heterogeneous dielectric media. In particular, with simulations of ellipsoidal semiconductor quantum dots and elongated biomacromolecules being its target applications, this paper extends the so-called three-layer dielectric models for generalized Coulomb and self-polarization potential calculation from the spherical and the spheroidal geometries to the triaxial ellipsoidal geometry. Compared to the simple steplike dielectric model, these three-layer dielectric models can overcome the mathematical divergence in the self-polarization energy by employing continuous radial dielectric functions. More specifically, in this paper, the quasiharmonic three-layer dielectric model for the ellipsoidal geometry is discussed, and the explicit analytical series solutions of the corresponding electrostatic problem are obtained in terms of the ellipsoidal harmonics. Then a robust numerical procedure working for general three-layer dielectric models is developed. The key component of the numerical method is to subdivide the transition layer of the underlying three-layer model into multiple sublayers and then in each one of them approximate the select dielectric function of the transition layer by one of the quasiharmonic functional form rather than simply by a constant value as one would normally do. As a result, the numerical method has no numerical divergence.

  19. Exact Klein-Gordon equation with spatially-dependent masses for unequal scalar-vector Coulomb-like potentials

    E-print Network

    Sameer M. Ikhdair

    2009-03-23

    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 force center. The exact bound state energy eigenvalues and the corresponding wave functions of the Klein-Gordon equation for mixed scalar-vector and pure scalar Coulomb-like field potentials are obtained by means of the Nikiforov-Uvarov (NU) method. The energy spectrum is discussed for different scalar-vector potential mixing cases and also for constant mass case.

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

    E-print Network

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

    2015-01-01

    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.

  1. Phase diagram and critical properties of Yukawa bilayers

    E-print Network

    Igor Travenec; Ladislav Samaj

    2015-04-14

    We study the ground-state Wigner bilayers of pointlike particles with Yukawa pairwise interactions, confined to the surface of two parallel hard walls at dimensionless distance $\\eta$. The model involves as limiting cases the unscreened Coulomb potential and hard spheres. The phase diagram of Yukawa particles, studied numerically by Messina and L\\"owen [Phys. Rev. Lett. 91 (2003) 146101], exhibits five different staggered phases as $\\eta$ varies from 0 to intermediate values. We present a lattice summation method using the generalized Misra functions which permits us to calculate the energy per particle of the phases with a precision much higher than usual in computer simulations. This allows us to address some tiny details of the phase diagram. Going from the hexagonal phase I to phase II is shown to occur at $\\eta=0$, which resolves a longtime controversy. We find a tricritical point where Messina and L\\"owen suggested a coexistence domain of several phases which was suggested to divide the staggered rhombic phase into two separate regions. Our calculations reveal one continuous region for this rhombic phase with a very narrow connecting channel. Further we show that all second-order phase transitions are of mean-field type. We also derive the asymptotic shape of critical lines close to the Coulomb and hard-spheres limits. In and close to the hard-spheres limit, the dependence of the internal parameters of the present phases on $\\eta$ is determined exactly.

  2. Criterion for bulk behavior of a Yukawa disk

    SciTech Connect

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

    2007-03-15

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

  3. Interatomic Coulombic decay in a He dimer: Ab initio potential-energy curves and decay widths

    NASA Astrophysics Data System (ADS)

    Koloren?, P?emysl; Kryzhevoi, Nikolai V.; Sisourat, Nicolas; Cederbaum, Lorenz S.

    2010-07-01

    The energy gained by either of the two helium atoms in a helium dimer through simultaneous ionization and excitation can be efficiently transferred to the other helium atom, which then ionizes. The respective relaxation process called interatomic Coulombic decay (ICD) is the subject of the present paper. Specifically, we are interested in ICD of the lowest of the ionized excited states, namely, the He+(n=2)He states, for which we calculated the relevant potential-energy curves and the interatomic decay widths. The full-configuration interaction method was used to obtain the potential-energy curves. The decay widths were computed by utilizing the Fano ansatz, Green’s-function methods, and the Stieltjes imaging technique. The behavior of the decay widths with the interatomic distance is examined and is elucidated, whereby special emphasis is given to the asymptotically large interatomic separations. Our calculations show that the electronic ICD processes dominate over the radiative decay mechanisms over a wide range of interatomic distances. The ICD in the helium dimer has recently been measured by Havermeier [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.104.133401 104, 133401 (2010)]. The impact of nuclear dynamics on the ICD process is extremely important and is discussed by Sisourat [Nat. Phys.1745-2473doi:10.1038/nphys1685 6, 508 (2010)] based on the ab initio data computed in the present paper.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    SciTech Connect

    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

    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.

  6. Two-Electron Systems in Generalized Exponential Cosine Screened Coulomb Potentials

    NASA Astrophysics Data System (ADS)

    Rodriguez, Karina V.; Ancarani, Lorenzo Ugo; Mitnik, Dario M.

    2014-10-01

    We look at the ground state of two-electron systems placed in a dense quantum plasma environment where the three interactions between two particles of charges zi and zj placed at a distance rij can be described by exponential-cosine-screened Coulomb potential (ECSCP) V(rij) = zizjexp(- ?rij) cos(?rij) /rij where ? and ? are two positive real screening parameters related to the plasma frequency. The first calculations of the ground and first excited states of H-, He and Li+ where all three interactions between pairs of particles were represented by the same ECSCP, and with ? = ? , were recently reported [2,3]. In the present work we show results for two-electron systems for which the interactions are described by generalized ECSCP with unequal parameters. Our calculations are performed with a rather versatile Configuration Interaction approach (see and references therein), with correlated basis functions which explicitly depend on the three interparticle distances and which respect exactly all three cusp conditions.

  7. Complex-scaling of screened Coulomb potentials for resonance calculations utilizing the modified Bessel functions

    NASA Astrophysics Data System (ADS)

    Jiao, Li-Guang; Ho, Yew Kam

    2014-05-01

    The screened Coulomb potential (SCP) has been extensively used in atomic physics, nuclear physics, quantum chemistry and plasma physics. However, an accurate calculation for atomic resonances under SCP is still a challenging task for various methods. Within the complex-scaling computational scheme, we have developed a method utilizing the modified Bessel functions to calculate doubly-excited resonances in two-electron atomic systems with configuration interaction-type basis. To test the validity of our method, we have calculated S- and P-wave resonance states of the helium atom with various screening strengths, and have found good agreement with earlier calculations using different methods. Our present method can be applied to calculate high-lying resonances associated with high excitation thresholds of the He+ ion, and with high-angular-momentum states. The derivation and calculation details of our present investigation together with new results of high-angular-momentum states will be presented at the meeting. Supported by NSC of Taiwan.

  8. Dimensional phase transition in small Yukawa clusters

    SciTech Connect

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

    2010-01-15

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

  9. Laser-induced excitation and ionization of a confined hydrogen atom in an exponential-cosine-screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Lumb, Shalini; Lumb, Sonia; Prasad, Vinod

    2014-09-01

    The energy spectra of spherically confined hydrogen atom embedded in an exponential-cosine-screened Coulomb potential is worked out by using the Bernstein-polynomial method. The interaction of short laser pulses in the femtosecond range with the system is studied in detail. The effect of shape of laser pulse, confinement radius, Debye screening length as well as different laser parameters on the dynamics of the system has been explored and analyzed.

  10. Asymptotic approach to the Schrödinger equation in the presence of a screened Coulomb potential and a uniform field

    NASA Astrophysics Data System (ADS)

    Rosales-Vera, Marco

    2015-07-01

    In this paper, the Schrödinger equation in the presence of a screened Coulomb potential and a uniform field is analysed using matched asymptotic expansions. When the cup well potential has a very short range, approximate analytical expressions for the energy levels and the lifetime of the system are found. The results are compared with those described in the literature. This paper may be helpful for undergraduate and graduate students in physics as an introductory problem in the application of asymptotic matching applied to quantum mechanics.

  11. Influence of the Coulomb potential on above-threshold ionization: a quantum-orbit analysis beyond the strong-field approximation

    E-print Network

    Lai, X -Y; Schomerus, H; Faria, C Figueira de Morisson

    2015-01-01

    We perform a detailed analysis of how the interplay between the residual binding potential and a strong laser field influences above-threshold ionization (ATI), employing a semi-analytical, Coulomb-corrected strong-field approximation (SFA) in which the Coulomb potential is incorporated in the electron propagation in the continuum. We find that the Coulomb interaction lifts the degeneracy of some SFA trajectories, and we identify a set of orbits which, for high enough photoelectron energies, may be associated with rescattering. Furthermore, by performing a direct comparison with the standard SFA, we show that several features in the ATI spectra can be traced back to the influence of the Coulomb potential on different electron trajectories. These features include a decrease in the contrast, a shift towards lower energies in the interference substructure, and an overall increase in the photoelectron yield. All features encountered exhibit a very good agreement with the \\emph{ab initio} solution of the time-depe...

  12. Magnetic dipolar and quadrupolar transitions in two-electron atoms under exponential-cosine-screened Coulomb potential

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  13. Collisional and collisionless expansion of Yukawa balls

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Goree, John A.

    2013-12-01

    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.

  14. Effective Coulomb logarithm for one component plasma

    SciTech Connect

    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

    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.

  15. Dirac equation for the harmonic scalar and vector potentials and linear plus coulomb-like tensor potential; the SUSY approach

    SciTech Connect

    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

    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.

  16. An example of double confluent Heun equation: Schroedinger equation with supersingular plus Coulomb potential

    E-print Network

    Julio Abad; Javier Sesma

    2009-07-25

    A recently proposed algorithm to obtain global solutions of the double confluent Heun equation is applied to solve the quantum mechanical problem of finding the energies and wave functions of a particle bound in a potential sum of a repulsive supersingular term, Ar(-4), plus an attractive Coulombian one, -Zr(-1). The existence of exact algebraic solutions for certain values of A is discussed.

  17. Yukawa Textures and Anomalies

    E-print Network

    Pierre Binetruy; Pierre Ramond

    1994-12-29

    We augment the Minimal Supersymmetric Standard Model with a gauged family-dependent $U(1)$ to reproduce Yukawa textures compatible with experiment. In the simplest model with one extra chiral electroweak singlet field, acceptable textures require this $U(1)$ to be anomalous. The cancellation of its anomalies by a generic Green-Schwarz mechanism requires $\\sin^2\\theta_w=3/8$ at the string scale, suggesting a superstring origin for the standard model.

  18. Direct demonstration of the completeness of the eigenstates of the Schrodinger equation with local and non-local potentials bearing a Coulomb tail

    E-print Network

    Nicolas Michel

    2008-02-12

    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.

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

    SciTech Connect

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

    2013-06-15

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

  20. Prediction of collective diffusion coefficient of bovine serum albumin in aqueous electrolyte solution with hard-core two-Yukawa potential.

    PubMed

    Yu, Yang-Xin; Tian, Ai-Wei; Gao, Guang-Hua

    2005-06-21

    A new method to predict concentration dependence of collective diffusion coefficient of bovine serum albumin (BSA) in aqueous electrolyte solution is developed based on the generalized Stokes-Einstein equation which relates the diffusion coefficient to the osmotic pressure. The concentration dependence of osmotic pressure is evaluated using the solution of the mean spherical approximation for the two-Yukawa model fluid. The two empirical correlations of sedimentation coefficient are tested in this work. One is for a disordered suspension of hard spheres, and another is for an ordered suspension of hard spheres. The concentration dependence of the collective diffusion coefficient of BSA under different solution conditions, such as pH and ionic strength is predicted. From the comparison between the predicted and experimental values we found that the sedimentation coefficient for the disordered suspension of hard spheres is more suitable for the prediction of the collective diffusion coefficients of charged BSA in aqueous electrolyte solution. The theoretical predictions from the hard-core two-Yukawa model coupled with the sedimentation coefficient for a suspension of hard spheres are in good agreement with available experimental data, while the hard sphere model is unable to describe the behavior of diffusion due to its neglect of the double-layer repulsive charge-charge interaction between BSA molecules. PMID:15962025

  1. Exploiting duality in a toy model of QCD at non-zero temperature and chemical potential the massive Thirring model, sine-Gordon model and Coulomb gases

    E-print Network

    Steer, D A; Rivers, R J; Evans, T S

    2000-01-01

    We focus on the massive Thirring model in 1+1 dimensions at finite temperature and non-zero chemical potential, and comment on some parallels between this model and QCD. In QCD, calculations of physical quantities such as transport coefficients are extremely difficult. In the massive Thirring model, similar calculations are greatly simplified by exploiting the duality which exists with the sine-Gordon model and its relation, at high temperature, to the exactly solvable classical Coulomb gas on the line.

  2. A self-consistent, microenvironment modulated screened coulomb potential approximation to calculate pH-dependent electrostatic effects in proteins.

    PubMed Central

    Mehler, E L; Guarnieri, F

    1999-01-01

    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

  3. Dynamic of rescattering-electron wave packets in strong and short-wavelength laser fields: Roles of Coulomb potential and excited states

    SciTech Connect

    Chen Yanjun [Beijing Computational Science Research Center, Beijing (China)

    2011-10-15

    We investigate the high-order harmonic generation of atoms and molecules exposed in strong and short-wavelength (shorter than 800 nm) laser fields. Our simulations show that the electronic rescattering trajectory depends strongly on the property of the Coulomb potential. Using numerical schemes, we identify the important role of excited states in the emission times of harmonics from molecules. We propose a model, which considers the initial position when electrons tunnel out from the potential, to explain the electronic response in intense and relatively high-frequency laser fields.

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

    PubMed Central

    Butler, James P.; Loring, Stephen H.

    2010-01-01

    Background During normal breathing, the mesothelial surfaces of the lung and chest wall slide relative to one another. Experimentally, the shear stresses induced by such reciprocal sliding motion are very small, consistent with hydrodynamic lubrication, and relatively insensitive to sliding velocity, similar to Coulomb-type dry friction. Here we explore the possibility that shear-induced deformation of surface roughness in such tissues could result in bidirectional load supporting behavior, in the absence of solid-solid contact, with shear stresses relatively insensitive to sliding velocity. Method of approach We consider a lubrication problem with elastic blocks (including the rigid limit) over a planar surface sliding with velocity U , where the normal force is fixed (hence the channel thickness is a dependent variable). One block shape is continuous piecewise linear (V block), the other continuous piecewise smoothly quadratic (Q block). The undeformed elastic blocks are spatially symmetric; their elastic deformation is simplified by taking it to be affine, with the degree of shape asymmetry linearly increasing with shear stress. Results We find that the V block exhibits nonzero Coulomb-type starting friction in both the rigid and elastic case, and that the smooth Q block exhibits approximate Coulomb friction in the sense that the rate of change of shear force with U is unbounded as U ? 0 ; shear force ?U1/ 2 in the rigid asymmetric case and ?U1/ 3 in the (symmetric when undeformed) elastic case. Shear-induced deformation of the elastic blocks results in load supporting behavior for both directions of sliding. Conclusions This mechanism could explain load-supporting behavior of deformable surfaces that are symmetrical when undeformed, and may be the source of the weak velocity dependence of friction seen in the sliding of lubricated, but rough, surfaces of elastic media such as the visceral and parietal pleural surfaces of the lung and chest wall. PMID:20890380

  5. Dielectric-dependent screened Hartree-Fock exchange potential and Slater-formula with Coulomb-hole interaction for energy band structure calculations.

    PubMed

    Shimazaki, Tomomi; Nakajima, Takahito

    2014-09-21

    We previously reported a screened Hartree-Fock (HF) exchange potential for energy band structure calculations [T. Shimazaki and Y. Asai, J. Chem. Phys. 130, 164702 (2009); T. Shimazaki and Y. Asai, J. Chem. Phys. 132, 224105 (2010)]. In this paper, we discuss the Coulomb-hole (COH) interaction and screened Slater-formula and determine the energy band diagrams of several semiconductors, such as diamond, silicon, AlAs, AlP, GaAs, GaP, and InP, based on the screened HF exchange potential and Slater-formula with COH interaction, to demonstrate the adequacy of those theoretical concepts. The screened HF exchange potential and Slater-formula are derived from a simplified dielectric function and, therefore, include the dielectric constant in their expressions. We also present a self-consistent calculation technique to automatically determine the dielectric constant, which is incorporated into each self-consistent field step. PMID:25240347

  6. Yukawa-Field Approximation of Electrostatic Free Energy and Dielectric Boundary Force

    PubMed Central

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

    2013-01-01

    A Yukawa-field approximation of the electrostatic free energy of a molecular solvation system with an implicit or continuum solvent is constructed. It is argued through the analysis of model molecular systems with spherically symmetric geometries that such an approximation is rational. The construction extends non-trivially that of the Coulomb-field approximation which serves as a basis of the widely used generalized Born model of molecular electrostatics. The electrostatic free energy determines the dielectric boundary force that in turn influences crucially the molecular conformation, stability, and dynamics. An explicit formula of such forces with the Yukawa-field approximation is obtained using local coordinates and shape differentiation. PMID:23853423

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

    DOE PAGESBeta

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    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.

  8. Longitudinal viscosity of two-dimensional Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Feng, Yan; Goree, J.; Liu, Bin

    2013-01-01

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

  9. Longitudinal viscosity of two-dimensional Yukawa liquids.

    PubMed

    Feng, Yan; Goree, J; Liu, Bin

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  11. The effect of the Coulomb potential on subcycle interference of electron wave packets in atomic ionization by two-colour laser pulses

    NASA Astrophysics Data System (ADS)

    Arbó, Diego G.

    2014-10-01

    We analyse the effect of the long-range potential of the ionic core on the photoelectron emission in atomic ionization by a linearly polarized subcycle sculpted laser pulse of two-colour components, where one frequency doubles the other. The total ionization yield consists mostly of direct electrons, which can be characterized by both intracycle and intercycle interferences. Using a semiclassical model based on the Simple Man’s Model, we can derive an analytical expression for the intracycle interference due to the coherent superposition of different electron trajectories released in the same sculpted optical cycle. In turn, the intercycle interference is the consequence of the superposition of multiple trajectories released at different cycles and is accounted for by the energy conservation in the photon absorption process. We show that a semiclassical description in terms of a diffraction process at a time grating for two-colour laser pulses remains qualitatively unchanged beyond the strong field approximation. In particular, the Coulomb potential shifts the intracycle interference modulations towards the threshold, whereas the intercycle interference pattern remains invariant. The present study completes a recent work by Xie et al (2013 New J. Phys. 15 043050), where the influence of the Coulomb field on atomic ionization by sculpted two-colour laser fields is probed but in which path interferences are not considered. Furthermore, this article gives theoretical support to recent experiments with He and Ar where the sub-cycle interference structures originating from trajectories launched within a time interval of less than one femtosecond were observed (Xie X et al 2012 Phys. Rev. Lett. 108 193004).

  12. Yukawa Couplings on Quintic Threefolds

    E-print Network

    Ron Donagi; Rene Reinbacher; Shing-Tung Yau

    2011-11-02

    We compute the particle spectrum and some of the Yukawa couplings for a family of heterotic compactifications on quintic threefolds X involving bundles that are deformations of TX+O_X. These are then related to the compactifications with torsion found recently by Li and Yau. We compute the spectrum and the Yukawa couplings for generic bundles on generic quintics, as well as for certain stable non-generic bundles on the special Dwork quintics. In all our computations we keep the dependence on the vector bundle moduli explicit. We also show that on any smooth quintic there exists a deformation of the bundle TX+O_X whose Kodaira-Spencer class obeys the Li-Yau non-degeneracy conditions and admits a non-vanishing triple pairing.

  13. Multimeson Yukawa interactions at criticality

    NASA Astrophysics Data System (ADS)

    Vacca, Gian Paolo; Zambelli, Luca

    2015-06-01

    The critical behavior of a relativistic Z2 -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 multimeson 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 multicritical models in less than three dimensions, both at infinite and finite numbers 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.

  14. The Spinless Relativistic Yukawa Problem

    E-print Network

    Wolfgang Lucha; Franz F. Schöberl

    2014-10-20

    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 Schr\\"odinger equation towards 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  16. Invariants in the Yukawa system's thermodynamic phase diagram

    E-print Network

    Veldhorst, Arno A; Dyre, Jeppe C

    2015-01-01

    This paper shows that several known properties of the Yukawa system can be derived from the isomorph theory, which applies to any system that has strong correlations between its virial and potential-energy equilibrium fluctuations. Such "Roskilde-simple" systems have a simplified thermodynamic phase diagram deriving from the fact that they have curves (isomorphs) along which structure and dynamics in reduced units are invariant to a good approximation. We show that the Yukawa system has strong virial potential-energy correlations and identify its isomorphs by two different methods. One method, the so-called direct isomorph check, identifies isomorphs numerically from jumps of relatively small density changes (here 10%). The second method identifies isomorphs analytically from the pair potential. The curves obtained by the two methods are close to each other; these curves are confirmed to be isomorphs by demonstrating the invariance of the radial distribution function, the static structure factor, the mean-squ...

  17. Electronic structure of antifluorite Cu{sub 2}X (X = S, Se, Te) within the modified Becke-Johnson potential plus an on-site Coulomb U

    SciTech Connect

    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

    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.

  18. Coulomb double helical structure

    NASA Astrophysics Data System (ADS)

    Kamimura, Tetsuo; Ishihara, Osamu

    2012-01-01

    Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

  19. An exchange-Coulomb model potential energy surface for the Ne-CO interaction. II. Molecular beam scattering and bulk gas phenomena in Ne-CO mixtures.

    PubMed

    Dham, Ashok K; McBane, George C; McCourt, Frederick R W; Meath, William J

    2010-01-14

    Four potential energy surfaces are of current interest for the Ne-CO interaction. Two are high-level fully ab initio surfaces obtained a decade ago using symmetry-adapted perturbation theory and supermolecule coupled-cluster methods. The other two are very recent exchange-Coulomb (XC) model potential energy surfaces constructed by using ab initio Heitler-London interaction energies and literature long range dispersion and induction energies, followed by the determination of a small number of adjustable parameters to reproduce a selected subset of pure rotational transition frequencies for the (20)Ne-(12)C(16)O van der Waals cluster. Testing of the four potential energy surfaces against a wide range of available experimental microwave, millimeter-wave, and mid-infrared Ne-CO transition frequencies indicated that the XC potential energy surfaces gave results that were generally far superior to the earlier fully ab initio surfaces. In this paper, two XC model surfaces and the two fully ab initio surfaces are tested for their abilities to reproduce experiment for a wide range of nonspectroscopic Ne-CO gas mixture properties. The properties considered here are relative integral cross sections and the angle dependence of rotational state-to-state differential cross sections, rotational relaxation rate constants for CO(v=2) in Ne-CO mixtures at T=296 K, pressure broadening of two pure rotational lines and of the rovibrational lines in the CO fundamental and first overtone transitions at 300 K, and the temperature and, where appropriate, mole fraction dependencies of the interaction second virial coefficient, the binary diffusion coefficient, the interaction viscosity, the mixture shear viscosity and thermal conductivity coefficients, and the thermal diffusion factor. The XC model potential energy surfaces give results that lie within or very nearly within the experimental uncertainties for all properties considered, while the coupled-cluster ab initio surface gives results that agree similarly well for all but one of the properties considered. When the present comparisons are combined with the ability to give accurate spectroscopic transition frequencies for the Ne-CO van der Waals complex, only the XC potential energy surfaces give results that agree well with all extant experimental data for the Ne-CO interaction. PMID:20095675

  20. Entropic Corrections to Coulomb's Law

    E-print Network

    S. H. Hendi; A. Sheykhi

    2011-10-17

    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 $\\phi$. Our study further supports the unification of gravity and electromagnetic interactions based on the holographic principle.

  1. Two-dimensional Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Gonzalez-Melchor, Minerva; Mendez, Arlette; Alejandre, Jose

    2015-03-01

    When the movement of particles is performed predominantly in two dimensions, the systems can be considered at a good extent as two-dimensional. For instance the lipids in a bilayer, micrometric particles in a quasi-two-dimensional colloidal suspension, colloids in a monolayer deposited on the air-water interface, and DNA complexes trapped at the water surface can be described at a first approach as bidimensional fluids. These systems are important for many applications in surface and colloidal science. In simulations where the explicit interface between liquid and vapor is present, the line tension can be directly computed. In this work we present molecular dynamics results obtained for the liquid/vapor coexistence curve of 2D Yukawa fluids and for the line tension. A comparison with the three-dimensional case is also presented.

  2. Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the $^{12}$C+$^{208}$Pb System at Near-Coulomb-Barrier Energies by using a Folding Potential

    E-print Network

    W. Y. So; T. Udagawa; S. W. Hong; B. T. Kim

    2008-01-15

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

  3. Extended Optical Model Analyses of Elastic Scattering and Fusion Cross Section Data for the 7Li+208Pb System at Near-Coulomb-Barrier Energies using the Folding Potential

    E-print Network

    W. Y. So; T. Udagawa; K. S. Kim; S. W. Hong; B. T. Kim

    2007-06-05

    Simultaneous $\\chi^{2}$ analyses previously made for elastic scattering and fusion cross section data for the $^{6}$Li+$^{208}$Pb system is extended to the $^{7}$Li+$^{208}$Pb system at near-Coulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the $\\chi^{2}$ analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the Continuum Discretized Coupled Channel (CDCC) calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the $^7$Li+$^{208}$Pb system with the analysis previously made for the $^{6}$Li+$^{208}$Pb system.

  4. Molecular dynamics simulations of thermal conductivity in 2D complex Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Shahzad, Aamir; Sultana, Mariam; Aslam, Arffa; He, Mao-Gang

    2014-06-01

    The thermal conductivity in strongly coupled complex dusty plasma liquids (SCCDPLs) has been investigated through an improved homogenous nonequilibrium molecular simulation (HNEMS) method, for the first time. The HNEMS method has been employed for two-dimensional (2D) Yukawa systems in a canonical ensemble. The thermal conductivities with suitable normalizations (plasma and Einstein frequencies), in the value of low force field strength, have been computed for a wide range of plasma state points of Coulomb coupling (?) and screening strength (?). The new simulation results are found to obey the simple analytical temperature scaling law. The present HNEMS results are in generally with parts of earlier HNEMS, equilibrium molecular dynamics (EMD) and experimental data in the literature for the 2D and there-dimensional (3D) SCCDPLs. It is shown that the HNEMS method can be used to estimate the thermal conductivity very effectively and to understand the fundamental behaviours in 2D Yukawa systems.

  5. Numerical approach to Coulomb gauge QCD

    SciTech Connect

    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

    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.

  6. Coulomb Interaction in Semiconductor Lasers

    Microsoft Academic Search

    W. D. Johnston

    1972-01-01

    Recent evidence suggests that the excitation density in semiconductor lasers exceeds the realm where exciton-based descriptions of the optical-gain process are valid. A treatment is presented based on the random-phase approximation from electron-gas theory in which the effects of the long-wavelength components of the Coulomb potential are included. In addition to the usual exchange term, a term derivable from electron-plasmon

  7. Indirect Handle on the Down-Quark Yukawa Coupling

    NASA Astrophysics Data System (ADS)

    Goertz, Florian

    2014-12-01

    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.

  8. Noncommutative Coulombic monopole

    SciTech Connect

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

    2005-10-15

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

  9. Solid-to-solid isostructural transition in the hard sphere/attractive Yukawa system

    NASA Astrophysics Data System (ADS)

    Rascón, C.; Mederos, L.; Navascués, G.

    1995-12-01

    A thermodynamically consistent density functional-perturbation theory is used to study the isostructural solid-to-solid transition which takes place in the hard sphere/attractive Yukawa system when the Yukawa tail is sufficiently short ranged. A comparison with results for the square well potential allows us to study the effect of the attractive potential form on the solid-solid transition. Reasonable agreement with simulations is found for the main transition properties as well as for the phase diagram evolution with the range of the attractive potential.

  10. Diffusion in Coulomb crystals.

    PubMed

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

    2011-07-01

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

  11. Diffusion in Coulomb crystals

    SciTech Connect

    Hughto, J.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K. [Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47405 (United States); University Information Technology Services, Indiana University, Bloomington, Indiana 47408 (United States)

    2011-07-15

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

  12. Resolutions of the Coulomb Operator

    NASA Astrophysics Data System (ADS)

    Gill, Peter

    2007-03-01

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

  13. Deviation of Yukawa Coupling in Gauge-Higgs Unification

    E-print Network

    Yuki Adachi; Nobuhito Maru

    2015-01-26

    We study the deviation of yukawa coupling in the gauge-Higgs unification scenario from the Standard Model one. Taking into account the brane mass terms necessary for generating the flavor mixing and removing the exotic massless fermions, we derive an analytic formula determining the KK mass spectrum and yukawa coupling. Applying the obtained results to the tau and bottom yukawa couplings, we numerically calculate the ratio of the yukawa couplings in the gauge-Higgs unification and in the Standard Model.

  14. Invariants in the Yukawa system's thermodynamic phase diagram

    E-print Network

    Arno A. Veldhorst; Thomas B. Schrøder; Jeppe C. Dyre

    2015-06-30

    This paper shows that several known properties of the Yukawa system can be derived from the isomorph theory, which applies to any system that has strong correlations between its virial and potential-energy equilibrium fluctuations. Such "Roskilde-simple" systems have a simplified thermodynamic phase diagram deriving from the fact that they have curves (isomorphs) along which structure and dynamics in reduced units are invariant to a good approximation. We show that the Yukawa system has strong virial potential-energy correlations and identify its isomorphs by two different methods. One method, the so-called direct isomorph check, identifies isomorphs numerically from jumps of relatively small density changes (here 10%). The second method identifies isomorphs analytically from the pair potential. The curves obtained by the two methods are close to each other; these curves are confirmed to be isomorphs by demonstrating the invariance of the radial distribution function, the static structure factor, the mean-square displacement as a function of time, and the incoherent intermediate scattering function. Since the melting line is predicted to be an isomorph, the theory provides a derivation of a known approximate analytical expression for this line in the temperature-density phase diagram. The paper's results give the first demonstration that the isomorph theory can be applied to systems like dense colloidal suspensions and strongly coupled dusty plasmas.

  15. Sparticle spectroscopy and neutralino dark matter for Yukawa and gauge-Yukawa unified models

    NASA Astrophysics Data System (ADS)

    Khalid, Rizwan

    2011-12-01

    This dissertation examines third generation (t-b-tau) Yukawa and gauge-Yukawa coupling unification in supersymmetric SU(4) c x SU(2)L x SU(2)RGUT. We assume a framework of gravity mediated supersymmetry breaking so the 4-2-2 structure dictates the form of the soft supersymmetry breaking parameters at M GUT. We study the spectroscopic implications of Yukawa and gauge-Yukawa unification that may be testable at the Large Hadron Collider. We also discuss the prospects of a Yukawa or gauge-Yukawa unified 4-2-2 model yielding solutions that are observable in direct and indirect dark matter detection experiments. We demonstrate the importance of finite corrections to the bottom quark Yukawa coupling for the question of Yukawa unification. We also show that Yukawa coupling unification in 4-2-2 is compatible with neutralino dark matter. If we restrict ourselves to the case of same sign gaugino soft mass terms, the resulting Yukawa unified model predicts a very characteristic sparticle spectrum with gluino as the next to lightest supersymmetric particle (NLSP) and heavy (multi-TeV) squarks and sleptons. By considering gaugino mass soft terms with a relative sign, we are able to realize Yukawa coupling unification with the universal soft supersymmetry breaking scalar mass parameter m 0 ? 400 GeV as opposed to m0 ? 8 TeV for same sign gauginos. We have demonstrated the existence of a variety of coannihilation scenarios involving gluino, wino and stau, in addition to the light Higgs, Z and A resonance solutions and the bino-Higgsino mixed dark matter solution. The 4-2-2 model with opposite sign gauginos also has relatively 'light' (m0 ˜ 43 GeV) neutralinos compatible with Yukawa unification and neutralino dark matter. We may also satisfy the Delta (g-2)mu constraint along with all the other experimental bounds for the case of opposite sign gauginos which is not possible for same sign gauginos. We show that gauge-Yukawa coupling unification is sensitive to the top quark mass mt. Varying mt within 1sigma of its current central value yields a variety of gauge-Yukawa unification as well as WMAP compatible neutralino dark matter solutions. They include mixed bino-Higgsino dark matter, stau and gluino coannihilation scenarios, and the A-resonance solution. We investigate mixed bino-Higgsino dark matter as the best scenario in the MSSM to be observed at direct and indirect dark matter search experiments. If the observed relic density is saturated by the bino-Higgsino dark matter, it fixes the amount of allowable bino-Higgsino mixing and provides predictions for other observables which can be tested at the Large Hadron Collider (LHC). We study the correlation between the cross sections and the branching ratio of Bs? mu + mu -. Finally, we show the bino-Higgsino mixing solutions that are compatible with Yukawa and gauge-Yukawa unification and may soon be detected at direct and indirect dark matter surveys.

  16. Electron Radiative Transitions in a Coulomb Field

    Microsoft Academic Search

    W. J. Karzas; R. Latter

    1961-01-01

    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

  17. Coulomb effects in quasielastic electron scattering

    SciTech Connect

    Onley, D.S.

    1991-01-01

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

  18. Coulomb effects in quasielastic electron scattering

    SciTech Connect

    Onley, D.S.

    1991-12-31

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

  19. THE "MOHR-COULOMB" ERROR

    NSDL National Science Digital Library

    Schofield, Andrew N.

    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.

  20. Energy dependence of the optical potentials for the 9Be +208Pb and 9Be +209Bi systems at near-Coulomb-barrier energies

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.; Yu, N.; Zhang, H. Q.; Gomes, P. R. S.; Jia, H. M.; Lubian, J.; Lin, C. J.

    2015-04-01

    We analyze the energy dependence of the interacting optical potential, at near barrier energies, for two systems involving the weakly bound projectile 9Be and the heavy 208Pb and 209Bi targets, by the simultaneous fit of elastic scattering angular distributions and fusion excitation functions. The approach used consists of dividing the optical potential into two parts. A short-range potential VF+i WF that is responsible for fusion, and a superficial potential VDR+i WDR for direct reactions. It is found, for both systems studied, that the fusion imaginary potential WF presents the usual threshold anomaly (TA) observed in tightly bound systems, whereas the direct reaction imaginary potential WDR shows a breakup threshold anomaly (BTA) behavior. Both potentials satisfy the dispersion relation. The direct reaction polarization potential predominates over the fusion potential and so a net overall behavior is found to follow the BTA phenomenon.

  1. Realistic Yukawa structures from orientifold compactifications

    Microsoft Academic Search

    Mirjam Cvetic; James Halverson; Robert Richter

    2009-01-01

    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

  2. The box diagram in Yukawa theory

    E-print Network

    Bernard L. G. Bakker; Jorn K. Boomsma; Chueng-Ryong Ji

    2006-10-30

    We present a light-front calculation of the box diagram in Yukawa theory. The covariant box diagram is finite for the case of spin-1/2 constituents exchanging spin-0 particles. In light-front dynamics, however, individual time-ordered diagrams are divergent. We analyze the corresponding light-front singularities and show the equivalence between the light-front and covariant results by taming the singularities.

  3. Yukawa Textures From Heterotic Stability Walls

    E-print Network

    Lara B. Anderson; James Gray; Burt Ovrut

    2010-01-13

    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.

  4. Modeling Fine-Particle (Dusty) Plasmas and Charge-Stabilized Colloidal Suspensions as Inhomogeneous Yukawa Systems

    NASA Astrophysics Data System (ADS)

    Totsuji, Hiroo

    2015-06-01

    As a basis for the structure and correlation analyses of fine-particle (dusty) plasmas and colloidal suspensions, the thermodynamic treatment of mixtures of macro- and microscopic charged particles is revisited and extended to finite systems with weak inhomogeneity within the adiabatic response of microscopic particles. The effective potential for macroscopic particles is shown to be composed of mutual Yukawa repulsions and a confining (attractive) Yukawa potential from their “shadow” (the average charge density of macroscopic particles with an inverted sign). Clarified is the relationship between two different approaches hitherto taken, the assumption of a parabolic one-body potential or of the flat one-body potential of finite extension. The enhanced charge neutrality due to the existence of macroscopic particles seems to suggest that the latter is closer to reality.

  5. Holographic Coulomb branch vevs

    NASA Astrophysics Data System (ADS)

    Skenderis, Kostas; Taylor, Marika

    2006-08-01

    We compute holographically the vevs of all chiral primary operators for supergravity solutions corresponding to the Coulomb branch of Script N = 4 SYM and find exact agreement with the corresponding field theory computation. Using the dictionary between 10d geometries and field theory developed to extract these vevs, we propose a gravity dual of a half supersymmetric deformation of Script N = 4 SYM (on Mink4) by certain irrelevant operators.

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

    NASA Astrophysics Data System (ADS)

    Lassettre, Edwin N.

    1985-08-01

    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.

  7. Coulomb bound states of strongly interacting photons

    E-print Network

    Maghrebi, M F; Bienias, P; Choi, S; Martin, I; Firstenberg, O; Lukin, M D; Büchler, H P; Gorshkov, A V

    2015-01-01

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

  8. Coulomb bound states of strongly interacting photons

    E-print Network

    M. F. Maghrebi; M. J. Gullans; P. Bienias; S. Choi; I. Martin; O. Firstenberg; M. D. Lukin; H. P. Büchler; A. V. Gorshkov

    2015-05-14

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.

  9. Associated t anti-t H production at a VLHC measuring the top-quark Yukawa coupling

    E-print Network

    Belyaev, A; Reina, L

    2001-01-01

    Future hadron colliders will have the potential to measure some of the most relevant Higgs boson couplings with high precision. In this paper we investigate the potential of a Very Large Hadron Collider (VLHC) to measure the top-quark Yukawa coupling.

  10. Associated t anti-t H production at a VLHC: measuring the top-quark Yukawa coupling

    E-print Network

    A. Belyaev; F. Maltoni; L. Reina

    2001-11-16

    Future hadron colliders will have the potential to measure some of the most relevant Higgs boson couplings with high precision. In this paper we investigate the potential of a Very Large Hadron Collider (VLHC) to measure the top-quark Yukawa coupling.

  11. The Coulomb gap and low energy statistics for Coulomb glasses

    Microsoft Academic Search

    Andreas Glatz; Valerii M. Vinokur; Joakim Bergli; Martin Kirkengen; Yuri M. Galperin

    2008-01-01

    We study the statistics of local energy minima in the configuration space of two-dimensional lattice Coulomb glasses with site disorder and the behavior of the Coulomb gap depending on the strength of random site energies. At intermediate disorder, i.e., when the typical strength of the disorder is of the same order as the nearest-neighbor Coulomb energy, the high energy tail

  12. Statics and dynamics of Yukawa cluster crystals on ordered substrates.

    PubMed

    Reichhardt, C; Olson Reichhardt, C J

    2012-05-01

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

  13. Soft mean spherical approximation for dusty plasma liquids: One-component Yukawa systems with plasma shielding

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  14. Exclusive Window onto Higgs Yukawa Couplings

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  16. Supersymmetric dark matter and Yukawa unification

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Utpal; Corsetti, Achille; Nath, Pran

    2002-08-01

    An analysis of supersymmetric dark matter under the Yukawa unification constraint is given. The analysis utilizes the recently discovered region of the parameter space of models with gaugino mass nonuniversalities where large negative supersymmetric corrections to the b quark mass appear to allow b-? unification for a positive ? sign consistent with the b-->s+? and g?-2 constraints. In the present analysis we use the revised theoretical determination of aSM? [a?=(g?-2)/2] in computing the difference aexpt?-aSM? which takes into account a reevaluation of the light by light contribution, which has a positive sign. The analysis shows that the region of parameter space with nonuniversalities of the gaugino masses that allows for unification of Yukawa couplings also contains regions that allow the satisfaction of the relic density constraint. Specifically, we find that the lightest neutralino mass consistent with the relic density constraint, b? unification for SU(5), and b-t-? unification for SO(10), in addition to other constraints, lies in the region below 80 GeV. An analysis of the maximum and the minimum neutralino-proton scalar cross sections for the allowed parameter space, including the effect of a new determination of the pion-nucleon sigma term, is also given. It is found that the full parameter space for this class of models can be explored in the next generation of proposed dark matter detectors.

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

    SciTech Connect

    Juste, A.

    2005-12-01

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

  18. Renormalization group invariant of lepton Yukawa couplings

    NASA Astrophysics Data System (ADS)

    Tsuyuki, Takanao

    2015-04-01

    By using quark Yukawa matrices only, we can construct renormalization invariants that are exact at the one-loop level in the standard model. One of them, Iq, is accidentally consistent with unity, even though quark masses are strongly hierarchical. We calculate a lepton version of the invariant Il for Dirac and Majorana neutrino cases and find that Il can also be close to unity. For the Dirac neutrino and inverted hierarchy case, if the lightest neutrino mass is 3.0 meV to 8.8 meV, an equality Iq=Il can be satisfied. These invariants are not changed even if new particles couple to the standard model particles, as long as those couplings are generation independent.

  19. Renormalization group invariant of lepton Yukawa couplings

    E-print Network

    Takanao Tsuyuki

    2015-04-20

    By using quark Yukawa matrices only, we can construct renormalization invariants that are exact at the one-loop level in the standard model. One of them $I^q$ is accidentally consistent with unity, even though quark masses are strongly hierarchical. We calculate a lepton version of the invariant $I^l$ for Dirac and Majorana neutrino cases and find that $I^l$ can also be close to unity. For the Dirac neutrino and inverted hierarchy case, if the lightest neutrino mass is 3.0 meV to 8.8 meV, an equality $I^q=I^l$ can be satisfied. These invariants are not changed even if new particles couple to the standard model particles, as long as those couplings are generation independent.

  20. Renormalization group invariant of lepton Yukawa couplings

    E-print Network

    Tsuyuki, Takanao

    2015-01-01

    By using quark Yukawa matrices only, we can construct renormalization invariants that are exact at the one-loop level in the standard model. One of them $I^q$ is accidentally consistent with unity, even though quark masses are strongly hierarchical. We calculate a lepton version of the invariant $I^l$ for Dirac and Majorana neutrino cases and find that $I^l$ can be also close to unity. For the Dirac neutrino case, if we assume $I^q=I^l$, we can deduce that the hierarchy of neutrino masses is inverted, and the lightest neutrino mass is 3.0 meV to 8.8 meV.

  1. Realistic Yukawa Structures from Orientifold Compactifications

    E-print Network

    Mirjam Cveti?; James Halverson; Robert Richter

    2009-09-24

    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.

  2. Realistic Yukawa structures from orientifold compactifications

    E-print Network

    Cveti?, Mirjam; Richter, Robert

    2009-01-01

    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.

  3. Coulomb crystallization of highly charged ions.

    PubMed

    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

    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

  4. Critical endpoint and analytical phase diagram of attractive hard-core Yukawa spheres.

    PubMed

    Tuinier, Remco; Fleer, Gerard J

    2006-10-19

    We analytically calculate the gas-liquid critical endpoint (cep) for hard spheres with a Yukawa attraction. This cep is a boundary condition for the existence of a liquid. We use an analytical Helmholtz energy expression for the attractive Yukawa (hard) spheres based on the first-order mean spherical approximation to the attractive Yukawa potential by Tang and Lu (J. Chem. Phys. 1993, 99, 9828). This theory and our analytical simplification of it predict the gas-liquid and fluid-solid phase behavior, as found from computer simulations, very accurately as long as the range 1/kappa of attraction is not too short. We find that the cep is situated at kappasigma approximately 6 and at a contact potential around 2 kT. It follows that a liquid state is only possible when the attraction range is longer than (1/6) of the particle diameter sigma, and the attraction strength is smaller than 2 kT. The liquid region does not span more than 0.6 kT in strength, and there is also a relatively narrow window for the attraction range. PMID:17034241

  5. Ion sphere model for Yukawa systems (dusty plasmas)

    E-print Network

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

    2014-12-12

    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.

  6. Mapping Dirac quasiparticles near a single Coulomb impurity on graphene

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  7. Regularization of the Coulomb scattering problem

    SciTech Connect

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

    2004-11-01

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

  8. Casimir forces in a Plasma: Possible Connections to Yukawa Potentials

    E-print Network

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

    2014-09-03

    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.

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

    SciTech Connect

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

    2010-04-01

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

  10. Three-body Coulomb systems using generalized angular-momentum S states

    NASA Technical Reports Server (NTRS)

    Whitten, R. C.; Sims, J. S.

    1974-01-01

    An expansion of the three-body Coulomb potential in generalized angular-momentum eigenfunctions developed earlier by one of the authors is used to compute energy eigenvalues and eigenfunctions of bound S states of three-body Coulomb systems. The results for He, H(-), e(-)e(+)e(-), and pmu(-)p are compared with the results of other computational approaches.

  11. Heavy ion reactions around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Zhang, HuanQiao; Lin, ChengJian; Jia, HuiMing; Zhang, ChunLei; Zhang, GaoLong; Yang, Feng; Liu, ZuHua; An, GuangPeng; Wu, ZhenDong; Xu, XinXing; Jia, Fei

    2011-08-01

    The angular distributions of fission fragments for the 32S+184W reaction near Coulomb barrier energies are measured. The experimental fission excitation function is obtained. The measured fission cross sections are decomposed into fusion-fission, quasi-fission and fast fission contributions by the dinuclear system (DNS) model. The hindrance to completing fusion both at small and large collision energies is explained. The fusion excitation functions of 32S+90,96Zr in an energy range from above to below the Coulomb barrier are measured and analyzed within a semi-classical model. The obvious effect of positive Q-value multi-neutron transfers on the sub-barrier fusion enhancement is observed in the 32S+96Zr system. In addition, the excitation functions of quasi-elastic scattering at a backward angle have been measured with high precision for the systems of 16O + 208Pb, 196Pt, 184W, and 154,152Sm at energies well below the Coulomb barrier. Considering the deformed coupling effects, the extracted diffuseness parameters are close to the values extracted from the systematic analysis of elastic and inelastic scattering data. The elastic scattering angular distribution of 17F+12C at 60 MeV is measured and calculated by using the continuum-discretized coupled-channels (CDCC) approach. It is found that the diffuseness parameter of the real part of core-target potential has to be increased by 20% to reproduce the experimental result, which corresponds to an increment of potential depth at the surface region. The breakup cross section and the coupling between breakup and elastic scattering are small.

  12. Studies of Coulomb Gauge QCD

    SciTech Connect

    Adam P. Szczepaniak; Eric S. Swanson

    2000-12-12

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

  13. Turbine blade cooling using Coulomb repulsion

    NASA Astrophysics Data System (ADS)

    Breidenthal, Robert; Colannino, Joseph; Dees, John; Goodson, David; Krichtafovitch, Igor; Prevo, Tracy

    2012-11-01

    Video photography and thermocouples reveal the effect of an electric field on the flow around a stationary, idealized turbine blade downstream of a combustor. The hot products of combustion naturally include positive ions. When the blade is an electrode and elevated to a positive potential, it tends to attract the free electrons and repel the positive ions. Due to their lower mass, the light electrons are rapidly swept toward the blade, while the positive ions are repelled. As they collide with the neutrals in the hot gas, the positive ions transfer their momentum so that a Coulomb body force is exerted on the hot gas. Cool, compressed air is injected out of the stationary blade near its leading edge to form a layer of film cooling. In contrast to the hot combustion products, the cool air is not ionized. At the interface between the hot gas and the cool air, the Coulomb repulsion force acts on the former but not the latter, analogous to gravity at a stratified interface. An effective Richardson number representing the ratio of potential to kinetic energy characterizes the topography of the interface. When the electric field is turned on, the repulsion of the hot gas from the idealized blade is evident in video recordings and thermocouple measurements.

  14. Linear and quadratic static response functions and structure functions in Yukawa liquids.

    PubMed

    Magyar, Péter; Donkó, Zoltán; Kalman, Gabor J; Golden, Kenneth I

    2014-08-01

    We compute linear and quadratic static density response functions of three-dimensional Yukawa liquids by applying an external perturbation potential in molecular dynamics simulations. The response functions are also obtained from the equilibrium fluctuations (static structure factors) in the system via the fluctuation-dissipation theorems. The good agreement of the quadratic response functions, obtained in the two different ways, confirms the quadratic fluctuation-dissipation theorem. We also find that the three-point structure function may be factorizable into two-point structure functions, leading to a cluster representation of the equilibrium triplet correlation function. PMID:25215834

  15. Linear and quadratic static response functions and structure functions in Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Magyar, Péter; Donkó, Zoltán; Kalman, Gabor J.; Golden, Kenneth I.

    2014-08-01

    We compute linear and quadratic static density response functions of three-dimensional Yukawa liquids by applying an external perturbation potential in molecular dynamics simulations. The response functions are also obtained from the equilibrium fluctuations (static structure factors) in the system via the fluctuation-dissipation theorems. The good agreement of the quadratic response functions, obtained in the two different ways, confirms the quadratic fluctuation-dissipation theorem. We also find that the three-point structure function may be factorizable into two-point structure functions, leading to a cluster representation of the equilibrium triplet correlation function.

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

    E-print Network

    Bin Liu; J. Goree

    2005-11-08

    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.

  17. Coulomb scattering for scalar field in Scr\\" odinger picture

    E-print Network

    Crucean Cosmin; Racoceanu Radu; Pop Adrian

    2008-04-11

    The scattering of a charged scalar field on Coulomb potential on de Sitter space-time is studied using the solution of the free Klein-Gordon equation. We find that the scattering amplitude is independent of the choice of the picture and in addition the total energy is conserved in the scattering process.

  18. Infrared Critical Exponents in Finite-Temperature Coulomb Gauge QCD

    E-print Network

    Klaus Lichtenegger; Daniel Zwanziger

    2009-11-28

    We investigate the infrared critical exponents of Coulomb gauge Yang-Mills theory in the limit of very high temperature. This allows us to focus on one scale (the spatial momentum) since all but the lowest Matsubara frequency decouple from the deep infrared. From the first-order Dyson-Schwinger equations in a bare-vertex truncation we obtain infrared exponents which correspond to confining or overconfining (yet mathematically well-defined) solutions. For three spatial dimensions the exponents are close to what is expected for a linearly rising color-Coulomb potential.

  19. The effect of Coulombic friction on spatial displacement statistics

    E-print Network

    Menzel, Andreas M

    2010-01-01

    The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. These results are relevant to recent experimental studies of the displacement of colloidal particles along bilayer membrane tubes.

  20. The effect of Coulombic friction on spatial displacement statistics

    E-print Network

    Andreas M. Menzel; Nigel Goldenfeld

    2011-06-23

    The phenomenon of Coulombic friction enters the stochastic description of dry friction between two solids and the statistic characterization of vibrating granular media. Here we analyze the corresponding Fokker-Planck equation including both velocity and spatial components, exhibiting a formal connection to a quantum mechanical harmonic oscillator in the presence of a delta potential. Numerical solutions for the resulting spatial displacement statistics show a crossover from exponential to Gaussian displacement statistics. We identify a transient intermediate regime that exhibits multiscaling properties arising from the contribution of Coulombic friction. The possible role of these effects during observations in diffusion experiments is shortly discussed.

  1. Coulomb blockade of resonant tunneling

    Microsoft Academic Search

    H. T. Imam; V. V. Ponomarenko; D. V. Averin

    1994-01-01

    We have considered the influence of electromagnetic fluctuations on electron tunneling via one nondegenerate resonant level, the problem that is relevant for electron transport through quantum dots in the Coulomb blockade regime. We show that the overall effect of the fluctuations depends on whether the electron bands in external electrodes are empty or filled. In the empty band case, depending

  2. Laser Coulomb-explosion imaging of small molecules

    SciTech Connect

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

    2005-01-01

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

  3. Nonasymptotic analysis of relativistic electron scattering in the Coulomb field

    SciTech Connect

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

    2010-11-15

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

  4. Cytotoxic Ribonucleases: The Dichotomy of Coulombic Forces†

    PubMed Central

    Johnson, R. Jeremy; Chao, Tzu-Yuan; Lavis, Luke D.; Raines, Ronald T.

    2010-01-01

    Cells tightly regulate their contents. Still, nonspecific Coulombic interactions between cationic molecules and anionic membrane components can lead to adventitious endocytosis. Here, we characterize this process in a natural system. To do so, we create variants of human pancreatic ribonuclease (RNase 1) that differ in net molecular charge. By conjugating a small-molecule latent fluorophore to these variants and using flow cytometry, we are able to determine the kinetic mechanism for RNase 1 internalization into live human cells. We find that internalization increases with solution concentration and is not saturable. Internalization also increases with time to a steady-state level, which varies linearly with molecular charge. In contrast, the rate constant for internalization (t1/2 = 2 h) is independent of charge. We conclude that internalization involves an extracellular equilibrium complex between the cationic proteins and abundant anionic cell-surface molecules, followed by rate-limiting internalization. The enhanced internalization of more cationic variants of RNase 1 is, however, countered by their increased affinity for the cytosolic ribonuclease inhibitor protein, which is anionic. Thus, Coulombic forces mediate extracellular and intracellular equilibria in a dichotomous manner that both endangers cells and defends them from the potentially lethal enzymatic activity of ribonucleases. PMID:17705507

  5. Practical thermodynamics of Yukawa systems at strong coupling

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.; Kryuchkov, Nikita P.; Yurchenko, Stanislav O.; Thomas, Hubertus M.

    2015-05-01

    Simple practical approach to estimate thermodynamic properties of strongly coupled Yukawa systems, in both fluid and solid phases, is presented. The accuracy of the approach is tested by extensive comparison with direct computer simulation results (for fluids and solids) and the recently proposed shortest-graph method (for solids). Possible applications to other systems of softly repulsive particles are briefly discussed.

  6. Gravitational Corrections to Yukawa and phi{sup 4} Interactions

    SciTech Connect

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

    2010-02-26

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

  7. On the shear viscosity of 3D Yukawa liquids

    SciTech Connect

    Donko, Z.; Hartmann, P. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-l525 Budapest, P.O. Box 49 (Hungary)

    2008-09-07

    We report calculations of the shear viscosity of three-dimensional strongly-coupled Yukawa liquids, based on two different non-equilibrium molecular dynamics methods. The present simulations intend to improve the accuracy of shear viscosity data, compared to those obtained in earlier studies.

  8. Nonlocal Yukawa interaction and fermion mass-scale nonlocality

    SciTech Connect

    Namsrai, K. [Inst. of Physics and Technology, Ulaanbaatar (Mongolia)

    1996-08-01

    A nonlocal Yukawa interaction between the Higgs boson and the fundamental fermions is introduced. A simple form of this interaction allows us to calculate a particular mass-scale nonlocality for all fundamental fermions. A prediction is given for the mass of the Higgs boson (m{sub H} {approx} 200 GeV).

  9. Coulomb interactions in charged fluids

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

  10. Coulomb Blockade of Shot Noise

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  11. On the phase structure of a chiral invariant Higgs-Yukawa model

    NASA Astrophysics Data System (ADS)

    Gerhold, Philipp

    2006-12-01

    In the past the construction of Higgs-Yukawa models on the lattice was blocked by the lack of a consistent definition of a chiral invariant Yukawa coupling term. Here, we consider a chiral invariant Higgs-Yukawa model based on the overlap operator D (ov) realized by the Neuberger- Dirac operator. As a first step towards a numerical examination of this model we study its phase diagram by means of an analytic 1/N f -expansion, which is possible for small and for large values of the Yukawa coupling constant. In the case of strong Yukawa couplings the model effectively becomes an O(4)-symmetric non-linear ? -model.

  12. Coulomb Energies In Isobaric Multiplets

    SciTech Connect

    Bentley, M.A. [School of Chemistry and Physics, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)

    2005-04-05

    Examination of fundamental symmetries is one of the key aspirations in physics research. In nuclear physics, the most fundamental of these is the exchange symmetry between neutrons and protons. The approximate charge symmetry and charge independence of the nuclear force results in striking symmetries in nuclear behavior between isobaric analogue states (IAS) - states of the same isospin quantum number in a set of nuclei of the same total number of nucleons (an isobaric multiplet). The Coulomb force breaks this symmetry and is the dominating factor in producing the large shifts in absolute binding energy between IAS. Until recently, progress in understanding these energy shifts in detail was broadly restricted to the lowest energy states for a given isospin (e.g. the difference in ground state masses of a pair of mirror nuclei). However, the recent advances in spectroscopic techniques - especially the development of large gamma-ray spectrometers - has resulted in a wealth of information on IAS at high excitation energy and high angular momentum. The very small differences in excitation energy between the IAS can be interpreted, principally, in terms of Coulomb effects. The analysis of these Coulomb differences has been shown to be a remarkably sensitive probe of nuclear structure effects as well as providing stringent tests of state-of-the-art shell-model calculations. In this review, some of the latest results and their interpretation are presented.

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

    E-print Network

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

    2015-01-01

    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.

  14. Lower Higgs boson mass bounds from a chirally invariant lattice Higgs-Yukawa model with overlap fermions

    E-print Network

    P. Gerhold; K. Jansen

    2009-02-24

    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.

  15. Spectroscopy as a test of Coulomb's law: A probe of the hidden sector

    NASA Astrophysics Data System (ADS)

    Jaeckel, Joerg; Roy, Sabyasachi

    2010-12-01

    High precision spectroscopy can provide a sensitive tool to test Coulomb’s law on atomic length scales. This can then be used to constrain particles such as extra “hidden” photons or minicharged particles that are predicted in many extensions of the standard model, and which cause small deviations from Coulomb’s law. In this paper we use a variety of transitions in atomic hydrogen, hydrogenic ions, and exotic atoms to probe Coulomb’s law. This extends the region of pure Coulomb’s law tests to larger masses. For hidden photons and minicharged particles this region is already tested by other astrophysical and laboratory probes. However, future tests of true muonium and muonic atoms are likely to probe new parameter space and therefore have good discovery potential for new physics. Finally, we investigate whether the discrepancy between the theoretical calculation of the 2s1/2F=1-2p3/2F=2 transition in muonic hydrogen and its recent experimental measurement at PSI can be explained by the existence of a hidden photon. This explanation is ruled out by measurements of the Lamb shift in ordinary hydrogen.

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

    NASA Astrophysics Data System (ADS)

    Sadooghi, N.; Taghinavaz, F.

    2014-06-01

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

  17. Exponentially spread dynamical Yukawa couplings from non-perturbative chiral symmetry breaking in the dark sector

    E-print Network

    Gabrielli, Emidio

    2014-01-01

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

  18. Approximate Coulomb distortion effects in (e,e'p) reactions

    E-print Network

    K. S. Kim; L. E. Wright

    2005-03-30

    In this paper we apply a well-tested approximation of electron Coulomb distortion effects to the exclusive reaction (e,e'p) in the quasielastic region. We compare the approximate treatment of Coulomb distortion effects to the exact distorted wave Born approximation evaluated by means of partial wave analysis to gauge the quality of our approximate treatment. We show that the approximate M\\"oller potential has a plane-wave-like structure and hence permits the separation of the cross section into five terms which depend on bilinear products of transforms of the transition four current elements. These transforms reduce to Fourier transforms when Coulomb distortion is not present, but become modified with the inclusion of Coulomb distortion. We investigate the application of the approximate formalism to a model of 208Pb(e,e'p) using Dirac-Hartree single particle wave functions for the ground state and relativistic optical model wave functions for the continuum proton. We show that it is still possible to extract, albeit with some approximation, the various structure functions from the experimentally measured data even for heavy nuclei.

  19. Yukawa unification and sparticle spectroscopy in gauge mediation models

    NASA Astrophysics Data System (ADS)

    Gogoladze, Ilia; Mustafayev, Azar; Shafi, Qaisar; Ün, Cem Salih

    2015-05-01

    We explore the implications of the t -b -? (and b -? ) Yukawa coupling unification condition on the fundamental parameter space and sparticle spectroscopy in the minimal gauge mediated supersymmetry breaking model. We find that this scenario prefers values of the C P -odd Higgs mass mA?1 TeV , with all colored sparticle masses above 3 TeV. These predictions will be hard to test at LHC13 but they may be testable at the high-energy LHC (HE-LHC) 33 TeV or a 100 TeV collider. Both the t -b -? and the b -? Yukawa coupling unification prefer a relatively light gravitino with mass ?30 eV , which makes it a candidate hot dark matter particle. However, it cannot account for more than 15% of the observed dark matter density.

  20. Coulomb force as an entropic force

    NASA Astrophysics Data System (ADS)

    Wang, Tower

    2010-05-01

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

  1. Dimensional renormalization of Yukawa theories via Wilsonian methods

    NASA Astrophysics Data System (ADS)

    Pernici, M.; Raciti, M.; Riva, F.

    2000-06-01

    In the 't Hooft-Veltman dimensional regularization scheme it is necessary to introduce finite counterterms to satisfy chiral Ward identities. It is a non-trivial task to evaluate these counterterms even at two loops. We suggest the use of Wilsonian exact renormalization group techniques to reduce the computation of these counterterms to simple master integrals. We illustrate this method by a detailed study of a generic Yukawa model with massless fermions at two loops.

  2. Dimensional renormalization of Yukawa theories wia Wilsonian methods

    E-print Network

    Pernici, M; Riva, F

    2000-01-01

    In the 't Hooft-Veltman dimensional regularization scheme it is necessary to introduce finite counterterms to satisfy chiral Ward identities. It is a non-trivial task to evaluate these counterterms even at two loops. We suggest the use of Wilsonian exact renormalization group techniques to reduce the computation of these counterterms to simple master integrals. We illustrate this method by a detailed study of a generic Yukawa model with massless fermions at two loops.

  3. Dimensional renormalization of Yukawa theories wia Wilsonian methods

    E-print Network

    M. Pernici; M. Raciti; F. Riva

    2000-01-20

    In the 't Hooft-Veltman dimensional regularization scheme it is necessary to introduce finite counterterms to satisfy chiral Ward identities. It is a non-trivial task to evaluate these counterterms even at two loops. We suggest the use of Wilsonian exact renormalization group techniques to reduce the computation of these counterterms to simple master integrals. We illustrate this method by a detailed study of a generic Yukawa model with massless fermions at two loops.

  4. Hard-core yukawa model for charge-stabilized colloids

    PubMed

    Davoudi; Kohandel; Mohammadi; Tanatar

    2000-11-01

    The hypernetted chain approximation is used to study the phase diagram of a simple hardcore Yukawa model of a charge-stabilized colloids. We calculate the static structure factor, the pair distribution function, and the collective mode energies over a wide range of parameters, and the results are used for studying the freezing transition of the system. The resulting phase diagram is in good agreement with the known estimates and the Monte Carlo simulations. PMID:11102053

  5. Optical spectra and intensities of graphene magnetic dot bound to a negatively charged Coulomb impurity

    SciTech Connect

    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

    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.

  6. Nonstandard Yukawa Couplings and Higgs Portal Dark Matter

    E-print Network

    Fady Bishara; Joachim Brod; Patipan Uttayarat; Jure Zupan

    2015-05-15

    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 interesting bounds on the light-quark Yukawa couplings.

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

    E-print Network

    Hovhannes R. Grigoryan; Yuri V. Kovchegov

    2011-06-23

    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.

  8. Coulomb drag between quantum wires

    NASA Astrophysics Data System (ADS)

    Klesse, Rochus; Stern, Ady

    2000-12-01

    We study Coulomb drag in a pair of parallel one-dimensional electron systems within the framework of the Tomonaga-Luttinger model. We find that Coulomb coupling has a much stronger effect on one-dimensional wires than on two-dimensional layers: At zero temperature the transresistivity diverges, due to the formation of locked charge density waves. At temperature well above a crossover temperature T* the transresistivity follows a power law ?~Tx, where the interaction-strength dependent exponent x is determined by the Luttinger liquid parameter Kc- of the relative charge mode. At temperature below T* relative charge displacements are enabled by solitonic excitations, reflected by an exponential temperature dependence. The crossover temperature T* depends sensitively on the wire width, interwire distance, Fermi wavelength and the effective Bohr radius. For wire distances d¯>>k-1F it is exponentially suppressed with T*/EF~exp[-d¯kF/(1-Kc-)]. The behavior changes drastically if each of the two wires develop spin gaps. In this case we find that the transresistivity vanishes at zero temperature. We discuss our results in view of possible experimental realizations in GaAs-AlxGa1-xAs semiconductor structures.

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

    NASA Astrophysics Data System (ADS)

    Novikov, Lev; Makletsov, Andrei; Sinolits, Vadim

    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

  10. Exact Solution of a Charge-Asymmetric Two-Dimensional Coulomb Gas

    Microsoft Academic Search

    L. Samaj

    2002-01-01

    The model under consideration is an asymmetric two-dimensional Coulomb gas of positively (q_1=+1) and negatively (q_2=-1\\/2) charged pointlike particles, interacting via a logarithmic potential. This continuous system is stable against collapse of positive-negative pairs of charges for the dimensionless coupling constant (inverse temperature) \\\\beta<4. The mapping of the Coulomb gas is made onto the complex Bullough-Dodd model, and recent results

  11. Aspect of Fermion Mass Hierarchy within Flavor Democracy for Yukawa Couplings

    NASA Astrophysics Data System (ADS)

    Higuchi, Katsuichi; Yamamoto, Katsuji

    We discuss the fermion mass hierarchy by including vector-like fermions which are accommodated in E6 GUTs within flavor democracy for Yukawa couplings. In this framework, all Yukawa couplings for the standard Higgs doublet have the same strength, and all Yukawa couplings for the singlet Higgs have the same strength (New ansatz). In addition, singlet Higgs and right-handed neutrinos exist. Under this condition, the mass hierarchy mt ? mb ˜ m? as well as mt ? mc, mu can be naturally explained.

  12. Yukawa terms in noncommutative SO(10) and E{sub 6} GUTs

    SciTech Connect

    Martin, C. P. [Departamento de Fisica Teorica I, Facultad de Ciencias Fisicas Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2010-10-15

    We propose a method for constructing Yukawa terms for noncommutative SO(10) and E{sub 6} GUTs when these GUTs are formulated within the enveloping-algebra formalism. The most general noncommutative Yukawa term that we propose contains, at first order in {theta}{sup {mu}{nu},} the most general Becchi-Rouet-Stora invariant Yukawa contribution whose only dimensionful parameter is the noncommutativity parameter. This noncommutative Yukawa interaction is thus renormalizable at first order in {theta}{sup {mu}{nu}}.

  13. Measurement of the leptoquark Yukawa couplings in e+e- collisions at TESLA

    E-print Network

    Aleksander Filip Zarnecki

    2001-02-22

    Measurement of the Yukawa couplings of the first-generation leptoquarks has been studied for e+e- collisions at TESLA, at sqrt(s)=800 GeV. By combining measurements from different production and decay channels, determination of Yukawa couplings with precision on the few per-cent level is possible. TESLA will be sensitive to very small leptoquark Yukawa couplings not accessible at LHC, down to lambda ~ 0.05 [e]. Distinction between left-handed and right-handed Yukawa couplings is feasible even for leptoquark masses very close to the pair-production kinematic limit.

  14. Coulomb Blockade with Neutral Modes

    NASA Astrophysics Data System (ADS)

    Kamenev, Alex; Gefen, Yuval

    2015-04-01

    We study transport through a quantum dot in the fractional quantum Hall regime with filling factors ? =2 /3 and ? =5 /2 , weakly coupled to the leads. We account for both injection of electrons to or from the leads, and quasiparticle rearrangement processes between the edge and the bulk of the quantum dot. The presence of neutral modes introduces topological constraints that modify qualitatively the features of the Coulomb blockade (CB). The periodicity of CB peak spacings doubles and the ratio of spacing between adjacent peaks approaches (in the low temperature and large dot limit) a universal value: 2 ?1 for ? =2 /3 and 3 ?1 for ? =5 /2 . The corresponding CB diamonds alternate their width in the direction of the bias voltage and allow for the determination of the neutral mode velocity, and of the topological numbers associated with it.

  15. Plane Wave and Coulomb Asymptotics

    NASA Astrophysics Data System (ADS)

    Mulligan, P. G.; Crothers, D. S. F.

    2004-01-01

    A simple plane wave solution of the Schrödinger Helmholtz equation is a quantum eigenfunction obeying both energy and linear momentum correspondence principles. Inclusion of the outgoing wave with scattering amplitude f obeys unitarity and the optical theorem. By closely considering the standard asymptotic development of the plane wave, we show that there is a problem with angular momentum when we consider forward scattering at the point of closest approach and at large impact parameter given semiclassically by (l + 1/2)/k where l is the azimuthal quantum number and may be large (J Leech et al, Phys. Rev. Lett. 88 257901 (2002)). The problem is resolved via non-uniform, non-standard analysis involving the Heaviside step function, unifying classical, semiclassical and quantum mechanics, and the treatment is extended to the case of pure Coulomb scattering.

  16. Coulomb blockade with neutral modes.

    PubMed

    Kamenev, Alex; Gefen, Yuval

    2015-04-17

    We study transport through a quantum dot in the fractional quantum Hall regime with filling factors ?=2/3 and ?=5/2, weakly coupled to the leads. We account for both injection of electrons to or from the leads, and quasiparticle rearrangement processes between the edge and the bulk of the quantum dot. The presence of neutral modes introduces topological constraints that modify qualitatively the features of the Coulomb blockade (CB). The periodicity of CB peak spacings doubles and the ratio of spacing between adjacent peaks approaches (in the low temperature and large dot limit) a universal value: 2?1 for ?=2/3 and 3?1 for ?=5/2. The corresponding CB diamonds alternate their width in the direction of the bias voltage and allow for the determination of the neutral mode velocity, and of the topological numbers associated with it. PMID:25933323

  17. Relativistic Coulomb scattering of spinless bosons

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Grady, Michael

    2013-11-01

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

  19. Diffusion coefficient of three-dimensional Yukawa liquids

    SciTech Connect

    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

    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.

  20. Thermodynamics and phase transitions in two-dimensional Yukawa systems

    NASA Astrophysics Data System (ADS)

    Vaulina, O. S.; Koss, X. G.

    2014-10-01

    The results of numerical simulations of strongly-coupled two-dimensional dissipative Yukawa systems are presented. The thermodynamic characteristics of these systems were studied, namely the internal energy, the specific heat and the entropy. For the first time, it is discovered that the considered characteristics have two singular points on the melting line; one of these points corresponds to the first-order phase transition from crystal to the hexatic phase, and another point corresponds to the second-order phase transition from the hexatic phase to the isotropic liquid. The obtained results are compared to the existing numerical and analytical data.

  1. Memorial Archival Libraries of Yukawa, Tomonaga, and Sakata

    NASA Astrophysics Data System (ADS)

    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

    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.

  2. Local mirror symmetry of curves: Yukawa couplings and genus 1

    Microsoft Academic Search

    Brian Forbes; Masao Jinzenji

    2006-01-01

    We continue our study of equivariant local mirror symmetry of curves, i.e.\\u000amirror symmetry for X_k=O(k)+O(-2-k) over P^1 with torus action\\u000a(lambda_1,lambda_2) on the bundle. For the antidiagonal action\\u000alambda_1=-lambda_2, we find closed formulas for the mirror map and a rational B\\u000amodel Yukawa coupling for all k. Moreover, we give a simple closed form for the\\u000aB model genus

  3. Phase diagram of the hard-sphere/attractive-Yukawa system

    NASA Astrophysics Data System (ADS)

    Mederos, L.; Navascués, G.

    1994-12-01

    A density functional approximation is used to study the phase diagram of a hard sphere-attractive Yukawa system. We pay special attention to the dependence of the liquid phase stability on the range of the attractive tail. When this is sufficiently short-ranged, the liquid phase is not present in the phase diagram. The transition to the usual behavior with a phase diagram showing vapor, liquid, and solid phases takes place for a value of the range of the attractive part which is in reasonable agreement with recent Monte Carlo simulations and theoretical results.

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

    E-print Network

    N. Sadooghi; F. Taghinavaz

    2015-04-16

    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).

  5. Description of the Coulomb excitation of the rotational state in the /sup 162/Dy nucleus on the basis of the uniform semiclassical approximation

    SciTech Connect

    Bolotin, Y.L.; Gonchar, V.Y.; Chekanov, N.A.

    1985-09-01

    The Coulomb excitation of rotational states in heavy-ion collisions is considered on the basis of the uniform semiclassical approximation. Included in the Hamiltonian of the system in question, besides the Coulomb forces (the monopole, quadrupole, and hexadecapole forces), is a real internuclear potential in the form of a deformed Woods-Saxon potential. It is shown that the excitation probability depends strongly on the interference between the Coulomb and nuclear interactions. Calculations are carried out for the reaction /sup 40/Ar+/sup 162/Dy at E = 148.6 MeV, and satisfactory agreement is obtained between the computed Coulomb excitation probabilities and the corresponding experimental quantities.

  6. New LEP constraints on some supersymmetric Yukawa interactions that violate R-parity

    E-print Network

    Gautam Bhattacharyya; John Ellis; K. Sridhar

    1995-03-08

    We consider one-loop corrections to partial widths of the $Z$ induced by supersymmetric Yukawa interactions that violate $R$-parity. The precise experimental values of the leptonic $Z$ partial widths bound these Yukawa couplings, with the most interesting constraints being those on couplings involving the $\\tau$, since previous constraints on them were very mild.

  7. Testing the SUSY-QCD Yukawa coupling in a combined LHC/ILC analysis

    E-print Network

    A. Freitas; P. Z. Skands

    2006-09-19

    In order to establish supersymmetry (SUSY) at future colliders, the identity of gauge couplings and the corresponding Yukawa couplings between gauginos, sfermions and fermions needs to be verified. Here a first phenomenological study for determining the Yukawa coupling of the SUSY-QCD sector is presented, using a method which combines information from LHC and ILC.

  8. Coulomb excitation of 73Ga

    E-print Network

    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

    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.

  9. Crystallization in two-component Coulomb systems.

    PubMed

    Bonitz, M; Filinov, V S; Fortov, V E; Levashov, P R; Fehske, H

    2005-12-01

    The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found, which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principles computer simulations. PMID:16384315

  10. Higher Dimensional Coulomb Gases and Renormalized Energy Functionals

    E-print Network

    N. Rougerie; S. Serfaty

    2015-01-23

    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.

  11. Coulomb crystal mass spectrometry in a digital ion trap

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  12. Dielectric susceptibility of the Coulomb glass

    NASA Astrophysics Data System (ADS)

    Díaz-Sánchez, A.; Ortuño, M.; Pollak, M.; Pérez-Garrido, A.; Möbius, A.

    1999-01-01

    We derive a microscopic expression for the dielectric susceptibility ? of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation-dissipation theorem tells us that ? is a function of the thermal fluctuations of the dipole moment of the system. We calculate ? numerically for three-dimensional Coulomb glasses as a function of temperature and frequency.

  13. Coulomb interaction effects on the Majorana states in quantum wires.

    PubMed

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

    2014-04-30

    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

  14. Spherical-box approach for resonances in presence of Coulomb interaction

    E-print Network

    Shan-Gui Zhou; Jie Meng; En-Guang Zhao

    2009-11-06

    The spherical-box approach is extended to calculate the resonance parameters and the real part of the wave function for single particle resonances in a potential containing the long-range Coulomb interaction. A model potential is taken to demonstrate the ability and accuracy of this approach. The calculated resonance parameters are compared with available results from other methods. It is shown that in the presence of the Coulomb interaction, the spherical-box approach works well for not so broad resonances. In particular, for very narrow resonances, the present method gives resonance parameters in a very high precision.

  15. Elastic properties of mono- and polydisperse two-dimensional crystals of hard--core repulsive Yukawa particles

    E-print Network

    Jakub W. Narojczyk; P. M. Piglowski; K. W. Wojciechowski; K. V. Tretiakov

    2015-04-28

    Monte Carlo simulations of mono-- and polydisperse two--dimensional crystals are reported. The particles in the studied system, interacting through hard--core repulsive Yukawa potential, form a solid phase of hexagonal lattice. The elastic properties of crystalline Yukawa systems are determined in the $NpT$ ensemble with variable shape of the periodic box. Effects of the Debye screening length ($\\kappa^{-1}$), contact value of the potential ($\\epsilon$), and the size polydispersity of particles on elastic properties of the system are studied. The simulations show that the polydispersity of particles strongly influences the elastic properties of the studied system, especially on the shear modulus. It is also found that the elastic moduli increase with density and their growth rate depends on the screening length. Shorter screening length leads to faster increase of elastic moduli with density and decrease of the Poisson's ratio. In contrast to its three-dimensional version, the studied system is non-auxetic, i.e. shows positive Poisson's ratio.

  16. Yukawa textures or dark doublets from Two Higgs Doublet Models with $Z_3$ symmetry

    E-print Network

    Aranda, Alfredo; Noriega-Papaqui, Roberto; Vaquera-Araujo, Carlos A

    2014-01-01

    The effect of $Z_3$ symmetry on the general Two Higgs Doublet Model is explored. Of particular interest is the question of what can a $Z_3$ symmetry do beyond the usual case with $Z_2$. There are two independent scenarios that give some interesting results: first, by giving non-trivial charges to the Standard Model fermions, it is possible to use the $Z_3$ symmetry of the scalar potential to generate potentially useful Yukawa textures. This is not possible with $Z_2$. A series of possibilities is presented where their viability is addressed and a specific example in the quark sector is given for concreteness. The second venue of interest is in the area of inert doublets. It is shown that by considering the Standard Model plus two additional inert doublet scalars, i.e. a Dark Two Higgs Doublet Model, together with $Z_3$, a scenario can be obtained that differs from the $Z_2$ case. Some general comments are presented on the potentially interesting phenomenology of such model.

  17. Baryon asymmetry from leptogenesis with four zero neutrino Yukawa textures

    SciTech Connect

    Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir, E-mail: biswajit.adhikary@saha.ac.in, E-mail: ambar.ghosal@saha.ac.in, E-mail: probir.roy@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

    2011-01-01

    The generation of the right amount of baryon asymmetry ? of the Universe from supersymmetric leptogenesis is studied within the type-I seesaw framework with three heavy singlet Majorana neutrinos N{sub i} (i = 1,2,3) and their superpartners. We assume the occurrence of four zeroes in the neutrino Yukawa coupling matrix Y{sub ?}, taken to be ?? symmetric, in the weak basis where N{sub i} (with real masses M{sub i} > 0) and the charged leptons l{sub ?} (? = e,?,?) are mass diagonal. The quadrant of the single nontrivial phase, allowed in the corresponding light neutrino mass matrix m{sub ?}, gets fixed and additional constraints ensue from the requirement of matching ? with its observed value. Special attention is paid to flavor effects in the washout of the lepton asymmetry. We also comment on the role of small departures from high scale ?? symmetry due to RG evolution.

  18. Four Zero Neutrino Yukawa Textures in the Minimal Seesaw Framework

    E-print Network

    Gustavo C. Branco; David Emmanuel-Costa; M. N. Rebelo; Probir Roy

    2008-03-07

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

  19. Mapping Dirac Quasiparticles near a Single Coulomb Impurity on Graphene

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Brar, Victor; Shytov, Andrey; Wu, Qiong; Regan, Willian; Tsai, Hsin-Zon; Zettl, Alex; Levitov, Leonid; Crommie, Michael

    2012-02-01

    We have locally mapped the response of charge carriers to a single Coulomb potential placed on a gated graphene device. Scanning tunneling microscopy and spectroscopy were used to fabricate a tunable charge impurity and to measure how Dirac fermions screen it. By mapping spatial variation in the electronic structure of graphene we have directly probed the strength of screened electronic interactions, obtaining a value of epsilon = 3 for the intrinsic graphene dielectric constant. This small value suggests that microscopic electron-electron interactions contribute significantly to intrinsic graphene properties.

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

    E-print Network

    Stefan Antusch; Stephen F. King; Martin Spinrath

    2015-03-24

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

  1. "Safe" Coulomb Excitation of 30Mg

    E-print Network

    O. Niedermaier; H. Scheit; V. Bildstein; H. Boie; J. Fitting; R. von Hahn; F. K"ock; M. Lauer; U. K. Pal; H. Podlech; R. Repnow; D. Schwalm

    2004-12-17

    We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation gamma ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31) e2fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg lies still outside the ``island of inversion''.

  2. Physlets Tour 7: Coulomb's Law

    NSDL National Science Digital Library

    Wolfgang Christian

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

  3. Can one turn off Coulomb focusing?

    E-print Network

    Berman, S A; Uzer, T

    2015-01-01

    We find that Coulomb focusing persists even when the Coulomb field is barely noticeable compared with the laser field. Delayed recollisions proliferate in this regime and bring back energy slightly above the 3.17 U_p high-harmonic cutoff, in stark contradiction with the Strong Field Approximation. We investigate the nonlinear-dynamical phase space structures which underlie this dynamics. It is found that the energetic delayed recollisions are organized by a reduced number of periodic orbits and their invariant manifolds.

  4. Can one turn off Coulomb focusing?

    E-print Network

    S. A. Berman; C. Chandre; T. Uzer

    2015-06-02

    We find that Coulomb focusing persists even when the Coulomb field is barely noticeable compared with the laser field. Delayed recollisions proliferate in this regime and bring back energy slightly above the 3.17 U_p high-harmonic cutoff, in stark contradiction with the Strong Field Approximation. We investigate the nonlinear-dynamical phase space structures which underlie this dynamics. It is found that the energetic delayed recollisions are organized by a reduced number of periodic orbits and their invariant manifolds.

  5. Coulomb force as an entropic force

    SciTech Connect

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

    2010-05-15

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

  6. Nonrelativistic Coulomb Green's function in parabolic coordinates

    NASA Astrophysics Data System (ADS)

    Blinder, S. M.

    1981-02-01

    The nonrelativistic Coulomb Green's function G(+)(r1,r2,k) is evaluated by explicit summation over discrete and continuum eigenstates in parabolic coordinates. This completes the derivation of Meixner, who was able to obtain only the r1=0 and r2?? limiting forms of the Green's function. Further progress is made possible by an integral representation for a product of two Whittaker functions given by Buchholz. We obtain the closed form for the Coulomb Green's function previously derived by Hostler, via an analogous summation in spherical polar coordinates. The Rutherford scattering limit of the Green's function is also demonstrated, starting with an integral representation in parabolic coordinates.

  7. Coulomb Force as an Entropic Force

    E-print Network

    Tower Wang

    2010-05-17

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

  8. Relativistic Coulomb excitation at small impact parameters

    E-print Network

    B. F. Bayman; F. Zardi

    2006-05-22

    The semiclassical model of relativistic Coulomb excitation is studied in situations in which the impact parameter is small enough so that projectile and target charge distributions overlap. The electromagnetic effects of this overlap are shown to be small. Realistic nucleon-nucleon reaction cross-sections, and realistic nuclear radial charge and matter distributions are used to determine a formula for the lower impact parameter limit to be used in the calculation of the Coulomb excitation cross-section. A wide selection of projectile-target pairs is explored, in the bombarding energy range of 1 GeV to 5 GeV per nucleon.

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

    NASA Astrophysics Data System (ADS)

    Przybytek, Michal; Helgaker, Trygve

    2013-08-01

    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.

  10. Infrared divergence of the color-Coulomb self-energy in Coulomb gauge QCD

    E-print Network

    Y. Nakagawa; T. Saito; H. Toki; A. Nakamura

    2006-10-31

    We investigate the spectrum of the Faddeev-Popov operator in Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement phase, we observe the accumulation of the near-zero modes of the FP operator at large lattice volumes, and the color-Coulomb self-energy diverges in the infrared limit. Moreover, even in the deconfinement phase, the behavior of the FP eigenvalue density is qualitatively the same as in the confinement phase and the color-Coulomb self-energy is infrared divergent.

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

    E-print Network

    Zhang, Jue

    2015-01-01

    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.

  12. 3D dust clouds (Yukawa Balls) in strongly coupled dusty plasmas

    SciTech Connect

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

    2010-06-16

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

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

    E-print Network

    Yuji Igarashi; Jan M. Pawlowski

    2009-11-11

    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.

  14. Mean spherical approximation for the Lennard-Jones-like two Yukawa model: Comparison against Monte Carlo data

    E-print Network

    J. Krejcí; I. Nezbeda; R. Melnyk; A. Trokhymchuk

    2012-02-20

    Monte Carlo simulation studies are performed for the Lennard-Jones like two Yukawa (LJ2Y) potential to show how properties of this model fluid depend on the replacement of the soft repulsion by the hard-core repulsion. Different distances for the positioning of hard core have been explored. We have found, that for temperatures that are slightly lower and slightly higher of the critical point temperature for the Lennard-Jones fluid, placing the hard core at distances that are shorter than zero-potential energy is well justified by thermodynamic properties that are practically the same as in original LJ2Y model without hard core. However, going to extreme conditions with the high temperature one should be careful since presence of the hard core provokes changes in the properties of the system. The later is extremely important when the mean spherical approximation (MSA) theory is applied to treat the Lennard-Jones-like fluid.

  15. Bound state of solution of Dirac-Coulomb problem with spatially dependent mass

    E-print Network

    Eser Olgar; Hayder M. Dhahir; H. Mutaf

    2014-09-24

    The bound state solution of Coulomb Potentials in the Dirac equation is calculated for position dependent mass function M(r) within the framework of asymptotic iteration method (AIM). The eigenfunctions are derived in terms of hypergeometric function and function generator equation of AIM.

  16. Schrödinger Equation with a Coulomb Field in 2+1 Dimensions

    NASA Astrophysics Data System (ADS)

    Dong, Shishan; Dong, Shi-Hai

    The solutions of the two-dimensional Schrödinger equation with a Coulomb potential are briefly studied and compared with those of the Klein-Gordon case studied in this work. The eigenvalues and the normalized eigenfunctions are analytically obtained. The fine structure of the energy level for this system is also discussed.

  17. Effective field theory of gravity: Leading quantum gravitational corrections to Newton's and Coulomb's laws

    Microsoft Academic Search

    Faller; Sven

    2008-01-01

    In this paper we consider general relativity and its combination with scalar quantum electrodynamics (QED) as an effective quantum field theory at energies well below the Planck scale. This enables us to compute the one-loop quantum corrections to the Newton and Coulomb potentials induced by the combination of graviton and photon fluctuations. We derive the relevant Feynman rules and compute

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  19. Quantum capacitance and compressibility of graphene: The role of Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Lozovik, Yu. E.; Sokolik, A. A.; Zabolotskiy, A. D.

    2015-02-01

    Many-body effects on quantum capacitance, compressibility, renormalized Fermi velocity, and kinetic and interaction energies of massless Dirac electrons in graphene, induced by Coulomb interactions, are analyzed theoretically in the first-order, Hartree-Fock, and random-phase approximations. Recent experimental data on quantum capacitance and renormalized Fermi velocity are analyzed and compared with the theory. The bare Fermi velocity and the effective dielectric constants are obtained from the experimental data. A combined effect of Coulomb interactions and Gaussian fluctuations of the disorder potential is considered.

  20. Boltzmann-Langevin theory of Coulomb drag

    NASA Astrophysics Data System (ADS)

    Chen, W.; Andreev, A. V.; Levchenko, A.

    2015-06-01

    We develop a Boltzmann-Langevin description of the Coulomb drag effect in clean double-layer systems with large interlayer separation d as compared to the average interelectron distance ?F. Coulomb drag arises from density fluctuations with spatial scales of order d . At low temperatures, their characteristic frequencies exceed the intralayer equilibration rate of the electron liquid, and Coulomb drag may be treated in the collisionless approximation. As temperature is raised, the electron mean free path becomes short due to electron-electron scattering. This leads to local equilibration of electron liquid, and consequently drag is determined by hydrodynamic density modes. Our theory applies to both the collisionless and the hydrodynamic regimes, and it enables us to describe the crossover between them. We find that drag resistivity exhibits a nonmonotonic temperature dependence with multiple crossovers at distinct energy scales. At the lowest temperatures, Coulomb drag is dominated by the particle-hole continuum, whereas at higher temperatures of the collision-dominated regime it is governed by the plasmon modes. We observe that fast intralayer equilibration mediated by electron-electron collisions ultimately renders a stronger drag effect.

  1. Coulombic Effects on Ion Mobility Spectrometry

    SciTech Connect

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

    2009-06-15

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

  2. Coulomb blockade in graphene quantum dots

    Microsoft Academic Search

    Qiong Ma; Tao Tu; Zhi-Rong Lin; Guang-Can Guo; Guo-Ping Guo

    2009-01-01

    We study the conductance spectrum of graphene quantum dots, both single and multiple cases. The single electron tunneling phenomenon is investigated and the periodicity, amplitude and line shape of the Coulomb blockade oscillations at low temperatures are obtained. Further, we discuss the transport behavior when multiple dots are assembled in array and find a phase transition of conductance spectra from

  3. Mobility reduction and apparent activation energies produced by hopping transport in the presence of Coulombic defects

    NASA Astrophysics Data System (ADS)

    Mady, Franck; Renoud, Raphaël; Iacconi, Philibert

    2007-01-01

    A Monte Carlo simulation is proposed to study the mobility reduction due to Coulombic defects for hopping transport in a one-dimensional regular lattice. Hops between energetically equivalent sites and within an exponential distribution of energy levels are considered. In the absence of Coulombic wells, the calculations reproduce the well known features of Gaussian and highly dispersive transport respectively. When the field due to Coulombic potential wells is superimposed on the applied one, the macroscopic conduction features change dramatically. The computed apparent mobilities or transit times exhibit a Poole-Frenkel character and a modified Arrhenius temperature dependence. Their activation energy differs from the mean energy characterizing hops at the microscopic scale and it is found to depend on parameters such as the defect charge. This has important practical consequences for data interpretation.

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

    SciTech Connect

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

    2011-01-01

    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.

  5. Dynamical saddle vs Coulomb saddle in antiproton impact ionization

    Microsoft Academic Search

    M. Goddard; J. M. Feagin

    1996-01-01

    The slow Coulomb breakup of a bound pair of particles by charged particle impact is often characterized by the Coulomb saddle located between the two like charges. If the breakup includes an antiproton, however, the particles experience forces on the Coulomb saddle and will tend to drift off the saddle, possibly preventing three particle breakup. There is however a dynamical

  6. Fermionic dark matter with pseudo-scalar Yukawa interaction

    E-print Network

    Karim Ghorbani

    2014-12-06

    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 $m_{\\text{DM}} = 300$ 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 $m_{\\text{DM}} \\sim 38$ GeV annihilating predominantly into $b$ quarks, which can explain the Fermi-LAT galactic gamma-ray excess.

  7. Trapping of topological-structural defects in Coulomb crystals.

    PubMed

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

    2013-03-29

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

  8. Critical fluctuations and anomalous transport in soft Yukawa-Langevin systems

    E-print Network

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

    2009-07-06

    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.

  9. An asymptotic safety scenario for gauged chiral Higgs-Yukawa models

    NASA Astrophysics Data System (ADS)

    Gies, Holger; Rechenberger, Stefan; Scherer, Michael M.; Zambelli, Luca

    2013-12-01

    We investigate chiral Higgs-Yukawa models with a non-abelian gauged left-handed sector reminiscent to a sub-sector of the standard model. We discover a new weak-coupling fixed-point behavior that allows for ultraviolet complete RG trajectories which can be connected with a conventional long-range infrared behavior in the Higgs phase. This non-trivial ultraviolet behavior is characterized by asymptotic freedom in all interaction couplings, but a quasi conformal behavior in all mass-like parameters. The stable microscopic scalar potential asymptotically approaches flatness in the ultraviolet, however, with a non-vanishing minimum increasing inversely proportional to the asymptotically free gauge coupling. This gives rise to non-perturbative—though weak-coupling—threshold effects which induce ultraviolet stability along a line of fixed points. Despite the weak-coupling properties, the system exhibits non-Gaußian features which are distinctly different from its standard perturbative counterpart: e.g., on a branch of the line of fixed points, we find linear instead of quadratically running renormalization constants. Whereas the Fermi constant and the top mass are naturally of the same order of magnitude, our model generically allows for light Higgs boson masses. Realistic mass ratios are related to particular RG trajectories with a "walking" mid-momentum regime.

  10. Structure of multi-component/multi-Yukawa mixtures

    NASA Astrophysics Data System (ADS)

    Blum, L.; Arias, M.

    2006-09-01

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

  11. Ferromagnetic Coulomb phase in classical spin ice

    NASA Astrophysics Data System (ADS)

    Powell, Stephen

    2015-03-01

    Spin ice is a frustrated magnetic system that at low temperatures exhibits a Coulomb phase, a classical spin liquid with topological order and deconfined excitations. This work establishes the presence of a Coulomb phase with coexisting ferromagnetic order in a microscopic model of classical spin ice subject to uniaxial lattice distortion. General theoretical arguments are presented for the presence of such a phase, and its existence is confirmed using Monte Carlo results. This example is used to illustrate generic properties of spin liquids with magnetic order, including deconfinement of monopoles, signatures in the neutron-scattering structure factor, and critical behavior at phase transitions. An analogous phase, a superfluid with spontaneously broken particle-hole symmetry, is demonstrated in a model of hard-core lattice bosons, related to spin ice through the quantum-classical correspondence.

  12. Coulomb edge effects in graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Jaskolski, W.; Ayuela, A.

    2014-10-01

    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.

  13. Bionic Coulomb phase on the pyrochlore lattice

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  14. Dynamical Coulomb Blockade of Shot Noise

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  15. Feynman rules for Coulomb gauge QCD

    SciTech Connect

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

    2012-10-15

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

  16. Coulomb effect in single particle distributions

    NASA Astrophysics Data System (ADS)

    Bøggild, H.; Boissevain, J.; Dodd, J.; Erazmus, B.; Esumi, S.; Fabjan, C. W.; Ferenc, D.; Fields, D. E.; Franz, A.; Gaardhøje, J. J.; Hansen, O.; Hardtke, D.; van Hecke, H.; Holzer, E. B.; Humanic, T.; Hummel, P.; Jacak, B. V.; Jayanti, R.; Kaneta, M.; Kopytine, M.; Leltchouk, M.; Ljubicic, T.; Lörstad, B.; Maeda, N.; Medvedev, A.; Murray, M.; Nishimura, S.; Ohnishi, H.; Paic, G.; Pandey, S. U.; Piuz, F.; Pluta, J.; Polychronakos, V.; Potekhin, M.; Poulard, G.; Sakaguchi, A.; Simon-Gillo, J.; Schmidt-Sørensen, J.; Sondheim, W.; Spegel, M.; Sugitate, T.; Sullivan, J. P.; Sumi, Y.; Willis, W. J.; Wolf, K.; Xu, N.; Zachary, D.; NA44 Collaboration

    1996-02-01

    Single particle distributions from heavy-ion collisions show the effect of Coulomb interactions on the final state. While a rather strong effect is seen in the ratio {? -}/{? +} from central 158A·GeV/c Pb+Pb collisions, at most a small enhancement is found in the ratios from S+S and S+Pb collisions at 200A·GeV/c.

  17. Coulomb dissociation of {sup 27} P

    SciTech Connect

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

    2010-04-26

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

  18. Feasibility of Coulomb blockade thermometry in metrology

    Microsoft Academic Search

    A. J. Manninen; J. P. Kauppinen; S. Farhangfar; L. J. T. Taskinen; J. P. Pekola

    2000-01-01

    Coulomb blockade thermometer (CBT) is a simple, magnetic-field-independent primary thermometer for everyday use at cryogenic temperatures. Its properties are well understood by now. The absolute accuracy at present is about \\/+\\/-0.5%. Recently, we have started studying the possibility of using CBT in metrological applications. We have especially in mind the future extension of the international temperature scale below 0.65 K,

  19. Feasibility of Coulomb blockade thermometry in metrology

    Microsoft Academic Search

    A. J Manninen; J. P Kauppinen; S Farhangfar; L. J. T Taskinen; J. P Pekola

    2000-01-01

    Coulomb blockade thermometer (CBT) is a simple, magnetic-field-independent primary thermometer for everyday use at cryogenic temperatures. Its properties are well understood by now. The absolute accuracy at present is about ±0.5%. Recently, we have started studying the possibility of using CBT in metrological applications. We have especially in mind the future extension of the international temperature scale below 0.65 K,

  20. Yukawa Coupling Thresholds: Application to the MSSM and the Minimal Supersymmetric SU(5) GUT

    E-print Network

    Brian D. Wright

    1994-04-06

    We consider a particular class of threshold corrections to Yukawa couplings and mass relations in the MSSM and supersymmetric grand unified models. We give a complete treatment of Yukawa coupling thresholds at the unification scale $\\Mx$ and the effective supersymmetry scale $\\Ms$ and apply them to corrections to the tree-level prediction $y_b(\\Mx) = y_{\\tau}(\\Mx)$ in minimal supersymmetric SU(5). We apply both gauge and Yukawa coupling thresholds to gauge unification and the above Yukawa unification condition to find predictions for the top quark mass, $M_t$, the superheavy vector boson mass $\\Mv$ and the colored Higgs triplet mass $\\Mhs$. We discuss the dependencies of $\\Mx$ and $\\Mhs$ on $\\alpha_s(M_Z)$, $M_t$ and the sparticle spectrum as well as those of $M_t$ on $\\tan\\beta$, $\\alpha_s(M_Z)$ and the bottom quark mass, $M_b$. The effect of the Yukawa coupling thresholds on $M_t$ are given for representative sparticle spectra. We describe the quantitative differences between these effects for low and high $\\tan\\beta$. We also give new bounds on superheavy masses, incorporating proton decay as well as unification constraints, the former leading to a lower bound on $\\alpha_s$.

  1. Ellipsoidal Coulomb crystals in a linear radio-frequency trap U. Frhlich, B. Roth, and S. Schiller

    E-print Network

    Schiller, Stephan

    Ellipsoidal Coulomb crystals in a linear radio-frequency trap U. Fröhlich, B. Roth, and S. Schiller to be an ellipsoid. Laser-cooled 9 Be+ ellipsoidal ion crystals were produced and good agreement was found between, and the density is a local function of the trap potential only. For a harmonic potential, the density then has

  2. Coulomb gauge confinement in the heavy quark limit

    SciTech Connect

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

    2010-05-15

    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.

  3. Strong nuclear couplings as a source of Coulomb rainbow suppression

    SciTech Connect

    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

    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.

  4. Bound states at threshold resulting from Coulomb repulsion

    SciTech Connect

    Gridnev, Dmitry K. [FIAS, Ruth-Moufang Strasse 1, D-60438 Frankfurt am Main (Germany)

    2012-10-15

    The eigenvalue absorption for a many-particle Hamiltonian depending on a parameter is analyzed in the framework of non-relativistic quantum mechanics. The long-range part of pair potentials is assumed to be pure Coulomb and no restriction on the particle statistics is imposed. It is proved that if the lowest dissociation threshold corresponds to the decay into two likewise non-zero charged clusters then the bound state, which approaches the threshold, does not spread and eventually becomes the bound state at threshold. The obtained results have applications in atomic and nuclear physics. In particular, we prove that an atomic ion with the critical charge Z{sub cr} and N{sub e} electrons has a bound state at threshold given that Z{sub cr} Element-Of (N{sub e}- 2, N{sub e}- 1), whereby the electrons are treated as fermions and the mass of the nucleus is finite.

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

    NASA Technical Reports Server (NTRS)

    Marshall, J. R.

    1999-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Marshall, J. R.

    1999-09-01

    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 incr

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

    E-print Network

    P. Gerhold; K. Jansen

    2010-02-23

    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.

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

    E-print Network

    N. Sadooghi; F. Taghinavaz

    2014-05-14

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

  9. Exponential representation in the Coulomb three-body problem

    Microsoft Academic Search

    Alexei M Frolov; Vedene H Smith Jr

    2004-01-01

    The exponential representation in the Coulomb three-body problem is considered. It is shown that the exponential variational expansion in relative coordinates r32, r31 and r21 has a number of advantages for the bound state calculations in Coulomb three-body systems. Moreover, it appears that the exponential (or Laplace–Fourier) representation of the Coulomb three-body problem is an optimal approach to analyse and

  10. Particle Diffusion Due to Coulomb Scattering

    SciTech Connect

    V. Lebedev and S. Nagaitsev

    2002-06-03

    Conventionally, the multiple and single particle scattering in a storage ring are considered to be independent. Such an approach is simple and often yields sufficiently accurate results. Nevertheless, there is a class of problems where such an approach is not adequate and the single and multiple scattering need to be considered together. This can be achieved by solving an integro-differential equation for the particle distribution function, which correctly treats particle Coulomb scattering in the presence of betatron motion. A derivation of the equation is presented in the article. A numerical solution for one practical case is also considered.

  11. Coulombic dragging of molecular assemblies on nanotubes

    NASA Astrophysics Data System (ADS)

    Kral, Petr; Sint, Kyaw; Wang, Boyang

    2009-03-01

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

  12. Effect of Coulomb interaction on multi-electronwave packet dynamics

    SciTech Connect

    Shiokawa, T. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571 (Japan); Takada, Y. [Faculty of Engineering, Tokyo University of Science, Chiyoda, Tokyo, 102-0073, Japan and CREST, Japan Science and Technology Agency (Japan); Konabe, S.; Hatsugai, Y. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and CREST, Japan Science and Technology Agency (Japan); Muraguchi, M. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and CREST, Japan Science and Technology Agency (Japan); Endoh, T. [Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan and Center for Spintronics Integrated Systems, Tohoku University, Sendai, 980-8577, Japan and CREST, Japan Science and Technology Agency (Japan); Shiraishi, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8571, Japan and Center for Computational Science, University of Tsukuba, Tsukuba, 305-8577, Japan and CREST, Japan Science and Technology Agency (Japan)

    2013-12-04

    We have investigated the effect of Coulomb interaction on electron transport in a one-dimensional nanoscale structure using a multi-electron wave packet approach. To study the time evolution, we numerically solve the time-dependent Hartree-Fock equation, finding that the electron wave packet dynamics strongly depends on the Coulomb interaction strength. When the Coulomb interaction is large, each electron wave packet moves separately in the presence of an electric field. With weak Coulomb interaction, however, the electron wave packets overlap, forming and moving as one collective wave packet.

  13. Modification of Coulomb law and energy levels of the hydrogen atom in a superstrong magnetic field

    NASA Astrophysics Data System (ADS)

    Machet, B.; Vysotsky, M. I.

    2011-01-01

    We obtain the following analytical formula which describes the dependence of the electric potential of a pointlike charge on the distance away from it in the direction of an external magnetic field B: ?(z)=e/|z|[1-exp?(-6me2|z|)+exp?(-(2/?)e3B+6me2|z|)]. The deviation from Coulomb’s law becomes essential for B>3?Bcr/?=3?me2/e3?6×1016G. In such superstrong fields, electrons are ultrarelativistic except those which occupy the lowest Landau level (LLL) and which have the energy ?02=me2+pz2. The energy spectrum on which LLL splits in the presence of the atomic nucleus is found analytically. For B>3?Bcr/? it differs substantially from the one obtained without accounting for the modification of the atomic potential.

  14. Derivation of the nonlinear Schrödinger equation from a many body Coulomb system

    E-print Network

    Laszlo Erdos; Horng-Tzer Yau

    2002-05-22

    We consider the time evolution of N bosonic particles interacting via a mean field Coulomb potential. Suppose the initial state is a product wavefunction. We show that at any finite time the correlation functions factorize in the limit $N \\to \\infty$. Furthermore, the limiting one particle density matrix satisfies the nonlinear Hartree equation. The key ingredients are the uniqueness of the BBGKY hierarchy for the correlation functions and a new apriori estimate for the many-body Schr\\"odinger equations.

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

    SciTech Connect

    Allanach, B.C. [Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom)] [Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX (United Kingdom); King, S.F. [Department of Physics and Astronomy, University of Southampton, Southampton, SO9 5NH (United Kingdom)] [Department of Physics and Astronomy, University of Southampton, Southampton, SO9 5NH (United Kingdom); Leontaris, G.K. [Physics Department, University of Ioannina, P.O. Box 1186, GR-45110 Ioannina (Greece)] [Physics Department, University of Ioannina, P.O. Box 1186, GR-45110 Ioannina (Greece); Lola, S. [Theory Division, CERN, 1211 Geneva 23 (Switzerland)] [Theory Division, CERN, 1211 Geneva 23 (Switzerland)

    1997-09-01

    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 10{sup 16} GeV. The combination of the U(1){sub X} family symmetry and the Pati-Salam gauge group leads to a successful and predictive set of Yukawa textures involving two kinds of texture zeros: {ital horizontal} and {ital vertical} texture zeros. We discuss both symmetric and nonsymmetric textures in models of this kind, and in the second case perform a detailed numerical fit to the charged fermion mass and mixing data. Two of the Yukawa textures allow a low energy fit to the data with a total {chi}{sup 2} of 0.39 and 1.02, respectively, for three degrees of freedom. We also make a first attempt at deriving the nonrenormalizable operators required for the Yukawa textures from string theory. {copyright} {ital 1997} {ital The American Physical Society}

  16. Virial coefficients and vapor-liquid equilibria of the EXP6 and 2-Yukawa fluids

    E-print Network

    J. Krejcí; I. Nezbeda; R. Melnyk; A. Trokhymchuk

    2011-07-20

    Virial coefficients $B_2$ through $B_4$ and the vapor-liquid equilibria for the EXP6 and 2-Yukawa (2Y) fluids have been determined using numerical integrations and Gibbs ensemble simulations, respectively. The chosen 2Y models have been recently determined as an appropriate reference fluid for the considered EXP6 models.

  17. Top Higgs Yukawa Coupling Analysis from ttH bW-

    E-print Network

    Top Higgs Yukawa Coupling Analysis from e+ e- ¯ttH ¯bW- bW+¯bb Hajrah Tabassam1 Victoria Martin2 of this symme- try breaking, the Higgs boson, is the most probable particle to be discovered at the Large Hadron Collider (LHC). If one, or more, Higgs particles are discovered, precise measurements of all the properties

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

    E-print Network

    Goree, John

    Shear viscosity and shear thinning in two-dimensional Yukawa liquids Z. Donk´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

  19. Yukawa hierarchies at the point of E 8 in F-theory

    NASA Astrophysics Data System (ADS)

    Marchesano, Fernando; Regalado, Diego; Zoccarato, Gianluca

    2015-04-01

    We analyse the structure of Yukawa couplings in local SU(5) F-theory models with E 8 enhancement. In this setting the E 8 symmetry is broken down to SU(5) by a 7-brane configuration described by T-branes, all the Yukawa couplings are generated in the vicinity of a point and only one family of quarks and leptons is massive at tree-level. The other two families obtain their masses when non-perturbative effects are taken into account, being hierarchically lighter than the third family. However, and contrary to previous results, we find that this hierarchy of fermion masses is not always appropriate to reproduce measured data. We find instead that different T-brane configurations breaking E 8 to SU(5) give rise to distinct hierarchical patterns for the holomorphic Yukawa couplings. Only some of these patterns allow to fit the observed fermion masses with reasonable local model parameter values, adding further constraints to the construction of F-theory GUTs. We consider an E 8 model where such appropriate hierarchy is realised and compute its physical Yukawas, showing that realistic charged fermions masses can indeed be obtained in this case.

  20. Singular Yukawa and gauge couplings in d=4 Heterotic String Vacua

    E-print Network

    Matthias Klein; Jan Louis

    1997-07-24

    In this paper we discuss the singularities in the Yukawa and gauge couplings of N=1 compactifications of the SO(32) heterotic string in four space-time dimensions. Such singularities can arise from the strong coupling dynamics of a confined non-perturbative gauge group.

  1. SU(5) and SO(10) Models from F-Theory with Natural Yukawa Couplings

    E-print Network

    Tianjun Li

    2010-03-03

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

  2. Nonperturbative Determination of the QCD Potential at O(1/m)

    SciTech Connect

    Koma, Yoshiaki [Deutsches Elektronen-Synchrotron DESY, Theory Group, D-22607 Hamburg (Germany); Koma, Miho [Deutsches Elektronen-Synchrotron DESY, Theory Group, D-22607 Hamburg (Germany); Research Center for Nuclear Physics (RCNP), Osaka University, Osaka 576-0047 (Japan); Wittig, Hartmut [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet Mainz, D-55099 Mainz (Germany)

    2006-09-22

    The relativistic correction to the QCD static interquark potential at O(1/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static potential when applied to charmonium, and amounts to one-fourth of the Coulombic term for bottomonium.

  3. Higgs boson, sparticle masses and neutralino Dark Matter in Yukawa unified models

    NASA Astrophysics Data System (ADS)

    Un, Cem Salih

    This dissertation collects our results that we obtain for a class of Yukawa unified SO(10) grand unified theories with non-universal soft supersymmetry breaking (SSB) gaugino mass parameters. As known for a long time, in contrast to its non-supersymmetrical version, SO(10) grand unified theories predict Yukawa coupling unification as well as gauge coupling and matter field unifications. The models considered in this thesis are assumed to be in the framework of gravity mediated supersymmetry breaking, and boundary conditions among the SSB terms are set by the group theoretical structure and breaking patterns of SO(10) at the grand unification scale (MGUT). In addition, we assume universality in the SSB mass terms assigned to the sfermion generations. Since Yukawa coupling unification implies contradictory mass relations for the first two generations, we consider a model with a larger Higgs sector. In this case, we assume that the MSSM Higgs doublets solely reside in 10 dimensional representation (10 H) of SO(10) and extra Higgs fields negligibly couple to the third generation sfermions in order to maintain Yukawa coupling unification for the third generation (when we mention Yukawa unification throughout this thesis, we mean Yukawa unification for the third family, a.k.a. t -b-tau Yukawa unification). First we consider a supersymmetric grand unified model in which SO(10) breaks into the MSSM via non-renormalizable dimension-5 operators involving non-singlet F--terms. In our case, we consider an F--term belonging to 54 dimensional representation of SO(10) and it develops a non-zero vacuum expectation value that non-trivially generates the SSB gaugino masses such that M 1 : M2 : M3 = --1 : --3 : 2. We consider the case with mu, M 1, M2 > 0 and M3 < 0 such that muM2 >0 and muM 3 < 0 always hold. This model with non-universal and relative-sign gaugino masses has one less parameter by setting the masses of Higgs doublets to be equivalent to each other at MGUT than those in the standard approach to Yukawa coupling unification. We briefly show also that Yukawa unification is possible even with one less parameter, if one considers a case in which all scalars of the MSSM including the Higgs doublets are assigned with the same SSB mass term. In the case of relative-sign SSB mass terms, the gaugino mass relation forms a subspace of SU(4)c x SU(2)L x SU(2) R (4-2-2). Even though 4-2-2 does not require gauge coupling unification, if one assumes that 4-2-2 breaks into the MSSM at an energy scale ˜ MGUT, then it can hold gauge coupling unification as well as Yukawa unification. As a generalization of the previous model, 4-2-2 results in a heavy spectrum for the color particles (˜ 3 TeV ) as well. We conclude this thesis by considering the anomalous magnetic moment of muon (muon g -- 2). First, we examine the conditions that are necessary in order to be consistent with the experimental measurements. Since the supersymmetric contribution to muon g -- 2 evolves as 1/M, where M is mass of the sparticle running in the loop, the MSSM needs to have light smuons and gauginos (bino and wino), while the 125 GeV Higgs boson requires heavier spectra. In order to resolve this conflict, we consider a case in which the first two generations of sfermions are split from the third generation in their SSB mass. Similarly the MSSM Higgs doublets have different masses from each other, while universality in gaugino masses is held. We show that our results can simultaneously be consistent with 125 GeV Higgs boson and muon g -- 2 within 1sigma deviation from its theoretical value. (Abstract shortened by UMI.)

  4. Dynamical effects in the Coulomb expansion following nuclear fragmentation

    SciTech Connect

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

    1987-09-01

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

  5. COULOMB SYSTEMS ON RIEMANNIAN MANIFOLDS AND STABILITY OF MATTER

    E-print Network

    Enciso, Alberto

    COULOMB SYSTEMS ON RIEMANNIAN MANIFOLDS AND STABILITY OF MATTER ALBERTO ENCISO Abstract. We limit of Coulomb systems (cf. e.g. [10] and references therein) and, needless to say, the analysis precisely, let us denote by (1.1) HN,K := - i 1 2mi i + i

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

    SciTech Connect

    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

    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.

  7. Sine-Gordon mean field theory of a Coulomb gas Alexandre Diehl, Marcia C. Barbosa, and Yan Levin

    E-print Network

    Levin, Yan

    Sine-Gordon mean field theory of a Coulomb gas Alexandre Diehl, Marcia C. Barbosa, and Yan Levin, Rio Grande do Sul, Brazil Received 6 November 1996 Sine-Gordon field theory is used to investigate potential, the sine-Gordon theory predicts the phase diagram topologically identical to the Monte Carlo

  8. Chiral Symmetry restoration in the massive Thirring model at finite T and $\\mu Dimensional reduction and the Coulomb gas

    E-print Network

    Gómez-Nicola, A; Steer, D A

    2000-01-01

    We show that in certain limits the (1+1)-dimensional massive Thirring model at finite temperature $T$ is equivalent to a one-dimensional Coulomb gas of charged particles at the same $T$. This equivalence is then used to explore the phase structure of the massive Thirring model. For strong coupling and $T>>m$ (the fermion mass) the system is shown to behave as a free gas of "molecules" (charge pairs in the Coulomb gas terminology) made of pairs of chiral condensates. This binding of chiral condensates is responsible for the restoration of chiral symmetry as $T\\to\\infty$. In addition, when a fermion chemical potential $\\mu\

  9. Loop statistics in the Coulomb phase

    NASA Astrophysics Data System (ADS)

    Jaubert, Ludovic; Haque, Masud; Moessner, Roderich

    2012-02-01

    The Coulomb phase is a classical gauge field theory arising in frustrated systems with ``divergence free'' constraints, such as spin ice [1]. In this talk, we show how this phase can be understood as a loop model, and characterized by their loop length distribution and fractal dimensions [2]. Comparing similar models in 2- and 3-dimensions allows us to extract insights from connections to Stochastic-Loewner Evolution (SLE) processes, percolation and polymer physics. We mention implications of these results for related models and experiments (Heisenberg magnets, itinerant electrons [3]). [4pt] [1] Henley, Annual Review of Condensed Matter Physics 1, 179 (2010).[0pt] [2] Jaubert, Haque, Moessner, Phys. Rev. Lett. 107, 177202 (2011)[0pt] [3] Jaubert, Pitaecki, Haque & Moessner, in preparation (2012).

  10. Experimental realization of a Coulomb blockade refrigerator

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  11. The ghost propagator in Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Watson, P.; Reinhardt, H.

    2011-05-01

    We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until `forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

  12. Coulomb breakup of 6Li into ?+d in the field of a 208Pb ion

    NASA Astrophysics Data System (ADS)

    Irgaziev, B. F.; Nabi, Jameel-Un; Khan, Darwaish

    2011-12-01

    The triple differential cross section of the 208Pb(6Li,?d)208Pb quasielastic breakup is calculated at a collision energy of 156 MeV and a scattering angle range of 2?-6?. We fit the parameters of the Woods-Saxon potential using the experimental ?-d phase shifts for different states to describe the relative motion of the ? particle and deuteron. To check the validity of the two particle approach for the ?-d system, we apply a potential model to describe the 2H(?,?)6Li radiative capture. We calculate the Coulomb breakup using the semiclassical method while an estimation of the nuclear breakup is made on the basis of the diffraction theory. A comparison of our calculation with the experimental data of Kiener [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.44.2195 44, 2195 (1991)] gives evidence for the dominance of the Coulomb dissociation mechanism and the contribution of nuclear distortion, but is essentially smaller than the value reported by Hammache [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.82.065803 82, 065803 (2010)]. The results of our calculation for the triple cross sections (contributed by the Coulomb and nuclear mechanisms) of the 6Li breakup hint toward a forward-backward asymmetry in the relative direction of the ? particle and deuteron emission, especially at smaller scattering angles, in the 6Li center-of-mass (c.m.) system.

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  14. Fast elliptic solvers in cylindrical coordinates and the Coulomb collision operator

    SciTech Connect

    Pataki, Andras [Courant Institute, New York University, 251 Mercer Street, NY 10012 (United States); Greengard, Leslie, E-mail: greengard@cims.nyu.edu [Courant Institute, New York University, 251 Mercer Street, NY 10012 (United States)

    2011-09-01

    Highlights: {yields} We describe new fast solvers for elliptic partial differential equations in free space. {yields} We combine integral equation methods with Fourier methods to achieve high order accuracy. {yields} We apply these solvers to the evaluation of the Coulomb collision operator in plasma physics. - Abstract: In this paper, we describe a new class of fast solvers for separable elliptic partial differential equations in cylindrical coordinates (r, {theta}, z) with free-space radiation conditions. By combining integral equation methods in the radial variable r with Fourier methods in {theta} and z, we show that high-order accuracy can be achieved in both the governing potential and its derivatives. A weak singularity arises in the Fourier transform with respect to z that is handled with special purpose quadratures. We show how these solvers can be applied to the evaluation of the Coulomb collision operator in kinetic models of ionized gases.

  15. Coulomb field effect on plasma focusing and wake field acceleration

    SciTech Connect

    Amatuni, A.Ts.; Elbakian, S.S.; Sekhpossian, E.V. [Yerevan Physics Inst. (Armenia)

    1993-11-01

    It is shown that the fields generated by relativistic electron (positron) bunches moving in overdense cold plasma have two components -- wake and Coulomb. The existence of the Coulomb component is caused by the absence of the Debay screening of the charge moving in plasma with the velocity greater than the thermal velocity of the plasma electrons. It is shown that at some conditions the contribution of the Coulomb component to focusing and self-focusing of the electron (positron) bunches, and wake field generation could be essential. This conclusion is valid for different descriptions of cold plasma-relativistic electron bunch system.

  16. Coulomb blockade of nonlocal electron transport in metallic conductors

    NASA Astrophysics Data System (ADS)

    Golubev, D. S.; Zaikin, A. D.

    2012-03-01

    We consider a metallic wire coupled to two metallic electrodes via two junctions placed nearby. A bias voltage applied to one of such junctions alters the electron distribution function in the wire in the vicinity of another junction, thus modifying both its noise and the Coulomb blockade correction to its conductance. We evaluate such interaction corrections to both local and nonlocal conductances, demonstrating nontrivial Coulomb anomalies in the system under consideration. Experiments on nonlocal electron transport with Coulomb effects can be conveniently used to test inelastic electron relaxation in metallic conductors at low temperatures.

  17. Influence of proton beam Coulomb explosion in laser proton acceleration

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    SciTech Connect

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

    2011-08-15

    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.

  19. Thermodynamics of Yukawa fluids near the one-component-plasma limit

    E-print Network

    Sergey A. Khrapak; Igor L. Semenov; Lenaic Couedel; Hubertus M. Thomas

    2015-07-02

    Thermodynamics of weakly screened (near the one-component-plasma limit) Yukawa fluids in two and three dimensions is analyzed in detail. It is shown that the thermal component of the excess internal energy of these fluids, when expressed in terms of the properly normalized coupling strength, exhibits the scaling pertinent to the corresponding one-component-plasma limit (the scalings differ considerably between the two- and three-dimensional situations). This provides us with a simple and accurate practical tool to estimate thermodynamic properties of weakly screened Yukawa fluids. Particular attention is paid to the two-dimensional fluids, for which several important thermodynamic quantities are calculated to illustrate the application of the approach.

  20. Thermodynamics of Yukawa fluids near the one-component-plasma limit

    E-print Network

    Khrapak, Sergey A; Couedel, Lenaic; Thomas, Hubertus M

    2015-01-01

    Thermodynamics of weakly screened (near the one-component-plasma limit) Yukawa fluids in two and three dimensions is analyzed in detail. It is shown that the thermal component of the excess internal energy of these fluids, when expressed in terms of the properly normalized coupling strength, exhibits the scaling pertinent to the corresponding one-component-plasma limit (the scalings differ considerably between the two- and three-dimensional situations). This provides us with a simple and accurate practical tool to estimate thermodynamic properties of weakly screened Yukawa fluids. Particular attention is paid to the two-dimensional fluids, for which several important thermodynamic quantities are calculated to illustrate the application of the approach.

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

    E-print Network

    Philipp Gerhold; Karl Jansen; Jim Kallarackal

    2012-03-20

    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.

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

    SciTech Connect

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

    2012-07-27

    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.

  3. New constraints on the Yukawa-type corrections to Newtonian gravity at short separations

    E-print Network

    Klimchitskaya, G L

    2014-01-01

    We discuss the strongest constraints on the Yukawa-type corrections to Newton's gravitational law within a submicrometer interaction range following from measurements of the Casimir force. In this connection the complicated problems arising when comparing the measurement data with the Lifshitz theory are analyzed. Special attention is paid to the results of two recent experiments on measuring the Casimir interaction between ferromagnetic surfaces and sinusoidally corrugated surfaces at various angles between corrugations.

  4. Measuring the top-quark Yukawa coupling at hadron colliders via tth, h->WW

    E-print Network

    Maltoni, F; Willenbrock, Scott S D

    2002-01-01

    We study the signal and background for the process tth, h->WW at the LHC and a 100 TeV VLHC. Signals are studied in two-, three-, and four-lepton final states. We find a statistical uncertainty in the top-quark Yukawa coupling at the LHC of 16%, 8%, 12% for m_h = 130, 160, 190 GeV, respectively. The statistical uncertainty at the VLHC is likely to be negligible in comparison with the systematic uncertainty.

  5. Measuring the top-quark Yukawa coupling at hadron colliders via tth, h->WW

    E-print Network

    F. Maltoni; D. Rainwater; S. Willenbrock

    2002-02-21

    We study the signal and background for the process tth, h->WW at the LHC and a 100 TeV VLHC. Signals are studied in two-, three-, and four-lepton final states. We find a statistical uncertainty in the top-quark Yukawa coupling at the LHC of 16%, 8%, 12% for m_h = 130, 160, 190 GeV, respectively. The statistical uncertainty at the VLHC is likely to be negligible in comparison with the systematic uncertainty.

  6. Yukawa hierarchies at the point of $E_8$ in F-theory

    E-print Network

    Marchesano, Fernando; Zoccarato, Gianluca

    2015-01-01

    We analyse the structure of Yukawa couplings in local SU(5) F-theory models with $E_8$ enhancement. In this setting the $E_8$ symmetry is broken down to SU(5) by a 7-brane configuration described by T-branes, all the Yukawa couplings are generated in the vicinity of a point and only one family of quarks and leptons is massive at tree-level. The other two families obtain their masses when non-perturbative effects are taken into account, being hierarchically lighter than the third family. However, and contrary to previous results, we find that this hierarchy of fermion masses is not always appropriate to reproduce measured data. We find instead that different T-brane configurations breaking $E_8$ to SU(5) give rise to distinct hierarchical patterns for the holomorphic Yukawa couplings. Only some of these patterns allow to fit the observed fermion masses with reasonable local model parameter values, adding further constraints to the construction of F-theory GUTs. We consider an $E_8$ model where such appropriate...

  7. Molecular dynamics of Yukawa liquids in gravitation: Equilibrium, Instability and Transport

    NASA Astrophysics Data System (ADS)

    Charan, Harish; Ganesh, Rajaraman; Joy, Ashwin; Joy

    2014-12-01

    Using 2D molecular dynamics (MD) 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, acquire 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 (GK) formalism does not agree with that obtained from Einstein-Smoluchowski (ES) 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 be predominant as compared to the longitudinal mode, leading to a novel Anisotropic Solid-like Yukawa liquid (ASYL). In in-homogenous Yukawa liquids studied here, Mach cones are found to be asymmetric. When density gradient direction is set in the direction opposite to gravity, the equilibrium is shown to be unstable to Rayleigh-Taylor (RT) instabilities resulting in transport.

  8. Beyond the God-particle at the Tevatron: detecting gluinos from Yukawa-unified SUSY

    E-print Network

    Baer, Howard; Sekmen, Sezen; Summy, Heaya

    2009-01-01

    Simple SUSY GUT models based on the gauge group SO(10) require t-b-\\tau Yukawa coupling unification, in addition to gauge coupling and matter unification. The Yukawa coupling unification places strong constraints on the expected superparticle mass spectrum, with scalar masses \\sim 10 TeV while gluino masses are much lighter: in the 300--500 GeV range. The very heavy squarks suppress negative interference in the q\\bar{q}\\to\\tg\\tg cross section, leading to a large enhancement in production rates. The gluinos decay almost always via three-body modes into a pair of b-quarks, so we expect at least four b-jets per signal event. We investigate the capability of Fermilab Tevatron collider experiments to detect gluino pair production in Yukawa-unified SUSY. By requiring events with large missing E_T and \\ge 2 or 3 tagged b-jets, we find a 5\\sigma reach in excess of m_{\\tg}\\sim 400 GeV for 5 fb^{-1} of data. This range in m_{\\tg} is much further than the conventional Tevatron SUSY reach, and should cut a significant sw...

  9. Interatomic Coulombic Decay in two coupled Quantum Wells

    E-print Network

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

    2015-02-25

    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.

  10. Interatomic Coulombic decay in two coupled quantum wells

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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) nanostructure. 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 metastable state in the con-tinuum, i.e., a one-electron resonance state. This causes the lifetime of the ICD to be an order of magnitude smaller even at very long distances, and improves the efficiency of the ICD process. For the ICD to be the 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 time scale of picoseconds. Therefore, based on our results we can design an experiment that will observe the ICD phenomenon in QWs nanostructure. This work can lead to a design of a wavelength-sensitive detector which is efficient even at low intensities.

  11. Near-BPS Skyrmions: Nonshell configurations and Coulomb effects

    NASA Astrophysics Data System (ADS)

    Bonenfant, Eric; Harbour, Louis; Marleau, Luc

    2012-06-01

    The relatively small binding energy in nuclei suggests that they may be well represented by near-BPS Skyrmions since their mass is roughly proportional to the baryon number A. For that purpose, we propose a generalization of the Skyrme model with terms up to order six in derivatives of the pion fields and treat the nonlinear ? and Skyrme terms as small perturbations. For our special choice of mass term (or potential) V, we obtain well-behaved analytical BPS-type solutions with nonshell configurations for the baryon density, as opposed to the more complex shell-like configurations found in most extensions of the Skyrme model. Along with static and (iso)rotational energies, we add to the mass of the nuclei the often neglected Coulomb energy and isospin breaking term. Fitting the four model parameters, we find a remarkable agreement for the binding energy per nucleon B/A with respect to experimental data. These results support the idea that nuclei could be near-BPS Skyrmions.

  12. Coulomb crystals in the magnetic field

    SciTech Connect

    Baiko, D. A. [A.F. Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021 St. Petersburg (Russian Federation)

    2009-10-15

    The body-centered-cubic Coulomb crystal of ions in the presence of a uniform magnetic field is studied using the rigid electron background approximation. The phonon mode spectra are calculated for a wide range of magnetic-field strengths and for several orientations of the field in the crystal. The phonon spectra are used to calculate the phonon contribution to the crystal energy, entropy, specific heat, Debye-Waller factor of ions, and the rms ion displacements from the lattice nodes for a broad range of densities, temperatures, chemical compositions, and magnetic fields. Strong magnetic field dramatically alters the properties of quantum crystals. The phonon specific heat increases by many orders of magnitude. The ion displacements from their equilibrium positions become strongly anisotropic. The results can be relevant for dusty plasmas, ion plasmas in Penning traps, and especially for the crust of magnetars (neutron stars with superstrong magnetic fields B > or approx. 10{sup 14} G). The effect of the magnetic field on ion displacements in a strongly magnetized neutron star crust can suppress the nuclear reaction rates and make them extremely sensitive to the magnetic-field direction.

  13. Coulomb gauge ghost Dyson-Schwinger equation

    NASA Astrophysics Data System (ADS)

    Watson, P.; Reinhardt, H.

    2010-12-01

    A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative boundary condition (the value of the inverse ghost propagator dressing function at zero momentum), which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until forced to freeze out in the infrared to the value of the boundary condition. The renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.

  14. Tunable Coulomb blockade in nanostructured graphene C. Stampfer,a

    E-print Network

    Ihn, Thomas

    blockade and Coulomb diamond measurements on an etched, tunable single-layer graphene quantum dot measurements on an etched graphene quantum dot tunable by graphene side gates.12 The nanodevice, schematically

  15. Zeros of the Whittaker function associated to Coulomb waves

    NASA Astrophysics Data System (ADS)

    Esparza, J.; Lopez, J. L.; Sesma, J.

    1999-08-01

    The zeros in the complex z plane of the Whittaker function Wc/z,{micro}(z), closely related to spherical waves in the quantum-mechanical Coulomb problem, are investigated for varying real values of the parameters c and {micro}

  16. Kohn-Luttinger Effect in a Two-dimensional Dense Fermi Liquid with Coulomb Repulsion.

    NASA Astrophysics Data System (ADS)

    Galitski, Victor

    2000-03-01

    In 1965 Kohn and Luttinger showed that a Fermi-liquid is unstable against the superconductive transition even in the case of purely repulsive interaction among particles. It has been shown that there is a pairing due to this singularity at least for large orbital momenta l. Recent experiments on 2-D electron gas have renewed interest in Kohn-Luttinger effect. In this work we consider the case of 2-D dense Fermi-liquid with pure Coulomb interaction among electrons. We show that such a system becomes superconductive at very low temperatures. Following Chubukov [2], we calculate the singular part of the scattering amplitude ?(q) up to the third order in the perturbation theory. To calculate diagrams we use screened Coulomb interaction. This allows us to avoid divergencies of the scattering amplitude appearing due to the Coulomb potential being long-range and also makes the problem similar to the one for the dilute Fermi-gas with short-range repulsive forces. The desired singularity ?^sing(q) ~ ?( 2 pF )^2 -q^2 appears in the third order perturbation theory and allows us to find the transition temperature Tc for large l. [1] W. Kohn and J. H. Luttinger, Phys. Rev. Lett. 15, 524 (1965), [2] A. Chubukov, Phys. Rev. B 48, 1097 (1993).

  17. Coexistence and competition of on-site and intersite Coulomb interactions in Mott-molecular-dimers

    NASA Astrophysics Data System (ADS)

    Arruda, Alberto; Juliano, Raffael; Werlang, Thiago; Craco, Luis

    2015-03-01

    Recent findings of Mott-Hubbard physics in ultracold atoms trapped in periodic potentials have reinvigorated the search for quantum simulators of fermionic and bosonic Hubbard-like models. With this in mind, we performed a systematic study of a two-site realization of the Hubbard model, i.e, in a regime where this model can exactly treated. Particularly, we reveal the interplay between on-site (U) and intersite (V) Coulomb interactions in the extended two-site Hubbard model. Due to its atomic-like form quantum correlations intrinsic to Mott-molecular-dimers are exactly computed. Our results for physical quantities such as double occupancy and specific heat are consistent with those obtained for the one-band Hubbard model, suggesting that a two-site dimer model is able to capture the essential thermodynamic properties of strongly interacting electron systems. It is shown that intersite Coulomb interactions promotes the formation of doublons, which compete with the spin-singlet state induced by the on-site Coulomb repulsion. Our results are expected to be relevant for understanding electronic and thermodynamical properties of interacting electrons in strongly coupled magnetic atoms.

  18. Coulomb Blockade and Hopping Conduction in Graphene Quantum Dots Array

    Microsoft Academic Search

    Daeha Joung; Lei Zhai; Saiful I. Khondaker

    2010-01-01

    We show that the low temperature electron transport properties of chemically\\u000afunctionalized graphene can be explained as sequential tunneling of charges\\u000athrough a two dimensional array of graphene quantum dots (GQD). Below 15 K, a\\u000atotal suppression of current due to Coulomb blockade through GQD array was\\u000aobserved. Temperature dependent current-gate voltage characteristics show\\u000aCoulomb oscillations with energy scales of

  19. Coulomb blockade and hopping conduction in graphene quantum dots array

    Microsoft Academic Search

    Daeha Joung; Lei Zhai; Saiful I. Khondaker

    2011-01-01

    We show that the low-temperature electron transport properties of chemically functionalized graphene can be explained as sequential tunneling of charges through a two-dimensional array of graphene quantum dots (GQDs). Below 15 K, a total suppression of current due to Coulomb blockade through a GQD array was observed. Temperature-dependent current-gate voltage characteristics show Coulomb oscillations with energy scales of 6.2-10 meV

  20. Dimensional regularization and renormalization of Coulomb gauge quantum electrodynamics

    Microsoft Academic Search

    Don Heckathorn

    1979-01-01

    Quantum electrodynamics is renormalized in the Coulomb gauge with covariant counter terms and without momentum-dependent wave-function renormalization constants. We show how to dimensionally regularize non-covariant integrals occuring in this gauge, and prove that the ``minimal'' subtraction prescription excludes non-covariant counter terms. Motivated by the need for a renormalized Coulomb gauge formalism in certain practical calculations, we introduce a convenient prescription

  1. Wannier excitons signalling strong Coulomb coupling in graphene

    NASA Astrophysics Data System (ADS)

    Grönqvist, J. H.; Stroucken, T.; Lindberg, M.; Koch, S. W.

    2012-12-01

    The Wannier equation for quasiparticles with a linear dispersion is investigated. It is shown that Coulomb bound compounds of mass less electron-hole pairs can only exist if the effective coupling strength exceeds the critical value of approximately 0.46. At the critical value, a second-order transition to a weak Coulomb regime is found. It is shown that the existence of bound excitons indicates an instability of the noninteracting ground state.

  2. Diffusion and Coulomb separation of ions in dense matter.

    PubMed

    Beznogov, M V; Yakovlev, D G

    2013-10-18

    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

  3. Characterization of ion Coulomb crystals in a linear Paul trap

    SciTech Connect

    Okada, K.; Takayanagi, T. [Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554 (Japan); Wada, M. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ohtani, S. [Institute for Laser Science (ILS), University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585 (Japan); Schuessler, H. A. [Department of Physics, Texas A and M University, College Station, Texas 77843 (United States)

    2010-01-15

    We describe a simple and fast method for simulating observed images of ion Coulomb crystals. In doing so, cold elastic collisions between Coulomb crystals and virtual very light atoms are implemented in a molecular dynamics (MD) simulation code. Such an approach reproduces the observed images of Coulomb crystals by obtaining density plots of the statistics of existence of each ion. The simple method has the advantage of short computing time in comparison with previous calculation methods. As a demonstration of the simulation, the formation of a planar Coulomb crystal with a small number of ions has been investigated in detail in a linear ion trap both experimentally and by simulation. However, also large Coulomb crystals including up to 1400 ions have been photographed and simulated to extract the secular temperature and the number of ions. For medium-sized crystals, a comparison between experiments and calculations has been performed. Moreover, an MD simulation of the sympathetic cooling of small molecular ions was performed in order to test the possibility of extracting the temperature and the number of refrigerated molecular ions from crystal images of laser-cooled ions. Such information is basic to studying ultracold ion-molecule reactions using ion Coulomb crystals including sympathetically cooled molecular ions.

  4. Aftershock triggering by complete Coulomb stress changes

    USGS Publications Warehouse

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

    2002-01-01

    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.

  5. Realistic Yukawa Textures and SUSY Spectra from Intersecting Branes

    E-print Network

    Ching-Ming Chen; Tianjun Li; V. E. Mayes; D. V. Nanopoulos

    2008-06-16

    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^6/(Z2 x Z2) orientifold with some desirable semi-realistic 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_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.

  6. On the Proof by Reductio ad Absurdum of the Hohenberg-Kohn Theorem for Ensembles of Fractionally Occupied States of Coulomb Systems

    E-print Network

    E. S. Kryachko

    2006-02-06

    It is demonstrated that the original reductio ad absurdum proof of the generalization of the Hohenberg-Kohn theorem for ensembles of fractionally occupied states for isolated many-electron Coulomb systems with Coulomb-type external potentials by Gross et al. [Phys. Rev. A 37, 2809 (1988)] is self-contradictory since the to-be-refuted assumption (negation) regarding the ensemble one-electron densities and the assumption about the external potentials are logically incompatible to each other due to the Kato electron-nuclear cusp theorem. It is however proved that the Kato theorem itself provides a satisfactory proof of this theorem.

  7. Coulomb-influenced collisions in aerosols and dusty plasmas

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Ranganathan; Hogan, Christopher J., Jr.

    2012-02-01

    In aerosol and dusty plasma systems, the behavior of suspended particles (grains) is often strongly influenced by collisions occurring between ions and particles, as well as between particles themselves. In determining the collision kernel or collision rate coefficient for such charged entities, complications arise in that the collision process can be completely described neither by continuum transport mechanics nor by free molecular (ballistic) mechanics; that is, collisions are transition regime processes. Further, both the thermal energy and the potential energy between colliding entities can strongly influence the collision rate and must be considered. Flux-matching theory, originally developed by Fuchs, is frequently applied for calculation of collision rate coefficients under these circumstances. However, recent work suggests that crucial assumptions in flux-matching theory are not appropriate to describe transition regime collisions in the presence of potential interactions. Here, we combine dimensional analysis and mean first passage time calculations to infer the collision kernel between dilute charged entities suspended in a light background gas at thermal equilibrium. The motion of colliding entities is described by a Langevin equation, and Coulombic interactions are considered. It is found that the dimensionless collision kernel for these conditions, H, is a function of the diffusive Knudsen number, KnD (in contrast to the traditional Knudsen number), and the potential energy to thermal energy ratio, ?E. For small and large KnD, it is found that the dimensionless collision kernels inferred from mean first passage time calculations collapse to the appropriate continuum and free molecular limiting forms, respectively. Further, for repulsive collisions (?E negative) or attractive collisions with ?E<0.5, calculated results are in excellent agreement with flux-matching theory predictions, and the dimensionless collision kernel can be determined conveniently via use of the H(KnD) relationship found for hard-sphere collisions with modified definitions of H and KnD to account for potential energy. However, for ?E>0.5, it is found that flux-matching theory predictions substantially underestimate the collision kernel. We find that the collision process in this regime is governed by the minimum of KnD and Kn? (Kn?=3KnD/2?E), and based on calculations, propose a function H(KnD, Kn?) for collision kernel evaluation. The situations for which ?E>0.5 apply to singly charged nanoparticles and multiply charged submicrometer and supermicrometer particles, and are thus prevalent in both aerosol and dusty plasma environments.

  8. The ice-limit of Coulomb gauge Yang-Mills theory

    E-print Network

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

    2008-07-29

    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.

  9. Magnetic field effect on the Coulomb interaction of acceptors in semimagnetic quantum dot

    NASA Astrophysics Data System (ADS)

    Kalpana, P.; Merwyn, A.; Reuben, Jasper D.; Nithiananthi, P.; Jayakumar, K.

    2015-06-01

    The Coulomb interaction of holes in a Semimagnetic Cd1-xMnxTe / CdTe Spherical and Cubical Quantum Dot (SMQD) in a magnetic field is studied using variational approach in the effective mass approximation. Since these holes in QD show a pronounced collective behavior, while distinct single particle phenomena is suppressed, their interaction in confined potential becomes very significant. It has been observed that acceptor-acceptor interaction is more in cubical QD than in spherical QD which can be controlled by the magnetic field. The results are presented and discussed.

  10. Density functional description of Coulomb blockade: Adiabatic versus dynamic exchange correlation

    NASA Astrophysics Data System (ADS)

    Liu, Zhen-Fei; Burke, Kieron

    2015-06-01

    Above the Kondo temperature, the Kohn-Sham zero-bias conductance of an Anderson junction has been shown to completely miss the Coulomb blockade. Within a standard model for the spectral function, we deduce a parametrization for both the on-site exchange-correlation potential and the bias drop as a function of the site occupation that applies for all correlation strengths. We use our results to sow doubt about the common interpretation of such corrections as arising from dynamical exchange-correlation contributions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  12. Virial expansions and augmented van der Waals approach: Application to Lennard-Jones-like Yukawa fluid

    E-print Network

    A. Trokhymchuk; R. Melnyk; I. Nezbeda

    2015-04-03

    We argue that recently proposed [Melnyk et al., Fluid Phase Equilibr., 2009, Vol. 279, 1] a criterion to split the pair interaction energy into two parts, one of which is forced to be responsible the most accurate as possible for excluded volume energy in the system, results in expressions for the virial coefficients that improve the performance of the virial equation of state in general, and at subcritical temperatures, in particular. As an example, application to the Lennard-Jones-like hard-core attractive Yukawa fluid is discussed.

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

    PubMed

    Khrustalyov, Yu V; Vaulina, O S

    2012-04-01

    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

  14. Control of quantum fluctuations for a Yukawa interaction in the Kaluza Klein picture

    E-print Network

    Jean Alexandre; Konstantinos Farakos

    2006-08-29

    We study a system of fermions interacting with a scalar field, in 4+1 dimensions where the 5th dimension is compactified, using an exact functional method, where quantum fluctuations are controlled by the amplitude of the bare fermion mass. The integration of our equationsleads to the properties of the dressed Yukawa coupling, that we study at one-loop so as to show the consistency of the approach. Beyond one loop, the non-perturbative aspect of the method gives us the possibility to derive the dynamical fermion mass. The result obtained is cut off independent and this derivation proposes an alternative to the Schwinger-Dyson approach.

  15. 125 GeV Higgs boson from t- b- ? Yukawa unification

    NASA Astrophysics Data System (ADS)

    Gogoladze, Ilia; Shafi, Qaisar; Ün, Cem Salih

    2012-07-01

    We identify a class of supersymmetric SU(4) c × SU(2) L × SU(2) R models in which imposing essentially perfect t- b- ? Yukawa coupling unification at M GUT yields a mass close to 122-126 GeV for the lightest CP-even (SM-like) Higgs boson. The squark and gluino masses in these models exceed 3 TeV, but the stau and charginos in some cases can be considerably lighter. We display some benchmark points corresponding to neutralino-stau and bino-wino coannihilations as well as A-resonance. The well-known MSSM parameter tan ? is around 46-52.

  16. Two-particle truncation of Pauli--Villars-regulated Yukawa theory

    SciTech Connect

    Brodsky, Stanley J.

    2002-09-10

    We obtain analytic nonperturbative approximate solutions of Yukawa theory in the one-fermion sector using light-front quantization. The theory is regulated in the ultraviolet by the introduction of heavy Pauli-Villars scalar and fermion fields each with negative norm. In order to obtain a directly soluble problem fermion-pair creation and annihilation are neglected and the number of bosonic constituents is limited to one of either type. We discuss some of the features of the wave function of the eigensolution including its endpoint behavior and spin and orbital angular momentum content. The limit of infinite Pauli-Villars mass receives special scrutiny.

  17. Coulomb-assisted dissociative electron attachment: application to a model peptide.

    PubMed

    Sobczyk, Monika; Anusiewicz, Iwona; Berdys-Kochanska, Joanna; Sawicka, Agnieszka; Skurski, Piotr; Simons, Jack

    2005-01-13

    The fragmentation of positively charged gas-phase samples of peptides is used to infer the primary structure of such molecules. In electron capture dissociation (ECD) experiments, very low-energy electrons attach to the sample and rupture bonds to effect the fragmentation. It turns out that ECD fragmentation tends to produce cleavage of very specific types of bonds. In earlier works by this group, it has been suggested that the presence of positive charges produces stabilizing Coulomb potentials that allow low-energy electrons to exothermically attach to sigma orbitals of certain bonds and thus to cleave those bonds. In the present effort, the stabilizing effects of Coulomb potentials due to proximal positive charges are examined for a small model peptide molecule that contains a wide range of bond types. Direct attachment of an electron to the sigma orbitals of eight different bonds as well as indirect sigma bond cleavage, in which an electron first binds to a carbonyl C=O pi orbital, are examined using ab initio methods. It is found that direct attachment to and subsequent cleavage of any of the eight sigma bonds is not likely except for highly positively charged samples. It is also found that attachment to a C=O pi orbital followed by cleavage of the nitrogen-to-alpha-carbon bond is the most likely outcome. Interestingly, this bond cleavage is the one that is seen most commonly in ECD experiments. So, the results presented here seem to offer good insight into one aspect of the ECD process, and they provide a means by which one can estimate (on the basis of a simple Coulomb energy formula) which bonds may be susceptible to cleavage by low-energy electron attachment. PMID:16839114

  18. Elementary excitations and avalanches in the Coulomb glass

    NASA Astrophysics Data System (ADS)

    Palassini, Matteo; Goethe, Martin

    2012-07-01

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

  19. Weak interaction rate Coulomb corrections in big bang nucleosynthesis

    SciTech Connect

    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

    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.

  20. Andreev Reflection versus Coulomb Blockade in Hybrid Semiconductor Nanowire Devices

    NASA Astrophysics Data System (ADS)

    Doh, Yong-Joo; Franceschi, Silvano De; Bakkers, Erik P. A. M.; Kouwenhoven, Leo P.

    2008-12-01

    Semiconductor nanowires provide promising low-dimensional systems for the study of quantum transport phenomena in combination with superconductivity. Here we investigate the competition between the Coulomb blockade effect, Andreev reflection, and quantum interference, in InAs and InP nanowires connected to aluminum-based superconducting electrodes. We compare three limiting cases depending on the tunnel coupling strength and the characteristic Coulomb interaction energy. For weak coupling and large charging energy, negative differential conductance is observed as a direct consequence of the BCS density of states in the leads. For intermediate coupling and charging energy smaller than the superconducting gap, the current-voltage characteristic is dominated by Andreev reflection and Coulomb blockade produces an effect only near zero bias. For almost ideal contact transparencies and negligible charging energy, we observe universal conductance fluctuations whose amplitude is enhanced due to Andreev reflection at the contacts.

  1. Supercritical Coulomb center and excitonic instability in graphene

    E-print Network

    O. V. Gamayun; E. V. Gorbar; V. P. Gusynin

    2009-10-31

    It is well known that there are resonant states with complex energy for the supercritical Coulomb impurity in graphene. We show that opening of a quasiparticle gap decreases the imaginary part of energy, |ImE|, of these states and stabilizes the system. For gapless quasiparticles with strong Coulomb interaction in graphene, we solve the Bethe-Salpeter equation for the electron - hole bound state and show that it has a tachyonic solution for strong enough coupling \\alpha=e^2/\\kappa\\hbar v_F leading to instability of the system. In the random-phase approximation, the critical coupling is estimated to be \\alpha_c =1.62 and is an analogue of the critical charge in the Coulomb center problem. We argue that the excitonic instability should be resolved through the formation of an excitonic condensate and gap generation in the quasiparticle spectrum.

  2. On Dirac-Coulomb problem in (2+1) dimensional space-time and path integral quantization

    SciTech Connect

    Haouat, S. [L.P.Th, Departement de physique, Universite de Jijel, BP 98, Ouled Aissa, Jijel 18000 (Algeria); Chetouani, L. [Departement de Physique, Faculte de Sciences, Universite Mentouri, Route Ain El-Bey, Constantine 25000 (Algeria)

    2012-06-15

    The problem of Dirac particle interacting with Coulomb potential in (2+1) dimensions is formulated in the framework of super-symmetric path integrals where the spin degrees of freedom are described by odd Grassmannian variables. The relative propagator is expressed through Cartesian coordinates in a Hamiltonian form by the use of an adequate transformation. The passage to the polar coordinates permitted us to calculate the fixed energy Green's function and to extract bound states and associating wave functions.

  3. Quantum simulator for the Hubbard model with long-range Coulomb interactions using surface acoustic waves

    E-print Network

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

    2006-08-09

    A practical experimental scheme for a quantum simulator of strongly correlated electrons is proposed. Our scheme employs electrons confined in a two dimensional electron gas in a GaAs/AlGaAs heterojunction. Two surface acoustic waves are then induced in the GaAs substrate, which create a two dimensional ``egg-carton'' potential. The dynamics of the electrons in this potential is described by a Hubbard model with long-range Coulomb interactions. The state of the electrons in this system can be probed via its conductance and noise properties. This allows the identification of a metallic or insulating state. Numerical estimates for the parameters appearing in the effective Hubbard model are calculated using the proposed experimental system. These calculations suggest that observations of quantum phase transition phenomena of the electrons in the potential array are within experimental reach.

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

    E-print Network

    Crowell, Kelly Jean

    1990-01-01

    the Lorentz gauge Green's functions in a program written by Zheng. In the Lorentz gauge program the two-dimensional free space Green's function singularity s' = ? ln (kR, ) (113) was extracted. C. Calculation of the Far Field Given the coeificients J... Space Figures 4-6 show the current distributions obtained through the method of moments solution of (38), the Coulomb gauge MPIE for the z ? directed wire of lengths ~, ~", and 3 in free space. Each current distribution obtained through the Coulomb...

  5. Mechanical vibrations induced resonant breakdown of the Coulomb blockade

    SciTech Connect

    Pogosov, A. G.; Budantsev, M. V.; Shevyrin, A. A. [Institute of Semiconductor Physics, SB RAS, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Plotnikov, A. E.; Bakarov, A. K.; Toropov, A. I. [Institute of Semiconductor Physics, SB RAS, Novosibirsk (Russian Federation)

    2011-12-23

    Influence of forced mechanical vibrations of a suspended single-electron transistor on electron tunneling through the quantum dot limited by the Coulomb blockade is investigated. It is shown that mechanical oscillations of the quantum dot lead to the Coulomb blockade breakdown, shown in sharp resonant peaks in the transistor conductance dependence on the excitation frequency at values corresponding to the mechanical oscillations eigen modes. The observed effect is presumably connected with oscillations of the mutual electrical capacitances between the quantum dot and surrounding electrodes.

  6. Hohenberg-Kohn Theorem for Coulomb Type Systems

    E-print Network

    Aihui Zhou

    2011-08-23

    Density functional theory (DFT) has become a basic tool for the study of electronic structure of matter, in which the Hohenberg-Kohn theorem plays a fundamental role in the development of DFT. Unfortunately, the existing proofs are incomplete even incorrect; besides, the statement of the Hohenberg-Kohn theorem for many-electron Coulomb systems is not perfect. In this paper, we shall restate the Hohenberg-Kohn theorem for Coulomb type systems and present a rigorous proof by using the Fundamental Theorem of Algebra.

  7. Parity Violating Elastic Electron Scattering and Coulomb Distortions

    E-print Network

    C. J. Horowitz

    1998-01-22

    Parity violating elastic electron-nucleus scattering provides an accurate and model independent measurement of neutron densities, because the $Z^0$ couples primarily to neutrons. Coulomb distortion corrections to the parity violating asymmetry $A_l$ are calculated exactly using a relativistic optical model. Distortions significantly reduce $A_l$ in a heavy nucleus. However even with distortions, an experiment to measure the neutron radius is feasible. This will aid the interpretation of future atomic parity violation measurements and provide fundamental nuclear structure information. Coulomb distortions and small differences between neutron and proton radii could be important for a standard model test on $^4$He, $^{12}$C or $^{16}$O.

  8. Lifetime Measurements and Coulomb Excitation of Light Hg Nuclei

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

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

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

    Microsoft Academic Search

    L Blum; J A Hernando

    2002-01-01

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

  10. Properties of gravitationally equilibrated Yukawa systems—A molecular dynamics study

    SciTech Connect

    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

    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.

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

    SciTech Connect

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

    2008-11-01

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

  12. Grand Yukawonification : SO(10) grand unified theories with dynamical Yukawa couplings

    E-print Network

    Charanjit S. Aulakh; Charanjit K. Khosa

    2014-08-19

    Renormalizable SO(10) grand unified theories (GUTs), extended by $O(N_g)_F$ family gauge symmetry, generate minimal supersymmetric Standard Model flavour structure dynamically via vacuum expectation values of "Yukawon" Higgs multiplets. For concrete illustration and calculability, we work with the fully realistic minimal supersymmetric GUTs based on the $\\bf{210 \\oplus {\\overline{126}}\\oplus 126} $ GUT Higgs system - which were already parameter counting minimal relative to other realistic models. $SO(10)$ fermion Higgs channels $\\bf{{\\overline{126}},10}$($\\mathbf{120}$) extend to symmetric(antisymmetric) representations of $O(N_g)_F$, while $\\mathbf{210,126}$ are symmetric. $N_g=3$ dynamical Yukawa generation reduces the matter fermion Yukawas from 15 to 3 (21 to 5) without (with) the $\\bf{120}$ Higgs. Yukawon GUTs are thus ultraminimal in parameter counting terms. Consistent symmetry breaking is ensured by a hidden sector Bajc-Melfo(BM) superpotential with a pair of symmetric $O(N_g)$ multiplets $\\phi,S $, of which the latter's singlet part $S_s$ breaks supersymmetry and the traceless part $\\hat S $ furnishes flat directions to cancel the $O(N_g)$ D-term contributions of the visible sector. Novel dark matter candidates linked to flavour symmetry arise from both the BM sector and GUT sector minimal supersymmetric Standard Model singlet pseudo-Goldstones. These relics may be viable light($theory (NMSGUT) even sterile neutrinos can appear in certain branches of the flavour symmetry breaking without the tuning of couplings.

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

    E-print Network

    P. Gerhold

    2010-02-12

    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.

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

    SciTech Connect

    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

    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.

  15. Constituent gluons and the static quark potential

    E-print Network

    Jeff Greensite; Adam P. Szczepaniak

    2015-05-19

    We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.

  16. Constituent gluons and the static quark potential

    E-print Network

    Greensite, Jeff

    2015-01-01

    We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.

  17. Antilocalization of Coulomb Blockade in a Ge/Si Nanowire A. P. Higginbotham,1,2

    E-print Network

    Lieber, Charles M.

    in the open-wire regime places a bound on the spin-orbit length (lso extracted in the Coulomb blockade regime (lso measured independently via Coulomb blockade spectroscopy. Consistent bounds on the spin-orbit length, lso

  18. Coulomb repulsion and the electron beam directed energy weapon

    NASA Astrophysics Data System (ADS)

    Retsky, Michael W.

    2004-09-01

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

  19. Coulomb energy of uniformly charged spheroidal shell systems

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  20. Interpolating the Coulomb Phase of Little String Theory

    E-print Network

    Ying-Hsuan Lin; Shu-Heng Shao; Yifan Wang; Xi Yin

    2015-02-05

    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.

  1. Coulomb corrections to superallowed beta decay in nuclei

    E-print Network

    N. Auerbach

    2008-11-28

    Corrections to the superallowed beta decay matrix elements are evaluated in perturbation theory using the notion of the isovector monopole resonance. The calculation avoids the separation into different contributions and thus presents a consistent, systematic and more transparent approach. Explicit expressions for the Coulomb correction as a function of mass number A, are given.

  2. Coulomb repulsion and the electron beam directed energy weapon

    Microsoft Academic Search

    Michael W. Retsky

    2004-01-01

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

  3. Can Coulomb repulsion for charged particle beams be overcome?

    Microsoft Academic Search

    Michael W. Retsky

    2004-01-01

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

  4. The Coulomb three-body problem: A progress report

    SciTech Connect

    Bottcher, C.; Schultz, D.R. [Oak Ridge National Lab., TN (United States)]|[California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics

    1992-12-31

    This report discusses the following topics on the Coulomb three-body problem: model in 2D with angular momentum; new classes of orbits; pseudoperiodic orbits - heuristic quantization; semiclassical propagator - removal of caustics; calculation of quasi-bound states; and scattering theory of resonances.

  5. The Coulomb three-body problem: A progress report

    SciTech Connect

    Bottcher, C.; Schultz, D.R. (Oak Ridge National Lab., TN (United States) California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics)

    1992-01-01

    This report discusses the following topics on the Coulomb three-body problem: model in 2D with angular momentum; new classes of orbits; pseudoperiodic orbits - heuristic quantization; semiclassical propagator - removal of caustics; calculation of quasi-bound states; and scattering theory of resonances.

  6. Taming Coulomb interactions in models for ions and water

    E-print Network

    Taming Coulomb interactions in models for ions and water Jocelyn Rodgers, Zhonghan Hu and John D-bonds in water, ... #12;·Need slowly-varying u1 for good cancellation · Separate theory or simulation needed can cause artifacts · Black-box treatment of distant images prevents simple physical picture

  7. Exchange Coulomb interaction in nanotubes: Dispersion of Langmuir waves

    E-print Network

    Andreev, P A

    2015-01-01

    Microscopic derivation of the Coulomb exchange interaction for electrons located on the nanotubes is presented. Our derivation is based on the many-particle quantum hydrodynamic method. We demonstrate the role of the curvature of the nanocylinders on the force of the exchange interaction. We calculate corresponding dispersion dependencies for electron oscillations on the nanotubes.

  8. Limits to Electron Beam Emittance from Stochastic Coulomb Interactions

    SciTech Connect

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

    2008-08-22

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

  9. Interpolating the Coulomb Phase of Little String Theory

    E-print Network

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

    2015-01-01

    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.

  10. Coulomb effects on edge scattering in elastic nuclear collisions

    SciTech Connect

    Silveira, R. da; Leclercq-Willain, Ch. [Groupe de Physique Theorique, Institut de Physique Nucleaire, F-91406 Orsay Cedex (France); Physique Nucleaire Theorique et Mathematique, Code Postal 229, Universite Libre de Bruxelles, B-1050 Bruxelles (Belgium)

    2011-04-15

    We present a qualitative analysis of the effects of the Coulomb force on the edge scattering produced in elastic nuclear collisions occurring under strong absorption conditions. This analysis is illustrated with several examples of nucleus-nucleus and antiproton-nucleus elastic scattering.

  11. The structure of small molecules with the Coulomb Explosion method

    SciTech Connect

    Vager, Z.; Kanter, E.P.

    1987-01-01

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

  12. Analytic Coulomb matrix elements in a three-dimensional geometry

    E-print Network

    Jaime Zaratiegui

    2005-11-04

    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.

  13. Analytic Coulomb matrix elements in a three-dimensional geometry

    SciTech Connect

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

    2005-12-15

    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.

  14. Compact Collision Kernels for Hard Sphere and Coulomb Cross Sections; Fokker-Planck Coefficients

    SciTech Connect

    Chang Yongbin; Shizgal, Bernie D. [Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada)

    2008-12-31

    A compact collision kernel is derived for both hard sphere and Coulomb cross sections. The difference between hard sphere interaction and Coulomb interaction is characterized by a parameter {eta}. With this compact collision kernel, the calculation of Fokker-Planck coefficients can be done for both the Coulomb and hard sphere interactions. The results for arbitrary order Fokker-Planck coefficients are greatly simplified. An alternate form for the Coulomb logarithm is derived with concern to the temperature relaxation in a binary plasma.

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

    SciTech Connect

    Cleland, A.N.

    1991-04-01

    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.

  16. SOME TOPICS IN COULOMB SCATTERING. Pure and Applied Mathematics and Physics 7

    Microsoft Academic Search

    1960-01-01

    A generalization of the Born approximation, using threedimensional ; Coulomb wave functions as unperturbed solutions, is applied to a study of various ; Coulomb scattering problems. The influence of vacuum polarization on ; protonproton scattering, and relativistic Coulomb scattering of Klein-Gordon and ; Dirac particles are included. (auth);

  17. PHYSICAL REVIEW B 86, 235406 (2012) Rings and Coulomb boxes in dissipative environments

    E-print Network

    Horovitz, Baruch

    2012-01-01

    PHYSICAL REVIEW B 86, 235406 (2012) Rings and Coulomb boxes in dissipative environments Yoav of this problem to that of the Coulomb box and show that the relaxation resistance, of recent interest is quantized. We propose a Coulomb-box experiment to measure a quantized noise. DOI: 10.1103/PhysRevB.86

  18. Radiative corrections in atomic physics in the presence of perturbing potentials

    Microsoft Academic Search

    S. A. Blundell; K. T. Cheng; J. Sapirstein

    1997-01-01

    Energy shifts of radiative corrections in atoms due to perturbing potentials are calculated. The potentials considered are a constant magnetic field, the magnetic field of a nucleus, and the Coulomb interaction from other electrons in many-electron atoms.

  19. A comprehensive study of the phase diagram of symmetrical hard-core Yukawa mixtures

    NASA Astrophysics Data System (ADS)

    Caccamo, C.; Costa, D.; Pellicane, G.

    1998-09-01

    The phase diagrams of hard-core Yukawa mixtures (HCYM), constituted of equal sized hard spheres interacting through an attractive Yukawa tail, are determined by means of Gibbs Ensemble Monte Carlo (GEMC) simulations, Semi-grand Canonical Monte Carlo (SGCMC) simulations, and through the modified hypernetted-chain (MHNC) theory. Freezing lines are obtained according to an approach recently proposed by Giaquinta and co-workers [Physica A 187, 145 (1992); Phys Rev. A 45, 6966 (1992)] in which an analysis of multiparticle contributions to the excess entropy, ?s, is performed, with the determination of the ?s=0 locus. Liquid-vapor coexistence, determined through GEMC simulations, turns out to be favored when the strength ratio ? of unlike to like particle interaction, is close to 1. For lower ?'s, liquid-vapor coexistence is favored at low densities, and liquid-liquid coexistence, determined through SGCMC simulations, at high densities. The liquid-vapor binodal shifts downward in temperature and flattens when ? decreases, with a decrease of the critical temperature. At ?=0.9 a triple point can be identified from the intersection of the freezing line with the binodal line; at ?=0.7, instead, the binodal ends on the line of liquid-liquid (consolute) critical points, the intersection of the two lines thus identifying the "crossover" density and temperature between the two equilibrium regimes which correspond to the critical end point of the mixture. We find that, for not too high densities, consolute equilibrium can be also explored through GEMC simulations; the results for liquid-liquid coexistence obtained through this method and SGCMC simulations compare quite satisfactorily with each other. The trend of the liquid-vapor binodal to disappear for relatively weak unlike interactions is discussed in connection with the disappearance of liquid-vapor equilibrium which occurs in one component hard-core Yukawa fluids characterized by very short ranged attractive forces. The latter behavior has been conjectured to be relevant for the onset of crystallization in protein solutions; the implications of the present results, which are obtained in the context of a two component, albeit rough, modelization of a realistic solution, are discussed. In agreement with similar results obtained by Giaquinta et al., we finally find that the ?s=0 locus not only brings the signature of the freezing transition, but also of structural rearrangements preluding to other phase equilibria; in fact, the ?s=0 line turns out to be coincident to a high accuracy with the line of consolute critical points and with the gas branches of the liquid-vapor binodals.

  20. Higgs boson resonance parameters and the finite temperature phase transition in a chirally invariant Higgs-Yukawa model

    E-print Network

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

    2011-11-11

    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.

  1. Yukawa Monte Carlo (YMC) and Orbital Free Molecular Dynamics (OFMD) approaches for the eos of warm dense iron plasma

    Microsoft Academic Search

    Dominique Gilles; Flavien Lambert; Jean Clerouin

    2008-01-01

    Yukawa Monte Carlo and Molecular Dynamics simulations are powerful techniques extensively used to compute plasma properties such as EOS or transport coefficients, but are limited to applications where the linear electronic screening assumption is valid (1). Recently we have shown that a modified scheme using density functional theory with a Thomas-Fermi kinetic energy functional for the electrons (OFMD) may be

  2. Influence of Coulomb interaction of tunable shapes on the collective transport of ultradilute two-dimensional holes.

    PubMed

    Huang, Jian; Pfeiffer, L N; West, K W

    2014-01-24

    In high quality updoped GaAs field-effect transistors, the two-dimensional charge carrier concentrations can be tuned to very low values similar to the density of electrons on helium surfaces. An important interaction effect, screening of the Coulomb interaction by the gate, rises as a result of the large charge spacing comparable to the distance between the channel and the gate. Based on the results of the temperature (T) dependence of the resistivity from measuring four different samples, a power-law characteristic is found for charge densities ?2×10(9)??cm(-2). Moreover, the exponent exhibits a universal dependence on a single dimensionless parameter, the ratio between the mean carrier separation and the distance to the metallic gate that screens the Coulomb interaction. Thus, the electronic properties are tuned through varying the shape of the interaction potential. PMID:24484159

  3. Two dimensional graphene nanogenerator by coulomb dragging: Moving van der Waals heterostructure

    NASA Astrophysics Data System (ADS)

    Zhong, Huikai; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan; Chen, Hongsheng; Lin, Shisheng

    2015-06-01

    Harvesting energy from environment is the current focus of scientific community. Here, we demonstrate a graphene nanogenerator, which is based on moving van der Waals heterostructure formed between graphene and two dimensional (2D) graphene oxide (GO). This nanogenerator can convert mechanical energy into electricity with a voltage output of around 10 mV. Systematic experiments reveal the generated electricity originates from the coulomb interaction induced momentum transfer between 2D GO and holes in graphene. 2D boron nitride was also demonstrated to be effective in the framework of moving van der Waals heterostructure nanogenerator. This investigation of nanogenerator based on the interaction between 2D macromolecule materials will be important to understand the origin of the flow-induced potential in nanomaterials and may have great potential in practical applications.

  4. Testing the critical Coulomb wedge theory on hyper-extended rifted margins

    NASA Astrophysics Data System (ADS)

    Nirrengarten, Michael; Manatschal, Gianreto; Kusznir, Nick

    2015-04-01

    Deformation of hyper-extended continental crust and its relationship with the underlying mantle is a key process in the evolution of rifted margins. Recent studies have focused on hyper-extension in rifted margins using different approaches such as numerical modelling, seismic interpretation, potential field methods and field observations. However many fundamental questions about the observed structures and their evolution during the formation of hyper-extended margins are still debated. In this study an observation driven approach has been used to characterise geometrical and physical attributes of the continental crust termination, considered as a hyper-extended wedge, in order to test the applicability of critical Coulomb wedge theory to hyper-extended margins. The Coulomb wedge theory was first developed on accretionary prisms and on fold and thrust belts, but it has also been applied in extensional settings. Coulomb wedge theory explains the evolution of the critical aperture angle of the wedge as a function of basal sliding without deformation in the overlying wedge. This critical angle depends on the frictional parameters of the material, the basal friction, the surface slope, the basal dip and the fluid pressure. If the evolution of hyper-extended wedges could be described by the critical Coulomb wedge theory, it would have a major impact in the understanding of the structural and physical evolution of rifted domains during the hyper-extension processes. On seismic reflection lines imaging magma-poor hyper-extended margins, the continental crust termination is often shown to form a hyper-extended wedge. ODP Sites 1067, 900 and 1068 on the Iberian margin as well as field observations in the Alps give direct access to the rocks forming the hyper-extended wedge, which are typically composed of highly deformed and hydrated continental rocks underlain by serpentinised mantle. The boundary between the hydrated continental and mantle rocks corresponds to a decollement level. In order to test the critical Coulomb wedge theory on hyper-extended magma-poor rifted margins, we have analysed a number of high quality seismic sections from present-day margins (e.g Iberia, Newfoundland, Porcupine, Angola, Brazil, South China Sea). We have measured, in the brittle hyper-extended crust, the wedge angles (?) of the top-basement surface and the basal dip angle (?) of the crust-mantle interface. Preliminary results from this analysis show that the hyper-extended wedge aperture angle (?+?) ranges between 4° and 18°. Most hyper-extended wedges on the footwall of the detachment (lower plate margin) present aperture angles around 10-11° whereas aperture angles in the hanging-wall are more scattered. This observed difference may be linked to the direction of the basal shear in the conjugate wedges. While the applicability to hyper-extended rifted margins of critical Coulomb wedge physics has to be numerically tested, initial results suggest a promising new approach to investigate the hyper-extension processes.

  5. Coseismic Coulomb stress changes caused by the Mw6.9 Yutian earthquake in 2014 and its correlation to the 2008 Mw7.2 Yutian earthquake

    NASA Astrophysics Data System (ADS)

    Li, Yujiang; Chen, Lianwang; Liu, Shaofeng; Yang, Shuxin; Yang, Xingyue; Zhang, Guangwei

    2015-06-01

    A three-dimensional viscoelastic finite element model of the Qinghai-Tibet Plateau and its adjacent regions was used to explore the relationship between the Mw7.2 Yutian earthquake in 2008 and the 2014 Mw6.9 Yutian earthquake. We further analyzed the Coulomb failure stress change caused by the Yutian Mw6.9 earthquake on faults surrounding the Bayan Har block and discussed the relationship between the Coulomb stress change and aftershock distribution. The preliminary results showed that: (1) The Coulomb failure stress change caused by the Mw7.2 Yutian earthquake in 2008, which was projected on the slip direction of the 2014 Yutian Mw6.9 earthquake, exceeded the earthquake triggering threshold of 0.01 MPa, implying an apparent triggering effect. Specifically, the coseismic Coulomb failure stress changes were 0.0167 MPa and 0.0170 MPa when assuming apparent friction coefficients of 0.4 and 0.6, respectively. The Coulomb failure stress changes, including viscoelastic relaxation effects, were 0.0187 MPa and 0.0194 MPa respectively. Combined with the tectonic stressing rate, the Mw6.9 Yutian earthquake in 2014 was advanced 21.4-24.9 years by the 2008 Mw7.2 Yutian earthquake; (2) The stress changes derived from the viscoelastic relaxation effect were much less than that from the coseismic effect, which was possibly interpreted as the shorter elapsed time between the two earthquakes relative to the characteristic time; (3) The Coulomb failure stresses increased on the mid-northern segment of the Altyn Tagh fault, the middle segment of the Mani-Yushu fault and the western segment of the eastern Kunlun fault, which demonstrated increasing seismic potential. In particular, the Coulomb failure stress on the middle segment of the Altyn Tagh fault increased by 2.8 × 103 Pa, the most significant increase. In contrast, the Coulomb failure stress decreased on the western segment of the Mani-Yushu and Minjiang faults, with the western segment of the Mani-Yushu fault dropping by 3.6 × 103 Pa. The Coulomb stress changes on most faults surrounding the Bayan Har block were calculated to have increased, while the Minjiang fault on the eastern boundary was inhabited due to the enhancement of coseismic compressive stresses; (4) Combining the relocation of the aftershock sequence with the coseismic failure stress change, we concluded that the Mw6.9 Yutian main-shock triggered the aftershock sequences.

  6. Potential scattering in atomic physics

    Microsoft Academic Search

    P. G. Burke; Robert St John

    1977-01-01

    An in-depth examination of potential field scattering of particles is presented with particular reference to elastic electron scattering by an ion or a neutral atom. Included are scattering by a short-range, Coulomb, and spin--orbit potentials, and by one-electron atoms, low energy effective-range theory, bound states and resonances, variational methods and bound principles, integral equation methods and the Born approximation, and

  7. Implications of R parity violating Yukawa couplings in ?S=1 semileptonic decays of K mesons

    NASA Astrophysics Data System (ADS)

    Mir, Azeem; Tahir, Farida; Haseeb, Mahnaz Q.; Ahmed, Kamaluddin

    2007-12-01

    We present a class of constraints on products and combinations of Yukawa couplings for R parity violating (R?p) and lepton flavor conserving as well as violating semileptonic decays of K mesons into light pseudoscalar mesons along with two charged leptons at 1? and 2? levels. We compare the constraints obtained by semileptonic rare decays with pure leptonic rare decays and find that most of these bounds are now improved over the existing ones. We also study the forward-backward asymmetry in the decays of K+??+l+l- (l=e and ?) in the absence of tensor terms. The asymmetry is found to be up to O(10-3) (O(10-1)) for the electron and muon modes, respectively. The asymmetry is found to be as large as O(10-1) in the case of K+??+?+?-.

  8. Exploring the Yukawa unified minimal supergravity model at the Tevatron, LEP II, and the LHC

    E-print Network

    Gunion, J F

    1994-01-01

    We explore the prospects for detection of sparticles and Higgs bosons at the Tevatron, LEP-200 and the LHC in the allowed parameter space of a "Yukawa unified" ($\\lambda_b(M_U)=\\lambda_{\\ tau}(M_U)$) minimal supergravity (YUMS) model, where the only non-zero unification scale soft-SUSY-breaking terms are a universal gaugino mass and a Higgs mixing term. In a bottom-up approach, just two weak scale parameters, $\\tanb$ and $\\mha$ (along with the sign of the Higgs mixing parameter $\\mu$) completely parameterize the model. Many interesting "special" situations regarding sparticle and Higgs discovery arise, such as the importance of the invisible $\\hl\\rta\\cnone\\cnone,\\snu\\ snubar$ decay modes.

  9. Four-zero neutrino Yukawa textures in the minimal seesaw framework

    SciTech Connect

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

    2008-03-01

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

  10. Two-Yukawa fluid at a hard wall: Field theory treatment

    NASA Astrophysics Data System (ADS)

    Kravtsiv, I.; Patsahan, T.; Holovko, M.; di Caprio, D.

    2015-05-01

    We apply a field-theoretical approach to study the structure and thermodynamics of a two-Yukawa fluid confined by a hard wall. We derive mean field equations allowing for numerical evaluation of the density profile which is compared to analytical estimations. Beyond the mean field approximation, analytical expressions for the free energy, the pressure, and the correlation function are derived. Subsequently, contributions to the density profile and the adsorption coefficient due to Gaussian fluctuations are found. Both the mean field and the fluctuation terms of the density profile are shown to satisfy the contact theorem. We further use the contact theorem to improve the Gaussian approximation for the density profile based on a better approximation for the bulk pressure. The results obtained are compared to computer simulation data.

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

    SciTech Connect

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

    2010-02-10

    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.

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

    E-print Network

    Lorenzo Iorio

    2008-11-10

    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.

  13. Fermion Masses at intermediate Tan(beta): Unification of Yukawa Determinants

    E-print Network

    F. Nesti

    2006-10-24

    In the context of the Grand Unified MSSM, we investigate the fermion mass matrices at GUT scale. We note that from the experimental mass pattern the determinants of the Yukawa matrices at this scale can be unified with good precision. Taking the unification o determinants as an hypothesis, it gives two model independent predictions that in the MSSM turns out to determine an appropriate value for the product m_d m_s and tan(beta)~7-10 in the favored range. We then review a predictive model of SU(3) flavour in the context of supersymmetric SO(10) that nicely implements this mechanism, while explaining all fermion masses and mixings at 1 sigma level, including neutrino data.

  14. Aftershock triggering by postseismic stresses: A study based on Coulomb rate-and-state models

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The spatiotemporal clustering of earthquakes is a feature of medium- and short-term seismicity, indicating that earthquakes interact. However, controversy exists about the physical mechanism behind aftershock triggering: static stress transfer and reloading by postseismic processes have been proposed as explanations. In this work, we use a Coulomb rate-and-state model to study the role of coseismic and postseismic stress changes on aftershocks and focus on two processes: creep on the main shock fault plane (afterslip) and secondary aftershock triggering by previous aftershocks. We model the seismic response to Coulomb stress changes using the Dieterich constitutive law and focus on two events: the Parkfield, Mw = 6.0, and the Tohoku, Mw = 9.0, earthquakes. We find that modeling secondary triggering systematically improves the maximum log likelihood fit of the sequences. The effect of afterslip is more subtle and difficult to assess for near-fault events, where model errors are largest. More robust conclusions can be drawn for off-fault aftershocks: following the Tohoku earthquake, afterslip promotes shallow crustal seismicity in the Fukushima region. Simple geometrical considerations indicate that afterslip-induced stress changes may have been significant on trench parallel crustal fault systems following several of the largest recorded subduction earthquakes. Moreover, the time dependence of afterslip strongly enhances its triggering potential: seismicity triggered by an instantaneous stress change decays more quickly than seismicity triggered by gradual loading, and as a result we find afterslip to be particularly important between few weeks and few months after the main shock.

  15. Coulomb Suppression of the Stellar Enhancement Factor

    SciTech Connect

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

    2008-11-07

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

  16. Quark-Monopole Potentials from Supersymmetric SL(3,R) Deformed IIB Supergravity

    E-print Network

    Changhyun Ahn

    2006-08-22

    We recompute the quark-monopole potential from supersymmetric SL(3,R) deformation of IIB supergravity background dual to deformed Coulomb branch flow of the N=4 super Yang-Mills theory. The marginal deformations strengthen the Coulombic attraction between quarks and monopoles.

  17. Orbital ice: An exact Coulomb phase on the diamond lattice

    SciTech Connect

    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

    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.

  18. Interplay of Coulomb blockade and ferroelectricity in nanosized granular materials

    NASA Astrophysics Data System (ADS)

    Udalov, O. G.; Chtchelkatchev, N. M.; Glatz, A.; Beloborodov, I. S.

    2014-02-01

    We study electron transport properties of composite ferroelectrics—materials consisting of metallic grains embedded in a ferroelectric matrix. In particular, we calculate the conductivity in a wide range of temperatures and electric fields, showing pronounced hysteretic behavior. In weak fields, electron cotunneling is the main transport mechanism. In this case, we show that the ferroelectric matrix strongly influences the transport properties through two effects: (i) the dependence of the Coulomb gap on the dielectric permittivity of the ferroelectric matrix, which in turn is controlled by temperature and external field, and (ii) the dependence of the tunneling matrix elements on the electric polarization of the ferroelectric matrix, which can be tuned by temperature and applied electric field as well. In the case of strong electric fields, the Coulomb gap is suppressed and only the second mechanism is important. Our results are important for (i) thermometers for precise temperature measurements and (ii) ferrroelectric memristors.

  19. Low-Temperature Kinetics and Dynamics with Coulomb Crystals

    NASA Astrophysics Data System (ADS)

    Heazlewood, Brianna R.; Softley, Timothy P.

    2015-04-01

    Coulomb crystals-as a source of translationally cold, highly localized ions-are being increasingly utilized in the investigation of ion-molecule reaction dynamics in the cold regime. To develop a fundamental understanding of ion-molecule reactions, and to challenge existing models that describe the rates, product branching ratios, and temperature dependence of such processes, investigators need to exercise full control over the experimental reaction parameters. This requires not only state selection of the reactants, but also control over the collision process (e.g., the collisional energy and angular momentum) and state-selective product detection. The combination of Coulomb crystals in ion traps with cold neutral-molecule sources is enabling the measurement of state-selective reaction rates in a diverse range of systems. With the development of appropriate product detection techniques, we are moving toward the ultimate goal of examining low-energy, state-to-state ion-molecule reaction dynamics.

  20. Intermolecular coulomb decay at weakly coupled heterogeneous interfaces.

    PubMed

    Grieves, Gregory A; Orlando, Thomas M

    2011-07-01

    Surface ejection of H(+)(H(2)O)(n=1-8) from low energy electron irradiated water clusters adsorbed on graphite and graphite with overlayers of Ar, Kr or Xe results from intermolecular Coulomb decay (ICD) at the mixed interface. Inner valence holes in water (2a(1)(-1)), Ar (3s(-1)), Kr (4s(-1)), and Xe (5s(-1)) correlate with the cluster appearance thresholds and initiate ICD. Proton transfer occurs during or immediately after ICD and the resultant Coulomb explosion leads to H(+)(H(2)O)(n=1-8) desorption with kinetic energies that vary with initiating state, final state, and interatomic or molecular distances. PMID:21797555

  1. Cooling of cryogenic electron bilayers via the Coulomb interaction

    E-print Network

    John King Gamble; Mark Friesen; Robert Joynt; S. N. Coppersmith

    2011-04-13

    Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

  2. Silicon-based Coulomb blockade thermometer with Schottky barriers

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  3. Low-temperature kinetics and dynamics with Coulomb crystals.

    PubMed

    Heazlewood, Brianna R; Softley, Timothy P

    2015-04-01

    Coulomb crystals-as a source of translationally cold, highly localized ions-are being increasingly utilized in the investigation of ion-molecule reaction dynamics in the cold regime. To develop a fundamental understanding of ion-molecule reactions, and to challenge existing models that describe the rates, product branching ratios, and temperature dependence of such processes, investigators need to exercise full control over the experimental reaction parameters. This requires not only state selection of the reactants, but also control over the collision process (e.g., the collisional energy and angular momentum) and state-selective product detection. The combination of Coulomb crystals in ion traps with cold neutral-molecule sources is enabling the measurement of state-selective reaction rates in a diverse range of systems. With the development of appropriate product detection techniques, we are moving toward the ultimate goal of examining low-energy, state-to-state ion-molecule reaction dynamics. PMID:25594853

  4. Cooling of cryogenic electron bilayers via the Coulomb interaction

    E-print Network

    Gamble, John King; Joynt, Robert; Coppersmith, S N

    2011-01-01

    Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby, cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure, and analyze the power transfer. We show that across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

  5. Cooling of cryogenic electron bilayers via the Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Gamble, John King; Friesen, Mark; Joynt, Robert; Coppersmith, S. N.

    2011-09-01

    Heat dissipation in current-carrying cryogenic nanostructures is problematic because the phonon density of states decreases strongly as energy decreases. We show that the Coulomb interaction can prove a valuable resource for carrier cooling via coupling to a nearby cold electron reservoir. Specifically, we consider the geometry of an electron bilayer in a silicon-based heterostructure and analyze the power transfer. We show that, across a range of temperatures, separations, and sheet densities, the electron-electron interaction dominates the phonon heat-dissipation modes as the main cooling mechanism. Coulomb cooling is most effective at low densities, when phonon cooling is least effective in silicon, making it especially relevant for experiments attempting to perform coherent manipulations of single spins.

  6. Characterization of ion Coulomb crystals for fundamental sciences

    NASA Astrophysics Data System (ADS)

    Okada, Kunihiro; Ichikawa, Masanari; Wada, Michiharu

    2015-05-01

    We performed classical molecular dynamics (MD) simulations in order to search the conditions for efficient sympathetic cooling of highly charged ions (HCIs) in a linear Paul trap. Small two-component ion Coulomb crystals consisting of laser-cooled ions and HCIs were characterized by the results of the MD simulations. We found that the spatial distribution is determined by not only the charge-to-mass ratio but also the space charge effect. Moreover, the simulation results suggest that the temperature of HCIs do not necessarily decrease with increasing the number of laser-cooled ions in the cases of linear ion crystals. We also determined the cooling limit of sympathetically cooled 165Ho14+ ions in small linear ion Coulomb crystals. The present results show that sub-milli-Kelvin temperatures of at least 10 Ho14+ ions will be achieved by sympathetic cooling with a single laser-cooled Be+.

  7. Coulomb effects in low-energy nuclear fragmentation

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  8. Coulomb shifts and shape changes in the mass 70 region

    E-print Network

    B. S. Nara Singh; A. N. Steer; D. G. Jenkins; R. Wadsworth; M. A. Bentley; P. J. Davies; R. Glover; N. S. Pattabiraman; C. J. Lister; T. Grahn; P. T. Greenlees; P. Jones; R. Julin; S. Juutinen; M. Leino; M. Nyman; J. Pakarinen; P. Rahkila; J. Saren; C. Scholey; J. Sorri; J. Uusitalo; P. A. Butler; M. Dimmock; D. T. Joss; J. Thomson; B. Cederwall; B. Hadinia; M. Sandzelius

    2007-06-22

    The technique of recoil beta tagging has been developed which allows prompt gamma decays in nuclei from excited states to be correlated with electrons from their subsequent short-lived beta decay. This technique is ideal for studying nuclei very far from stability and improves in sensitivity for very short-lived decays and for high decay Q-values. The method has allowed excited states in 78Y to be observed for the first time, as well as an extension in the knowledge of T=1 states in 74Rb. From this new information it has been possible to compare Coulomb energy differences (CED) between T=1 states in 70Br/70Se, 74Rb/74Kr, and 78Y/78Sr. The A=70 CED exhibit an anomalous behavior which is inconsistent with all other known CED. This behavior may be accounted for qualitatively in terms of small variations in the Coulomb energy arising from shape changes.

  9. Stability characterizations of fixtured rigid bodies with Coulomb friction

    SciTech Connect

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

    2000-02-15

    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.

  10. Fractional describing function of systems with Coulomb friction

    Microsoft Academic Search

    Fernando B. Duarte; J. Tenreiro Machado

    2009-01-01

    This paper studies the describing function (DF) of systems constituted by a mass subjected to nonlinear friction. The friction\\u000a force is decomposed into two components, namely, the viscous and the Coulomb friction. The system dynamics is analyzed in\\u000a the DF perspective revealing a fractional-order behavior. The reliability of the DF method is evaluated through the signal\\u000a harmonic contents.

  11. Screened Coulomb interaction in the maximally localized Wannier basis

    Microsoft Academic Search

    Takashi Miyake; F. Aryasetiawan

    2008-01-01

    We discuss a maximally localized Wannier function approach for constructing lattice models from first-principles electronic structure calculations, where the effective Coulomb interactions are calculated in the constrained random-phase approximation. The method is applied to the 3d transition metals and a perovskite (SrVO3) . We also optimize the Wannier functions by unitary transformation so that U is maximized. Such Wannier functions

  12. Coulomb interaction from the interplay between confinement and screening

    NASA Astrophysics Data System (ADS)

    Gaete, P.; Guendelman, E. I.

    2004-07-01

    It has been noticed that confinement effects can be described by the addition of a -F??aFa?? term in the Lagrangian density. We now study the combined effect of such "confinement term" and that of a mass term. The surprising result is that the interplay between these two terms gives rise to a Coulomb interaction. Our picture has a certain correspondence with the quasiconfinement picture described by Giles, Jaffe and de Rujula for QCD with symmetry breaking.

  13. Coulomb Damped Relaxation Oscillations in Semiconductor Quantum Dot Lasers

    Microsoft Academic Search

    Ermin Malic; Moritz J. P. Bormann; P. Hovel; M. Kuntz; D. Bimberg; Andreas Knorr; Eckehard Scholl

    2007-01-01

    We present a theoretical simulation of the turn-on dynamics of InAs\\/GaAs quantum dot semiconductor lasers driven by electrical current pulses. Our approach goes beyond standard phenomenological rate equations. It contains microscopically calculated Coulomb scattering rates, which describe Auger transitions between quantum dots and the wetting layer. In agreement with the experimental results, we predict a strong damping of relaxation oscillations

  14. Special issue on new developments in strongly coupled Coulomb systems

    Microsoft Academic Search

    2008-01-01

    This is a call for contributions to a special issue of Journal of Physics A: Mathematical and Theoretical dedicated to the subject of the `International Conference on Strongly Coupled Coulomb Systems (SCCS)', 29 July–2 August 2008, Camerino, Italy (http:\\/\\/sccs2008.df.unicam.it\\/). Participants of that meeting, as well as other scientists working in the field, are invited to submit a research paper to

  15. Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study

    Microsoft Academic Search

    Anders Mathias Lunde; Karsten Flensberg; Antti-Pekka Jauho

    2005-01-01

    We calculate the intershell resistance R21 in a multiwall carbon nanotube as a function of temperature T and Fermi level ?F (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I1 in one shell induces a voltage drop V2 in another shell by the

  16. Molecular Dynamics Simulation of Shear Moduli for Coulomb Crystals

    E-print Network

    C. J. Horowitz; J. Hughto

    2008-12-15

    Torsional (shear) oscillations of neutron stars may have been observed in quasiperiodic oscillations of Magnetar Giant Flares. The frequencies of these modes depend on the shear modulus of neutron star crust. We calculate the shear modulus of Coulomb crystals from molecular dynamics simulations. We find that electron screening reduces the shear modulus by about 10% compared to previous Ogata et al. results. Our MD simulations can be extended to calculate the effects of impurities and or polycrystalline structures on the shear modulus.

  17. Can Coulomb repulsion for charged particle beams be overcome?

    NASA Astrophysics Data System (ADS)

    Retsky, Michael W.

    2004-01-01

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

  18. Colossal Coulomb Drag in Double Bilayer Graphene Heterostructures

    NASA Astrophysics Data System (ADS)

    Lee, Kayoung; Xue, Jaimin; Taniguchi, Takashi; Watanabe, Kenji; Tutuc, Emanuel

    2015-03-01

    Double-layer electron systems, where charge carriers are apart into two parallel layers, have been of interest thanks to their various interlayer interaction phenomena. One of the peculiar interaction features is Coulomb drag, in which current flowing in one layer (drive layer) induces voltage drop in the opposite layer (drag layer) via interlayer momentum transfer. Recent progress in the fabrication of heterostructures consisting of atomic layer materials such as graphene and hexagonal boron nitride (hBN) has led to high mobility double layer systems. Here we probe Coulomb drag in double bilayer graphene heterostructures separated by 2 - 5 nm thick hBN dielectrics. At temperatures (T) lower than 30 K, we observe an anomalous Coulomb drag in the vicinity of the drag layer charge neutrality points, which increases as T is reduced. At T = 1.4 K, the lowest temperature studied here, the drag resistivity becomes comparable to the layer resistivity at a finite drag layer density ndrag ~ 1 - 4 1011 cm-2. The ratio of the drag to layer resistivity increases as the hBN thickness reduces, and also as the drag layer mobility increases. At T >50K, we observe diffusive drag, which increases with T. We thank ONR, NRI and Intel for support.

  19. Intershell resistance in multiwall carbon nanotubes: A Coulomb drag study

    NASA Astrophysics Data System (ADS)

    Lunde, Anders Mathias; Flensberg, Karsten; Jauho, Antti-Pekka

    2005-03-01

    We calculate the intershell resistance R21 in a multiwall carbon nanotube as a function of temperature T and Fermi level ?F (e.g., a gate voltage), varying the chirality of the inner and outer tubes. This is done in a so-called Coulomb drag setup, where a current I1 in one shell induces a voltage drop V2 in another shell by the screened Coulomb interaction between the shells neglecting the intershell tunneling. We provide benchmark results for R21=V2/I1 within the Fermi liquid theory using Boltzmann equations. The band structure gives rise to strongly chirality-dependent suppression effects for the Coulomb drag between different tubes due to selection rules combined with mismatching of wave vector and crystal angular momentum conservation near the Fermi level. This gives rise to orders of magnitude changes in R21 and even the sign of R21 can change depending on the chirality of the inner and outer tube and misalignment of inner and outer tube Fermi levels. However for any tube combination, we predict a dip (or peak) in R21 as a function of gate voltage, since R21 vanishes at the electron-hole symmetry point. As a by-product, we classified all metallic tubes into either zigzaglike or armchairlike, which have two different nonzero crystal angular momenta ma , mb and only zero angular momentum, respectively.

  20. Exponential representation in the Coulomb three-body problem

    NASA Astrophysics Data System (ADS)

    Frolov, Alexei M.; Smith, Vedene H., Jr.

    2004-07-01

    The exponential representation in the Coulomb three-body problem is considered. It is shown that the exponential variational expansion in relative coordinates r32, r31 and r21 has a number of advantages for the bound state calculations in Coulomb three-body systems. Moreover, it appears that the exponential (or Laplace-Fourier) representation of the Coulomb three-body problem is an optimal approach to analyse and solve various three-body problems. The optimization of nonlinear parameters in the trial wavefunctions is also considered. The developed methods are used to determine the highly accurate ground 11S(L = 0)-state energies and other bound state properties for a number of He-like two-electron ions (Li+, Be2+, B3+, C4+, N5+, O6+, F7+ and Ne8+). To represent the ground state energies of these He-like ions we apply the Z-1 expansion. The asymptotic form of the ground state wavefunctions at large electron-nuclear distances for the He-like ions is briefly discussed. Considered hypervirial theorems are of great interest for these ions, since they allow one to obtain some useful relations between different expectation values. The generalization of the exponential variational expansion in relative coordinates to the four-body non-relativistic systems is also considered.

  1. Coulomb effects and hopping transport in granular metals

    NASA Astrophysics Data System (ADS)

    Beloborodov, I. S.; Lopatin, A. V.; Vinokur, V. M.

    2005-09-01

    We investigate effects of Coulomb interaction and hopping transport in the insulator phase of granular metals and quantum dot arrays considering both spatially periodic as well as irregular grain or dot arraignments. We study the Mott transition between the insulating and metallic phases in a strictly periodic system and find the dependence of the Mott gap on the intergranular coupling. In this case the conductivity of the insulating state has the activation form with the Mott gap entering the exponent. In the irregular arrays the electrostatic disorder induces the finite density of states near the Fermi level giving rise to the variable range hopping conductivity. We derive the transport properties of the irregular array in the dielectric, low coupling limit and show that the conductivity follows the Efros-Shklovskii law. We develop a theory of tunneling through a chain of grains and discuss in detail both elastic and inelastic cotunneling mechanisms; the former dominates at very low temperatures and very low applied electric fields, while the inelastic mechanism controls tunneling at high temperature or fields. Our results are obtained within the framework of the technique based on the mapping of the quantum electronic problem onto the classical gas of Coulomb charges. The processes of quantum tunneling of real electrons are represented in this technique as trajectories (world lines) of charged classical particles in d+1 dimensions. The Mott gap is related to the dielectric susceptibility of the Coulomb gas in the direction of the imaginary time axis.

  2. Dynamical approach to heavy-ion induced fission using actinide target nuclei at energies around the Coulomb barrier

    E-print Network

    Y. Aritomo; K. Hagino; K. Nishio; S. Chiba

    2012-03-12

    In order to describe heavy-ion fusion reactions around the Coulomb barrier with an actinide target nucleus, we propose a model which combines the coupled-channels approach and a fluctuation-dissipation model for dynamical calculations. This model takes into account couplings to the collective states of the interacting nuclei in the penetration of the Coulomb barrier and the subsequent dynamical evolution of a nuclear shape from the contact configuration. In the fluctuation-dissipation model with a Langevin equation, the effect of nuclear orientation at the initial impact on the prolately deformed target nucleus is considered. Fusion-fission, quasi-fission and deep quasi-fission are separated as different Langevin trajectories on the potential energy surface. Using this model, we analyze the experimental data for the mass distribution of fission fragments (MDFF) in the reactions of $^{34,36}$S+$^{238}$U and $^{30}$Si+$^{238}$U at several incident energies around the Coulomb barrier. We find that the time scale in the quasi-fission as well as the deformation of fission fragments at the scission point are different between the $^{30}$Si+$^{238}$U and $^{36}$S+$^{238}$U systems, causing different mass asymmetries of the quasi-fission.

  3. Should Coulomb stress change calculations be used to forecast aftershocks and to influence earthquake probability estimates? (Invited)

    NASA Astrophysics Data System (ADS)

    Parsons, T.

    2009-12-01

    After a large earthquake, our concern immediately moves to the likelihood that another large shock could be triggered, threatening an already weakened building stock. A key question is whether it is best to map out Coulomb stress change calculations shortly after mainshocks to potentially highlight the most likely aftershock locations, or whether it is more prudent to wait until the best information is available. It has been shown repeatedly that spatial aftershock patterns can be matched with Coulomb stress change calculations a year or more after mainshocks. However, with the onset of rapid source slip model determinations, the method has produced encouraging results like the M=8.7 earthquake that was forecast using stress change calculations from 2004 great Sumatra earthquake by McCloskey et al. [2005]. Here, I look back at two additional prospective calculations published shortly after the 2005 M=7.6 Kashmir and 2008 M=8.0 Wenchuan earthquakes. With the benefit of 1.5-4 years of additional seismicity, it is possible to assess the performance of rapid Coulomb stress change calculations. In the second part of the talk, within the context of the ongoing Working Group on California Earthquake Probabilities (WGCEP) assessments, uncertainties associated with time-dependent probability calculations are convolved with uncertainties inherent to Coulomb stress change calculations to assess the strength of signal necessary for a physics-based calculation to merit consideration into a formal earthquake forecast. Conclusions are as follows: (1) subsequent aftershock occurrence shows that prospective static stress change calculations both for Kashmir and Wenchuan examples failed to adequately predict the spatial post-mainshock earthquake distributions. (2) For a San Andreas fault example with relatively well-understood recurrence, a static stress change on the order of 30 to 40 times the annual stressing rate would be required to cause a significant (90%) perturbation to the distribution of allowable 30-year time-dependent probability results.

  4. Bridging interactions due to telechelic linkers balanced by screened Coulombic repulsions

    NASA Astrophysics Data System (ADS)

    Porte, Grégoire; Ligoure, Christian; Appell, Jacqueline; Aznar, Raymond

    2006-05-01

    When telechelic polymers (poly-ethyleneoxide grafted at both ends with an aliphatic chain) are added to a microemulsion of decane droplets in water stabilized by a surfactant film they can link the droplets and thus introduce an effective attractive interaction between the droplets, eventually leading to a phase separation. Starting from a neutral microemulsion we show that this attractive interaction can be offset by adding minute quantities of an ionic surfactant, thus introducing a repulsive Coulombic interaction. This opens up the possibility of 'weighting' an unknown effective attraction against a well known repulsion. The phase behaviour and the small angle neutron scattering spectra of different samples illustrate this point. The spectra are simulated assuming the interaction potentials to be the sum of attractive and repulsive contributions and a good agreement is found between the experimental and simulated spectra in the neutral microemulsion, in the charged microemulsion and in the charged and connected microemulsion.

  5. Effective field theory of gravity: Leading quantum gravitational corrections to Newton's and Coulomb's laws

    SciTech Connect

    Faller, Sven [Theoretische Physik 1, Fachbereich Physik, Universitaet Siegen, D-57068 Siegen (Germany)

    2008-06-15

    In this paper we consider general relativity and its combination with scalar quantum electrodynamics (QED) as an effective quantum field theory at energies well below the Planck scale. This enables us to compute the one-loop quantum corrections to the Newton and Coulomb potentials induced by the combination of graviton and photon fluctuations. We derive the relevant Feynman rules and compute the nonanalytical contributions to the one-loop scattering matrix for charged scalars in the nonrelativistic limit. In particular, we derive the post-Newtonian corrections of order Gm/c{sup 2}r from general relativity and the genuine quantum corrections of order G({Dirac_h}/2{pi})/c{sup 3}r{sup 2}.

  6. Topological defect formation and spontaneous symmetry breaking in ion Coulomb crystals

    NASA Astrophysics Data System (ADS)

    Pyka, K.; Keller, J.; Partner, H. L.; Nigmatullin, R.; Burgermeister, T.; Meier, D. M.; Kuhlmann, K.; Retzker, A.; Plenio, M. B.; Zurek, W. H.; Del Campo, A.; Mehlstäubler, T. E.

    2013-08-01

    Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry state independently. Where such local choices are incompatible, topological defects can form. The Kibble-Zurek mechanism predicts the defect densities to follow a power law that scales with the rate of the transition. Owing to its ubiquitous nature, this theory finds application in a wide field of systems ranging from cosmology to condensed matter. Here we present the successful creation of defects in ion Coulomb crystals by a controlled quench of the confining potential, and observe an enhanced power law scaling in accordance with numerical simulations and recent predictions. This simple system with well-defined critical exponents opens up ways to investigate the physics of non-equilibrium dynamics from the classical to the quantum regime.

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

    SciTech Connect

    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

    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.

  8. The effect of magnetic field on the structure of Coulomb crystal in dusty plasma

    SciTech Connect

    Baruah, Swati; Das, Nilakshi [Department of Physics, Tezpur University, Tezpur, 784028 Assam (India)

    2010-07-15

    A molecular dynamics code is developed to study the formation of dust crystal and phase transition of a three-dimensional dusty plasma system in the presence of magnetic field. Under the influence of the magnetic field, the interaction potential among the grains gets modified and becomes anisotropic. The pair correlation function has been calculated to characterize the structural properties of the dusty plasma for different values of magnetic field strength. The phase diagram in the GAMMA-kappa plane is plotted for the system for different values of magnetic field strength. This diagram shows the existence of three phases: solid (fcc-like), solid (bcc-like), and fluid phases. It is seen that as the value of the magnetic field gets higher, the triple point shifts toward the lower value of the screening constant but higher value of Coulomb coupling parameter.

  9. Fermi and Coulomb correlated relativistic local-density method for atoms

    NASA Astrophysics Data System (ADS)

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

    1989-12-01

    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.

  10. Understanding the influence of Coulomb and dispersion interactions on the wetting behavior of ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-11-01

    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

  11. Upper and lower Higgs boson mass bounds from a lattice Higgs-Yukawa model with dynamical overlap fermions

    E-print Network

    P. Gerhold; K. Jansen

    2009-12-02

    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.

  12. Fano effect dominance over Coulomb blockade in transport properties of parallel coupled quantum dot system

    NASA Astrophysics Data System (ADS)

    Brogi, Bharat Bhushan; Chand, Shyam; Ahluwalia, P. K.

    2015-06-01

    Theoretical study of the Coulomb blockade effect on transport properties (Transmission Probability and I-V characteristics) for varied configuration of coupled quantum dot system has been studied by using Non Equilibrium Green Function(NEGF) formalism and Equation of Motion(EOM) method in the presence of magnetic flux. The self consistent approach and intra-dot Coulomb interaction is being taken into account. As the key parameters of the coupled quantum dot system such as dot-lead coupling, inter-dot tunneling and magnetic flux threading through the system can be tuned, the effect of asymmetry parameter and magnetic flux on this tuning is being explored in Coulomb blockade regime. The presence of the Coulomb blockade due to on-dot Coulomb interaction decreases the width of transmission peak at energy level ? + U and by adjusting the magnetic flux the swapping effect in the Fano peaks in asymmetric and symmetric parallel configuration sustains despite strong Coulomb blockade effect.

  13. Two-Boson Truncation of Pauli-Villars-RegulatedYukawa Theory

    SciTech Connect

    Brodsky, Stanley J.; /SLAC; Hiller, John R.; /Minnesota U., Duluth; McCartor, Gary; /Southern Methodist U.; ,

    2005-09-01

    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{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.

  14. Phase equilibria and interfacial properties of two-dimensional Yukawa fluids

    E-print Network

    G. A. Méndez-Maldonado; M. González-Melchor; J. Alejandre

    2012-07-13

    Molecular dynamics simulations of two-dimensional soft Yukawa fluids are performed to analyze the effect that the range of interaction has on coexisting densities and line tension. The attractive one-component fluid and equimolar mixtures containing positive and negative particles are studied at different temperatures to locate the region where the vapor-solid and vapor-liquid phases are stable. When the range of interaction decreases, the critical temperature of the attractive one-component systems decreases. However, for the charged mixtures it increases, and this opposite behaviour is understood in terms of the repulsive interactions which are dominant for these systems. The stable phase diagram of two-dimensional fluids is defined for smaller values of the decay parameter \\lambda\\ than that of fluids in three dimensions. The two-dimensional attractive one-component fluid has stable liquid-vapor phase diagram for values of \\lambda<3, in contrast to the three-dimensional case, where stability has been observed even for values of \\lambda<15. The same trend is observed in equimolar mixtures of particles carrying opposite charges.

  15. Corresponding states law for a generalized Lennard-Jones potential.

    PubMed

    Orea, P; Romero-Martínez, A; Basurto, E; Vargas, C A; Odriozola, G

    2015-07-14

    It was recently shown that vapor-liquid coexistence densities derived from Mie and Yukawa models collapse to define a single master curve when represented against the difference between the reduced second virial coefficient at the corresponding temperature and that at the critical point. In this work, we further test this proposal for another generalization of the Lennard-Jones pair potential. This is carried out for vapor-liquid coexistence densities, surface tension, and vapor pressure, along a temperature window set below the critical point. For this purpose, we perform molecular dynamics simulations by varying the potential softness parameter to produce from very short to intermediate attractive ranges. We observed all properties to collapse and yield master curves. Moreover, the vapor-liquid curve is found to share the exact shape of the Mie and attractive Yukawa. Furthermore, the surface tension and the logarithm of the vapor pressure are linear functions of this difference of reduced second virial coefficients. PMID:26178115

  16. Conductance of molecularly linked gold nanoparticle films across an insulator-to-metal transition: From hopping to strong Coulomb electron-electron interactions and correlations

    NASA Astrophysics Data System (ADS)

    Tie, M.; Dhirani, A.-A.

    2015-04-01

    We study the influence of Coulomb effects on conductance (g ) of 1,4-butanedithiol-linked gold nanoparticle (NP) films near a percolation insulator-to-metal transition. On the insulating side, g ˜exp [-(T?/T ) 1 /2] , where T is absolute temperature, a behavior predicted by Efros-Shklovskii's theory for charges optimizing pathways that accommodate Coulomb charging barriers. On the metallic side below ˜20 K, g varies linearly with T1 /2. Such a correction to g (T =0 ) is predicted by Altshuler-Aronov's theory for Fermi liquid metals when disorder mediates electron-electron (e -e ) Coulomb interactions. Remarkably, in the present system, the T1 /2 component of g is significant compared to g (T =0 ) , and fitting to Boltzmann's transport theory yields elastic scattering lengths that are anomalously small—much smaller than the distance between atoms (Ioffe-Regel limit required for metals). Previous studies of materials such as fullerites, layered organic salts, and transition metal compounds have also reported such anomalously small scattering lengths and large T1 /2 components and attributed them to strong Coulomb mediated e -e correlations, which we believe is likely the case in the present system as well. This study highlights a potential opportunity to use molecularly linked nanoparticle films as a platform to study strongly correlated electrons in a controlled fashion.

  17. Is the Coulomb sum rule violated in nuclei?

    E-print Network

    J. Morgenstern; Z. E. Meziani

    2001-06-26

    Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on $^{40}$Ca, $^{48}$Ca, $^{56}$Fe, $^{197}$Au, $^{208}$Pb and $^{238}$U. We find that the longitudinal response function for these nuclei is "quenched" and that the Coulomb sum is not saturated, at odds with claims in the literature.

  18. Halo nuclei with the Coulomb-Sturmian basis

    E-print Network

    M. A. Caprio; P. Maris; J. P. Vary

    2014-08-30

    The rapid falloff of the oscillator functions at large radius (Gaussian asymptotics) makes them poorly suited for the description of the asymptotic properties of the nuclear wave function, a problem which becomes particularly acute for halo nuclei. We consider an alternative basis for ab initio no-core configuration interaction (NCCI) calculations, built from Coulomb-Sturmian radial functions, allowing for realistic (exponential) radial falloff. NCCI calculations are carried out for the neutron-rich He isotopes, and estimates are made for the RMS radii of the proton and neutron distributions.

  19. Conjugate Directions in Lattice Landau and Coulomb Gauge Fixing

    E-print Network

    R. J. Hudspith

    2014-12-08

    We provide details expanding on our implementation of a non-linear conjugate gradient method with Fourier acceleration for lattice Landau and Coulomb gauge fixing. We find clear improvement over the Fourier accelerated steepest descent method, with the average time taken for the algorithm to converge to a fixed, high accuracy, being reduced by a factor of 2 to 4. We show such improvement for the logarithmic definition of the gauge fields here, having already shown this to be the case for a more common definition. We also discuss the implementation of an optimal Fourier accelerated steepest descent method.

  20. Challenges in calculating molecular systems with Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Kirnosov, Nikita; Sharkey, Keeper; Adamowicz, Ludwik

    2014-03-01

    The highly accurate quantum mechanical calculations are not only crucial for high-resolution experimental data verification, but may also serve as a guide in the field of exotic systems exploration. Including all non-relativistic effects in a single-step variational approach and rigorously separating out the center of mass motion allows us to build a reliable model for calculating bound states of molecular systems with Coulomb interactions. In these calculations the wave function of the system is expanded in terms of explicitly correlated Gaussian (ECG) basis functions. Examples of calculations of energies and other properties of some molecular systems will be presented.

  1. Unsafe coulomb excitation of {sup 240-244}Pu.

    SciTech Connect

    Wiedenhoever, I.

    1998-12-01

    The high spin states of {sup 240}Pu and {sup 244}Pu have been investigated with GAMMASPHERE at ATLAS, using Coulomb excitation with a {sup 208}Pb beam at energies above the Coulomb barrier. Data on a transfer channel leading to {sup 242}Pu were obtained as well. In the case of {sup 244}Pu, the yrast band was extended to 34{h_bar}, revealing the completed {pi}i{sub 13/2} alignment, a ''first'' for actinide nuclei. The yrast sequence of {sup 242}Pu was also extended to higher spin and a similar backbend was delineated. In contrast, while the ground state band of {sup 240}Pu was measured up to the highest rotational frequencies ever reported in the actinide region ({approximately} 300 keV), no sign of particle alignment was observed. In this case, several observables such as the large B(E1)/B(E2) branching ratios in the negative parity band, and the vanishing energy staggering between the negative and positive parity bands suggest that the strength of octupole correlations increases with rotational frequency. These stronger correlations may well be responsible for delaying or suppressing the {pi}i{sub 13/2} particle alignment.

  2. Slave rotor approach to dynamically screened Coulomb interactions in solids

    NASA Astrophysics Data System (ADS)

    Krivenko, I. S.; Biermann, S.

    2015-04-01

    Recent studies of dynamical screening of the electronic Coulomb interactions in solids have revived interest in lattice models of correlated fermions coupled to bosonic degrees of freedom (Hubbard-Holstein-type models). We propose a new dynamical mean-field-based approach to dynamically screened Coulomb interactions. In the effective Anderson-Holstein model, a transformation to slave rotors [S. Florens and A. Georges, Phys. Rev. B 66, 165111 (2002), 10.1103/PhysRevB.66.165111] is performed to decouple the dynamical part of the interaction. This transformation allows for a systematic derivation and analysis of recently introduced approximate schemes for the solution of dynamical impurity problems, in particular, the Bose factor ansatz within the dynamic atomic limit approximation (DALA) with and without Lang-Firsov correction. More importantly still, it suggests an optimized choice for a Bose factor in the sense of the variational principle of Feynman and Peierls. We demonstrate the accuracy of our scheme and present a comparison to calculations within the DALA.

  3. On thermoelectric pure spin currents in Coulomb blockaded quantum dots

    NASA Astrophysics Data System (ADS)

    Buddhiraju, Siddharth; Muralidharan, Bhaskaran

    2015-03-01

    The generation of thermoelectric pure spin currents through quantum dot systems has attracted some attention in the recent years. The topic of optimizing pure thermoelectric spin current generation across Coulomb blockaded quantum dots and its utilization is the focus of this talk. While it is clear that maximal pure spin current occurs at the point of particle-hole symmetry in the non-interacting case, the situation changes considerably with the incidence of Coulomb interaction. At a high enough value of the interaction parameter U, it is seen that the maximum does not occur at the point of particle-hole symmetry as expected, but at two other points located symmetrically about it. By including normal metal contacts described by Boltzmann transport, we then discuss issues related to the utilization of the optimized pure spin currents and set the stage to discuss the relevance of the spin dependent Seebeck coefficient. We conclude by considering the important question: does the spin figure of merit relate to maximum efficiency in the same sense as in conventional thermoelectrics?

  4. Theory of rolling: Solution of the Coulomb problem

    NASA Astrophysics Data System (ADS)

    Cherepanov, G. P.

    2014-01-01

    A theory of rolling of round bodies in the normal mode with adhesion conditions satisfied on the entire contact area is proposed. This theory refines the classical Coulomb's theory of rolling in which the rolling moment is directly proportional to the pressing force (e.g., the weight of the rolling body). The rolling moment of cylinders is found to be directly proportional to the pressing force raised to a power of 3/2, and the rolling moment of balls and tori is proportional to the pressing force raised to a power of 4/3. It is shown that the normal mode of uniform rolling can only be provided for a certain ratio of the elastic constants of the materials of the round body and the base forming an ideal pair. The Coulomb problem is solved for the cases of rolling of an elastic cylinder over an elastic half-space, of an elastic ball over an elastic half-space, of an elastic torus over an elastic half-space, and of a cylinder and ball over a tightly stretched membrane. The rolling law is derived for such cases. The rolling friction coefficients, the rolling moment, and the rolling friction force are calculated.

  5. Revision of the Coulomb logarithm in the ideal plasma

    SciTech Connect

    Mulser, P., E-mail: peter.mulser@physik.tu-darmstadt.de; Alber, G. [Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany)] [Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany); Murakami, M. [ILE: Institute of Laser Engineering, Osaka University, Yamada Kami, Osaka (Japan)] [ILE: Institute of Laser Engineering, Osaka University, Yamada Kami, Osaka (Japan)

    2014-04-15

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

  6. Coulomb effects on pions produced in heavy-ion reactions

    SciTech Connect

    Sullivan, J.P.

    1981-11-01

    Double differential cross sections for the production of ..pi../sup +/ and ..pi../sup -/ near the velocity of the incident beam for pion lab angles less than 40 degrees are presented. The experimental apparatus and the techniques are discussed. Beams of /sup 20/Ne with E/A from 80 to 655 MeV and /sup 40/Ar with E/A = 535 MeV incident on Be, C, NaF, KC1, Cu, and U targets were used. A sharp peak in the ..pi../sup -/ spectrum and a depression in the ..pi../sup +/ spectrum were observed at zero degrees near the incident beam velocity. The effect is explained in terms of Coulomb interactions between the pions and fragments of the incident beam. Least squares fits to the data using the Coulomb correction formulas of Gyulassy and Kauffman and an effective projectile fragment charge are made. The relationship between these data and previously measured pion production and projectile fragmentation data is discussed. The data are also compared to some theoretical models. A simple expression is given for the differential cross section as a function of the projectile mass, target mass, and beam energy.

  7. Separable Optical Potentials for (d,p) Reactions

    E-print Network

    Ch. Elster; L. Hlophe; V. Eremenko; F. M. Nunes; G. Arbanas; J. E. Escher; I. J. Thompson

    2014-10-05

    An important ingredient for applications of nuclear physics to e.g. astrophysics or nuclear energy are the cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not possible, indirect methods like (d,p) reactions must be used instead. Those (d,p) reactions may be viewed as effective three-body reactions and described with Faddeev techniques. An additional challenge posed by (d,p) reactions involving heavier nuclei is the treatment of the Coulomb force. To avoid numerical complications in dealing with the screening of the Coulomb force, recently a new approach using the Coulomb distorted basis in momentum space was suggested. In order to implement this suggestion, one needs not only to derive a separable representation of neutron- and proton-nucleus optical potentials, but also compute the Coulomb distorted form factors in this basis.

  8. Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac-Coulomb atomic calculations

    Microsoft Academic Search

    V. Pershina; A. Borschevsky; E. Eliav; U. Kaldor

    2008-01-01

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the

  9. Gauge symmetry, chirality and parity effects in four-particle systems: Coulomb's law as a universal function for diatomic molecules

    NASA Astrophysics Data System (ADS)

    Van Hooydonk, G.

    2000-11-01

    Following recent work in search for a universal function (Van Hooydonk, Eur. J. Inorg. Chem., (1999), 1617), we test four symmetric ± anRn potentials for reproducing molecular potential energy curves (PECs). Classical gauge symmetry for 1/ R-potentials results in generic left-right asymmetric PECs. A pair of symmetric perturbed Coulomb potentials is quantitatively in accordance with observed PECs. For a bond, a four-particle system, charge inversion (a parity effect, atom chirality) is the key to explain this shape generically. A parity adapted Hamiltonian reduces from ten to two terms and to a soluble Bohr-like formula, a Kratzer (1- Re/ R) 2 potential. The result is similar to the combined action of spin and wave function symmetry upon the Hamiltonian in Heitler-London theory. Analytical perturbed Coulomb functions varying with (1- Re/ R) scale attractive and repulsive branches of PECs for 13 bonds H 2, HF, LiH, KH, AuH, Li 2, LiF, KLi, NaCs, Rb 2, RbCs, Cs 2 and I 2 in a single straight line. The 400 turning points for 13 bonds are reproduced with a deviation of 0.007 Å at both branches. For 230 points at the repulsive side, the deviation is 0.003 Å. The perturbed electrostatic Coulomb law is a universal molecular function. Ab initio zero molecular parameter functions give PECs of acceptable quality, just using atomic ionisation energies. The function can be used as a model potential for inverting levels and gives a first principle's comparison of short- and long-range interactions, important for the study of cold atoms. Wave-packet dynamics, femto-chemistry applied to the crossing of covalent and ionic curves, can provide evidence for this theory. We anticipate this scale/shape invariant scheme applies to smaller scales in nuclear and high-energy particle physics. For larger gravitational scales (Newton 1/ R potentials), problems with super-unification are discussed. Reactions between hydrogen and antihydrogen, feasible in the near future, will probably produce normal H 2.

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

    SciTech Connect

    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

    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.

  11. Static and dynamic image potential for tunneling into a Luttinger liquid

    NASA Astrophysics Data System (ADS)

    Hügle, S.; Egger, R.; Grabert, H.

    2000-12-01

    We study electron tunneling from a tip or a lead into an interacting quantum wire described by Luttinger liquid theory. Within a WKB-type approach, the Coulomb interaction between the wire and the tunneling electrons, as well as the finite traversal time are taken into account. Although the static image potential is only logarithmically suppressed against the bare Coulomb interaction, the dynamic image potential is not strong enough to alter power-law exponents entering the tunneling density of states.

  12. Coulomb blockade related to mutual Coulomb interaction in an external environment in an array of single tunnel junctions connected to Ni nanowires

    Microsoft Academic Search

    Junji Haruyama; Ken-Ichiro Hijioka; Motohiro Tako; Yuki Sato

    2000-01-01

    The Coulomb blockade (CB), which depends on the mutual Coulomb interaction (MCI) in external electromagnetic environments (EME's), is reported in an array system of single tunnel junctions connected directly to disordered Ni nanowires (i.e., an array of a disordered Ni nanowire\\/Al2O3\\/Al system located in parallel), fabricated using a nanoporous Al film template. The observed zero-bias conductance (G0) anomaly and its

  13. Coulomb interaction in self-consistent field calculations on molecules in molecular crystals

    Microsoft Academic Search

    M. M. Mestechkin

    1997-01-01

    A method of direct calculation of Madelung sums in molecular crystals is proposed. It is based on preliminary evaluation of Coulomb interaction of two contrarily charged elements of a crystal cell translated over the whole crystal. As a result some Madelung parameters similar to Coulomb integrals enter the molecular crystal Hartree - Fock equations whose dimensionality remains the same as

  14. ELECTRON PROPERTIES AND COULOMB COLLISIONS IN THE SOLAR WIND AT 1 AU: WIND OBSERVATIONS

    E-print Network

    California at Berkeley, University of

    ELECTRON PROPERTIES AND COULOMB COLLISIONS IN THE SOLAR WIND AT 1 AU: WIND OBSERVATIONS C. Salem,1 the electron properties of the solar wind observed by the Wind satellite at 1 AU in the ecliptic plane, during, in favor of a regulation of the heat flux by Coulomb collisions. The observed heat flux is then compared

  15. The Effect of Quantization and Coulomb Friction on the Stability of Haptic Rendering

    E-print Network

    Salisbury, Kenneth

    The Effect of Quantization and Coulomb Friction on the Stability of Haptic Rendering Nicola of haptics. A study of this problem is presented, which relates the maximum achievable object stiffness mea- surements interact with the inertia, natural viscous, and Coulomb damping of the haptic device

  16. Single-electron Coulomb blockade in a nanometer field-effect transistor with a single barrier

    E-print Network

    Single-electron Coulomb blockade in a nanometer field-effect transistor with a single barrier study of a new nanometer field-effect transistor with a single barrier in its one-dimensional channel corresponds to the Coulomb blockade of a single electron in the one-dimensional channel. A model

  17. Semiclassical theory of Coulomb blockade peak heights in chaotic quantum dots Evgenii E. Narimanov,1

    E-print Network

    Tomsovic, Steve

    Semiclassical theory of Coulomb blockade peak heights in chaotic quantum dots Evgenii E. Narimanov of Coulomb blockade peak heights in chaotic quantum dots. Using Berry's conjecture, we calculate peak height of the peak heights on any parameter which is varied; it is substantial for both sym- metric and asymmetric

  18. Experimental investigation of the Coulomb effect in electron projection lithography (EPL)

    Microsoft Academic Search

    Jiro Yamamoto; Fumio Murai; Akemi Moniwa

    2002-01-01

    Electron projection lithography (EPL) is a promising tool for next-generation lithography. However, beam blur due to the Coulomb effect becomes significant and degrades resolution when a high beam current is used to improve throughput. Suppressing the impact of the Coulomb effect is thus necessary to make EPL a practical tool for fabricating ULSI devices. We discuss the influence of the

  19. Measuring the top-quark Yukawa coupling at hadron colliders via tt¯h,h-->W+W-

    NASA Astrophysics Data System (ADS)

    Maltoni, F.; Rainwater, D.; Willenbrock, S.

    2002-08-01

    We study the signal and backgrounds for the process tt¯h,h-->W+W- at the CERN Large Hadron Collider (LHC) and a 100 TeV Very Large Hadron Collider (VLHC). Signals are studied in two-, three-, and four-lepton final states. We find a statistical uncertainty in the top-quark Yukawa coupling at the LHC of 16%,8%,12% for mh=130,160,190 GeV, respectively. The statistical uncertainty at the VLHC is likely to be negligible in comparison with the systematic uncertainty.

  20. Gravitational Modification of the Coulomb-Breit Hamiltonian

    SciTech Connect

    Caicedo, Jose Alexander; Urrutia, Luis Fernando [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (Mexico)

    2009-04-20

    In the poster session we presented a short review of our first results in the construction of the Coulomb-Breit Hamiltonian for a pair of fermions immersed in a background gravitational field which is described by General Relativity. Here we present a resume of that construction. We make a special stress on the objectives and the hypothesis used, but there is no special attention on the explicit form of the results because actually there is an updated and optimised version of our work in the edition process for publication; however we mention some special characteristics of the effect of the background gravitational field on the quantum nature of the system composed by fermions and its electromagnetic field, particularly the possibility of the observation of centre of mass effects in matter interferometry experiments.

  1. Nuclear reorientation and Coulomb excitation in a magnetic field

    NASA Astrophysics Data System (ADS)

    Demeur, M.; Leclercq-Willain, Ch.

    1988-08-01

    The motion of a charged structureless particle in a constant homogeneous magnetic field when scattered by a fixed system of charges such as a nucleus is investigated theoretically. The nucleus is characterized in terms of electric multipole moments; the matrix elements of any multipole operator are described by an analytical expression and a recurrence rule; and it is demonstrated that multipoles higher than zero cause target reorientations. Coulomb excitation rates are determined and shown to agree with the direct field-free results in the zero-field limit. Brief consideration is given to the implications of these findings for theoretical models of scattering in laboratory experiments and in astrophysical environments such as white dwarfs or neutron stars.

  2. Classical Kepler-Coulomb problem on SO(2, 2) hyperboloid

    SciTech Connect

    Petrosyan, D., E-mail: petrosyan@theor.jinr.ru; Pogosyan, G. S., E-mail: pogosyan@ysu.am [Joint Institute for Nuclear Research, Bogoliubov Laboratory of Theoretical Physics (Russian Federation)

    2013-10-15

    In the present work, the problem of the motion of the classical particle in the Kepler-Coulomb field in three-dimensional hyperbolic space H{sub 2}{sup 2}: z{sub 2}{sup 0} + z{sub 2}{sup 1} - z{sub 2}{sup 2} - z{sub 2}{sup 3} = R{sup 2} is solved in the framework of Hamilton-Jacobi equation. The requirements for the existence of bounded motion of particle are formulated. The equation of the trajectory of particle is obtained, and it is shown that all the finite trajectories are closed. It is also demonstrated that under the certain values (zero or negative) of the separation constant A the fall of the particle onto the center takes place.

  3. Gribov pendulum in the Coulomb gauge on curved spaces

    E-print Network

    Fabrizio Canfora; Alex Giacomini; Julio Oliva

    2011-10-29

    In this paper the generalization of the Gribov pendulum equation in the Coulomb gauge for curved spacetimes is analyzed on static spherically symmetric backgrounds. A rigorous argument for the existence and uniqueness of solution is provided in the asymptotically AdS case. The analysis of the strong and weak boundary conditions is equivalent to analyzing an effective one-dimensional Schrodinger equation. Necessary conditions in order for spherically symmetric backgrounds to admit solutions of the Gribov pendulum equation representing copies of the vacuum satisfying the strong boundary conditions are given. It is shown that asymptotically flat backgrounds do not support solutions of the Gribov pendulum equation of this type, while on asymptotically AdS backgrounds such ambiguities can appear. Some physical consequences are discussed.

  4. Exploring Interatomic Coulombic Decay by Free Electron Lasers

    SciTech Connect

    Demekhin, Philipp V.; Stoychev, Spas D.; Kuleff, Alexander I.; Cederbaum, Lorenz S. [Theoretische Chemie, Physikalisch-Chemisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2011-12-30

    To exploit the high intensity of laser radiation, we propose to select frequencies at which single-photon absorption is of too low energy and two or more photons are needed to produce states of an atom that can undergo interatomic Coulombic decay (ICD) with its neighbors. For Ne{sub 2} it is explicitly demonstrated that the proposed multiphoton absorption scheme is much more efficient than schemes used until now, which rely on single-photon absorption. Extensive calculations on Ne{sub 2} show how the low-energy ICD electrons and Ne{sup +} pairs are produced for different laser intensities and pulse durations. At higher intensities the production of Ne{sup +} pairs by successive ionization of the two atoms becomes competitive and the respective emitted electrons interfere with the ICD electrons. It is also shown that a measurement after a time delay can be used to determine the contribution of ICD even at high laser intensity.

  5. Particle-gamma measurements around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Pain, Steven

    2014-09-01

    Reactions performed around Coulomb barrier energies have contributed significantly to our foundation of nuclear structure knowledge over the decades, being highly selective probes of specific components of the nuclear wave function. In particular, such reactions can be used as probes of single-particle structure, pairing and collective structure, etc. Many of these reactions are more recently being revisited, but employed in inverse kinematics to study reactions using radioactive beams. In this effort, the addition of gamma-ray detection is becoming increasingly recognized as crucial to fully exploiting such measurements, and in some cases is critical to the experimental approach. An brief overview of techniques and some state of the art measurements will be presented. Work supported in part by the US Department of Energy.

  6. Correlated continuum wave functions for three particles with Coulomb interactions

    SciTech Connect

    Gasaneo, G.; Colavecchia, F.D.; Garibotti, C.R. [Centro Atomico Bariloche and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8400 San Carlos de Bariloche, Rio Negro (Argentina)] [Centro Atomico Bariloche and Consejo Nacional de Investigaciones Cientificas y Tecnicas, 8400 San Carlos de Bariloche, Rio Negro (Argentina); Miraglia, J.E.; Macri, P. [Instituto de Astronomia y Fisica del Espacio, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina)] [Instituto de Astronomia y Fisica del Espacio, Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina)

    1997-04-01

    We present an approximate solution of the Schr{umlt o}dinger equation for the three-body Coulomb problem. We write the Hamiltonian in parabolic curvilinear coordinates and study the possible separation of the wave equation as a system of coupled partial differential equations. When two of the particles are heavier than the others, we write an approximate wave equation that incorporates some terms of the Hamiltonian that before had been considered as a perturbation. Its solution can be expressed in terms of a confluent hypergeometric function of two variables. We show that the proposed wave function includes a correlation between the motion of the light particle relative to the heavy particles and verifies the correct asymptotic behavior when all particles are far from each other. Finally, we discuss the possible uses of this function in the calculation of transition matrices and differential cross sections in ionizing collisions. {copyright} {ital 1997} {ital The American Physical Society}

  7. Investigation of uncertainty components in Coulomb blockade thermometry

    SciTech Connect

    Hahtela, O. M.; Heinonen, M.; Manninen, A. [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland)] [MIKES Centre for Metrology and Accreditation, Tekniikantie 1, 02150 Espoo (Finland); Meschke, M.; Savin, A.; Pekola, J. P. [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland)] [Low Temperature Laboratory, Aalto University, Tietotie 3, 02150 Espoo (Finland); Gunnarsson, D.; Prunnila, M. [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland)] [VTT Technical Research Centre of Finland, Tietotie 3, 02150 Espoo (Finland); Penttilä, J. S.; Roschier, L. [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)] [Aivon Oy, Tietotie 3, 02150 Espoo (Finland)

    2013-09-11

    Coulomb blockade thermometry (CBT) has proven to be a feasible method for primary thermometry in every day laboratory use at cryogenic temperatures from ca. 10 mK to a few tens of kelvins. The operation of CBT is based on single electron charging effects in normal metal tunnel junctions. In this paper, we discuss the typical error sources and uncertainty components that limit the present absolute accuracy of the CBT measurements to the level of about 1 % in the optimum temperature range. Identifying the influence of different uncertainty sources is a good starting point for improving the measurement accuracy to the level that would allow the CBT to be more widely used in high-precision low temperature metrological applications and for realizing thermodynamic temperature in accordance to the upcoming new definition of kelvin.

  8. Coulomb-scattering and eta - eta-prime mixing angle

    E-print Network

    F. Kleefeld

    2006-02-20

    The fascinating physics underlying eta and eta-prime mesons can be studied theoretically and experimentally in various contexts. In this presentation we want to turn our attention to two important uncorrelated aspects of this vivid research field which provide yet unexpected challenges or surprises. First we discuss open questions in the theoretical treatment of Coulomb-interaction in the context of reaction processes like p p --> p p eta. Then we review eta - eta-prime and sigma(600) - f_0(980) mixing in the U(3) x U(3) Linear Sigma Model and extract information on eta - eta-prime mixing and the K*0(800) resonance from meson-meson scattering.

  9. Coulomb problem in non-commutative quantum mechanics

    SciTech Connect

    Galikova, Veronika; Presnajder, Peter [Faculty of Mathematics, Physics and Informatics, Comenius University of Bratislava, Mlynska dolina F2, Bratislava (Slovakia)] [Faculty of Mathematics, Physics and Informatics, Comenius University of Bratislava, Mlynska dolina F2, Bratislava (Slovakia)

    2013-05-15

    The aim of this paper is to find out how it would be possible for space non-commutativity (NC) to alter the quantum mechanics (QM) solution of the Coulomb problem. The NC parameter {lambda} is to be regarded as a measure of the non-commutativity - setting {lambda}= 0 which means a return to the standard quantum mechanics. As the very first step a rotationally invariant NC space R{sub {lambda}}{sup 3}, an analog of the Coulomb problem configuration space (R{sup 3} with the origin excluded) is introduced. R{sub {lambda}}{sup 3} is generated by NC coordinates realized as operators acting in an auxiliary (Fock) space F. The properly weighted Hilbert-Schmidt operators in F form H{sub {lambda}}, a NC analog of the Hilbert space of the wave functions. We will refer to them as 'wave functions' also in the NC case. The definition of a NC analog of the hamiltonian as a hermitian operator in H{sub {lambda}} is one of the key parts of this paper. The resulting problem is exactly solvable. The full solution is provided, including formulas for the bound states for E < 0 and low-energy scattering for E > 0 (both containing NC corrections analytic in {lambda}) and also formulas for high-energy scattering and unexpected bound states at ultra-high energy (both containing NC corrections singular in {lambda}). All the NC contributions to the known QM solutions either vanish or disappear in the limit {lambda}{yields} 0.

  10. Anisotropy of the Coulomb Interaction between Folded Proteins: Consequences for Mesoscopic Aggregation of Lysozyme

    PubMed Central

    Chan, Ho Yin; Lankevich, Vladimir; Vekilov, Peter G.; Lubchenko, Vassiliy

    2012-01-01

    Toward quantitative description of protein aggregation, we develop a computationally efficient method to evaluate the potential of mean force between two folded protein molecules that allows for complete sampling of their mutual orientation. Our model is valid at moderate ionic strengths and accounts for the actual charge distribution on the surface of the molecules, the dielectric discontinuity at the protein-solvent interface, and the possibility of protonation or deprotonation of surface residues induced by the electric field due to the other protein molecule. We apply the model to the protein lysozyme, whose solutions exhibit both mesoscopic clusters of protein-rich liquid and liquid-liquid separation; the former requires that protein form complexes with typical lifetimes of approximately milliseconds. We find the electrostatic repulsion is typically lower than the prediction of the Derjaguin-Landau-Verwey-Overbeek theory. The Coulomb interaction in the lowest-energy docking configuration is nonrepulsive, despite the high positive charge on the molecules. Typical docking configurations barely involve protonation or deprotonation of surface residues. The obtained potential of mean force between folded lysozyme molecules is consistent with the location of the liquid-liquid coexistence, but produces dimers that are too short-lived for clusters to exist, suggesting lysozyme undergoes conformational changes during cluster formation. PMID:22768950

  11. The Effective Potential, the Renormalisation Group and Vacuum Stability

    E-print Network

    Martin B. Einhorn; D. R. Timothy Jones

    2007-03-06

    We review the calculation of the the effective potential with particular emphasis on cases when the tree potential or the renormalisation-group-improved, radiatively corrected potential exhibits non-convex behaviour. We illustrate this in a simple Yukawa model which exhibits a novel kind of dimensional transmutation. We also review briefly earlier work on the Standard Model. We conclude that, despite some recent claims to the contrary, it can be possible to infer reliably that the tree vacuum does not represent the true ground state of the theory.

  12. Observations of static Coulomb stress triggering of the November 2011 M5.7 Oklahoma earthquake sequence

    USGS Publications Warehouse

    Sumy, Danielle F.; Cochran, Elizabeth S.; Keranen, Katie M.; Wei, Maya; Abers, Geoffrey A.

    2014-01-01

    In November 2011, a M5.0 earthquake occurred less than a day before a M5.7 earthquake near Prague, Oklahoma, which may have promoted failure of the mainshock and thousands of aftershocks along the Wilzetta fault, including a M5.0 aftershock. The M5.0 foreshock occurred in close proximity to active fluid injection wells; fluid injection can cause a buildup of pore fluid pressure, decrease the fault strength, and may induce earthquakes. Keranen et al. [] links the M5.0 foreshock with fluid injection, but the relationship between the foreshock and successive events has not been investigated. Here we examine the role of coseismic Coulomb stress transfer on earthquakes that follow the M5.0 foreshock, including the M5.7 mainshock. We resolve the static Coulomb stress change onto the focal mechanism nodal plane that is most consistent with the rupture geometry of the three M???5.0 earthquakes, as well as specified receiver fault planes that reflect the regional stress orientation. We find that Coulomb stress is increased, e.g., fault failure is promoted, on the nodal planes of ~60% of the events that have focal mechanism solutions, and more specifically, that the M5.0 foreshock promoted failure on the rupture plane of the M5.7 mainshock. We test our results over a range of effective coefficient of friction values. Hence, we argue that the M5.0 foreshock, induced by fluid injection, potentially triggered a cascading failure of earthquakes along the complex Wilzetta fault system.

  13. Identification of Coulomb Friction at Supporting Points of a Hinged-Hinged Beam

    NASA Astrophysics Data System (ADS)

    Yabuno, Hiroshi; Koda, Takafumi

    Systems with slight Coulomb friction at a supporting point have a very small dead zone in which the system stops after free oscillation. The small stiffness makes the dead zone very wide, even under slight Coulomb friction, because it is determined according to the ratio between Coulomb friction and stiffness. Results of a previous study clarify both theoretically and experimentally that in the neighborhood of buckling point, slight Coulomb friction produces a large dead zone around the stable and unstable equilibrium states of the pitchfork bifurcation in the case without Coulomb friction. Therefore, it is important in analyses of behavior of low-stiffness systems such as flexible structures used for spacecraft, to estimate the value of Coulomb friction at a supporting point. In this paper, we describe an experimental identification method for the bending moment attributable to Coulomb friction at the supporting points of a hinged-hinged beam. The moment attributable to dynamic friction is identified from experimental free oscillation by separating the effects of viscous damping and dynamic friction. For static friction, we use the equilibrium region in the bifurcation diagram because of static friction. In the vicinity of the buckling point, the region is very wide. Its boundary is obtained easily through experimentation. We describe a method for identification of the moment because of the static friction from the experimentally obtained boundary.

  14. Yukawa Monte Carlo (YMC) and Orbital Free Molecular Dynamics (OFMD) approaches for the eos of warm dense iron plasma

    NASA Astrophysics Data System (ADS)

    Gilles, Dominique; Lambert, Flavien; Clerouin, Jean

    2008-04-01

    Yukawa Monte Carlo and Molecular Dynamics simulations are powerful techniques extensively used to compute plasma properties such as EOS or transport coefficients, but are limited to applications where the linear electronic screening assumption is valid (1). Recently we have shown that a modified scheme using density functional theory with a Thomas-Fermi kinetic energy functional for the electrons (OFMD) may be well suited to perform MD simulations at high densities and temperature, without any assumption on the electronic screening (2). For selected iron plasma conditions representative of warm and dense matter, we shall compare pressure results calculated using YMC and OFMD codes and QEOS (3) and Sesame EOS models (4) and discuss the influence of keys parameters, like ionization in Yukawa theory. References: [1] D. Gilles, O. Peyrusse, JQSRT 53, 6, 1995. ;Caillol J-M, Gilles D., J. Stat Phys. 100, N5/6, 905-947, 2000; Caillol J-M, Gilles D., J. Phys. A 36, 6243, (2003) ; A. Potekhin, G. Chabrier, Gilles, PRE 65, 036412, 2002. [2] D. Gilles, F. Lambert, J. Cl'erouin, S. Mazevet, Gwena"el Salin, HEDP 3, 95-98, 2007; F. Lambert, J. Cl'erouin, S. Mazevet, D. Gilles, Plama Physics, 47,4-5, 272-280(2007). [3] R.M. More, Lawrence Livermore Laboratory Report, UCRL-84991, (1981). [4] G.I. Kerley, User's Manual for PANDA : A computer Code for calculating Equation of State, Los Alamos National Laboratory, 1981 (LA8833).

  15. Light staus and enhanced Higgs diphoton rate with non-universal gaugino masses and SO(10) Yukawa unification

    NASA Astrophysics Data System (ADS)

    Badziak, Marcin; Olechowski, Marek; Pokorski, Stefan

    2013-10-01

    It is shown that substantially enhanced Higgs to diphoton rate induced by light staus with large left-right mixing in MSSM requires at the GUT scale non-universal gaugino masses with bino and/or wino lighter than gluino. The possibility of such enhancement is investigated in MSSM models with arbitrary gaugino masses at the GUT scale with additional restriction of top-bottom-tau Yukawa unification, as predicted by minimal SO(10) GUTs. Many patterns of gaugino masses leading to enhanced Higgs to diphoton rate and the Yukawa unification are identified. Some of these patterns can be accommodated in a well-motivated scenarios such as mirage mediation or SUSY breaking F -terms being a non- singlet of SO(10). Phenomenological implications of a scenario with non-universal gaugino masses generated by a mixture of the singlet F -term and the F -term in a 24-dimensional representation of SU(5) ? SO(10) are studied in detail. Possible non-universalities of other soft terms generated by such F-terms are discussed. The enhancement of Higgs to diphoton rate up to 30% can be obtained in agreement with all phenomenological constraints, including vacuum metastability bounds. The lightest sbottom and pseudoscalar Higgs are within easy reach of the 14 TeV LHC. The LSP can be either bino-like or wino-like. The thermal relic abundance in the former case may be in agreement with the cosmological data thanks to efficient stau coannihilation.

  16. Static Coulomb stress-based Southern California earthquake forecasts: A pseudoprospective test

    NASA Astrophysics Data System (ADS)

    Strader, Anne; Jackson, David D.

    2015-03-01

    Many studies support the hypothesis that where earthquakes occur, recent changes in resolved Coulomb stress tend to be positive. How about the converse hypothesis, that where resolved Coulomb stress recently increased, earthquakes are more likely to occur? Successful earthquake forecasting by Coulomb stress changes requires the converse. To test this, we calculated stress everywhere in our study area, not just at earthquake locations. We modeled stress accumulation in Southern California since 1812 both from the elastic effect of slip below locked faults and from M ? 5 "source" earthquakes up to any given date. To minimize the effect of secondary aftershocks not directly related to the source earthquakes, we measured seismicity using a gridded binary map: each 0.1° × 0.1° cell is "activated" if containing one or more test events ("receiver" earthquakes) of M ? 2.8. We then constructed an empirical relationship between resolved Coulomb stress and activation rate within regions with similar stress values, defining probabilities of activated cells during the "test" period, within 11 years of the M7.1 Hector Mine earthquake. We found that Coulomb stress reliably indicates future earthquake locations at the 95% confidence interval. However, smoothed seismicity forecasts outperformed Coulomb forecasts in some areas with large earthquakes due to aftershock clustering. Most earthquakes tend to nucleate in areas with Coulomb stress changes greater than 0.5 MPa or less than -0.5 MPa. Within areas with increased Coulomb stress from older earthquakes, fewer earthquakes occurred than anticipated. After reducing stress uncertainty impact, Coulomb rate-and-state forecasts may also improve upon statistical earthquake forecasts.

  17. Relaxation dynamics of the electron distribution in the Coulomb-blockade problem.

    SciTech Connect

    Rodionov, Ya. I.; Burmistrov, I. S.; Chtchelkatchev, N. M.; Materials Science Division; Russian Academy of Sciences; Moscow Inst. of Physics and Technology

    2010-01-01

    We study the relaxation dynamics of electron distribution function on the island of a single-electron transistor. We focus on the regime of not very low temperatures in which an electron coherence can be neglected but quantum fluctuations of charge are strong due to Coulomb interaction. The quantum kinetic equation governing evolution of the electron distribution function due to escape of electrons to the reservoirs is derived. Analytical solutions for time dependence of the electron distribution are obtained in the regimes of weak and strong Coulomb blockade. We find that usual exponential in time relaxation is strongly modified due to the presence of Coulomb interaction.

  18. Long-Range Coulomb Interaction Effects on the Surface Dirac Electron System of a Three-Dimensional Topological Insulator

    NASA Astrophysics Data System (ADS)

    Okuma, Nobuyuki; Ogata, Masao

    2015-03-01

    The surface state of a three-dimensional topological insulator forms a two-dimensional massless Dirac electron system. In Dirac electron systems, Coulomb interaction is not screened due to the small density of states at the Fermi energy and thus the long-range Coulomb interaction (LRCI) plays a crucial role. In this paper, we investigate the surface state with chemical potential ? = 0 in the presence of the LRCI using the Wilsonian renormalization group. We first check the Fermi velocity enhancement in the surface Dirac system, which also occurs in a usual Dirac electron system. The most remarkable feature of the surface Dirac system is that the Dirac Hamiltonian contains not pseudo spin but real spin Pauli matrices. Because of this feature, we find the g-factor enhancement, which is a unique property of the surface Dirac system. We also investigate the explicit form of the spin susceptibility and find that the spin susceptibility is enhanced in the presence of the LRCI.

  19. Phase diagrams of systems of particles interacting via repulsive potentials

    NASA Astrophysics Data System (ADS)

    Rascón, C.; Velasco, E.; Mederos, L.; Navascués, G.

    1997-04-01

    We use a recently developed density-functional perturbation theory, which has been applied successfully to predict phase diagrams of systems of attractive particles, to describe the phase diagram of particles interacting via repulsive potentials. We consider potentials composed of a hard-sphere core plus a repulsive term. Specifically, we have investigated square shoulder and repulsive Yukawa terms. We show that, when the range of the interaction is very short, the shoulder potential leads to solid-solid coexistence involving two face-centered cubic structures, in analogy to an attractive square-well potential. Comparison with simulation results shows that the theory is quantitatively correct. If the range of the potentials is sufficiently long, we also find that a body-centered cubic structure can be stabilized. By considering the phase behavior at zero temperature, we argue that several triple points, involving coexistence of fluid and/or solid phases, may occur. A repulsive Yukawa term also shows a region of body-centered cubic stability but, contrary to the square shoulder and attractive Yukawa cases, there is no isostructural solid-solid coexistence. The role of the functional dependence of the interaction potential on particle separation at short distances is discussed and shown to be crucial to generate a solid-solid transition in systems of repulsive particles. Available computer simulation results for this system indicate that the density-functional approximation for the hard-sphere system used in this work, as well as all other currently available approximations, although qualitatively correct, may be overestimating the stability of the body-centered cubic phase.

  20. Phase-field approach to implicit solvation of biomolecules with Coulomb-field approximation

    PubMed Central

    Zhao, Yanxiang; Kwan, Yuen-Yick; Che, Jianwei; Li, Bo; McCammon, J. Andrew

    2013-01-01

    A phase-field variational implicit-solvent approach is developed for the solvation of charged molecules. The starting point of such an approach is the representation of a solute-solvent interface by a phase field that takes one value in the solute region and another in the solvent region, with a smooth transition from one to the other on a small transition layer. The minimization of an effective free-energy functional of all possible phase fields determines the equilibrium conformations and free energies of an underlying molecular system. All the surface energy, the solute-solvent van der Waals interaction, and the electrostatic interaction are coupled together self-consistently through a phase field. The surface energy results from the minimization of a double-well potential and the gradient of a field. The electrostatic interaction is described by the Coulomb-field approximation. Accurate and efficient methods are designed and implemented to numerically relax an underlying charged molecular system. Applications to single ions, a two-plate system, and a two-domain protein reveal that the new theory and methods can capture capillary evaporation in hydrophobic confinement and corresponding multiple equilibrium states as found in molecular dynamics simulations. Comparisons of the phase-field and the original sharp-interface variational approaches are discussed. PMID:23862933

  1. Dynamical theory of strongly coupled two-dimensional Coulomb fluids in the weakly degenerate quantum domain

    SciTech Connect

    Das, Mukunda P.; Golden, Kenneth I.; Green, Frederick

    2001-10-01

    We study the problem of dynamical response and plasma mode dispersion in strongly coupled two-dimensional Coulomb fluids (2DCFs) in the weakly degenerate quantum domain. Adapting the nonlinear response function approach of Golden and Kalman [Phys. Rev. A 19, 2112 (1979)] to the 2DCF, we construct a self-consistent approximation scheme for the calculation of the density response functions and plasma mode dispersion at long wavelengths. The basic ingredients in the construction are (i) the first kinetic equation in the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy, (ii) the velocity-average-approximation (VAA) hypothesis, (iii) the quadratic fluctuation-dissipation theorem, and (iv) the dynamical superposition approximation (DSA) closure hypothesis. The reliability of the VAA-DSA theory can be assessed by observing that the principal coupling correction to the 2D temperature-dependent Lindhard function is identified as being precisely the part of the third-frequency-moment sum-rule coefficient proportional to the potential energy.

  2. Electron heating due to coulomb collisions between slow and intermediate electrons in DC glow discharges

    NASA Astrophysics Data System (ADS)

    Eliseev, Stepan; Kudryavtsev, Anatoliy

    2014-10-01

    As is known, the electrons in the cathode glow discharge plasma (negative glow and Faraday dark space) can be divided into three groups - slow, intermediate and fast electrons. Slow electrons, having maximum density, provide quasi-neutrality. They're locked in a potential well and have Maxwellian energy distribution. Fast electrons gain their energy in the cathode fall and maintain sufficient ionization in discharge. Intermediate electrons originate during ionization by fast electrons and carry current in the discharge. They have energies up to the threshold of inelastic collisions in the gas. At the same time they carry out their energy to the walls of the discharge and spend it on elastic collisions with gas atoms and Coulomb collisions with slow electrons and heat them. The amount of heating depends on the degree of ionization of gas, pressure, discharge tube size etc. The paper presents the results of a study on the impact of the heating on temperature and concentration of slow electrons in glow discharge.

  3. Theory and simulation of ion Coulomb crystal formation in a Penning trap

    NASA Astrophysics Data System (ADS)

    Asprusten, Martin; Worthington, Simon; Thompson, Richard C.

    2014-01-01

    Ion Coulomb crystals (ICCs) are formed by laser-cooled ions in both radio-frequency and Penning traps. In radio-frequency traps, the crystals are generally stationary. In Penning traps, ICCs always rotate. The frequency of rotation is often set by an applied rotating wall drive that forces the crystal to rotate at the same frequency as the drive. In the absence of any applied rotating or oscillating fields, ICCs in a Penning trap can be in stable equilibrium with a range of rotation frequencies. The density and shape of the crystal adjust with the rotation frequency to ensure that equilibrium is reached. Here, we show that the parameters of the radial laser-cooling beam determine the rotation frequency of a small crystal in a Penning trap when no driving fields are present. We demonstrate, using an approximate theoretical treatment and realistic simulations, that the crystal rotation frequency is independent of the number of ions and the trap parameters, so long as the crystal radius remains smaller than the cooling laser beam waist. As the rotation frequency increases, the crystal eventually becomes a linear string, at which point it is no longer able to adjust its density. Instead, a small amplitude vibration in the zigzag mode of oscillation manifests itself as a rotation of the crystal at a fixed frequency that depends only on the applied trap potential.

  4. Near-BPS Skyrmions: Non-shell configurations and Coulomb effects

    E-print Network

    Eric Bonenfant; Louis Harbour; Luc Marleau

    2012-10-12

    The relatively small binding energy in nuclei suggests that they may be well represented by near-BPS Skyrmions since their mass is roughly proportional to the baryon number $A.$ For that purpose, we propose a generalization of the Skyrme model with terms up to order six in derivatives of the pion fields and treat the nonlinear $\\sigma$ and Skyrme terms as small perturbations. For our special choice of mass term (or potential) $V$, we obtain well-behaved analytical BPS-type solutions with non-shell configurations for the baryon density, as opposed to the more complex shell-like configurations found in most extensions of the Skyrme model . Along with static and (iso)rotational energies, we add to the mass of the nuclei the often neglected Coulomb energy and isospin breaking term. Fitting the four model parameters, we find a remarkable agreement for the binding energy per nucleon $B/A$ with respect to experimental data. These results support the idea that nuclei could be near-BPS Skyrmions.

  5. Near-BPS Skyrmions: Non-shell configurations and Coulomb effects

    E-print Network

    Bonenfant, Eric; Marleau, Luc

    2012-01-01

    The relatively small binding energy in nuclei suggests that they may be well represented by near-BPS Skyrmions since their mass is roughly proportional to the baryon number $A.$ For that purpose, we propose a generalization of the Skyrme model with terms up to order six in derivatives of the pion fields and treat the nonlinear $\\sigma$ and Skyrme terms as small perturbations. For our special choice of mass term (or potential) $V$, we obtain well-behaved analytical BPS-type solutions with non-shell configurations for the baryon density, as opposed to the more complex shell-like configurations found in most extensions of the Skyrme model . Along with static and (iso)rotational energies, we add to the mass of the nuclei the often neglected Coulomb energy and isospin breaking term. Fitting the four model parameters, we find a remarkable agreement for the binding energy per nucleon $B/A$ with respect to experimental data. These results support the idea that nuclei could be near-BPS Skyrmions.

  6. Influence of Coulomb collisions on the structure of reconnection layers

    SciTech Connect

    Daughton, W.; Roytershteyn, V.; Albright, B. J.; Yin, L.; Bowers, Kevin J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Karimabadi, H. [University of California, San Diego, La Jolla, California 92093 (United States)

    2009-07-15

    The influence of Coulomb collisions on the structure of reconnection layers is examined in neutral sheet geometry using fully kinetic simulations with a Monte Carlo treatment of the Fokker-Planck operator. The algorithm is first carefully benchmarked against key predictions from transport theory, including the parallel and perpendicular resistivities as well as the thermal force. The results demonstrate that the collisionality is accurately specified, thus allowing the initial Lundquist number to be chosen as desired. For modest Lundquist numbers S < or approx. 1000, the classic Sweet-Parker solution is recovered. Furthermore, a distinct transition to a faster kinetic regime is observed when the thickness of the resistive layer {delta}{sub SP} falls below the ion inertial length d{sub i}. For higher Lundquist numbers S > or approx. 1000, plasmoids (secondary islands) are observed within the elongated resistive layers. These plasmoids give rise to a measurable increase in the reconnection rate and for certain cases induce a transition to kinetic regimes sooner than expected from the {delta}{sub SP}{approx_equal}d{sub i} condition. During this transition, the reconnection electric field exceeds the runaway limit, leading to electron scale current layers in which the nonideal electric field is supported predominantly by off-diagonal components in the electron pressure tensor, along with a residual contribution from electron-ion momentum exchange. These weakly collisional electron layers are also unstable to the formation of new plasmoids.

  7. The onset of coulomb explosions in polyatomic molecules

    PubMed

    Smith; Ledingham; Singhal; McCanny; Graham; Kilic; Tzallas; Kosmidis; Langley; Taday

    1999-01-01

    With the development of high intensity femtosecond lasers, the ionisation and dissociation dynamics of molecules has become an area of considerable interest. Using the technique of femtosecond laser mass spectrometry (FLMS), the molecules carbon disulphide, pyrimidine, toluene, cyclohexanone and benzaldehyde are studied with pulse widths of 50 fs in the near infrared (IR) wavelength region (790 nm). Results are presented and contrasted for laser beam intensities around 10(15) and 10(16) W cm(-2). For the lower intensities, the mass spectra yield dominant singly charged parent ions. Additionally, the appearance of doubly charged parent ions is evident for carbon disulphide, toluene and benzaldehyde with envelopes of doubly charged satellite species existing in these local regions. Carbon disulphide also reveals a small triply charged component. Such atomic-like features are thought to be a strong fingerprint of FLMS at these intensities. However, upon increasing the laser intensity to approximately 10(16) W cm(-2), parent ion dominance decreases and the appearance of multiply charged atomic species occurs, particularly carbon. This phenomenon has been attributed to Coulomb explosions in which the fast absorption of many photons may produce transient highly ionised parent species which can subsequently blow apart. Copyright 1999 John Wiley & Sons, Ltd. PMID:10407326

  8. Coulomb pairing resonances in multiple-ring aromatic molecules

    E-print Network

    Huber, D L

    2015-01-01

    We present an analysis of the Coulomb pairing resonances observed in photo-double-ionization studies of CnHm aromatic molecules with multiple benzene-like rings. It is applied to naphthalene, anthracene, phenanthrene, pyrene and coronene, all of which have six-member rings, and azulene which is comprised of a five-member and a seven-member ring. There is a high energy resonance at ~ 40 eV that is found in all of the molecules cited and is associated with paired electrons localized on carbon sites on the perimeter of the molecule, each of which having two carbon sites as nearest neighbors. The low energy resonance at 10 eV, which is found only in pyrene and coronene, is attributed to the formation of paired electrons localized on arrays of interior carbon atoms that have the point symmetry of the molecule with each carbon atom having three nearest neighbors. The origin of the anomalous increase in the doubly charged to singly charged parent-ion ratio that is found above the 40 eV resonance in all of the cited ...

  9. On the Fractal Character of the Planar Coulomb Classical Scattering H.Varvoglis1Y2

    E-print Network

    Varvoglis, Harry

    is orbiting around the incoming ion (charge transfer, C) or, ¢nally, the electron is ejected from the targetOn the Fractal Character of the Planar Coulomb Classical Scattering H.Varvoglis1Y2Ã , K. Katsonis1Y

  10. Collective strong coupling between ion Coulomb crystals and an optical cavity field: Theory and experiment

    E-print Network

    Albert, M.

    A detailed description and theoretical analysis of experiments achieving coherent coupling between an ion Coulomb crystal and an optical cavity field are presented. The various methods used to measure the coherent coupling ...

  11. Study of ultrasonic attenuation in f-electron systems in the paramagnetic limit of Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Shadangi, Asit Ku.; Rout, G. C.

    2015-05-01

    We report here a microscopic model study of ultrasonic attenuation in f-electron systems based on Periodic Anderson Model in which Coulomb interaction is considered within a mean-field approximation for a weak interaction. The Phonon is coupled to the conduction band and f-electrons. The phonon Green's function is calculated by Zubarev's technique of the Green's function method. The temperature dependent ultrasonic attenuation co-efficient is calculated from the imaginary part of the phonon self-energy in the dynamic and long wave length limit. The f-electron occupation number is calculated self-consistently in paramagnetic limit of Coulomb interaction. The effect of the Coulomb interaction on ultrasonic attenuation is studied by varying the phonon coupling parameters to the conduction and f-electrons, hybridization strength, the position of f-level and the Coulomb interaction Strength. Results are discussed on the basis of experimental results.

  12. Polarons as solitary wave solutions to the Dirac-Coulomb system

    E-print Network

    Comech, A

    2013-01-01

    We consider solitary wave solutions to the Dirac-Coulomb system both from physical and mathematical points of view. Possible applications of these solutions in physics are discussed. Namely, we consider the model of Dirac fermions with the Coulomb attraction, which appears in certain condensed matter systems with emergent Dirac fermions interacting via optical phonons. In this model, there exist classical soliton solutions of equations of motion which correspond to polarons. We also discuss the relativistic generalization of this model: the fermion field interacting with the gravitational field, where the Dirac fermions with the Coulomb attraction appear in Newtonian limit. On the mathematical side, we develop analytical methods for the Dirac-Coulomb system, showing that the no-node gap solitons of sufficiently small amplitude are linearly (or spectrally) stable.

  13. Generalized quasiclassical approximation for the Coulomb excitation of nuclei with variable moment of inertia

    SciTech Connect

    Bolotin, Y.L.; Gonchar, V.Y.; Inopin, E.V.; Chekanov, N.A.

    1987-04-01

    Coulomb excitation of rotational states is studied within the framework of the generalized quasiclassical approximation taking into account variation of the moment of inertia of the nucleus in the scattering.

  14. 1694 Macromolecules 1992,25, 1694-1698 Dielectric Screening of Coulomb Interactions in Polymers

    E-print Network

    Taylor, Philip L.

    1694 Macromolecules 1992,25, 1694-1698 Dielectric Screening of Coulomb Interactions in Polymers conformation of macromolecules begin with a calculation of the energies of possible structures. Of the various

  15. Pore pressure and poroelasticity effects in Coulomb stress analysis of earthquake interactions

    E-print Network

    Pore pressure and poroelasticity effects in Coulomb stress analysis of earthquake interactions Massimo Cocco Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy James R. Rice Engineering determined by mean stress changes in those surroundings. INDEX TERMS: 7209 Seismology: Earthquake dynamics

  16. Electrostatic normal modes in an unmagnetized homogeneous Coulomb plasma. A Hamiltonian approach

    Microsoft Academic Search

    Richard G. Spencer; Rudolf Schmid

    1984-01-01

    The hamiltonian structure for fluid electrodynamics in the Coulomb case is used to derive the Bohm-Gross and ion-acoustic dispersion relations. Research partially supported by National Science Foundation grants MCS 8301124 and MCS 8120790.

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

    E-print Network

    Hilley, George

    Steady state erosion of critical Coulomb wedges with applications to Taiwan and the Himalaya G. E the mountain belt by tectonic accretion and geomorphic erosion, respectively. We developed a coupled erosion. Erosional steadystateisreachedwhenallmaterialintroducedintothewedgeisremovedby erosion thatis limited

  18. Effect of the on-site Coulomb repulsion on superconductivity in the boson-fermion model

    Microsoft Academic Search

    Tadeusz Domanski

    We study the influence of the repulsive Coulomb interactions on thermodynamic properties of the boson fermion model with an anisotropic (d-wave, and extended s-wave) order parameter. Su- perconductivity is induced in this model from the anisotropic charge exchange interaction between the conduction band fermions (electrons or holes) and the immobile hard-core bosons (the localized electron pairs). The on-site Coulomb repulsion

  19. Effect of charge polarization on the Coulomb barrier for cold-fusion reactions

    SciTech Connect

    Ichikawa, Takatoshi; Iwamoto, Akira [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki, 319-1195 (Japan); Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki, 319-1195 (Japan)

    2005-06-01

    We estimate the decrease of the Coulomb-barrier height between colliding partners due to charge polarizations in the entrance channel for cold-fusion reactions. The resulting charge displacements between protons and neutrons are the sum of the surface- and volume-charge components. We show the difference between the charge polarization of light and heavy nuclei and the decrease of the Coulomb barrier height for synthesizing superheavy elements.

  20. Effect of on-site Coulomb repulsion on superconductivity in the boson-fermion model

    Microsoft Academic Search

    T. Domanski; M. Curie

    2002-01-01

    We study the influence of the repulsive Coulomb interactions on the thermodynamic properties of the boson-fermion model with an anisotropic (d-wave and extended s-wave) order parameter. Superconductivity is induced in this model from the anisotropic charge exchange interaction between the conduction-band fermions (electrons or holes) and the immobile hard-core bosons (the localized electron pairs). The on-site Coulomb repulsion competes with