Duality between QCD perturbative series and power corrections

International Nuclear Information System (INIS)

Narison, S.; Zakharov, V.I.

2009-01-01

We elaborate on the relation between perturbative and power-like corrections to short-distance sensitive QCD observables. We confront theoretical expectations with explicit perturbative calculations existing in literature. As is expected, the quadratic correction is dual to a long perturbative series and one should use one of them but not both. However, this might be true only for very long perturbative series, with number of terms needed in most cases exceeding the number of terms available. What has not been foreseen, the quartic corrections might also be dual to the perturbative series. If confirmed, this would imply a crucial modification of the dogma. We confront this quadratic correction against existing phenomenology (QCD (spectral) sum rules scales, determinations of light quark masses and of α s from τ-decay). We find no contradiction and (to some extent) better agreement with the data and with recent lattice calculations.

Duality between QCD perturbative series and power corrections

Energy Technology Data Exchange (ETDEWEB)

Narison, S. [Laboratoire de Physique Theorique et Astroparticules, CNRS-IN2P3 and Universite de Montpellier II, Case 070, Place Eugene, 34095 Montpellier Cedex 05 (France)], E-mail: snarison@yahoo.fr; Zakharov, V.I. [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Munich (Germany); Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya 25, Moscow 117218 (Russian Federation)], E-mail: xxz@mppmu.mpg.de

2009-08-31

We elaborate on the relation between perturbative and power-like corrections to short-distance sensitive QCD observables. We confront theoretical expectations with explicit perturbative calculations existing in literature. As is expected, the quadratic correction is dual to a long perturbative series and one should use one of them but not both. However, this might be true only for very long perturbative series, with number of terms needed in most cases exceeding the number of terms available. What has not been foreseen, the quartic corrections might also be dual to the perturbative series. If confirmed, this would imply a crucial modification of the dogma. We confront this quadratic correction against existing phenomenology (QCD (spectral) sum rules scales, determinations of light quark masses and of {alpha}{sub s} from {tau}-decay). We find no contradiction and (to some extent) better agreement with the data and with recent lattice calculations.

Non-perturbative Heavy-Flavor Transport at RHIC and LHC

Energy Technology Data Exchange (ETDEWEB)

He, Min, E-mail: mhe@comp.tamu.edu; Fries, Rainer J.; Rapp, Ralf

2013-08-15

We calculate open heavy-flavor (HF) transport in relativistic heavy-ion collisions by applying a strong-coupling treatment in both macro- and microscopic dynamics (hydrodynamics and non-perturbative diffusion interactions). The hydrodynamic medium evolution is quantitatively constrained by bulk and multi-strange hadron spectra and elliptic flow. The heavy quark transport coefficient is evaluated from a non-perturbative T-matrix approach in the Quark–Gluon Plasma which, close to the critical temperature, leads to resonance formation and feeds into the recombination of heavy quarks on a hydrodynamic hypersurface. In the hadronic phase, the diffusion of HF mesons is obtained from effective hadronic theory. We compute observables at RHIC and LHC for non-photonic electrons and HF mesons, respectively.

On the systematic construction of convergent perturbation series

International Nuclear Information System (INIS)

Schmidt, C.

1993-12-01

Starting from the general decomposition of the many-body Hamiltonian parametrized by an operator Λwe derive the class of 'Λ-transformed' perturbation series. Aiming at practical applications we consider many-body perturbation theory of atoms and molecules in finite dimensional Hilbert spaces. Investigation of the analyticity properties of the eigenvalues and eigenstates of the Hamiltonian as functions of the coupling parameter defined by the particular decomposition of H allows for the construction of (minimal) Λoperators mapping an originally divergent series to a convergent one. There exists an operator Λ opt leading to the exact results in first order. Further improvements of the above mentioned minimal Λoperators can be achieved by approximations of Λ opt leading to fast convergent perturbation series. As the size of the remaining perturbation is given by the Λoperator chosen this method provides an a priori estimate of the convergence properties. (orig.)

EDITORIAL: Non-linear and non-Gaussian cosmological perturbations Non-linear and non-Gaussian cosmological perturbations

Science.gov (United States)

Sasaki, Misao; Wands, David

2010-06-01

In recent years there has been a resurgence of interest in the study of non-linear perturbations of cosmological models. This has been the result of both theoretical developments and observational advances. New theoretical challenges arise at second and higher order due to mode coupling and the need to develop new gauge-invariant variables beyond first order. In particular, non-linear interactions lead to deviations from a Gaussian distribution of primordial perturbations even if initial vacuum fluctuations are exactly Gaussian. These non-Gaussianities provide an important probe of models for the origin of structure in the very early universe. We now have a detailed picture of the primordial distribution of matter from surveys of the cosmic microwave background, notably NASA's WMAP satellite. The situation will continue to improve with future data from the ESA Planck satellite launched in 2009. To fully exploit these data cosmologists need to extend non-linear cosmological perturbation theory beyond the linear theory that has previously been sufficient on cosmological scales. Another recent development has been the realization that large-scale structure, revealed in high-redshift galaxy surveys, could also be sensitive to non-linearities in the primordial curvature perturbation. This focus section brings together a collection of invited papers which explore several topical issues in this subject. We hope it will be of interest to theoretical physicists and astrophysicists alike interested in understanding and interpreting recent developments in cosmological perturbation theory and models of the early universe. Of course it is only an incomplete snapshot of a rapidly developing field and we hope the reader will be inspired to read further work on the subject and, perhaps, fill in some of the missing pieces. This focus section is dedicated to the memory of Lev Kofman (1957-2009), an enthusiastic pioneer of inflationary cosmology and non-Gaussian perturbations.

Strongly perturbed Rydberg series originating from KrII 4p45s ionic states

International Nuclear Information System (INIS)

Petrov, I.D.; Demekhin, Ph.V.; Lagutin, B.M.; Sukhorukov, V.L.; Kammer, S.; Mickat, S.; Schartner, K.-H.; Ehresmann, A.; Klumpp, S.; Werner, L.; Schmoranzer, H.

2005-01-01

Photoionization cross-sections for the 4p 4 ( 3 P) 5s 4 P 5/2,3/2,1/2 satellites and 4s, 4p main levels of Kr II in the exciting-photon energy range between 28.48 and 28.70-bar eV with extremely narrow bandwidth (1.7-bar meV at 28.55-bar eV) of the monochromatized synchrotron radiation were measured utilizing the photon-induced fluorescence spectroscopy. The observed resonances were assigned to the 4p 4 5s( 4 P 1/2 )n p and 4p 4 5s( 2 P 3/2 )n p Rydberg series on the basis of calculations performed with taking into account core relaxation and interaction between many resonances and many continua. The calculation shows that the resonance structure in the photoionization channels exists due to 4p 4 ( 1 D) 5s 2 D 5/2 6p 3/2 promoter state which also strongly perturbs the above Rydberg series.

Non-resonant magnetic braking on JET and TEXTOR

DEFF Research Database (Denmark)

Sun, Y.; Liang, Y.; Shaing, K.C.

2012-01-01

The non-resonant magnetic braking effect induced by a non-axisymmetric magnetic perturbation is investigated on JET and TEXTOR. The collisionality dependence of the torque induced by the n = 1, where n is the toroidal mode number, magnetic perturbation generated by the error field correction coils...... in the 1/ν regime. The strongest NTV torque on JET is also located near the plasma core. The magnitude of the NTV torque strongly depends on the plasma response, which is also discussed in this paper. There is no obvious braking effect with n = 2 magnetic perturbation generated by the dynamic ergodic...

High resolution detection and excitation of resonant magnetic perturbations in a wall-stabilized tokamak

Energy Technology Data Exchange (ETDEWEB)

Maurer, David A. [Physics Department, Auburn University, Auburn, Alabama 36849 (United States); Shiraki, Daisuke; Levesque, Jeffrey P.; Bialek, James; Angelini, Sarah; Byrne, Patrick; DeBono, Bryan; Hughes, Paul; Mauel, Michael E.; Navratil, Gerald A.; Peng Qian; Rhodes, Dov; Rath, Nickolaus; Stoafer, Christopher [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

2012-05-15

We report high-resolution detection of the 3D plasma magnetic response of wall-stabilized tokamak discharges in the High Beta Tokamak-Extended Pulse [T. H. Ivers et al., Phys. Plasmas 3, 1926 (1996)] device. A new adjustable conducting wall has been installed on HBT-EP made up of 20 independent, movable, wall segments instrumented with three distinct sets of 40 modular coils that can be independently driven to generate a wide variety of magnetic perturbations. High-resolution detection of the plasma response is made with 216 poloidal and radial magnetic sensors that have been located and calibrated with high-accuracy. Static and dynamic plasma responses to resonant and non-resonant magnetic perturbations are observed through measurement of the step-response following a rapid change in the toroidal phase of the applied perturbations. Biorthogonal decomposition of the full set of magnetic sensors clearly defines the structures of naturally occurring external kinks as being composed of independent m/n = 3/1 and 6/2 modes. Resonant magnetic perturbations were applied to discharges with pre-existing, saturated m/n = 3/1 external kink mode activity. This m/n = 3/1 kink mode was observed to lock to the applied perturbation field. During this kink mode locked period, the plasma resonant response is characterized by a linear, a saturated, and a disruptive plasma regime dependent on the magnitude of the applied field and value of the edge safety factor and plasma rotation.

New evidence and impact of electron transport non-linearities based on new perturbative inter-modulation analysis

Science.gov (United States)

van Berkel, M.; Kobayashi, T.; Igami, H.; Vandersteen, G.; Hogeweij, G. M. D.; Tanaka, K.; Tamura, N.; Zwart, H. J.; Kubo, S.; Ito, S.; Tsuchiya, H.; de Baar, M. R.; LHD Experiment Group

2017-12-01

A new methodology to analyze non-linear components in perturbative transport experiments is introduced. The methodology has been experimentally validated in the Large Helical Device for the electron heat transport channel. Electron cyclotron resonance heating with different modulation frequencies by two gyrotrons has been used to directly quantify the amplitude of the non-linear component at the inter-modulation frequencies. The measurements show significant quadratic non-linear contributions and also the absence of cubic and higher order components. The non-linear component is analyzed using the Volterra series, which is the non-linear generalization of transfer functions. This allows us to study the radial distribution of the non-linearity of the plasma and to reconstruct linear profiles where the measurements were not distorted by non-linearities. The reconstructed linear profiles are significantly different from the measured profiles, demonstrating the significant impact that non-linearity can have.

Design of the power system for dynamic resonant magnetic perturbation coils on the J-TEXT tokamak

Energy Technology Data Exchange (ETDEWEB)

Yi, B. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Ding, Y.H., E-mail: yhding@mail.hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang, M.; Rao, B.; Nan, J.Y.; Zeng, W.B.; Zheng, M.Y.; Xu, H.Y.; Zhuang, G.; Pan, Y. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

2013-10-15

Highlights: ► We introduce the dynamic resonant magnetic perturbation coils system on J-TEXT. ► Details of the design of the power supply system have been presented. ► At DC mode, two antiparallel 6-pulse phase thyristor rectifiers were chosen. ► An AC–DC–AC converter including a series resonant inverter was adopted for AC mode. ► Some engineering testing result was given in this paper. -- Abstract: A set of in-vessel saddle coils has been installed on J-TEXT tokamak. They are proposed for further researches on controlling tearing modes and driving plasma rotation by static and dynamic resonant magnetic perturbations (RMPs). The saddle coils will be energized by DC with the amplitude up to 10 kA, or AC with maximum amplitude up to 5 kA within the frequency range of 1–5 kHz. At DC mode two antiparallel 6-pulse phase thyristor rectifiers are chosen to obtain bidirectional current, while at AC mode an AC–DC–AC converter including a series resonant inverter can generate current of various amplitudes and frequencies. The paper presents the design of the power supply system, based on the definition of the power supply requirements and the feasibility of implementation of the topology and control strategy. Some simulation and experimental results are given in the end.

Rayleigh-Schrödinger series and Birkhoff decomposition

Science.gov (United States)

Novelli, Jean-Christophe; Paul, Thierry; Sauzin, David; Thibon, Jean-Yves

2018-01-01

We derive new expressions for the Rayleigh-Schrödinger series describing the perturbation of eigenvalues of quantum Hamiltonians. The method, somehow close to the so-called dimensional renormalization in quantum field theory, involves the Birkhoff decomposition of some Laurent series built up out of explicit fully non-resonant terms present in the usual expression of the Rayleigh-Schrödinger series. Our results provide new combinatorial formulae and a new way of deriving perturbation series in quantum mechanics. More generally we prove that such a decomposition provides solutions of general normal form problems in Lie algebras.

A perturbative approach to mass-generation - the non-linear sigma model

International Nuclear Information System (INIS)

Davis, A.C.; Nahm, W.

1985-01-01

A calculational scheme is presented to include non-perturbative effects into the perturbation expansion. As an example we use the O(N + 1) sigma model. The scheme uses a natural parametrisation such that the lagrangian can be written in a form normal-ordered with respect to the O(N + 1) symmetric vacuum plus vacuum expectation values, the latter calculated by symmetry alone. Including such expectation values automatically leads to the inclusion of a mass-gap in the perturbation series. (orig.)

Elliptic CY3folds and non-perturbative modular transformation

International Nuclear Information System (INIS)

Iqbal, Amer; Shabbir, Khurram

2016-01-01

We study the refined topological string partition function of a class of toric elliptically fibered Calabi-Yau threefolds. These Calabi-Yau threefolds give rise to five dimensional quiver gauge theories and are dual to configurations of M5-M2-branes. We determine the Gopakumar-Vafa invariants for these threefolds and show that the genus g free energy is given by the weight 2 g Eisenstein series. We also show that although the free energy at all genera are modular invariant, the full partition function satisfies the non-perturbative modular transformation property discussed by Lockhart and Vafa in arXiv:1210.5909 and therefore the modularity of free energy is up to non-perturbative corrections. (orig.)

Elliptic CY3folds and non-perturbative modular transformation

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Amer [Government College University, Abdus Salam School of Mathematical Sciences, Lahore (Pakistan); Shabbir, Khurram [Government College University, Department of Mathematics, Lahore (Pakistan)

2016-03-15

We study the refined topological string partition function of a class of toric elliptically fibered Calabi-Yau threefolds. These Calabi-Yau threefolds give rise to five dimensional quiver gauge theories and are dual to configurations of M5-M2-branes. We determine the Gopakumar-Vafa invariants for these threefolds and show that the genus g free energy is given by the weight 2 g Eisenstein series. We also show that although the free energy at all genera are modular invariant, the full partition function satisfies the non-perturbative modular transformation property discussed by Lockhart and Vafa in arXiv:1210.5909 and therefore the modularity of free energy is up to non-perturbative corrections. (orig.)

Non-perturbative effects in supersymmetry

International Nuclear Information System (INIS)

Veneziano, G.

1987-01-01

Some non perturbative aspects of globally supersymmetric (SUSY) gauge theories are discussed. These share with their non-supersymmetric analogues interesting non perturbative features, such as the spontaneous breaking of chiral symmetries via condensates. What is peculiar about supersymmetric theories, however, is that one is able to say a lot about non-perturbative effects even without resorting to elaborate numerical calculations: general arguments, supersymmetric and chiral Ward identities and analytic, dynamical calculations will turn out to effectively determine most of the supersymmetric vacuum properties. 28 references, 5 figures

A non-perturbative argument for the non-abelian Higgs mechanism

International Nuclear Information System (INIS)

De Palma, G.; Strocchi, F.

2013-01-01

The evasion of massless Goldstone bosons by the non-abelian Higgs mechanism is proved by a non-perturbative argument in the local BRST gauge. -- Highlights: •The perturbative explanation of the Higgs mechanism (HM) is not under mathematical control. •We offer a non-perturbative proof of the absence of Goldstone bosons from the non-abelian HM. •Our non-perturbative proof in the BRST gauge avoids a mean field ansatz and expansion

A non-perturbative argument for the non-abelian Higgs mechanism

Energy Technology Data Exchange (ETDEWEB)

De Palma, G. [Scuola Normale Superiore, Pisa (Italy); INFN, Sezione di Pisa, Pisa (Italy); Strocchi, F., E-mail: franco.strocchi@sns.it [INFN, Sezione di Pisa, Pisa (Italy)

2013-09-15

The evasion of massless Goldstone bosons by the non-abelian Higgs mechanism is proved by a non-perturbative argument in the local BRST gauge. -- Highlights: •The perturbative explanation of the Higgs mechanism (HM) is not under mathematical control. •We offer a non-perturbative proof of the absence of Goldstone bosons from the non-abelian HM. •Our non-perturbative proof in the BRST gauge avoids a mean field ansatz and expansion.

Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

International Nuclear Information System (INIS)

Rack, Michael Thomas

2014-01-01

Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

Energy Technology Data Exchange (ETDEWEB)

Rack, Michael Thomas

2014-07-11

Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

On the non-perturbative effects

International Nuclear Information System (INIS)

Manjavidze, J.; Voronyuk, V.

2004-01-01

The quantum correspondence principle based on the time reversibility is adopted to take into account the non-Abelian symmetry constrains. The main properties of the new strong-coupling perturbation theory which take into account non-perturbative effects are described. (author)

Non-perturbative versus perturbative renormalization of lattice operators

International Nuclear Information System (INIS)

Goeckeler, M.; Technische Hochschule Aachen; Horsley, R.; Ilgenfritz, E.M.; Oelrich, H.; Forschungszentrum Juelich GmbH; Schierholz, G.; Forschungszentrum Juelich GmbH; Perlt, H.; Schiller, A.; Rakow, P.

1995-09-01

Our objective is to compute the moments of the deep-inelastic structure functions of the nucleon on the lattice. A major source of uncertainty is the renormalization of the lattice operators that enter the calculation. In this talk we compare the renormalization constants of the most relevant twist-two bilinear quark operators which we have computed non-perturbatively and perturbatively to one loop order. Furthermore, we discuss the use of tadpole improved perturbation theory. (orig.)

Complex energies from real perturbation series for the LoSurdo-Stark effect in hydrogen by Borel-Pade approximants

Energy Technology Data Exchange (ETDEWEB)

Franceschini, V.; Grecchi, V.; Silverstone, H.J.

1985-09-01

The resonance energies for the hydrogen atom in an electric field, both the real and imaginary parts, have been calculated together from the real Rayleigh-Schroedinger perturbation series by Borel summation. Pade approximants were used to evaluate the Borel transform. The numerical results compare well with values obtained by the complex-coordinate variational method and by sequential use of Pade approximants.

Pressure-driven amplification and penetration of resonant magnetic perturbations

Energy Technology Data Exchange (ETDEWEB)

Loizu, J. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany); Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Hudson, S. R.; Lazerson, S. A.; Bhattacharjee, A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Helander, P. [Max-Planck-Institut für Plasmaphysik, D-17491 Greifswald (Germany)

2016-05-15

We show that a resonant magnetic perturbation applied to the boundary of an ideal plasma screw-pinch equilibrium with nested surfaces can penetrate inside the resonant surface and into the core. The response is significantly amplified with increasing plasma pressure. We present a rigorous verification of nonlinear equilibrium codes against linear theory, showing excellent agreement.

Non-adiabatic perturbations in multi-component perfect fluids

Energy Technology Data Exchange (ETDEWEB)

Koshelev, N.A., E-mail: koshna71@inbox.ru [Ulyanovsk State University, Leo Tolstoy str 42, 432970 (Russian Federation)

2011-04-01

The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.

Non-adiabatic perturbations in multi-component perfect fluids

International Nuclear Information System (INIS)

Koshelev, N.A.

2011-01-01

The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models

The role of resonances in chiral perturbation theory

International Nuclear Information System (INIS)

Ecker, G.; Rafael, E. de

1988-09-01

The strong interactions of low-lying meson resonances (spin ≤ 1) with the octet of pseudoscalar mesons (π,Κ,η) are considered to lowest order in the derivative expansion of chiral SU(3). The resonance contributions to the coupling constants of the O(p 4 ) effective chiral lagrangian involving pseudoscalar fields only are determined. These low-energy coupling constants are found to be dominated by the resonance contributions. Although we do not treat the vector and axial-vector mesons as gauge bosons of local chiral symmetry, vector meson dominance emerges as a prominent result of our analysis. As a further application of chiral resonance couplings, we calculate the electromagnetic pion mass difference to lowest order in chiral perturbation theory with explicit resonance fields. 29 refs., 2 figs., 5 tabs. (Author)

Nu shifts in betatron oscillations from uniform perturbations in the presence of non-linear magnetic guide fields

International Nuclear Information System (INIS)

Crebbin, K.C.

1985-05-01

Uniform magnetic field perturbations cause a closed orbit distortion in a circular accelerator. If the magnetic guide field is non-linear these perturbations can also cause a Nu shift in the betatron oscillations. Such a shift in radial Nu values has been observed in the Bevalac while studying the low energy resonant extraction system. In the Bevalac, the radial perturbation comes from the quadrants being magnetically about 0.8% longer than 90 0 . The normal effect of this type of perturbation is a radial closed orbit shift and orbit distortion. The Nu shift, associated with this type of perturbation in the presence of a non-linear guide field, is discussed in this paper. A method of handling the non-linear n values is discussed as well as the mechanism for the associated Nu shift. Computer calculations are compared to measurements. 2 refs., 4 figs

Non-hard sphere thermodynamic perturbation theory.

Science.gov (United States)

Zhou, Shiqi

2011-08-21

A non-hard sphere (HS) perturbation scheme, recently advanced by the present author, is elaborated for several technical matters, which are key mathematical details for implementation of the non-HS perturbation scheme in a coupling parameter expansion (CPE) thermodynamic perturbation framework. NVT-Monte Carlo simulation is carried out for a generalized Lennard-Jones (LJ) 2n-n potential to obtain routine thermodynamic quantities such as excess internal energy, pressure, excess chemical potential, excess Helmholtz free energy, and excess constant volume heat capacity. Then, these new simulation data, and available simulation data in literatures about a hard core attractive Yukawa fluid and a Sutherland fluid, are used to test the non-HS CPE 3rd-order thermodynamic perturbation theory (TPT) and give a comparison between the non-HS CPE 3rd-order TPT and other theoretical approaches. It is indicated that the non-HS CPE 3rd-order TPT is superior to other traditional TPT such as van der Waals/HS (vdW/HS), perturbation theory 2 (PT2)/HS, and vdW/Yukawa (vdW/Y) theory or analytical equation of state such as mean spherical approximation (MSA)-equation of state and is at least comparable to several currently the most accurate Ornstein-Zernike integral equation theories. It is discovered that three technical issues, i.e., opening up new bridge function approximation for the reference potential, choosing proper reference potential, and/or using proper thermodynamic route for calculation of f(ex-ref), chiefly decide the quality of the non-HS CPE TPT. Considering that the non-HS perturbation scheme applies for a wide variety of model fluids, and its implementation in the CPE thermodynamic perturbation framework is amenable to high-order truncation, the non-HS CPE 3rd-order or higher order TPT will be more promising once the above-mentioned three technological advances are established. © 2011 American Institute of Physics

Non-Gaussianity from isocurvature perturbations

Energy Technology Data Exchange (ETDEWEB)

Kawasaki, Masahiro; Nakayama, Kazunori; Sekiguchi, Toyokazu; Suyama, Teruaki [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582 (Japan); Takahashi, Fuminobu, E-mail: kawasaki@icrr.u-tokyo.ac.jp, E-mail: nakayama@icrr.u-tokyo.ac.jp, E-mail: sekiguti@icrr.u-tokyo.ac.jp, E-mail: suyama@icrr.u-tokyo.ac.jp, E-mail: fuminobu.takahashi@ipmu.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa 277-8568 (Japan)

2008-11-15

We develop a formalism for studying non-Gaussianity in both curvature and isocurvature perturbations. It is shown that non-Gaussianity in the isocurvature perturbation between dark matter and photons leaves distinct signatures in the cosmic microwave background temperature fluctuations, which may be confirmed in future experiments, or possibly even in the currently available observational data. As an explicit example, we consider the quantum chromodynamics axion and show that it can actually induce sizable non-Gaussianity for the inflationary scale, H{sub inf} = O(10{sup 9}-10{sup 11}) GeV.

Propagation Dynamics Associated with Resonant Magnetic Perturbation Fields in High-Confinement Mode Plasmas inside the KSTAR Tokamak.

Science.gov (United States)

Xiao, W W; Evans, T E; Tynan, G R; Yoon, S W; Jeon, Y M; Ko, W H; Nam, Y U; Oh, Y K

2017-11-17

The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5  m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.

New evidence and impact of electron transport non-linearities based on new perturbative inter-modulation analysis

NARCIS (Netherlands)

van Berkel, M.; Kobayashi, T.; Igami, H.; Vandersteen, Gerd; Hogeweij, G.M.D.; Tanaka, K.; Tamura, N.; Zwart, Hans; Kubo, S.; Ito, S.; Tsuchiya, H.; de Baar, M.R.

2017-01-01

A new methodology to analyze non-linear components in perturbative transport experiments is introduced. The methodology has been experimentally validated in the Large Helical Device for the electron heat transport channel. Electron cyclotron resonance heating with different modulation frequencies by

Noise-enhanced Parametric Resonance in Perturbed Galaxies

Science.gov (United States)

Sideris, Ioannis V.; Kandrup, Henry E.

2004-02-01

This paper describes how parametric resonances associated with a galactic potential subjected to relatively low-amplitude, strictly periodic time-dependent perturbations can be impacted by pseudo-random variations in the pulsation frequency, modeled as colored noise. One aim thereby is to allow for the effects of a changing oscillation frequency as the density distribution associated with a galaxy evolves during violent relaxation. Another is to mimic the possible effects of internal substructures, satellite galaxies, and/or a high-density environment. The principal conclusions are that allowing for a variable frequency does not vitiate the effects of parametric resonance, and that, in at least some cases, such variations can increase the overall importance of parametric resonance associated with systematic pulsations. In memory of Professor H. E. Kandrup, a brilliant scientist, excellent teacher, and good friend. His genius and sense of humor will be greatly missed.

A perturbative approach for enhancing the performance of time series forecasting.

Science.gov (United States)

de Mattos Neto, Paulo S G; Ferreira, Tiago A E; Lima, Aranildo R; Vasconcelos, Germano C; Cavalcanti, George D C

2017-04-01

This paper proposes a method to perform time series prediction based on perturbation theory. The approach is based on continuously adjusting an initial forecasting model to asymptotically approximate a desired time series model. First, a predictive model generates an initial forecasting for a time series. Second, a residual time series is calculated as the difference between the original time series and the initial forecasting. If that residual series is not white noise, then it can be used to improve the accuracy of the initial model and a new predictive model is adjusted using residual series. The whole process is repeated until convergence or the residual series becomes white noise. The output of the method is then given by summing up the outputs of all trained predictive models in a perturbative sense. To test the method, an experimental investigation was conducted on six real world time series. A comparison was made with six other methods experimented and ten other results found in the literature. Results show that not only the performance of the initial model is significantly improved but also the proposed method outperforms the other results previously published. Copyright © 2017 Elsevier Ltd. All rights reserved.

Non-adiabatic perturbations in Ricci dark energy model

International Nuclear Information System (INIS)

Karwan, Khamphee; Thitapura, Thiti

2012-01-01

We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included

Formulating and testing a method for perturbing precipitation time series to reflect anticipated climatic changes

DEFF Research Database (Denmark)

Sørup, Hjalte Jomo Danielsen; Georgiadis, Stylianos; Gregersen, Ida Bülow

2017-01-01

Urban water infrastructure has very long planning horizons, and planning is thus very dependent on reliable estimates of the impacts of climate change. Many urban water systems are designed using time series with a high temporal resolution. To assess the impact of climate change on these systems......, similarly high-resolution precipitation time series for future climate are necessary. Climate models cannot at their current resolutions provide these time series at the relevant scales. Known methods for stochastic downscaling of climate change to urban hydrological scales have known shortcomings...... in constructing realistic climate-changed precipitation time series at the sub-hourly scale. In the present study we present a deterministic methodology to perturb historical precipitation time series at the minute scale to reflect non-linear expectations to climate change. The methodology shows good skill...

Suppressing magnetic island growth by resonant magnetic perturbation

Science.gov (United States)

Yu, Q.; Günter, S.; Lackner, K.

2018-05-01

The effect of externally applied resonant magnetic perturbations (RMPs) on the growth of magnetic islands is investigated based on two-fluid equations. It is found that if the local bi-normal electron fluid velocity at the resonant surface is sufficiently large, static RMPs of the same helicity and of moderate amplitude can suppress the growth of magnetic islands in high-temperature plasmas. These islands will otherwise grow, driven by an unfavorable plasma current density profile and bootstrap current perturbation. These results indicate that the error field can stabilize island growth, if the error field amplitude is not too large and the local bi-normal electron fluid velocity is not too low. They also indicate that applied rotating RMPs with an appropriate frequency can be utilized to suppress island growth in high-temperature plasmas, even for a low bi-normal electron fluid velocity. A significant change in the local equilibrium plasma current density gradient by small amplitude RMPs is found for realistic plasma parameters, which are important for the island stability and are expected to be more important for fusion reactors with low plasma resistivity.

Perturbative and constructive renormalization

International Nuclear Information System (INIS)

Veiga, P.A. Faria da

2000-01-01

These notes are a survey of the material treated in a series of lectures delivered at the X Summer School Jorge Andre Swieca. They are concerned with renormalization in Quantum Field Theories. At the level of perturbation series, we review classical results as Feynman graphs, ultraviolet and infrared divergences of Feynman integrals. Weinberg's theorem and Hepp's theorem, the renormalization group and the Callan-Symanzik equation, the large order behavior and the divergence of most perturbation series. Out of the perturbative regime, as an example of a constructive method, we review Borel summability and point out how it is possible to circumvent the perturbation diseases. These lectures are a preparation for the joint course given by professor V. Rivasseau at the same school, where more sophisticated non-perturbative analytical methods based on rigorous renormalization group techniques are presented, aiming at furthering our understanding about the subject and bringing field theoretical models to a satisfactory mathematical level. (author)

A discrete homotopy perturbation method for non-linear Schrodinger equation

Directory of Open Access Journals (Sweden)

H. A. Wahab

2015-12-01

Full Text Available A general analysis is made by homotopy perturbation method while taking the advantages of the initial guess, appearance of the embedding parameter, different choices of the linear operator to the approximated solution to the non-linear Schrodinger equation. We are not dependent upon the Adomian polynomials and find the linear forms of the components without these calculations. The discretised forms of the nonlinear Schrodinger equation allow us whether to apply any numerical technique on the discritisation forms or proceed for perturbation solution of the problem. The discretised forms obtained by constructed homotopy provide the linear parts of the components of the solution series and hence a new discretised form is obtained. The general discretised form for the NLSE allows us to choose any initial guess and the solution in the closed form.

Effects of 3D Magnetic Perturbations on Toroidal Plasmas

International Nuclear Information System (INIS)

Callen, J.D.

2010-01-01

Full text: To lowest order tokamaks are two-dimensional (2D) axisymmetric magnetic systems. But small 3D magnetic perturbations (both externally applied and from plasma instabilities) have many interesting and useful effects on tokamak (and quasi-symmetric stellarator) plasmas. Plasma transport equations that include these effects, especially on diamagnetic-level toroidal plasma rotation, have recently been developed. The 3D magnetic perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (1 to 5) resonant (q = m/n in plasma) and non-resonant fields, medium n (due to toroidal field ripple), and high n (due to microturbulence). This paper concentrates on low and medium n perturbations. Low n non-resonant magnetic fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal plasma rotation throughout the plasma toward an offset flow in the counter-I p direction; recent tokamak experiments have confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n perturbations have similar effects plus possible ripple trapping and resultant edge ion losses. A low n resonant magnetic field induces a toroidal plasma torque in the vicinity of the rational surface; when large enough it can stop plasma rotation there and lead to a locked mode, which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components; in the plasma their lowest n components are amplified by plasma responses, particularly at high beta. Low n plasma instabilities (e.g., NTMs, RWMs) cause additional 3D magnetic perturbations in tokamak plasmas; tearing modes can bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can cause local magnetic stochasticity and influence H-mode edge pedestal transport. These various effects of 3D magnetic perturbations can be used to control the toroidal plasma

Non-perturbative materialization of ghosts

International Nuclear Information System (INIS)

Emparan, Roberto; Garriga, Jaume

2006-01-01

In theories with a hidden ghost sector that couples to visible matter through gravity only, empty space can decay into ghosts and ordinary matter by graviton exchange. Perturbatively, such processes can be very slow provided that the gravity sector violates Lorentz invariance above some cut-off scale. Here, we investigate non-perturbative decay processes involving ghosts, such as the spontaneous creation of self-gravitating lumps of ghost matter, as well as pairs of Bondi dipoles (i.e. lumps of ghost matter chasing after positive energy objects). We find the corresponding instantons and calculate their Euclidean action. In some cases, the instantons induce topology change or have negative Euclidean action. To shed some light on the meaning of such peculiarities, we also consider the nucleation of concentrical domain walls of ordinary and ghost matter, where the Euclidean calculation can be compared with the canonical (Lorentzian) description of tunneling. We conclude that non-perturbative ghost nucleation processes can be safely suppressed in phenomenological scenarios

Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Kazuya; Yamada, Shoichi, E-mail: ktakahashi@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku 169-8555 (Japan)

2014-10-20

We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch and Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solved as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M {sub ☉} progenitor model by Woosley and Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.

Non-perturbative QCD and hadron physics

International Nuclear Information System (INIS)

Cobos-Martínez, J J

2016-01-01

A brief exposition of contemporary non-perturbative methods based on the Schwinger-Dyson (SDE) and Bethe-Salpeter equations (BSE) of Quantum Chromodynamics (QCD) and their application to hadron physics is given. These equations provide a non-perturbative continuum formulation of QCD and are a powerful and promising tool for the study of hadron physics. Results on some properties of hadrons based on this approach, with particular attention to the pion distribution amplitude, elastic, and transition electromagnetic form factors, and their comparison to experimental data are presented. (paper)

Implications of perturbative unitarity for scalar di-boson resonance searches at LHC

Energy Technology Data Exchange (ETDEWEB)

Di Luzio, Luca [Universita di Genova, Dipartimento di Fisica, Genova (Italy); Durham University, Institute for Particle Physics Phenomenology, Department of Physics, Durham (United Kingdom); INFN, Sezione di Genova (Italy); Kamenik, Jernej F. [Jozef Stefan Institute, Ljubljana (Slovenia); University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana (Slovenia); Nardecchia, Marco [DAMTP, University of Cambridge, Cambridge (United Kingdom); CERN, Theoretical Physics Department, Geneva (Switzerland)

2017-01-15

We study the constraints implied by partial wave unitarity on new physics in the form of spin-zero di-boson resonances at LHC. We derive the scale where the effective description in terms of the SM supplemented by a single resonance is expected to break down depending on the resonance mass and signal cross section. Likewise, we use unitarity arguments in order to set perturbativity bounds on renormalizable UV completions of the effective description. We finally discuss under which conditions scalar di-boson resonance signals can be accommodated within weakly coupled models. (orig.)

Very high order lattice perturbation theory for Wilson loops

International Nuclear Information System (INIS)

Horsley, R.

2010-10-01

We calculate perturbativeWilson loops of various sizes up to loop order n=20 at different lattice sizes for pure plaquette and tree-level improved Symanzik gauge theories using the technique of Numerical Stochastic Perturbation Theory. This allows us to investigate the behavior of the perturbative series at high orders. We observe differences in the behavior of perturbative coefficients as a function of the loop order. Up to n=20 we do not see evidence for the often assumed factorial growth of the coefficients. Based on the observed behavior we sum this series in a model with hypergeometric functions. Alternatively we estimate the series in boosted perturbation theory. Subtracting the estimated perturbative series for the average plaquette from the non-perturbative Monte Carlo result we estimate the gluon condensate. (orig.)

Computation of solar perturbations with Poisson series

Science.gov (United States)

Broucke, R.

1974-01-01

Description of a project for computing first-order perturbations of natural or artificial satellites by integrating the equations of motion on a computer with automatic Poisson series expansions. A basic feature of the method of solution is that the classical variation-of-parameters formulation is used rather than rectangular coordinates. However, the variation-of-parameters formulation uses the three rectangular components of the disturbing force rather than the classical disturbing function, so that there is no problem in expanding the disturbing function in series. Another characteristic of the variation-of-parameters formulation employed is that six rather unusual variables are used in order to avoid singularities at the zero eccentricity and zero (or 90 deg) inclination. The integration process starts by assuming that all the orbit elements present on the right-hand sides of the equations of motion are constants. These right-hand sides are then simple Poisson series which can be obtained with the use of the Bessel expansions of the two-body problem in conjunction with certain interation methods. These Poisson series can then be integrated term by term, and a first-order solution is obtained.

Excited states of ethylene interpreted in terms of perturbed Rydberg series

International Nuclear Information System (INIS)

Yamamoto, Shigeyoshi; Tatewaki, Hiroshi

2003-01-01

We have investigated the excited states of the ethylene molecule by the multireference configuration interaction (MRCI) method. In particular, the nature of the V state (1 1 B 1u π→π*) was interpreted in terms of perturbed Rydberg series. To clarify the role of the perturbers, we use pseudo-restricted Hartree-Fock natural orbitals (PRHFNO), which would be the most suitable molecular orbital set to describe Rydberg series. It is well known that the expectation value of x 2 for the V state is reduced from 44a 0 2 (RHF) to around 17a 0 2 by considering electron correlation effects, where x is the direction out of the molecular plane. In the present study, a reasonable 2 > value was obtained from small multireference configuration interaction with single excitations (MRCIS), where the π→π* configurations and a few perturbers were assigned as the reference configurations. The major perturbers were found to be five configurations represented by 3a g → 3b 1u , 1b 3g → 3b 2u , 2b 1u → 4a g , 2a g → 3b 1u , and 1b 2u → 2b 3g with respect to the ground state configuration. The V state can therefore be described as a scattering process of the π→π* state by these perturbers. Other low-lying excited states are also investigated by the MRCI method

Non-perturbative analytical solutions of the space- and time-fractional Burgers equations

International Nuclear Information System (INIS)

Momani, Shaher

2006-01-01

Non-perturbative analytical solutions for the generalized Burgers equation with time- and space-fractional derivatives of order α and β, 0 < α, β ≤ 1, are derived using Adomian decomposition method. The fractional derivatives are considered in the Caputo sense. The solutions are given in the form of series with easily computable terms. Numerical solutions are calculated for the fractional Burgers equation to show the nature of solution as the fractional derivative parameter is changed

Edge localized modes control by resonant magnetic perturbations

International Nuclear Information System (INIS)

Nardon, E.

2007-10-01

The present work is dedicated to one of the most promising methods of control of the ELMs (Edge Localized Modes), based on a system of coils producing Resonant Magnetic Perturbations (RMPs). Our main objectives are, on the one hand, to improve the physical understanding of the mechanisms at play, and on the other hand to propose a concrete design of ELMs control coils for ITER. In order to calculate and analyze the magnetic perturbations produced by a given set of coils, we have developed the ERGOS code. The first ERGOS calculation was for the DIII-D ELMs control coils, the I-coils. It showed that they produce magnetic islands chains which overlap at the edge of the plasma, resulting in the ergodization of the magnetic field. We have then used ERGOS for the modelling of the experiments on ELMs control using the error field correction coils at JET and MAST. In the case of JET, we have shown the existence of a correlation between the mitigation of the ELMs and the ergodization of the magnetic field at the edge, in agreement with the DIII-D result. In order to design the ELMs control coils for ITER we have used ERGOS intensively, taking the case of the DIII-D I-coils as a reference. Three candidate designs came out, which we presented at the ITER Design Review, in 2007. Recently, the ITER management decided to provide a budget for building ELMs control coils, the design of which remains to be chosen between two of the three options that we proposed. Finally, in order to understand better the non-linear magnetohydrodynamics phenomena taking place in ELMs control by RMPs, we performed numerical simulations, in particular with the JOREK code for a DIII-D case. The simulations reveal the existence of convection cells induced at the edge by the magnetic perturbations, and the possible screening of the RMPs in presence of rotation

Non perturbative method for radiative corrections applied to lepton-proton scattering

International Nuclear Information System (INIS)

Chahine, C.

1979-01-01

We present a new, non perturbative method to effect radiative corrections in lepton (electron or muon)-nucleon scattering, useful for existing or planned experiments. This method relies on a spectral function derived in a previous paper, which takes into account both real soft photons and virtual ones and hence is free from infrared divergence. Hard effects are computed perturbatively and then included in the form of 'hard factors' in the non peturbative soft formulas. Practical computations are effected using the Gauss-Jacobi integration method which reduce the relevant integrals to a rapidly converging sequence. For the simple problem of the radiative quasi-elastic peak, we get an exponentiated form conjectured by Schwinger and found by Yennie, Frautschi and Suura. We compare also our results with the peaking approximation, which we derive independantly, and with the exact one-photon emission formula of Mo and Tsai. Applications of our method to the continuous spectrum include the radiative tail of the Δ 33 resonance in e + p scattering and radiative corrections to the Feynman scale invariant F 2 structure function for the kinematics of two recent high energy muon experiments

Transmission Line Resonator Segmented with Series Capacitors

DEFF Research Database (Denmark)

Zhurbenko, Vitaliy; Boer, Vincent; Petersen, Esben Thade

2016-01-01

Transmission line resonators are often used as coils in high field MRI. Due to distributed nature of such resonators, coils based on them produce inhomogeneous field. This work investigates application of series capacitors to improve field homogeneity along the resonator. The equations for optimal...... values of evenly distributed capacitors are presented. The performances of the segmented resonator and a regular transmission line resonator are compared....

Non-perturbative renormalization of HQET and QCD

International Nuclear Information System (INIS)

Sommer, Rainer

2003-01-01

We discuss the necessity of non-perturbative renormalization in QCD and HQET and explain the general strategy for solving this problem. A few selected topics are discussed in some detail, namely the importance of off shell improvement in the MOM-scheme on the lattice, recent progress in the implementation of finite volume schemes and then particular emphasis is put on the recent idea to carry out a non-perturbative renormalization of the Heavy Quark Effective Theory (HQET)

Radial thermal diffusivity of toroidal plasma affected by resonant magnetic perturbations

International Nuclear Information System (INIS)

Kanno, Ryutaro; Nunami, Masanori; Satake, Shinsuke; Takamaru, Hisanori; Okamoto, Masao

2012-04-01

We investigate how the radial thermal diffusivity of an axisymmetric toroidal plasma is modified by effect of resonant magnetic perturbations (RMPs), using a drift kinetic simulation code for calculating the thermal diffusivity in the perturbed region. The perturbed region is assumed to be generated on and around the resonance surfaces, and is wedged in between the regular closed magnetic surfaces. It has been found that the radial thermal diffusivity χ r in the perturbed region is represented as χ r = χ r (0) {1 + c r parallel 2 >}. Here r parallel 2 > 1/2 is the strength of the RMPs in the radial directions, means the flux surface average defined by the unperturbed (i.e., original) magnetic field, χ r (0) is the neoclassical thermal diffusivity, and c is a positive coefficient. In this paper, dependence of the coefficient c on parameters of the toroidal plasma is studied in results given by the δ f simulation code solving the drift kinetic equation under an assumption of zero electric field. We find that the dependence of c is given as c ∝ ω b /ν eff m in the low collisionality regime ν eff b , where ν eff is the effective collision frequency, ω b is the bounce frequency and m is the particle mass. In case of ν eff > ω b , the thermal diffusivity χ r evaluated by the simulations becomes close to the neoclassical thermal diffusivity χ r (0) . (author)

Effects of 3D magnetic perturbations on toroidal plasmas

International Nuclear Information System (INIS)

Callen, J.D.

2011-01-01

Small three-dimensional (3D) magnetic field perturbations have many interesting and possibly useful effects on tokamak and quasi-symmetric stellarator plasmas. Plasma transport equations that include these effects, most notably on diamagnetic-level toroidal plasma flows, have recently been developed. The 3D field perturbations and their plasma effects can be classified according to their toroidal mode number n: low n (say 1-5) resonant (with field line pitch, q = m/n) and non-resonant fields, medium n (∼20, due to toroidal field ripple) and high n (due to microturbulence). Low n non-resonant fields induce a neoclassical toroidal viscosity (NTV) that damps toroidal rotation throughout the plasma towards an offset rotation in the counter-current direction. Recent tokamak experiments have generally confirmed and exploited these predictions by applying external low n non-resonant magnetic perturbations. Medium n toroidal field ripple produces similar effects plus possible ripple-trapping NTV effects and ion direct losses in the edge. A low n (e.g. n = 1) resonant field is mostly shielded by the toroidally rotating plasma at and inside the resonant (rational) surface. If it is large enough it can stop plasma rotation at the rational surface, facilitate magnetic reconnection there and lead to a growing stationary magnetic island (locked mode), which often causes a plasma disruption. Externally applied 3D magnetic perturbations usually have many components. In the plasma their lowest n (e.g. n = 1) externally resonant components can be amplified by kink-type plasma responses, particularly at high β. Low n plasma instabilities (e.g. resistive wall modes, neoclassical tearing modes) cause additional 3D magnetic perturbations in tokamak plasmas. Tearing modes in their nonlinear (Rutherford) regime bifurcate the topology and form magnetic islands. Finally, multiple resonant magnetic perturbations (RMPs) can, if not shielded by plasma rotation effects, cause local magnetic

Strongly perturbed Rydberg series originating from Kr II 4p45s ionic states

International Nuclear Information System (INIS)

Petrov, I.D.; Demekhin, P.V.; Lagutin, B.M.; Sukhorukov, V.L.; Kammer, S.; Mickat, S.; Schartner, K.-H.; Ehresmann, A.; Klumpp, S.; Werner, L.; Schmoranzer, H.

2004-01-01

Full text:Dispersed fluorescence excitation spectra for KrII fluorescence transitions to the 4p 4 5s 4 P 3/2 , 5/2 states were observed after excitation out of the KrI ground state with photons of energies between 28.4 eV and 28.7 eV and very narrow exciting-photon bandwidth of 1.7 meV. With this energy resolution it was possible to observe Rydberg series of doubly excited atomic states. The observed series were assigned to the states 4p 4 5s( 4 P 1/2 )np and 4p 4 5s( 2 P 3/2 )np ,based on calculations performed within theory taking into account interaction between many resonances and many continua. Calculated and measured cross sections are compared for the 4p - level (upper panel, ion yield) and for the 4p 4 5s 4 P 5/2 level (lower panel). An analysis of the computed photoionization (PI) cross sections shows that high - n members of Rydberg series are strongly perturbed by interaction with low - n ones of other series. In particular, the series shown are well pronounced because they borrow intensity from the low - n 4p 4 5s( 2 D 5/2 )6p 3/2 doublyexcited state. The above Rydberg series are predicted to be observable in photoelectron experiments, too. FIG. 1 shows, e.g., that members of the 4p 4 5s( 2 P 3/2 )np series starting from n 14 could also be observed in the 4p 4 5s 4P 1/2 observer channel at low photoelectron energies

Heavy baryon chiral perturbation theory and the spin 3/2 delta resonances

Energy Technology Data Exchange (ETDEWEB)

Kambor, J.

1996-12-31

Heavy baryon chiral perturbation theory is briefly reviewed, paying particular attention to the role of the spin 3/2 delta resonances. The concept of resonance saturation for the baryonic sector is critically discussed. Starting from a relativistic formulation of the pion-nucleon-delta system, the heavy baryon chiral Lagrangian including spin 3/2 resonances is constructed by means of a 1/m-expansion. The effective theory obtained admits a systematic expansion in terms of soft momenta, the pion mass M{sub {pi}} and the delta-nucleon mass difference {Delta}. (author). 22 refs.

Effect of Hydrotherapy on Static and Dynamic Balance in Older Adults: Comparison of Perturbed and Non-Perturbed Programs

Directory of Open Access Journals (Sweden)

Elham Azimzadeh

2013-01-01

Full Text Available Objectives: Falling is a main cause of mortality in elderly. Balance training exercises can help to prevent falls in older adults. According to the principle of specificity of training, the perturbation-based trainings are more similar to the real world. So these training programs can improve balance in elderly. Furthermore, exercising in an aquatic environment can reduce the limitations for balance training rather than a non-aquatic on. The aim of this study is comparing the effectiveness of perturbed and non-perturbed balance training programs in water on static and dynamic balance in aforementioned population group. Methods & Materials: 37 old women (age 80-65, were randomized to the following groups: perturbation-based training (n=12, non-perturbation-based training (n=12 and control (n=13 groups. Static and dynamic balance had been tested before and after the eight weeks of training by the postural stability test of the Biodex balance system using dynamic (level 4 and static platform. The data were analyzed by one sample paired t-test, Independent t-test and ANOVA. Results: There was a significant improvement for all indexes of static and dynamic balance in perturbation-based training (P<0.05. However, in non-perturbed group, all indexes were improved except ML (P<0.05. ANOVA showed that perturbed training was more effective than non-perturbed training on both static and dynamic balances. Conclusion: The findings confirmed the specificity principle of training. Although balance training can improve balance abilities, these kinds of trainings are not such specific for improving balance neuromuscular activities.The perturbation-based trainings can activate postural compensatory responses and reduce falling risk. According to results, we can conclude that hydrotherapy especially with perturbation-based programs will be useful for rehabilitation interventions in elderly .

Analysis on voltage oscillation of a mid-frequency series resonant inverter for DRMP coils on J-TEXT

Energy Technology Data Exchange (ETDEWEB)

Liu, Long-jian, E-mail: liulongjian001@yeah.net [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Yu, Ke-xun; Zhang, Ming; Nan, Jie-yin; Jiang, Guo-zhong; Rao, Bo; Li, Xuan [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2016-01-15

Highlights: • The reason of high-voltage oscillation of a series resonant inverter for DRMP coils is analyzed. • The condition or method for reduction of high-voltage oscillation is discussed. • The considerations of dead time and switch frequency for reduction of high-voltage oscillation are discussed. - Abstract: This paper deals with the voltage oscillation of an AC power supply for generating dynamic magnetic perturbation (DRMP) on J-TEXT. The power supply is a series resonant inverter with a matching transformer. It was noted that the high-voltage oscillation at transformer primary side is caused by an interaction between the line inductance and the stray capacitance of the matching transformer at switching transitions. In order to reduce the high-voltage oscillation and consider the requirement for soft-switching technique simultaneously, the switching frequency should be chosen properly by fine-tuning. The dead time should be chosen according to the relative size of minimum required dead time for protection and the optimal dead time.

Non-Perturbative Renormalization

CERN Document Server

Mastropietro, Vieri

2008-01-01

The notion of renormalization is at the core of several spectacular achievements of contemporary physics, and in the last years powerful techniques have been developed allowing to put renormalization on a firm mathematical basis. This book provides a self-consistent and accessible introduction to the sophisticated tools used in the modern theory of non-perturbative renormalization, allowing an unified and rigorous treatment of Quantum Field Theory, Statistical Physics and Condensed Matter models. In particular the first part of this book is devoted to Constructive Quantum Field Theory, providi

Numerical simulation of plasma response to externally applied resonant magnetic perturbation on the J-TEXT tokamak

Science.gov (United States)

Bicheng, LI; Zhonghe, JIANG; Jian, LV; Xiang, LI; Bo, RAO; Yonghua, DING

2018-05-01

Nonlinear magnetohydrodynamic (MHD) simulations of an equilibrium on the J-TEXT tokamak with applied resonant magnetic perturbations (RMPs) are performed with NIMROD (non-ideal MHD with rotation, open discussion). Numerical simulation of plasma response to RMPs has been developed to investigate magnetic topology, plasma density and rotation profile. The results indicate that the pure applied RMPs can stimulate 2/1 mode as well as 3/1 mode by the toroidal mode coupling, and finally change density profile by particle transport. At the same time, plasma rotation plays an important role during the entire evolution process.

Suppression of Runaway Electrons by Resonant Magnetic Perturbations in TEXTOR Disruptions

International Nuclear Information System (INIS)

Lehnen, M.; Bozhenkov, S. A.; Abdullaev, S. S.; TEXTOR Team,; Jakubowski, M. W.

2008-01-01

The generation of runaway electrons in the international fusion experiment ITER disruptions can lead to severe damage at plasma facing components. Massive gas injection might inhibit the generation process, but the amount of gas needed can affect, e.g., vacuum systems. Alternatively, magnetic perturbations can suppress runaway generation by increasing the loss rate. In TEXTOR disruptions runaway losses were enhanced by the application of resonant magnetic perturbations with toroidal mode number n=1 and n=2. The disruptions are initiated by fast injection of about 3x10 21 argon atoms, which leads to a reliable generation of runaway electrons. At sufficiently high perturbation levels a reduction of the runaway current, a shortening of the current plateau, and the suppression of high energetic runaways are observed. These findings indicate the suppression of the runaway avalanche during disruptions

Non-perturbative methods applied to multiphoton ionization

International Nuclear Information System (INIS)

Brandi, H.S.; Davidovich, L.; Zagury, N.

1982-09-01

The use of non-perturbative methods in the treatment of atomic ionization is discussed. Particular attention is given to schemes of the type proposed by Keldysh where multiphoton ionization and tunnel auto-ionization occur for high intensity fields. These methods are shown to correspond to a certain type of expansion of the T-matrix in the intra-atomic potential; in this manner a criterium concerning the range of application of these non-perturbative schemes is suggested. A brief comparison between the ionization rate of atoms in the presence of linearly and circularly polarized light is presented. (Author) [pt

Thoughts on non-perturbative thermalization and jet quenching in heavy ion collisions

International Nuclear Information System (INIS)

Kovchegov, Yuri V.

2006-01-01

We start by presenting physical arguments for the impossibility of perturbative thermalization leading to (non-viscous) Bjorken hydrodynamic description of heavy ion collisions. These arguments are complimentary to our more formal argument presented in [Yu.V. Kovchegov, hep-ph/0503038]. We argue that the success of hydrodynamic models in describing the quark-gluon system produced in heavy ion collisions could only be due to non-perturbative strong coupling effects. We continue by studying non-perturbative effects in heavy ion collisions at high energies. We model non-perturbative phenomena by an instanton ensemble. We show that non-perturbative instanton vacuum fields may significantly contribute to jet quenching in nuclear collisions. At the same time, the instanton ensemble contribution to thermalization is likely to be rather weak, leading to non-perturbative thermalization time comparable to the time of hadronization. This example illustrates that jet quenching is not necessarily a signal of a thermalized medium. Indeed, since the instanton models do not capture all the effects of QCD vacuum (e.g., they do not account for confinement), there may be other non-perturbative effects facilitating thermalization of the system

Analysis of series resonant converter with series-parallel connection

Science.gov (United States)

Lin, Bor-Ren; Huang, Chien-Lan

2011-02-01

In this study, a parallel inductor-inductor-capacitor (LLC) resonant converter series-connected on the primary side and parallel-connected on the secondary side is presented for server power supply systems. Based on series resonant behaviour, the power metal-oxide-semiconductor field-effect transistors are turned on at zero voltage switching and the rectifier diodes are turned off at zero current switching. Thus, the switching losses on the power semiconductors are reduced. In the proposed converter, the primary windings of the two LLC converters are connected in series. Thus, the two converters have the same primary currents to ensure that they can supply the balance load current. On the output side, two LLC converters are connected in parallel to share the load current and to reduce the current stress on the secondary windings and the rectifier diodes. In this article, the principle of operation, steady-state analysis and design considerations of the proposed converter are provided and discussed. Experiments with a laboratory prototype with a 24 V/21 A output for server power supply were performed to verify the effectiveness of the proposed converter.

Resonant interaction of energetic ions with Alfven-like perturbations in stellarators

International Nuclear Information System (INIS)

Karulin, N.; Wobig, H.

1994-04-01

The modification of passing guiding center orbits of 3.5 MeV alpha particles and 45 keV protons in the presence of global Alfven eigenmodes (GAE's) is studied in modular advanced stellarators. It is found that if resonances between particles and waves occur, drift surfaces form a set of island structures. The mode numbers of the perturbations, which are dangerous for the energetic particle confinement, are discussed for two particular stellarators (Helias reactor and Wendelstein 7-AS). The perturbation amplitudes corresponding to the onset of orbit stochasticity are studied numerically. The coefficient of the collisionless stochastic diffusion is estimated using the island width derived analytically. (orig.)

A non-perturbative operator product expansion

International Nuclear Information System (INIS)

Bietenholz, W.; Cundy, N.; Goeckeler, M.

2009-10-01

Nucleon structure functions can be observed in Deep Inelastic Scattering experiments, but it is an outstanding challenge to confront them with fully non-perturbative QCD results. For this purpose we investigate the product of electromagnetic currents (with large photonmomenta) between quark states (of low momenta). By means of an Operator Product Expansion the structure function can be decomposed into matrix elements of local operators, and Wilson coefficients. For consistency both have to be computed non-perturbatively. Here we present precision results for a set of Wilson coefficients. They are evaluated from propagators for numerous quark momenta on the lattice, where the use of chiral fermions suppresses undesired operator mixing. This overdetermines the Wilson coefficients, but reliable results can be extracted by means of a Singular Value Decomposition. (orig.)

Toroidal modeling of plasma response and resonant magnetic perturbation field penetration

Czech Academy of Sciences Publication Activity Database

Liu, Y.Q.; Kirk, A.; Sun, Y.; Cahyna, Pavel; Chapman, I.T.; Denner, P.; Fishpool, G.; Garofalo, A.M.; Harrison, J.R.; Nardon, E.

2012-01-01

Roč. 54, č. 12 (2012), s. 124013-124013 ISSN 0741-3335 Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamak * resonant magnetic perturbation * neoclassical toroidal viscosity Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.369, year: 2012 http://iopscience.iop.org/0741-3335/54/12/124013/pdf/0741-3335_54_12_124013.pdf

Spectral zeta function and non-perturbative effects in ABJM Fermi-gas

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki

2015-03-01

The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of ''non-perturbative'' poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example associated with a spectral problem in topological string theory. A conjectured non-perturbative free energy on the resolved conifold is successfully reproduced in this framework.

On equivalence of high temperature series expansion and coupling parameter series expansion in thermodynamic perturbation theory of fluids

International Nuclear Information System (INIS)

Sai Venkata Ramana, A.

2014-01-01

The coupling parameter series expansion and the high temperature series expansion in the thermodynamic perturbation theory of fluids are shown to be equivalent if the interaction potential is pairwise additive. As a consequence, for the class of fluids with the potential having a hardcore repulsion, if the hard-sphere fluid is chosen as reference system, the terms of coupling parameter series expansion for radial distribution function, direct correlation function, and Helmholtz free energy follow a scaling law with temperature. The scaling law is confirmed by application to square-well fluids

Importance of Plasma Response to Non-axisymmetric Perturbations in Tokamaks

International Nuclear Information System (INIS)

Park, Jong-kyu; Boozer, Allen H.; Menard, Jonathan E.; Garofalo, Andrea M.; Schaffer, Michael J.; Hawryluk, Richard J.; Kaye, Stanley M.; Gerhardt, Stefan P.; Sabbagh, Steve A. and the NSTX Team

2009-01-01

Tokamaks are sensitive to deviations from axisymmetry as small as (delta)B/B 0 ∼ 10 -4 . These non-axisymmetric perturbations greatly modify plasma confinement and performance by either destroying magnetic surfaces with subsequent locking or deforming magnetic surfaces with associated non-ambipolar transport. The Ideal Perturbed Equilibrium Code (IPEC) calculates ideal perturbed equilibria and provides important basis for understanding the sensitivity of tokamak plasmas to perturbations. IPEC calculations indicate that the ideal plasma response, or equivalently the effect by ideally perturbed plasma currents, is essential to explain locking experiments on National Spherical Torus eXperiment (NSTX) and DIII-D. The ideal plasma response is also important for Neoclassical Toroidal Viscosity (NTV) in non-ambipolar transport. The consistency between NTV theory and magnetic braking experiments on NSTX and DIII-D can be improved when the variation in the field strength in IPEC is coupled with generalized NTV theory. These plasma response effects will be compared with the previous vacuum superpositions to illustrate the importance. However, plasma response based on ideal perturbed equilibria is still not sufficiently accurate to predict the details of NTV transport, and can be inconsistent when currents associated with a toroidal torque become comparable to ideal perturbed currents

Non-perturbative heavy quark effective theory. Introduction and status

International Nuclear Information System (INIS)

Sommer, Rainer; Humboldt-Universitaet, Berlin

2015-01-01

We give an introduction to Heavy Quark Effective Theory (HQET). Our emphasis is on its formulation non-perturbative in the strong coupling, including the non-perturbative determination of the parameters in the HQET Lagrangian. In a second part we review the present status of HQET on the lattice, largely based on work of the ALPHA collaboration in the last few years. We finally discuss opportunities and challenges.

Non-perturbative QCD Effect on K-Factor of Drell-Yan Process

International Nuclear Information System (INIS)

Hou Zhaoyu; Zhi Haisu; Chen Junxiao

2006-01-01

By using a non-perturbative quark propagator with the lowest-dimensional condensate contributions from the QCD vacuum, the non-perturbative effect to K-factor of the Drell-Yan process is numerically investigated for 12 6 C- 12 6 C collision at the center-of-mass energy (s) 1/2 = 200 GeV, 630 GeV respectively. Calculated results show that the non-perturbative QCD effect has just a weak influence on K-factor in the two cases.

Perturbative analysis of non-Abelian Aharonov-Bohm scattering

International Nuclear Information System (INIS)

Bak, D.; Bergman, O.

1995-01-01

We perform a perturbative analysis of the non-Abelian Aharonov-Bohm problem to one loop in the framework of a local field theory, and show the necessity of contact interactions for renormalizability of perturbation theory. Moreover at critical values of the contact interaction strength the theory is finite and preserves classical conformal invariance

Transformer induced instability of the series resonant converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1983-01-01

It is shown that the common series resonant power converter is subject to a low frequency oscillation that can lead to the loss of cyclic stability. This oscillation is caused by a low frequency resonant circuit formed by the normal L and C components in series with the magnetizing inductance of the output transformer. Three methods for eliminating this oscillation are presented and analyzed. One of these methods requires a change in the circuit topology during the resonance cycle. This requires a new set of steady state equations which are derived and presented in a normalized form. Experimental results are included which demonstrate the nature of the low frequency oscillation before cyclic stability is lost.

Fast response double series resonant high-voltage DC-DC converter

International Nuclear Information System (INIS)

Lee, S S; Iqbal, S; Kamarol, M

2012-01-01

In this paper, a novel double series resonant high-voltage dc-dc converter with dual-mode pulse frequency modulation (PFM) control scheme is proposed. The proposed topology consists of two series resonant tanks and hence two resonant currents flow in each switching period. Moreover, it consists of two high-voltage transformer with the leakage inductances are absorbed as resonant inductor in the series resonant tanks. The secondary output of both transformers are rectified and mixed before supplying to load. In the resonant mode operation, the series resonant tanks are energized alternately by controlling two Insulated Gate Bipolar Transistor (IGBT) switches with pulse frequency modulation (PFM). This topology operates in discontinuous conduction mode (DCM) with all IGBT switches operating in zero current switching (ZCS) condition and hence no switching loss occurs. To achieve fast rise in output voltage, a dual-mode PFM control during start-up of the converter is proposed. In this operation, the inverter is started at a high switching frequency and as the output voltage reaches 90% of the target value, the switching frequency is reduced to a value which corresponds to the target output voltage. This can effectively reduce the rise time of the output voltage and prevent overshoot. Experimental results collected from a 100-W laboratory prototype are presented to verify the effectiveness of the proposed system.

Analytic-continuation approach to the resummation of divergent series in Rayleigh-Schrödinger perturbation theory

Science.gov (United States)

Mihálka, Zsuzsanna É.; Surján, Péter R.

2017-12-01

The method of analytic continuation is applied to estimate eigenvalues of linear operators from finite order results of perturbation theory even in cases when the latter is divergent. Given a finite number of terms E(k ),k =1 ,2 ,⋯M resulting from a Rayleigh-Schrödinger perturbation calculation, scaling these numbers by μk (μ being the perturbation parameter) we form the sum E (μ ) =∑kμkE(k ) for small μ values for which the finite series is convergent to a certain numerical accuracy. Extrapolating the function E (μ ) to μ =1 yields an estimation of the exact solution of the problem. For divergent series, this procedure may serve as resummation tool provided the perturbation problem has a nonzero radius of convergence. As illustrations, we treat the anharmonic (quartic) oscillator and an example from the many-electron correlation problem.

Edge localized modes control by resonant magnetic perturbations; Controle des instabilites de bord par perturbations magnetiques resonantes

Energy Technology Data Exchange (ETDEWEB)

Nardon, E

2007-10-15

The present work is dedicated to one of the most promising methods of control of the ELMs (Edge Localized Modes), based on a system of coils producing Resonant Magnetic Perturbations (RMPs). Our main objectives are, on the one hand, to improve the physical understanding of the mechanisms at play, and on the other hand to propose a concrete design of ELMs control coils for ITER. In order to calculate and analyze the magnetic perturbations produced by a given set of coils, we have developed the ERGOS code. The first ERGOS calculation was for the DIII-D ELMs control coils, the I-coils. It showed that they produce magnetic islands chains which overlap at the edge of the plasma, resulting in the ergodization of the magnetic field. We have then used ERGOS for the modelling of the experiments on ELMs control using the error field correction coils at JET and MAST. In the case of JET, we have shown the existence of a correlation between the mitigation of the ELMs and the ergodization of the magnetic field at the edge, in agreement with the DIII-D result. In order to design the ELMs control coils for ITER we have used ERGOS intensively, taking the case of the DIII-D I-coils as a reference. Three candidate designs came out, which we presented at the ITER Design Review, in 2007. Recently, the ITER management decided to provide a budget for building ELMs control coils, the design of which remains to be chosen between two of the three options that we proposed. Finally, in order to understand better the non-linear magnetohydrodynamics phenomena taking place in ELMs control by RMPs, we performed numerical simulations, in particular with the JOREK code for a DIII-D case. The simulations reveal the existence of convection cells induced at the edge by the magnetic perturbations, and the possible screening of the RMPs in presence of rotation.

Non-perturbative power corrections to ghost and gluon propagators

International Nuclear Information System (INIS)

Boucaud, Philippe; Leroy, Jean-Pierre; Yaouanc, Alain Le; Lokhov, Alexey; Micheli, Jacques; Pene, Olivier; RodrIguez-Quintero, Jose; Roiesnel, Claude

2006-01-01

We study the dominant non-perturbative power corrections to the ghost and gluon propagators in Landau gauge pure Yang-Mills theory using OPE and lattice simulations. The leading order Wilson coefficients are proven to be the same for both propagators. The ratio of the ghost and gluon propagators is thus free from this dominant power correction. Indeed, a purely perturbative fit of this ratio gives smaller value ( ≅ 270MeV) of Λ M-barS-bar than the one obtained from the propagators separately( ≅ 320MeV). This argues in favour of significant non-perturbative ∼ 1/q 2 power corrections in the ghost and gluon propagators. We check the self-consistency of the method

Introduction and overview to some topics in perturbative QCD and their relationship to non perturbative effects

International Nuclear Information System (INIS)

West, G.

1990-01-01

The main thrust of this talk is to review and discuss various topics in both perturbative and non-perturbative QCD that are, by and large, model independent. This inevitably means that we shall rely heavily on the renormalization group and asymptotic freedom. Although this usually means that one has to concentrate on high energy phenomena, there are some physical processes even involving bound states which are certainly highly non-perturbative, where one can make some progress without becoming overly model independent. Experience with the EMC effect, where there are about as many ''explanations'' as authors, has surely taught us that it may well be worth returning to ''basics'' and thinking about general properties of QCD rather than guessing, essentially arbitrarily, what we think is its low energy structure. No doubt we shall have to await further numerical progress or for some inspired theoretical insight before we can, with confidence, attack these extremely difficult problems. So, with this in mine, I shall review a smattering of problems which do have a non-perturbative component and where some rather modest progress can actually be made; I emphasize the adjective ''modest''exclamation point

Generalized perturbation series

International Nuclear Information System (INIS)

Baird, L.C.; Stinchcomb, G.

1973-01-01

An approximate solution of the Green's function equation may be used to generate an exact solution of the Schroedinger equation. This is accomplished through an iterative procedure. The procedure is equivalent to a perturbation expansion if the approximate Green's function is exact with respect to some reference potential

Effects of resonant magnetic perturbation on the triggering and the evolution of double-tearing mode

Science.gov (United States)

Wang, L.; Lin, W. B.; Wang, X. Q.

2018-02-01

The effects of resonant magnetic perturbation on the triggering and the evolution of the double-tearing mode are investigated by using nonlinear magnetohydrodynamics simulations in a slab geometry. It is found that the double-tearing mode can be destabilized by boundary magnetic perturbation. Moreover, the mode has three typical development stages before it reaches saturation: the linear stable stage, the linear-growth stage, and the exponential-growth stage. The onset and growth of the double-tearing mode significantly depend on the boundary magnetic perturbations, particularly in the early development stage of the mode. The influences of the magnetic perturbation amplitude on the mode for different separations of the two rational surfaces are also discussed.

Implications of perturbative unitarity for scalar di-boson resonance searches at LHC

CERN Document Server

Di Luzio, Luca; Nardecchia, Marco

2017-01-01

We study the constraints implied by partial wave unitarity on new physics models explaining the LHC di-photon excess at 750 GeV. We argue that the effective description in terms of the SM supplemented by a single scalar resonance breaks down at scales of few tens of TeV, where perturbative unitarity is violated due to the large cross-section required in order to fit the $\\gamma\\gamma$ signal. Likewise, we use unitarity arguments in order to set perturbativity bounds on renormalizable UV completions of the EFT description. We finally discuss under which conditions the data can be accommodated within weakly-coupled models.

Non-perturbative Heavy Quark Effective Theory

DEFF Research Database (Denmark)

Della Morte, Michele; Heitger, Jochen; Simma, Hubert

2015-01-01

We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m_h-corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B...

Non-perturbative quark mass renormalization

CERN Document Server

Capitani, S.; Luescher, M.; Sint, S.; Sommer, R.; Weisz, P.; Wittig, H.

1998-01-01

We show that the renormalization factor relating the renormalization group invariant quark masses to the bare quark masses computed in lattice QCD can be determined non-perturbatively. The calculation is based on an extension of a finite-size technique previously employed to compute the running coupling in quenched QCD. As a by-product we obtain the $\\Lambda$--parameter in this theory with completely controlled errors.

A stochastic perturbation theory for non-autonomous systems

Energy Technology Data Exchange (ETDEWEB)

Moon, W., E-mail: wm275@damtp.cam.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Wettlaufer, J. S., E-mail: wettlaufer@maths.ox.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom)

2013-12-15

We develop a perturbation theory for a class of first order nonlinear non-autonomous stochastic ordinary differential equations that arise in climate physics. The perturbative procedure produces moments in terms of integral delay equations, whose order by order decay is characterized in a Floquet-like sense. Both additive and multiplicative sources of noise are discussed and the question of how the nature of the noise influences the results is addressed theoretically and numerically. By invoking the Martingale property, we rationalize the transformation of the underlying Stratonovich form of the model to an Ito form, independent of whether the noise is additive or multiplicative. The generality of the analysis is demonstrated by developing it both for a Brownian particle moving in a periodically forced quartic potential, which acts as a simple model of stochastic resonance, as well as for our more complex climate physics model. The validity of the approach is shown by comparison with numerical solutions. The particular climate dynamics problem upon which we focus involves a low-order model for the evolution of Arctic sea ice under the influence of increasing greenhouse gas forcing ΔF{sub 0}. The deterministic model, developed by Eisenman and Wettlaufer [“Nonlinear threshold behavior during the loss of Arctic sea ice,” Proc. Natl. Acad. Sci. U.S.A. 106(1), 28–32 (2009)] exhibits several transitions as ΔF{sub 0} increases and the stochastic analysis is used to understand the manner in which noise influences these transitions and the stability of the system.

Hybrid perturbation methods based on statistical time series models

Science.gov (United States)

San-Juan, Juan Félix; San-Martín, Montserrat; Pérez, Iván; López, Rosario

2016-04-01

In this work we present a new methodology for orbit propagation, the hybrid perturbation theory, based on the combination of an integration method and a prediction technique. The former, which can be a numerical, analytical or semianalytical theory, generates an initial approximation that contains some inaccuracies derived from the fact that, in order to simplify the expressions and subsequent computations, not all the involved forces are taken into account and only low-order terms are considered, not to mention the fact that mathematical models of perturbations not always reproduce physical phenomena with absolute precision. The prediction technique, which can be based on either statistical time series models or computational intelligence methods, is aimed at modelling and reproducing missing dynamics in the previously integrated approximation. This combination results in the precision improvement of conventional numerical, analytical and semianalytical theories for determining the position and velocity of any artificial satellite or space debris object. In order to validate this methodology, we present a family of three hybrid orbit propagators formed by the combination of three different orders of approximation of an analytical theory and a statistical time series model, and analyse their capability to process the effect produced by the flattening of the Earth. The three considered analytical components are the integration of the Kepler problem, a first-order and a second-order analytical theories, whereas the prediction technique is the same in the three cases, namely an additive Holt-Winters method.

A large-signal dynamic simulation for the series resonant converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1983-01-01

A simple nonlinear discrete-time dynamic model for the series resonant dc-dc converter is derived using approximations appropriate to most power converters. This model is useful for the dynamic simulation of a series resonant converter using only a desktop calculator. The model is compared with a laboratory converter for a large transient event.

Edge localized mode control by resonant magnetic perturbations in tokamak plasmas

International Nuclear Information System (INIS)

Orain, Francois

2014-01-01

The growth of plasma instabilities called Edge Localized Modes (ELMs) in tokamaks results in the quasi-periodic relaxation of the edge pressure profile. These relaxations induce large heat fluxes which might be harmful for the divertor in ITER, thus ELM control is mandatory in ITER. One of the promising control methods planned in ITER is the application of external resonant magnetic perturbations (RMPs), already efficient for ELM mitigation/suppression in current tokamak experiments. However a better understanding of the interaction between ELMs, RMPs and plasma flows is needed to explain the experimental results and make reliable predictions for ITER. In this perspective, non-linear modeling of ELMs and RMPs is done with the reduced MHD code JOREK, in toroidal geometry including the X-point and the Scrape-Off Layer. The initial model has been further developed to describe self-consistent plasma flows - with the addition of the bi-fluid diamagnetic drifts, the neoclassical friction and a source of parallel rotation - and to simulate the RMP penetration consistently with the plasma response. As a first step, the plasma response to RMPs (without ELMs) is studied for JET, MAST and ITER realistic plasma parameters and geometry. The general behaviour of the plasma/RMP interaction is similar for the three studied cases: RMPs are generally screened by the formation of response currents, induced by the plasma rotation on the resonant surfaces. RMPs however penetrate at the very edge where an ergodic zone is formed. The amplification of the non-resonant spectrum of the magnetic perturbations is also observed in the core. The edge ergodization induces an enhanced transport at the edge, which slightly degrades the pedestal profiles. RMPs also generate the 3D-deformation of the plasma boundary with a maximum deformation near the X-point where lobe structures are formed. Then the full dynamics of a multi-ELM cycle (without RMPs) is modeled for the first time in realistic

Wilson loops to 20th order numerical stochastic perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics; Hotzel, G.; Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Ilgenfritz, E.M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Joint Institute for Nuclear Research, VBLHEP, Dubna (Russian Federation); Millo, R.; Rakow, P.E.L. [Liverpool Univ. (Germany). Theoretical Physics Div.; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Kobe, Hyogo (Japan); Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-05-15

We calculate Wilson loops of various sizes up to 20 loops in SU(3) pure lattice gauge theory at different lattice sizes for Wilson gauge action using the technique of numerical stochastic perturbation theory. This allows us to investigate the perturbative series for various Wilson loops at high loop orders. We observe differences in the behavior of those series as function of the loop order. Up to n=20 we do not find evidence for the factorial growth of the expansion coefficients often assumed to characterize an asymptotic series. Based on the actually observed behavior we sum the series in a model parametrized by hypergeometric functions. Alternatively we estimate the total series in boosted perturbation theory using information from the first 14 loops. We introduce generalized ratios of Wilson loops of different sizes. Together with the corresponding Wilson loops from standard Monte Carlo measurements they enable us to assess their non-perturbative parts.

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

International Nuclear Information System (INIS)

Pankin, Alexei Y.; Kritz, Arnold H.

2011-01-01

Topics covered are: anomalous transport and E f- B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects

Energy Technology Data Exchange (ETDEWEB)

Pankin, Alexei Y.; Kritz, Arnold H.

2011-07-19

Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

The power of perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Serone, Marco [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Spada, Gabriele [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Villadoro, Giovanni [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)

2017-05-10

We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the Picard-Lefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented.

Cosmological perturbations in non-local higher-derivative gravity

International Nuclear Information System (INIS)

Craps, Ben; Jonckheere, Tim De; Koshelev, Alexey S.

2014-01-01

We study cosmological perturbations in a non-local higher-derivative model of gravity introduced by Biswas, Mazumdar and Siegel. We extend previous work, which had focused on classical scalar perturbations around a cosine hyperbolic bounce solution, in three ways. First, we point out the existence of a Starobinsky solution in this model, which is more attractive from a phenomenological point of view (even though it has no bounce). Second, we study classical vector and tensor pertuxsxrbations. Third, we show how to quantize scalar and tensor perturbations in a de Sitter phase (for choices of parameters such that the model is ghost-free). Our results show that the model is well-behaved at this level, and are very similar to corresponding results in local f(R) models. In particular, for the Starobinsky solution of non-local higher-derivative gravity, we find the same tensor-to-scalar ratio as for the conventional Starobinsky model

Using a Combination of FEM and Perturbation Method in Frequency Split Calculation of a Nearly Axisymmetric Shell with Middle Surface Shape Defect

Directory of Open Access Journals (Sweden)

D. S. Vakhlyarskiy

2016-01-01

Full Text Available This paper proposes a method to calculate the splitting of natural frequency of the shell of hemispherical resonator gyro. (HRG. The paper considers splitting that arises from the small defect of the middle surface, which makes the resonator different from the rotary shell. The presented method is a combination of the perturbation method and the finite element method. The method allows us to find the frequency splitting caused by defects in shape, arbitrary distributed in the circumferential direction. This is achieved by calculating the perturbations of multiple natural frequencies of the second and higher orders. The proposed method allows us to calculate the splitting of multiple frequencies for the shell with the meridian of arbitrary shape.A developed finite element is an annular element of the shell and has two nodes. Projections of movements are used on the axis of the global cylindrical system of coordinates, as the unknown. To approximate the movements are used polynomials of the second degree. Within the finite element the geometric characteristics are arranged in a series according to the small parameter of perturbations of the middle surface geometry.Movements on the final element are arranged in series according to the small parameter, and in a series according to circumferential angle. With computer used to implement the method, three-dimensional arrays are used to store the perturbed quantities. This allows the use of regular expressions for the mass and stiffness matrices, when building the finite element, instead of analytic dependencies for each perturbation of these matrices of the required order with desirable mathematical operations redefined in accordance with the perturbation method.As a test task, is calculated frequency splitting of non-circular cylindrical resonator with Navier boundary conditions. The discrepancy between the results and semi-analytic solution to this problem is less than 1%. For a cylindrical shell is

Perturbation approach to the self-energy of non-S hydrogenic states

International Nuclear Information System (INIS)

Le Bigot, Eric-Olivier; Jentschura, Ulrich D.; Mohr, Peter J.; Indelicato, Paul; Soff, Gerhard

2003-01-01

We present results on the self-energy correction to the energy levels of hydrogen and hydrogenlike ions. The self-energy represents the largest QED correction to the relativistic (Dirac-Coulomb) energy of a bound electron. We focus on the perturbation expansion of the self-energy of non-S states, and provide estimates of the so-called A 60 perturbation coefficient, which can be viewed as a relativistic Bethe logarithm. Precise values of A 60 are given for many P, D, F, and G states, while estimates are given for other states. These results can be used in high-precision spectroscopy experiments in hydrogen and hydrogenlike ions. They yield the best available estimate of the self-energy correction of many atomic states

Pion-nucleon scattering in covariant baryon chiral perturbation theory with explicit Delta resonances

Energy Technology Data Exchange (ETDEWEB)

Yao, De-Liang [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Siemens, D. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Bernard, V. [Groupe de Physique Théorique, Institut de Physique Nucléaire, UMR 8606,CNRS, University Paris-Sud, Université Paris-Saclay, 91405 Orsay Cedex (France); Epelbaum, E. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Gasparyan, A.M. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); SSC RF ITEP, Bolshaya Cheremushkinskaya 25, 117218 Moscow (Russian Federation); Gegelia, J. [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany); Tbilisi State University, 0186 Tbilisi (Georgia); Krebs, H. [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Meißner, Ulf-G. [Helmholtz Institut für Strahlen- und Kernphysik andBethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics,Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-05-05

We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz invariant formulation of baryon chiral perturbation theory using dimensional regularization and the extended on-mass-shell renormalization scheme. In the delta resonance sector, the on mass-shell renormalization is realized as a complex-mass scheme. By fitting the low-energy constants of the effective Lagrangian to the S- and P-partial waves a satisfactory description of the phase shifts from the analysis of the Roy-Steiner equations is obtained. We predict the phase shifts for the D and F waves and compare them with the results of the analysis of the George Washington University group. The threshold parameters are calculated both in the delta-less and delta-full cases. Based on the determined low-energy constants, we discuss the pion-nucleon sigma term. Additionally, in order to determine the strangeness content of the nucleon, we calculate the octet baryon masses in the presence of decuplet resonances up to next-to-next-to-leading order in SU(3) baryon chiral perturbation theory. The octet baryon sigma terms are predicted as a byproduct of this calculation.

Introduction to non-perturbative heavy quark effective theory

International Nuclear Information System (INIS)

Sommer, R.

2010-08-01

My lectures on the effective field theory for heavy quarks, an expansion around the static limit, concentrate on the motivation and formulation of HQET, its renormalization and discretization. This provides the basis for understanding that and how this effective theory can be formulated fully non-perturbatively in the QCD coupling, while by the very nature of an effective field theory, it is perturbative in the expansion parameter 1/m. After the couplings in the effective theory have been determined, the result at a certain order in 1/m is unique up to higher order terms in 1/m. In particular the continuum limit of the lattice regularized theory exists and leaves no trace of how it was regularized. In other words, the theory yields an asymptotic expansion of the QCD observables in 1/m - as usual in a quantum field theory modified by powers of logarithms. None of these properties has been shown rigorously (e.g. to all orders in perturbation theory) but perturbative computations and recently also non-perturbative lattice results give strong support to this ''standard wisdom''. A subtle issue is that a theoretically consistent formulation of the theory is only possible through a non-perturbative matching of its parameters with QCD at finite values of 1/m. As a consequence one finds immediately that the splitting of a result for a certain observable into, for example, lowest order and first order is ambiguous. Depending on how the matching between effective theory and QCD is done, a first order contribution may vanish and appear instead in the lowest order. For example, the often cited phenomenological HQET parameters anti Λ and λ 1 lack a unique non-perturbative definition. But this does not affect the precision of the asymptotic expansion in 1/m. The final result for an observable is correct up to order (1/m) n+1 if the theory was treated including (1/m) n terms. Clearly, the weakest point of HQET is that it intrinsically is an expansion. In practise, carrying it

Non-perturbative improvement of stout-smeared three flavour clover fermions

Energy Technology Data Exchange (ETDEWEB)

Cundy, N.; Goeckeler, M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, R. [Edinburgh Univ. (GB). School of Physics and Astronomy] (and others)

2009-01-15

We discuss a 3-flavour lattice QCD action with clover improvement in which the fermion matrix has single level stout smearing for the hopping terms together with unsmeared links for the clover term. With the (tree-level) Symanzik improved gluon action this constitutes the Stout Link Non-perturbative Clover or SLiNC action. To cancel O(a) terms the clover term coefficient has to be tuned. We present here results of a non-perturbative determination of this coefficient using the Schroedinger functional and as a by-product a determination of the critical hopping parameter. Comparisons of the results are made with lowest order perturbation theory. (orig.)

Detection of perturbation phases and developmental stages in organisms from DNA microarray time series data.

Directory of Open Access Journals (Sweden)

Marianne Rooman

Full Text Available Available DNA microarray time series that record gene expression along the developmental stages of multicellular eukaryotes, or in unicellular organisms subject to external perturbations such as stress and diauxie, are analyzed. By pairwise comparison of the gene expression profiles on the basis of a translation-invariant and scale-invariant distance measure corresponding to least-rectangle regression, it is shown that peaks in the average distance values are noticeable and are localized around specific time points. These points systematically coincide with the transition points between developmental phases or just follow the external perturbations. This approach can thus be used to identify automatically, from microarray time series alone, the presence of external perturbations or the succession of developmental stages in arbitrary cell systems. Moreover, our results show that there is a striking similarity between the gene expression responses to these a priori very different phenomena. In contrast, the cell cycle does not involve a perturbation-like phase, but rather continuous gene expression remodeling. Similar analyses were conducted using three other standard distance measures, showing that the one we introduced was superior. Based on these findings, we set up an adapted clustering method that uses this distance measure and classifies the genes on the basis of their expression profiles within each developmental stage or between perturbation phases.

Effect of Ambipolar Plasma Flow on the Penetration of Resonant Magnetic Perturbations in a Quasi-axisymmetric Stellarator

International Nuclear Information System (INIS)

Reiman, A.; Zarnstorff, M.; Mikkelsen, D.; Owen, L.; Mynick, H.; Hudson, S.; Monticello, D.

2005-01-01

A reference equilibrium for the U.S. National Compact Stellarator Experiment is predicted to be sufficiently close to quasi-symmetry to allow the plasma to flow in the toroidal direction with little viscous damping, yet to have sufficiently large deviations from quasi-symmetry that nonambipolarity significantly affects the physics of the shielding of resonant magnetic perturbations by plasma flow. The unperturbed velocity profile is modified by the presence of an ambipolar potential, which produces a broad velocity profile. In the presence of a resonant magnetic field perturbation, nonambipolar transport produces a radial current, and the resulting j x B force resists departures from the ambipolar velocity and enhances the shielding

Hypergeometric continuation of divergent perturbation series: II. Comparison with Shanks transformation and Padé approximation

International Nuclear Information System (INIS)

Sanders, Sören; Holthaus, Martin

2017-01-01

We explore in detail how analytic continuation of divergent perturbation series by generalized hypergeometric functions is achieved in practice. Using the example of strong-coupling perturbation series provided by the two-dimensional Bose–Hubbard model, we compare hypergeometric continuation to Shanks and Padé techniques, and demonstrate that the former yields a powerful, efficient and reliable alternative for computing the phase diagram of the Mott insulator-to-superfluid transition. In contrast to Shanks transformations and Padé approximations, hypergeometric continuation also allows us to determine the exponents which characterize the divergence of correlation functions at the transition points. Therefore, hypergeometric continuation constitutes a promising tool for the study of quantum phase transitions. (paper)

Hypergeometric continuation of divergent perturbation series: II. Comparison with Shanks transformation and Padé approximation

Science.gov (United States)

Sanders, Sören; Holthaus, Martin

2017-11-01

We explore in detail how analytic continuation of divergent perturbation series by generalized hypergeometric functions is achieved in practice. Using the example of strong-coupling perturbation series provided by the two-dimensional Bose-Hubbard model, we compare hypergeometric continuation to Shanks and Padé techniques, and demonstrate that the former yields a powerful, efficient and reliable alternative for computing the phase diagram of the Mott insulator-to-superfluid transition. In contrast to Shanks transformations and Padé approximations, hypergeometric continuation also allows us to determine the exponents which characterize the divergence of correlation functions at the transition points. Therefore, hypergeometric continuation constitutes a promising tool for the study of quantum phase transitions.

Resonant magnetic perturbations and edge ergodization on the COMPASS tokamak

Czech Academy of Sciences Publication Activity Database

Cahyna, Pavel; Bécoulet, M.; Pánek, Radomír; Fuchs, Vladimír; Nardon, E.; Krlín, Ladislav

2008-01-01

Roč. 34, č. 4 (2008), s. 746-749 ISSN 1063-780X. [Workshop on Electric Fields, Structures, and Relaxation in Plasmas/10th./. Varšava, 8.7.2007-9.7.2007] R&D Projects: GA AV ČR IAA100430502; GA AV ČR KJB100430602 Institutional research plan: CEZ:AV0Z20430508 Keywords : ELM mitigation * saddle coils * resonant magnetic perturbations Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.785, year: 2008 http://dx.doi.org/10.1134/S1063780X08090080

Calculation, normalization and perturbation of quasinormal modes in coupled cavity-waveguide systems

DEFF Research Database (Denmark)

Kristensen, Philip Trøst; de Lasson, Jakob Rosenkrantz; Gregersen, Niels

2014-01-01

of divergent series to provide a framework for modeling of optical phenomena in such coupled cavity-waveguide systems. As an example, we apply the framework to study perturbative changes in the resonance frequency and Q value of a photonic crystal cavity coupled to a defect waveguide....

Multiphoton transitions in semiconductors in the non-perturbative approach

International Nuclear Information System (INIS)

Iqbal, M.Z.; Hassan, A.R.

1987-09-01

Transition rates for multiphoton absorption via direct band-to-band excitation have been calculated using a non-perturbative approach due to Jones and Reiss, based on the Volkov type final state wave functions. Both cases of parabolic and non-parabolic energy bands have been included in our calculations. Absorption coefficients have been obtained for the cases of plane polarized and circularly polarized light. In particular, two-photon absorption coefficients are derived for the two cases of polarization for the parabolic band approximation as well as for non-parabolic bands and compared with the results based on perturbation theory. Numerical estimates of the two photon absorption coefficients resulting from our calculations are also provided. (author). 10 refs, 1 tab

Introduction to non-perturbative heavy quark effective theory

Energy Technology Data Exchange (ETDEWEB)

Sommer, R. [DESY, Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2010-08-15

My lectures on the effective field theory for heavy quarks, an expansion around the static limit, concentrate on the motivation and formulation of HQET, its renormalization and discretization. This provides the basis for understanding that and how this effective theory can be formulated fully non-perturbatively in the QCD coupling, while by the very nature of an effective field theory, it is perturbative in the expansion parameter 1/m. After the couplings in the effective theory have been determined, the result at a certain order in 1/m is unique up to higher order terms in 1/m. In particular the continuum limit of the lattice regularized theory exists and leaves no trace of how it was regularized. In other words, the theory yields an asymptotic expansion of the QCD observables in 1/m - as usual in a quantum field theory modified by powers of logarithms. None of these properties has been shown rigorously (e.g. to all orders in perturbation theory) but perturbative computations and recently also non-perturbative lattice results give strong support to this ''standard wisdom''. A subtle issue is that a theoretically consistent formulation of the theory is only possible through a non-perturbative matching of its parameters with QCD at finite values of 1/m. As a consequence one finds immediately that the splitting of a result for a certain observable into, for example, lowest order and first order is ambiguous. Depending on how the matching between effective theory and QCD is done, a first order contribution may vanish and appear instead in the lowest order. For example, the often cited phenomenological HQET parameters anti {lambda} and {lambda}{sub 1} lack a unique non-perturbative definition. But this does not affect the precision of the asymptotic expansion in 1/m. The final result for an observable is correct up to order (1/m){sup n+1} if the theory was treated including (1/m){sup n} terms. Clearly, the weakest point of HQET is that it

Influence of external resonant magnetic perturbation field on edge plasma of small tokamak HYBTOK-II

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Y., E-mail: hayashi-yuki13@ees.nagoya-u.ac.jp [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Suzuki, Y.; Ohno, N. [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Okamoto, M. [Ishikawa National College of Technology, Kitachujo, Tsubata-cho, Kahoku-gun, Ishikawa 929-0392 (Japan); Kikuchi, Y. [University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Sakakibara, S.; Watanabe, K.; Takemura, Y. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan)

2015-08-15

Radial profile of externally applied resonant magnetic perturbation (RMP) field with mode numbers of m = 6 and n = 2 in a small tokamak device HYBTOK-II have been investigated using a magnetic probe array, which is able to measure the radial profile of magnetic field perturbation induced by applying RMP. Results of RMP penetration into the plasma show that the RMP decreased toward the plasma center, while they were amplified around the resonant surface with a safety factor q = 3 due to the formation of magnetic islands. This suggests that RMP fields for controlling edge plasmas may trigger some kind of MHD instabilities. In addition, simulation results, based on a linearized four-field model, which agrees with the experimental ones, indicates that the penetration and amplification process of RMP strongly depend on a Doppler-shifted frequency between the RMP and plasma rotation.

Resonance phenomenon in classical cepheids

International Nuclear Information System (INIS)

Takeuti, Mine; Aikawa, Toshiki

1981-01-01

To investigate resonance phenomenon in classical cepheids, the non-linear radial oscillation of stars is studied based on the assumption that the non-adiabatic perturbation is expressed in terms of van der Pol's type damping. Two- and three-wave resonance in this system is applied to classical cepheids to describe their bump and double-mode behavior. The phase of bump and the depression of amplitude are explained for bump cepheids. The double-periodicity is shown by the enhancement of the third overtone in three-wave resonance. Non-linear effect on resonant period is also discussed briefly. (author)

Non-Perturbative Formulation of Time-Dependent String Solutions

CERN Document Server

Alexandre, J; Mavromatos, Nikolaos E; Alexandre, Jean; Ellis, John; Mavromatos, Nikolaos E.

2006-01-01

We formulate here a new world-sheet renormalization-group technique for the bosonic string, which is non-perturbative in the Regge slope alpha' and based on a functional method for controlling the quantum fluctuations, whose magnitudes are scaled by the value of alpha'. Using this technique we exhibit, in addition to the well-known linear-dilaton cosmology, a new, non-perturbative time-dependent background solution. Using the reparametrization invariance of the string S-matrix, we demonstrate that this solution is conformally invariant to alpha', and we give a heuristic inductive argument that conformal invariance can be maintained to all orders in alpha'. This new time-dependent string solution may be applicable to primordial cosmology or to the exit from linear-dilaton cosmology at large times.

Ab initio approach to the non-perturbative scalar Yukawa model

OpenAIRE

Li, YangDepartment of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA; Karmanov, V.A.(Lebedev Physical Institute, Leninsky Prospekt 53, Moscow, 119991, Russia); Maris, P.(Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA); Vary, J.P.(Department of Physics and Astronomy, Iowa State University, Ames, IA, 50011, USA)

2015-01-01

We report on the first non-perturbative calculation of the scalar Yukawa model in the single-nucleon sector up to four-body Fock sector truncation (one "scalar nucleon" and three "scalar pions"). The light-front Hamiltonian approach with a systematic non-perturbative renormalization is applied. We study the $n$-body norms and the electromagnetic form factor. We find that the one- and two-body contributions dominate up to coupling $\\alpha \\approx 1.7$. As we approach the coupling $\\alpha \\appr...

Partons and quarks. Daresbury lecture note series No. 12

Energy Technology Data Exchange (ETDEWEB)

Close, F. E.

1973-04-15

The report is based on a series of lectures given at Daresbury Laboratory on 2 to 12 Apri1 1973. It is stated that the purpose was to show the reasons why parton models describe the data, show what other phenomena can be understood and what predictions can be made within the parton hypothesis. The report is in sections: elastic electron scattering; inelastic electron scattering; deep inelastic scattering and partons; structure functions and surn rules in the quark parton model; inelastic neutrinto scattering; forward Compton scattering; Compton scattering in simple models; a J = 0 fixed pole in Compton scattering; the non-perturbative parton model without tears; the parton model and vector-meson dominance-rivals or partners; do resonances scale; resonances, SU(6) and the quark parton model; towards a dynamical parton model. (UK)

Using the MCNP Taylor series perturbation feature (efficiently) for shielding problems

Science.gov (United States)

Favorite, Jeffrey

2017-09-01

The Taylor series or differential operator perturbation method, implemented in MCNP and invoked using the PERT card, can be used for efficient parameter studies in shielding problems. This paper shows how only two PERT cards are needed to generate an entire parameter study, including statistical uncertainty estimates (an additional three PERT cards can be used to give exact statistical uncertainties). One realistic example problem involves a detailed helium-3 neutron detector model and its efficiency as a function of the density of its high-density polyethylene moderator. The MCNP differential operator perturbation capability is extremely accurate for this problem. A second problem involves the density of the polyethylene reflector of the BeRP ball and is an example of first-order sensitivity analysis using the PERT capability. A third problem is an analytic verification of the PERT capability.

Theoretical approach for plasma series resonance effect in geometrically symmetric dual radio frequency plasma

International Nuclear Information System (INIS)

Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.

2012-01-01

Plasma series resonance (PSR) effect is well known in geometrically asymmetric capacitively couple radio frequency plasma. However, plasma series resonance effect in geometrically symmetric plasma has not been properly investigated. In this work, a theoretical approach is made to investigate the plasma series resonance effect and its influence on Ohmic and stochastic heating in geometrically symmetric discharge. Electrical asymmetry effect by means of dual frequency voltage waveform is applied to excite the plasma series resonance. The results show considerable variation in heating with phase difference between the voltage waveforms, which may be applicable in controlling the plasma parameters in such plasma.

Testing QCD in the non-perturbative regime

Energy Technology Data Exchange (ETDEWEB)

A.W. Thomas

2007-01-01

This is an exciting time for strong interaction physics. We have a candidate for a fundamental theory, namely QCD, which has passed all the tests thrown at it in the perturbative regime. In the non-perturbative regime it has also produced some promising results and recently a few triumphs but the next decade will see enormous progress in our ability to unambiguously calculate the consequences of non-perturbative QCD and to test those predictions experimentally. Amongst the new experimental facilities being constructed, the hadronic machines at JPARC and GSI-FAIR and the 12 GeV Upgrade at Jefferson Lab, the major new electromagnetic facility worldwide, present a beautifully complementary network aimed at producing precise new measurements which will advance our knowledge of nuclear systems and push our ability to calculate the consequences of QCD to the limit. We will first outline the plans at Jefferson Lab for doubling the energy of CEBAF. The new facility presents some wonderful opportunities for discovery in strong interaction physics, as well as beyond the standard model. Then we turn to the theoretical developments aimed at extracting precise results for physical hadron properties from lattice QCD simulations. This discussion will begin with classical examples, such as the mass of the nucleon and ?, before dealing with a very recent and spectacular success involving information extracted from modern parity violating electron scattering.

Alien calculus and non perturbative effects in Quantum Field Theory

Science.gov (United States)

Bellon, Marc P.

2016-12-01

In many domains of physics, methods for dealing with non-perturbative aspects are required. Here, I want to argue that a good approach for this is to work on the Borel transforms of the quantities of interest, the singularities of which give non-perturbative contributions. These singularities in many cases can be largely determined by using the alien calculus developed by Jean Écalle. My main example will be the two point function of a massless theory given as a solution of a renormalization group equation.

Perturbation-induced emergence of Poisson-like behavior in non-Poisson systems

International Nuclear Information System (INIS)

Akin, Osman C; Grigolini, Paolo; Paradisi, Paolo

2009-01-01

The response of a system with ON–OFF intermittency to an external harmonic perturbation is discussed. ON–OFF intermittency is described by means of a sequence of random events, i.e., the transitions from the ON to the OFF state and vice versa. The unperturbed waiting times (WTs) between two events are assumed to satisfy a renewal condition, i.e., the WTs are statistically independent random variables. The response of a renewal model with non-Poisson ON–OFF intermittency, associated with non-exponential WT distribution, is analyzed by looking at the changes induced in the WT statistical distribution by the harmonic perturbation. The scaling properties are also studied by means of diffusion entropy analysis. It is found that, in the range of fast and relatively strong perturbation, the non-Poisson system displays a Poisson-like behavior in both WT distribution and scaling. In particular, the histogram of perturbed WTs becomes a sequence of equally spaced peaks, with intensity decaying exponentially in time. Further, the diffusion entropy detects an ordinary scaling (related to normal diffusion) instead of the expected unperturbed anomalous scaling related to the inverse power-law decay. Thus, an analysis based on the WT histogram and/or on scaling methods has to be considered with some care when dealing with perturbed intermittent systems

Spatiotemporal response of plasma edge density and temperature to non-axisymmetric magnetic perturbations at ASDEX Upgrade

International Nuclear Information System (INIS)

Fischer, R; Fuchs, J C; McDermott, R; Rathgeber, S K; Suttrop, W; Wolfrum, E; Willensdorfer, M

2012-01-01

Non-axisymmetric magnetic perturbations (MPs) were successfully applied at ASDEX Upgrade to substantially reduce the plasma energy loss and peak divertor power load that occur concomitant with type-I edge localized modes (ELMs). The response of electron density edge profiles and temperature and pressure pedestal-top values to MPs are reported. ELM mitigation is observed above an edge density threshold and independent of the MPs being resonant or non-resonant with the edge safety factor. The edge electron collisionality appears not to be appropriate to separate mitigated from non-mitigated discharges for the present high-collisionality plasmas. No significant change in the position or gradient of the edge density profile could be observed for the transition into the ELM-mitigated phase, except from the effect of the three-dimensional MP field which leads to an apparent profile shift. An increase in the density and decrease in the temperature at the pedestal-top balance such that the pressure saturates at the value of the pre-mitigated phase. The plasma stored energy, the normalized plasma pressure, and the H-mode quality factor follow closely the evolution of the pedestal-top pressure and thus remain almost unaffected. The temporal evolution of the ion effective charge shows that the impurity content does not increase although flushing through type-I ELMs is missing. The type-I ELMs are replaced in the mitigated phase by small-scale and high-frequency edge perturbations. The effect of the small bursts on the density profile, which is correlated with a transient increase of the divertor thermoelectric current, is small compared with the effect of the type-I ELMs. The residual scatter of the profiles in the mitigated phase is small directly after the transition into the ELM-mitigated phase and increases again when the pressure saturates at the value of the pre-mitigated phase. (paper)

The width of the Δ-resonance at two loop order in baryon chiral perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Gegelia, Jambul, E-mail: j.gegelia@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Tbilisi State University, 0186 Tbilisi, Georgia (United States); Meißner, Ulf-G., E-mail: meissner@hiskp.uni-bonn.de [Helmholtz Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Siemens, Dmitrij, E-mail: dmitrij.siemens@rub.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yao, De-Liang, E-mail: d.yao@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-12-10

We calculate the width of the delta resonance at leading two-loop order in baryon chiral perturbation theory. This gives a correlation between the leading pion–nucleon–delta and pion–delta couplings, which is relevant for the analysis of pion–nucleon scattering and other processes.

Asymptotic behaviour of optimal fraction-rational series of the perturbation theory at description of molecular rotational spectra

International Nuclear Information System (INIS)

Burenin, A.V.

1994-01-01

A possibility is shown of substantial expansion of the choice of asymptotic behaviour of optimal fraction-rational series of the perturbation theory on description of molecular rotational spectra. The expansion permits to hope for substantial improvement of results of using the conception of effective rotational hamiltonian in a fraction-rational form on the description of highly perturbed vibrational states

Non-perturbative aspects of nonlinear sigma models

Energy Technology Data Exchange (ETDEWEB)

Flore, Raphael

2012-12-07

The aim of this thesis was the study and further development of non-perturbative methods of quantum field theory by means of their application to nonlinear sigma models. While a large part of the physical phenomena of quantum field theory can be successfully predicted by the perturbation theory, some aspects in the region of large coupling strengths are not definitively understood and require suited non-perturbative methods for its analysis. This thesis is concentrated on two approaches, the numerical treatment of field theories on discrete space-time lattices and the functional renormalization group (FRG) as description of the renormalization flux of effective actions. Considerations of the nonlinear O(N) models have shown that for the correct analysis of the critical properties in the framework of the FRG an approach must be chosen, which contained fourth-derivation orders. For this a covariant formalism was developed, which is based on a background-field expansion and the development of a heat kernel. Apart from a destabilizing coupling the results suggest a nontrivial fixed point and by this a non-perturbative renormalizability of these models. The resulting flow diagrams were finally still compared with the results of a numerical analysis of the renormalization flow by means of the Monte-Carlo renormalization group, and hereby qualitative agreement was found. Furthermore an alternative formulation of the FRG in phase-space coordinates was studied and their consistency tested on simple examples. Beyond this an alternative expansion of the effective action in orders of the canonical momenta was applied to the nonlinear O(N) models with the result of a stable non-trivial fixed point, the critical properties of which however show not the expected N-dependence. By means of the FRG finally still the renormalization of topological operators was studied by means of the winding number of the O(3){approx_equal}CP{sup 1} model. By the generalization of the topological

Non-perturbative aspects of nonlinear sigma models

International Nuclear Information System (INIS)

Flore, Raphael

2012-01-01

The aim of this thesis was the study and further development of non-perturbative methods of quantum field theory by means of their application to nonlinear sigma models. While a large part of the physical phenomena of quantum field theory can be successfully predicted by the perturbation theory, some aspects in the region of large coupling strengths are not definitively understood and require suited non-perturbative methods for its analysis. This thesis is concentrated on two approaches, the numerical treatment of field theories on discrete space-time lattices and the functional renormalization group (FRG) as description of the renormalization flux of effective actions. Considerations of the nonlinear O(N) models have shown that for the correct analysis of the critical properties in the framework of the FRG an approach must be chosen, which contained fourth-derivation orders. For this a covariant formalism was developed, which is based on a background-field expansion and the development of a heat kernel. Apart from a destabilizing coupling the results suggest a nontrivial fixed point and by this a non-perturbative renormalizability of these models. The resulting flow diagrams were finally still compared with the results of a numerical analysis of the renormalization flow by means of the Monte-Carlo renormalization group, and hereby qualitative agreement was found. Furthermore an alternative formulation of the FRG in phase-space coordinates was studied and their consistency tested on simple examples. Beyond this an alternative expansion of the effective action in orders of the canonical momenta was applied to the nonlinear O(N) models with the result of a stable non-trivial fixed point, the critical properties of which however show not the expected N-dependence. By means of the FRG finally still the renormalization of topological operators was studied by means of the winding number of the O(3)≅CP 1 model. By the generalization of the topological operator and the

Perturbative approach to non-Markovian stochastic Schroedinger equations

International Nuclear Information System (INIS)

Gambetta, Jay; Wiseman, H.M.

2002-01-01

In this paper we present a perturbative procedure that allows one to numerically solve diffusive non-Markovian stochastic Schroedinger equations, for a wide range of memory functions. To illustrate this procedure numerical results are presented for a classically driven two-level atom immersed in an environment with a simple memory function. It is observed that as the order of the perturbation is increased the numerical results for the ensemble average state ρ red (t) approach the exact reduced state found via Imamog-barlu ' s enlarged system method [Phys. Rev. A 50, 3650 (1994)

Non-perturbative QCD Effects and the Top Mass at the Tevatron

CERN Document Server

Wicke, Daniel

2008-01-01

The modelling of non-perturbative effects is an important part of modern collider physics simulations. In hadron collisions there is some indication that the modelling of the interactions of the beam remnants, the underlying event, may require non-trivial colour reconnection effects to be present. We recently introduced a universally applicable toy model of such reconnections, based on hadronising strings. This model, which has one free parameter, has been implemented in the Pythia event generator. We then considered several parameter sets (`tunes'), constrained by fits to Tevatron minimum-bias data, and determined the sensitivity of a simplified top mass analysis to these effects, in exclusive semi-leptonic top events at the Tevatron. A first attempt at isolating the genuine non-perturbative effects gave an estimate of order +-0.5GeV from non-perturbative uncertainties. The results presented here are an update to the original study and include recent bug fixes of Pythia that influenced the tunings investigat...

Controlling quark mass determinations non-perturbatively in three-flavour QCD

CERN Document Server

Campos, Isabel

2017-01-01

The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely established. We present our results for the non-perturbative running of renormalized quark masses in Nf=3 QCD between the electroweak and a hadronic energy scale, where lattice simulations are at our disposal. Recent theoretical advances in combination with well-established techniques allows to follow the scale evolution to very high statistical accuracy, and full control of systematic effects.

Perturbation analysis of cyclotron resonance in the electromagnetic field of a TE{sub 011} mode; Analyse par perturbation de la resonance cyclotronique dans le champ electromagnetique en mode TE{sub 011} mode

Energy Technology Data Exchange (ETDEWEB)

Dreicer, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-07-01

The motion of an electron orbiting under the combined action of a static magnetic field and the AC azimuthal electric field of a cylindrical TE{sub 011} mode is analyzed with help of a perturbation technique. The first and second order perturbation results indicate that at cyclotron resonance the electron's center of gyration oscillates slowly at right angles to the magnetic field between two turning points. We find that superimposed upon this nearly static Exb drift the electron cyclically undergoes the process of cyclotron absorption and induced emission. Our results indicate that it is possible to insure maser action (i.e. induced emission rather than absorption) without special preparation of the electron's velocity provided that the electron is introduced into the field in certain special regions of space pervaded by the TE mode. This is a case where over-population of the upper state is accomplished through 'pumping' in real space. The relation between an electron cyclotron resonance maser based upon this principle and one based upon the principle of velocity space pumping, due to Twiss, is examined. This treatment provides physical interpretations and verifies the numerical results found earlier by Le Gardeur. (author) [French] Le mouvement d'un electron soumis a l'action combinee d'un champ magnetique statique et d'un champ electrique haute frequence azimutal engendre dans une cavite cylindrique en mode TE{sub 011} est analyse a partir d'une methode de perturbation. Les resultats des perturbations au premier et deuxieme ordre indiquent qu'a la resonance cyclotronique, le centre de giration de l'electron oscille lentement dans le plan perpendiculaire au champ magnetique entre deux points de rebroussement. En plus de la derivee quasi-statique ExB, l'electron passe par des etats d'absorption et emission cyclotronique. Les resultats du calcul confirment la possibilite d'avoir une action maser (c'est-a-dire: emission au lieu d'absorption) sans que la vitesse des

Non-perturbative aspects of string theory from elliptic curves

International Nuclear Information System (INIS)

Reuter, Jonas

2015-08-01

We consider two examples for non-perturbative aspects of string theory involving elliptic curves. First, we discuss F-theory on genus-one fibered Calabi-Yau manifolds with the fiber being a hypersurface in a toric fano variety. We discuss in detail the fiber geometry in order to find the gauge groups, matter content and Yukawa couplings of the corresponding supergravity theories for the four examples leading to gauge groups SU(3) x SU(2) x U(1), SU(4) x SU(2) x SU(2)/Z 2 , U(1) and Z 3 . The theories are connected by Higgsings on the field theory side and conifold transitions on the geometry side. We extend the discussion to the network of Higgsings relating all theories stemming from the 16 hypersurface fibrations. For the models leading to gauge groups SU(3) x SU(2) x U(1), SU(4) x SU(2) x SU(2)/Z 2 and U(1) we discuss the construction of vertical G 4 fluxes. Via the D3-brane tadpole cancelation condition we can restrict the minimal number of families in the first two of these models to be at least three. As a second example for non-perturbative aspects of string theory we discuss a proposal for a non-perturbative completion of topological string theory on local B-model geometries. We discuss in detail the computation of quantum periods for the examples of local F 1 , local F 2 and the resolution of C 3 /Z 5 . The quantum corrections are calculated order by order using second order differential operators acting on the classical periods. Using quantum geometry we calculate the refined free energies in the Nekrasov-Shatashvili limit. Finally we check the non-perturbative completion of topological string theory for the geometry of local F 2 against numerical calculations.

Non-perturbative topological strings and conformal blocks

NARCIS (Netherlands)

Cheng, M.C.N.; Dijkgraaf, R.; Vafa, C.

2011-01-01

We give a non-perturbative completion of a class of closed topological string theories in terms of building blocks of dual open strings. In the specific case where the open string is given by a matrix model these blocks correspond to a choice of integration contour. We then apply this definition to

The non-linear Perron-Frobenius theorem : Perturbations and aggregation

NARCIS (Netherlands)

Dietzenbacher, E

The dominant eigenvalue and the corresponding eigenvector (or Perron vector) of a non-linear eigensystem are considered. We discuss the effects upon these, of perturbations and of aggregation of the underlying mapping. The results are applied to study the sensivity of the outputs in a non-linear

Accurate energy levels for the anharmonic oscillator and a summable series for the double-well potential in perturbation theory

International Nuclear Information System (INIS)

Caswell, W.E.

1979-01-01

We introduce a generalization of Wick-ordering which maps the anharmonic oscillator (AO) Hamiltonian for mass m and coupling lambda exactly into a ''Wick-ordered'' Hamiltonian with an effective mass M which is a simple analytic function of lambda and m. The effective coupling Λ=lambda/M 3 is bounded. We transform the AO perturbation series in lambda into one in Λ. This series may then be summed using Borel summation methods. We also introduce a new summation method for the AO series (which is a practical necessity to obtain accurate energy levels of the excited states). We obtain a numerical accuracy for (E/sub P/T--E/sub e/xact)/ E/sub e/xact of at least 10 -7 (using 20 orders of perturbation theory) and 10 -3 (using only 2 orders of perturbation theory) for all couplings and all energy levels of the anharmonic oscillator. The methods are applicable also to the double-well potential (DWP, the AO with a negative mass-squared). The only change is that now the effective coupling is unbounded as lambda→0. The series in Λ is, however, still summable. The relative accuracy in the energy levels for 20 orders of perturbation theory varies from 10 -7 for large coupling to 1% at lambda=0.1 and to 10% at lambda=.05. We also present results for the sextic oscillator

Exact non-linear equations for cosmological perturbations

Energy Technology Data Exchange (ETDEWEB)

Gong, Jinn-Ouk [Asia Pacific Center for Theoretical Physics, Pohang 37673 (Korea, Republic of); Hwang, Jai-chan [Department of Astronomy and Atmospheric Sciences, Kyungpook National University, Daegu 41566 (Korea, Republic of); Noh, Hyerim [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of); Wu, David Chan Lon; Yoo, Jaiyul, E-mail: jinn-ouk.gong@apctp.org, E-mail: jchan@knu.ac.kr, E-mail: hr@kasi.re.kr, E-mail: clwu@physik.uzh.ch, E-mail: jyoo@physik.uzh.ch [Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, Universität Zürich, CH-8057 Zürich (Switzerland)

2017-10-01

We present a complete set of exact and fully non-linear equations describing all three types of cosmological perturbations—scalar, vector and tensor perturbations. We derive the equations in a thoroughly gauge-ready manner, so that any spatial and temporal gauge conditions can be employed. The equations are completely general without any physical restriction except that we assume a flat homogeneous and isotropic universe as a background. We also comment briefly on the application of our formulation to the non-expanding Minkowski background.

Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

International Nuclear Information System (INIS)

Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.; Kakati, M.

2011-01-01

Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure.

Non-gaussianity from the trispectrum and vector field perturbations

International Nuclear Information System (INIS)

Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon

2010-01-01

We use the δN formalism to study the trispectrum T ζ of the primordial curvature perturbation ζ when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, τ NL , is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f NL , and the level of statistical anisotropy in the power spectrum, g ζ . Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on τ NL from WMAP, for generic inflationary models, is done.

Modelling of Plasma Response to Resonant Magnetic Perturbations and its Influence on Divertor Strike Points

Energy Technology Data Exchange (ETDEWEB)

Cahyna, P.; Peterka, M.; Panek, R., E-mail: cahyna@ipp.cas.cz [Institute of Plasma Physics AS CR, Prague (Czech Republic); Liu, Y.; Kirk, A.; Harrison, J.; Thornton, A.; Chapman, I. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Nardon, E. [Association Euratom/CEA, CEA Cadarache, St. Paul-lez-Durance (France); Schmitz, O. [Forschung Zentrum Juelich, Juelich (Germany)

2012-09-15

Full text: Resonant magnetic perturbations (RMPs) for edge localized mode (ELM) mitigation in tokamaks can be modified by the plasma response and indeed strong screening of the applied perturbation is in some cases predicted by simulations. In this contribution we investigate what effect would such screening have on the spiralling patterns (footprints) which may appear at the divertor when RMPs are applied. We use two theoretical tools for investigation of the impact of plasma response on footprints: a simple model of the assumed screening currents, which can be used to translate the screening predicted by MHD codes in a simplified geometry into the real geometry, and the MHD code MARS-F. The former consistently predicts that footprints are significantly reduced when complete screening of the resonant perturbation modes (like it is the case in ideal MHD) is assumed. This result is supported by the result of MARS-F in ideal mode for the case of the MAST tokamak. To predict observed patterns of fluxes it is necessary to take into account the deformation of the scrape-off layer, and for this we developed an approximative method based on the Melnikov integral. If the screening of perturbations indeed reduces the footprints, it would provide us with an important tool to evaluate the amount of screening in experiments, as the footprints can be easily observed. We thus present a comparison between predictions and experimental data, especially for the MAST tokamak, where a significant amount of data has been collected. (author)

Resonant non-Gaussianity with equilateral properties

International Nuclear Information System (INIS)

Gwyn, Rhiannon; Rummel, Markus

2012-11-01

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f NL ∝O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

Non-perturbative particle dynamics in (2+1)-gravity

CERN Document Server

Bellini, A; Valtancoli, P

1995-01-01

We construct a non-perturbative, single-valued solution for the metric and the motion of two interacting particles in (2+1)-Gravity, by using a Coulomb gauge of conformal type. The method provides the mapping from multivalued ( minkowskian ) coordinates to single-valued ones, which solves the non-abelian monodromies due to particles's momenta and can be applied also to the general N-body case.

Hysteresis in the tearing mode locking/unlocking due to resonant magnetic perturbations in EXTRAP T2R

Science.gov (United States)

Fridström, R.; Frassinetti, L.; Brunsell, P. R.

2015-10-01

The physical mechanisms behind the hysteresis in the tearing mode locking and unlocking to a resonant magnetic perturbation (RMP) are experimentally studied in EXTRAP T2R reversed-field pinch. The experiments show that the electromagnetic and the viscous torque increase with increasing perturbation amplitude until the mode locks to the wall. At the wall-locking, the plasma velocity reduction profile is peaked at the radius where the RMP is resonant. Thereafter, the viscous torque drops due to the relaxation of the velocity in the central plasma. This is the main reason for the hysteresis in the RMP locking and unlocking amplitude. The increased amplitude of the locked tearing mode produces further deepening of the hysteresis. Both experimental results are in qualitative agreement with the model in Fitzpatrick et al (2001 Phys. Plasmas 8 4489)

The resonance expansion for the Green's function of the Schroedinger and wave equations

International Nuclear Information System (INIS)

Albeverio, S.; Aix-Marseille-2 Univ., 13 - Marseille; Hoeegh-Krohn, R.; Oslo Univ.

1984-01-01

We give a survey of some recent mathematical work on resonances, in particular on perturbation series, low energy expansions and on resonances for point interactions. Expansions of the kernels of esup(-it)√sup(H+) and esup(-itH) in terms of resonances are also given (where Hsub(+) is the positive part of the Hamiltonian). (orig.)

Non-perturbative approach for laser radiation interactions with solids

International Nuclear Information System (INIS)

Jalbert, G.

1985-01-01

Multiphoton transitions in direct-gap crystals are studied considering non-perturbative approaches. Two methods currently used for atoms and molecules are revised, generalized and applied to solids. In the first one, we construct an S-matrix which incorporates the eletromagnetic field to all orders in an approximated way leading to analytical solution for the multiphoton transition rates. In the second one, the transition probability is calculated within the Bloch-Floquet formalism applieed to the specific case of solids. This formalism is interpreted as a classical approximation to the quantum treatment of the field. In the weak field limit, we compare our results with the usual perturbation calculations. We also incorporate, in the first approach, the non homogeneity and the multimodes effects of a real laser. (author) [pt

Non-gaussianity from the trispectrum and vector field perturbations

Energy Technology Data Exchange (ETDEWEB)

Valenzuela-Toledo, Cesar A., E-mail: cavalto@ciencias.uis.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Rodriguez, Yeinzon, E-mail: yeinzon.rodriguez@uan.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Centro de Investigaciones, Universidad Antonio Narino, Cra 3 Este 47A-15, Bogota D.C. (Colombia)

2010-03-01

We use the deltaN formalism to study the trispectrum T{sub z}eta of the primordial curvature perturbation zeta when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, tau{sub NL}, is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f{sub NL}, and the level of statistical anisotropy in the power spectrum, g{sub z}eta. Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on tau{sub NL} from WMAP, for generic inflationary models, is done.

Resonant non-Gaussianity with equilateral properties

Energy Technology Data Exchange (ETDEWEB)

Gwyn, Rhiannon [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany); Rummel, Markus [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-11-15

We discuss the effect of superimposing multiple sources of resonant non-Gaussianity, which arise for instance in models of axion inflation. The resulting sum of oscillating shape contributions can be used to ''Fourier synthesize'' different non-oscillating shapes in the bispectrum. As an example we reproduce an approximately equilateral shape from the superposition of O(10) oscillatory contributions with resonant shape. This implies a possible degeneracy between the equilateral-type non-Gaussianity typical of models with non-canonical kinetic terms, such as DBI inflation, and an equilateral-type shape arising from a superposition of resonant-type contributions in theories with canonical kinetic terms. The absence of oscillations in the 2-point function together with the structure of the resonant N-point functions, imply that detection of equilateral non-Gaussianity at a level greater than the PLANCK sensitivity of f{sub NL} {proportional_to}O(5) will rule out a resonant origin. We comment on the questions arising from possible embeddings of this idea in a string theory setting.

High-Speed imaging of the plasma response to resonant magnetic perturbations in HBT-EP

International Nuclear Information System (INIS)

Angelini, Sarah M; Levesque, Jeffrey P; Mauel, Michael E; Navratil, Gerald A

2015-01-01

A Phantom v7.3 fast digital camera was used to study visible light fluctuations in the High Beta Tokamak–Extended Pulse (HBT–EP). This video data is the first to be used to analyze and understand the behavior of long wavelength kink perturbations in a wall-stabilized tokamak. The light was mostly comprised of Dα 656 nm light. Profiles of the plasma light at the midplane were hollow with a radial scale length of approximately 4 cm at the plasma edge. The fast camera was also used to measure the plasma’s response to applied helical magnetic perturbations. The programmed toroidal phase angle of the resonant magnetic perturbation (RMP) was directly inferred from the resulting images of the plasma response. The plasma response and the intensity of the RMP were compared under different conditions. The resulting amplitude correlations are consistent with previous measurements of the static response using an array of magnetic sensors. (paper)

Systems of evolution equations and the singular perturbation method

International Nuclear Information System (INIS)

Mika, J.

Several fundamental theorems are presented important for the solution of linear evolution equations in the Banach space. The algorithm is deduced extending the solution of the system of singularly perturbed evolution equations into an asymptotic series with respect to a small positive parameter. The asymptotic convergence is shown of an approximate solution to the accurate solution. Singularly perturbed evolution equations of the resonance type were analysed. The special role is considered of the asymptotic equivalence of P1 equations obtained as the first order approximation if the spherical harmonics method is applied to the linear Boltzmann equation, and the diffusion equations of the linear transport theory where the small parameter approaches zero. (J.B.)

Numerical studies of QCD renormalons in high-order perturbative expansions

International Nuclear Information System (INIS)

Bauer, Clemens

2013-01-01

Perturbative expansions in four-dimensional non-Abelian gauge theories such as Quantum Chromodynamics (QCD) are expected to be divergent, at best asymptotic. One reason is that it is impossible to strictly exclude from the relevant Feynman diagrams those energy regions in which a perturbative treatment is inapplicable. The divergent nature of the series is then signaled by a rapid (factorial) growth of the perturbative expansion coefficients, commonly referred to as a renormalon. In QCD, the most severe divergences occur in the infrared (IR) limit and therefore they are classified as IR renormalons. Their appearance can be understood within the well-accepted Operator Product Expansion (OPE) framework. According to the OPE, the perturbative calculation of a physical observable must be amended by non-perturbative power corrections that come in the form of condensates, universal characteristics of the rich QCD vacuum structure. Adding up perturbative and non-perturbative contributions, the ambiguity due to the renormalon cancels and the physical observable is well-defined. Although the field has made considerable progress in the last twenty years, a proof of renormalon existence is still pending. It has only been tested assuming strong simplifications or in toy models. The aim of this thesis is to provide the first numerical evidence for renormalon existence in the gauge sector of QCD. We use Numerical Stochastic Perturbation Theory (NSPT) to directly obtain perturbative coefficients within lattice regularization, a means to replace continuum spacetime by a four-dimensional hypercubic lattice. A peculiar feature of NSPT are comparatively low simulation costs when reaching high expansion orders. We examine two distinct observables: the static self-energy of an isolated quark and the elementary plaquette. Following the OPE classification, the static quark self-energy is ideally suited for a renormalon study. Taking into account peculiarities of the lattice approach such

Series resonant converter with auxiliary winding turns: analysis, design and implementation

Science.gov (United States)

Lin, Bor-Ren

2018-05-01

Conventional series resonant converters have researched and applied for high-efficiency power units due to the benefit of its low switching losses. The main problems of series resonant converters are wide frequency variation and high circulating current. Thus, resonant converter is limited at narrow input voltage range and large input capacitor is normally adopted in commercial power units to provide the minimum hold-up time requirement when AC power is off. To overcome these problems, the resonant converter with auxiliary secondary windings are presented in this paper to achieve high voltage gain at low input voltage case such as hold-up time duration when utility power is off. Since the high voltage gain is used at low input voltage cased, the frequency variation of the proposed converter compared to the conventional resonant converter is reduced. Compared to conventional resonant converter, the hold-up time in the proposed converter is more than 40ms. The larger magnetising inductance of transformer is used to reduce the circulating current losses. Finally, a laboratory prototype is constructed and experiments are provided to verify the converter performance.

Non-perturbative construction of the Luttinger-Ward functional

Directory of Open Access Journals (Sweden)

M.Potthoff

2006-01-01

Full Text Available For a system of correlated electrons, the Luttinger-Ward functional provides a link between static thermodynamic quantities on the one hand and single-particle excitations on the other. The functional is useful in deriving several general properties of the system as well as in formulating the thermodynamically consistent approximations. Its original construction, however, is perturbative as it is based on the weak-coupling skeleton-diagram expansion. Here, it is shown that the Luttinger-Ward functional can be derived within a general functional-integral approach. This alternative and non-perturbative approach stresses the fact that the Luttinger-Ward functional is universal for a large class of models.

Predictions of toroidal rotation and torque sources arising in non-axisymmetric perturbed magnetic fields in tokamaks

Science.gov (United States)

Honda, M.; Satake, S.; Suzuki, Y.; Shinohara, K.; Yoshida, M.; Narita, E.; Nakata, M.; Aiba, N.; Shiraishi, J.; Hayashi, N.; Matsunaga, G.; Matsuyama, A.; Ide, S.

2017-11-01

Capabilities of the integrated framework consisting of TOPICS, OFMC, VMEC and FORTEC-3D, have been extended to calculate toroidal rotation in fully non-axisymmetric perturbed magnetic fields for demonstrating operation scenarios in actual tokamak geometry and conditions. The toroidally localized perturbed fields due to the test blanket modules and the tangential neutral beam ports in ITER augment the neoclassical toroidal viscosity (NTV) substantially, while do not significantly influence losses of beam ions and alpha particles in an ITER L-mode discharge. The NTV takes up a large portion of total torque in ITER and fairly decelerates toroidal rotation, but the change in toroidal rotation may have limited effectiveness against turbulent heat transport. The error field correction coils installed in JT-60SA can externally apply the perturbed fields, which may alter the NTV and the resultant toroidal rotation profiles. However, the non-resonant n=18 components of the magnetic fields arising from the toroidal field ripple mainly contribute to the NTV, regardless of the presence of the applied field by the coil current of 10 kA , where n is the toroidal mode number. The theoretical model of the intrinsic torque due to the fluctuation-induced residual stress is calibrated by the JT-60U data. For five JT-60U discharges, the sign of the calibration factor conformed to the gyrokinetic linear stability analysis and a range of the amplitude thereof was revealed. This semi-empirical approach opens up access to an attempt on predicting toroidal rotation in H-mode plasmas.

A 25-kW Series-Resonant Power Converter

Science.gov (United States)

Frye, R. J.; Robson, R. R.

1986-01-01

Prototype exhibited efficiency of 93.9 percent. 25-kW resonant dc/dc power converter designed, developed, fabricated, and tested, using Westinghouse D7ST transistors as high-power switches. D7ST transistor characterized for use as switch in series-resonant converters, and refined base-drive circuit developed. Technical base includes advanced switching magnetic, and filter components, mathematical circuit models, control philosophies, and switch-drive strategies. Power-system benefits such as lower losses when used for high-voltage distribution, and reduced magnetics and filter mass realized.

Basic dynamics at a multiple resonance

International Nuclear Information System (INIS)

Ferraz-Mello, S.; Yokoyama, T.

The problem of multiple resonance is dealt with as it occurs in Celestial Mechanics and in non-linear Mechanics. In perturbation theory small divisors occur as a consequence of the fact that the flows in the phase space of the real system and the flows in the phase space of the so-called undisturbed system are not homeomorphic at all. Whatever the perturbation technique we adopt, the first step is to correct the topology of the undisturbed flows. It is shown that at a multiple resonance we are led to dynamical systems that are generally non-integrable. The basic representatives of these systems are the n-pendulums theta sup(:) sub(k) = σ sub(j)A sub(jk) sin theta sub(j). Multiple resonances are classified as syndetic or asyndetic following the eigenvalues of a quadratic form. Some degenerate cases are also presented. (Author) [pt

Implementation of optimal trajectory control of series resonant converter

Science.gov (United States)

Oruganti, Ramesh; Yang, James J.; Lee, Fred C.

1987-01-01

Due to the presence of a high-frequency LC tank circuit, the dynamics of a resonant converter are unpredictable. There is often a large surge of tank energy during transients. Using state-plane analysis technique, an optimal trajectory control utilizing the desired solution trajectory as the control law was previously proposed for the series resonant converters. The method predicts the fastest response possible with minimum energy surge in the resonant tank. The principle of the control and its experimental implementation are described here. The dynamics of the converter are shown to be close to time-optimal.

Current Mode Control for LLC Series Resonant DC-to-DC Converters

Directory of Open Access Journals (Sweden)

Jinhaeng Jang

2015-06-01

Full Text Available Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a new current mode control scheme which could consistently provide good closed-loop performance for LLC resonant converters for the entire operational range. The proposed control scheme employs an additional feedback from the current of the resonant tank network to overcome the limitation of the existing voltage mode control. The superiority of the proposed current mode control over the conventional voltage mode control is verified using an experimental 150 W LLC series resonant DC-to-DC converter.

Non-perturbative renormalization of static-light four-fermion operators in quenched lattice QCD

Energy Technology Data Exchange (ETDEWEB)

Palombi, F. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Papinutto, M.; Pena, C. [CERN, Geneva (Switzerland). Physics Dept., Theory Div.; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik

2007-06-15

We perform a non-perturbative study of the scale-dependent renormalization factors of a multiplicatively renormalizable basis of {delta}B=2 parity-odd four-fermion operators in quenched lattice QCD. Heavy quarks are treated in the static approximation with various lattice discretizations of the static action. Light quarks are described by nonperturbatively O(a) improved Wilson-type fermions. The renormalization group running is computed for a family of Schroedinger functional (SF) schemes through finite volume techniques in the continuum limit. We compute non-perturbatively the relation between the renormalization group invariant operators and their counterparts renormalized in the SF at a low energy scale. Furthermore, we provide non-perturbative estimates for the matching between the lattice regularized theory and all the SF schemes considered. (orig.)

High voltage series resonant inverter ion engine screen supply. [SCR series resonant inverter for space applications

Science.gov (United States)

Biess, J. J.; Inouye, L. Y.; Shank, J. H.

1974-01-01

A high-voltage, high-power LC series resonant inverter using SCRs has been developed for an Ion Engine Power Processor. The inverter operates within 200-400Vdc with a maximum output power of 2.5kW. The inverter control logic, the screen supply electrical and mechanical characteristics, the efficiency and losses in power components, regulation on the dual feedback principle, the SCR waveforms and the component weight are analyzed. Efficiency of 90.5% and weight density of 4.1kg/kW are obtained.

A study of the high frequency limitations of series resonant converters

Science.gov (United States)

Stuart, T. A.; King, R. J.

1982-01-01

A transformer induced oscillation in series resonant (SR) converters is studied. It may occur in the discontinuous current mode. The source of the oscillation is an unexpected resonant circuit formed by normal resonance components in series with the magnetizing inductance of the output transformers. The methods for achieving cyclic stability are: to use a half bridge SR converter where q0.5. Q should be as close to 1.0 as possible. If 0.5q1.0, the instability will be avoided if psi2/3q-1/3. The second objective was to investigate a power field effect transistor (FET) version of the SR converter capable of operating at frequencies above 100 KHz, to study component stress and losses at various frequencies.

Generalized Euler transformation for summing strongly divergent Rayleigh-Schroedinger perturbation series: the Zeeman effect

International Nuclear Information System (INIS)

Silverman, J.N.

1983-01-01

A generalized Euler transformation (GET) is introduced which provides a powerful alternative method of accurately summing strongly divergent Rayleigh-Schroedinger (RS) perturbation series when other summability methods fail or are difficult to apply. The GET is simple to implement and, unlike a number of other summation procedures, requires no a priori knowledge of the analytic properties of the function underlying the RS series. Application of the GET to the difficult problem of the RS weak-field ground-state eigenvalue series of the hydrogen atom in a magnetic field (quadratic Zeeman effect) yields sums of good accuracy over a very wide range of field strengths up to the most intense fields of 10 14 G. The GET results are compared with those obtained by other summing methods

A non-perturbative definition of 2D quantum gravity by the fifth time action

International Nuclear Information System (INIS)

Ambjoern, J.; Greensite, J.; Varsted, S.

1990-07-01

The general formalism for stabilizing bottomless Euclidean field theories (the 'fifth-time' action) provides a natural non-perturbative definition of matrix models corresponding to 2d quantum gravity. The formalism allows, in principle, the use of lattice Monte Carlo techniques for non-perturbative computation of correlation functions. (orig.)

Non-Gaussianity at tree and one-loop levels from vector field perturbations

International Nuclear Information System (INIS)

Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon; Lyth, David H.

2009-01-01

We study the spectrum P ζ and bispectrum B ζ of the primordial curvature perturbation ζ when the latter is generated by scalar and vector field perturbations. The tree-level and one-loop contributions from vector field perturbations are worked out considering the possibility that the one-loop contributions may be dominant over the tree-level terms [both (either) in P ζ and (or) in B ζ ] and vice versa. The level of non-Gaussianity in the bispectrum, f NL , is calculated and related to the level of statistical anisotropy in the power spectrum, g ζ . For very small amounts of statistical anisotropy in the power spectrum, the level of non-Gaussianity may be very high, in some cases exceeding the current observational limit.

QCD phenomenology

International Nuclear Information System (INIS)

Gaillard, M.K.

1979-01-01

Selected topics in QCD phenomenology are reviewed: the development of an effective jet perturbation series with applications to factorization, energy flow analysis and photon physics; implications of non-perturbative phenomena for hard scattering processes and the pseudoscalar mass spectrum; resonance properties as extracted from the combined technologies of perturbative and non-perturbative QCD. (orig.)

Perturbation theory of quantum resonances

Czech Academy of Sciences Publication Activity Database

Durand, P.; Paidarová, Ivana

2016-01-01

Roč. 135, č. 7 (2016), s. 159 ISSN 1432-2234 Institutional support: RVO:61388955 Keywords : Partitioning technique * Analytic continuation * Perturbative expansion Subject RIV: CF - Physical ; Theoretical Chemistry

Vertical and pitching resonance of train cars moving over a series of simple beams

Science.gov (United States)

Yang, Y. B.; Yau, J. D.

2015-02-01

The resonant response, including both vertical and pitching motions, of an undamped sprung mass unit moving over a series of simple beams is studied by a semi-analytical approach. For a sprung mass that is very small compared with the beam, we first simplify the sprung mass as a constant moving force and obtain the response of the beam in closed form. With this, we then solve for the response of the sprung mass passing over a series of simple beams, and validate the solution by an independent finite element analysis. To evaluate the pitching resonance, we consider the cases of a two-axle model and a coach model traveling over rough rails supported by a series of simple beams. The resonance of a train car is characterized by the fact that its response continues to build up, as it travels over more and more beams. For train cars with long axle intervals, the vertical acceleration induced by pitching resonance dominates the peak response of the train traveling over a series of simple beams. The present semi-analytical study allows us to grasp the key parameters involved in the primary/sub-resonant responses. Other phenomena of resonance are also discussed in the exemplar study.

Transition of EMRIs through resonance: higher order corrections in resonant flux enhancement

Science.gov (United States)

Mihaylov, Deyan; Gair, Jonathan

2017-01-01

Extreme mass ratio inspirals (EMRIs) are candidate events for gravitational wave detection in the millihertz range (by detectors like LISA and eLISA). These events involve a stellar-mass black hole, or a similar compact object, descending into the gravitational field of a supermassive black hole, eventually merging with it. Properties of the inspiraling trajectory away from resonance are well known and have been studied extensively, however little is known about the behaviour of these binary systems at resonance, when the radial and lateral frequencies of the orbit become commensurate. There are two resonance models in the literature, the instantaneous frequency function by Gair, Bender, and Yunes, and the standard two timescales approach devised by Flanagan and Hinderer. We argue that the Gair, Bender and Yunes model provides a valid treatment of the resonance problem and extend this solution to higher order in the size of the on-resonance perturbation. The non-linear differential equations which arise in treating resonances are interesting from a mathematical view point. We present our algorithm for perturbative solutions and the results to third order in the infinitesimal parameter, and discuss the scope of this approach. Deyan Mihaylov is funded by the STFC.

Four-fluxes and non-perturbative superpotentials in two dimensions

International Nuclear Information System (INIS)

Lerche, W.

1998-01-01

We show how certain non-perturbative superpotentials W(Σ), which are the two-dimensional analogs of the Seiberg-Witten prepotential in 4d, can be computed via geometric engineering from 4-folds. We analyze an explicit example for which the relevant compact geometry of the 4-fold is given by P 1 fibered over P 2 . In the field theory limit, this gives an effective U(1) gauge theory with N=(2,2) supersymmetry in two dimensions. We find that the analog of the SW curve is a K3 surface, and that the complex FI coupling is given by the modular parameter of this surface. The FI potential itself coincides with the middle period of a meromorphic differential. However, it only shows up in the effective action if a certain 4-flux is switched on, and then supersymmetry appears to be non-perturbatively broken. (orig.)

Experimental studies of high-confinement mode plasma response to non-axisymmetric magnetic perturbations in ASDEX Upgrade

Science.gov (United States)

Suttrop, W.; Kirk, A.; Nazikian, R.; Leuthold, N.; Strumberger, E.; Willensdorfer, M.; Cavedon, M.; Dunne, M.; Fischer, R.; Fietz, S.; Fuchs, J. C.; Liu, Y. Q.; McDermott, R. M.; Orain, F.; Ryan, D. A.; Viezzer, E.; The ASDEX Upgrade Team; The DIII-D Team; The Eurofusion MST1 Team

2017-01-01

The interaction of externally applied small non-axisymmetric magnetic perturbations (MP) with tokamak high-confinement mode (H-mode) plasmas is reviewed and illustrated by recent experiments in ASDEX Upgrade. The plasma response to the vacuum MP field is amplified by stable ideal kink modes with low toroidal mode number n driven by the H-mode edge pressure gradient (and associated bootstrap current) which is experimentally evidenced by an observable shift of the poloidal mode number m away from field alignment (m  =  qn, with q being the safety factor) at the response maximum. A torque scan experiment demonstrates the importance of the perpendicular electron flow for shielding of the resonant magnetic perturbation, as expected from a two-fluid MHD picture. Two significant effects of MP occur in H-mode plasmas at low pedestal collisionality, ν \\text{ped}\\ast≤slant 0.4 : (a) a reduction of the global plasma density by up to 61 % and (b) a reduction of the energy loss associated with edge localised modes (ELMs) by a factor of up to 9. A comprehensive database of ELM mitigation pulses at low {ν\\ast} in ASDEX Upgrade shows that the degree of ELM mitigation correlates with the reduction of pedestal pressure which in turn is limited and defined by the onset of ELMs, i. e. a modification of the ELM stability limit by the magnetic perturbation.

Operation Analysis of the Series-Parallel Resonant Converter Working above Resonance Frequency

Directory of Open Access Journals (Sweden)

Peter Dzurko

2006-01-01

Full Text Available The present article deals with theoretical analysis of operation of a series-parallel converter working above resonance frequency. Derived are principal equations for individual operation intervals. Based on these made out are waveforms of individual quantities during both the inverter operation at load and no-load operation. The waveforms may be utilised at designing the inverter individual parts.

On the acceleration of convergence of many-body perturbation theory. Pt. 2

International Nuclear Information System (INIS)

Dietz, K.; Schmidt, C.; Warken, M.; Hess, B.A.

1992-07-01

We employ the method developed in a previous paper to small systems-Be, LiH, H 2 -where full CI-calculations are available for monitoring convergence of many-body perturbation theory. It is shown that divergent series, in particular for excited states, can be transformed into fast converging ones. In essence our method consists in performing infinite subsummations of perturbation series in order to improve convergence: coupling constants are redefined such that singularities are incorporated in a non-perturbative manner and remaining correlations can be expanded in a larger domain of the complex coupling constant plane. It is in this way that the notion of 'improved convergence' has a well defined meaning. (orig.)

Eisenstein series and string thresholds

International Nuclear Information System (INIS)

Obers, N.A.; Pioline, B.

2000-01-01

We investigate the relevance of Eisenstein series for representing certain G(Z)-invariant string theory amplitudes which receive corrections from BPS states only. G(Z) may stand for any of the mapping class, T-duality and U-duality groups Sl(d,Z), SO(d,d,Z) or E d+1(d+1) (Z) respectively. Using G(Z)-invariant mass formulae, we construct invariant modular functions on the symmetric space K backslash G(R) of non-compact type, with K the maximal compact subgroup of G(R), that generalize the standard non-holomorphic Eisenstein series arising in harmonic analysis on the fundamental domain of the Poincare upper half-plane. Comparing the asymptotics and eigenvalues of the Eisenstein series under second order differential operators with quantities arising in one- and g-loop string amplitudes, we obtain a manifestly T-duality invariant representation of the latter, conjecture their non-perturbative U-duality invariant extension, and analyze the resulting non-perturbative effects. This includes the R 4 and R 4 H -4 g -4 couplings in toroidal compactifications of M-theory to any dimension D≥4 and D≥6 respectively. (orig.)

Discontinuous conduction mode analysis of phase-modulated series ...

Indian Academy of Sciences (India)

modulated dc–dc series resonant converter (SRC) operating in discontinuous conduction mode (DCM). The conventional fundamental harmonic approximation technique is extended for a non-ideal series resonant tank to clarify the limitations of ...

Resonant magnetic perturbation effect on tearing mode dynamics

International Nuclear Information System (INIS)

Frassinetti, L.; Olofsson, K.E.J.; Brunsell, P.R.; Drake, J.R.

2010-01-01

The effect of a resonant magnetic perturbation (RMP) on the tearing mode (TM) dynamics is experimentally studied in the EXTRAP T2R device. EXTRAP T2R is equipped with a set of sensor coils and active coils connected by a digital controller allowing a feedback control of the magnetic instabilities. The recently upgraded feedback algorithm allows the suppression of all the error field harmonics but keeping a selected harmonic to the desired amplitude, therefore opening the possibility of a clear study of the RMP effect on the corresponding TM. The paper shows that the RMP produces two typical effects: (1) a weak oscillation in the TM amplitude and a modulation in the TM velocity or (2) a strong modulation in the TM amplitude and phase jumps. Moreover, the locking mechanism of a TM to a RMP is studied in detail. It is shown that before the locking, the TM dynamics is characterized by velocity modulation followed by phase jumps. Experimental results are reasonably explained by simulations obtained with a model.

Resonant primordial gravitational waves amplification

Directory of Open Access Journals (Sweden)

Chunshan Lin

2016-01-01

Full Text Available We propose a mechanism to evade the Lyth bound in models of inflation. We minimally extend the conventional single-field inflation model in general relativity (GR to a theory with non-vanishing graviton mass in the very early universe. The modification primarily affects the tensor perturbation, while the scalar and vector perturbations are the same as the ones in GR with a single scalar field at least at the level of linear perturbation theory. During the reheating stage, the graviton mass oscillates coherently and leads to resonant amplification of the primordial tensor perturbation. After reheating the graviton mass vanishes and we recover GR.

Non-gaussianity versus nonlinearity of cosmological perturbations.

Science.gov (United States)

Verde, L

2001-06-01

Following the discovery of the cosmic microwave background, the hot big-bang model has become the standard cosmological model. In this theory, small primordial fluctuations are subsequently amplified by gravity to form the large-scale structure seen today. Different theories for unified models of particle physics, lead to different predictions for the statistical properties of the primordial fluctuations, that can be divided in two classes: gaussian and non-gaussian. Convincing evidence against or for gaussian initial conditions would rule out many scenarios and point us toward a physical theory for the origin of structures. The statistical distribution of cosmological perturbations, as we observe them, can deviate from the gaussian distribution in several different ways. Even if perturbations start off gaussian, nonlinear gravitational evolution can introduce non-gaussian features. Additionally, our knowledge of the Universe comes principally from the study of luminous material such as galaxies, but galaxies might not be faithful tracers of the underlying mass distribution. The relationship between fluctuations in the mass and in the galaxies distribution (bias), is often assumed to be local, but could well be nonlinear. Moreover, galaxy catalogues use the redshift as third spatial coordinate: the resulting redshift-space map of the galaxy distribution is nonlinearly distorted by peculiar velocities. Nonlinear gravitational evolution, biasing, and redshift-space distortion introduce non-gaussianity, even in an initially gaussian fluctuation field. I investigate the statistical tools that allow us, in principle, to disentangle the above different effects, and the observational datasets we require to do so in practice.

Time series analysis in chaotic diode resonator circuit

Energy Technology Data Exchange (ETDEWEB)

Hanias, M.P. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece)] e-mail: mhanias@teihal.gr; Giannaris, G. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece); Spyridakis, A. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece); Rigas, A. [TEI of Chalkis, GR 34400, Evia, Chalkis (Greece)

2006-01-01

A diode resonator chaotic circuit is presented. Multisim is used to simulate the circuit and show the presence of chaos. Time series analysis performed by the method proposed by Grasberger and Procaccia. The correlation and minimum embedding dimension {nu} and m {sub min}, respectively, were calculated. Also the corresponding Kolmogorov entropy was calculated.

Time series analysis in chaotic diode resonator circuit

International Nuclear Information System (INIS)

Hanias, M.P.; Giannaris, G.; Spyridakis, A.; Rigas, A.

2006-01-01

A diode resonator chaotic circuit is presented. Multisim is used to simulate the circuit and show the presence of chaos. Time series analysis performed by the method proposed by Grasberger and Procaccia. The correlation and minimum embedding dimension ν and m min , respectively, were calculated. Also the corresponding Kolmogorov entropy was calculated

The Schroedinger equation and canonical perturbation theory

International Nuclear Information System (INIS)

Graffi, S.; Paul, T.

1987-01-01

Let T 0 (ℎ,ω)+εV be the Schroedinger operator corresponding to the classical Hamiltonian H 0 (ω)+εV, where H 0 (ω) is the d-dimensional harmonic oscillator with non-resonant frequencies ω=(ω 1 ..., ω d ) and the potential V(q 1 , ..., q d ) is an entire function of order (d+l) -1 . We prove that the algorithm of classical, canonical perturbation theory can be applied to the Schroedinger equation in the Bargmann representation. As a consequence, each term of the Rayleigh-Schroedinger series near any eigenvalue of T 0 (ℎ,ω) admits a convergent expansion in powers of ℎ of initial point the corresponding term of the classical Birkhoff expansion. Moreover if V is an even polynomial, the above result and the KAM theorem show that all eigenvalues λ n (ℎ,ε) of T 0 +εV such that nℎ coincides with a KAM torus are given, up to order ε ∞ , by a quantization formula which reduces to the Bohr-Sommerfeld one up to first order terms in ℎ. (orig.)

Insights on non-perturbative aspects of TMDs from models

Energy Technology Data Exchange (ETDEWEB)

H. Avakian, A. Efremov, P. Schweitzer, O. Teryaev, F. Yuan, P. Zavada

2009-12-01

Transverse momentum dependent parton distribution functions are a key ingredient in the description of spin and azimuthal asymmetries in deep-inelastic scattering processes. Recent results from non-perturbative calculations in effective approaches are reviewed, with focus on relations among different parton distribution functions in QCD and models.

Electromagnetic structure of the lowest-lying decuplet resonances in covariant chiral perturbation theory

International Nuclear Information System (INIS)

Geng, L. S.; Camalich, J. Martin; Vacas, M. J. Vicente

2009-01-01

We present a calculation of the leading SU(3)-breaking O(p 3 ) corrections to the electromagnetic moments and charge radius of the lowest-lying decuplet resonances in covariant chiral perturbation theory. In particular, the magnetic dipole moment of the members of the decuplet is predicted fixing the only low-energy constant (LEC) present up to this order with the well-measured magnetic dipole moment of the Ω - . We predict μ Δ ++ =6.04(13) and μ Δ + =2.84(2), which agree well with the current experimental information. For the electric quadrupole moment and the charge radius, we use state-of-the-art lattice QCD results to determine the corresponding LECs, whereas for the magnetic octupole moment there is no unknown LEC up to the order considered here, and we obtain a pure prediction. We compare our results with those reported in large N c , lattice QCD, heavy-baryon chiral perturbation theory, and other models.

Non-Gaussian and nonscale-invariant perturbations from tachyonic preheating in hybrid inflation

Science.gov (United States)

Barnaby, Neil; Cline, James M.

2006-05-01

We show that in hybrid inflation it is possible to generate large second-order perturbations in the cosmic microwave background due to the instability of the tachyonic field during preheating. We carefully calculate this effect from the tachyon contribution to the gauge-invariant curvature perturbation, clarifying some confusion in the literature concerning nonlocal terms in the tachyon curvature perturbation; we show explicitly that such terms are absent. We quantitatively compute the non-Gaussianity generated by the tachyon field during the preheating phase and translate the experimental constraints on the nonlinearity parameter fNL into constraints on the parameters of the model. We also show that nonscale-invariant second-order perturbations from the tachyon field with spectral index n=4 can become larger than the inflaton-generated first-order perturbations, leading to stronger constraints than those coming from non-Gaussianity. The width of the excluded region in terms of the logarithm of the dimensionless coupling g, grows linearly with the log of the ratio of the Planck mass to the tachyon VEV, log⁡(Mp/v); hence very large regions are ruled out if the inflationary scale v is small. We apply these results to string-theoretic brane-antibrane inflation, and find a stringent upper bound on the string coupling, gs<10-4.5.

Non-Abelian integrable hierarchies: matrix biorthogonal polynomials and perturbations

Science.gov (United States)

Ariznabarreta, Gerardo; García-Ardila, Juan C.; Mañas, Manuel; Marcellán, Francisco

2018-05-01

In this paper, Geronimus–Uvarov perturbations for matrix orthogonal polynomials on the real line are studied and then applied to the analysis of non-Abelian integrable hierarchies. The orthogonality is understood in full generality, i.e. in terms of a nondegenerate continuous sesquilinear form, determined by a quasidefinite matrix of bivariate generalized functions with a well-defined support. We derive Christoffel-type formulas that give the perturbed matrix biorthogonal polynomials and their norms in terms of the original ones. The keystone for this finding is the Gauss–Borel factorization of the Gram matrix. Geronimus–Uvarov transformations are considered in the context of the 2D non-Abelian Toda lattice and noncommutative KP hierarchies. The interplay between transformations and integrable flows is discussed. Miwa shifts, τ-ratio matrix functions and Sato formulas are given. Bilinear identities, involving Geronimus–Uvarov transformations, first for the Baker functions, then secondly for the biorthogonal polynomials and its second kind functions, and finally for the τ-ratio matrix functions, are found.

Large-order perturbation theory

International Nuclear Information System (INIS)

Wu, T.T.

1982-01-01

The original motivation for studying the asymptotic behavior of the coefficients of perturbation series came from quantum field theory. An overview is given of some of the attempts to understand quantum field theory beyond finite-order perturbation series. At least is the case of the Thirring model and probably in general, the full content of a relativistic quantum field theory cannot be recovered from its perturbation series. This difficulty, however, does not occur in quantum mechanics, and the anharmonic oscillator is used to illustrate the methods used in large-order perturbation theory. Two completely different methods are discussed, the first one using the WKB approximation, and a second one involving the statistical analysis of Feynman diagrams. The first one is well developed and gives detailed information about the desired asymptotic behavior, while the second one is still in its infancy and gives instead information about the distribution of vertices of the Feynman diagrams

Impact of rotating resonant magnetic perturbation fields on plasma edge electron density and temperature

International Nuclear Information System (INIS)

Stoschus, H.; Schmitz, O.; Frerichs, H.; Reiser, D.; Unterberg, B.; Lehnen, M.; Reiter, D.; Samm, U.; Jakubowski, M.W.

2012-01-01

Rotating resonant magnetic perturbation (RMP) fields impose a characteristic modulation to the edge electron density n e (r, t) and temperature T e (r, t) fields, which depends on the relative rotation f rel between external RMP field and plasma fluid. The n e (r, t) and T e (r, t) fields measured in the edge (r/a = 0.9–1.05) of TEXTOR L-mode plasmas are in close correlation with the local magnetic vacuum topology for low relative rotation f rel = −0.2 kHz. In comparison with the 3D neutral and plasma transport code EMC3-Eirene, this provides substantial experimental evidence that for low relative rotation level and high resonant field amplitudes (normalized radial field strength B r 4/1 /B t =2×10 -3 ), a stochastic edge with a remnant island chain dominated by diffusive transport exists. Radially outside a helical scrape-off layer, the so-called laminar zone embedded into a stochastic domain is found to exist. In contrast for high relative rotation of f rel = 1.8 kHz, the measured modulation of n e is shifted by π/2 toroidally with respect to the modelled vacuum topology. A pronounced flattening in T e (r) and a reduction in n e (r) is measured at the resonant flux surface and represents a clear signature for a magnetic island, which is phase shifted with respect to the vacuum island position. A correlated shift of the laminar zone radially outwards at the very plasma edge is observed suggesting that the actual near-field structure at the perturbation source is determined by the plasma response as well. (paper)

Criteria for first- and second-order vibrational resonances and correct evaluation of the Darling-Dennison resonance coefficients using the canonical Van Vleck perturbation theory

International Nuclear Information System (INIS)

Krasnoshchekov, Sergey V.; Isayeva, Elena V.; Stepanov, Nikolay F.

2014-01-01

The second-order vibrational Hamiltonian of a semi-rigid polyatomic molecule when resonances are present can be reduced to a quasi-diagonal form using second-order vibrational perturbation theory. Obtaining exact vibrational energy levels requires subsequent numerical diagonalization of the Hamiltonian matrix including the first- and second-order resonance coupling coefficients. While the first-order Fermi resonance constants can be easily calculated, the evaluation of the second-order Darling-Dennison constants requires more complicated algebra for seven individual cases with different numbers of creation-annihilation vibrational quanta. The difficulty in precise evaluation of the Darling-Dennison coefficients is associated with the previously unrecognized interference with simultaneously present Fermi resonances that affect the form of the canonically transformed Hamiltonian. For the first time, we have presented the correct form of the general expression for the evaluation of the Darling-Dennison constants that accounts for the underlying effect of Fermi resonances. The physically meaningful criteria for selecting both Fermi and Darling-Dennison resonances are discussed and illustrated using numerical examples

Even order snake resonances

International Nuclear Information System (INIS)

Lee, S.Y.

1993-01-01

We found that the perturbed spin tune due to the imperfection resonance plays an important role in beam depolarization at snake resonances. We also found that even order snake resonances exist in the overlapping intrinsic and imperfection resonances. Due to the perturbed spin tune shift of imperfection resonances, each snake resonance splits into two

Inverting the Rayleigh-Schroedinger perturbation series: Application to atomic stabilization by intense light

International Nuclear Information System (INIS)

Baik, M.; Pont, M.; Shakeshaft, R.

1995-01-01

We develop a method for calculating the (quasi)energy eigenvalue E(F) of a hydrogen atom in a nonperturbative ac field of strength F starting from a knowledge of the coefficients E (2m) of the Rayleigh-Schroedinger perturbation series E(F)=tsum m=0 M E (2m) F 2m . We first use the coefficients E (2m) (the unperturbed energy is E (0) ) to construct the inverse series F 2 (E)=tsum m=1 M F (m) (E-E (0) ) m . We resum the latter series using the Pade method, and solve the implicit equation F 2 (E)=bar F 2 for E(bar F). The reconstructed function E(F) has the singularity structure appropriate to the true E(F). We are able to obtain good results for the lifetime of a hydrogen atom in a high-frequency field up to very high intensities, well into the (highly nonperturbative) stabilization regime

Reflection effect of localized absorptive potential on non-resonant and resonant tunneling

International Nuclear Information System (INIS)

Rubio, A.; Kumar, N.

1992-06-01

The reflection due to absorptive potential (-iV i ) for resonant and non-resonant tunneling has been considered. We show that the effect of reflection leads to a non-monotonic dependence of absorption on the strength V i with a maximum absorption of typically 0.5. This has implications for the operation of resonant tunneling devices. General conceptual aspects of absorptive potentials are discussed. (author). 9 refs, 2 figs

Resonance ionization spectroscopy in dysprosium

Energy Technology Data Exchange (ETDEWEB)

Studer, D., E-mail: dstuder@uni-mainz.de; Dyrauf, P.; Naubereit, P.; Heinke, R.; Wendt, K. [Johannes Gutenberg-Universität Mainz, Institut für Physik (Germany)

2017-11-15

We report on resonance ionization spectroscopy (RIS) of high-lying energy levels in dysprosium. We developed efficient excitation schemes and re-determined the first ionization potential (IP) via analysis of Rydberg convergences. For this purpose both two- and three-step excitation ladders were investigated. An overall ionization efficiency of 25(4) % could be demonstrated in the RISIKO mass separator of Mainz University, using a three-step resonance ionization scheme. Moreover, an extensive analysis of the even-parity 6sns- and 6snd-Rydberg-series convergences, measured via two-step excitation was performed. To account for strong perturbations in the observed s-series, the approach of multichannel quantum defect theory (MQDT) was applied. Considering all individual series limits we extracted an IP-value of 47901.76(5) cm{sup −1}, which agrees with the current literature value of 47901.7(6) cm{sup −1}, but is one order of magnitude more precise.

Large x Behaviour and the Non-Perturbative Structure of Hadronic Systems

Energy Technology Data Exchange (ETDEWEB)

Anthony W. Thomas

2005-02-01

While the traditional interest in structure functions has been the confirmation of the predictions of perturbative QCD, this data also contains a wealth of information on how QCD works in the infrared, or confinement, region. As the challenge of the strong force now turns to the study of QCD in the non-perturbative region, such information is extremely valuable.We outline some of the key issues for both nucleon and nuclear structure functions.

Modeling the full-bridge series-resonant power converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1982-01-01

A steady state model is derived for the full-bridge series-resonant power converter. Normalized parametric curves for various currents and voltages are then plotted versus the triggering angle of the switching devices. The calculations are compared with experimental measurements made on a 50 kHz converter and a discussion of certain operating problems is presented.

Particle resonance in the Dirac equation in the presence of a delta interaction and a perturbative hyperbolic potential

International Nuclear Information System (INIS)

Villalba, Victor M.; Gonzalez-Diaz, Luis A.

2009-01-01

We show that the energy spectrum of the one-dimensional Dirac equation, in the presence of an attractive vectorial delta potential, exhibits a resonant behavior when one includes an asymptotically spatially vanishing weak electric field associated with a hyperbolic tangent potential. We solve the Dirac equation in terms of Gauss hyper-geometric functions and show explicitly how the resonant behavior depends on the strength of the electric field evaluated at the support of the point interaction. We derive an approximate expression for the value of the resonances and compare the results calculated for the hyperbolic potential with those obtained for a linear perturbative potential. Finally, we characterize the resonances with the help of the phase shift and the Wigner delay time. (orig.)

Calibrated geometries and non perturbative superpotentials in M-theory

International Nuclear Information System (INIS)

Hernandez, R.

1999-12-01

We consider non perturbative effects in M-theory compactifications on a seven-manifold of G 2 holonomy arising from membranes wrapped on supersymmetric three-cycles. When membranes are wrapped on associative submanifolds they induce a superpotential that can be calculated using calibrated geometry. This superpotential is also derived from compactification on a seven-manifold, to four dimensional Anti-de Sitter spacetime, of eleven dimensional supergravity with non vanishing expectation value of the four-form field strength. (author)

A series-resonant converter used as an amplitude and frequency function generator

NARCIS (Netherlands)

Huisman, H.; Gravendeel, B.

1988-01-01

A series-resonant power converter system is presented which allows generation of multiphase output voltages with very low distortion at high efficiency. The self-commutated resonant operation mode ensures the converter to be short-circuit proof. After a discussion of the control concept, some

Formation of a three-dimensional plasma boundary after decay of the plasma response to resonant magnetic perturbation fields

Science.gov (United States)

Schmitz, O.; Evans, T. E.; Fenstermacher, M. E.; Lanctot, M. J.; Lasnier, C. L.; Mordijck, S.; Moyer, R. A.; Reimerdes, H.; the DIII-D Team

2014-01-01

First time experimental evidence is presented for a direct link between the decay of a n = 3 plasma response and the formation of a three-dimensional (3D) plasma boundary. We inspect a lower single-null L-mode plasma which first reacts at sufficiently high rotation with an ideal resonant screening response to an external toroidal mode number n = 3 resonant magnetic perturbation field. Decay of this response due to reduced bulk plasma rotation changes the plasma state considerably. Signatures such as density pump out and a spin up of the edge rotation—which are usually connected to formation of a stochastic boundary—are detected. Coincident, striation of the divertor single ionized carbon emission and a 3D emission structure in double ionized carbon at the separatrix is seen. The striated C II pattern follows in this stage the perturbed magnetic footprint modelled without a plasma response (vacuum approach). This provides for the first time substantial experimental evidence, that a 3D plasma boundary with direct impact on the divertor particle flux pattern is formed as soon as the internal plasma response decays. The resulting divertor structure follows the vacuum modelled magnetic field topology. However, the inward extension of the perturbed boundary layer can still not directly be determined from these measurements.

A Homotopy-Perturbation analysis of the non-linear contaminant ...

African Journals Online (AJOL)

In this research work, a Homotopy-perturbation analysis of a non –linear contaminant flow equation with an initial continuous point source is provided. The equation is characterized by advection, diffusion and adsorption. We assume that the adsorption term is modeled by Freudlich Isotherm. We provide an approximation of ...

High speed resonant frequency determination applied to field mapping using perturbation techniques

International Nuclear Information System (INIS)

Smith, B.H.; Burton, R.J.; Hutcheon, R.M.

1992-01-01

Perturbation techniques are commonly used for measuring electric and magnetic field distributions in resonant structures. A field measurement system has been assembled using a Hewlett Packard model 8753C network analyzer interfaced via an HPIB bus to a personal computer to form an accurate, rapid and flexible system for data acquisition, control, and analysis of such measurements. Characterization of long linac structures (up to 3 m) is accomplished in about three minutes, minimizing thermal drift effects. This paper describes the system, its application and its extension to applications such as confirming the presence of weak, off-axis quadrupole fields in an on-axis coupled linac. (Author) 5 figs., 10 refs

Ferromagnetic resonance frequency increase and resonance line broadening of a ferromagnetic Fe–Co–Hf–N film with in-plane uniaxial anisotropy by high-frequency field perturbation

International Nuclear Information System (INIS)

Seemann, K.; Leiste, H.; Krüger, K.

2013-01-01

Soft ferromagnetic Fe-Co-Hf-N films, produced by reactive r.f. magnetron sputtering, are useful to study the ferromagnetic resonance (FMR) by means of frequency domain permeability measurements up to the GHz range. Films with the composition Fe 33 Co 43 Hf 10 N 14 exhibit a saturation polarisation J s of around 1.35 T. They are consequently considered as being uniformly magnetised due to an in-plane uniaxial anisotropy of approximately μ 0 H u ≈4.5 m T after annealing them, e.g., at 400 °C in a static magnetic field for 1 h. Being exposed to a high-frequency field, the precession of magnetic moments leads to a marked frequency-dependent permeability with a sharp Lorentzian shaped imaginary part at around 2.33 GHz (natural resonance peak), which is in a very good agreement with the modified Landau–Lifschitz–Gilbert (LLG) differential equation. A slightly increased FMR frequency and a clear increase in the resonance line broadening due to an increase of the exciting high-frequency power (1–25.1 mW), considered as an additional perturbation of the precessing system of magnetic moments, could be discovered. By solving the homogenous LLG differential equation with respect to the in-plane uniaxial anisotropy, it was revealed that the high-frequency field perturbation impacts the resonance peak position f FMR and resonance line broadening Δf FMR characterised by a completed damping parameter α=α eff +Δα. Adapted from this result, the increase in f FMR and decrease in lifetime of the excited level of magnetic moments associated with Δf FMR , similar to a spin-½ particle in a static magnetic field, was theoretically elaborated as well as compared with experimental data. - Highlights: • Impact on the resonance frequency and resonance line by the high-frequency power. • Theoretic approach by solving the LLG differential equation. • Experimental verification and magnon processes. • Theoretical and experimental determination of the resonance state

Probing non-perturbative effects in M-theory

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki; Okuyama, Kazumi

2014-07-01

The AdS/CFT correspondence enables us to probe M-theory on various backgrounds from the corresponding dual gauge theories. Here we investigate in detail a three-dimensional U(N) N=4 super Yang-Mills theory coupled to one adjoint hypermultiplet and N f fundamental hypermultiplets, which is large N dual to M-theory on AdS 4 x S 7 /Z N f . Using the localization and the Fermi-gas formulation, we explore non-perturbative corrections to the partition function. As in the ABJM theory, we find that there exists a non-trivial pole cancellation mechanism, which guarantees the theory to be well-defined, between worldsheet instantons and membrane instantons for all rational (in particular, physical or integral) values of N f .

Novel operation and control modes for series-resonant converters

NARCIS (Netherlands)

Haan, de S.W.H.; Huisman, H.

1985-01-01

A series-resonant converter (SRC) able to generate an output voltage either lower or higher than the source voltage is described. Moreover, a novel control scheme is presented which renders two degrees of freedom for control and which guarantees symmetrical steady-state waveforms in all operation

Curvature perturbation spectra from waterfall transition, black hole constraints and non-Gaussianity

Energy Technology Data Exchange (ETDEWEB)

Bugaev, Edgar; Klimai, Peter, E-mail: bugaev@pcbai10.inr.ruhep.ru, E-mail: pklimai@gmail.com [Institute for Nuclear Research, Russian Academy of Sciences, 60th October Anniversary Prospect 7a, 117312 Moscow (Russian Federation)

2011-11-01

We carried out numerical calculations of a contribution of the waterfall field to the primordial curvature perturbation (on uniform density hypersurfaces) ζ, which is produced during waterfall transition in hybrid inflation scenario. The calculation is performed for a broad interval of values of the model parameters. We show that there is a strong growth of amplitudes of the curvature perturbation spectrum in the limit when the bare mass-squared of the waterfall field becomes comparable with the square of Hubble parameter. We show that in this limit the primordial black hole constraints on the curvature perturbations must be taken into account. It is shown that, in the same limit, peak values of the curvature perturbation spectra are far beyond horizon, and the spectra are strongly non-Gaussian.

Curvature perturbation spectra from waterfall transition, black hole constraints and non-Gaussianity

International Nuclear Information System (INIS)

Bugaev, Edgar; Klimai, Peter

2011-01-01

We carried out numerical calculations of a contribution of the waterfall field to the primordial curvature perturbation (on uniform density hypersurfaces) ζ, which is produced during waterfall transition in hybrid inflation scenario. The calculation is performed for a broad interval of values of the model parameters. We show that there is a strong growth of amplitudes of the curvature perturbation spectrum in the limit when the bare mass-squared of the waterfall field becomes comparable with the square of Hubble parameter. We show that in this limit the primordial black hole constraints on the curvature perturbations must be taken into account. It is shown that, in the same limit, peak values of the curvature perturbation spectra are far beyond horizon, and the spectra are strongly non-Gaussian

Ultrasonic series resonant converter with integrated L-C-T

CSIR Research Space (South Africa)

Smit, MC

1995-01-01

Full Text Available primary plate separation, w G bifilar primary 2EOE,NpW(h + To - T;) d C= where d plate width. Fig. 8. SPICE model of discrete component converter ~ 21 B. Spice Simulation The objective of the simulation is to show that the integrated structure... reacts in the same way as a discrete series inductor capacitor and transformer would do, and in turn agrees with the experimental results. Fig. 8 shows the SPICE circuit model of the discrete component series resonant converter. Inductance L...

Non-perturbative treatment of relativistic quantum corrections in large Z atoms

International Nuclear Information System (INIS)

Dietz, K.; Weymans, G.

1983-09-01

Renormalised g-Hartree-Dirac equations incorporating Dirac sea contributions are derived. Their implications for the non-perturbative, selfconsistent calculation of quantum corrections in large Z atoms are discussed. (orig.)

Operation States Analysis of the Series-Parallel resonant Converter Working Above Resonance Frequency

Directory of Open Access Journals (Sweden)

Peter Dzurko

2007-01-01

Full Text Available Operation states analysis of a series-parallel converter working above resonance frequency is described in the paper. Principal equations are derived for individual operation states. On the basis of them the diagrams are made out. The diagrams give the complex image of the converter behaviour for individual circuit parameters. The waveforms may be utilised at designing the inverter individual parts.

The non-linear ion trap. Part 5. Nature of non-linear resonances and resonant ion ejection

Science.gov (United States)

Franzen, J.

1994-01-01

The superposition of higher order multipole fields on the basic quadrupole field in ion traps generates a non-harmonic oscillator system for the ions. Fourier analyses of simulated secular oscillations in non-linear ion traps, therefore, not only reveal the sideband frequencies, well-known from the Mathieu theory, but additionally a commonwealth of multipole-specific overtones (or higher harmonics), and corresponding sidebands of overtones. Non-linear resonances occur when the overtone frequencies match sideband frequencies. It can be shown that in each of the resonance conditions, not just one overtone matches one sideband, instead, groups of overtones match groups of sidebands. The generation of overtones is studied by Fourier analysis of computed ion oscillations in the direction of thez axis. Even multipoles (octopole, dodecapole, etc.) generate only odd orders of higher harmonics (3, 5, etc.) of the secular frequency, explainable by the symmetry with regard to the planez = 0. In contrast, odd multipoles (hexapole, decapole, etc.) generate all orders of higher harmonics. For all multipoles, the lowest higher harmonics are found to be strongest. With multipoles of higher orders, the strength of the overtones decreases weaker with the order of the harmonics. Forz direction resonances in stationary trapping fields, the function governing the amplitude growth is investigated by computer simulations. The ejection in thez direction, as a function of timet, follows, at least in good approximation, the equation wheren is the order of multipole, andC is a constant. This equation is strictly valid for the electrically applied dipole field (n = 1), matching the secular frequency or one of its sidebands, resulting in a linear increase of the amplitude. It is valid also for the basic quadrupole field (n = 2) outside the stability area, giving an exponential increase. It is at least approximately valid for the non-linear resonances by weak superpositions of all higher odd

Non-perturbative Green functions in quantum gauge theories

International Nuclear Information System (INIS)

Shabanov, S.V.

1991-01-01

Non-perturbative Green functions for gauge invariant variables are considered. The Green functions are found to be modified as compared with the usual ones in a definite gauge because of a physical configuration space (PCS) reduction. In the Yang-Mills theory with fermions this phenomenon follows from the Singer theorem about the absence of a global gauge condition for the fields tensing to zero at spatial infinity. 20 refs

A complete non-perturbative renormalization prescription for quasi-PDFs

Energy Technology Data Exchange (ETDEWEB)

Alexandrou, Constantia [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; The Cyprus Institute, Nicosia (Cyprus); Cichy, Krzysztof [Frankfurt Univ. (Germany). Inst. fuer Theoretische Physik; Adam Mickiewicz Univ., Poznan (Poland). Faculty of Physics; Constantinou, Martha [Temple Univ., Philadelphia, PA (United States). Dept. of Physics; Hadjiyiannakou, Kyriakos [The Cyprus Institute, Nicosia (Cyprus); Jansen, Karl; Steffens, Fernanda [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Panagopoulos, Haralambos [Cyprus Univ., Nicosia (Cyprus). Dept. of Physics; Collaboration: European Twisted Mass Collaboration

2017-06-15

In this work we present, for the first time, the non-perturbative renormalization for the unpolarized, helicity and transversity quasi-PDFs, in an RI{sup '} scheme. The proposed prescription addresses simultaneously all aspects of renormalization: logarithmic divergences, finite renormalization as well as the linear divergence which is present in the matrix elements of fermion operators with Wilson lines. Furthermore, for the case of the unpolarized quasi-PDF, we describe how to eliminate the unwanted mixing with the twist-3 scalar operator. We utilize perturbation theory for the one-loop conversion factor that brings the renormalization functions to the MS-scheme at a scale of 2 GeV. We also explain how to improve the estimates on the renormalization functions by eliminating lattice artifacts. The latter can be computed in one-loop perturbation theory and to all orders in the lattice spacing. We apply the methodology for the renormalization to an ensemble of twisted mass fermions with N{sub f}=2+1+1 dynamical quarks, and a pion mass of around 375 MeV.

Non-perturbative solution of a quantum mechanical oscillator interacting with a specific environment

International Nuclear Information System (INIS)

Badralexe, E.; Gupta, R.K.; Scheid, W.

1984-01-01

A quantum mechanical model of an oscillator interacting linearly with an environment is treated by the method of perturbation series expansion. For a special class of environments and interactions, the series is summed up to all orders. An integral equation for the time dependence of the coordinate operator of the oscillator is obtained, which is solved analytically by the method of Laplace transformations. General conditions are stated for a dissipative behaviour of the special class of environments considered. An example, which is widely applicable, is discussed. (author)

A non-perturbative analysis in finite volume gauge theory

International Nuclear Information System (INIS)

Koller, J.; State Univ. of New York, Stony Brook; Van Baal, P.; State Univ. of New York, Stony Brook

1988-01-01

We discuss SU(2) gauge theory on a three-torus using a finite volume expansion. Our discovery of natural coordinates allows us to obtain continuum results in a region where Monte Carlo data are also available. The obtained results agree well with the perturbative and semiclassical analysis for small volumes, and there is fair agreement with the Monte Carlo results in intermediate volumes. The simple picture which emerges for the approximate low energy dynamics is that of three interacting particles enclosed in a sphere, with zero total 'angular momentum'. The validity of an adiabatic approximation is investigated. The fundamentally new understanding gained, is that non-perturbative dynamics can be incorporated by imposing boundary conditions which arise through the nontrivial topology of configuration space. (orig.)

Cosmological perturbations in theories with non-minimal coupling between curvature and matter

International Nuclear Information System (INIS)

Bertolami, Orfeu; Frazão, Pedro; Páramos, Jorge

2013-01-01

In this work, we examine how the presence of a non-minimal coupling between spacetime curvature and matter affects the evolution of cosmological perturbations on a homogeneous and isotropic Universe, and hence the formation of large-scale structure. This framework places constraints on the terms which arise due to the coupling with matter and, in particular, on the modified growth of matter density perturbations. We derive approximate analytical solutions for the evolution of matter overdensities during the matter dominated era and discuss the compatibility of the obtained results with the hypothesis that the late time acceleration of the Universe is driven by a non-minimal coupling

Large N non-perturbative effects in N=4 superconformal Chern-Simons theories

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki; Honda, Masazumi; Okuyama, Kazumi

2015-07-01

We investigate the large N instanton effects of partition functions in a class of N = 4 circular quiver Chern-Simons theories on a three-sphere. Our analysis is based on the supersymmetry localization and the Fermi-gas formalism. The resulting matrix model can be regarded as a two-parameter deformation of the ABJM matrix model, and has richer non-perturbative structures. Based on a systematic semi-classical analysis, we find analytic expressions of membrane instanton corrections. We also exactly compute the partition function for various cases and find some exact forms of worldsheet instanton corrections, which appear as quantum mechanical non-perturbative corrections in the Fermi-gas system.

Correlations in double parton distributions: perturbative and non-perturbative effects

Energy Technology Data Exchange (ETDEWEB)

Rinaldi, Matteo; Scopetta, Sergio [Dipartimento di Fisica e Geologia, Università degli Studi di Perugia andIstituto Nazionale di Fisica Nucleare, Sezione di Perugia, via A. Pascoli, I-06123 Perugia (Italy); Traini, Marco [Institut de Physique Théorique CEA-Saclay, F-91191 Gif-sur-Yvette (France); INFN - TIFPA, Dipartimento di Fisica, Università degli Studi di Trento,Via Sommarive 14, I-38123 Povo (Trento) (Italy); Vento, Vicente [Departament de Física Teòrica, Universitat de València and Institut de Física Corpuscular,Consejo Superior de Investigaciones Científicas, 46100 Carrer del Dr. Moliner 50 València (Spain)

2016-10-12

The correct description of Double Parton Scattering (DPS), which represents a background in several channels for the search of new Physics at the LHC, requires the knowledge of double parton distribution functions (dPDFs). These quantities represent also a novel tool for the study of the three-dimensional nucleon structure, complementary to the possibilities offered by electromagnetic probes. In this paper we analyze dPDFs using Poincaré covariant predictions obtained by using a Light-Front constituent quark model proposed in a recent paper, and QCD evolution. We study to what extent factorized expressions for dPDFs, which neglect, at least in part, two-parton correlations, can be used. We show that they fail in reproducing the calculated dPDFs, in particular in the valence region. Actually measurable processes at existing facilities occur at low longitudinal momenta of the interacting partons; to have contact with these processes we have analyzed correlations between pairs of partons of different kind, finding that, in some cases, they are strongly suppressed at low longitudinal momenta, while for other distributions they can be sizeable. For example, the effect of gluon-gluon correlations can be as large as 20 %. We have shown that these behaviors can be understood in terms of a delicate interference of non-perturbative correlations, generated by the dynamics of the model, and perturbative ones, generated by the model independent evolution procedure. Our analysis shows that at LHC kinematics two-parton correlations can be relevant in DPS, and therefore we address the possibility to study them experimentally.

Analysis and implementation of LLC-T series parallel resonant ...

African Journals Online (AJOL)

A prototype 300 W, 100 kHz converter is designed and built to experimentally demonstrate, dynamic and steady state performance for the LLC-T series parallel resonant converter. A comparative study is performed between experimental results and the simulation studies. The analysis shows that the output of converter is ...

Impact of magnetic perturbation fields on tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Fietz, Sina; Maraschek, Marc; Suttrop, Wolfgang; Zohm, Hartmut [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Classen, Ivo [FOM-Institute DIFFER, Nieuwegein (Netherlands); Collaboration: the ASDEX Upgrade Team

2015-05-01

Non-axisymmetric external magnetic perturbation (MP) fields arise in every tokamak e.g. due to not perfectly positioned external coils. Additionally many tokamaks, like ASDEX Upgrade (AUG), are equipped with a set of external coils, which produce a 3D MP field in addition to the equilibrium field. This field is used to either compensate for the intrinsic MP field or to influence MHD instabilities such as Edge Localised Modes (ELMs) or Neoclassical Tearing Modes (NTMs). But these MP fields can also give rise to a more global plasma response. The resonant components can penetrate the plasma and influence the stability of existing NTMs or even lead to their formation via magnetic reconnection. In addition they exert a local torque on the plasma. These effects are less pronounced at high plasma rotation where the resonant field components are screened. The non-resonant components do not influence NTMs directly but slow down the plasma rotation globally via the neoclassical toroidal viscous torque. The island formation caused by the MP field as well as the interaction of pre-existing islands with the MP field at AUG is presented. It is shown that these effects can be modelled using a simple forced reconnection theory. Also the effect of resonant and non-resonant MPs on the plasma rotation at AUG is discussed.

Subsynchronous resonance - identification of the resonance modes in systems with series compensation; Ressonancia subsincrona - identificacao dos modos ressonantes em sistemas dotados de compensacao-serie

Energy Technology Data Exchange (ETDEWEB)

Rocha, J J [Brasilia Univ., DF (Brazil). Dept. de Engenharia Eletrica; Camargo, B C.C. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Eletrica

1988-12-31

This work shows the phenomenon and mechanism of the subsynchronous resonance, as well as it presents the modelling and simulation of a electromechanics system to verify the adequacy of the use of series capacitor in systems that has turbogenerators 4 refs., 7 figs., 3 tabs.

Perturbation measurement of waveguides for acoustic thermometry

Science.gov (United States)

Lin, H.; Feng, X. J.; Zhang, J. T.

2013-09-01

Acoustic thermometers normally embed small acoustic transducers in the wall bounding a gas-filled cavity resonator. At high temperature, insulators of transducers loss electrical insulation and degrade the signal-to-noise ratio. One essential solution to this technical trouble is to couple sound by acoustic waveguides between resonator and transducers. But waveguide will break the ideal acoustic surface and bring perturbations(Δf+ig) to the ideal resonance frequency. The perturbation model for waveguides was developed based on the first-order acoustic theory in this paper. The frequency shift Δf and half-width change g caused by the position, length and radius of waveguides were analyzed using this model. Six different length of waveguides (52˜1763 mm) were settled on the cylinder resonator and the perturbation (Δf+ig) were measured at T=332 K and p=250˜500 kPa. The experiment results agreed with the theoretical prediction very well.

Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies

International Nuclear Information System (INIS)

Geshnizjani, Ghazal; Kinney, William H.; Dizgah, Azadeh Moradinezhad

2012-01-01

We generalize the cosmological duality between inflation and cyclic contraction under the interchange a↔H to the case of non-canonical scalar field theories with varying speed of sound. The single duality in the canonical case generalizes to a family of three dualities constructed to leave the cosmological acoustic horizon invariant. We find three classes of models: (I) DBI inflation, (II) the non-canonical generalization of cyclic contraction, and (III) a new cosmological solution with rapidly decreasing speed of sound and relatively slowly growing scale factor, which we dub stalled cosmology. We construct dual analogs to the inflationary slow roll approximation, and solve for the curvature perturbation in all three cases. Both cyclic contraction and stalled cosmology predict a strongly blue spectrum for the curvature perturbations inconsistent with observations

Fully nonlinear and exact perturbations of the Friedmann world model: non-flat background

Energy Technology Data Exchange (ETDEWEB)

Noh, Hyerim, E-mail: hr@kasi.ac.kr [Korea Astronomy and Space Science Institute, Daejeon, 305-348 (Korea, Republic of)

2014-07-01

We extend the fully non-linear and exact cosmological perturbation equations in a Friedmann background universe to include the background curvature. The perturbation equations are presented in a gauge ready form, so any temporal gauge condition can be adopted freely depending on the problem to be solved. We consider the scalar, and vector perturbations without anisotropic stress. As an application, we analyze the equations in the special case of irrotational zero-pressure fluid in the comoving gauge condition. We also present the fully nonlinear formulation for a minimally coupled scalar field.

A 10kW series resonant converter design, transistor characterization, and base-drive optimization

Science.gov (United States)

Robson, R.; Hancock, D.

1981-01-01

Transistors are characterized for use as switches in resonant circuit applications. A base drive circuit to provide the optimal base drive to these transistors under resonant circuit conditions is developed and then used in the design, fabrication and testing of a breadboard, spaceborne type 10 kW series resonant converter.

Massive states in chiral perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Mallik, S [Saha Inst. of Nuclear Physics, Calcutta (India)

1995-08-01

It is shown that the chiral nonanalytic terms generated by {Delta}{sub 33} resonance in the nucleon self-energy is reproduced in chiral perturbation theory by perturbing appropriate local operators contained in the pion-nucleon effective Lagrangian itself. (orig.)

Small-signal model for the series resonant converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1985-01-01

The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented.

Non perturbative aspects of strongly correlated electron systems

International Nuclear Information System (INIS)

Controzzi, D.

2000-01-01

In this thesis we report some selected works on Strongly Correlated Electron Systems. A common ingredient of these works is the use of non-perturbative techniques available in low dimensions. In the first part we use the Bethe Ansatz to study some properties of two families of integrable models introduced by Fateev. We calculate the Thermodynamics of the models and show how they can be interpreted as effective Landau-Ginzburg theories for coupled two-dimensional superconductors interacting with an insulating substrate. This allows us to study exactly the dependence of the critical temperature on the thickness of the insulating layer, and on the interaction between the order parameters of two different superconducting planes. In the second part of the thesis we study the optical conductivity of the sine-Gordon model using the Form Factor method and Conformal Perturbation Theory. This allows us to develop, for the first time, a complete theory of the optical conductivity of one-dimensional Mott insulators, in the Quantum Field Theory limit. (author)

Non-perturbative Debye mass in finite-T QCD

CERN Document Server

Kajantie, Keijo; Peisa, J; Rajantie, A; Rummukainen, K; Shaposhnikov, Mikhail E

1997-01-01

Employing a non-perturbative gauge invariant definition of the Debye screening mass m_D in the effective field theory approach to finite T QCD, we use 3d lattice simulations to determine the leading O(g^2) and to estimate the next-to-leading O(g^3) corrections to m_D in the high temperature region. The O(g^2) correction is large and modifies qualitatively the standard power-counting hierarchy picture of correlation lengths in high temperature QCD.

Holomorphic couplings in non-perturbative string compactifications

International Nuclear Information System (INIS)

Klevers, Denis Marco

2011-06-01

In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z 3 , that is canonically constructed from the original five-brane and Calabi-Yau threefold Z 3 via a blow-up. We exploit the use of the blow-up threefold Z 3 as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z 3 as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z 3 , that is generated dynamically by the five-brane backreaction. (orig.)

Non-perturbative background field calculations

International Nuclear Information System (INIS)

Stephens, C.R.; Department of Physics, University of Utah, Salt Lake City, Utah 84112)

1988-01-01

New methods are developed for calculating one loop functional determinants in quantum field theory. Instead of relying on a calculation of all the eigenvalues of the small fluctuation equation, these techniques exploit the ability of the proper time formalism to reformulate an infinite dimensional field theoretic problem into a finite dimensional covariant quantum mechanical analog, thereby allowing powerful tools such as the method of Jacobi fields to be used advantageously in a field theory setting. More generally the methods developed herein should be extremely valuable when calculating quantum processes in non-constant background fields, offering a utilitarian alternative to the two standard methods of calculation: perturbation theory in the background field or taking the background field into account exactly. The formalism developed also allows for the approximate calculation of covariances of partial differential equations from a knowledge of the solutions of a homogeneous ordinary differential equation. copyright 1988 Academic Press, Inc

Non-perturbative background field calculations

Science.gov (United States)

Stephens, C. R.

1988-01-01

New methods are developed for calculating one loop functional determinants in quantum field theory. Instead of relying on a calculation of all the eigenvalues of the small fluctuation equation, these techniques exploit the ability of the proper time formalism to reformulate an infinite dimensional field theoretic problem into a finite dimensional covariant quantum mechanical analog, thereby allowing powerful tools such as the method of Jacobi fields to be used advantageously in a field theory setting. More generally the methods developed herein should be extremely valuable when calculating quantum processes in non-constant background fields, offering a utilitarian alternative to the two standard methods of calculation—perturbation theory in the background field or taking the background field into account exactly. The formalism developed also allows for the approximate calculation of covariances of partial differential equations from a knowledge of the solutions of a homogeneous ordinary differential equation.

Non-perturbative BRST quantization of Euclidean Yang-Mills theories in Curci-Ferrari gauges

Science.gov (United States)

Pereira, A. D.; Sobreiro, R. F.; Sorella, S. P.

2016-10-01

In this paper we address the issue of the non-perturbative quantization of Euclidean Yang-Mills theories in the Curci-Ferrari gauge. In particular, we construct a refined Gribov-Zwanziger action for this gauge, which takes into account the presence of gauge copies as well as the dynamical formation of dimension-two condensates. This action enjoys a non-perturbative BRST symmetry recently proposed in Capri et al. (Phys. Rev. D 92(4), 045039. doi: 10.1103/PhysRevD.92.045039 arXiv:1506.06995 [hep-th], 2015). Finally, we pay attention to the gluon propagator in different space-time dimensions.

Non-perturbative BRST quantization of Euclidean Yang-Mills theories in Curci-Ferrari gauges

International Nuclear Information System (INIS)

Pereira, A.D.; Sobreiro, R.F.; Sorella, S.P.

2016-01-01

In this paper we address the issue of the non-perturbative quantization of Euclidean Yang-Mills theories in the Curci-Ferrari gauge. In particular, we construct a refined Gribov-Zwanziger action for this gauge, which takes into account the presence of gauge copies as well as the dynamical formation of dimension-two condensates. This action enjoys a non-perturbative BRST symmetry recently proposed in Capri et al. (Phys. Rev. D 92(4), 045039. doi:10.1103/PhysRevD.92.045039. arXiv:1506.06995 [hepth], 2015). Finally, we pay attention to the gluon propagator in different space-time dimensions. (orig.)

Non-perturbative BRST quantization of Euclidean Yang-Mills theories in Curci-Ferrari gauges

Energy Technology Data Exchange (ETDEWEB)

Pereira, A.D. [UFF, Universidade Federal Fluminense, Instituto de Fisica, Campus da Praia Vermelha, Niteroi, RJ (Brazil); Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Potsdam (Germany); UERJ, Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro (Brazil); Sobreiro, R.F. [UFF, Universidade Federal Fluminense, Instituto de Fisica, Campus da Praia Vermelha, Niteroi, RJ (Brazil); Sorella, S.P. [UERJ, Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro (Brazil)

2016-10-15

In this paper we address the issue of the non-perturbative quantization of Euclidean Yang-Mills theories in the Curci-Ferrari gauge. In particular, we construct a refined Gribov-Zwanziger action for this gauge, which takes into account the presence of gauge copies as well as the dynamical formation of dimension-two condensates. This action enjoys a non-perturbative BRST symmetry recently proposed in Capri et al. (Phys. Rev. D 92(4), 045039. doi:10.1103/PhysRevD.92.045039. arXiv:1506.06995 [hepth], 2015). Finally, we pay attention to the gluon propagator in different space-time dimensions. (orig.)

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

International Nuclear Information System (INIS)

Vrscay, E.R.

1986-01-01

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

Mathematical Model of Thyristor Inverter Including a Series-parallel Resonant Circuit

OpenAIRE

Miroslaw Luft; Elzbieta Szychta

2008-01-01

The article presents a mathematical model of thyristor inverter including a series-parallel resonant circuit with theaid of state variable method. Maple procedures are used to compute current and voltage waveforms in the inverter.

Non-axisymmetric line-driven disc winds - I. Disc perturbations

Science.gov (United States)

Dyda, Sergei; Proga, Daniel

2018-04-01

We study mass outflows driven from accretion discs by radiation pressure due to spectral lines. To investigate non-axisymmetric effects, we use the ATHENA++ code and develop a new module to account for radiation pressure driving. In 2D, our new simulations are consistent with previous 2D axisymmetric solutions by Proga et al., who used the ZEUS 2D code. Specifically, we find that the disc winds are time dependent, characterized by a dense stream confined to ˜45° relative to the disc mid-plane and bounded on the polar side by a less dense, fast stream. In 3D, we introduce a vertical, ϕ-dependent, subsonic velocity perturbation in the disc mid-plane. The perturbation does not change the overall character of the solution but global outflow properties such as the mass, momentum, and kinetic energy fluxes are altered by up to 100 per cent. Non-axisymmetric density structures develop and persist mainly at the base of the wind. They are relatively small, and their densities can be a few times higher than the azimuthal average. The structure of the non-axisymmetric and axisymmetric solutions differ also in other ways. Perhaps most importantly from the observational point of view are the differences in the so-called clumping factors, that serve as a proxy for emissivity due to two body processes. In particular, the spatially averaged clumping factor over the entire fast stream, while it is of a comparable value in both solutions, it varies about 10 times faster in the non-axisymmetric case.

Non-perturbative plaquette in 3d pure SU(3)

CERN Document Server

Hietanen, A; Laine, Mikko; Rummukainen, K; Schröder, Y

2005-01-01

We present a determination of the elementary plaquette and, after the subsequent ultraviolet subtractions, of the finite part of the gluon condensate, in lattice regularization in three-dimensional pure SU(3) gauge theory. Through a change of regularization scheme to MSbar and a matching back to full four-dimensional QCD, this result determines the first non-perturbative contribution in the weak-coupling expansion of hot QCD pressure.

Mathematical model of thyristor inverter including a series-parallel resonant circuit

OpenAIRE

Luft, M.; Szychta, E.

2008-01-01

The article presents a mathematical model of thyristor inverter including a series-parallel resonant circuit with the aid of state variable method. Maple procedures are used to compute current and voltage waveforms in the inverter.

Robust Forecasting of Non-Stationary Time Series

NARCIS (Netherlands)

Croux, C.; Fried, R.; Gijbels, I.; Mahieu, K.

2010-01-01

This paper proposes a robust forecasting method for non-stationary time series. The time series is modelled using non-parametric heteroscedastic regression, and fitted by a localized MM-estimator, combining high robustness and large efficiency. The proposed method is shown to produce reliable

Eisenstein series for infinite-dimensional U-duality groups

Science.gov (United States)

Fleig, Philipp; Kleinschmidt, Axel

2012-06-01

We consider Eisenstein series appearing as coefficients of curvature corrections in the low-energy expansion of type II string theory four-graviton scattering amplitudes. We define these Eisenstein series over all groups in the E n series of string duality groups, and in particular for the infinite-dimensional Kac-Moody groups E 9, E 10 and E 11. We show that, remarkably, the so-called constant term of Kac-Moody-Eisenstein series contains only a finite number of terms for particular choices of a parameter appearing in the definition of the series. This resonates with the idea that the constant term of the Eisenstein series encodes perturbative string corrections in BPS-protected sectors allowing only a finite number of corrections. We underpin our findings with an extensive discussion of physical degeneration limits in D < 3 space-time dimensions.

Resummation of the QCD perturbative series for hard processes

International Nuclear Information System (INIS)

Catani, S.

1989-01-01

We study the region of inhibited radiation in hard hadronic processes, as for jet cross sections and heavy flavour production near threshold. The cases of deep inelastic scattering and Drell-Yan annihilation are explicitly considered. A general method to exponentiate leading and next-to-leading logarithms to all orders in perturbation theory is developed. A complete formula for the large N-moments is given and shown to agree with previous two-loop calculations. The resummation procedure suggests how to connect the perturbative and nonperturbative regions. The natural limit within the perturbative phase is shown to be the intrinsic transverse momentum. (orig.)

Resonance in the restricted problem caused by solar radiation pressure

International Nuclear Information System (INIS)

Bhatnagar, K.B.; Gupta, B.

1977-01-01

Resonance is discussed in the motion of an artificial Earth satellite caused by solar radiation pressure. The Hamiltonian and the generating functions occurring in the problem are expanded in the power series of small parameter β, which depends on solar radiation pressure. Also the perturbations in the osculating elements are obtained up to O(βsup(1/2)). (author)

Optimal trajectory control of a series-resonant inverter with a non-linear resonant inductor

NARCIS (Netherlands)

Huisman, H.; Baskurt, F.; Bouloukos, A; Baars, N.H.; Lomonova, E.A.

2017-01-01

ies-Resonant (SR) converters have been used as building blocks for DC-AC and DC-DC power converters for at least half a century. Applications were first found in induction heating [1], where generating a substantial AC current at moderately high frequency was required by the application. Later, the

Holomorphic couplings in non-perturbative string compactifications

Energy Technology Data Exchange (ETDEWEB)

Klevers, Denis Marco

2011-06-15

In this thesis we present an analysis of several aspects of four-dimensional, non-perturbative N = 1 compactifications of string theory. Our focus is on the study of brane dynamics and their effective physics as encoded in the holomorphic couplings of the low-energy N=1 effective action, most prominently the superpotential W. The thesis is divided into three parts. In part one we derive the effective action of a spacetime-filling D5-brane in generic Type IIB Calabi-Yau orientifold compactifications. In the second part we invoke tools from string dualities, namely from F-theory, heterotic/F-theory duality and mirror symmetry, for a more elaborate study of the dynamics of (p, q) 7-branes and heterotic five-branes. In this context we demonstrate exact computations of the complete perturbative effective superpotential, both due to branes and background fluxes. Finally, in the third part we present a novel geometric description of five-branes in Type IIB and heterotic M-theory Calabi-Yau compactifications via a non-Calabi-Yau threefold Z{sub 3}, that is canonically constructed from the original five-brane and Calabi-Yau threefold Z{sub 3} via a blow-up. We exploit the use of the blow-up threefold Z{sub 3} as a tool to derive open-closed Picard-Fuchs differential equations, that govern the complete effective brane and flux superpotential. In addition, we present first evidence to interpret Z{sub 3} as a flux compactification dual to the original five-brane by defining an SU(3)-structure on Z{sub 3}, that is generated dynamically by the five-brane backreaction. (orig.)

Mathematical Model of Thyristor Inverter Including a Series-parallel Resonant Circuit

Directory of Open Access Journals (Sweden)

Miroslaw Luft

2008-01-01

Full Text Available The article presents a mathematical model of thyristor inverter including a series-parallel resonant circuit with theaid of state variable method. Maple procedures are used to compute current and voltage waveforms in the inverter.

A non-perturbative study of massive gauge theories

DEFF Research Database (Denmark)

Della Morte, Michele; Hernandez, Pilar

2013-01-01

and the lightest degrees of freedom are spin one vector particles with the same quantum numbers as the conserved current, we argue that the most general effective theory describing their low-energy dynamics must be a massive gauge theory. We present results of a exploratory numerical simulation of the model......We consider a non-perturbative formulation of an SU(2) massive gauge theory on a space-time lattice, which is also a discretised gauged non-linear chiral model. The lattice model is shown to have an exactly conserved global SU(2) symmetry. If a scaling region for the lattice model exists...... and find indications for the presence of a scaling region where both a triplet vector and a scalar remain light....

The effect of resonant magnetic perturbations on the divertor heat and particle fluxes in MAST

Czech Academy of Sciences Publication Activity Database

Thornton, A.J.; Kirk, A.; Cahyna, Pavel; Chapman, I.T.; Harrison, J.R.; Liu, Y.

2014-01-01

Roč. 54, č. 6 (2014), 064011-064011 ISSN 0029-5515. [International Workshop on Stochasticity in Fusion Plasmas /6./. Jülich, 18.03.2013-20.03.2013] R&D Projects: GA ČR GAP205/11/2341 Institutional support: RVO:61389021 Keywords : divertor * edge localized mode * resonant magnetic perturbation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.062, year: 2014 http://iopscience.iop.org/0029-5515/54/6/064011/pdf/0029-5515_54_6_064011.pdf

Non-perturbative subtractions in the heavy quark effective field theory

International Nuclear Information System (INIS)

Maiani, L.; Martinelli, G.; Sachrajda, C.T.

1992-01-01

We demonstrate the presence of ultraviolet power divergences in the O(1/m h ) corrections to matrix elements of hadronic operators containing a heavy quark field (where m h is the mass of the heavy quark). These power divergences must be subtracted non-perturbatively. The implications for lattice computations are discussed in detail. (orig.)

On the summation of divergent perturbation series in quantum mechanics and field theory

International Nuclear Information System (INIS)

Kazakov, D.I.; Popov, V.S.

2002-01-01

The possibility of recovering the Gell-Mann-Low function in the asymptotic strong-coupling regime by known first-order perturbation-theory (PT) terms β n and their asymptotics β-tilde n as n → ∞ is investigated. Conditions are formulated that are necessary for recovering the required function at the physical level of rigor: (1) a large number of PT coefficients are known whose asymptotics has already been established, and (2) there is no intermediate asymptotics. Higher orders of PT, their asymptotic behavior, and power corrections are calculated in quantum mechanical problems that involve divergent PT series (including series for a funnel potential, the φ 4 (0) model, and the Stark effect in a strong field). The scalar field theory φ 4 (4) is considered in the MS and MOM regularization schemes. It is shown that one cannot make any definite conclusion about the asymptotics of the Gell-Mann-Low function as g → ∞ on the basis of information available for the above theory

Wilson loops in very high order lattice perturbation theory

International Nuclear Information System (INIS)

Ilgenfritz, E.M.; Nakamura, Y.; Perlt, H.; Schiller, A.; Rakow, P.E.L.; Schierholz, G.; Regensburg Univ.

2009-10-01

We calculate Wilson loops of various sizes up to loop order n=20 for lattice sizes of L 4 (L=4,6,8,12) using the technique of Numerical Stochastic Perturbation Theory in quenched QCD. This allows to investigate the behaviour of the perturbative series at high orders. We discuss three models to estimate the perturbative series: a renormalon inspired fit, a heuristic fit based on an assumed power-law singularity and boosted perturbation theory. We have found differences in the behavior of the perturbative series for smaller and larger Wilson loops at moderate n. A factorial growth of the coefficients could not be confirmed up to n=20. From Monte Carlo measured plaquette data and our perturbative result we estimate a value of the gluon condensate left angle (α)/(π)GG right angle. (orig.)

Entanglement Evolution of Jaynes-Cummings Model in Resonance Case and Non-resonance Case

Science.gov (United States)

Cheng, Jing; Chen, Xi; Shan, Chuan-Jia

2018-03-01

We investigate the entanglement evolution of a two-level atom and a quantized single model electromagnetic filed in the resonance and non-resonance cases. The effects of the initial state, detuning degree, photon number on the entanglement are shown in detail. The results show that the atom-cavity entanglement state appears with periodicity. The increasing of the photon number can make the period of quantum entanglement be shorter. In the non-resonant case, if we choose the suitable initial state the entanglement of atom-cavity can be 1.0

Magnetic resonance imaging detects placental hypoxia and acidosis in mouse models of perturbed pregnancies.

Directory of Open Access Journals (Sweden)

Gabriele Bobek

Full Text Available Endothelial dysfunction as a result of dysregulation of anti-angiogenic molecules secreted by the placenta leads to the maternal hypertensive response characteristic of the pregnancy complication of preeclampsia. Structural abnormalities in the placenta have been proposed to result in altered placental perfusion, placental oxidative stress, cellular damage and inflammation and the release of anti-angiogenic compounds into the maternal circulation. The exact link between these factors is unclear. Here we show, using Magnetic Resonance Imaging as a tool to examine placental changes in mouse models of perturbed pregnancies, that T 2 contrast between distinct regions of the placenta is abolished at complete loss of blood flow. Alterations in T 2 (spin-spin or transverse relaxation times are explained as a consequence of hypoxia and acidosis within the tissue. Similar changes are observed in perturbed pregnancies, indicating that acidosis as well as hypoxia may be a feature of pregnancy complications such as preeclampsia and may play a prominent role in the signalling pathways that lead to the increased secretion of anti-angiogenic compounds.

Perturbation theory for arbitrary coupling strength?

Science.gov (United States)

Mahapatra, Bimal P.; Pradhan, Noubihary

2018-03-01

We present a new formulation of perturbation theory for quantum systems, designated here as: “mean field perturbation theory” (MFPT), which is free from power-series-expansion in any physical parameter, including the coupling strength. Its application is thereby extended to deal with interactions of arbitrary strength and to compute system-properties having non-analytic dependence on the coupling, thus overcoming the primary limitations of the “standard formulation of perturbation theory” (SFPT). MFPT is defined by developing perturbation about a chosen input Hamiltonian, which is exactly solvable but which acquires the nonlinearity and the analytic structure (in the coupling strength) of the original interaction through a self-consistent, feedback mechanism. We demonstrate Borel-summability of MFPT for the case of the quartic- and sextic-anharmonic oscillators and the quartic double-well oscillator (QDWO) by obtaining uniformly accurate results for the ground state of the above systems for arbitrary physical values of the coupling strength. The results obtained for the QDWO may be of particular significance since “renormalon”-free, unambiguous results are achieved for its spectrum in contrast to the well-known failure of SFPT in this case.

Equation-of-motion coupled cluster perturbation theory revisited

DEFF Research Database (Denmark)

Eriksen, Janus Juul; Jørgensen, Poul; Olsen, Jeppe

2014-01-01

The equation-of-motion coupled cluster (EOM-CC) framework has been used for deriving a novel series of perturbative corrections to the coupled cluster singles and doubles energy that formally con- verges towards the full configuration interaction energy limit. The series is based on a Møller-Ples......-Plesset partitioning of the Hamiltonian and thus size extensive at any order in the perturbation, thereby rem- edying the major deficiency inherent to previous perturbation series based on the EOM-CC ansatz. © 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4873138]...

Non-perturbative O(a) improvement of lattice QCD

CERN Document Server

Lüscher, Martin; Sommer, Rainer; Weisz, P; Wolff, U; Luescher, Martin; Sint, Stefan; Sommer, Rainer; Weisz, Peter; Wolff, Ulli

1997-01-01

The coefficients multiplying the counterterms required for O($a$) improvement of the action and the isovector axial current in lattice QCD are computed non-perturbatively, in the quenched approximation and for bare gauge couplings $g_0$ in the range $0 \\leq g_0 \\leq 1$. A finite-size method based on the Schrödinger functional is employed, which enables us to perform all calculations at zero or nearly zero quark mass. As a by-product the critical hopping parameter $\\kappa_c$ is obtained at all couplings considered.

Random surfaces: A non-perturbative regularization of strings?

International Nuclear Information System (INIS)

Ambjoern, J.

1989-12-01

I review the basic properties of the theory of randum surfaces. While it is by now well known that the theory of (discretized) random surfaces correctly describes the (perturbative) aspects of non-critical strings in d 1. In these lectures I intend to show that the theory of dynamical triangulated random surfaces provides us with a lot of information about the dynamics of both the bosonic string and the superstring even for d>1. I also briefly review recent attempts to define a string field theory (sum over all genus) in this approach. (orig.)

A normalized model for the half-bridge series resonant converter

Science.gov (United States)

King, R.; Stuart, T. A.

1981-01-01

Closed-form steady-state equations are derived for the half-bridge series resonant converter with a rectified (dc) load. Normalized curves for various currents and voltages are then plotted as a function of the circuit parameters. Experimental results based on a 10-kHz converter are presented for comparison with the calculations.

Non-perturbative approach to 2D-supergravity and super-Virasoro constraints

CERN Document Server

Becker, M

1994-01-01

The coupling of N=1 SCFT of type (4m,2) to two-dimensional supergravity can be formulated non-perturbatively in terms of a discrete super-eigenvalue model proposed by Alvarez-Gaum\\'e, et al. We derive the superloop equations that describe, in the double scaling limit, the non-perturbative solution of this model. These equations are equivalent to the double scaled super-Virasoro constraints satisfied by the partition function. They are formulated in terms of a \\widehat c=1 theory, with a \\IZ_2-twisted scalar field and a Weyl-Majorana fermion in the Ramond sector. We have solved the superloop equations to all orders in the genus expansion and obtained the explicit expressions for the correlation functions of gravitationally dressed scaling operators in the NS- and R-sector. In the double scaling limit, we obtain a formulation of the model in terms of a new supersymmetric extension of the KdV hierarchy.

Dynamical generation of non-abelian gauge group via the improved perturbation theory

International Nuclear Information System (INIS)

Kuroki, Tsunehide

2008-01-01

It was suggested that the massive Yang-Mills-Chern-Simons matrix model has three phases and that in one of them a non-Abelian gauge symmetry is dynamically generated. The analysis was at the one-loop level around a classical solution of fuzzy sphere type. We obtain evidences that three phases are indeed realized as nonperturbative vacua by using the improved perturbation theory. It gives a good example that even if we start from a trivial vacuum, the improved perturbation theory around it enables us to observe nontrivial vacua. (author)

Robust Forecasting of Non-Stationary Time Series

OpenAIRE

Croux, C.; Fried, R.; Gijbels, I.; Mahieu, K.

2010-01-01

This paper proposes a robust forecasting method for non-stationary time series. The time series is modelled using non-parametric heteroscedastic regression, and fitted by a localized MM-estimator, combining high robustness and large efficiency. The proposed method is shown to produce reliable forecasts in the presence of outliers, non-linearity, and heteroscedasticity. In the absence of outliers, the forecasts are only slightly less precise than those based on a localized Least Squares estima...

CP violation induced by the double resonance for pure annihilation decay process in perturbative QCD

Energy Technology Data Exchange (ETDEWEB)

Lue, Gang; Li, Sheng-Tao; Wang, Yu-Ting [Henan University of Technology, College of Science, Zhengzhou (China); Lu, Ye [Guangxi Normal University, Department of Physics, Guilin (China)

2017-08-15

In a perturbative QCD approach we study the direct CP violation in the pure annihilation decay process of anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -} induced by the ρ and ω double resonance effect. Generally, the CP violation is small in the pure annihilation type decay process. However, we find that the CP violation can be enhanced by double ρ-ω interference when the invariant masses of the π{sup +}π{sup -} pairs are in the vicinity of the ω resonance. For the decay process of anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -}, the CP violation can reach A{sub CP}(anti B{sup 0}{sub s} → π{sup +}π{sup -}π{sup +}π{sup -}) = 27.20{sup +0.05+0.28+7.13}{sub -0.15-0.31-6.11}%. (orig.)

Gauge-invariant non-spherical metric perturbations of Schwarzschild black-hole spacetimes

International Nuclear Information System (INIS)

Nagar, Alessandro; Rezzolla, Luciano

2005-01-01

The theory of gauge-invariant non-spherical metric perturbations of Schwarzschild black-hole spacetimes is now well established. Yet, as different notations and conventions have been used throughout the years, the literature on the subject is often confusing and sometimes confused. The purpose of this review is to review and collect the relevant expressions related to the Regge-Wheeler and Zerilli equations for the odd and even-parity perturbations of a Schwarzschild spacetime. Special attention is paid to the form they assume in the presence of matter-sources and, for the two most popular conventions in the literature, to the asymptotic expressions and gravitational-wave amplitudes. Besides pointing out some inconsistencies in the literature, the expressions collected here could serve as a quick reference for the calculation of the perturbations of a Schwarzschild black-hole spacetime driven by generic sources and for those approaches in which gravitational waves are extracted from numerically generated spacetimes. (topical review)

Non-perturbative renormalization of three-quark operators

Energy Technology Data Exchange (ETDEWEB)

Goeckeler, Meinulf [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Horsley, Roger [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Kaltenbrunner, Thomas [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

2008-10-15

High luminosity accelerators have greatly increased the interest in semi-exclusive and exclusive reactions involving nucleons. The relevant theoretical information is contained in the nucleon wavefunction and can be parametrized by moments of the nucleon distribution amplitudes, which in turn are linked to matrix elements of local three-quark operators. These can be calculated from first principles in lattice QCD. Defining an RI-MOM renormalization scheme, we renormalize three-quark operators corresponding to low moments non-perturbatively and take special care of the operator mixing. After performing a scheme matching and a conversion of the renormalization scale we quote our final results in the MS scheme at {mu}=2 GeV. (orig.)

A non-perturbative approach to the Coleman-Weinberg mechanism in massless scalar QED

International Nuclear Information System (INIS)

Malbouisson, A.P.C.; Nogueira, F.S.; Svaiter, N.F.

1995-08-01

We rederived non-perturbatively the Coleman-Weinberg expression for the effective potential for massless scalar QED. Our result is not restricted to small values of the coupling constants. This shows that the Coleman-Weinberg result can be established beyond the range of perturbation theory. Also, we derive it in a manifestly renormalization group invariant way. It is shown that with the derivation given no Landau ghost singularity arises. The finite temperature case is discussed. (author). 13 refs

Utilization of the series resonant dc link converter as a conditioning system for SMES

International Nuclear Information System (INIS)

Marschke, K.W.; Caldeira, P.P.A.; Lipo, T.A.

1992-01-01

In this paper a new superconductive magnetic energy storage (SMES) system utilizes a high-frequency series resonant dc link power converter of high efficiency as the conditioning converter is presented. This system generates a high-frequency (20 kHz or more) resonant current in a series link and switching is done at zero current instants, reducing switching losses to a minimal value. Through the utilization of an adequate control strategy, the input power factor can be fully adjusted during the charging, storing, and discharging modes of the SMES, improving the overall system efficiency. Different semiconductor devices are employed as the switching elements of the resonant converter and switching losses are established for each case. Experimental results from a monophase and three-phase system verified the results obtained from digital simulation

Instantons and Borel resummability for the perturbed supersymmetric anharmonic oscillator

International Nuclear Information System (INIS)

Verbaarschot, J.J.M.; West, P.

1991-01-01

In this paper we give an analytical derivation of the large-order behavior of the perturbation series for both the ground state and the excited states of the supersymmetric anharmonic oscillator and of the anharmonic oscillator obtained from the supersymmetric case by varying the strength of the fermion coupling. The results which are obtained with the help of instanton calculus coincide with those obtained numerically in previous work. The large-order perturbation series of the ground state vanishes in the supersymmetric case, whereas away from the supersymmetric point the perturbation series diverges factorially. The perturbation series of the excited states diverges factorially both at the supersymmetric point and away from this point

Higher order perturbation theory applied to radiative transfer in non-plane-parallel media

International Nuclear Information System (INIS)

Box, M.A.; Polonsky, I.N.; Davis, A.B.

2003-01-01

Radiative transfer in non-plane-parallel media is a very challenging problem, which is currently the subject of concerted efforts to develop computational techniques which may be used to tackle different tasks. In this paper we develop the full formalism for another technique, based on radiative perturbation theory. With this approach, one starts with a plane-parallel 'base model', for which many solution techniques exist, and treat the horizontal variability as a perturbation. We show that under the most logical assumption as to the base model, the first-order perturbation term is zero for domain-average radiation quantities, so that it is necessary to go to higher order terms. This requires the computation of the Green's function. While this task is by no means simple, once the various pieces have been assembled they may be re-used for any number of perturbations--that is, any horizontal variations

M{sub b} and f{sub B} from non-perturbatively renormalized HQET with N{sub f} = 2 light quarks

Energy Technology Data Exchange (ETDEWEB)

Blossier, Benoit [CNRS et Univ. Paris-Sud XI, Orsay (France). Lab. de Physique Theorique; Bulava, John [CERN, Geneva (Switzerland). Physics Dept.; Della Morte, Michele; Hippel, Georg von [Mainz Univ. (Germany). Inst. fuer Kernphysik; Donnellan, Michael; Simma, Hubert; Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). NIC; Fritzsch, Patrick [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Garron, Nicolas [Edinburgh Univ. (United Kingdom). Tait Inst.; Heitger, Jochen [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1

2011-12-15

We present an updated analysis of the non-perturbatively renormalized b-quark mass and B meson decay constant based on CLS lattices with two dynamical non-perturbatively improved Wilson quarks. This update incorporates additional light quark masses and lattice spacings in large physical volume to improve chiral extrapolations and to reach the continuum limit. We use Heavy Quark Effective Theory (HQET) including 1/m{sub b} terms with non-perturbative coefficients based on the matching of QCD and HQET developed by the ALPHA collaboration during the past years. (orig.)

Linear and non-linear amplification of high-mode perturbations at the ablation front in HiPER targets

Energy Technology Data Exchange (ETDEWEB)

Olazabal-Loume, M; Breil, J; Hallo, L; Ribeyre, X [CELIA, UMR 5107 Universite Bordeaux 1-CNRS-CEA, 351 cours de la Liberation, 33405 Talence (France); Sanz, J, E-mail: olazabal@celia.u-bordeaux1.f [ETSI Aeronauticos, Universidad Politecnica de Madrid, Madrid 28040 (Spain)

2011-01-15

The linear and non-linear sensitivity of the 180 kJ baseline HiPER target to high-mode perturbations, i.e. surface roughness, is addressed using two-dimensional simulations and a complementary analysis by linear and non-linear ablative Rayleigh-Taylor models. Simulations provide an assessment of an early non-linear stage leading to a significant deformation of the ablation surface for modes of maximum linear growth factor. A design using a picket prepulse evidences an improvement in the target stability inducing a delay of the non-linear behavior. Perturbation evolution and shape, evidenced by simulations of the non-linear stage, are analyzed with existing self-consistent non-linear theory.

Non-perturbative aspects of quantum field theory. From the quark-gluon plasma to quantum gravity

International Nuclear Information System (INIS)

Christiansen, Nicolai

2015-01-01

In this dissertation we investigate several aspects of non-perturbative quantum field theory. Two main parts of the thesis are concerned with non-perturbative renormalization of quantum gravity within the asymptotic safety scenario. This framework is based on a non-Gaussian ultraviolet fixed point and provides a well-defined theory of quantized gravity. We employ functional renormalization group (FRG) techniques that allow for the study of quantum fields even in strongly coupled regimes. We construct a setup for the computation of graviton correlation functions and analyze the ultraviolet completion of quantum gravity in terms of the properties of the two- and three point function of the graviton. Moreover, the coupling of gravity to Yang-Mills theories is discussed. In particular, we study the effects of graviton induced interactions on asymptotic freedom on the one hand, and the role of gluonic fluctuations in the gravity sector on the other hand. The last subject of this thesis is the physics of the quark-gluon plasma. We set-up a general non-perturbative strategy for the computation of transport coefficients in non-Abelian gauge theories. We determine the viscosity over entropy ratio η/s in SU(3) Yang-Mills theory as a function of temperature and estimate its behavior in full quantum chromodynamics (QCD).

Towards understanding edge localised mode mitigation by resonant magnetic perturbations in MAST

Energy Technology Data Exchange (ETDEWEB)

Chapman, I. T.; Kirk, A.; Ham, C. J.; Harrison, J. R.; Liu, Y. Q.; Saarelma, S.; Scannell, R.; Thornton, A. J.; Team, MAST [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Becoulet, M.; Orain, F. [Association Euratom/CEA, CEA Cadarache, IRFM, F-13108, St. Paul-lez-Durance (France); Cooper, W. A. [CRPP, Association EURATOM/Confédération Suisse, EPFL, 1015 Lausanne (Switzerland); Pamela, S. [IIFS-PIIM. Aix Marseille Université—CNRS, 13397 Marseille Cedex 20 (France)

2013-05-15

Type-I Edge Localised Modes (ELMs) have been mitigated in MAST through the application of n=3,4, and 6 resonant magnetic perturbations. For each toroidal mode number of the non-axisymmetric applied fields, the frequency of the ELMs has been increased significantly, and the peak heat flux on the divertor plates reduced commensurately. This increase in ELM frequency occurs despite a significant drop in the edge pressure gradient, which would be expected to stabilise the peeling-ballooning modes thought to be responsible for type-I ELMs. Various mechanisms which could cause a destabilisation of the peeling-ballooning modes are presented, including pedestal widening, plasma rotation braking, three dimensional corrugation of the plasma boundary, and the existence of radially extended lobe structures near to the X-point. This leads to a model aimed at resolving the apparent dichotomy of ELM control, which is to say ELM suppression occurring due to the pedestal pressure reduction below the peeling-ballooning stability boundary, whilst the reduction in pressure can also lead to ELM mitigation, which is ostensibly a destabilisation of peeling-ballooning modes. In the case of ELM mitigation, the pedestal broadening, 3d corrugation, or lobes near the X-point degrade ballooning stability so much that the pedestal recovers rapidly to cross the new stability boundary at lower pressure more frequently, whilst in the case of suppression, the plasma parameters are such that the particle transport reduces the edge pressure below the stability boundary, which is only mildly affected by negligible rotation braking, small edge corrugation or short, broad lobe structures.

Perturbation of a Schwarzschild Black Hole Due to a Rotating Thin Disk

Energy Technology Data Exchange (ETDEWEB)

Čížek, P.; Semerák, O., E-mail: oldrich.semerak@mff.cuni.cz [Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University, Prague (Czech Republic)

2017-09-01

Will, in 1974, treated the perturbation of a Schwarzschild black hole due to a slowly rotating, light, concentric thin ring by solving the perturbation equations in terms of a multipole expansion of the mass-and-rotation perturbation series. In the Schwarzschild background, his approach can be generalized to perturbation by a thin disk (which is more relevant astrophysically), but, due to rather bad convergence properties, the resulting expansions are not suitable for specific (numerical) computations. However, we show that Green’s functions, represented by Will’s result, can be expressed in closed form (without multipole expansion), which is more useful. In particular, they can be integrated out over the source (a thin disk in our case) to yield good converging series both for the gravitational potential and for the dragging angular velocity. The procedure is demonstrated, in the first perturbation order, on the simplest case of a constant-density disk, including the physical interpretation of the results in terms of a one-component perfect fluid or a two-component dust in a circular orbit about the central black hole. Free parameters are chosen in such a way that the resulting black hole has zero angular momentum but non-zero angular velocity, as it is just carried along by the dragging effect of the disk.

Comments on exact quantization conditions and non-perturbative topological strings

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki

2015-12-01

We give some remarks on exact quantization conditions associated with quantized mirror curves of local Calabi-Yau threefolds, conjectured in arXiv:1410.3382. It is shown that they characterize a non-perturbative completion of the refined topological strings in the Nekrasov-Shatashvili limit. We find that the quantization conditions enjoy an exact S-dual invariance. We also discuss Borel summability of the semi-classical spectrum.

Perturbation series at large orders in quantum mechanics and field theories: application to the problem of resummation

International Nuclear Information System (INIS)

Zinn-Justin, J.; Freie Univ. Berlin

1981-01-01

In this review I present a method to estimate the large order behavior of perturbation theory in quantum mechanics and field theory. The basic idea, due to Lipatov, is to relate the large order behavior to (in general complex) instanton contributions to the path integral representation of Green's functions. I explain the method first in the case of a simple integral and of the anharmonic oscillator and recover the results of Bender and Wu. I apply it then to the PHI 4 field theory. I study general potentials and boson field theories. I show, following Parisi, how the method can be generalized to theories with fermions. Finally I outline the implications of these results for the summability of the series. In particular I explain a method to sum divergent series based on a Borel transformation. In a last section I compare the larger order behavior predictions to actual series calculation. I present also some numerical examples of series summation. (orig.)

Non-perturbative renormalization of the static vector current and its O(a)-improvement in quenched QCD

Energy Technology Data Exchange (ETDEWEB)

Palombi, F.

2007-06-15

We carry out the renormalization and the Symanzik O(a)-improvement programme for the static vector current in quenched lattice QCD. The scale independent ratio of the renormalization constants of the static vector and axial currents is obtained non-perturbatively from an axial Ward identity with Wilson-type light quarks and various lattice discretizations of the static action. The improvement coefficients c{sub V}{sup stat} and b{sub V}{sup stat} are obtained up to O(g{sub 4}{sup 0})-terms by enforcing improvement conditions respectively on the axial Ward identity and a three-point correlator of the static vector current. A comparison between the non-perturbative estimates and the corresponding one-loop results shows a non-negligible effect of the O(g{sub 4}{sup 0})-terms on the improvement coefficients but a good accuracy of the perturbative description of the ratio of the renormalization constants. (orig.)

Non-standard perturbative methods for the effective potential in λφ4 QFT

International Nuclear Information System (INIS)

Okopinska, A.

1986-07-01

The effective potential in scalar QFT is calculated in the non-standard perturbative methods and compared with the conventional loop expansion. In the space time dimensions 0 and 1 the results are compared with the ''exact'' effective potential obtained numerically. In 4 dimensions we show that λφ 4 theory is non-interacting. (author)

World-Line Formalism: Non-Perturbative Applications

Directory of Open Access Journals (Sweden)

Dmitry Antonov

2016-11-01

Full Text Available This review addresses the impact on various physical observables which is produced by confinement of virtual quarks and gluons at the level of the one-loop QCD diagrams. These observables include the quark condensate for various heavy flavors, the Yang-Mills running coupling with an infra-red stable fixed point, and the correlation lengths of the stochastic Yang-Mills fields. Other non-perturbative applications of the world-line formalism presented in the review are devoted to the determination of the electroweak phase-transition critical temperature, to the derivation of a semi-classical analogue of the relation between the chiral and the gluon QCD condensates, and to the calculation of the free energy of the gluon plasma in the high-temperature limit. As a complementary result, we demonstrate Casimir scaling of k-string tensions in the Gaussian ensemble of the stochastic Yang-Mills fields.

Non-perturbative description of quantum systems

CERN Document Server

Feranchuk, Ilya; Le, Van-Hoang; Ulyanenkov, Alexander

2015-01-01

This book introduces systematically the operator method for the solution of the Schrödinger equation. This method permits to describe the states of quantum systems in the entire range of parameters of Hamiltonian with a predefined accuracy. The operator method is unique compared with other non-perturbative methods due to its ability to deliver in zeroth approximation the uniformly suitable estimate for both ground and excited states of quantum system. The method has been generalized for the application to quantum statistics and quantum field theory.  In this book, the numerous applications of operator method for various physical systems are demonstrated. Simple models are used to illustrate the basic principles of the method which are further used for the solution of complex problems of quantum theory for many-particle systems. The results obtained are supplemented by numerical calculations, presented as tables and figures.

VHF Series-Input Parallel-Output Interleaved Self-Oscillating Resonant SEPIC Converter

DEFF Research Database (Denmark)

Kovacevic, Milovan; Knott, Arnold; Andersen, Michael A. E.

2013-01-01

If the switches of two resonant SEPIC converters are capacitively coupled, it is possible to obtain a self-oscillating converter in which the two power stages operate in interleaved mode. This paper describes a topology where the inputs of two SEPIC converters are connected in series, thereby sha...

Non-perturbative renormalisation of left-left four-fermion operators with Neuberger fermions

International Nuclear Information System (INIS)

Dimopoulos, P.; Giusti, L.; Hernandez, P.; Palombi, F.; Pena, C.; Vladikas, A.; Wennekers, J.; Wittig, H.

2006-01-01

We outline a general strategy for the non-perturbative renormalisation of composite operators in discretisations based on Neuberger fermions, via a matching to results obtained with Wilson-type fermions. As an application, we consider the renormalisation of the four-quark operators entering the ΔS=1 and ΔS=2 effective Hamiltonians. Our results are an essential ingredient for the determination of the low-energy constants governing non-leptonic kaon decays

Series elasticity of the human triceps surae muscle : Measurement by controlled-release vs. resonance methods.

NARCIS (Netherlands)

Hof, AL; Boom, H; Robinson, C; Rutten, W; Neuman, M; Wijkstra, H

1997-01-01

With a newly developed Controlled-Release Ergometer the complete characteristic of the series elastic component can be measured in human muscles. Previous estimates were based on the resonance method: muscle elasticity was assessed from the resonance frequency of the muscle elasticity connected to a

Inter-Series Interactions on the Atomic Photoionization Spectra Studied by the Phase-Shifted Multichannel-Quantum Defect Theory

Directory of Open Access Journals (Sweden)

Chun-Woo Lee

2017-05-01

Full Text Available Development in mathematical formulations of parameterizing the resonance structures using the phase-shifted multichannel quantum defect theory (MQDT and their use in analyzing the effect of inter-series interactions on the autoionizing Rydberg spectra is reviewed. Reformulation of the short-range scattering matrix into the form analogous to S = SBSR in scattering theory are the crucial step in this development. Formulation adopts different directions and goals depending on whether autoionizing series converge to the same limit (degenerate or to different limits (nondegenerate because of the different nature of the perturbation. For the nondegenerate case, finding the simplest form of profile index functions of the autoionizing spectra with the minimal number of parameters is the main goal and some results are reviewed. For the degenerate case where perturbation acts uniformly throughout the entire series, isolation of the overlapped autoionizing series into the unperturbed autoionizing series is the key objective in research and some results in that direction are reviewed.

Topological string theory, modularity and non-perturbative physics

Energy Technology Data Exchange (ETDEWEB)

Rauch, Marco

2011-09-15

In this thesis the holomorphic anomaly of correlators in topological string theory, matrix models and supersymmetric gauge theories is investigated. In the first part it is shown how the techniques of direct integration known from topological string theory can be used to solve the closed amplitudes of Hermitian multi-cut matrix models with polynomial potentials. In the case of the cubic matrix model, explicit expressions for the ring of non-holomorphic modular forms that are needed to express all closed matrix model amplitudes are given. This allows to integrate the holomorphic anomaly equation up to holomorphic modular terms that are fixed by the gap condition up to genus four. There is an one-dimensional submanifold of the moduli space in which the spectral curve becomes the Seiberg-Witten curve and the ring reduces to the non-holomorphic modular ring of the group {gamma}(2). On that submanifold, the gap conditions completely fix the holomorphic ambiguity and the model can be solved explicitly to very high genus. Using these results it is possible to make precision tests of the connection between the large order behavior of the 1/N expansion and non-perturbative effects due to instantons. Finally, it is argued that a full understanding of the large genus asymptotics in the multi-cut case requires a new class of non-perturbative sectors in the matrix model. In the second part a holomorphic anomaly equation for the modified elliptic genus of two M5-branes wrapping a rigid divisor inside a Calabi-Yau manifold is derived using wall-crossing formulae and the theory of mock modular forms. The anomaly originates from restoring modularity of an indefinite theta-function capturing the wall-crossing of BPS invariants associated to D4- D2-D0 brane systems. The compatibility of this equation with anomaly equations previously observed in the context of N=4 topological Yang-Mills theory on P{sup 2} and E-strings obtained from wrapping M5-branes on a del Pezzo surface which in

Topological string theory, modularity and non-perturbative physics

International Nuclear Information System (INIS)

Rauch, Marco

2011-09-01

In this thesis the holomorphic anomaly of correlators in topological string theory, matrix models and supersymmetric gauge theories is investigated. In the first part it is shown how the techniques of direct integration known from topological string theory can be used to solve the closed amplitudes of Hermitian multi-cut matrix models with polynomial potentials. In the case of the cubic matrix model, explicit expressions for the ring of non-holomorphic modular forms that are needed to express all closed matrix model amplitudes are given. This allows to integrate the holomorphic anomaly equation up to holomorphic modular terms that are fixed by the gap condition up to genus four. There is an one-dimensional submanifold of the moduli space in which the spectral curve becomes the Seiberg-Witten curve and the ring reduces to the non-holomorphic modular ring of the group Γ(2). On that submanifold, the gap conditions completely fix the holomorphic ambiguity and the model can be solved explicitly to very high genus. Using these results it is possible to make precision tests of the connection between the large order behavior of the 1/N expansion and non-perturbative effects due to instantons. Finally, it is argued that a full understanding of the large genus asymptotics in the multi-cut case requires a new class of non-perturbative sectors in the matrix model. In the second part a holomorphic anomaly equation for the modified elliptic genus of two M5-branes wrapping a rigid divisor inside a Calabi-Yau manifold is derived using wall-crossing formulae and the theory of mock modular forms. The anomaly originates from restoring modularity of an indefinite theta-function capturing the wall-crossing of BPS invariants associated to D4- D2-D0 brane systems. The compatibility of this equation with anomaly equations previously observed in the context of N=4 topological Yang-Mills theory on P 2 and E-strings obtained from wrapping M5-branes on a del Pezzo surface which in turn is

HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

International Nuclear Information System (INIS)

Blossier, Benoit; Della Morte, Michele; Garron, Nicolas; Edinburgh Univ.; Sommer, Rainer

2010-01-01

We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m b . Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m b in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

Energy Technology Data Exchange (ETDEWEB)

Blossier, Benoit [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Edinburgh Univ. (United Kingdom). School of Physics and Astronomy - SUPA; Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

2010-01-15

We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m{sub b}. Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m{sub b} in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

Modeling of Volatility with Non-linear Time Series Model

OpenAIRE

Kim Song Yon; Kim Mun Chol

2013-01-01

In this paper, non-linear time series models are used to describe volatility in financial time series data. To describe volatility, two of the non-linear time series are combined into form TAR (Threshold Auto-Regressive Model) with AARCH (Asymmetric Auto-Regressive Conditional Heteroskedasticity) error term and its parameter estimation is studied.

Formation of primordial black holes from non-Gaussian perturbations produced in a waterfall transition

Science.gov (United States)

Bugaev, Edgar; Klimai, Peter

2012-05-01

We consider the process of primordial black hole (PBH) formation originated from primordial curvature perturbations produced during waterfall transition (with tachyonic instability), at the end of hybrid inflation. It is known that in such inflation models, rather large values of curvature perturbation amplitudes can be reached, which can potentially cause a significant PBH production in the early Universe. The probability distributions of density perturbation amplitudes in this case can be strongly non-Gaussian, which requires a special treatment. We calculated PBH abundances and PBH mass spectra for the model and analyzed their dependence on model parameters. We obtained the constraints on the parameters of the inflationary potential, using the available limits on βPBH.

Two-dimensional sigma models: modelling non-perturbative effects of gauge theories

International Nuclear Information System (INIS)

Novikov, V.A.; Shifman, M.A.; Vainshtein, A.I.; Zakharov, V.I.

1984-01-01

The review is devoted to a discussion of non-perturbative effects in gauge theories and two-dimensional sigma models. The main emphasis is put on supersymmetric 0(3) sigma model. The instanton-based method for calculating the exact Gell-Mann-Low function and bifermionic condensate is considered in detail. All aspects of the method in simplifying conditions are discussed. The basic points are: the instanton measure from purely classical analysis; a non-renormalization theorem in self-dual external fields; existence of vacuum condensates and their compatibility with supersymmetry

Non-linear perturbations of a spherically collapsing star

International Nuclear Information System (INIS)

Brizuela, David

2009-01-01

Linear perturbation theory has been a successful tool in General Relativity, and can be considered as complementary to full nonlinear simulations. Going to second and higher perturbative orders improves the approximation and offers a controlled way to analyze the nonlinearities of the theory, though the problem becomes much harder computationally. We present a systematic approach to the treatment of high order metric perturbations, focusing on the scenario of nonspherical perturbations of a dynamical spherical background. It is based on the combination of adapted geometrical variables and the use of efficient computer algebra techniques. After dealing with a number of theoretical issues, like the construction of gauge invariants, we apply the formalism to the particular case of a perfect fluid star surrounded by a vacuum exterior. We describe the regularization of the divergences of the perturbations at null infinity and the matching conditions through the surface of the star.

Non-perturbative field theory/field theory on a lattice

International Nuclear Information System (INIS)

Ambjorn, J.

1988-01-01

The connection between the theory of critical phenomena in statistical mechanics and the renormalization of field theory is briefly outlined. The way of using this connection is described to get information about non-perturbative quantities in QCD and about more intelligent ways of doing the Monte Carlo (MC) simulations. The (MC) method is shown to be a viable one in high energy physics, but it is not a good substitute for an analytic understanding. MC-methods will be very valuable both for getting out hard numbers and for testing the correctness of new ideas

Non-Gaussianities and curvature perturbations from hybrid inflation

Science.gov (United States)

Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi

2014-03-01

For the original hybrid inflation as well as the supersymmetric F-term and D-term hybrid models, we calculate the level of non-Gaussianities and the power spectrum of curvature perturbations generated during the waterfall, taking into account the contribution of entropic modes. We focus on the regime of mild waterfall, in which inflation continues for more than about 60 e-folds N during the waterfall. We find that the associated fNL parameter goes typically from fNL≃-1/Nexit in the regime with N ≫60, where Nexit is the number of e-folds between the time of Hubble exit of a pivot scale and the end of inflation, down to fNL˜-0.3 when N ≳60, i.e., much smaller in magnitude than the current bound from Planck. Considering only the adiabatic perturbations, the power spectrum is red, with a spectral index ns=1-4/Nexit in the case N ≫60, whereas in the case N≳60, it increases up to unity. Including the contribution of entropic modes does not change observable predictions in the first case, and the spectral index is too low for this regime to be viable. In the second case, entropic modes are a relevant source for the power spectrum of curvature perturbations, of which the amplitude increases by several orders of magnitude. When spectral index values are consistent with observational constraints, the primordial spectrum amplitude is much larger than the observed value and can even lead to black hole formation. We conclude that, due to the important contribution of entropic modes, the parameter space leading to a mild waterfall phase is excluded by cosmic microwave background observations for all the considered models.

Non recurrent behaviour in quantum dynamics

International Nuclear Information System (INIS)

Casati, G.; Guarneri, I.

1984-01-01

We study the motion of a quantum rotator under an external periodic perturbation. For the resonant case, i.e. when the frequency of driving pulses is rationally connected with the frequencies of the free rotator, the quasi-energy spectrum is known to be continuous. We prove that for a generic choice of the potential there is a non-empty set of non-resonant values of the external frequency such that the quasi-energy spectrum still has a continuous component. (orig.)

Three-dimensional modeling of plasma edge transport and divertor fluxes during application of resonant magnetic perturbations on ITER

Czech Academy of Sciences Publication Activity Database

Schmitz, O.; Becoulet, M.; Cahyna, Pavel; Evans, T.E.; Feng, Y.; Frerichs, H.; Loarte, A.; Pitts, R.A.; Reiser, D.; Fenstermacher, M.E.; Harting, D.; Kirschner, A.; Kukushkin, A.; Lunt, T.; Saibene, G.; Reiter, D.; Samm, U.; Wiesen, S.

2016-01-01

Roč. 56, č. 6 (2016), č. článku 066008. ISSN 0029-5515 Institutional support: RVO:61389021 Keywords : resonant magnetic perturbations * plasma edge physics * 3D modeling * neutral particle physics * ITER * divertor heat and particle loads * ELM control Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.307, year: 2016 http://iopscience.iop.org/article/10.1088/0029-5515/56/6/066008/meta

Perturbation Biology: Inferring Signaling Networks in Cellular Systems

Science.gov (United States)

Miller, Martin L.; Gauthier, Nicholas P.; Jing, Xiaohong; Kaushik, Poorvi; He, Qin; Mills, Gordon; Solit, David B.; Pratilas, Christine A.; Weigt, Martin; Braunstein, Alfredo; Pagnani, Andrea; Zecchina, Riccardo; Sander, Chris

2013-01-01

We present a powerful experimental-computational technology for inferring network models that predict the response of cells to perturbations, and that may be useful in the design of combinatorial therapy against cancer. The experiments are systematic series of perturbations of cancer cell lines by targeted drugs, singly or in combination. The response to perturbation is quantified in terms of relative changes in the measured levels of proteins, phospho-proteins and cellular phenotypes such as viability. Computational network models are derived de novo, i.e., without prior knowledge of signaling pathways, and are based on simple non-linear differential equations. The prohibitively large solution space of all possible network models is explored efficiently using a probabilistic algorithm, Belief Propagation (BP), which is three orders of magnitude faster than standard Monte Carlo methods. Explicit executable models are derived for a set of perturbation experiments in SKMEL-133 melanoma cell lines, which are resistant to the therapeutically important inhibitor of RAF kinase. The resulting network models reproduce and extend known pathway biology. They empower potential discoveries of new molecular interactions and predict efficacious novel drug perturbations, such as the inhibition of PLK1, which is verified experimentally. This technology is suitable for application to larger systems in diverse areas of molecular biology. PMID:24367245

A DC to 3-phase series-resonant converter with low harmonic distortion

NARCIS (Netherlands)

Huisman, H.; Haan, de S.W.H.

1985-01-01

A type of dc to 3-phase series-resonant converter (s.r.converter) or potentially submegawatt industrial applications is presented. The converter provides variable-frequency sine-wave currents, with low harmonic distortion at the output terminals, and with the frequency ranging from -200 through dc

A perturbation-based model for rectifier circuits

Directory of Open Access Journals (Sweden)

Vipin B. Vats

2006-01-01

Full Text Available A perturbation-theoretic analysis of rectifier circuits is presented. The governing differential equation of the half-wave rectifier with capacitor filter is analyzed by expanding the output voltage as a Taylor series with respect to an artificially introduced parameter in the nonlinearity of the diode characteristic as is done in quantum theory. The perturbation parameter introduced in the analysis is independent of the circuit components as compared to the method presented by multiple scales. The various terms appearing in the perturbation series are then modeled in the form of an equivalent circuit. This model is subsequently used in the analysis of full-wave rectifier. Matlab simulation results are included which confirm the validity of the theoretical formulations. Perturbation analysis acts a helpful tool in analyzing time-varying systems and chaotic systems.

Non-perturbative Approach to Equation of State and Collective Modes of the QGP

Directory of Open Access Journals (Sweden)

Y.F. Liu Shuai

2018-01-01

Full Text Available We discuss a non-perturbative T-matrix approach to investigate the microscopic structure of the quark-gluon plasma (QGP. Utilizing an effective Hamiltonian which includes both light- and heavy-parton degrees of freedoms. The basic two-body interaction includes color-Coulomb and confining contributions in all available color channels, and is constrained by lattice-QCD data for the heavy-quark free energy. The in-medium T-matrices and parton spectral functions are computed selfconsistently with full account of off-shell properties encoded in large scattering widths. We apply the T-matrices to calculate the equation of state (EoS for the QGP, including a ladder resummation of the Luttinger-Ward functional using a matrix-log technique to account for the dynamical formation of bound states. It turns out that the latter become the dominant degrees of freedom in the EoS at low QGP temperatures indicating a transition from parton to hadron degrees of freedom. The calculated spectral properties of one- and two-body states confirm this picture, where large parton scattering rates dissolve the parton quasiparticle structures while broad resonances start to form as the pseudocritical temperature is approached from above. Further calculations of transport coefficients reveal a small viscosity and heavy-quark diffusion coefficient.

Thermal gluons beyond pure perturbation theory

International Nuclear Information System (INIS)

Reinbach, J.

2000-01-01

The perturbative treatment of non-abelian gauge theory at high temperature leads to a threshold in calculation because of chromomagnetic effects. Infinitely many terms of the same order of magnitude arise. The numerical series to be summed is contained in the part of the theory reduced on 3D, which was recently treated non-perturbative as 2+1D Yang-Mills theory at T=0 by Karabali, Kim and Nair. In the thesis in question the exact 3D results are combined with the thermal 4D diagrammatic. In particular the splitting of the space-part of the transverse self-energy in the static limit is treated. As expected, the 3D subsystem can separate as regularized 3D Yang-Mills theory from the 4D structure. In 1-loop order the regulators are received explicit. For 2-loop order it can be shown amongst other things, that the generic contribution with hard inner momenta vanishes. It is examined, how the magnetic mass could follow. Under pressure it is possible to separate the 3D part in 1- and 2-loop order and to receive regulators [de

Analysis of stochastic magnetic fields formed by the application of resonant magnetic perturbations on MAST and comparison with experiment

International Nuclear Information System (INIS)

Denner, P.; Liu, Yueqiang; Kirk, A.; Nardon, E.

2012-01-01

In MAST experiments with applied resonant magnetic perturbations (RMPs), clear reduction in line-averaged density has been observed in a wide range of L-mode plasmas when there is an alignment between the perturbation and the equilibrium magnetic field that maximizes the size of the resonant components of the applied magnetic field, as well as in a few H-mode plasmas but with a much stronger sensitivity to this alignment. This density pump-out is the result of increased particle transport, which is thought to be caused by the formation of a stochastic magnetic field in the plasma edge. This paper presents an analysis of the magnetic field structures formed by the application of n = 3 RMPs on MAST, including various parameters characterizing the degree of stochasticity in the plasma edge. Values for these parameters are calculated and compared with the amount of density pump-out observed in MAST experiments. It is found that density pump-out is fairly well correlated with some of the parameters calculated using vacuum modelling, but none of them provides a single threshold value for pump-out that applies to both L- and H-mode plasmas. Plasma response modelling provides a robust criterion for density pump-out that applies both to L- and H-mode plasmas. (paper)

Determination of calibration constants for perturbing objects of cavity resonators

International Nuclear Information System (INIS)

Franco, M.A.R.; Serrao, V.A.; Fuhrmann, C.

1989-05-01

Using the Slater theorem, the calibrating constants for objects utilized in the tecnique of perturbing measurements of cavities electric and magnetic fields have been determined. Such perturbing objects are utilized in the measurements of the shunt impedance and electric field relative intensity ocurring in linac accelerating structures. To determine the calibrating constants of the perturbing objects, a cylindrical cavity of well know field pattern has been utilized. The cavity was excited in two differente modes of oscillation and the experimental results are in good aggrement with the theoretical values. (author) [pt

On the non-Gaussian correlation of the primordial curvature perturbation with vector fields

DEFF Research Database (Denmark)

Kumar Jain, Rajeev; Sloth, Martin Snoager

2013-01-01

We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified...... with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit...

Perturbation Theory of the Cosmological Log-Density Field

DEFF Research Database (Denmark)

Wang, Xin; Neyrinck, Mark; Szapudi, István

2011-01-01

, motivating an analytic study of it. In this paper, we develop cosmological perturbation theory for the power spectrum of this field. Our formalism is developed in the context of renormalized perturbation theory, which helps to regulate the convergence behavior of the perturbation series, and of the Taylor...

A new perturbative approach to QCD

International Nuclear Information System (INIS)

Pervushin, V.N.; Kallies, W.; Sarikov, N.A.

1988-01-01

For the description of bound states in QED and QCD the physical perturbation theory on the spatial components of the vector over the exact solution, defined by the time one, is proposed. It is shown this perturbation theory in QCD can be redefined so that it reproduces the main elements of hadron physics: confinement, spectroscopy of light and heavy quarkonia, dual-resonance amplitudes, chiral Lagrangians and the parton model

Non-perturbative phenomena in QCD vacuum, hadrons, and quark-gluon plasma

International Nuclear Information System (INIS)

Shuryak, E.V.

1983-01-01

These lectures provide a brief review of recent progress in non-perturbative quantum chromodynamics (QCD). They are intended for non specialists, mainly experimentalists. The main object of discussion, the QCD vacuum, is a rather complicated medium. It may be studied either by infinitesimal probes producing microscopic excitations (=hadrons), or by finite excitations (say, heating some volume to a given temperature T). In the latter case, some qualitative changes (phase transitions) should take place. A summary is given of the extent to which such phenomena can be observed in the laboratory by proton-proton, proton-nucleus, and nucleus-nucleus collisions. (orig.)

Non-perturbative QCD correlation functions

Energy Technology Data Exchange (ETDEWEB)

Cyrol, Anton Konrad

2017-11-27

Functional methods provide access to the non-perturbative regime of quantum chromo- dynamics. Hence, they allow investigating confinement and chiral symmetry breaking. In this dissertation, correlation functions of Yang-Mills theory and unquenched two-flavor QCD are computed from the functional renormalization group. Employing a self-consistent vertex expansion of the effective action, Yang-Mills correlation functions are obtained in four as well as in three spacetime dimensions. To this end, confinement and Slavnov-Taylor identities are discussed. Our numerical results show very good agreement with corresponding lattice results. Next, unquenched two-flavor QCD is considered where it is shown that the unquenched two-flavor gluon propagator is insensitive to the pion mass. Furthermore, the necessity for consistent truncations is emphasized. Finally, correlation functions of finite-temperature Yang-Mills theory are computed in a truncation that includes the splitting of the gluon field into directions that are transverse and longitudinal to the heat bath. In particular, it includes the splitting of the three- and four-gluon vertices. The obtained gluon propagator allows to extract a Debye screening mass that coincides with the hard thermal loop screening mass at high temperatures, but is meaningful also at temperatures below the phase transition temperature.

Inherent overload protection for the series resonant converter

Science.gov (United States)

King, R. J.; Stuart, T. A.

1983-01-01

The overload characteristics of the full bridge series resonant power converter are considered. This includes analyses of the two most common control methods presently in use. The first of these uses a current zero crossing detector to synchronize the control signals and is referred to as the alpha controller. The second is driven by a voltage controlled oscillator and is referred to as the gamma controller. It is shown that the gamma controller has certain reliability advantages in that it can be designed with inherent short circuit protection. Experimental results are included for an 86 kHz converter using power metal-oxide-semiconductor field-effect transistors (MOSFETs).

Coupling-parameter expansion in thermodynamic perturbation theory.

Science.gov (United States)

Ramana, A Sai Venkata; Menon, S V G

2013-02-01

An approach to the coupling-parameter expansion in the liquid state theory of simple fluids is presented by combining the ideas of thermodynamic perturbation theory and integral equation theories. This hybrid scheme avoids the problems of the latter in the two phase region. A method to compute the perturbation series to any arbitrary order is developed and applied to square well fluids. Apart from the Helmholtz free energy, the method also gives the radial distribution function and the direct correlation function of the perturbed system. The theory is applied for square well fluids of variable ranges and compared with simulation data. While the convergence of perturbation series and the overall performance of the theory is good, improvements are needed for potentials with shorter ranges. Possible directions for further developments in the coupling-parameter expansion are indicated.

Resonances in the two centers Coulomb system

International Nuclear Information System (INIS)

Seri, Marcello

2012-01-01

In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

Resonances in the two centers Coulomb system

Energy Technology Data Exchange (ETDEWEB)

Seri, Marcello

2012-09-14

In this work we investigate the existence of resonances for two-centers Coulomb systems with arbitrary charges in two and three dimensions, defining them in terms of generalized complex eigenvalues of a non-selfadjoint deformation of the two-center Schroedinger operator. After giving a description of the bifurcation of the classical system for positive energies, we construct the resolvent kernel of the operators and we prove that they can be extended analytically to the second Riemann sheet. The resonances are then defined and studied with numerical methods and perturbation theory.

Interacting fermions in two dimensions: Beyond the perturbation theory

International Nuclear Information System (INIS)

Gangadharaiah, S.; Maslov, D.L.; Chubukov, A.V.; Glazman, L.I.

2005-05-01

We consider a system of 2D fermions with short-range interaction. A straightforward perturbation theory is shown to be ill-defined even for an infinitesimally weak interaction, as the perturbative series for the self-energy diverges near the mass shell. We show that the divergences result from the interaction of fermions with the zero-sound collective mode. By re-summing the most divergent diagrams, we obtain a closed form of the self-energy near the mass shell. The spectral function exhibits a threshold feature at the onset of the emission of the zero-sound waves. We also show that the interaction with the zero sound does not affect a non- analytic, T 2 -part of the specific heat. (author)

EXAMINING A SERIES RESONANT INVERTER CIRCUIT TO USE IN THE PHOTOVOLTAIC ENERGY CONVERSION SYSTEMS

Directory of Open Access Journals (Sweden)

Engin ÇETİN

2004-03-01

Full Text Available As we know, solar energy is the energy source which is environment friendly, renewable, and can be found easily. Particularly, in the recent years, interest on producing electrical energy by alternative energy sources increased because of the fact that underground sources are not enough to produce energy in the future and also these sources cause enviromental pollution. The solar energy is one of the most popular one among the alternative energy sources. Photovoltaic systems produce the electrical energy from the sunlight. In this study, a series resonant inverter circuit which is used in the photovoltaic energy conversion systems has been examined.Effects of the series resonant inverter circuit on the photovoltaic energy conversion system have been investigated and examined

On the generation of a non-gaussian curvature perturbation during preheating

Energy Technology Data Exchange (ETDEWEB)

Kohri, Kazunori; Lyth, David H. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom); Valenzuela-Toledo, Cesar A., E-mail: k.kohri@lancaster.ac.uk, E-mail: d.lyth@lancaster.ac.uk, E-mail: cavalto@ciencias.uis.edu.co [Escuela de Física, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia)

2010-02-01

The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation ζ. The field might appear directly in the preheating model (curvaton-type preheating) or indirectly through its effect on a mass or coupling (modulated preheating). We give general expressions for ζ based on the δN formula, and apply them to the cases of quadratic and quartic chaotic inflation. For the quadratic case, curvaton-type preheating is ineffective in contributing to ζ, but modulated preheating can be effective. For quartic inflation, curvaton-type preheating may be effective but the usual δN formalism has to be modified. We see under what circumstances the recent numerical simulation of Bond et al. [0903.3407] may be enough to provide a rough estimate for this case.

On the generation of a non-gaussian curvature perturbation during preheating

International Nuclear Information System (INIS)

Kohri, Kazunori; Lyth, David H.; Valenzuela-Toledo, Cesar A.

2010-01-01

The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation ζ. The field might appear directly in the preheating model (curvaton-type preheating) or indirectly through its effect on a mass or coupling (modulated preheating). We give general expressions for ζ based on the δN formula, and apply them to the cases of quadratic and quartic chaotic inflation. For the quadratic case, curvaton-type preheating is ineffective in contributing to ζ, but modulated preheating can be effective. For quartic inflation, curvaton-type preheating may be effective but the usual δN formalism has to be modified. We see under what circumstances the recent numerical simulation of Bond et al. [0903.3407] may be enough to provide a rough estimate for this case

Non-perturbative test of the Witten-Veneziano formula from lattice QCD

International Nuclear Information System (INIS)

Cichy, Krzysztof; Jansen, Karl; Ottnad, Konstantin; Urbach, Carsten; Bonn Univ.

2015-10-01

We compute both sides of the Witten-Veneziano formula using lattice techniques. For the one side we perform dedicated quenched simulations and use the spectral projector method to determine the topological susceptibility in the pure Yang-Mills theory. The other side we determine in lattice QCD with N f =2 +1+1 dynamical Wilson twisted mass fermions including for the first time also the flavour singlet decay constant. The Witten-Veneziano formula represents a leading order expression in the framework of chiral perturbation theory and we also employ leading order chiral perturbation theory to relate the flavor singlet decay constant to the relevant decay constant parameters in the quark flavor basis and flavor non-singlet decay constants. After taking the continuum and the SU(2) chiral limits we compare both sides and find good agreement within uncertainties.

Non-perturbative Aspects of QCD and Parameterized Quark Propagator

Institute of Scientific and Technical Information of China (English)

HAN Ding-An; ZHOU Li-Juan; ZENG Ya-Guang; GU Yun-Ting; CAO Hui; MA Wei-Xing; MENG Cheng-Ju; PAN Ji-Huan

2008-01-01

Based on the Global Color Symmetry Model, the non-perturbative QCD vacuum is investigated in theparameterized fully dressed quark propagator. Our theoretical predictions for various quantities characterized the QCD vacuum are in agreement with those predicted by many other phenomenological QCD inspired models. The successful predictions clearly indicate the extensive validity of our parameterized quark propagator used here. A detailed discussion on the arbitrariness in determining the integration cut-off parameter of# in calculating QCD vacuum condensates and a good method, which avoided the dependence of calculating results on the cut-off parameter is also strongly recommended to readers.

Multiphoton resonances

International Nuclear Information System (INIS)

Shore, B.W.

1977-01-01

The long-time average of level populations in a coherently-excited anharmonic sequence of energy levels (e.g., an anharmonic oscillator) exhibits sharp resonances as a function of laser frequency. For simple linearly-increasing anharmonicity, each resonance is a superposition of various multiphoton resonances (e.g., a superposition of 3, 5, 7, . . . photon resonances), each having its own characteristic width predictable from perturbation theory

Special Features in the Structure of Resonant Perturbations of Uncontrollable Objects of Glonass and GPS Navigating Systems. Influence on the Orbital Evolution

Science.gov (United States)

Tomilova, I. V.; Bordovitsyna, T. V.

2017-08-01

Results of investigation into the resonant structure of perturbations and long-term orbital evolution of space vehicles of GLONASS and GPS global navigating satellite systems (GNSS) under assumption that all of them have lost control on 08/01/2015 are presented. It is demonstrated that the majority of the examined objects are in the range of action of the secular resonances of various types. In addition, practically all satellites of the GPS system are within the scope of the 2:1 orbital resonance with rotation of the Earth. Results of the MEGNO analysis demonstrate that the motion of all objects of the GLONASS system during the 100-year period is regular, whereas the motion of the majority of objects of the GPS system is subject to chaotization.

A Non-Perturbative, Finite Particle Number Approach to Relativistic Scattering Theory

Energy Technology Data Exchange (ETDEWEB)

Lindesay, James V

2001-05-11

We present integral equations for the scattering amplitudes of three scalar particles, using the Faddeev channel decomposition, which can be readily extended to any finite number of particles of any helicity. The solution of these equations, which have been demonstrated to be calculable, provide a non-perturbative way of obtaining relativistic scattering amplitudes for any finite number of particles that are Lorentz invariant, unitary, cluster decomposable and reduce unambiguously in the non-relativistic limit to the non-relativistic Faddeev equations. The aim of this program is to develop equations which explicitly depend upon physically observable input variables, and do not require ''renormalization'' or ''dressing'' of these parameters to connect them to the boundary states.

Preheating curvaton perturbations

International Nuclear Information System (INIS)

Bastero-Gil, M.; Di Clemente, V.; King, S.F.

2005-01-01

We discuss the potentially important role played by preheating in certain variants of the curvaton mechanism in which isocurvature perturbations of a D-flat (and F-flat) direction become converted to curvature perturbations during reheating. We discover that parametric resonance of the isocurvature components amplifies the superhorizon fluctuations by a significant amount. As an example of these effects we develop a particle physics motivated model which involves hybrid inflation with the waterfall field N being responsible for generating the μ term, the right-handed neutrino mass scale, and the Peccei-Quinn symmetry breaking scale. The role of the curvaton field can be played either by usual Higgs field, or the lightest right-handed sneutrino. Our new results show that it is possible to achieve the correct curvature perturbations for initial values of the curvaton fields of order the weak scale. In this model we show that the prediction for the spectral index of the final curvature perturbation only depends on the mass of the curvaton during inflation, where consistency with current observational data requires the ratio of this mass to the Hubble constant to be 0.3

Optimal separable bases and series expansions

International Nuclear Information System (INIS)

Poirier, B.

1997-01-01

A method is proposed for the efficient calculation of the Green close-quote s functions and eigenstates for quantum systems of two or more dimensions. For a given Hamiltonian, the best possible separable approximation is obtained from the set of all Hilbert-space operators. It is shown that this determination itself, as well as the solution of the resultant approximation, is a problem of reduced dimensionality. Moreover, the approximate eigenstates constitute the optimal separable basis, in the sense of self-consistent field theory. The full solution is obtained from the approximation via iterative expansion. In the time-independent perturbation expansion for instance, all of the first-order energy corrections are zero. In the Green close-quote s function case, we have a distorted-wave Born series with optimized convergence properties. This series may converge even when the usual Born series diverges. Analytical results are presented for an application of the method to the two-dimensional shifted harmonic-oscillator system, in the course of which the quantum tanh 2 potential problem is solved exactly. The universal presence of bound states in the latter is shown to imply long-lived resonances in the former. In a comparison with other theoretical methods, we find that the reaction path Hamiltonian fails to predict such resonances. copyright 1997 The American Physical Society

Renormalized Lie perturbation theory

International Nuclear Information System (INIS)

Rosengaus, E.; Dewar, R.L.

1981-07-01

A Lie operator method for constructing action-angle transformations continuously connected to the identity is developed for area preserving mappings. By a simple change of variable from action to angular frequency a perturbation expansion is obtained in which the small denominators have been renormalized. The method is shown to lead to the same series as the Lagrangian perturbation method of Greene and Percival, which converges on KAM surfaces. The method is not superconvergent, but yields simple recursion relations which allow automatic algebraic manipulation techniques to be used to develop the series to high order. It is argued that the operator method can be justified by analytically continuing from the complex angular frequency plane onto the real line. The resulting picture is one where preserved primary KAM surfaces are continuously connected to one another

On the non-linear scale of cosmological perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Blas, Diego [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Garny, Mathias; Konstandin, Thomas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2013-04-15

We discuss the convergence of cosmological perturbation theory. We prove that the polynomial enhancement of the non-linear corrections expected from the effects of soft modes is absent in equal-time correlators like the power or bispectrum. We first show this at leading order by resumming the most important corrections of soft modes to an arbitrary skeleton of hard fluctuations. We derive the same result in the eikonal approximation, which also allows us to show the absence of enhancement at any order. We complement the proof by an explicit calculation of the power spectrum at two-loop order, and by further numerical checks at higher orders. Using these insights, we argue that the modification of the power spectrum from soft modes corresponds at most to logarithmic corrections. Finally, we discuss the asymptotic behavior in the large and small momentum regimes and identify the expansion parameter pertinent to non-linear corrections.

On the non-linear scale of cosmological perturbation theory

International Nuclear Information System (INIS)

Blas, Diego; Garny, Mathias; Konstandin, Thomas

2013-04-01

We discuss the convergence of cosmological perturbation theory. We prove that the polynomial enhancement of the non-linear corrections expected from the effects of soft modes is absent in equal-time correlators like the power or bispectrum. We first show this at leading order by resumming the most important corrections of soft modes to an arbitrary skeleton of hard fluctuations. We derive the same result in the eikonal approximation, which also allows us to show the absence of enhancement at any order. We complement the proof by an explicit calculation of the power spectrum at two-loop order, and by further numerical checks at higher orders. Using these insights, we argue that the modification of the power spectrum from soft modes corresponds at most to logarithmic corrections. Finally, we discuss the asymptotic behavior in the large and small momentum regimes and identify the expansion parameter pertinent to non-linear corrections.

On the non-linear scale of cosmological perturbation theory

CERN Document Server

Blas, Diego; Konstandin, Thomas

2013-01-01

We discuss the convergence of cosmological perturbation theory. We prove that the polynomial enhancement of the non-linear corrections expected from the effects of soft modes is absent in equal-time correlators like the power or bispectrum. We first show this at leading order by resumming the most important corrections of soft modes to an arbitrary skeleton of hard fluctuations. We derive the same result in the eikonal approximation, which also allows us to show the absence of enhancement at any order. We complement the proof by an explicit calculation of the power spectrum at two-loop order, and by further numerical checks at higher orders. Using these insights, we argue that the modification of the power spectrum from soft modes corresponds at most to logarithmic corrections. Finally, we discuss the asymptotic behavior in the large and small momentum regimes and identify the expansion parameter pertinent to non-linear corrections.

Non-resonant oscillations for some third-order differential equations II

International Nuclear Information System (INIS)

Ezeilo, J.O.C.; Omari, P.

1987-11-01

The existence of 2π-periodic solutions to the equation x'''+ax''+g(t,x')+cx=p(t) is proved, under certain non-resonance conditions on the non-linear function g(t,y). Here a,c are constants, but the case where a,c are not necessarily constants is also discussed, subject to some rather special non-resonance conditions on g. The uniqueness of the solutions is also examined. (author). 12 refs

Implementation of advanced feedback control algorithms for controlled resonant magnetic perturbation physics studies on EXTRAP T2R

International Nuclear Information System (INIS)

Frassinetti, L.; Olofsson, K.E.J.; Brunsell, P.R.; Drake, J.R.

2011-01-01

The EXTRAP T2R feedback system (active coils, sensor coils and controller) is used to study and develop new tools for advanced control of the MHD instabilities in fusion plasmas. New feedback algorithms developed in EXTRAP T2R reversed-field pinch allow flexible and independent control of each magnetic harmonic. Methods developed in control theory and applied to EXTRAP T2R allow a closed-loop identification of the machine plant and of the resistive wall modes growth rates. The plant identification is the starting point for the development of output-tracking algorithms which enable the generation of external magnetic perturbations. These algorithms will then be used to study the effect of a resonant magnetic perturbation (RMP) on the tearing mode (TM) dynamics. It will be shown that the stationary RMP can induce oscillations in the amplitude and jumps in the phase of the rotating TM. It will be shown that the RMP strongly affects the magnetic island position.

Implementation of advanced feedback control algorithms for controlled resonant magnetic perturbation physics studies on EXTRAP T2R

Science.gov (United States)

Frassinetti, L.; Olofsson, K. E. J.; Brunsell, P. R.; Drake, J. R.

2011-06-01

The EXTRAP T2R feedback system (active coils, sensor coils and controller) is used to study and develop new tools for advanced control of the MHD instabilities in fusion plasmas. New feedback algorithms developed in EXTRAP T2R reversed-field pinch allow flexible and independent control of each magnetic harmonic. Methods developed in control theory and applied to EXTRAP T2R allow a closed-loop identification of the machine plant and of the resistive wall modes growth rates. The plant identification is the starting point for the development of output-tracking algorithms which enable the generation of external magnetic perturbations. These algorithms will then be used to study the effect of a resonant magnetic perturbation (RMP) on the tearing mode (TM) dynamics. It will be shown that the stationary RMP can induce oscillations in the amplitude and jumps in the phase of the rotating TM. It will be shown that the RMP strongly affects the magnetic island position.

Nonlinear Modeling of Forced Magnetic Reconnection with Transient Perturbations

Science.gov (United States)

Beidler, Matthew T.; Callen, James D.; Hegna, Chris C.; Sovinec, Carl R.

2017-10-01

Externally applied 3D magnetic fields in tokamaks can penetrate into the plasma and lead to forced magnetic reconnection, and hence magnetic islands, on resonant surfaces. Analytic theory has been reasonably successful in describing many aspects of this paradigm with regard to describing the time asymptotic-steady state. However, understanding the nonlinear evolution into a low-slip, field-penetrated state, especially how MHD events such as sawteeth and ELMs precipitate this transition, is in its early development. We present nonlinear computations employing the extended-MHD code NIMROD, building on previous work by incorporating a temporally varying external perturbation as a simple model for an MHD event that produces resonant magnetic signals. A parametric series of proof-of-principle computations and accompanying analytical theory characterize the transition into a mode-locked state with an emphasis on detailing the temporal evolution properties. Supported by DOE OFES Grants DE-FG02-92ER54139, DE-FG02-86ER53218, and the U.S. DOE FES Postdoctoral Research program administered by ORISE and managed by ORAU under DOE contract DE-SC0014664.

Perturbative expansion of Chern-Simons theory with non-compact gauge group

International Nuclear Information System (INIS)

Bar-Natan, D.; Witten, E.

1991-01-01

Naive imitation of the usual formulas for compact gauge group in quantizing three dimensional Chern-Simons gauge theory with non-compact gauge group leads to formulas that are wrong or unilluminating. In this paper, an appropriate modification is described, which puts the perturbative expansion in a standard manifestly 'unitary' format. The one loop contributions (which differ from naive extrapolation from the case of compact gauge group) are computed, and their topological invariance is verified. (orig.)

A strategy for implementing non-perturbative renormalisation of heavy-light four-quark operators in the static approximation

Energy Technology Data Exchange (ETDEWEB)

Palombi, F. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie; Papinutto, M. [Istituto Nazionale di Fisica Nucleare, Rome (Italy); Pena, C. [European Organization for Nuclear Research, Geneva (Switzerland). Theoretical Physics Div.; Wittig, H. [Mainz Univ. (Germany). Inst. fuer Kernphysik

2006-04-15

We discuss the renormalisation properties of the complete set of {delta}B=2 four-quark operators with the heavy quark treated in the static approximation. We elucidate the role of heavy quark symmetry and other symmetry transformations in constraining their mixing under renormalisation. By employing the Schroedinger functional, a set of non-perturbative renormalisation conditions can be defined in terms of suitable correlation functions. As a first step in a fully non-perturbative determination of the scale-dependent renormalisation factors, we evaluate these conditions in lattice perturbation theory at one loop. Thereby we verify the expected mixing patterns and determine the anomalous dimensions of the operators at NLO in the Schroedinger functional scheme. Finally, by employing twisted-mass QCD it is shown how finite subtractions arising from explicit chiral symmetry breaking can be avoided completely. (Orig.)

A strategy for implementing non-perturbative renormalisation of heavy-light four-quark operators in the static approximation

International Nuclear Information System (INIS)

Palombi, F.; Pena, C.; Wittig, H.

2006-04-01

We discuss the renormalisation properties of the complete set of ΔB=2 four-quark operators with the heavy quark treated in the static approximation. We elucidate the role of heavy quark symmetry and other symmetry transformations in constraining their mixing under renormalisation. By employing the Schroedinger functional, a set of non-perturbative renormalisation conditions can be defined in terms of suitable correlation functions. As a first step in a fully non-perturbative determination of the scale-dependent renormalisation factors, we evaluate these conditions in lattice perturbation theory at one loop. Thereby we verify the expected mixing patterns and determine the anomalous dimensions of the operators at NLO in the Schroedinger functional scheme. Finally, by employing twisted-mass QCD it is shown how finite subtractions arising from explicit chiral symmetry breaking can be avoided completely. (Orig.)

Resonant dynamics of gravitationally bound pair of binaries: the case of 1:1 resonance

Science.gov (United States)

Breiter, Slawomir; Vokrouhlický, David

2018-04-01

The work presents a study of the 1:1 resonance case in a hierarchical quadruple stellar system of the 2+2 type. The resonance appears if orbital periods of both binaries are approximately equal. It is assumed that both periods are significantly shorter than the period of principal orbit of one binary with respect to the other. In these circumstances, the problem can be treated as three independent Kepler problems perturbed by mutual gravitational interactions. By means of canonical perturbation methods, the planar problem is reduced to a secular system with 1 degree of freedom involving a resonance angle (the difference of mean longitudes of the binaries) and its conjugate momentum (involving the ratio of orbital period in one binary to the period of principal orbit). The resonant model is supplemented with short periodic perturbations expressions, and verified by the comparison with numerical integration of the original equations of motion. Estimates of the binaries periods variations indicate that the effect is rather weak, but possibly detectible if it occurs in a moderately compact system. However, the analysis of resonance capture scenarios implies that the 1:1 resonance should be exceptional amongst the 2+2 quadruples.

Nonperturbative perturbation theory

International Nuclear Information System (INIS)

Bender, C.M.

1989-01-01

In this talk we describe a recently proposed graphical perturbative calculational scheme for quantum field theory. The basic idea is to expand in the power of the interaction term. For example, to solve a λφ 4 theory in d-dimensional space-time, we introduce a small parameter δ and consider a λ(φ 2 ) 1+δ field theory. We show how to expand such a theory as a series in powers of δ. The resulting perturbation series appears to have a finite radius of convergence and numerical results for low-dimensional models are good. We have computed the two-point and four-point Green's functions to second order in powers of δ and the 2n-point Green's functions (n>2) to order δ. We explain how to renormalize the theory and show that, to first order in powers of δ, when δ>0 and d≥4 the theory is free. This conclusion remains valid to second order in powers of δ, and we believe that it remains valid to all orders in powers of δ. The new perturbative scheme is consistent with global supersymmetry invariance. We examine a two-dimensional supersymmetric quantum field theory in which we do not know of any other means for doing analytical calculations. We illustrate the power of this new technique by computing the ground-state energy density E to second order in this new perturbation theory. We show that there is a beautiful and delicate cancellation between infinite classes of graphs which leads to the result that E=0. (orig.)

A non-perturbative study of 4d U(1) non-commutative gauge theory - the fate of one-loop instability

International Nuclear Information System (INIS)

Bietenholz, Wolfgang; Nishimura, Jun; Susaki, Yoshiaki; Volkholz, Jan

2006-01-01

Recent perturbative studies show that in 4d non-commutative spaces, the trivial (classically stable) vacuum of gauge theories becomes unstable at the quantum level, unless one introduces sufficiently many fermionic degrees of freedom. This is due to a negative IR-singular term in the one-loop effective potential, which appears as a result of the UV/IR mixing. We study such a system non-perturbatively in the case of pure U(1) gauge theory in four dimensions, where two directions are non-commutative. Monte Carlo simulations are performed after mapping the regularized theory onto a U(N) lattice gauge theory in d = 2. At intermediate coupling strength, we find a phase in which open Wilson lines acquire non-zero vacuum expectation values, which implies the spontaneous breakdown of translational invariance. In this phase, various physical quantities obey clear scaling behaviors in the continuum limit with a fixed non-commutativity parameter θ, which provides evidence for a possible continuum theory. The extent of the dynamically generated space in the non-commutative directions becomes finite in the above limit, and its dependence on θ is evaluated explicitly. We also study the dispersion relation. In the weak coupling symmetric phase, it involves a negative IR-singular term, which is responsible for the observed phase transition. In the broken phase, it reveals the existence of the Nambu-Goldstone mode associated with the spontaneous symmetry breaking

Quantum fields in the non-perturbative regime. Yang-Mills theory and gravity

International Nuclear Information System (INIS)

Eichhorn, Astrid

2011-01-01

In this thesis we study candidates for fundamental quantum field theories, namely non-Abelian gauge theories and asymptotically safe quantum gravity. Whereas the first ones have a stronglyinteracting low-energy limit, the second one enters a non-perturbative regime at high energies. Thus, we apply a tool suited to the study of quantum field theories beyond the perturbative regime, namely the Functional Renormalisation Group. In a first part, we concentrate on the physical properties of non-Abelian gauge theories at low energies. Focussing on the vacuum properties of the theory, we present an evaluation of the full effective potential for the field strength invariant F μν F μν from non-perturbative gauge correlation functions and find a non-trivial minimum corresponding to the existence of a dimension four gluon condensate in the vacuum. We also relate the infrared asymptotic form of the β function of the running background-gauge coupling to the asymptotic behavior of Landau-gauge gluon and ghost propagators and derive an upper bound on their scaling exponents. We then consider the theory at finite temperature and study the nature of the confinement phase transition in d = 3+1 dimensions in various non-Abelian gauge theories. For SU(N) with N= 3,..,12 and Sp(2) we find a first-order phase transition in agreement with general expectations. Moreover our study suggests that the phase transition in E(7) Yang-Mills theory also is of first order. Our studies shed light on the question which property of a gauge group determines the order of the phase transition. In a second part we consider asymptotically safe quantum gravity. Here, we focus on the Faddeev-Popov ghost sector of the theory, to study its properties in the context of an interacting UV regime. We investigate several truncations, which all lend support to the conjecture that gravity may be asymptotically safe. In a first truncation, we study the ghost anomalous dimension which we find to be negative at the

Expectation propagation for large scale Bayesian inference of non-linear molecular networks from perturbation data.

Science.gov (United States)

Narimani, Zahra; Beigy, Hamid; Ahmad, Ashar; Masoudi-Nejad, Ali; Fröhlich, Holger

2017-01-01

Inferring the structure of molecular networks from time series protein or gene expression data provides valuable information about the complex biological processes of the cell. Causal network structure inference has been approached using different methods in the past. Most causal network inference techniques, such as Dynamic Bayesian Networks and ordinary differential equations, are limited by their computational complexity and thus make large scale inference infeasible. This is specifically true if a Bayesian framework is applied in order to deal with the unavoidable uncertainty about the correct model. We devise a novel Bayesian network reverse engineering approach using ordinary differential equations with the ability to include non-linearity. Besides modeling arbitrary, possibly combinatorial and time dependent perturbations with unknown targets, one of our main contributions is the use of Expectation Propagation, an algorithm for approximate Bayesian inference over large scale network structures in short computation time. We further explore the possibility of integrating prior knowledge into network inference. We evaluate the proposed model on DREAM4 and DREAM8 data and find it competitive against several state-of-the-art existing network inference methods.

Ground state energies from converging and diverging power series expansions

International Nuclear Information System (INIS)

Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E.; Su, Q.; Grobe, R.

2016-01-01

It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh–Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state’s spatial extension is comparable to L. Once the binding strength is so strong that the ground state’s extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

Ground state energies from converging and diverging power series expansions

Energy Technology Data Exchange (ETDEWEB)

Lisowski, C.; Norris, S.; Pelphrey, R.; Stefanovich, E., E-mail: eugene-stefanovich@usa.net; Su, Q.; Grobe, R.

2016-10-15

It is often assumed that bound states of quantum mechanical systems are intrinsically non-perturbative in nature and therefore any power series expansion methods should be inapplicable to predict the energies for attractive potentials. However, if the spatial domain of the Schrödinger Hamiltonian for attractive one-dimensional potentials is confined to a finite length L, the usual Rayleigh–Schrödinger perturbation theory can converge rapidly and is perfectly accurate in the weak-binding region where the ground state’s spatial extension is comparable to L. Once the binding strength is so strong that the ground state’s extension is less than L, the power expansion becomes divergent, consistent with the expectation that bound states are non-perturbative. However, we propose a new truncated Borel-like summation technique that can recover the bound state energy from the diverging sum. We also show that perturbation theory becomes divergent in the vicinity of an avoided-level crossing. Here the same numerical summation technique can be applied to reproduce the energies from the diverging perturbative sums.

Super Toeplitz operators and non-perturbative deformation quantization of supermanifolds

Energy Technology Data Exchange (ETDEWEB)

Borthwick, D.; Lesniewski, A.; Rinaldi, M. (Harvard Univ., Cambridge, MA (United States). Lyman Lab. of Physics); Klimek, S. (IUPUI, Indianapolis, IN (United States). Dept. of Mathematics)

1993-04-01

The purpose of this paper is to construct non-perturbative deformation quantizations of the algebras of smooth functions on Poisson supermanifolds. For the examples U[sup 1vertical] [sup stroke1] and C[sup mvertical] [sup stroken], algebras of super Toeplitz operators are defined with respect to certain Hilbert spaces of superholomorphic functions. Generators and relations for these algebras are given. The algebras can be thought of as algebras of 'quantized functions', and deformation conditions are proven which demonstrate the recovery of the super Piosson structures in a semi-classical limit. (orig.).

Synchronization of Two Non-Identical Coupled Exciters in a Non-Resonant Vibrating System of Linear Motion. Part I: Theoretical Analysis

Directory of Open Access Journals (Sweden)

Chunyu Zhao

2009-01-01

Full Text Available In this paper an analytical approach is proposed to study the feature of frequency capture of two non-identical coupled exciters in a non-resonant vibrating system. The electromagnetic torque of an induction motor in the quasi-steady-state operation is derived. With the introduction of two perturbation small parameters to average angular velocity of two exciters and their phase difference, we deduce the Equation of Frequency Capture by averaging two motion equations of two exciters over their average period. It converts the synchronization problem of two exciters into that of existence and stability of zero solution for the Equation of Frequency Capture. The conditions of implementing frequency capture and that of stabilizing synchronous operation of two motors have been derived. The concept of torque of frequency capture is proposed to physically explain the peculiarity of self-synchronization of the two exciters. An interesting conclusion is reached that the moments of inertia of the two exciters in the Equation of Frequency Capture reduce and there is a coupling moment of inertia between the two exciters. The reduction of moments of inertia and the coupling moment of inertia have an effect on the stability of synchronous operation.

Current Mode Control for LLC Series Resonant DC-to-DC Converters

OpenAIRE

Jinhaeng Jang; Syam Kumar Pidaparthy; Byungcho Choi

2015-01-01

Conventional voltage mode control only offers limited performance for LLC series resonant DC-to-DC converters experiencing wide variations in operational conditions. When the existing voltage mode control is employed, the closed-loop performance of the converter is directly affected by unavoidable changes in power stage dynamics. Thus, a specific control design optimized at one particular operating point could become unacceptable when the operational condition is varied. This paper presents a...

A view on coupled cluster perturbation theory using a bivariational Lagrangian formulation.

Science.gov (United States)

Kristensen, Kasper; Eriksen, Janus J; Matthews, Devin A; Olsen, Jeppe; Jørgensen, Poul

2016-02-14

We consider two distinct coupled cluster (CC) perturbation series that both expand the difference between the energies of the CCSD (CC with single and double excitations) and CCSDT (CC with single, double, and triple excitations) models in orders of the Møller-Plesset fluctuation potential. We initially introduce the E-CCSD(T-n) series, in which the CCSD amplitude equations are satisfied at the expansion point, and compare it to the recently developed CCSD(T-n) series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)], in which not only the CCSD amplitude, but also the CCSD multiplier equations are satisfied at the expansion point. The computational scaling is similar for the two series, and both are term-wise size extensive with a formal convergence towards the CCSDT target energy. However, the two series are different, and the CCSD(T-n) series is found to exhibit a more rapid convergence up through the series, which we trace back to the fact that more information at the expansion point is utilized than for the E-CCSD(T-n) series. The present analysis can be generalized to any perturbation expansion representing the difference between a parent CC model and a higher-level target CC model. In general, we demonstrate that, whenever the parent parameters depend upon the perturbation operator, a perturbation expansion of the CC energy (where only parent amplitudes are used) differs from a perturbation expansion of the CC Lagrangian (where both parent amplitudes and parent multipliers are used). For the latter case, the bivariational Lagrangian formulation becomes more than a convenient mathematical tool, since it facilitates a different and faster convergent perturbation series than the simpler energy-based expansion.

Dynamical gluon masses in perturbative calculations at the loop level

International Nuclear Information System (INIS)

Machado, Fatima A.; Natale, Adriano A.

2013-01-01

Full text: In the phenomenology of strong interactions one always has to deal at some extent with the interplay between perturbative and non-perturbative QCD. On one hand, the former has quite developed tools, yielded by asymptotic freedom. On the other, concerning the latter, we nowadays envisage the following scenario: 1) There are strong evidences for a dynamically massive gluon propagator and infrared finite coupling constant; 2) There is an extensive and successful use of an infrared finite coupling constant in phenomenological calculations at tree level; 3) The infrared finite coupling improves the perturbative series convergence; 4) The dynamical gluon mass provides a natural infrared cutoff in the physical processes at the tree level. Considering this scenario it is natural to ask how these non-perturbative results can be used in perturbative calculations of physical observables at the loop level. Recent papers discuss how off-shell gauge and renormalization group invariant Green functions can be computed with the use of the Pinch Technique (PT), with IR divergences removed by the dynamical gluon mass, and using a well defined effective charge. In this work we improve the former results by the authors, which evaluate 1-loop corrections to some two- and three-point functions of SU(3) pure Yang-Mills, investigating the dressing of quantities that could account for an extension of loop calculations to the infrared domain of the theory, in a way applicable to phenomenological calculations. One of these improvements is maintaining the gluon propagator transverse in such a scheme. (author)

Kato expansion in quantum canonical perturbation theory

International Nuclear Information System (INIS)

Nikolaev, Andrey

2016-01-01

This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.

Kato expansion in quantum canonical perturbation theory

Energy Technology Data Exchange (ETDEWEB)

Nikolaev, Andrey, E-mail: Andrey.Nikolaev@rdtex.ru [Institute of Computing for Physics and Technology, Protvino, Moscow Region, Russia and RDTeX LTD, Moscow (Russian Federation)

2016-06-15

This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.

Non-Perturbative QCD Coupling and Beta Function from Light Front Holography

International Nuclear Information System (INIS)

Brodsky, Stanley J.

2010-01-01

The light-front holographic mapping of classical gravity in AdS space, modified by a positive-sign dilaton background, leads to a non-perturbative effective coupling α s AdS (Q 2 ). It agrees with hadron physics data extracted from different observables, such as the effective charge defined by the Bjorken sum rule, as well as with the predictions of models with built-in confinement and lattice simulations. It also displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale ∼ 1 GeV. The resulting β-function appears to capture the essential characteristics of the full β-function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD. Commensurate scale relations relate observables to each other without scheme or scale ambiguity. In this paper we extrapolate these relations to the nonperturbative domain, thus extending the range of predictions based on α s AdS (Q 2 ).

Physics beyond the standard model in the non-perturbative unification scheme

International Nuclear Information System (INIS)

Kapetanakis, D.; Zoupanos, G.

1990-01-01

The non-perturbative unification scenario predicts reasonably well the low energy gauge couplings of the standard model. Agreement with the measured low energy couplings is obtained by assuming certain kind of physics beyond the standard model. A number of possibilities for physics beyond the standard model is examined. The best candidates so far are the standard model with eight fermionic families and a similar number of Higgs doublets, and the supersymmetric standard model with five families. (author)

Matching Pion-Nucleon Roy-Steiner Equations to Chiral Perturbation Theory

Science.gov (United States)

Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.

2015-11-01

We match the results for the subthreshold parameters of pion-nucleon scattering obtained from a solution of Roy-Steiner equations to chiral perturbation theory up to next-to-next-to-next-to-leading order, to extract the pertinent low-energy constants including a comprehensive analysis of systematic uncertainties and correlations. We study the convergence of the chiral series by investigating the chiral expansion of threshold parameters up to the same order and discuss the role of the Δ (1232 ) resonance in this context. Results for the low-energy constants are also presented in the counting scheme usually applied in chiral nuclear effective field theory, where they serve as crucial input to determine the long-range part of the nucleon-nucleon potential as well as three-nucleon forces.

Singular perturbation analysis of relaxation oscillations in reactor systems

International Nuclear Information System (INIS)

Ward, M.E.; Lee, J.C.

1987-01-01

A singular perturbation method for the analysis of large power oscillations in nuclear reactors is applied to obtain phase-plane solutions of the Ergen-Weinberg model. The system equations, recast in an appropriate form, directly give a first approximation to the closed trajectory in which the system behaviour is idealized as relaxation oscillations. Further approximations in the phase plane are determined using separate perturbation series on individual parts of the oscillation, with variations in the assignment of dependent and independent variables to consistently obtain convergent series. The accuracy of each order of the phase-plane solution increases with the magnitude of the power pulse in the actual physical situation. For realistic reactor conditions, both the trajectory and period of oscillation are well predicted using the first two terms of each perturbation series

Design of a Resonant Magnetic Perturbation ELM Suppression System for JET

International Nuclear Information System (INIS)

Agarici, G.; Becoulet, M.; Nardon, E.; Saille, A.; Thomas, P.R.; Verger, J.M.

2006-01-01

The suppression of ELMs with a Resonant Magnetic Perturbation (RMP), as demonstrated in DIIID experiments, is an attractive solution to the problem of divertor target erosion in ITER. Ideally, the RMP should be strong at the plasma edge and weak in the core, which requires the installation of the RMP coils as close as possible to the plasma. In both ITER and JET, an installation within the vacuum vessel would subject the coils to neutron irradiation, tritium contamination and all the problems of furnishing cooling and electrical services, across many interfaces. It has been proposed to install an '' ITER prototype '' RMP on JET. The nearest ex-vessel location, which avoids these difficulties and permits a suitable perturbation field, is between the poloidal field coils, P3 and P4. The proposed RMP system consists of 18 upper and 18 lower Ergodic field coils, arranged around the torus and located ∼ 2.5 m from the plasma edge. Each coil measures 0.9 m poloidally and 1.8 m toroidally, with a 30 cm cross-section and a weight near 1,4 tonne. 400 kA per coil are necessary to produce the radial magnetic field perturbation required for a plasma of 4 MA/3.4 T. Using a standard rectangular water-cooled conductor (OFHC copper plate 50 x 12.5 mm 2 with two holes inside), the coil can be built by winding 6 x 12 turns. In order to generate the required toroidal mode, n = 3, the current direction inside the coils will alternate every 3 coils. Vertical forces, up to 36 tonnes, and radial forces, up to 18 tonnes, due to the interaction between the machine main magnetic field and the coil current are withstood by a circular structure of 4 m diameter, made-out of 2 cm thick stainless-steel plates. Since the structure is toroidally continuous, the total radial forces counter balance each-other, whilst, via vertical supports, the vertical forces are taken by the 8 iron limbs of the external magnetic circuit. The installation of the coils is simplified by the circular geometry of the

Fundamental parameters of QCD from non-perturbative methods for two and four flavors

International Nuclear Information System (INIS)

Marinkovic, Marina

2013-01-01

The non-perturbative formulation of Quantumchromodynamics (QCD) on a four dimensional space-time Euclidean lattice together with the finite size techniques enable us to perform the renormalization of the QCD parameters non-perturbatively. In order to obtain precise predictions from lattice QCD, one needs to include the dynamical fermions into lattice QCD simulations. We consider QCD with two and four mass degenerate flavors of O(a) improved Wilson quarks. In this thesis, we improve the existing determinations of the fundamental parameters of two and four flavor QCD. In four flavor theory, we compute the precise value of the Λ parameter in the units of the scale L max defined in the hadronic regime. We also give the precise determination of the Schroedinger functional running coupling in four flavour theory and compare it to the perturbative results. The Monte Carlo simulations of lattice QCD within the Schroedinger Functional framework were performed with a platform independent program package Schroedinger Funktional Mass Preconditioned Hybrid Monte Carlo (SF-MP-HMC), developed as a part of this project. Finally, we compute the strange quark mass and the Λ parameter in two flavour theory, performing a well-controlled continuum limit and chiral extrapolation. To achieve this, we developed a universal program package for simulating two flavours of Wilson fermions, Mass Preconditioned Hybrid Monte Carlo (MP-HMC), which we used to run large scale simulations on small lattice spacings and on pion masses close to the physical value.

Nonlinear Plasma Response to Resonant Magnetic Perturbation in Rutherford Regime

Science.gov (United States)

Zhu, Ping; Yan, Xingting; Huang, Wenlong

2017-10-01

Recently a common analytic relation for both the locked mode and the nonlinear plasma response in the Rutherford regime has been developed based on the steady-state solution to the coupled dynamic system of magnetic island evolution and torque balance equations. The analytic relation predicts the threshold and the island size for the full penetration of resonant magnetic perturbation (RMP). It also rigorously proves a screening effect of the equilibrium toroidal flow. In this work, we test the theory by solving for the nonlinear plasma response to a single-helicity RMP of a circular-shaped limiter tokamak equilibrium with a constant toroidal flow, using the initial-value, full MHD simulation code NIMROD. Time evolution of the parallel flow or ``slip frequency'' profile and its asymptotic approach to steady state obtained from the NIMROD simulations qualitatively agree with the theory predictions. Further comparisons are carried out for the saturated island size, the threshold for full mode penetration, as well as the screening effects of equilibrium toroidal flow in order to understand the physics of nonlinear plasma response in the Rutherford regime. Supported by National Magnetic Confinement Fusion Science Program of China Grants 2014GB124002 and 2015GB101004, the 100 Talent Program of the Chinese Academy of Sciences, and U.S. Department of Energy Grants DE-FG02-86ER53218 and DE-FC02-08ER54975.

Approximations to the non-adiabatic particle response in toroidal geometry

International Nuclear Information System (INIS)

Schep, T.J.; Braams, B.J.

1981-08-01

The non-adiabatic part of the particle response to low-frequency electromagnetic modes with long parallel wavelengths is discussed. Analytic approximations to the kernels of the integrals that relate the amplitudes of the perturbed potentials to the non-adiabatic part of the perturbed density in an axisymmetric toroidal configuration are presented and the results are compared with numerical calculations. It is shown that both in the plane slab and in toroidal geometry the kernel contains a logarithmic singularity. This singularity is associated with particles with vanishing parallel velocity so that, in toroidal geometry, it is related with the behaviour of trapped particles near their turning points. In contrast to the plane slab, in toroidal geometry this logarithmic singularity is mainly real and associated with non-resonant particles. Apart from this logarithmic term, the kernel contains a complex regular part arising from resonant as well as from non-resonant particles. The analytic approximations that will be presented make the dispersion relation of drift-type modes in toroidal geometry amenable to analytic as well as to simpler numerical calculation of the growth rate and of the spatial mode structure

A phenomenological analysis of non-resonant charm meson decays

International Nuclear Information System (INIS)

Bediaga, I.; Goebel, C.; Mendez-Galain, R.

1997-07-01

We analyse the consequences of the usual assumption of a constant function to fit non-resonant decays from experimental Dalitz plot describing charmed meson decays. We first show, using the D + -> K 0 π + π 0 decay channel as an example, how an inadequate extraction of the non-resonant contribution could yield incorrect measurements for the resonant channels. We analyse how the correct study of this decay will provide a test for the validity of factorization in D meson decays. Finally, we show how form factors that can be measured from the D + s -> π - π + π + decay. We emphasize its relevance for the study of the decay τ -> v t 3π and the extraction of the α 1 meson width. (author)

Comparisons of linear and nonlinear plasma response models for non-axisymmetric perturbations

Energy Technology Data Exchange (ETDEWEB)

Turnbull, A. D.; Ferraro, N. M.; Lao, L. L.; Lanctot, M. J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Izzo, V. A. [University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Lazarus, E. A.; Hirshman, S. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Park, J.-K.; Lazerson, S.; Reiman, A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Cooper, W. A. [Association Euratom-Confederation Suisse, Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Turco, F. [Columbia University, 116th St and Broadway, New York, New York 10027 (United States)

2013-05-15

With the installation of non-axisymmetric coil systems on major tokamaks for the purpose of studying the prospects of ELM-free operation, understanding the plasma response to the applied fields is a crucial issue. Application of different response models, using standard tools, to DIII-D discharges with applied non-axisymmetric fields from internal coils, is shown to yield qualitatively different results. The plasma response can be treated as an initial value problem, following the system dynamically from an initial unperturbed state, or from a nearby perturbed equilibrium approach, and using both linear and nonlinear models [A. D. Turnbull, Nucl. Fusion 52, 054016 (2012)]. Criteria are discussed under which each of the approaches can yield a valid response. In the DIII-D cases studied, these criteria show a breakdown in the linear theory despite the small 10{sup −3} relative magnitude of the applied magnetic field perturbations in this case. For nonlinear dynamical evolution simulations to reach a saturated nonlinear steady state, appropriate damping mechanisms need to be provided for each normal mode comprising the response. Other issues arise in the technical construction of perturbed flux surfaces from a displacement and from the presence of near nullspace normal modes. For the nearby equilibrium approach, in the absence of a full 3D equilibrium reconstruction with a controlled comparison, constraints relating the 2D system profiles to the final profiles in the 3D system also need to be imposed to assure accessibility. The magnetic helicity profile has been proposed as an appropriate input to a 3D equilibrium calculation and tests of this show the anticipated qualitative behavior.

Non-perturbative heavy quark effective theory. An application to semi-leptonic B-decays

International Nuclear Information System (INIS)

Della Morte, Michele; Heitger, Jochen; Simma, Hubert; Sommer, Rainer; Humboldt-Universitaet, Berlin

2015-01-01

We review a lattice strategy how to non-perturbatively determine the coefficients in the HQET expansion of all components of the heavy-light axial and vector currents, including 1/m h -corrections. We also discuss recent preliminary results on the form factors parameterizing semi-leptonic B-decays at the leading order in 1/m h .

Perturbation approach for nuclear magnetic resonance solid-state quantum computation

Directory of Open Access Journals (Sweden)

G. P. Berman

2003-01-01

Full Text Available A dynamics of a nuclear-spin quantum computer with a large number (L=1000 of qubits is considered using a perturbation approach. Small parameters are introduced and used to compute the error in an implementation of an entanglement between remote qubits, using a sequence of radio-frequency pulses. The error is computed up to the different orders of the perturbation theory and tested using exact numerical solution.

A non-perturbative approach to jet cross-sections and a new model for hadron-hadron interactions

International Nuclear Information System (INIS)

Andersson, B.

1986-01-01

The author discusses two subjects in this work. The first is a description of a non-perturbative approach to calculate the probabilities to obtain a particular state of confined force field in a hard interaction like e/sup +/e/sup -/ annihilation. This approach has been discussed previously by the author. There are at this time many more results of the program, in particular, some rather puzzling and disturbing ones as compared to the results obtained in perturbative QCD. The second subject is a new approach to hadron-hadron inelastic scattering. A model for these interactions based upon multiple perturbative parton interactions and subsequent string-stretching and breaking has been formulated by others in earlier works

H{sup +}{sub 2} ionization by ultra-short electromagnetic pulses investigated through a non-perturbative Coulomb-Volkov approach

Energy Technology Data Exchange (ETDEWEB)

RodrIguez, V D [Departamento de Fisica, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Macri, P [Departamento de Fisica, FCEyN, Universidad de Buenos Aires, 1428 Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio, Consejo Nacional de Investigaciones CientIficas y Tecnicas, 1428 Buenos Aires (Argentina); Gayet, R [CELIA, Centre Lasers Intenses et Applications, UMR 5107, Unite Mixte de Recherche CNRS-CEA-Universite Bordeaux 1, Universite Bordeaux 1, 351 Cours de la Liberation, 33405 Talence Cedex (France)

2005-08-14

The sudden Coulomb-Volkov theoretical approximation has been shown to well describe atomic ionization by intense and ultra-short electromagnetic pulses, such as pulses generated by very fast highly-charged ions. This approach is extended here to investigate single ionization of homonuclear diatomic molecules by such pulses in the framework of one-active electron. Under particular conditions, a Young-like interference formula can approximately be factored out. Present calculations show interference effects originating from the molecular two-centre structure. Fivefold differential angular distributions of the ejected electron are studied as a function of the molecular orientation and internuclear distance. Both non-perturbative and perturbative regimes are examined. In the non-perturbative case, an interference pattern is visible but a main lobe, opposite to the electric field polarization direction, dominates the angular distribution. In contrast, in perturbation conditions the structure of interferences shows analogies to the Young-like interference pattern obtained in ionization of molecules by fast electron impacts. Finally, the strong dependence of these Young-like angular distributions on the internuclear distance is addressed.

Parametric Resonance in the Early Universe - A Fitting Analysis

CERN Document Server

Figueroa, Daniel G.

2017-02-01

Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in $3+1$ dimensions, we parametrise the dynamics' outcome scanning over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasise the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequ...

Recursive approach for non-Markovian time-convolutionless master equations

Science.gov (United States)

Gasbarri, G.; Ferialdi, L.

2018-02-01

We consider a general open system dynamics and we provide a recursive method to derive the associated non-Markovian master equation in a perturbative series. The approach relies on a momenta expansion of the open system evolution. Unlike previous perturbative approaches of this kind, the method presented in this paper provides a recursive definition of each perturbative term. Furthermore, we give an intuitive diagrammatic description of each term of the series, which provides a useful analytical tool to build them and to derive their structure in terms of commutators and anticommutators. We eventually apply our formalism to the evolution of the observables of the reduced system, by showing how the method can be applied to the adjoint master equation, and by developing a diagrammatic description of the associated series.

The FLUKA Monte Carlo, Non-Perturbative QCD and Cosmic Ray Cascades

International Nuclear Information System (INIS)

Battistoni, G.

2005-01-01

The FLUKA Monte Carlo code, presently used in cosmic ray physics, contains packages to sample soft hadronic processes which are built according to the Dual Parton Model. This is a phenomenological model capable of reproducing many of the features of hadronic collisions in the non perturbative QCD regime. The basic principles of the model are summarized and, as an example, the associated Lambda-K production is discussed. This is a process which has some relevance for the calculation of atmospheric neutrino fluxes

Perturbation theory of effective Hamiltonians

International Nuclear Information System (INIS)

Brandow, B.H.

1975-01-01

This paper constitutes a review of the many papers which have used perturbation theory to derive ''effective'' or ''model'' Hamiltonians. It begins with a brief review of nondegenerate and non-many-body perturbation theory, and then considers the degenerate but non-many-body problem in some detail. It turns out that the degenerate perturbation problem is not uniquely defined, but there are some practical criteria for choosing among the various possibilities. Finally, the literature dealing with the linked-cluster aspects of open-shell many-body systems is reviewed. (U.S.)

Regenerative feedback resonant circuit

Science.gov (United States)

Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

2014-09-02

A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

Perturbation of embedded eigenvalue by a near-lying resonance

Energy Technology Data Exchange (ETDEWEB)

Belyaev, V B; Motovilov, A K

1997-12-31

The case of quantum-mechanical system (including electronic molecules) is considered where Hamiltonian allows a separation, in particular by the Faddeev method, of a weakly coupled channel. Width (i.e. the imaginary part) of the resonance generated by a discrete spectrum eigenvalue of the separated channel is studied in the case where main part of the Hamiltonian gives itself another resonance. It is shown that if real parts of these resonances coincide and, at the same time, a coupling between the separated and main channels is sufficiently small then the width of the resonance generated by the separated (molecular) channel is inversely proportional to the width of the main (nuclear) channel resonance. This phenomenon being a kind of universal law, may play an important role increasing the `cold fusion` probability in electronic molecules whose nuclear constituents have narrow pre-threshold resonances. 21 refs.

A non-perturbative study of 4d U(1) non-commutative gauge theory — the fate of one-loop instability

Science.gov (United States)

Bietenholz, Wolfgang; Nishimura, Jun; Susaki, Yoshiaki; Volkholz, Jan

2006-10-01

Recent perturbative studies show that in 4d non-commutative spaces, the trivial (classically stable) vacuum of gauge theories becomes unstable at the quantum level, unless one introduces sufficiently many fermionic degrees of freedom. This is due to a negative IR-singular term in the one-loop effective potential, which appears as a result of the UV/IR mixing. We study such a system non-perturbatively in the case of pure U(1) gauge theory in four dimensions, where two directions are non-commutative. Monte Carlo simulations are performed after mapping the regularized theory onto a U(N) lattice gauge theory in d = 2. At intermediate coupling strength, we find a phase in which open Wilson lines acquire non-zero vacuum expectation values, which implies the spontaneous breakdown of translational invariance. In this phase, various physical quantities obey clear scaling behaviors in the continuum limit with a fixed non-commutativity parameter θ, which provides evidence for a possible continuum theory. The extent of the dynamically generated space in the non-commutative directions becomes finite in the above limit, and its dependence on θ is evaluated explicitly. We also study the dispersion relation. In the weak coupling symmetric phase, it involves a negative IR-singular term, which is responsible for the observed phase transition. In the broken phase, it reveals the existence of the Nambu-Goldstone mode associated with the spontaneous symmetry breaking.

Modeling of divertor particle and heat loads during application of resonant magnetic perturbation fields for ELM control in ITER

Energy Technology Data Exchange (ETDEWEB)

Schmitz, O., E-mail: o.schmitz@fz-juelich.de [Forschungszentrum Jülich, IEK-4, Association EURATOM-FZJ, Jülich (Germany); Becoulet, M. [CEA/IRFM, Cadarache, 13108 St. Paul-lez-Durance Cedex (France); Cahyna, P. [IPP AS CR, Za Slovankou 3, 18200 Prague 8 (Czech Republic); Evans, T.E. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Feng, Y. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Frerichs, H.; Kirschner, A. [Forschungszentrum Jülich, IEK-4, Association EURATOM-FZJ, Jülich (Germany); Kukushkin, A. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Laengner, R. [Forschungszentrum Jülich, IEK-4, Association EURATOM-FZJ, Jülich (Germany); Lunt, T. [Max-Planck-Institut für Plasmaphysik, Greifswald (Germany); Loarte, A.; Pitts, R. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Reiser, D.; Reiter, D. [Forschungszentrum Jülich, IEK-4, Association EURATOM-FZJ, Jülich (Germany); Saibene, G. [Fusion for Energy Joint Undertaking, Barcelona (Spain); Samm, U. [Forschungszentrum Jülich, IEK-4, Association EURATOM-FZJ, Jülich (Germany)

2013-07-15

First results from three-dimensional modeling of the divertor heat and particle flux pattern during application of resonant magnetic perturbation fields as ELM control scheme in ITER with the EMC3-Eirene fluid plasma and kinetic neutral transport code are discussed. The formation of a helical magnetic footprint breaks the toroidal symmetry of the heat and particle fluxes. Expansion of the flux pattern as far as 60 cm away from the unperturbed strike line is seen with vacuum RMP fields, resulting in a preferable heat flux spreading. Inclusion of plasma response reduces the radial extension of the heat and particle fluxes and results in a heat flux peaking closer to the unperturbed level. A strong reduction of the particle confinement is found. 3D flow channels are identified as a consistent reason due to direct parallel outflow from inside of the separatrix. Their radial inward expansion and hence the level of particle pump out is shown to be dependent on the perturbation level.

(Non)perturbative gravity, nonlocality, and nice slices

International Nuclear Information System (INIS)

Giddings, Steven B.

2006-01-01

Perturbative dynamics of gravity is investigated for high-energy scattering and in black hole backgrounds. In the latter case, a straightforward perturbative analysis fails, in a close parallel to the failure of the former when the impact parameter reaches the Schwarzschild radius. This suggests a flaw in a semiclassical description of physics on spatial slices that intersect both outgoing Hawking radiation and matter that has carried information into a black hole; such slices are instrumental in a general argument for black hole information loss. This indicates a possible role for the proposal that nonperturbative gravitational physics is intrinsically nonlocal

Orbital Resonances in the Vinti Solution

Science.gov (United States)

Zurita, L. D.

As space becomes more congested, contested, and competitive, high-accuracy orbital predictions become critical for space operations. Current orbit propagators use the two-body solution with perturbations added, which have significant error growth when numerically integrated for long time periods. The Vinti Solution is a more accurate model than the two-body problem because it also accounts for the equatorial bulge of the Earth. Unfortunately, the Vinti solution contains small divisors near orbital resonances in the perturbative terms of the Hamiltonian, which lead to inaccurate orbital predictions. One approach to avoid the small divisors is to apply transformation theory, which is presented in this research. The methodology of this research is to identify the perturbative terms of the Vinti Solution, perform a coordinate transformation, and derive the new equations of motion for the Vinti system near orbital resonances. An analysis of these equations of motion offers insight into the dynamics found near orbital resonances. The analysis in this research focuses on the 2:1 resonance, which includes the Global Positioning System. The phase portrait of a nominal Global Positioning System satellite orbit is found to contain a libration region and a chaotic region. Further analysis shows that the dynamics of the 2:1 resonance affects orbits with semi-major axes ranging from -5.0 to +5.4 kilometers from an exactly 2:1 resonant orbit. Truth orbits of seven Global Positioning System satellites are produced for 10 years. Two of the satellites are found to be outside of the resonance region and three are found to be influenced by the libration dynamics of the resonance. The final satellite is found to be influenced by the chaotic dynamics of the resonance. This research provides a method of avoiding the small divisors found in the perturbative terms of the Vinti Solution near orbital resonances.

Non-perturbative measurement of low-intensity charged particle beams

Science.gov (United States)

Fernandes, M.; Geithner, R.; Golm, J.; Neubert, R.; Schwickert, M.; Stöhlker, T.; Tan, J.; Welsch, C. P.

2017-01-01

Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of 30 {nA}.

Non-perturbative improvement of the axial current with three dynamical flavors and the Iwasaki gauge action

International Nuclear Information System (INIS)

Kaneko, T.; Hashimoto, S.; Aoki, S.; Hoffmann, R.

2007-03-01

We perform a non-perturbative determination of the improvement coefficient c A to remove O(a) discretization errors in the axial vector current in three-flavor lattice QCD with the Iwasaki gauge action and the standard O(a)-improved Wilson quark action. An improvement condition with a good sensitivity to c A is imposed at constant physics. Combining our results with the perturbative expansion, c A is now known rather precisely for a -1 >or similar 1.6 GeV. (orig.)

Orbital resonances of Taiwan's FORMOSAT-2 remote sensing satellite

Science.gov (United States)

Lin, Shin-Fa; Hwang, Cheinway

2018-06-01

Unlike a typical remote sensing satellite that has a global coverage and non-integral orbital revolutions per day, Taiwan's FORMOSAT-2 (FS-2) satellite has a non-global coverage due to the mission requirements of one-day repeat cycle and daily visit around Taiwan. These orbital characteristics result in an integer number of revolutions a day and orbital resonances caused by certain components of the Earth's gravity field. Orbital flight data indicated amplified variations in the amplitudes of FS-2's Keplerian elements. We use twelve years of orbital observations and maneuver data to analyze the cause of the resonances and explain the differences between the simulated (at the pre-launch stage) and real orbits of FS-2. The differences are quantified using orbital perturbation theories that describe secular and long-period orbital evolutions caused by resonances. The resonance-induced orbital rising rate of FS-2 reaches +1.425 m/day, due to the combined (modeled) effect of resonances and atmospheric drags (the relative modeling errors remote sensing mission similar to FS-2, especially in the early mission design and planning phase.

A study on stimulation of DC high voltage power of LCC series parallel resonant in projectile velocity measurement system

Science.gov (United States)

Lu, Dong-dong; Gu, Jin-liang; Luo, Hong-e.; Xia, Yan

2017-10-01

According to specific requirements of the X-ray machine system for measuring velocity of outfield projectile, a DC high voltage power supply system is designed for the high voltage or the smaller current. The system comprises: a series resonant circuit is selected as a full-bridge inverter circuit; a high-frequency zero-current soft switching of a high-voltage power supply is realized by PWM output by STM32; a nanocrystalline alloy transformer is chosen as a high-frequency booster transformer; and the related parameters of an LCC series-parallel resonant are determined according to the preset parameters of the transformer. The concrete method includes: a LCC series parallel resonant circuit and a voltage doubling circuit are stimulated by using MULTISM and MATLAB; selecting an optimal solution and an optimal parameter of all parts after stimulation analysis; and finally verifying the correctness of the parameter by stimulation of the whole system. Through stimulation analysis, the output voltage of the series-parallel resonant circuit gets to 10KV in 28s: then passing through the voltage doubling circuit, the output voltage gets to 120KV in one hour. According to the system, the wave range of the output voltage is so small as to provide the stable X-ray supply for the X-ray machine for measuring velocity of outfield projectile. It is fast in charging and high in efficiency.

Non-integrable quantum field theories as perturbations of certain integrable models

International Nuclear Information System (INIS)

Delfino, G.; Simonetti, P.

1996-03-01

We approach the study of non-integrable models of two-dimensional quantum field theory as perturbations of the integrable ones. By exploiting the knowledge of the exact S-matrix and Form Factors of the integrable field theories we obtain the first order corrections to the mass ratios, the vacuum energy density and the S-matrix of the non-integrable theories. As interesting applications of the formalism, we study the scaling region of the Ising model in an external magnetic field at T ∼ T c and the scaling region around the minimal model M 2 , τ . For these models, a remarkable agreement is observed between the theoretical predictions and the data extracted by a numerical diagonalization of their Hamiltonian. (author). 41 refs, 9 figs, 1 tab

Non-perturbative computation of the strong coupling constant on the lattice

International Nuclear Information System (INIS)

Sommer, Rainer; Humboldt-Universitaet, Berlin; Wolff, Ulli

2015-01-01

We review the long term project of the ALPHA collaboration to compute in QCD the running coupling constant and quark masses at high energy scales in terms of low energy hadronic quantities. The adapted techniques required to numerically carry out the required multiscale non-perturbative calculation with our special emphasis on the control of systematic errors are summarized. The complete results in the two dynamical flavor approximation are reviewed and an outlook is given on the ongoing three flavor extension of the programme with improved target precision.

Distribution functions for resonantly trapped orbits in the Galactic disc

Science.gov (United States)

Monari, Giacomo; Famaey, Benoit; Fouvry, Jean-Baptiste; Binney, James

2017-11-01

The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment, however, leads to singularities at resonances, which prevent quantitative comparisons with data. Here, we manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then follow the prescription of Binney, assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits depends only on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of DFs in action space.

Coupling effects of resonant and discretized non-resonant continuum states in 4He+6Li scattering at 10 MeV/A

International Nuclear Information System (INIS)

Sinha, T.; Kanungo, R.; Samanta, C.; Ghosh, S.; Basu, P.; Rebel, H.

1996-01-01

Alpha- particle scattering from the resonant (3 + 1 ) and non-resonant continuum states of 6 Li is studied at incident energy 10 MeV/A. The α+d breakup continuum part within the excitation energy E ex = 1.475-2.475 MeV is discretized in two energy bins. Unlike the results at higher incident energies, here the coupled-channel calculations show significant breakup continuum coupling effects on the elastic and inelastic scattering. It is shown that even when the continuum-continuum coupling effects are strong, the experimental data of the ground state and the resonant as well as discretized non-resonant continuum states impose stringent constraint on the coupling strengths of the non-resonant continuum states. (orig.). With 2 figs., 1 tab

Cosmological perturbation theory and quantum gravity

Energy Technology Data Exchange (ETDEWEB)

Brunetti, Romeo [Dipartimento di Matematica, Università di Trento,Via Sommarive 14, 38123 Povo TN (Italy); Fredenhagen, Klaus [II Institute für Theoretische Physik, Universität Hamburg,Luruper Chaussee 149, 22761 Hamburg (Germany); Hack, Thomas-Paul [Institute für Theoretische Physik, Universität Leipzig,Brüderstr. 16, 04103 Leipzig (Germany); Pinamonti, Nicola [Dipartimento di Matematica, Università di Genova,Via Dodecaneso 35, 16146 Genova (Italy); INFN, Sezione di Genova,Via Dodecaneso 33, 16146 Genova (Italy); Rejzner, Katarzyna [Department of Mathematics, University of York,Heslington, York YO10 5DD (United Kingdom)

2016-08-04

It is shown how cosmological perturbation theory arises from a fully quantized perturbative theory of quantum gravity. Central for the derivation is a non-perturbative concept of gauge-invariant local observables by means of which perturbative invariant expressions of arbitrary order are generated. In particular, in the linearised theory, first order gauge-invariant observables familiar from cosmological perturbation theory are recovered. Explicit expressions of second order quantities are presented as well.

Resonant ultrasound spectroscopy and non-destructive testing

Science.gov (United States)

Migliori, A.; Darling, T. W.

The use of mechanical resonances to test properties of materials is perhaps older than the industrial revolution. Early documented cases of British railroad engineers tapping the wheels of a train and using the sound to detect cracks perhaps mark the first real use of resonances to test the integrity of high-performance alloys. Attempts were made in the following years to understand the resonances of solids mathematically, based on the shape and composition. But Nobel Laureate Lord Rayleigh best summarized the state of affairs in 1894, stating 'the problem has, for the most part, resisted attack'. More recently, modern computers and electronics have enabled Anderson and co-workers with their work on minerals, and our work at Los Alamos on new materials and manufactured components to advance the use of resonances to a precision non-destructive testing tool that makes anisotropic modulus measurements, defect detection and geometry error detection routine. The result is that resonances can achieve the highest absolute accuracy for any dynamic modulus measurement technique, can be used on the smallest samples, and can also enable detection of errors in certain classes of precision manufactured components faster and more accurately than any other technique.

Non-resonant terahertz field enhancement in periodically arranged nanoslits

DEFF Research Database (Denmark)

Novitsky, Andrey; Ivinskaya, Aliaksandra; Zalkovskij, Maksim

2012-01-01

We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength λ of the impinging radiatio...... by the microscopic Drude-Lorentz model taking into account retardation processes in the metal film and validated by the finite difference frequency domain method. We expect sensor and modulation applications of the predicted giant broadband field enhancement.......We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength λ of the impinging radiation...... approaches the THz wavelength but before entering the Raleigh-Wood anomaly, the field enhancement in nanoslit stays close to that in a single isolated slit, i.e., the well-known inversefrequency dependence. Both regimes are non-resonant and thus extremely broadband for P

Divergence of perturbation theory in large scale structures

Science.gov (United States)

Pajer, Enrico; van der Woude, Drian

2018-05-01

We make progress towards an analytical understanding of the regime of validity of perturbation theory for large scale structures and the nature of some non-perturbative corrections. We restrict ourselves to 1D gravitational collapse, for which exact solutions before shell crossing are known. We review the convergence of perturbation theory for the power spectrum, recently proven by McQuinn and White [1], and extend it to non-Gaussian initial conditions and the bispectrum. In contrast, we prove that perturbation theory diverges for the real space two-point correlation function and for the probability density function (PDF) of the density averaged in cells and all the cumulants derived from it. We attribute these divergences to the statistical averaging intrinsic to cosmological observables, which, even on very large and "perturbative" scales, gives non-vanishing weight to all extreme fluctuations. Finally, we discuss some general properties of non-perturbative effects in real space and Fourier space.

Non-Perturbative QCD Coupling and Beta Function from Light Front Holography

Energy Technology Data Exchange (ETDEWEB)

Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.; Deur, Alexandre; /Jefferson Lab

2010-05-26

The light-front holographic mapping of classical gravity in AdS space, modified by a positive-sign dilaton background, leads to a non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q{sup 2}). It agrees with hadron physics data extracted from different observables, such as the effective charge defined by the Bjorken sum rule, as well as with the predictions of models with built-in confinement and lattice simulations. It also displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale {approx} 1 GeV. The resulting {beta}-function appears to capture the essential characteristics of the full {beta}-function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD. Commensurate scale relations relate observables to each other without scheme or scale ambiguity. In this paper we extrapolate these relations to the nonperturbative domain, thus extending the range of predictions based on {alpha}{sub s}{sup AdS} (Q{sup 2}).

Quantum fields in the non-perturbative regime. Yang-Mills theory and gravity

Energy Technology Data Exchange (ETDEWEB)

Eichhorn, Astrid

2011-09-06

In this thesis we study candidates for fundamental quantum field theories, namely non-Abelian gauge theories and asymptotically safe quantum gravity. Whereas the first ones have a stronglyinteracting low-energy limit, the second one enters a non-perturbative regime at high energies. Thus, we apply a tool suited to the study of quantum field theories beyond the perturbative regime, namely the Functional Renormalisation Group. In a first part, we concentrate on the physical properties of non-Abelian gauge theories at low energies. Focussing on the vacuum properties of the theory, we present an evaluation of the full effective potential for the field strength invariant F{sub {mu}}{sub {nu}}F{sup {mu}}{sup {nu}} from non-perturbative gauge correlation functions and find a non-trivial minimum corresponding to the existence of a dimension four gluon condensate in the vacuum. We also relate the infrared asymptotic form of the {beta} function of the running background-gauge coupling to the asymptotic behavior of Landau-gauge gluon and ghost propagators and derive an upper bound on their scaling exponents. We then consider the theory at finite temperature and study the nature of the confinement phase transition in d = 3+1 dimensions in various non-Abelian gauge theories. For SU(N) with N= 3,..,12 and Sp(2) we find a first-order phase transition in agreement with general expectations. Moreover our study suggests that the phase transition in E(7) Yang-Mills theory also is of first order. Our studies shed light on the question which property of a gauge group determines the order of the phase transition. In a second part we consider asymptotically safe quantum gravity. Here, we focus on the Faddeev-Popov ghost sector of the theory, to study its properties in the context of an interacting UV regime. We investigate several truncations, which all lend support to the conjecture that gravity may be asymptotically safe. In a first truncation, we study the ghost anomalous dimension

Radiative bound-state formation in unbroken perturbative non-Abelian theories and implications for dark matter

OpenAIRE

Harz, Julia; Petraki, Kalliopi

2018-01-01

We compute the cross-sections for the radiative capture of non-relativistic particles into bound states, in unbroken perturbative non-Abelian theories. We find that the formation of bound states via emission of a gauge boson can be significant for a variety of dark matter models that feature non-Abelian long-range interactions, including multi-TeV scale WIMPs and dark matter co-annihilating with coloured partners. Our results disagree with previous computations, on the relative sign of the Ab...

Non-perturbative improvement of the axial current with three dynamical flavors and the Iwasaki gauge action

Energy Technology Data Exchange (ETDEWEB)

Kaneko, T.; Hashimoto, S. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan)]|[Graduate Univ. for Advanced Studies, Tsukuba, Ibaraki (Japan); Aoki, S. [Tsukuba Univ., Ibaraki (Japan). Graduate School of Pure and Applied Sciences]|[Brookhaven National Laboratory, Upton, NY (United States). Riken BNL Research Center; Della Morte, M. [CERN, Physics Dept., Geneva (Switzerland); Hoffmann, R. [Colorado Univ., Boulder, CO (United States). Dept. of Physics; Sommer, R. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2007-03-15

We perform a non-perturbative determination of the improvement coefficient c{sub A} to remove O(a) discretization errors in the axial vector current in three-flavor lattice QCD with the Iwasaki gauge action and the standard O(a)-improved Wilson quark action. An improvement condition with a good sensitivity to c{sub A} is imposed at constant physics. Combining our results with the perturbative expansion, c{sub A} is now known rather precisely for a{sup -1}>or similar 1.6 GeV. (orig.)

Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak

Science.gov (United States)

Yan, W.; Chen, Z. Y.; Huang, D. W.; Hu, Q. M.; Shi, Y. J.; Ding, Y. H.; Cheng, Z. F.; Yang, Z. J.; Pan, X. M.; Lee, S. G.; Tong, R. H.; Wei, Y. N.; Dong, Y. B.; J-TEXT Team

2018-03-01

The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s-1 in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.

A phenomenological analysis of non-resonant charm meson decays

Energy Technology Data Exchange (ETDEWEB)

Bediaga, I.; Goebel, C. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Mendez-Galain, R. [Montevideo Univ. (Uruguay). Facultad de Ingenieria

1997-07-01

We analyse the consequences of the usual assumption of a constant function to fit non-resonant decays from experimental Dalitz plot describing charmed meson decays. We first show, using the D{sup +} -> K{sup 0} {pi}{sup +} {pi}{sup 0} decay channel as an example, how an inadequate extraction of the non-resonant contribution could yield incorrect measurements for the resonant channels. We analyse how the correct study of this decay will provide a test for the validity of factorization in D meson decays. Finally, we show how form factors that can be measured from the D{sup +}{sub s} -> {pi}{sup -} {pi}{sup +} {pi}{sup +} decay. We emphasize its relevance for the study of the decay {tau} -> v{sub t} 3{pi} and the extraction of the {alpha}{sub 1} meson width. (author) 26 refs., 6 figs.

Formation of magnetic islands due to field perturbations in toroidal stellarator configurations

International Nuclear Information System (INIS)

Lee, D.K.; Harris, J.H.; Lee, G.S.

1990-06-01

An explicit formulation is developed to determine the width of a magnetic island separatrix generated by magnetic field perturbations in a general toroidal stellarator geometry. A conventional method is employed to recast the analysis in a magnetic flux coordinate system without using any simplifying approximations. The island width is seen to be proportional to the square root of the Fourier harmonic of B ρ /B ζ that is in resonance with the rational value of the rotational transform, where B ρ and B ζ are contravariant normal and toroidal components of the perturbed magnetic field, respectively. The procedure, which is based on a representation of three-dimensional flux surfaces by double Fourier series, allows rapid and fairly accurate calculation of the island widths in real vacuum field configurations, without the need to follow field lines through numerical integration of the field line equations. Numerical results of the island width obtained in the flux coordinate representation for the Advanced Toroidal Facility agree closely with those determined from Poincare puncture points obtained by following field lines. 22 refs., 5 tabs

Diagnosis of pericardial cysts using diffusion weighted magnetic resonance imaging: A case series

Directory of Open Access Journals (Sweden)

Mousavi Negareh

2011-09-01

Full Text Available Abstract Introduction Congenital pericardial cysts are benign lesions that arise from the pericardium during embryonic development. The diagnosis is based on typical imaging features, but atypical locations and signal magnetic resonance imaging sequences make it difficult to exclude other lesions. Diffusion-weighted magnetic resonance imaging is a novel method that can be used to differentiate tissues based on their restriction to proton diffusion. Its use in differentiating pericardial cysts from other pericardial lesions has not yet been described. Case presentation We present three cases (a 51-year-old Caucasian woman, a 66-year-old Caucasian woman and a 77-year-old Caucasian woman with pericardial cysts evaluated with diffusion-weighted imaging using cardiac magnetic resonance imaging. Each lesion demonstrated a high apparent diffusion coefficient similar to that of free water. Conclusion This case series is the first attempt to investigate the utility of diffusion-weighted magnetic resonance imaging in the assessment of pericardial cysts. Diffusion-weighted imaging may be a useful noninvasive diagnostic tool for pericardial cysts when conventional imaging findings are inconclusive.

Computer Simulation of Phase Shifted Series Resonant DC to DC Converter

Directory of Open Access Journals (Sweden)

P. PARVATHY

2016-01-01

Full Text Available This paper deals with digital simulation of phase shifted series resonant DC to DC converter using Matlab Simulink. The Simulink models for open loop and closed loop systems are developed and they are used for simulation studies. This converter is capable of producing ripple free DC output. Switching losses and switching stresses are reduced by using soft switching. This converter has advantages like high power density and low switching losses. Theoretical predictions are well supported by the simulation results.

Twisting perturbed parafermions

Directory of Open Access Journals (Sweden)

A.V. Belitsky

2017-07-01

Full Text Available The near-collinear expansion of scattering amplitudes in maximally supersymmetric Yang–Mills theory at strong coupling is governed by the dynamics of stings propagating on the five sphere. The pentagon transitions in the operator product expansion which systematize the series get reformulated in terms of matrix elements of branch-point twist operators in the two-dimensional O(6 nonlinear sigma model. The facts that the latter is an asymptotically free field theory and that there exists no local realization of twist fields prevents one from explicit calculation of their scaling dimensions and operator product expansion coefficients. This complication is bypassed making use of the equivalence of the sigma model to the infinite-level limit of WZNW models perturbed by current–current interactions, such that one can use conformal symmetry and conformal perturbation theory for systematic calculations. Presently, to set up the formalism, we consider the O(3 sigma model which is reformulated as perturbed parafermions.

Reviving Graduate Seminar Series through Non-Technical Presentations

Science.gov (United States)

Madihally, Sundararajan V.

2011-01-01

Most chemical engineering programs that offer M.S. and Ph.D. degrees have a common seminar series for all the graduate students. Many would agree that seminars lack student interest, leading to ineffectiveness. We questioned the possibility of adding value to the seminar series by incorporating non-technical topics that may be more important to…

Non-resonant triple alpha reaction rate at low temperature

Energy Technology Data Exchange (ETDEWEB)

Itoh, T.; Tamii, A.; Aoi, N.; Fujita, H.; Hashimoto, T.; Miki, K.; Ogata, K. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Carter, J.; Donaldson, L.; Sideras-Haddad, E. [Schools of Physics, University of Witwatersrand, Johannesburg 2050 (South Africa); Furuno, T.; Kawabata, T. [Departments of Physics, Kyoto University, Sakyo, Kyoto, 606-8502 (Japan); Kamimura, M. [RIKEN Nishina Center, Wako, Saitama, 351-0198 (Japan); Nemulodi, F.; Neveling, R.; Smit, F. D.; Swarts, C. [iThemba Laboratory for Accelerator Based Sciences Somerset, West, 7129 (South Africa)

2014-05-02

Our experimental goal is to study the non-resonant triple alpha reaction rate at low temperture (T < 10{sup 8} K). The {sup 13}C(p,d) reaction at 66 MeV has been used to probe the alpha-unbound continuum state in {sup 12}C just below the 2{sup nd} 0{sup +} state at 7.65 MeV. The transition strength to the continuum state is predicted to be sensitive to the non-resonant triple alpha reaction rate. The experiment has been performed at iThemba LABS. We report the present status of the experiment.

Non-perturbative running of quark masses in three-flavour QCD

CERN Document Server

Campos, Isabel; Pena, Carlos; Preti, David; Ramos, Alberto; Vladikas, Anastassios

2016-01-01

We present our preliminary results for the computation of the non-perturbative running of renormalized quark masses in $N_f = 3$ QCD, between the electroweak and hadronic scales, using standard finite-size scaling techniques. The computation is carried out to very high precision, using massless $\\mathcal{O}(a)$-improved Wilson quarks. Following the strategy adopted by the ALPHA Collaboration for the running coupling, different schemes are used above and below a scale $\\mu_0 \\sim m_b$, which differ by using either the Schr\\"odinger Functional or Gradient Flow renormalized coupling. We discuss our results for the running in both regions, and the procedure to match the two schemes.

Quasilocal quark models as effective theory of non-perturbative QCD

International Nuclear Information System (INIS)

Andrianov, A.A.

2006-01-01

We consider the Quasilocal Quark Model of NJL type (QNJLM) as effective theory of non-perturbative QCD including scalar (S), pseudo-scalar (P), vector (V) and axial-vector (A) four-fermion interaction with derivatives. In the presence of a strong attraction in the scalar channel the chiral symmetry is spontaneously broken and as a consequence the composite meson states are generated in all channels. With the help of Operator Product Expansion the appropriate set of Chiral Symmetry Restoration (CSR) Sum Rules in these channels are imposed as matching rules to QCD at intermediate energies. The mass spectrum and some decay constants for ground and excited meson states are calculated

Orbital classical solutions, non-perturbative phenomena and singularity at the zero coupling constant point

International Nuclear Information System (INIS)

Vourdas, A.

1982-01-01

We try to extend previous arguments on orbital classical solutions in non-relativistic quantum mechanics to the 1/4lambda vertical stroke phi vertical stroke 4 complex relativistic field theory. The single valuedness of the Green function in the semiclassical (Planksche Konstante → 0) limit leads to a Bohr-Sommerfeld quantization. A path integral formalism for the Green functions analogous to that in non-relativistic quantum mechanics is employed and a semiclassical approach which uses our classical solutions indicates non-perturbative effects. They reflect an esub(1/lambda) singularity at the zero coupling constant point. (orig.)

Statistical nature of non-Gaussianity from cubic order primordial perturbations: CMB map simulations and genus statistic

International Nuclear Information System (INIS)

Chingangbam, Pravabati; Park, Changbom

2009-01-01

We simulate CMB maps including non-Gaussianity arising from cubic order perturbations of the primordial gravitational potential, characterized by the non-linearity parameter g NL . The maps are used to study the characteristic nature of the resulting non-Gaussian temperature fluctuations. We measure the genus and investigate how it deviates from Gaussian shape as a function of g NL and smoothing scale. We find that the deviation of the non-Gaussian genus curve from the Gaussian one has an antisymmetric, sine function like shape, implying more hot and more cold spots for g NL > 0 and less of both for g NL NL and also exhibits mild increase as the smoothing scale increases. We further study other statistics derived from the genus, namely, the number of hot spots, the number of cold spots, combined number of hot and cold spots and the slope of the genus curve at mean temperature fluctuation. We find that these observables carry signatures of g NL that are clearly distinct from the quadratic order perturbations, encoded in the parameter f NL . Hence they can be very useful tools for distinguishing not only between non-Gaussian temperature fluctuations and Gaussian ones but also between g NL and f NL type non-Gaussianities

Endothelial perturbation: a link between non-dipping and retinopathy in type 2 diabetes?

DEFF Research Database (Denmark)

Knudsen, Søren Tang; Jeppesen, Peter; Frederiksen, Christian Alcaraz

2007-01-01

-six subjects, stratified to 4 gender-, age-, and duration-matched groups of 19 subjects each, were studied (group A: non-diabetic subjects; group B to D, type 2 diabetic subjects; group B: no retinopathy; group C: minimal background retinopathy; group D: diabetic maculopathy). All subjects underwent a 24-hour......Reduced diurnal blood pressure (BP) variation ("non-dipping") is associated with both micro- and macrovascular complications in patients with type 2 diabetes. The relation between endothelial perturbation and diurnal BP variation in diabetic subjects has not previously been studied. Seventy...... to endothelial cell activation as well as with retinopathy in subjects with type 2 diabetes. This finding suggests a possible mechanism linking non-dipping with microvascular complications in these subjects....

Transmutation of a trans-series: the Gross-Witten-Wadia phase transition

Science.gov (United States)

Ahmed, Anees; Dunne, Gerald V.

2017-11-01

We study the change in the resurgent asymptotic properties of a trans-series in two parameters, a coupling g 2 and a gauge index N, as a system passes through a large N phase transition, using the universal example of the Gross-Witten-Wadia third-order phase transition in the unitary matrix model. This transition is well-studied in the immediate vicinity of the transition point, where it is characterized by a double-scaling limit Painlevé II equation, and also away from the transition point using the pre-string difference equation. Here we present a complementary analysis of the transition at all coupling and all finite N, in terms of a differential equation, using the explicit Tracy-Widom mapping of the Gross-Witten-Wadia partition function to a solution of a Painlevé III equation. This mapping provides a simple method to generate trans-series expansions in all parameter regimes, and to study their transmutation as the parameters are varied. For example, at any finite N the weak coupling expansion is divergent, with a non-perturbative trans-series completion; on the other hand, the strong coupling expansion is convergent, and yet there is still a non-perturbative trans-series completion. We show how the different instanton terms `condense' at the transition point to match with the double-scaling limit trans-series. We also define a uniform large N strong-coupling expansion (a non-linear analogue of uniform WKB), which is much more precise than the conventional large N expansion through the transition region, and apply it to the evaluation of Wilson loops.

Thermoelastic analysis of non-uniform pressurized functionally graded cylinder with variable thickness using first order shear deformation theory(FSDT) and perturbation method

Science.gov (United States)

Khoshgoftar, M. J.; Mirzaali, M. J.; Rahimi, G. H.

2015-11-01

Recently application of functionally graded materials(FGMs) have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs. Such composites with varying thickness and non-uniform pressure can be used in the aerospace engineering. Therefore, analysis of such composite is of high importance in engineering problems. Thermoelastic analysis of functionally graded cylinder with variable thickness under non-uniform pressure is considered. First order shear deformation theory and total potential energy approach is applied to obtain the governing equations of non-homogeneous cylinder. Considering the inner and outer solutions, perturbation series are applied to solve the governing equations. Outer solution for out of boundaries and more sensitive variable in inner solution at the boundaries are considered. Combining of inner and outer solution for near and far points from boundaries leads to high accurate displacement field distribution. The main aim of this paper is to show the capability of matched asymptotic solution for different non-homogeneous cylinders with different shapes and different non-uniform pressures. The results can be used to design the optimum thickness of the cylinder and also some properties such as high temperature residence by applying non-homogeneous material.

The role of radial particle pinches in ELM suppression by resonant magnetic perturbations

International Nuclear Information System (INIS)

Stacey, W.M.; Evans, T.E.

2011-01-01

The force balance in the plasma edge in a matched pair of DIII-D (Luxon 2002 Nucl. Fusion 42 6149) tokamak discharges with and without resonant magnetic perturbations (RMPs) is evaluated in order to investigate the effects on particle transport of RMP applied for the purpose of suppressing edge-localized modes (ELMs). Experimental data are used to evaluate the radial and toroidal force balances, which may be written as a pinch-diffusion relation for the radial ion flux to facilitate investigation of transport effects. The radial electric field in the H-mode plasma had a sharp negative dip in the steep gradient region of the edge pedestal, associated with which was a large inward pinch velocity. The main effect of RMP was to make the edge electric field less negative or more positive, reducing this strong negative dip in the radial electric field (even reversing it from negative to positive over some regions), thereby reducing the strong inward particle pinch in the edge of an H-mode discharge, thus causing a reduction in edge density below the ELM threshold.

Stochastic resonance and vibrational resonance in an excitable system: The golden mean barrier

International Nuclear Information System (INIS)

Stan, Cristina; Cristescu, C.P.; Alexandroaei, D.; Agop, M.

2009-01-01

We report on stochastic resonance and vibrational resonance in an electric charge double layer configuration as usually found in electrical discharges, biological cell membranes, chemical systems and nanostructures. The experiment and numerical computation show the existence of a barrier expressible in terms of the golden mean above which the two phenomena do not take place. We consider this as new evidence for the importance of the golden mean criticality in the oscillatory dynamics, in agreement with El Naschie's E-infinity theory. In our experiment, the dynamics of a charge double layer generated in the inter-anode space of a twin electrical discharge is investigated under noise-harmonic and harmonic-harmonic perturbations. In the first case, a Gaussian noise can enhance the response of the system to a weak injected periodic signal, a clear mark of stochastic resonance. In the second case, similar enhancement can appear if the noise is replaced by a harmonic perturbation with a frequency much higher than the frequency of the weak oscillation. The amplitude of the low frequency oscillation shows a maximum versus the amplitude of the high frequency perturbation demonstrating vibrational resonance. In order to model these dynamics, we derived an excitable system by modifying a biased van der Pol oscillator. The computational study considers the behaviour of this system under the same types of perturbation as in the experimental investigations and is found to give consistent results in both situations.

On p-adic aspects of some perturbation series

International Nuclear Information System (INIS)

Dragovic, B.G.

1993-01-01

Series with factorial terms, which are of potential interest in quantum field theory and string theory, are considered. Divergent series in the real case are usually p-adic convergent. Using simple and number field invariant methods of summation, rational sums are obtained. Sums of the convergent and divergent counterparts of the same series are connected by adelic summability. 9 refs

Interaction between doubly-excited 4p4nln'l' resonances in KrI

International Nuclear Information System (INIS)

Sukhorukov, V L; Petrov, I D; Demekhin, Ph V; Schmoranzer, H; Mickat, S; Kammer, S; Schartner, K-H; Klumpp, S; Werner, L; Ehresmann, A

2007-01-01

Photoionization cross sections for the 4p 4 ( 3 P)5s 4 P 5/2,3/2,1/2 satellites and 4s → εl, 4p → εl main lines of Kr II were measured using the photon-induced fluorescence spectroscopy in the exciting-photon energy range between 27.80 eV and 29.44 eV with extremely narrow bandwidth (1.7 meV at 28.55 eV) of the monochromatized synchrotron radiation. The observed resonances were assigned to the 4p 4 5s( 4 P 1/2 )np and 4p 4 5s( 2 P 3/2 )np Rydberg series on the basis of the calculations including core relaxation and interaction between many resonances and many continua. The calculation shows that the resonance structure in the photoionization channels exists due to the 4p 4 ( 1 D)5s 2 D 5/2 6p 3/2 and 4p 4 ( 1 D)5s 2 D 3/2 6p 3/2,1/2 promoter states which strongly perturb the above Rydberg series

Non-Vacuum Initial States for Cosmological Perturbations of Quantum-Mechanical Origin

CERN Document Server

Martín, J; Sakellariadou, M; Martin, Jerome; Riazuelo, Alain; Sakellariadou, Mairi

2000-01-01

In the context of inflation, non-vacuum initial states for cosmological perturbations that possess a built in scale are studied. It is demonstrated that this assumption leads to a falsifiable class of models. The question of whether they lead to conflicts with the available observations is addressed. For this purpose, the power spectrum of the Bardeen potential operator is calculated and compared with the CMBR anisotropies measurements and the redshift surveys of galaxies and clusters of galaxies. Generic predictions of the model are: a high first acoustic peak, the presence of a bump in the matter power spectrum and non-Gaussian statistics. The details are controlled by the number of quanta in the non-vacuum initial state. Comparisons with observations show that there exists a window for the free parameters such that good agreement between the data and the theoretical predictions is possible. However, in the case where the initial state is a state with a fixed number of quanta, it is shown that this number c...

Loschmidt echo for local perturbations: non-monotonic cross-over from the Fermi-golden-rule to the escape-rate regime

International Nuclear Information System (INIS)

Goussev, Arseni; Waltner, Daniel; Richter, Klaus; Jalabert, Rodolfo A

2008-01-01

We address the sensitivity of quantum mechanical time evolution by considering the time decay of the Loschmidt echo (LE) (or fidelity) for local perturbations of the Hamiltonian. Within a semiclassical approach, we derive analytical expressions for the LE decay for chaotic systems for the whole range from weak to strong local perturbations and identify different decay regimes which complement those known for the case of global perturbations. For weak perturbations, a Fermi-golden-rule (FGR)-type behavior is recovered. For strong perturbations, the escape-rate regime is reached, where the LE decays exponentially with a rate independent of the perturbation strength. The transition between the FGR regime and the escape-rate regime is non-monotonic, i.e. the rate of the exponential time-decay of the LE oscillates as a function of the perturbation strength. We further perform extensive quantum mechanical calculations of the LE based on numerical wave packet evolution, which strongly support our semiclassical theory. Finally, we discuss in some detail possible experimental realizations for observing the predicted behavior of the LE

Perturbation theory with non-diagonal propagators and its use in the intermediate-coupling regime

International Nuclear Information System (INIS)

Znojil, M.

1998-01-01

An innovated method of construction of the Rayleigh-Schroedinger perturbation series in a seemingly nonperturbative regime is offered. Designed for the needs of condensed matter physics, nuclear physics and quantum chemistry, the flexibility of our new formalism is based on a nonstandard Lanczosean construction of unperturbed basis. With an asymmetric choice of the model space the recipe becomes recurrent not only order-by- order in a small parameter (as usual) but also projection-by-projection in the Hilbert space. Its idea and efficiency are illustrated on a few schematic examples. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

Investigations on perturbations of microwave dielectric resonator thermometer

International Nuclear Information System (INIS)

Yu, Lili; Zhang, Guangming; Fernicola, V; Lu, Jinchuan

2017-01-01

Investigations of antenna probe length, antenna-dielectric distance, cavity filling and humidity on microwave resonator thermometer with respect to Q , spurious mode depression, coupling strength, accuracy, shock resistance or sensitivity were carried out in order to improve the dielectric resonator thermometer performance. Significant improvement of Q and depression of spurious mode coupling were obtained when the antenna length was reduced. It also turns out that the Q and spurious mode coupling strength vary with the distance between dielectric and antenna pin, as well under appropriate antenna length. Filling the cavity with nitrogen increases coupling strength but decrease frequency-temperature sensitivity compared to a vacuum-pumped cavity. Besides, preliminary results on the microwave resonator sensitivity to air humidity were obtained. (technical note)

Finite field-dependent symmetries in perturbative quantum gravity

International Nuclear Information System (INIS)

Upadhyay, Sudhaker

2014-01-01

In this paper we discuss the absolutely anticommuting nilpotent symmetries for perturbative quantum gravity in general curved spacetime in linear and non-linear gauges. Further, we analyze the finite field-dependent BRST (FFBRST) transformation for perturbative quantum gravity in general curved spacetime. The FFBRST transformation changes the gauge-fixing and ghost parts of the perturbative quantum gravity within functional integration. However, the operation of such symmetry transformation on the generating functional of perturbative quantum gravity does not affect the theory on physical ground. The FFBRST transformation with appropriate choices of finite BRST parameter connects non-linear Curci–Ferrari and Landau gauges of perturbative quantum gravity. The validity of the results is also established at quantum level using Batalin–Vilkovisky (BV) formulation. -- Highlights: •The perturbative quantum gravity is treated as gauge theory. •BRST and anti-BRST transformations are developed in linear and non-linear gauges. •BRST transformation is generalized by making it finite and field dependent. •Connection between linear and non-linear gauges is established. •Using BV formulation the results are established at quantum level also

Tests of perturbative and non perturbative structure of moments of hadronic event shapes using experiments JADE and OPAL

International Nuclear Information System (INIS)

Pahl, Christoph Johannes

2008-01-01

In hadron production data of the e + e - annihilation experiments JADE and OPAL we measure the first five moments of twelve hadronic-event-shape variables at c.m. energies from 14 to 207 GeV. From the comparison of the QCD NLO prediction with the data corrected by means of MC models about hadronization we obtain the reference value of the strong coupling α s (M Z 0 )=0.1254±0.0007(stat.)±0.0010(exp.) +0.0009 -0.0 0 23 (had.) +0.0069 -0.0053 (theo.). For some, especially higher moments, systematic unsufficiencies in the QCD NLO prediction are recognizable. Simultaneous fits to two moments under assumption of identical renormalization scales yield scale values from x μ =0.057 to x μ =0.196. We check predictions of different non-perturbative models. From the single-dressed-gluon approximation a perturbative prediction in O(α 5 s ) results with neglegible energy power correction, which describes the thrust average on hadron level well with α s (M Z 0 )=0.1186±0,0017(exp.) -0.0028 +0.0033 (theo.). The variance of the event-shape variable is measured and compared with models as well as predictions. [de

G-fluxes and non-perturbative stabilisation of heterotic M-theory

International Nuclear Information System (INIS)

Curio, Gottfried; Krause, Axel

2002-01-01

We examine heterotic M-theory compactified on a Calabi-Yau manifold with an additional parallel M5-brane. The dominant non-perturbative effect stems from open membrane instantons connecting the M5 with the boundaries. We derive the four-dimensional low-energy supergravity potential for this situation including subleading contributions as it turns out that the leading term vanishes after minimisation. At the minimum of the potential the M5 gets stabilised at the middle of the orbifold interval while the vacuum energy is shown to be manifestly positive. Moreover, induced by the non-trivial running of the Calabi-Yau volume along the orbifold which is driven by the G-fluxes, we find that the orbifold-length and the Calabi-Yau volume modulus are stabilised at values which are related by the G-flux of the visible boundary. Finally we determine the supersymmetry-breaking scale and the gravitino mass for this open membrane vacuum

One dimensional systems with singular perturbations

International Nuclear Information System (INIS)

Alvarez, J J; Gadella, M; Nieto, L M; Glasser, L M; Lara, L P

2011-01-01

This paper discusses some one dimensional quantum models with singular perturbations. Eventually, a mass discontinuity is added at the points that support the singular perturbations. The simplest model includes an attractive singular potential with a mass jump both located at the origin. We study the form of the only bound state. Another model exhibits a hard core at the origin plus one or more repulsive deltas with mass jumps at the points supporting these deltas. We study the location and the multiplicity of these resonances for the case of one or two deltas and settle the basis for a generalization. Finally, we consider the harmonic oscillator and the infinite square well plus a singular potential at the origin. We see how the energy of bound states is affected by the singular perturbation.

Analytic continuation in perturbative QCD

International Nuclear Information System (INIS)

Caprini, Irinel

2002-01-01

We discuss some attempts to improve standard perturbative expansion in QCD by using the analytic continuation in the momentum and the Borel complex planes. We first analyse the momentum-plane analyticity properties of the Borel-summed Green functions in perturbative QCD and the connection between the Landau singularities and the infrared renormalons. By using the analytic continuation in the Borel complex plane, we propose a new perturbative series replacing the standard expansion in powers of the normalized coupling constant a. The new expansion functions have branch point and essential singularities at the origin of the complex a-plane and divergent Taylor expansions in powers of a. On the other hand the modified expansion of the QCD correlators is convergent under rather conservative conditions. (author)

Analysis of a Non-resonant Ultrasonic Levitation Device

Science.gov (United States)

Andrade, Marco A. B.; Pérez, Nicolás; Adamowski, Julio C.

In this study, a non-resonant configuration of ultrasonic levitation device is presented, which is formed by a small diameter ultrasonic transducer and a concave reflector. The influence of different levitator parameters on the levitation performance is investigated by using a numerical model that combines the Gor'kov theory with a matrix method based on the Rayleigh integral. In contrast with traditional acoustic levitators, the non-resonant ultrasonic levitation device allows the separation distance between the transducer and the reflector to be adjusted continually, without requiring the separation distance to be set to a multiple of half-wavelength. It is also demonstrated, both numerically and experimentally, that the levitating particle can be manipulated by maintaining the transducer in a fixed position in space and moving the reflector in respect to the transducer.

Detection of leak-defective fuel rods using the circumferential Lamb waves excited by the resonance backscattering of ultrasonic pulses

International Nuclear Information System (INIS)

Choi, M.S.; Yang, M.S.; Kim, H.C.

1992-01-01

A new ultrasonic technique for detecting the infiltrated water in leaked fuel rods is developed. Propagation characteristics of the circumferential Lamb waves in the cladding tubes are estimated by the resonance scattering theory. The Lamb waves are excited by the resonance backscattering of ultrasonic pulses. In sound fuel rods, the existence of the Lamb waves is revealed by a series of periodic echoes. In leaked fuel rods, however, the Lamb waves are perturbed strongly by the scattered waves from the surface of fuel pellets, thus the periodic echoes are not observed. (author)

A Non-standard Empirical Likelihood for Time Series

DEFF Research Database (Denmark)

Nordman, Daniel J.; Bunzel, Helle; Lahiri, Soumendra N.

Standard blockwise empirical likelihood (BEL) for stationary, weakly dependent time series requires specifying a fixed block length as a tuning parameter for setting confidence regions. This aspect can be difficult and impacts coverage accuracy. As an alternative, this paper proposes a new version...... of BEL based on a simple, though non-standard, data-blocking rule which uses a data block of every possible length. Consequently, the method involves no block selection and is also anticipated to exhibit better coverage performance. Its non-standard blocking scheme, however, induces non......-standard asymptotics and requires a significantly different development compared to standard BEL. We establish the large-sample distribution of log-ratio statistics from the new BEL method for calibrating confidence regions for mean or smooth function parameters of time series. This limit law is not the usual chi...

Discrete state perturbation theory via Green's functions

International Nuclear Information System (INIS)

Rubinson, W.

1975-01-01

The exposition of stationary-state perturbation theory via the Green's function method in Goldberger and Watson's Collision Theory is reworked in a way that makes explicit its mathematical basis. It is stressed that the theory consists of the construction of, and manipulations on, a mathematical identity. The perturbation series fall out of the identity almost immediately. The logical status of the method is commented on

Non-resonant energy harvesting via an adaptive bistable potential

International Nuclear Information System (INIS)

Hosseinloo, Ashkan Haji; Turitsyn, Konstantin

2016-01-01

Narrow bandwidth and easy detuning, inefficiency in broadband and non-stationary excitations, and difficulties in matching a linear harvester’s resonance frequency to low-frequency excitations at small scales, have convinced researchers to investigate nonlinear, and in particular bistable, energy harvesters in recent years. However, bistable harvesters suffer from co-existing low and high energy orbits, and sensitivity to initial conditions, and have recently been proven inefficient when subjected to many real-world random and non-stationary excitations. Here, we propose a novel non-resonant buy-low-sell-high strategy that can significantly improve the harvester’s effectiveness at low frequencies in a much more robust fashion. This strategy could be realized by a passive adaptive bistable system. Simulation results confirm the high effectiveness of the adaptive bistable system following a buy-low-sell-high logic when subjected to harmonic and random non-stationary walking excitations compared to its conventional bistable and linear counterparts. (paper)

Hadron scattering, resonances, and QCD

Science.gov (United States)

Briceño, R. A.

2016-11-01

The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

Self-organising mixture autoregressive model for non-stationary time series modelling.

Science.gov (United States)

Ni, He; Yin, Hujun

2008-12-01

Modelling non-stationary time series has been a difficult task for both parametric and nonparametric methods. One promising solution is to combine the flexibility of nonparametric models with the simplicity of parametric models. In this paper, the self-organising mixture autoregressive (SOMAR) network is adopted as a such mixture model. It breaks time series into underlying segments and at the same time fits local linear regressive models to the clusters of segments. In such a way, a global non-stationary time series is represented by a dynamic set of local linear regressive models. Neural gas is used for a more flexible structure of the mixture model. Furthermore, a new similarity measure has been introduced in the self-organising network to better quantify the similarity of time series segments. The network can be used naturally in modelling and forecasting non-stationary time series. Experiments on artificial, benchmark time series (e.g. Mackey-Glass) and real-world data (e.g. numbers of sunspots and Forex rates) are presented and the results show that the proposed SOMAR network is effective and superior to other similar approaches.

Geometric Hamiltonian structures and perturbation theory

International Nuclear Information System (INIS)

Omohundro, S.

1984-08-01

We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging

Non-perturbative string theories and singular surfaces

International Nuclear Information System (INIS)

Bochicchio, M.

1990-01-01

Singular surfaces are shown to be dense in the Teichmueller space of all Riemann surfaces and in the grasmannian. This happens because a regular surface of genus h, obtained identifying 2h disks in pairs, can be approximated by a very large genus singular surface with punctures dense in the 2h disks. A scale ε is introduced and the approximate genus is defined as half the number of connected regions covered by punctures of radius ε. The non-perturbative partition function is proposed to be a scaling limit of the partition function on such infinite genus singular surfaces with a weight which is the coupling constant g raised to the approximate genus. For a gaussian model in any space-time dimension the regularized partition function on singular surfaces of infinite genus is the partition function of a two-dimensional lattice gas of charges and monopoles. It is shown that modular invariance of the partition function implies a version of the Dirac quantization condition for the values of the e/m charges. Before the scaling limit the phases of the lattice gas may be classified according to the 't Hooft criteria for the condensation of e/m operators. (orig.)

Strings as perturbations of evolving spin networks

International Nuclear Information System (INIS)

Smolin, Lee

2000-01-01

One step in the construction of a background independent formulation of string theory is detailed, in which it is shown how perturbative strings may arise as small fluctuations around histories in a formulation of non-perturbative dynamics of spin networks due to Markopoulou. In this formulation the dynamics of spin network states and their generalizations is described in terms of histories which have discrete analogues of the causal structure and many fingered time of Lorentzian spacetimes. Perturbations of these histories turn out to be described in terms of spin systems defined on 2-dimensional timelike surfaces embedded in the discrete spacetime. When the history has a classical limit which is Minkowski spacetime, the action of the perturbation theory is given to leading order by the spacetime area of the surface, as in bosonic string theory. This map between a non-perturbative formulation of quantum gravity and a 1+1 dimensional theory generalizes to a large class of theories in which the group SU(2) i s extended to any quantum group or supergroup. It is argued that a necessary condition for the non-perturbative theory to have a good classical limit is that the resulting 1+1 dimensional theory defines a consistent and stable perturbative string theory

Stark resonances: asymptotics and distributional Borel sum

International Nuclear Information System (INIS)

Caliceti, E.; Grecchi, V.; Maioli, M.

1993-01-01

We prove that the Stark effect perturbation theory of a class of bound states uniquely determines the position and the width of the resonances by Distributional Borel Sum. In particular the small field asymptotics of the width is uniquely related to the large order asymptotics of the perturbation coefficients. Similar results apply to all the ''resonances'' of the anharmonic and double well oscillators. (orig.)

Non-stationarity of resonance signals from magnetospheric and ionospheric plasmas

International Nuclear Information System (INIS)

Higel, Bernard

1975-01-01

Rocket observations of resonance signals from ionospheric plasma were made during EIDI relaxation sounding experiments. It appeared that their amplitude, phase, and frequency characteristics are not stationary as a function of the receipt time. The measurement of these nonstationary signals increases the interest presented by resonance phenomena in spatial plasma diagnostics, but this measurement is not easy for frequency non-stationarities. A new method, entirely numerical, is proposed for automatic recognition of these signals. It will be used for the selecting and real-time processing of signals of the same type to be observed during relaxation sounding experiments on board of the futur GEOS satellite. In this method a statistical discrimination is done on the values taken by several parameters associated with the non-stationarities of the observed resonance signals [fr

Non-perturbative treatment of excitation and ionization in U92++U91+ collisions at 1 GeV/amu

International Nuclear Information System (INIS)

Becker, U.; Gruen, N.; Scheid, W.; Soff, G.

1986-01-01

Inner shell excitation and ionization processes in relativistic collisions of very heavy ions are treated by a non-perturbative method for the first time. The time-dependent Dirac equation is solved by a finite difference method for the scattering of U 92+ on U 91+ at Esub(lab) = 1 GeV/amu and zero impact parameter. The K-shell ionization probabilities are compared with those resulting from first-order perturbation theory. (orig.)

Modeling Non-Gaussian Time Series with Nonparametric Bayesian Model.

Science.gov (United States)

Xu, Zhiguang; MacEachern, Steven; Xu, Xinyi

2015-02-01

We present a class of Bayesian copula models whose major components are the marginal (limiting) distribution of a stationary time series and the internal dynamics of the series. We argue that these are the two features with which an analyst is typically most familiar, and hence that these are natural components with which to work. For the marginal distribution, we use a nonparametric Bayesian prior distribution along with a cdf-inverse cdf transformation to obtain large support. For the internal dynamics, we rely on the traditionally successful techniques of normal-theory time series. Coupling the two components gives us a family of (Gaussian) copula transformed autoregressive models. The models provide coherent adjustments of time scales and are compatible with many extensions, including changes in volatility of the series. We describe basic properties of the models, show their ability to recover non-Gaussian marginal distributions, and use a GARCH modification of the basic model to analyze stock index return series. The models are found to provide better fit and improved short-range and long-range predictions than Gaussian competitors. The models are extensible to a large variety of fields, including continuous time models, spatial models, models for multiple series, models driven by external covariate streams, and non-stationary models.

Jahn-Teller effect in Rydberg series: A multi-state vibronic coupling problem

International Nuclear Information System (INIS)

Staib, A.; Domcke, W.; Sobolewski, A.L.

1990-01-01

Two simple limiting cases of Jahn-Teller (JT) coupling in Rydberg states of polyatomic molecules are considered, namely (i) JT coupling in Rydberg orbitals as well as in the ionization continuum (nondegenerate ion core, degenerate Rydberg series) and (ii) JT coupling in the ion core (degenerate ion core, nondegenerate Rydberg series). For both models simple and efficient algorithms for the computation of spectra (dynamical JT effect) are developed. The orbital JT effect is shown to represent a novel type of multi-state vibronic coupling, giving rise to interesting spectroscopic phenomena, among them resonant inter-Rydberg perturbations and JT induced autoionization. Particular attention is paid to the demonstration of the characteristic spectroscopic signatures of the two types of JT coupling in Rydberg states. (orig.)

A multiphase series-resonant converter with a new topology and a reduced number of thyristors

NARCIS (Netherlands)

Huisman, H.

1995-01-01

Multiphase series resonant (SR) power converters provide a flexible way to transform power between a utility grid and a multiphase load or source. The current implementations all suffer from a high component count, which makes the use of these power converters unattractive from an economical point

Non-perturbative renormalization of the chromo-magnetic operator in heavy quark effective theory and the B{sup *} - B mass splitting

Energy Technology Data Exchange (ETDEWEB)

Guazzini, D.; Sommer, R. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Meyer, H. [Massachusetts Institute of Technology, Cambridge, MA (United States). Center for Theoretical Physics

2007-05-15

We carry out the non-perturbative renormalization of the chromo-magnetic operator in Heavy Quark Effective Theory. At order 1/m of the expansion, the operator is responsible for the mass splitting between the pseudoscalar and vector B mesons. We obtain its two-loop anomalous dimension in a Schroedinger functional scheme by successive oneloop conversions to the lattice MS scheme and the MS scheme. We then compute the scale evolution of the operator non-perturbatively in the N{sub f}=0 theory between {mu} {approx}0.3 GeV and {mu} {approx}100 GeV, where contact is made with perturbation theory. The overall renormalization factor that converts the bare lattice operator to its renormalization group invariant form is given for the Wilson gauge action and two standard discretizations of the heavy-quark action. As an application, we find that this factor brings the previous quenched predictions of the B{sup *}-B mass splitting closer to the experimental value than found with a perturbative renormalization. The same renormalization factor is applicable to the spin-dependent potentials of Eichten and Feinberg. (orig.)

Distribution functions for orbits trapped at the resonances in the Galactic disc

Science.gov (United States)

Monari, G.

2017-12-01

The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment however leads to singularities at resonances, which prevent quantitative comparisons with data. Monari et al. manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. They then follow the prescription of Binney (2016), assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits only depends on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of distribution functions in action space.

Schroedinger operators with singular perturbation potentials

International Nuclear Information System (INIS)

Harrell, E.M. II.

1976-01-01

This is a perturbative analysis of the eigenvalues and eigenfunctions of Schroedinger operators of the form -Δ + A + lambda V, defined on the Hilbert space L 2 (R/sup n/). A is a potential function (a smooth, real multiplication operator), and V is a ''spikelike'' perturbation, i.e., a perturbative potential function which diverges at some finite point. Lambda is a small real or complex parameter. The emphasis is on one-dimensional problems, and in particular the typical example is the ''spiked harmonic oscillator'' Hamiltonian, -d 2 /dx 2 + x 2 + lambda x/sup -α/, where α is a positive constant. An earlier study by L. Detwiler and J. R. Klauder [Phys. Rev. D 11 (1975) 1436] indicated that the lowest-order corrections to the ground-state eigenvalue of the spiked harmonic oscillator with lambda greater than 0 were proportional to lambda ln lambda when α = 3, and to lambda/sup 1/(α-2) when α is greater than 3. These and analogous results for a large class of operators and arbitrary eigenvalues are proved. Explicit constants in a modified perturbation series with a complicated dependence on lambda are determined and exhibited. Higher-order corrections for real lambda and lowest-order corrections for complex lambda are also discussed. While the substance of the dissertation is mathematical, its main applications are to quantum physics. The immediate cause of interest in such problems was the use of their peculiar convergence properties by J. R. Klauder as models for the behavior of nonrenormalizable quantum field theories. However, the results of this study are likely to be of greater importance in chemical or nuclear physics, as positive spikelike perturbations represent repulsive core interactions for quantum mechanical particles. The modified perturbation series are a new calculation technique for this situation

Anomalous resonance of the symmetric single-impurity Anderson model in the presence of pairing fluctuations

International Nuclear Information System (INIS)

Guang-Ming Zhang; Lu Yu

1998-10-01

We consider the symmetric single-impurity Anderson model in the presence of pairing fluctuations. In the isotropic limit, the degrees of freedom of the local impurity are separated into hybridizing and non-hybridizing modes. The self-energy for the hybridizing modes can be obtained exactly, leading to two subbands centered at ±U/2. For the non-hybridizing modes, the second order perturbation yields a singular resonance of the marginal Fermi liquid form. By multiplicative renormalization, the self-energy is derived exactly, showing the resonance is pinned at the Fermi level, while its strength is weakened by renormalization. (author)

Selberg zeta functions and transfer operators an experimental approach to singular perturbations

CERN Document Server

Fraczek, Markus Szymon

2017-01-01

This book presents a method for evaluating Selberg zeta functions via transfer operators for the full modular group and its congruence subgroups with characters. Studying zeros of Selberg zeta functions for character deformations allows us to access the discrete spectra and resonances of hyperbolic Laplacians under both singular and non-singular perturbations. Areas in which the theory has not yet been sufficiently developed, such as the spectral theory of transfer operators or the singular perturbation theory of hyperbolic Laplacians, will profit from the numerical experiments discussed in this book. Detailed descriptions of numerical approaches to the spectra and eigenfunctions of transfer operators and to computations of Selberg zeta functions will be of value to researchers active in analysis, while those researchers focusing more on numerical aspects will benefit from discussions of the analytic theory, in particular those concerning the transfer operator method and the spectral theory of hyperbolic spac...

THE RESONANT OVERVOLTAGE IN NON-SINUSOIDAL MODE OF MAIN ELECTRIC NETWORK

Directory of Open Access Journals (Sweden)

V. G. Kuznetsov

2018-04-01

Full Text Available Purpose. The resonant overvoltage arises in main electrical networks as a result of random coincidence of some parameters of circuit and its mode and it may exist for a relatively long time. Therefore, the traditional means of limitation of short duration commutation surges are not effective in this case. The study determines conditions of appearance and development of non-sinusoidal mode after switching idle autotransformer to the overhead line of extra high voltage. The purpose of the paper is to choice measures for prevention overvoltage, too. Methodology. The study has used the result of extra high voltage line testing, the methods of electric circuit theory and the simulation in the MATLAB & Simulink package. Results. The simulation model of the extra high voltage transmission line for the study of resonant non-sinusoidal overvoltage is developed. The conditions for the appearance of resonant circuits in the real power line are found and harmonic frequency in which overvoltage arises are obtained. The study proposes using the controlled switching device as a measure to prevent resonance surges and determines the appropriate settings. Originality. The expression for calculation of resonant length of extra high voltage line was derived. The special investigation of processes in the resonant circuit of the extra high voltage transmission line for higher harmonic components of voltage is carried out. The program of switching for control apparatus that prevents non-sinusoidal overvoltage has been developed at the first time. Practical value. The using of the proposed settings of controlled switchgear will prevent the occurrence of hazardous resonant surge on higher harmonic components of voltage.

{alpha}{sub s} from the non-perturbatively renormalised lattice three-gluon vertex

Energy Technology Data Exchange (ETDEWEB)

Alles, B. [Pisa Univ. (Italy). Dipt. di Fisica; Henty, D.S. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Panagopoulos, H. [Department of Natural Sciences, University of Cyprus, CY-1678 Nicosia (Cyprus); Parrinello, C. [Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX (United Kingdom); Pittori, C. [L.P.T.H.E., Universite de Paris Sud, Centre d`Orsay, 91405 Orsay (France); Richards, D.G. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom)]|[Fermilab, P.O. Box 500, Batavia, IL 60510 (United States)

1997-09-29

We compute the running QCD coupling on the lattice by evaluating two-point and three-point off-shell gluon Green`s functions in a fixed gauge and imposing non-perturbative renormalisation conditions on them. Our exploratory study is performed in the quenched approximation at {beta}=6.0 on 16{sup 4} and 24{sup 4} lattices. We show that, for momenta in the range 1.8-2.3 GeV, our coupling runs according to the two-loop asymptotic formula, allowing a precise determination of the corresponding {Lambda} parameter. The role of lattice artifacts and finite-volume effects is carefully analysed and these appear to be under control in the momentum range of interest. Our renormalisation procedure corresponds to a momentum subtraction scheme in continuum field theory, and therefore lattice perturbation theory is not needed in order to match our results to the anti M anti S scheme, thus eliminating a major source of uncertainty in the determination of {alpha} {sub anti} {sub M} {sub anti} {sub S}. Our method can be applied directly to the unquenched case. (orig.). 20 refs.

Geometry of perturbed Gaussian states and quantum estimation

International Nuclear Information System (INIS)

Genoni, Marco G; Giorda, Paolo; Paris, Matteo G A

2011-01-01

We address the non-Gaussianity (nG) of states obtained by weakly perturbing a Gaussian state and investigate the relationships with quantum estimation. For classical perturbations, i.e. perturbations to eigenvalues, we found that the nG of the perturbed state may be written as the quantum Fisher information (QFI) distance minus a term depending on the infinitesimal energy change, i.e. it provides a lower bound to statistical distinguishability. Upon moving on isoenergetic surfaces in a neighbourhood of a Gaussian state, nG thus coincides with a proper distance in the Hilbert space and exactly quantifies the statistical distinguishability of the perturbations. On the other hand, for perturbations leaving the covariance matrix unperturbed, we show that nG provides an upper bound to the QFI. Our results show that the geometry of non-Gaussian states in the neighbourhood of a Gaussian state is definitely not trivial and cannot be subsumed by a differential structure. Nevertheless, the analysis of perturbations to a Gaussian state reveals that nG may be a resource for quantum estimation. The nG of specific families of perturbed Gaussian states is analysed in some detail with the aim of finding the maximally non-Gaussian state obtainable from a given Gaussian one. (fast track communication)

Keldysh meets Lindblad: Correlated Gain and Loss in Higher Order Perturbation Theory

Science.gov (United States)

Stace, Tom; Mueller, Clemens

Motivated by correlated decay processes driving gain, loss and lasing in driven artificial quantum systems, we develop a theoretical technique using Keldysh diagrammatic perturbation theory to derive a Lindblad master equation that goes beyond the usual second order perturbation theory. We demonstrate the method on the driven dissipative Rabi model, including terms up to fourth order in the interaction between the qubit and both the resonator and environment. This results in a large class of Lindblad dissipators and associated rates which go beyond the terms that have previously been proposed to describe similar systems. All of the additional terms contribute to the system behaviour at the same order of perturbation theory. We then apply these results to analyse the phonon-assisted steady-state gain of a microwave field driving a double quantum-dot in a resonator. We show that resonator gain and loss are substantially affected by dephasing- assisted dissipative processes in the quantum-dot system. These additional processes, which go beyond recently proposed polaronic theories, are in good quantitative agreement with experimental observations.

The tension as perturbative parameter in string theory

International Nuclear Information System (INIS)

Gamboa, J.

1990-01-01

We propose an approach to string theory where the zero theory is the null string. We find an explicit form of the propagator for the null string in the momentum space. We show that considering the tension as perturbative parameter, the perturbative series is completely summable and we find the propagator of the bosonic open string with tension T. (author) [pt

Chromatic perturbation and resonance analysis for the AGS-Booster

International Nuclear Information System (INIS)

Parsa, Z.

1987-01-01

The authors investigated the nonlinear effects with the emphasis on nonlinear resonances. They present some of their findings, (e.g. the structure resonances; stop-bandwidths, etc.) for the AGS-Booster Lattice using program HARMON. Comparison with the results obtained from the algorithm ''NONLIN'' is presented

Model for screening of resonant magnetic perturbations by plasma in a realistic tokamak geometry and its impact on divertor strike points

Czech Academy of Sciences Publication Activity Database

Cahyna, Pavel; Nardon, E.

2011-01-01

Roč. 415, č. 1 (2011), S927-S931 ISSN 0022-3115. [International Conference on Plasma-Surface Interactions in Controlled Fusion Device/19th./. San Diego, 24.05.2010-28.05.2010] R&D Projects: GA MŠk 7G09042; GA MŠk LA08048 Institutional research plan: CEZ:AV0Z20430508 Keywords : tokamaks * ELM control * resonant magnetic perturbations * divertor Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.052, year: 2011 http://dx.doi.org/10.1016/j.jnucmat.2011.01.117

Series Solution for Steady Three-Dimensional Flow due to Spraying on Inclined Spinning Disk by Homotopy Perturbation Method

Directory of Open Access Journals (Sweden)

Saeed Dinarvand

2012-01-01

Full Text Available The steady three-dimensional flow of condensation or spraying on inclined spinning disk is studied analytically. The governing nonlinear equations and their associated boundary conditions are transformed into the system of nonlinear ordinary differential equations. The series solution of the problem is obtained by utilizing the homotopy perturbation method (HPM. The velocity and temperature profiles are shown and the influence of Prandtl number on the heat transfer and Nusselt number is discussed in detail. The validity of our solutions is verified by the numerical results. Unlike free surface flows on an incline, this through flow is highly affected by the spray rate and the rotation of the disk.

Level density approach to perturbation theory and inverse-energy-weighted sum-rules

International Nuclear Information System (INIS)

Halemane, T.R.

1983-01-01

The terms in the familiar Rayleigh-Schroedinger perturbation series involve eigenvalues and eigenfunctions of the unperturbed operator. A level density formalism, that does not involve computation of eigenvalues and eigenfunctions, is given here for the perturbation series. In the CLT (central limit theorem) limit the expressions take very simple linear forms. The evaluation is in terms of moments and traces of operators and operator products. 3 references

Non-resonant microwave absorption studies of superconducting ...

Indian Academy of Sciences (India)

Abstract. Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing 10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field Hc1 is ...

Self-excited nonlinear plasma series resonance oscillations in geometrically symmetric capacitively coupled radio frequency discharges

International Nuclear Information System (INIS)

Donko, Z.; Schulze, J.; Czarnetzki, U.; Luggenhoelscher, D.

2009-01-01

At low pressures, nonlinear self-excited plasma series resonance (PSR) oscillations are known to drastically enhance electron heating in geometrically asymmetric capacitively coupled radio frequency discharges by nonlinear electron resonance heating (NERH). Here we demonstrate via particle-in-cell simulations that high-frequency PSR oscillations can also be excited in geometrically symmetric discharges if the driving voltage waveform makes the discharge electrically asymmetric. This can be achieved by a dual-frequency (f+2f) excitation, when PSR oscillations and NERH are turned on and off depending on the electrical discharge asymmetry, controlled by the phase difference of the driving frequencies

Dimensional perturbation theory for the two-electron atom

International Nuclear Information System (INIS)

Goodson, D.Z.

1987-01-01

Perturbation theory in δ = 1/D, where D is the dimensionality of space, is applied to the two-electron atom. In Chapter 1 an efficient procedure for calculating the coefficients of the perturbation series for the ground-state energy is developed using recursion relations between the moments of the coordinate operators. Results through tenth order are presented. The series is divergent, but Pade summation gives results comparable in accuracy to the best configuration-interaction calculations. The singularity structure of the Pade approximants confirms the hypothesis that the energy as a function of δ has an infinite sequence of poles on the negative real axis that approaches an essential singularity at δ = O. The essential singularity causes the divergence of the perturbation series. There are also two poles at δ = 1 that slow the asymptotic convergence of the low-order terms. In Chapter 2, various techniques are demonstrated for removing the effect of these poles, and accurate results are thereby obtained, even at very low order. In Chapter 3, the large D limit of the correlation energy (CE) is investigated. In the limit D → infinity it is only 35% smaller than at D = 3. It can be made to vanish in the limit by modifying the Hartree-Fock (HF) wavefunction. In Chapter 4, perturbation theory is applied to the Hooke's-law model of the atom. Prospects for treating more-complicated systems are briefly discussed

Some phenomenological consequences of the time-ordered perturbation theory of QED on non-commutative spacetime

CERN Document Server

Liao, Y

2003-01-01

A framework was recently proposed for doing perturbation theory on non-commutative (NC) spacetime. It preserves the unitarity of the S matrix and differs from the naive, popular approach already at the lowest order in perturbation when time does not commute with space. In this work, we investigate its phenomenological implications at linear colliders, especially the TESLA at DESY, through the processes of e sup + e sup --> mu sup +mu sup - ,H sup + H sup - ,H sup 0 H sup 0. We find that some NC effects computed previously are now modified and that there are new processes which now exhibit NC effects. Indeed, the first two processes get corrected at tree level as opposed to the null result in the naive approach, while the third one coincides with the naive result only in the low energy limit. The impact of the earth's rotation is incorporated. The NC signals are generally significant when the NC scale is comparable to the collider energy. If this is not the case, the non-trivial azimuthal angle distribution an...

'Non-local' response of RTP ohmic plasmas to peripheral perturbations

International Nuclear Information System (INIS)

Galli, P.; Gorini, G.; Mantica, P.; Hogeweij, G.M.D.; Kloe, J. de; Lopes Cardozo, N.J.

1999-01-01

A 'non-local' response of the plasma core triggered by peripheral plasma perturbations other than laser ablation is found in the RTP tokamak. Oblique pellet injection (OPI) has been used to induce fast cooling of the peripheral plasma. In response, an inward cold pulse (T e drop) and a slightly delayed core T e rise are observed. A somewhat similar 'non-local' response is observed when the peripheral plasma is heated by modulated electron cyclotron heating or by fast current ramps, i.e. the core temperature drops in response to the peripheral heating. The plasma conditions for the occurrence of the 'non-local' response have been investigated. The core T e rise following OPI is associated with the formation of a large temperature gradient in the region 1 e rise is largest at low electron density and for large pellet deposition radii. Above a critical density the T e rise disappears and only the (weaker) drop in core T e is observed. Time dependent transport simulations show that the propagation of the inward cold pulse is consistent with local transport, while the core T e rise is a slower phenomenon requiring a large transient drop of χ e in the region 1 < q < 2. (author)

Many body perturbation calculations of photoionization

International Nuclear Information System (INIS)

Kelly, H.P.

1979-01-01

The application of many body perturbation theory to the calculation of atomic photoionization cross sections is reviewed. The choice of appropriate potential for the single-particle state is discussed and results are presented for several atoms including resonance structure. In addition to single photoionization, the process of double photoionization is considered and is found to be significant. (Auth.)

Perturbation theory from stochastic quantization

International Nuclear Information System (INIS)

Hueffel, H.

1984-01-01

By using a diagrammatical method it is shown that in scalar theories the stochastic quantization method of Parisi and Wu gives the usual perturbation series in Feynman diagrams. It is further explained how to apply the diagrammatical method to gauge theories, discussing the origin of ghost effects. (Author)

A complete dc characterization of a constant-frequency, clamped-mode, series-resonant converter

Science.gov (United States)

Tsai, Fu-Sheng; Lee, Fred C.

1988-01-01

The dc behavior of a clamped-mode series-resonant converter is characterized systematically. Given a circuit operating condition, the converter's mode of operation is determined and various circuit parameters are calculated, such as average inductor current (load current), rms inductor current, peak capacitor voltage, rms switch currents, average diode currents, switch turn-on currents, and switch turn-off currents. Regions of operation are defined, and various circuit characteristics are derived to facilitate the converter design.

Higher order perturbation theory - An example for discussion

International Nuclear Information System (INIS)

Lewins, J.D.; Parks, G.; Babb, A.L.

1986-01-01

Higher order perturbation theory is developed in the form of a Taylor series expansion to third order to calculate the thermal utilization of a nonuniform cell. The development takes advantage of the self-adjoint property of the diffusion operator to provide a simple development of this illustration of generalized perturbation theory employing scalar perturbation parameters. The results show how a designer might employ a second-order theory to quantify proposed design improvements, together with the limitations of second- and third-order theory. The chosen example has an exact optimization solution and thus provides a clear understanding of the role of perturbation theory at its various orders. Convergence and the computational advantages and disadvantages of the method are discussed

MCNP perturbation technique for criticality analysis

International Nuclear Information System (INIS)

McKinney, G.W.; Iverson, J.L.

1995-01-01

The differential operator perturbation technique has been incorporated into the Monte Carlo N-Particle transport code MCNP and will become a standard feature of future releases. This feature includes first and/or second order terms of the Taylor Series expansion for response perturbations related to cross-section data (i.e., density, composition, etc.). Criticality analyses can benefit from this technique in that predicted changes in the track-length tally estimator of K eff may be obtained for multiple perturbations in a single run. A key advantage of this method is that a precise estimate of a small change in response (i.e., < 1%) is easily obtained. This technique can also offer acceptable accuracy, to within a few percent, for up to 20-30% changes in a response

An introduction to non-harmonic Fourier series

CERN Document Server

Young, Robert M

2001-01-01

An Introduction to Non-Harmonic Fourier Series, Revised Edition is an update of a widely known and highly respected classic textbook.Throughout the book, material has also been added on recent developments, including stability theory, the frame radius, and applications to signal analysis and the control of partial differential equations.

New Results in {mathcal {N}}=2 N = 2 Theories from Non-perturbative String

Science.gov (United States)

Bonelli, Giulio; Grassi, Alba; Tanzini, Alessandro

2018-03-01

We describe the magnetic phase of SU(N) $\\mathcal{N}=2$ Super Yang-Mills theories in the self-dual Omega background in terms of a new class of multi-cut matrix models. These arise from a non-perturbative completion of topological strings in the dual four dimensional limit which engineers the gauge theory in the strongly coupled magnetic frame. The corresponding spectral determinants provide natural candidates for the tau functions of isomonodromy problems for flat spectral connections associated to the Seiberg-Witten geometry.

Scale-invariant scalar metric fluctuations during inflation: non-perturbative formalism from a 5D vacuum

International Nuclear Information System (INIS)

Anabitarte, M.; Bellini, M.; Madriz Aguilar, Jose Edgar

2010-01-01

We extend to 5D an approach of a 4D non-perturbative formalism to study scalar metric fluctuations of a 5D Riemann-flat de Sitter background metric. In contrast with the results obtained in 4D, the spectrum of cosmological scalar metric fluctuations during inflation can be scale invariant and the background inflaton field can take sub-Planckian values. (orig.)

Parametric resonance in the early Universe—a fitting analysis