WorldWideScience

Sample records for scattering amplitudes due

  1. Unifying relations for scattering amplitudes

    Science.gov (United States)

    Cheung, Clifford; Shen, Chia-Hsien; Wen, Congkao

    2018-02-01

    We derive new amplitudes relations revealing a hidden unity among a wideranging variety of theories in arbitrary spacetime dimensions. Our results rely on a set of Lorentz invariant differential operators which transmute physical tree-level scattering amplitudes into new ones. By transmuting the amplitudes of gravity coupled to a dilaton and two-form, we generate all the amplitudes of Einstein-Yang-Mills theory, Dirac-Born-Infield theory, special Galileon, nonlinear sigma model, and biadjoint scalar theory. Transmutation also relates amplitudes in string theory and its variants. As a corollary, celebrated aspects of gluon and graviton scattering like color-kinematics duality, the KLT relations, and the CHY construction are inherited traits of the transmuted amplitudes. Transmutation recasts the Adler zero as a trivial consequence of the Weinberg soft theorem and implies new subleading soft theorems for certain scalar theories.

  2. Scattering amplitudes in gauge theories

    CERN Document Server

    Henn, Johannes M

    2014-01-01

    At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge.   These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...

  3. Scattering Amplitudes from Intersection Theory.

    Science.gov (United States)

    Mizera, Sebastian

    2018-04-06

    We use Picard-Lefschetz theory to prove a new formula for intersection numbers of twisted cocycles associated with a given arrangement of hyperplanes. In a special case when this arrangement produces the moduli space of punctured Riemann spheres, intersection numbers become tree-level scattering amplitudes of quantum field theories in the Cachazo-He-Yuan formulation.

  4. Periodic instantons and scattering amplitudes

    International Nuclear Information System (INIS)

    Khlebnikov, S.Yu.; Rubakov, V.A.; Tinyakov, P.G.

    1991-04-01

    We discuss the role of periodic euclidean solutions with two turning points and zero winding number (periodic instantons) in instanton induced processes below the sphaleron energy E sph . We find that the periodic instantons describe certain multiparticle scattering events leading to the transitions between topologically distinct vacua. Both the semiclassical amplitudes and inital and final states of these transitions are determined by the periodic instantons. Furthermore, the corresponding probabilities are maximal among all states of given energy. We show that at E ≤ E sph , the periodic instantons can be approximated by infinite chains of ordinary instantons and anti-instantons, and they naturally emerge as deformations of the zero energy instanton. In the framework of 2d abelian Higgs model and 4d electroweak theory we show, however, that there is not obvious relation between periodic instantons and two-particle scattering amplitudes. (orig.)

  5. Determination of the scattering amplitude

    International Nuclear Information System (INIS)

    Gangal, A.D.; Kupsch, J.

    1984-01-01

    The problem to determine the elastic scattering amplitude from the differential cross-section by the unitarity equation is reexamined. We prove that the solution is unique and can be determined by a convergent iteration if the parameter lambda=sin μ of Newton and Martin is bounded by lambda 2 approx.=0.86. The method is based on a fixed point theorem for holomorphic mappings in a complex Banach space. (orig.)

  6. Cluster polylogarithms for scattering amplitudes

    International Nuclear Information System (INIS)

    Golden, John; Paulos, Miguel F; Spradlin, Marcus; Volovich, Anastasia

    2014-01-01

    Motivated by the cluster structure of two-loop scattering amplitudes in N=4 Yang-Mills theory we define cluster polylogarithm functions. We find that all such functions of weight four are made up of a single simple building block associated with the A 2 cluster algebra. Adding the requirement of locality on generalized Stasheff polytopes, we find that these A 2 building blocks arrange themselves to form a unique function associated with the A 3 cluster algebra. This A 3 function manifests all of the cluster algebraic structure of the two-loop n-particle MHV amplitudes for all n, and we use it to provide an explicit representation for the most complicated part of the n = 7 amplitude as an example. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Cluster algebras in mathematical physics’. (paper)

  7. Scattering amplitudes in gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Plefka, Jan C. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2014-03-01

    First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

  8. Scattering amplitudes in gauge theories

    International Nuclear Information System (INIS)

    Henn, Johannes M.; Plefka, Jan C.

    2014-01-01

    First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

  9. Grassmannian geometry of scattering amplitudes

    CERN Document Server

    Arkani-Hamed, Nima; Cachazo, Freddy; Goncharov, Alexander; Postnikov, Alexander; Trnka, Jaroslav

    2016-01-01

    Outlining a revolutionary reformulation of the foundations of perturbative quantum field theory, this book is a self-contained and authoritative analysis of the application of this new formulation to the case of planar, maximally supersymmetric Yang–Mills theory. The book begins by deriving connections between scattering amplitudes and Grassmannian geometry from first principles before introducing novel physical and mathematical ideas in a systematic manner accessible to both physicists and mathematicians. The principle players in this process are on-shell functions which are closely related to certain sub-strata of Grassmannian manifolds called positroids - in terms of which the classification of on-shell functions and their relations becomes combinatorially manifest. This is an essential introduction to the geometry and combinatorics of the positroid stratification of the Grassmannian and an ideal text for advanced students and researchers working in the areas of field theory, high energy physics, and the...

  10. Scattering Amplitudes via Algebraic Geometry Methods

    DEFF Research Database (Denmark)

    Søgaard, Mads

    Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized...

  11. Scattering Amplitudes via Algebraic Geometry Methods

    CERN Document Server

    Søgaard, Mads; Damgaard, Poul Henrik

    This thesis describes recent progress in the understanding of the mathematical structure of scattering amplitudes in quantum field theory. The primary purpose is to develop an enhanced analytic framework for computing multiloop scattering amplitudes in generic gauge theories including QCD without Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized unitarity cuts. We take advantage of principles from algebraic geometry in order to extend the notion of maximal cuts to a large class of two- and three-loop integrals. This allows us to derive unique and surprisingly compact formulae for the coefficients of the basis integrals. Our results are expressed in terms of certain linear combinations of multivariate residues and elliptic integrals computed from products of ...

  12. How to calculate the Coulomb scattering amplitude

    International Nuclear Information System (INIS)

    Grosse, H.; Narnhofer, H.; Thirring, W.

    1974-01-01

    The derivation of scattering amplitudes for Coulomb scattering is discussed. A derivation of the S-matrix elements for a dense set of states in momentum space is given in the framework of time dependent scattering theory. The convergence of the S-matrix is studied. A purely algebraic derivation of the S-matrix elements and phase shifts is also presented. (HFdV)

  13. Effective string theory and QCD scattering amplitudes

    International Nuclear Information System (INIS)

    Makeenko, Yuri

    2011-01-01

    QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luescher term, and discuss an application to meson scattering amplitudes in QCD.

  14. Scattering Amplitudes and Worldsheet Models of QFTs

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    I will describe recent progress on the study of scattering amplitudes via ambitwistor strings and the scattering equations. Ambitwistor strings are worldsheet models of quantum field theories, inspired by string theory. They naturally lead to a representation of amplitudes based on the scattering equations. While worldsheet models and related ideas have had a wide-ranging impact on the modern study of amplitudes, their direct application at loop level is a very recent success. I will show how a major difficulty in the loop-level story, the technicalities of higher-genus Riemann surfaces, can be avoided by turning the higher-genus surface into a nodal Riemann sphere, with the nodes representing the loop momenta. I will present new formulas for the one-loop integrands of gauge theory and gravity, with or without supersymmetry, and also some two-loop results.

  15. Deep Inelastic Scattering at the Amplitude Level

    International Nuclear Information System (INIS)

    Brodsky, Stanley J.

    2005-01-01

    The deep inelastic lepton scattering and deeply virtual Compton scattering cross sections can be interpreted in terms of the fundamental wavefunctions defined by the light-front Fock expansion, thus allowing tests of QCD at the amplitude level. The AdS/CFT correspondence between gauge theory and string theory provides remarkable new insights into QCD, including a model for hadronic wavefunctions which display conformal scaling at short distances and color confinement at large distances

  16. Holographic corrections to meson scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Armoni, Adi; Ireson, Edwin, E-mail: 746616@swansea.ac.uk

    2017-06-15

    We compute meson scattering amplitudes using the holographic duality between confining gauge theories and string theory, in order to consider holographic corrections to the Veneziano amplitude and associated higher-point functions. The generic nature of such computations is explained, thanks to the well-understood nature of confining string backgrounds, and two different examples of the calculation in given backgrounds are used to illustrate the details. The effect we discover, whilst only qualitative, is re-obtainable in many such examples, in four-point but also higher point amplitudes.

  17. Constraints on low energy Compton scattering amplitudes

    International Nuclear Information System (INIS)

    Raszillier, I.

    1979-04-01

    We derive the constraints and correlations of fairly general type for Compton scattering amplitudes at energies below photoproduction threshold and fixed momentum transfer, following from (an upper bound on) the corresponding differential cross section above photoproduction threshold. The derivation involves the solution of an extremal problem in a certain space of vector - valued analytic functions. (author)

  18. Scattering amplitudes in super-renormalizable gravity

    International Nuclear Information System (INIS)

    Donà, Pietro; Giaccari, Stefano; Modesto, Leonardo; Rachwał, Lesław; Zhu, Yiwei

    2015-01-01

    We explicitly compute the tree-level on-shell four-graviton amplitudes in four, five and six dimensions for local and weakly nonlocal gravitational theories that are quadratic in both, the Ricci and scalar curvature with form factors of the d’Alembertian operator inserted between. More specifically we are interested in renormalizable, super-renormalizable or finite theories. The scattering amplitudes for these theories turn out to be the same as the ones of Einstein gravity regardless of the explicit form of the form factors. As a special case the four-graviton scattering amplitudes in Weyl conformal gravity are identically zero. Using a field redefinition, we prove that the outcome is correct for any number of external gravitons (on-shell n−point functions) and in any dimension for a large class of theories. However, when an operator quadratic in the Riemann tensor is added in any dimension (with the exception of the Gauss-Bonnet term in four dimensions) the result is completely altered, and the scattering amplitudes depend on all the form factors introduced in the action.

  19. Scattering amplitudes in open superstring theory

    Energy Technology Data Exchange (ETDEWEB)

    Schlotterer, Oliver

    2011-07-15

    The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all

  20. Scattering amplitudes in open superstring theory

    International Nuclear Information System (INIS)

    Schlotterer, Oliver

    2011-01-01

    The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all

  1. Amplitude growth due to random, correlated kicks

    International Nuclear Information System (INIS)

    Michelotti, L.; Mills, F.

    1989-03-01

    Historically, stochastic processes, such as gas scattering or stochastic cooling, have been treated by the Fokker-Planck equation. In this approach, usually considered for one dimension only, the equation can be considered as a continuity equation for a variable which would be a constant of the motion in the absence of the stochastic process, for example, the action variable, I = ε/2π for betatron oscillations, where ε is the area of the Courant-Snyder ellipse, or energy in the case of unbunched beams, or the action variable for phase oscillations in case the beam is bunched. A flux, /Phi/, including diffusive terms can be defined, usually to second order. /Phi/ = M 1 F(I) + M 2 ∂F/∂I + /hor ellipsis/. M 1 and M 2 are the expectation values of δI and (δI) 2 due to the individual stochastic kicks over some period of time, long enough that the variance of these quantities is sufficiently small. Then the Fokker-Planck equation is just ∂F/∂I + ∂/Phi//∂I = 0. In many cases those where the beam distribution has already achieved its final shape, it is sufficient to find the rate of increase of by taking simple averages over the Fokker-Planck equation. At the time this work was begun, there was good knowledge of the second moment for general stochastic processes due to stochastic cooling theory, but the form of the first moment was known only for extremely wideband processes. The purposes of this note are to derive an expression relating the expected single particle amplitude growth to the noise autocorrelation function and to obtain, thereby, the form of M 1 for narrow band processes. 4 refs

  2. Multichannel conformal blocks for scattering amplitudes

    Science.gov (United States)

    Belitsky, A. V.

    2018-05-01

    By performing resummation of small fermion-antifermion pairs within the pentagon form factor program to scattering amplitudes in planar N = 4 superYang-Mills theory, we construct multichannel conformal blocks within the flux-tube picture for N-sided NMHV polygons. This procedure is equivalent to summation of descendants of conformal primaries in the OPE framework. The resulting conformal partial waves are determined by multivariable hypergeometric series of Lauricella-Saran type.

  3. Scattering amplitudes from multivariate polynomial division

    Energy Technology Data Exchange (ETDEWEB)

    Mastrolia, Pierpaolo, E-mail: pierpaolo.mastrolia@cern.ch [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Dipartimento di Fisica e Astronomia, Universita di Padova, Padova (Italy); INFN Sezione di Padova, via Marzolo 8, 35131 Padova (Italy); Mirabella, Edoardo, E-mail: mirabell@mppmu.mpg.de [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Ossola, Giovanni, E-mail: GOssola@citytech.cuny.edu [New York City College of Technology, City University of New York, 300 Jay Street, Brooklyn, NY 11201 (United States); Graduate School and University Center, City University of New York, 365 Fifth Avenue, New York, NY 10016 (United States); Peraro, Tiziano, E-mail: peraro@mppmu.mpg.de [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)

    2012-11-15

    We show that the evaluation of scattering amplitudes can be formulated as a problem of multivariate polynomial division, with the components of the integration-momenta as indeterminates. We present a recurrence relation which, independently of the number of loops, leads to the multi-particle pole decomposition of the integrands of the scattering amplitudes. The recursive algorithm is based on the weak Nullstellensatz theorem and on the division modulo the Groebner basis associated to all possible multi-particle cuts. We apply it to dimensionally regulated one-loop amplitudes, recovering the well-known integrand-decomposition formula. Finally, we focus on the maximum-cut, defined as a system of on-shell conditions constraining the components of all the integration-momenta. By means of the Finiteness Theorem and of the Shape Lemma, we prove that the residue at the maximum-cut is parametrized by a number of coefficients equal to the number of solutions of the cut itself.

  4. Integrable spin chains and scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Prygarin, A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Lipatov, L.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Petersburg Nuclear Physics Institute (Russian Federation); Sankt-Peterburgskij Univ., St. Petersburg (Russian Federation)

    2011-04-15

    In this review we show that the multi-particle scattering amplitudes in N=4 SYM at large N{sub c} and in the multi-Regge kinematics for some physical regions have the high energy behavior appearing from the contribution of the Mandelstam cuts in the complex angular momentum plane of the corresponding t-channel partial waves. These Mandelstam cuts or Regge cuts are resulting from gluon composite states in the adjoint representation of the gauge group SU(N{sub c}). In the leading logarithmic approximation (LLA) their contribution to the six point amplitude is in full agreement with the known two-loop result. The Hamiltonian for the Mandelstam states constructed from n gluons in LLA coincides with the local Hamiltonian of an integrable open spin chain. We construct the corresponding wave functions using the integrals of motion and the Baxter-Sklyanin approach. (orig.)

  5. First order correction to quasiclassical scattering amplitude

    International Nuclear Information System (INIS)

    Kuz'menko, A.V.

    1978-01-01

    First order (with respect to h) correction to quasiclassical with the aid of scattering amplitude in nonrelativistic quantum mechanics is considered. This correction is represented by two-loop diagrams and includes the double integrals. With the aid of classical equations of motion, the sum of the contributions of the two-loop diagrams is transformed into the expression which includes one-dimensional integrals only. The specific property of the expression obtained is that the integrand does not possess any singularities in the focal points of the classical trajectory. The general formula takes much simpler form in the case of one-dimensional systems

  6. Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis

    Science.gov (United States)

    Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.

  7. Eikonal representation of N-body Coulomb scattering amplitudes

    International Nuclear Information System (INIS)

    Fried, H.M.; Kang, K.; McKellar, B.H.J.

    1983-01-01

    A new technique for the construction of N-body Coulomb scattering amplitudes is proposed, suggested by the simplest case of N = 2: Calculate the scattering amplitude in eikonal approximation, discard the infinite phase factors which appear upon taking the limit of a Coulomb potential, and treat the remainder as an amplitude whose absolute value squared produces the exact, Coulomb differential cross section. The method easily generalizes to the N-body Coulomb problem for elastic scattering, and for inelastic rearrangement scattering of Coulomb bound states. We give explicit results for N = 3 and 4; in the N = 3 case we extract amplitudes for the processes (12)+3->1+2+3 (breakup), (12)+3->1+(23) (rearrangement), and (12)+3→(12)'+3 (inelastic scattering) as residues at the appropriate poles in the free-free amplitude. The method produces scattering amplitudes f/sub N/ given in terms of explicit quadratures over (N-2) 2 distinct integrands

  8. Determination of backward pion nucleon scattering amplitudes

    International Nuclear Information System (INIS)

    Pietarinen, E.

    1978-04-01

    Backward C(sup(+-))πN amplitudes are determined from πN→Nπ and NantiN→2π differential cross sections in such a way that they are consistent with the analyticity properties and information of the unphysical ππ→NantiN amplitudes. Combining the result with forward C(sup(+-)) amplitudes positive and negative parity resonances are extracted. An error analysis of the amplitudes is performed. (author)

  9. Singularities of elastic scattering amplitude by long-range potentials

    International Nuclear Information System (INIS)

    Kvitsinsky, A.A.; Komarov, I.V.; Merkuriev, S.P.

    1982-01-01

    The angular peculiarities and the zero energy singularities of the elastic scattering amplitude by a long-range potential are described. The singularities of the elastic (2 → 2) scattering amplitude for a system of three Coulomb particles are considered [ru

  10. Miracles in Scattering Amplitudes: from QCD to Gravity

    Energy Technology Data Exchange (ETDEWEB)

    Volovich, Anastasia [Brown Univ., Providence, RI (United States)

    2016-10-09

    The goal of my research project "Miracles in Scattering Amplitudes: from QCD to Gravity" involves deepening our understanding of gauge and gravity theories by exploring hidden structures in scattering amplitudes and using these rich structures as much as possible to aid practical calculations.

  11. Renormalization Scale-Fixing for Complex Scattering Amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Llanes-Estrada, Felipe J.; /Madrid U.

    2005-12-21

    We show how to fix the renormalization scale for hard-scattering exclusive processes such as deeply virtual meson electroproduction by applying the BLM prescription to the imaginary part of the scattering amplitude and employing a fixed-t dispersion relation to obtain the scale-fixed real part. In this way we resolve the ambiguity in BLM renormalization scale-setting for complex scattering amplitudes. We illustrate this by computing the H generalized parton distribution at leading twist in an analytic quark-diquark model for the parton-proton scattering amplitude which can incorporate Regge exchange contributions characteristic of the deep inelastic structure functions.

  12. Corrections to the large-angle scattering amplitude

    International Nuclear Information System (INIS)

    Goloskokov, S.V.; Kudinov, A.V.; Kuleshov, S.P.

    1979-01-01

    High-energy behaviour of scattering amplitudes is considered within the frames of Logunov-Tavchelidze quasipotential approach. The representation of scattering amplitude of two scalar particles, convenient for the study of its asymptotic properties is given. Obtained are corrections of the main value of scattering amplitude of the first and the second orders in 1/p, where p is the pulse of colliding particles in the system of the inertia centre. An example of the obtained formulas use for a concrete quasipotential is given

  13. Singularity Structure of Maximally Supersymmetric Scattering Amplitudes

    DEFF Research Database (Denmark)

    Arkani-Hamed, Nima; Bourjaily, Jacob L.; Cachazo, Freddy

    2014-01-01

    We present evidence that loop amplitudes in maximally supersymmetric (N=4) Yang-Mills theory (SYM) beyond the planar limit share some of the remarkable structures of the planar theory. In particular, we show that through two loops, the four-particle amplitude in full N=4 SYM has only logarithmic ...... singularities and is free of any poles at infinity—properties closely related to uniform transcendentality and the UV finiteness of the theory. We also briefly comment on implications for maximal (N=8) supergravity theory (SUGRA)....

  14. Multiple pole in the electron--hydrogen-atom scattering amplitude

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Kuchiev, M.Y.

    1982-01-01

    It is demonstrated that the amplitude for electron--hydrogen-atom forward scattering has the third-order pole at the point E = -13.6 eV, E being the energy of the incident electron. The coefficients which characterize the pole are calculated exactly. The invalidity of the Born approximation is proved. The contribution of the pole singularity to the dispersion relation for the scattering amplitude is discussed

  15. Properties of the scattering amplitude for electron-atom collisions

    International Nuclear Information System (INIS)

    Combes, J.M.; Tip, A.

    1983-02-01

    For the scattering of an electron by an atom finiteness of the amplitude at non threshold energies is proved in the framework of the N-body Schroedinger equation. It is also shown that both the direct and exchange amplitudes have analytic continuations for complex values of incident momentum, with pole or cut singularities on the imaginary axis

  16. Improved pion pion scattering amplitude from dispersion relation formalism

    International Nuclear Information System (INIS)

    Cavalcante, I.P.; Coutinho, Y.A.; Borges, J. Sa

    2005-01-01

    Pion-pion scattering amplitude is obtained from Chiral Perturbation Theory at one- and two-loop approximations. Dispersion relation formalism provides a more economic method, which was proved to reproduce the analytical structure of that amplitude at both approximation levels. This work extends the use of the formalism in order to compute further unitarity corrections to partial waves, including the D-wave amplitude. (author)

  17. The zerology of kaon-nucleon forward scattering amplitudes

    International Nuclear Information System (INIS)

    Dumbrajs, O.

    1981-01-01

    It has been realized for a long time that zeros of the forward kaon-nucleon scattering amplitudes are useful in correlating different low and high-energy scattering parameters and in providing a consistency test of available data. The simplest possibility of exploring zeros is to evaluate the ordinary dispersion relations in the complex energy plane. The more natural way of bringing zeros of amplitudes into play is to consider either one of the more sophisticated forms of dispersion relations: i) phase dispersion relations, ii) inverse-amplitude dispersion relations, iii) logarithmic dispersion relations, or to apply the maximum modulus theorem and a factorization theorem. The author concentrates on the use of logarithmic dispersion relations because this approach seems to be the most convenient one for future extensions to nonforward scattering data analyses based on the zeros of the amplitude. (Auth.)

  18. New rigorous asymptotic theorems for inverse scattering amplitudes

    International Nuclear Information System (INIS)

    Lomsadze, Sh.Yu.; Lomsadze, Yu.M.

    1984-01-01

    The rigorous asymptotic theorems both of integral and local types obtained earlier and establishing logarithmic and in some cases even power correlations aetdeen the real and imaginary parts of scattering amplitudes Fsub(+-) are extended to the inverse amplitudes 1/Fsub(+-). One also succeeds in establishing power correlations of a new type between the real and imaginary parts, both for the amplitudes themselves and for the inverse ones. All the obtained assertions are convenient to be tested in high energy experiments when the amplitudes show asymptotic behaviour

  19. Analytical structure of the 3. -->. 3 forward scattering amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Logunov, A A; Medvedev, B V; Muzafarov, L M; Pavlov, V P; Polivanov, M K; Sukhanov, A D [AN SSSR, Moscow. Matematicheskij Inst.

    1979-08-01

    Analytical properties of the amplitude of 3..-->..3 forward scattering established in the framework of the Bogolyubov axiomatic approach are described. The amplitudes of the different channels of the process are boundary values of a unique analytical function of invariant variables. Crossing-symmetry property of the amplitude is proved. Analysis of the absorptive part of the amplitude is performed and the generalized optical theorem is proved which connects one of the contributions into the absorptive part with the distribution function of the inclusive process.

  20. Scattering amplitudes in four- and six-dimensional gauge theories

    International Nuclear Information System (INIS)

    Schuster, Theodor

    2014-01-01

    We study scattering amplitudes in quantum chromodynamics (QCD), N=4 super Yang-Mills (SYM) theory and the six-dimensional N=(1,1) SYM theory, focusing on the symmetries of and relations between the tree-level scattering amplitudes in these three gauge theories. We derive the tree level and one-loop color decomposition of an arbitrary QCD amplitude into primitive amplitudes. Furthermore, we derive identities spanning the null space among the primitive amplitudes. We prove that every color ordered tree amplitude of massless QCD can be obtained from gluon-gluino amplitudes of N=4 SYM theory. Furthermore, we derive analytical formulae for all gluon-gluino amplitudes relevant for QCD. We compare the numerical efficiency and accuracy of evaluating these closed analytic formulae for color ordered QCD tree amplitudes to a numerically efficient implementation of the Berends-Giele recursion. We derive the symmetries of massive tree amplitudes on the coulomb branch of N=4 SYM theory, which in turn can be obtained from N=(1,1) SYM theory by dimensional reduction. Furthermore, we investigate the tree amplitudes of N=(1, 1) SYM theory and explain how analytical formulae can be obtained from a numerical implementation of the supersymmetric BCFW recursion relation and investigate a potential uplift of the massless tree amplitudes of N=4 SYM theory. Finally we study an alternative to dimensional regularization of N=4 SYM theory. The infrared divergences are regulated by masses obtained from a Higgs mechanism. The corresponding string theory set-up suggests that the amplitudes have an exact dual conformal symmetry. We confirm this expectation and illustrate the calculational advantages of the massive regulator by explicit calculations.

  1. Green function and scattering amplitudes in many dimensional space

    International Nuclear Information System (INIS)

    Fabre de la Ripelle, M.

    1991-06-01

    Methods for solving scattering are studied in many dimensional space. Green function and scattering amplitudes are given in terms of the requested asymptotic behaviour of the wave function. The Born approximation and the optical theorem are derived in many dimensional space. Phase-shift analysis are developed for hypercentral potentials and for non-hypercentral potentials with the hyperspherical adiabatic approximation. (author) 16 refs., 3 figs

  2. Analytical fits to Fink's electron scattering amplitudes, 1

    International Nuclear Information System (INIS)

    Hayashi, Shigeo

    1984-01-01

    Numerical data of the direct and spin-flip amplitudes for elastic electron scattering, calculated previously by Fink and co-workers, were expressed in the form Σc 1 exp(-c 2 x+ic 3 +ic 4 ), where x=1-cos theta,theta being a scattering angle. The adjustable c-parameters were determined by the use of a simplex method. Results are reported for carbon at incident electron energies of 25-1000eV. (author)

  3. Green functions and scattering amplitudes in many-dimensional space

    International Nuclear Information System (INIS)

    Fabre de la Ripelle, M.

    1993-01-01

    Methods for solving scattering are studied in many-dimensional space. Green function and scattering amplitudes are given in terms of the required asymptotic behaviour of the wave function. The Born approximation and the optical theorem are derived in many-dimensional space. Phase-shift analyses are performed for hypercentral potentials and for non-hypercentral potentials by use of the hyperspherical adiabatic approximation. (author)

  4. Conformal higher spin scattering amplitudes from twistor space

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim [Blackett Laboratory, Imperial College, London, SW7 2AZ (United Kingdom); Hähnel, Philipp; McLoughlin, Tristan [School of Mathematics, Trinity College Dublin, College Green, Dublin 2 (Ireland)

    2017-04-04

    We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point (MHV)-bar amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.

  5. Conformal higher spin scattering amplitudes from twistor space

    International Nuclear Information System (INIS)

    Adamo, Tim; Hähnel, Philipp; McLoughlin, Tristan

    2017-01-01

    We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point (MHV)-bar amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.

  6. Hilbert-Schmidt expansion for the nucleon-deuteron scattering amplitude

    International Nuclear Information System (INIS)

    Moeller, K.; Narodetskii, I.M.

    1983-01-01

    The Hilbert-Schmidt method is used to sum the divergent iterative series for the partial amplitudes of nucleon-deuteron scattering in the energy region above the deuteron breakup threshold. It is observed that the Hilbert-Schmidt series for the partial amplitudes themselves diverges, which is due to the closeness of the logarithmic singularities. But if the first iterations in the series for multiple scattering are subtracted from the amplitude, the Hilbert-Schmidt series for the remainder converges rapidly. The final answer obtained in the present paper is in excellent agreement with the results obtained in exact calculations

  7. Born amplitudes and seagull term in meson-soliton scattering

    International Nuclear Information System (INIS)

    Liang, Y.G.; Li, B.A.; Liu, K.F.; Su, R.K.

    1990-01-01

    The meson-soliton scattering for the φ 4 theory in 1+1 dimensions is calculated. We show that when the seagull term from the equal time commutator is included in addition to the Born amplitudes, the t-matrix from the reduction formula approach is identical to that of the potential scattering with small quantum fluctuations to leading order in weak coupling. The seagull term is equal to the Born term in the potential scattering. This confirms the speculation that the leading order Yukawa coupling is derivable from the classical soliton. (orig.)

  8. Double logarithmic asymptotics of quark scattering amplitudes with flavour exchange

    International Nuclear Information System (INIS)

    Kirschner , R.; Lipatov, L.N.

    1982-02-01

    We propose simple equations in terms of the definite signature partial waves of the quark scattering and annihilation amplitudes with quark-quark and quark-antiquark states in the exchange channel. We discuss the singularities in the complex angular momentum plane generated by the double logarithmic contributions and point out their relation to the particle Regge trajectories. (author)

  9. Unitarity relations for the four-body scattering amplitude

    International Nuclear Information System (INIS)

    Matsui, Y.

    1988-01-01

    A formal derivation of the general unitarity relation for the four-particle transition operator is given by generalizing the three-body formalism of Karlson and Zeiger to the four-body case. From this operator relation the on-shell unitarity relations for the amplitudes that describe elastic/rearrangement, partial breakup, and full breakup scattering processes are obtained

  10. Positivity of the real part of the forward scattering amplitude

    Science.gov (United States)

    Martin, André; Wu, Tai Tsun

    2018-01-01

    We prove the general theorem that the real part of the crossing even forward two-body scattering amplitude is positive at sufficiently high energies if, above a certain energy, the total cross section increases monotonically to infinity at infinite energy.

  11. On expansion of scattering amplitude at large momentum transfers

    International Nuclear Information System (INIS)

    Edneral, V.F.; Troshin, S.M.; Tyurin, N.E.

    1979-01-01

    The aim of the paper is to construct an iterative approximation for hadronic scattering amplitude and to search for the related small parameters. The expansion of the amplitude is obtained. A series is derived where the role of the small parameter is played by the quantity dependent on the momentum transfer. The appearance of the small parameter is directly related to the growth of total cross section. For the case g 2 not equal to 0 in the framework of the strong interaction theory model, based on the solution of three-domensional dynamical equation an expression is obtained for scattering amplitude in the form of a series over the quantity decreasing with the growth of momentum transfer

  12. Harmonic R-matrices for scattering amplitudes and spectral regularization

    Energy Technology Data Exchange (ETDEWEB)

    Ferro, Livia; Plefka, Jan [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Lukowski, Tomasz [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Univ. Berlin (Germany). IRIS Adlershof; Meneghelli, Carlo [Hamburg Univ. (Germany). Fachbereich 11 - Mathematik; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Staudacher, Matthias [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Potsdam (Germany)

    2012-12-15

    Planar N=4 super Yang-Mills appears to be integrable. While this allows to find this theory's exact spectrum, integrability has hitherto been of no direct use for scattering amplitudes. To remedy this, we deform all scattering amplitudes by a spectral parameter. The deformed tree-level four-point function turns out to be essentially the one-loop R-matrix of the integrable N=4 spin chain satisfying the Yang-Baxter equation. Deformed on-shell three-point functions yield novel three-leg R-matrices satisfying bootstrap equations. Finally, we supply initial evidence that the spectral parameter might find its use as a novel symmetry-respecting regulator replacing dimensional regularization. Its physical meaning is a local deformation of particle helicity, a fact which might be useful for a much larger class of non-integrable four-dimensional field theories.

  13. Infrared singularities of scattering amplitudes in perturbative QCD

    Energy Technology Data Exchange (ETDEWEB)

    Becher, Thomas [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Neubert, Matthias [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany)

    2013-11-01

    An exact formula is derived for the infrared singularities of dimensionally regularized scattering amplitudes in massless QCD with an arbitrary number of legs, valid at any number of loops. It is based on the conjecture that the anomalous-dimension matrix of n-jet operators in soft-collinear effective theory contains only a single non-trivial color structure, whose coefficient is the cusp anomalous dimension of Wilson loops with light-like segments. Its color-diagonal part is characterized by two anomalous dimensions, which are extracted to three-loop order from known perturbative results for the quark and gluon form factors. This allows us to predict the three-loop coefficients of all 1/epsilon^k poles for an arbitrary n-parton scattering amplitudes, generalizing existing two-loop results.

  14. Advanced methods for scattering amplitudes in gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Peraro, Tiziano

    2014-09-24

    We present new techniques for the evaluation of multi-loop scattering amplitudes and their application to gauge theories, with relevance to the Standard Model phenomenology. We define a mathematical framework for the multi-loop integrand reduction of arbitrary diagrams, and elaborate algebraic approaches, such as the Laurent expansion method, implemented in the software Ninja, and the multivariate polynomial division technique by means of Groebner bases.

  15. Advanced methods for scattering amplitudes in gauge theories

    International Nuclear Information System (INIS)

    Peraro, Tiziano

    2014-01-01

    We present new techniques for the evaluation of multi-loop scattering amplitudes and their application to gauge theories, with relevance to the Standard Model phenomenology. We define a mathematical framework for the multi-loop integrand reduction of arbitrary diagrams, and elaborate algebraic approaches, such as the Laurent expansion method, implemented in the software Ninja, and the multivariate polynomial division technique by means of Groebner bases.

  16. Scattering amplitudes in gauge theories with and without supersymmetry

    International Nuclear Information System (INIS)

    Ochirov, Alexander

    2014-01-01

    This thesis aims at providing better understanding of the perturbative expansion of gauge theories with and without supersymmetry. At tree level, the BCFW recursion relations are analyzed with respect to their validity for general off-shell objects in Yang-Mills theory, which is a significant step away from their established zone of applicability. Unphysical poles constitute a new potential problem in addition to the boundary behavior issue, common to the on-shell case as well. For an infinite family of massive fermion currents, both obstacles are shown to be avoided under the certain conditions, which provides a natural recursion relation. At one loop, scattering amplitudes can be calculated from unitarity cuts through their expansion into known scalar integrals with free coefficients. A powerful method to obtain these coefficients, namely spinor integration, is discussed and rederived in a somewhat novel form. It is then used to compute analytically the infinite series of one-loop gluon amplitudes in N = 1 super-Yang-Mills theory with exactly three negative helicities. The final part of this thesis concerns the intriguing relationship between gluon and graviton scattering amplitudes, which involves a beautiful duality between the color and kinematic content of gauge theories. This BCJ duality is extended to include particles in the fundamental representation of the gauge group, which is shown to relieve the restriction of the BCJ construction to factorizable gravities and thus give access to amplitudes in generic (super-)gravity theories. (author) [fr

  17. Two-Loop Scattering Amplitudes from the Riemann Sphere

    CERN Document Server

    Geyer, Yvonne; Monteiro, Ricardo; Tourkine, Piotr

    2016-01-01

    The scattering equations give striking formulae for massless scattering amplitudes at tree level and, as shown recently, at one loop. The progress at loop level was based on ambitwistor string theory, which naturally yields the scattering equations. We proposed that, for ambitwistor strings, the standard loop expansion in terms of the genus of the worldsheet is equivalent to an expansion in terms of nodes of a Riemann sphere, with the nodes carrying the loop momenta. In this paper, we show how to obtain two-loop scattering equations with the correct factorization properties. We adapt genus-two integrands from the ambitwistor string to the nodal Riemann sphere and show that these yield correct answers, by matching standard results for the four-point two-loop amplitudes of maximal supergravity and super-Yang-Mills theory. In the Yang-Mills case, this requires the loop analogue of the Parke-Taylor factor carrying the colour dependence, which includes non-planar contributions.

  18. On the Construction of Scattering Amplitudes for Spinning Massless Particles

    CERN Document Server

    Berends, F A

    1997-01-01

    In this paper the general form of scattering amplitudes for massless particles with equal spins s ($s s \\to s s$) or unequal spins ($s_a s_b \\to s_a s_b$) are derived. The imposed conditions are that the amplitudes should have the lowest possible dimension, have propagators of dimension $m^{-2}$, and obey gauge invariance. It is shown that the number of momenta required for amplitudes involving particles with s > 2 is higher than the number implied by 3-vertices for higher spin particles derived in the literature. Therefore, the dimension of the coupling constants following from the latter 3-vertices has a smaller power of an inverse mass than our results imply. Consequently, the 3-vertices in the literature cannot be the first interaction terms of a gauge-invariant theory. When no spins s > 2 are present in the process the known QCD, QED or (super) gravity amplitudes are obtained from the above general amplitudes.

  19. Construction of two-dimensional Schrodinger operator with given scattering amplitude at fixed energy

    International Nuclear Information System (INIS)

    Novikov, R.G.

    1986-01-01

    The classical necessary properties of the scattering amplitude (reciprocity and unitarity) are, provided its L 2 norm is small, sufficient for the existence of a two-dimensional Schrodinger operator with the given scattering amplitude at fixed energy

  20. Scattering amplitude of ultracold atoms near the p-wave magnetic Feshbach resonance

    International Nuclear Information System (INIS)

    Zhang Peng; Naidon, Pascal; Ueda, Masahito

    2010-01-01

    Most of the current theories on the p-wave superfluid in cold atomic gases are based on the effective-range theory for the two-body scattering, where the low-energy p-wave scattering amplitude f 1 (k) is given by f 1 (k)=-1/[ik+1/(Vk 2 )+1/R]. Here k is the incident momentum, V and R are the k-independent scattering volume and effective range, respectively. However, due to the long-range nature of the van der Waals interaction between two colliding ultracold atoms, the p-wave scattering amplitude of the two atoms is not described by the effective-range theory [J. Math. Phys. 4, 54 (1963); Phys. Rev. A 58, 4222 (1998)]. In this paper we provide an explicit calculation for the p-wave scattering of two ultracold atoms near the p-wave magnetic Feshbach resonance. We show that in this case the low-energy p-wave scattering amplitude f 1 (k)=-1/[ik+1/(V eff k 2 )+1/(S eff k)+1/R eff ] where V eff , S eff , and R eff are k-dependent parameters. Based on this result, we identify sufficient conditions for the effective-range theory to be a good approximation of the exact scattering amplitude. Using these conditions we show that the effective-range theory is a good approximation for the p-wave scattering in the ultracold gases of 6 Li and 40 K when the scattering volume is enhanced by the resonance.

  1. Analytic amplitudes for hadronic forward scattering: COMPETE update

    Energy Technology Data Exchange (ETDEWEB)

    Nicolescu, B.; Cudell, J.R.; Ezhela, V.V.; Gauron, P.; Kang, K.; Kuyanov, Yu.V.; Lugovsky, S.B.; Martynov, E.; Razuvaev, E.A.; Tkachenko, N.P

    2003-04-01

    We consider several classes of analytic parametrizations of hadronic scattering amplitudes, and compare their predictions to all available forward data (pp, p-bar p, {pi}p, Kp, {gamma}p, {gamma}{gamma}, {sigma}p). Although these parametrizations are very close for {radical}s {>=} 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term {approx} ln{sup 2} s enables one to extend the fit down to {radical}s = 4 GeV. We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude ({rho} parameter) for present and future pp and p-bar p colliders, and on the total cross sections for {gamma}p {yields} hadrons at cosmic-ray energies and for {gamma}{gamma} {yields} hadrons up to {radical}s = 1 TeV.

  2. Cluster algebras in scattering amplitudes with special 2D kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Marcus A.C. [Institut de Physique Theorique, CEA-Saclay, Gif-sur-Yvette Cedex (France)

    2014-02-15

    We study the cluster algebra of the kinematic configuration space Conf{sub n}(P{sup 3}P3) of an n-particle scattering amplitude restricted to the special 2D kinematics. We found that the n-point two-loop MHVremainder function in special 2D kinematics depends on a selection of the X-coordinates that are part of a special structure of the cluster algebra related to snake triangulations of polygons. This structure forms a necklace of hypercube beads in the corresponding Stasheff polytope. Furthermore at n = 12, the cluster algebra and the selection of theX-coordinates in special2Dkinematics replicates the cluster algebra and the selection of X-coordinates of the n = 6 two-loop MHV amplitude in 4D kinematics. (orig.)

  3. Long-distance singularities in multi-leg scattering amplitudes

    CERN Document Server

    Gardi, Einan; Duhr, Claude

    2016-01-01

    We report on the recent completion of the three-loop calculation of the soft anomalous dimension in massless gauge-theory scattering amplitudes. This brings the state-of-the-art knowledge of long-distance singularities in multi-leg QCD amplitudes with any number of massless particles to three loops. The result displays some novel features: this is the first time non-dipole corrections appear, which directly correlate the colour and kinematic degrees of freedom of four coloured partons. We find that non-dipole corrections appear at three loops also for three coloured partons, but these are independent of the kinematics. The final result is remarkably simple when expressed in terms of single-valued harmonic polylogarithms, and it satisfies several non-trivial constraints. In particular, it is consistent with the high-energy limit behaviour and it satisfies the expected factorization properties in two-particle collinear limits.

  4. Automated evaluation of one-loop scattering amplitudes

    International Nuclear Information System (INIS)

    Deurzen, Hans van

    2015-01-01

    In this dissertation the developments toward fully automated evaluation of one-loop scattering amplitudes will be presented, as implemented in the GoSam framework. The code Xsamurai, part of GoSam, is described, which implements the integrand reduction algorithm including an extension to higher-rank capability. GoSam was used to compute several Higgs boson production channels at NLO QCD. An interface between GoSam and a Monte Carlo program was constructed, which enables computing any process at NLO precision needed in the LHC era.

  5. Some bounds on pion-scattering amplitudes and their applications

    International Nuclear Information System (INIS)

    Chung, B.K.; Vinh Mau, R.

    1976-01-01

    If one uses the method introduced by Meinam and further developed by Martin, together with unitarity crossing symmetry and analyticity, upper and lower bounds to the πdeg πged scattering amplitudes inside the Mandelstam triangle are obtained in terms of the scattering lengths. These bounds are used to set a lower bound to the renormalized pion coupling constant lambda. In terms of the D-wave scattering length a 2 , the results are a 0 greater than or equal to -23.18 square root a 2 + 129.07a 2 and -7.71 square root a 2 less than or equal to lambda less than or equal to 7.71 square root a 2 +2.5a 2 . For a 2 =7.10 -4 they yield a 2 greater than or equal to -0.52 and lambda less than or equal to 0.20 where the pion, mass is set equal to unity

  6. Local analyticity properties of the n particle scattering amplitude

    CERN Document Server

    Bros, J; Glaser, Vladimir Jurko

    1972-01-01

    The connected part F/sub /c(p) of the scattering amplitude (p/sub 1 /...p/sub /r mod S-1 mod p/sub r+1/,..., p/sub n/) defined on the mass shell p/sub i//sup 2/=m/sub i//sup 2/ and deduced from a local field theory involving only (stable) particles with strictly positive masses can be represented in a suitable neighbourhood of any physical point p as a finite sum f/sub /c(p)= Sigma /sub 1//sup N/F/sub i/(p) of partial amplitudes', each F/sub i/(k) analytic in a certain domain F /sub i/ of the complex mass shell k/sub i//sup 2/=m/sub i//sup 2/. The mentioned real neighbourhood lies on the boundary of each F/sub i/. The above decomposition may fail to hold only at points p where any two incoming or any two outgoing four-momenta become parallel (thresholds). The number N as well as the shape of the domains F/sub i / depend on the number n and on the real neighbourhood considered. For a generic configuration p the intersection of the domains F/sub i/ is empty. When this does not happen, F/sub i/(p) is the boundar...

  7. The Lauricella functions and exact string scattering amplitudes

    International Nuclear Information System (INIS)

    Lai, Sheng-Hong; Lee, Jen-Chi; Yang, Yi

    2016-01-01

    We discover that the 26D open bosonic string scattering amplitudes (SSA) of three tachyons and one arbitrary string state can be expressed in terms of the D-type Lauricella functions with associated SL(K+3,ℂ) symmetry. As a result, SSA and symmetries or relations among SSA of different string states at various limits calculated previously can be rederived. These include the linear relations first conjectured by Gross http://dx.doi.org/10.1016/0370-2693(87)90355-8; http://dx.doi.org/10.1016/0550-3213(88)90390-2; http://dx.doi.org/10.1103/PhysRevLett.60.1229D.J. Gross and J.R. Ellis, Strings at superplanckian energies: in search of the string symmetry, Phil. Trans. Roy. Soc. Lond. A 329 (1989) 401. http://dx.doi.org/10.1016/0550-3213(89)90435-5 and later corrected and proved in http://dx.doi.org/10.1016/j.physletb.2005.02.034; http://arxiv.org/abs/hep-th/0303012; http://dx.doi.org/10.1016/j.nuclphysb.2004.04.022; http://dx.doi.org/10.1016/j.nuclphysb.2004.11.032; http://dx.doi.org/10.1103/PhysRevLett.96.171601; http://dx.doi.org/10.1016/j.nuclphysb.2005.07.018; http://dx.doi.org/10.1016/j.nuclphysb.2005.12.025 in the hard scattering limit, the recurrence relations in the Regge scattering limit with associated SL(5,ℂ) symmetry http://dx.doi.org/10.1088/1126-6708/2009/06/028; http://dx.doi.org/10.1007/JHEP04(2013)082; http://dx.doi.org/10.1016/j.physletb.2014.11.017 and the extended recurrence relations in the nonrelativistic scattering limit with associated SL(4,ℂ) symmetry http://dx.doi.org/10.1007/JHEP05(2016)186 discovered recently. Finally, as an application, we calculate a new recurrence relation of SSA which is valid for all energies.

  8. Form factors and scattering amplitudes in N=4 SYM in dimensional and massive regularizations

    Energy Technology Data Exchange (ETDEWEB)

    Henn, Johannes M. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; California Univ., Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics; Moch, Sven [California Univ., Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Naculich, Stephen G. [California Univ., Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics; Bowdoin College, Brunswick, ME (United States). Dept. of Physics

    2011-09-15

    The IR-divergent scattering amplitudes of N=4 supersymmetric Yang-Mills theory can be regulated in a variety of ways, including dimensional regularization and massive (or Higgs) regularization. The IR-finite part of an amplitude in different regularizations generally differs by an additive constant at each loop order, due to the ambiguity in separating finite and divergent contributions. We give a prescription for defining an unambiguous, regulator-independent finite part of the amplitude by factoring off a product of IR-divergent ''wedge'' functions. For the cases of dimensional regularization and the common-mass Higgs regulator, we define the wedge function in terms of a form factor, and demonstrate the regularization independence of the n-point amplitude through two loops. We also deduce the form of the wedge function for the more general differential-mass Higgs regulator, although we lack an explicit operator definition in this case. Finally, using extended dual conformal symmetry, we demonstrate the link between the differential-mass wedge function and the anomalous dual conformal Ward identity for the finite part of the scattering amplitude. (orig.)

  9. Form factors and scattering amplitudes in N=4 SYM in dimensional and massive regularizations

    International Nuclear Information System (INIS)

    Henn, Johannes M.; Naculich, Stephen G.; Bowdoin College, Brunswick, ME

    2011-09-01

    The IR-divergent scattering amplitudes of N=4 supersymmetric Yang-Mills theory can be regulated in a variety of ways, including dimensional regularization and massive (or Higgs) regularization. The IR-finite part of an amplitude in different regularizations generally differs by an additive constant at each loop order, due to the ambiguity in separating finite and divergent contributions. We give a prescription for defining an unambiguous, regulator-independent finite part of the amplitude by factoring off a product of IR-divergent ''wedge'' functions. For the cases of dimensional regularization and the common-mass Higgs regulator, we define the wedge function in terms of a form factor, and demonstrate the regularization independence of the n-point amplitude through two loops. We also deduce the form of the wedge function for the more general differential-mass Higgs regulator, although we lack an explicit operator definition in this case. Finally, using extended dual conformal symmetry, we demonstrate the link between the differential-mass wedge function and the anomalous dual conformal Ward identity for the finite part of the scattering amplitude. (orig.)

  10. Scattering amplitudes over finite fields and multivariate functional reconstruction

    International Nuclear Information System (INIS)

    Peraro, Tiziano

    2016-01-01

    Several problems in computer algebra can be efficiently solved by reducing them to calculations over finite fields. In this paper, we describe an algorithm for the reconstruction of multivariate polynomials and rational functions from their evaluation over finite fields. Calculations over finite fields can in turn be efficiently performed using machine-size integers in statically-typed languages. We then discuss the application of the algorithm to several techniques related to the computation of scattering amplitudes, such as the four- and six-dimensional spinor-helicity formalism, tree-level recursion relations, and multi-loop integrand reduction via generalized unitarity. The method has good efficiency and scales well with the number of variables and the complexity of the problem. As an example combining these techniques, we present the calculation of full analytic expressions for the two-loop five-point on-shell integrands of the maximal cuts of the planar penta-box and the non-planar double-pentagon topologies in Yang-Mills theory, for a complete set of independent helicity configurations.

  11. Scattering amplitudes over finite fields and multivariate functional reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Peraro, Tiziano [Higgs Centre for Theoretical Physics,School of Physics and Astronomy, The University of Edinburgh,James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD (United Kingdom)

    2016-12-07

    Several problems in computer algebra can be efficiently solved by reducing them to calculations over finite fields. In this paper, we describe an algorithm for the reconstruction of multivariate polynomials and rational functions from their evaluation over finite fields. Calculations over finite fields can in turn be efficiently performed using machine-size integers in statically-typed languages. We then discuss the application of the algorithm to several techniques related to the computation of scattering amplitudes, such as the four- and six-dimensional spinor-helicity formalism, tree-level recursion relations, and multi-loop integrand reduction via generalized unitarity. The method has good efficiency and scales well with the number of variables and the complexity of the problem. As an example combining these techniques, we present the calculation of full analytic expressions for the two-loop five-point on-shell integrands of the maximal cuts of the planar penta-box and the non-planar double-pentagon topologies in Yang-Mills theory, for a complete set of independent helicity configurations.

  12. Corrections to the box diagram amplitude due to kaon mass

    International Nuclear Information System (INIS)

    Datta, A.; Kumbhakar, D.

    1985-08-01

    The K 0 -anti-K 0 mixing amplitude is calculated without using the standard zero external momentum approximation. The resulting corrections are numerically significant for the real part of the amplitude. In the imaginary part of the amplitude the effects of similar corrections are less important. Implications for Δmsub(k) and epsilon are discussed. (author)

  13. Amplitude correlations for inelastic proton scattering from 48Ti

    International Nuclear Information System (INIS)

    Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.

    1981-01-01

    The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 45 5/2 + resonances in 49 V. The reduced widths in each channel follow a Porter-Thomas distribution, but extremely large amplitude correlations are observed - for one pair of channel amplitudes the relative sign is positive for 43 of 45 resonances. These results provide the first direct test of the Krieger-Porter reduced width amplitude distribution. (orig.)

  14. Picture book of nucleon--nucleon scattering: amplitudes, models, double- and triple-spin observables

    International Nuclear Information System (INIS)

    Field, R.D.; Stevens, P.R.

    1975-01-01

    A comprehensive study of nucleon-nucleon scattering is presented with particular emphasis on the underlying amplitude structure. The five complex NN amplitudes are determined as a function of energy and momentum transfer from existing pp, anti pp, and np elastic scattering data and np and anti pp CHEX data. Some constraints determined from meson-baryon fits are imposed. The resulting amplitudes are used to make predictions of forthcoming double- and triple-spin measurements, and are also compared with the model amplitudes of Kane and Seidl. In addition, the usefulness of transversity amplitudes in NN scattering is discussed, the status of our present knowledge concerning them is examined, and model predictions of these amplitudes are displayed. The paper is presented in a ''picture book'' form so that the reader can get a good overview of NN scattering by studying the figures and reading the tables and figure captions

  15. Probing the phase of the elastic pp scattering amplitude with vortex proton beams

    International Nuclear Information System (INIS)

    Ivanov, I. P.

    2013-01-01

    We show that colliding vortex proton beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the scattering amplitude changes with the scattering angle. In elastic pp scattering, this will open a novel way to measure the parameter ρ(t) and probe the real part of the Pomeron.

  16. Probing the phase of the elastic pp scattering amplitude with vortex proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, I. P. [IFPA, Universite de Liege, Allee du 6 Aout 17, batiment B5a, 4000 Liege, Belgium Sobolev Institute of Mathematics, Koptyug avenue 4, 630090, Novosibirsk (Russian Federation)

    2013-04-15

    We show that colliding vortex proton beams instead of (approximate) plane waves can lead to a direct measurement of how the overall phase of the scattering amplitude changes with the scattering angle. In elastic pp scattering, this will open a novel way to measure the parameter {rho}(t) and probe the real part of the Pomeron.

  17. Comments on gluon 6-point scattering amplitudes in N = 4 SYM at strong coupling

    International Nuclear Information System (INIS)

    Astefanesei, Dumitru; Dobashi, Suguru; Ito, Katsushi; Nastase, Horatiu

    2007-01-01

    We use the AdS-CFT prescription of Alday and Maldacena [1] to analyze gluon 6-point scattering amplitudes at strong coupling in N = 4 SYM. By cutting and gluing we obtain AdS 6-point amplitudes that contain extra boundary conditions and come close to matching the field theory results. We interpret them as parts of the field theory amplitudes, containing only certain diagrams. We also analyze the collinear limits of 6- and 5-point amplitudes and discuss the results

  18. High energy asymptotics of the scattering amplitude for the ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Keywords. Scattering matrix; asymptotic expansion; high energy; diagonal singula- ..... (see subsection 2 of § 3) with functions of the generator of dilations. A = 1. 2 d ..... ness in quantum scattering theory, Ann. Inst. Henri Poincaré, Phys. Théor.

  19. Analytical properties and behaviour of scattering amplitude at high energies in the localizable quantum field theory

    International Nuclear Information System (INIS)

    Lazur, V.Yu.; Khimich, I.V.

    1977-01-01

    Analytical properties of the elastic πN-scattering amplitude in in the cos THETA are proved in the Lehmann ellipse. The instrument for establishing analytical properties of the scattering amplitude in the cos THETA is the Jost-Lehmann-Dyson integral representation proved in terms of the localizable quantum field theory containing the strictly localizable theory and theory of moderate growth as particular cases. On this basis the Greenberg-Low restriction is obtained in frames of this class theories for the πN-scattering amplitude. This result gives a possibility to prove the ordinary dispersion relations with a finite number of subtraction in frames of the localizable quantum field theory

  20. The dispersion relation for the forward elastic electron-atom scattering amplitude

    International Nuclear Information System (INIS)

    Amusia, M.Y.

    1978-01-01

    The analytical properties of forward elastic electron-atom scattering amplitude are discussed. It is noted that the occurrence of exchange between the incoming and atomic electrons leads to the appearance of a number of singularities on the negative real axis in the complex energy plane. The conclusion is drawn that the dispersion relation for the forward electron-atom scattering amplitude should also include an integration over the negative energy from - I to - infinity, where I is the ionization potential. (author)

  1. Corrections to the leading eikonal amplitude for high-energy scattering and quasipotential approach

    International Nuclear Information System (INIS)

    Nguyen Suan Hani; Nguyen Duy Hung

    2003-12-01

    Asymptotic behaviour of the scattering amplitude for two scalar particle at high energy and fixed momentum transfers is reconsidered in quantum field theory. In the framework of the quasipotential approach and the modified perturbation theory a systematic scheme of finding the leading eikonal scattering amplitudes and its corrections is developed and constructed. The connection between the solutions obtained by quasipotential and functional approaches is also discussed. (author)

  2. Tune-shift with amplitude due to nonlinear kinematic effect

    CERN Document Server

    Wan, W

    1999-01-01

    Tracking studies of the Muon Collider 50 on 50 GeV collider ring show that the on-momentum dynamic aperture is limited to around 10 sigma even with the chromaticity sextupoles turned off. Numerical results from the normal form algorithm show that the tune-shift with amplitude is surprisingly large. Both analytical and numerical results are presented to show that nonlinear kinematic effect originated from the large angles of particles in the interaction region is responsible for the large tune-shift which in turn limits the dynamic aperture. A comparative study of the LHC collider ring is also presented to demonstrate the difference between the two machines. (14 refs).

  3. Ward Identity and Scattering Amplitudes for Nonlinear Sigma Models

    Science.gov (United States)

    Low, Ian; Yin, Zhewei

    2018-02-01

    We present a Ward identity for nonlinear sigma models using generalized nonlinear shift symmetries, without introducing current algebra or coset space. The Ward identity constrains correlation functions of the sigma model such that the Adler's zero is guaranteed for S -matrix elements, and gives rise to a subleading single soft theorem that is valid at the quantum level and to all orders in the Goldstone decay constant. For tree amplitudes, the Ward identity leads to a novel Berends-Giele recursion relation as well as an explicit form of the subleading single soft factor. Furthermore, interactions of the cubic biadjoint scalar theory associated with the single soft limit, which was previously discovered using the Cachazo-He-Yuan representation of tree amplitudes, can be seen to emerge from matrix elements of conserved currents corresponding to the generalized shift symmetry.

  4. Off-shell two-particle scattering amplitude in the P-matrix approach

    International Nuclear Information System (INIS)

    Babenko, V.A.; Petrov, N.M.

    1988-01-01

    A generalization of the P-matrix approach which makes it possible to describe the interaction of two particles off the energy shell is proposed. Explicit separation in the wave function of a part corresponding to free motion yields a compact expression for the off-shell scattering amplitude and gives directly a method for separable expansion of the amplitude

  5. Equality of some integrals from real and imaginary parts of a scattering amplitude

    International Nuclear Information System (INIS)

    Vernov, Yu.S.; Konovalov, A.V.; Mnatsakanova, M.N.

    1984-01-01

    Relation between the behaviour of real and imaginary parts of a forward elastic scattering amplitude is investigated on the basis of analyticity and crossing symmetry. Possibility for the generalization of this equality also for symmetric amplitude resulted from dispersion relations was considered. It is noted that the investigation performed is true for any function complying with the dispersion relation, for example, for polarization operator

  6. Multi-Regge amplitudes for bremsstrahlung in e+e- backward scattering

    International Nuclear Information System (INIS)

    Ermolaev, B.I.; Lipatov, L.N.

    1988-01-01

    Using the method of factorization, equations are obtained for the inelastic on-shell amplitudes describing the asymptotic behavior of e + e - backward scattering with emission of bremsstrahlung photons in the doubly logarithmic approximation. Explicit expressions are found for these amplitudes in the case in which the photons are emitted with multi-Regge kinematics

  7. Topics in Nonsupersymmetric Scattering Amplitudes in Gauge and Gravity Theories

    Science.gov (United States)

    Nohle, Joshua David

    In Chapters 1 and 2, we introduce and review the duality between color and kinematics in Yang-Mills theory uncovered by Bern, Carrasco and Johansson (BCJ). In Chapter 3, we provide evidence in favor of the conjectured duality between color and kinematics for the case of nonsupersymmetric pure Yang-Mills amplitudes by constructing a form of the one-loop four-point amplitude of this theory that makes the duality manifest. Our construction is valid in any dimension. We also describe a duality-satisfying representation for the two-loop four-point amplitude with identical four-dimensional external helicities. We use these results to obtain corresponding gravity integrands for a theory containing a graviton, dilaton, and antisymmetric tensor, simply by replacing color factors with specified diagram numerators. Using this, we give explicit forms of ultraviolet divergences at one loop in four, six, and eight dimensions, and at two loops in four dimensions. In Chapter 4, we extend the four-point one-loop nonsupersymmetric pure Yang-Mills discussion of Chapter 3 to include fermions and scalars circulating in the loop with all external gluons. This gives another nontrivial loop-level example showing that the duality between color and kinematics holds in nonsupersymmetric gauge theory. The construction is valid in any spacetime dimension and written in terms of formal polarization vectors. We also convert these expressions into a four-dimensional form with explicit external helicity states. Using this, we compare our results to one-loop duality-satisfying amplitudes that are already present in literature. In Chapter 5, we switch from the topic of color-kinematics duality to discuss the recently renewed interest in the soft behavior of gravitons and gluons. Specifically, we discuss the subleading low-energy behavior. Cachazo and Strominger recently proposed an extension of the soft-graviton theorem found by Weinberg. In addition, they proved the validity of their extension at

  8. Renormalization group and relations between scattering amplitudes in a theory with different mass scales

    International Nuclear Information System (INIS)

    Gulov, A.V.; Skalozub, V.V.

    2000-01-01

    In the Yukawa model with two different mass scales the renormalization group equation is used to obtain relations between scattering amplitudes at low energies. Considering fermion-fermion scattering as an example, a basic one-loop renormalization group relation is derived which gives possibility to reduce the problem to the scattering of light particles on the external field substituting a heavy virtual state. Applications of the results to problem of searching new physics beyond the Standard Model are discussed [ru

  9. High-Energy String Scattering Amplitudes and Signless Stirling Number Identity

    Directory of Open Access Journals (Sweden)

    Jen-Chi Lee

    2012-07-01

    Full Text Available We give a complete proof of a set of identities (7 proposed recently from calculation of high-energy string scattering amplitudes. These identities allow one to extract ratios among high-energy string scattering amplitudes in the fixed angle regime from high-energy amplitudes in the Regge regime. The proof is based on a signless Stirling number identity in combinatorial theory. The results are valid for arbitrary real values L rather than only for L=0,1 proved previously. The identities for non-integer real value L were recently shown to be realized in high-energy compactified string scattering amplitudes [He S., Lee J.C., Yang Y., arXiv:1012.3158]. The parameter L is related to the mass level of an excited string state and can take non-integer values for Kaluza-Klein modes.

  10. Scattering amplitudes to all orders in meson exchange

    International Nuclear Information System (INIS)

    Silbar, R.R.; Mattis, M.P.

    1990-01-01

    As the number of colors in QCD, N C , becomes large, it is possible to sum up all meson-exchange contributions, however arbitrarily complicated, to meson-baryon and baryon-baryon scattering. A semi-classical structure for the two-flavor theory emerges, in close correspondence to vector-meson-augmented Skyrme models. In this limit, baryons act as extended static sources for the classical meson fields. This leads to non-linear differential equations for the classical meson fields which can be solved numerically for static radial (hedgehog-like) solutions. The non-linear terms in the equations of motion for the quantized meson fields can then be simplified, to leading order in 1/N C , by replacing all factors of the meson field but one by the previously-found classical field. This results in linear, Schroedinger-like equations, which are easily solved. For the meson-baryon case the solution can be subsequently analyzed to obtain the phase shifts for the scattering and, from these, the baryon resonance spectrum of the model. As the warm-up, we have carried out this calculation for the simple case of σ mesons only, finding sensible results. 8 refs., 3 figs

  11. N=4 Scattering Amplitudes and the Deformed Graßmannian

    CERN Document Server

    Ferro, Livia; Staudacher, Matthias

    2014-01-01

    Some time ago the general tree-level scattering amplitudes of N=4 Super Yang-Mills theory were expressed as certain Grassmannian contour integrals. These remarkable formulas allow to clearly expose the super-conformal, dual super-conformal, and Yangian symmetries of the amplitudes. Using ideas from integrability it was recently shown that the building blocks of the amplitudes permit a natural multi-parameter deformation. However, this approach had been criticized by the observation that it seemed impossible to reassemble the building blocks into Yangian-invariant deformed non-MHV amplitudes. In this note we demonstrate that the deformations may be succinctly summarized by a simple modification of the measure of the Grassmannian integrals, leading to a Yangian-invariant deformation of the general tree-level amplitudes. Interestingly, the deformed building-blocks appear as residues of poles in the spectral parameter planes. Given that the contour integrals also contain information on the amplitudes at loop-leve...

  12. Phase variation of nucleon-nucleon amplitude for proton-12C elastic scattering

    International Nuclear Information System (INIS)

    Deng Yibing; Wang Shilai; Yin Gaofang

    2006-01-01

    Franco and Yin studied for α- 4 He, 3 He, 2 He, 1 He elastic-scattering by using the phase of the nucleon-nucleon elastic-scattering amplitude varies with momentum transfer in the framework of Glauber multiple scattering theory at intermediate energy. The phase variation leads to large changes in the differential cross sections, and brings the Glauber theory into agreement with experimental data. Later Lombard and Maillet is based on the suggestion by Franco and Yin studied for the p- 4 He elastic-scattering in the framework of Glauber theory, and found this phase to be actually important for the description of spin observables. Recently Wang Shilai and Deng Yibing et al studied for the p- 4 He elastic-scattering in the framework of KMT multiple scattering theory at intermediate energy, and found this phase lead to differential cross sections and polarization, which are in better agreement with experimental data. This paper is based on the suggestion by Franco and Yin that the phase of the nucleon-nucleon scattering amplitude should vary with momentum transfer. The proton elastic scattering on 12 C is studied in the KMT multiple scattering theory with microscopic momentum space first term optical potential. The Coulomb interactions are taken into account in our calculation. The theoretical calculation results show that the phase leads to differential cross section and polarization are in better agreement with experimental data. In conclusion this phase is actually important in the framework of KMT theory. (authors)

  13. Sum rules for the real parts of nonforward current-particle scattering amplitudes

    International Nuclear Information System (INIS)

    Abdel-Rahman, A.M.M.

    1976-01-01

    Extending previous work, using Taha's refined infinite-momentum method, new sum rules for the real parts of nonforward current-particle scattering amplitudes are derived. The sum rules are based on covariance, casuality, scaling, equal-time algebra and unsubtracted dispersion relations for the amplitudes. A comparison with the corresponding light-cone approach is made, and it is shown that the light-cone sum rules would also follow from the assumptions underlying the present work

  14. Analysis of pp and pp-bar elastic scattering amplitudes at high energies

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, E.; Kodama, T.; Kohara, A.K. [Universidade Federal do Rio de Janeiro (IF/UFRJ), RJ (Brazil). Inst. de Fisica

    2012-07-01

    Full text: A careful analysis of high energies elastic scattering data at 7 TeV for pp, 1800 - 1950 GeV for pp-bar and 540 -541 GeV for pp-bar in terms of its amplitudes has been performed as natural extension of previous analysis for lower energies. The disentanglement of the real and imaginary parts is written consistently with constraints from dispersion relations for amplitudes and for slopes, and also satisfying the universal asymptotic behavior for large |t| values due to the three gluon Exchange process. Values for the imaginary and real slopes and for the total cross section at 7 TeV, 1800-1950 GeV and 540-541 GeV are presented, and the shape of the differential cross section at 14 TeV, with a dip/bump structure more marked and at a smaller values of |t| is predicted. It is predicted that future measurements at large |t| will be connected smoothly with the perturbative tail observed in the interval 5.5 to 14.2 GeV{sup 2} at lower energies and that a marked dip would be observed in pp-bar scattering near this tail range. It is stressed for the consistent description of elastic pp and pp-bar data and pointed out the importance of the future measurements in the Coulomb interference range and in the transition range to the perturbative tail where the perturbative and non-perturbative effects appears together. (author)

  15. Ambiguities of the phase analysis of the proton-proton scattering amplitude

    International Nuclear Information System (INIS)

    Grebenyuk, O.G.; Shklyarevskij, G.M.

    1980-01-01

    Ambiguities of the phase analysis of the proton-proton scattering amplitude are analysed. It is shown that for five measurements of polarization parameters sets there are ambiguities similar to the Gersten ambiguities in the phase analysis of πN scattering. A problem on additional experiments needed to eliminate these ambiguities is investigated. It is shown that for this purpose it suffices to measure three total cross sections with polarized and nonpolarized protons, thus determining the imaginary parts of amplitudes at THETA=0 and polarization parameters

  16. Calculation of the Full Scattering Amplitude without Partial Wave Decomposition II: Inclusion of Exchange

    Science.gov (United States)

    Shertzer, Janine; Temkin, A.

    2003-01-01

    As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE), which can be reduced to a 2d partial differential equation (pde), was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation, which is reducible to a pair of coupled pde's. The resultant scattering amplitudes, both singlet and triplet, calculated as a function of energy are in excellent agreement with converged partial wave results.

  17. Calculation of the Full Scattering Amplitude without Partial Wave Decomposition II

    Science.gov (United States)

    Shertzer, J.; Temkin, A.

    2003-01-01

    As is well known, the full scattering amplitude can be expressed as an integral involving the complete scattering wave function. We have shown that the integral can be simplified and used in a practical way. Initial application to electron-hydrogen scattering without exchange was highly successful. The Schrodinger equation (SE) can be reduced to a 2d partial differential equation (pde), and was solved using the finite element method. We have now included exchange by solving the resultant SE, in the static exchange approximation. The resultant equation can be reduced to a pair of coupled pde's, to which the finite element method can still be applied. The resultant scattering amplitudes, both singlet and triplet, as a function of angle can be calculated for various energies. The results are in excellent agreement with converged partial wave results.

  18. Amplitudes and observables in pp elastic scattering at {radical}(s)=7 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Kohara, A.K.; Ferreira, E. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, C.P. 68528, Rio de Janeiro, RJ (Brazil); Kodama, T. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, C.P. 68528, Rio de Janeiro, RJ (Brazil); EMMI at FIAS-Frankfurt Institute for Advanced Study, Frankfurt am Main (Germany)

    2013-02-15

    A precise analysis of the pp elastic scattering data at 7 TeV in terms of its amplitudes is performed as an extension of previous studies for lower energies. Slopes B{sub R} and B{sub I} of the real and imaginary amplitudes are independent quantities, and a proper expression for the Coulomb phase is used. The real and imaginary amplitudes are fully disentangled, consistently with forward dispersion relations for amplitudes and for slopes. We present analytic expressions for the amplitudes that cover all t range completely, while values of total cross section {sigma}, ratio {rho}, B{sub I}, and B{sub R} enter consistently to describe forward scattering. It is stressed that the identification of the amplitudes is an essential step for the description of elastic scattering, and pointed out the importance of the experimental investigation of the transition range from non-perturbative to perturbative dynamics, which may confirm the three gluon exchange mechanism observed at lower energies. (orig.)

  19. Real part of amplitude and hadron scattering cross section at superhigh energies

    International Nuclear Information System (INIS)

    Troshin, S.M.; Tyurin, N.E.

    1987-01-01

    New data on measuring the ratio of the real to imaginary part of the forward scattering amplitude: ρ pp-bar (√s=546 GeV)=0.24±0.04 have been considered. This result is shown to agree with the behaviour of σ tot (s), predicted by the U-matrix model. A possibility of transition to antishadow scattering mode at superhigh energies is stated

  20. Quality factor due to roughness scattering of shear horizontal surface acoustic waves in nanoresonators

    NARCIS (Netherlands)

    Palasantzas, G.

    2008-01-01

    In this work we study the quality factor associated with dissipation due to scattering of shear horizontal surface acoustic waves by random self-affine roughness. It is shown that the quality factor is strongly influenced by both the surface roughness exponent H and the roughness amplitude w to

  1. Spectator scattering at NLO in non-leptonic B decays: Leading penguin amplitudes

    International Nuclear Information System (INIS)

    Beneke, M.; Jaeger, S.

    2007-01-01

    We complete the computation of the 1-loop (α s 2 ) corrections to hard spectator scattering in non-leptonic B decays at leading power in Λ/m b by evaluating the penguin amplitudes. This extends the knowledge of these next-to-next-to-leading-order contributions in the QCD factorization formula for B decays to a much wider class of final states, including all pseudoscalar-pseudoscalar, pseudoscalar-vector, and longitudinally polarized vector-vector final states, except final states with η or η ' mesons. The new 1-loop correction is significant for the colour-suppressed amplitudes, but turns out to be strongly suppressed for the leading QCD penguin amplitude α 4 p . We provide numerical values of the phenomenological P/T and C/T amplitude ratios for the ππ, πρ and ρρ final states, and discuss corrections to several relations between electroweak penguin and tree amplitudes

  2. Dispersion relation for elastic electron-hydrogen atom forward scattering amplitude

    International Nuclear Information System (INIS)

    Kuchiev, M.Yu.; Amusia, M.Ya.

    1978-01-01

    The elastic e+H forward scattering amplitude is an analytical function in the complex energy E plane and has two cuts on the real axis: 0 < E < infinity and -infinity < E < -B, B being the hydrogen ionization potential. The e+H dispersion relation contains two integrals over the right and left cuts. (Auth.)

  3. Remarks on the high-energy behavior of string scattering amplitudes in warped spacetimes. II

    International Nuclear Information System (INIS)

    Andreev, Oleg

    2005-01-01

    We study the Regge limit of string amplitudes within the model of Polchinski-Strassler for string scattering in warped spacetimes. We also present some numerical estimations of the Regge slopes and intercepts. It is quite remarkable that the real values of those are inside a range of ours

  4. Scattering amplitudes on the Coulomb branch of N=4 super Yang-Mills

    International Nuclear Information System (INIS)

    Henn, J.M.

    2010-01-01

    We discuss planar scattering amplitudes on the Coulomb branch of N=4 super Yang-Mills. The vacuum expectation values on the Coulomb branch can be used to regulate infrared divergences. We argue that this has a number of conceptual as well as practical advantages over dimensional regularisation.

  5. On the loop-loop scattering amplitudes in Abelian and non-Abelian gauge theories

    International Nuclear Information System (INIS)

    Meggiolaro, Enrico

    2005-01-01

    The high-energy elastic scattering amplitude of two colour-singlet qq-bar pairs is governed by the correlation function of two Wilson loops, which follow the classical straight lines for quark (antiquark) trajectories. This quantity is expected to be free of IR divergences, differently from what happens for the parton-parton elastic scattering amplitude, described, in the high-energy limit, by the expectation value of two Wilson lines. We shall explicitly test this IR finiteness by a direct non-perturbative computation of the loop-loop scattering amplitudes in the (pedagogic, but surely physically interesting) case of quenched QED. The results obtained for the Abelian case will be generalized to the case of a non-Abelian gauge theory with Nc colours, but stopping to the order O(g4) in perturbation theory. In connection with the above-mentioned IR finiteness, we shall also discuss some analytic properties of the loop-loop scattering amplitudes in both Abelian and non-Abelian gauge theories, when going from Minkowskian to Euclidean theory, which can be relevant to the still unsolved problem of the s-dependence of hadron-hadron total cross-sections

  6. Recursion rules for scattering amplitudes in non-Abelian gauge theories

    International Nuclear Information System (INIS)

    Kim, C.; Nair, V.P.

    1997-01-01

    We present a functional derivation of recursion rules for scattering amplitudes in a non-Abelian gauge theory in a form valid to arbitrary loop order. The tree-level and one-loop recursion rules are explicitly displayed. copyright 1997 The American Physical Society

  7. Construction of Non-Perturbative, Unitary Particle-Antiparticle Amplitudes for Finite Particle Number Scattering Formalisms

    International Nuclear Information System (INIS)

    Lindesay, James V

    2002-01-01

    Starting from a unitary, Lorentz invariant two-particle scattering amplitude, we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy shell. Further, amplitudes are constructed using the invariant parameters which are appropriate to use as driving terms in the multi-particle, multichannel nonperturbative, cluster decomposable, relativistic scattering equations of the Faddeev-type integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes. It is therefore anticipated that when so employed, the resulting multi-channel solutions will also be unitary. The process preserves the usual particle-antiparticle symmetries. To illustrate this process, we construct a J=0 scattering length model chosen for simplicity. We also exhibit a class of physical models which contain a finite quantum mass parameter and are Lorentz invariant. These are constructed to reduce in the appropriate limits, and with the proper choice of value and sign of the interaction parameter, to the asymptotic solution of the nonrelativistic Coulomb problem, including the forward scattering singularity , the essential singularity in the phase, and the Bohr bound-state spectrum

  8. A novel sampling method for multiple multiscale targets from scattering amplitudes at a fixed frequency

    Science.gov (United States)

    Liu, Xiaodong

    2017-08-01

    A sampling method by using scattering amplitude is proposed for shape and location reconstruction in inverse acoustic scattering problems. Only matrix multiplication is involved in the computation, thus the novel sampling method is very easy and simple to implement. With the help of the factorization of the far field operator, we establish an inf-criterion for characterization of underlying scatterers. This result is then used to give a lower bound of the proposed indicator functional for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functional decays like the bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functional continuously depends on the scattering amplitude, this further implies that the novel sampling method is extremely stable with respect to errors in the data. Different to the classical sampling method such as the linear sampling method or the factorization method, from the numerical point of view, the novel indicator takes its maximum near the boundary of the underlying target and decays like the bessel functions as the sampling points go away from the boundary. The numerical simulations also show that the proposed sampling method can deal with multiple multiscale case, even the different components are close to each other.

  9. Spectral parameters for scattering amplitudes in N=4 super Yang-Mills theory

    International Nuclear Information System (INIS)

    Ferro, Livia; Łukowski, Tomasz; Meneghelli, Carlo; Plefka, Jan; Staudacher, Matthias

    2014-01-01

    Planar N=4 Super Yang-Mills theory appears to be a quantum integrable four-dimensional conformal theory. This has been used to find equations believed to describe its exact spectrum of anomalous dimensions. Integrability seemingly also extends to the planar space-time scattering amplitudes of the N=4 model, which show strong signs of Yangian invariance. However, in contradistinction to the spectral problem, this has not yet led to equations determining the exact amplitudes. We propose that the missing element is the spectral parameter, ubiquitous in integrable models. We show that it may indeed be included into recent on-shell approaches to scattering amplitude integrands, providing a natural deformation of the latter. Under some constraints, Yangian symmetry is preserved. Finally we speculate that the spectral parameter might also be the regulator of choice for controlling the infrared divergences appearing when integrating the integrands in exactly four dimensions

  10. Superconducting quasiparticle lifetimes due to spin-fluctuation scattering

    International Nuclear Information System (INIS)

    Quinlan, S.M.; Scalapino, D.J.; Bulut, N.

    1994-01-01

    Superconducting quasiparticle lifetimes associated with spin-fluctuation scattering are calculated. A Berk-Schrieffer interaction with an irreducible susceptibility given by a BCS form is used to model the quasiparticle damping due to spin fluctuations. Results are presented for both s-wave and d-wave gaps. Also, quasiparticle lifetimes due to impurity scattering are calculated for a d-wave superconductor

  11. Equivalence of meson scattering amplitudes in strong coupling lattice and flat space string theory

    Directory of Open Access Journals (Sweden)

    Adi Armoni

    2018-03-01

    Full Text Available We consider meson scattering in the framework of the lattice strong coupling expansion. In particular we derive an expression for the 4-point function of meson operators in the planar limit of scalar Chromodynamics. Interestingly, in the naive continuum limit the expression coincides with an independently known result, that of the worldline formalism. Moreover, it was argued by Makeenko and Olesen that (assuming confinement the resulting scattering amplitude in momentum space is the celebrated expression proposed by Veneziano several decades ago. This motivates us to also use holography in order to argue that the continuum expression for the scattering amplitude is related to the result obtained from flat space string theory. Our results hint that at strong coupling and large-Nc the naive continuum limit of the lattice formalism can be related to a flat space string theory.

  12. Equivalence of meson scattering amplitudes in strong coupling lattice and flat space string theory

    Science.gov (United States)

    Armoni, Adi; Ireson, Edwin; Vadacchino, Davide

    2018-03-01

    We consider meson scattering in the framework of the lattice strong coupling expansion. In particular we derive an expression for the 4-point function of meson operators in the planar limit of scalar Chromodynamics. Interestingly, in the naive continuum limit the expression coincides with an independently known result, that of the worldline formalism. Moreover, it was argued by Makeenko and Olesen that (assuming confinement) the resulting scattering amplitude in momentum space is the celebrated expression proposed by Veneziano several decades ago. This motivates us to also use holography in order to argue that the continuum expression for the scattering amplitude is related to the result obtained from flat space string theory. Our results hint that at strong coupling and large-Nc the naive continuum limit of the lattice formalism can be related to a flat space string theory.

  13. Low-energy theorems for Compton scattering up to order e/sup 4/. [Scattering amplitudes dispersion relations

    Energy Technology Data Exchange (ETDEWEB)

    Pippig, G

    1975-01-01

    Taking the Compton scattering of pions and deuterons as an example it is shown that low-energy theorems which are valid for the order e/sup 2/ are also valid for the next higher order of electromagnetic interactions. The imaginary component of the scattering amplitude was exactly calculated for the energy of incident photons in the order e/sup 4/ up to the desired one, whereas the real component was obtained from dispersion relations. It is proved that the results derived from the dispersion theory of strong interactions are equivalent to those obtained from quantum electrodynamics for spin 0 and spin 1, respectively.

  14. Calculating Rayleigh scattering amplitudes from 100 eV to 10 MeV

    International Nuclear Information System (INIS)

    Parker, J.C.; Reynaud, G.W.; Botto, D.J.; Pratt, R.H.

    1979-01-01

    An attempt is made to explain how to calculate the contribution to elastic photon-atom scattering due to Rayleigh scattering (the scattering off bound electrons) in the photon energy range 100 eV less than or equal to W less than or equal to 10 MeV. All intermediate calculations are described, including the calculation of the potential, bound state wave functions, matrix elements, and final cross sections. 12 references

  15. N=4 scattering amplitudes and the deformed Graßmannian

    International Nuclear Information System (INIS)

    Ferro, Livia; Łukowski, Tomasz; Staudacher, Matthias

    2014-01-01

    Some time ago the general tree-level scattering amplitudes of N=4 Super Yang–Mills theory were expressed as certain Graßmannian contour integrals. These remarkable formulas allow to clearly expose the super-conformal, dual super-conformal, and Yangian symmetries of the amplitudes. Using ideas from integrability it was recently shown that the building blocks of the amplitudes permit a natural multi-parameter deformation. However, this approach had been criticized by the observation that it seemed impossible to reassemble the building blocks into Yangian-invariant deformed non-MHV amplitudes. In this note we demonstrate that the deformations may be succinctly summarized by a simple modification of the measure of the Graßmannian integrals, leading to a Yangian-invariant deformation of the general tree-level amplitudes. Interestingly, the deformed building blocks appear as residues of poles in the spectral parameter planes. Given that the contour integrals also contain information on the amplitudes at loop-level, we expect the deformations to be useful there as well. In particular, applying meromorphicity arguments, they may be expected to regulate all notorious infrared divergences. We also point out relations to Gelfand hypergeometric functions and the quantum Knizhnik–Zamolodchikov equations

  16. High energy behaviour of the scattering amplitude in the presence of confined channels

    International Nuclear Information System (INIS)

    Gehlen, G.; Rittenberg, V.

    1977-09-01

    The two-channel potential scattering problem in three space-dimensions is considered in the case when one channel is permanently confined. Two examples of confining potentials are considered: the harmonic oscillator and the infinite well. The two cases give radically different results: for the infinite well there is no high energy limit; in the case of the harmonic oscillator the amplitude has properties similar to that of dual absorptive models. (orig.) [de

  17. Representation of the virtual Compton amplitude for polarized scattering in the generalized Bjorken region

    OpenAIRE

    Blümlein, J.; Gezer, B.; Robaschik, D.

    1999-01-01

    The Compton amplitude is calculated in terms of expectation values of light-ray quark operators. As a technical tool we apply the nonlocal light-cone expansion. Thereby we express the expectation value of the vector light-ray operator with the help of the expectation value of the corresponding scalar operator of twist 2. This allows important simplifications. In the limit of forward scattering the integral relations between the twist-2 contributions of the structure functions are implied dire...

  18. Radar transponder operation with compensation for distortion due to amplitude modulation

    Science.gov (United States)

    Ormesher, Richard C [Albuquerque, NM; Tise, Bertice L [Albuquerque, NM; Axline, Jr., Robert M.

    2011-01-04

    In radar transponder operation, a variably delayed gating signal is used to gate a received radar pulse and thereby produce a corresponding gated radar pulse for transmission back to the source of the received radar pulse. This compensates for signal distortion due to amplitude modulation on the retransmitted pulse.

  19. N=4 supersymmetric Yang Mills scattering amplitudes at high energies. The Regge cut contribution

    International Nuclear Information System (INIS)

    Bartels, J.; Sabio Vera, A.

    2008-07-01

    We further investigate, in N=4 supersymmetric Yang Mills theories, the high energy Regge behavior of six-point scattering amplitudes. In particular, for the new Regge cut contribution found in our previous paper, we compute in the leading logarithmic approximation (LLA) the energy spectrum of the BFKL equation in the color octet channel, and we calculate explicitly the two loop corrections to the discontinuities of the amplitudes for the transitions 2→4 and 3→3. We find an explicit solution of the BFKL equation for the octet channel for arbitrary momentum transfers and investigate the intercepts of the Regge singularities in this channel. As an important result we find that the universal collinear and infrared singularities of the BDS formula are not affected by this Regge-cut contribution. (orig.)

  20. Nonplanar on-shell diagrams and leading singularities of scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Baoyi; Cheung, Yeuk-Kwan E.; Li, Yunxuan; Xie, Ruofei; Xin, Yuan [Nanjing University, Department of Physics, Nanjing (China); Chen, Gang [Zhejiang Normal University, Department of Physics, Jinhua, Zhejiang (China); Nanjing University, Department of Physics, Nanjing (China)

    2017-02-15

    Bipartite on-shell diagrams are the latest tool in constructing scattering amplitudes. In this paper we prove that a Britto-Cachazo-Feng-Witten (BCFW) decomposable on-shell diagram process a rational top form if and only if the algebraic ideal comprised the geometrical constraints are shifted linearly during successive BCFW integrations. With a proper geometric interpretation of the constraints in the Grassmannian manifold, the rational top form integration contours can thus be obtained, and understood, in a straightforward way. All rational top form integrands of arbitrary higher loops leading singularities can therefore be derived recursively, as long as the corresponding on-shell diagram is BCFW decomposable. (orig.)

  1. Multichannel scattering amplitudes of microparticles in a quantum well with two-dimensional -potential

    International Nuclear Information System (INIS)

    Sedrakian, D.M.; Badalyan, D.H.; Sedrakian, L.R.

    2015-01-01

    Quasi-one-dimensional quantum particle scattering on two-dimensional δ-potential is considered. Analytical expressions for the amplitudes of the multi-channel transmission and reflection are given. The problem for the case when the number of channels is finite and equal N, and the particle falls on the potential moving through the channel l is solved. The case of a three channel scattering is studied in details. It is shown that under conditions k 2 → 0 and k 3 → 0 'overpopulation' of particles on the second and third channels occurs. The points of δ-potential location which provide a full 'overpopulation' of particles is also found

  2. Semiclassical asymptotics for the scattering amplitude in the presence of focal points at infinity

    Energy Technology Data Exchange (ETDEWEB)

    Hohberger, H.

    2006-10-16

    We consider scattering in R{sup n}, n{>=}2, described by the Schroedinger operator P(h)=-h{sup 2}{delta}+V, where V is a short-range potential. With the aid of Maslov theory, we give a geometrical formula for the semiclassical asymptotics as h{yields}0 of the scattering amplitude f({omega}{sub -},{omega}{sub +};{lambda},h) ({omega}{sub +}{ne}{omega}{sub -}) which remains valid in the presence of focal points at infinity (caustics). Crucial for this analysis are precise estimates on the asymptotics of the classical phase trajectories and the relationship between caustics in euclidean phase space and caustics at infinity. (orig.)

  3. Proton-Nucleus Elastic Cross Sections Using Two-Body In-Medium Scattering Amplitudes

    Science.gov (United States)

    Tripathi, R. K.; Wilson, John W.; Cucinotta, Francis A.

    2001-01-01

    Recently, a method was developed of extracting nucleon-nucleon (NN) cross sections in the medium directly from experiment. The in-medium NN cross sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the Langley Research Center. The ratio of the real to the imaginary part of the two-body scattering amplitude in the medium was investigated. These ratios are used in combination with the in-medium NN cross sections to calculate elastic proton-nucleus cross sections. The agreement is excellent with the available experimental data. These cross sections are needed for the radiation risk assessment of space missions.

  4. Scattering amplitude and bosonization duality in general Chern-Simons vector models

    Science.gov (United States)

    Yokoyama, Shuichi

    2016-09-01

    We present the exact large N calculus of four point functions in general Chern-Simons bosonic and fermionic vector models. Applying the LSZ formula to the four point function we determine the two body scattering amplitudes in these theories taking a special care for a non-analytic term to achieve unitarity in the singlet channel. We show that the S-matrix enjoys the bosonization duality, an unusual crossing relation and a non-relativistic reduction to Aharonov-Bohm scattering. We also argue that the S-matrix develops a pole in a certain range of coupling constants, which disappears in the range where the theory reduces to the Chern-Simons theory interacting with free fermions.

  5. Calculation of Scattering Amplitude Without Partial Analysis. II; Inclusion of Exchange

    Science.gov (United States)

    Temkin, Aaron; Shertzer, J.; Fisher, Richard R. (Technical Monitor)

    2002-01-01

    There was a method for calculating the whole scattering amplitude, f(Omega(sub k)), directly. The idea was to calculate the complete wave function Psi numerically, and use it in an integral expression for f, which can be reduced to a 2 dimensional quadrature. The original application was for e-H scattering without exchange. There the Schrodinger reduces a 2-d partial differential equation (pde), which was solved using the finite element method (FEM). Here we extend the method to the exchange approximation. The S.E. can be reduced to a pair of coupled pde's, which are again solved by the FEM. The formal expression for f(Omega(sub k)) consists two integrals, f+/- = f(sub d) +/- f(sub e); f(sub d) is formally the same integral as the no-exchange f. We have also succeeded in reducing f(sub e) to a 2-d integral. Results will be presented at the meeting.

  6. Spectral distortion due to scattered cold neutrons in beryllium filter

    International Nuclear Information System (INIS)

    Sakamoto, Yukio; Inoue, Kazuhiko

    1980-01-01

    Polycrystalline beryllium filters are used to discriminate the cold neutrons from the thermal neutrons with energies above Bragg cut-off energy. The cold neutron scattering cross section is very small, but the remaining cross section is not zero. Then the neutrons scattered once from the filter in the cold neutron energy region have chance of impinging on the outlet of filter. Those neutrons are almost upscattered and develop into thermal neutrons; thus the discriminated cold neutrons include a small spectral distortion due to the thermal neutrons. In the present work we have evaluated the effect on the cold neutron spectrum due to the repeatedly scattered and transmitted neutrons by using a Monte Carlo calculation method. (author)

  7. Dispersion relation for the 3. -->. 3 forward scattering amplitude and the generalized optical theorem. [Crossing properties, dispersion relations

    Energy Technology Data Exchange (ETDEWEB)

    Logunov, A A; Medvedev, B V; Mestvirishvili, M A; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Serpukhov. Inst. Fiziki Vysokikh Ehnergij

    1977-11-01

    Investigation of analytical structure of the three-particle forward scattering amplitude with respect to energy variable of one of particles is performed. The results obtained make it possible to draw the conclusions on crossing properties of the amplitude and to derive the generalized optical theorem relating the discontinuity of the amplitude to the distribution function of an inclusive process. For a special case when two of three particles are of zero mass, a dispersion relation is proved.

  8. Bipartite field theories: from D-brane probes to scattering amplitudes

    Science.gov (United States)

    Franco, Sebastián

    2012-11-01

    We introduce and initiate the investigation of a general class of 4d, {N}=1 quiver gauge theories whose Lagrangian is defined by a bipartite graph on a Riemann surface, with or without boundaries. We refer to such class of theories as Bipartite Field Theories (BFTs). BFTs underlie a wide spectrum of interesting physical systems, including: D3-branes probing toric Calabi-Yau 3-folds, their mirror configurations of D6-branes, cluster integrable systems in (0 + 1) dimensions and leading singularities in scattering amplitudes for {N}=4 SYM. While our discussion is fully general, we focus on models that are relevant for scattering amplitudes. We investigate the BFT perspective on graph modifications, the emergence of Calabi-Yau manifolds (which arise as the master and moduli spaces of BFTs), the translation between square moves in the graph and Seiberg duality and the identification of dual theories by means of the underlying Calabi-Yaus, the phenomenon of loop reduction and the interpretation of the boundary operator for cells in the positive Grassmannian as higgsing in the BFT. We develop a technique based on generalized Kasteleyn matrices that permits an efficient determination of the Calabi-Yau geometries associated to arbitrary graphs. Our techniques allow us to go beyond the planar limit by both increasing the number of boundaries of the graphs and the genus of the underlying Riemann surface. Our investigation suggests a central role for Calabi-Yau manifolds in the context of leading singularities, whose full scope is yet to be uncovered.

  9. Amplitude of Light Scattering by a Truncated Pyramid and Cone in the Rayleigh-Gans-Debye Approximation

    Directory of Open Access Journals (Sweden)

    Konstantin A. Shapovalov

    2013-01-01

    Full Text Available The article considers general approach to structured particle and particle system form factor calculation in the Rayleigh-Gans-Debye (RGD approximation. Using this approach, amplitude of light scattering by a truncated pyramid and cone formulas in RGD approximation are obtained. Light scattering indicator by a truncated pyramid and cone in the RGD approximation are calculated.

  10. Scattering amplitudes in N=2 Maxwell-Einstein and Yang-Mills/Einstein supergravity

    CERN Document Server

    Chiodaroli, Marco; Johansson, Henrik; Roiban, Radu

    2015-01-01

    We expose a double-copy structure in the scattering amplitudes of the generic Jordan family of N=2 Maxwell-Einstein and Yang-Mills/Einstein supergravity theories in four and five dimensions. The Maxwell-Einstein supergravity amplitudes are obtained through the color/kinematics duality as a product of two gauge-theory factors; one originating from pure N=2 super-Yang-Mills theory and the other from the dimensional reduction of a bosonic higher-dimensional pure Yang-Mills theory. We identify a specific symplectic frame in four dimensions for which the on-shell fields and amplitudes from the double-copy construction can be identified with the ones obtained from the supergravity Lagrangian and Feynman-rule computations. The Yang-Mills/Einstein supergravity theories are obtained by gauging a compact subgroup of the isometry group of their Maxwell-Einstein counterparts. For the generic Jordan family this process is identified with the introduction of cubic scalar couplings on the bosonic gauge-theory side, which th...

  11. Scattering amplitudes in N=2 Maxwell-Einstein and Yang-Mills/Einstein supergravity

    International Nuclear Information System (INIS)

    Chiodaroli, Marco; Günaydin, Murat; Johansson, Henrik; Roiban, Radu

    2015-01-01

    We expose a double-copy structure in the scattering amplitudes of the generic Jordan family of N=2 Maxwell-Einstein and Yang-Mills/Einstein supergravity theories in four and five dimensions. The Maxwell-Einstein supergravity amplitudes are obtained through the color/kinematics duality as a product of two gauge-theory factors; one originating from pure N=2 super-Yang-Mills theory and the other from the dimensional reduction of a bosonic higher-dimensional pure Yang-Mills theory. We identify a specific symplectic frame in four dimensions for which the on-shell fields and amplitudes from the double-copy construction can be identified with the ones obtained from the supergravity Lagrangian and Feynman-rule computations. The Yang-Mills/Einstein supergravity theories are obtained by gauging a compact subgroup of the isometry group of their Maxwell-Einstein counterparts. For the generic Jordan family this process is identified with the introduction of cubic scalar couplings on the bosonic gauge-theory side, which through the double copy are responsible for the non-abelian vector interactions in the supergravity theory. As a demonstration of the power of this structure, we present explicit computations at tree-level and one loop. The double-copy construction allows us to obtain compact expressions for the supergravity superamplitudes, which are naturally organized as polynomials in the gauge coupling constant.

  12. Elastic pp scattering in the Coulomb-nuclear interference region and low energy behaviour of p-barp scattering partial amplitudes

    International Nuclear Information System (INIS)

    Kudryavtsev, A.E.; Markushin, V.E.

    1985-01-01

    The experimental data on the low energy elastic p-barp scattering in the Coulomb-nuclear interference region and on the shift and width of the 1s level of p-barp-atom are analysed. The partial wave amplitudes for l=0.1 are extracted. The p-wave amplitude is in fair agreement with the atomic data for the 2p state and exhibits some energy structure. It is shown that the real-to-imaginary ratio of the p-barp forward elastic-scattering amplitude becomes negative in an energy interval just near p-barp-threshold

  13. Landau damping due to tune spreads in betatron amplitude and momentum

    International Nuclear Information System (INIS)

    Lee, S.Y.; Tran, P.; Weng, W.T.

    1989-01-01

    Due to the large space charge transverse impedance in a low energy synchrotron, the coherent tune shift causes the Landau damping to be ineffective in damping the transverse coherent motion. We analyze the effect of Landau damping that is caused by the tune spreads of the betatron amplitude (space charge and/or octupole) and momentum. We find that the Landau damping becomes more significant in our two dimensional analysis. 5 refs

  14. Response of ENSO amplitude to global warming in CESM large ensemble: uncertainty due to internal variability

    Science.gov (United States)

    Zheng, Xiao-Tong; Hui, Chang; Yeh, Sang-Wook

    2018-06-01

    El Niño-Southern Oscillation (ENSO) is the dominant mode of variability in the coupled ocean-atmospheric system. Future projections of ENSO change under global warming are highly uncertain among models. In this study, the effect of internal variability on ENSO amplitude change in future climate projections is investigated based on a 40-member ensemble from the Community Earth System Model Large Ensemble (CESM-LE) project. A large uncertainty is identified among ensemble members due to internal variability. The inter-member diversity is associated with a zonal dipole pattern of sea surface temperature (SST) change in the mean along the equator, which is similar to the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV) in the unforced control simulation. The uncertainty in CESM-LE is comparable in magnitude to that among models of the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting the contribution of internal variability to the intermodel uncertainty in ENSO amplitude change. However, the causations between changes in ENSO amplitude and the mean state are distinct between CESM-LE and CMIP5 ensemble. The CESM-LE results indicate that a large ensemble of 15 members is needed to separate the relative contributions to ENSO amplitude change over the twenty-first century between forced response and internal variability.

  15. NOTE ON TRAVEL TIME SHIFTS DUE TO AMPLITUDE MODULATION IN TIME-DISTANCE HELIOSEISMOLOGY MEASUREMENTS

    International Nuclear Information System (INIS)

    Nigam, R.; Kosovichev, A. G.

    2010-01-01

    Correct interpretation of acoustic travel times measured by time-distance helioseismology is essential to get an accurate understanding of the solar properties that are inferred from them. It has long been observed that sunspots suppress p-mode amplitude, but its implications on travel times have not been fully investigated so far. It has been found in test measurements using a 'masking' procedure, in which the solar Doppler signal in a localized quiet region of the Sun is artificially suppressed by a spatial function, and using numerical simulations that the amplitude modulations in combination with the phase-speed filtering may cause systematic shifts of acoustic travel times. To understand the properties of this procedure, we derive an analytical expression for the cross-covariance of a signal that has been modulated locally by a spatial function that has azimuthal symmetry and then filtered by a phase-speed filter typically used in time-distance helioseismology. Comparing this expression to the Gabor wavelet fitting formula without this effect, we find that there is a shift in the travel times that is introduced by the amplitude modulation. The analytical model presented in this paper can be useful also for interpretation of travel time measurements for the non-uniform distribution of oscillation amplitude due to observational effects.

  16. Variability of phase and amplitude fronts due to horizontal refraction in shallow water.

    Science.gov (United States)

    Katsnelson, Boris G; Grigorev, Valery A; Lynch, James F

    2018-01-01

    The variability of the interference pattern of a narrow-band sound signal in a shallow water waveguide in the horizontal plane in the presence of horizontal stratification, in particular due to linear internal waves, is studied. It is shown that lines of constant phase (a phase front) and lines of constant amplitude/envelope (an amplitude front) for each waveguide mode may have different directions in the spatial vicinity of the point of reception. The angle between them depends on the waveguide's parameters, the mode number, and the sound frequency. Theoretical estimates and data processing methodology for obtaining these angles from experimental data recorded by a horizontal line array are proposed. The behavior of the angles, which are obtained for two episodes from the Shallow Water 2006 (SW06) experiment, show agreement with the theory presented.

  17. Calculation of zero-norm states and reduction od stringy scattering amplitudes

    International Nuclear Information System (INIS)

    Lee Jen-Chi

    2005-01-01

    We give a simplified method to generate two types of zero-norm states in the old covariant first quantized (OCFQ) spectrum of open bosonic string. Zero-norm states up to the fourth massive level and general formulas of some zero-norm tensor states at arbitrary mass levels are calculated. On-shell Ward identities generated by zero-norm states and the factor-ization property of stringy vertex operators can then be used to argue that the string-tree scattering amplitudes of the degenerate lower spin propagating states are fixed by those of higher spin propagating states at each fixed mass level. This decoupling phenomenon is, in contrast to Gross's high-energy symmetries, valid to all energies. As examples, we explicitly demonstrate this stringy phenomenon up to fourth massive level (spin-five), which justifies the calculation of two other previous approaches based on the massive worldsheet sigma-model and Witten's string field theory (WSFT). (author)

  18. Use of analytical Born amplitude representation in studies of dispersion potentials and electron-atom scattering

    International Nuclear Information System (INIS)

    Carvalho, I.L. de.

    1985-01-01

    Two distinct problems have been studied using simplifield Born's Amplitude Analitical Expressions. The first problem deals with the dispersion energy between the constituent members of the systems He - Ne, - He and H 2 - H 2 . In the second problem second order Born Aproximation has been used for the Electron - Atom Inelastic Scattering for the transitions 1 1 S → 2 1 S and 1 1 S → 2 1 P of helium atom and 1 S → 1 s 2 ([3s' {1/2} sup(o) 1; M sub(j)>) of neon atom (in the case of neon we have used the coupling scheme proposed by Cowan and Andrew). The results obtained by us have been compared with the theoretical and experimental results available in the literature. (author) [pt

  19. 4D scattering amplitudes and asymptotic symmetries from 2D CFT

    Science.gov (United States)

    Cheung, Clifford; de la Fuente, Anton; Sundrum, Raman

    2017-01-01

    We reformulate the scattering amplitudes of 4D flat space gauge theory and gravity in the language of a 2D CFT on the celestial sphere. The resulting CFT structure exhibits an OPE constructed from 4D collinear singularities, as well as infinite-dimensional Kac-Moody and Virasoro algebras encoding the asymptotic symmetries of 4D flat space. We derive these results by recasting 4D dynamics in terms of a convenient foliation of flat space into 3D Euclidean AdS and Lorentzian dS geometries. Tree-level scattering amplitudes take the form of Witten diagrams for a continuum of (A)dS modes, which are in turn equivalent to CFT correlators via the (A)dS/CFT dictionary. The Ward identities for the 2D conserved currents are dual to 4D soft theorems, while the bulk-boundary propagators of massless (A)dS modes are superpositions of the leading and subleading Weinberg soft factors of gauge theory and gravity. In general, the massless (A)dS modes are 3D Chern-Simons gauge fields describing the soft, single helicity sectors of 4D gauge theory and gravity. Consistent with the topological nature of Chern-Simons theory, Aharonov-Bohm effects record the "tracks" of hard particles in the soft radiation, leading to a simple characterization of gauge and gravitational memories. Soft particle exchanges between hard processes define the Kac-Moody level and Virasoro central charge, which are thereby related to the 4D gauge coupling and gravitational strength in units of an infrared cutoff. Finally, we discuss a toy model for black hole horizons via a restriction to the Rindler region.

  20. Study of Compton broadening due to electron-photon scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao M.

    2010-01-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radia­tion field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation. The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons. It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle. We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  1. Study of Compton Broadening Due to Electron-Photon Scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.

    2010-06-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  2. Medium modified two-body scattering amplitude from proton-nucleus total cross-sections

    Science.gov (United States)

    Tripathi, R. K.; Wilson, J. W.; Cucinotta, F. A.

    2001-01-01

    Recently (R.K. Tripathi, J.W. Wilson, F.A. Cucinotta, Nucl. Instr. and Meth. B 145 (1998) 277; R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, NASA-TP-1998-208438), we have extracted nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Center. Here, we investigate the ratio of real to imaginary part of the two-body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate total proton-nucleus cross-sections. The agreement is excellent with the available experimental data. These cross-sections are needed for the radiation risk assessment of space missions. c2001 Elsevier Science B.V. All rights reserved.

  3. Relationship between the Amplitude and Phase of a Signal Scattered by a Point-Like Acoustic Inhomogeneity

    Science.gov (United States)

    Burov, V. A.; Morozov, S. A.

    2001-11-01

    Wave scattering by a point-like inhomogeneity, i.e., a strong inhomogeneity with infinitesimal dimensions, is described. This type of inhomogeneity model is used in investigating the point-spread functions of different algorithms and systems. Two approaches are used to derive the rigorous relationship between the amplitude and phase of a signal scattered by a point-like acoustic inhomogeneity. The first approach is based on a Marchenko-type equation. The second approach uses the scattering by a scatterer whose size decreases simultaneously with an increase in its contrast. It is shown that the retarded and advanced waves are scattered differently despite the relationship between the phases of the corresponding scattered waves.

  4. Neutron diffuse scattering in magnetite due to molecular polarons

    International Nuclear Information System (INIS)

    Yamada, Y.; Wakabayashi, N.; Nicklow, R.M.

    1980-01-01

    A detailed neutron diffuse scattering study has been carried out in order to verify a model which describes the property of valence fluctuations in magnetite above T/sub V/. This model assumes the existence of a complex which is composed of two excess electrons and a local displacement mode of oxygens within the fcc primitive cell. The complex is called a molecular polaron. It is assumed that at sufficiently high temperatures there is a random distribution of molecular polarons, which are fluctuating independently by making hopping motions through the crystal or by dissociating into smaller polarons. The lifetime of each molecular polaron is assumed to be long enough to induce an instantaneous strain field around it. Based on this model, the neutron diffuse scattering cross section due to randomly distributed dressed molecular polarons has been calculated. A precise measurement of the quasielastic scattering of neutrons has been carried out at 150 K. The observed results definitely show the characteristics which are predicted by the model calculation and, thus, give evidence for the existence of the proposed molecular polarons. From this standpoint, the Verwey transition of magnetite may be viewed as the cooperative ordering process of dressed molecular polarons. Possible extensions of the model to describe the ordering and the dynamical behavior of the molecular polarons are discussed

  5. Punctual Pade approximants as a regularization procedure for divergent and oscillatory partial wave expansions of the scattering amplitude

    International Nuclear Information System (INIS)

    Garibotti, C.R.; Grinstein, F.F.

    1978-01-01

    Previous theorems on the convergence of the [n,n+m] punctual Pade approximants to the scattering amplitude are extended. The new proofs include the cases of nonforward and backward scattering corresponding to potentials having 1/r and 1/r 2 long-range behaviors, for which the partial wave expansions are divergent and oscillatory, respectively. In this way, the ability of the approximation scheme as a summation method is established for all of the long-range potentials of interest in potential scattering

  6. Punctual Pade Approximants as a regularization procedure for divergent and oscillatory partial wave expansions of the scattering amplitude

    International Nuclear Information System (INIS)

    Garibotti, C.R.; Grinstein, F.F.

    1978-01-01

    Previous theorems on the convergence of the [n, n+m] Punctual Pade Approximants to the scattering amplitude are extended. The new proofs include the cases of non-forward and backward scattering corresponding to potentials having 1/r and 1/r 2 long range behaviours, for which the partial wave expansions are divergent and oscillatory, respectively. In this way, the ability of the approximation scheme as a summation method is established for all of the long range potentials of interest in potential scattering [pt

  7. Effects of 6q bags in the 1D2 pp scattering amplitude and the problem of dibaryon resonances

    International Nuclear Information System (INIS)

    Grach, I.L.; Kalashnikova, Yu.S.; Narodetskij, I.M.

    1987-01-01

    It is shown that the short-range NN forces in the quark compound bag method reproduce the energy dependence of the 1 D 2 pp-scattering amplitude predicted by existing phaseshift analyses. The parameters of the six-quark bag wave function obtained by description of the experimental data are in agreement with the theoretical predictions of the MIT bag model

  8. Left-cut contribution to the dispersion relation for the elastic electron - atomic-hydrogen scattering amplitude

    International Nuclear Information System (INIS)

    Amusia, M.Ya.; Kuchiev, M.Yu.

    1979-01-01

    The jump in the electron - atomic-hydrogen forward scattering amplitude at the cut extending to the left from E = -0.5 au is calculated as a function of the incident electron energy, E, by using the second Born approximation. The contribution from this singularity to the dispersion relation is determined. (Auth.)

  9. Cubic scattering amplitudes for all massless representations of the Poincare group in any space-time dimension

    International Nuclear Information System (INIS)

    Fradkin, E.S.; Metsaev, R.R.

    1996-02-01

    Using the language of highest weight representations and the light cone formalism we construct a full list of cubic amplitudes of scattering for all bosonic massless representations of the Poincare group in any even space-time dimension. (author). 29 refs

  10. Quantum Wronskian approach to six-point gluon scattering amplitudes at strong coupling

    International Nuclear Information System (INIS)

    Hatsuda, Yasuyuki; Ito, Katsushi; Satoh, Yuji; Suzuki, Junji

    2014-06-01

    We study the six-point gluon scattering amplitudes in N=4 super Yang-Mills theory at strong coupling based on the twisted Z 4 -symmetric integrable model. The lattice regularization allows us to derive the associated thermodynamic Bethe ansatz (TBA) equations as well as the functional relations among the Q-/T-/Y-functions. The quantum Wronskian relation for the Q-/T-functions plays an important role in determining a series of the expansion coefficients of the T-/Y-functions around the UV limit, including the dependence on the twist parameter. Studying the CFT limit of the TBA equations, we derive the leading analytic expansion of the remainder function for the general kinematics around the limit where the dual Wilson loops become regular-polygonal. We also compare the rescaled remainder functions at strong coupling with those at two, three and four loops, and find that they are close to each other along the trajectories parameterized by the scale parameter of the integrable model.

  11. Amplitude and Phase Characteristics of Signals at the Output of Spatially Separated Antennas for Paths with Scattering

    Science.gov (United States)

    Anikin, A. S.

    2018-06-01

    Conditional statistical characteristics of the phase difference are considered depending on the ratio of instantaneous output signal amplitudes of spatially separated weakly directional antennas for the normal field model for paths with radio-wave scattering. The dependences obtained are related to the physical processes on the radio-wave propagation path. The normal model parameters are established at which the statistical characteristics of the phase difference depend on the ratio of the instantaneous amplitudes and hence can be used to measure the phase difference. Using Shannon's formula, the amount of information on the phase difference of signals contained in the ratio of their amplitudes is calculated depending on the parameters of the normal field model. Approaches are suggested to reduce the shift of phase difference measured for paths with radio-wave scattering. A comparison with results of computer simulation by the Monte Carlo method is performed.

  12. On the harmonic analysis of the elastic scattering amplitude of two spinless particles at fixed momentum transfer

    International Nuclear Information System (INIS)

    Viano, G.A.

    1980-01-01

    The harmonic analysis of the elastic scattering amplitude F(s,t) of two spinless particles, at fixed t<0, is here revisited using the non-euclidean Fourier analysis in the sense of Helgason, and the approach of Ehrenpresis to the special functions. With these techniques it is possible to derive the Fourier and Laplace transforms for the scattering amplitude. Indeed these transforms are obtained by projecting the amplitude on functions which play a role similar to that played by the exponentials on the real line; here we show how to construct these functions, using essentially geometrical tools. Since the harmonic analysis is a decomposition which separates the dynamics from the symmetry of the problem, we obtain an explicit geometrical characterization of those terms which reflect the symmetry

  13. Inhibition of stimulated Raman scattering due to the excitation of stimulated Brillouin scattering

    Science.gov (United States)

    Zhao, Yao; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming

    2017-09-01

    The nonlinear coupling between stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) of intense laser in underdense plasma is studied theoretically and numerically. Based upon the fluid model, their coupling equations are derived, and a threshold condition of plasma density perturbations due to SBS for the inhibition of SRS is given. Particle-in-cell simulations show that this condition can be achieved easily by SBS in the so-called fluid regime with kLλDDebye length [Kline et al., Phys. Plasmas 13, 055906 (2006)]. SBS can reduce the saturation level of SRS and the temperature of electrons in both homogeneous and inhomogeneous plasma. Numerical simulations also show that this reduced SRS saturation is retained even if the fluid regime condition mentioned above is violated at a later time due to plasma heating.

  14. Density fluctuations due to Raman forward scattering in quantum plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Punit, E-mail: punitkumar@hotmail.com; Singh, Shiv; Rathore, Nisha Singh, E-mail: nishasingh-rathore@yahoo.com [Department of Physics, University of Lucknow, Lucknow-226007 (India)

    2016-05-06

    Density fluctuations due Raman forward scattering (RFS) is analysed in the interaction of a high intensity laser pulse with high density quantum plasma. The interaction model is developed using the quantum hydrodynamic (QHD) model which consist of a set of equations describing the transport of charge, density, momentum and energy of a charged particle system interacting through a self-consistent electrostatic potential. The nonlinear source current has been obtained incorporating the effects of quantum Bohm potential, Fermi pressure and electron spin. The laser spectrum is strongly modulated by the interaction, showing sidebands at the plasma frequency. Furthermore, as the quiver velocity of the electrons in the high electric field of the laser beam is quit large, various quantum effects are observed which can be attributed to the variation of electron mass with laser intensity.

  15. MIGRATION RATES OF PLANETS DUE TO SCATTERING OF PLANETESIMALS

    International Nuclear Information System (INIS)

    Ormel, C. W.; Ida, S.; Tanaka, H.

    2012-01-01

    Planets migrate due to the recoil they experience from scattering solid (planetesimal) bodies. To first order, the torques exerted by the interior and exterior disks will cancel, analogous to the cancellation of the torques from the gravitational interaction with the gas (Type-I migration). Assuming the dispersion-dominated regime and power laws characterized by indices α and β for the surface density and eccentricity profiles, we calculate the net torque on the planet. We consider both distant encounters and close (orbit-crossing) encounters. We find that the close and distant encounter torques have opposite signs with respect to α and β; and that the torque is especially sensitive to the eccentricity gradient β. Compared to Type-I migration due to excitation of density waves, the planetesimal-driven migration rate is generally lower due to the lower surface density of solids in gas-rich disk, although this may be partially or fully offset when their eccentricity and inclinaton are small. Allowing for the feedback of the planet on the planetesimal disk through viscous stirring, we find that under certain conditions a self-regulated migration scenario emerges, in which the planet migrates at a steady pace that approaches the rate corresponding to the one-sided torque. If the ratio of the local disk mass in planetesimals to planet mass is low, however, migration will stall. We quantify the boundaries separating the three accretion regimes.

  16. Measurements of the spin rotation parameter R in high energy elastic scattering and helicity amplitudes at Serpukhov energies

    International Nuclear Information System (INIS)

    Pierrard, J.; Bruneton, C.; Bystricky, J.; Cozzika, G.; Deregel, J.; Ducros, Y.; Gaidot, A.; Khantine-Langlois, F.; Lehar, F.; Lesquen, A. de; Merlo, J.P.; Miyashita, S.; Movchet, J.; Raoul, J.C.; Van Rossum, L.; Kanavets, V.P.

    1975-01-01

    The spin rotation parameter R in pp and π + p elastic scattering at 45GeV/c has been measured at the Serpukhov accelerator, for /t/ ranging from 0.2 to 0.5(GeV/c) 2 . The results are presented, together with previous R measurements at 3.8, 6, 16 and 40GeV/c, and are compared with the predictions of Regge pole models. The equality of the values for R in proton-proton and pion-proton scattering, within the experimental errors, is a test of factorization of the residues. An s-channel helicity amplitude analysis for pion-nucleon scattering at 40GeV/c is made using all available data. Significant results are obtained for the non flip amplitude in isoscalar exchange and for flip amplitudes on both isovector and isoscalar exchanges. The helicity flip in isoscalar exchange is non negligible. The energy dependence of this amplitude, at 6, 16 and 40GeV/c, is compared with predictions of Regge pole models [fr

  17. A Study on Scattered Wave Amplitude Closed-Form Solution Calculation of Torsional Wave Mode by Reciprocity Theorem

    International Nuclear Information System (INIS)

    Lee, Jaesun; Cho, Younho; Achenbach, Jan D.

    2016-01-01

    Guided waves can be used for the inspection of long range pipelines. Surface corrosion is often found as a major defect type in pipelines. The reciprocity relation is a well-established theorem by which one can simplify complicated mathematical expressions. The approach has been already applied to plate and half-space structures to obtain the closed-form solutions of scattered amplitude. However, results for the case of cylindrical structures have not been reported yet. In this paper, the scattering of torsional waves, which is widely used in commercial applications, is explored by the reciprocity theorem approach. Obtaining closed-form solutions of the amplitudes of propagating waves is much simplified by using the reciprocal relation. The scattered amplitudes for elliptical and rectangular defect shapes are calculated with respect to defect depth and width, at frequencies between 0 and 500 kHz. The amplitude shows the periodic result as a function of frequency. The derived closed-form solutions can play a significant role in quantitative signal interpretation

  18. A Study on Scattered Wave Amplitude Closed-Form Solution Calculation of Torsional Wave Mode by Reciprocity Theorem

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaesun; Cho, Younho [Pusan National Univ., Pusan (Korea, Republic of); Achenbach, Jan D. [Northwestern Univ., Everston (United States)

    2016-07-15

    Guided waves can be used for the inspection of long range pipelines. Surface corrosion is often found as a major defect type in pipelines. The reciprocity relation is a well-established theorem by which one can simplify complicated mathematical expressions. The approach has been already applied to plate and half-space structures to obtain the closed-form solutions of scattered amplitude. However, results for the case of cylindrical structures have not been reported yet. In this paper, the scattering of torsional waves, which is widely used in commercial applications, is explored by the reciprocity theorem approach. Obtaining closed-form solutions of the amplitudes of propagating waves is much simplified by using the reciprocal relation. The scattered amplitudes for elliptical and rectangular defect shapes are calculated with respect to defect depth and width, at frequencies between 0 and 500 kHz. The amplitude shows the periodic result as a function of frequency. The derived closed-form solutions can play a significant role in quantitative signal interpretation.

  19. Explosion Amplitude Reduction due to Fractures in Water-Saturated and Dry Granite

    Science.gov (United States)

    Stroujkova, A. F.; Leidig, M.; Bonner, J. L.

    2013-12-01

    Empirical observations made at the Semipalatinsk Test Site suggest that nuclear tests in the fracture zones left by previous explosions ('repeat shots') show reduced seismic amplitudes compared to the nuclear tests in virgin rocks. Likely mechanisms for the amplitude reduction in the repeat shots include increased porosity and reduced strength and elastic moduli, leading to pore closing and frictional sliding. Presence of pore water significantly decreases rock compressibility and strength, thus affecting seismic amplitudes. A series of explosion experiments were conducted in order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fracture zones of previously detonated explosions. Explosions in water-saturated granite were conducted in central New Hampshire in 2011 and 2012. Additional explosions in dry granite were detonated in Barre, VT in 2013. The amplitude reduction is different between dry and water-saturated crystalline rocks. Significant reduction in seismic amplitudes (by a factor of 2-3) in water-saturated rocks was achieved only when the repeat shot was detonated in the extensive damage zone created by a significantly larger (by a factor of 5) explosion. In case where the first and the second explosions were similar in yield, the amplitude reduction was relatively modest (5-20%). In dry rocks the amplitude reduction reached a factor of 2 even in less extensive damage zones. In addition there are differences in frequency dependence of the spectral amplitude ratios between explosions in dry and water-saturated rocks. Thus the amplitude reduction is sensitive to the extent of the damage zone as well as the pore water content.

  20. Why the Real Part of the Proton-Proton Forward Scattering Amplitude Should be Measured at the LHC

    CERN Document Server

    Bourrely, C.; Martin, Andre; Soffer, Jacques; Wu, Tai Tsun

    2006-01-01

    For the energy of 14 TeV, to be reached at the Large Hadron Collider (LHC), we have had for some time accurate predictions for both the real and imaginary parts of the forward proton-proton elastic scattering amplitude. LHC is now scheduled to start operating in two years, and it is timely to discuss some of the important consequences of the measurements of both the total cross-section and the ratio of the real to the imaginary part. We stress the importance of measuring the real part of the proton-proton forward scattering amplitude at LHC, because a deviation from existing theoretical predictions could be a strong sign for new physics.

  1. Solution of equation for imaginary part of forward scattering amplitude for theories with lambdaphisup(n) interaction

    International Nuclear Information System (INIS)

    Arbuzov, B.A.; D'yakonov, V.Yu.; Rochev, V.E.

    1975-01-01

    Solution of equations for imaginary part of forward scattering amplitude in ladder approximation for theories with lambdaphisup(n),n(>=)4 interaction have been obtained. Two types of diagrams have been considered for lambdaphisup(n) renormalizable theory. It is shown, that the leading singularity is the branch point, which gives the power asymptotics with accuracy up to logarithms. The unrenormalizable theory with n(>=)5 lead to exponentially rising asymptotics

  2. Raman scattering evidence for a cascade-like evolution of the charge-density-wave collective amplitude mode

    Energy Technology Data Exchange (ETDEWEB)

    Eiter, Hans-Martin; Tassini, Leonardo; Muschler, Bernhard; Hackl, Rudi [Walther Meissner Institute, Bavarian Academy of Sciences and Humanities, 85748 Garching (Germany); Lavagnini, Michela; Degiorgi, Leonardo [Laboratorium fuer Festkoerperphysik, ETH - Zuerich, CH-8093 Zuerich (Switzerland); Chu, Jiun-Haw; Ru, Nancy; Fisher, Ian R. [GLAM, Stanford University, CA 94304 (United States)

    2010-07-01

    We report results of Raman scattering experiments as a function of temperature on the charge-density-wave (CDW) systems DyTe{sub 3} and on LaTe{sub 3} at 6 GPa applied pressure. We clearly identify the unidirectional collective CDW amplitude excitation and follow their temperature dependence in the range from 6 K to 311 K. Surprisingly, we discover that the amplitude mode develops as a succession of two mean-field, BCS-like transitions at two different temperatures. Tri-tellurides with heavier rare-earth atoms (i.e. Tm, Er, Ho, Dy) undergo another phase transition to a bidirectional CDW at low temperatures. In DyTe{sub 3} we find spectroscopic evidence for the amplitude mode excitation associated with the bidirectional CDW occuring below 50 K.

  3. Emittance growth due to beam-gas scattering

    International Nuclear Information System (INIS)

    Raubenheimer, T.O.

    1992-06-01

    The effect of beam-gas scattering on beam emittance is examined by deriving the beam distribution function. The distribution function is found by treating the beam-gas scattering as a filtered Poisson process and calculating the cumulants of the distribution. (author)

  4. Forward diffraction amplitude of pp and pp elastic scattering at accelerator energies

    International Nuclear Information System (INIS)

    Kawasaki, M.; Maehara, T.; Yonezawa, M.

    2004-01-01

    A simple relation between the total cross section and the forward exponential slope of the elastic differential cross section of pp and pp scattering is indicated. An interpretation of this relation is presented as the formation of a black-disk structure for the elastic diffraction interaction of hadron-hadron scattering at the nonasymptotic energy region

  5. The Analytic Structure of Scattering Amplitudes in N = 4 Super-Yang-Mills Theory

    Science.gov (United States)

    Litsey, Sean Christopher

    We begin the dissertation in Chapter 1 with a discussion of tree-level amplitudes in Yang-. Mills theories. The DDM and BCJ decompositions of the amplitudes are described and. related to one another by the introduction of a transformation matrix. This is related to the. Kleiss-Kuijf and BCJ amplitude identities, and we conjecture a connection to the existence. of a BCJ representation via a condition on the generalized inverse of that matrix. Under. two widely-believed assumptions, this relationship is proved. Switching gears somewhat, we introduce the RSVW formulation of the amplitude, and the extension of BCJ-like features to residues of the RSVW integrand is proposed. Using the previously proven connection of BCJ representations to the generalized inverse condition, this extension is validated, including a version of gravitational double copy. The remainder of the dissertation involves an analysis of the analytic properties of loop. amplitudes in N = 4 super-Yang-Mills theory. Chapter 2 contains a review of the planar case, including an exposition of dual variables and momentum twistors, dual conformal symmetry, and their implications for the amplitude. After defining the integrand and on-shell diagrams, we explain the crucial properties that the amplitude has no poles at infinite momentum and that its leading singularities are dual-conformally-invariant cross ratios, and can therefore be normalized to unity. We define the concept of a dlog form, and show that it is a feature of the planar integrand as well. This leads to the definition of a pure integrand basis. The proceeding setup is connected to the amplituhedron formulation, and we put forward the hypothesis that the amplitude is determined by zero conditions. Chapter 3 contains the primary computations of the dissertation. This chapter treats. amplitudes in fully nonplanar N = 4 super-Yang-Mills, analyzing the conjecture that they. follow the pattern of having no poles at infinity, can be written in dlog

  6. A heating mechanism of ions due to large amplitude coherent ion acoustic wave

    International Nuclear Information System (INIS)

    Yajima, Nobuo; Kawai, Yoshinobu; Kogiso, Ken.

    1978-05-01

    Ion heating mechanism in a plasma with a coherent ion acoustic wave is studied experimentally and numerically. Ions are accelerated periodically in the electrostatic potential of the coherent wave and their oscillation energy is converted into the thermal energy of ions through the collision with the neutral atoms in plasma. The Monte Carlo calculation is applied to obtain the ion temperature. The amplitude of the electrostatic potential, the mean number of collisions and the mean life time of ions are treated as parameters in the calculation. The numerical results are compared with the experiments and both of them agree well. It is found that the ion temperature increases as the amplitude of the coherent wave increases and the high energy tail in the distribution function of ions are observed for the case of large wave-amplitude. (author)

  7. Analysis of forward and near-forward elastic-scattering amplitudes for pp and anti pp collisions

    International Nuclear Information System (INIS)

    Block, M.B.; Cahn, R.N.

    1983-04-01

    We will present the results of two recently published (1983) papers by M.M. Block and R.N. Cahn, which analyze for anti pp and pp elastic scattering the rho values (ratios of the real to the imaginary parts of the forward nuclear scattering amplitudes), the total (hadronic) cross sections sigma, and the b values, the nuclear slope parameters. The predictions of the analyses, from √ s bar > 5 GeV, is compared with the recently measured values of sigma and b at the SPS Collider. The analysis has also been redone to include new ISR data available from R211 at √ s bar = 62.5 GeV, in order to estimate odderon contributions, i.e., contributions from odd amplitudes with unconventional (non-Reggeon) energy dependence. Limits of approx. 1% are placed on these amplitudes. Our analysis has been extrapolated up to 100 TeV, to give sigma, rho and b predictions for cosmic ray and future collider energies

  8. A high-resolution two-pulse coherent anti-Stokes Raman scattering spectrum using a spectral amplitude modulation

    International Nuclear Information System (INIS)

    Lu, Chenhui; Zhang, Shian; Wu, Meizhen; Jia, Tianqing; Sun, Zhenrong; Qiu, Jianrong

    2013-01-01

    Femtosecond coherent anti-Stokes Raman scattering (CARS) spectra suffer from low spectral resolution because of the broadband laser spectrum. In this paper, we propose a feasible scheme to achieve a high-resolution two-pulse CARS spectrum by shaping both the pump and probe pulses using rectangular amplitude modulation. We show that a narrowband hole in the CARS spectrum can be created by the amplitude-shaped laser pulse, the position of which is correlated with the Raman resonant frequency of the molecule. Thus, by observing holes in the CARS spectrum, we are able to obtain a high-resolution CARS spectrum and the energy-level diagram of the molecule. (paper)

  9. Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance.

    Science.gov (United States)

    Chesi, Stefano; Yang, Li-Ping; Loss, Daniel

    2016-02-12

    We analyze effects of the hyperfine interaction on electric dipole spin resonance when the amplitude of the quantum-dot motion becomes comparable or larger than the quantum dot's size. Away from the well-known small-drive regime, the important role played by transverse nuclear fluctuations leads to a Gaussian decay with characteristic dependence on drive strength and detuning. A characterization of spin-flip gate fidelity, in the presence of such additional drive-dependent dephasing, shows that vanishingly small errors can still be achieved at sufficiently large amplitudes. Based on our theory, we analyze recent electric dipole spin resonance experiments relying on spin-orbit interactions or the slanting field of a micromagnet. We find that such experiments are already in a regime with significant effects of transverse nuclear fluctuations and the form of decay of the Rabi oscillations can be reproduced well by our theory.

  10. Magnitudes and slopes of real and imaginary amplitudes in the Coulomb interference region of pp and pbarp scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kohara, Anderson Kendi; Ferreira, Erasmo; Kodama, Takeshi [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

    2011-07-01

    Full text: We use exact Derivative Dispersion Relations [?, ?] to investigate properties of the real and imaginary amplitudes in the forward region of pp and pbarp scattering. We emphasize that the effective slope in dσ/dt is formed by different exponential slopes in the real and imaginary amplitudes (called B{sub R} and B{sub I} ). For this purpose a more general treatment of the Coulomb phase is developed. The dσ/dt data in the range from 19 to 1800 GeV for low |t| are analysed in terms of the four quantities σ, ρ, B{sub I}, B{sub R} that are basic for dynamical models . The usual assumption that B{sub I} and B{sub R} are the same, with σ not depending strongly on t, does not agree with dispersion relations, for which B{sub R} > B{sub I} , and with the expectation that the first real zero approaches t=0 as the energy increases. Our work uses dispersion relations to disentangle the quantities that represent observables in terms of imaginary and real parts, intrinsically combined with the Coulomb contribution. To investigate real slopes we use new forms of dispersion relations [?]. With the difference between imaginary and real slopes , the future RHIC and LHC data will require the extended analysis with B{sub R} as a free quantity. We investigate in detail the region from 19 to 30 GeV where the real amplitude in pp scattering may vanish. The data for ρ are contradictory in this range. We investigate the meaning of the real slope B{sub R} in this region where the parameter ρ is very small, and construct coherent description of the data. In the high energy region we obtain scattering parameters for the RHIC and LHC experiments. (author)

  11. Dispersion corrections to the forward Rayleigh scattering amplitudes of tantalum, mercury and lead derived using photon interaction cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Appaji Gowda, S.B. [Department of Studies in Physics, Manasagangothri, University of Mysore, Mysore 570006 (India); Umesh, T.K. [Department of Studies in Physics, Manasagangothri, University of Mysore, Mysore 570006 (India)]. E-mail: tku@physics.uni-mysore.ac.in

    2006-01-15

    Dispersion corrections to the forward Rayleigh scattering amplitudes of tantalum, mercury and lead in the photon energy range 24-136 keV have been determined by a numerical evaluation of the dispersion integral that relates them through optical theorem to the photo effect cross sections. The photo effect cross sections have been extracted by subtracting the coherent and incoherent scattering contribution from the measured total attenuation cross section, using high-resolution high-purity germanium detector in a narrow beam good geometry set up. The real part of the dispersion correction to which the relativistic corrections calculated by Kissel and Pratt (S-matrix approach) or Creagh and McAuley (multipole corrections) have been included are in better agreement with the available theoretical values.

  12. Elastic high-energy proton scattering on 40Ca with exact expression for nucleon-nucleon amplitude and flucton correlations

    International Nuclear Information System (INIS)

    Antonov, A.N.; Christov, Chr.V.; Nikolov, E.N.

    1989-01-01

    Differential cross-section of the 1.04 GeV - proton elastic scattering from 40 Ca is calculated within the Glauber-Sitenko theoretical scheme using the coherent density fluctuation model (CDFM). It is shown that the use of exact noneikonal expression for the two-body scattering amplitude (which describes the p-p data) leads to a satisfactory agreement with the experimental data. The influence of the flucton correlations on the differential cross-sections is considerable as the use of a realistic charge density distribution leads to a better agreement with the experimental data of the CDFM which is not for the case of the independent-particle model. 20 refs.; 4 figs

  13. Reggeon effects in a geometrical model of elastic scattering. [Crossover curves, dip depth, scattering amplitude, 10 to 10,000 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Dias de Deus, J [Instituto de Fisica e Matematica, Lisboa (Portugal); Kroll, P [Wuppertal Univ. (Gesamthochschule) (Germany, F.R.)

    1976-08-21

    The inclusion of secondary contributions Reggeons and real parts by changing the radial scale but exactly preserving geometrical scaling (GS) alloys an exclusion of GS to lower energies. The crossover curves in proton proton, Kp, and *pp are in this way correctly described. A GS formula relating two measurable quantities, the depth of the dip in proton proton scattering and the ratio of the real to immaginary part of the amplitude at t=0, is shown to be valid in the 10-1000 GeV region.

  14. Pulsar high energy emission due to inverse Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lyutikov, Maxim

    2013-06-15

    We discuss growing evidence that pulsar high energy is emission is generated via Inverse Compton mechanism. We reproduce the broadband spectrum of Crab pulsar, from UV to very high energy gamma-rays - nearly ten decades in energy, within the framework of the cyclotron-self-Compton model. Emission is produced by two counter-streaming beams within the outer gaps, at distances above ∼ 20 NS radii. The outward moving beam produces UV-X-ray photons via Doppler-booster cyclotron emission, and GeV photons by Compton scattering the cyclotron photons produced by the inward going beam. The scattering occurs in the deep Klein-Nishina regime, whereby the IC component provides a direct measurement of particle distribution within the magnetosphere. The required plasma multiplicity is high, ∼10{sup 6} – 10{sup 7}, but is consistent with the average particle flux injected into the pulsar wind nebula.

  15. Phenomenological extraction of two-photon exchange amplitudes from elastic electron-proton scattering cross section data

    Science.gov (United States)

    Qattan, I. A.

    2017-05-01

    Background: The inconsistency in the results obtained from the Rosenbluth separation method and the high-Q2 recoil polarization results on the ratio μpGEp/GMp implies a systematic difference between the two techniques. Several studies suggest that missing higher-order radiative corrections to elastic electron-proton scattering cross section σR(ɛ ,Q2) and in particular hard two-photon-exchange (TPE) contributions could account for the discrepancy. Purpose: In this work, I improve on and extend to low and high Q2 values the extractions of the ɛ dependence of the real parts of the TPE amplitudes relative to the magnetic form factor, as well as the ratio Pl/PlBorn(ɛ ,Q2) by using world data on σR(ɛ ,Q2) with an emphasis on precise new data covering the low-momentum region which is sensitive to the large-scale structure of the nucleon. Method: I combine cross section and polarization measurements of elastic electron-proton scattering to extract the TPE amplitudes. Because the recoil polarization data were confirmed "experimentally" to be essentially independent of ɛ , I constrain the ratio Pt/Pl(ɛ ,Q2) to its ɛ -independent term (Born value) by setting the TPE contributions to zero. This allows for the amplitude YM(ɛ ,Q2) and σR(ɛ ,Q2) to be expressed in terms of the remaining two amplitudes YE(ɛ ,Q2) and Y3(ɛ ,Q2) which in turn are parametrized as second-order polynomials in ɛ and Q2 to reserve as possible the linearity of σR(ɛ ,Q2) as well as to account for possible nonlinearities in the TPE amplitudes. Furthermore, I impose the Regge limit which ensures the vanishing of the TPE contributions to σR(ɛ ,Q2) and the TPE amplitudes in the limit ɛ →1 . Results: I provide simple parametrizations of the TPE amplitudes, along with an estimate of the fit uncertainties. The extracted TPE amplitudes are compared with previous phenomenological extractions and TPE calculations. The Pl/PlBorn ratio is extracted by using the new parametrizations of the TPE

  16. QED polarization asymmetries for e+e- scattering due to helicity flips

    International Nuclear Information System (INIS)

    Anders, T.B.; Sell, E.W.

    1992-01-01

    The polarization asymmetries for the e + e - scattering with polarized incoming of outgoing beams, which are proportional to the amplitudes φ 5 describing one helicity flip and φ 2 describing two helicity flips, have been calculated including their pure QED radiative corrections. These asymmetries are partly large and can be observed well at low energies. (orig.)

  17. The high energy behavior of the forward scattering parameters - an amplitude analysis update

    International Nuclear Information System (INIS)

    Block, M.M.; Margolis, B.; White, A.R.

    1995-01-01

    Utilizing the most recent experimental data, we reanalyze high energy pp and pp data, using the asymptotic amplitude analysis, under the assumption that we have reached open-quotes asymptopiaclose quotes. This analysis gives strong evidence for a log (s/s 0 ) dependence at current energies and not log 2 (s/s 0 ), and also demonstrates that odderons are not necessary to explain the experimental data

  18. Probing scalar effective field theories with the soft limits of scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, Antonio [School of Physics and Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD United Kingdom (United Kingdom); Stefanyszyn, David [Van Swinderen Institute for Particle Physics and Gravity, University of Groningen,Nijenborgh 4, Groningen, 9747 AG The (Netherlands); Wilson, Toby [School of Physics and Astronomy, University of Nottingham,University Park, Nottingham, NG7 2RD United Kingdom (United Kingdom)

    2017-04-04

    We investigate the soft behaviour of scalar effective field theories (EFTs) when there is a number of distinct derivative power counting parameters, ρ{sub 1}<ρ{sub 2}<…<ρ{sub Q}. We clarify the notion of an enhanced soft limit and use these to extend the scope of on-shell recursion techniques for scalar EFTs. As an example, we perform a detailed study of theories with two power counting parameters, ρ{sub 1}=1 and ρ{sub 2}=2, that include the shift symmetric generalised galileons. We demonstrate that the minimally enhanced soft limit uniquely picks out the Dirac-Born-Infeld (DBI) symmetry, including DBI galileons. For the exceptional soft limit we uniquely pick out the special galileon within the class of theories under investigation. We study the DBI galileon amplitudes more closely, verifying the validity of the recursion techniques in generating the six point amplitude, and explicitly demonstrating the invariance of all amplitudes under DBI galileon duality.

  19. Why the real part of the proton-proton forward scattering amplitude should be measured at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Bourrely, C.; Soffer, J. [Centre de Physique Theorique, UMR 6207 b, CNRS-Luminy, 13 - Marseille (France); Khuri, N.N. [Rockfeller Univ., (2) Physics Dept., New York, N.Y. (United States); Martin, A.; Tai Tsun Wu, J. [Conseil Europeen pour la recherche nucleaire, Theory Div., Geneve (Switzerland); Tai Tsun Wu, J. [Harvard Univ., Gordon Mc Kay Lab., Cambridge, MA (United States)

    2005-07-01

    For the energy of 14 TeV, to be reached at the Large Hadron Collider (LHC), we have had for some time accurate predictions for both the real and imaginary parts of the forward proton-proton elastic scattering amplitude. LHC is now scheduled to start operating in 2 years, and it is timely to discuss some of the important consequences of the measurements of both the total cross-section and the ratio of the real to the imaginary part ({rho}). An accurate prediction is given by the BSW model: {rho} = 0.122 with {sigma}(total) = 103.6 mb (at the LHC energy {radical}(s) = 14 TeV. If the experiment gives numbers compatible with those above, it will mean that the scale of violation is very much above the LHC energy or that the corresponding minimal size is much smaller. On the contrary a disagreement would give indication for new physics and we stress the importance of measuring the real part of the proton-proton forward scattering amplitude at LHC, because a deviation from existing theoretical predictions could be a strong sign for new physics.

  20. Surface plasmon transmission through discontinuous conducting surfaces: Plasmon amplitude modulation by grazing scattered fields

    Energy Technology Data Exchange (ETDEWEB)

    Mayoral-Astorga, L. A.; Gaspar-Armenta, J. A.; Ramos-Mendieta, F. [Departamento de Investigación en Física, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora, 83190 México (Mexico)

    2016-04-15

    We have studied numerically the diffraction of a surface plasmon polariton (SPP) when it encounters a wide multi-wavelength slit in conducting films. As a jump process a SPP is excited beyond the slit by wave scattering at the second slit edge. The exciting radiation is produced when the incident SPP collapses at the first slit edge. We have found that the transmitted SPP supports inherent and unavoidable interference with grazing scattered radiation; the spatial modulation extends to the fields in the diffraction region where a series of low intensity spots arises. We demonstrate that the SPP generated on the second slab depends on the frequency but not on the wave vector of the collapsed SPP; a SPP is transmitted even when the two metals forming the slit are different. The numerical results were obtained using the Finite Difference Time Domain (FDTD) method with a grid size λ/100.

  1. Quasielastic neutron scattering study of large amplitude motions in molecular systems

    International Nuclear Information System (INIS)

    Bee, M.

    1996-01-01

    This lecture aims at giving some illustrations of the use of Incoherent Quasielastic Neutron Scattering in the investigation of motions of atoms or molecules in phases with dynamical disorder. The general incoherent scattering function is first recalled. Then the Elastic Incoherent Structure Factor is introduced. It is shown how its determination permits to deduce a particular dynamical model. Long-range translational diffusion is illustrated by some experiments carried out with liquids or with different chemical species intercalated in porous media. Examples of rotational motions are provided by solid phases where an orientational disorder of the molecules exists. The jump model is the most commonly used and yields simple scattering laws which can be easily handled. Highly disordered crystals require a description in terms of the isotropic rotational diffusion model. Many of the present studies are concerned with rather complicated systems. Considerable help is obtained either by using selectively deuterated samples or by carrying out measurements with semi-oriented samples. (author) 5 figs., 14 refs

  2. Generalized separable expansion method of the two-body and the three-body scattering amplitudes

    International Nuclear Information System (INIS)

    Oryu, S.; Ishihara, T.

    1976-01-01

    A systematic method is proposed for obtaining new N-rank separable amplitudes of the two-body and the three-body equations. First of all, the authors start from the Amado equation which is modified from the three-body Faddeev equation by using the two-body Yamaguchi potential for the nucleon-nucleon interaction. It is well known that the Amado equation can be integrated on the real axis because the kernel has a logarithmic cut on the real axis. However, a separable three-body form factor which is regular on the real axis except for the cut has been found. (Auth.)

  3. NearFar: A computer program for nearside farside decomposition of heavy-ion elastic scattering amplitude

    Science.gov (United States)

    Cha, Moon Hoe

    2007-02-01

    The NearFar program is a package for carrying out an interactive nearside-farside decomposition of heavy-ion elastic scattering amplitude. The program is implemented in Java to perform numerical operations on the nearside and farside angular distributions. It contains a graphical display interface for the numerical results. A test run has been applied to the elastic O16+Si28 scattering at E=1503 MeV. Program summaryTitle of program: NearFar Catalogue identifier: ADYP_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADYP_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: none Computers: designed for any machine capable of running Java, developed on PC-Pentium-4 Operating systems under which the program has been tested: Microsoft Windows XP (Home Edition) Program language used: Java Number of bits in a word: 64 Memory required to execute with typical data: case dependent No. of lines in distributed program, including test data, etc.: 3484 Number of bytes distributed program, including test data, etc.: 142 051 Distribution format: tar.gz Other software required: A Java runtime interpreter, or the Java Development Kit, version 5.0 Nature of physical problem: Interactive nearside-farside decomposition of heavy-ion elastic scattering amplitude. Method of solution: The user must supply a external data file or PPSM parameters which calculates theoretical values of the quantities to be decomposed. Typical running time: Problem dependent. In a test run, it is about 35 s on a 2.40 GHz Intel P4-processor machine.

  4. Geometric scaling behavior of the scattering amplitude for DIS with nuclei

    Science.gov (United States)

    Kormilitzin, Andrey; Levin, Eugene; Tapia, Sebastian

    2011-12-01

    The main question, that we answer in this paper, is whether the initial condition can influence on the geometric scaling behavior of the amplitude for DIS at high energy. We re-write the non-linear Balitsky-Kovchegov equation in the form which is useful for treating the interaction with nuclei. Using the simplified BFKL kernel, we find the analytical solution to this equation with the initial condition given by the McLerran-Venugopalan formula. This solution does not show the geometric scaling behavior of the amplitude deeply in the saturation region. On the other hand, the BFKL Pomeron calculus with the initial condition at x=1/mR given by the solution to Balitsky-Kovchegov equation, leads to the geometric scaling behavior. The McLerran-Venugopalan formula is the natural initial condition for the Color Glass Condensate (CGC) approach. Therefore, our result gives a possibility to check experimentally which approach: CGC or BFKL Pomeron calculus, is more satisfactory.

  5. Geometric scaling behavior of the scattering amplitude for DIS with nuclei

    International Nuclear Information System (INIS)

    Kormilitzin, Andrey; Levin, Eugene; Tapia, Sebastian

    2011-01-01

    The main question, that we answer in this paper, is whether the initial condition can influence on the geometric scaling behavior of the amplitude for DIS at high energy. We re-write the non-linear Balitsky–Kovchegov equation in the form which is useful for treating the interaction with nuclei. Using the simplified BFKL kernel, we find the analytical solution to this equation with the initial condition given by the McLerran–Venugopalan formula. This solution does not show the geometric scaling behavior of the amplitude deeply in the saturation region. On the other hand, the BFKL Pomeron calculus with the initial condition at x A =1/mR A given by the solution to Balitsky–Kovchegov equation, leads to the geometric scaling behavior. The McLerran–Venugopalan formula is the natural initial condition for the Color Glass Condensate (CGC) approach. Therefore, our result gives a possibility to check experimentally which approach: CGC or BFKL Pomeron calculus, is more satisfactory.

  6. A new method for the determination of the real part of the hadron elastic scattering amplitude at small angles and high energies

    Energy Technology Data Exchange (ETDEWEB)

    Gauron, P. [Theory Group, Laboratoire de Physique Nucleaire et des Hautes Energies (LPNHE), CNRS, and Universite Pierre et Marie Curie, Paris (France)]. E-mail: gauron@in2p3.fr; Nicolescu, B. [Theory Group, Laboratoire de Physique Nucleaire et des Hautes Energies (LPNHE), CNRS, and Universite Pierre et Marie Curie, Paris (France)]. E-mail: nicolesc@lpnhep.in2p3.fr; Selyugin, O.V. [BLTP, JINR, Dubna, Moscow region (Russian Federation)]. E-mail: selugin@thsun1.jinr.ru

    2005-11-24

    A new method for the determination of the real part of the elastic scattering amplitude is examined for high energy proton-proton at small momentum transfer. This method allows us to decrease the number of model assumptions, to obtain the real part in a narrow region of momentum transfer and to test different models. The real part is computed at a given point t{sub min} near t=0 from the known Coulomb amplitude. Hence one obtains an important constraint on the real part of the forward scattering amplitude and therefore on the {rho}-parameter (measuring the ratio of the real to imaginary part of the scattering amplitude at t=0), which can be tested at LHC.

  7. The quasi-classical limit of scattering amplitude - L2-approach for short range potentials

    International Nuclear Information System (INIS)

    Yajima, K.; Vienna Univ.

    1984-01-01

    We are concerned with the asymptotic behaviour as Planck's constant h → 0 of the scattering operator Ssup(h) associated with the pair of Schroedinger equations i h/2π delta u/delta t = - ((h/2π) 2 /2m)Δu + V(x) u equivalent to Hsup(h)u and i h/2π delta u/delta t = - ((h/2π) 2 /2m)Δu equivalent to Hsup(h) 0 u. We shall show under certain conditions that the scattering matrix S-circumflexsup(h)(p,q), the distribution kernel of Ssup(h) in momentum representation, may be expressed in terms of a Fourier integral operator. Then applying the stationary phase method to it, we shall prove that S-circumflexsup(h) has an asymptotic expansion in powers of h/2π up to any order in L 2 -space and that the limit as h → 0 of the total cross section is twice the one of classical mechanics, in generic. (Author)

  8. Improved Off-Shell Scattering Amplitudes in String Field Theory and New Computational Methods

    CERN Document Server

    Park, I Y; Bars, Itzhak

    2004-01-01

    We report on new results in Witten's cubic string field theory for the off-shell factor in the 4-tachyon amplitude that was not fully obtained explicitly before. This is achieved by completing the derivation of the Veneziano formula in the Moyal star formulation of Witten's string field theory (MSFT). We also demonstrate detailed agreement of MSFT with a number of on-shell and off-shell computations in other approaches to Witten's string field theory. We extend the techniques of computation in MSFT, and show that the j=0 representation of SL(2,R) generated by the Virasoro operators $L_{0},L_{\\pm1}$ is a key structure in practical computations for generating numbers. We provide more insight into the Moyal structure that simplifies string field theory, and develop techniques that could be applied more generally, including nonperturbative processes.

  9. MHV amplitudes for 3→3 gluon scattering in Regge limit

    International Nuclear Information System (INIS)

    Bartels, J.; Prygarin, A.

    2010-12-01

    We calculate corrections to the BDS formula for the six-particle planar MHV amplitude for the gluon transition 3 → 3 in the multi-Regge kinematics for the physical region, in which the Regge pole ansatz is not valid. The remainder function at two loops is obtained by an analytic continuation of the expression derived by Goncharov, Spradlin, Vergu and Volovich to the kinematic region described by the Mandelstam singularity exchange in the crossing channel. It contains both the imaginary and real contributions being in agreement with the BFKL predictions. The real part of the three loop expression is found from a dispersion-like all-loop formula for the remainder function in the multi-Regge kinematics derived by one of the authors. We also make a prediction for the all-loop real part of the remainder function multiplied by the BDS phase, which can be accessible through calculations in the regime of the strong coupling constant. (orig.)

  10. MHV amplitudes for 3{yields}3 gluon scattering in Regge limit

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Prygarin, A. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Lipatov, L.N. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; St. Petersburg Nuclear Physics Institute (Russian Federation)

    2010-12-15

    We calculate corrections to the BDS formula for the six-particle planar MHV amplitude for the gluon transition 3 {yields} 3 in the multi-Regge kinematics for the physical region, in which the Regge pole ansatz is not valid. The remainder function at two loops is obtained by an analytic continuation of the expression derived by Goncharov, Spradlin, Vergu and Volovich to the kinematic region described by the Mandelstam singularity exchange in the crossing channel. It contains both the imaginary and real contributions being in agreement with the BFKL predictions. The real part of the three loop expression is found from a dispersion-like all-loop formula for the remainder function in the multi-Regge kinematics derived by one of the authors. We also make a prediction for the all-loop real part of the remainder function multiplied by the BDS phase, which can be accessible through calculations in the regime of the strong coupling constant. (orig.)

  11. Exact potential and scattering amplitudes from the tachyon non-linear β -function

    International Nuclear Information System (INIS)

    Coletti, E.; Forini, V.; Nardelli, G.; Orselli, M.; Grignani, G.

    2004-01-01

    We compute, on the disk, the non-linear tachyon β-function, β T , of the open bosonic string theory. β T is determined both in an expansion to the third power of the field and to all orders in derivatives and in an expansion to any power of the tachyon field in the leading order in derivatives. We construct the Witten-Shatashvili (WS) space-time effective action S and prove that it has a very simple universal form in terms of the renormalized tachyon field and β T . The expression for S is well suited to studying both processes that are far off-shell, such as tachyon condensation, and close to the mass-shell, such as perturbative on-shell amplitudes. We evaluate S in a small derivative expansion, providing the exact tachyon potential. The normalization of S is fixed by requiring that the field redefinition that maps S into the tachyon effective action derived from the cubic string field theory is regular on-shell. The normalization factor is in precise agreement with the one required for verifying all the conjectures on tachyon condensation. The coordinates in the space of couplings in which the tachyon β-function is non linear are the most appropriate to study RG fixed points that can be interpreted as solitons of S, i.e. D-branes. (author)

  12. Analytic amplitudes for hadronic forward scattering and the Heisenberg ln{sup 2} s behaviour of total cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Nicolescu, Basarab [LPNHE, Unite de Recherche des Universites Paris 6 et Paris 7, associee au CNRS, Theory Group, Universite Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05 (France)

    2004-07-01

    We consider several classes of analytic parametrizations of hadronic scattering amplitudes (the COMPETE analysis), and compare their predictions to all available forward data (pp, {pi}p, Kp, {gamma}p, {gamma}{gamma}, {sigma}p). Although these parametrizations are very close for {radical}s {>=} 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term {approx} ln{sup 2} s enables one to extend the fit down to {radical}s = 4 GeV. We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude ({rho} parameter) for present and future pp colliders, and on total cross sections for {gamma}p {yields} hadrons at cosmic-ray energies and for it{gamma}{gamma} {yields} hadrons up to {radical}s = 1 TeV. The ln{sup 2} s behaviour of total cross sections, first obtained by Heisenberg 50 years ago, receives now increased interest both on phenomenological and theoretical levels. We present a modification of the Heisenberg's model in connection with the presence of glueballs and we show that it leads to a realistic description of all existing hadron total cross-sections data, in agreement with the COMPETE analysis.

  13. High amplitude ultrasound pulse generation using time-reversal through a multiple scattering medium

    OpenAIRE

    ARNAL , Bastien; Pernot , Mathieu; Fink , Mathias; Tanter , Mickaël

    2012-01-01

    International audience; In histotripsy, soft tissues can be fragmented using very high pressure ultrasound pulses. Using time-reversal cavity is a way to generate high pressure pulses with a limited number of acoustic sources. The principle was already demonstrated by Montaldo et al. using a solid metal cavity, but low transmission coefficient was obtained due to the strong impedance mismatch at the metal/water interface. We propose here to use a waveguide filled with water containing a 2D mu...

  14. Analytic structure of the n=7 scattering amplitude in N=4 SYM theory at multi-Regge kinematics. Conformal Regge pole contribution

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, Jochen; Kormilitzin, Andrey [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Lipatov, Lev [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; St. Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation)

    2013-11-15

    We investigate the analytic structure of the 2 {yields} 5 scattering amplitude in the planar limit of N=4 SYM in multi-Regge kinematics in all physical regions. We demonstrate the close connection between Regge pole and Regge cut contributions: in a selected class of kinematic regions (Mandelstam regions) the usual factorizing Regge pole formula develops unphysical singularities which have to be absorbed and compensated by Regge cut contributions. This leads, in the corrections to the BDS formula, to conformal invariant 'renormalized' Regge pole expressions in the remainder function. We compute these renormalized Regge poles for the 2 {yields} 5 scattering amplitude.

  15. Analytic structure of the n=7 scattering amplitude in N=4 SYM theory in multi-Regge kinematics. Conformal Regge cut contribution

    International Nuclear Information System (INIS)

    Bartels, Jochen; Kormilitzin, Andrey; Oxford Univ.; Lipatov, Lev N.; Oxford Univ.; St. Petersburg State Univ.

    2014-11-01

    In this second part of our investigation of the analytic structure of the 2→5 scattering amplitude in the planar limit of N=4 SYM in multi-Regge kinematics we compute, in all kinematic regions, the Regge cut contributions in leading order. The results are infrared finite and conformally invariant.

  16. Forward scattering amplitudes for π+- on Al, Ca, Cu, Sn, Ho, and Pb in the energy range 114-215 MeV

    International Nuclear Information System (INIS)

    Jeppesen, R.H.

    1980-01-01

    Measurements have been made of the attenuation cross section, sigma(Ω), for both π + and π- projectiles on Al, 40 Ca, Cu, Sn, Ho, and Pb nuclei. The measurements were made over a range of energies including 114, 140, 165, and 215 MeV. A new method of analyzing transmission experiments data has been used to extract both the real and the imaginary parts of a forward scattering amplitude f/sub N/(0), where f/sub N/(0) is defined to be the limit as Ω → 0 of F(Ω)-f/sub c/(Ω). F(Ω) is the full elastic scattering amplitude and f/sub c/(Ω) is the relativistic point Coulomb amplitude. The values of f/sub N/(0) are compared with forward amplitudes from model calculation. These comparisons demonstrate that much of the observed rotation of the forward scattering amplitude, when plotted in the Argand plane, can be attributed to the Coulomb phase contained in the definition of f/sub N/(0). Results are also compared to those of other experiments. A difference is observed in attenuation measurements between this experiment and a Brookhaven experiment which measured total cross sections on Pb, Sn, and Al. There have been only a few published results in which experimental values of f/sub N/(0) are given. In those cases, general agreement is obsserved with the results of this experiment

  17. Pion-nucleus forward scattering amplitudes at Δ(3,3) energies for π+---12C, 40Ca and 48Ca

    International Nuclear Information System (INIS)

    Dragoset, W.H. Jr.

    1978-01-01

    Using the LAMPF P 3 channel, small angle elastic cross sections and total cross sections were measured for π +- -- 12 C, 40 Ca and 48 Ca at incident pion kinetic energies spanning the energy region of the Δ(3,3) resonance. The sigma/sub EL/ experiment employed a spectrometer consisting of two magnets and six MWPC to measure scattering angles and momenta. For the sigma/sub T/ experiment six MWPC were positioned about the target in the beam to measure the deflection or absorption of the incident pions. Both experiments monitored the Jacobian cusp of the π → μ + ν decay to achieve absolute normalization. The two complementary data sets allowed the nuclear forward scattering amplitudes, f/sub N/(0), to be completely determined. The sigma/sub EL/ data were fit by a phenomenological small angle scattering model developed by Bethe and modified by West and Yennie. Due to the presence of nuclear-Coulomb interference in the elastic cross sections, both the magnitude and sign of Re f/sub N/ were determined by the fits. The Re f/sub N/ results were used in the sigma/sub T/ analysis to calculate corrections for the nuclear and nuclear-Coulomb interference amplitudes. Im f/sub N/ was calculated from the sigma/sub T/ results via the optical theorem. The overall self-consistencies of the data were checked by inserting IM f/sub N/ as a fixed parameter into the sigma/sub EL/ fits and comparing the resulting Re f/sub N/ to the original Re f/sub N/. It was determined that Re f/sub N/(0) has a zero near 180 MeV for both 12 C and 40 Ca. For 48 Ca, however, the Re f/sub N/ obtained by fitting with the West-Yennie formula was quite charge dependent and did not exhibit a zero in the energy range investigated. The differences in the 40 Ca, 48 Ca total cross sections were compared to a simple Kisslinger optical model calculation. The model indicated that the RMS neutron radius of 48 Ca exceeds the proton radius by 0.10 +- 0.06 fm

  18. Strain amplitude-dependent anelasticity in Cu-Ni solid solution due to thermally activated and athermal dislocation-point obstacle interactions

    Science.gov (United States)

    Kustov, S.; Gremaud, G.; Benoit, W.; Golyandin, S.; Sapozhnikov, K.; Nishino, Y.; Asano, S.

    1999-02-01

    Experimental investigations of the internal friction and the Young's modulus defect in single crystals of Cu-(1.3-7.6) at. % Ni have been performed for 7-300 K over a wide range of oscillatory strain amplitudes. Extensive data have been obtained at a frequency of vibrations around 100 kHz and compared with the results obtained for the same crystals at a frequency of ˜1 kHz. The strain amplitude dependence of the anelastic strain amplitude and the average friction stress acting on a dislocation due to solute atoms are also analyzed. Several stages in the strain amplitude dependence of the internal friction and the Young's modulus defect are revealed for all of the alloy compositions, at different temperatures and in different frequency ranges. For the 100 kHz frequency, low temperatures and low strain amplitudes (˜10-7-10-5), the amplitude-dependent internal friction and the Young's modulus defect are essentially temperature independent, and are ascribed to a purely hysteretic internal friction component. At higher strain amplitudes, a transition stage and a steep strain amplitude dependence of the internal friction and the Young's modulus defect are observed, followed by saturation at the highest strain amplitudes employed. These stages are temperature and frequency dependent and are assumed to be due to thermally activated motion of dislocations. We suggest that the observed regularities in the entire strain amplitude, temperature and frequency ranges correspond to a motion of dislocations in a two-component system of obstacles: weak but long-range ones, due to the elastic interaction of dislocations with solute atoms distributed in the bulk of the crystal; and strong short-range ones, due to the interaction of dislocations with solute atoms distributed close to dislocation glide planes. Based on these assumptions, a qualitative explanation is given for the variety of experimental observations.

  19. Structural changes of small amplitude kinetic Alfvén solitary waves due to second-order corrections

    International Nuclear Information System (INIS)

    Choi, Cheong R.

    2015-01-01

    The structural changes of kinetic Alfvén solitary waves (KASWs) due to higher-order terms are investigated. While the first-order differential equation for KASWs provides the dispersion relation for kinetic Alfvén waves, the second-order differential equation describes the structural changes of the solitary waves due to higher-order nonlinearity. The reductive perturbation method is used to obtain the second-order and third-order partial differential equations; then, Kodama and Taniuti's technique [J. Phys. Soc. Jpn. 45, 298 (1978)] is applied in order to remove the secularities in the third-order differential equations and derive a linear second-order inhomogeneous differential equation. The solution to this new second-order equation indicates that, as the amplitude increases, the hump-type Korteweg-de Vries solution is concentrated more around the center position of the soliton and that dip-type structures form near the two edges of the soliton. This result has a close relationship with the interpretation of the complex KASW structures observed in space with satellites

  20. Elastic I=3 /2 p -wave nucleon-pion scattering amplitude and the Δ (1232) resonance from Nf=2+1 lattice QCD

    DEFF Research Database (Denmark)

    Andersen, Christian Walther; Bulava, John; Hörz, Ben

    2018-01-01

    We present the first direct determination of meson-baryon resonance parameters from a scattering amplitude calculated using lattice QCD. In particular, we calculate the elastic I=3/2, p-wave nucleon-pion amplitude on a single ensemble of Nf=2+1 Wilson-clover fermions with mπ=280 MeV and mK=460 Me......V. At these quark masses, the Δ(1232) resonance pole is found close to the N-π threshold and a Breit-Wigner fit to the amplitude gives gΔNπBW=19.0(4.7) in agreement with phenomenological determinations.......We present the first direct determination of meson-baryon resonance parameters from a scattering amplitude calculated using lattice QCD. In particular, we calculate the elastic I=3/2, p-wave nucleon-pion amplitude on a single ensemble of Nf=2+1 Wilson-clover fermions with mπ=280 MeV and mK=460 Me...

  1. Problems in nonlinear acoustics: Scattering of sound by sound, parametric receiving arrays, nonlinear effects in asymmetric sound beams and pulsed finite amplitude sound beams

    Science.gov (United States)

    Hamilton, Mark F.

    1989-08-01

    Four projects are discussed in this annual summary report, all of which involve basic research in nonlinear acoustics: Scattering of Sound by Sound, a theoretical study of two nonconlinear Gaussian beams which interact to produce sum and difference frequency sound; Parametric Receiving Arrays, a theoretical study of parametric reception in a reverberant environment; Nonlinear Effects in Asymmetric Sound Beams, a numerical study of two dimensional finite amplitude sound fields; and Pulsed Finite Amplitude Sound Beams, a numerical time domain solution of the KZK equation.

  2. Scattering amplitudes and static atomic correction factors for the composition-sensitive 002 reflection in sphalerite ternary III-V and II-VI semiconductors.

    Science.gov (United States)

    Schowalter, M; Müller, K; Rosenauer, A

    2012-01-01

    Modified atomic scattering amplitudes (MASAs), taking into account the redistribution of charge due to bonds, and the respective correction factors considering the effect of static atomic displacements were computed for the chemically sensitive 002 reflection for ternary III-V and II-VI semiconductors. MASAs were derived from computations within the density functional theory formalism. Binary eight-atom unit cells were strained according to each strain state s (thin, intermediate, thick and fully relaxed electron microscopic specimen) and each concentration (x = 0, …, 1 in 0.01 steps), where the lattice parameters for composition x in strain state s were calculated using continuum elasticity theory. The concentration dependence was derived by computing MASAs for each of these binary cells. Correction factors for static atomic displacements were computed from relaxed atom positions by generating 50 × 50 × 50 supercells using the lattice parameter of the eight-atom unit cells. Atoms were randomly distributed according to the required composition. Polynomials were fitted to the composition dependence of the MASAs and the correction factors for the different strain states. Fit parameters are given in the paper.

  3. Electrical resistivity due to electron-phonon scattering in thin gadolinium films

    International Nuclear Information System (INIS)

    Urbaniak-Kucharczyk, A.

    1988-01-01

    The contribution to the electrical resistivity due to the electron-phonon scattering for the special case of h.c.p. structure is derived. The numerical results obtained for the case of polycrystalline gadolinum films show the resistivity dependence on the film thickness and the surface properties. (author)

  4. Measurements of stimulated-Raman-scattering-induced tilt in spectral-amplitude-coding optical code-division multiple-access systems

    Science.gov (United States)

    Al-Qazwini, Zaineb A. T.; Abdullah, Mohamad K.; Mokhtar, Makhfudzah B.

    2009-01-01

    We measure the stimulated Raman scattering (SRS)-induced tilt in spectral-amplitude-coding optical code-division multiple-access (SAC-OCDMA) systems as a function of system main parameters (transmission distance, power per chip, and number of users) via computer simulations. The results show that SRS-induced tilt significantly increases as transmission distance, power per chip, or number of users grows.

  5. Study of probing beam enlargement due to forward-scattering under low wavenumber turbulence using a FDTD full-wave code

    Energy Technology Data Exchange (ETDEWEB)

    Silva, F. da [Associao EURATOM/IST, IPFN-LA, Instituto Superor Tecnico, Lisbon (Portugal); Heuraux, S. [Institut Jean Lamour, CNRS-Nancy-Universite, BP70239, Vandoeuvre-les-Nancy (France); Gusakov, E.; Popov, A. [Ioffe Institute, Polytekhnicheskaya, St Petersburg (Russian Federation)

    2011-07-01

    Forward-scattering under high level of turbulence or long propagation paths can induce significant effects, as predicted by theory, and impose a signature on the Doppler reflectometry response. Simulations using a FDTD (finite-difference time-domain) full-wave code have confirmed the main dependencies and general behavior described by theory but display a returned RMS power, at moderate amplitudes, half of the one predicted by theory due to the impossibility to reach the numerical requirements needed to describe the small wavenumber spectrum with the wanted accuracy.One justifying factor may be due to the splitting and enlargement of the probing beam. At high turbulence levels, the scattered power returning to the antenna is higher than the predicted by the theory probably due to the scattered zone being closer than the oblique cutoff. This loss of coherence of the wavefront induces a beam spreading, which is also responsible for a diminution of the wavenumber resolution. With a FDTD full-wave code we study the behavior of the probing beam under several amplitude levels of low wavenumber plasma turbulence, using long temporal simulations series to ensure statistical accuracy. (authors)

  6. Locating scatterers while drilling using seismic noise due to tunnel boring machine

    Science.gov (United States)

    Harmankaya, U.; Kaslilar, A.; Wapenaar, K.; Draganov, D.

    2018-05-01

    Unexpected geological structures can cause safety and economic risks during underground excavation. Therefore, predicting possible geological threats while drilling a tunnel is important for operational safety and for preventing expensive standstills. Subsurface information for tunneling is provided by exploratory wells and by surface geological and geophysical investigations, which are limited by location and resolution, respectively. For detailed information about the structures ahead of the tunnel face, geophysical methods are applied during the tunnel-drilling activity. We present a method inspired by seismic interferometry and ambient-noise correlation that can be used for detecting scatterers, such as boulders and cavities, ahead of a tunnel while drilling. A similar method has been proposed for active-source seismic data and validated using laboratory and field data. Here, we propose to utilize the seismic noise generated by a Tunnel Boring Machine (TBM), and recorded at the surface. We explain our method at the hand of data from finite-difference modelling of noise-source wave propagation in a medium where scatterers are present. Using the modelled noise records, we apply cross-correlation to obtain correlation gathers. After isolating the scattered arrivals in these gathers, we cross-correlate again and invert for the correlated traveltime to locate scatterers. We show the potential of the method for locating the scatterers while drilling using noise records due to TBM.

  7. Non-Markovian dynamics of a qubit due to single-photon scattering in a waveguide

    Science.gov (United States)

    Fang, Yao-Lung L.; Ciccarello, Francesco; Baranger, Harold U.

    2018-04-01

    We investigate the open dynamics of a qubit due to scattering of a single photon in an infinite or semi-infinite waveguide. Through an exact solution of the time-dependent multi-photon scattering problem, we find the qubit's dynamical map. Tools of open quantum systems theory allow us then to show the general features of this map, find the corresponding non-Linbladian master equation, and assess in a rigorous way its non-Markovian nature. The qubit dynamics has distinctive features that, in particular, do not occur in emission processes. Two fundamental sources of non-Markovianity are present: the finite width of the photon wavepacket and the time delay for propagation between the qubit and the end of the semi-infinite waveguide.

  8. Suppression of Quasiparticle Scattering Signals in Bilayer Graphene Due to Layer Polarization and Destructive Interference.

    Science.gov (United States)

    Jolie, Wouter; Lux, Jonathan; Pörtner, Mathias; Dombrowski, Daniela; Herbig, Charlotte; Knispel, Timo; Simon, Sabina; Michely, Thomas; Rosch, Achim; Busse, Carsten

    2018-03-09

    We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scattering between electronic states (both intraband and interband) is detected via quasiparticle interference. However, not all expected processes are visible in our experiment. We uncover two general effects causing this suppression: first, intercalation leads to an asymmetrical distribution of the states within the two layers, which significantly reduces the scanning tunneling spectroscopy signal of standing waves mainly present in the lower layer; second, forward scattering processes, connecting points on the constant energy contours with parallel velocities, do not produce pronounced standing waves due to destructive interference. We present a theory to describe the interference signal for a general n-band material.

  9. Suppression of Quasiparticle Scattering Signals in Bilayer Graphene Due to Layer Polarization and Destructive Interference

    Science.gov (United States)

    Jolie, Wouter; Lux, Jonathan; Pörtner, Mathias; Dombrowski, Daniela; Herbig, Charlotte; Knispel, Timo; Simon, Sabina; Michely, Thomas; Rosch, Achim; Busse, Carsten

    2018-03-01

    We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scattering between electronic states (both intraband and interband) is detected via quasiparticle interference. However, not all expected processes are visible in our experiment. We uncover two general effects causing this suppression: first, intercalation leads to an asymmetrical distribution of the states within the two layers, which significantly reduces the scanning tunneling spectroscopy signal of standing waves mainly present in the lower layer; second, forward scattering processes, connecting points on the constant energy contours with parallel velocities, do not produce pronounced standing waves due to destructive interference. We present a theory to describe the interference signal for a general n -band material.

  10. Scattering factor evaluation for internal dose assessment due to 60Co

    International Nuclear Information System (INIS)

    Gautam, Y.P.; Kumar, A.; Sharma, S.; Sharma, A.K.; Dube, B.; Hegde, A.G.

    2008-01-01

    Guidelines for the assessment of internal doses from monitoring suggest default measurement of uncertainties (i.e. lognormal scattering factor, SF) to be used for different types of monitoring data. In this paper, SF values have been evaluated for internal contamination due to 60 Co in two cases using whole body counting data. SF values of 1.04 and 1.03 were obtained for case I and II respectively while SF value of 1.03 was obtained using bioassay data for case I. SF evaluated is in good agreement with the default values given by IDEAS guidelines. (author)

  11. H(10) due to radiation scattered in a 6 MV Linac for tomotherapy

    International Nuclear Information System (INIS)

    Vega C, H. R.; Esparza H, A.; Garcia R, M. G.; Reyes R, E.; Hernandez A, L.; Rivera, T.

    2017-10-01

    In order to determine the environmental equivalent dose (H(10)), due to the radiation that is dispersed over the body of a patient, 100 thermoluminescent dosimeters (TLD) around 6 MV TomoLINAC were used. The characteristics of the tomotherapy have the disadvantage that the shielding of the bunker increases considerably and for its design validated parameters are used for the conventional Linacs. In order to determine H(10) due to scattered radiation, measurements were made in the vicinity of the isocenter, while the 6 MeV photon beam was applied on a phantom. Also, TLDs were placed on the walls of the bunker that remained for 7 days, where approximately 50 patients were treated per day. At points close to the isocenter, the H(10) has an angular distribution caused by the phantom shape. In the bunker walls the highest H(10) was observed in the primary barriers. In the labyrinth, the impact of the scattered radiation was observed when measuring a greater value of the environmental equivalent dose in the wall furthest from the isocenter compared to the point located closest to it. (Author)

  12. K/sup 0//sub L/ interactions at 550 MeV/c. [Phase shift, scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Y; Derrick, M; Miller, R J; Smith, R P [Argonne National Lab., Ill. (USA); Engler, A; Keyes, G; Kraemer, R W; Schlereth, J; Tanaka, M [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

    1976-01-19

    Differential and channel cross sections and hyperon polarizations are presented for the reactions K/sub L//sup 0/p..-->..K/sub S//sup 0/p, ..pi../sup +/..lambda../sup 0/, and ..pi../sup +/..sigma../sup 0/ at an average beam momentum of 550 MeV/c. These data provide constraints on KN and anti KN amplitudes obtained from charged kaon reactions and reject one of the S=+1,I=0 and one of the S=-1,I=1 phase shift solutions.

  13. Multi-modal vibration amplitudes of taut inclined cables due to direct and/or parametric excitation

    Science.gov (United States)

    Macdonald, J. H. G.

    2016-02-01

    Cables are often prone to potentially damaging large amplitude vibrations. The dynamic excitation may be from external loading or motion of the cable ends, the latter including direct excitation, normally from components of end motion transverse to the cable, and parametric excitation induced by axial components of end motion causing dynamic tension variations. Geometric nonlinearity can be important, causing stiffening behaviour and nonlinear modal coupling. Previous analyses of the vibrations, often neglecting sag, have generally dealt with direct and parametric excitation separately or have reverted to numerical solutions of the responses. Here a nonlinear cable model is adopted, applicable to taut cables such as on cable-stayed bridges, that allows for cable inclination, small sag (such that the vibration modes are similar to those of a taut string), multiple modes in both planes and end motion and/or external forcing close to any natural frequency. Based on the method of scaling and averaging it is found that, for sinusoidal inputs and positive damping, non-zero steady state responses can only occur in the modes in each plane with natural frequencies close to the excitation frequency and those with natural frequencies close to half this frequency. Analytical solutions, in the form of non-dimensional polynomial equations, are derived for the steady state vibration amplitudes in up to three modes simultaneously: the directly excited mode, the corresponding nonlinearly coupled mode in the orthogonal plane and a parametrically excited mode with half the natural frequency. The stability of the solutions is also identified. The outputs of the equations are consistent with previous results, where available. Example results from the analytical solutions are presented for a typical inclined bridge cable subject to vertical excitation of the lower end, and they are validated by numerical integration of the equations of motion and against some previous experimental

  14. The AKM theorem and oscillations in the hadron scattering amplitude at high energy and small momentum transfer

    Energy Technology Data Exchange (ETDEWEB)

    Gauron, P.; Nicolescu, B. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Selyugin, O.V. [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Bogoliubov Lab. of Theoretical Physics

    1996-10-01

    It is shown that the high precision UA4/2 data for differential cross sections p-barp scattering are compatible with the presence of Auberson -Kinoshita - Martin (AKM) type of oscillations at very small momentum transfers. These oscillations seem to be periodic in {radical}|t|. The existence of such visible oscillations suggests a general mechanism of saturation of axiomatic bounds. As an illustration the consequences for extracting the parameter {rho} = ReF/ImF from dN/dt data are also discussed. (K.A.). 19 refs.

  15. Rigorous lower bounds on the imaginary parts of the scattering amplitudes and the positions of their zeros

    CERN Document Server

    Uchiyama, T

    1974-01-01

    Rigorous lower bounds are derived from axiomatic field theory, by invoking analyticity and unitarity of the S-matrix. The bounds are expressed in terms of the total cross section and the slope parameter, and are found to be compatible with CERN experimental pp scattering data. It is also shown that the calculated lower-bound values imply non-existence of zeros for -t

  16. Measurement of the real part of the forward scattering amplitude in K/sup + -/p elastic scattering at 10. 4 and 14 GeV/c. [Differential cross sections, interference, coulomb and nuclear interactions

    Energy Technology Data Exchange (ETDEWEB)

    Carnegie, R K; Cashmore, R J; Davier, M; Leith, D W.G.S.; Richard, F; Schacht, P; Walden, P; Williams, S H [Stanford Linear Accelerator Center, Calif. (USA)

    1975-11-10

    The differential cross section for K/sup + -/p elastic scattering has been measured in the very low t region (0.003scattering amplitude. At 10.4 GeV/c the authors measure ..cap alpha..(K/sup +/p)=-0.21+-0.06 and ..cap alpha..(K/sup -/p)=0.08+-0.04, and at 14 GeV/c, ..cap alpha..(K/sup +/p)=-0.13+-0.03 and ..cap alpha..(K/sup -/p)=0.00+-0.04 in agreement with the predictions of dispersion theory calculations.

  17. Elastic scattering of. pi. /sup -/ mesons on protons in the Coulomb-nuclear interference region at 33-60 GeV/c. [Total and differential cross sections,scattering amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Apokin, V D; Vasiliev, A N; Derevshchikov, A A; Matulenko, Yu A; Meschanin, A P; Mysnik, A I; Nurushev, S B; Saraykin, A I; Siksin, V V; Smirnov, E V [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Serpukhov. Inst. Fiziki Vysokikh Ehnergij

    1976-04-19

    Differential cross sections for the elastic scattering of negative pions on protons, as well as total cross sections have been measured for the incident momentum range from 33 up to 60 GeV/c. The values for four-momentum transfer were within the limits of -(10/sup -3/-8x10/sup -2/) (GeV/c)/sup 2/. The energy dependence of the ratio rho(0) of the real part of the forward elastic scattering amplitude to the imaginary part has been determined from the experimental data. The magnitude rho(0) smoothly increases from (-10.9+-1.2)% at momenta 33.52 GeV/c up to (-1.8+-1.8)% at 59.4 GeV/c. The results obtained are compared with the predictions of theoretical models.

  18. Polarization due to dust scattering in the planetary nebula Cn1-1

    International Nuclear Information System (INIS)

    Bhatt, H.C.

    1989-01-01

    The peculiar emission-line object Cn1-1 (=HDE330036=PK330+4 degrees 1), classified both as a symbiotic star and as a planetary nebula, was detected by the Infrared Astronomical Satellite (IRAS) as a strong source of far-infrared dust in the system. Bhatt and Mallik (1986) discussed the nature of the dust in Cn1-1 and argued that the object is a Type I protoplanetary nebula in a binary system. The argument presented here is that the polarization is intrinsic to Cn1-1 and is due to scattering by large (compared to interstellar) dust grains in the protoplanetary nebula that are asymmetrically distributed around the central star. The large degree of polarization (approximately 3 percent for the Cn1-1 distance of approximately 450 pc) with a large lambda(sub max) is naturally explained if it is caused by scattering by large dust grains in the Cn1-1 nebula. Since the H(sub alpha) line is also polarized at the same level and position angle as the continuum, the dust must be asymmetrically distributed around the central star. The morphology of the protoplanetary nebula in Cn1-1 may be bipolar. Thus, the polarization observations support the suggestion that Cn1-1 is a bipolar Type I planetary nebula

  19. Doubly-logarithmic asymptotic of the quark scattering amplitude with nonvacuum exchange in the t-channel

    International Nuclear Information System (INIS)

    Kirschner, R.; Lipatov, L.N.

    1982-01-01

    Nonlinear differential equations of the Riccati type for the t-channel partial waves f/sub j/(t) describing the scattering of quarks on the mass shell are derived by employing the dispersion relations. The derivation applies to high energies s/sup 1/2/ in the region α/sub s/ln 2 (s/μ 2 )approx.1, where μ is the infrared cutoff parameter with respect to the transverse momenta of the virtual particles. For colorless channels the solutions are found in explicit form. It is shown that the singularities of partial waves with negative signature are in all cases located to the right of the singularities of partial waves with positive signature, i.e., the negative signature dominates in the asymptotic region α/sub s/ln 2 (s/μ 2 )>>1

  20. Chirality in Magnetic Multilayers Probed by the Symmetry and the Amplitude of Dichroism in X-Ray Resonant Magnetic Scattering

    Science.gov (United States)

    Chauleau, Jean-Yves; Legrand, William; Reyren, Nicolas; Maccariello, Davide; Collin, Sophie; Popescu, Horia; Bouzehouane, Karim; Cros, Vincent; Jaouen, Nicolas; Fert, Albert

    2018-01-01

    Chirality in condensed matter has recently become a topic of the utmost importance because of its significant role in the understanding and mastering of a large variety of new fundamental physical mechanisms. Versatile experimental approaches, capable to reveal easily the exact winding of order parameters, are therefore essential. Here we report x-ray resonant magnetic scattering as a straightforward tool to reveal directly the properties of chiral magnetic systems. We show that it can straightforwardly and unambiguously determine the main characteristics of chiral magnetic distributions: i.e., its chiral nature, the quantitative winding sense (clockwise or counterclockwise), and its type, i.e., Néel [cycloidal] or Bloch [helical]. This method is model independent, does not require a priori knowledge of the magnetic parameters, and can be applied to any system with magnetic domains ranging from a few nanometers (wavelength limited) to several microns. By using prototypical multilayers with tailored magnetic chiralities driven by spin-orbit-related effects at Co |Pt interfaces, we illustrate the strength of this method.

  1. Fermion-boson scattering in ladder approximation

    International Nuclear Information System (INIS)

    Jafarov, R.G.; Hadjiev, S.A.

    1992-10-01

    A method of calculation of forward scattering amplitude for fermions and scalar bosons with exchanging of scalar particle is suggested. The Bethe-Salpeter ladder equation for the imaginary part of the amplitude is constructed and a solution in Regge asymptotical form is found and the corrections to the amplitude due to the exit from mass shell are calculated. (author). 8 refs

  2. Correlation in atomic scattering

    International Nuclear Information System (INIS)

    McGuire, J.H.

    1987-01-01

    Correlation due to the Coulomb interactions between electrons in many-electron targets colliding with charged particles is formulated, and various approximate probability amplitudes are evaluated. In the limit that the electron-electron, 1/r/sub i//sub j/, correlation interactions are ignored or approximated by central potentials, the independent-electron approximation is obtained. Two types of correlations, or corrections to the independent-electron approximation due to 1/r/sub i//sub j/ terms, are identified: namely, static and scattering correlation. Static correlation is that contained in the asymptotic, e.g., bound-state, wave functions. Scattering correlation, arising from correlation in the scattering operator, is new and is considered in some detail. Expressions for a scattering correlation amplitude, static correlation or rearrangement amplitude, and independent-electron or direct amplitude are derived at high collision velocity and compared. At high velocities the direct and rearrangement amplitudes dominate. At very high velocities, ν, the rearrangement amplitude falls off less rapidly with ν than the direct amplitude which, however, is dominant as electron-electron correlation tends to zero. Comparisons with experimental observations are discussed

  3. Point spread function due to multiple scattering of light in the atmosphere

    International Nuclear Information System (INIS)

    Pękala, J.; Wilczyński, H.

    2013-01-01

    The atmospheric scattering of light has a significant influence on the results of optical observations of air showers. It causes attenuation of direct light from the shower, but also contributes a delayed signal to the observed light. The scattering of light therefore should be accounted for, both in simulations of air shower detection and reconstruction of observed events. In this work a Monte Carlo simulation of multiple scattering of light has been used to determine the contribution of the scattered light in observations of a point source of light. Results of the simulations and a parameterization of the angular distribution of the scattered light contribution to the observed signal (the point spread function) are presented. -- Author-Highlights: •Analysis of atmospheric scattering of light from an isotropic point source. •Different geometries and atmospheric conditions were investigated. •A parameterization of scattered light distribution has been developed. •The parameterization allows one to easily account for the light scattering in air. •The results will be useful in analyses of observations of extensive air shower

  4. Phonon scattering by isotopic impurities

    International Nuclear Information System (INIS)

    Dacol, D.K.

    1974-06-01

    The effects upon vibrations of a perfect crystal lattice due to the replacement of some of its atoms by isotopes of these atoms are studied. The approach consists in considering the isotopic impurities as scattering centres for the quanta of the elastic waves the objective is to obtain the scattering amplitudes. These amplitudes are obtained through a canonical transformation method which was introduced by Chevalier and Rideau in the study of the Wentzel's model in quantum field theory

  5. Beam loss due to the aperture limitation resulting from intrabeam scattering

    International Nuclear Information System (INIS)

    Lee, S.Y.

    1984-01-01

    Diffusion equation is used to evaluate the beam loss in the presence of aperture limitation resulting from the intrabeam scattering. We discuss the effect of different boundary conditions. Satisfactory beam intensity can be maintained within the proposed RHIC operation time

  6. Measurement of the real part of the forward scattering amplitude by means of the Coulomb-nuclear interference in πsup(+-)p and Ksup(+-)p elastic scattering at incident momenta below 3 GeV/c

    International Nuclear Information System (INIS)

    Baillon, P.; Bricman, C.; Ferro-Luzzi, M.; Jenni, P.; Perreau, J.M.; Tripp, R.D.; Ypsilantis, T.; Declais, Y.; Seguinot, J.

    1975-01-01

    The differential cross sections for π + p elastic scattering at 0.6, 1.0, 1.5, 2.0 GeV/c, for π - p at 1.0, 1.5, 2.0 GeV/c, for K + p at 1.2, 1.8, 2.6 GeV/c and for K - p at 0.9, 1.2, 1.4, 1.6, 1.8, 2.6 GeV/c have been measured with an overall accuracy of the order of 1 to 2 per cent in a counter experiment over the angular region corresponding to momentum transfers t between 0.0005 and 0.10 GeV 2 . Making use of the interference effects between the Coulomb and the nuclear interaction, a determination has been done of the magnitude and sign of the real part of the scattering amplitude near t = 0. The πp real parts are compared to the values predicted by the dispersion relations and found to agree quite well. The Ksup(+-)p real parts have been used in a dispersion relation to derive the value of the KNA coupling constant. Two possible values of this coupling constant are found, both much larger than those commonly accepted. One of them agrees well with the value predicted by the SU(3) and SU(6) symmetry schemes. (Author)

  7. Problem of determination of the elementary hardon-nucleon interaction amplitude from Glauber-theory analysis of elastic hardon-nucleus scattering and self-consistent FFS nuclear densities

    International Nuclear Information System (INIS)

    Saperstein, E.E.

    1992-01-01

    The influence of the detailed behavior of the nuclear densities on the Glauber-theory description of hadron-nucleus scattering is discussed in connection with the problem of determination of elementary hadron-nucleon amplitudes from such analysis. Arguments are given in favor of using the self-consistent FFS nuclear densities for this purpose. 20 refs., 6 figs

  8. SCATTER

    International Nuclear Information System (INIS)

    Broome, J.

    1965-11-01

    The programme SCATTER is a KDF9 programme in the Egtran dialect of Fortran to generate normalized angular distributions for elastically scattered neutrons from data input as the coefficients of a Legendre polynomial series, or from differential cross-section data. Also, differential cross-section data may be analysed to produce Legendre polynomial coefficients. Output on cards punched in the format of the U.K. A. E. A. Nuclear Data Library is optional. (author)

  9. Improved extraction of two-photon exchange amplitudes from elastic electron-proton scattering cross section data up to Q2=5.20 (GeV/c ) 2

    Science.gov (United States)

    Qattan, I. A.; Homouz, D.; Riahi, M. K.

    2018-04-01

    In this work, we improve on and extend to low- and high-Q2 values the extractions of the two-photon-exchange (TPE) amplitudes and the ratio Pl/PlBorn(ɛ ,Q2) using world data on electron-proton elastic scattering cross section σR(ɛ ,Q2) with an emphasis on data covering the high-momentum region, up to Q2=5.20 (GeV/c ) 2 , to better constrain the TPE amplitudes in this region. We provide a new parametrization of the TPE amplitudes, along with an estimate of the fit uncertainties. We compare the results to several previous phenomenological extractions and hadronic TPE predictions. We use the new parametrization of the TPE amplitudes to extract the ratio Pl/PlBorn(ɛ ,Q2) , and then compare the results to previous extractions, several theoretical calculations, and direct measurements at Q2=2.50 (GeV/c ) 2 .

  10. Intrinsic Patterns of Coupling between Correlation and Amplitude of Low-Frequency fMRI Fluctuations Are Disrupted in Degenerative Dementia Mainly due to Functional Disconnection

    Science.gov (United States)

    Mascali, Daniele; DiNuzzo, Mauro; Gili, Tommaso; Moraschi, Marta; Fratini, Michela; Maraviglia, Bruno; Serra, Laura; Bozzali, Marco; Giove, Federico

    2015-01-01

    Low frequency fluctuations (LFFs) of the BOLD signal are a major discovery in the study of the resting brain with functional magnetic resonance imaging (fMRI). Two fMRI-based measures, functional connectivity (FC), a measure of signal synchronicity, and the amplitude of LFFs (ALFF), a measure of signal periodicity, have been proved to be sensitive to changes induced by several neurological diseases, including degenerative dementia. In spite of the increasing use of these measures, whether and how they are related to each other remains to be elucidated. In this work we used voxel-wise FC and ALFF computed in different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.073 Hz; and full-band: 0.01-0.073 Hz), in order to assess their relationship in healthy elderly as well as the relevant changes induced by Alzheimer’s Disease (AD) and Mild Cognitive Impairment (MCI). We found that in healthy elderly subjects FC and ALFF are positively correlated in anterior and posterior cingulate cortex (full-band, slow-4 and slow-5), temporal cortex (full-band and slow-5), and in a set of subcortical regions (full-band and slow-4). These correlation patterns between FC and ALFF were absent in either AD or MCI patients. Notably, the loss of correlation between FC and ALFF in the AD group was primarily due to changes in FC rather than in ALFF. Our results indicate that degenerative dementia is characterized by a loss of global connection rather than by a decrease of fluctuation amplitude. PMID:25844531

  11. Study of elastic pion scattering from /sup 9/Be, /sup 28/Si, /sup 58/Ni, and /sup 208/Pb at 162 MeV. [Total and differential cross sections, scattering yields, scattering amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Devereux, M.J.

    1979-05-01

    Elastic pion scattering from /sup 9/Be, /sup 28/Si, /sup 58/Ni, and /sup 208/Pb at 162 MeV is analyzed and compared with an optical model theory which incorporates a pion--nucleon range. Excellent fits to the data are obtained in all but one case. The fitted values of the pion--nucleon range, as well as other fitted values are listed. 108 references.

  12. Enhancement of the incoherent scattering plasma lines due to precipitating protons and secondary electrons

    International Nuclear Information System (INIS)

    Bjoernaa, N.; Havnes, O.; Jensen, J.O.; Trulsen, J.

    1982-01-01

    Precipitating protons in the energy range 1-100 keV are regularly present in the auroral ionosphere. These protons will produce enhancements in the intensity of the upshifted plasma line of the incoherently scattered spectrum. Similarly, secondary electrons produced by the precipitating protons give rise to enhanced plasma line intensities. For a quantitative discussion of these effects an experimentally measured proton flux is adapted and the corresponding secondary electron flux calculated. These particle fluxes are then applied in connection with the EISCAT radar facility. Both fluxes give rise to enhancements of the order of 20. It is possible to separate between proton and electron contributions to the enhanced plasma lines for scattering heights above the source region of secondary electrons. (Auth.)

  13. Resistivity scaling due to electron surface scattering in thin metal layers

    Science.gov (United States)

    Zhou, Tianji; Gall, Daniel

    2018-04-01

    The effect of electron surface scattering on the thickness-dependent electrical resistivity ρ of thin metal layers is investigated using nonequilibrium Green's function density functional transport simulations. Cu(001) thin films with thickness d =1 -2 nm are used as a model system, employing a random one-monolayer-high surface roughness and frozen phonons to cause surface and bulk scattering, respectively. The zero-temperature resistivity increases from 9.7 ±1.0 μ Ω cm at d =1.99 nm to 18.7 ±2.6 μ Ω cm at d =0.9 0 nm, contradicting the asymptotic T =0 prediction from the classical Fuchs-Sondheimer model. At T =9 00 K, ρ =5.8 ±0.1 μ Ω cm for bulk Cu and ρ =13.4 ±1.1 and 22.5 ±2.4 μ Ω cm for layers with d =1.99 and 0.90 nm, respectively, indicating an approximately additive phonon contribution which, however, is smaller than for bulk Cu or atomically smooth layers. The overall data indicate that the resistivity contribution from surface scattering is temperature-independent and proportional to 1 /d , suggesting that it can be described using a surface-scattering mean-free path λs for 2D transport which is channel-independent and proportional to d . Data fitting indicates λs=4 ×d for the particular simulated Cu(001) surfaces with a one-monolayer-high surface roughness. The 1 /d dependence deviates considerably from previous 1 /d2 predictions from quantum models, indicating that the small-roughness approximation in these models is not applicable to very thin (<2 nm) layers, where the surface roughness is a considerable fraction of d .

  14. Theoretical evaluation of self-shielding factors due to scattering resonances in foils

    International Nuclear Information System (INIS)

    Selander, W.N.

    1960-06-01

    A semi-analytical method is given for evaluating self-shielding factors for activation measurements which use thin foils having neutron scattering resonances. The energy loss by scattering in the foil is taken into account. The energy-dependent neutron angular distribution is expanded as a double series, the coefficients of which are (energy dependent) solutions of an infinite set of coupled integral equations. These are truncated in some suitable manner and solved numerically. The leading term of the series is proportional to the average, or effective flux in the activation sample. The product of this terra and the neutron capture cross-section is integrated numerically over the resonance to give the resonance self-shielding correction. Figure 4 shows resonance self-shielding factors derived in this mariner for the 132ev resonance in Co-59 and figure 5 shows similar results for the two Mn-55 resonances at 337ev and 1080ev. Self-shielding factors for 1/v capture are not significantly different from unity. (author)

  15. Phononic thermal resistance due to a finite periodic array of nano-scatterers

    Energy Technology Data Exchange (ETDEWEB)

    Trang Nghiêm, T. T.; Chapuis, Pierre-Olivier [Univ. Lyon, CNRS, INSA-Lyon, Université Claude Bernard Lyon 1, CETHIL UMR5008, F-69621 Villeurbanne (France)

    2016-07-28

    The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects that are both subject to reciprocity. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the 5–100 K temperature range. It is observed that the associated thermal conductance has the same temperature dependence as that without phononic filtering.

  16. Errors due to random noise in velocity measurement using incoherent-scatter radar

    Directory of Open Access Journals (Sweden)

    P. J. S. Williams

    1996-12-01

    Full Text Available The random-noise errors involved in measuring the Doppler shift of an 'incoherent-scatter' spectrum are predicted theoretically for all values of Te/Ti from 1.0 to 3.0. After correction has been made for the effects of convolution during transmission and reception and the additional errors introduced by subtracting the average of the background gates, the rms errors can be expressed by a simple semi-empirical formula. The observed errors are determined from a comparison of simultaneous EISCAT measurements using an identical pulse code on several adjacent frequencies. The plot of observed versus predicted error has a slope of 0.991 and a correlation coefficient of 99.3%. The prediction also agrees well with the mean of the error distribution reported by the standard EISCAT analysis programme.

  17. Reduced thermal conductivity due to scattering centers in p-type SiGe alloys

    International Nuclear Information System (INIS)

    Beaty, J.S.; Rolfe, J.L.; Vandersande, J.; Fleurial. J.P.

    1992-01-01

    This paper reports that a theoretical model has been developed that predicts that the addition of ultra-fine, inert, phonon-scattering centers to SiGe thermoelectric material will reduce its thermal conductivity and improve its figure-of-merit. To investigate this prediction, ultra-fine particulates (20 Angstrom to 200 Angstrom) of boron nitride have been added to boron doped, p-type, 80/20 SiGe. All previous SiGe samples produced from ultra-fine SiGe powder without additions had lower thermal conductivities than standard SiGe, but high temperature (1525 K) heat treatment increased their thermal conductivity back to the value for standard SiGe. Transmission Electron Microscopy has been used to confirm the presence of occluded particulates and X-ray diffraction has been used to determine the composition to be BN

  18. Energy and Momentum Relaxation Times of 2D Electrons Due to Near Surface Deformation Potential Scattering

    Science.gov (United States)

    Pipa, Viktor; Vasko, Fedor; Mitin, Vladimir

    1997-03-01

    The low temperature energy and momentum relaxation rates of 2D electron gas placed near the free or clamped surface of a semi-infinit sample are calculated. To describe the electron-acoustic phonon interaction with allowance of the surface effect the method of elasticity theory Green functions was used. This method allows to take into account the reflection of acoustic waves from the surface and related mutual conversion of LA and TA waves. It is shown that the strength of the deformation potential scattering at low temperatures substantially depends on the mechanical conditions at the surface: relaxation rates are suppressed for the free surface while for the rigid one the rates are enhanced. The dependence of the conductivity on the distance between the 2D layer and the surface is discussed. The effect is most pronounced in the range of temperatures 2 sl pF < T < (2 hbar s_l)/d, where pF is the Fermi momentum, sl is the velocity of LA waves, d is the width of the quantum well.

  19. Velocity-space diffusion due to resonant wave-wave scattering of electromagnetic and electrostatic waves in a plasma

    International Nuclear Information System (INIS)

    Sugaya, Reija

    1991-01-01

    The velocity-space diffusion equation describing distortion of the velocity distribution function due to resonant wave-wave scattering of electromagnetic and electrostatic waves in an unmagnetized plasma is derived from the Vlasov-Maxwell equations by perturbation theory. The conservation laws for total energy and momentum densities of waves and particles are verified, and the time evolutions of the energy and momentum densities of particles are given in terms of the nonlinear wave-wave coupling coefficient in the kinetic wave equation. (author)

  20. Off-shell CHY amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Lam, C.S., E-mail: Lam@physics.mcgill.ca [Department of Physics, McGill University, Montreal, Q.C., H3A 2T8 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Yao, York-Peng, E-mail: yyao@umich.edu [Department of Physics, The University of Michigan Ann Arbor, MI 48109 (United States)

    2016-06-15

    The Cachazo–He–Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.

  1. Neutron scattering cross sections for 204,206Pb and neutron and proton amplitudes of E2 and E3 excitations

    International Nuclear Information System (INIS)

    Hicks, S.F.; Hanly, J.M.; Hicks, S.E.; Shen, G.R.; McEllistrem, M.T.

    1994-01-01

    Differential elastic and inelastic scattering cross sections have been measured for neutrons incident on 204 Pb and 206 Pb at energies of 2.5, 4.6, and 8.0 MeV and total cross sections in 100-keV steps from 250 keV to 4.0 MeV. Both spherical and coupled-channels analyses have been used to interpret this large set of data, together with other cross sections extending to 8 MeV. Several purposes motivate this work. The first is to establish the dispersion-corrected mean field appropriate for these nuclei. A consistent description of the energy dependent neutron scattering potential includes a dispersion relation connecting the real and imaginary parts of the potential; the resultant potential relates the energy dependent scattering field to one representing bound single particle levels. Dispersion relations using both the single channel and coupled-channels models have been examined; both give very similar results. The second motivation is to deduce neutron and proton excitation strengths of the lowest-energy quadrupole and octupole excitations seen via neutron scattering, and to compare those strengths with similar values derived from electromagnetic exciton, heavy-ion and pion scattering. The role of target neutrons in both collective excitations was found to be enhanced compared to the proton role

  2. Spectral Dependent Degradation of the Solar Diffuser on Suomi-NPP VIIRS Due to Surface Roughness-Induced Rayleigh Scattering

    Directory of Open Access Journals (Sweden)

    Xi Shao

    2016-03-01

    Full Text Available The Visible Infrared Imaging Radiometer Suite (VIIRS onboard Suomi National Polar Orbiting Partnership (SNPP uses a solar diffuser (SD as its radiometric calibrator for the reflective solar band calibration. The SD is made of Spectralon™ (one type of fluoropolymer and was chosen because of its controlled reflectance in the Visible/Near-Infrared/Shortwave-Infrared region and its near-Lambertian reflectance property. On-orbit changes in VIIRS SD reflectance as monitored by the Solar Diffuser Stability Monitor showed faster degradation of SD reflectance for 0.4 to 0.6 µm channels than the longer wavelength channels. Analysis of VIIRS SD reflectance data show that the spectral dependent degradation of SD reflectance in short wavelength can be explained with a SD Surface Roughness (length scale << wavelength based Rayleigh Scattering (SRRS model due to exposure to solar UV radiation and energetic particles. The characteristic length parameter of the SD surface roughness is derived from the long term reflectance data of the VIIRS SD and it changes at approximately the tens of nanometers level over the operational period of VIIRS. This estimated roughness length scale is consistent with the experimental result from radiation exposure of a fluoropolymer sample and validates the applicability of the Rayleigh scattering-based model. The model is also applicable to explaining the spectral dependent degradation of the SDs on other satellites. This novel approach allows us to better understand the physical processes of the SD degradation, and is complementary to previous mathematics based models.

  3. Two-Loop Splitting Amplitudes

    International Nuclear Information System (INIS)

    Bern, Z.

    2004-01-01

    Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

  4. Two-loop splitting amplitudes

    International Nuclear Information System (INIS)

    Bern, Z.; Dixon, L.J.; Kosower, D.A.

    2004-01-01

    Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

  5. The measurement of the real part of the proton-antiproton elastic scattering amplitude at a C.M.S. energy of 546 GEV and the rise of the total cross section

    International Nuclear Information System (INIS)

    Kluit, P.M.

    1988-01-01

    The subject of this thesis is the experimental study of the elastic scattering of protons and anti-protons at a centre of mass energy of 546 GeV at the SPS (Super Proton Synchrotron) at CERN. The measurement of ρ, i.e. the ratio of the real to the imaginary part of the nuclear part of elastic scattering amplitude for proton-antiproton at zero momentum transfer squared (-t = 0 GeV 2 ), at a centre of mass energy of √s = 546 GeV is described. The implications of the result of this measurement for the behaviour of the total cross section in the TeV domain are derived. The hypothesis is investigated whether there is a relation between the rise of the total cross section and the rise of the total jet cross section, as calculated in perturbative QCD and observed by the UA1 experiment. 104 refs.; 40 figs.; 16 tabs

  6. Spectral and far-field broadening due to stimulated rotational Raman scattering driven by the Nike krypton fluoride laser.

    Science.gov (United States)

    Weaver, James; Lehmberg, Robert; Obenschain, Stephen; Kehne, David; Wolford, Matthew

    2017-11-01

    Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248  nm) has been observed at the Nike laser over extended propagation paths in air during high power operation. Although this phenomenon is not significant for standard operating configurations at Nike, broadening of the laser spectrum and far-field focal profiles has been observed once the intensity-path length product exceeds a threshold of approximately 1  TW/cm. This paper presents experimental results and a new theoretical evaluation of these effects. The observations suggest that significantly broader spectra can be achieved with modest degradation of the final focal distribution. These results point to a possible path for enhanced laser-target coupling with the reduction of laser-plasma instabilities due to broad laser bandwidth produced by the SRRS.

  7. Ordinary mode reflectometry. Modification of the scattering and cut-off responses due to the shape of localized density fluctuations

    International Nuclear Information System (INIS)

    Fanack, C.; Boucher, I.; Heuraux, S.; Leclert, G.; Clairet, F.; Zou, X.L.

    1996-01-01

    Ordinary wave reflectometry in a plasma containing a localized density perturbation is studied with a 1-D model. The phase response is studied as a function of the wavenumber and position of the perturbation. It is shown that it strongly depends upon the perturbation shape and size. For a small perturbation wavenumber, the response is due to the oscillation of the cut-off layer. For larger wavenumbers, two regimes are found: for a broad perturbation, the phase response is an image of the perturbation itself; for a narrow perturbation, it is rather an image of the Fourier transform. For tokamak plasmas it turns out that, for the fluctuation spectra usually observed, the phase response comes primarily from those fluctuations that are localized at the cut-off. Results of a 2-D numerical model show that geometry effects are negligible for the scattering by radial fluctuations. (author)

  8. Non-eikonal effects in high-energy scattering IV. Inelastic scattering

    International Nuclear Information System (INIS)

    Gurvitz, S.A.; Kok, L.P.; Rinat, A.S.

    1978-01-01

    Amplitudes of inelastically scattered high-energy projections were calculated. In the scattering on 12 C(Tsub(P)=1 GeV) sizeable non-eikonal corrections in diffraction extrema even for relatively small q 2 are demonstrated. At least part of the anomaly in the 3 - distribution may be due to these non-eikonal effects. (B.G.)

  9. Analyses and Simulation of 3D Scattering Due to Heterogeneous Crustal Structure and Surface Topography on Regional Phases, Magnitude Discrimination

    National Research Council Canada - National Science Library

    Pitarka, Arban; Helmberger, Don V; Ni, Sidao

    2008-01-01

    ... into ongoing research for the development of simple empirical models of scattering that can be used in reducing the scatter in measures of Lg and coda wave magnitude and for discrimination purposes as well...

  10. Dosimetric perturbation due to scattered rays released by a gold marker used for tumor tracking in external radiotherapy

    International Nuclear Information System (INIS)

    Habara, Kosaku; Furukawa, Takashi; Shimozato, Tomohiro; Obata, Yasunori; Aoyama, Yuichi; Kawanami, Ryota; Hayashi, Naoki; Yasui, Keisuke; Matsuura, Kanji

    2011-01-01

    Image-guided radiation therapy using a gold marker-based tumor tracking technique provides precise patient setup and monitoring. However, the marker consists of high-Z material, and the resulting scattered rays tend to have adverse effects on the dose distribution of radiotherapy. The purpose of this study was to evaluate the dosimetric perturbation due to the use of a gold marker for radiotherapy in the lungs. The relative dose distributions were compared with film measurement, Monte Carlo simulation, and XiO calculation with the multi grid superposition algorithm using two types of virtual lung phantoms, which were composed of tough water phantoms, tough lung phantoms, cork boards, and a 2.0-mm-diameter gold ball. No dose increase and decrease in the vicinity of the gold ball was seen in the XiO calculations, although it was seen in the film measurements and the Monte Carlo simulation. The dose perturbation due to a gold marker cannot be evaluated using XiO calculation with the superposition algorithm when the tumor is near a gold marker (especially within 0.5 cm). To rule out the presence of such dose perturbations due to a gold marker, the distance between the gold marker and the tumor must therefore be greater than 0.5 cm. (author)

  11. Exposure levels due to WLAN devices in indoor environments corrected by a time-amplitude factor of distribution of the quasi-stochastic signals

    International Nuclear Information System (INIS)

    Miclaus, Simona; Bechet, Paul; Stratakis, Dimitrios

    2014-01-01

    With the development of radiofrequency technology, radiating quasi-stochastic signals like the wireless local area networks (WLAN), a proper procedure of exposure level assessment is needed. No standardised procedure exists at the moment. While channel power measurement proved to overestimate the field strength, weighting techniques were proposed. The paper compares the exposure levels determined by three different procedures, two of them correcting the field level by weighting. Twenty-three experimental cases of WLAN traffic load are analysed in an indoor environment in controlled conditions. The results show the differences obtained when the duty cycle (DC) method is applied comparatively with the application of weighting based on an amplitude-time correction. Significant exposure level reductions of 52.6-79.2 % from the field determined by frequency domain method and of 36.5-72.8 % from the field determined by the DC weighting method were obtained by time-amplitude method. Specificities of weighting factors probability density functions were investigated and regression analysis was applied for a detailed characterisation of this procedure. (authors)

  12. Effects of terraces, surface steps and 'over-specular' reflection due to inelastic energy losses on angular scattering spectra for glancing incidence scattering

    CERN Document Server

    Danailov, D; O'Connor, D J

    2002-01-01

    Recent experiments and our molecular-dynamics simulations indicate that the main signal of the angular scattering spectra of glancing incidence scattering are not affected by the thermal motion of surface atoms and can be explained by our row-model with averaged cylindrical potentials. At the ICACS-18 Conference [Nucl. Instr. and Meth. B 164-165 (2000) 583] we reported good agreement between experimental and calculated multimodal azimuthal angular scattering spectra for the glancing scattering of 10 and 15 keV [Nucl. Instr. and Meth. B 180 (2001) 265, Appl. Surf. Sci. 171 (2001) 113] He sup 0 beam along the [1 0 0] direction on the Fe(1 0 0) face. Our simulations also predicted that in contrast to the 2D angular scattering distribution, the 1D azimuthal angular distribution of scattered particles is very sensitive to the interaction potential used. Here, we report more detailed calculations incorporating the influence of terraces and surface steps on surface channeling, which show a reduction of the angular s...

  13. SU-E-I-55: The Contribution to Skin Dose Due to Scatter From the Patient Table and the Head Holder During Fluoroscopy

    International Nuclear Information System (INIS)

    Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D

    2015-01-01

    Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant

  14. SU-E-I-55: The Contribution to Skin Dose Due to Scatter From the Patient Table and the Head Holder During Fluoroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

    2015-06-15

    Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant.

  15. On the inverse problem in high-energy elastic hadron scattering and the applicability of a representation for the real part of the amplitude

    International Nuclear Information System (INIS)

    Fagundes, Daniel Almeida

    2010-01-01

    The theoretical description of high-energy elastic hadron scattering constitutes an open problem in both, the underlying quantum field theory of strong interactions (QCD) and the phenomenological context. In this work the inverse problem in elastic hadron scattering is discussed in the impact parameter and eikonal frameworks, specifically a study on the empirical extraction of the profile, the inelastic overlap and the eikonal functions, from the experimental data and some principles and high-energy theorems (model independent). The analysis is limited to elastic proton-proton scattering in the center of momentum energy interval 19.4 - 62.5 GeV. In particular, a novel representation for the Martin's Real Part Formula is introduced but without the scaling property and suitable for empirical analysis. By means of this representation, and two other parametrizations previously introduced (constrained and unconstrained), several properties of the inelastic overlap function and the imaginary part of the eikonal (opacity) in the momentum transfer space are determined, in special: (1) evidence of a peripheral effect (tail) in the inelastic overlap function in the parameter impact space above 2 fm; (2) development of analytical parametrizations for this function leading to three gaussian components with centers at 0.0, ∼0.7 and ∼1.3 fm; (3) evidence of a finite zero (change of sign) in the opacity function in the momentum transfer space; (4) development of empirical parametrization for this function consistent with form factors as a product of two monopoles with constrained masses (not a dipole type) and a term with zero; (5) detailed discussion on the determination of the opacity function in the momentum transfer space through the semi-analytical approach. The applicability of these empirical results in the development of eikonal models (mainly those inspired in QCD) is also discussed. (author)

  16. Magnetic photon scattering

    International Nuclear Information System (INIS)

    Lovesey, S.W.

    1987-05-01

    The report reviews, at an introductory level, the theory of photon scattering from condensed matter. Magnetic scattering, which arises from first-order relativistic corrections to the Thomson scattering amplitude, is treated in detail and related to the corresponding interaction in the magnetic neutron diffraction amplitude. (author)

  17. Difference in x-ray scattering between metallic and non-metallic liquids due to conduction electrons

    International Nuclear Information System (INIS)

    Chihara, Junzo

    1987-01-01

    X-ray scattered intensity from a liquid metal as an electron-ion mixture is described using the structure factors, which are exactly expressed in terms of the static and dynamic direct correlation functions. This intensity for a metal is shown to differ from the usual scattered intensity from a non-metal in two points: the atomic form factor and the incoherent (Compton) scattering factor. It is shown that the valence electron form factor, which constitutes the atomic form factor in a liquid metal, leads to a determination of the electron-electron and electron-ion structure factors by combining the ionic structure factor. It is also shown that a part of the electron structure factor, which appears as the incoherent x-ray scattering, is usually approximated as the electron structure factor of the jellium model in the case of a simple metal. As a by-product, the x-ray scattered intensity from a crystalline metal and the inelastic scattering from a liquid metal are given by taking account of the presence of conduction electrons. In this way, we clarify some confusion which appeared in the proposal by Egelstaff et al for extracting the electron-electron correlation function in a metal from x-ray and neutron scattering experiments. A procedure to extract the electron-electron and electron-ion structure factors in a liquid metal is proposed on the basis of formula for scattered intensity derived here. (author)

  18. Forward amplitude in pion deuteron

    International Nuclear Information System (INIS)

    Ferreira, E.M.; Munguia, G.A.P.; Rosa, L.P.; Thome, Z.D.

    1979-06-01

    The data on total cross section for πd scattering is analysed in terms of a single scattering calculation with Fermi motion dependence, in order to obtain a criterion to fix the value of the energy entering the two body meson nucleon amplitude. It is found that the prescription derived from the non-relativistic three body kinematics gives reasonable results. The introduction of a shift in the energy value, possibly representing nuclear binding effects, leads to a very good fitting of the data. The results are compared with those obtained in direct calculations of Faddeev equations and with the Brueckner model of fixed scatterers. (Author) [pt

  19. Discontinuity formulas for multiparticle amplitudes

    International Nuclear Information System (INIS)

    Stapp, H.P.

    1976-03-01

    It is shown how discontinuity formulas for multiparticle scattering amplitudes are derived from unitarity and analyticity. The assumed analyticity property is the normal analytic structure, which was shown to be equivalent to the space-time macrocausality condition. The discontinuity formulas to be derived are the basis of multi-particle fixed-t dispersion relations

  20. Nonsinglet pentagons and NMHV amplitudes

    Directory of Open Access Journals (Sweden)

    A.V. Belitsky

    2015-07-01

    Full Text Available Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

  1. Nonsinglet pentagons and NMHV amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Belitsky, A.V., E-mail: andrei.belitsky@asu.edu

    2015-07-15

    Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

  2. Visibility degradation and light scattering/absorption due to aerosol particles in urban/suburban atmosphere of Irbid, Jordan

    International Nuclear Information System (INIS)

    Hamasha, K. M.; University of Tabuk, Tabuk

    2010-01-01

    Visible light scattering and absorption patterns were measured using a photoacoustic instrument at different locations in Irbid city. Measurments were perfoemed during the intervals 1-9 August 2007 and 7-13 October 2007 at the city center site (Palestine street) and the southern site (University Circle), respectively. The city center site is impacted by local urban and regional aerosols. The southern site is dominated by regional aerosols. Data from both sampling sites showed variety of diurnal light absorption and scattering patterns. During most of the measurement days, the highest light absorption peaks appeared in the morning, 7:00 - 9:30 AM, whereas the highest light scattering peaks appeared later, 9:30 - 11:00 AM. The earlier light absorption peaks are likely attributed to the elevated black carbon vehicular emission during the heavy traffic hours (rush hours) whereas, the later light scattering peaks are attributed to secondary aerosols generted in the atmosphere through photochmical reactions. The southern site (University Circle) exhibited a higher light scattering and a lower light absorption contribution to the light extinction, leading to a better visibility compared to the City Center site. The visibility is averaged at 44 km and 115 km at the city center site and southern site, respectively. (author).

  3. Relaxation of a kinetic hole due to carrier-carrier scattering in multisubband single-quantum-well semiconductors

    DEFF Research Database (Denmark)

    Dery, H.; Tromborg, Bjarne; Eisenstein, G.

    2003-01-01

    We describe a theoretical model for carrier-carrier scattering in an inverted semiconductor quantum well structure using a multisubband diagram. The model includes all possible nonvanishing interaction terms within the static screening approximation, and it enables one to calculate accurately...

  4. Fast-ion redistribution due to sawtooth crash in the TEXTOR tokamak measured by collective Thomson scattering

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Bindslev, Henrik; Salewski, Mirko

    2010-01-01

    Here we present collective Thomson scattering measurements of 1D fast-ion velocity distribution functions in neutral beam heated TEXTOR plasmas with sawtooth oscillations. Up to 50% of the fast ions in the centre are redistributed as a consequence of a sawtooth crash. We resolve various directions...

  5. Effects of admittance and gyrotropy on the scattering due to chiro-ferrite medium coated microstructured PMC cylinder

    Science.gov (United States)

    Iqbal, N.; Choudhury, P. K.

    2017-12-01

    The paper deals with scattering of electromagnetic (EM) waves by perfectly magnetic conducting (PMC) cylinder coated with chiro-ferrite medium under the assumption of oblique angle of incidence wave with perpendicular polarization (transverse electric; TE). An on-demand (in respect of orientation) kind of conducting sheath helix structure is assumed to exist at the outer surface of cylinder. The effects of sheath helix orientation, along with the material parameters, such as chirality admittance and gyrotropy, on the echo width as well as the magnitude and phase of the electric and magnetic fields are investigated. Control on the anisotropic property remains greatly useful in obtaining the required optical response from the scatterer - the feature which would find fabulous sensing related applications.

  6. Induced scattering due to nonlinear Landau and cyclotron damping of electromagnetic and electrostatic waves in a magnetized plasma

    International Nuclear Information System (INIS)

    Sugaya, Reiji

    1989-01-01

    General expressions of the matrix elements for nonlinear wave-particle scattering (nonlinear Landau and cyclotron damping) of electromagnetic and electrostatic waves in a homogeneous magnetized plasma are derived from the Vlasov-Maxwell equations. The kinetic wave equations obtained for electromagnetic waves are expressed by four-order tensors in the rotating and cartesian coordinates. No restrictions are imposed on the propagation angle to a uniform magnetic field, the Larmor radius, the frequencies, or the wave numbers. By electrostatic approximation of the dielectric tensor and the matrix elements the kinetic wave equations can be applied to the case in which two scattering waves are electrostatic or they are partially electrostatic. Further, the matrix elements in the limit of parallel or perpendicular propagation to the magnetic field are given. (author)

  7. Time evolution of scattering states and velocity increase due to nonlinear processes in the quantum hall regime

    International Nuclear Information System (INIS)

    Riess, J.; Duport, C.

    1991-01-01

    We report the first numerical results (with realistic parameter values) for the time evolution of a scattered Landau function in a model system. They give a striking illustration for the Hall velocity increase beyond the classical value of the conduction electrons in the quantum Hall regime. This phenomenon, which is crucial for the integer quantum Hall effect, is caused by a special kind of nonclassical particle dynamics induced by disorder and cannot be described by linear response theory

  8. New relations for graviton-matter amplitudes

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    I report on recent progress in finding compact expressions for scattering amplitudes involving gravitons and gluons as well as massive scalar and fermionic matter particles. At tree level the single graviton emission amplitudes may be expressed as linear combination of purely non-gravitational ones. At the one-loop level recent results on all four point Einstein-Yang-Mills amplitudes with at most one opposite helicity state using unitarity methods are reported. 

  9. BRIEF COMMUNICATION: Fast-ion redistribution due to sawtooth crash in the TEXTOR tokamak measured by collective Thomson scattering

    Science.gov (United States)

    Nielsen, S. K.; Bindslev, H.; Salewski, M.; Bürger, A.; Delabie, E.; Furtula, V.; Kantor, M.; Korsholm, S. B.; Leipold, F.; Meo, F.; Michelsen, P. K.; Moseev, D.; Oosterbeek, J. W.; Stejner, M.; Westerhof, E.; Woskov, P.; TEXTOR Team

    2010-09-01

    Here we present collective Thomson scattering measurements of 1D fast-ion velocity distribution functions in neutral beam heated TEXTOR plasmas with sawtooth oscillations. Up to 50% of the fast ions in the centre are redistributed as a consequence of a sawtooth crash. We resolve various directions to the magnetic field. The fast-ion distribution is found to be anisotropic as expected. For a resolved angle of 39° to the magnetic field we find a drop in the fast-ion distribution of 20-40%. For a resolved angle of 83° to the magnetic field the drop is no larger than 20%.

  10. Motivic amplitudes and cluster coordinates

    International Nuclear Information System (INIS)

    Golden, J.K.; Goncharov, A.B.; Spradlin, M.; Vergu, C.; Volovich, A.

    2014-01-01

    In this paper we study motivic amplitudes — objects which contain all of the essential mathematical content of scattering amplitudes in planar SYM theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. We find that the cluster structure on the kinematic configuration space Conf n (ℙ 3 ) underlies the structure of motivic amplitudes. Specifically, we compute explicitly the coproduct of the two-loop seven-particle MHV motivic amplitude A 7,2 M and find that like the previously known six-particle amplitude, it depends only on certain preferred coordinates known in the mathematics literature as cluster X-coordinates on Conf n (ℙ 3 ). We also find intriguing relations between motivic amplitudes and the geometry of generalized associahedrons, to which cluster coordinates have a natural combinatoric connection. For example, the obstruction to A 7,2 M being expressible in terms of classical polylogarithms is most naturally represented by certain quadrilateral faces of the appropriate associahedron. We also find and prove the first known functional equation for the trilogarithm in which all 40 arguments are cluster X-coordinates of a single algebra. In this respect it is similar to Abel’s 5-term dilogarithm identity

  11. Two-Loop Gluon to Gluon-Gluon Splitting Amplitudes in QCD

    International Nuclear Information System (INIS)

    Bern, Z.

    2004-01-01

    Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g → gg splitting amplitudes in QCD, N = 1, and N = 4 super-Yang-Mills theories, which describe the limits of two-loop n-point amplitudes where two gluon momenta become parallel. They also represent an ingredient in a direct x-space computation of DGLAP evolution kernels at next-to-next-to-leading order. To obtain the splitting amplitudes, we use the unitarity sewing method. In contrast to the usual light-cone gauge treatment, our calculation does not rely on the principal-value or Mandelstam-Leibbrandt prescriptions, even though the loop integrals contain some of the denominators typically encountered in light-cone gauge. We reduce the integrals to a set of 13 master integrals using integration-by-parts and Lorentz invariance identities. The master integrals are computed with the aid of differential equations in the splitting momentum fraction z. The ε-poles of the splitting amplitudes are consistent with a formula due to Catani for the infrared singularities of two-loop scattering amplitudes. This consistency essentially provides an inductive proof of Catani's formula, as well as an ansatz for previously-unknown 1/ε pole terms having non-trivial color structure. Finite terms in the splitting amplitudes determine the collinear behavior of finite remainders in this formula

  12. Amplification of Surface-Enhanced Raman Scattering Due to Substrate-Mediated Localized Surface Plasmons in Gold Nanodimers

    KAUST Repository

    Yue, Weisheng

    2017-03-28

    Surface-enhanced Raman scattering (SERS) is ubiquitous in chemical and biochemical sensing, imaging and identification. Maximizing SERS enhancement is a continuous effort focused on the design of appropriate SERS substrates. Here we show that significant improvement in a SERS signal can be achieved with substrates combining localized surface plasmon resonances and a nonresonant plasmonic substrate. By introducing a continuous gold (Au) film underneath Au nanodimers antenna arrays, an over 10-fold increase in SERS enhancement is demonstrated. Triangular, rectangle and disc dimers were studied, with bowtie antenna providing highest SERS enhancement. Simulations of electromagnetic field distributions of the Au nanodimers on the Au film support the observed enhancement dependences. The hybridization of localized plasmonic modes with the image modes in a metal film provides a straightforward way to improve SERS enhancement in designer SERS substrate.

  13. Comparison of collective Thomson scattering signals due to fast ions in ITER scenarios with fusion and auxiliary heating

    DEFF Research Database (Denmark)

    Salewski, Mirko; Asunta, O.; Eriksson, L.-G.

    2009-01-01

    Auxiliary heating such as neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH) will accelerate ions in ITER up to energies in the MeV range, i.e. energies which are also typical for alpha particles. Fast ions of any of these populations will elevate the collective Thomson...... functions of fast ions generated by NBI and ICRH are calculated for a steady-state ITER burning plasma equilibrium with the ASCOT and PION codes, respectively. The parameters for the auxiliary heating systems correspond to the design currently foreseen for ITER. The geometry of the CTS system for ITER...... is chosen such that near perpendicular and near parallel velocity components are resolved. In the investigated ICRH scenario, waves at 50MHz resonate with tritium at the second harmonic off-axis on the low field side. Effects of a minority heating scheme with He-3 are also considered. CTS scattering...

  14. One-loop triple collinear splitting amplitudes in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Simon; Buciuni, Francesco; Peraro, Tiziano [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom)

    2015-09-28

    We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic Higgs plus four partons amplitudes. We present compact results for primitive helicity splitting amplitudes making use of super-symmetric decompositions. The universality of the collinear factorisation is checked numerically against the full colour six parton squared matrix elements.

  15. DVCS amplitude with kinematical twist-3 terms

    International Nuclear Information System (INIS)

    Radyushkin, A.V.; Weiss, C.

    2000-01-01

    The authors compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude they include the operators of twist-3 which appear as total derivatives of twist-2 operators. The results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. They find that this approximation gives a finite result for the amplitude of a longitudinally polarized virtual photon, while the amplitude for transverse polarization is divergent, i.e., factorization breaks down in this term

  16. Amplitude structure of off-shell processes

    International Nuclear Information System (INIS)

    Fearing, H.W.; Goldstein, G.R.; Moravcsik, M.J.

    1984-01-01

    The structure of M matrices, or scattering amplitudes, and of potentials for off-shell processes is discussed with the objective of determining how one can obtain information on off-shell amplitudes of a process in terms of the physical observables of a larger process in which the first process is embedded. The procedure found is inevitably model dependent, but within a particular model for embedding, a determination of the physically measurable amplitudes of the larger process is able to yield a determination of the off-shell amplitudes of the embedded process

  17. Electromagnetic and gravitational scattering at Planckian energies

    International Nuclear Information System (INIS)

    Das, S.; Majumdar, P.

    1994-11-01

    The scattering of pointlike particles at very large center of mass energies and fixed low momentum transfers, occurring due to both their electromagnetic and gravitational interactions is re-examined in the particular case when one of the particles carries magnetic charge. At Planckian center-of-mass energies, when gravitational dominance is normally expected, the presence of magnetic charge is shown to produce dramatic modifications to the scattering cross section as well as to the holomorphic structure of the scattering amplitude. (author). 20 refs

  18. pp-elastic scattering

    Energy Technology Data Exchange (ETDEWEB)

    Aprile, E; Cantale, G; Degli-Agosti, S; Hausammann, R; Heer, E; Hess, R; Lechanoine-LeLuc, C; Leo, W; Morenzoni, S; Onel, Y [Geneva Univ. (Switzerland). Dept. de Physique Nucleaire et Corpusculaire

    1983-01-01

    The aim of the elastic pp experimental program at SIN was to measure enough spin dependent parameters in order to do a direct experimental reconstruction of the elastic scattering amplitudes at a few energies between 400 and 600 MeV and at several angles between 38/sup 0/ cm and 90/sup 0/ cm. This reconstruction was not possible until recently due to lack of experimental data. Information instead has come mainly from phase shift analysis (PSA). The only way to extract the elastic scattering amplitudes without any hypotheses except those of basic symmetries, is to measure a sufficient set of spin dependent parameters at a given angle and energy. With this in view, the authors have measured at 448, 494, 515, 536 and 579 MeV, the polarization, the spin correlation parameters Asub(00nn), Asub(00ss), Asub(00kk), Asub(00ks), the 2-spin parameters Dsub(n0n0), Ksub(n00n), Dsub(s'0s0), Dsub(s'0k0) and the 3-spin parameters Msub(s'0sn), Msub(s'0kn) between 34/sup 0/ cm and 118/sup 0/ cm. A few of these parameters have also been measured at 560 and 470 MeV and at a few energies below 448 MeV. The indices refer to the polarization orientation of the scattered, recoil, beam and target particle respectively.

  19. Influence of Kohn singularity on the occurrence scattering time in degenerate quantum collisional plasmas

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-10-01

    The influence of Kohn singularity on the occurrence scattering time for the electron-ion interaction is investigated in degenerate quantum collisional plasmas. The first-order eikonal analysis is used to obtain the scattering amplitude and the occurrence scattering time. The result shows that the Friedel oscillation due to the Kohn singularity suppresses the advance phenomena of occurrence scattering time in both forward and backward scattering domains. It is shown that the increase of plasmon energy would reduce the time advance for both forward and backward scattering domains. However, the increase of Fermi energy would enhance the phenomena of time advance. It is also found that the time advance with high collision frequency is larger than that with low collision frequency for the forward scattering domain and vice versa for the backward scattering domain. We have shown that the time advance is stronger in general for the forward scattering domain than that for the backward scattering domain.

  20. MHV Vertices And Tree Amplitudes In Gauge Theory

    International Nuclear Information System (INIS)

    Cachazo, Freddy; Svrcek, Peter; Witten, Edward

    2004-01-01

    As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills theory can be constructed from tree graphs in which the vertices are tree level MHV scattering amplitudes, continued off shell in a particular fashion. The formalism leads to new and relatively simple formulas for many amplitudes, and can be heuristically derived from twistor space. (author)

  1. H(10) due to radiation scattered in a 6 MV Linac for tomotherapy; H*(10) debida a la radiacion dispersada en un LINAC de 6 MV para tomoterapia

    Energy Technology Data Exchange (ETDEWEB)

    Vega C, H. R.; Esparza H, A. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98060 Zacatecas, Zac. (Mexico); Garcia R, M. G. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Zacatecas, Calz. Pedro Coronel 16, Dependencias Federales, 98600 Guadalupe, Zacatecas (Mexico); Reyes R, E. [Universidad de Guanajuato, Campus Leon, Division de Ciencias e Ingenierias, Loma del Bosque 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico); Hernandez A, L. [Consejo Nacional de Ciencia y Tecnologia, CIBNOR, Mar Bermejo 195, Col. Playa Palo de Santa Rita, 23090 La Paz, Baja California Sur (Mexico); Rivera, T., E-mail: fermineutron@yahoo.com [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Calz. Legaria 694, Col. Irrigacion, 11500 Ciudad de Mexico (Mexico)

    2017-10-15

    In order to determine the environmental equivalent dose (H(10)), due to the radiation that is dispersed over the body of a patient, 100 thermoluminescent dosimeters (TLD) around 6 MV TomoLINAC were used. The characteristics of the tomotherapy have the disadvantage that the shielding of the bunker increases considerably and for its design validated parameters are used for the conventional Linacs. In order to determine H(10) due to scattered radiation, measurements were made in the vicinity of the isocenter, while the 6 MeV photon beam was applied on a phantom. Also, TLDs were placed on the walls of the bunker that remained for 7 days, where approximately 50 patients were treated per day. At points close to the isocenter, the H(10) has an angular distribution caused by the phantom shape. In the bunker walls the highest H(10) was observed in the primary barriers. In the labyrinth, the impact of the scattered radiation was observed when measuring a greater value of the environmental equivalent dose in the wall furthest from the isocenter compared to the point located closest to it. (Author)

  2. Loop Amplitudes in Pure Yang-Mills from Generalised Unitarity

    OpenAIRE

    Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele

    2005-01-01

    We show how generalised unitarity cuts in D = 4 - 2 epsilon dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.

  3. Loop amplitudes in pure Yang-Mills from generalised unitarity

    International Nuclear Information System (INIS)

    Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele

    2005-01-01

    We show how generalised unitarity cuts in D = 4-2ε dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions

  4. Loop amplitudes in pure Yang-Mills from generalised unitarity

    Energy Technology Data Exchange (ETDEWEB)

    Brandhuber, Andreas [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); McNamara, Simon [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Spence, Bill [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Travaglini, Gabriele [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom)

    2005-10-15

    We show how generalised unitarity cuts in D = 4-2{epsilon} dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.

  5. Analytic representations of Yang–Mills amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Bjerrum-Bohr, N.E.J. [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Bourjaily, Jacob L., E-mail: bourjaily@nbi.ku.dk [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Damgaard, Poul H. [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Feng, Bo [Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou City, 310027 (China)

    2016-12-15

    Scattering amplitudes in Yang–Mills theory can be represented in the formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary projective space—fully localized on the support of the scattering equations. Because solving the scattering equations is difficult and summing over the solutions algebraically complex, a method of directly integrating the terms that appear in this representation has long been sought. We solve this important open problem by first rewriting the terms in a manifestly Möbius-invariant form and then using monodromy relations (inspired by analogy to string theory) to decompose terms into those for which combinatorial rules of integration are known. The result is the foundations of a systematic procedure to obtain analytic, covariant forms of Yang–Mills tree-amplitudes for any number of external legs and in any number of dimensions. As examples, we provide compact analytic expressions for amplitudes involving up to six gluons of arbitrary helicities.

  6. Multiphoton amplitude in a constant background field

    Science.gov (United States)

    Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian

    2018-01-01

    In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.

  7. Quasiresonant scattering

    International Nuclear Information System (INIS)

    Hategan, Cornel; Comisel, Horia; Ionescu, Remus A.

    2004-01-01

    The quasiresonant scattering consists from a single channel resonance coupled by direct interaction transitions to some competing reaction channels. A description of quasiresonant Scattering, in terms of generalized reduced K-, R- and S- Matrix, is developed in this work. The quasiresonance's decay width is, due to channels coupling, smaller than the width of the ancestral single channel resonance (resonance's direct compression). (author)

  8. Diurnal and semi-diurnal tidal structures due to O2, O3 and H2O ...

    Indian Academy of Sciences (India)

    from World Meteorological Organization (WMO. 1986), while the Rayleigh scattering cross section was calculated using the formula of Nicolet (1984). ..... Figure 5(a) exhibits the exponential growth of diurnal amplitude with altitude, at low to mid lat- itudes. At high latitudes, the diurnal amplitude decreases with altitude due to ...

  9. Superstring amplitudes and contact interactions

    International Nuclear Information System (INIS)

    Greensite, J.

    1987-08-01

    We show that scattering amplitudes computed from light-cone superstring field theory are divergent at tree level. The divergences can be eliminated, and supersymmetry restored, by the addition of certain counter terms to the light-cone Hamiltonian. These counter terms have the form of local contact interactions, whose existence we had previously deduced on grounds of vacuum stability, and closure of the super-Poincare algebra. The quartic contact interactions required in Type I and Type IIB superstring theories are constructed in detail. (orig.)

  10. Monitoring the distributed impact wave on a concrete slab due to the traffic based on polarization dependence on stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Bao Xiaoyi; Zhang Chunshu; Li Wenhai; Eisa, M; El-Gamal, S; Benmokrane, B

    2008-01-01

    For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h −1 ), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montréal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m

  11. Gravitational Bhabha scattering

    International Nuclear Information System (INIS)

    Santos, A F; Khanna, Faqir C

    2017-01-01

    Gravitoelectromagnetism (GEM) as a theory for gravity has been developed similar to the electromagnetic field theory. A weak field approximation of Einstein theory of relativity is similar to GEM. This theory has been quantized. Traditional Bhabha scattering, electron–positron scattering, is based on quantized electrodynamics theory. Usually the amplitude is written in terms of one photon exchange process. With the development of quantized GEM theory, the scattering amplitude will have an additional component based on an exchange of one graviton at the lowest order of perturbation theory. An analysis will provide the relative importance of the two amplitudes for Bhabha scattering. This will allow an analysis of the relative importance of the two amplitudes as the energy of the exchanged particles increases. (paper)

  12. Hidden simplicity of gauge theory amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J M, E-mail: drummond@lapp.in2p3.f [LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux, Cedex (France)

    2010-11-07

    These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in N=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.

  13. Tree-level gluon amplitudes on the celestial sphere

    Science.gov (United States)

    Schreiber, Anders Ø.; Volovich, Anastasia; Zlotnikov, Michael

    2018-06-01

    Pasterski, Shao and Strominger have recently proposed that massless scattering amplitudes can be mapped to correlators on the celestial sphere at infinity via a Mellin transform. We apply this prescription to arbitrary n-point tree-level gluon amplitudes. The Mellin transforms of MHV amplitudes are given by generalized hypergeometric functions on the Grassmannian Gr (4 , n), while generic non-MHV amplitudes are given by more complicated Gelfand A-hypergeometric functions.

  14. Knock-on tail formation due to nuclear elastic scattering and its observation method using γ-ray-generating "6Li+d reaction in tokamak deuterium plasmas

    International Nuclear Information System (INIS)

    Matsuura, Hideaki; Sugiyama, Shota; Kajimoto, Shogo; Sawada, Daisuke; Nishimura, Yosuke; Kawamoto, Yasuko

    2016-01-01

    A knock-on tail formation in deuteron velocity distribution function due to nuclear elastic scattering (NES) by energetic protons and its observation method using γ-ray-generating "6Li(d,pγ)"7Li reaction are examined for proton-beam-injected deuterium plasmas. The proton velocity distribution function is obtained by means of the ion trajectory analysis in a Tokamak magnetic configuration. The knock-on tail in two-dimensional (2D) deuteron velocity distribution function due to NES by energetic protons is evaluated via Boltzmann collision integral and 2D Fokker-Planck simulation. From the 2D deuteron velocity distribution function obtained, enhancement of the emission rate of 0.48-MeV γ-rays by "6Li(d,p)"7Li*, "7Li*→"7Li+γ reaction due to NES is evaluated. It is shown that the γ-ray emission rate is significantly influenced by the magnitude of the knock-on tail, and the γ-ray-generating reaction can be a useful tool for the knock-on tail observation. (author)

  15. Topological amplitudes in string theory

    International Nuclear Information System (INIS)

    Antoniadis, I.; Taylor, T.R.

    1993-07-01

    We show that certain type II string amplitudes at genus g are given by the topological partition F g discussed recently by Bershadsky, Cecotti, Ooguri and Vafa. These amplitudes give rise to a term in the four-dimensional effective action of the form Σ g F g W 2g , where W is the chiral superfield of N = 2 supergravitational multiplet. The holomorphic anomaly of F g is related to non-localities of the effective action due to the propagation of massless states. This result generalizes the holomorphic anomaly of the one loop case which is known to lead to non-harmonic gravitational couplings. (author). 22 refs, 2 figs

  16. Diphoton generalized distribution amplitudes

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

    2008-01-01

    We calculate the leading order diphoton generalized distribution amplitudes by calculating the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region at the Born order and in the leading logarithmic approximation. As in the case of the anomalous photon structure functions, the γγ generalized distribution amplitudes exhibit a characteristic lnQ 2 behavior and obey inhomogeneous QCD evolution equations.

  17. Tree-level amplitudes and dual superconformal symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J M, E-mail: drummond@lapp.in2p3.fr [PH-TH Division, CERN, CH-1211, Geneva 23 (Switzerland); LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux Cedex (France)

    2011-11-11

    We review the structure of gauge theory scattering amplitudes at tree level and describe how a compact expression can be found which encodes all the tree-level amplitudes in the maximally supersymmetric N=4 theory. The expressions for the amplitudes reveal a dual superconformal symmetry. We describe how these ideas can be extended to leading singularities and the loop integrand in the planar theory and discuss the appearance of dual conformal symmetry in higher-dimensional gauge theories. This paper is an invited review for a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Scattering amplitudes in gauge theories'. (review)

  18. Pion-pion scattering

    International Nuclear Information System (INIS)

    Kuehnelt, H.

    1975-01-01

    We discuss a few properties of scattering amplitudes proved within the framework of the field theory and their significance in the derivation of quantitative statements. The state of the boundaries for the scattering lengths is to be especially discussed as well as the question as to how far it is possible to exclude various solutions from phase displacement analyses. (orig./LH) [de

  19. High energy hadron spin-flip amplitude

    International Nuclear Information System (INIS)

    Selyugin, O.V.

    2016-01-01

    The high-energy part of the hadron spin-flip amplitude is examined in the framework of the new high-energy general structure (HEGS) model of the elastic hadron scattering at high energies. The different forms of the hadron spin-flip amplitude are compared in the impact parameter representation. It is shown that the existing experimental data of the proton-proton and proton-antiproton elastic scattering at high energy in the region of the diffraction minimum and at large momentum transfer give support in the presence of the energy-independent part of the hadron spin-flip amplitude with the momentum dependence proposed in the works by Galynskii-Kuraev. [ru

  20. On the singularities of massive superstring amplitudes

    International Nuclear Information System (INIS)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism. (orig.)

  1. On the singularities of massive superstring amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Foda, O.

    1987-06-04

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism.

  2. Realizing total reciprocity violation in the phase for photon scattering.

    Science.gov (United States)

    Deák, László; Bottyán, László; Fülöp, Tamás; Merkel, Dániel Géza; Nagy, Dénes Lajos; Sajti, Szilárd; Schulze, Kai Sven; Spiering, Hartmut; Uschmann, Ingo; Wille, Hans-Christian

    2017-02-22

    Reciprocity is when wave or quantum scattering satisfies a symmetry property, connecting a scattering process with the reversed one. While reciprocity involves the interchange of source and detector, it is fundamentally different from rotational invariance, and is a generalization of time reversal invariance, occurring in absorptive media as well. Due to its presence at diverse areas of physics, it admits a wide variety of applications. For polarization dependent scatterings, reciprocity is often violated, but violation in the phase of the scattering amplitude is much harder to experimentally observe than violation in magnitude. Enabled by the advantageous properties of nuclear resonance scattering of synchrotron radiation, we have measured maximal, i.e., 180-degree, reciprocity violation in the phase. For accessing phase information, we introduced a new version of stroboscopic detection. The scattering setting was devised based on a generalized reciprocity theorem that opens the way to construct new types of reciprocity related devices.

  3. Rayleigh scattering from ions near threshold

    International Nuclear Information System (INIS)

    Roy, S.C.; Gupta, S.K.S.; Kissel, L.; Pratt, R.H.

    1988-01-01

    Theoretical studies of Rayleigh scattering of photons from neon atoms with different degrees of ionization, for energies both below and above the K-edges of the ions, are presented. Some unexpected structures both in Rayleigh scattering and in photoionization from neutral and weakly ionized atoms, very close to threshold, have been reported. It has recently been realized that some of the predicted structures may have a nonphysical origin and are due to the limitation of the independent-particle model and also to the use of a Coulombic Latter tail. Use of a K-shell vacancy potential - in which an electron is assumed to be removed from the K-shell - in calculating K-shell Rayleigh scattering amplitudes removes some of the structure effects near threshold. We present in this work a discussion of scattering angular distributions and total cross sections, obtained utilizing vacancy potentials, and compare these predictions with those previously obtained in other potential model. (author) [pt

  4. Two Photon Distribution Amplitudes

    International Nuclear Information System (INIS)

    El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.

    2008-01-01

    The factorization of the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region is demonstrated at the Born order and in the leading logarithmic approximation. The leading order two photon (generalized) distribution amplitudes exhibit a characteristic ln Q 2 behaviour and obey new inhomogeneous evolution equations

  5. Amplitudes, acquisition and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bloor, Robert

    1998-12-31

    Accurate seismic amplitude information is important for the successful evaluation of many prospects and the importance of such amplitude information is increasing with the advent of time lapse seismic techniques. It is now widely accepted that the proper treatment of amplitudes requires seismic imaging in the form of either time or depth migration. A key factor in seismic imaging is the spatial sampling of the data and its relationship to the imaging algorithms. This presentation demonstrates that acquisition caused spatial sampling irregularity can affect the seismic imaging and perturb amplitudes. Equalization helps to balance the amplitudes, and the dealing strategy improves the imaging further when there are azimuth variations. Equalization and dealiasing can also help with the acquisition irregularities caused by shot and receiver dislocation or missing traces. 2 refs., 2 figs.

  6. Color guided amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Broedel, Johannes [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States); Dixon, Lance J. [SLAC National Accelerator Laboratory, Stanford University, Stanford, CA (United States)

    2012-07-01

    Amplitudes in gauge thoeries obtain contributions from color and kinematics. While these two parts of the amplitude seem to exhibit different symmetry structures, it turns out that they can be reorganized in a way to behave equally, which leads to the so-called color-kinematic dual representations of amplitudes. Astonishingly, the existence of those representations allows squaring to related gravitational theories right away. Contrary to the Kawaii-Levellen-Tye relations, which have been used to relate gauge theories and gravity previously, this method is applicable not only to tree amplitudes but also at loop level. In this talk, the basic technique is introduced followed by a discussion of the existence of color-kinematic dual representations for amplitudes derived from gauge theory actions which are deformed by higher-operator insertions. In addition, it is commented on the implications for deformed gravitational theories.

  7. Scattering of intermediate energy protons

    International Nuclear Information System (INIS)

    Chaumeaux, Alain.

    1980-06-01

    The scattering of 1 GeV protons appears to be a powerful means of investigating nuclear matter. We worked with SPESI and the formalism of Kerman-Mc Manus and Thaler. The amplitude of nucleon-nucleon scattering was studied as were the aspects of 1 GeV proton scattering (multiple scattering, absorption, spin-orbit coupling, N-N amplitude, KMT-Glauber comparison, second order effects). The results of proton scattering on 16 O, the isotopes of calcium, 58 Ni, 90 Zr and 208 Pb are given [fr

  8. On the singularities of massive superstring amplitudes

    NARCIS (Netherlands)

    Foda, O.

    1987-01-01

    Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are

  9. Dressing effects on the occurrence scattering time retardation and advance in a dusty plasma

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae; Hanyang Plasma Team

    2017-10-01

    The dressing effects on the occurrence scattering time for the dust-dust interaction are investigated in a complex plasma. The first-order eikonal analysis is applied to obtain the scattering amplitude and the occurrence scattering time for the dust-dust interaction. The result shows that dressing effect enhances the retardation phenomena of the occurrence scattering time in the forward scattering domain. It is shown that the oscillatory behavior of the scaled occurrence scattering time is getting more significant with an increase of the Debye length. It is also found that the retardation domain of the occurrence scattering time increases with a decrease of the Debye length. The variation of the occurrence scattering time retardation and advance due to the dressing effect is also discussed.

  10. Edge profile analysis of Joint European Torus (JET) Thomson scattering data: Quantifying the systematic error due to edge localised mode synchronisation.

    Science.gov (United States)

    Leyland, M J; Beurskens, M N A; Flanagan, J C; Frassinetti, L; Gibson, K J; Kempenaars, M; Maslov, M; Scannell, R

    2016-01-01

    The Joint European Torus (JET) high resolution Thomson scattering (HRTS) system measures radial electron temperature and density profiles. One of the key capabilities of this diagnostic is measuring the steep pressure gradient, termed the pedestal, at the edge of JET plasmas. The pedestal is susceptible to limiting instabilities, such as Edge Localised Modes (ELMs), characterised by a periodic collapse of the steep gradient region. A common method to extract the pedestal width, gradient, and height, used on numerous machines, is by performing a modified hyperbolic tangent (mtanh) fit to overlaid profiles selected from the same region of the ELM cycle. This process of overlaying profiles, termed ELM synchronisation, maximises the number of data points defining the pedestal region for a given phase of the ELM cycle. When fitting to HRTS profiles, it is necessary to incorporate the diagnostic radial instrument function, particularly important when considering the pedestal width. A deconvolved fit is determined by a forward convolution method requiring knowledge of only the instrument function and profiles. The systematic error due to the deconvolution technique incorporated into the JET pedestal fitting tool has been documented by Frassinetti et al. [Rev. Sci. Instrum. 83, 013506 (2012)]. This paper seeks to understand and quantify the systematic error introduced to the pedestal width due to ELM synchronisation. Synthetic profiles, generated with error bars and point-to-point variation characteristic of real HRTS profiles, are used to evaluate the deviation from the underlying pedestal width. We find on JET that the ELM synchronisation systematic error is negligible in comparison to the statistical error when assuming ten overlaid profiles (typical for a pre-ELM fit to HRTS profiles). This confirms that fitting a mtanh to ELM synchronised profiles is a robust and practical technique for extracting the pedestal structure.

  11. Non-supersymmetric loop amplitudes and MHV vertices

    International Nuclear Information System (INIS)

    Bedford, James; Brandhuber, Andreas; Spence, Bill; Travaglini, Gabriele

    2005-01-01

    We show how the MHV diagram description of Yang-Mills theories can be used to study non-supersymmetric loop amplitudes. In particular, we derive a compact expression for the cut-constructible part of the general one-loop MHV multi-gluon scattering amplitude in pure Yang-Mills theory. We show that in special cases this expression reduces to known amplitudes-the amplitude with adjacent negative-helicity gluons, and the five gluon non-adjacent amplitude. Finally, we briefly discuss the twistor space interpretation of our result

  12. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    wavelength, they are called shallow water waves. In the ... Deep and intermediate water waves are dispersive as the velocity of these depends on wavelength. This is not the ..... generation processes, the finite amplitude wave theories are very ...

  13. Real topological string amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Narain, K.S. [The Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, Trieste, 34151 (Italy); Piazzalunga, N. [Simons Center for Geometry and Physics, State University of New York,Stony Brook, NY, 11794-3636 (United States); International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy); Tanzini, A. [International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy)

    2017-03-15

    We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G{sub χ}, at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g{sup ′}=−χ+1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F{sub g}.

  14. Dissecting CFT Correlators and String Amplitudes. Conformal Blocks and On-Shell Recursion for General Tensor Fields

    International Nuclear Information System (INIS)

    Hansen, Tobias

    2015-07-01

    This thesis covers two main topics: the tensorial structure of quantum field theory correlators in general spacetime dimensions and a method for computing string theory scattering amplitudes directly in target space. In the first part tensor structures in generic bosonic CFT correlators and scattering amplitudes are studied. To this end arbitrary irreducible tensor representations of SO(d) (traceless mixed-symmetry tensors) are encoded in group invariant polynomials, by contracting with sets of commuting and anticommuting polarization vectors which implement the index symmetries of the tensors. The tensor structures appearing in CFT d correlators can then be inferred by studying these polynomials in a d + 2 dimensional embedding space. It is shown with an example how these correlators can be used to compute general conformal blocks describing the exchange of mixed-symmetry tensors in four-point functions, which are crucial for advancing the conformal bootstrap program to correlators of operators with spin. Bosonic string theory lends itself as an ideal example for applying the same methods to scattering amplitudes, due to its particle spectrum of arbitrary mixed-symmetry tensors. This allows in principle the definition of on-shell recursion relations for string theory amplitudes. A further chapter introduces a different target space definition of string scattering amplitudes. As in the case of on-shell recursion relations, the amplitudes are expressed in terms of their residues via BCFW shifts. The new idea here is that the residues are determined by use of the monodromy relations for open string theory, avoiding the infinite sums over the spectrum arising in on-shell recursion relations. Several checks of the method are presented, including a derivation of the Koba-Nielsen amplitude in the bosonic string. It is argued that this method provides a target space definition of the complete S-matrix of string theory at tree-level in a at background in terms of a small

  15. Double logarithmic asymptotics of quark amplitudes with flavour exchange

    International Nuclear Information System (INIS)

    Kirschner, R.

    1982-01-01

    Results on the quark scattering and annihilation amplitudes in the Regge region are presented. The perturbative contribution to those amplitudes in the double logarithmic approximation are calculated. In the calculations a method based on dispersion relations and gauge invariance is used. (M.F.W.)

  16. Ambitwistor strings and reggeon amplitudes in N=4 SYM

    Directory of Open Access Journals (Sweden)

    L.V. Bork

    2017-11-01

    Full Text Available We consider the description of reggeon amplitudes (Wilson lines form factors in N=4 SYM within the framework of four dimensional ambitwistor string theory. The latter is used to derive scattering equations representation for reggeon amplitudes with multiple reggeized gluons present. It is shown, that corresponding tree-level string correlation function correctly reproduces previously obtained Grassmannian integral representation of reggeon amplitudes in N=4 SYM.

  17. Optical theorem for heavy-ion scattering

    International Nuclear Information System (INIS)

    Schwarzschild, A.Z.; Auerbach, E.H.; Fuller, R.C.; Kahana, S.

    1976-01-01

    An heuristic derivation is given of an equivalent of the optical theorem stated in the charged situation with the remainder or nuclear elastic scattering amplitude defined as a difference of elastic and Coulomb amplitudes. To test the detailed behavior of this elastic scattering amplitude and the cross section, calculations were performed for elastic scattering of 18 O + 58 Ni, 136 Xe + 209 Bi, 84 Kr + 208 Pb, and 11 B + 26 Mg at 63.42 to 114 MeV

  18. Amplitude Models for Discrimination and Yield Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, William Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-01

    This seminar presentation describes amplitude models and yield estimations that look at the data in order to inform legislation. The following points were brought forth in the summary: global models that will predict three-component amplitudes (R-T-Z) were produced; Q models match regional geology; corrected source spectra can be used for discrimination and yield estimation; three-component data increase coverage and reduce scatter in source spectral estimates; three-component efforts must include distance-dependent effects; a community effort on instrument calibration is needed.

  19. Gluon amplitudes as 2 d conformal correlators

    Science.gov (United States)

    Pasterski, Sabrina; Shao, Shu-Heng; Strominger, Andrew

    2017-10-01

    Recently, spin-one wave functions in four dimensions that are conformal primaries of the Lorentz group S L (2 ,C ) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wave functions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2 d CFT. The Britto-Cachazo-Feng-Witten (BCFW) recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis.

  20. Three applications of a bonus relation for gravity amplitudes

    International Nuclear Information System (INIS)

    Spradlin, Marcus; Volovich, Anastasia; Wen, Congkao

    2009-01-01

    Arkani-Hamed et al. have recently shown that all tree-level scattering amplitudes in maximal supergravity exhibit exceptionally soft behavior when two supermomenta are taken to infinity in a particular complex direction, and that this behavior implies new non-trivial relations amongst amplitudes in addition to the well-known on-shell recursion relations. We consider the application of these new 'bonus relations' to MHV amplitudes, showing that they can be used quite generally to relate (n-2)!-term formulas typically obtained from recursion relations to (n-3)!-term formulas related to the original BGK conjecture. Specifically we provide (1) a direct proof of a formula presented by Elvang and Freedman, (2) a new formula based on one due to Bedford et al., and (3) an alternate proof of a formula recently obtained by Mason and Skinner. Our results also provide the first direct proof that the conjectured BGK formula, only very recently proven via completely different methods, satisfies the on-shell recursion.

  1. Gluon cascades and amplitudes in light-front perturbation theory

    International Nuclear Information System (INIS)

    Cruz-Santiago, C.A.; Staśto, A.M.

    2013-01-01

    We construct the gluon wave functions, fragmentation functions and scattering amplitudes within the light-front perturbation theory. Recursion relations on the light-front are constructed for the wave functions and fragmentation functions, which in the latter case are the light-front analogs of the Berends–Giele recursion relations. Using general relations between wave functions and scattering amplitudes it is demonstrated how to obtain the maximally-helicity violating amplitudes, and explicit verification of the results is based on simple examples.

  2. Unitarity and amplitudes for high energies

    International Nuclear Information System (INIS)

    Efimov, G.V.

    1997-01-01

    It is shown that in the quantum field theory of scalar particles with mass m the following inequalities for the upper bound for the amplitude of elastic scattering Μ(s,t) |Μ(s,t)| 0 )s, (|t|≥|t 0 |>0) and for the total cross section of scalar particles σ tot (s)≤C|d/dt ln Im Μ(s,t)| t=0 , (s → ∞) are valid. This result is based on the unitarity of the S-matrix on the mass shell and on a natural assumption that the imaginary part of the elastic scattering Im Μ(s,t) is a differentiable and convex down function in some vicinity of t=0. The locality of the theory and the analyticity of the elastic amplitude in the Martin-Lehmann ellipse are not used in proving these inequalities

  3. Resonant scattering of surface plasmon polaritons by dressed quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Danhong; Cardimona, Dave [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland Air Force Base, New Mexico 87117 (United States); Easter, Michelle [Department of Mechanical Engineering, Stevens Institute of Technology, 1 Castle Point Terrace, Hoboken, New Jersey 07030 (United States); Gumbs, Godfrey [Department of Physics and Astronomy, Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065 (United States); Maradudin, A. A. [Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States); Lin, Shawn-Yu [Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Zhang, Xiang [Department of Mechanical Engineering, 3112 Etcheverry Hall, University of California at Berkeley, Berkeley, California 94720 (United States)

    2014-06-23

    The resonant scattering of surface plasmon-polariton waves (SPP) by embedded semiconductor quantum dots above the dielectric/metal interface is explored in the strong-coupling regime. In contrast to non-resonant scattering by a localized dielectric surface defect, a strong resonant peak in the spectrum of the scattered field is predicted that is accompanied by two side valleys. The peak height depends nonlinearly on the amplitude of SPP waves, reflecting the feedback dynamics from a photon-dressed electron-hole plasma inside the quantum dots. This unique behavior in the scattered field peak strength is correlated with the occurrence of a resonant dip in the absorption spectrum of SPP waves due to the interband photon-dressing effect. Our result on the scattering of SPP waves may be experimentally observable and applied to spatially selective illumination and imaging of individual molecules.

  4. Polaron scattering by an external field

    International Nuclear Information System (INIS)

    Kochetov, E.A.

    1980-01-01

    The problem of polaron scattering by an external field is studied. The problem is solved using the stationary scattering theory formalism based on two operators: the G Green function operator and the T scattering operator. The dependence of the scattering amplitude on the quasi particle structure is studied. The variation approach is used for estimation of the ground energy level

  5. Amplitude and Ascoli analysis

    International Nuclear Information System (INIS)

    Hansen, J.D.

    1976-01-01

    This article discusses the partial wave analysis of two, three and four meson systems. The difference between the two approaches, referred to as amplitude and Ascoli analysis is discussed. Some of the results obtained with these methods are shown. (B.R.H.)

  6. Reinforcing Saccadic Amplitude Variability

    Science.gov (United States)

    Paeye, Celine; Madelain, Laurent

    2011-01-01

    Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…

  7. Generalized unitarity for N=4 super-amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J.M.; Henn, J. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France); Korchemsky, G.P., E-mail: Gregory.Korchemsky@cea.fr [Institut de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Sokatchev, E. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France)

    2013-04-21

    We develop a manifestly supersymmetric version of the generalized unitarity cut method for calculating scattering amplitudes in N=4 SYM theory. We illustrate the power of this method by computing the one-loop n-point NMHV super-amplitudes. The result confirms two conjectures which we made in Drummond, et al., [1]. Firstly, we derive the compact, manifestly dual superconformally covariant form of the NMHV tree amplitudes for arbitrary number and types of external particles. Secondly, we show that the ratio of the one-loop NMHV to the MHV amplitude is dual conformal invariant.

  8. Light output response of EJ-309 liquid organic scintillator to 2.86-3.95 MeV carbon recoil ions due to neutron elastic and inelastic scatter

    Science.gov (United States)

    Norsworthy, Mark A.; Ruch, Marc L.; Hamel, Michael C.; Clarke, Shaun D.; Hausladen, Paul A.; Pozzi, Sara A.

    2018-03-01

    We present the first measurements of energy-dependent light output from carbon recoils in the liquid organic scintillator EJ-309. For this measurement, neutrons were produced by an associated particle deuterium-tritium generator and scattered by a volume of EJ-309 scintillator into stop detectors positioned at four fixed angles. Carbon recoils in the scintillator were isolated using triple coincidence among the associated particle detector, scatter detector, and stop detectors. The kinematics of elastic and inelastic scatter allowed data collection at eight specific carbon recoil energies between 2.86 and 3.95 MeV. We found the light output caused by carbon recoils in this energy range to be approximately 1.14% of that caused by electrons of the same energy, which is comparable to the values reported for other liquid organic scintillators. A comparison of the number of scattered neutrons at each angle to a Monte Carlo N-Particle eXtended simulation indicates that the ENDF/B-VII.1 evaluation of differential cross sections for 14.1 MeV neutrons on carbon has discrepancies with the experiment as large as 55%, whereas those reported in the JENDL-4.0u evaluation agree with experiment.

  9. The Low-Temperature Inflection Observed in Neutron Scattering Measurements of Proteins Is Due to Methyl Rotation : Direct Evidence Using Isotope Labeling and Molecular Dynamics Simulations

    NARCIS (Netherlands)

    Wood, Kathleen; Tobias, Douglas J.; Kessler, Brigitte; Gabel, Frank; Oesterhelt, Dieter; Mulder, Frans A. A.; Zaccai, Giuseppe; Weik, Martin

    2010-01-01

    There is increasing interest in the contribution of methyl groups to the overall dynamics measured by neutron scattering experiments of proteins. In particular an inflection observed in atomic mean square displacements measured as a function of temperature on high resolution spectrometers (similar

  10. Light Meson Distribution Amplitudes

    CERN Document Server

    Arthur, R.; Brommel, D.; Donnellan, M.A.; Flynn, J.M.; Juttner, A.; de Lima, H.Pedroso; Rae, T.D.; Sachrajda, C.T.; Samways, B.

    2010-01-01

    We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.

  11. Laser-induced damage of fused silica optics at 355 nm due to backward stimulated Brillouin scattering: experimental and theoretical results.

    Science.gov (United States)

    Lamaignère, Laurent; Gaudfrin, Kévin; Donval, Thierry; Natoli, Jeanyves; Sajer, Jean-Michel; Penninckx, Denis; Courchinoux, Roger; Diaz, Romain

    2018-04-30

    Forward pump pulses with nanosecond duration are able to generate an acoustic wave via electrostriction through a few centimeters of bulk silica. Part of the incident energy is then scattered back on this sound wave, creating a backward Stokes pulse. This phenomenon known as stimulated Brillouin scattering (SBS) might induce first energy-loss, variable change of the temporal waveform depending on the location in the spatial profile making accurate metrology impossible, and moreover it might also initiate front surface damage making the optics unusable. Experiments performed on thick fused silica optics at 355 nm with single longitudinal mode pulses allowed us to detect, observe and quantify these backward pulses. Experimental results are first compared to theoretical calculations in order to strengthen our confidence in metrology. On this basis a phase-modulator has been implemented on the continuous-wave seeders of the lasers leading to pulses with a wide spectrum that suppress SBS and do not exhibit temporal overshoots that also reduce Kerr effects. The developed set-ups are used to check the reduction of the backward stimulated Brillouin scattering and they allow measuring with accuracy the rear surface damage of thick fused silica optics.

  12. An algebraic approach to the scattering equations

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Rijun; Rao, Junjie [Zhejiang Institute of Modern Physics, Zhejiang University,Hangzhou, 310027 (China); Feng, Bo [Zhejiang Institute of Modern Physics, Zhejiang University,Hangzhou, 310027 (China); Center of Mathematical Science, Zhejiang University,Hangzhou, 310027 (China); He, Yang-Hui [School of Physics, NanKai University,Tianjin, 300071 (China); Department of Mathematics, City University,London, EC1V 0HB (United Kingdom); Merton College, University of Oxford,Oxford, OX14JD (United Kingdom)

    2015-12-10

    We employ the so-called companion matrix method from computational algebraic geometry, tailored for zero-dimensional ideals, to study the scattering equations. The method renders the CHY-integrand of scattering amplitudes computable using simple linear algebra and is amenable to an algorithmic approach. Certain identities in the amplitudes as well as rationality of the final integrand become immediate in this formalism.

  13. An algebraic approach to the scattering equations

    International Nuclear Information System (INIS)

    Huang, Rijun; Rao, Junjie; Feng, Bo; He, Yang-Hui

    2015-01-01

    We employ the so-called companion matrix method from computational algebraic geometry, tailored for zero-dimensional ideals, to study the scattering equations. The method renders the CHY-integrand of scattering amplitudes computable using simple linear algebra and is amenable to an algorithmic approach. Certain identities in the amplitudes as well as rationality of the final integrand become immediate in this formalism.

  14. Diffusive scattering of electrons by electron holes around injection fronts

    Science.gov (United States)

    Vasko, I. Y.; Agapitov, O. V.; Mozer, F. S.; Artemyev, A. V.; Krasnoselskikh, V. V.; Bonnell, J. W.

    2017-03-01

    Van Allen Probes have detected nonlinear electrostatic spikes around injection fronts in the outer radiation belt. These spikes include electron holes (EH), double layers, and more complicated solitary waves. We show that EHs can efficiently scatter electrons due to their substantial transverse electric fields. Although the electron scattering driven by EHs is diffusive, it cannot be evaluated via the standard quasi-linear theory. We derive analytical formulas describing local electron scattering by a single EH and verify them via test particle simulations. We show that the most efficiently scattered are gyroresonant electrons (crossing EH on a time scale comparable to the local electron gyroperiod). We compute bounce-averaged diffusion coefficients and demonstrate their dependence on the EH spatial distribution (latitudinal extent and spatial filling factor) and individual EH parameters (amplitude of electrostatic potential, velocity, and spatial scales). We show that EHs can drive pitch angle scattering of ≲5 keV electrons at rates 10-2-10-4 s-1 and, hence, can contribute to electron losses and conjugated diffuse aurora brightenings. The momentum and pitch angle scattering rates can be comparable, so that EHs can also provide efficient electron heating. The scattering rates driven by EHs at L shells L ˜ 5-8 are comparable to those due to chorus waves and may exceed those due to electron cyclotron harmonics.

  15. Comparison of Travel-Time and Amplitude Measurements for Deep-Focusing Time-Distance Helioseismology

    Science.gov (United States)

    Pourabdian, Majid; Fournier, Damien; Gizon, Laurent

    2018-04-01

    The purpose of deep-focusing time-distance helioseismology is to construct seismic measurements that have a high sensitivity to the physical conditions at a desired target point in the solar interior. With this technique, pairs of points on the solar surface are chosen such that acoustic ray paths intersect at this target (focus) point. Considering acoustic waves in a homogeneous medium, we compare travel-time and amplitude measurements extracted from the deep-focusing cross-covariance functions. Using a single-scattering approximation, we find that the spatial sensitivity of deep-focusing travel times to sound-speed perturbations is zero at the target location and maximum in a surrounding shell. This is unlike the deep-focusing amplitude measurements, which have maximum sensitivity at the target point. We compare the signal-to-noise ratio for travel-time and amplitude measurements for different types of sound-speed perturbations, under the assumption that noise is solely due to the random excitation of the waves. We find that, for highly localized perturbations in sound speed, the signal-to-noise ratio is higher for amplitude measurements than for travel-time measurements. We conclude that amplitude measurements are a useful complement to travel-time measurements in time-distance helioseismology.

  16. A two-loop four-gluon helicity amplitude in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, L.

    2000-01-06

    The authors present the two-loop pure gauge contribution to the gluon-gluon scattering amplitude with maximal helicity violation. The construction of the amplitude does not rely directly on Feynman diagrams, but instead uses its analytic properties 4--2{epsilon} dimensions. The authors evaluate the loop integrals appearing in the amplitude through order({epsilon}{sup 0})in terms of polylogarithms.

  17. Uniform semiclassical approximation for absorptive scattering systems

    International Nuclear Information System (INIS)

    Hussein, M.S.; Pato, M.P.

    1987-07-01

    The uniform semiclassical approximation of the elastic scattering amplitude is generalized to absorptive systems. An integral equation is derived which connects the absorption modified amplitude to the absorption free one. Division of the amplitude into a diffractive and refractive components is then made possible. (Author) [pt

  18. The complete experiment for backward elastic dp scattering

    International Nuclear Information System (INIS)

    Rekalo, M.P.; Piskunov, N.M.; Sitnik, I.M.

    1996-01-01

    The problem of the complete experiment in backward elastic dp scattering is analyzed. All effects due to polarization of one or two initial and one of secondary particles are considered. It is shown that the minimal set of measurements allowing to reconstruct each of four amplitudes describing this process does not comprise too complicated experiments and is quite realistic nowadays. The geography of realization of the complete experiment is briefly reviewed. 21 refs

  19. Phonon linewidth due to electron-phonon interactions with strong forward scattering in FeSe thin films on oxide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan [Univ. of Tennessee, Knoxville, TN (United States); Rademaker, Louk [Univ. of California, Santa Barbara, CA (United States); Dagotto, Elbio R. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnston, Steven [Univ. of Tennessee, Knoxville, TN (United States)

    2017-08-18

    Here, the discovery of an enhanced superconducting transition temperature Tc in monolayers of FeSe grown on several oxide substrates has opened a new route to high-Tc superconductivity through interface engineering. One proposal for the origin of the observed enhancement is an electronphonon (e-ph) interaction across the interface that peaked at small momentum transfers. In this paper, we examine the implications of such a coupling on the phononic properties of the system. We show that a strong forward scattering leads to a sizable broadening of phonon lineshape, which may result in charge instabilities at long-wavelengths. However, we further find that the inclusion of Coulombic screening significantly reduces the phonon broadening. Our results show that one might not expect anomalously broad phonon linewidths in the FeSe interface systems, despite the fact that the e-ph interaction has a strong peak in the forward scattering (small \\bfq ) direction.

  20. Interocular differences in visual quality due to ocular aberrations and scattering in a patient with post-traumatic anisocoria: A case report

    Directory of Open Access Journals (Sweden)

    Andrés Gené-Sampedro

    2012-04-01

    Full Text Available A 41-year-old patient with visual disturbances after an ocular trauma in right eye three years before was carefully analyzed and discussed. No corneal or intraocular sequelae were present. Only a significant anisocoria could be observed. Right eye (RE achieved a best spectacle-corrected visual acuity (BSCVA of 0.05 LogMAR with a refraction of +0.50 sphere and −1.25 cylinder. Left eye (LE achieved a BSCVA of 0.0 LogMAR with a refraction of +0.75 sphere and −1.00 cylinder. In photopic conditions pupil diameter was 4.96 mm for RE and 3.02 mm for LE whereas in scotopic conditions, these values were 7.45 mm and 6.71 mm, respectively. More significant levels of higher-order corneal and ocular aberrations were found in RE for the same pupil size. In addition, the scattering index (OSI was 3.8 in RE and 1.0 in LE (4-mm pupil. In conclusion, anisocoria can lead to relevant visual disturbances if significant interocular differences in ocular aberrations and scattering are present.

  1. Weak Deeply Virtual Compton Scattering

    International Nuclear Information System (INIS)

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2006-01-01

    We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities

  2. Λ scattering equations

    Science.gov (United States)

    Gomez, Humberto

    2016-06-01

    The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.

  3. Measurement of the surface-enhanced coherent anti-Stokes Raman scattering (SECARS) due to the 1574 cm(-1) surface-enhanced Raman scattering (SERS) mode of benzenethiol using low-power (CW diode lasers.

    Science.gov (United States)

    Aggarwal, Roshan L; Farrar, Lewis W; Greeneltch, Nathan G; Van Duyne, Richard P; Polla, Dennis L

    2013-02-01

    The surface-enhanced coherent anti-Stokes Raman scattering (SECARS) from a self-assembled monolayer (SAM) of benzenethiol on a silver-coated surface-enhanced Raman scattering (SERS) substrate has been measured for the 1574 cm(-1) SERS mode. A value of 9.6 ± 1.7×10(-14) W was determined for the resonant component of the SECARS signal using 17.8 mW of 784.9 nm pump laser power and 7.1 mW of 895.5 nm Stokes laser power; the pump and Stokes lasers were polarized parallel to each other but perpendicular to the grooves of the diffraction grating in the spectrometer. The measured value of resonant component of the SECARS signal is in agreement with the calculated value of 9.3×10(-14) W using the measured value of 8.7 ± 0.5 cm(-1) for the SERS linewidth Γ (full width at half-maximum) and the value of 5.7 ± 1.4×10(-7) for the product of the Raman cross section σSERS and the surface concentration Ns of the benzenethiol SAM. The xxxx component of the resonant part of the third-order nonlinear optical susceptibility |3 χxxxx((3)R)| for the 1574 cm(-1) SERS mode has been determined to be 4.3 ± 1.1×10(-5) cm·g(-1)·s(2). The SERS enhancement factor for the 1574 cm(-1) mode was determined to be 3.6 ± 0.9×10(7) using the value of 1.8×10(15) molecules/cm(2) for Ns.

  4. Particle Distribution Modification by Low Amplitude Modes

    International Nuclear Information System (INIS)

    White, R.B.; Gorelenkov, N.; Heidbrink, W.W.; Van Zeeland, M.A.

    2009-01-01

    Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.

  5. Asymptotic behaviour of physical amplitudes in a finite field theory

    International Nuclear Information System (INIS)

    Helayel Neto, J.A.; Rajpoot, S.; Smith, A.W.

    1987-01-01

    Using the N=4 super-Yang-Mills theory softly broken by supersymmetric N=1 mass terms for matter superfields, we compute the one-loop chiral + chiral → antichiral + antichiral scattering amplitude directly in superspace. By suitable choices of the mass parameters, on can endow the model with a hierarchy of light and heavy particles, and the decoupling of the heavy sector from light-light physical amplitude is studied. We also analyze the high-energy limit of the cross-section for a two physical scalar scattering and find a (logs) behaviour, which then respects the Froissart bound. (author) [pt

  6. Acceleration of the charged particles due to chaotic scattering in the combined black hole gravitational field and asymptotically uniform magnetic field

    International Nuclear Information System (INIS)

    Stuchlik, Zdenek; Kolos, Martin

    2016-01-01

    To test the role of large-scale magnetic fields in accretion processes, we study the dynamics of the charged test particles in the vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of the charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes of the charged particle dynamics provides a mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause a transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is largest and it can be ultra-relativistic. We discuss the consequences of the model of ionization of test particles forming a neutral accretion disc, or heavy ions following off-equatorial circular orbits, and we explore the fate of heavy charged test particles after ionization where no kick of heavy ions is assumed and only the switch-on effect of the magnetic field is relevant. We demonstrate that acceleration and escape of the ionized particles can be efficient along the Kerr black hole symmetry axis parallel to the magnetic field lines. We show that a strong acceleration of the ionized particles to ultra-relativistic velocities is preferred in the direction close to the magnetic field lines. Therefore, the process of ionization of Keplerian discs around the Kerr black holes can serve as a model of relativistic jets. (orig.)

  7. Neutron spectrum perturbations due to scattering materials and their effect on the average neutron energy, the spectral index, and the hardness parameter

    International Nuclear Information System (INIS)

    Wright, H.L.; Meason, J.L.; Wolf, M.; Harvey, J.T.

    1976-01-01

    Measurements have been performed on the perturbing effect of a number of scattering materials by the 'free-field' neutron leakage spectrum from a Godiva Type Critical Assembly (White Sands Missile Range Fast Burst Reactor). The results of these measurements are interpreted in relation to some of the general parameters characterizing a neutron environment, namely, the average neutron energy >10 KeV, the spectral index and the hardness parameter. Three neutron spectrum measurements have been performed, each under different experimental configurations of scattering materials. Results from these measurements show the following with relation to the spectral index: (1) The neutron environment on the core surface and at 12-inches from the core surface (free-field) yield a spectral index of 6.8, (2) The neutron environment behind a 4.75-inch Plexiglas plate yield 4.6 for the spectral index and (3) The neutron environment behind a 2-inch aluminum plate yield 6.7 for the spectral index. It is concluded that the core surface and the 12-inch from core surface neutron environment are identical with the 'free-field' neutron environment at 20-inches when considering only those neutrons with energy >10 KeV. On the other hand, it appears that the 4.75 inches of Plexiglas severely perturbs the 'free-field' neutron environment, i.e., a much harder neutron spectrum >10 KeV. In the situation where 2-inches of aluminum is used as the perturbing medium, essentially no change in the neutron spectrum >10 KeV is noted

  8. Acceleration of the charged particles due to chaotic scattering in the combined black hole gravitational field and asymptotically uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Stuchlik, Zdenek; Kolos, Martin [Silesian University in Opava, Faculty of Philosophy and Science, Institute of Physics and Research Centre of Theoretical Physics and Astrophysics, Opava (Czech Republic)

    2016-01-15

    To test the role of large-scale magnetic fields in accretion processes, we study the dynamics of the charged test particles in the vicinity of a black hole immersed into an asymptotically uniform magnetic field. Using the Hamiltonian formalism of the charged particle dynamics, we examine chaotic scattering in the effective potential related to the black hole gravitational field combined with the uniform magnetic field. Energy interchange between the translational and oscillatory modes of the charged particle dynamics provides a mechanism for charged particle acceleration along the magnetic field lines. This energy transmutation is an attribute of the chaotic charged particle dynamics in the combined gravitational and magnetic fields only, the black hole rotation is not necessary for such charged particle acceleration. The chaotic scatter can cause a transition to the motion along the magnetic field lines with small radius of the Larmor motion or vanishing Larmor radius, when the speed of the particle translational motion is largest and it can be ultra-relativistic. We discuss the consequences of the model of ionization of test particles forming a neutral accretion disc, or heavy ions following off-equatorial circular orbits, and we explore the fate of heavy charged test particles after ionization where no kick of heavy ions is assumed and only the switch-on effect of the magnetic field is relevant. We demonstrate that acceleration and escape of the ionized particles can be efficient along the Kerr black hole symmetry axis parallel to the magnetic field lines. We show that a strong acceleration of the ionized particles to ultra-relativistic velocities is preferred in the direction close to the magnetic field lines. Therefore, the process of ionization of Keplerian discs around the Kerr black holes can serve as a model of relativistic jets. (orig.)

  9. US images encoding envelope amplitude following narrow band filtering

    International Nuclear Information System (INIS)

    Sommer, F.G.; Stern, R.A.; Chen, H.S.

    1986-01-01

    Ultrasonic waveform data from phantoms having differing scattering characteristics and from normal and cirrhotic human liver in vivo were recorded within a standardized dynamic range and filtered with narrow band filters either above or below the mean recorded ultrasonic center frequency. Images created by mapping the amplitudes of received ultrasound following such filtration permitted dramatic differentiation, not discernible in conventional US images, of phantoms having differing scattering characteristics, and of normal and cirrhotic human livers

  10. Neutron scattering lengths of 3He

    International Nuclear Information System (INIS)

    Alfimenkov, V.P.; Akopian, G.G.; Wierzbicki, J.; Govorov, A.M.; Pikelner, L.B.; Sharapov, E.I.

    1976-01-01

    The total neutron scattering cross-section of 3 He has been measured in the neutron energy range from 20 meV to 2 eV. Together with the known value of coherent scattering amplitude it leads to the two sts of n 3 He scattering lengths

  11. Intermediate energy nucleon-deuteron scattering theory.

    Science.gov (United States)

    Wilson, J. W.

    1973-01-01

    Sloan's conclusion (1969) that terms of the multiple-scattering series beyond single scattering contribute only to S- and P-wave amplitudes in an S-wave separable model is examined. A comparison of experiments with the calculation at 146 MeV shows that the conclusion is valid in nucleon-deuteron scattering applications.

  12. Elementary amplitudes from full QCD and the stochastic vacuum model

    International Nuclear Information System (INIS)

    Martini, A.F.; Menon, M.J.

    2002-01-01

    In a previous work, making use of the gluon gauge-invariant two-point correlation function determined from lattice QCD in the quenched approximation and the stochastic vacuum model, we determined the elementary (parton-parton) scattering amplitude in the momentum transfer space. In this communication we compute the elementary amplitude from new lattice QCD calculations that include the effects of dynamical fermions (full QCD). The main conclusion is that the inclusion of dynamical fermions leads to a normalized elementary amplitude that decreases more quickly with the momentum transfer than that in the quenched approximation. (author)

  13. Concentric layered Hermite scatterers

    Science.gov (United States)

    Astheimer, Jeffrey P.; Parker, Kevin J.

    2018-05-01

    The long wavelength limit of scattering from spheres has a rich history in optics, electromagnetics, and acoustics. Recently it was shown that a common integral kernel pertains to formulations of weak spherical scatterers in both acoustics and electromagnetic regimes. Furthermore, the relationship between backscattered amplitude and wavenumber k was shown to follow power laws higher than the Rayleigh scattering k2 power law, when the inhomogeneity had a material composition that conformed to a Gaussian weighted Hermite polynomial. Although this class of scatterers, called Hermite scatterers, are plausible, it may be simpler to manufacture scatterers with a core surrounded by one or more layers. In this case the inhomogeneous material property conforms to a piecewise continuous constant function. We demonstrate that the necessary and sufficient conditions for supra-Rayleigh scattering power laws in this case can be stated simply by considering moments of the inhomogeneous function and its spatial transform. This development opens an additional path for construction of, and use of scatterers with unique power law behavior.

  14. Journeys through the Precision Frontier: Amplitudes for Colliders

    CERN Document Server

    2014-01-01

    This volume is a compilation of the lectures at TASI 2014. The coverage focuses on modern calculational techniques for scattering amplitudes, and on the phenomenology of QCD in hadronic collisions. Introductions to flavor physics, dark matter, and physics beyond the Standard Model are also provided. The lectures are accessible to graduate students at the initial stages of their research careers.

  15. Gauge and Gravity Amplitudes from Trees to Loops

    DEFF Research Database (Denmark)

    Huang, Rijun

    This thesis describes two subjects that I mainly work on during my PhD study. They are both about scattering amplitudes, covering gravity and gauge theories, tree and loop level, with or without supersymmetry. The rst subject is Kawai-Lewellen-Tye(KLT) relation in field theory, which mysteriously...

  16. Bursting behaviours in cascaded stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Liu Zhan-Jun; He Xian-Tu; Zheng Chun-Yang; Wang Yu-Gang

    2012-01-01

    Stimulated Brillouin scattering is studied by numerically solving the Vlasov—Maxwell system. A cascade of stimulated Brillouin scattering can occur when a linearly polarized laser pulse propagates in a plasma. It is found that a stimulated Brillouin scattering cascade can reduce the scattering and increase the transmission of light, as well as introduce a bursting behaviour in the evolution of the laser-plasma interaction. The bursting time in the reflectivity is found to be less than half the ion acoustic period. The ion temperature can affect the stimulated Brillouin scattering cascade, which can repeat several times at low ion temperatures and can be completely eliminated at high ion temperatures. For stimulated Brillouin scattering saturation, higher-harmonic generation and wave—wave interaction of the excited ion acoustic waves can restrict the amplitude of the latter. In addition, stimulated Brillouin scattering cascade can restrict the amplitude of the scattered light. (physics of gases, plasmas, and electric discharges)

  17. Hidden beauty in multiloop amplitudes

    International Nuclear Information System (INIS)

    Cachazo, Freddy; Spradlin, Marcus; Volovich, Anastasia

    2006-01-01

    Planar L-loop maximally helicity violating amplitudes in N = 4 supersymmetric Yang-Mills theory are believed to possess the remarkable property of satisfying iteration relations in L. We propose a simple new method for studying iteration relations for four-particle amplitudes which involves the use of certain linear differential operators and eliminates the need to fully evaluate any loop integrals. We carry out this procedure in explicit detail for the two-loop amplitude and prove that this method can be applied to any multiloop integral, allowing a conjectured iteration relation for any given amplitude to be tested up to polynomials in logarithms

  18. Diffraction in nuclear scattering

    International Nuclear Information System (INIS)

    Wojciechowski, H.

    1986-01-01

    The elastic scattering amplitudes for charged and neutral particles have been decomposed into diffractive and refractive parts by splitting the nuclear elastic scattering matrix elements into components responsible for these effects. It has been shown that the pure geometrical diffractive effect which carries no information about the nuclear interaction is always predominant at forward angle of elastic angular distributions. This fact suggests that for strongly absorbed particles only elastic cross section at backward angles, i.e. the refractive cross section, can give us basic information about the central nuclear potential. 12 refs., 4 figs., 1 tab. (author)

  19. Heptagon amplitude in the multi-Regge regime

    International Nuclear Information System (INIS)

    Bartels, J.

    2014-05-01

    As we have shown in previous work, the high energy limit of scattering amplitudes in N=4 supersymmetric Yang-Mills theory corresponds to the infrared limit of the 1-dimensional quantum integrable system that solves minimal area problems in AdS 5 . This insight can be developed into a systematic algorithm to compute the strong coupling limit of amplitudes in the multi-Regge regime through the solution of auxiliary Bethe Ansatz equations. We apply this procedure to compute the scattering amplitude for n=7 external gluons in different multi-Regge regions at infinite 't Hooft coupling. Our formulas are remarkably consistent with the expected form of 7-gluon Regge cut contributions in perturbative gauge theory. A full description of the general algorithm and a derivation of results is given in a forthcoming paper.

  20. Scattering amplitude and shift in self-energy in medium

    International Nuclear Information System (INIS)

    Mallik, S.

    2002-01-01

    Two simple proofs are presented for the first order virial expansion of the self-energy of a particle moving through a medium, characterised by temperature and/or chemical potential(s). One is based on the virial expansion of the self-energy operator itself, while the other is based on the analysis of its Feynman diagrams in configuration space. (orig.)

  1. Elliptic Double-Box Integrals: Massless Scattering Amplitudes beyond Polylogarithms

    Science.gov (United States)

    Bourjaily, Jacob L.; McLeod, Andrew J.; Spradlin, Marcus; von Hippel, Matt; Wilhelm, Matthias

    2018-03-01

    We derive an analytic representation of the ten-particle, two-loop double-box integral as an elliptic integral over weight-three polylogarithms. To obtain this form, we first derive a fourfold, rational (Feynman-)parametric representation for the integral, expressed directly in terms of dual-conformally invariant cross ratios; from this, the desired form is easily obtained. The essential features of this integral are illustrated by means of a simplified toy model, and we attach the relevant expressions for both integrals in ancillary files. We propose a normalization for such integrals that renders all of their polylogarithmic degenerations pure, and we discuss the need for a new "symbology" of mixed iterated elliptic and polylogarithmic integrals in order to bring them to a more canonical form.

  2. Inelastic Light Scattering Processes

    Science.gov (United States)

    Fouche, Daniel G.; Chang, Richard K.

    1973-01-01

    Five different inelastic light scattering processes will be denoted by, ordinary Raman scattering (ORS), resonance Raman scattering (RRS), off-resonance fluorescence (ORF), resonance fluorescence (RF), and broad fluorescence (BF). A distinction between fluorescence (including ORF and RF) and Raman scattering (including ORS and RRS) will be made in terms of the number of intermediate molecular states which contribute significantly to the scattered amplitude, and not in terms of excited state lifetimes or virtual versus real processes. The theory of these processes will be reviewed, including the effects of pressure, laser wavelength, and laser spectral distribution on the scattered intensity. The application of these processes to the remote sensing of atmospheric pollutants will be discussed briefly. It will be pointed out that the poor sensitivity of the ORS technique cannot be increased by going toward resonance without also compromising the advantages it has over the RF technique. Experimental results on inelastic light scattering from I(sub 2) vapor will be presented. As a single longitudinal mode 5145 A argon-ion laser line was tuned away from an I(sub 2) absorption line, the scattering was observed to change from RF to ORF. The basis, of the distinction is the different pressure dependence of the scattered intensity. Nearly three orders of magnitude enhancement of the scattered intensity was measured in going from ORF to RF. Forty-seven overtones were observed and their relative intensities measured. The ORF cross section of I(sub 2) compared to the ORS cross section of N2 was found to be 3 x 10(exp 6), with I(sub 2) at its room temperature vapor pressure.

  3. Semiclassical scattering theory

    International Nuclear Information System (INIS)

    Di Salvo, A.

    1985-01-01

    It is intended to write the semiclassical scattering amplitude as a sum of terms, each of them being associated to trajectory. First of all the classical equations of motion are studied, considering both the analytical (real and complex) solutions and a certain type of singular solutions, which behave similary to the difracted rays in optics; in particular, in the case of a central nuclear potential, classical effects like rainbow and orbiting and also wave effects like diffraction and direct reflection are singled out. Successively, considering the Debye expansion of the scattering amplitude relative to a central nuclear potential, and evaluating asymptotically each term by means of the saddle point technique, the decay exponents and difraction coefficients relative to such a potential are determined

  4. Diffraction dissociation and elastic scattering

    International Nuclear Information System (INIS)

    Verebryusov, V.S.; Ponomarev, L.A.; Smorodinskaya, N.Ya.

    1987-01-01

    In the framework of Regge scheme with supercritical pomeron a model is suggested for the NN-scattering amplitude which takes into account the contribution introduced to the intermediate state by diffraction dissociation (DD) processes. The DD amplitude is written in terms of the Deck model which has been previously applied to describing the main DD features. The calculated NN cross sections are compared with those obtained experimentally. Theoretical predictions for higher energy are presented

  5. Some tree-level string amplitudes in the NSR formalism

    International Nuclear Information System (INIS)

    Becker, Katrin; Becker, Melanie; Melnikov, Ilarion V.; Robbins, Daniel; Royston, Andrew B.

    2015-01-01

    We calculate tree level scattering amplitudes for open strings using the NSR formalism. We present a streamlined symmetry-based and pedagogical approach to the computations, which we first develop by checking two-, three-, and four-point functions involving bosons and fermions. We calculate the five-point amplitude for massless gluons and find agreement with an earlier result by Brandt, Machado and Medina. We then compute the five-point amplitudes involving two and four fermions respectively, the general form of which has not been previously obtained in the NSR formalism. The results nicely confirm expectations from the supersymmetric F 4 effective action. Finally we use the prescription of Kawai, Lewellen and Tye (KLT) to compute the amplitudes for the closed string sector.

  6. Singularities in four-body final-state amplitudes

    International Nuclear Information System (INIS)

    Adhikari, S.K.

    1978-01-01

    Like three-body amplitudes, four-body amplitudes have subenergy threshold singularities over and above total-energy singularities. In the four-body problem we encounter a new type of subenergy singularity besides the usual two- and three-body subenergy threshold singularities. This singularity will be referred to as ''independent-pair threshold singularity'' and involves pair-subenergy threshold singularities in each of the two independent pair subenergies in four-body final states. We also study the particularly interesting case of resonant two- and three-body interactions in the four-body isobar model and the rapid (singular) dependence of the isobar amplitudes they generate in the four-body phase space. All these singularities are analyzed in the multiple-scattering formalism and it is shown that they arise from the ''next-to-last'' rescattering and hence may be represented correctly by an approximate amplitude which has that rescattering

  7. A manifestly reciprocal theory of scattering in the presence of elastic media

    International Nuclear Information System (INIS)

    Wurmser, D.

    1996-01-01

    The role of elastic waves in the scattering problem is examined in the context of modern field theory. This effort builds upon a previously published, and since successfully applied formalism for solving the acoustic and electromagnetic scattering problems. It specifically addresses the scattering of acoustic waves from a fluid-solid interface, as well as the scattering of elastodynamic waves from surfaces satisfying the zero-displacement, stress-free, and solid endash solid boundary conditions. Expressions for the change in the scattering amplitude due to a perturbation in the scattering surface are derived directly from the requirement of time reversal symmetry (also known as reciprocity). These results constitute formal statements of the composite (or two-scale) model. In a typical application, the perturbation usually corresponds to Bragg scattering and is treated statistically, while the reference surface provides tilt, shadowing, and multiple scattering, and is usually treated deterministically. Used in this way, the new formalism effectively allows existing numerical and operator expansion methods to be used to calculate the scattering from rougher and/or higher dimensional surfaces than would otherwise be possible. An alternate application of the formalism is illustrated using the fluid-solid boundary as an example. A new manifestly reciprocal expression for the scattering amplitude is presented, as are the small slope and open-quote open-quote local close-quote close-quote two-scale approximations for this problem. (By local, it is meant that only local phenomena such as the tilt of the reference surface are automatically included. However, since the result is manifestly reciprocal, it is fairly straightforward to incorporate a non-local effect such as shadowing.) During the course of the discussion, the classical scattering problem is reexamined from an entirely new perspective

  8. Scattering effects of small-scale density fluctuations on reflectometric measurements in a tokamak plasma

    International Nuclear Information System (INIS)

    Garcia, J.P.; Manso, M.E.; Serra, F.M.; Mendonca, J.T.

    1989-01-01

    When a wave propagates in a non homogeneous fluctuating plasma part of the incident energy is scattered out to the nonlinear interaction between the wave and the oscillating modes perturbing the plasma. The possibility of enhanced scattering at the cutoff layer, where reflection of the incident wave occurs, has been recently suggested as the basis of a reflectometric experiment to determine the spatial location of small scale fluctuations in a fusion plasma. Here we report on the development of a theoretical model to evaluate the flux of energy scattered by fluctuations, in order to give insight about the interpretation of measurements using a microwave reflectometry diagnostic in a tokamak. The scattered field is obtained through the resolution of a (non-homogeneous) wave propagation equation where the source term is related with the nonlinear current due to the interaction between the incident wave and local fluctuations. We use a slab model for the plasma, and an ordinary (0) wave propagation along the density gradient is considered. The amplitude of the scattered wave at the border of the plasma is estimated. In order to know the contributions to the energy scattered both from the propagation region and the reflecting layer, an approach was used where perturbations are modelled by spatial step functions at several layers. The main contribution to the scattered power comes from the cutoff region, where the electric field amplitude swells as compared with the incident value. Considering the reflectometric system recently installed on the ASDEX tokamak, and using typical density profiles, expected values of the 'swelling factor' have been numerically evaluated. The role of incoherent scattering due to drift wave activity is discussed as well as the coherent scattering due to fluctuations induced by lower hybrid (LH) waves. (author) 2 refs., 4 figs

  9. Linearized least-square imaging of internally scattered data

    KAUST Repository

    Aldawood, Ali; Hoteit, Ibrahim; Turkiyyah, George M.; Zuberi, M. A H; Alkhalifah, Tariq Ali

    2014-01-01

    Internal multiples deteriorate the quality of the migrated image obtained conventionally by imaging single scattering energy. However, imaging internal multiples properly has the potential to enhance the migrated image because they illuminate zones in the subsurface that are poorly illuminated by single-scattering energy such as nearly vertical faults. Standard migration of these multiples provide subsurface reflectivity distributions with low spatial resolution and migration artifacts due to the limited recording aperture, coarse sources and receivers sampling, and the band-limited nature of the source wavelet. Hence, we apply a linearized least-square inversion scheme to mitigate the effect of the migration artifacts, enhance the spatial resolution, and provide more accurate amplitude information when imaging internal multiples. Application to synthetic data demonstrated the effectiveness of the proposed inversion in imaging a reflector that is poorly illuminated by single-scattering energy. The least-square inversion of doublescattered data helped delineate that reflector with minimal acquisition fingerprint.

  10. Integration rules for scattering equations

    International Nuclear Information System (INIS)

    Baadsgaard, Christian; Bjerrum-Bohr, N.E.J.; Bourjaily, Jacob L.; Damgaard, Poul H.

    2015-01-01

    As described by Cachazo, He and Yuan, scattering amplitudes in many quantum field theories can be represented as integrals that are fully localized on solutions to the so-called scattering equations. Because the number of solutions to the scattering equations grows quite rapidly, the contour of integration involves contributions from many isolated components. In this paper, we provide a simple, combinatorial rule that immediately provides the result of integration against the scattering equation constraints for any Möbius-invariant integrand involving only simple poles. These rules have a simple diagrammatic interpretation that makes the evaluation of any such integrand immediate. Finally, we explain how these rules are related to the computation of amplitudes in the field theory limit of string theory.

  11. On the scattering of composite particles

    International Nuclear Information System (INIS)

    Garsevanishvili, V.R.

    1975-01-01

    The ''light front'' form of the quasipotential approach is applied to the study of interactions of relativistic composite objects. The expression for the scattering amplitude of the composite particle on the elementary one is obtained and analysed

  12. Slope of differential cross sections and size of hadron spin-flip amplitude

    International Nuclear Information System (INIS)

    Selyugin, O.V.

    1998-01-01

    A possibility to obtain restrictions of the size of the elastic spin-flip hadron scattering amplitude from the exactly measured experimental data on the differential cross sections of elastic hadron-hadron scattering is shown and possible sizes are calculated. Appropriate estimations confirm the previous analysis of experimental data at √s = 540 GeV and a probable contribution of the hadron spin-flip amplitude

  13. Quantum-mechanical few-body scattering equations with half-on-shell energy-independent subsystem input

    International Nuclear Information System (INIS)

    Zeiger, E.M.

    1978-01-01

    New equations are presented for three- and four-body scattering, within the context of nonrelativistic quantum mechanics and a Hamiltonian scattering theory. For the three-body case Faddeev-type equations are presented which, although obtained from the rigorous Faddeev theory, only require two-body bound state wave functions and half-off-shell transition amplitudes as input. In addition, their effective potentials are independent of the three-body energy, and can easily be made real after an angular momentum decomposition. The equations are formulated in terms of physical transition amplitudes for three-body processes, except that in the breakup case the partial-wave amplitudes differ from the corresponding full amplitudes by a Watson final-state-interaction factor. Also presented are new equations for four-body scattering, obtained by generalizing our three-body formalism to the four-body case. These equations, although equivalent to those of Faddeev--Yakubovskii, are expressed in terms of singularity-free transition amplitudes, and their energy-independent effective potentials require only half-on-shell subsystem transition amplitudes (and bound state wave functions) as input. However, due to the detailed index structure of the Faddeev--Yakubovskii formalsim, the result of the generalization is considerably more complicated than in the three-body case

  14. pp elastic scattering at LHC energies

    Energy Technology Data Exchange (ETDEWEB)

    Kohara, A.K.; Ferreira, E.; Kodama, T. [Universidade Federal do Rio de Janeiro, Instituto de Fisica, C.P. 68528, Rio de Janeiro, RJ (Brazil)

    2014-11-15

    Using a unified analytic representation for the elastic scattering amplitudes of pp scattering valid for all energies above 20 GeV, the behavior of observables in the LHC collisions in the range √(s) = 2.76-14 TeV is discussed. After the precise description of dσ/dt at 7 TeV, we discuss the energy dependence of the amplitudes and expect that the proposed analytical forms give equally good predictions for the future experiments. (orig.)

  15. pp elastic scattering at LHC energies

    International Nuclear Information System (INIS)

    Kohara, A.K.; Ferreira, E.; Kodama, T.

    2014-01-01

    Using a unified analytic representation for the elastic scattering amplitudes of pp scattering valid for all energies above 20 GeV, the behavior of observables in the LHC collisions in the range √(s) = 2.76-14 TeV is discussed. After the precise description of dσ/dt at 7 TeV, we discuss the energy dependence of the amplitudes and expect that the proposed analytical forms give equally good predictions for the future experiments. (orig.)

  16. Multiscalar production amplitudes beyond threshold

    CERN Document Server

    Argyres, E N; Kleiss, R H

    1993-01-01

    We present exact tree-order amplitudes for $H^* \\to n~H$, for final states containing one or two particles with non-zero three-momentum, for various interaction potentials. We show that there are potentials leading to tree amplitudes that satisfy unitarity, not only at threshold but also in the above kinematical configurations and probably beyond. As a by-product, we also calculate $2\\to n$ tree amplitudes at threshold and show that for the unbroken $\\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they vanish for $n\\ge 3~$ and for a model potential, respecting tree-order unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of the one-loop $1\\to n$ amplitude in both symmetric and spontaneously broken $\\phi^4$ theory.

  17. Amplitude damping of vortex modes

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2010-09-01

    Full Text Available An interferometer, mimicking an amplitude damping channel for vortex modes, is presented. Experimentally the action of the channel is in good agreement with that predicted theoretically. Since we can characterize the action of the channel on orbital...

  18. Amplitude and phase modulation with waveguide optics

    International Nuclear Information System (INIS)

    Burkhart, S.C.; Wilcox, R.B.; Browning, D.; Penko, F.A.

    1996-01-01

    We have developed amplitude and phase modulation systems for glass lasers using integrated electro-optic modulators and solid state high-speed electronics. The present and future generation of lasers for Inertial Confinement Fusion require laser beams with complex temporal and phase shaping to compensate for laser gain saturation, mitigate parametric processes such as transverse stimulated Brillouin scattering in optics, and to provide specialized drive to the fusion targets. These functions can be performed using bulk optoelectronic modulators, however using high-speed electronics to drive low voltage integrated optical modulators has many practical advantages. In particular, we utilize microwave GaAs transistors to perform precision, 250 ps resolution temporal shaping. Optical bandwidth is generated using a microwave oscillator at 3 GHz amplified by a solid state amplifier. This drives an integrated electrooptic modulator to achieve laser bandwidths exceeding 30 GHz

  19. Polynomial structures in one-loop amplitudes

    International Nuclear Information System (INIS)

    Britto, Ruth; Feng Bo; Yang Gang

    2008-01-01

    A general one-loop scattering amplitude may be expanded in terms of master integrals. The coefficients of the master integrals can be obtained from tree-level input in a two-step process. First, use known formulas to write the coefficients of (4-2ε)-dimensional master integrals; these formulas depend on an additional variable, u, which encodes the dimensional shift. Second, convert the u-dependent coefficients of (4-2ε)-dimensional master integrals to explicit coefficients of dimensionally shifted master integrals. This procedure requires the initial formulas for coefficients to have polynomial dependence on u. Here, we give a proof of this property in the case of massless propagators. The proof is constructive. Thus, as a byproduct, we produce different algebraic expressions for the scalar integral coefficients, in which the polynomial property is apparent. In these formulas, the box and pentagon contributions are separated explicitly.

  20. Reducing full one-loop amplitudes to scalar integrals at the integrand level

    International Nuclear Information System (INIS)

    Ossola, Giovanni; Papadopoulos, Costas G.; Pittau, Roberto

    2007-01-01

    We show how to extract the coefficients of the 4-, 3-, 2- and 1-point one-loop scalar integrals from the full one-loop amplitude of arbitrary scattering processes. In a similar fashion, also the rational terms can be derived. Basically no information on the analytical structure of the amplitude is required, making our method appealing for an efficient numerical implementation

  1. Reducing full one-loop amplitudes to scalar integrals at the integrand level

    Science.gov (United States)

    Ossola, Giovanni; Papadopoulos, Costas G.; Pittau, Roberto

    2007-02-01

    We show how to extract the coefficients of the 4-, 3-, 2- and 1-point one-loop scalar integrals from the full one-loop amplitude of arbitrary scattering processes. In a similar fashion, also the rational terms can be derived. Basically no information on the analytical structure of the amplitude is required, making our method appealing for an efficient numerical implementation.

  2. Theorems of low energy in Compton scattering

    International Nuclear Information System (INIS)

    Chahine, J.

    1984-01-01

    We have obtained the low energy theorems in Compton scattering to third and fouth order in the frequency of the incident photon. Next we calculated the polarized cross section to third order and the unpolarized to fourth order in terms of partial amplitudes not covered by the low energy theorems, what will permit the experimental determination of these partial amplitudes. (Author) [pt

  3. The Bateman method for multichannel scattering theory

    International Nuclear Information System (INIS)

    Kim, Y. E.; Kim, Y. J.; Zubarev, A. L.

    1997-01-01

    Accuracy and convergence of the Bateman method are investigated for calculating the transition amplitude in multichannel scattering theory. This approximation method is applied to the calculation of elastic amplitude. The calculated results are remarkably accurate compared with those of exactly solvable multichannel model

  4. Double collinear splitting amplitudes at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Sborlini, Germán F.R. [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain); Florian, Daniel de [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Rodrigo, Germán [Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain)

    2014-01-07

    We compute the next-to-leading order (NLO) QCD corrections to the 1→2 splitting amplitudes in different dimensional regularization (DREG) schemes. Besides recovering previously known results, we explore new DREG schemes and analyze their consistency by comparing the divergent structure with the expected behavior predicted by Catani’s formula. Through the introduction of scalar-gluons, we show the relation among splittings matrices computed using different schemes. Also, we extended this analysis to cover the double collinear limit of scattering amplitudes in the context of QCD+QED.

  5. Numerical construction of 'optimal' nonoscillating amplitude and phase functions

    International Nuclear Information System (INIS)

    Matzkin, A.; Lombardi, M.

    2002-01-01

    A numerical recipe for the construction of nonoscillating amplitude and phase functions for potentials with a single minimum is given. We give different examples illustrating the recipe, showing the usefulness of the procedure for the construction of basis functions in bound-state scattering processes, such as those described by quantum defect theory. The resulting amplitude and accumulated phase functions are coined as 'optimal' nonoscillating (as a function of the space and energy variables) because they are the counterpart for the quantum problem of the classical action for the analog semiclassical problem

  6. From magnetized iron bars to amplitude imaging of hadronic reactions

    International Nuclear Information System (INIS)

    Svec, M.

    1989-01-01

    Instruments shape research and determine which discoveries are made. Considering spin observables as carriers of information on nonperturbative QCD dynamics in hadronic reactions, we examine the relevance of amplitude analysis for the design goals of high intensity hadron facilities. New instrumental goals emerge: Hadron facility dedicated to continous measurements of spin observables and to cumulative production of computer images of scattering amplitudes over broad kinematic regions. The facility is viewed as a single instrument and termed spinoscope. We stress its connections to frontier developments in computer industries and to studies of nonperturbative states in condensed matter

  7. On tree amplitudes of supersymmetric Einstein-Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim; Casali, Eduardo; Roehrig, Kai A.; Skinner, David [Department of Applied Mathematics & Theoretical Physics, University of Cambridge,Wilberforce Road, Cambridge, CB3 0WA United Kingdom (United Kingdom)

    2015-12-29

    We present a new formula for all single trace tree amplitudes in four dimensional super Yang-Mills coupled to Einstein supergravity. Like the Cachazo-He-Yuan formula, our expression is supported on solutions of the scattering equations, but with momenta written in terms of spinor helicity variables. Supersymmetry and parity are both manifest. In the pure gravity and pure Yang-Mills sectors, it reduces to the known twistor-string formulae. We show that the formula behaves correctly under factorization and sketch how these amplitudes may be obtained from a four-dimensional (ambi)twistor string.

  8. π-π scattering in a consistent relativistic quark model

    International Nuclear Information System (INIS)

    Micu, L.

    1977-12-01

    Introducing the expression of the interpolating field of a pion as a product of suitable modified free quark fields and of a scalar unquantified field into the LSZ formalism one deduces the vanishing of the exotic amplitudes and of the π-π scattering lengths. The asymptotic vanishing of the elastic π - π scattering amplitude may also be obtained under special requirements. (author)

  9. Decoherence due to elastic rayleigh scattering

    CSIR Research Space (South Africa)

    Uys, H

    2010-11-01

    Full Text Available . acknowledges support from Georgia Tech and IARPA. D.M. is supported by NSF. This work was supported by the DARPA OLE program and by IARPA. This manuscript is the contribution of NIST and is not subject to U.S. copyright. *huys@csir.co.za †john...

  10. Elastic and quasielastic scattering of light nuclei in the theory of multiple scattering

    International Nuclear Information System (INIS)

    Ismatov, E.I.; Kuterbekov, K.A.; Dzhuraev, Sh.Kh.; Ehsaniyazov, Sh.P.; Zholdasova, S.M.

    2005-01-01

    In the work the calculation method for diffraction scattering amplitudes of light nuclei by heavy nuclei is developed. For A 1 A 2 -scattering effects of pair-, three-fold, and four-fold screenings are estimated. It is shown, that in amplitude calculations for A 1 A 2 elastic scattering it is enough come to nothing more than accounting of total screenings in the first order. Analysis of nucleus-nucleus scattering sensitive characteristics to choice of single-particle nuclear densities parametrization is carried out

  11. Validity of Miles Equation in Predicting Propellant Slosh Damping in Baffled Tanks at Variable Slosh Amplitude

    Science.gov (United States)

    Yang, H. Q.; West, Jeff

    2018-01-01

    Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involves the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations were mainly carried out by extensive experiments. A systematical study is needed to understand the damping physics of baffled tanks, to identify the difference between the empirical Miles equation and experimental measurements, and to develop new semi-empirical relations to better represent the real damping physics. The approach of this study is to use Computational Fluid Dynamics (CFD) technology to shed light on the damping mechanisms of a baffled tank. First, a 1-D Navier-Stokes equation representing different length scales and time scales in the baffle damping physics is developed and analyzed. Loci-STREAM-VOF, a well validated CFD solver developed at NASA MSFC, is applied to study the vorticity field around a baffle and around the fluid-gas interface to highlight the dissipation mechanisms at different slosh amplitudes. Previous measurement data is then used to validate the CFD damping results. The study found several critical parameters controlling fluid damping from a baffle: local slosh amplitude to baffle thickness (A/t), surface liquid depth to tank radius (d/R), local slosh amplitude to baffle width (A/W); and non-dimensional slosh frequency. The simulation highlights three significant damping regimes where different mechanisms dominate. The study proves that the previously found discrepancies between Miles equation and experimental measurement are not due to the measurement scatter, but rather due to different damping mechanisms at various slosh amplitudes. The limitations on the use of Miles equation are discussed based on the flow regime.

  12. SCATTERING OF SPIN WAVES BY MAGNETIC DEFECTS

    Energy Technology Data Exchange (ETDEWEB)

    Callaway, Joseph

    1962-12-15

    The scattering of spin waves by magnetic point defects is considered using a Green's function method. A partial wave expansion for the scattering amplitude is derived. An expression for the cross section is determined that includes the effect of resonant states. Application is made to the calculation of the thermal conductivity of an insulating ferromagnet. (auth)

  13. On three-particle scattering theory

    International Nuclear Information System (INIS)

    Kuz'michev, V.E.

    1977-01-01

    The approach proposed earlier by the author to three-particle scattering theory is discussed. This approach may prove to be useful for studying certain problems in the physics of few-nucleon systems. The corresponding equations for the partial components of the amplitudes and the potentials are obtained in the N-d scattering case

  14. On Fine Structure of Strings: The Universal Correction to the Veneziano Amplitude

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    We consider theories of weakly interacting higher spin particles in flat spacetime. We focus on the four-point scattering amplitude at high energies and imaginary scattering angles. The leading asymptotic of the amplitude in this regime is universal and equal to the corresponding limit of the Veneziano amplitude. In this paper, we find that the first sub-leading correction to this asymptotic is universal as well. We compute the correction using a model of relativistic strings with massive endpoints. We argue that it is unique using holography, effective theory of long strings and bootstrap techniques.

  15. Classical trajectory in non-relativistic scattering

    International Nuclear Information System (INIS)

    Williams, A.C.

    1978-01-01

    With the statistical interpretation of quantum mechanics as a guide, the classical trajectory is incorporated into quantum scattering theory. The Feynman path integral formalism is used as a starting point, and classical transformation theory is applied to the phase of the wave function so derived. This approach is then used to derive an expression for the scattering amplitude for potential scattering. It is found that the amplitude can be expressed in an impact parameter representation similar to the Glauber formalism. Connections are then made to the Glauber approximation and to semiclassical approximations derived from the Feynman path integral formalism. In extending this analysis to projectile-nucleus scattering, an approximation scheme is given with the first term being the same as in Glauber's multiple scattering theory. Higher-order approximations, thus, are found to give corrections to the fixed scatterer form of the impulse approximation inherent in the Glauber theory

  16. Delbrueck scattering of monoenergetic photons

    International Nuclear Information System (INIS)

    Kahane, S.

    1978-05-01

    The Delbrueck effect was experimentally investigated in high Z nuclei with monoenergetic photons in the range 6.8-11.4 MeV. Two different methods were used for measurements of the differential scattering cross-section, in the 25-140 deg range and in the forward direction (theta = 1.5 deg), respectively. The known Compton scattering cross-section was used in a new and unique way for the determination of the elastic scattering cross-section. Isolation of the contribution of the real Delbrueck amplitudes to the cross-section was crried out successfully. Experimental confirmation of the theoretical calculations of Papatzacos and Mork and measurement, for the first time, of the Rayleigh scattering in the 10 MeV region are also reported. One of the most interesting findings is the presence of Coulomb corrections in Delbrueck scattering at these energies. More theoretical effort is needed in this last direction. (author)

  17. The CHY representation of tree-level primitive QCD amplitudes

    International Nuclear Information System (INIS)

    Cruz, Leonardo de la; Kniss, Alexander; Weinzierl, Stefan

    2015-01-01

    In this paper we construct a CHY representation for all tree-level primitive QCD amplitudes. The quarks may be massless or massive. We define a generalised cyclic factor Ĉ(w,z) and a generalised permutation invariant function Ê(z,p,ε). The amplitude is then given as a contour integral encircling the solutions of the scattering equations with the product ĈÊ as integrand. Equivalently, it is given as a sum over the inequivalent solutions of the scattering equations, where the summand consists of a Jacobian times the product ĈÊ. This representation separates information: The generalised cyclic factor does not depend on the helicities of the external particles, the generalised permutation invariant function does not depend on the ordering of the external particles.

  18. An Analysis of Fundamental Mode Surface Wave Amplitude Measurements

    Science.gov (United States)

    Schardong, L.; Ferreira, A. M.; van Heijst, H. J.; Ritsema, J.

    2014-12-01

    Seismic tomography is a powerful tool to decipher the Earth's interior structure at various scales. Traveltimes of seismic waves are widely used to build velocity models, whereas amplitudes are still only seldomly accounted for. This mainly results from our limited ability to separate the various physical effects responsible for observed amplitude variations, such as focussing/defocussing, scattering and source effects. We present new measurements from 50 global earthquakes of fundamental-mode Rayleigh and Love wave amplitude anomalies measured in the period range 35-275 seconds using two different schemes: (i) a standard time-domain amplitude power ratio technique; and (ii) a mode-branch stripping scheme. For minor-arc data, we observe amplitude anomalies with respect to PREM in the range of 0-4, for which the two measurement techniques show a very good overall agreement. We present here a statistical analysis and comparison of these datasets, as well as comparisons with theoretical calculations for a variety of 3-D Earth models. We assess the geographical coherency of the measurements, and investigate the impact of source, path and receiver effects on surface wave amplitudes, as well as their variations with frequency in a wider range than previously studied.

  19. Small angle neutron scattering by polymer solutions

    International Nuclear Information System (INIS)

    Farnoux, B.; Jannink, G.

    1980-08-01

    Small angle neutron scattering is an experimental technique introduced since about 10 years for the observation of the polymer conformation in all the concentration range from dilute solution to the melt. After a brief recall of the elementary relations between scattering amplitude, index of refraction and scattered intensity, two concepts related to this last quantity (the contrast and the pair correlation function) are discussed in details

  20. Newtonian versus black-hole scattering

    International Nuclear Information System (INIS)

    Siopsis, G.

    1999-01-01

    We discuss non-relativistic scattering by a Newtonian potential. We show that the gray-body factors associated with scattering by a black hole exhibit the same functional dependence as scattering amplitudes in the Newtonian limit, which should be the weak-field limit of any quantum theory of gravity. This behavior arises independently of the presence of supersymmetry. The connection to two-dimensional conformal field theory is also discussed. copyright 1999 The American Physical Society

  1. String amplitudes: from field theories to number theory

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    In a variety of recent developments, scattering amplitudes hint at new symmetries of and unexpected connections between physical theories which are otherwise invisible in their conventional description via Feynman diagrams or Lagrangians. Yet, many of these hidden structures are conveniently accessible to string theory where gauge interactions and gravity arise as the low-energy excitations of open and closed strings. In this talk, I will give an intuitive picture of gravity as a double copy of gauge interactions and extend the web of relations to scalar field theories including chiral Lagrangians for Goldstone bosons. The string corrections to gauge and gravity amplitudes beyond their point-particle limit exhibit elegant mathematical structures and offer a convenient laboratory to explore modern number-theoretic concepts in a simple context. As a common theme with Feynman integrals, string amplitudes introduce a variety of periods and special functions including multiple zeta values and polylogarithms, orga...

  2. arXiv New relations for graviton-matter amplitudes

    CERN Document Server

    Plefka, Jan

    We present new relations for scattering amplitudes of color ordered gluons, massive quarks and scalars minimally coupled to gravity. Tree-level amplitudes of arbitrary matter and gluon multiplicities involving one graviton are reduced to partial amplitudes in QCD or scalar QCD. The obtained relations are a direct generalization of the recently found Einstein-Yang-Mills relations. The proof of the new relation employs a simple diagrammatic argument trading the graviton-matter couplings to an `upgrade' of a gluon coupling with a color-kinematic replacement rule enforced. The use of the Melia-Johansson-Ochirov color basis is a key element of the reduction. We comment on the generalization to multiple gravitons in the single color trace case.

  3. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Nandan, Dhritiman; Plefka, Jan [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam (Germany); Wen, Congkao [I.N.F.N. Sezione di Roma Tor Vergata,Via della Ricerca Scientifica, 00133 Roma (Italy)

    2016-10-14

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.

  4. Calculation of the real part of the nuclear amplitude at high s and small t from the Coulomb amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Gauron, P.; Nicolescu, B. [Universite Pierre et Marie Curie, Theory Group, Lab. de Physique Nucleaire et des Hautes Energies (LPNHE), CNRS 75 - Paris (France)

    2005-07-01

    A new method for the determination of the real part of the elastic scattering amplitude is examined for high energy proton-proton at small momentum transfer. This method allows us to decrease the number of model assumptions, to obtain the real part in a narrow region of momentum transfer and to test different models. The possible non-exponential behavior of the real part was found on the base of the analysis of the ISR experimental data. (authors)

  5. N-loop string amplitude

    International Nuclear Information System (INIS)

    Mandelstam, S.

    1986-06-01

    Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture

  6. Positivity of spin foam amplitudes

    International Nuclear Information System (INIS)

    Baez, John C; Christensen, J Daniel

    2002-01-01

    The amplitude for a spin foam in the Barrett-Crane model of Riemannian quantum gravity is given as a product over its vertices, edges and faces, with one factor of the Riemannian 10j symbols appearing for each vertex, and simpler factors for the edges and faces. We prove that these amplitudes are always nonnegative for closed spin foams. As a corollary, all open spin foams going between a fixed pair of spin networks have real amplitudes of the same sign. This means one can use the Metropolis algorithm to compute expectation values of observables in the Riemannian Barrett-Crane model, as in statistical mechanics, even though this theory is based on a real-time (e iS ) rather than imaginary-time e -S path integral. Our proof uses the fact that when the Riemannian 10j symbols are nonzero, their sign is positive or negative depending on whether the sum of the ten spins is an integer or half-integer. For the product of 10j symbols appearing in the amplitude for a closed spin foam, these signs cancel. We conclude with some numerical evidence suggesting that the Lorentzian 10j symbols are always nonnegative, which would imply similar results for the Lorentzian Barrett-Crane model

  7. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are

  8. Employing helicity amplitudes for resummation

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.

    2015-08-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.

  9. Distribution amplitudes of vector mesons

    Energy Technology Data Exchange (ETDEWEB)

    Braun, V.M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Broemmel, D. [Deutsches Elektronen-Synchrotron, Hamburg (Germany); Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)

    2007-11-15

    Results are presented for the lowest moment of the distribution amplitude for the K{sup *} vector meson. Both longitudinal and transverse moments are investigated. We use two flavours of O(a) improved Wilson fermions, together with a non-perturbative renormalisation of the matrix element. (orig.)

  10. Accommodative Amplitude in School-Age Children

    Directory of Open Access Journals (Sweden)

    Ikaunieks Gatis

    2017-10-01

    Full Text Available In children, intensive near-work affects the accommodation system of the eye. Younger children, due to anatomical parameters, read at smaller distance than older children and we can expect that the accommodation system of younger can be affected more than that of older children. We wanted to test this hypothesis. Some authors showed that the norms of amplitude of accommodation (AA developed by Hofstetter (1950 not always could be applied for children. We also wanted to verify these results. A total of 106 (age 7-15 children participated in the study. Distance visual acuity was measured for all children and only data of children with good visual acuity 1.0 or more (dec. units were analysed (73 children. Accommodative amplitude was measured before and after lessons using subjective push-up technique (with RAF Near Point Ruler. The results showed that the amplitude of accommodation reduced significantly (p < 0.05 during the day and decrease of AA was similar in different age groups (about ~0.70 D. Additional measurements are needed to verify that the observed changes in AA were associated with fatigue effect. The results showed lower accommodation values compared to average values calculated according to the Hofstetter equation (p < 0.05.

  11. On the complex angular momentum theory of scattering

    International Nuclear Information System (INIS)

    Thylwe, K.-E.

    1983-01-01

    A contribution to the theory of complex angular momentum techniques in the field of atomic and molecular collisions is given. A new, flexible representation of the scattering amplitude on the basis of realistic assumptions for the behaviour of the S matrix in the complex angular momentum plane is derived. The representation has the form of a sum of steepest-descent integrals, S-matrix residue terms and a symmetry-type background integral. The flexibility is due to the presence of two integer parameters which may be chosen conveniently so as to make the residue sums sufficiently convergent and to minimise the total number of important terms. (author)

  12. Scattering forms and the positive geometry of kinematics, color and the worldsheet

    Science.gov (United States)

    Arkani-Hamed, Nima; Bai, Yuntao; He, Song; Yan, Gongwang

    2018-05-01

    The search for a theory of the S-Matrix over the past five decades has revealed surprising geometric structures underlying scattering amplitudes ranging from the string worldsheet to the amplituhedron, but these are all geometries in auxiliary spaces as opposed to the kinematical space where amplitudes actually live. Motivated by recent advances providing a reformulation of the amplituhedron and planar N = 4 SYM amplitudes directly in kinematic space, we propose a novel geometric understanding of amplitudes in more general theories. The key idea is to think of amplitudes not as functions, but rather as differential forms on kinematic space. We explore the resulting picture for a wide range of massless theories in general spacetime dimensions. For the bi-adjoint ϕ 3 scalar theory, we establish a direct connection between its "scattering form" and a classic polytope — the associahedron — known to mathematicians since the 1960's. We find an associahedron living naturally in kinematic space, and the tree level amplitude is simply the "canonical form" associated with this "positive geometry". Fundamental physical properties such as locality and unitarity, as well as novel "soft" limits, are fully determined by the combinatorial geometry of this polytope. Furthermore, the moduli space for the open string worldsheet has also long been recognized as an associahedron. We show that the scattering equations act as a diffeomorphism between the interior of this old "worldsheet associahedron" and the new "kinematic associahedron", providing a geometric interpretation and simple conceptual derivation of the bi-adjoint CHY formula. We also find "scattering forms" on kinematic space for Yang-Mills theory and the Non-linear Sigma Model, which are dual to the fully color-dressed amplitudes despite having no explicit color factors. This is possible due to a remarkable fact—"Color is Kinematics"— whereby kinematic wedge products in the scattering forms satisfy the same Jacobi

  13. Multi-leg one-loop gravity amplitudes from gauge theory

    International Nuclear Information System (INIS)

    Bern, Z.; Dixon, L.; Perelstein, M.; Rozowsky, J.S.

    1999-01-01

    By exploiting relations between gravity and gauge theories, we present two infinite sequences of one-loop n-graviton scattering amplitudes: the 'maximally helicity-violating' amplitudes in N = 8 supergravity, and the 'all-plus' helicity amplitudes in gravity with any minimally coupled massless matter content. The all-plus amplitudes correspond to self-dual field configurations and vanish in supersymmetric theories. We make use of the tree-level Kawai-Lewellen-Tye (KLT) relations between open and closed string theory amplitudes, which in the low-energy limit imply relations between gravity and gauge theory tree amplitudes. For n ≤ 6, we determine the all-plus amplitudes explicitly from their unitarity cuts. The KLT relations, applied to the cuts, allow us to extend to gravity a previously found 'dimension-shifting' relation between (the cuts of) the all-plus amplitudes in gauge theory and the maximally helicity-violating amplitudes in N = 4 super-Yang-Mills theory. The gravitational version of the relation lets us determine the n ≤ 6N = 8 supergravity amplitudes from the all-plus gravity amplitudes. We infer the two series of amplitudes for all n from their soft and collinear properties, which can also be derived from gauge theory using the KLT relations

  14. Duality and multi-gluon scattering

    International Nuclear Information System (INIS)

    Mangano, M.; Parke, S.; Xu Zhan

    1988-01-01

    For the six-gluon scattering process we give explicit and simple expressions for the amplitude and its square. To achieve this we use an analogy with string theories to identify a unique procedure for writing the multi-gluon scattering amplitudes in terms of a sum of gauge invariant dual sub-amplitudes multiplied by an appropriate color (Chan-Paton) factor. The sub-amplitudes defined in this way are invariant under cyclic permutations, satisfy powerful identities which relate different non-cyclic permutations and factorize in the soft gluon limit, the two-gluon collinear limit and on multi-gluon poles. Also, to leading order in the number of colors these sub-amplitudes sum incoherently in the square of the full matrix element. The results contained here are important for Monte Carlo studies of multi-jet processes at hadron colliders as well as for understanding the general structure of QCD. (orig.)

  15. Theory of near-critical-angle scattering from a curved interface

    International Nuclear Information System (INIS)

    Fiedler-Ferrari, N.; Nussenzveig, H.M.; Wiscombe, W.J.

    1990-01-01

    A new type of diffraction effect, different from the standard semiclassical ones (rainbow, glory, forward peak, orbiting), takes place near the critical angle for total reflection at a curved interface between two homogeneous media. A theoretical treatment of this new effects is given for Mie scattering, e.g., light scattering by an air bubble in water; it can readily be extended to more general curved interface problems in a variety of different fields (quantum mechanics, acoustics, seismic waves). The relatively slowly-varying Mie diffraction pattern associated with near-critical scattering is obscured by rapid fine-structure oscillations due to interference with unrelated farside contributions. These contributions are evaluated and subtracted from the Mie amplitudes to yield the relevant nearside effects. A zero-order transitional CAM (complex angular momentum) approximation to the nearside amplitude is developed. The most important contributions arise from partial and total reflection, represented by two new diffraction integrals, designated Fresnel-Fock and Pearcey-Fock respectively. Also discussed are the WKB approximation, a known physical optics approximation and a new modified version of this approximation: they are compared with the exact nearside Mie amplitude obtained by numerical partial-wave summation, at scatterer size parameters (circumference/wavelength) ranging from 1,000 to 10,000. (author)

  16. Survey of vibration amplitudes throughout the linac

    International Nuclear Information System (INIS)

    Werner, K.L.

    1984-01-01

    The magnitude of vibrations of the Linac structure due to on site disturbances, such as cooling towers, pumps, generators, Highway 280 overpass traffic, is of interest. CN-263, for example, discusses tolerances of random (i.e., uncorrelated) quad jitter and suggests that amplitudes should not exceed 0.7 microns rms. This note describes the results of a series of measurements carried out in the summer of 1983. In general, the tolerance is not exceeded, but there appears not to be a good safety factor at low frequencies

  17. Multiple exchange and high-energy fixed-angle scattering

    CERN Document Server

    Halliday, I G; Orzalesi, C A; Tau, M

    1975-01-01

    The application of the eikonal ansatz to fermion fermion elastic scattering with Abelian vector gluon exchanges is discussed. The behaviours of the elastic scattering amplitude and the elastic form factor are considered and an important mechanism for fixed angle high energy elastic scattering is identified. (6 refs).

  18. Stationary scattering theory

    International Nuclear Information System (INIS)

    Combes, J.M.

    1980-10-01

    A complementary approach to the time dependent scattering theory for one-body Schroedinger operators is presented. The stationary theory is concerned with objects of quantum theory like scattering waves and amplitudes. In the more recent abstract stationary theory some generalized form of the Lippman-Schwinger equation plays the basic role. Solving this equation leads to a linear map between generalized eigenfunctions of the perturbed and unperturbed operators. This map is the section at fixed energy of the wave-operator from the time dependent theory. Although the radiation condition does not appears explicitely in this formulation it can be shown to hold a posteriori in a variety of situations thus restoring the link with physical theories

  19. Scruncher phase and amplitude control

    International Nuclear Information System (INIS)

    DeHaven, R.A.; Morris, C.L.; Johnson, R.; Davis, J.; O'Donnell, J.M.

    1992-01-01

    The analog controller for phase and amplitude control of a 402.5 MHz super conducting cavity is described in this paper. The cavity is a single cell with niobium explosively bonded to a copper cavity. It is used as an energy compressor for pions at the Clinton P. Anderson Meson Physics Facility (LAMPF). The controller maintains cavity frequency to within 4 degrees in phase of the LAMPF beam frequency. Field amplitude is maintained to within 2 percent. This control is accomplished at critical coupling (Q load of 1 x 10 9 ) with the use of only a 30 watt rf amplifier for accelerating fields of 6 MV/m. The design includes the use of piezoelectric crystals for fast resonance control. Three types of control, self excited, VCO, and a reference frequency driven, were tried on this cavity and we present a comparison of their performance. (Author) 4 figs., ref

  20. SCRUNCHER phase and amplitude control

    International Nuclear Information System (INIS)

    DeHaven, R.A.; Morris, C.L.; Johnson, R.; Davis, J.; O'Donnell, J.M.

    1992-01-01

    The analog controller for phase and amplitude control of a 402.5 MHz super conducting cavity is described in this paper. The cavity is a single cell with niobium explosively bonded to a copper cavity. It is used as an energy compressor for pions at the Clinton P. Anderson Meson Physics Facility (LAMPF). The controller maintains cavity frequency to within 4 degrees in phase of the LAMPF beam frequency. Field amplitude is maintained to within 2 percent. This control is accomplished at critical coupling (Q loaded of 1 x 10 9 ) with the use of only a 30 watt rf amplifier for accelerating fields of 6 MV/m. The design includes the use of piezoelectric crystals for fast resonance control. Three types of control, self excited VCO, and a reference frequency driven, were tried on this cavity and we present a comparison of their performance

  1. Deeply Virtual Neutrino Scattering

    International Nuclear Information System (INIS)

    Ales Psaker

    2007-01-01

    We investigate the extension of the deeply virtual Compton scattering process into the weak interaction sector. Standard electromagnetic Compton scattering provides a unique tool for studying hadrons, which is one of the most fascinating frontiers of modern science. In this process the relevant Compton scattering amplitude probes the hadron structure by means of two quark electromagnetic currents. We argue that replacing one of the currents with the weak interaction current can promise a new insight. The paper is organized as follows. In Sec. II we briefly discuss the features of the handbag factorization scheme. We introduce a new set of phenomenological functions, known as generalized parton distributions (GPDs) [1-6], and discuss some of their basic properties in Sec. III. An application of the GPD formalism to the neutrino-induced deeply virtual Compton scattering in the kinematics relevant to future high-intensity neutrino experiments is given in Sec. IV. The cross section results are presented in Sec. V. Finally, in Sec. VI we draw some conclusions and discuss future prospects. Some of the formal results in this paper have appeared in preliminary reports in Refs. [7] and [8], whereas a comprehensive analysis of the weak neutral and weak charged current DVCS reactions in collaboration with W. Melnitchouk and A. Radyushkin has been presented in Ref. [9

  2. Pulse amplitude modulated chlorophyll fluorometer

    Science.gov (United States)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  3. Semiclassical approach to fidelity amplitude

    International Nuclear Information System (INIS)

    García-Mata, Ignacio; Vallejos, Raúl O; Wisniacki, Diego A

    2011-01-01

    The fidelity amplitude (FA) is a quantity of paramount importance in echo-type experiments. We use semiclassical theory to study the average FA for quantum chaotic systems under external perturbation. We explain analytically two extreme cases: the random dynamics limit - attained approximately by strongly chaotic systems - and the random perturbation limit, which shows a Lyapunov decay. Numerical simulations help us to bridge the gap between both the extreme cases. (paper)

  4. Study of inelastic decay of amplitudes in 49V

    International Nuclear Information System (INIS)

    Chou, B.H.

    1980-01-01

    Inelastic decay amplitudes from d-wave resonances in 49 V were obtained for 80 resonances in the proton energy range 2.2 to 3.1 MeV. With the 3 MV Van de Graaff accelerator and high resolution system at the Triangle Universities Nuclear Laboratory, an overall resolution of 350 eV was obtained. The experiment consisted of measurements of the angular distributions of the inelastically scattered protons and the subsequent deexcitation gamma rays. Forty five resonances were assigned J/sup π/ = 5/2 + , while thirty five resonances were assigned 3/2 + . The magnitudes of three inelastic decay amplitudes and the relative signs between these three amplitudes were determined. Large amplitude correlations were observed; the data are in the striking disagreement with the extreme statistical model. The present results provide the first explicit test of the multivariate reduced width amplitude distribution of Krieger and Porter; the agreement is excellent. The physical origin of these channel correlations has not yet been explained

  5. Diffraction scattering of strongly bound system

    International Nuclear Information System (INIS)

    Kuzmichev, V.E.

    1982-04-01

    The scattering of a hadron on a strongly bound system of two hadrons (dihadron) is considered in the high-energy limit for the relative hadron-dihadron motion. The dihadron scatterer motion and the internal interaction are included in our consideration. It is shown that only small values of the internal transfer momentum of dihadron particles bring the principal contribution to the three-particle propagator in eikonal approximation. On the basis of the exact analytical solution of the integral equation for the total Green function the scattering amplitude is derived. It is shown that the scattering amplitude contains only single, double, and triple scattering terms. The three new terms to the Glauber formula for the total cross section are obtained. These terms decrease both the true total hadron-hadron cross section and the screening correction. (orig.)

  6. Thomson Scattering

    NARCIS (Netherlands)

    Donne, A. J. H.

    1994-01-01

    Thomson scattering is a very powerful diagnostic which is applied at nearly every magnetic confinement device. Depending on the experimental conditions different plasma parameters can be diagnosed. When the wave vector is much larger than the plasma Debye length, the total scattered power is

  7. Parity violation in polarized p-p scattering at 222 MEV

    International Nuclear Information System (INIS)

    Bandyopadhyay, D.; Birchall, J.; Campbell, J.; Davis, C.A.; Davison, N.E.; Page, S.A.; Ramsay, W.D.; Sekulovich, A.M.; Oers, W.T.H. van; Davis, C.A.; Healey, D.C.; Schmor, P.W.; Stinson, G.M.; Boyce, M.; Green, P.W.; Korkmaz, E.; Soukup, J.; Bowman, J.D.; Mischke, R.E.

    1989-01-01

    An experiment is in progess at TRIUMF to measure the parity-violating longitudinal analyzing power A z in polarizedp-p scattering at 222 MeV. Previous measurements at 15 and 45 MeV have determined the parity-mixed partial wave scattering amplitude to high precision. In contrast, only the ( 3 P 2 - 1 D 2 ) amplitude contributes to A z at 222 MeV. These two amplitudes yield complementary information on the underlying parity violating reaction mechanism. In a weak meson exchange model, the ( 3 P 2 - 1 D 2 ) amplitude is entirely due to rho meson exchange, and the present experiment affords a unique opportunity to measure the weak ρ-N coupling strength h ρ . At TRIUMF, a 500 nA beam of longitudinally polarized protons (p z ∼0.8) from the optically pumped polarized ion source will be scattered from a 20 cm liquid hydrogen target. A unique feature of this experiment is that A z will be measured in two different geometries (scattering and transmission mode) simultaneously, which will provide a crucial consistency check on the results. Monte Carlo simulations have confirmed that d.c. ionization chambers used to collect the transmitted and scattered protons in the two simultaneous measurements will achieve comparable statistical accuracies in the ∼ 300 hour counting time proposed for the experiment. High precision monitoring devices are being constructed and tested at TRIUMF to monitor changes in beam properties, such as beam position and residual transverse polarization, that can contribute to systematic errors in the parity violation measurements. The present status of the detector developments and systematic error controls will be discussed

  8. Elastic scattering of low energy γ-rays

    International Nuclear Information System (INIS)

    Whittingham, I.B.

    1978-05-01

    Theoretical cross sections for the elastic scattering of 245, 334, 444, 779, 1086, 1112 and 1408 keV γ-rays by Pb are obtained for scattering angles up to 150 degrees. Three sets of Rayleigh scattering amplitudes have been computed using (1) the calculations of Johnson and Cheng, (2) the K shell calculations of Brown and co-workers supplemented by form factors amplitudes for higher shells, and (3) form factor amplitudes for all shells. Nuclear Thomson amplitudes have been included for all energies and, for 1408 keV, Delbruck scattering based upon the calculations of Papatzacos and Mork has been included. Nuclear resonance scattering is show to be negligble for all energies

  9. Time-amplitude converter; Convertisseur temps-amplitude

    Energy Technology Data Exchange (ETDEWEB)

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

    1961-07-01

    It is normal in high energy physics to measure the time of flight of a particle in order to determine its mass. This can be done by the method which consists in transforming the time measurement into an analysis of amplitude, which is easier; a time-amplitude converter has therefore been built for this purpose. The apparatus here described uses a double grid control tube 6 BN 6 whose resolution time, as measured with a pulse generator, is 5 x 10{sup -11} s. The analysis of the response of a particle counter, made up of a scintillator and a photomultiplier, indicates that a time of resolution of 5 x 10{sup -10} s. can be obtained. A time of this order of magnitude is obtained experimentally with the converter. This converter has been used in the study of the time of flight of particles in a secondary beam of the accelerator Saturne. It has thus been possible to measure the energy spectrum of {pi}-mesons, of protons, and of deutons emitted from a polyethylene target bombarded by 1,4 and 2 GeV protons. (author) [French] Pour determiner la masse d'une particule, il est courant, en physique des hautes energies, de mesurer le temps de vol de cette particule. Cela peut etre fait par la methode qui consiste a transformer la mesure d'un temps en une analyse d'amplitude, plus aisee; aussi a-t-on, a cet effet, cree un convertisseur temps-amplitude. L'appareillage decrit dans cet article utilise un tube a double grille de commande 6 BN 6 dont le temps de resolution mesure avec un generateur d'impulsion est de 5.10{sup -11} s. L'analyse de la reponse d'un compteur de particules, constitue par un scintillateur et un photomultiplicateur, indique qu'un temps de resolution de 5.10{sup -10} s peut etre obtenu. Un temps de cet ordre est atteint experimentalement avec le convertisseur. Ce convertisseur a servi a l'etude du temps de vol des particules dans un faisceau secondaire de l'accelerateur Saturne. On a mesure ainsi le spectre d'energie des mesons {pi}, des protons, des deutons

  10. Variation of structural damping with response amplitude in piping systems

    International Nuclear Information System (INIS)

    Ware, A.G.

    1986-01-01

    From tests conducted over the last several years, it has become apparent that structural damping is not a single number applicable to all piping systems, but is highly dependent on piping system parameters such as supports, response amplitude, and insulation. As a result, there is considerable scatter in the available data. Furthermore, the relationships between the parameters and damping are often highly complex, interrelated, and difficult to predict. From tests of piping supported by various typical methods, two basic types of energy dissipation in the supports can be observed. The first is friction such as between spring hangers and their housings or in the internal mechanisms of constant force hangers. The second is impacting such as occurs in snubbers, rigid struts, and rod hangers. Overall, these effects lead to a wide variety of possibilities that can occur at low vibration levels and can change with only a slight perturbation of vibration amplitude. This can account for much of the scatter in the data at low strain levels. Thus damping is almost impossible to predict at low amplitudes, and extrapolation of this type data to higher amplitudes is cautioned. However, once strain levels rise above 100 to 200 micro in/in, the damping trend becomes easier to characterize. From the 100 to 200 micro in/in to 800 to 1000 micro in/in range the damping is fairly constant and is induced primarily by the supports. At the upper end of this range a threshold is reached in which damping increases with increasing strain amplitude. Data in the high strain (plastic range) is sparse since the test usually renders the pipe unsuitable for further use. 15 refs

  11. Gamma holography from multiple scattering

    International Nuclear Information System (INIS)

    Coussement, R.

    2007-01-01

    Since the introduction of heterodyne methods for synchrotron radiation (Cousesement et al. in Phys. Rev. B 54:16003, 1996; Callens et al. in Phys. Rev. 67:104423, 2003) one observes interferences between two scattering amplitudes; the scattering amplitude of resonant nuclei in a reference sample and the scattering amplitude of nuclei in the sample under investigation. Theses interferences can easily been observed as resonances in velocity spectra when one uses a time integrated method. They can also been observed as quantum beats, when one would use the time differential method. For both methods it is important that one uses a reference sample and therefore both methods disserved the name 'heterodyne methods.' As theses interferences are a product of two scattering amplitudes, the amplitude of a wave scattered form the investigated sample can be known with its phase. But it is assumed that the reference wave is known in advance by a proper choice of the reference sample. At first sight it is very likely that multiple scattering would add more complexity but in this paper it is claimed that on the contrary it provide a bonus, especially for single crystals. It provokes only a line broadening and a line shift of the resonances in the velocity spectra (or a change in the damping and frequency of the quantum beats when the time spectra are registered). Moreover these changes in the line shapes can easily be measured and they provide all the information needed to reconstruct a 3-D picture of the atomic arrangement of resonant nuclei and moreover they distinguish between different hyperfine sites. The method may be more practical for measurements on synchrotron radiation but it does also apply to velocity spectra obtained from resonant scattering with strong sources. The use of radioactive sources suffer from the disadvantage of poorer statistics or much longer accumulation times but they enjoy the advantage to be table-top and at-home experiments. As strong sources are

  12. The open superstring 6-point amplitude with manifest symmetries

    International Nuclear Information System (INIS)

    Barreiro, Luiz Antonio; Medina, Ricardo; Stieberger, Stephan

    2011-01-01

    Full text: The general tree level amplitude for massless bosons states of open superstrings has been known for a long time ago. It is clear how to obtain this general formula using vertex operators in the Ramond-Neveu-Schwarz formalism. From the beginning of the eighties the explicit expression for this formula has been known in the case of 3 and 4-point amplitudes. In that decade an attempt (with partial success) was done, by Kitazawa, to obtain the corresponding 5-point amplitude. Only in 2002 a complete and correct expression for this amplitude was obtained. Its low energy expansion was compared to the corresponding one from the low energy effective Lagrangian of the open superstring, finding a perfect match. A few years later, in 2005, it was realized that the 5-point formula could be written in a very much compact form, as a sum of two terms: each of them consisting of a momentum factor and a kinematic expression. This constituted a generalization of the 4-point amplitude case, which had been known to be cast in only one momentum factor multiplied by one kinematic expression. For this simplification to happen, known symmetries of the (tree level) scattering amplitudes were implemented in a manifest form. These symmetries are (on-shell) gauge symmetry, cyclic symmetry and twisting symmetry (or world sheet parity). In the recent years it has been realized that the N-point amplitude can be written as a sum of (N - 3)! terms (where N > 3). This result not only agrees with the 3, 4 and 5-point results, but also with the 6-point result which had been obtained by 2005, written as a sum of six terms. The expression that up to now has been obtained for the 6-point amplitude is quite complicated and, besides knowing that it consists of six terms, is not very illuminating. In this work we report on the recent result of writing the 6-point amplitude with gauge, cyclic and twisting symmetries manifest. Not only because of the manifest symmetries this result is important

  13. Model of homogeneous nucleus. Total and inelastic cross sections of nucleon-nucleus scattering

    International Nuclear Information System (INIS)

    Ponomarev, L.A.; Smorodinskaya, N.Ya.

    1985-01-01

    It is shown that the nucleon-nuckleus scattering amplitude at high energy can be easily calculated by generalization of the nucleon-nucleon scattering amplitude and satisfies a simple factorization relation. As distinct from the Glauber model, the suggested approach makes no use of the nucleonic structure of the nucleus and the hadron-nucleus scattering amplitude is not expressed in terms of hadron-nucleon scattering amplitudes. The energy dependence of total and inelastic cross sections is successfully described for a number of nuclei

  14. Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering

    Energy Technology Data Exchange (ETDEWEB)

    Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss

    2007-03-01

    We propose a new approach to the problem of rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton, or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons (''diffraction pattern''). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the LHC.

  15. Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering

    International Nuclear Information System (INIS)

    Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss

    2006-01-01

    We propose a new approach to the problem of rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton, or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons (''diffraction pattern''). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the LHC

  16. The Role of Mesonic Degrees of Freedom in Scattering of Hardrons on Nuclei

    DEFF Research Database (Denmark)

    Kofoed-Hansen, O.

    1978-01-01

    The Glauber multiple scattering is reviewed, its experimental success described and its essential approximations enumerated. A simple harmonic oscillator model of mesonic degrees of freedom is constructed and Glauber scattering evaluated. The difficulties in fitting experimental amplitude data va...

  17. Scattering theory

    International Nuclear Information System (INIS)

    Sitenko, A.

    1991-01-01

    This book emerged out of graduate lectures given by the author at the University of Kiev and is intended as a graduate text. The fundamentals of non-relativistic quantum scattering theory are covered, including some topics, such as the phase-function formalism, separable potentials, and inverse scattering, which are not always coverded in textbooks on scattering theory. Criticisms of the text are minor, but the reviewer feels an inadequate index is provided and the citing of references in the Russian language is a hindrance in a graduate text

  18. Impact parameter dynamics in quantum theory in large angle scattering

    International Nuclear Information System (INIS)

    Andriyanov, A.A.

    1975-01-01

    High energy behaviour of a free particle Green's function is studied for construction of the scattering amplitude. The main part of the Green's function is determined by eikonal scattering along the mean moment and by the total scattering along the transfered momentum. This ''impact'' approximation may be included as a first approximation in the iteration scheme for the scattering amplitude along the mean momentum, i.e. the ''impact'' perturbation theory. With the help of the ''impact'' approximation an expansion of the scattering amplitude in the impact parameter depending on interaction is obtained. These expansions are more correct than the eikonal expansions at large angle scattering. The results are illustrated grafically foe the exponential and the Yukawa potentials

  19. Amplitude modulation reflectometer for FTU

    International Nuclear Information System (INIS)

    Zerbini, M.; Buratti, P.; Centioli, C.; Amadeo, P.

    1995-06-01

    Amplitude modulation (AM) reflectometry is a modification of the classical frequency sweep technique which allows to perform unambiguous phase delay measurements. An eight-channel AM reflectometer has been realized for the measurement of density profiles on the FTU tokamak in the range. The characteristics of the instrument have been determined in extensive laboratory tests; particular attention has been devoted to the effect of interference with parasitic reflections. The reflectometer is now operating on FTU. Some examples of the first experimental data are discussed

  20. Analysis of perturbation methods for rearrangement collisions: Comparison of distorted-wave and coupled-channel-wave transition amplitudes

    International Nuclear Information System (INIS)

    Suck Salk, S.H.

    1985-01-01

    With the use of projection operators, the formal expressions of distorted-wave and coupled-channel-wave transition amplitudes for rearrangement collisions are derived. Use of projection operators (for the transition amplitudes) sharpens our understanding of the structural differences between the two transition amplitudes. The merit of each representation of the transition amplitudes is discussed. Derived perturbation potentials are found to have different structures. The rigorously derived distorted-wave Born-approximation (DWBA) transition amplitude is shown to be a generalization of the earlier DWBA expression obtained from the assumption of the dominance of elastic scattering in rearrangement collisions

  1. Nucleon-nucleon scattering data

    International Nuclear Information System (INIS)

    Bystricky, J.; Lehar, F.

    1981-01-01

    The present review contains a compilation of p-p, n-n, n-p and p-n elastic scattering data, total cross sections for elastic and inelastic nucleon-nucleon processes as well as the slope parameters and the ratios of the real to the imaginary part of the forward scattering amplitude measured at all energies. The data are given in detailed tables with comments on each measurement. Summary tables, nucleon-nucleon kinematics formulae, transformation tables for kinematics, a detailed list of references and an author index complete the paper. (orig.)

  2. Complex amplitude reconstruction by iterative amplitude-phase retrieval algorithm with reference

    Science.gov (United States)

    Shen, Cheng; Guo, Cheng; Tan, Jiubin; Liu, Shutian; Liu, Zhengjun

    2018-06-01

    Multi-image iterative phase retrieval methods have been successfully applied in plenty of research fields due to their simple but efficient implementation. However, there is a mismatch between the measurement of the first long imaging distance and the sequential interval. In this paper, an amplitude-phase retrieval algorithm with reference is put forward without additional measurements or priori knowledge. It gets rid of measuring the first imaging distance. With a designed update formula, it significantly raises the convergence speed and the reconstruction fidelity, especially in phase retrieval. Its superiority over the original amplitude-phase retrieval (APR) method is validated by numerical analysis and experiments. Furthermore, it provides a conceptual design of a compact holographic image sensor, which can achieve numerical refocusing easily.

  3. Amplitude chimeras and chimera death in dynamical networks

    International Nuclear Information System (INIS)

    Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard

    2016-01-01

    We find chimera states with respect to amplitude dynamics in a network of Stuart- Landau oscillators. These partially coherent and partially incoherent spatio-temporal patterns appear due to the interplay of nonlocal network topology and symmetry-breaking coupling. As the coupling range is increased, the oscillations are quenched, amplitude chimeras disappear and the network enters a symmetry-breaking stationary state. This particular regime is a novel pattern which we call chimera death. It is characterized by the coexistence of spatially coherent and incoherent inhomogeneous steady states and therefore combines the features of chimera state and oscillation death. Additionally, we show two different transition scenarios from amplitude chimera to chimera death. Moreover, for amplitude chimeras we uncover the mechanism of transition towards in-phase synchronized regime and discuss the role of initial conditions. (paper)

  4. Critical scattering

    International Nuclear Information System (INIS)

    Stirling, W.G.; Perry, S.C.

    1996-01-01

    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO 3 is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs

  5. High-Frequency Guided Wave Scattering by a Partly Through-Thickness Hole Based on 3D Theory

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Xu Jian; Ma Shi-Wei

    2015-01-01

    We present a theoretical investigation of the scattering of high frequency S0 Lamb mode from a circular blind hole defect in a plate based on the 3D theory. The S0 wave is incident at the frequency above the A1 mode cut-off frequency, in which the popular approximate plate theories are inapplicable. Due to the non-symmetric blind hole defect, the scattered fields will contain higher order converted modes in addition to the fundamental S0 and A0 modes. The far-field scattering amplitudes of various propagating Lamb modes for different hole sizes are inspected. The results are compared with those of lower frequencies and some different phenomena are found. Two-dimensional Fourier transform (2DFT) results of transient scattered Lamb and SH wave signals agree well with the analytical dispersion curves, which check the validity of the solutions from another point of view. (paper)

  6. Using HERA data to determine the infrared behaviour of the BFKL amplitude

    International Nuclear Information System (INIS)

    Kowalski, H.; Lipatov, L.N.; Hamburg Univ.; Ross, D.A.; Watt, G.

    2010-11-01

    We determine the infrared behaviour of the BFKL forward amplitude for gluon-gluon scattering. Our approach, based on the discrete pomeron solution, leads to an excellent description of the new combined inclusive HERA data at low values of x ( 2 . The phases of this amplitude are sensitive to the non-perturbative gluonic dynamics and could be sensitive to the presence of Beyond-the- Standard-Model particles at very high energies. (orig.)

  7. Atomic vibration amplitudes in fcc and hcp 4He through x-ray diffraction measurements

    International Nuclear Information System (INIS)

    Venkataraman, C.T.; Simmons, R.O.

    2003-01-01

    Atomic vibration amplitudes in dense fcc and hcp 4 He crystals have been measured using synchrotron x rays from the dependence of integrated Bragg intensities up to wave vectors of 91 nm -1 . Observed raw Bragg x-ray integrated intensities cover an extraordinary range, greater than 10 5 , due to the combined effect of the Debye-Waller factor and electronic form factor. From analysis of these intensities mean-square atomic vibration amplitudes Q 2 > and Lindemann ratios are determined. Path-integral Monte Carlo (PIMC) computations of Draeger and Ceperley, extrapolated to the thermodynamic limit, provide excellent agreement with these experimental results. For both present measurements and the PIMC results, one finds both a predominantly Gaussian distribution in Q 2 > and an extraordinarily large Lindemann ratio. In contrast, these directly measured x-ray values are significantly larger than published values inferred from Born-von Karman fitting to phonon dispersion measured by neutron scattering. Mildly anharmonic neon, which is fairly well described by self-consistent phonon theories, is contrasted with present results on fcc 4 He at corresponding densities

  8. Phonon scattering in graphite

    International Nuclear Information System (INIS)

    Wagner, P.

    1976-04-01

    Effects on graphite thermal conductivities due to controlled alterations of the graphite structure by impurity addition, porosity, and neutron irradiation are shown to be consistent with the phonon-scattering formulation 1/l = Σ/sub i equals 1/sup/n/ 1/l/sub i/. Observed temperature effects on these doped and irradiated graphites are also explained by this mechanism

  9. Inversion assuming weak scattering

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Gerstoft, Peter; Mosegaard, Klaus

    2013-01-01

    due to the complex nature of the field. A method based on linear inversion is employed to infer information about the statistical properties of the scattering field from the obtained cross-spectral matrix. A synthetic example based on an active high-frequency sonar demonstrates that the proposed...

  10. Light scattering by soap films

    NARCIS (Netherlands)

    Vrij, A.

    A theory is constructed describing the scattering from a liquid film (e.g., a soap film) of a light beam polarized normal to the plane of incidence. This scattering is due to the small irregular corrugations caused by thermal motion. The interference of the reflected incident beam with its multiple

  11. Covariant amplitudes in Polyakov string theory

    International Nuclear Information System (INIS)

    Aoyama, H.; Dhar, A.; Namazie, M.A.

    1986-01-01

    A manifestly Lorentz-covariant and reparametrization-invariant procedure for computing string amplitudes using Polyakov's formulation is described. Both bosonic and superstring theories are dealt with. The computation of string amplitudes is greatly facilitated by this formalism. (orig.)

  12. Tree-level disk amplitude of three closed strings

    Science.gov (United States)

    Mousavi, Sepideh; Velni, Komeil Babaei

    2018-05-01

    It has been shown that the disk-level S-matrix elements of one Ramond-Ramond (RR) and two Neveu-Schwarz-Neveu-Schwarz (NSNS) states could be found by applying the Ward identity associated with the string duality and the gauge symmetry on a given component of the S matrix. These amplitudes have appeared as the components of six different T-dual multiplets. It is predicted in the literature that there are some nonzero disk-level scattering amplitudes, such as one RR (p -1 ) form with zero transverse index and two N S N S states, could not be captured by the T-dual Ward identity. We explicitly find this amplitude in terms of a minimal context of the integral functions by the insertion of one closed string RR vertex operator and two NSNS vertex operators. From the amplitude invariance under the Ward identity associated with the NSNS gauge transformations and T-duality, we also find some integral identities.

  13. Monodromy relations in higher-loop string amplitudes

    Directory of Open Access Journals (Sweden)

    S. Hohenegger

    2017-12-01

    Full Text Available New monodromy relations of loop amplitudes are derived in open string theory. We particularly study N-point (planar and non-planar one-loop amplitudes described by a world-sheet cylinder and derive a set of relations between subamplitudes of different color orderings. Various consistency checks are performed by matching α′-expansions of planar and non-planar amplitudes involving elliptic iterated integrals with the resulting periods giving rise to two sets of multiple elliptic zeta values. The latter refer to the two homology cycles on the once-punctured complex elliptic curve and the monodromy equations provide relations between these two sets of multiple elliptic zeta values. Furthermore, our monodromy relations involve new objects for which we present a tentative interpretation in terms of open string scattering amplitudes in the presence of a non-trivial gauge field flux. Finally, we provide an outlook on how to generalize the new monodromy relations to the non-oriented case and beyond the one-loop level. Comparing a subset of our results with recent findings in the literature we find therein several serious issues related to the structure and significance of monodromy phases and the relevance of missed contributions from contour integrations.

  14. Supersymmetric Yang-Mills and supergravity amplitudes at one loop

    International Nuclear Information System (INIS)

    Hall, Anthony

    2009-01-01

    By applying the known expressions for super Yang-Mills (SYM) and supergravity (SUGRA) tree amplitudes, we write generating functions for the next-to-next-to-maximally helicity violating (NNMHV) box coefficients of SYM as well as the maximally helicity violating, next-to-maximally helicity violating, and NNMHV box coefficients for SUGRA. The all-multiplicity generating functions utilize covariant, on-shell superspace whereby the contribution from arbitrary external states in the supermultiplet can be extracted by Grassmann operators. In support of the relation between dual-Wilson loops and SYM scattering amplitudes at weak coupling, the SYM amplitudes are presented in a manifestly dual superconformal form. We introduce ordered box coefficients for calculating SUGRA quadruple cuts and prove that ordered coefficients generate physical cut amplitudes after summing over permutations of the external legs. The ordered box coefficients are produced by sewing ordered subamplitudes, previously used in applying on-shell recursion relations at tree level. We describe our verification of the results against the literature, and a formula for extracting the contributions from external gluons or gravitons to NNMHV superamplitudes is presented.

  15. On the scattering over the GKP vacuum

    International Nuclear Information System (INIS)

    Fioravanti, Davide; Piscaglia, Simone; Rossi, Marco

    2014-01-01

    By converting the asymptotic Bethe Ansatz (ABA) of N=4 SYM into non-linear integral equations, we find 2D scattering amplitudes of excitations on top of the GKP vacuum. We prove that this is a suitable and powerful set-up for the understanding and computation of the whole S-matrix. We show that all the amplitudes depend on the fundamental scalar–scalar one

  16. Cosmophysical Factors in the Fluctuation Amplitude Spectrum of Brownian Motion

    Directory of Open Access Journals (Sweden)

    Kaminsky A. V.

    2010-04-01

    Full Text Available Phenomenon of the regular variability of the fine structure of the fluctuation in the amplitude distributions (shapes of related histograms for the case of Brownian motion was investigated. We took an advantage of the dynamic light scattering method (DLS to get a stochastically fluctuated signal determined by Brownian motion. Shape of the histograms is most likely to vary, synchronous, in two proximally located independent cells containing Brownian particles. The synchronism persists in the cells distant at 2m from each other, and positioned meridionally. With a parallel-wise positioning of the cells, high probability of the synchronous variation in the shape of the histograms by local time has been observed. This result meets the previous conclusion about the dependency of histogram shapes ("fluctuation amplitudes" of the spectra of stochastic processes upon rotation of the Earth.

  17. Large-angle hadron scattering at high energies

    International Nuclear Information System (INIS)

    Goloskokov, S.V.; Kudinov, A.V.; Kuleshov, S.P.

    1981-01-01

    Basing on the quasipotential Logunov-Tavkhelidze approach, corrections to the amplitude of high-energy large-angle meson-nucleon scattering are estimated. The estimates are compared with the available experimental data on pp- and π +- p-scattering, so as to check the adequacy of the suggested scheme to account for the preasymptotic deffects. The compared results are presented in the form of tables and graphs. The following conclusions are drawn: 1. the account for corrections, due to the long-range interaction, to the amplituda gives a good aghreee main asymptotic termment between the theoretical and experimental data. 2. in the case of π +- p- scattering the corrections prove to be comparable with the main asymptotic term up to the values of transferred pulses psub(lambdac)=50 GeV/c, which results in a noticeable deviation form the quark counting rules at such energies. Nevertheless, the preasymptotic formulae do well, beginning with psub(lambdac) approximately 6 GeV/c. In case of pp-scattering the corrections are mutually compensated to a considerable degree, and the deviation from the quark counting rules is negligible

  18. A complex angular momentum theory of modified Coulomb scattering

    International Nuclear Information System (INIS)

    Thylwe, K.E.; Connor, J.N.L.

    1985-01-01

    The paper develops an exact complex angular momentum (CAM) theory of elastic scattering for a complex optical potential with a Coulombic tail. The present CAM theory avoids complications due to the long range nature of the Coulombic potential in a straightforward way. The Sommerfeld-Watson transformation together with a travelling wave (near-side far-side) decomposition, is used to obtain an exact representation for the scattering amplitude f(theta) in terms of a background integral fsub(B)(theta) and a series of subamplitudes fsup((+-))sub(n)(theta). New exact representations are derived for fsub(B)(theta) when the scattering matrix element S(lambda) possesses local symmetries of the type S(-lambda)=S(lambda)exp(+-2iπlambda) and S(-lambda)=S(lambda). The exact results obtained in this paper unify the CAM theory of scattering for Coulombic and short range potentials and are especially suitable for the introduction of semiclassical approximations. (author)

  19. Interference of Coulomb and nuclear excitation in inelastic scattering of 20Ne from 40Ca

    International Nuclear Information System (INIS)

    Ratel, Guy.

    1976-01-01

    Angular distributions at 54 and 63MeV and excitation functions from 35 to 95MeV for the elastic and inelastic scattering of 20 Ne by 40 Ca have been measured. Experimental data for the inelastic scattering leading to the 20 Ne (2 + , 1.63MeV) state show a characteristic minimum for the angular distributions and excitation functions. This phenomenon was explained by an interference effect between Coulomb and nuclear excitation amplitudes with the DWBA and the coupled-channel formalism. The existence of this interference minimum could be explained only by assuming a nuclear deformation stronger than these obtained with light ion scattering. However a small shift between the experimental data and theoretical curves suggests that effects of a stronger complex coupling or nuclear reorientation due to the large quadrupole moment of 20 Ne must be included [fr

  20. On Born approximation in black hole scattering

    Science.gov (United States)

    Batic, D.; Kelkar, N. G.; Nowakowski, M.

    2011-12-01

    A massless field propagating on spherically symmetric black hole metrics such as the Schwarzschild, Reissner-Nordström and Reissner-Nordström-de Sitter backgrounds is considered. In particular, explicit formulae in terms of transcendental functions for the scattering of massless scalar particles off black holes are derived within a Born approximation. It is shown that the conditions on the existence of the Born integral forbid a straightforward extraction of the quasi normal modes using the Born approximation for the scattering amplitude. Such a method has been used in literature. We suggest a novel, well defined method, to extract the large imaginary part of quasinormal modes via the Coulomb-like phase shift. Furthermore, we compare the numerically evaluated exact scattering amplitude with the Born one to find that the approximation is not very useful for the scattering of massless scalar, electromagnetic as well as gravitational waves from black holes.

  1. Expansion of continuum functions on resonance wave functions and amplitudes

    International Nuclear Information System (INIS)

    Bang, J.; Gareev, F.A.; Gizzatkulov, M.H.; Goncharov, S.A.

    1978-01-01

    To overcome difficulties encountered with wave functions of continuum spectrum (for example, in a shell model with continuum) the pole expansion (by the Mittag-Leffler theorem) of wave functions, scattering amplitudes and the Green functions with positive energies are considered. It is shown that resonance functions (the Gamov functions) form a complete set over which the continuum functions could be expanded. The general view of these expansions for final potentials and for the Coulomb repulsion potential are obtained and discussed. It is shown that the application of the method to nuclear structure calculations leads to simple algebraic equations

  2. Measurements of acoustic pressure at high amplitudes and intensities

    International Nuclear Information System (INIS)

    Crum, L A; Bailey, M R; Kaczkowski, P; McAteer, J A; Pishchalnikov, Y A; Sapozhnikov, O A

    2004-01-01

    In our research group, we desire measurements of the large pressure amplitudes generated by the shock waves used in shock wave lithotripsy (SWL) and the large acoustic intensities used in High Intensity Focused Ultrasound (HIFU). Conventional piezoelectric or PVDF hydrophones can not be used for such measurements as they are damaged either by cavitation, in SWL applications, or heat, in HIFU applications. In order to circumvent these difficulties, we have utilized optical fiber hydrophones in SWL that do not cavitate, and small glass probes and a scattering technique for measurements of large HIFU intensities. Descriptions of these techniques will be given as well as some typical data

  3. Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids

    Science.gov (United States)

    Adler, Laszlo; Cantrell, John H.; Yost, William T.

    2016-01-01

    Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.

  4. Nuclear Compton scattering

    International Nuclear Information System (INIS)

    Christillin, P.

    1986-01-01

    The theory of nuclear Compton scattering is reformulated with explicit consideration of both virtual and real pionic degrees of freedom. The effects due to low-lying nuclear states, to seagull terms, to pion condensation and to the Δ dynamics in the nucleus and their interplay in the different energy regions are examined. It is shown that all corrections to the one-body terms, of diffractive behaviour determined by the nuclear form factor, have an effective two-body character. The possibility of using Compton scattering as a complementary source of information about nuclear dynamics is restressed. (author)

  5. Investigation of Damping Physics and CFD Tool Validation for Simulation of Baffled Tanks at Variable Slosh Amplitude

    Science.gov (United States)

    Yang, H. Q.; West, Jeff

    2016-01-01

    Determination of slosh damping is a very challenging task as there is no analytical solution. The damping physics involves the vorticity dissipation which requires the full solution of the nonlinear Navier-Stokes equations. As a result, previous investigations were mainly carried out by extensive experiments. A systematical study is needed to understand the damping physics of baffled tanks, to identify the difference between the empirical Miles equation and experimental measurements, and to develop new semi-empirical relations to better represent the real damping physics. The approach of this study is to use Computational Fluid Dynamics (CFD) technology to shed light on the damping mechanisms of a baffled tank. First, a 1-D Navier-Stokes equation representing different length scales and time scales in the baffle damping physics is developed and analyzed. Loci-STREAM-VOF, a well validated CFD solver developed at NASA MSFC, is applied to study the vorticity field around a baffle and around the fluid-gas interface to highlight the dissipation mechanisms at different slosh amplitudes. Previous measurement data is then used to validate the CFD damping results. The study found several critical parameters controlling fluid damping from a baffle: local slosh amplitude to baffle thickness (A/t), surface liquid depth to tank radius (d/R), local slosh amplitude to baffle width (A/W); and non-dimensional slosh frequency. The simulation highlights three significant damping regimes where different mechanisms dominate. The study proves that the previously found discrepancies between Miles equation and experimental measurement are not due to the measurement scatter, but rather due to different damping mechanisms at various slosh amplitudes. The limitations on the use of Miles equation are discussed based on the flow regime.

  6. Hard scattering and gauge/string duality

    International Nuclear Information System (INIS)

    Polchinski, Joseph; Strassler, Matthew J.

    2002-01-01

    We consider high-energy fixed-angle scattering of glueballs in confining gauge theories that have supergravity duals. Although the effective description is in terms of the scattering of strings, we find that the amplitudes are hard (power law). This is a consequence of the warped geometry of the dual theory, which has the effect that in an inertial frame the string process is never in the soft regime. At small angle we find hard and Regge behaviors in different kinematic regions

  7. A complete two-loop, five-gluon helicity amplitude in Yang-Mills theory

    International Nuclear Information System (INIS)

    Badger, Simon; Mogull, Gustav; Ochirov, Alexander; O’Connell, Donal

    2015-01-01

    We compute the integrand of the full-colour, two-loop, five-gluon scattering amplitude in pure Yang-Mills theory with all helicities positive, using generalized unitarity cuts. Tree-level BCJ relations, satisfied by amplitudes appearing in the cuts, allow us to deduce all the necessary non-planar information for the full-colour amplitude from known planar data. We present our result in terms of irreducible numerators, with colour factors derived from the multi-peripheral colour decomposition. Finally, the leading soft divergences are checked to reproduce the expected infrared behaviour.

  8. A complete two-loop, five-gluon helicity amplitude in Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Simon; Mogull, Gustav; Ochirov, Alexander [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); O’Connell, Donal [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030 (United States)

    2015-10-09

    We compute the integrand of the full-colour, two-loop, five-gluon scattering amplitude in pure Yang-Mills theory with all helicities positive, using generalized unitarity cuts. Tree-level BCJ relations, satisfied by amplitudes appearing in the cuts, allow us to deduce all the necessary non-planar information for the full-colour amplitude from known planar data. We present our result in terms of irreducible numerators, with colour factors derived from the multi-peripheral colour decomposition. Finally, the leading soft divergences are checked to reproduce the expected infrared behaviour.

  9. Compton scattering

    International Nuclear Information System (INIS)

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A -2 based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required

  10. Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  11. Scattering of charged particles by a multicenter potential

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  12. Damage accumulation of bovine bone under variable amplitude loads

    Directory of Open Access Journals (Sweden)

    Abbey M. Campbell

    2016-12-01

    Full Text Available Stress fractures, a painful injury, are caused by excessive fatigue in bone. This study on damage accumulation in bone sought to determine if the Palmgren-Miner rule (PMR, a well-known linear damage accumulation hypothesis, is predictive of fatigue failure in bone. An electromagnetic shaker apparatus was constructed to conduct cyclic and variable amplitude tests on bovine bone specimens. Three distinct damage regimes were observed following fracture. Fractures due to a low cyclic amplitude loading appeared ductile (4000 μϵ, brittle due to high cyclic amplitude loading (>9000 μϵ, and a combination of ductile and brittle from mid-range cyclic amplitude loading (6500 –6750 μϵ. Brittle and ductile fracture mechanisms were isolated and mixed, in a controlled way, into variable amplitude loading tests. PMR predictions of cycles to failure consistently over-predicted fatigue life when mixing isolated fracture mechanisms. However, PMR was not proven ineffective when used with a single damage mechanism. Keywords: Bone fatigue, Bone fracture, Health system monitoring, Failure prediction

  13. Feasibility of Ocean Acoustic Waveguide Remote Sensing (OAWRS of Atlantic Cod with Seafloor Scattering Limitations

    Directory of Open Access Journals (Sweden)

    Ankita D. Jain

    2013-12-01

    scattering losses. As the sensingfrequency moves away from the resonance peak, OAWRS detection of cod becomesincreasingly less optimal, due to a rapid decrease in cod scattering amplitude. In otherenvironments where cod depth may be greater, the optimal frequencies for cod detectionare expected to increase with swim bladder resonance frequency.

  14. Scattering on plane waves and the double copy

    Science.gov (United States)

    Adamo, Tim; Casali, Eduardo; Mason, Lionel; Nekovar, Stefan

    2018-01-01

    Perturbatively around flat space, the scattering amplitudes of gravity are related to those of Yang–Mills by colour-kinematic duality, under which gravitational amplitudes are obtained as the ‘double copy’ of the corresponding gauge theory amplitudes. We consider the question of how to extend this relationship to curved scattering backgrounds, focusing on certain ‘sandwich’ plane waves. We calculate the 3-point amplitudes on these backgrounds and find that a notion of double copy remains in the presence of background curvature: graviton amplitudes on a gravitational plane wave are the double copy of gluon amplitudes on a gauge field plane wave. This is non-trivial in that it requires a non-local replacement rule for the background fields and the momenta and polarization vectors of the fields scattering on the backgrounds. It must also account for new ‘tail’ terms arising from scattering off the background. These encode a memory effect in the scattering amplitudes, which naturally double copies as well.

  15. Dynamic manipulation of the subharmonic scattering of phospholipid-coated microbubbles

    Energy Technology Data Exchange (ETDEWEB)

    Faez, Telli; Renaud, Guillaume; De Jong, Nico [Biomedical Engineering Thoraxcenter, Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam (Netherlands); Defontaine, Marielle; Calle, Samuel, E-mail: t.faez@erasmusmc.nl [INSERM U930-CNRS ERL3106, Universite Francois Rabelais, UFR Medecine, 10 bd Tonnelle, 37000 Tours (France)

    2011-10-07

    In this paper, the influence of a dynamic variation in the ambient pressure on the subharmonic response of phospholipid-coated microbubbles was investigated. The ambient pressure in water was modulated by a 2.5 kHz acoustic wave with a peak amplitude of 15 kPa. We investigated the fundamental and subharmonic emissions at two driving frequencies: 5 and 10 MHz. The modulation of the bubble radius induced by the dynamic variation in the liquid ambient pressure subsequently causes modulations of the scattered acoustic pressure at the fundamental and subharmonic frequencies (half the fundamental frequency). As a first result, we measured that the variation in the ambient pressure of 15 kPa can modulate the subharmonic amplitude up to 10 dB as compared to the static atmospheric pressure condition. As a second result, we noticed that the relative subharmonic amplitude modulation as a function of the LF acoustic pressure was symmetrical for the 5 MHz driving frequency but asymmetric for 10 MHz. In the latter case, the subharmonic amplitude was more enhanced for an ambient overpressure than reduced for an ambient depression of the same amplitude likely due to the buckling of the lipid shell. However, the fundamental amplitude was symmetrically modulated during bubble compression and expansion. Moreover, subharmonic and fundamental amplitude modulations were found to be either in phase or out of phase with the low-frequency acoustic pressure. Numerical simulations showed that this behavior can be obtained depending on the bubbles' diameter. The highest subharmonic amplitude was measured when microbubbles were insonified at 10 MHz. This fact together with the asymmetry observed in the subharmonic modulation suggests that smaller bubbles with a buckling shell are excited at 10 MHz compared to 5 MHz. These results present new potentials for in vitro characterization of contrast agent microbubbles and possibly a new imaging modality.

  16. Three-wave scattering in magnetized plasmas: From cold fluid to quantized Lagrangian.

    Science.gov (United States)

    Shi, Yuan; Qin, Hong; Fisch, Nathaniel J

    2017-08-01

    Large amplitude waves in magnetized plasmas, generated either by external pumps or internal instabilities, can scatter via three-wave interactions. While three-wave scattering is well known in collimated geometry, what happens when waves propagate at angles with one another in magnetized plasmas remains largely unknown, mainly due to the analytical difficulty of this problem. In this paper, we overcome this analytical difficulty and find a convenient formula for three-wave coupling coefficient in cold, uniform, magnetized, and collisionless plasmas in the most general geometry. This is achieved by systematically solving the fluid-Maxwell model to second order using a multiscale perturbative expansion. The general formula for the coupling coefficient becomes transparent when we reformulate it as the scattering matrix element of a quantized Lagrangian. Using the quantized Lagrangian, it is possible to bypass the perturbative solution and directly obtain the nonlinear coupling coefficient from the linear response of the plasma. To illustrate how to evaluate the cold coupling coefficient, we give a set of examples where the participating waves are either quasitransverse or quasilongitudinal. In these examples, we determine the angular dependence of three-wave scattering, and demonstrate that backscattering is not necessarily the strongest scattering channel in magnetized plasmas, in contrast to what happens in unmagnetized plasmas. Our approach gives a more complete picture, beyond the simple collimated geometry, of how injected waves can decay in magnetic confinement devices, as well as how lasers can be scattered in magnetized plasma targets.

  17. Evaluation of light scattering properties and chromophore concentrations in skin tissue based on diffuse reflectance signals at isosbestic wavelengths of hemoglobin

    Science.gov (United States)

    Yokokawa, Takumi; Nishidate, Izumi

    2016-04-01

    We investigate a method to evaluate light-scattering properties and chromophore concentrations in human skin tissue through diffuse reflectance spectroscopy using the reflectance signals acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed method, Monte Carlo simulation-based empirical formulas are used to specify the scattering parameters of skin tissue, such as the scattering amplitude a and the scattering power b, as well as the concentration of melanin C m and the total blood concentration C tb. The use of isosbestic wavelengths of hemoglobin enables the values of C m, C tb, a, and b to be estimated independently of the oxygenation of hemoglobin. The spectrum of the reduced scattering coefficient is reconstructed from the scattering parameters. Experiments using in vivo human skin tissues were performed to confirm the feasibility of the proposed method for evaluating the changes in scattering properties and chromophore concentrations in skin tissue. The experimental results revealed that light scattering is significantly reduced by the application of a glycerol solution, which indicates an optical clearing effect due to osmotic dehydration and the matching of the refractive indices of scatterers in the epidermis.

  18. Resonant scattering in the presence of an electromagnetic field

    International Nuclear Information System (INIS)

    Rosenberg, L.

    1983-01-01

    The theory of resonant reactions, in the projection-operator formulation of Feshbach, is generalized to account for the presence of an external electromagnetic field. The theory is used as the basis for the construction of low-frequency approximations for the transition amplitude. Results obtained here for scattering in a laser field confirm earlier versions of the low-frequency approximation when the resonances are isolated. However, if there are several closely spaced resonances additional terms must be included (their importance magnified by the appearance of near singularities) which account for the effect of radiative transitions between pairs of nearly degenerate resonant states. The weak-field limit of this result yields a low-frequency approximation for single-photon spontaneous bremsstrahlung which, through the inclusion of correction terms associated with closely spaced resonances, provides an improvement over the Feshbach-Yennie version derived some time ago. A separate treatment is required to deal with the limiting case of a static external field and this is worked out here in the context of a time-dependent formulation of the scattering problem. Linear and quadratic Stark splitting of the resonance positions, and resonance broadening due to the tunneling mechanism, are expected to play a significant role in the static limit and these effects are included in the approximation derived here for the transition amplitude

  19. Study of elastic scattering between heavy ions. Reaction channel influence

    International Nuclear Information System (INIS)

    Doubre, Hubert.

    1978-01-01

    The role of absorption on the behavior of heavy ion angular distributions and excitaton functions has been investigated on light and medium mass systems. Comparison between 20 Ne+ 12 C and 16 O+ 16 O systems which lead to the same compound nucleus, shows that it originates from the direct channels strongly coupled to the entrance channel. Structures in the excitation functions occur for almost all the light systems and it is shown that the damping observed for heavier systems such as 40 Ca+ 40 Ca, essentially results on the predominance of Coulomb effects which hide the nuclear structure effects. Thus no valuable information on the details of S-matrix can be extracted for such an heavy system. A coherent description of the elastic scattering, based on a splitting of the scattering amplitude into two components, the modulus of each component varying smoothly as a function of energy and angle. The interference between these sub-amplitudes give rise to interference effects in angular distributions and excitation functions. The study of the main reaction channels of the 40 Ca+ 40 Ca system - i.e. deep inelastic reactions and fusion - also shows that the closed-shell nature of the interacting nuclei does not play any role in these processes due to the excitation processes in the first stage of the reactions which destroy the specific structure of the nuclei [fr

  20. Heavy ion elastic scatterings

    International Nuclear Information System (INIS)

    Mermaz, M.C.

    1984-01-01

    Diffraction and refraction play an important role in particle elastic scattering. The optical model treats correctly and simultaneously both phenomena but without disentangling them. Semi-classical discussions in terms of trajectories emphasize the refractive aspect due to the real part of the optical potential. The separation due to to R.C. Fuller of the quantal cross section into two components coming from opposite side of the target nucleus allows to understand better the refractive phenomenon and the origin of the observed oscillations in the elastic scattering angular distributions. We shall see that the real part of the potential is responsible of a Coulomb and a nuclear rainbow which allows to determine better the nuclear potential in the interior region near the nuclear surface since the volume absorption eliminates any effect of the real part of the potential for the internal partial scattering waves. Resonance phenomena seen in heavy ion scattering will be discussed in terms of optical model potential and Regge pole analysis. Compound nucleus resonances or quasi-molecular states can be indeed the more correct and fundamental alternative

  1. Twistor diagrams and massless Moeller scattering

    International Nuclear Information System (INIS)

    Hodges, A.P.

    1983-01-01

    The theory of twistor diagrams, as devised by Penrose, is intended to lead to a manifestly finite account of scattering amplitudes in quantum field theory. The theory is here extended to a more general type of interaction between massless fields than has hitherto been described. It is applied to the example of first-order massless Moeller scattering in quantum electrodynamics. It is shown that earlier studies of this example have failed to render a correct account, in particular by overlooking an infrared divergency, but that the scattering data can nevertheless be represented within the twistor formalism. (author)

  2. Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon

    CERN Document Server

    Angelopoulos, Angelos; Locher, M P; Markushin, V E; Aslanides, Elie; Backenstoss, Gerhard; Bargassa, P; Behnke, O; Benelli, A; Bertin, V; Blanc, F; Bloch, P; Carlson, P J; Carroll, M; Cawley, E; Chertok, M B; Danielsson, M; Dejardin, M; Derré, J; Ealet, A; Eleftheriadis, C; Faravel, L; Festcher, W; Fidecaro, Maria; Filipcic, A; Francis, D; Fry, J; Gabathuler, Erwin; Gamet, R; Gerber, H J; Go, A; Haselden, A; Hayman, P J; Henry-Coüannier, F; Hollander, R W; Jon-And, K; Kettle, P R; Kokkas, P; Kreuger, R; Le Gac, R; Leimgruber, F; Mandic, I; Manthos, N; Marel, Gérard; Mikuz, M; Miller, J; Montanet, François; Müller, A; Nakada, Tatsuya; Pagels, B; Papadopoulos, I M; Pavlopoulos, P; Polivka, G; Rickenbach, R; Roberts, B L; Ruf, T; Schäfer, M; Schaller, L A; Schietinger, T; Schopper, A; Tauscher, Ludwig; Thibault, C; Touchard, F; Touramanis, C; van Eijk, C W E; Vlachos, S; Weber, P; Wigger, O; Wolter, M; Zavrtanik, D; Zimmerman, D

    1999-01-01

    We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on /sup 12/C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold $9 region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle. (29 refs).

  3. An alternative way of computation of amplitudes and intensities in time-dependent Moessbauer spectroscopy (TDMS)

    International Nuclear Information System (INIS)

    Christoskov, I.D.; Vapirev, E.I.

    1990-01-01

    An alternative way of presenting the time-dependent amplitudes and intensities of radiation, corresponding to resonant absorption and scattering experiments, is developed. Infinite series of Bessel functions with complex coefficients are replaced by simple for calculation definite integrals and the number of Bessel function calls is reduced to one per a tabulation point. Thus the calculational effort for experimental data processing becomes smaller

  4. Explicit formuli for one, two, three and four loops string amplitudes in critical dimension

    International Nuclear Information System (INIS)

    Morozov, A.Yu.

    1987-01-01

    A report on explicit formulae for loop string diagrams in the primary-quantized theory of strings is presented. In the critical dimension d=26 tachyon p-loop scattering amplitude in the theory of boson strings is presented as finite-multiple integral with respect to Riemann surface M p moduli space. Integration on M p in continual integral is determined

  5. Patterns of High energy Massive String Scatterings in the Regge Regime

    International Nuclear Information System (INIS)

    Lee Jen Chi

    2009-01-01

    We calculate high energy massive string scattering amplitudes of open bosonic string in the Regge regime (RR). We found that the number of high energy amplitudes for each fixed mass level in the RR is much more numerous than that of Gross regime (GR) calculated previously. Moreover, we discover that the leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. In particular, based on a summation algorithm for Stirling number identities developed recently, we discover that the ratios calculated previously among scattering amplitudes in the GR can be extracted from this Kummer function in the RR. We conjecture and give evidences that the existence of these GR ratios in the RR persists to sub-leading orders in the Regge expansion of all string scattering amplitudes. Finally, we demonstrate the universal power-law behavior for all massive string scattering amplitudes in the RR. (author)

  6. Analytical properties of multiple production amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, B V; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki; AN SSSR, Moscow. Matematicheskij Inst.)

    1984-05-01

    Local analytical properties of amplitudes 2..-->..3 and 2..-->..4 are studied. The amplitudes are shown to be analytical functions of total and partial energies at fixed momentum transfers in the neighbourhood of any physical point on the energy shell 14 (for the 2..-->..3 case) and 242 (for the 2..-->..4 case) boundary values are expressed through the amplitudes of real processes.

  7. Regge cuts in γγ scattering

    International Nuclear Information System (INIS)

    Jackson, C.P.

    1976-01-01

    It is shown that the Pomeron-Pomeron cut in γγ scattering has natural C parity and conspires, in contrast to the Pomeron pole which is evasive, and has natural parity and C parity. The constraints this places upon the invariant amplitudes are analyzed

  8. Precise relative cross sections for np scattering

    International Nuclear Information System (INIS)

    Goetz, J.; Brogli-Gysin, C.; Hammans, M.; Haffter, P.; Henneck, R.; Jourdan, J.; Masson, G.; Qin, L.M.; Robinson, S.; Sick, I.; Tuccillo, M.

    1994-01-01

    We present data on the differential cross section for neutron-proton scattering for an incident neutron energy of 67 MeV. These data allow a precise determination of the 1 P 1 phase which, in phase-shift analyses, is strongly correlated with the S-D amplitude which we are measuring via different observables. ((orig.))

  9. The isomonodromy method for black hole scattering

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro da Cunha, Bruno, E-mail: bcunha@df.ufpe.br [Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife, Pernambuco (Brazil); Novaes, Fábio, E-mail: fabio.nsantos@gmail.com [International Institute of Physics, Federal University of Rio Grande do Norte, Av. Odilon Gomes de Lima 1722, Capim Macio, Natal-RN 59078-400 (Brazil)

    2015-12-17

    We summarize recent results by the authors [7, 8, 35] on the extraction of scattering amplitudes for scalar fields in Kerr/Kerr-de Sitter backgrounds. Analytical, closed forms are found in terms of the Painlevé V and VI transcendents for generic values of the physical parameters.

  10. Elastic ππ scattering to two loops

    International Nuclear Information System (INIS)

    Bijnens, J.; Colangelo, G.; Gasser, J.; Ecker, G.; Sainio, M.E.

    1995-11-01

    We evaluate analytically the elastic ππ scattering amplitude to two loops in chiral perturbation theory and give numerical values for the two S-wave scattering lengths and for the phase shift difference δ 0 0 -δ 1 1 . (author)

  11. Inelastic two composite particle systems scattering at high energy

    International Nuclear Information System (INIS)

    Zhang Yushun.

    1986-11-01

    In this paper, by using the collective coordinate of Bohr and phenomenological deformed optical potentials, the scattering amplitudes of two composite particle systems can be obtained and the collective excitation for two composite particle systems in the scattering process is discussed. (author). 10 refs, 6 figs, 2 tabs

  12. K correlations and facet models in diffuse scattering

    NARCIS (Netherlands)

    Hoenders, B.J.; Jakeman, E.; Baltes, H.P.; Steinle, B.

    1979-01-01

    The angular intensity distribution of radiation scattered by a wide range of random media can be accounted for by assuming effective source amplitude correlations involving modified Bessel functions Kv. We investigate how such correlations can be derived from physical models of stochastic scattering

  13. Elastic scattering

    International Nuclear Information System (INIS)

    Leader, Elliot

    1991-01-01

    With very few unexplained results to challenge conventional ideas, physicists have to look hard to search for gaps in understanding. An area of physics which offers a lot more than meets the eye is elastic and diffractive scattering where particles either 'bounce' off each other, emerging unscathed, or just graze past, emerging relatively unscathed. The 'Blois' workshops provide a regular focus for this unspectacular, but compelling physics, attracting highly motivated devotees

  14. Interpretation of second Born amplitudes in electron capture

    International Nuclear Information System (INIS)

    McGuire, J.H.; Simony, P.R.; Weaver, O.L.; Macek, J.

    1982-01-01

    Exact sound Born amplitudes for 1s-1s electron capture are presented and interpreted in terms of contributions from intermediate states off the energy shell and on the energy shell. The classical model of Thomas corresponds to two-step scattering via one particular on-shell intermediate state. In the high-velocity limit for 1s-1s capture, this on-shell intermediate state of the Thomas model accounts for one-half of the total cross section, i.e., the second Born cross section. The other half comes from off-energy-shell intermediate states near the on-shell Thomas state. Above 5 MeV both the off-shell and on-shell amplitudes have a simple structure near the Thomas peak. Below 1 MeV, contributions from a broader range of intermediate states are evident in the amplitudes. Although the contribution from the Thomas state is not large below 1 MeV, other second Born effects are significant

  15. Neutron scattering

    International Nuclear Information System (INIS)

    1991-02-01

    The annual report on hand gives an overview of the research work carried out in the Laboratory for Neutron Scattering (LNS) of the ETH Zuerich in 1990. Using the method of neutron scattering, it is possible to examine in detail the static and dynamic properties of the condensed material. In accordance with the multidisciplined character of the method, the LNS has for years maintained a system of intensive co-operation with numerous institutes in the areas of biology, chemistry, solid-state physics, crystallography and materials research. In 1990 over 100 scientists from more than 40 research groups both at home and abroad took part in the experiments. It was again a pleasure to see the number of graduate students present, who were studying for a doctorate and who could be introduced into the neutron scattering during their stay at the LNS and thus were in the position to touch on central ways of looking at a problem in their dissertation using this modern experimental method of solid-state research. In addition to the numerous and interesting ways of formulating the questions to explain the structure, nowadays the scientific programme increasingly includes particularly topical studies in connection with high temperature-supraconductors and materials research

  16. Scattering theory

    CERN Document Server

    Friedrich, Harald

    2016-01-01

    This corrected and updated second edition of "Scattering Theory" presents a concise and modern coverage of the subject. In the present treatment, special attention is given to the role played by the long-range behaviour of the projectile-target interaction, and a theory is developed, which is well suited to describe near-threshold bound and continuum states in realistic binary systems such as diatomic molecules or molecular ions. It is motivated by the fact that experimental advances have shifted and broadened the scope of applications where concepts from scattering theory are used, e.g. to the field of ultracold atoms and molecules, which has been experiencing enormous growth in recent years, largely triggered by the successful realization of Bose-Einstein condensates of dilute atomic gases in 1995. The book contains sections on special topics such as near-threshold quantization, quantum reflection, Feshbach resonances and the quantum description of scattering in two dimensions. The level of abstraction is k...

  17. Convergence of the multiple scattering expansion in XAFS and XANES

    International Nuclear Information System (INIS)

    Rehr, J.J.

    1992-01-01

    The convergence of the multiple-scattering expansion of XAFS and XANES by explicit path-bypath calculations. The approach is based on the fast scattering matrix formalism of Rehr and Albers, together with an automated path finder and filters that exclude negligible paths. High-order scattering terms are found to be essential, especially at low energies. Several factors including the magnitude of curved wave scattering amplitudes, inelastic losses and multiple-scattering Debye-Waller factors control convergence of the expansion. The convergence is illustrated explicitly for the case of diatomic molecules

  18. Pion deuteron scattering at intermediate energies

    International Nuclear Information System (INIS)

    Ferreira, E.M.

    1978-09-01

    A comparison is made of results of calculations of πd elastic scattering cross section using multiple scattering and three-body equations, in relation to their ability to reproduce the experimental data at intermediate energies. It is shown that the two methods of theoretical calculation give quite similar curves for the elastic differential cross sections, and that both fail in reproducing backward scattering data above 200MeV. The new accurate experimental data on πd total cross section as a function of the energy are confronted with the theoretical values obtained from the multiple scattering calculation through the optical theorem. Comparison is made between the values of the real part of the forward amplitude evaluated using dispersion relations and using the multiple scattering method [pt

  19. Compton scattering by mesons in nuclei: Experiment on 208Pb

    International Nuclear Information System (INIS)

    Fuhrberg, K.; Martin, G.; Haeger, D.; Ludwig, M.; Schumacher, M.; Andersson, B.E.; Blomqvist, K.I.; Ruijter, H.; Sandell, A.; Schroeder, B.; Hayward, E.; Nilsson, L.; Zorro, R.

    1992-01-01

    Using 58 and 73 MeV tagged photons and scattering angles from 60deg to 150deg, it is shown that is possible to observe Compton scattering by 'mesons in nuclei ' through an incomplete cancellation of the mesonic (exchange- current) seagull amplitude by parts of the nuclear resonance amplitude related to the giant-dipole resonance of 208 Pb. This phenomenon is a property of an extended nucleus and , therefore, cannot be dtudied on the deuteron. Predictions of the exchange form factor which determines the angular distribution of the exchange seagull amplitude are compared with experimental data. (orig.)

  20. Do we understand elastic scattering up to LHC energies?

    International Nuclear Information System (INIS)

    Soffer, Jacques

    2013-01-01

    The measurements of high energy (bar sign)pp and pp elastic at ISR, SPS, and Tevatron colliders have provided usefull informations on the behavior of the scattering amplitude. A large step in energy domain is accomplished with the LHC collider presently running, giving a unique opportunity to improve our knowledge on the asymptotic regime of the elastic scattering amplitude and to verify the validity of our theoretical approach, to describe the total cross section σ tot (s), the total elastic cross section σ el (s), the ratio of the real to imaginary parts of the forward amplitude ρ(s) and the differential cross section dσ (s,t)/dt.