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Sample records for coulomb yukawa potentials

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

    NASA Astrophysics Data System (ADS)

    Ho, Y. K.; Kar, S.

    2012-10-01

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

  2. Approximate arbitrary κ-state solutions of Dirac equation with Schiöberg and Manning-Rosen potentials within the coulomb-like Yukawa-like and generalized tensor interactions

    NASA Astrophysics Data System (ADS)

    Ikot, Akpan N.; Hassanabadi, Hassan; Obong, Hillary Patrick; Mehraban, H.; Yazarloo, Bentol Hoda

    2015-07-01

    The effects of Coulomb-like tensor (CLT), Yukawa-like tensor (YLT) and generalized tensor (GLT) interactions are investigated in the Dirac theory with Schiöberg and Manning-Rosen potentials within the framework of spin and pseudospin symmetries using the Nikiforov-Uvarov method. The bound state energy spectra and the radial wave functions have been approximately obtained in the case of spin and pseudospin symmetries. We have also reported some numerical results and figures to show the effects these tensor interactions.

  3. Eigensolutions of the Schrödinger equation with a class of Yukawa potentials via supersymmetric approach

    NASA Astrophysics Data System (ADS)

    Onate, C. A.; Ojonubah, J. O.

    2016-03-01

    Using the basic concept of the supersymmetric shape invariance approach and formalism, we obtained an approximate solution of the Schrödinger equation with an interaction of inversely quadratic Yukawa potential, Yukawa potential and Coulomb potential which we considered as a class of Yukawa potentials. By varying the potential strengths, we obtained a solution for Hellmann potential, Yukawa potential, Coulomb potential and inversely quadratic Yukawa potential. The numerical results we obtained show that the interaction of these potentials is equivalent to each of the potential.

  4. Coupling strength in Coulomb and Yukawa one-component plasmas

    SciTech Connect

    Ott, T.; Bonitz, M.; Stanton, L. G.; Murillo, M. S.

    2014-11-15

    In a non-ideal classical Coulomb one-component plasma (OCP), all thermodynamic properties are known to depend only on a single parameter—the coupling parameter Γ. In contrast, if the pair interaction is screened by background charges (Yukawa OCP) the thermodynamic state depends, in addition, on the range of the interaction via the screening parameter κ. How to determine in this case an effective coupling parameter has been a matter of intensive debate. Here we propose a consistent approach for defining and measuring the coupling strength in Coulomb and Yukawa OCPs based on a fundamental structural quantity, the radial pair distribution function (RPDF). The RPDF is often accessible in experiments by direct observation or indirectly through the static structure factor. Alternatively, it is directly computed in theoretical models or simulations. Our approach is based on the observation that the build-up of correlation from a weakly coupled system proceeds in two steps: First, a monotonically increasing volume around each particle becomes devoid of other particles (correlation hole), and second (upon further increase of the coupling), a shell structure emerges around each particle giving rise to growing peaks of the RPDF. Using molecular dynamics simulation, we present a systematic study for the dependence of these features of the RPDF on Γ and κ and derive a simple expression for the effective coupling parameter.

  5. Yukawa particles in a confining potential

    SciTech Connect

    Girotto, Matheus Levin, Yan; Santos, Alexandre P. dos; Colla, Thiago

    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.

  6. Using the Screened Coulomb Potential to Illustrate the Variational Method

    ERIC Educational Resources Information Center

    Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

    2012-01-01

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

  7. Phenomenological calculation of nuclear binding energy and density with Yukawa-potentials

    NASA Astrophysics Data System (ADS)

    Scheid, W.

    2016-01-01

    In this paper, we study a phenomenological collective model for the calculation of the nuclear density and ground state binding energy of nuclei. The proton density is assumed proportional to the nuclear density. The total binding energy of the nuclear matter consists of the binding energy of infinite nuclear matter, of two Yukawa-potentials, of the Coulomb-energy and of the symmetry-energy. The parameters of the Yukawa-potential are fitted with the Bethe-Weizsäcker (BW) mass formula. The resulting binding energies and nuclear densities agree quite satisfying with known nuclear values.

  8. The effects of hyper-spherical approximation of Yukawa potential to diffusion properties

    NASA Astrophysics Data System (ADS)

    Kim, In Gee; Murillo, Michael S.

    2015-11-01

    The effects of Yukawa potential to the diffusion properties of binary ionic mixtures are investigated in terms of both the classical molecular dynamics and the kinetic theory. The Yukawa interatomic potential is treated by means of the hyper-spherical approximation, which replaces the Ewald summation by a multiple of the hyperbolic trigonometric functions and the lattice summation of screening. The influence of the hyper-spherical approximation of the Yukawa potential is able to be understood through the calculations of transport coefficients with the relationship to Coulomb logarithm. Numerical studies over a various range of the Debye-Hückel screening parameter and of the plasma coupling parameter to binary ionic mixtures will be provided. We consider primarily the interdiffusion coefficients and then discuss about the mixing properties of self-diffusion coefficients.

  9. Energies of Screened Coulomb Potentials.

    ERIC Educational Resources Information Center

    Lai, C. S.

    1979-01-01

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

  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 the column version of matrix-vector multiplication with the row version. The matrix here, however, is in compressive representation. Sufficient care is taken in the revision not to alter the algorithmic complexity or numerical behavior, as concurrent writing potentially takes place in the upward calculation of the multipole expansion coefficients, interactions at every level of the FMM tree, and downward calculation of the local expansion coefficients. The software modules and their compositions are also organized according to the stages they are used. Demonstration files and makefiles for merging the user routines and the library routines are provided. Restrictions: Accuracy requirement is described in terms of three or six digits. Higher multiples of three digits will be allowed in a later version. Finer decimation in digits for accuracy specification may or may not be necessary. Unusual features: Ready and friendly for customized use and instrumental in expression of concurrency and dependency for efficient parallelization. Running time: The running time depends linearly on the number N of particles, and varies with the distribution characteristics of the particle distribution. It also depends on the accuracy requirement, a higher accuracy requirement takes relatively longer time. The code outperforms the direct summation method when N⩾750.

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

    SciTech Connect

    Baruah, Swati; Das, Nilakshi

    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.

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

    NASA Astrophysics Data System (ADS)

    Baruah, Swati; Das, Nilakshi

    2011-09-01

    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 Γ and screening parameter κ. 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 κ. 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.

  13. Accurate momentum transfer cross section for the attractive Yukawa potential

    SciTech Connect

    Khrapak, S. A.

    2014-04-15

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

  14. Scaling behavior of the Yukawa potential in two and three dimensions: a comparative study

    NASA Astrophysics Data System (ADS)

    Abdelmonem, M. S.; Al-Marzoug, S. M.; Abdel-Hady, Afaf; Nasser, I.

    2015-05-01

    By using the Laguerre basis in two and three dimensions, we report the scaling behavior of the bound state energies associated with the Yukawa potential. The energy spectrum crossover phenomenon is shown to exist through the scaling law for bound state energies ?ft| n\\ell \\right> , at different principal quantum numbers n and the angular momentum \\ell , as we approach the continuum. It is found that the bound/resonance phase transitions in ?ft| n1 \\right> and ?ft| n2 \\right> states are of the first order, while it is higher in the case of ?ft| n0 \\right> states. Few physical phenomena, such as the dipole matrix element, the oscillator strength and the transition probabilities for the Yukawa potential are calculated in both two and three dimensions, and then compared with the analytic Coulomb potential. A comparison is made between the two- and three-dimensional cases. This method has a potential application in predicting stable and metastable nuclear, molecular, atomic and graphene states.

  15. How Yukawa balls expand

    NASA Astrophysics Data System (ADS)

    Piel, Alexander; Bockwoldt, Tim; Goree, John

    2013-10-01

    Yukawa balls are spherical arangements of highly charged microparticles in a complex (dusty) plasma, which are confined in a potential trap and interact by shielded Coulomb forces. When the confinement is switched off, the particle cloud expands rapidly. The analogous process of Coulomb explosions of a xenon nanocluster that has been completely stripped of electrons by a femtosecond laser pulse, see e.g., is an established technique to produce energetic ions. Coulomb explosions represent a self-similar expansion process. In this contribution we demonstrate that the expansion of a Yukawa system is governed by a different principle. Because of the shielding, the expansion starts as blow-off of the surface layer and continues by the inward propagation of a rarefactive wave, which delays the blow-off of deeper layers. The differences between Coulomb explosions and Yukawa expansions are investigated by Molecular Dynamics simulations and analytical models. Work supported by DFG within the Transregional Collaborative Research Centre TR-24, project A2.

  16. 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)

  17. Glass-transition properties of Yukawa potentials: from charged point particles to hard spheres.

    PubMed

    Yazdi, Anoosheh; Ivlev, Alexei; Khrapak, Sergey; Thomas, Hubertus; Morfill, Gregor E; Löwen, Hartmut; Wysocki, Adam; Sperl, Matthias

    2014-06-01

    The glass transition is investigated in three dimensions for single and double Yukawa potentials for the full range of control parameters. For vanishing screening parameter, the limit of the one-component plasma is obtained; for large screening parameters and high coupling strengths, the glass-transition properties cross over to the hard-sphere system. Between the two limits, the entire transition diagram can be described by analytical functions. Unlike other potentials, the glass-transition and melting lines for Yukawa potentials are found to follow shifted but otherwise identical curves in control-parameter space. PMID:25019902

  18. Cosmological model with fermion and tachyon fields interacting via Yukawa-type potential

    NASA Astrophysics Data System (ADS)

    Ribas, Marlos O.; Devecchi, Fernando P.; Kremer, Gilberto M.

    2016-02-01

    A model for the universe with tachyonic and fermionic fields interacting through a Yukawa-type potential is investigated. It is shown that the tachyonic field answers for the initial accelerated regime and for the subsequent decelerated regime so that it behaves as an inflaton at early times and as a matter field at intermediate times, while the fermionic field has the role of a dark energy constituent, since it leads to an accelerated regime at later times. The interaction between the fields via a Yukawa-type potential controls the duration of the decelerated era, since a stronger coupling makes a shorter decelerated period.

  19. Spinless particles in the field of unequal scalar—vector Yukawa potentials

    NASA Astrophysics Data System (ADS)

    Hamzavi, M.; M. Ikhdair, S.; E. Thylwe, K.

    2013-04-01

    We present analytical bound state solutions of the spin-zero Klein—Gordon (KG) particles in the field of unequal mixture of scalar and vector Yukawa potentials within the framework of the approximation scheme to the centrifugal potential term for any arbitrary l-state. The approximate energy eigenvalues and unnormalized wave functions are obtained in closed forms using a simple shortcut of the Nikiforov—Uvarov (NU) method. Further, we solve the KG—Yukawa problem for its exact numerical energy eigenvalues via the amplitude phase (AP) method to test the accuracy of the present solutions found by using the NU method. Our numerical tests using energy calculations demonstrate the existence of inter-dimensional degeneracy amongst the energy states of the KG—Yukawa problem. The dependence of the energy on the dimension D is numerically discussed for spatial dimensions D = 2-6.

  20. Quantum gravity and the Coulomb potential

    SciTech Connect

    Husain, Viqar; Winkler, Oliver; Louko, Jorma

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

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

    PubMed

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

    2010-01-21

    In this work we apply the discrete perturbation theory [A. L. Benavides and A. Gil-Villegas, Mol. Phys. 97, 1225 (1999)] to obtain an equation of state for the case of two continuous potentials: the hard-core attractive Yukawa potential and the hard-core repulsive Yukawa potential. The main advantage of the presented equation of state is that it is an explicit analytical expression in the parameters that characterize the intermolecular interactions. With a suitable choice of their inverse screening length parameter one can model the behavior of different systems. This feature allows us to make a systematic study of the effect of the variation in the parameters on the thermodynamic properties of this system. We analyze single phase properties at different conditions of density and temperature, and vapor-liquid phase diagrams for several values of the reduced inverse screening length parameter within the interval kappa( *)=0.1-5.0. The theoretical predictions are compared with available and new Monte Carlo simulation data. Good agreement is found for most of the cases and better predictions are found for the long-range ones. The Yukawa potential is an example of a family of hard-core plus a tail (attractive or repulsive) function that asymptotically goes to zero as the separations between particles increase. We would expect that similar results could be found for other potentials with these characteristics. PMID:20095742

  3. Positron scattering from hydrogen atom with screened Coulomb potentials

    SciTech Connect

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

    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.

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

    PubMed

    Gazzillo, Domenico

    2011-03-28

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

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

    PubMed

    Trokhymchuk; Orozco; Pizio; Vlachy

    1998-11-15

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

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

    SciTech Connect

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

    2010-03-01

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

  7. A heuristic rule for classification of classical fluids: Master curves for Mie, Yukawa and square-well potentials

    NASA Astrophysics Data System (ADS)

    Orea, Pedro; Varga, Szabolcs; Odriozola, Gerardo

    2015-07-01

    A shift of the vapor-liquid coexistence curves by the critical value of the reduced second virial coefficient yields striking data collapses to define master curves. This is observed for the Mie, Yukawa and square-well fluids of different attractive ranges. This modification of the extended corresponding-states law of Noro and Frenkel strongly improves the outcomes from the van der Waals principle. Moreover, this shifted extended principle makes the master curves from Mie and Yukawa potentials to be one on top of the other. The square-well potential forms two well defined master curves, each one corresponding to different effective critical exponents.

  8. Analytical Solution of Relativistic Few-Body Bound Systems with a Generalized Yukawa Potential

    NASA Astrophysics Data System (ADS)

    Aslanzadeh, M.; Rajabi, A. A.

    2016-03-01

    We have investigated in this paper the few-body bound systems in a simple semi-relativistic scheme. For this aim, we introduced a spin independent relativistic description for a few-identical body system by presenting the analytical solution of few-particle Klein-Gordon equation. Performing calculations in D-dimensional configuration on the basis of the hypercentral approach, we reduced the few-body Klein-Gordon equation to a Schrödinger-like form. This equation is solved by using the Nikiforov-Uvarov method, through which the energy equations and eigenfunctions for a few-body bound system are obtained. We used the spin- and isospin-independent generalized Yukawa potential in our calculations, and the dependence of the few-body binding energies on the potential parameters has been investigated.

  9. Coulomb scattering of Weyl fermions through a potential barrier

    NASA Astrophysics Data System (ADS)

    Khan, Mahtab; Leuenberger, Michael; Nano Science Team

    2014-03-01

    We investigate the effects of the Coulomb interaction on the two-dimensional relativistic quantum-mechanical scattering of two Weyl fermions, injected on the opposite sides of a potential barrier. We consider the Coulomb interaction in the standard two-body problem and evaluate the corresponding scattering amplitude. We apply our formalism to describe the scattering of Weyl fermions in two-dimensional materials exhibiting Dirac cones, such as graphene and the surface of 3d topological insulators. We obtain a complex shape for the scattering amplitude due to the angle-dependent Klein tunneling through a potential barrier. We show that the Coulomb interaction leads to shifts and broadenings of the transmission peaks. .

  10. Electron interactions in graphene through an effective Coulomb potential

    NASA Astrophysics Data System (ADS)

    Rodrigues, Joao N. B.; Adam, Shaffique

    A recent numerical work [H.-K. Tang et al, PRL 115, 186602 (2015)] considering graphene's π-electrons interacting through an effective Coulomb potential that is finite at short-distances, stressed the importance of the sp2 -electrons in determining the semimetal to Mott insulator phase transition in graphene. Some years ago, I. F. Herbut [PRL 97, 146401 (2006)] studied such a transition by mapping graphene's π-electrons into a Gross-Neveu model. From a different perspective, D. T. Son [PRB 75, 235423 (2007)] put the emphasis on the long-range interactions by modelling graphene as Dirac fermions interacting through a bare Coulomb potential. Here we build on these works and explore the phase diagram of Dirac fermions interacting through an effective Coulomb-like potential screened at short-distances. The interaction potential used allows for analytic results that controllably switch between the two perspectives above. This work was supported by the Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM medium-sized centre program) and by the Singapore Ministry of Education and Yale-NUS College (R-607-265-01312).

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  12. Hexaquark states as possible candidates for di-baryonic molecular states with Yukawa potential in a semi-relativistic scheme

    NASA Astrophysics Data System (ADS)

    Patel, Smruti J.; Vinodkumar, P. C.

    2016-05-01

    We study the mass spectra of hexaquark states as di-hadronic molecules with Yukawa potential in a semi-relativistic scheme. We have solved numerically the relevant equation using mathematica notebook of Range-Kutta method including effective Yukawa like potential between two baryons to model the two-body interaction and have calculated their masses and binding energy. We have been able to assign the JP values for many of the exotic states according to their compositions. We have predicted some of the di-baryonic exotic states for which experimental as well as theoretical data are not available and we look forward to see the experimental support in favour of our predictions. So in the absence of such results our predictions can be used as guidelines for future experimental and theoretical analysis of exotic states.

  13. 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 к 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.

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

    SciTech Connect

    Bhattacharjee, Saurav; Das, Nilakshi

    2012-10-15

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

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

    SciTech Connect

    Popovici, Carina; Watson, Peter; Reinhardt, Hugo

    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.

  16. Solid-liquid phase transitions in 3D systems with the inverse-power and Yukawa potentials

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The melting of face-centered cubic (fcc) and body-centered cubic (bcc) crystal lattices was studied analytically and numerically for the systems of particles interacting via the inverse-power-law and Yukawa potentials. New approach is proposed for determination of the solid-liquid phase transitions in these systems. The suggested approach takes into account a nonlinearity (anharmonicity) of pair interaction forces and allows to correctly predict the conditions of melting of the systems with various isotropic pair interaction potentials. The obtained results are compared with the existing theoretical and numerical data.

  17. Structure and confinement of Coulomb balls

    NASA Astrophysics Data System (ADS)

    Arp, O.

    2005-10-01

    Coulomb balls [2] are spherical dust clouds of a few hundred micrometer sized particles embedded in a plasma environment. Due to their large negative charge these particles are strongly coupled and can form crystalline structures. Coulomb balls have an unusual crystal structure with nested spherical shells. This contribution presents experiments and simulations on structural properties and trapping of these Coulomb balls. By means of particle imaging velocimetry the contribution of different forces to the confinement is investigated. It is shown that a proper combination of gravity, thermophoresis and electric fields leads to a stable confinement potential. Further, a comparison of experiments with molecular dynamics simulations shows that the structural properties of Coulomb balls require a description based on Yukawa interaction of individual particles.[1] O. Arp et al, Phys. Rev. Lett. 63, 165004 (2004)

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

    SciTech Connect

    Avrigeanu, M.; Avrigeanu, V.

    2010-03-15

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

  19. LETTERS AND COMMENTS: Comment on 'Vector potential of the Coulomb gauge'

    NASA Astrophysics Data System (ADS)

    Hnizdo, V.

    2004-03-01

    The expression for the Coulomb-gauge vector potential in terms of the 'instantaneous' magnetic field derived by Stewart (2003 Eur. J. Phys. 24 519) by employing Jefimenko's equation for the magnetic field and Jackson's formula for the Coulomb-gauge vector potential can be proven much more simply. This comment is written by V Hnizdo in his private capacity. No support or endorsement by the Centers for Disease Control and Prevention is intended or should be inferred.

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

    SciTech Connect

    Barakat, T.

    2009-03-15

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

  1. Deflections of photoelectron classical trajectories in screened Coulomb potentials of H2+

    NASA Astrophysics Data System (ADS)

    Qin, Bo-Ya; Wang, Pei-Jie; He, Feng

    2015-11-01

    The photoelectron momentum distribution of in circularly polarized laser fields is studied based on classical trajectory calculations. We screen Coulomb potentials at different radii, and trace trajectories of an ensemble of electrons in such screened Coulomb potentials and circularly polarized laser fields. Simulations show that electron trajectories are bent by Coulomb fields, resulting in the laser-intensity-dependent drift of photoelectron momentum distributions in the laser polarization plane. This study intuitively explains how Coulomb potentials modify photoelectron momenta. Project supported by the National Natural Science Foundation of China (Grant Nos. 11104180, 11175120, 11121504, and 11322438) and the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China (Grant No. 131010).

  2. 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.

  3. Study of the Cox-Thompson inverse scattering method with a Coulomb potential

    NASA Astrophysics Data System (ADS)

    Hilk, Daniel; Scheid, Werner; Palmai, Tamas; Apagyi, Barnabas

    2010-06-01

    In order to learn more about the precision of the inversion by the Cox-Thompson method, we investigated the inversion of phase shifts of a singular potential, namely of a Coulomb potential. Using asymptotically Riccati-Bessel functions as reference functions, we could only approximately reproduce the singularity of the Coulomb potential at the origin. We also show uncertainties in the inverted potential due to different minima in the minimization solution of the nonlinear equations of the Cox-Thompson procedure. As a result, we conclude that one has to take much care with the inversion of experimental phase shifts suffering from measurement errors.

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

    SciTech Connect

    Bakke, K. Furtado, C.

    2015-04-15

    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. - Highlights: • Interaction between the Klein–Gordon oscillator and a modified mass term. • Relativistic bound states for both attractive and repulsive Coulomb-type potentials. • Dependence of the Klein–Gordon oscillator frequency on the quantum numbers. • Relativistic analogue of a position-dependent mass system.

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

    NASA Astrophysics Data System (ADS)

    Khalilov, V. R.

    2013-08-01

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

  6. Extending the class of solvable potentials: II. Screened Coulomb potential with a barrier

    NASA Astrophysics Data System (ADS)

    Alhaidari, A. D.

    2010-02-01

    This is the second paper in a series where we succeed in enlarging the class of solvable problems in one and three dimensions. We do that by working in a complete square integrable basis that carries a tridiagonal matrix representation of the wave operator. Consequently, the wave equation becomes equivalent to a three-term recursion relation for the expansion coefficients of the wavefunction in the basis. Finding solutions of the recursion relation is equivalent to solving the original problem. This method gives a larger class of solvable potentials. The usual diagonal representation constraint results in a reduction to the conventional class of solvable potentials. However, the tridiagonal requirement allows only very few and special potentials to be added to the solvability class. In the present work, we obtain S-wave solutions for a three-parameter 1/r singular but short-range potential with a nonorbital barrier and study its energy spectrum. We argue that it could be used as a more appropriate model for the screened Coulomb interaction of an electron with extended molecules. We give also its resonance structure for nonzero angular momentum. Additionally, we plot the phase shift for an electron scattering off a molecule modeled by a set of values of the potential parameters.

  7. Effective Screened Coulomb Potential from e-- e- to 208Pb -208Pb Systems

    NASA Astrophysics Data System (ADS)

    Watanabe, Takashi; Hiratsuka, Yasuhisa; Oryu, Shinsho

    2016-03-01

    We confirmed that the Coulomb phase shifts can not be given with a screened Coulomb potential by a monotonic increase of the range R. However, several screening "discrete range-bands" reproduce the Coulomb phase shift in a wide energy region. If the range-band of a proton-proton system for example is obtained, then the range-bands are generalized by three universal arguments: the universal range R(k)(≡ kR), the Sommerfeld parameter η(k)(≡ Z1Z2e2ν/k), and the universal asymptotic phase F(k)(≡ 2krc). Finally, the phase shifts of any other systems from e--e- to heavy ions such as 208Pb-208Pb can be reproduced automatically by an individual range R = R(k)/k on the universal range-bands R(k).

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

    SciTech Connect

    Tanoudis, Y.; Daskaloyannis, C.

    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.

  9. Potential splitting approach to the three-body Coulomb scattering problem

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    The potential splitting technique is developed for solving the three-body Coulomb scattering problem. The formalism is applied to e+-H and e+-He+ scattering problems. Calculated phase shifts and the annihilation rate parameter Z\\text{eff} are in fairly good agreement with the most accurate results available in the literature.

  10. Symmetrization of the Coulomb pairing potential by electron-phonon interaction

    SciTech Connect

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

    2012-08-15

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

  11. Virial theorem and Gibbs thermodynamic potential for Coulomb systems

    SciTech Connect

    Bobrov, V. B. E-mail: satron@mail.ru; Trigger, S. A. E-mail: satron@mail.ru

    2014-10-15

    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.

  12. The influence of Coulomb potential fluctuation on c-axis tunneling in cuprates

    NASA Astrophysics Data System (ADS)

    Pham, Minh Tuan

    The subject of this thesis is studying the resistivity along c-axis direction in cuprates, layered high-temperature superconducting materials as a function of temperature. A point-to-point tunneling model is built to describe the tunneling between two CuO2 planes including the in-plane Coulomb interaction. With a general assumption that the spectral function of the Coulomb fluctuation is ohmic, the solution of the transmission rate in the model is obtained by mapping the Coulomb potential fluctuation to phonon coupling of the spin-boson model. From the result of the transmission rate, the c-axis resistivity is calculated in both gapless and gap cases as a function of the temperature and the strength of the Coulomb fluctuation. The dimensionless parameter alpha characterizing the strength of the Coulomb fluctuation is calculated theoretically in the random-phase approximation (RPA) and in the Landau-Fermi liquid theory. The extensions of the calculation to include the Coulomb interaction between CuO 2 planes are done in this thesis to get a better description of c-axis transport for double-layered cuprates and single-layered cuprates. It turns out the theoretical form of the c-axis resistivity fits quite well with experimental data in both the metallic (gapless) region and the metal-insulator crossover (pseudogap) region of the c-axis resistivity. The parameter alpha in the fitting is also compared with the solution in the RPA calculation. It shows that the RPA result of alpha is reasonably good in gapless case but fails in gap case. An extension for the future work about a multi-channel tunneling model is discussed in the last part of the thesis.

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

    PubMed

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

    2013-02-01

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

  14. Coulomb potential V (r )=1 /r problem on the Bethe lattice

    NASA Astrophysics Data System (ADS)

    Petrova, Olga; Moessner, Roderich

    2016-01-01

    We study the problem of a particle hopping on the Bethe lattice in the presence of a Coulomb potential. We obtain an exact solution to the particle's Green's function along with the full energy spectrum. In addition, we present a mapping of a generalized radial potential problem defined on the Bethe lattice to an infinite number of one-dimensional problems that are easily accessible numerically. The latter method is particularly useful when the problem admits no analytical solution.

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

    SciTech Connect

    Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-26

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

  16. The 6He Optical Potential at energies around the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Rodríguez-Gallardo, M.; Alvarez, M. A. G.; Moro, A. M.

    2010-04-01

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

  17. Vacuum polarization of planar charged fermions with Coulomb and Aharonov-Bohm potentials

    NASA Astrophysics Data System (ADS)

    Khalilov, V. R.; Mamsurov, I. V.

    2016-02-01

    Vacuum polarization of charged massless fermions is investigated in the superposition of Coulomb and Aharonov-Bohm (AB) potentials in 2 + 1 dimensions. For this purpose, we construct the Green function of the two-dimensional Dirac equation with Coulomb and AB potentials (via the regular and irregular solutions of the radial Dirac equation) and then calculate the vacuum polarization charge density in the so-called subcritical and supercritical regimes. In the supercritical regime, the Green function has a discontinuity in the complex plane of “energy” due to the singularities on the negative energy axis; these singularities are situated on the unphysical sheet and related to the creation of infinitely many quasistationary fermionic states with negative energies. We expect that our results will be helpful in gaining deeper understanding of the fundamental problem of quantum electrodynamics which can be applied to the problems of charged impurity screening in graphene taking into consideration the electron spin.

  18. Simple unified derivation and solution of Coulomb, Eckart and Rosen-Morse potentials in prepotential approach

    SciTech Connect

    Ho, Choon-Lin

    2009-05-15

    The four exactly solvable models related to non-sinusoidal coordinates, namely, the Coulomb, Eckart, Rosen-Morse type I and II models are normally being treated separately, despite the similarity of the functional forms of the potentials, their eigenvalues and eigenfunctions. Based on an extension of the prepotential approach to exactly and quasi-exactly solvable models proposed previously, we show how these models can be derived and solved in a simple and unified way.

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

    SciTech Connect

    Giacometti, Achille; Gazzillo, Domenico; Pastore, Giorgio; Das, Tushar Kanti

    2005-03-01

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

  20. Madelung energy of Yukawa lattices.

    PubMed

    Pereira, P C N; Apolinario, S W S

    2012-10-01

    We propose a method to obtain an approximate closed form expression for the Madelung energy (ME) of Yukawa lattices. Such a method is applied for lattices of different topologies and dimensions. The obtained Madelung energies have a satisfactory accuracy for all ranges of the screening parameter κ of the Yukawa potential, and it becomes exact in the asymptotic limits κ→0 and κ→+∞. For instance, for the triangular lattice, the maximum relative error of the ME given by the method is about 0.0047. Also, satisfactory results are obtained for the one-component plasma limit. The Madelung constants of the two-dimensional hexagonal BN and square NaCl and the three-dimensional cubic NaCl crystals are estimated with a relative error of 0.004, 0.006, and 0.03, respectively. Finally, different ways to improve the method are presented and discussed. PMID:23214705

  1. 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.

  2. Solution of D dimensional Dirac equation for coulombic potential using NU method and its thermodynamics properties

    NASA Astrophysics Data System (ADS)

    Cari, C.; Suparmi, A.; Yunianto, M.; Husein, A. S.

    2016-02-01

    The analytical solution of Ddimensional Dirac equation for Coulombic potential is investigated using Nikiforov-Uvarov method. The D dimensional relativistic energy spectra are obtained from relativistic energy eigenvalue equation by using Mat Lab software.The corresponding D dimensional radial wave functions are formulated in the form of generalized Jacobi and Laguerre Polynomials. In the non-relativistic limit, the relativistic energy equation reduces to the non-relativistic energy which will be applied to determine some thermodynamical properties of the system. The thermodynamical properties of the system are expressed in terms of error function and imaginary error function.

  3. Algebraic Calculation of the Energy Eigenvalues for the Nondegenerate Three-Dimensional Kepler-Coulomb Potential

    NASA Astrophysics Data System (ADS)

    Tanoudis, Yannis; Daskaloyannis, Costas

    2011-06-01

    In the three-dimensional flat space, a classical Hamiltonian, which has five functionally independent integrals of motion, including the Hamiltonian, is characterized as superintegrable. Kalnins, Kress and Miller (J. Math. Phys. 48 (2007), 113518, 26 pages) have proved that, in the case of nondegenerate potentials, i.e. potentials depending linearly on four parameters, with quadratic symmetries, posses a sixth quadratic integral, which is linearly independent of the other integrals. The existence of this sixth integral imply that the integrals of motion form a ternary quadratic Poisson algebra with five generators. The superintegrability of the generalized Kepler-Coulomb potential that was investigated by Verrier and Evans (J. Math. Phys. 49 (2008), 022902, 8 pages) is a special case of superintegrable system, having two independent integrals of motion of fourth order among the remaining quadratic ones. The corresponding Poisson algebra of integrals is a quadratic one, having the same special form, characteristic to the nondegenerate case of systems with quadratic integrals. In this paper, the ternary quadratic associative algebra corresponding to the quantum Verrier-Evans system is discussed. The subalgebras structure, the Casimir operators and the the finite-dimensional representation of this algebra are studied and the energy eigenvalues of the nondegenerate Kepler-Coulomb are calculated.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  5. Biography of Hideki Yukawa

    NASA Astrophysics Data System (ADS)

    Sato, Humitaka

    2008-06-01

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

  6. Hyperpolarizability of two electron atoms under exponential cosine screened coulomb potential

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Supriya K.; Mukherjee, Prasanta K.; Fricke, Burkhard

    2015-12-01

    Hyperpolarizability of two electron atoms He, Li+, B e2 +, B3 + , and C4 + embedded under quantum plasma environment has been calculated for the first time using exponential cosine screened coulomb potential (ECSCP) arising out of the interaction of atomic charge cloud with such an environment. Coupled Hartree-Fock theory within variational scheme has been utilised to estimate such nonlinear optical property for systematic variation of the screening parameter arising out of the coupling strength of the plasma with atomic charge cloud. Hyperpolarizability of the ions increases systematically with increase of the screening parameter. Results have been compared with respect to those obtained from the interaction of atomic systems with a Debye plasma environment giving rise to SCP. Interesting feature is observed for the polarizability and hyperpolarizability values under increasing screening parameters of ECSCP and SCP. Hyperpolarizability values for zero screening compare well with those available for the free ions.

  7. Molecular dynamics simulation of electron-ion temperature relaxation in dense hydrogen: A scheme of truncated Coulomb potential

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Top Yukawa deviation in extra dimension

    NASA Astrophysics Data System (ADS)

    Haba, Naoyuki; Oda, Kin-ya; Takahashi, Ryo

    2009-11-01

    We suggest a simple one-Higgs-doublet model living in the bulk of five-dimensional spacetime compactified on S/Z, in which the top Yukawa coupling can be smaller than the naive standard-model expectation, i.e. the top quark mass divided by the Higgs vacuum expectation value. If we find only single Higgs particle at the LHC and also observe the top Yukawa deviation, our scenario becomes a realistic candidate beyond the standard model. The Yukawa deviation comes from the fact that the wave function profile of the free physical Higgs field can become different from that of the vacuum expectation value, due to the presence of the brane-localized Higgs potentials. In the Brane-Localized Fermion scenario, we find sizable top Yukawa deviation, which could be checked at the LHC experiment, with a dominant Higgs production channel being the WW fusion. We also study the Bulk Fermion scenario with brane-localized Higgs potential, which resembles the Universal Extra Dimension model with a stable dark matter candidate. We show that both scenarios are consistent with the current electroweak precision measurements.

  9. Ground state and resonant states of helium in exponential cosine screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Ghoshal, Arijit; Ho, Y. K.

    2009-05-01

    We have investigated the ground state and a resonance state of normal helium atom in exponential cosine screened Coulomb potential (ECSCP) with screening parameterλ: V(r),,,1r,^-λr(λr) (in a.u.), where r denotes the inter-particle distance. Within the framework of Ritz's variational principle and making use of a highly correlated wave function, we have determined the ground state energies and wave functions of the helium atom for different values of the screening parameterλ. Furthermore, we have shown that the ground state energy of helium for a particular value of λ does converge with increasing number of terms in the wave function. In addition, using the stabilization method, we have investigated the doubly excited 2s^2 ^1S^e resonance state in helium with ECSCP. Resonance energy and width for various λ values are calculated. Our present work will play a useful role in the investigations of atomic structures in quantum plasmas [1]. [1]. P.K. Shukla and B. Eliasson, Phys. Lett. A 372, 2899 (2008).

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

    SciTech Connect

    Rakityansky, S. A.; Elander, N.

    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.

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

    NASA Astrophysics Data System (ADS)

    Rakityansky, S. A.; Elander, N.

    2013-12-01

    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.

  12. 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.

  13. Effective Coulomb logarithm for one component plasma

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.

    2013-05-01

    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.

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

    SciTech Connect

    Nagy, I.

    2011-04-15

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

  15. Coulomb Green's function and image potential near a cylindrical diffuse interface

    NASA Astrophysics Data System (ADS)

    Xue, Changfeng; Huang, Qiongwei; Deng, Shaozhong

    2015-12-01

    In a preceding paper [Comput. Phys. Commun. 184 (1): 51-59, 2013], we revisited the problem of calculating Coulomb Green's function and image potential near a planar diffuse interface within which the dielectric permittivity of the inhomogeneous medium changes continuously along one Cartesian direction in a transition layer between two dissimilar dielectric materials. In the present paper, we consider a cylindrical diffuse interface within which the dielectric permittivity changes continuously along the radial direction instead. First we propose a specific cylindrical diffuse interface model, termed the quasi-harmonic diffuse interface model, that can admit analytical solution for the Green's function in terms of the modified Bessel functions. Then and more importantly we develop a robust numerical method for building Green's functions for any cylindrical diffuse interface models. The main idea of the numerical method is, after dividing a diffuse interface into multiple sublayers, to approximate the dielectric permittivity profile in each one of the sublayers by one of the quasi-harmonic functional form rather than simply by a constant value as one would normally do. Next we describe how to efficiently compute well-behaved ratios, products, and logarithmic derivatives of the modified Bessel functions so as to avoid direct evaluations of individual modified Bessel functions in our formulations. Finally we conduct numerical experiments to show the effectiveness of the quasi-harmonic diffuse interface model in overcoming the divergence of the image potential, to validate the numerical method in terms of its accuracy and convergence, and to demonstrate its capability for computing Green's functions for any cylindrical diffuse interface models.

  16. EFFECT OF COULOMB COLLISIONS ON THE GRAVITATIONAL SETTLING OF LOW AND HIGH FIRST IONIZATION POTENTIAL ELEMENTS

    SciTech Connect

    Bo, Iselin M. Th.; Esser, Ruth; Lie-Svendsen, Oystein E-mail: ruth.esser@uit.no

    2013-05-20

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

  17. Mie and potential scattering by a refractive 1/r inhomogeneity: Electromagnetic scattering by an infinite Coulomb-like scatterer

    NASA Astrophysics Data System (ADS)

    Selmke, Markus

    2015-09-01

    The weak electromagnetic scattering of a special type of gradient index scatterer resembles the situation of charged particle scattering off an electrostatic Coulomb potential. Accordingly, plane-wave scattering for a radially symmetric decaying perturbation of the refractive index n(r) =n0 - ν /k0 r is studied. The experimental realization of this specific scattering is found in photothermal single particle microscopy. Vectorial scattering in Lorenz-Mie theory recovers the properties in the Born approximation of the corresponding potential scattering scenario. Shaped beams within the generalized Lorenz-Mie theory are found to resolve known pathologic properties of the problematic 1/r potential.

  18. The Coulomb interaction in Helium-3: Interplay of strong short-range and weak long-range potentials

    NASA Astrophysics Data System (ADS)

    Kirscher, J.; Gazit, D.

    2016-04-01

    Quantum chromodynamics and the electroweak theory at low energies are prominent instances of the combination of a short-range and a long-range interaction. For the description of light nuclei, the large nucleon-nucleon scattering lengths produced by the strong interaction, and the reduction of the weak interaction to the Coulomb potential, play a crucial role. Helium-3 is the first bound nucleus comprised of more than one proton in which this combination of forces can be studied. We demonstrate a proper renormalization of Helium-3 using the pionless effective field theory as the formal representation of the nuclear regime as strongly interacting fermions. The theory is found consistent at leading and next-to-leading order without isospin-symmetry-breaking 3-nucleon interactions and a non-perturbative treatment of the Coulomb interaction. The conclusion highlights the significance of the regularization method since a comparison to previous work is contradictory if the difference in those methods is not considered. With a perturbative Coulomb interaction, as suggested by dimensional analysis, we find the Helium-3 system properly renormalized, too. For both treatments, renormalization-scheme independence of the effective field theory is demonstrated by regulating the potential and a variation of the associated cutoff.

  19. Density profile of strongly correlated spherical Yukawa plasmas

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

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

  20. Asymptotic approach to the Schrdinger 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 Schrdinger 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.

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

    NASA Astrophysics Data System (ADS)

    Sameer, M. Ikhdair; Majid, Hamzavi

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 semianalytical, 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 that, 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 very good agreement with the ab initio solution of the time-dependent Schrödinger equation.

  3. Shear viscosity for dense plasmas by equilibrium molecular dynamics in asymmetric Yukawa ionic mixtures

    NASA Astrophysics Data System (ADS)

    Haxhimali, Tomorr; Rudd, Robert E.; Cabot, William H.; Graziani, Frank R.

    2015-11-01

    We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 1025 ions/cc. The motion of 30 000-120 000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We systematically study different mixtures through a series of simulations with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. In the more strongly coupled plasmas, the kinetic theory does not agree well with the MD results. We develop a simple model that interpolates between classical kinetic theories at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated, ranging from moderately weakly coupled to moderately strongly coupled asymmetric plasma mixtures.

  4. Shear viscosity for dense plasmas by equilibrium molecular dynamics in asymmetric Yukawa ionic mixtures.

    PubMed

    Haxhimali, Tomorr; Rudd, Robert E; Cabot, William H; Graziani, Frank R

    2015-11-01

    We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 10^{25} ions/cc. The motion of 30,000-120,000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We systematically study different mixtures through a series of simulations with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. In the more strongly coupled plasmas, the kinetic theory does not agree well with the MD results. We develop a simple model that interpolates between classical kinetic theories at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated, ranging from moderately weakly coupled to moderately strongly coupled asymmetric plasma mixtures. PMID:26651805

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

    SciTech Connect

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

    2015-03-15

    A detailed investigation of the magnetic dipolar and quadrupolar excitation energies and transition probabilities of helium isoelectronic He, Be{sup 2+}, C{sup 4+}, and O{sup 6+} have been performed under exponential cosine screened Coulomb potential generated in a plasma environment. The low-lying excited states 1s{sup 2}:{sup 1}S{sup e} → 1sns:{sup 3}S{sup e}{sub 0}, and 1snp:{sup 3}P{sup o}{sub 2} (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.

  6. Short-range screening potentials for classical Coulomb fluids: Reanalysis of Monte Carlo sampling and cluster model studies

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Yaakov

    1996-02-01

    Results for the short-range screening potentials of classical Coulomb fluids, which were significantly different from existing theory and from earlier approaches, were obtained by Ichimaru et al. by their analyses of extra long simulations. In a recent paper [Phys. Rev. E 50, 2977 (1994)], Ichimaru, Ogata, and Tsuruta (IOT) summarize these results and attempt to support them with more simulations and with cluster model studies. In this paper I present an alternative analysis of the same data, which is in contradiction with the analyses of Ichimaru et al., as portrayed by IOT. I present an analysis of general axially symmetric clusters that is different from that of IOT and provides insight into the short-range screening potentials of strongly coupled plasmas. In particular, I give an exact mathematical proof that questions the main conclusion of IOT from their cluster model studies [their Eq. (49b)].

  7. Holomorphic Yukawa couplings in heterotic string theory

    NASA Astrophysics Data System (ADS)

    Blesneag, Stefan; Buchbinder, Evgeny I.; Candelas, Philip; Lukas, Andre

    2016-01-01

    We develop techniques, based on differential geometry, to compute holomorphic Yukawa couplings for heterotic line bundle models on Calabi-Yau manifolds defined as complete intersections in projective spaces. It is shown explicitly how these techniques relate to algebraic methods for computing holomorphic Yukawa couplings. We apply our methods to various examples and evaluate the holomorphic Yukawa couplings explicitly as functions of the complex structure moduli. It is shown that the rank of the Yukawa matrix can decrease at specific loci in complex structure moduli space. In particular, we compute the up Yukawa coupling and the singlet-Higgs-lepton trilinear coupling in the heterotic standard model described in ref. [32].

  8. Variation of coulombic efficiency versus upper cutoff potential of Li-ion cells tested with aggressive protocols

    NASA Astrophysics Data System (ADS)

    Xia, Jian; Nie, Mengyun; Ma, Lin; Dahn, J. R.

    2016-02-01

    Three different cycling protocols including "continuous-cycling", "barn-charge" and "cycle-store" were applied with an ultra high precision charger to Li[Ni0.42Mn0.42Co0.16]O2/graphite and/or Li[Ni1/3Mn1/3Co1/3]O2/graphite pouch cells tested using different upper cutoff potentials. The barn-charge and cycle-store protocols were designed so that cells stay at high potential for a larger fraction of their testing time compared to continuous cycling. For cells tested to 4.2, 4.4 or 4.5 V, the greater the fraction of testing time spent at high potential, the lower the coulombic efficiency and the greater the charge endpoint capacity slippage rate, with the effects being more severe at higher potential. These results confirm that Li[Ni0.42Mn0.42Co0.16]O2/graphite and Li[Ni1/3Mn1/3Co1/3]O2/graphite Li-ion cells which are charged and then left at high potential (>4.4 V) for extended periods of time will have much shorter calendar and cycle life compared to those that are continuously cycled as has been recently reported in long-term test results.

  9. On the corresponding states law of the Yukawa fluid.

    PubMed

    Orea, Pedro; Duda, Yurko

    2008-04-01

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

  10. Vacuum stability of asymptotically safe gauge-Yukawa theories

    NASA Astrophysics Data System (ADS)

    Litim, Daniel F.; Mojaza, Matin; Sannino, Francesco

    2016-01-01

    We study the phase diagram and the stability of the ground state for certain four-dimensional gauge-Yukawa theories whose high-energy behaviour is controlled by an interacting fixed point. We also provide analytical and numerical results for running couplings, their crossover scales, the separatrix, and the Coleman-Weinberg effective potential. Classical and quantum stability of the vacuum is established.

  11. Dielectric confinement influenced screened Coulomb potential for a semiconductor quantum wire

    NASA Astrophysics Data System (ADS)

    Aharonyan, K. H.; Margaryan, N. B.

    2016-01-01

    A formalism of the Thomas-Fermi method has been applied for studying the screening effect due to quasi-one-dimensional electron gas in a semiconductor cylindrical quantum wire embedded in the barrier environment. With taking into account of strongly low dielectric properties of the barrier material, an applicability of the quantum wire effective interaction potential of the confined charge carriers has been revealed. Both screened quasi- one-dimensional interaction potential and effective screening length analytical expressions are derived in the first time. It is shown that in the long wavelength moderate limit dielectric confinement effect enhances strength of the screening potential depending on the both radius of the wire and effective screening length, whereas in the long wavelength strong limit the screening potential solely is determined by barrier environment dielectric properties.

  12. Mixing parameters of neutral beauty mesons from the Coulomb plus power potential (CPPν)

    NASA Astrophysics Data System (ADS)

    Patel, Bhavin; Vinodkumar, P. C.

    2009-11-01

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

  13. Path Integral Solution for the Coulomb Potential in a Curved Space of Constant Positive Curvature

    NASA Astrophysics Data System (ADS)

    Aggoun, L.; Bounouioua, N.; Benamira, F.; Guechi, L.

    2016-05-01

    A new path integral treatment of a hydrogen-like atom in a uniformly curved space with a constant positive curvature is presented. By converting the radial path integral into a path integral for the modified Pöschl-Teller potential with the help of the space-time transformation technique, the radial Green's function is expressed in closed form, from which the energy spectrum and the corresponding normalized wave functions of the bound states are extracted. In the limit of vanishing curvature, the Green's function, the energy spectra and the correctly normalized wave functions of bound and scattering states for a standard hydrogen-like atom are found.

  14. Path Integral Solution for the Coulomb Potential in a Curved Space of Constant Positive Curvature

    NASA Astrophysics Data System (ADS)

    Aggoun, L.; Bounouioua, N.; Benamira, F.; Guechi, L.

    2016-01-01

    A new path integral treatment of a hydrogen-like atom in a uniformly curved space with a constant positive curvature is presented. By converting the radial path integral into a path integral for the modified Pöschl-Teller potential with the help of the space-time transformation technique, the radial Green's function is expressed in closed form, from which the energy spectrum and the corresponding normalized wave functions of the bound states are extracted. In the limit of vanishing curvature, the Green's function, the energy spectra and the correctly normalized wave functions of bound and scattering states for a standard hydrogen-like atom are found.

  15. Improved Shell models for screened Coulomb balls

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

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

  16. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

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

  17. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

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

  18. Spin and Pseudospin Symmetries of Hellmann Potential with Three Tensor Interactions Using Nikiforov-Uvarov Method

    NASA Astrophysics Data System (ADS)

    Akpan, N. Ikot; Hassan, Hassanabadi; Tamunoimi, M. Abbey

    2015-12-01

    The Dirac equation with Hellmann potential is presented in the presence of Coulomb-like tensor (CLT), Yukawa-like tensor (YLT), and Hulthen-type tensor (HLT) interactions by using Nikiforov-Uvarov method. The bound state energy spectra and the radial wave functions are obtained approximately within the framework of spin and pseudospin symmetries limit. We have also reported some numerical results and figures to show the effects of the tensor interactions. Special cases of the potential are also discussed.

  19. Coulomb breakup problem.

    PubMed

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

    2008-12-01

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

  20. Coulomb crystallization in classical and quantum systems

    NASA Astrophysics Data System (ADS)

    Bonitz, Michael

    2007-11-01

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

  1. Equation of state and critical point behavior of hard-core double-Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Montes, J.; Robles, M.; López de Haro, M.

    2016-02-01

    A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out.

  2. Equation of state and critical point behavior of hard-core double-Yukawa fluids.

    PubMed

    Montes, J; Robles, M; López de Haro, M

    2016-02-28

    A theoretical study on the equation of state and the critical point behavior of hard-core double-Yukawa fluids is presented. Thermodynamic perturbation theory, restricted to first order in the inverse temperature and having the hard-sphere fluid as the reference system, is used to derive a relatively simple analytical equation of state of hard-core multi-Yukawa fluids. Using such an equation of state, the compressibility factor and phase behavior of six representative hard-core double-Yukawa fluids are examined and compared with available simulation results. The effect of varying the parameters of the hard-core double-Yukawa intermolecular potential on the location of the critical point is also analyzed using different perspectives. The relevance of this analysis for fluids whose molecules interact with realistic potentials is also pointed out. PMID:26931708

  3. Quasiparticle weight and renormalized Fermi velocity of graphene with long-range Coulomb interactions

    NASA Astrophysics Data System (ADS)

    Tang, Ho-Kin; Leaw, Jia Ning; Rodrigues, J. N. B.; Sengupta, P.; Assaad, F. F.; Adam, S.

    In this work, we study the effects of realistic Coulomb interactions in graphene using a projective quantum Monte Carlo simulation of electrons at half-filing on a honeycomb lattice. We compute the quasiparticle residue, the renormalized Fermi velocity and the antiferromagnetic order parameter as a function of both the long-range and short-range components of the Coulomb potential. We find that the Mott insulator transition is determined mostly by the short-range interaction and is consistent with the Gross-Neveu-Yukawa critical theory. Far from the critical point and in the semi-metallic regime, we find that the Fermi-velocity and quasiparticle residue are influenced by the long-range tail of the Coulomb potential, and for very small interaction strength are consistent with predictions of first order perturbation theory. For experimentally relevant and stronger values of the long-range interaction, our numerical data contradicts prediction from both perturbation theory and the renormalization group approaches. This work was supported by Singapore National Research Foundation (NRF-NRFF2012-01 and CA2DM mid-size Centre), Singapore Ministry of Education(Yale-NUS College R-607-265-01312 and MOE2014-T2-2-112), and DFG Grant No. AS120/9-1.

  4. Generalized Yukawa PPPM for molecular dynamics simulation of strongly coupled plasmas

    NASA Astrophysics Data System (ADS)

    Dharuman, Gautham; Stanton, Liam; Glosli, James; Verboncoeur, John; Christlieb, Andrew; Murillo, Michael

    2015-11-01

    The Particle-Particle-Particle-Mesh (PPPM) method is an efficient way of treating the Ewald sum for long range interactions in a periodic system. It makes use of the Fast-Fourier-Transform algorithm that scales as O(N logN). In this work we have applied the PPPM method to long range interactions in the weak screening limit of generalized Yukawa interaction to identify the range of screening over which PPPM is computationally more efficient than the minimum image method which is usually usedfor the well-known Yukawa interactions. Generalized Yukawa interaction is obtained by including arbitrary linear dielectric screening in the Yukawa model. In the PPPM method the Fourier space part of the Ewald sum is treated by assigning charges to a mesh and computing the potential using an optimized Green's function that minimizes the discretization errors introduced in the forces.

  5. Asymptotic equivalence of the shell-model and local-density descriptions of Coulombic systems confined by radially symmetric potentials in two and three dimensions.

    PubMed

    Cioslowski, Jerzy; Albin, Joanna

    2013-09-21

    Asymptotic equivalence of the shell-model and local-density (LDA) descriptions of Coulombic systems confined by radially symmetric potentials in two and three dimensions is demonstrated. Tight upper bounds to the numerical constants that enter the LDA expressions for the Madelung energy are derived and found to differ by less than 0.5% from the previously known approximate values. Thanks to the variational nature of the shell-model approximate energies, asymptotic expressions for other properties, such as mean radial positions of the particles and number densities, are also obtained. A conjecture that generalizes the present results to confining potentials with arbitrary symmetries is formulated. PMID:24070281

  6. Minimal SUSY SO(10) and Yukawa unification

    SciTech Connect

    Okada, Nobuchika

    2013-05-23

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

  7. Homogeneous Nonequilibrium Molecular Dynamics Evaluation of Thermal Conductivity in 2D Yukawa Liquids

    NASA Astrophysics Data System (ADS)

    Shahzad, Aamir; He, Mao-Gang

    2015-11-01

    The thermal conductivity of two-dimensional (2D) complex (dusty) plasma liquids (CDPLs) has been explored using a homogenous nonequilibrium molecular dynamics (HNEMD) technique in a canonical ensemble, for the first time. The effects of an external force field along with different plasma parameters of the Coulomb coupling (\\varGamma ) and screening (κ) strengths on the thermal conductivity of CDPLs have been investigated using improved HNEMD simulations. The new simulations show that the thermal conductivity is dependent on the temperature in the 2D Yukawa liquids and provides more reliable results than previously known numerical results. It is shown that a simple analytical temperature representation of Yukawa thermal conductivities with a suitable normalized Einstein frequency is performed. The obtained simulation results are in satisfactory agreement with the earlier nonequilibrium molecular dynamics, equilibrium molecular dynamics simulations, and experimental data, for the whole range of plasma parameters (\\varGamma , κ).

  8. SU(1,1) coherent states for Dirac-Kepler-Coulomb problem in D+1 dimensions with scalar and vector potentials

    NASA Astrophysics Data System (ADS)

    Ojeda-Guillén, D.; Mota, R. D.; Granados, V. D.

    2014-08-01

    We decouple the Dirac's radial equations in D+1 dimensions with Coulomb-type scalar and vector potentials through appropriate transformations. We study each of these uncoupled second-order equations in an algebraic way by using an su(1,1) algebra realization. Based on the theory of irreducible representations, we find the energy spectrum and the radial eigenfunctions. We construct the Perelomov coherent states for the Sturmian basis, which is the basis for the unitary irreducible representation of the su(1,1) Lie algebra. The physical radial coherent states for our problem are obtained by applying the inverse original transformations to the Sturmian coherent states.

  9. Indirect handle on the down-quark Yukawa coupling.

    PubMed

    Goertz, Florian

    2014-12-31

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

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Schll-Paschinger, Elisabeth; Valadez-Prez, Nstor E.; Benavides, Ana L.; Castaeda-Priego, Ramn

    2013-11-01

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

  12. 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.

  13. Introduction to SC-Potential

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin; Christianto, Victor

    2011-03-01

    A new type of potential for nucleus, which is different from Coulomb potential or Yukawa potential, is introduced. This new called Smarandache-Christianto potential may have effect for radius range within r = 5-10 fm. For experimental verification of this potential, we find possible applications in the context of Condensed Matter Nuclear reaction. According to Takahashi's research, it is more likely to get condensed matter nuclear reaction using cluster of deuterium (4D) rather than using D+D reaction (as in hot-fusion, in this process Coulomb barrier is very high). In recent work, Takahashi shows that in the TSC framework it is also possible to do CMNS reaction not only with DDDD, but also with DDDH, DDHH, DHHH, or HHHH, where the reaction can be different. In other words, TSC can be a mixture of heavy and light water (as in neutrosophic logic). More interestingly, his EQPET/TSC (tetrahedra symmetric condensate) model, Takahashi can predict a new potential called STTBA (sudden-tall thin barrier approximate) which includes negative potential (reverse potential) and differs from Coulomb potential. The SC-potential, which has sinusoidal form, can be viewed as a generalization of Takahashi's TSC/STTBA potential.

  14. Constraining the range of Yukawa gravity interaction from S2 star orbits

    SciTech Connect

    Borka, D.; Jovanović, V. Borka; Jovanović, P.; Zakharov, A.F. E-mail: pjovanovic@aob.rs E-mail: zakharov@itep.ru

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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-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.

  16. Non-unique monopole oscillations of harmonically confined Yukawa systems

    NASA Astrophysics Data System (ADS)

    Ducatman, Samuel; Henning, Christian; Kaehlert, Hanno; Bonitz, Michael

    2008-11-01

    Recently it was shown that the Breathing Mode (BM), the mode of uniform radial expansion and contraction, which is well known from harmonically confined Coulomb systems [1], does not exist in general for other systems [2]. As a consequence the monopole oscillation (MO), the radial collective excitation, is not unique, but there are several MO with different frequencies. Within this work we show simulation results of those monopole oscillations of 2-dimensional harmonically confined Yukawa systems, which are known from, e.g., dusty plasma crystals [3,4]. We present the corresponding spectrum of the particle motion, including analysis of the frequencies found, and compare with theoretical investigations.[1] D.H.E. Dubin and J.P. Schiffer, Phys. Rev. E 53, 5249 (1996)[2] C. Henning at al., accepted for publication in Phys. Rev. Lett. (2008)[3] A. Melzer et al., Phys. Rev. Lett. 87, 115002 (2001)[4] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)

  17. Separation of Wigner structures for two-dimensional equimolar binary mixtures of Coulomb particles

    NASA Astrophysics Data System (ADS)

    Travěnec, Igor; Šamaj, Ladislav

    2016-03-01

    We study the lowest energy configurations of an equimolar binary mixture of classical pointlike particles with charges Q1 and Q2, such that q =Q2/Q1∈[0 ,1 ] . The particles interact pairwise via three-dimensional (3D) Coulomb potential and are confined to a 2D plane with a homogeneous neutralizing background charge density. In a recent paper by M. Antlanger and G. Kahl [Condens. Matter Phys. 16, 43501 (2013), 10.5488/CMP.16.43501], using numerical computations based on an evolutionary algorithm, six fully mixed structures were identified for 0 ≤q ≲0.59 , while the separation of Q1 and Q2 pure hexagonal phases minimizes the energy for 0.59 ≲q <1 . Here, we introduce a structure which consists of the separation of two phases: a pure hexagonal one formed by a fraction of particles with the larger charge Q1 and the other a mixed one containing different numbers of Q1 and Q2 charges. Using an analytic method based on an expansion of the interaction energy in Misra functions, we show that this structure provides the lowest energy in two intervals of q values, 0 Coulomb and Yukawa interactions, to test more general separations which go beyond the separation of two pure phases.

  18. Yukawa unification predictions with effective "mirage" mediation.

    PubMed

    Anandakrishnan, Archana; Raby, Stuart

    2013-11-22

    In this Letter we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the grand unified theory (GUT) scale, which we characterize as effective "mirage" mediation. We perform a global χ2 analysis including the observables M(W), M(Z), G(F), α(em)(-1), α(s)(M(Z)), M(t), m(b)(m(b)), M(τ), BR(B→X(s)γ), BR(B(s)→μ(+)μ(-)), and M(h). The fit is performed in the minimal supersymmetric standard model in terms of 10 GUT scale parameters, while tanβ and μ are fixed at the weak scale. We find good fits to the low energy data and a supersymmetry spectrum which is dramatically different than previously studied in the context of Yukawa unification. PMID:24313477

  19. Yukawa Unification Predictions with Effective ``Mirage'' Mediation

    NASA Astrophysics Data System (ADS)

    Anandakrishnan, Archana; Raby, Stuart

    2013-11-01

    In this Letter we analyze the consequences, for the LHC, of gauge and third family Yukawa coupling unification with a particular set of boundary conditions defined at the grand unified theory (GUT) scale, which we characterize as effective “mirage” mediation. We perform a global χ2 analysis including the observables MW, MZ, GF, αem-1, αs(MZ), Mt, mb(mb), Mτ, BR(B→Xsγ), BR(Bs→μ+μ-), and Mh. The fit is performed in the minimal supersymmetric standard model in terms of 10 GUT scale parameters, while tan⁡β and μ are fixed at the weak scale. We find good fits to the low energy data and a supersymmetry spectrum which is dramatically different than previously studied in the context of Yukawa unification.

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

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Y.; Ashcroft, N. W.

    1978-01-01

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

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

    PubMed

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

    2014-02-21

    The traditional photon absorbers Cu2-xX (X = S, Se, and Te) have regained significant research attention in the search of earth-abundant photovoltaic materials. These moderate- and narrow-gap materials have also been shown to exhibit excellent thermoelectric properties recently. However, semimetallic band structures with inverted band orderings are predicted for antifluorite structure Cu2X using density functional theory with the local density approximation or the generalized gradient approximation. We find that semiconducting band structures and normal band orderings can be obtained using the modified Becke-Johnson potential plus an on-site Coulomb U (the mBJ+U approach), which is consistent with our earlier finding for diamond-like Cu-based multinary semiconductors [Y. Zhang, J. Zhang, W. Gao, T. A. Abtew, Y. Wang, P. Zhang, and W. Zhang, J. Chem. Phys. 139, 184706 (2013)]. The trend of the chemical bonding of Cu2X is analyzed, which shows that the positions of the valence band maximum and conduction band minimum are strongly affected by the inter-site pd and intra-site sp hybridizations, respectively. The calculated gaps of Cu2S and Cu2Se still seem to be underestimated compared with experimental results. We also discuss the effects of different structural phases and Cu disordering and deficiency on the bandgaps of these materials. PMID:24559355

  2. 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; Zhang, Peihong E-mail: pzhang3@buffalo.edu; Beijing Computational Science Research Center, Beijing 100084 ; Zhang, Wenqing E-mail: pzhang3@buffalo.edu; School of Chemistry and Chemical Engineering, and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093

    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.

  3. New approach to the Yukawa puzzle

    SciTech Connect

    Branco, G.C.; Emmanuel-Costa, D.; Silva-Marcos, J.I.

    1997-07-01

    We do a systematic analysis of the question of the calculability of CKM matrix elements in terms of quark-mass ratios, within the framework of the hypothesis of the universality of strength for Yukawa couplings (USY), where all Yukawa couplings have equal moduli, and the flavor dependence is only in their phases. We use the fact that the limit m{sub u}=m{sub d}=0 is especially simple in the USY, to construct the various {ital Ans{umlt a}tze}. It is shown that the experimentally observed CKM matrix can be obtained within USY {ital Ans{umlt a}tze} corresponding to simple relations among phases of Yukawa couplings. Within the USY, one finds a natural explanation why Cabibbo mixing is significantly larger than the other CKM mixings. In the most successful of the USY {ital Ans{umlt a}tze}, one obtains, in leading order, {vert_bar}V{sub us}{vert_bar}={radical}(m{sub d}/m{sub s}), {vert_bar}V{sub cb}{vert_bar}={radical}(2)(m{sub s}/m{sub b}), {vert_bar}V{sub ub}{vert_bar}=(1/{radical}(2)){radical}(m{sub d}m{sub s}/m{sub b}{sup 2}), and {vert_bar}V{sub td}{vert_bar}=3{vert_bar}V{sub ub}{vert_bar}. We study the behavior of this USY {ital Ansatz} under the renormalization group. {copyright} {ital 1997} {ital The American Physical Society}

  4. 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.

  5. Exclusive window onto Higgs Yukawa couplings.

    PubMed

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

    2015-03-13

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

  6. Lepton masses and mixing without Yukawa hierarchies

    SciTech Connect

    Ponce, William A.; Zapata, Oscar

    2006-11-01

    We investigate the neutrino masses and mixing pattern in a version of the SU(3){sub c}(multiply-in-circle sign)SU(3){sub L}(multiply-in-circle sign)U(1){sub X} model with one extra exotic charged lepton per family as introduced by Ozer. It is shown that an extended scalar sector, together with a discrete Z{sub 2} symmetry, is able to reproduce a consistent lepton mass spectrum without a hierarchy in the Yukawa coupling constants, the former as a consequence of a carefull balance between one universal see-saw and two radiative mechanisms.

  7. Periodically sheared 2D Yukawa systems

    SciTech Connect

    Kovács, Anikó Zsuzsa; Hartmann, Peter; Donkó, Zoltán

    2015-10-15

    We present non-equilibrium molecular dynamics simulation studies on the dynamic (complex) shear viscosity of a 2D Yukawa system. We have identified a non-monotonic frequency dependence of the viscosity at high frequencies and shear rates, an energy absorption maximum (local resonance) at the Einstein frequency of the system at medium shear rates, an enhanced collective wave activity, when the excitation is near the plateau frequency of the longitudinal wave dispersion, and the emergence of significant configurational anisotropy at small frequencies and high shear rates.

  8. 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 Γ=175 to Coulomb parameters up to Γ=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

  9. Diffusion in Coulomb crystals

    SciTech Connect

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

    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.

  10. Measuring the top Yukawa coupling at 100 TeV

    NASA Astrophysics Data System (ADS)

    Mangano, Michelangelo L.; Plehn, Tilman; Reimitz, Peter; Schell, Torben; Shao, Hua-Sheng

    2016-04-01

    We propose a measurement of the top Yukawa coupling at a 100 TeV hadron collider, based on boosted Higgs and top decays. We find that the top Yukawa coupling can be measured to 1%, with excellent handles for reducing systematic and theoretical uncertainties, both from side bands and from t\\bar{t}H/t\\bar{t}Z ratios.

  11. Numerical approach to Coulomb gauge QCD

    SciTech Connect

    Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O.

    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.

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

    NASA Astrophysics Data System (ADS)

    Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2007-04-01

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

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

    PubMed

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

    2011-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

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

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

    PubMed

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Carrillo-Bernal, M. A.; Nez-Ypez, H. N.; Salas-Brito, A. L.; Solis, Didier A.

    2015-02-01

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

  17. Simple estimation of thermodynamic properties of Yukawa systems.

    PubMed

    Khrapak, S A; Khrapak, A G; Ivlev, A V; Morfill, G E

    2014-02-01

    A simple analytical approach to estimate thermodynamic properties of model Yukawa systems is presented. The approach extends the traditional Debye-Hückel theory into the regime of moderate coupling and is able to qualitatively reproduce thermodynamics of Yukawa systems up to the fluid-solid phase transition. The simplistic equation of state (pressure equation) is derived and applied to the hydrodynamic description of the longitudinal waves in Yukawa fluids. The relevance of this study to the topic of complex (dusty) plasmas is discussed. PMID:25353581

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

    SciTech Connect

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

    2014-12-15

    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.

  19. 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.

  20. Thermodynamics of Yukawa systems and sound velocity in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Khrapak, S. A.

    2016-01-01

    The simple practical approaches to estimate thermodynamic properties of three-dimensional Yukawa systems across coupling regimes (in fluid and solid phases) are summarized. These approaches demonstrate very good accuracy when compared with the results of direct numerical simulations. To demonstrate possible applications, the sound velocity in a strongly coupled dusty plasma is evaluated by combining the conventional fluid description of multi-component plasma with the appropriate equation of state of Yukawa fluids. Limitations of the proposed approaches are briefly discussed.

  1. Kelvin Helmholtz Instability in Strongly Coupled Yukawa Liquids

    SciTech Connect

    Ashwin, J.; Ganesh, R.

    2010-05-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  3. Cholesteric order in systems of helical Yukawa rods

    NASA Astrophysics Data System (ADS)

    Wensink, H. H.; Jackson, G.

    2011-05-01

    We consider the interaction potential between two chiral rod-like colloids which consist of a thin cylindrical backbone decorated with a helical charge distribution on the cylinder surface. For sufficiently slender helical rods a simple scaling expression is derived which relates the chiral 'twisting' potential to the microscopic properties of the particles, such as the internal helical pitch, charge density and electrostatic screening parameter. To predict the behaviour of the macroscopic cholesteric pitch of the fluid bulk phase we invoke a simple second-virial theory generalized to treat anisotropic states with weakly twisted director fields. It is shown that, while particles with weakly coiled helices always form a cholesteric phase whose helical sense is commensurate with that of the internal helix, more strongly coiled rods lead to the formation of a cholesteric state of opposite sense. The correlation between the helical symmetry at the microscopic and macroscopic scale is found to be very sensitive to the pitch of the Yukawa helix. Mixing helical particles of sufficiently disparate length and internal pitch may give rise to a demixing of the uniform cholesteric phase into two fractions with a different macroscopic pitch. Our findings could be relevant to the interpretation of experimental observations in systems of cellulose and chitin microfibres, DNA and fd virus rods.

  4. Supersymmetric Yukawa sum rule and LHC tests

    SciTech Connect

    Blanke, Monika; Curtin, David; Perelstein, Maxim

    2010-08-01

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

  5. Stable Coulomb Bubbles?

    SciTech Connect

    Moretto, L.; Tso, K.; Wozniak, G.

    1997-02-01

    Coulomb bubbles, though stable against monopole displacement, are unstable at least with respect to quadrupole and octupole distortions. We show that there exists a temperature at which the pressure of the vapor filling the bubble stabilizes all the radial modes. In extremely thin bubbles, the crispation modes become unstable due to the surface-surface interaction. {copyright} {ital 1997} {ital The American Physical Society}

  6. New approach to folding with the Coulomb wave function

    SciTech Connect

    Blokhintsev, L. D.; Savin, D. A.; Kadyrov, A. S.; Mukhamedzhanov, A. M.

    2015-05-15

    Due to the long-range character of the Coulomb interaction theoretical description of low-energy nuclear reactions with charged particles still remains a formidable task. One way of dealing with the problem in an integral-equation approach is to employ a screened Coulomb potential. A general approach without screening requires folding of kernels of the integral equations with the Coulomb wave. A new method of folding a function with the Coulomb partial waves is presented. The partial-wave Coulomb function both in the configuration and momentum representations is written in the form of separable series. Each term of the series is represented as a product of a factor depending only on the Coulomb parameter and a function depending on the spatial variable in the configuration space and the momentum variable if the momentum representation is used. Using a trial function, the method is demonstrated to be efficient and reliable.

  7. Ground state of a confined Yukawa plasma including correlation effects

    NASA Astrophysics Data System (ADS)

    Henning, C.; Ludwig, P.; Filinov, A.; Piel, A.; Bonitz, M.

    2007-09-01

    The ground state of an externally confined one-component Yukawa plasma is derived analytically using the local density approximation (LDA). In particular, the radial density profile is computed. The results are compared with the recently obtained mean-field (MF) density profile [Henning , Phys. Rev. E 74, 056403 (2006)]. While the MF results are more accurate for weak screening, the LDA with correlations included yields the proper description for large screening. By comparison with first-principles simulations for three-dimensional spherical Yukawa crystals, we demonstrate that the two approximations complement each other. Together they accurately describe the density profile in the full range of screening parameters.

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

    ERIC Educational Resources Information Center

    Spradley, Joseph L.

    1985-01-01

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

  9. Thermodynamics of Thomas-Fermi screened Coulomb systems

    NASA Technical Reports Server (NTRS)

    Firey, B.; Ashcroft, N. W.

    1977-01-01

    We obtain in closed analytic form, estimates for the thermodynamic properties of classical fluids with pair potentials of Yukawa type, with special reference to dense fully ionized plasmas with Thomas-Fermi or Debye-Hueckel screening. We further generalize the hard-sphere perturbative approach used for similarly screened two-component mixtures, and demonstrate phase separation in this simple model of a liquid mixture of metallic helium and hydrogen.

  10. Analysis of two-dimensional photoelectron momentum spectra and the effect of the long-range Coulomb potential in single ionization of atoms by intense lasers

    SciTech Connect

    Chen, Zhangjin; Le, Anh-Thu; Lin, C. D.; Morishita, Toru; Wickenhauser, M.; Tong, X. M.

    2006-11-15

    Two-dimensional (2D) electron momentum distributions and energy spectra for multiphoton ionization of atoms by intense laser pulses, calculated by solving the time-dependent Schroedinger equation (TDSE) for different wavelengths and intensities, are compared to those predicted by the strong-field approximation (SFA). It is shown that the momentum spectra at low energies between the TDSE and SFA are quite different and the differences arise largely from the absence of a long-range Coulomb interaction in the SFA. We further found that the low-energy 2D momentum spectra from the TDSE exhibit ubiquitous fanlike features where the number of stripes is due to a single dominant angular momentum of the low-energy electron. The specific dominant angular momentum in turn has been found to be decided by the minimum number of photons needed to ionize the atom only. The electron momentum spectra predicted by models modified from the SFA are also examined and found to lack the fanlike features as in the SFA.

  11. Semiclassical Coulomb field

    SciTech Connect

    Polonyi, J.

    2008-06-15

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

  12. Numerical studies of the melting transition in 2D Yukawa systems

    SciTech Connect

    Hartmann, P.; Donko, Z.; Kalman, G. J.

    2008-09-07

    We present the latest results of our systematic studies of the solid--liquid phase transition in 2D classical many-particle systems interacting with the Yukawa potential. Our previous work is extended by applying the molecular dynamic simulations to systems with up to 1.6 million particles in the computational box (for {kappa} = 2 case). Equilibrium simulations are performed for different coupling parameters in the vicinity of the expected melting transition ({gamma}{sub m}{sup {kappa}}{sup ={sup 2}}{approx_equal}415) and a wide range of observables are averaged over uncorrelated samples of the micro-canonical ensemble generated by the simulations.

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

    NASA Astrophysics Data System (ADS)

    Sadooghi, N.; Taghinavaz, F.

    2016-01-01

    Using the standard Green-Kubo formalism, we determine the shear viscosity η 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, ηb and ηf. It turns out that the effects of plasminos on ηf become negligible with increasing (decreasing) temperature (chemical potential).

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

    PubMed

    Odriozola, G; Bárcenas, M; Orea, P

    2011-04-21

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

  15. Relations between the longitudinal and transverse sound velocities in strongly coupled Yukawa fluids

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.

    2016-02-01

    Two useful relations between the longitudinal and transverse sound velocities of the strongly coupled single component Yukawa fluids are derived. The first relates the sound velocities given by the quasilocalized charge approximation (QLCA) to the excess pressure of the system. This is shown to be a mathematical identity within QLCA, applicable to any soft isotropic interaction potential. The second relates the same quantities to the fluid sound velocity obtained via the thermodynamic route. Both three-dimensional and two-dimensional cases are considered. The accuracy of the relations is verified using the available results based on direct numerical simulations.

  16. Remote Spacecraft Attitude Control by Coulomb Charging

    NASA Astrophysics Data System (ADS)

    Stevenson, Daan

    The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose orbits experience no natural means of decay. The ability to rendezvous with these derelict satellites would enable active debris removal by servicing or repositioning missions, but docking procedures are generally inhibited by the large rotational momenta of uncontrolled satellites. Therefore, a contactless means of reducing the rotation rate of objects in the space environment is desired. This dissertation investigates the viability of Coulomb charging to achieve such remote spacecraft attitude control. If a servicing craft imposes absolute electric potentials on a nearby nonspherical debris object, it will impart electrostatic torques that can be used to gradually arrest the object's rotation. In order to simulate the relative motion of charged spacecraft with complex geometries, accurate but rapid knowledge of the Coulomb interactions is required. To this end, a new electrostatic force model called the Multi-Sphere Method (MSM) is developed. All aspects of the Coulomb de-spin concept are extensively analyzed and simulated using a system with simplified geometries and one dimensional rotation. First, appropriate control algorithms are developed to ensure that the nonlinear Coulomb torques arrest the rotation with guaranteed stability. Moreover, the complex interaction of the spacecraft with the plasma environment and charge control beams is modeled to determine what hardware requirements are necessary to achieve the desired electric potential levels. Lastly, the attitude dynamics and feedback control development is validated experimentally using a scaled down terrestrial testbed. High voltage power supplies control the potential on two nearby conductors, a stationary sphere and a freely rotating cylinder. The nonlinear feedback control algorithms developed above are implemented to achieve rotation rate and absolute attitude control. Collectively, these studies decisively validate the feasibility of Coulomb charging for remote spacecraft attitude control.

  17. Scalar decay constant and Yukawa coupling in walking gauge theories

    SciTech Connect

    Hashimoto, Michio

    2011-05-01

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

  18. On the shear viscosity of 3D Yukawa liquids

    SciTech Connect

    Donko, Z.; Hartmann, P.

    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.

  19. Four-fermion limit of gauge-Yukawa theories

    NASA Astrophysics Data System (ADS)

    Krog, Jens; Mojaza, Matin; Sannino, Francesco

    2015-10-01

    We elucidate and extend the conditions that map gauge-Yukawa theories at low energies into time-honored gauged four-fermion interactions at high energies. These compositeness conditions permit us to investigate theories of composite dynamics through gauge-Yukawa theories. Here we investigate whether perturbative gauge-Yukawa theories can have a strongly coupled limit at high energy that can be mapped into a four-fermion theory. Interestingly, we are able to precisely carve out a region of the perturbative parameter space supporting such a composite limit. This has interesting implications on our current view on models of particle physics. As a template model we use an S U (NC) gauge theory with NF Dirac fermions transforming according to the fundamental representation of the gauge group. The fermions further interact with a gauge singlet complex NFNF Higgs boson that ceases to be a physical degree of freedom at the ultraviolet composite scale, where it gives away to the four-fermion interactions. We compute the hierarchy between the ultraviolet and infrared composite scales of the theory and show that they are naturally large and well separated. Our results show that some weakly coupled gauge-Yukawa theories can be viewed, in fact, as composite theories. It is therefore tantalizing to speculate that the standard model, with its phenomenological perturbative Higgs sector, could hide, in plain sight, a composite theory.

  20. Practical thermodynamics of Yukawa systems at strong coupling

    SciTech Connect

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

    2015-05-21

    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.

  1. Coulomb Bound States of Strongly Interacting Photons

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    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 quasibound 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 wave function 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.

  2. S2 like Star Orbits near the Galactic Center in Rn and Yukawa Gravity

    NASA Astrophysics Data System (ADS)

    Borka, Dusko; Jovanović, Predrag; Jovanović Vesna Borka; Zakharov, Alexander F.

    2015-01-01

    In this chapter we investigate the possibility to provide theoretical explanation for the observed deviations of S2 star orbit around the Galactic Center using gravitational potentials derived from extended gravity models, but in absence of dark matter. Extended Theories of Gravity are alternative theories of gravitational interaction developed from the exact starting points investigated first by Einstein and Hilbert and aimed from one side to extend the positive results of General Relativity and, on the other hand, to cure its shortcomings. One of the aims of these theories is to explain galactic and extragalactic dynamics without introduction of dark matter. They are based on straightforward generalizations of the Einstein theory where the gravitational action (the Hilbert-Einstein action) is assumed to be linear in the Ricci curvature scalar R. The f(R) gravity is a type of modified gravity which generalizes Einstein's General Relativity, i.e. the simplest case is just the General Relativity. It is actually a family of models, each one defined by a different function of the Ricci scalar. Here, we consider Rn (power-law fourth-order theories of gravity) and Yukawa-like modified gravities in the weak field limit and discuss the constrains on these theories. For that purpose we simulate the orbit of S2 star around the Galactic Center in Rn and Yukawa-like gravity potentials and compare it with New Technology Telescope/Very Large Telescope (NTT/VLT) as well as by Keck telescope observations. Our simulations result in strong constraints on the range of gravity interaction and showed that both Rn and Yukawa gravity could satisfactorily explain the observed orbits of S2 star. However, we concluded that parameters of Rn and Yukawa gravity theories must be very close to those corresponding to the Newtonian limit of the theory. Besides, in contrast to Newtonian gravity, these two modified theories induce orbital precession, even in the case of point-like central mass. The approach we are proposing seems to be sufficiently reliable to constrain the modified gravity models from stellar orbits around Galactic Center.

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

    PubMed

    Khrapak, Sergey A; Thomas, Hubertus M

    2015-03-01

    The conventional fluid description of multicomponent plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasilocalized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strength in the fluid regime but exhibits a pronounced decrease with the increase of the screening strength. The limitations of the present approach in applications to real complex plasmas are briefly discussed. PMID:25871227

  4. Reply to "Comment on `Calculations for the one-dimensional soft Coulomb problem and the hard Coulomb limit' "

    NASA Astrophysics Data System (ADS)

    Gebremedhin, Daniel H.; Weatherford, Charles A.

    2015-02-01

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

  5. Chaotic particle motion in Coulomb electric and uniform magnetic fields

    NASA Astrophysics Data System (ADS)

    Sonmor, L. J.; Laframboise, J. G.

    1991-08-01

    In an attractive Coulomb electric field and a uniform magnetic field B, some particle orbits originating at infinite distance undergo many reflections, repeatedly approaching the Coulomb center. The chaotic nature of these orbits is discussed and illustrated by numerical calculations. The divergence of neighboring trajectories is shown to occur mostly in discrete jumps when they pass near the Coulomb center. The appearance of chaotic behavior in this simplified situation suggests that it will also occur when space-charge effects significantly perturb the potential distribution around a current-collecting electrode in a space magnetoplasma.

  6. Exponential approximation for one-component Yukawa plasma

    SciTech Connect

    Hlushak, Stepan

    2014-11-28

    A theory based on the exponential approximation of the liquid-state theory is applied to study properties of several models of one-component Yukawa plasma characterized by different values of the screening parameter z. The results of the new theory are compared to the results of a conventional theory, which is based on the first-order mean spherical approximation, and to the results of a Monte Carlo simulation. The new theory shows improvements in the predictions for the thermodynamic and structural properties of Yukawa plasmas with high and intermediate values of the screening parameter, z, and coupling parameter, Γ. For low values of z and Γ, the new theory is comparable in accuracy to the conventional theory, which in turn agrees well with the results of the Monte Carlo simulation.

  7. Effective Hamiltonian for bound states in Yukawa theory

    SciTech Connect

    Weber, Axel

    2013-07-15

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

  8. Why should we care about the top quark Yukawa coupling?

    DOE PAGESBeta

    Shapshnikov, Mikhail; Bezrukov, Fedor

    2015-04-15

    In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling yt should not exceed the critical value ytcrit , coinciding with good precision (about 0.2‰) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of yt may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to yt. In this study, we overview the most recent theoretical computations of and the experimental measurements of ytcrit and the experimental measurements ofmore » yt. Within the theoretical and experimental uncertainties in yt, the required scale of new physics varies from 10⁷ GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.« less

  9. 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

  10. On the long-waves dispersion in Yukawa systems

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.; Klumov, Boris; Couëdel, Lénaïc; Thomas, Hubertus M.

    2016-02-01

    A useful simplification of the quasilocalized charge approximations (QLCA) method to calculate the dispersion relations in strongly coupled Yukawa fluids is discussed. In this simplified version, a simplest possible model radial distribution function, properly related to the thermodynamic properties of the system, is used. The approach demonstrates good agreement with the dispersion relations obtained using the molecular dynamics simulations and the original QLCA in the long-wavelength regime.

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

    SciTech Connect

    Rattazzi, R.; Sarid, U.; Hall, L.J.

    1993-05-01

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

  12. Nonstandard Yukawa couplings and Higgs portal dark matter

    DOE PAGESBeta

    Bishara, Fady; Brod, Joachim; Uttayarat, Patipan; Zupan, Jure

    2016-01-04

    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,more » 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. In conclusion, we point out that a discovery of Higgs-portal dark matter could lead to interesting bounds on the light-quark Yukawa couplings.« less

  13. Nonstandard Yukawa couplings and Higgs portal dark matter

    NASA Astrophysics Data System (ADS)

    Bishara, Fady; Brod, Joachim; Uttarayat, Patipan; Zupan, Jure

    2016-01-01

    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.

  14. Universality in the Equilibration of Quenched Yukawa One Component Plasmas

    NASA Astrophysics Data System (ADS)

    Langin, Thomas; McQuillen, Patrick; Strickler, Trevor; Maksimovic, Nikola; Pohl, Thomas; Killian, Thomas

    2015-11-01

    We study the equilibration of a Yukawa One Component Plasma (OCP) after a rapid change in the screening parameter from κ0 = ∞ to κf (n ,Te) , which is realized by photoionizing a laser cooled (T ~ 10 mK), uncorrelated gas of 88Sr atoms with density n between 1014 m-3 and 3 ×1016 m-3 using a two photon process in which the energy of one of the photons is adjustable. The excess photon energy above the ionization threshold sets the electron temperature, Te, and thus gives us control of κf. The resultant plasma is a classical plasma with strongly coupled ions, and is therefore described by the Yukawa OCP model with the electrons treated as a screening background. After photoionization, the ions develop spatial correlations to minimize their interaction energy, thus heating the ions. Since the dynamics of a Yukawa OCP depend solely on κ, we expect the heating process to be uniquely determined by κf. We verify this behavior by measuring the ion heating curve and comparing it to molecular dynamics simulations. We also report on how this behavior can be used to accurately measure n given a measured equilibration curve at a known Te. This work was supported by the United States National Science Foundation and the Department of Energy (PHY-0714603), the Air Force Office of Scientific Research (FA9550- 12-1-0267), and the Department of Defense (DoD) through the NDSEG Program.

  15. Interatomic Coulombic electron capture

    SciTech Connect

    Gokhberg, K.; Cederbaum, L. S.

    2010-11-15

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

  16. Kolmogorov flow in two dimensional strongly coupled Yukawa liquid: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Gupta, Akanksha; Ganesh, Rajaraman; Joy, Ashwin

    2015-10-01

    The transition from laminar to turbulent flows in liquids remains a problem of great interest despite decades of intensive research. Here, we report an atomistic study of this transition in a model Yukawa liquid using molecular dynamics simulations. Starting from an thermally equilibrated Yukawa liquid, for a given value of coupling parameter Γ (defined as ratio of potential energy to kinetic energy per particle) and screening length κ, a subsonic flow of magnitude U0 is superposed and transition to an unstable regime is observed eventually leading to turbulent flow at sufficiently high Reynolds numbers. We have performed a parametric study for a range of Reynolds number R and found that the flow is neutrally stable for R Rc(Γ) , where Rc is the critical value of Reynolds number. Strong molecular shear heating is observed in all cases studied here. It is found that the coupling parameter Γ decreases because of molecular shear heating on a time scale comparable to the instability time scale. Irrespective of the initial value of coupling parameter Γ, the average heating rate is found to be sensitive to the ratio of equilibrium flow speed to the thermal speed, say, α=U/0 vt h , where vt h=√{2/Γ } . Our results reported here are expected to be generic and should apply to a wide variety of strongly coupled systems such as laboratory dusty plasma, molten salts, and charged colloidal systems.

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  18. Demonstrating universal scaling for dynamics of Yukawa one-component plasmas after an interaction quench

    NASA Astrophysics Data System (ADS)

    Langin, T. K.; Strickler, T.; Maksimovic, N.; McQuillen, P.; Pohl, T.; Vrinceanu, D.; Killian, T. C.

    2016-02-01

    The Yukawa one-component plasma (OCP) model is a paradigm for describing plasmas that contain one component of interest and one or more other components that can be treated as a neutralizing, screening background. In appropriately scaled units, interactions are characterized entirely by a screening parameter, κ . As a result, systems of similar κ show the same dynamics, regardless of the underlying parameters (e.g., density and temperature). We demonstrate this behavior using ultracold neutral plasmas (UNPs) created by photoionizing a cold (T ≤10 mK) gas. The ions in UNP systems are well described by the Yukawa model, with the electrons providing the screening. Creation of the plasma through photoionization can be thought of as a rapid quench of the interaction potential from κ =∞ to a final κ value set by the electron density and temperature. We demonstrate experimentally that the postquench dynamics are universal in κ over a factor of 30 in density and an order of magnitude in temperature. Results are compared with molecular-dynamics simulations. We also demonstrate that features of the postquench kinetic energy evolution, such as disorder-induced heating and kinetic-energy oscillations, can be used to determine the plasma density and the electron temperature.

  19. Solutions of D-dimensional Schrodinger equation for Woods-Saxon potential with spin-orbit, coulomb and centrifugal terms through a new hybrid numerical fitting Nikiforov-Uvarov method

    NASA Astrophysics Data System (ADS)

    Niknam, A.; Rajabi, A. A.; Solaimani, M.

    2015-12-01

    Solution of the radial Schrodinger equation for the Woods-Saxon potential together with spin-orbit interaction, coulomb and centrifugal terms by using usual Nikiforov-Uvarov (NU) method is not possible. Here, we have presented a new NU procedure with which we are able to solve this Schrodinger equation and any other one-dimensional ones with any shape of the potential profile. For this purpose, we have combined the NU method with numerical fitting schema. The energy eigenvalues and corresponding eigenfunctions for various values of n, l, and j quantum numbers have been obtained. Good agreement with experimental values is also achieved. We have calculated the 1/2+ state energy with more accuracy (our absolute error = 0.023 MeV and Hagen et al. absolute error = 0.0918 MeV), while Hagen et al. have calculated the 5/2+ state energy with higher accuracy (our absolute error = 0.71 MeV and Hagen et al. absolute error = 0.0337 MeV). Our wave functions are in agreement with Kim et al.'s work, too.

  20. Solutions of D-dimensional Schrodinger equation for Woods-Saxon potential with spin-orbit, coulomb and centrifugal terms through a new hybrid numerical fitting Nikiforov-Uvarov method

    NASA Astrophysics Data System (ADS)

    Niknam, A.; Rajabi, A. A.; Solaimani, M.

    2016-03-01

    Solution of the radial Schrodinger equation for the Woods-Saxon potential together with spin-orbit interaction, coulomb and centrifugal terms by using usual Nikiforov-Uvarov (NU) method is not possible. Here, we have presented a new NU procedure with which we are able to solve this Schrodinger equation and any other one-dimensional ones with any shape of the potential profile. For this purpose, we have combined the NU method with numerical fitting schema. The energy eigenvalues and corresponding eigenfunctions for various values of n, l, and j quantum numbers have been obtained. Good agreement with experimental values is also achieved. We have calculated the 1/2+ state energy with more accuracy (our absolute error = 0.023 MeV and Hagen et al. absolute error = 0.0918 MeV), while Hagen et al. have calculated the 5/2+ state energy with higher accuracy (our absolute error = 0.71 MeV and Hagen et al. absolute error = 0.0337 MeV). Our wave functions are in agreement with Kim et al.'s work, too.

  1. Coulomb crystallization of highly charged ions.

    PubMed

    Schmger, 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; Lpez-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

  2. Coulomb crystallization of highly charged ions

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Strader, Anne Elizabeth

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

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

    SciTech Connect

    Martin, C. P.

    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}}.

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

    NASA Astrophysics Data System (ADS)

    Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Rigel Mora-Luna, Refugio

    2016-05-01

    Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ̅ in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb's law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb's law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb's law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally observed or astrophysically inferred photon mass, are far beyond its upper bound, positively testing the viability of our tachyonic braneworld. Moreover, the 5D parameters that define these corrections possess the same order, providing naturalness to our model, however, a fine-tuning between them is needed in order to fit the corresponding upper bound on the photon mass.

  6. Dynamics of Coulombic and gravitational periodic systems

    NASA Astrophysics Data System (ADS)

    Kumar, Pankaj; Miller, Bruce N.

    2016-04-01

    We study the dynamics and the phase-space structures of Coulombic and self-gravitating versions of the classical one-dimensional three-body system with periodic boundary conditions. We demonstrate that such a three-body system may be reduced isomorphically to a spatially periodic system of a single particle experiencing a two-dimensional potential on a rhombic plane. For the case of both Coulombic and gravitational versions, exact expressions of the Hamiltonian have been derived in rhombic coordinates. We simulate the phase-space evolution through an event-driven algorithm that utilizes analytic solutions to the equations of motion. The simulation results show that the motion exhibits chaotic, quasiperiodic, and periodic behaviors in segmented regions of the phase space. While there is no evidence of global chaos in either the Coulombic or the gravitational system, the former exhibits a transition from a completely nonchaotic phase space at low energies to a mixed behavior. Gradual yet striking transitions from mild to intense chaos are indicated with changing energy, a behavior that differentiates the spatially periodic systems studied in this Rapid Communication from the well-understood free-boundary versions of the three-body problem. Our treatment of the three-body systems opens avenues for analysis of the dynamical properties exhibited by spatially periodic versions of various classes of systems studied in plasma and gravitational physics as well as in cosmology.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

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

    SciTech Connect

    Zhang, Yubo; Zhang, Jiawei; Wang, Youwei; Gao, Weiwei; Abtew, Tesfaye A.; Zhang, Peihong E-mail: wqzhang@mail.sic.ac.cn; Beijing Computational Science Research Center, Beijing 100084 ; Zhang, Wenqing E-mail: wqzhang@mail.sic.ac.cn; School of Chemistry and Chemical Engineering and Sate Key Laboratory of Coordination Chemistry, Nanjing University, Jiangsu 210093

    2013-11-14

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

  9. Poisson's equation solution of Coulomb integrals in atoms and molecules

    NASA Astrophysics Data System (ADS)

    Weatherford, Charles A.; Red, Eddie; Joseph, Dwayne; Hoggan, Philip

    The integral bottleneck in evaluating molecular energies arises from the two-electron contributions. These are difficult and time-consuming to evaluate, especially over exponential type orbitals, used here to ensure the correct behaviour of atomic orbitals. In this work, it is shown that the two-centre Coulomb integrals involved can be expressed as one-electron kinetic-energy-like integrals. This is accomplished using the fact that the Coulomb operator is a Green's function of the Laplacian. The ensuing integrals may be further simplified by defining Coulomb forms for the one-electron potential satisfying Poisson's equation therein. A sum of overlap integrals with the atomic orbital energy eigenvalue as a factor is then obtained to give the Coulomb energy. The remaining questions of translating orbitals involved in three and four centre integrals and the evaluation of exchange energy are also briefly discussed. The summation coefficients in Coulomb forms are evaluated using the LU decomposition. This algorithm is highly parallel. The Poisson method may be used to calculate Coulomb energy integrals efficiently. For a single processor, gains of CPU time for a given chemical accuracy exceed a factor of 40. This method lends itself to evaluation on a parallel computer.

  10. Beam-Plasma Instabilities in a 2D Yukawa Lattice

    SciTech Connect

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

    2009-06-05

    We consider a 2D Yukawa lattice of grains, with a beam of other charged grains moving in the lattice plane. In contrast to Vlasov plasmas, where the electrostatic instability excited by the beam is only longitudinal, here both longitudinal and transverse instabilities of the lattice phonons can develop. We determine and compare the transverse and longitudinal growth rates. The growth rate spectrum in wave number space exhibits remarkable gaps where no instability can develop. Depending on the system parameters, the transverse instability can be selectively excited.

  11. 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.

  12. Hard-sphere Yukawa fluid near a planar slit

    NASA Astrophysics Data System (ADS)

    Yi, Jong-Ho; Kim, Soon-Chul

    1997-11-01

    A density functional perturbative approximation, which is based on both the weighted-density approximation (WDA) of Tarazona and the density functional approximation of Rickayzen et al., has been employed to predict the density profiles of the hard-sphere attractive Yukawa fluid near a planar slit. The calculated density profiles show that the density functional perturbative approximation is a significant improvement upon those of the modified version of the Lovett-Mou-Buff-Wertheim (LMBW-1), which uses the exact contact value theorem, and compares very well with the computer simulation even for the low temperatures in the vicinity of the liquid-vapor fluid bulk transition.

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

    PubMed

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

    2010-03-21

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

  14. Solving the eigenvalue problem of the nuclear Yukawa-folded mean-field Hamiltonian

    NASA Astrophysics Data System (ADS)

    Dobrowolski, A.; Pomorski, K.; Bartel, J.

    2016-02-01

    The nuclear Hamiltonian with a Yukawa-folded mean-field potential is diagonalized within the basis of a deformed harmonic-oscillator in Cartesian coordinates. The nuclear shape is characterized by the equivalent sharp surface described either by the well known Funny-Hills or the Trentalange-Koonin-Sierk parametrizations. They are both able to describe a very vast variety of nuclear deformations, including necked-in shapes, left-right asymmetry and non-axiality. The only imposed limitation on the nuclear shape is the z-signature symmetry, which corresponds to a symmetry of the shape with respect to a rotation by an angle π around the z-axis. On output, the computer code produces for a given nucleus with mass number A and charge number Z the energy eigenvalues and eigenfunctions of the mean-field Hamiltonian at chosen deformation.

  15. Molecular thermodynamic modeling of ionic liquids using the perturbation-based linear Yukawa isotherm regularity.

    PubMed

    Sohrabi Mahboub, Mahdi; Farrokhpour, Hossein

    2016-06-15

    In this paper, we present the results of an extensive study on a novel approach to the molecular modeling of pure ionic liquids (ILs) that incorporates the perturbed thermodynamic linear Yukawa isotherm regularity (LYIR), which is derived based on an effective nearest neighboring pair attractive interaction of the Yukawa potential. The LYIR was used to model the densities of ILs up to high pressures (35 MPa) and in the temperature range 293.15 to 393.15 K. To use the LYIR for ILs, a simple molecular model was proposed to describe their molecular structure, in which they were considered as a liquid consisting of the ion pairs moving together in the fluid, and each ion pair was assumed to be a one-center spherical united atom. The ILs under consideration contained one of the IL cations [C2mim](+), [C4mim](+), [C7mim](+), [C8mim](+), [C3mpy](+), [C3mpip](+), [C3mpyr](+) or [C4mpyr](+), and one of the IL anions [BF4](-), [C(CN)3](-), [CF3SO4](-) or [NTf2](-). The reliability and physical significance of the parameters as well as the proposed molecular model were tested by calculating the densities of pure imidazolium-, pyridinium-, piperidinium- and pyrrolidimium-based ILs. The results showed that the LYIR can be used to predict and reproduce the density of ILs in good agreement with the experimental data. In addition, the LYIR enabled us to determine the physical quantities, such as an effective Yukawa screening length, λ eff, the product of the effective energy well depth and the effective coordination number, (ε eff/k)z eff, the contribution of the non-reference thermal pressure and also the influence of the anionic and cationic structure on the λ eff parameter. The standard deviation of the IL densities predicted in this work is lower than those calculated by the one other important equation of state reported in the literature. PMID:27157142

  16. Why should we care about the top quark Yukawa coupling?

    SciTech Connect

    Shapshnikov, Mikhail; Bezrukov, Fedor

    2015-04-15

    In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling yt should not exceed the critical value ytcrit , coinciding with good precision (about 0.2‰) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of yt may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to yt. In this study, we overview the most recent theoretical computations of and the experimental measurements of ytcrit and the experimental measurements of yt. Within the theoretical and experimental uncertainties in yt, the required scale of new physics varies from 10⁷ GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    In this paper we study Yukawa-unified SO(10) supersymmetric (SUSY) grand unified theories (GUTs) with two types of SO(10) boundary conditions: (i) universal gaugino masses and (ii) nonuniversal gaugino masses with effective "mirage" mediation. With these boundary conditions, we perform a global χ2 analysis to obtain the parameters consistent with 11 low energy observables, including the top, bottom, and tau masses. Both boundary conditions have universal scalar masses and "just so" splitting for the up- and down-type Higgs masses. In these models, the third family scalars are lighter than the first two families and the gauginos are lighter than all the scalars. We therefore focus on the gluino phenomenology in these models. In particular, we estimate the lowest allowed gluino mass in our models coming from the most recent LHC data and compare this to limits obtained using simplified models. We find that the lower bound on Mg ˜ in Yukawa-unified SO(10) SUSY GUTs is generically ˜1.2 TEV at the 1σ level unless there is considerable degeneracy between the gluino and the lightest supersymmetric particle, in which case the bounds are much weaker. Hence many of our benchmark points are not ruled out by the present LHC data and are still viable models which can be tested at LHC 14.

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

    NASA Astrophysics Data System (ADS)

    Vasiliev, Victor; Moon, Russell

    2006-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Vasiliev, Victor; Moon, Russell

    2006-11-01

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

  20. Why should we care about the top quark Yukawa coupling?

    SciTech Connect

    Shapshnikov, Mikhail; Bezrukov, Fedor

    2015-04-15

    In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling yt should not exceed the critical value ytcrit , coinciding with good precision (about 0.2) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of yt may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to yt. In this study, we overview the most recent theoretical computations of and the experimental measurements of ytcrit and the experimental measurements of yt. Within the theoretical and experimental uncertainties in yt, the required scale of new physics varies from 10? GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.

  1. Nonlinear mode coupling and vibrational energy transfer in Yukawa clusters

    NASA Astrophysics Data System (ADS)

    Qiao, Ke; Kong, Jie; Matthews, Lorin; Hyde, Truell

    2015-11-01

    Nonlinear mode coupling and the subsequent vibrational energy transfer that results is an important topic in chemical physics research, ranging from small molecules consisting of several atoms to macromolecules such as those found in proteins and DNA. Nonlinear mode coupling is recognized as the mechanism leading to ergodicity, which is a foundational tenet of statistical mechanics. Over the past two decades, Yukawa systems of particles such as those found in complex plasma, have been shown to be an effective model across a large number of physical systems. In this research, nonlinear mode coupling in Yukawa clusters consisting of 3-10 particles is examined via numerical simulation of the vibrational energy transfer between modes starting from an initial excited state. The relationship between the energy transfer process and the internal resonance between modes having a specified frequency ratio and the temporal evolution of the system to a state of equal energy across all modes, i.e., the state of ergodicity, will be discussed. Support from the NSF and the DOE (award numbers PHY-1262031 and PHY-1414523) is gratefully acknowledged.

  2. Quantum defect theory for Coulomb and other potentials in the framework of configuration interaction and implementation to the calculation of 2 D and 2 F o perturbed spectra of Al

    NASA Astrophysics Data System (ADS)

    Komninos, Yannis; Nicolaides, Cleanthes A.

    2004-05-01

    In continuation of our earlier work on the ab initio calculation of perturbed spectra and on a corresponding quantum defect theory (QDT), we discuss certain essential characteristics having to do with the unification of the continuous and the discrete spectra via the formal and practical construction of smooth quantities without invoking the pair of analytic forms of regular and irregular functions. The theory and its computational methodology are in the framework of configuration interaction (CI), and its structure shows how wavefunctions and properties of excited states of atoms and molecules can be computed provided one uses reliable zero-order basis functions, regardless of whether the relevant potential is, asymptotically, Coulombic or some other type. The mathematical connection with smooth reaction matrices in the discrete spectrum is demonstrated via the Mittag-Leffler theorem for the construction of analytic functions. We compare results for the quantum defects and fine structure from the present theory, as implemented by Komninos et al ( 1995 J. Phys. B: At. Mol. Opt. Phys. 28 2049 , 1996 J. Phys. B: At. Mol. Opt. Phys. 29 L193 ), of the Al spectra of 2 D symmetry (strongly perturbed) and of 2 F o symmetry (weakly perturbed), with the recently reported measurements on high-lying states ( Dyubko et al 2003 J. Phys. B: At. Mol. Opt. Phys. 36 3797 and 4827 ), as well as with those of Eriksson and Isberg (1963 Ark. Fys. 23 527) for the low-lying states. The comparison reveals for the first time very good agreement between theory and experiment for both series. In addition, predictions for the other states of the series are made. Previous computations of the quantum defects of the 2 D spectrum, in general, do not agree among themselves while they deviate from the experimental values.

  3. 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.

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

    SciTech Connect

    Greensite, Jeff; Olejnik, Stefan

    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.

  5. 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.

  6. Short-time dynamics of correlated quantum Coulomb systems

    NASA Astrophysics Data System (ADS)

    Bonitz, Michael

    2007-03-01

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

  7. Dynamical fermion mass generation by a strong Yukawa interaction

    SciTech Connect

    Brauner, Tomas; Hosek, Jiri

    2005-08-15

    We consider a model with global Abelian chiral symmetry of two massless fermion fields interacting with a complex massive scalar field. We argue that the Schwinger-Dyson equations for the fermion and boson propagators admit ultraviolet-finite chiral-symmetry-breaking solutions provided the Yukawa couplings are large enough. The fermions acquire masses and the elementary excitations of the complex scalar field are the two real spin-zero particles with different masses. As a necessary consequence of the dynamical chiral symmetry breakdown both in the fermion and scalar sectors, one massless pseudoscalar Nambu-Goldstone boson appears in the spectrum as a collective excitation of both the fermion and the boson fields. Its effective couplings to the fermion and boson fields are calculable.

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

    NASA Astrophysics Data System (ADS)

    Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir

    2011-01-01

    The generation of the right amount of baryon asymmetry η of the Universe from supersymmetric leptogenesis is studied within the type-I seesaw framework with three heavy singlet Majorana neutrinos Ni (i = 1,2,3) and their superpartners. We assume the occurrence of four zeroes in the neutrino Yukawa coupling matrix Yν, taken to be μτ symmetric, in the weak basis where Ni (with real masses Mi > 0) and the charged leptons lα (α = e,μ,τ) are mass diagonal. The quadrant of the single nontrivial phase, allowed in the corresponding light neutrino mass matrix mν, gets fixed and additional constraints ensue from the requirement of matching η 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 μτ symmetry due to RG evolution.

  9. Neutrino Masses, Cosmological Bound and Four Zero Yukawa Textures

    NASA Astrophysics Data System (ADS)

    Adhikary, Biswajit; Ghosal, Ambar; Roy, Probir

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

  10. SO(10) grand unified theories with dynamical Yukawa couplings

    NASA Astrophysics Data System (ADS)

    Aulakh, Charanjit S.; Khosa, Charanjit K.

    2014-08-01

    Renormalizable SO(10) grand unified theories (GUTs), extended by O(Ng)F family gauge symmetry, generate minimal supersymmetric Standard Model flavor 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 210⊕126 ¯⊕126 GUT Higgs system—which were already parameter counting minimal relative to other realistic models. SO(10) fermion Higgs channels 126 ¯,10(120) extend to symmetric (antisymmetric) representations of O(Ng)F, while 210,126 are symmetric. Ng=3 dynamical Yukawa generation reduces the matter fermion Yukawas from 15 to 3 (21 to 5) without (with) the 120 Higgs. Yukawon GUTs are thus ultraminimal in parameter counting terms. Consistent symmetry breaking is ensured by a hidden sector Bajc-Melfo superpotential with a pair of symmetric O(Ng) multiplets ϕ,S, of which the latter's singlet part Ss breaks supersymmetry and the traceless part S ^ furnishes flat directions to cancel the O(Ng) D-term contributions of the visible sector. Novel dark matter candidates linked to flavor symmetry arise from both the Bajc-Melfo sector and GUT sector minimal supersymmetric Standard Model singlet pseudo-Goldstones. These relics may be viable light (<50 GeV) cold dark matter as reported by DAMA/LIBRA. In contrast to the new minimal supersymmetric SO(10) grand unified theory (NMSGUT) even sterile neutrinos can appear in certain branches of the flavor symmetry breaking without the tuning of couplings.

  11. Coulomb versus physical string tension on the lattice

    NASA Astrophysics Data System (ADS)

    Burgio, Giuseppe; Quandt, Markus; Reinhardt, Hugo; Vogt, Hannes

    2015-08-01

    From continuum studies it is known that the Coulomb string tension σC gives an upper bound for the physical (Wilson) string tension σW [D. Zwanziger, Phys. Rev. Lett. 90, 102001 (2003)]. How does such a relationship translate to the lattice, however? In this paper we give evidence that on the lattice, while the two string tensions are related at zero temperature, they decouple at finite temperature. More precisely, we show that on the lattice the Coulomb gauge confinement scenario is always tied to the spatial string tension, which is known to survive the deconfinement phase transition and to cause screening effects in the quark-gluon plasma. Our analysis is based on the identification and elimination of center vortices, which allows us to control the physical string tension and study its effect on the Coulomb gauge observables. We also show how alternative definitions of the Coulomb potential may sense the deconfinement transition; however, a true static Coulomb gauge order parameter for the phase transition is still elusive on the lattice.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. 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 ˜ mτ as well as mt ≫ mc, mu can be naturally explained.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  15. Strong Coulomb effects in hole-doped Heisenberg chains

    NASA Astrophysics Data System (ADS)

    Schnack, J.

    2005-06-01

    Substances such as the “telephone number compound” Sr14Cu24O41 are intrinsically hole-doped. The involved interplay of spin and charge dynamics is a challenge for theory. In this article we propose to describe hole-doped Heisenberg spin rings by means of complete numerical diagonalization of a Heisenberg Hamiltonian that depends parametrically on hole positions and includes the screened Coulomb interaction among the holes. It is demonstrated that key observables like magnetic susceptibility, specific heat, and inelastic neutron scattering cross section depend sensitively on the dielectric constant of the screened Coulomb potential.

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

    NASA Astrophysics Data System (ADS)

    Feranchuk, I. D.; Skoromnik, O. D.

    2010-11-01

    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.

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

    SciTech Connect

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

    2014-06-15

    The relativistic effects in the photoionization of hydrogen-like ion with screened Coulomb interaction of Yukawa type are studied for a broad range of screening lengths and photoelectron energies. The bound and continuum wave functions have been determined by solving the Dirac equation. The study is focused on the relativistic effects manifested in the characteristic features of photoionization cross section for electric dipole nl→ε,l±1 transitions: shape resonances, Cooper minima and cross section enhancements due to near-zero-energy states. It is shown that the main source of relativistic effects in these cross section features is the fine-structure splitting of bound state energy levels. The relativistic effects are studied in the photoionization of Fe{sup 25+} ion, as an example.

  18. Coulomb gauge approach for charmonium meson and hybrid radiative transitions

    DOE PAGESBeta

    Gou, Peng; Yepez-Martínez, Tochtli; Szczepaniak, Adam P.

    2015-01-22

    We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

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

    NASA Astrophysics Data System (ADS)

    Narojczyk, Jakub W.; Pigłowski, Paweł M.; Wojciechowski, Krzysztof W.; Tretiakov, Konstantin V.

    2015-07-01

    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.

  20. Dynamical chiral symmetry breaking in Yukawa and Wess-Zumino models

    SciTech Connect

    Bashir, A.; Diaz Cruz, J. L.

    1999-10-25

    We study dynamical mass generation for fermions in the Yukawa and the supersymmetric Wess-Zumino (WZ) models. It is found that above a critical coupling fermion mass can be generated dynamically in the Yukawa model, whereas in the WZ model the fermion does not acquire mass. We also show that the supersymmetry (SUSY) preserving solution is permitted and hence the scalars may not acquire mass either.

  1. Instanton induced Yukawa couplings from distant E3 and E(-1) instantons

    NASA Astrophysics Data System (ADS)

    Goodsell, Mark D.; Witkowski, Lukas T.

    2016-01-01

    We calculate non-perturbative contributions to Yukawa couplings on D3-branes at orbifold singularities due to E3 and fractional E(-1) instantons which do not intersect the visible sector branes. While distant E3 instantons on bulk cycles typically contribute to Yukawa couplings, we find that distant fractional E(-1) can also give rise to new Yukawa couplings. However, fractional E(-1) instantons only induce Yukawa couplings if they are located at a singularity which shares a collapsed homologous two-cycle with the singularity supporting the visible sector. The non-perturbative contributions to Yukawa couplings exhibit a different flavour structure than the tree-level Yukawa couplings and, as a result, they can be sources of flavour violation. This is particularly relevant for schemes of moduli stabilisation which rely on superpotential contributions from E3 instantons, such as KKLT or the Large Volume Scenario. As a byproduct of our analysis, we shed some new light on the properties of annulus diagrams with matter field insertions in stringy instanton calculus.

  2. PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Neilson, David; Senatore, Gaetano

    2009-05-01

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

  3. Coulomb branch localization in quiver quantum mechanics

    NASA Astrophysics Data System (ADS)

    Ohta, Kazutoshi; Sasai, Yuya

    2016-02-01

    We show how to exactly calculate the refined indices of {N}=4U(1)× U(N) supersymmetric quiver quantum mechanics in the Coulomb branch by using the localization technique. The Coulomb branch localization is discussed from the viewpoint of both non-linear and gauged linear sigma models. A classification of fixed points in the Coulomb branch differs from one in the Higgs branch, but the derived indices completely agree with the results which were obtained by the localization in the Higgs branch. In the Coulomb branch localization, the refined indices can be written as a summation over different sets of the Coulomb branch fixed points. We also discuss a space-time picture of the fixed points in the Coulomb branch.

  4. Controlling the electrostatic Coulomb interaction using metamaterials

    NASA Astrophysics Data System (ADS)

    Karakasoglu, Ilker; Fan, Shanhui

    2016-02-01

    We study electrostatic screening in two classes of metamaterials. The first class consists of a cubic array of metal cubes, which is known to give rise to a positive local dielectric function. We show that such a local positive dielectric function also correctly describes its electrostatic behavior. The second class consists of a variety of wire media that have a strong nonlocal response in their dielectric function. We show that in these wire media, the electrostatic potential generated by a point charge decays exponentially as a function of distance from the charge, and such an exponential screening is intrinsically related to the nonlocal behavior of the dielectric function. We also show, surprisingly, that the electrostatic behavior in some of these wire media is isotropic in spite of the strong anisotropy in the dielectric tensor. Our work here provides an understanding of how to geometrically control electrostatic screening and Coulomb interaction in metamaterials.

  5. Fermionic dark matter with pseudo-scalar Yukawa interaction

    SciTech Connect

    Ghorbani, Karim

    2015-01-01

    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{sub 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{sub DM} ∼ 38 GeV annihilating predominantly into b quarks, which can explain the Fermi-LAT galactic gamma-ray excess.

  6. Coulomb gauge approach to scalar hadrons

    SciTech Connect

    Cotanch, Steve; General, Ignacio; Wang, Ping; Llanes-Estrada, Felipe

    2008-08-31

    The Coulomb gauge model, involving an effective QCD Hamiltonian in the Coulomb gauge, is applied to scalar hadrons. Mass predictions are presented for both conventional qq-bar meson and qq-barqq-bar tetra-quark states. Mixing matrix elements between these states were also computed and diagonalized to provide a reasonable description of the scalar spectrum below 2 GeV.

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

    SciTech Connect

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

    2009-10-15

    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. Our model does not contain external drive or plasma interactions that serve to drive the system away from thermodynamic equilibrium. 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}<{tau}{sub {delta}}, where {tau}{sub {delta}} is the time at which the standard deviation {sigma}({tau}){identical_to}<{xi}{sup 2}({tau})>{sup 1/2} approaches the mean intergrain distance {delta}. Others are development of humps in the distributions on multiples of {delta}, anomalous Hurst exponents, and transitions from leptokurtic toward Gaussian displacement distributions on time scales {tau}>{tau}{sub {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. These intermittency features are quantitatively modeled by a single-particle Ito-Langevin stochastic equation with a nonlinear drift term.

  8. Higgs-Yukawa model with higher dimension operators via extended mean field theory

    NASA Astrophysics Data System (ADS)

    Akerlund, Oscar; de Forcrand, Philippe

    2016-02-01

    Using extended mean field theory (EMFT) on the lattice, we study properties of the Higgs-Yukawa model as an approximation of the standard model Higgs sector, and the effect of higher dimension operators. We remark, as has been noted before, that the discussion of vacuum stability is completely modified in the presence of a ϕ6 term, and that the Higgs mass no longer appears fine tuned. We also study the finite temperature transition. Without higher dimension operators the transition is found to be second order (crossover with gauge fields) for the experimental value of the Higgs mass Mh=125 GeV . By taking a ϕ6 interaction in the Higgs potential as a proxy for a UV completion of the standard model, the transition becomes stronger and turns first order if the scale of new physics, i.e., the mass of the lightest mediator particle, is around 1.5 TeV. This implies that electroweak baryogenesis may be viable in models which introduce new particles around that scale.

  9. Observation of the Rayleigh-Bénard convection cells in strongly coupled Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Charan, Harish; Ganesh, Rajaraman

    2015-08-01

    Using "first principles" molecular dynamics simulation, we report for the first time the formation of Rayleigh-Bénard convection cells (RBCC) in two-dimensional strongly coupled Yukawa liquids, characterized by coupling strength Γ (ratio of average potential energy to kinetic energy per particle) and screening parameter κ (ratio of average inter-particle distance to Debye length). For typical values of (Γ, κ), existence of a critical external temperature difference is demonstrated, beyond which RBCC are seen to set in. Beyond this critical external temperature difference, the strength of the maximum convective flow velocity is shown to exhibit a new, hitherto unsuspected linear relationship with external temperature difference and with a slope independent of (Γ, κ). The time taken for the transients to settle down (τs) to a steady state RBCC is found to be maximum close to the above said critical external temperature difference and is seen to reduce with increasing external temperature difference. For the range of values of (Γ, κ) considered here, τs ≈ 10 000-20 000 ωpd-1 , where ωpd is dust plasma frequency. As Γ is increased to very high values, due to strong coupling effects, cells are seen to be in a transient state without attaining a steady state for as long as 100 000 ωpd-1 , even for a very high external temperature difference. Role of system size, aspect ratio, and dust-neutral collisions has also been addressed.

  10. Coulomb's law for rolling friction

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2016-03-01

    Measurements are presented on the coefficient of rolling friction for steel balls rolling on hard surfaces. Two simple techniques are described, both suitable for use in a student laboratory, and both capable of measuring friction coefficients as small as 0.0001. The coefficient of rolling friction depends strongly on ball radius, an effect first observed by Coulomb in 1785. In this work, the dependence on ball radius is found to be similar to that observed by Tabor in 1955 using steel balls on rubber and on soft metal surfaces. However, it is found that rolling friction on a hard surface is due primarily to surface roughness rather than the hysteresis losses commonly associated with soft balls or soft surfaces. It is also found that the coefficient of rolling friction is approximately proportional to rolling speed.

  11. PREFACE: Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    In this paper we study an SO(10) SUSY GUT with Yukawa unification for the third generation. We perform a global χ2 analysis given to obtain the GUT boundary conditions consistent with 11 low-energy observables, including the top, bottom and tau masses. We assume a universal mass, m16, for squarks and sleptons and a universal gaugino mass, M1/2. We then analyze the phenomenological consequences for the LHC for 15 benchmark models with fixed m16=20TeV and with varying values of the gluino mass. The goal of the present work is to (i) evaluate the lower bound on the gluino mass in our model coming from the most recent published data of CMS and (ii) to compare this bound with similar bounds obtained by CMS using simplified models. The bottom line is that the bounds coming from the same-sign dilepton analysis are comparable for our model and the simplified model studied assuming B(g˜→tt¯χ˜10)=100%. However the bounds coming from the purely hadronic analyses for our model are 10%-20% lower than obtained for the simplified models. This is due to the fact that for our models the branching ratio for the decay g˜→gχ˜1,20 is significant. Thus there are significantly fewer b-jets. We find a lower bound on the gluino mass in our models with Mg˜≳1000GeV. Finally, there is a theoretical upper bound on the gluino mass which increases with the value of m16. For m16≤30TeV, the gluino mass satisfies Mg˜≤2.8TeV at 90% C.L. Thus, unless we further increase the amount of fine-tuning, we expect gluinos to be discovered at LHC 14.

  14. Quasi-localized wavefunctions on magnetized tori and tiny neutrino Yukawa couplings

    NASA Astrophysics Data System (ADS)

    Sumita, Keigo

    2016-01-01

    This paper shows that, a quasi-localization of wavefunctions in toroidal compactifications with magnetic fluxes can lead to a strong suppression for relevant Yukawa couplings, and it is applicable to obtain tiny neutrino masses. Although it is known that magnetic fluxes lead to a Gaussian profile of zero-modes on a torus and that can yield a suppressed coupling in higher-dimensional supersymmetric Yang-Mills (SYM) theories, the largest (diagonal) entry of Yukawa matrices is always of O(1) . In this paper, we propose a way to induce an absolutely tiny global factor of Yukawa matrices. In two SYM theories defined in different dimensional spacetime, their bifundamental representations must be localized as a point in some directions. Overlaps of such point-like localized wavefunctions and Gaussian zero-modes give a global factor of Yukawa matrices, and it can be a strong suppression factor or a usual O(1) factor, corresponding to their distance. Our numerical analysis shows that it is possible to obtain a suppression strong enough to realize the tiny neutrino masses without a fine-tuning. Furthermore, we propose a concrete model in a magnetized SYM system and demonstrate the mechanism to generate the tiny neutrino Yukawa couplings.

  15. Quantum solution for the one-dimensional Coulomb problem

    SciTech Connect

    Nunez-Yepez, H. N.; Salas-Brito, A. L.; Solis, Didier A.

    2011-06-15

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

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

    SciTech Connect

    Lee, C. M. E-mail: apkschan@cityu.edu.hk; Chan, K. S. E-mail: apkschan@cityu.edu.hk

    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.

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

    NASA Technical Reports Server (NTRS)

    Au, C. K.

    1988-01-01

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

  18. Poisson Green's function method for increased computational efficiency in numerical calculations of Coulomb coupling elements

    NASA Astrophysics Data System (ADS)

    Zimmermann, Anke; Kuhn, Sandra; Richter, Marten

    2016-01-01

    Often, the calculation of Coulomb coupling elements for quantum dynamical treatments, e.g., in cluster or correlation expansion schemes, requires the evaluation of a six dimensional spatial integral. Therefore, it represents a significant limiting factor in quantum mechanical calculations. If the size or the complexity of the investigated system increases, many coupling elements need to be determined. The resulting computational constraints require an efficient method for a fast numerical calculation of the Coulomb coupling. We present a computational method to reduce the numerical complexity by decreasing the number of spatial integrals for arbitrary geometries. We use a Green's function formulation of the Coulomb coupling and introduce a generalized scalar potential as solution of a generalized Poisson equation with a generalized charge density as the inhomogeneity. That enables a fast calculation of Coulomb coupling elements and, additionally, a straightforward inclusion of boundary conditions and arbitrarily spatially dependent dielectrics through the Coulomb Green's function. Particularly, if many coupling elements are included, the presented method, which is not restricted to specific symmetries of the model, presents a promising approach for increasing the efficiency of numerical calculations of the Coulomb interaction. To demonstrate the wide range of applications, we calculate internanostructure couplings, such as the Förster coupling, and illustrate the inclusion of symmetry considerations in the method for the Coulomb coupling between bound quantum dot states and unbound continuum states.

  19. Spin-dependent tunneling with Coulomb blockade

    NASA Astrophysics Data System (ADS)

    Schelp, L. F.; Fert, A.; Fettar, F.; Holody, P.; Lee, S. F.; Maurice, J. L.; Petroff, F.; Vaurès, A.

    1997-09-01

    We have fabricated Co/Al2O3/Co tunnel junctions in which the Al2O3 layer includes a unique layer of small and disconnected cobalt clusters, with a typical mean diameter ranging from 2.0 to 4.0 nm. We observe spin-dependent tunneling properties with, below about 50 K, typical Coulomb-blockade effects induced by intermediate electron tunneling into cobalt clusters. The tunnel magnetoresistance ratio is approximately the same in the Coulomb-blockade regime (low-temperature range with very high tunnel resistance) and in the room-temperature regime without Coulomb blockade. It also depends weakly on the applied voltage.

  20. 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.

  1. Non-minimal coupling in Higgs–Yukawa model with asymptotically safe gravity

    NASA Astrophysics Data System (ADS)

    Oda, Kin-ya; Yamada, Masatoshi

    2016-06-01

    We study the fixed-point structure of the Higgs–Yukawa model, with its scalar being non-minimally coupled to the asymptotically safe gravity, using the functional renormalization group. We have obtained the renormalization group equations for the cosmological and Newton constants, the scalar mass squared and quartic coupling constant, and the Yukawa and non-minimal coupling constants, taking into account all the scalar, fermion, and graviton loops. We find that switching on the fermionic quantum fluctuations makes the non-minimal coupling constant irrelevant around the Gaussian-matter fixed point with asymptotically safe gravity.

  2. 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.С., Wimberly S.C. 51st AIAA Aerospace Science Meeting 2013 (AIAA 2013-0810). 2. http://dev.spis.org/projects/spine/home/spis

  3. Effect of Coulomb screening length on nuclear "pasta" simulations

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. 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

  5. Second Born approximation and Coulomb scattering

    NASA Astrophysics Data System (ADS)

    Holstein, Barry R.

    2007-06-01

    We examine the problem of calculating higher order contributions to the Coulomb scattering amplitude. To make contact with the well known result, it is necessary to modify the conventional definition of the scattering amplitude.

  6. Quarks in Coulomb gauge perturbation theory

    SciTech Connect

    Popovici, C.; Watson, P.; Reinhardt, H.

    2009-02-15

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

  7. Recent developments in Coulomb breakup calculations

    SciTech Connect

    Capel, P.

    2008-05-12

    The theory of reactions applied to Coulomb breakup of loosely-bound projectiles is reviewed. Both the Continuum Discretized Coupled Channel (CDCC) and time-dependent models are described. Recent results about sensitivity of breakup calculations to the projectile wave function are reviewed. Analyses of the extraction of radiative-capture cross section from Coulomb breakup measurements are presented. Current developments in breakup theory are also mentioned.

  8. Coulomb crystallization of sympathetically cooled highly charged ions

    NASA Astrophysics Data System (ADS)

    Crespo López-Urrutia, José R.

    2015-05-01

    Wave functions of inner-shell electrons significantly overlap with the nucleus, whereby enormously magnified relativistic, quantum electrodynamic (QED) and nuclear size effects emerge. In highly charged ions (HCI), the relative reduction of electronic correlations contributions improves the visibility of these effects. This well known facts have driven research efforts with HCI, yet the typically high temperatures at which these can be prepared in the laboratory constitutes a serious hindrance for application of laser spectroscopic methods. The solution for this, cooling HCI down to crystallization has remained an elusive target for more than two decades. By applying laser cooling to an ensemble of Be+ ions, we build Coulomb crystals that we use for stopping the motion of HCI and for cooling them. HCI, in this case Ar13+ ions are extracted from an electron beam ion trap with an energy spread of a few 100's of eV, due to the ion temperature within the trap. Carefully timed electric pulses in a potential-gradient decelerate and bunch the HCI. We achieve Coulomb crystallization of these HCI by re-trapping them in a cryogenic linear radiofrequency trap where they are sympathetically cooled through Coulomb interaction with the directly laser-cooled ensemble. Furthermore, we also demonstrate cooling of a single Ar13+ ion by a single Be+ ion, prerequisite for quantum logic spectroscopy with potentially 10-19 relative accuracy. The strongly suppressed thermal motion of the embedded HCI offers novel possibilities for investigation of questions related to the time variation of fundamental constants, parity non-conservation effects, Lorentz invariance and quantum electrodynamics. Achieving a seven orders-of-magnitude decrease in HCI temperature, from the starting point at MK values in the ion source down to the mK range within the Coulomb crystal eliminates the major obstacle for HCI investigation with high precision laser spectroscopy and quantum computation schemes.

  9. Laser Coulomb explosion imaging of molecular dynamics

    NASA Astrophysics Data System (ADS)

    Bocharova, Irina A.

    2009-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Last, Isidore; Levy, Yaakov; Jortner, Joshua

    2002-07-01

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

  11. Temperature dependence of Coulomb oscillations in a few-layer two-dimensional WS2 quantum dot

    PubMed Central

    Song, Xiang-Xiang; Zhang, Zhuo-Zhi; You, Jie; Liu, Di; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Guo, Guo-Ping

    2015-01-01

    Standard semiconductor fabrication techniques are used to fabricate a quantum dot (QD) made of WS2, where Coulomb oscillations were found. The full-width-at-half-maximum of the Coulomb peaks increases linearly with temperature while the height of the peaks remains almost independent of temperature, which is consistent with standard semiconductor QD theory. Unlike graphene etched QDs, where Coulomb peaks belonging to the same QD can have different temperature dependences, these results indicate the absence of the disordered confining potential. This difference in the potential-forming mechanism between graphene etched QDs and WS2 QDs may be the reason for the larger potential fluctuation found in graphene QDs. PMID:26538164

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

    SciTech Connect

    Li Tianjun

    2010-03-15

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

  13. 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.

  14. Photoelectron wave function in photoionization: plane wave or Coulomb wave?

    PubMed

    Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

    2015-11-19

    The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion. PMID:26509428

  15. Exact SU(5) Yukawa matrix unification in the general flavour violating MSSM

    NASA Astrophysics Data System (ADS)

    Iskrzyński, Mateusz; Kowalska, Kamila

    2015-04-01

    We investigate the possibility of satisfying the SU(5) boundary condition Y d = Y eT at the GUT scale within the renormalizable R-parity conserving Minimal Supersymmetric Standard Model (MSSM). Working in the super-CKM basis, we consider non-zero flavour off-diagonal entries in the soft SUSY-breaking mass matrices and the A-terms. At the same time, the diagonal A-terms are assumed to be suppressed by the respective Yukawa couplings. We show that a non-trivial flavour structure of the soft SUSY-breaking sector can contribute to achieving precise Yukawa coupling unification for all three families, and that the relevant flavour-violating parameters are , , and A {12/21/ d }. We indicate the parameter space regions where the Yukawa unification condition can be satisfied, and we demonstrate that it is consistent with a wide set of experimental constraints, including flavour and electroweak observables, Higgs physics and the LHC bounds. However, as a consequence of the down-electron Yukawa unification requirement, the MSSM vacuum in our scenario is metastable, though long-lived. We also point out that the lightest neutralino needs to be almost purely bino-like and relatively light, with the mass in the ballpark of 250 GeV. Since the proper value of the dark matter relic density is in this case obtained through co-annihilation with a sneutrino, at least one generation of sleptons must be light. Such a clear experimental prediction makes the flavour-violating SU(5) Yukawa unification scenario fully testable at the LHC TeV with the 3-lepton searches for electroweakino production.

  16. Quantum magnetotransport in two-dimensional Coulomb liquids

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

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

  17. Coulombic effect and renormalization in nuclear pairing

    SciTech Connect

    Nakada, H.; Yamagami, M.

    2011-03-15

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

  18. Coulomb force as an entropic force

    SciTech Connect

    Wang Tower

    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.

  19. 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 δ-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

  20. The Legacy of Hideki Yukawa, Sin-itiro Tomonaga, and Shoichi Sakata: Some Aspects from their Archives

    NASA Astrophysics Data System (ADS)

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

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

  1. Evolution of Yukawa couplings and quark flavor mixings in two universal extra dimension models

    NASA Astrophysics Data System (ADS)

    Abdalgabar, Ammar; Cornell, A. S.; Deandrea, Aldo; Tarhini, Ahmad

    2013-09-01

    The evolution equations of the Yukawa couplings and quark mixings are derived for the one-loop renormalization group equations in six-dimensional models, compactified in different possible ways to yield standard four space-time dimensions. Different possibilities for the matter fields are also discussed, such as the case of bulk propagating or brane localized fields. We discuss in both cases the evolution of the Yukawa couplings, the Jarlskog parameter and the Cabibbo-Kobayashi-Maskawa matrix element, and find that for both scenarios, as we run up to the unification scale, significant renormalization group corrections are present. We also discuss the results of different observables of the five-dimensional universal extra dimension model in comparison with these six-dimensional models and the model dependence of the results.

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

    SciTech Connect

    Gomez, Mario E.; Ibrahim, Tarek; Nath, Pran; Skadhauge, Solveig

    2005-11-01

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

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

    SciTech Connect

    Ashwin, J.; Ganesh, R.

    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.

  4. Remarkable coincidence for the top Yukawa coupling and an approximately massless bound state

    SciTech Connect

    Froggatt, C. D.; Nielsen, H. B.

    2009-08-01

    We calculate, with several corrections, the nonrelativistic binding by Higgs exchange and gluon exchange between six top and six antitop quarks (actually replaced by left-handed b quarks from time to time). The remarkable result is that, within our calculational accuracy of the order of 14% in the top-quark Yukawa coupling g{sub t}, the experimental running top-quark Yukawa coupling g{sub t}=0.935 happens to have just that value which gives a perfect cancellation of the unbound mass=12 top-quark masses by this binding energy. In other words the bound state is massless to the accuracy of our calculation. Our calculation is in disagreement with a similar calculation by Kuchiev et al., but this deviation may be explained by a phase transition. We and Kuchiev et al. compute on different sides of this phase transition.

  5. Yukawa couplings in string theory: the case for F-theory GUT's

    NASA Astrophysics Data System (ADS)

    Font, Anamaría

    2015-11-01

    We study the pattern of Yukawa couplings in local F-theory SU(5) GUT's. Couplings for the third family of quarks and leptons appear at the perturbative level, but to reproduce the observed couplings for the lighter families requires non-perturbative dynamics. We show that corrections due to instanton effects do lead to a Yukawa matrix with a hierarchical structure. Our results apply to both down-like and up- like 10 × 10 × 5 couplings. The models include magnetic fluxes needed for a chiral spectrum and for symmetry breaking down to the Standard Model. We compute the holomorphic couplings via residues and then obtain the physical couplings taking into account the normalization of wavefunction profiles. Combining non-perturbative corrections and magnetic fluxes allows to fit the measured masses and hierarchies of the third and second generations in the Standard Model.

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

    NASA Astrophysics Data System (ADS)

    Abdalgabar, Ammar; Cornell, A. S.

    2013-08-01

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

  7. Blowup results for the KGS system with higher order Yukawa coupling

    SciTech Connect

    Shi, Qi-Hong; Li, Wan-Tong; Wang, Shu

    2015-10-15

    In this paper, we investigate the Klein-Gordon-Schrödinger (KGS) system with higher order Yukawa coupling in spatial dimensions N ≥ 3. We establish a perturbed virial type identity and prove blowup results relied on Lyapunov functionals for KGS system with a negative energy level. Additionally, we give a result with respect to the blowup rate in finite time for the radial solution in 3 spatial dimensions.

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

    SciTech Connect

    Shafi, Qaisar

    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.

  9. Exclusive radiative Higgs decays as probes of light-quark Yukawa couplings

    NASA Astrophysics Data System (ADS)

    Knig, Matthias; Neubert, Matthias

    2015-08-01

    We present a detailed analysis of the rare exclusive Higgs boson decays into a single vector meson and a photon and investigate the possibility of using these processes to probe the light-quark Yukawa couplings. We work with an effective Lagrangian with modified Higgs couplings to account for possible new-physics effects in a model-independent way. The h ? V? decay rate is governed by the destructive interference of two amplitudes, one of which involves the Higgs coupling to the quark anti-quark pair inside the vector meson. We derive this amplitude at next-to-leading order in ? s using QCD factorization, including the resummation of large logarithmic corrections and accounting for the effects of flavor mixing. The high factorization scale ? m h ensures that our results are rather insensitive to the hadronic parameters characterizing the light-cone distribution amplitude of the vector meson. The second amplitude arises from the loop-induced effective h?? * and h?Z * couplings, where the off-shell gauge boson converts into the vector meson. We devise a strategy to eliminate theoretical uncertainties related to this amplitude to almost arbitrary precision. This opens up the possibility to probe for modifications of the c- and b-quark Yukawa couplings and modifications of the s-quark Yukawa coupling in the high-luminosity LHC run. In particular, we show that measurements of the ratios Br( h ? ?( nS) ?)/Br( h ? ??) and can provide complementary information on the real and imaginary parts of the b-quark Yukawa coupling. More accurate measurements would be possible at a future 100 TeV proton-proton collider.

  10. Thermodynamic Theory of Spherically Trapped Coulomb Clusters

    NASA Astrophysics Data System (ADS)

    Wrighton, Jeffrey; Dufty, James; Bonitz, Michael; K"{A}Hlert, Hanno

    2009-11-01

    The radial density profile of a finite number of identical charged particles confined in a harmonic trap is computed over a wide ranges of temperatures (Coulomb coupling) and particle numbers. At low temperatures these systems form a Coulomb crystal with spherical shell structure which has been observed in ultracold trapped ions and in dusty plasmas. The shell structure is readily reproduced in simulations. However, analytical theories which used a mean field approachfootnotetext[1]C. Henning et al., Phys. Rev. E 74, 056403 (2006) or a local density approximationfootnotetext[2]C. Henning et al., Phys. Rev. E 76, 036404 (2007) have, so far, only been able to reproduce the average density profile. Here we present an approach to Coulomb correlations based on the hypernetted chain approximation with additional bridge diagrams. It is demonstrated that this model reproduces the correct shell structure within a few percent and provides the basis for a thermodynamic theory of Coulomb clusters in the strongly coupled fluid state.footnotetext[3]J. Wrighton, J.W. Dufty, H. K"ahlert and M. Bonitz, J. Phys. A 42, 214052 (2009) and Phys. Rev. E (2009) (to be submitted)

  11. Coulomb's Electrical Measurements. Experiment No. 14.

    ERIC Educational Resources Information Center

    Devons, Samuel

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

  12. 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.

  13. The Pioneer Anomaly as a Coulomb Attraction

    NASA Astrophysics Data System (ADS)

    Morris, Steven

    2016-06-01

    The anomalous acceleration of the Pioneer 10 and Pioneer 11 spacecraft can be explained as a Coulomb attraction between the positively-charged Solar System (due to cosmic rays) and the negatively-charged spacecraft (due to alpha-particle emission from the radioisotope thermoelectric generators).

  14. 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.

  15. Density profile and breathing mode of strongly correlated spherical Yukawa plasmas

    NASA Astrophysics Data System (ADS)

    Henning, Christian; Fujioka, Kenji; Ludwig, Patrick; Bonitz, Michael

    2007-11-01

    The structure of ``Yukawa balls,'' i.e. spherical 3D dust crystals, which recently have been produced [1], is well explained by computer simulations of charged Yukawa interacting particles within an external parabolic confinement [2]. Dynamical properties (e.g. breathing mode) of these systems were investigated by experiment, simulations as well as theoretically by using the ansatz of a uniform ground state density [3]. Here we show analytically that screening has a dramatic effect on the density profile which decreases away from the center [4,5] and which is in excellent agreement with MD simulations of Yukawa balls. This result is used to improve former calculations of the breathing mode [6].References[1] O. Arp et al. Phys. Rev. Lett. 93, 165004 (2004)[2] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)[3] T. E. Sheridan, Phys. Plasmas 13, 022106 (2006)[4] C. Henning et al., Phys. Rev. E 74, 056403 (2006)[5] C. Henning at al., Phys. Rev. E (2007)[6] C. Henning at al., submitted for publication

  16. Theoretical approach to the ground state of spherically confined Yukawa plasmas

    NASA Astrophysics Data System (ADS)

    Henning, Christian; Bonitz, Michael; Piel, Alexander; Ludwig, Patrick; Baumgartner, Henning

    2007-11-01

    Recently spherical 3D dust crystals (aka Yukawa balls) were discovered [1], which allow direct observation of strong correlation phenomena and the structure of which is well explained by computer simulations of charged Yukawa interacting particles within an external parabolic confinement [2]. Here we present an analytical approach to the ground state of these systems using the minimization of the system's energy. Applying the non-local mean-field approximation we show that screening has a dramatic effect on the density profile, which can be derived explicitly [3]. In addition the local density approximation allows for the inclusion of correlations, which further improves the results in the regime of large screening [4]. Comparisons with MD simulations of Yukawa balls show excellent agreement.[1] O. Arp et al. Phys. Rev. Lett. 93, 165004 (2004)[2] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)[3] C. Henning et al., Phys. Rev. E 74, 056403 (2006)[4] C. Henning at al., Phys. Rev. E (2007)

  17. Numerical experiment of thermal conductivity in two-dimensional Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Shahzad, Aamir; He, Mao-Gang

    2015-12-01

    A newly improved homogenous nonequilibrium molecular dynamics simulation (HNEMDS) method, proposed by the Evans, has been used to compute the thermal conductivity of two-dimensional (2D) strongly coupled complex (dusty) plasma liquids (SCCDPLs), for the first time. The effects of equilibrium external field strength along with different system sizes and plasma states (?, ?) on the thermal conductivity of SCCDPLs have been calculated using an enhanced HNEMDS method. A simple analytical temperature representation of Yukawa 2D thermal conductivity with appropriate normalized frequencies (plasma and Einstein) has also been calculated. The new HNEMDS algorithm shows that the present method provides more accurate results with fast convergence and small size effects over a wide range of plasma states. The presented thermal conductivity obtained from HNEMDS method is found to be in very good agreement with that obtained through the previously known numerical simulations and experimental results for 2D Yukawa liquids (SCCDPLs) and with the three-dimensional nonequilibrium molecular dynamics simulation (MDS) and equilibrium MDS calculations. It is shown that the HNEMDS algorithm is a powerful tool, making the calculations very efficient and can be used to predict the thermal conductivity in 2D Yukawa liquid systems.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    SciTech Connect

    Zhang, Xiaoguang; Xiang, T.

    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.

  20. 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 (γH = 2) and eight (γ1st = 8) Gaussians on hydrogen and first-row atoms, respectively, with exponents greater than a given threshold (α _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.

  1. Charge and color breaking constraints in the Minimal Supersymmetric Standard Model associated with the bottom Yukawa coupling

    NASA Astrophysics Data System (ADS)

    Hollik, Wolfgang Gregor

    2016-01-01

    Testing the stability of the electroweak vacuum in any extension of the Standard Model Higgs sector is of great importance to verify the consistency of the theory. Multi-scalar extensions as the Minimal Supersymmetric Standard Model generically lead to unstable configurations in certain regions of parameter space. An exact minimization of the scalar potential is rather an impossible analytic task. To give handy analytic constraints, a specific direction in field space has to be considered which is a simplification that tends to miss excluded regions, however good to quickly check parameter points. We describe a yet undescribed class of charge and color breaking minima as they appear in the Minimal Supersymmetric Standard Model, exemplarily for the case of non-vanishing bottom squark vacuum expectation values constraining the combination μYb in a non-trivial way. Contrary to famous A-parameter bounds, we relate the bottom Yukawa coupling with the supersymmetry breaking masses. Another bound can be found relating soft breaking masses and μ only. The exclusions follow from the tree-level minimization and can change dramatically using the one-loop potential. Estimates of the lifetime of unstable configurations show that they are either extremely short- or long-lived.

  2. Exact linearized Coulomb collision operator in the moment expansion

    DOE PAGESBeta

    Ji, Jeong -Young; Held, Eric D.

    2006-10-05

    In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collisionmore » operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Furthermore, useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.« less

  3. Enhancement of the Coulomb collision rate by individual particle wakes

    NASA Astrophysics Data System (ADS)

    Baalrud, Scott; Scheiner, Brett

    2013-09-01

    Charged particles moving in a plasma leave a trailing wake in their electric potential profile associated with the response function of the medium. For superthermal particles, these wakes can cause significant departures from the oft-assumed screened Coulomb potential profile. The wakes extend the interaction length scale beyond the Debye screening length for collisions between fast test particles and field particles in their wake. This can increase the Coulomb collision rate for velocities beyond the thermal speed. To demonstrate this effect, we consider the relaxation rate due to electron-electron collisions of an electron distribution function with initially depleted tails, as is common near boundary sheaths or double layers. This problem is related to Langmuir's paradox. We compare the standard Landau (Fokker-Planck) collision operator, which does not account for wakes, with the Lenard-Balescu collision operator, which includes wake effects through the linear dielectric response function. For this distribution, the linear dielectric is described by the incomplete plasma dispersion function. We compare the collision operators directly as well as the relaxation rate determined from a hybrid kinetic-fluid model. S. D. Baalrud, Phys. Plasmas 20, 012118 (2013).

  4. Exact linearized Coulomb collision operator in the moment expansion

    SciTech Connect

    Ji, Jeong -Young; Held, Eric D.

    2006-10-05

    In the moment expansion, the Rosenbluth potentials, the linearized Coulomb collision operators, and the moments of the collision operators are analytically calculated for any moment. The explicit calculation of Rosenbluth potentials converts the integro-differential form of the Coulomb collision operator into a differential operator, which enables one to express the collision operator in a simple closed form for any arbitrary mass and temperature ratios. In addition, it is shown that gyrophase averaging the collision operator acting on arbitrary distribution functions is the same as the collision operator acting on the corresponding gyrophase averaged distribution functions. The moments of the collision operator are linear combinations of the fluid moments with collision coefficients parametrized by mass and temperature ratios. Furthermore, useful forms involving the small mass-ratio approximation are easily found since the collision operators and their moments are expressed in terms of the mass ratio. As an application, the general moment equations are explicitly written and the higher order heat flux equation is derived.

  5. Integrability and separation of variables in Calogero-Coulomb-Stark and two-center Calogero-Coulomb systems

    NASA Astrophysics Data System (ADS)

    Hakobyan, Tigran; Nersessian, Armen

    2016-02-01

    We propose the integrable N -dimensional Calogero-Coulomb-Stark and two-center Calogero-Coulomb systems and construct their constants of motion via the Dunkl operators. Their Schrödinger equations decouple in parabolic and elliptic coordinates into the set of three differential equations like for the Coulomb-Stark and two-center Coulomb problems. The Calogero term preserves the energy levels, but changes their degrees of degeneracy.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  7. "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 with time of both the aerodynamic and bed-dilatancy thresholds (3). Because of Paschen discharge effects in the martian atmosphere, the electrostatic charging in a saltation cloud may be partially abated, but this will lead to greater grain mobility, more charging, and thus to a charge-discharge steady state mediated by mechanical interactions. II. Dry colluvial systems: Sand avalanches on dunes, dry debris flows, talus flows, avalanches, and pyroclastic surges are examples of gravity-driven, dense granular flows where rock/grain fragmentation and grain-to-grain interactions cause triboelectrification (sometimes augmented by other electrical charging processes), and where the grain densities of the systems are such that strong dipole-dipole interactions between grains might be expected to be present. Because it is expected that the Coulombic forces between grains will cause a sluggishness or enhanced granular-flow viscosity, the motion of a grain mass will be retarded or damped so that this will assist, ultimately, in terminating the flow. The greatest Coulombic viscosity will be created in the most highly charged systems, which will also be the most energetic. Thus, grain flows have some tendency to be self-limiting by internal energy partitioning; gravitational potential is converted to Coulombic potential, which manifests itself as a drag force between the grains. III. Volcanic eruption plumes and impact ejecta curtains: The violence of these systems leads to powerful electrical charging of particulates. Lightning storms emanating from volcanic plumes are a testimony to the levels of charging. As pyroclastic grains interact forcefully and frequently within eruption plumes, it is reasonable to predict that the internal turbulent motions of the plume will be significantly damped by the Coulombic viscosity exerted by grain charges. Additional information is contained in the original.

  8. "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 increase with time of both the aerodynamic and bed-dilatancy thresholds (3). Because of Paschen discharge effects in the martian atmosphere, the electrostatic charging in a saltation cloud may be partially abated, but this will lead to greater grain mobility, more charging, and thus to a charge-discharge steady state mediated by mechanical interactions. II. Dry colluvial systems: Sand avalanches on dunes, dry debris flows, talus flows, avalanches, and pyroclastic surges are examples of gravity-driven, dense granular flows where rock/grain fragmentation and grain-to-grain interactions cause triboelectrification (sometimes augmented by other electrical charging processes), and where the grain densities of the systems are such that strong dipole-dipole interactions between grains might be expected to be present. Because it is expected that the Coulombic forces between grains will cause a sluggishness or enhanced granular-flow viscosity, the motion of a grain mass will be retarded or damped so that this will assist, ultimately, in terminating the flow. The greatest Coulombic viscosity will be created in the most highly charged systems, which will also be the most energetic. Thus, grain flows have some tendency to be self-limiting by internal energy partitioning; gravitational potential is converted to Coulombic potential, which manifests itself as a drag force between the grains. III. Volcanic eruption plumes and impact ejecta curtains: The violence of these systems leads to powerful electrical charging of particulates. Lightning storms emanating from volcanic plumes are a testimony to the levels of charging. As pyroclastic grains interact forcefully and frequently within eruption plumes, it is reasonable to predict that the internal turbulent motions of the plume will be significantly damped by the Coulombic viscosity exerted by grain charges. Additional information is contained in the original.

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

    NASA Astrophysics Data System (ADS)

    Diaz-Torres, Alexis; Wiescher, Michael

    2014-03-01

    A preliminary study of the 12C + 12C sub-Coulomb fusion reaction using the time-dependent wave-packet method is presented. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.

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

    SciTech Connect

    Reinhardt, H. Schleifenbaum, W.

    2009-04-15

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

  11. Feynman rules for Coulomb gauge QCD

    SciTech Connect

    Andrasi, A.; Taylor, J.C.

    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.

  12. Coulomb drag in topological insulator films

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Liu, Weizhe Edward; Culcer, Dimitrie

    2016-05-01

    We study Coulomb drag between the top and bottom surfaces of topological insulator films. We derive a kinetic equation for the thin-film spin density matrix containing the full spin structure of the two-layer system, and analyze the electron-electron interaction in detail in order to recover all terms responsible for Coulomb drag. Focusing on typical topological insulator systems, with a film thicknesses d up to 6 nm, we obtain numerical and approximate analytical results for the drag resistivity ρD and find that ρD is proportional to T2d-4 na-3/2 np-3/2 at low temperature T and low electron density na,p, with a denoting the active layer and p the passive layer. In addition, we compare ρD with graphene, identifying qualitative and quantitative differences, and we discuss the multi-valley case, ultra thin films and electron-hole layers.

  13. Coulomb scattering and transport in graphene

    NASA Astrophysics Data System (ADS)

    Novikov, Dmitry

    2008-03-01

    The exact transport cross-section off a Coulomb impurity in graphene [1] is proportional to the carrier wavelength. Unexpectedly, the relativistic Coulomb scattering also exhibits a pronounced attraction-repulsion asymmetry [1,2]: Massless carriers are scattered more strongly when they are attracted to a charged impurity than when they are repelled from it. This finding, confirmed recently [3], can be used to separately determine the surface density of donors and acceptors in a graphene monolayer [2]. I will outline quantitative and qualitative differences between the exact result [1] and the commonly used Born approximation for charged impurity scattering. [1] D. S. Novikov, arXiv:0706.1391, Phys. Rev. B (in press); [2] D. S. Novikov, Appl. Phys. Lett. 91, 102102 (2007); [3] J. H. Chen, C. Jang, M. S. Fuhrer, E. D. Williams, M. Ishigami, arXiv:0708.2408v2.

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

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

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

  15. Coulomb dissociation of {sup 27} P

    SciTech Connect

    Beceiro, S.; Cortina-Gil, D.; Suemmerer, K.

    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.

  16. Coulomb collision effects on linear Landau damping

    SciTech Connect

    Callen, J. D.

    2014-05-15

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

  17. Fermi-edge transmission resonance in graphene driven by a single Coulomb impurity.

    PubMed

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

    2014-07-11

    The interaction between the Fermi sea of conduction electrons and a nonadiabatic attractive impurity potential can lead to a power-law divergence in the tunneling probability of charge through the impurity. The resulting effect, known as the Fermi edge singularity (FES), constitutes one of the most fundamental many-body phenomena in quantum solid state physics. Here we report the first observation of FES for Dirac fermions in graphene driven by isolated Coulomb impurities in the conduction channel. In high-mobility graphene devices on hexagonal boron nitride substrates, the FES manifests in abrupt changes in conductance with a large magnitude ≈e(2)/h at resonance, indicating total many-body screening of a local Coulomb impurity with fluctuating charge occupancy. Furthermore, we exploit the extreme sensitivity of graphene to individual Coulomb impurities and demonstrate a new defect-spectroscopy tool to investigate strongly correlated phases in graphene in the quantum Hall regime. PMID:25062215

  18. 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.)

  19. Exciton condensation and perfect Coulomb drag.

    PubMed

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

    2012-08-23

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

  20. Pore fluid pressure, apparent friction, and Coulomb failure

    USGS Publications Warehouse

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

    2000-01-01

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

  1. Coulomb-stable triply charged diatomic: HeY3+

    NASA Astrophysics Data System (ADS)

    Wesendrup, Ralf; Pernpointner, Markus; Schwerdtfeger, Peter

    1999-11-01

    Accurate relativistic coupled-cluster calculations show that the triply charged species HeY3+ is a stable molecule and represents the lightest diatomic trication that does not undergo a Coulomb fragmentation into charged fragments. The diatomic potential-energy curve is approximated by an extended Morse potential, and vibrational-rotational constants for HeY3+ are predicted (Re=224.3 pm, D0=0.394 eV, ωe=437 cm-1, ωexe=15.8 cm-1, Be=0.877 cm-1). It is further shown that the He-Y3+ bond can basically be described as a charge-induced dipole interaction.

  2. 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 η∞, 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 η∞, for smaller volume fractions up to about 10% and 20%, respectively. The second scheme is a hybrid method combining the virtues of the δγ 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.

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

    SciTech Connect

    Freitas, Ayres; Skands, Peter Z.; Spira, M.; Zerwas, P.M.; /DESY

    2007-03-01

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

  4. Decay of a Yukawa fermion at finite temperature and applications to leptogenesis

    SciTech Connect

    Kiessig, Clemens P.; Pluemacher, Michael; Thoma, Markus H.

    2010-08-01

    We calculate the decay rate of a Yukawa fermion in a thermal bath using finite-temperature cutting rules and effective Green's functions according to the hard thermal loop resummation technique. We apply this result to the decay of a heavy Majorana neutrino in leptogenesis. Compared to the usual approach where thermal masses are inserted into the kinematics of final states, we find that deviations arise through two different leptonic dispersion relations. The decay rate differs from the usual approach by more than 1 order of magnitude in the temperature range which is interesting for the weak washout regime. We discuss how to arrive at consistent finite-temperature treatments of leptogenesis.

  5. Probing the Charm Quark Yukawa Coupling in Higgs+Charm Production.

    PubMed

    Brivio, Ilaria; Goertz, Florian; Isidori, Gino

    2015-11-20

    We propose a new method for determining the coupling of the Higgs boson to charm quarks, via Higgs production in association with a charm-tagged jet: pp→hc. As a first estimate, we find that at the LHC with 3000 fb^{-1}, it should be possible to derive a constraint of order one, relative to the standard model (SM) value of the charm Yukawa coupling. As a by-product of this analysis, we present an estimate of the exclusive pp→hD^{(*)} electroweak cross section. Within the SM, the latter turns out to be not accessible at the LHC even in the high-luminosity phase. PMID:26636844

  6. New properties of the renormalization group equations of the Yukawa couplings and the CKM matrix

    SciTech Connect

    Juarez, S. R.; Kielanowski, P.; Mora, G.

    1999-10-25

    We solve the one-loop Renormalization Group Equations (RGE) and show that each of the Quark Yukawa Couplings (QYC) matrices for the up and down quarks depends on two functions of energy. The energy dependence is such that the diagonalizing matrices of the up QYC and the ratio m{sub c}/m{sub u} are constant while for the down QYC the diagonalizing matrices are energy dependent. From this it follows that the evolution of the CKM matrix depends on energy through one known function.

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

    SciTech Connect

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

    2013-05-15

    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.

  8. Neutrino mass matrices from two zero 3 × 2 Yukawa textures and minimal d = 5 entries

    NASA Astrophysics Data System (ADS)

    Achelashvili, Avtandil; Tavartkiladze, Zurab

    2016-05-01

    Aiming to relate leptonic CP violating phase δ to the cosmological CP asymmetry, we study the extension of MSSM by two quasi-degenerate (strictly degenerate at tree level) right-handed neutrinos and consider all possible two texture zero 3 × 2 Yukawa matrices plus one ΔL = 2 dimension five (d = 5) operator contributing to the light neutrino mass matrix. We classify all experimentally viable mass matrices, leading to several predictions, and analytically derive predictive relations. We also relate the CP violating δ phase to the CP phase of the thermal leptogenesis.

  9. Schwinger-Dyson approach for a Lifshitz-type Yukawa model

    SciTech Connect

    Alexandre, J.; Farakos, K.; Pasipoularides, P.; Tsapalis, A.

    2010-02-15

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

  10. The influence of the mean charge state on the Coulomb heating of fast diclusters through the Si<1 1 1> direction

    NASA Astrophysics Data System (ADS)

    Nascimento, C. D.; Fadanelli, R. C.; Behar, M.

    2016-04-01

    In the present work, we report a theoretical and experimental study of the Coulomb heating of H2+ and C2+ in Si<1 1 1> channel, covering an energy range from 200 keV/ion to 2200 keV/ion. The experimental values for Coulomb heating were obtained by combining the Rutherford backscattering spectrometry (RBS) and the particle induced X-ray emission (PIXE) techniques under channeling conditions. Theoretical values were obtained by performing classical trajectory Monte-Carlo (CTMC) simulations of the ion paths inside the <1 1 1> Si channel, using Dirac-Hartree-Fock-Slater (DHFS) results for the interionic potential. As seen for the <1 1 0> case, it is shown that the use of a DHFS potential based on the ion mean charge states in amorphous targets leads to a disagreement between the Coulomb heating values and the expected potential energies stored in the dicluster prior to the Coulomb explosion. Therefore, a numerical procedure was used in order to calculate the mean charge state values for ions traveling in Si<1 1 1>. The use of the resulting charge states led to a linear relationship between the Coulomb heating values and the stored potential energy per ion of the diclusters. Finally, the Coulomb heating/stored potential energy ratio amounts to about 2/3, as expected from an isotropic Coulomb explosion.

  11. Equation of state for magnetized Coulomb plasmas

    NASA Astrophysics Data System (ADS)

    Potekhin, A. Y.; Chabrier, G.

    2013-02-01

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

  12. Radiative symmetry breaking, fermion masses and mixing angles, and large Yukawa couplings in N - 1 SUSY-GUTS

    SciTech Connect

    Anderson, G.W.

    1992-12-01

    The effect of large third generation Yukawa couplings on radiative electroweak symmetry breaking in N = 1 SUSY-GUTS is reported. Limits on tan {beta}, and on the amount of fine tuning necessary for consistent symmetry breaking in the MSSM are derived. Predictions for fermion masses and mixing angles from GUT scale textures are also discussed. The effect of large Yukawa couplings on the running of the DHR texture is used to determine limits on the top quark valid for all values of tan {beta}.

  13. Coulomb sum rule for {sup 4}He

    SciTech Connect

    J. Carlson; J. Jourdan; R. Schiavilla; I. Sick

    2002-10-01

    We determine the Coulomb sum for {sup 4}He using world data on {sup 4}He(e, e') and compare the results to calculations based on realistic interactions and including two-body components in the nuclear charge operator. We find good agreement between theory and experiment using free-nucleon form factors. The apparent reduction of the in-medium G{sub ep} implied by IA-interpretation of the L/T-ratios measured in {sup 4}He(e,e'p) and {sup 4}He([vec]e, e'p) is not confirmed.

  14. Coulomb Interactions of Colloidal Particles in Oil

    NASA Astrophysics Data System (ADS)

    Sainis, Sunil; Dufresne, Eric

    2007-03-01

    We study the electrostatic interactions of microspheres (PMMA-PHSA) in solutions of surfactant (NaAOT) in oil (hexadecane). We directly measure the forces between isolated pairs of particles to extract the particle charge and solvent ionic strength. Over a wide range of surfactant concentrations, the interparticle forces are indistinguishable from unscreened Coulomb interactions. Far above the critical micelle concentration, however, the interactions assume the familiar screened Debye-Huckel form. Long-ranged interactions between micron-sized particles provide a window to study the structure and dynamics of strongly-correlated systems.

  15. Multiple Coulomb scattering in thin silicon

    NASA Astrophysics Data System (ADS)

    Berger, N.; Buniatyan, A.; Eckert, P.; Förster, F.; Gredig, R.; Kovalenko, O.; Kiehn, M.; Philipp, R.; Schöning, A.; Wiedner, D.

    2014-07-01

    We present a measurement of multiple Coulomb scattering of 1 to 6 GeV/c electrons in thin (50-140 μm) silicon targets. The data were obtained with the EUDET telescope Aconite at DESY and are compared to parametrisations as used in the Geant4 software package. We find good agreement between data and simulation in the scattering distribution width but large deviations in the shape of the distribution. In order to achieve a better description of the shape, a new scattering model based on a Student's t distribution is developed and compared to the data.

  16. Quenching molecular photodissociation by intermolecular Coulombic decay

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    In this paper we study the impact of interatomic Coulombic decay (ICD) on molecular photodissociation. The investigation reveals the hitherto unrecognized ability of ICD to quench processes involving nuclear rearrangements. Numerical computations of the nuclear dynamics, initiated by photoexciting the B1Σ+ Rydberg state of CO in CO.Mg complexes, are carried out. The efficiencies of ICD and photoinduced predissociation are compared for the four lowest vibrational levels of the corresponding electronic state. We also show the impact of CO vibrations on the ICD electron spectrum. Finally, we discuss the growing efficiency of ICD to quench the dissociation as the number of neighboring Mg atoms is increased.

  17. Coulomb Repulsion in Miniature Ion Mobility Spectrometry

    SciTech Connect

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

    1999-08-08

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

  18. Perturbativity limits for scalar minimal dark matter with Yukawa interactions: Septuplet

    NASA Astrophysics Data System (ADS)

    Cai, Chengfeng; Huang, Ze-Min; Kang, Zhaofeng; Yu, Zhao-Huan; Zhang, Hong-Hao

    2015-12-01

    The candidate of minimal dark matter (MDM) is limited if one demands perturbativity up to a very high scale, and it was believed that the MDM model with a real scalar septuplet could keep perturbative up to the Planck or grand unified theory scale. In this work we point out that it is not true after taking into account the running of the quartic self-couplings of the scalar septuplet. For the septuplet mass around 10 TeV, which is suggested by the observed dark matter relic abundance, these couplings would hit the Landau pole at a scale 108- 109 GeV , much lower than the Planck scale. We attempt to push up the Landau pole scale as high as possible by proposing an extension with extra Yukawa interactions of the septuplet. We find that in principle the Landau pole could be deferred to a scale of 1014 GeV if one could tolerate a serious fine-tuning of the initial condition of the Yukawa coupling. Moreover, if the MDM particle mass could be relaxed to 108 GeV , which would need some nonthermal production mechanisms to give a correct relic abundance, the Landau pole scale could be pushed up above the Planck scale.

  19. Dynamical breakdown of Abelian gauge chiral symmetry by strong Yukawa interactions

    SciTech Connect

    Benes, Petr; Brauner, Tomas; Hosek, Jiri

    2007-03-01

    We consider a model with anomaly-free Abelian gauge axial-vector symmetry, which is intended to mimic the standard electroweak gauge chiral SU(2){sub L}xU(1){sub Y} theory. Within this model we demonstrate: (1) Strong Yukawa interactions between massless fermion fields and a massive scalar field carrying the axial charge generate dynamically the fermion and boson proper self-energies, which are ultraviolet-finite and chirally noninvariant. (2) Solutions of the underlying Schwinger-Dyson equations found numerically exhibit a huge amplification of the fermion mass ratios as a response to mild changes of the ratios of the Yukawa couplings. (3) The 'would-be' Nambu-Goldstone boson is a composite of both the fermion and scalar fields, and it gives rise to the mass of the axial-vector gauge boson. (4) Spontaneous breakdown of the gauge symmetry further manifests by mass splitting of the complex scalar and by new symmetry-breaking vertices, generated at one loop. In particular, we work out in detail the cubic vertex of the Abelian gauge boson.

  20. Is ``just-so'' Higgs splitting needed for t-b-τ Yukawa unified SUSY GUTs?

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Kraml, Sabine; Sekmen, Sezen

    2009-09-01

    Recent renormalization group calculations of the sparticle mass spectrum in the Minimal Supersymmetric Standard Model (MSSM) show that t-b-τ Yukawa coupling unification at MGUT is possible when the mass spectra follow the pattern of a radiatively induced inverted scalar mass hierarchy. The calculation is entirely consistent with expectations from SO(10) SUSY GUT theories, with one exception: it seems to require MSSM Higgs soft term mass splitting at MGUT, dubbed ``just-so Higgs splitting'' (HS) in the literature, which apparently violates the SO(10) gauge symmetry. Here, we investigate three alternative effects: i). SO(10) D-term splitting, ii). inclusion of right hand neutrino in the RG calculation, and iii). first/third generation scalar mass splitting. By combining all three effects (the DR3 model), we find t-b-τ Yukawa unification at MGUT can be achieved at the 2.5% level. In the DR3 case, we expect lighter (and possibly detectable) third generation and heavy Higgs scalars than in the model with HS. In addition, the light bottom squark in DR3 should be dominantly a right state, while in the HS model, it is dominantly a left state.

  1. SOSpin, a C++ library for Yukawa decomposition in SO(2 N) models

    NASA Astrophysics Data System (ADS)

    Cardoso, Nuno; Emmanuel-Costa, David; Gonçalves, Nuno; Simões, C.

    2016-06-01

    We present in this paper the SOSpin library, which calculates an analytic decomposition of the Yukawa interactions invariant under any SO(2N) group in terms of an SU(N) basis. We make use of the oscillator expansion formalism, where the SO(2N) spinor representations are expressed in terms of creation and annihilation operators of a Grassmann algebra. These noncommutative operators and their products are simulated in SOSpin through the implementation of doubly-linked-list data structures. These data structures were determinant to achieve a higher performance in the simplification of large products of creation and annihilation operators. We illustrate the use of our library with complete examples of how to decompose Yukawa terms invariant under SO(2N) in terms of SU(N) degrees of freedom for N=2 and 5. We further demonstrate, with an example for SO(4), that higher dimensional field-operator terms can also be processed with our library. Finally, we describe the functions available in SOSpin that are made to simplify the writing of spinors and their interactions specifically for SO(10) models.

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

    SciTech Connect

    Charan, Harish; Ganesh, Rajaraman Joy, Ashwin

    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 Γ, screening parameter κ, 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, θ) 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.

  3. On the temperature dependence of ballistic Coulomb drag in nanowires.

    PubMed

    Muradov, M I; Gurevich, V L

    2012-04-01

    We have investigated within Fermi liquid theory the dependence of Coulomb drag current in a passive quantum wire on the applied voltage V across an active wire and on the temperature T for any values of eV/k(B)T. We assume that the bottoms of the 1D minibands in both wires almost coincide with the Fermi level. We conclude that: (1) within a certain temperature interval the drag current can be a descending function of the temperature T; (2) the experimentally observed temperature dependence T(-0.77) of the drag current can be interpreted within the framework of Fermi liquid theory; (3) at relatively high applied voltages the drag current saturates as a function of the applied voltage; and (4) the screening of the electron potential by metallic gate electrodes can be of importance. PMID:22406816

  4. Coulomb problem for graphene with the gapped electron spectrum

    NASA Astrophysics Data System (ADS)

    Kuleshov, V. M.; Mur, V. D.; Narozhny, N. B.; Fedotov, A. M.; Lozovik, Yu. E.

    2015-02-01

    The characteristics of charge carriers in graphene with dopants having charge Z and deposited onto a SiC substrate are analyzed. The closed set of explicit equations determining the spectrum of charge carriers are obtained for the case of the Coulomb potential modified at small distances. The critical values Z cr of the dopant charge at which the energy level with the given quantum numbers crosses the valence band boundary are determined. At Z < Z cr, for the lowest values of the orbital angular momentum, the position of the energy level corresponding to the bound state is obtained as a function of charge Z. For Z > Z cr, the position and width of the quasistationary state are calculated. The problem concerning the screening of the impurity charge is also considered.

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

    SciTech Connect

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

    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.

  6. Coulomb gauge confinement in the heavy quark limit

    SciTech Connect

    Popovici, C.; Watson, P.; Reinhardt, H.

    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.

  7. Non-commutative relativistic equation with a Coulomb potential

    SciTech Connect

    Zaim, Slimane; Khodja, Lamine; Delenda, Yazid

    2012-06-27

    We improve the previous study of the Klein-Gordon equation in a non-commutative space-time as applied to the Hydrogen atom to extract the energy levels, by considering the secondorder corrections in the non-commutativity parameter. Phenomenologically we show that noncommutativity plays the role of spin.

  8. Hyperspherical Coulomb spheroidal basis in the Coulomb three-body problem

    SciTech Connect

    Abramov, D. I.

    2013-02-15

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

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

    SciTech Connect

    Shiokawa, T.; Takada, Y.; Konabe, S.; Hatsugai, Y.; Muraguchi, M.; Endoh, T.; Shiraishi, K.

    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.

  10. Dynamic stresses, coulomb failure, and remote triggering: corrected

    USGS Publications Warehouse

    Hill, David P.

    2012-01-01

    Dynamic stresses associated with crustal surface waves with 15–30 s periods and peak amplitudes <1  MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid‐onset triggered seismicity that develop during the surface‐wave peak dynamic stressing. Evaluation of the triggering potential of surface‐wave dynamic stresses acting on critically stressed faults using a Mohr’s circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves for most fault orientations and wave incidence angles. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earlier arriving Love wave, and (2) Love‐wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid‐onset dynamic triggering may not reside solely with a simple static‐threshold friction mode. The results also indicate that normal faults should be more susceptible to dynamic triggering by 20‐s Rayleigh‐wave stresses than thrust faults in the shallow seismogenic crust (<10  km) while the advantage tips in favor of reverse faults greater depths. This transition depth scales with wavelength and coincides roughly with the transition from retrograde‐to‐prograde particle motion. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems. The result is consistent with the apparent elevated susceptibility of extensional or transtensional tectonic regimes to remote triggering by Rayleigh‐wave dynamic stresses than compressional or transpressional regimes.

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

    SciTech Connect

    Campagnari, Davide R.; Reinhardt, Hugo; Weber, Axel

    2009-07-15

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

  12. Confining solution of the Dyson-Schwinger equations in Coulomb gauge

    SciTech Connect

    Epple, D.; Reinhardt, H.; Schleifenbaum, W.

    2007-02-15

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

  13. Phase diagram of a quantum Coulomb wire

    NASA Astrophysics Data System (ADS)

    Ferr, G.; Astrakharchik, G. E.; Boronat, J.

    2015-12-01

    We report the quantum phase diagram of a one-dimensional Coulomb wire obtained using the path-integral Monte Carlo method. The exact knowledge of the nodal points of this system permits us to find the energy in an exact way, solving the sign problem which spoils fermionic calculations in higher dimensions. The results obtained allow for the determination of the stability domain, in terms of density and temperature, of the one-dimensional Wigner crystal. At low temperatures, the quantum wire reaches the quantum-degenerate regime, which is also described by the diffusion Monte Carlo method. Increasing the temperature, the system transforms to a classical Boltzmann gas, which we simulate using classical Monte Carlo. At large enough density, we identify a one-dimensional ideal Fermi gas which remains quantum up to higher temperatures than in two- and three-dimensional electron gases. The obtained phase diagram and the energetic and structural properties of this system are relevant to experiments with electrons in quantum wires and to Coulomb ions in one-dimensional confinement.

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

    SciTech Connect

    Santra, S.; Kailas, S.; Ramachandran, K.; Parkar, V. V.; Jha, V.; Roy, B. J.; Shukla, P.

    2011-03-15

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

  15. Evaluation of negative energy Coulomb (Whittaker) functions

    NASA Astrophysics Data System (ADS)

    Noble, C. J.

    2004-05-01

    This paper describes a code for evaluating exponentially decaying negative energy Coulomb functions and their first derivatives with respect to the radial variable. The functions, which correspond to Whittaker functions of the second kind, are obtained to high accuracy for a wide range of parameters using recurrence techniques. Program summaryTitle of program: whittaker_w Catalog identifier: ADSZ Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSZ Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Cray T3E, Sun Ultra-5_10 sparc, Origin2000, Compaq EV67, IBM SP3, Toshiba 460CDT Operating systems under which the program has been tested: Windows NT4, Redhat Linux, SunOS 5.8 Programming language used: Fortran 95 Memory required to run with typical data: 500 KB Number of bytes in distributed program, including test data, etc.: 39728 Number of lines in distributed program, including test data, etc.: 2900 Distribution format: tar gzip file Nature of physical problem: The closed-channel components of the asymptotic radial wave function corresponding to electron or positron scattering by atomic or molecular ions may be expressed in terms of negative energy Coulomb functions. The scattering observables are obtained from S or T matrices which in turn are obtained by matching the radial and asymptotic wavefunctions at a finite radial point. Recent large scale scattering calculations have required accurate values of the Coulomb functions at smaller ρ values and larger negative η values than previous work. The present program is designed to extend the range of parameters for which the function may be calculated. Method of solution: Recurrence relations, power series expansion, numerical quadrature. Restrictions on the complexity of the problem: The program has been tested for the parameter ranges: 0< ρ⩽1000, | η|⩽120 and 0⩽ l⩽100. These ranges may, with appropriate scaling to avoid underflow and overflow, be extended. References: A. Sunderland, C.J. Noble, P.G. Burke, V.M. Burke, Comp. Phys. Commun. 145 (2002) 311.

  16. Known-to-Unknown Approach to Teach about Coulomb's Law

    ERIC Educational Resources Information Center

    Thamburaj, P. K.

    2007-01-01

    Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to

  17. 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.

  18. Known-to-Unknown Approach to Teach about Coulomb's Law

    ERIC Educational Resources Information Center

    Thamburaj, P. K.

    2007-01-01

    Analogies from life experiences help students understand various relationships presented in an introductory chemistry course. Coulomb's law is a complex relationship encountered in introductory general chemistry. A proper understanding of the relationships between the quantities involved in Coulomb's law is necessary in order for students to…

  19. Study on Coulomb explosions of ion mixtures

    NASA Astrophysics Data System (ADS)

    Boella, E.; Peiretti Paradisi, B.; D'Angola, A.; Silva, L. O.; Coppa, G.

    2016-01-01

    > The paper presents a theoretical work on the dynamics of Coulomb explosion for spherical nanoplasmas composed by two different ion species. Particular attention has been dedicated to study the energy spectra of the ions with the larger charge-to-mass ratio. The connection between the formation of shock shells and the energy spread of the ions has been the object of a detailed analysis, showing that under particular conditions the width of the asymptotic energy spectrum tends to become very narrow, which leads to a multi-valued ion phase space. The conditions to generate a quasi-monoenergetic ion spectrum have been rigorously demonstrated and verified by numerical simulations using a technique that, exploiting the spherical symmetry of the problem, allows one to obtain very accurate and precise results.

  20. Tabletop nucleosynthesis driven by cluster Coulomb explosion.

    PubMed

    Last, Isidore; Jortner, Joshua

    2006-10-27

    Coulomb explosion of completely ionized (CH4)n, (NH3)n, and (H2O)n clusters will drive tabletop nuclear reactions of protons with 12C6+, 14N7+, and 16O8+ nuclei, extending the realm of nuclear reactions driven by ultraintense laser-heterocluster interaction. The realization for nucleosynthesis in exploding cluster beams requires complete electron stripping from the clusters (at laser intensities I(M) > or = 10(19) W cm(-2)), the utilization of nanodroplets of radius 300-700 A for vertical ionization, and the attainment of the highest energies for the nuclei (i.e., approximately 30 MeV for heavy nuclei and approximately 3 MeV for protons). PMID:17155473

  1. 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.

  2. The ghost propagator in Coulomb gauge

    SciTech Connect

    Watson, P.; Reinhardt, H.

    2011-05-23

    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.

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

    NASA Astrophysics Data System (ADS)

    Summy, Heaya Ann

    2010-02-01

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

  4. Probing the Charm Quark Yukawa Coupling in Higgs+Charm Production

    NASA Astrophysics Data System (ADS)

    Brivio, Ilaria; Goertz, Florian; Isidori, Gino

    2015-11-01

    We propose a new method for determining the coupling of the Higgs boson to charm quarks, via Higgs production in association with a charm-tagged jet: p p →h c . As a first estimate, we find that at the LHC with 3000 fb-1 , it should be possible to derive a constraint of order one, relative to the standard model (SM) value of the charm Yukawa coupling. As a by-product of this analysis, we present an estimate of the exclusive p p →h D(*) electroweak cross section. Within the SM, the latter turns out to be not accessible at the LHC even in the high-luminosity phase.

  5. Enhanced auxeticity in Yukawa systems due to introduction of nanochannels in [001]-direction

    NASA Astrophysics Data System (ADS)

    Tretiakov, Konstantin V.; Pigłowski, Paweł M.; Hyżorek, Krzysztof; Wojciechowski, Krzysztof W.

    2016-05-01

    A new approach to search for materials with auxetic properties by modifying structures of solids at molecular level has been proposed. The analysis of elastic properties of the face-centered cubic Yukawa crystals with very narrow nanochannels in the [001] crystallographic direction using Monte Carlo simulations in the isothermal–isobaric ensemble has been done. An influence of the size of nanochannels on the value of Poisson’s ratio in main crystallographic directions has been studied. It has been shown that the insertion of nanochannels in the system causes a decrease of the Poisson’s ratio in the direction [110][1\\bar{1}0] from –0.15(2) to –0.29(3). That means an amplification of auxetity in the studied system twice as compared to the system without nanochannels.

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

    SciTech Connect

    Ann Summy, Heaya

    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.

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

    SciTech Connect

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

    2015-05-21

    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.

  8. A Dream of Yukawa — Non-Local Fields out of Non-Commutative Spacetime —

    NASA Astrophysics Data System (ADS)

    Naka, Shigefumi; Toyoda, Haruki; Takanashi, Takahiro; Umezawa, Eizo

    The coordinates of κ-Minkowski spacetime form Lie algebraic elements, in which time and space coordinates do not commute in spite of that space coordinates commute each other. The non-commutativity is realized by a Planck-length-scale constant κ - 1( ne 0), which is a universal constant other than the light velocity under the κ-Poincare transformation. Such a non-commutative structure can be realized by SO(1,4) generators in dS4 spacetime. In this work, we try to construct a κ-Minkowski like spacetime with commutative 4-dimensional spacetime based on Adsn+1 spacetime. Another aim of this work is to study invariant wave equations in this spacetime from the viewpoint of non-local field theory by H. Yukawa, who expected to realize elementary particle theories without divergence according to this viewpoint.

  9. Hexatic phase in two-dimensional Yukawa systems: Existence and properties

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    In present work, phase transitions in strongly-coupled two-dimensional dissipative Yukawa systems are studied. The thermodynamic characteristics of these systems are calculated, namely the internal energy, the specific heat and the entropy. The considered characteristics have two singular points; 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 dependence of the position of the melting lines and the range of existence of the hexatic phase on the concentration of the grains in the considered system is studied. The special attention is paid to the comparison of our results to the existing numerical and analytical data.

  10. Self-Consistent Monte Carlo Study of the Coulomb Interaction under Nano-Scale Device Structures

    NASA Astrophysics Data System (ADS)

    Sano, Nobuyuki

    2011-03-01

    It has been pointed that the Coulomb interaction between the electrons is expected to be of crucial importance to predict reliable device characteristics. In particular, the device performance is greatly degraded due to the plasmon excitation represented by dynamical potential fluctuations in high-doped source and drain regions by the channel electrons. We employ the self-consistent 3D Monte Carlo (MC) simulations, which could reproduce both the correct mobility under various electron concentrations and the collective plasma waves, to study the physical impact of dynamical potential fluctuations on device performance under the Double-gate MOSFETs. The average force experienced by an electron due to the Coulomb interaction inside the device is evaluated by performing the self-consistent MC simulations and the fixed-potential MC simulations without the Coulomb interaction. Also, the band-tailing associated with the local potential fluctuations in high-doped source region is quantitatively evaluated and it is found that the band-tailing becomes strongly dependent of position in real space even inside the uniform source region. This work was partially supported by Grants-in-Aid for Scientific Research B (No. 2160160) from the Ministry of Education, Culture, Sports, Science and Technology in Japan.

  11. Backward scattering of low-energy antiprotons by highly charged and neutral uranium: Coulomb glory

    SciTech Connect

    Maiorova, A. V.; Telnov, D. A.; Shabaev, V. M.; Tupitsyn, I. I.; Plunien, G.; Stoehlker, T.

    2007-09-15

    Collisions of antiprotons with He-, Ne-, Ni-like, bare, and neutral uranium are studied theoretically for scattering angles close to 180 deg. and antiproton energies in the interval from 100 eV to 10 keV. We investigate the Coulomb glory effect which is caused by a screening of the Coulomb potential of the nucleus and results in a prominent maximum of the differential cross section in the backward direction at some energies of the incident particle. We found that for larger numbers of electrons in the ion the effect becomes more pronounced and shifts to higher energies of the antiproton. On the other hand, a maximum of the differential cross section in the backward direction can also be found in the scattering of antiprotons on a bare uranium nucleus. The latter case can be regarded as a manifestation of the screening property of the vacuum-polarization potential in nonrelativistic collisions of heavy particles.

  12. Scattering and stopping of swift diatomic molecules under Coulomb explosion

    SciTech Connect

    Sigmund, P. . Dept. of Physics Argonne National Lab., IL )

    1991-01-01

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

  13. Characterizing intra-exciton Coulomb scattering in terahertz excitations

    SciTech Connect

    Zybell, S.; Eßer, F.; Helm, M.; Bhattacharyya, J.; Winnerl, S.; Schneider, H.; Schneebeli, L.; Böttge, C. N.; Kira, M.; Koch, S. W.; Andrews, A. M.; Strasser, G.

    2014-11-17

    An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay.

  14. Characterizing intra-exciton Coulomb scattering in terahertz excitations

    NASA Astrophysics Data System (ADS)

    Zybell, S.; Bhattacharyya, J.; Winnerl, S.; Eer, F.; Helm, M.; Schneider, H.; Schneebeli, L.; Bttge, C. N.; Kira, M.; Koch, S. W.; Andrews, A. M.; Strasser, G.

    2014-11-01

    An intense terahertz field is applied to excite semiconductor quantum wells yielding strong non-equilibrium exciton distributions. Even though the relaxation channels involve a complicated quantum kinetics of Coulomb and phonon effects, distinct relaxation signatures of Coulomb scattering are identified within time-resolved photoluminescence by comparing the experiment with a reduced model that contains all relevant microscopic processes. The analysis uncovers a unique time scale for the Coulomb scattering directly from experiments and reveals the influence of phonon relaxation as well as radiative decay.

  15. Quantifying the {sup 12}C+{sup 12}C sub-Coulomb fusion with the time-dependent wave-packet method

    SciTech Connect

    Diaz-Torres, Alexis; Wiescher, Michael

    2012-10-20

    This contribution provides a preliminary study of the {sup 12}C+{sup 12}C sub-Coulomb fusion reaction using the time-dependent wave-packet method within a nuclear molecular picture. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.

  16. 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.

  17. Accelerated Monte Carlo Methods for Coulomb Collisions

    NASA Astrophysics Data System (ADS)

    Rosin, Mark; Dimits, Andris; Ricketson, Lee; Caflisch, Russel; Cohen, Bruce

    2012-10-01

    As an alternative to binary-collision models for simulating Coulomb collisions in the Fokker-Planck limit, we present a new numerical higher-order-accurate time integration scheme for Langevin-equation-based collisions. A Taylor-series expansion of the stochastic differential equations is used to improve upon the standard Euler time integration. Additional Milstein terms arise in the time-discretization due to both the velocity dependence of the diffusion coefficients, and the aggregation of angular deflections. We introduce an accurate, easily computable direct sampling method for the multidimensional terms -- an approximation to the double integral over products of Gaussian random processes. Including these terms improves the strong convergence of the time integration of the particle trajectories from O(δt1/2) to O(δt). This is useful as a both a first step towards direct higher-order weak schemes (for computing average quantities), and as a key component in a ``multi-level'' scheme that returns a computationally efficient estimate of averaged quantities. The latter is maximally efficient, in the asymptotic sense, when used with Milstein terms, and therefore the optimal choice of multi-level scheme. We present results showing both the improved strong convergence of the new integration method, and the increased efficiency multi-level scheme.

  18. Accelerated Monte Carlo Methods for Coulomb Collisions

    NASA Astrophysics Data System (ADS)

    Rosin, Mark; Ricketson, Lee; Dimits, Andris; Caflisch, Russel; Cohen, Bruce

    2014-03-01

    We present a new highly efficient multi-level Monte Carlo (MLMC) simulation algorithm for Coulomb collisions in a plasma. The scheme, initially developed and used successfully for applications in financial mathematics, is applied here to kinetic plasmas for the first time. The method is based on a Langevin treatment of the Landau-Fokker-Planck equation and has a rich history derived from the works of Einstein and Chandrasekhar. The MLMC scheme successfully reduces the computational cost of achieving an RMS error ɛ in the numerical solution to collisional plasma problems from (ɛ-3) - for the standard state-of-the-art Langevin and binary collision algorithms - to a theoretically optimal (ɛ-2) scaling, when used in conjunction with an underlying Milstein discretization to the Langevin equation. In the test case presented here, the method accelerates simulations by factors of up to 100. We summarize the scheme, present some tricks for improving its efficiency yet further, and discuss the method's range of applicability. Work performed for US DOE by LLNL under contract DE-AC52- 07NA27344 and by UCLA under grant DE-FG02-05ER25710.

  19. Deep inelastic scattering near the Coulomb barrier

    SciTech Connect

    Gehring, J.; Back, B.; Chan, K.

    1995-08-01

    Deep inelastic scattering was recently observed in heavy ion reactions at incident energies near and below the Coulomb barrier. Traditional models of this process are based on frictional forces and are designed to predict the features of deep inelastic processes at energies above the barrier. They cannot be applied at energies below the barrier where the nuclear overlap is small and friction is negligible. The presence of deep inelastic scattering at these energies requires a different explanation. The first observation of deep inelastic scattering near the barrier was in the systems {sup 124,112}Sn + {sup 58,64}Ni by Wolfs et al. We previously extended these measurements to the system {sup 136}Xe + {sup 64}Ni and currently measured the system {sup 124}Xe + {sup 58}Ni. We obtained better statistics, better mass and energy resolution, and more complete angular coverage in the Xe + Ni measurements. The cross sections and angular distributions are similar in all of the Sn + Ni and Xe + Ni systems. The data are currently being analyzed and compared with new theoretical calculations. They will be part of the thesis of J. Gehring.

  20. Multilevel Monte Carlo simulation of Coulomb collisions

    SciTech Connect

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

    2014-10-01

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

  1. Coulomb excitation of {sup 73}Ga

    SciTech Connect

    Diriken, J.; Bree, N.; Cocolios, T. E.; Huyse, M.; Ivanov, O. V.; Patronis, N.; Pauwels, D.; Van Duppen, P.; Stefanescu, I.; Balabanski, D.; Blasi, N.; Lo Bianco, G.; Blazhev, A.; Eberth, J.; Jolie, J.; Reiter, P.; Warr, N.; Cederkaell, J.; Davinson, T.; Ekstroem, A.

    2010-12-15

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

  2. Probing the influence of the Coulomb field on atomic ionization by sculpted two-color laser fields

    NASA Astrophysics Data System (ADS)

    Xie, Xinhua; Roither, Stefan; Gräfe, Stefanie; Kartashov, Daniil; Persson, Emil; Lemell, Christoph; Zhang, Li; Schöffler, Markus S.; Baltuška, Andrius; Burgdörfer, Joachim; Kitzler, Markus

    2013-04-01

    Interpretation of electron or photon spectra obtained with strong laser pulses that may carry attosecond dynamical and Ångström structural information about atoms or molecules usually relies on variants of the strong-field approximation (SFA) within which the influence of the Coulomb potential on the electron trajectory is neglected. We employ two-color sculpted laser fields to experimentally tune and probe the influence of the Coulomb field on the strong-field-driven wavepacket as observed by two-dimensional electron and ion momentum spectra. By comparison of measured spectra with predictions of the three-dimensional time-dependent Schrödinger equation as well as the quasi-classical limit of the SFA, the strong-field classical trajectory model, we are able to trace back the influence of the Coulomb field to the timing of the wavepacket release with sub-cycle precision.

  3. Influence of Coulomb effects on the resolving power of multireflection mass-spectrometer systems

    NASA Astrophysics Data System (ADS)

    Skoblin, M. G.; Kopaev, I. A.; Greenfield, D. E.; Makarov, A. A.; Monastyrskiy, M. A.; Alimpiev, S. S.

    2015-12-01

    General theoretical approaches to the modelling of Coulomb effects in short ion bunches, developed previously by the authors, are applied in this paper to the calculation of multireflection mass-spectrometer systems. A separate module of the MASIM 3D applied software package is designed. An adaptive computational procedure for calculating the 'mirror potential' induced by an ion bunch on the surface of field-forming electrodes is proposed. The dynamics of ion bunches in a time-of-flight reflectron-type mass analyser is calculated and the limitations on the resolving power, caused by resonant Coulomb effects of self-bunching and coalescence in the groups of particles with close masses, are revealed on the basis of numerical experiments.

  4. Linear-scaling multipole-accelerated Gaussian and finite-element Coulomb method

    NASA Astrophysics Data System (ADS)

    Watson, Mark A.; Kurashige, Yuki; Nakajima, Takahito; Hirao, Kimihiko

    2008-02-01

    A linear-scaling implementation of the Gaussian and finite-element Coulomb (GFC) method is presented for the rapid computation of the electronic Coulomb potential. The current work utilizes the fast multipole method (FMM) for the evaluation of the Poisson equation boundary condition. The FMM affords significant savings for small- and medium-sized systems and overcomes the bottleneck in the GFC method for very large systems. Compared to an exact analytical treatment of the boundary, more than 100-fold speedups are observed for systems with more than 1000 basis functions without any significant loss of accuracy. We present CPU times to demonstrate the effectiveness of the linear-scaling GFC method for both one-dimensional polyalanine chains and the challenging case of three-dimensional diamond fragments.

  5. The effects of Coulomb interactions on the superconducting gaps in iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Leong, Zhidong; Phillips, Philip

    2015-03-01

    Recent ARPES measurements on Co-doped LiFeAs report a large and robust superconducting gap on a band below the chemical potential. We will show that, unlike a conventional BCS theory, a multiband system with strong interband Coulomb interactions can explain the observations. We use a two-band model consisting of a superconducting electron band and a hole band that is below the chemical potential. The two bands are coupled via interband Coulomb interactions. Using Eliashberg theory, we found that superconductivity in the electron band induces a large superconducting gap in the hole band. Furthermore, the repulsive nature of the Coulomb interactions gives the induced gap an opposite sign, corresponding to an s+/- gap symmetry. Unlike other families of iron pnictides, the gap symmetry of LiFeAs has not been ascertained experimentally. The implications for the superconducting mechanism in iron pnictides will be discussed. Z. Leong is supported by a scholarship from the Agency of Science, Technology and Research. P. Phillips is supported by the Center for Emergent Superconductivity, a DOE Energy Frontier Research Center, Grant No. DE-AC0298CH1088.

  6. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures

    NASA Astrophysics Data System (ADS)

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-05-01

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)—a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.

  7. Coulomb excitation of radioactive nuclear beams in inverse kinematics

    SciTech Connect

    Zamfir, N.V. |||; Barton, C.J.; Brenner, D.S.; Casten, R.F. |; Gill, R.L.; Zilges, A. |

    1996-12-31

    Techniques for the measurement of B (E2:0{sub 1}{sup +} {r_arrow} 2{sub 1}{sup +}) values by Coulomb excitation of Radioactive Nuclear Beams in inverse kinematics are described. Using a thin, low Z target, the Coulomb excited beam nuclei will decay in flight downstream of the target. For long lifetimes (nanosecond range) these nuclei decay centimeters downstream of the target and for shorter lifetimes (picoseconds or less) they decay near the target. Corresponding to these two lifetime regimes two methods have been developed to measure {gamma} rays from the Coulomb excited nuclei: the lifetime method in which the lifetime of the excited state is deduced from the decay curve and the integral method in which the B(E2) value is extracted from the measured total Coulomb excitation cross section.

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

    SciTech Connect

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

    1993-08-01

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

  9. Indirect Coulomb energy for two-dimensional atoms

    SciTech Connect

    Benguria, Rafael D.; Tusek, Matej

    2012-09-15

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

  10. Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots.

    PubMed

    Ardelt, P-L; Gawarecki, K; Müller, K; Waeber, A M; Bechtold, A; Oberhofer, K; Daniels, J M; Klotz, F; Bichler, M; Kuhn, T; Krenner, H J; Machnikowski, P; Finley, J J

    2016-02-19

    We report Coulomb mediated hybridization of excitonic states in optically active InGaAs quantum dot molecules. By probing the optical response of an individual quantum dot molecule as a function of the static electric field applied along the molecular axis, we observe unexpected avoided level crossings that do not arise from the dominant single-particle tunnel coupling. We identify a new few-particle coupling mechanism stemming from Coulomb interactions between different neutral exciton states. Such Coulomb resonances hybridize the exciton wave function over four different electron and hole single-particle orbitals. Comparisons of experimental observations with microscopic eight-band k·p calculations taking into account a realistic quantum dot geometry show good agreement and reveal that the Coulomb resonances arise from broken symmetry in the artificial semiconductor molecule. PMID:26943557

  11. Coulomb Mediated Hybridization of Excitons in Coupled Quantum Dots

    NASA Astrophysics Data System (ADS)

    Ardelt, P.-L.; Gawarecki, K.; Müller, K.; Waeber, A. M.; Bechtold, A.; Oberhofer, K.; Daniels, J. M.; Klotz, F.; Bichler, M.; Kuhn, T.; Krenner, H. J.; Machnikowski, P.; Finley, J. J.

    2016-02-01

    We report Coulomb mediated hybridization of excitonic states in optically active InGaAs quantum dot molecules. By probing the optical response of an individual quantum dot molecule as a function of the static electric field applied along the molecular axis, we observe unexpected avoided level crossings that do not arise from the dominant single-particle tunnel coupling. We identify a new few-particle coupling mechanism stemming from Coulomb interactions between different neutral exciton states. Such Coulomb resonances hybridize the exciton wave function over four different electron and hole single-particle orbitals. Comparisons of experimental observations with microscopic eight-band k .p calculations taking into account a realistic quantum dot geometry show good agreement and reveal that the Coulomb resonances arise from broken symmetry in the artificial semiconductor molecule.

  12. Inelastic Scattering Form Factors

    Energy Science and Technology Software Center (ESTSC)

    1992-01-01

    ATHENA-IV computes form factors for inelastic scattering calculations, using single-particle wave functions that are eigenstates of motion in either a Woods-Saxon potential well or a harmonic oscillator well. Two-body forces of Gauss, Coulomb, Yukawa, and a sum of cut-off Yukawa radial dependences are available.

  13. 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

  14. A New Hybrid STEP/Coulomb model for Aftershock Forecasting

    NASA Astrophysics Data System (ADS)

    Steacy, S.; Jimenez, A.; Gerstenberger, M.

    2014-12-01

    Aftershock forecasting models tend to fall into two classes - purely statistical approaches based on clustering, b-value, and the Omori-Utsu law; and Coulomb rate-state models which relate the forecast increase in rate to the magnitude of the Coulomb stress change. Recently, hybrid models combining physical and statistical forecasts have begun to be developed, for example by Bach and Hainzl (2012) and Steacy et al. (2013). The latter approach combined Coulomb stress patterns with the STEP (short-term earthquake probability) model by redistributing expected rate from areas with decreased stress to regions where the stress had increased. The chosen 'Coulomb Redistribution Parameter' (CRP) was 0.93, based on California earthquakes, which meant that 93% of the total rate was expected to occur where the stress had increased. The model was tested against the Canterbury sequence and the main result was that the new model performed at least as well as, and often better than, STEP when tested against retrospective data but that STEP was generally better in pseudo-prospective tests that involved data actually available within the first 10 days of each event of interest. The authors suggested that the major reason for this discrepancy was uncertainty in the slip models and, particularly, in the geometries of the faults involved in each complex major event. Here we develop a variant of the STEP/Coulomb model in which the CRP varies based on the percentage of aftershocks that occur in the positively stressed areas during the forecast learning period. We find that this variant significantly outperforms both STEP and the previous hybrid model in almost all cases, even when the input Coulomb model is quite poor. Our results suggest that this approach might be more useful than Coulomb rate-state when the underlying slip model is not well constrained due to the dependence of that method on the magnitude of the Coulomb stress change.

  15. Renormalization in Coulomb-gauge QCD within the Lagrangian formalism

    SciTech Connect

    Niegawa, A.

    2006-08-15

    We study renormalization of Coulomb-gauge QCD within the Lagrangian, second-order, formalism. We derive a Ward identity and the Zinn-Justin equation, and, with the help of the latter, we give a proof of algebraic renormalizability of the theory. Through diagrammatic analysis, we show that, in the strict Coulomb gauge, g{sup 2}D{sup 00} is invariant under renormalization. (D{sup 00} is the time-time component of the gluon propagator.)

  16. The Examination of the {sup 12}C + {sup 24}Mg Elastic Scattering around the Coulomb Barrier

    SciTech Connect

    Boztosun, I.; Dagdemir, Y.; Bayrak, O.

    2005-07-01

    The investigation of nuclear reactions near the Coulomb barrier poses a number of problematic issues which have remained unsolved for a long time: The out-of-phase problem between theoretical predictions and experimental data, the reproduction of the oscillatory structure near the Coulomb barrier, and the consistent description of angular distributions together with the excitation functions data are just some of these issues. To address and overcome them, we examine the elastic scattering of the {sup 12}C + {sup 24}Mg system within the framework of the optical model with two small potentials in addition to the nuclear potential. The experimental data have been analyzed in the laboratory system from 16.0 to 24.0 MeV and excellent agreement between theoretical results and the measured experimental data has been obtained by using this modified optical potential. We show that the presence of the two small additional potentials creates a deepening in the surface region of the nuclear potential, which is very effective for the interference of the internal and barrier waves. This work is important in showing the sensitivity of the cross section to the fine details of the optical potential. It is also argued that the two small additional potentials take into account the coupling effect like that of the coupled channels and as a result reduce the strength of the imaginary potential. In this context, the results of the optical model are compared with that of the coupled channels.

  17. 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.

  18. Dark Coulomb binding of heavy neutrinos of fourth family

    NASA Astrophysics Data System (ADS)

    Belotsky, K. M.; Esipova, E. A.; Khlopov, M. Yu.; Laletin, M. N.

    2015-11-01

    Direct dark matter searches put severe constraints on the weakly interacting massive particles (WIMPs). These constraints cause serious troubles for the model of stable neutrino of fourth generation with mass around 50GeV. Though the calculations of primordial abundance of these particles make them in the charge symmetric case a sparse subdominant component of the modern dark matter, their presence in the universe would exceed the current upper limits by several orders of the magnitude. However, if quarks and leptons of fourth generation possess their own Coulomb-like y-interaction, recombination of pairs of heavy neutrinos and antineutrinos and their annihilation in the neutrinium atoms can play important role in their cosmological evolution, reducing their modern abundance far below the experimental upper limits. The model of stable fourth generation assumes that the dominant part of dark matter is explained by excessive ? antiquarks, forming (???)?? charged clusters, bound with primordial helium in nuclear-interacting O-helium (OHe) dark atoms. The y charge conservation implies generation of the same excess of fourth generation neutrinos, potentially dangerous WIMP component of this scenario. We show that due to y-interaction recombination of fourth neutrinos with OHe hides these WIMPs from direct WIMP searches, leaving the negligible fraction of free neutrinos, what makes their existence compatible with the experimental constraints.

  19. Le probleme quantique bicomplexe du potentiel de Coulomb

    NASA Astrophysics Data System (ADS)

    Mathieu, Jeremie

    In this master's thesis, is gathered a great part of my work on bicomplex quantum mechanics. Bicomplex numbers are the second order multicomplex generalization of complex numbers. Equipped with the standard addition and multiplication, they form an algebraic structure called a commutative ring with unity and are one of many known generalizations of the real number system. It has been almost eighty years since it's been proposed to use an algebra of a superior dimension than the one of complex numbers to construct the mathematical formalism of quantum mechanics. However it's only been since less than a decade ago that the idea of using the bicomplex numbers to do so has been seriously considered. In that sense, the complete resolution of the quantum harmonic oscillator in a bicomplex Hilbert space was the first major achievement of this ambitious project. This thesis, by article style, is a continuation of this work of generalization. It presents, by an axiomatic approach, the complete differential solution of the bicomplex quantum Coulomb potential problem and half of its algebraic solution.

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    The thermodynamic perturbation theories, which are based on the power series of a coupling constant (λ-expansion), have been proposed for studying the structural and thermodynamic properties of a hard-core Yukawa (HCY) fluid: one (A1-approximation) is the perturbation theory based on the hard-sphere repulsion as a reference system. The other (A2-approximation) is the perturbation theory based on the reference system which incorporates both the repulsive and short-range attractive interactions. The first-order mean-spherical approximation (FMSA) provided by Tang and Lu [J. Chem. Phys. 99, 9828 (1993)], 10.1063/1.465465 has been employed for investigating the thermodynamic properties of a HCY fluid using the alternative method via the direct correlation function. The calculated results show that (i) the A1 and A2 approximations are in excellent agreements with previous computer simulation results in the literature and compare with the semi-empirical works of Shukla including the higher-order free energy terms, (ii) the A1 and A2 approximations are better than the FMSA and the mean-spherical approximation, (iii) the A2-approximation compares with the A1-approximation, even though the perturbation effect of an A2-approximation is much smaller than that of an A1-approximation, and that (iv) the FMSA study is particularly of advantage in providing the structure and thermodynamics in a simple and analytic manner.

  1. Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

    DOE PAGESBeta

    Aad, G.

    2015-04-21

    Results of a search for H → ττ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb–1 and 20.3 fb–1 at centre-of-mass energies of √s=7 TeV and √s=8 TeV respectively. All combinations of leptonic (τ → ℓνν¯ with ℓ = e, μ) and hadronic (τ → hadrons ν) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standardmore » deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalized to the Standard Model expectation, of μ = 1.43–0.37+0.43 is consistent with the predicted Yukawa coupling strength in the Standard Model.« less

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  3. Two-Boson Truncation of Pauli-Villars-RegulatedYukawa Theory

    SciTech Connect

    Brodsky, Stanley J.; Hiller, John R.; McCartor, Gary; ,

    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.

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

    SciTech Connect

    Gapinski, Jacek Patkowski, Adam; Nägele, Gerhard

    2014-09-28

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

  5. Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

    SciTech Connect

    Aad, G.

    2015-04-21

    Results of a search for H → ττ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb–1 and 20.3 fb–1 at centre-of-mass energies of √s=7 TeV and √s=8 TeV respectively. All combinations of leptonic (τ → ℓνν¯ with ℓ = e, μ) and hadronic (τ → hadrons ν) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standard deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalized to the Standard Model expectation, of μ = 1.43–0.37+0.43 is consistent with the predicted Yukawa coupling strength in the Standard Model.

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

    SciTech Connect

    Avrigeanu, V.; Avrigeanu, M.

    2011-01-15

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

  7. Coulomb explosions and stopping of molecular ions channeled through carbon nanotubes

    SciTech Connect

    Zhou Dapeng; Song Yuanhong; Wang Younian; Miskovic, Z. L.

    2006-03-15

    We study Coulomb explosions of fast H{sub 2}{sup +} molecules under the channeling conditions through a single-wall carbon nanotube by solving the classical equations of motion for the fragment ions, involving both the repulsive continuum potential of the nanotube wall and the dynamically screened Coulomb repulsion between the two ions. Dynamic polarization of the nanotube electrons, described by a two-dimensional hydrodynamic model, gives rise to the correlated energy losses, a wakelike interaction between the fragment ions, as well as the dynamical image force on each ion. The explosion dynamics is dominated by the bare Coulomb repulsion and it mostly proceeds in the longitudinal direction, accompanied with the radially constrained oscillations of the fragment ions. Strong vicinage effects are found in both the molecule self-energy and its stopping power in the early stages of explosions, but they quickly diminish with the increasing dwell time in a manner which depends on the impact molecule speed and its axis orientation.

  8. Simple interpretation of nuclear orientation for Coulomb barrier distributions derived from a realistic effective interaction

    SciTech Connect

    Ismail, M.; Seif, W. M.

    2010-03-15

    A simple straightforward method has been presented to predict the dependence of barrier distributions at arbitrary orientations on different deformations. The proposed interpretation is developed independently of the complicated numerical calculations. It is related to the change of half-density radius of the deformed nucleus, in the direction of the separation vector. The microscopic calculations of Coulomb barrier are carried out by using a realistic density dependent nucleon-nucleon (NN) interaction, BDM3Y, for the interaction between spherical, {sup 48}Ca, and deformed, {sup 244}Pu, nuclei, as an example. To do so, the double-folding model for the interaction of spherical-deformed nuclei is put in a suitable computational form for the calculation of the potential at several separation distances and orientation angles using the density dependent NN force without consuming computational time. We found that the orientation distributions of the Coulomb barrier parameters show similar patterns to those of the interacting deformed nucleus radius. It is found that the orientation distribution of the Coulomb barrier radius follows the same variation of the deformed nucleus radius while the barrier height distribution follows it inversely. This correlation (anticorrelation) allows a simple evaluation of the orientation barrier distribution which would be very helpful to estimate when the barrier parameters will increase or decrease and at which orientations they will be independent of the deformation. This also allows us to estimate the compact and elongated configurations of the interacting nuclei which lead to hot and cold fusion, respectively.

  9. Simple interpretation of nuclear orientation for Coulomb barrier distributions derived from a realistic effective interaction

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Seif, W. M.

    2010-03-01

    A simple straightforward method has been presented to predict the dependence of barrier distributions at arbitrary orientations on different deformations. The proposed interpretation is developed independently of the complicated numerical calculations. It is related to the change of half-density radius of the deformed nucleus, in the direction of the separation vector. The microscopic calculations of Coulomb barrier are carried out by using a realistic density dependent nucleon-nucleon (NN) interaction, BDM3Y, for the interaction between spherical, Ca48, and deformed, Pu244, nuclei, as an example. To do so, the double-folding model for the interaction of spherical-deformed nuclei is put in a suitable computational form for the calculation of the potential at several separation distances and orientation angles using the density dependent NN force without consuming computational time. We found that the orientation distributions of the Coulomb barrier parameters show similar patterns to those of the interacting deformed nucleus radius. It is found that the orientation distribution of the Coulomb barrier radius follows the same variation of the deformed nucleus radius while the barrier height distribution follows it inversely. This correlation (anticorrelation) allows a simple evaluation of the orientation barrier distribution which would be very helpful to estimate when the barrier parameters will increase or decrease and at which orientations they will be independent of the deformation. This also allows us to estimate the compact and elongated configurations of the interacting nuclei which lead to hot and cold fusion, respectively.

  10. Propagation of Coulomb stress uncertainties in physics-based aftershock models

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  11. Cold chemistry with electronically excited Ca{sup +} Coulomb crystals

    SciTech Connect

    Gingell, Alexander D.; Bell, Martin T.; Oldham, James M.; Softley, Timothy P.; Harvey, Jeremy N.

    2010-11-21

    Rate constants for chemical reactions of laser-cooled Ca{sup +} ions and neutral polar molecules (CH{sub 3}F, CH{sub 2}F{sub 2}, or CH{sub 3}Cl) have been measured at low collision energies (/k{sub B}=5-243 K). Low kinetic energy ensembles of {sup 40}Ca{sup +} ions are prepared through Doppler laser cooling to form ''Coulomb crystals'' in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca{sup +} ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of {sup 40}Ca{sup +} involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state ({sup 2}S{sub 1/2}) and the combined excited states ({sup 2}D{sub 3/2} and {sup 2}P{sub 1/2}) of {sup 40}Ca{sup +}. These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

  12. On the solution of a "2D Coulomb + Aharonov-Bohm" problem: oscillator strengths in the discrete spectrum and scattering

    NASA Astrophysics Data System (ADS)

    Nguyen, H. T. T.; Meleshenko, P. A.; Dolgikh, A. V.; Klinskikh, A. F.

    2011-05-01

    In this paper we present an exact analytic solution of the Schrödinger equation both in the discrete and continuous spectra for the combination of a 2D Coulomb potential and the Aharonov-Bohm flux. We analyze the influence of the Aharonov-Bohm flux on the energy spectrum of such a system and show that its presence leads to the broadening of the electron density in the bound states with the given value of the principal quantum number. We have shown that the scattering phase shift, which determines the S-matrix, can be represented as a sum of the Aharonov-Bohm scattering phase, first obtained by Henneberger, and a "modified" 2D Coulomb phase. We have noticed, that the Aharonov-Bohm scattering phase has a full analogy with the "quantum defect" for such a system. We have shown also, that the presence of the Aharonov-Bohm flux affects the radiation spectrum of the electron in this case, and this fact is demonstrated by calculations of the corresponding oscillator strengths. The explicit analytic expression for the scattering cross section on such a system is found in the frame of the eikonal approach. Obtained formula contains the two exact limiting cases, namely, the "pure" 2D Coulomb scattering as well as the "pure" Aharonov-Bohm effect. The mutual influence of a 2D Coulomb potential and the Aharonov-Bohm flux is also discussed.

  13. Marine ice sheet profiles and stability under Coulomb basal conditions

    NASA Astrophysics Data System (ADS)

    Tsai, Victor; Stewart, Andrew; Thompson, Andrew

    2015-04-01

    The behavior of marine-terminating ice sheets, like the West Antarctic Ice Sheet, is of interest due to the possibility of rapid grounding line retreat and consequent catastrophic loss of ice. Critical to modeling this behavior is a choice of basal rheology, where the most popular approach is to relate the ice sheet velocity to a power-law function of basal stress. Recent experiments, however, suggest that near-grounding line tills exhibit Coulomb friction behavior. Here we address how Coulomb conditions modify ice sheet profiles and stability criteria. The basal rheology necessarily transitions to Coulomb friction near the grounding line due to low effective stresses, leading to changes in ice sheet properties within a narrow boundary layer. Ice sheet profiles 'taper off' towards a flatter upper surface, compared to the power-law case, and basal stresses vanish at the grounding line, consistent with observations. In the Coulomb case, the grounding line ice flux also depends more strongly on flotation ice thickness, which implies that ice sheets are more sensitive to climate perturbations. Furthermore, with Coulomb friction, the ice sheet grounds stably in shallower water than with a power-law rheology. This implies that smaller perturbations are required to push the grounding line into regions of negative bed slope, where it would become unstable. These results have important implications for ice sheet stability in a warming climate.

  14. Coulomb excitation studies of shape coexistence in atomic nuclei

    NASA Astrophysics Data System (ADS)

    Görgen, Andreas; Korten, Wolfram

    2016-02-01

    Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei and allows measuring electromagnetic moments that can be directly related to the nuclear shape. The availability of radioactive ion beams (RIBs) at energies near the Coulomb barrier has made it possible to study shape coexistence in a variety of short-lived exotic nuclei. This review presents a short overview of the methods related to multi-step Coulomb excitation experiments, followed by a discussion of several examples. The focus is on two mass regions where recent Coulomb excitation experiments have contributed to the quantitative understanding of shape coexistence: nuclei with mass A≈ 70 near the N = Z line and nuclei with A ≈ 100 near neutron number N = 60. Experimental results are summarized and their significance for understanding shape coexistence is discussed. Experimental observables such as quadrupole moments and electromagnetic transition strengths represent furthermore important benchmarks for advancing theoretical nuclear structure models. With several new RIB facilities planned and under construction, Coulomb excitation will remain to be an important tool to extend the studies of nuclear shapes toward more exotic systems, and to obtain a more comprehensive and quantitative understanding of shape coexistence.

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

    SciTech Connect

    Mahmoudi, F.

    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.

  16. Weak interaction rate Coulomb corrections in big bang nucleosynthesis

    SciTech Connect

    Smith, Christel J.; Fuller, George M.

    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.

  17. New Structures in 178HF and Coulomb Excitation of Isomers

    NASA Astrophysics Data System (ADS)

    Hayes, A. B.; Cline, D.; Wu, C. Y.; Hurst, A. M.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Lauritsen, T.; Seweryniak, D.; Zhu, S.; Karamian, S. A.; Walker, P. M.; Swan, T. P. D.; Rigby, S. V.; Cullen, D. M.; Lumley, N. M.; Mason, P.; Carroll, J. J.; Detwiler, B.; Harle, T.; Mills, I.; Trees, G.

    A 985 MeV 178Hf beam was Coulomb excited by a 208Pb target at the ATLAS accelerator of Argonne National Laboratory. Gammasphere and the CHICO particle detector recorded particle-γ coincidence data. The aim was to populate and determine the mechanism of previously observed Coulomb excitation of the Kπ = 6+ (t1/2 = 77 ns), 8- (4 s) and 16+ (31 y) isomer bands. New rotational bands were identified including an aligned band which appears to mix with the ground-state band (GSB) and the γ-vibrational band above ~ 12 ħ of angular momentum. Newly observed γ-decay transitions into the three isomer bands may elucidate the K-mixing which allows Coulomb excitation of these isomer bands, but direct decays from the GSB into the 16+ isomer band have not yet been confirmed.

  18. Long-range Coulomb interaction in nodal-ring semimetals

    NASA Astrophysics Data System (ADS)

    Huh, Yejin; Moon, Eun-Gook; Kim, Yong Baek

    2016-01-01

    Recently there have been several proposals of materials predicted to be nodal-ring semimetals, where zero energy excitations are characterized by a nodal ring in the momentum space. This class of materials falls between the Dirac-like semimetals and the more conventional Fermi-surface systems. As a step towards understanding this unconventional system, we explore the effects of the long-range Coulomb interaction. Due to the vanishing density of states at the Fermi level, Coulomb interaction is only partially screened and remains long-ranged. Through renormalization group and large-Nf computations, we have identified a nontrivial interacting fixed point. The screened Coulomb interaction at the interacting fixed point is an irrelevant perturbation, allowing controlled perturbative evaluations of physical properties of quasiparticles. We discuss unique experimental consequences of such quasiparticles: acoustic wave propagation, anisotropic dc conductivity, and renormalized phonon dispersion as well as energy dependence of quasiparticle lifetime.

  19. Thermodynamic functions of the hcp Coulomb crystal lattice

    NASA Astrophysics Data System (ADS)

    Kozhberov, A. A.; Baiko, D. A.

    2015-10-01

    One-component Coulomb crystals of ions with hexagonal close-packed (hcp) lattice likely form in the crust of strongly-magnetized neutron stars (magnetars). In this work we present a detailed study of vibration modes and thermodynamic properties of such crystals in a wide range of temperatures at zero magnetic field. In contrast to typically considered lattices, the phonon spectrum of the system exhibits a peculiar crossing of the acoustic modes near the Brillouin zone center in certain directions of the wavevector. It is demonstrated that in the field-free regime the Helmholtz free energy of the hcp Coulomb crystal is always higher than those of the Coulomb crystals with body-centered cubic and face-centered cubic lattices. The results of our numerical calculations are fitted by simple analytic expressions.

  20. Modified Coulomb-Dipole Theory for 2e Photoionization

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  1. Mechanical vibrations induced resonant breakdown of the Coulomb blockade

    SciTech Connect

    Pogosov, A. G.; Budantsev, M. V.; Shevyrin, A. A.; Plotnikov, A. E.; Bakarov, A. K.; Toropov, A. I.

    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.

  2. Coulomb breakup in a transformed harmonic oscillator basis

    SciTech Connect

    Moro, A.M.; Arias, J.M.; Gomez-Camacho, J.; Perez-Bernal, F.

    2006-04-15

    The problem of Coulomb breakup in the scattering of a two-body loosely bound projectile by a heavy target is addressed. A basis of transformed harmonic oscillator (THO) wave functions is used to discretize the projectile continuum and to diagonalize the Hamiltonian of the two-body system. Results for the reaction {sup 8}B+{sup 58}Ni at sub-Coulomb energies are presented. Comparison of different observables with those obtained with the standard continuum discretized coupled-channels (CDCC) method shows good agreement between both approaches.

  3. Femtosecond studies of Coulomb explosion utilizing covariance mapping

    NASA Astrophysics Data System (ADS)

    Card, Dennis Alan

    2000-10-01

    The studies presented herein elucidate details of the Coulomb explosion event initiated through the interaction of molecular clusters with an intense femtosecond laser beam (>=1 PW/cm2). Clusters studied include ammonia, titanium-hydrocarbon, pyridine, and 7-azaindole. Covariance analysis is presented as a general technique to study the dynamical processes in clusters and to discern whether the fragmentation channels are competitive. Positive covariance determinations identify concerted processes such as the concomitant explosion of protonated cluster ions of asymmetrical size. Anti- covariance mapping is exploited to distinguish competitive reaction channels such as the production of highly charged nitrogen atoms formed at the expense of the protonated members of a cluster ion ensemble. This technique is exemplified in each cluster system studied. Kinetic energy analyses, from experiment and simulation, are presented to fully understand the Coulomb explosion event. A cutoff study strongly suggests that a Coulomb explosion create ions with two different energies, a direct result of an incomplete Coulomb explosion. A peak analysis implies a strong mass-to-charge dependence on the KER. Taken together, the two studies suggest a duality in the elastic and inelastic contributions to the energy released in a Coulomb explosion. Finally, backward-ejected ions were found capable of arriving before the ion expelled without energy from a Coulomb explosion. Gradient, clustering, and microchannel plate studies confirm the chaotic nature of the Coulomb explosion and the effect clusters have on the event. Backward-ejected protons are found to impact the repeller and eject adsorbed protons from the surface. Moreover, delayed fragmentation is suggested by proton time-of-flights. A cluster study demonstrates the need for clusters at low intensities. Conceptually, the dynamic charge resonance enhanced ionization (CREI) model explains these results of heterocyclic Coulomb explosion. The nonvertical ionization model and the ionization ignition model cannot explain the results herein. The kinetic energy studies suggest that the ground state atomic distance is essential to achieve the amount of kinetic energy released, contrary to the nonvertical ionization model. The cluster study demonstrates that clusters are needed to gain multiply charged atoms at relatively low intensities; this conflicts directly with the supposition of the ionization ignition model.

  4. Lifetime Measurements and Coulomb Excitation of Light Hg Nuclei

    SciTech Connect

    Petts, A.; Butler, P. A.; Grahn, T.; Herzberg, R.-D.; Page, R. D.; Pakarinen, J.; Scheck, M.; Blazhev, A.; Bruyneel, B.; Dewald, A.; Eberth, J.; Fransen, C.; Jolie, J.; Melon, B.; Pascovici, G.; Pissulla, Th.; Reiter, P.; Warr, N.; Weisshaar, D.; Bree, N.

    2009-01-28

    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 Jyvaeskylae utilizing the Koeln plunger device in conjunction with the JUROGAM+RITU+GREAT setup. In addition, Coulomb excitation measurements of {sup 184,186,188}Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to I{sup {pi}} = 10{sup +} in {sup 182}Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.

  5. Convergence of Feynman integrals in Coulomb gauge QCD

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2014-12-15

    At 2-loop order, Feynman integrals in the Coulomb gauge are divergent over the internal energy variables. Nevertheless, it is known how to calculate the effective action, provided that the external gluon fields are all transverse. We show that, for the two-gluon Greens function as an example, the method can be extended to include longitudinal external fields. The longitudinal Greens functions appear in the BRST identities. As an intermediate step, we use a flow gauge, which interpolates between the Feynman and Coulomb gauges.

  6. Reconciling deformation parameters from fusion with those from Coulomb excitation

    SciTech Connect

    Leigh, J.R.; Rowley, N.; Lemmon, R.C.; Hinde, D.J.; Newton, J.O.; Wei, J.X.; Mein, J.C.; Morton, C.R.; Kuyucak, S.; Kruppa, A.T. Department of Theoretical Physics, Research School of Physical Sciences and Engineering, Australian National University, GPO Box 4, Canberra, ACT 2601 Science and Engineering Research Council, Daresbury Laboratory, Warrington WA44AD )

    1993-02-01

    The effects of deformation on sub-barrier fusion were first demonsrated almost fifteen years ago. Since that first analysis, it has become generally accepted that quadrupole deformation parameters deduced from fusion are significantly lower than those deduced from Coulomb excitation. Following a detailed analysis of the excitation function for [sup 154]Sm+[sup 16]O we find the excitation function is best fitted with deformation parameters which are consistent with Coulomb excitation data when a sufficiently complete model is used. The shape of the deduced barrier distribution strongly favors the inclusion of a positive hexadecapole moment.

  7. On rate-state and Coulomb failure models

    USGS Publications Warehouse

    Gomberg, J.; Beeler, N.; Blanpied, M.

    2000-01-01

    We examine the predictions of Coulomb failure stress and rate-state frictional models. We study the change in failure time (clock advance) Δt due to stress step perturbations (i.e., coseismic static stress increases) added to "background" stressing at a constant rate (i.e., tectonic loading) at time t0. The predictability of Δt implies a predictable change in seismicity rate r(t)/r0, testable using earthquake catalogs, where r0 is the constant rate resulting from tectonic stressing. Models of r(t)/r0, consistent with general properties of aftershock sequences, must predict an Omori law seismicity decay rate, a sequence duration that is less than a few percent of the mainshock cycle time and a return directly to the background rate. A Coulomb model requires that a fault remains locked during loading, that failure occur instantaneously, and that Δt is independent of t0. These characteristics imply an instantaneous infinite seismicity rate increase of zero duration. Numerical calculations of r(t)/r0 for different state evolution laws show that aftershocks occur on faults extremely close to failure at the mainshock origin time, that these faults must be "Coulomb-like," and that the slip evolution law can be precluded. Real aftershock population characteristics also may constrain rate-state constitutive parameters; a may be lower than laboratory values, the stiffness may be high, and/or normal stress may be lower than lithostatic. We also compare Coulomb and rate-state models theoretically. Rate-state model fault behavior becomes more Coulomb-like as constitutive parameter a decreases relative to parameter b. This is because the slip initially decelerates, representing an initial healing of fault contacts. The deceleration is more pronounced for smaller a, more closely simulating a locked fault. Even when the rate-state Δt has Coulomb characteristics, its magnitude may differ by some constant dependent on b. In this case, a rate-state model behaves like a modified Coulomb failure model in which the failure stress threshold is lowered due to weakening, increasing the clock advance. The deviation from a non-Coulomb response also depends on the loading rate, elastic stiffness, initial conditions, and assumptions about how state evolves.

  8. Primary Thermometry in the Intermediate Coulomb Blockade Regime

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  9. Observation of intracluster Coulombic decay of Rydberg-like states triggered by intense near-infrared pulses

    NASA Astrophysics Data System (ADS)

    Schütte, Bernd; Arbeiter, Mathias; Fennel, Thomas; Jabbari, Ghazal; Gokhberg, Kirill; Kuleff, Alexander I.; Vrakking, Marc J. J.; Rouzée, Arnaud

    2015-05-01

    Interatomic Coulombic decay (ICD) describes a process, where an excited atom relaxes by transferring its energy to an atom in the environment that gets ionized. So far, ICD has been observed following XUV ionization or excitation of clusters. Here we present novel results of an intracluster Coulombic decay mechanism induced by intense NIR pulses and following Rydberg atom formation in the generated nanoplasma. When a highly-excited Rydberg atom relaxes to its ground state by transferring its excess energy to a weakly bound electron in the environment, electrons with kinetic energies close to the atomic ionization potential are emitted. We show evidence for such an intracluster Coulombic decay process that leaves clear signatures in the electron kinetic energy spectra. ICD is time-resolved in a pump-probe experiment, where a weak probe pulse depopulates the excited states, leading to a quenching of the ICD signal. We find a decay time of 87 ps, which is siginificantly longer than for previous ICD observations, where inner-shell holes were created by XUV pulses. Intracluster Coulombic decay is found to be a generic process that takes places in atomic and molecular clusters and at different wavelengths. It may play an important role in biological systems and in astronomical plasmas. Previous affiliation: Max-Born-Institut, Berlin, Germany.

  10. Extension of time-independent wave-operator methods to the calculation of the two-body Coulomb photoionization amplitude

    NASA Astrophysics Data System (ADS)

    Johnson, Bruce R.; Reinhardt, William P.; McCurdy, C. W.; Rescigno, T. N.

    1985-10-01

    A finite-basis method [B. R. Johnson and W. P. Reinhardt, Phys. Rev. A 28, 1930 (1983)] recently introduced for calculating bound-free transition amplitudes is extended here to apply to the Coulomb potential. This method is based upon the use of complex-coordinate techniques to calculate matrix elements of the time-independent wave operators of formal scattering theory, and avoids explicit enforcement of coordinate-space boundary conditions. Numerical experiments aiming at the calculation of the known hydrogenic ground-state photoionization amplitude have been made with use of different known forms of the two-body Coulomb wave operator. We have successfully reproduced the hydrogenic photoionization amplitude, but only within an accuracy and precision of about 1%. The most plausible explanation for these numerical difficulties is associated with the singular behavior of the ``iɛ'' limit in Coulomb scattering theory. In shorter-range problems, this limit is conveniently implemented by complex-coordinate techniques or complex-coordinate techniques in conjunction with Padé extrapolation. However, neither of these methods effectively implements the ɛ-->0 limit in the Coulomb case.

  11. A Laguerre expansion method for the field particle portion in the linearized Coulomb collision operator

    NASA Astrophysics Data System (ADS)

    Nishimura, Shin

    2015-12-01

    The spherical coordinates expressions of the Rosenbluth potentials are applied to the field particle portion in the linearized Coulomb collision operator. The Sonine (generalized Laguerre) polynomial expansion formulas for this operator allowing general field particles' velocity distributions are derived. An important application area of these formulas is the study of flows of thermalized particles in NBI-heated or burning plasmas since the energy space structure of the fast ions' slowing down velocity distribution cannot be expressed by usual orthogonal polynomial expansions, and since the Galilean invariant property and the momentum conservation of the collision must be distinguished there.

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

    PubMed

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

    2011-10-28

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

  13. Predicting Freezing for Some Repulsive Potentials

    SciTech Connect

    Khrapak, S. A.; Morfill, G. E.

    2009-12-18

    We propose a simple method to approximately predict the freezing (fluid-solid) phase transition in systems of particles interacting via purely repulsive potentials. The method is based on the striking universality of the freezing curve for the model Yukawa and inverse-power-law interactions. This method is applied to draw an exemplary phase diagram of complex plasmas. We suggest that it can also be used to locate freezing transition in other substances with similar properties of interaction.

  14. Constituent gluon content of the static quark-antiquark state in Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Greensite, J.; Olejník, Š.

    2009-06-01

    Motivated by the gluon-chain model of flux tube formation, we compute and diagonalize the transfer matrix in lattice SU(2) gauge theory for states containing heavy static quark-antiquark sources, with separations up to one Fermi. The elements of the transfer matrix are calculated by variational Monte Carlo methods, in a basis of states obtained by acting on the vacuum state with zero-, one-, and two-gluon operators in Coulomb gauge. The color Coulomb potential is obtained from the zero-gluon to zero-gluon element of the transfer matrix, and it is well known that while this potential is asymptotically linear, it has a slope which is 2 to 3 times larger than the standard asymptotic string tension. We show that the addition of one- and two-gluon states results in a potential which is still linear, but the disagreement with the standard asymptotic string tension is reduced to 38% for the variational states used in this study, at the largest value of β=4/g2=2.4 considered.

  15. Coulomb effects on edge scattering in elastic nuclear collisions

    SciTech Connect

    Silveira, R. da; Leclercq-Willain, Ch.

    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.

  16. Accurate Coulomb blockade thermometry up to 60 kelvin.

    PubMed

    Meschke, M; Kemppinen, A; Pekola, J P

    2016-03-28

    We demonstrate experimentally a precise realization of Coulomb blockade thermometry working at temperatures up to 60 K. Advances in nano-fabrication methods using electron beam lithography allow us to fabricate uniform arrays of sufficiently small tunnel junctions to guarantee an overall temperature reading precision of about 1%. PMID:26903107

  17. Interpolating the Coulomb phase of little string theory

    DOE PAGESBeta

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

    2015-12-03

    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 onmore » 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. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.« less

  18. Interpolating the Coulomb phase of little string theory

    SciTech Connect

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

    2015-12-03

    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. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.

  19. Magnetic control of Coulomb scattering and terahertz transitions among excitons

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, J.; Zybell, S.; Eer, F.; Helm, M.; Schneider, H.; Schneebeli, L.; Bttge, C. N.; Breddermann, B.; Kira, M.; Koch, S. W.; Andrews, A. M.; Strasser, G.

    2014-03-01

    Time-resolved terahertz quenching studies of the magnetoexcitonic photoluminescence from GaAs/AlGaAs quantum wells are performed. A microscopic theory is developed to analyze the experiments. Detailed experiment-theory comparisons reveal a remarkable magnetic-field controllability of the Coulomb and terahertz interactions in the excitonic system.

  20. Circular dichroism in classical Coulomb scattering involving bremsstrahlung

    SciTech Connect

    Krylovetsky, A.A.; Manakov, N.L.; Marmo, S.I.; Starace, Anthony F.

    2005-09-15

    Classical orbit derivations of the triply differential cross section for electron bremsstrahlung (BrS) in a Coulomb field are presented; the classical origin of the circular dichroism effect in the electron scattering angular distributions is established for both spontaneous and laser-stimulated BrS.

  1. Coulomb gas transitions in three-dimensional classical dimer models

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Gukelberger, Jan; Trebst, Simon; Alet, Fabien; Balents, Leon

    2009-07-01

    Close-packed, classical dimer models on three-dimensional, bipartite lattices harbor a Coulomb phase with power-law correlations at infinite temperature. Here, we discuss the nature of the thermal phase transition out of this Coulomb phase for a variety of dimer models which energetically favor crystalline dimer states with columnar ordering. For a family of these models, we find a direct thermal transition from the Coulomb phase to the dimer crystal. While some systems exhibit (strong) first-order transitions in correspondence with the Landau-Ginzburg-Wilson paradigm, we also find clear numerical evidence for continuous transitions. A second family of models undergoes two consecutive thermal transitions with an intermediate paramagnetic phase separating the Coulomb phase from the dimer crystal. We can describe all of these phase transitions in one unifying framework of candidate field theories with two complex Ginzburg-Landau fields coupled to a U(1) gauge field. We derive the symmetry-mandated Ginzburg-Landau actions in these field variables for the various dimer models and discuss implications for their respective phase transitions.

  2. Finiteness of the Coulomb gauge QCD perturbative effective action

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2015-05-15

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ–Lee term which was inserted into the Hamiltonian.

  3. Hamiltonian flow in Coulomb gauge Yang-Mills theory

    SciTech Connect

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

    2011-01-15

    We derive a new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge. The flow equations for the static gluon and ghost propagators are solved under the assumption of ghost dominance within different diagrammatic approximations. The results are compared to those obtained in the variational approach and the reliability of the approximations is discussed.

  4. Coulomb energy of uniformly charged spheroidal shell systems.

    PubMed

    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. PMID:25871108

  5. Coulomb Interactions in Hanbury Brown-Twiss Experiments with Electrons

    ERIC Educational Resources Information Center

    Shen, Kan

    2009-01-01

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

  6. Interpolating the Coulomb phase of little string theory

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  7. Coulomb crystallization in two-component quantum plasmas

    NASA Astrophysics Data System (ADS)

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

    2006-10-01

    Coulomb crystallization is a common phenomenon in trapped (non-neutral) plasmas. In a neutral plasma, however, it is hampered by recombination of electrons and ions. Known examples are ion Coulomb crystals in white dwarf and neutron stars. Here, we predict the conditions under which a Coulomb crystal of heavy particles (e.g. ions) can form in the presence of a degenerate delocalized background of light charges (e.g. electrons): the key requirement is the mass ratio has to exceed a critical value of about 80 [1]. This leads to the prediction of novel types of crystals e.g. in hydrogen and helium. Further, we predict that holes in semiconductors can spontaneously order into a regular lattice in materials with sufficiently flat valence bands. A unified phase diagram of Coulomb crystals in two-component systems is derived and verified by first-principe path-integral Monte Carlo simulations [1-3]. [1] M. Bonitz, V.S. Filinov, V.E. Fortov, P. Levashov, H. Fehske, Phys. Rev. Lett. 95, 235006 (2005), Phys. Rev. Focus, Dec 2005 [2] M. Bonitz, V.S. Filinov, V.E. Fortov, P. Levashov, H. Fehske, J. Phys. A: Math. Gen. 39, 4717 (2006) [3] M. Bonitz, V.S. Filinov, V.E. Fortov, P. Levashov, H. Fehske, Phys. Rev. E (2006)

  8. 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.

  9. 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).

  10. Towards Stronger Coulomb Coupling in an Ultracold Neutral Plasma

    NASA Astrophysics Data System (ADS)

    Lyon, Mary E.

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

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

    SciTech Connect

    Chang Yongbin; Shizgal, Bernie D.

    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.

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

    SciTech Connect

    Haouat, S.; Chetouani, L.

    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.

  13. Two-dimensional and three-dimensional Coulomb clusters in parabolic traps

    SciTech Connect

    D'yachkov, L. G. Myasnikov, M. I.; Petrov, O. F.; Hyde, T. W.; Kong, J.; Matthews, L.

    2014-09-15

    We consider the shell structure of Coulomb clusters in an axially symmetric parabolic trap exhibiting a confining potential U{sub c}(?,z)=(m?{sup 2}/2)(?{sup 2}+?z{sup 2}). Assuming an anisotropic parameter ??=?4 (corresponding to experiments employing a cusp magnetic trap under microgravity conditions), we have calculated cluster configurations for particle numbers N?=?3 to 30. We have shown that clusters with N???12 initially remain flat, transitioning to three-dimensional configurations as N increases. For N?=?8, we have calculated the configurations of minimal potential energy for all values of ? and found the points of configuration transitions. For N?=?13 and 23, we discuss the influence of both the shielding and anisotropic parameter on potential energy, cluster size, and shell structure.

  14. 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.

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

    SciTech Connect

    Ki, Dae-Han; Jung, Young-Dae

    2010-09-06

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

  16. Reconfiguration and Control of Non-Equal Mass Three-Craft Coulomb Formation

    NASA Astrophysics Data System (ADS)

    Ting, Wang; Guangqing, Xia; Nan, Zhao

    2016-03-01

    The paper studied reconfiguration of Coulomb formation from three-craft system to four-craft system. Assumed that three-craft Coulomb system already formed a triangle configuration, then, the fourth Coulomb craft is scheduled to join the existing system so as to form a new static configuration. New possible configurations such as quadrilateral in 2-dimension and tetrahedron in 3-dimension for four-craft Coulomb formation are discussed in the paper. The processing of reconfiguration will not change the original origin and triangle formation. Through the Particle Swarm Optimization (PSO) algorithm, the mass, the charge and the position of the fourth Coulomb craft can be calculated for these configurations.

  17. 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 (α) of the top-basement surface and the basal dip angle (β) of the crust-mantle interface. Preliminary results from this analysis show that the hyper-extended wedge aperture angle (α+β) 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.

  18. Coulomb chronometry to probe the decay mechanism of hot nuclei

    NASA Astrophysics Data System (ADS)

    Gruyer, D.; Frankland, J. D.; Bonnet, E.; Chbihi, A.; Ademard, G.; Boisjoli, M.; Borderie, B.; Bougault, R.; Galichet, E.; Gauthier, J.; Guinet, D.; Lautesse, P.; Le Neindre, N.; Legouée, E.; Lombardo, I.; Lopez, O.; Manduci, L.; Marini, P.; Mazurek, K.; Nadtochy, P. N.; Pârlog, M.; Rivet, M. F.; Roy, R.; Rosato, E.; Spadaccini, G.; Verde, G.; Vient, E.; Vigilante, M.; Wieleczko, J. P.; Indra Collaboration

    2015-12-01

    In 129Xe+natSn central collisions from 8 to 25 MeV/nucleon, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive breakups decreases with increasing bombarding energy, becoming quasisimultaneous above excitation energy E*=4.0 ±0.5 MeV /nucleon . This transition from sequential to simultaneous breakup was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.

  19. Stationary entanglement between two nanomechanical oscillators induced by Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Qin, Wu; Yin, Xiao; Zhi-Ming, Zhang

    2016-01-01

    We propose a scheme for entangling two nanomechanical oscillators by Coulomb interaction in an optomechanical system. We find that the steady-state entanglement of two charged nanomechanical oscillators can be obtained when the coupling between them is stronger than a critical value which relies on the detuning. Remarkably, the degree of entanglement can be controlled by the Coulomb interaction and the frequencies of the two charged oscillators. Project supported by the Major Research Plan of the National Natural Science Foundation of China (Grant No. 91121023), the National Natural Science Foundation of China (Grant Nos. 61378012, 60978009, and 11574092), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20124407110009), the National Basic Research Program of China (Grant Nos. 2011CBA00200 and 2013CB921804), and the Program for Changjiang Scholar and Innovative Research Team in University, China (Grant No. IRT1243).

  20. 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.

  1. Hadron diffractive scattering at ultrahigh energies and Coulomb interaction

    NASA Astrophysics Data System (ADS)

    Anisovich, V. V.; Nikonov, V. A.

    2016-03-01

    We study the interplay of hadronic and Coulomb interactions for pp scattering at LHC energies on the basis of the previous determination of the real part of the amplitude [V. V. Anisovich, V. A. Nikonov and J. Nyiri, Int. J. Mod. Phys. A 30, 1550188 (2015)]. The interference of hadron and Coulomb interactions is discussed in terms of the K-matrix function technique. Supposing the black disk mode for the asymptotic interaction of hadrons, we calculate interference effects for the energies right up to s = 106 TeV. It turns out that the real part of the amplitude is concentrated in the impact parameter space at the border of the black disk that results in a growth of interplay effects with the energy increase.

  2. Coulomb drag in graphene quantum Hall bilayer systems

    NASA Astrophysics Data System (ADS)

    Liu, Xiaomeng; Wang, Lei; Fong, Kin Chung; Gao, Yuanda; Maher, Patrick; Watanabe, Kenji; Taniguchi, Takashi; Hone, James; Dean, Cory; Kim, Philip

    2015-03-01

    Coulomb drag between electrons in closely spaced two-dimensional electron systems has provided an exciting avenue for research on quantum Hall bilayer systems. Employing dual-gated, encapsulated graphene double layers separated by a thin hBN dielectric, we investigate density tunable magneto and Hall drag in quantum Hall bilayer systems. Large variations of magneto-drag and Hall-drag are observed, which can be related to the Landau level (LL) filling status of both driving and drag layers. The measured drag resistivity tensor can be associated with the tensor product of the differential magneto-resistivity tensors of the drive and drag layers. The temperature and field dependence of magneto-drag can be described in terms of the phase space for Coulomb scattering between LLs in the drag and drive layers. In the strong interaction regime and ultra-low temperature, we observe the effect of symmetry broken integer quantum Hall States in magneto and Hall drag signals.

  3. Quantum criticality and stability of three-body Coulomb systems

    NASA Astrophysics Data System (ADS)

    Kais, Sabre; Shi, Qicun

    2000-12-01

    We present quantum phase transitions and critical phenomena of three-body Coulomb systems with charges (Q, q, Q) and masses (M, m, M). Full numerical results, using the finite-size scaling method, for an arbitrary mass ratio 0<=κ=(1+m/M)-1<=1 over the range 1<=λ=\\|Q/q\\|<=1.25, show that there exists a transition curve λc(κ) through which all systems undergo a first-order phase transition from stable to unstable. Particularly, λc(κ) has a minimum at κm=0.35, which leads to a new proposed classification of the three-body Coulomb systems: moleculelike systems, κ>κm, such as Ps- (κ=0.5) and atomlike systems, κ<κm, such as p¯p¯d (κ=0.33).

  4. 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.

  5. Coulomb explosion of simple metal clusters in intense laser fields

    SciTech Connect

    Belkacem, M.; Megi, F.; Reinhard, P.-G.; Zwicknagel, G.; Suraud, E.

    2006-05-15

    We present a molecular dynamics model giving a classical description of valence and core electrons in Na clusters irradiated by intense laser pulses. Both core electrons and valence electrons are treated at the same level as classical Coulomb interacting particles. A minimum of quantum information is embodied by giving to each electron a finite width adjusted to the energies and radii of the related atomic shells. This model provides a surprisingly stable cluster ground state and a fair description of optical linear response. We focus on electron emission under laser irradiation in the intermediate and high-intensity regime. With increasing laser intensity, we observe a clear threshold for core ionization at a critical intensity of 10{sup 16} W/cm{sup 2}. Excitation at the critical intensity produces a fragmentation of the cluster into single ions with an average charge state of +2 and a kinetic energy distribution, which clearly indicates a Coulomb explosion.

  6. Coulomb excitation of radioactive beams in inverse kinematics

    SciTech Connect

    Barton, C.J.; Gill, R.L.; Casten, R.F.

    1995-10-01

    The advent of Radioactive Nuclear Beam facilities will soon open new perspectives for nuclear structure studies. However, they will never provide the same wealth of data as stable beam facilities. Recent studies have shown that B(E2;0{sub 1}{sup +}2{sub 1}{sup +}) values have a high degree of sensitivity to structural features. We developed several techniques to obtain these values by low-energy Coulomb excitation of Radioactive Nuclear Beams in inverse kinematics on low Z targets. The methods are based on the measurement of the decay curve as the Coulomb excited nuclei decay in-flight. The apparatus will be described and recent results of test runs with stable beams will be presented.

  7. Simulation of Coulomb interaction effects in electron sources

    NASA Astrophysics Data System (ADS)

    Rouse, John; Zhu, Xieqing; Liu, Haoning; Munro, Eric

    2011-07-01

    Over many years, we have developed electron source simulation software that has been used widely in the electron optics community to aid the development of rotationally symmetric electron and ion guns. The simulation includes the modelling of cathode emission and the effects of volumetric space charge. In the present paper we describe the existing software and explain how we have extended this software to include the effects of discrete Coulomb interactions between the electrons as they travel from the cathode surface to the exit of the gun. In the paper, we will describe the numerical models we have employed, the techniques we have used to maximize the speed of the Coulomb force computation and present several illustrative examples of cases analyzed using the new software, including thermal field emitters, LaB 6 guns and flat dispenser-type cathodes.

  8. Logarithmic, Coulomb and Riesz Energy of Point Processes

    NASA Astrophysics Data System (ADS)

    Leblé, Thomas

    2016-02-01

    We define a notion of logarithmic, Coulomb and Riesz interactions in any dimension for random systems of infinite charged point configurations with a uniform background of opposite sign. We connect this interaction energy with the "renormalized energy" studied by Serfaty et al. which appears in the free energy functional governing the microscopic behavior of logarithmic, Coulomb and Riesz gases. Minimizers of this functional include the Sine-beta processes in the one-dimensional Log-gas case. Using our explicit expression (inspired by the work of Borodin-Serfaty) we prove their convergence to the Poisson process in the high-temperature limit as well as a crystallization result in the low-temperature limit for one-dimensional systems.

  9. Parity violating elastic electron scattering and Coulomb distortions

    SciTech Connect

    Horowitz, C.J.

    1998-06-01

    Parity violating elastic electron-nucleus scattering provides an accurate and model-independent measurement of neutron densities, because the Z{sup 0} couples primarily to neutrons. Coulomb distortion corrections to the parity violating asymmetry A{sub l} are calculated exactly using a relativistic optical model. Distortions significantly reduce A{sub 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 {sup 4}He, {sup 12}C, or {sup 16}O. {copyright} {ital 1998} {ital The American Physical Society}

  10. Elastic scattering of Beryllium isotopes near the Coulomb barrier

    SciTech Connect

    Di Pietro, A.; Figuera, P.; Amorini, F.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Randisi, G.; Rizzo, F.; Santonocito, D.; Scalia, G.; Scuderi, V.; Strano, E.; Torresi, D.; Papa, M.; Acosta, L.; Martel, I.; Perez-Bernal, F.; Borge, M. J. G.; Tengblad, O.

    2011-10-28

    In this contribution, results of experiments performed with the three Beryllium isotopes {sup 9,10,11}Be on a medium mass {sup 64}Zn target, at a center of mass energy of {approx_equal}1.4 the Coulomb barrier, will be discussed. Elastic scattering angular distributions have been measured for the {sup 9,10}Be reactions. In the {sup 11}Be case the quasielastic scattering angular distribution was obtained. In the halo nucleus case, the angular distribution exhibit a non-Fresnel-type pattern with a strong damping of the Coulomb-nuclear interference peak. Moreover, it is found that the total reaction cross-section for the halo nucleus induced collision is more than double the ones extracted in the collisions induced by the non-halo Beryllium isotopes. A large contribution to the total-reaction cross-section in the {sup 11}Be case could be attributed to transfer and/or break-up events.

  11. Glassy Dynamics in Geometrically Frustrated Coulomb Liquids without Disorder.

    PubMed

    Mahmoudian, Samiyeh; Rademaker, Louk; Ralko, Arnaud; Fratini, Simone; Dobrosavljević, Vladimir

    2015-07-10

    We show that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many low-lying metastable states with amorphous "stripe-glass" spatial structures. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of supercooled liquids above the glass transition. Our results show remarkable similarity with the recent observations of charge-glass behavior in ultraclean triangular organic materials of the θ-(BEDT-TTF)(2) family. PMID:26207481

  12. Coulomb Blockade Effect in a Nano-Sized Gold Chain

    NASA Astrophysics Data System (ADS)

    Hu, S. F.; Yeh, R. L.; Liu, R. S.

    Single electron transistors (SETs) has been proposed as a future basis for nanoelectric components. SETs, which utilize Coulomb blockade effect arising from the electrostatic charging energy of a single electron, are one of the promising candidates for future integrated circuits due to their extremely low power consumption and high-density integration. Here, we report on the study of the formation mechanism of a nanometer-scale Au chain on a patterned SiO2 based wafer by controlling the reaction of raw materials to form citrate Au sol and aminosilane/dithiol treated SiO2/Si wafer. Three gold colloidal particles (~15 nm) were aligned in a chain to form a one-dimensional current path which was bridged on a 80 nm gap between source and drain metal electrode. The SET device exhibited a Coulomb blockade effect at 40 K.

  13. Structural phase transitions and topological defects in ion Coulomb crystals

    SciTech Connect

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

    2014-11-19

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

  14. 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.

  15. Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene

    PubMed Central

    Mihnev, Momchil T.; Tolsma, John R.; Divin, Charles J.; Sun, Dong; Asgari, Reza; Polini, Marco; Berger, Claire; de Heer, Walt A.; MacDonald, Allan H.; Norris, Theodore B.

    2015-01-01

    In van der Waals bonded or rotationally disordered multilayer stacks of two-dimensional (2D) materials, the electronic states remain tightly confined within individual 2D layers. As a result, electron–phonon interactions occur primarily within layers and interlayer electrical conductivities are low. In addition, strong covalent in-plane intralayer bonding combined with weak van der Waals interlayer bonding results in weak phonon-mediated thermal coupling between the layers. We demonstrate here, however, that Coulomb interactions between electrons in different layers of multilayer epitaxial graphene provide an important mechanism for interlayer thermal transport, even though all electronic states are strongly confined within individual 2D layers. This effect is manifested in the relaxation dynamics of hot carriers in ultrafast time-resolved terahertz spectroscopy. We develop a theory of interlayer Coulomb coupling containing no free parameters that accounts for the experimentally observed trends in hot-carrier dynamics as temperature and the number of layers is varied. PMID:26399955

  16. Glassy Dynamics in Geometrically Frustrated Coulomb Liquids without Disorder

    NASA Astrophysics Data System (ADS)

    Mahmoudian, Samiyeh; Rademaker, Louk; Ralko, Arnaud; Fratini, Simone; Dobrosavljevi?, Vladimir

    2015-07-01

    We show that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many low-lying metastable states with amorphous "stripe-glass" spatial structures. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of supercooled liquids above the glass transition. Our results show remarkable similarity with the recent observations of charge-glass behavior in ultraclean triangular organic materials of the ? -(BEDT -TTF )2 family.

  17. Coulomb branch Hilbert series and three dimensional Sicilian theories

    NASA Astrophysics Data System (ADS)

    Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto

    2014-09-01

    We evaluate the Coulomb branch Hilbert series of mirrors of three dimensional Sicilian theories, which arise from compactifying the 6 d (2 , 0) theory with symmetry G on a circle times a Riemann surface with punctures. We obtain our result by gluing together the Hilbert series for building blocks T ρ ( G), where ρ is a certain partition related to the dual group of G, which we evaluated in a previous paper. The result is expressed in terms of a class of symmetric functions, the Hall-Littlewood polynomials. As expected from mirror symmetry, our results agree at genus zero with the superconformal index prediction for the Higgs branch Hilbert series of the Sicilian theories and extend it to higher genus. In the A 1 case at genus zero, we also evaluate the Coulomb branch Hilbert series of the Sicilian theory itself, showing that it only depends on the number of external legs.

  18. Calculating Charmonium Dissociation in a Coulomb Gauge QCD Quark Model

    SciTech Connect

    Szpigel, S.; Krein, G.; Marques de Carvalho, R.S.

    2004-12-02

    We describe the derivation of an effective Hamiltonian which involves explicit hadron degrees of freedom and consistently combines chiral symmetry and color confinement. We use a field theoretical method known as Fock-Tani (FT) representation and a microscopic relativistic quark model formulated in the context of Coulomb gauge QCD. Using this relativistic hadron Hamiltonian, we evaluate the dissociation cross section of J/{psi}-{rho} into D-mesons.

  19. Multiple Coulomb scattering and spatial resolution in proton radiography.

    PubMed

    Schneider, U; Pedroni, E

    1994-11-01

    A simple formula for the spatial resolution of transmission proton radiography is derived for two different methods of measuring the proton coordinates. The effect of multiple Coulomb scattering and energy loss are taken into account. Experimental measurements of the spatial resolution have been done and are compared with the calculations. The technique of measuring entrance and exit coordinates in coincidence for each single proton improves the spatial resolution by a factor of 8 compared to a single coordinate measurement. PMID:7891624

  20. 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.

  1. Aharonov-Bohm oscillations in the Coulomb blockade regime

    NASA Astrophysics Data System (ADS)

    Taylor, R. P.; Sachrajda, A. S.; Zawadzki, P.; Coleridge, P. T.; Adams, J. A.

    1992-09-01

    We discuss the electronic transmission through lateral dots, featuring both the Aharonov-Bohm-type oscillations observed in high magnetic field sweeps and Coulomb blockade oscillations detected as a function of electron density. We focus on the interplay of these two effects and demonstrate two intrinsic features of submicron dot behavior-the manifestation of the Aharonov-Bohn oscillations in a resonant reflection mode and a novel regime characterized by the simultaneous observation and a commensurate relationship of the two effects.

  2. Coulomb excitations for a short linear chain of metallic shells

    SciTech Connect

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

    2015-03-15

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

  3. Effect of the Long-Range Coulomb Interaction on the Phase Diagram of the Kohn-Luttinger Superconducting State in Idealized Graphene

    NASA Astrophysics Data System (ADS)

    Kagan, M. Yu.; Mitskan, V. A.; Korovushkin, M. M.

    2015-12-01

    The effect of the long-range Coulomb interaction on the formation of the Kohn-Luttinger superconductivity in monolayer doped graphene is studied disregarding the Van der Waals potential of the substrate and both magnetic and non-magnetic impurities. It is shown that the allowance for the Kohn-Luttinger renormalizations up to the second order in perturbation theory in the on-site Hubbard interaction inclusively, as well as in the intersite Coulomb interaction, significantly affects the interplay between the superconducting phases with the f-wave, p+ip -wave, and d + id -wave symmetries of the order parameter. It is demonstrated that taking Coulomb repulsion of electrons located at the next-nearest neighboring atoms in such a system into account changes qualitatively the phase diagram and enhances the critical temperature of the transition to the superconducting phase.

  4. Coulomb blockade phenomena observed in supported metallic nanoislands

    NASA Astrophysics Data System (ADS)

    Schneider, Wolf-Dieter

    2013-09-01

    The electron transport properties of single crystalline metallic nanostructures in the Coulomb blockade regime have been investigated by low-temperature scanning tunneling spectroscopy. To this end, nanoscale flat-top Pb islands with well-defined geometries are grown on NaCl-covered Ag(111) substrate. The tunneling spectra acquired at 4.6 K on the Pb nanoislands reflect the presence of single electron tunneling processes across the double-barrier tunnel junction (DBTJ). By a controlled change of the tip-island tunnel distance, the spectra display the characteristic evolution from Coulomb blockade (CB) to Coulomb staircase (CS) regime. Simulations within the semi-classical orthodox theory allow us to extract quantitatively the parameters characterizing the DBTJ, i. e., the resistances, capacitances, and the residual charge Q0. Manipulation of Q0 is achieved by controlled application of voltage pulses on the Pb islands. Moreover, under specific tunneling conditions, the influence of the tip-island junction on Q0 is revealed in topographic images of the Pb islands.

  5. Bound-state calculations of Coulomb three-body systems

    NASA Astrophysics Data System (ADS)

    Frolov, Alexei M.

    1999-06-01

    Various geometrical and energetical properties in the symmetric muonic molecular ions pp?,dd?,tt?, molecular ions ppe,dde,tte, and exotic system ??e (?+?+e-) are determined with high accuracy by using the two-stage strategy proposed by Frolov [Phys. Rev. A 57, 2436 (1998)]. The significant difference between bound-state spectra in muonic molecular ions pp?,dd?,tt? and molecular ions ppe,dde,tte ions is explained by using the general theory of bound-state spectra in Coulomb three-body systems, which is closely related with the general theory of compact operators. In particular, the principal classification of the bound-state spectra in such systems can be made in the same manner as for compact operators. For instance, the discrete spectrum of a Coulomb three-body system may have the Hilbert-Schmidt, nuclear or finite-dimensional structure. Moreover, this structure can be changed by varying some of the physical parameters (e.g., masses or charges) of the system. The developed theory is applied to the case of symmetric Coulomb three-body systems with unit charges.

  6. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule

    NASA Astrophysics Data System (ADS)

    Cloët, Ian C.; Bentz, Wolfgang; Thomas, Anthony W.

    2016-01-01

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q |≳0.5 GeV . The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

  7. 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.

  8. Phase Transitions and Stability of Three-Body Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Shi, Qicun; Kais, Sabre

    2002-03-01

    We present quantum phase transitions and critical phenomena of three-body Coulomb systems with charges (Q, q, Q) and masses (M, m, M). Full numerical results, using finite size scaling method, for an arbitrary mass ratio 0<= κ=(1+fracmM)-1 <= 1 over the range 1<= λ=midfracQqmid<= 1.25 show that there exists a transition curve λ_c(κ) through which all systems undergo a first-order phase transition from stable to unstable. Particularly, λ_c(κ) has a minimum at κ_m=0.35, which leads to a new proposed classification of the three-body Coulomb systems: molecule-like systems, κ > κ_m, such Ps^- (κ=0.5) and atom-like systems, κ < κm , such stackrel-pstackrel-pd (κ=0.33). We also show phase transitions for the three-body Coulomb systems in the large dimensional limits where they exhibit critical points with mean field exponents (α=0, β=1/2, δ=3, γ=1).

  9. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    NASA Astrophysics Data System (ADS)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  10. Optimal reconfigurations of two-craft Coulomb formations along manifolds

    NASA Astrophysics Data System (ADS)

    Jones, Drew R.; Schaub, Hanspeter

    2013-02-01

    Coulomb formations refer to swarms of closely flying spacecraft, in which the net electric charge of each vehicle is controlled. Active charge control is central to this concept and enables a propulsion system with highly desirable characteristics, albeit with limited controllability. Numerous Coulomb formation equilibria have been derived, but to maintain and maneuver these configurations, some inertial thrust is required to supplement the nearly propellant-less charge control. In this work, invariant manifold theory is applied to two-craft Coulomb equilibria, which are admitted in a linearized two-body gravity model. The manifolds associated with these systems are analyzed for the first time, and are then utilized as part of a general procedure for formulating optimal reconfigurations. Specifically, uncontrolled flows along the manifolds are sought which provide near continuous transfers from one equilibrium to another. Control is then introduced to match continuity, while minimizing inertial thrusting. This methodology aims to exploit uncontrolled motions and charge control to realize the shape-changing ability of these formations, without large inertial control efforts. Some variations in formulating and parameterizing the optimal transfers are discussed, and analytical expressions are derived to aid in establishing control parameter limits, under certain assumptions. Numerical results are provided, as demonstrative examples of the optimization procedure, using relatively simple control approximations. Finally, Particle Swarm Optimization, a novel stochastic method, is used with considerable success to solve the numerically difficult parameter optimization problems.

  11. Strong Coulomb effects on pions produced in heavy ion collisons

    NASA Astrophysics Data System (ADS)

    Sullivan, J. P.; Bistirlich, J. A.; Bowman, H. R.; Bossingham, R.; Buttke, T.; Crowe, K. M.; Frankel, K. A.; Martoff, C. J.; Miller, J.; Murphy, D. L.; Rasmussen, J. O.; Zajc, W. A.; Hashimoto, O.; Koike, M.; Péter, J.; Benenson, W.; Crawley, G. M.; Kashy, E.; Nolen, J. A.

    1982-03-01

    Doubly differential cross sections for the production of π+ and π- near the velocity of the incident beam for pion laboratory angles from 0 to 20 degrees are presented. Beams of 20Ne with EA=280, 380, and 480 MeV and 40Ar with EA=535 MeV incident on C, NaF, KCl, Cu, and U targets were used. A sharp peak in the π- spectrum and a depression in the π+ spectrum is observed at 0° near the incident projectile velocity. The effect is explained in terms of Coulomb interactions between pions and fragments of the incident beam. Least squares fits to the data using the Coulomb correction formulas of Gyulassy and Kauffmann and an effective projectile fragment charge are made. The relationship between these data and previously measured projectile fragmentation data is discussed and a simple parametrization of projectile mass, target mass, and beam energy dependence of the differential cross sections is given. NUCLEAR REACTIONS C, NaF, Cu, U (20Ne,π+/-)X, EA=280-480 MeV; C, KCl (40Ar,π+/-)X, EA=535 MeV; measured σ(Eπ,θπ), θπ=0°-20°, π velocity near beam velocity; deduced projectile fragment charges, Coulomb effects.

  12. Confining dyon-antidyon Coulomb liquid model. I.

    NASA Astrophysics Data System (ADS)

    Liu, Yizhuang; Shuryak, Edward; Zahed, Ismail

    2015-10-01

    We revisit the dyon-antidyon liquid model for the Yang-Mills confining vacuum discussed by Diakonov and Petrov, by retaining the effects of the classical interactions mediated by the streamline between the dyons and antidyons. In the SU(2) case the model describes a 4-component strongly interacting Coulomb liquid in the center symmetric phase. We show that in the linearized screening approximation, the streamline interactions yield Debye-Huckel-type corrections to the bulk parameters, such as the pressure and densities, but do not alter significantly the large-distance behavior of the correlation functions in leading order. The static scalar and charged structure factors are consistent with a plasma of a dyon-antidyon liquid with a Coulomb parameter ΓD D ¯≈1 in the dyon-antidyon channel. Heavy quarks are still linearly confined and the large spatial Wilson loops still exhibit area laws in leading order. The t' Hooft loop is shown to be one modulo Coulomb corrections.

  13. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

    PubMed

    Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

    2016-01-22

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei. PMID:26849589

  14. Instabilities of Coulomb phases and quark confinement in QCD

    SciTech Connect

    Asorey, Manuel; Santagata, Alessandro

    2009-01-01

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

  15. Experimental Studies of the Coulomb Force Effects in Deuteron-Proton Break-up Reaction at Medium Energy Regime

    NASA Astrophysics Data System (ADS)

    Ciepał, I.; Parol, W.; Kalantar-Nayestanaki, N.; Khatri, G.; Kistryn, St.; Kłos, B.; Kozela, A.; Kulessa, P.; Messchendorp, J.; Skwira-Chalot, I.; Stephan, E.; Włoch, B.

    2016-03-01

    A set of differential cross-section data of the 1H(d, pp)n breakup reaction at 130 and 160 MeV deuteron beam energies has been measured in the forward polar angles domain. The data were collected with the use of the Germanium Wall (FZ Jülich) and BINA (KVI Groningen) detectors. This part of the phase-space is special with respect to the dominant Coulomb force influence on the system dynamics. The data are compared with the theoretical calculations based on the Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest.

  16. Gravitationally induced zero modes of the Faddeev-Popov operator in the Coulomb gauge for Abelian gauge theories

    SciTech Connect

    Canfora, Fabrizio; Giacomini, Alex; Oliva, Julio

    2010-08-15

    It is shown that on curved backgrounds, the Coulomb gauge Faddeev-Popov operator can have zero modes even in the Abelian case. These zero modes cannot be eliminated by restricting the path integral over a certain region in the space of gauge potentials. The conditions for the existence of these zero modes are studied for static spherically symmetric spacetimes in arbitrary dimensions. For this class of metrics, the general analytic expression of the metric components in terms of the zero modes is constructed. Such expression allows one to find the asymptotic behavior of background metrics, which induce zero modes in the Coulomb gauge, an interesting example being the three-dimensional anti-de Sitter spacetime. Some of the implications for quantum field theory on curved spacetimes are discussed.

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

    SciTech Connect

    Lepine-Szily, A.; Benjamim, E. A.; Lichtenthaeler, R.; Guimaraes, V.; Chamon, L. C.; Hussein, M. S.; Alcantara Nunez, J.; Assuncao, M.; Barioni, A.; Camargo, O. Jr.; Denke, R. Z.; Faria, P. N. de; Mendes Junior, D. R.; Pires, K. C. C.; Gomes, P. R. S.; Arazi, A.; Padron, I.

    2006-08-14

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

  18. Coulomb breakup of 6Li into α+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,αd)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 α-d phase shifts for different states to describe the relative motion of the α particle and deuteron. To check the validity of the two particle approach for the α-d system, we apply a potential model to describe the 2H(α,γ)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 α particle and deuteron emission, especially at smaller scattering angles, in the 6Li center-of-mass (c.m.) system.

  19. 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.

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

    SciTech Connect

    Ashwin, J.; Ganesh, R.

    2010-10-15

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

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

    NASA Astrophysics Data System (ADS)

    Ashwin, J.; Ganesh, R.

    2010-10-01

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

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

    NASA Astrophysics Data System (ADS)

    Ashwin, J.; Ganesh, R.

    2010-10-01

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

  3. Full simulation study of the top Yukawa coupling at the ILC at √s = 1 TeV

    DOE PAGESBeta

    Price, T.; Roloff, P.; Strube, J.; Tanabe, T.

    2015-07-04

    We present a study of the expected precision for the measurement of the top Yukawa coupling, yt, in e+e- collisions at a center-of-mass energy of 1 TeV. Independent analyses of tt-barH final states containing at least six hadronic jets are performed, based on detailed simulations of SiD and ILD, the two candidate detector concepts for the ILC. We estimate that a statistical precision on yt of 4.5 % can be obtained with an integrated luminosity of 1 ab-1 that is split equally between two configurations for the beam polarization P(e-,e+), (-80 %,+20 %) and (+80 %,-20 %). This estimate improvesmore » to 4 % if the 1 ab-1 sample is assumed to be fully in the P(e-,e+)=(-80 %,+20 %) configuration.« less

  4. Full simulation study of the top Yukawa coupling at the ILC at √s = 1 TeV

    SciTech Connect

    Price, T.; Roloff, P.; Strube, J.; Tanabe, T.

    2015-07-04

    We present a study of the expected precision for the measurement of the top Yukawa coupling, yt, in e+e- collisions at a center-of-mass energy of 1 TeV. Independent analyses of tt-barH final states containing at least six hadronic jets are performed, based on detailed simulations of SiD and ILD, the two candidate detector concepts for the ILC. We estimate that a statistical precision on yt of 4.5 % can be obtained with an integrated luminosity of 1 ab-1 that is split equally between two configurations for the beam polarization P(e-,e+), (-80 %,+20 %) and (+80 %,-20 %). This estimate improves to 4 % if the 1 ab-1 sample is assumed to be fully in the P(e-,e+)=(-80 %,+20 %) configuration.

  5. Yukawa textures and charged Higgs boson phenomenology in the type-III two-Higgs-doublet model

    SciTech Connect

    Diaz-Cruz, J. L.; Hernandez-Sanchez, J.; Moretti, S.; Noriega-Papaqui, R.; Rosado, A.

    2009-05-01

    We discuss the implications of assuming a four-zero Yukawa texture for the properties of the charged Higgs boson within the context of the general two-Higgs-doublet model of type III. We begin by presenting a detailed analysis of the charged Higgs boson couplings with heavy quarks and the resulting pattern for its decays. The production of charged Higgs bosons is also sensitive to the modifications of its couplings, so that we also evaluate the resulting effects on the top decay t{yields}bH{sup +} as well as on 'direct'cb{yields}H{sup +}+c.c. and 'indirect'qq,gg{yields}tbH{sup +}+c.c. production. A significant scope exists at the Large Hadron Collider for several H{sup {+-}} production and decay channels combined to enable one to distinguish between such a model and alternative two-Higgs-doublet scenarios.

  6. Effect of Coulomb interaction on time of flight of cold antiprotons launched from an ion trap

    NASA Technical Reports Server (NTRS)

    Camp, J. B.; Witteborn, F. C.

    1993-01-01

    Time-of-flight spectra for Maxwell-Boltzman (MB) distributions of antiprotons initially held in an ion trap and detected after being launched through a 50-cm-long shielding drift tube have been calculated. The distributions used are of temperature 0.4-40 K, cubic length 0.003-3.0 cm, and number 10-100 particles. The mutual Coulomb repulsion of the particles causes a reduction in the number of late arrival particles expected from the MB velocity distribution. The Coulomb energy is not equally divided among the particles during the expansion. The energy is transferred preferentially to the outer particles so that the reduction in the number of slow particles is not necessarily large. The reduction factor is found to be greater than unity when the potential energy of the trapped ions is greater than about 5 percent of the ions' kinetic energy and is about 2 for the launch parameters of the Los Alamos antiproton gravity experiment.

  7. 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.

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

    SciTech Connect

    Ortakaya, Sami

    2013-11-15

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

  9. Equal-time two-point correlation functions in Coulomb gauge Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Campagnari, D.; Weber, A.; Reinhardt, H.; Astorga, F.; Schleifenbaum, W.

    2011-01-01

    We apply a functional perturbative approach to the calculation of the equal-time two-point correlation functions and the potential between static color charges to one-loop order in Coulomb gauge Yang-Mills theory. The functional approach proceeds through a solution of the Schrödinger equation for the vacuum wave functional to order g and derives the equal-time correlation functions from a functional integral representation via new diagrammatic rules. We show that the results coincide with those obtained from the usual Lagrangian functional integral approach, extract the beta function, and determine the anomalous dimensions of the equal-time gluon and ghost two-point functions and the static potential under the assumption of multiplicative renormalizability to all orders.

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

    PubMed Central

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

    2013-01-01

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

  11. 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.

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

    PubMed

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

    2013-01-01

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

  13. Time-dependent analysis of the nuclear and Coulomb dissociation of 11Be

    SciTech Connect

    Capel, Pierre; Goldstein, Gerald; Baye, Daniel

    2005-10-14

    The breakup of 11Be on carbon and lead targets around 70 MeV/nucleon is investigated within a semiclassical framework. The role of the (5/2){sup +} resonance is analyzed in both cases. It induces a narrow peak in the nuclear-induced breakup cross section, while its effect on Coulomb breakup is small. The nuclear interactions between the projectile and the target is responsible for the transition toward this resonant state. The influence of the parametrization of the 10Be-n potential that simulates 11Be is also addressed. The breakup calculation is found to be dependent on the potential choice. This leads us to question the reliability of this technique to extract spectroscopic factors.

  14. A comparison of Coulomb and pseudo-Coulomb friction implementations: Application to the table contact phase of gymnastics vaulting.

    PubMed

    Jackson, M I; Hiley, M J; Yeadon, M R

    2011-10-13

    In the table contact phase of gymnastics vaulting both dynamic and static friction act. The purpose of this study was to develop a method of simulating Coulomb friction that incorporated both dynamic and static phases and to compare the results with those obtained using a pseudo-Coulomb implementation of friction when applied to the table contact phase of gymnastics vaulting. Kinematic data were obtained from an elite level gymnast performing handspring straight somersault vaults using a Vicon optoelectronic motion capture system. An angle-driven computer model of vaulting that simulated the interaction between a seven segment gymnast and a single segment vaulting table during the table contact phase of the vault was developed. Both dynamic and static friction were incorporated within the model by switching between two implementations of the tangential frictional force. Two vaulting trials were used to determine the model parameters using a genetic algorithm to match simulations to recorded performances. A third independent trial was used to evaluate the model and close agreement was found between the simulation and the recorded performance with an overall difference of 13.5%. The two-state simulation model was found to be capable of replicating performance at take-off and also of replicating key contact phase features such as the normal and tangential motion of the hands. The results of the two-state model were compared to those using a pseudo-Coulomb friction implementation within the simulation model. The two-state model achieved similar overall results to those of the pseudo-Coulomb model but obtained solutions more rapidly. PMID:21889150

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

    SciTech Connect

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

    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.

  16. A Coulomb stress model for induced seismicity distribution due to fluid injection and withdrawal in deep boreholes

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  17. Corresponding states law for a generalized Lennard-Jones potential

    NASA Astrophysics Data System (ADS)

    Orea, P.; Romero-Martínez, A.; Basurto, E.; Vargas, C. A.; Odriozola, G.

    2015-07-01

    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.

  18. 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

  19. Screening corrections to the Coulomb crystal elastic moduli

    NASA Astrophysics Data System (ADS)

    Baiko, D. A.

    2015-08-01

    Corrections to elastic moduli, including the effective shear modulus, of a solid neutron star crust due to electron screening are calculated. At any given mass density, the crust is modelled as a body-centred cubic Coulomb crystal of fully ionized atomic nuclei of a single type with a polarizable charge-compensating electron background. Motion of the nuclei is neglected. The electron polarization is described by a simple Thomas-Fermi model of exponential electron screening. The results of numerical calculations are fitted by convenient analytic formulae. They should be used for precise neutron star oscillation modelling, a rapidly developing branch of stellar seismology.

  20. Coulombic wall slip of concentrated soft-particle suspensions

    NASA Astrophysics Data System (ADS)

    Adams, Michael; Liu, Wei; Zhang, Zhibing; Fryer, Peter

    2013-06-01

    The coefficients of friction of concentrated soft-particle suspensions (tomato paste and a microgel suspension) were measured as a function of the slip velocity for a number of substrates. The data are interpreted using a micro-elastohydrodynamic model that is consistent with significant bulk frictional dissipation and an increase in the number of particle-wall contacts with increasing normal stress. The origin of the Coulombic slip, which has not been observed previously for pastes, is ascribed to the sensitivity of the lubricating film thickness.