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Sample records for multi-parton scattering amplitudes

  1. Bootstrapping Multi-Parton Loop Amplitudes in QCD

    SciTech Connect

    Bern, Zvi; Dixon, Lance J.; Kosower, David A.; /Saclay, SPhT

    2005-07-06

    The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.

  2. Calculating scattering amplitudes efficiently

    SciTech Connect

    Dixon, L.

    1996-01-01

    We review techniques for more efficient computation of perturbative scattering amplitudes in gauge theory, in particular tree and one- loop multi-parton amplitudes in QCD. We emphasize the advantages of (1) using color and helicity information to decompose amplitudes into smaller gauge-invariant pieces, and (2) exploiting the analytic properties of these pieces, namely their cuts and poles. Other useful tools include recursion relations, special gauges and supersymmetric rearrangements. 46 refs., 11 figs.

  3. Multi-parton loop amplitudes and next-to-leading order jet cross-sections

    SciTech Connect

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

    1998-02-01

    The authors review recent developments in the calculation of QCD loop amplitudes with several external legs, and their application to next-to-leading order jet production cross-sections. When a number of calculational tools are combined together--helicity, color and supersymmetry decompositions, plus unitarity and factorization properties--it becomes possible to compute multi-parton one-loop QCD amplitudes without ever evaluating analytically standard one-loop Feynman diagrams. One-loop helicity amplitudes are now available for processes with five external partons (ggggg, q{anti q}ggg and q{anti q}q {anti q}{prime} g), and for an intermediate vector boson V {equivalent_to} {gamma}{sup *}, Z, W plus four external partons (V q{anti q} and V q{anti q}q{prime}{anti q}{prime}). Using these amplitudes, numerical programs have been constructed for the next-to-leading order corrections to the processes p{anti p} {yields} 3 jets (ignoring quark contributions so far) and e{sup +}e{sup -} {yields} 4 jets.

  4. One-Loop Multi-Parton Amplitudes with a Vector Boson for the LHC

    SciTech Connect

    Berger, C.F.; Bern, Z.; Dixon, L.J.; Cordero, F.Febres; Forde, D.; Ita, H.; Kosower, D.A.; Maitre, D.; /SLAC

    2008-08-11

    In this talk, we present the first, numerically stable, results for the one-loop amplitudes needed for computing W; Z + 3 jet cross sections at the LHC to next-to-leading order in the QCD coupling. We implemented these processes in BlackHat, an automated program based on on-shell methods. These methods scale very well with increasing numbers of external partons, and are applicable to a wide variety of problems of phenomenological interest at the LHC.

  5. Topics in Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Dennen, Tristan Lucas

    In Part 1, we combine on-shell methods with the six-dimensional helicity formalism of Cheung and O'Connell to construct tree-level and multiloop scattering amplitudes. As a nontrivial multiloop example, we confirm that the recently constructed four-loop four-point amplitude of N=4 super-Yang-Mills theory, including nonplanar contributions, is valid for dimensions less than or equal to six. We demonstrate that the tree-level amplitudes of maximal super-Yang-Mills theory in six dimensions, when stripped of their overall momentum and supermomentum delta functions, are covariant with respect to the six-dimensional dual conformal group. We demonstrate that this property is also present for loop amplitudes. In Part 2, we explore consequences of the recently discovered duality between color and kinematics, which states that kinematic numerators in a diagrammatic expansion of gauge-theory amplitudes can be arranged to satisfy Jacobi-like identities in one-to-one correspondence to the associated color factors. The related squaring relations express gravity amplitudes in terms of gauge-theory ingredients. We then present a Yang-Mills Lagrangian whose diagrams through five points manifestly satisfy the duality between color and kinematics. Finally, we compute the coefficient of the potential three-loop divergence in pure N=4 supergravity and show that it vanishes, contrary to expectations from symmetry arguments.

  6. Effective string theory and QCD scattering amplitudes

    SciTech Connect

    Makeenko, Yuri

    2011-01-15

    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.

  7. Deep Inelastic Scattering at the Amplitude Level

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2005-08-04

    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.

  8. CAMORRA: A C++ library for recursive computation of particle scattering amplitudes

    NASA Astrophysics Data System (ADS)

    Kleiss, R.; van den Oord, G.

    2011-02-01

    We present a new Monte Carlo tool that computes full tree-level matrix elements in high-energy physics. The program accepts user-defined models and has no restrictions on the process multiplicity. To achieve acceptable performance, CAMORRA evaluates the matrix elements in a recursive way by combining off-shell currents. Furthermore, CAMORRA can be used to compute amplitudes involving continuous color and helicity final states. Program summaryProgram title: CAMORRA Catalogue identifier: AEHN_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHN_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL version 2 No. of lines in distributed program, including test data, etc.: 252 572 No. of bytes in distributed program, including test data, etc.: 1 711 469 Distribution format: tar.gz Programming language: C++ Computer: All Operating system: Tested on Linux and Mac OS, but should work on any system Classification: 4.4 Nature of problem: Current recursive matrix element computation programs are confined to standard model amplitudes, whereas many new physics signatures and backgrounds at hadron colliders are associated with multi-parton final states. Solution method: The library applies the Berends-Giele/Caravaglios-Moretti recursive algorithm in a generic way applicable to a wide range of quantum field theories. It allows the user to define a new physics model and consequently compute its predicted scattering amplitudes with exponential growth of the computing time with process multiplicity rather than factorial growth. Restrictions: There are no built-in restrictions on process complexity. Unusual features: CAMORRA can cope with Majorana fermions. Running time: A ten-gluon amplitude typically takes 9 ms per event.

  9. Amplitude for N-Gluon Superstring Scattering

    SciTech Connect

    Stieberger, Stephan; Taylor, Tomasz R.

    2006-11-24

    We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope {alpha}{sup '}. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in {alpha}{sup '}, for the so-called maximally helicity violating configurations, with N=4, 5 and N=6. We also obtain the leading O({alpha}{sup '2}) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.

  10. Scattering amplitudes with off-shell quarks

    NASA Astrophysics Data System (ADS)

    van Hameren, A.; Kutak, K.; Salwa, T.

    2013-11-01

    We present a prescription to calculate manifestly gauge invariant tree-level scattering amplitudes for arbitrary scattering processes with off-shell initial-state quarks within the kinematics of high-energy scattering. Consider the embedding of the process, in which the off-shell u-quark is replaced by an auxiliary quark qA, and an auxiliary photon γA is added in final state. The momentum flow is as if qA carries momentum k1 and the momentum of γA is identical to 0. γA only interacts via Eq. (3), and qA further only interacts with gluons via normal quark-gluon vertices. qA-line propagators are interpreted as iℓ̸1/(2ℓ1ṡp), and are diagonal in color space. Sum the squared amplitude over helicities of the auxiliary photon. For one helicity, simultaneously assign to the external qA-quark and to γA the spinor and polarization vector |ℓ1], {<ℓ1|γμ|ℓ2]}/{√{2}[ℓ1|ℓ2]}, and for the other helicity assign |ℓ1>, {<ℓ2|γμ|ℓ1]}/{√{2}<ℓ2|ℓ1>}. Multiply the amplitude with √{-x1k12/2}. For the rest, normal Feynman rules apply.Some remarks are at order. Regarding the momentum flow, we stress, as in [20], that momentum components proportional to k1 do not contribute in the eikonal propagators, and there is a freedom in the choice of the momenta flowing through qA-lines.Regarding the sum over helicities, one might argue that only one of them leads to a non-zero result for given helicity of the final-state quark, but there may, for example, be several identical such quarks in the final state with different helicities.In case of more than one quark in the final state with the same flavor as the off-shell quark, the rules as such admit graphs with γA-propagators. These must be omitted. They do not survive the limit Λ→∞ in the derivation, since the γA-propagators are suppressed by 1/Λ.The rules regarding the qA-line could be elaborated further like in [20], leading to simplified vertices for gluons attached to this line and reducing the

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Recurrence relations of Kummer functions and Regge string scattering amplitudes

    NASA Astrophysics Data System (ADS)

    Lee, Jen-Chi; Mitsuka, Yoshihiro

    2013-04-01

    We discover an infinite number of recurrence relations among Regge string scattering amplitudes [11, 30] of different string states at arbitrary mass levels in the open bosonic string theory. As a result, all Regge string scattering amplitudes can be algebraically solved up to multiplicative factors. Instead of decoupling zero-norm states in the fixed angle regime, the calculation is based on recurrence relations and addition theorem of Kummer functions of the second kind. These recurrence relations among Regge string scattering amplitudes are dual to linear relations or symmetries among high-energy fixed angle string scattering amplitudes discovered previously.

  13. Scattering amplitudes in gauge theories: progress and outlook Scattering amplitudes in gauge theories: progress and outlook

    NASA Astrophysics Data System (ADS)

    Roiban, Radu; Spradlin, Marcus; Volovich, Anastasia

    2011-11-01

    This issue aims to serve as an introduction to our current understanding of the structure of scattering amplitudes in gauge theory, an area which has seen particularly rapid advances in recent years following decades of steady progress. The articles contained herein provide a snapshot of the latest developments which we hope will serve as a valuable resource for graduate students and other scientists wishing to learn about the current state of the field, even if our continually evolving understanding of the subject might soon render this compilation incomplete. Why the fascination with scattering amplitudes, which have attracted the imagination and dedicated effort of so many physicists? Part of it stems from the belief, supported now by numerous examples, that unexpected simplifications of otherwise apparently complicated calculations do not happen by accident. Instead they provide a strong motivation to seek out an underlying explanation. The insight thereby gained can subsequently be used to make the next class of seemingly impossible calculations not only possible, but in some cases even trivial. This two-pronged strategy of exploring and exploiting the structure of gauge theory amplitudes appeals to a wide audience from formal theorists interested in mathematical structure for the sake of its own beauty to more phenomenologically-minded physicists eager to speed up the next generation of analysis software. Understandably it is the maximally supersymmetric 𝒩 = 4 Yang-Mills theory (SYM) which has the simplest structure and has correspondingly received the most attention. Rarely in theoretical physics are we fortunate enough to encounter a toy model which is simple enough to be solved completely yet rich enough to possess interesting non-trivial structure while simultaneously, and most importantly, being applicable (even if only as a good approximation) to a wide range of 'real' systems. The canonical example in quantum mechanics is of course the harmonic

  14. Calculation of the Scattering Amplitude Without Partial Wave Expansion

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Two developments in the direct calculation of the angular differential scattering amplitude have been implemented: (a) The integral expansion of the scattering amplitude is simplified by analytically integration over the azimuthal angle. (b) The resulting integral as a function of scattering angle is calculated by using the numerically generated wave function from a finite element method calculation. Results for electron-hydrogen scattering in the static approximation will be shown to be as accurate as a partial wave expansion with as many l's as is necessary for convergence at the incident energy being calculated.

  15. Multiple parton scattering in nuclei: Beyond helicity amplitude approximation

    SciTech Connect

    Zhang, Ben-Wei; Wang, Xin-Nian

    2003-01-21

    Multiple parton scattering and induced parton energy loss in deeply inelastic scattering (DIS) off heavy nuclei is studied within the framework of generalized factorization in perturbative QCD with a complete calculation beyond the helicity amplitude (or soft bremsstrahlung) approximation. Such a calculation gives rise to new corrections to the modified quark fragmentation functions. The effective parton energy loss is found to be reduced by a factor of 5/6 from the result of helicity amplitude approximation.

  16. Scattering Amplitudes: The Most Perfect Microscopic Structures in the Universe

    SciTech Connect

    Dixon, Lance J.; /CERN /SLAC

    2011-11-04

    This article gives an overview of many of the recent developments in understanding the structure of relativistic scattering amplitudes in gauge theories ranging from QCD to N = 4 super-Yang-Mills theory, as well as (super)gravity. I also provide a pedagogical introduction to some of the basic tools used to organize and illuminate the color and kinematic structure of amplitudes. This article is an invited review introducing a special issue of Journal of Physics A devoted to 'Scattering Amplitudes in Gauge Theories'.

  17. Compact Multigluonic Scattering Amplitudes with Heavy Scalars and Fermions

    SciTech Connect

    Ferrario, Paola; Rodrigo, German; Talavera, Pere

    2006-05-12

    Combining the Berends-Giele and on-shell recursion relations we obtain an extremely compact expression for the scattering amplitude of a complex massive scalar-antiscalar pair and an arbitrary number of positive helicity gluons. This is one of the basic building blocks for constructing other helicity configurations from recursion relations. We also show explicitly that the scattering amplitude of massive fermions to gluons, all with positive helicity, is proportional to the scalar one, confirming in this way the recently advocated SUSY-like Ward identities relating both amplitudes.

  18. Loop Integrands for Scattering Amplitudes from the Riemann Sphere

    NASA Astrophysics Data System (ADS)

    Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Tourkine, Piotr

    2015-09-01

    The scattering equations on the Riemann sphere give rise to remarkable formulas for tree-level gauge theory and gravity amplitudes. Adamo, Casali, and Skinner conjectured a one-loop formula for supergravity amplitudes based on scattering equations on a torus. We use a residue theorem to transform this into a formula on the Riemann sphere. What emerges is a framework for loop integrands on the Riemann sphere that promises to have a wide application, based on off-shell scattering equations that depend on the loop momentum. We present new formulas, checked explicitly at low points, for supergravity and super-Yang-Mills amplitudes and for n -gon integrands at one loop. Finally, we show that the off-shell scattering equations naturally extend to arbitrary loop order, and we give a proposal for the all-loop integrands for supergravity and planar super-Yang-Mills theory.

  19. Loop Integrands for Scattering Amplitudes from the Riemann Sphere.

    PubMed

    Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Tourkine, Piotr

    2015-09-18

    The scattering equations on the Riemann sphere give rise to remarkable formulas for tree-level gauge theory and gravity amplitudes. Adamo, Casali, and Skinner conjectured a one-loop formula for supergravity amplitudes based on scattering equations on a torus. We use a residue theorem to transform this into a formula on the Riemann sphere. What emerges is a framework for loop integrands on the Riemann sphere that promises to have a wide application, based on off-shell scattering equations that depend on the loop momentum. We present new formulas, checked explicitly at low points, for supergravity and super-Yang-Mills amplitudes and for n-gon integrands at one loop. Finally, we show that the off-shell scattering equations naturally extend to arbitrary loop order, and we give a proposal for the all-loop integrands for supergravity and planar super-Yang-Mills theory. PMID:26430983

  20. Wilson loops and QCD/string scattering amplitudes

    SciTech Connect

    Makeenko, Yuri; Olesen, Poul

    2009-07-15

    We generalize modern ideas about the duality between Wilson loops and scattering amplitudes in N=4 super Yang-Mills theory to large N QCD by deriving a general relation between QCD meson scattering amplitudes and Wilson loops. We then investigate properties of the open-string disk amplitude integrated over reparametrizations. When the Wilson-loop is approximated by the area behavior, we find that the QCD scattering amplitude is a convolution of the standard Koba-Nielsen integrand and a kernel. As usual poles originate from the first factor, whereas no (momentum-dependent) poles can arise from the kernel. We show that the kernel becomes a constant when the number of external particles becomes large. The usual Veneziano amplitude then emerges in the kinematical regime, where the Wilson loop can be reliably approximated by the area behavior. In this case, we obtain a direct duality between Wilson loops and scattering amplitudes when spatial variables and momenta are interchanged, in analogy with the N=4 super Yang-Mills theory case.

  1. Collinear limit of scattering amplitudes at strong coupling.

    PubMed

    Basso, Benjamin; Sever, Amit; Vieira, Pedro

    2014-12-31

    In this Letter, we consider the collinear limit of gluon scattering amplitudes in planar N=4 super-Yang-Mills theory at strong coupling. We argue that in this limit scattering amplitudes map into correlators of twist fields in the two dimensional nonlinear O(6) sigma model, similar to those appearing in recent studies of entanglement entropy. We provide evidence for this assertion by combining the intuition springing from the string world-sheet picture and the predictions coming from the operator product expansion series. One of the main implications of these considerations is that scattering amplitudes receive equally important contributions at strong coupling from both the minimal string area and its fluctuations in the sphere. PMID:25615305

  2. Effective Field Theories from Soft Limits of Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Cheung, Clifford; Kampf, Karol; Novotny, Jiri; Trnka, Jaroslav

    2015-06-01

    We derive scalar effective field theories—Lagrangians, symmetries, and all—from on-shell scattering amplitudes constructed purely from Lorentz invariance, factorization, a fixed power counting order in derivatives, and a fixed order at which amplitudes vanish in the soft limit. These constraints leave free parameters in the amplitude which are the coupling constants of well-known theories: Nambu-Goldstone bosons, Dirac-Born-Infeld scalars, and Galilean internal shift symmetries. Moreover, soft limits imply conditions on the Noether current which can then be inverted to derive Lagrangians for each theory. We propose a natural classification of all scalar effective field theories according to two numbers which encode the derivative power counting and soft behavior of the corresponding amplitudes. In those cases where there is no consistent amplitude, the corresponding theory does not exist.

  3. Effective Field Theories from Soft Limits of Scattering Amplitudes.

    PubMed

    Cheung, Clifford; Kampf, Karol; Novotny, Jiri; Trnka, Jaroslav

    2015-06-01

    We derive scalar effective field theories-Lagrangians, symmetries, and all-from on-shell scattering amplitudes constructed purely from Lorentz invariance, factorization, a fixed power counting order in derivatives, and a fixed order at which amplitudes vanish in the soft limit. These constraints leave free parameters in the amplitude which are the coupling constants of well-known theories: Nambu-Goldstone bosons, Dirac-Born-Infeld scalars, and Galilean internal shift symmetries. Moreover, soft limits imply conditions on the Noether current which can then be inverted to derive Lagrangians for each theory. We propose a natural classification of all scalar effective field theories according to two numbers which encode the derivative power counting and soft behavior of the corresponding amplitudes. In those cases where there is no consistent amplitude, the corresponding theory does not exist. PMID:26196613

  4. Light focusing through strongly scattering media by binary amplitude modulation

    NASA Astrophysics Data System (ADS)

    Huang, Hui-ling; Sun, Cun-zhi; Chen, Zi-yang; Pu, Ji-xiong

    2015-07-01

    Based on the angular spectrum method and the circular Gaussian distribution (CGD) model of scattering media, we numerically simulate light focusing through strongly scattering media. A high contrast focus in the target area is produced by using feedback optimization algorithm with binary amplitude modulation. It is possible to form the focusing with one focus or multiple foci at arbitrary areas. The influence of the number of square segments of spatial light modulation on the enhancement factor of intensity is discussed. Simulation results are found to be in good agreement with theoretical analysis for light refocusing.

  5. Infrared singularities of scattering amplitudes in perturbative QCD

    SciTech Connect

    Becher, Thomas; Neubert, Matthias

    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.

  6. Analytical {pi}{pi} scattering amplitude and the light scalars

    SciTech Connect

    Achasov, N. N.; Kiselev, A. V.

    2011-03-01

    In this work we construct the {pi}{pi} scattering amplitude T{sub 0}{sup 0} with regular analytical properties in the s complex plane, which describes simultaneously the data on the {pi}{pi} scattering, {phi}{yields}{pi}{sup 0}{pi}0{gamma} decay, and {pi}{pi}{yields}KK reaction. The chiral shielding of the {sigma}(600) meson and its mixing with the f{sub 0}(980) meson are also taken into account. The data agrees with the four-quark nature of the {sigma}(600) and f{sub 0}(980) mesons. The amplitude in the range -5m{sub {pi}}{sup 2}

  7. [ital I]=2 pion scattering amplitude with Wilson fermions

    SciTech Connect

    Gupta, R. ); Patel, A. ); Sharpe, S.R. )

    1993-07-01

    We present an exploratory calculation of the [ital I]=2 [pi][pi] scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find good agreement with the predictions of chiral perturbation theory even for pions of mass 560--700 MeV. Within 10% error, we do not see the onset of the bad chiral behavior expected for Wilson fermions. We also derive rigorous inequalities that apply to two-particle correlators and as a consequence show that the interaction in the antisymmetric state of two pions has to be attractive.

  8. Scattering amplitude of a single fracture under uniaxial stress

    NASA Astrophysics Data System (ADS)

    Blum, T. E.; van Wijk, K.; Snieder, R.

    2014-05-01

    Remotely sensing the properties of fractures has applications ranging from exploration geophysics to hazard monitoring. Newly developed capabilities to measure the in-plane component of dense laser-based ultrasound wave fields allow us to test the applicability of a linear slip model to describe fracture properties. In particular, we estimate the diameter, and the normal and tangential compliance of a fracture from the measured scattering amplitudes of P and S waves in the laboratory. Finally, we show that the normal compliance decreases linearly with increasing uniaxial static stress in the plane of the fracture, but that our measurements of the SV scattered field do not show significant changes in the tangential compliance.

  9. The Stoyanovsky-Ribault Map and String Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Giribet, Gaston; Nakayama, Yu

    Recently, Ribault and Teschner pointed out the existence of a one-to-one correspondence between N-point correlation functions for the SL(2,ℂ)k/SU(2) WZNW model on the sphere and certain set of 2N-2-point correlation functions in Liouville field theory. This result is based on a seminal work by Stoyanovsky. Here, we discuss the implications of this correspondence focusing on its application to string theory on curved backgrounds. For instance, we analyze how the divergences corresponding to worldsheet instantons in AdS3 can be understood as arising from the insertion of the dual screening operator in the Liouville theory side. We also study the pole structure of N-point functions in the 2D Euclidean black hole and its holographic meaning in terms of the Little String Theory. This enables us to interpret the correspondence between CFT's as encoding a LSZ-type reduction procedure. Furthermore, we discuss the scattering amplitudes violating the winding number conservation in those backgrounds and provide a formula connecting such amplitudes with observables in Liouville field theory. Finally, we study the WZNW correlation functions in the limit k → 0 and show that, at the point k = 0, the Stoyanovsky-Ribault-Teschner dictionary turns out to be in agreement with the FZZ conjecture at a particular point of the space of parameters where the Liouville central charge becomes cL = -2. This result makes contact with recent studies on the dynamical tachyon condensation in closed string theory.

  10. Strong-field cyclotron scattering. I - Scattering amplitudes and natural line width

    NASA Astrophysics Data System (ADS)

    Graziani, Carlo

    1993-07-01

    The introduction of resonance line width into the QED cyclotron scattering amplitudes is considered. It is shown that the width arises from loop corrections to the electron propagator, which also bring about shifts in the Landau energy levels. A formalism is developed that allows the dressed electron propagator to be derived. It is shown that the states of Herold et al. (1982) and of Sokolov and Ternov (1968), which diagonalize the component of the magnetic moment operator parallel to the external magnetic field, are appropriate for calculation of the scattering amplitudes, whereas the states of Johnson and Lippmann (1949) are not. In addition, it is shown that the Breit-Wigner broadening approximation E tends to E - i(Gamma)/2 is consistent with the perturbation-theoretic order of the calculation, if the former basis states are chosen, but not the latter.

  11. Relating multichannel scattering and production amplitudes in a microscopic OZI-based model

    SciTech Connect

    Beveren, Eef van Rupp, George

    2008-05-15

    Relations between scattering and production amplitudes are studied in a microscopic multichannel model for meson-meson scattering, with coupling to confined quark-antiquark channels. Overlapping resonances and a proper threshold behaviour are treated exactly in the model. Under the spectator assumption, it is found that the two-particle production amplitude shares a common denominator with the elastic scattering amplitude, besides a numerator consisting of a linear combination of all elastic and some inelastic matrix elements. The coefficients in these linear combinations are shown to be generally complex. Finally, the standard operator expressions relating production and scattering amplitudes, viz. A=T/VandIm(A)=T*A, are fulfilled, while in the small-coupling limit the usual isobar model is recovered.

  12. Calculation of the Full Scattering Amplitude without Partial Wave Decomposition. 2; Inclusion of Exchange

    NASA Technical Reports Server (NTRS)

    Shertzer, Janine; Temkin, Aaron

    2004-01-01

    The development of a practical method of accurately calculating the full scattering amplitude, without making a partial wave decomposition is continued. The method is developed in the context of electron-hydrogen scattering, and here exchange is dealt with by considering e-H scattering in the static exchange approximation. The Schroedinger equation in this approximation can be simplified to a set of coupled integro-differential equations. The equations are solved numerically for the full scattering wave function. The scattering amplitude can most accurately be calculated from an integral expression for the amplitude; that integral can be formally simplified, and then evaluated using the numerically determined wave function. The results are essentially identical to converged partial wave results.

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

    NASA Astrophysics Data System (ADS)

    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

  14. Implementation of the Duality between Wilson Loops and Scattering Amplitudes in QCD

    SciTech Connect

    Makeenko, Yuri; Olesen, Poul

    2009-02-20

    We generalize modern ideas about the duality between Wilson loops and scattering amplitudes in N=4 super Yang-Mills theory to large-N (or quenched) QCD. We show that the area-law behavior of asymptotically large Wilson loops is dual to the Regge-Veneziano behavior of scattering amplitudes at high energies and fixed momentum transfer, when the quark mass is small and/or the number of particles is large. We elaborate on this duality for string theory in flat space, identifying the asymptotes of the disk amplitude and the Wilson loop of large-N QCD.

  15. Scattering amplitudes to all orders in meson exchange

    SciTech Connect

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

    1990-01-01

    As the number of colors in QCD, N{sub 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{sub 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 {sigma} mesons only, finding sensible results. 8 refs., 3 figs.

  16. Amplitude description of elastic pp scattering at 800 MeV

    NASA Astrophysics Data System (ADS)

    Moravcsik, Michael J.; Arash, Firooz; Goldstein, Gary R.

    1985-04-01

    Recent polarization data on proton-proton elastic scattering at 800 MeV taken at LAMPF are used for an amplitude analysis using the optimal formalism. The direct analysis of data is done in the transversity frame, which is best suited to parity-conserving reactions. From the results, amplitudes are also obtained in the helicity frame and the ``magic'' frame. Agreement with previous amplitudes obtained from an energy-dependent phase-shift analysis is good. The comparison of the helicity amplitudes c and e strengthens previous suggestions for a possible triplet-state dibaryon resonance. The comparison of the amplitudes am and cm in the magic frame indicates a possible domination of the process near 90° scattering angle by one-particle-exchange mechanism involving exchanged particles with natural parity.

  17. Quark born diagrams: Meson-meson scattering amplitudes from the nonrelativistic quark potential model

    SciTech Connect

    Barnes, T. |

    1992-12-31

    In this talk I summarize recent calculations of meson-meson scattering amplitudes in the nonrelativistic quark potential model, which assume that the scattering mechanism is one-gluon-exchange followed by constituent exchange (OGE+CEX). We refer to the scattering diagrams as ``quark Born diagrams``. For the cases chosen to isolate this mechanism, I=2 {pi}{pi} and I=3/2 K{pi}, the theoretical results are in remarkably good agreement with experimental S- and P-wave phase shifts and PCAC scattering lengths, given standard potential-model parameters.

  18. Quark born diagrams: Meson-meson scattering amplitudes from the nonrelativistic quark potential model

    SciTech Connect

    Barnes, T. Tennessee Univ., Knoxville, TN . Dept. of Physics)

    1992-01-01

    In this talk I summarize recent calculations of meson-meson scattering amplitudes in the nonrelativistic quark potential model, which assume that the scattering mechanism is one-gluon-exchange followed by constituent exchange (OGE+CEX). We refer to the scattering diagrams as quark Born diagrams''. For the cases chosen to isolate this mechanism, I=2 [pi][pi] and I=3/2 K[pi], the theoretical results are in remarkably good agreement with experimental S- and P-wave phase shifts and PCAC scattering lengths, given standard potential-model parameters.

  19. Non-Perturbative, Unitary Quantum-Particle Scattering Amplitudes from Three-Particle Equations

    SciTech Connect

    Lindesay, James V

    2002-03-19

    We here use our non-perturbative, cluster decomposable relativistic scattering formalism to calculate photon-spinor scattering, including the related particle-antiparticle annihilation amplitude. We start from a three-body system in which the unitary pair interactions contain the kinematic possibility of single quantum exchange and the symmetry properties needed to identify and substitute antiparticles for particles. We extract from it unitary two-particle amplitude for quantum-particle scattering. We verify that we have done this correctly by showing that our calculated photon-spinor amplitude reduces in the weak coupling limit to the usual lowest order, manifestly covariant (QED) result with the correct normalization. That we are able to successfully do this directly demonstrates that renormalizability need not be a fundamental requirement for all physically viable models.

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

    SciTech Connect

    Zhang Peng; Naidon, Pascal; Ueda, Masahito

    2010-12-15

    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{sub 1}(k) is given by f{sub 1}(k)=-1/[ik+1/(Vk{sup 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{sub 1}(k)=-1/[ik+1/(V{sup eff}k{sup 2})+1/(S{sup eff}k)+1/R{sup eff}] where V{sup eff}, S{sup eff}, and R{sup 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 {sup 6}Li and {sup 40}K when the scattering volume is enhanced by the resonance.

  1. Direct Calculation of the Scattering Amplitude Without Partial Wave Decomposition. III; Inclusion of Correlation Effects

    NASA Technical Reports Server (NTRS)

    Shertzer, Janine; Temkin, Aaron

    2007-01-01

    In the first two papers in this series, we developed a method for studying electron-hydrogen scattering that does not use partial wave analysis. We constructed an ansatz for the wave function in both the static and static exchange approximations and calculated the full scattering amplitude. Here we go beyond the static exchange approximation, and include correlation in the wave function via a modified polarized orbital. This correlation function provides a significant improvement over the static exchange approximation: the resultant elastic scattering amplitudes are in very good agreement with fully converged partial wave calculations for electron-hydrogen scattering. A fully variational modification of this approach is discussed in the conclusion of the article Popular summary of Direct calculation of the scattering amplitude without partial wave expansion. III ....." by J. Shertzer and A. Temkin. In this paper we continue the development of In this paper we continue the development of a new approach to the way in which researchers have traditionally used to calculate the scattering cross section of (low-energy) electrons from atoms. The basic mathematical problem is to solve the Schroedinger Equation (SE) corresponding the above physical process. Traditionally it was always the case that the SE was reduced to a sequence of one-dimensional (ordinary) differential equations - called partial waves which were solved and from the solutions "phase shifts" were extracted, from which the scattering cross section was calculated.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  4. Non-relativistic scattering amplitude for a new multi-parameter exponential-type potential

    NASA Astrophysics Data System (ADS)

    Yazarloo, B. H.; Mehraban, H.; Hassanabadi, H.

    2016-08-01

    In this paper, we study the scattering properties of s-wave Schrödinger equation for the multi-parameter potential, which can be reduced into four special cases for different values of potential parameters, i.e., Hulthén, Manning–Rosen, and Eckart potentials. We also obtain and investigate the scattering amplitudes of these special cases. Some numerical results are also obtained and reported.

  5. Observations on open and closed string scattering amplitudes at high energies

    NASA Astrophysics Data System (ADS)

    Caputa, Pawel; Hirano, Shinji

    2012-02-01

    We study massless open and closed string scattering amplitudes in flat space at high energies. Similarly to the case of AdS space, we demonstrate that, under the T-duality map, the open string amplitudes are given by the exponential of minus minimal surface areas whose boundaries are cusped closed loops formed by lightlike momentum vectors. We show further that the closed string amplitudes are obtained by gluing two copies of minimal surfaces along their cusped lightlike boundaries. This can be thought of as a manifestation of the Kawai-Lewellen-Tye (KLT) relation at high energies. We also discuss the KLT relation in AdS/CFT and its possible connection to amplitudes in mathcal{N} = {8} supergravity as well as the correlator/amplitude duality.

  6. Chiral representation of the πN scattering amplitude and the pion-nucleon sigma term

    NASA Astrophysics Data System (ADS)

    Alarcón, J. M.; Camalich, J. Martin; Oller, J. A.

    2012-03-01

    We present a novel analysis of the πN scattering amplitude in Lorentz covariant baryon chiral perturbation theory renormalized in the extended-on-mass-shell scheme. This amplitude, valid up to O(p3) in the chiral expansion, systematically includes the effects of the Δ(1232) in the δ-counting, has the right analytic properties, and is renormalization-scale independent. This approach overcomes the limitations that previous chiral analyses of the πN scattering amplitude had, providing an accurate description of the partial wave phase shifts of the Karlsruhe-Helsinki and George-Washington groups up to energies just below the resonance region. We also study the solution of the Matsinos group which focuses on the parameterization of the data at low energies. Once the values of the low-energy constants are determined by adjusting the center-of-mass energy dependence of the amplitude to the scattering data, we obtain predictions on different observables. In particular, we extract an accurate value for the pion-nucleon sigma term, σπN. This allows us to avoid the usual method of extrapolation to the unphysical region of the amplitude. Our study indicates that the inclusion of modern meson-factory and pionic-atom data favors relatively large values of the sigma term. We report the value σπN=59(7)MeV and comment on implications that this result may have.

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

    SciTech Connect

    Lindesay, James V

    2002-03-12

    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. Double-logarithmic asymptotics of quark scattering amplitudes with flavor exchange

    SciTech Connect

    Kirschner, R.; Lipatov, L.N.

    1982-09-01

    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.

  9. Extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements

    NASA Technical Reports Server (NTRS)

    Franco, V.

    1977-01-01

    A method is presented for extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements within the framework of the Glauber approximation. This method, which involves the solution of a linear integral equation, is applied to pn collisions between 15 and 275 GeV/c. Effects arising from inelastic intermediate states are estimated.

  10. Relativistic electron scattering by magnetosonic waves: Effects of discrete wave emission and high wave amplitudes

    SciTech Connect

    Artemyev, A. V.; Mourenas, D.; Krasnoselskikh, V. V.

    2015-06-15

    In this paper, we study relativistic electron scattering by fast magnetosonic waves. We compare results of test particle simulations and the quasi-linear theory for different spectra of waves to investigate how a fine structure of the wave emission can influence electron resonant scattering. We show that for a realistically wide distribution of wave normal angles θ (i.e., when the dispersion δθ≥0.5{sup °}), relativistic electron scattering is similar for a wide wave spectrum and for a spectrum consisting in well-separated ion cyclotron harmonics. Comparisons of test particle simulations with quasi-linear theory show that for δθ>0.5{sup °}, the quasi-linear approximation describes resonant scattering correctly for a large enough plasma frequency. For a very narrow θ distribution (when δθ∼0.05{sup °}), however, the effect of a fine structure in the wave spectrum becomes important. In this case, quasi-linear theory clearly fails in describing accurately electron scattering by fast magnetosonic waves. We also study the effect of high wave amplitudes on relativistic electron scattering. For typical conditions in the earth's radiation belts, the quasi-linear approximation cannot accurately describe electron scattering for waves with averaged amplitudes >300 pT. We discuss various applications of the obtained results for modeling electron dynamics in the radiation belts and in the Earth's magnetotail.

  11. The string BCJ relations revisited and extended recurrence relations of nonrelativistic string scattering amplitudes

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We review and extend high energy four point string BCJ relations in both the fixed angle and Regge regimes. We then give an explicit proof of four point string BCJ relations for all energy. This calculation provides an alternative proof of the one based on monodromy of integration in string amplitude calculation. In addition, we calculate both s- t and t- u channel nonrelativistic low energy string scattering amplitudes of three tachyons and one higher spin string state at arbitrary mass levels. We discover that the mass and spin dependent nonrelativistic string BCJ relations can be expressed in terms of Gauss hypergeometry functions. As an application, for each fixed mass level N, we derive extended recurrence relations among nonrelativistic low energy string scattering amplitudes of string states with different spins and different channels.

  12. Correlations among angular wave component amplitudes in elastic multiple-scattering random media.

    PubMed

    Hoover, Brian G; Deslauriers, Louis; Grannell, Shawn M; Ahmed, Rizwan E; Dilworth, David S; Athey, Brian D; Leith, Emmett N

    2002-02-01

    The propagation of scalar waves through random media that provide multiple elastic scattering is considered by derivation of an expression for the angular correlation of the scattered wave amplitudes. Coherent wave transmission is shown to occur through a mechanism similar to that responsible for coherent backscattering. While the properties of the scattered wave are generally consistent with radiative-transfer theory for sufficiently small incident and scattering angles, coherent transmission provides corrections to radiative-transfer results at larger angles. The theoretical angular correlation curves are fit, by specifying the probability densities of two random variables that correspond to material parameters, to measured data of laser light scattering from various polymer microsphere suspensions. PMID:11863685

  13. Statistical density model for composite system scattering: Modified ensemble densities and bounded amplitudes

    NASA Astrophysics Data System (ADS)

    Hahn, Y. K.

    2016-09-01

    A statistical density model for composite system scattering is formulated, by incorporating the ensemble density functional approach in describing the correlation dynamics during the collision. The principal difficulty of non-integrable propagating waves is first resolved by treating the open and closed channels separately; only the closed channel part does allow a density description. The unique open/closed channel separation adopted here allows not only the closed channel Hamiltonian MQ to support integrable densities, but also to establish the important bounds on the scattering amplitude. A modified ensemble energy functional for the MQ is constructed, and the statistical densities ρmtQ for the closed channels are generated. The scattering amplitude is then formulated in terms of the ρmtQ and the coefficients of variation that connect the closed channels to the asymptotic source. Evaluation of the amplitude integrals requires the determinantal functions deduced from the ρmtQ, which also leads to a coupled channel approach. The bound property of the amplitude allows variational optimization of the coefficients. Approximate procedures for securing the orthogonality of the MQ and for evaluation of the source term itself are discussed, including a judicious choice of configurations with zero and one inner-shell holes. Validity of the several critical modifications introduced is assessed.

  14. Modulating the amplitude of dark soliton by scattering-length management in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Zhang, W. X.; Wang, D. L.; He, Z. M.; Wang, F. J.; Ding, J. W.

    2008-06-01

    We present a family of soliton solutions of the quasi-one-dimensional Bose-Einstein condensates with time-dependent scattering length, by developing multiple-scale method combined with truncated Painlevé expansion. Then, by numerical calculating the solutions, it is shown that there exhibit two types of dark solitons-black soliton (the zero minimum amplitude at its center) and gray soliton (the minimum density does not drop to zero) in a repulsive condensate. Furthermore, we propose experimental protocols to realize the exchange between black and gray solitons by varying the scattering length via the Feshbach resonance in currently experimental conditions.

  15. Generalized polarizabilities and the spin-averaged amplitude in virtual Compton scattering off the nucleon

    SciTech Connect

    Drechsel, D.; Knoechlein, G.; Metz, A.; Scherer, S.

    1997-01-01

    We discuss the low-energy behavior of the spin-averaged amplitude of virtual Compton scattering off a nucleon. Based on gauge invariance, Lorentz invariance, and the discrete symmetries, it is shown that to first order in the frequency of the final real photon only two generalized polarizabilities appear. Different low-energy expansion schemes are discussed and put into perspective. {copyright} {ital 1997} {ital The American Physical Society}

  16. Time-dependent treatment of scattering - Integral equation approaches using the time-dependent amplitude density

    NASA Technical Reports Server (NTRS)

    Hoffman, David K.; Sharafeddin, Omar; Judson, Richard S.; Kouri, Donald J.

    1990-01-01

    The time-dependent form of the Lippmann-Schwinger integral equation is used as the basis of several new wave packet propagation schemes. These can be formulated in terms of either the time-dependent wave function or a time-dependent amplitude density. The latter is nonzero only in the region of configuratiaon space for which the potential is nonzero, thereby in principle obviating the necessity of large grids or the use of complex absorbing potentials when resonances cause long collision times (leading, consequently, to long propagation times). Transition amplitudes are obtained in terms of Fourier transforms of the amplitude density from the time to the energy domain. The approach is illustrated by an application to a standard potential scattering model problem where, as in previous studies, the action of the kinetic energy operator is evaluated by fast Fourier transform (FFT) techniques.

  17. J. J. Sakurai Prize: Scattering Amplitudes - the Story of Loops and Legs

    NASA Astrophysics Data System (ADS)

    Dixon, Lance

    2014-03-01

    Scattering amplitudes are at the interface between quantum field theory and particle experiment. Precise predictions for reactions at energy frontier machines such as the Large Hadron Collider (LHC) rely on quantum corrections to scattering amplitudes involving multiple quarks and gluons, as well as other particles. For decades, theorists used Feynman diagrams for this job. However, Feynman diagrams are just too slow, even on fast computers, to allow adequate precision for complicated events with many jets of hadrons in the final state. Such events are produced copiously at the LHC, and constitute formidable backgrounds to many searches for new physics. Over the past two decades, alternative methods to Feynman diagrams have come to fruition. The new ``on-shell'' methods are based on the old principle of unitarity. They can be much more efficient because they exploit the underlying simplicity of scattering amplitudes, and recycle lower-loop information. The same methods have also enabled new insight into the structure of gauge theory and gravity at the quantum level, especially in highly supersymmetric theories where they maintain all of the symmetries. I'll give a brief motivation for and introduction to the new methods, which will be followed by descriptions of their phenomenological and formal applications by David Kosower and Zvi Bern.

  18. Integrand reduction for two-loop scattering amplitudes through multivariate polynomial division

    NASA Astrophysics Data System (ADS)

    Mastrolia, Pierpaolo; Mirabella, Edoardo; Ossola, Giovanni; Peraro, Tiziano

    2013-04-01

    We describe the application of a novel approach for the reduction of scattering amplitudes, based on multivariate polynomial division, which we have recently presented. This technique yields the complete integrand decomposition for arbitrary amplitudes, regardless of the number of loops. It allows for the determination of the residue at any multiparticle cut, whose knowledge is a mandatory prerequisite for applying the integrand-reduction procedure. By using the division modulo Gröbner basis, we can derive a simple integrand recurrence relation that generates the multiparticle pole decomposition for integrands of arbitrary multiloop amplitudes. We apply the new reduction algorithm to the two-loop planar and nonplanar diagrams contributing to the five-point scattering amplitudes in N=4 super Yang-Mills and N=8 supergravity in four dimensions, whose numerator functions contain up to rank-two terms in the integration momenta. We determine all polynomial residues parametrizing the cuts of the corresponding topologies and subtopologies. We obtain the integral basis for the decomposition of each diagram from the polynomial form of the residues. Our approach is well suited for a seminumerical implementation, and its general mathematical properties provide an effective algorithm for the generalization of the integrand-reduction method to all orders in perturbation theory.

  19. Pion-nucleus forward scattering amplitudes from total cross section measurements

    NASA Astrophysics Data System (ADS)

    Jeppesen, R. H.; Jakobson, M. J.; Cooper, M. D.; Hagerman, D. C.; Johnson, M. B.; Redwine, R. P.; Burleson, G. R.; Johnson, K. F.; Marrs, R. E.; Meyer, H. O.; Halpern, I.; Knutson, L. D.

    1983-02-01

    Measurements have been made of the attenuation cross sections for both π+ and π- mesons on Al, 40Ca, Cu, Sn, Ho, and Pb nuclei. The measurements were made at several energies between 114 and 215 MeV. A new method of data analysis has been used to extract both the real and the imaginary parts of a Coulomb-distorted forward scattering amplitude fN(0). Insight into the nature of fN(0) is obtained by the comparison of experimental data with theoretical values calculated from a simple absorption model. This comparison demonstrates that much of the observed rotation of the forward amplitude, when plotted on an Argand diagram, can be attributed to the Coulomb phase contained in fN(0). Comparison is also made with results of similar experiments. Although the present results are in general agreement with previously published ones, some differences are noted for the heavier elements. NUCLEAR REACTIONS Measured pion forward scattering amplitudes; Al, 40Ca, Cu, Sn, Ho, and Pb; E=114-215 MeV; strong absorption model.

  20. Yangian symmetry of scattering amplitudes in Script N = 4 super Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Drummond, James; Henn, Johannes; Plefka, Jan

    2009-05-01

    Tree-level scattering amplitudes in Script N = 4 super Yang-Mills theory have recently been shown to transform covariantly with respect to a `dual' superconformal symmetry algebra, thus extending the conventional superconformal symmetry algebra psu(2,2|4) of the theory. In this paper we derive the action of the dual superconformal generators in on-shell superspace and extend the dual generators suitably to leave scattering amplitudes invariant. We then study the algebra of standard and dual symmetry generators and show that the inclusion of the dual superconformal generators lifts the psu(2,2|4) symmetry algebra to a Yangian. The non-local Yangian generators acting on amplitudes turn out to be cyclically invariant due to special properties of psu(2,2|4). The representation of the Yangian generators takes the same form as in the case of local operators, suggesting that the Yangian symmetry is an intrinsic property of planar Script N = 4 super Yang-Mills, at least at tree level.

  1. Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles.

    PubMed

    Ranasinghesagara, Janaka C; Hayakawa, Carole K; Davis, Mitchell A; Dunn, Andrew K; Potma, Eric O; Venugopalan, Vasan

    2014-07-01

    We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell's equations. Our HF-WEFS implementation is 2-4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens. PMID:25121440

  2. Rapid computation of the amplitude and phase of tightly focused optical fields distorted by scattering particles

    PubMed Central

    Ranasinghesagara, Janaka C.; Hayakawa, Carole K.; Davis, Mitchell A.; Dunn, Andrew K.; Potma, Eric O.; Venugopalan, Vasan

    2014-01-01

    We develop an efficient method for accurately calculating the electric field of tightly focused laser beams in the presence of specific configurations of microscopic scatterers. This Huygens–Fresnel wave-based electric field superposition (HF-WEFS) method computes the amplitude and phase of the scattered electric field in excellent agreement with finite difference time-domain (FDTD) solutions of Maxwell’s equations. Our HF-WEFS implementation is 2–4 orders of magnitude faster than the FDTD method and enables systematic investigations of the effects of scatterer size and configuration on the focal field. We demonstrate the power of the new HF-WEFS approach by mapping several metrics of focal field distortion as a function of scatterer position. This analysis shows that the maximum focal field distortion occurs for single scatterers placed below the focal plane with an offset from the optical axis. The HF-WEFS method represents an important first step toward the development of a computational model of laser-scanning microscopy of thick cellular/tissue specimens. PMID:25121440

  3. Role of Möbius constants and scattering functions in Cachazo-He-Yuan scalar amplitudes

    NASA Astrophysics Data System (ADS)

    Lam, C. S.; Yao, York-Peng

    2016-05-01

    The integration over the Möbius variables leading to the Cachazo-He-Yuan double-color n -point massless scalar amplitude are carried out one integral at a time. Möbius invariance dictates the final amplitude to be independent of the three Möbius constants σr,σs,σt, but their choice affects integrations and the intermediate results. The effect of the Möbius constants, which will be held finite but otherwise arbitrary, the two sets of colors, and the scattering functions on each integration is investigated. A general systematic way to carry out the n -3 integrations is explained, each exposing one of the n -3 propagators of a single Feynman diagram. Two detailed examples are shown to illustrate the procedure, one a five-point amplitude, and the other a nine-point amplitude. Our procedure does not generate intermediate spurious poles, in contrast to what is common by choosing Möbius constants at 0, 1, and ∞ .

  4. Broadband flat-amplitude multiwavelength Brillouin-Raman fiber laser with spectral reshaping by Rayleigh scattering.

    PubMed

    Wang, Zinan; Wu, Han; Fan, Mengqiu; Li, Yi; Gong, Yuan; Rao, Yunjiang

    2013-12-01

    In this letter, we propose a novel configuration for generating multiwavelength Brillouin-Raman fiber laser (MBRFL). The spectral reshaping effect introduced by Rayleigh scattering in a 50 km single mode fiber unifies the generated Brillouin comb in terms of both power level and linewidth. As a consequence, we are able to obtain a 40 nm flat-amplitude MBRFL with wide bandwidth from 1557 nm to 1597 nm covering >500 Stokes lines. This is, to the best of our knowledge, the widest flat-amplitude bandwidth of MBRFL with uniform Stokes combs using just a single Raman pump laser. The channel-spacing is 0.08 nm and the measured OSNR is higher than 12.5 dB. We also demonstrate that the output spectrum of the MBRFL is nearly unaffected over 14 dB range of Brillouin pumping power. PMID:24514489

  5. Pion-nucleon scattering in the Skyrme model and the P-wave Born amplitudes

    NASA Astrophysics Data System (ADS)

    Hayashi, A.; Saito, S.; Uehara, M.

    1991-03-01

    We treat fluctuating pion fields around a rotating Skyrmion by means of Dirac's quantization method. The rotational collective motion of the Skyrmion is described by collective coordinates, and conventional gauge-fixing conditions are imposed. Taking into account all the relevant terms at the tree level appearing in the Hamiltonian, we show that pion-nucleon scattering amplitudes exhibit the P-wave Born amplitudes attributed to the Yukawa coupling of order √Nc , which is consistent with the prediction of chiral symmetry such as the Adler-Weisberger relation. This resolves the difficulty that the Skyrme model predicts a wrong Nc dependence for the coupling of order N-3/2c.

  6. Scattering Amplitudes, the AdS/CFT Correspondence, Minimal Surfaces, and Integrability

    DOE PAGESBeta

    Alday, Luis F.

    2010-01-01

    We focus on the computation of scattering amplitudes of planar maximally supersymmetric Yang-Mill in four dimensions at strong coupling by means of the AdS/CFT correspondence and explain how the problem boils down to the computation of minimal surfaces in AdS in the first part of this paper. In the second part of this review we explain how integrability allows to give a solution to the problem in terms of a set of integral equations. The intention of the review is to give a pedagogical, rather than very detailed, exposition.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Decomposition of the scattering amplitude into shadow and surface components with inclusion of spin-orbit coupling

    SciTech Connect

    Melo, German; David, Jorge; Restrepo, Albeiro

    2008-09-15

    We propose a decomposition of the scattering amplitude into shadow and surface components for proton scattering against calcium isotopes as targets at 21 MeV. We account for spin-orbit coupling effects for the optical potential in the nonrelativistic limit. Our calculations show very good agreement with experimental trends.

  11. Improved Persistent Scatterer analysis using Amplitude Dispersion Index optimization of dual polarimetry data

    NASA Astrophysics Data System (ADS)

    Esmaeili, Mostafa; Motagh, Mahdi

    2016-07-01

    Time-series analysis of Synthetic Aperture Radar (SAR) data using the two techniques of Small BAseline Subset (SBAS) and Persistent Scatterer Interferometric SAR (PSInSAR) extends the capability of conventional interferometry technique for deformation monitoring and mitigating many of its limitations. Using dual/quad polarized data provides us with an additional source of information to improve further the capability of InSAR time-series analysis. In this paper we use dual-polarized data and combine the Amplitude Dispersion Index (ADI) optimization of pixels with phase stability criterion for PSInSAR analysis. ADI optimization is performed by using Simulated Annealing algorithm to increase the number of Persistent Scatterer Candidate (PSC). The phase stability of PSCs is then measured using their temporal coherence to select the final sets of pixels for deformation analysis. We evaluate the method for a dataset comprising of 17 dual polarization SAR data (HH/VV) acquired by TerraSAR-X data from July 2013 to January 2014 over a subsidence area in Iran and compare the effectiveness of the method for both agricultural and urban regions. The results reveal that using optimum scattering mechanism decreases the ADI values in urban and non-urban regions. As compared to single-pol data the use of optimized polarization increases initially the number of PSCs by about three times and improves the final PS density by about 50%, in particular in regions with high rate of deformation which suffer from losing phase stability over the time. The classification of PS pixels based on their optimum scattering mechanism revealed that the dominant scattering mechanism of the PS pixels in the urban area is double-bounce while for the non-urban regions (ground surfaces and farmlands) it is mostly single-bounce mechanism.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Single Spin Asymmetries in Inclusive Dis and Multi-Parton Correlations in the Nucleon

    NASA Astrophysics Data System (ADS)

    Metz, Andreas; Pitonyak, Daniel; Schäfer, Andreas; Schlegel, Marc; Vogelsang, Werner; Zhou, Jian

    Transverse single spin asymmetries in inclusive deep-inelastic lepton-nucleon scattering can be generated through multi-photon exchange between the leptonic and the hadronic part of the process. Here we consider two-photon exchange, and mainly focus on the transverse target spin asymmetry. In particular, we investigate the case where two photons couple to different quarks. Such a contribution involves a quark-photon-quark correlator in the nucleon, which has a (model-dependent) relation to the Efremov-Teryaev-Qiu-Sterman quark-gluon-quark correlator TF. Using different parameterizations for TF we compute the transverse target spin asymmetry for both a proton and a neutron target, and compare the results to recent experimental data. Potential implications on our general understanding of single spin asymmetries in hard scattering processes are discussed as well.

  14. Thomson-Scattering Measurements of Ion-Acoustic Wave Amplitudes Driven by the Two-Plasmon-Decay Instability

    NASA Astrophysics Data System (ADS)

    Follett, R. K.; Michel, D. T.; Myatt, J. F.; Hu, S. X.; Yaakobi, B.; Froula, D. H.

    2012-10-01

    Thomson scattering was used to measure enhanced ion-acoustic waves (IAW's) driven by the two-plasmon-decay (TPD) instability. The IAW amplitude scales with the 3/2φ emission (a TPD signature). Up to 20 beams with 860-μm-diam laser spots generated by 2-ns-long pulses of 3φ (0.351-μm) light with overlapped intensities up to 4 x 10^14 W/cm^2 were used to produce ˜300-μm density-scale lengths. The IAW amplitudes were measured using 4φ Thomson scattering near 3φ quarter-critical densities. Time-resolved 3/2φ spectroscopy was used to compare the amplitude of 3/2φ emission to the IAW amplitude. QZAKfootnotetext K. Y. Sanbonmatsu et al., Phys. Rev. Lett. 82, 932 (1999).^,footnotetext K. Y. Sanbonmatsu et al., Phys. Plasmas 7, 2824 (2000). modeling shows a similar onset threshold and wave amplitude as the experiments. The model suggests that the source of the IAW growth is from the beating of electron-plasma waves, which drive density perturbations through the ponderomotive force. This conclusion is supported by the experimental geometry. This process is shown to be a saturation mechanism for TPD from simulations.footnotetext R. Yan et al., Phys. Rev. Lett. 103, 175002 (2009). This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

  15. Strong-field cyclotron scattering. I - Scattering amplitudes and natural line width. [in spectra of accretion-powered X-ray pulsars

    NASA Technical Reports Server (NTRS)

    Graziani, Carlo

    1993-01-01

    The introduction of resonance line width into the QED cyclotron scattering amplitudes is considered. It is shown that the width arises from loop corrections to the electron propagator, which also bring about shifts in the Landau energy levels. A formalism is developed that allows the dressed electron propagator to be derived. It is shown that the states of Herold et al. (1982) and of Sokolov and Ternov (1968), which diagonalize the component of the magnetic moment operator parallel to the external magnetic field, are appropriate for calculation of the scattering amplitudes, whereas the states of Johnson and Lippmann (1949) are not. In addition, it is shown that the Breit-Wigner broadening approximation E tends to E - i(Gamma)/2 is consistent with the perturbation-theoretic order of the calculation, if the former basis states are chosen, but not the latter.

  16. Detecting the Amplitude Mode of Strongly Interacting Lattice Bosons by Bragg Scattering

    SciTech Connect

    Bissbort, Ulf; Hofstetter, Walter; Li Yongqiang

    2011-05-20

    We report the first detection of the Higgs-type amplitude mode using Bragg spectroscopy in a strongly interacting condensate of ultracold atoms in an optical lattice. By the comparison of our experimental data with a spatially resolved, time-dependent bosonic Gutzwiller calculation, we obtain good quantitative agreement. This allows for a clear identification of the amplitude mode, showing that it can be detected with full momentum resolution by going beyond the linear response regime. A systematic shift of the sound and amplitude modes' resonance frequencies due to the finite Bragg beam intensity is observed.

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

    NASA Astrophysics Data System (ADS)

    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

  18. Near-Forward Rescattering Photoelectron Holography in Strong-Field Ionization: Extraction of the Phase of the Scattering Amplitude.

    PubMed

    Zhou, Yueming; Tolstikhin, Oleg I; Morishita, Toru

    2016-04-29

    We revisit the concept of near-forward rescattering strong-field photoelectron holography introduced by Y. Huismans et al. [Science 331, 61 (2011)]. The recently developed adiabatic theory is used to show how the phase of the scattering amplitude for near-forward rescattering of an ionized electron by the parent ion is encoded in and can be read out from the corresponding interference pattern in photoelectron momentum distributions (PEMDs) produced in the ionization of atoms and molecules by intense laser pulses. A procedure to extract the phase is proposed. Its application to PEMDs obtained by solving the time-dependent Schrödinger equation for a model atom yields results in good agreement with scattering calculations. This establishes a novel general approach to extracting structural information from strong-field observables capable of providing time-resolved imaging of ultrafast processes. PMID:27176518

  19. Argand-diagram representation of transition amplitudes for resonant reactive scattering: e+HCl and e+H2

    NASA Astrophysics Data System (ADS)

    Lutrus, C. K.; Suck Salk, S. H.

    1989-01-01

    Resonances for rearrangement collisions (reactive scattering) involving the two dissociative attachment processes, e+HCl-->H+Cl- and e+H2-->H+H-, are examined. It is shown from the Argand-diagram representation of transition amplitudes that strong resonance is present in the former but not in the latter. That is, the strong resonance is evidenced by the clear exhibition of a phase change by π in a counterclockwise direction in the Argand diagram as the collision energy increases. Such a manifest phase change is absent in the dissociative attachment process of e+H2-->H+H-. This is attributed to the presence of equally strong, direct, and resonant scattering processes, and to the strong influence of mutually destructive interference.

  20. Near-Forward Rescattering Photoelectron Holography in Strong-Field Ionization: Extraction of the Phase of the Scattering Amplitude

    NASA Astrophysics Data System (ADS)

    Zhou, Yueming; Tolstikhin, Oleg I.; Morishita, Toru

    2016-04-01

    We revisit the concept of near-forward rescattering strong-field photoelectron holography introduced by Y. Huismans et al. [Science 331, 61 (2011)]. The recently developed adiabatic theory is used to show how the phase of the scattering amplitude for near-forward rescattering of an ionized electron by the parent ion is encoded in and can be read out from the corresponding interference pattern in photoelectron momentum distributions (PEMDs) produced in the ionization of atoms and molecules by intense laser pulses. A procedure to extract the phase is proposed. Its application to PEMDs obtained by solving the time-dependent Schrödinger equation for a model atom yields results in good agreement with scattering calculations. This establishes a novel general approach to extracting structural information from strong-field observables capable of providing time-resolved imaging of ultrafast processes.

  1. Elastic electron-atom scattering in amplitude-phase representation with application to electron diffraction and spectroscopy

    NASA Astrophysics Data System (ADS)

    Rundgren, J.

    2007-11-01

    The amplitude-phase representation (APR) [W. E. Milne, Phys. Rev. 35, 863 (1930)] is applied to the relativistic radial Schrödinger equation corresponding to the Dirac equations with central potential. The initial conditions, hitherto unspecified, for the nonlinear second-order amplitude equation at the finite radius of a muffin-tin (MT) sphere are established by a semiconvergent method. This opens the possibility of using APR for the calculation of electron scattering phase shifts with a finite MT radius as well as with a large atomic radius, whereby the first wave node is phase of reference equal to a multiple of π , adding nothing to the phase shifts. Furthermore, APR is used for benchmarking wave functions obtained by ordinary differential equation integration of the Dirac equations up to high energy and high orbital quantum number. The present APR procedure is discussed with reference to earlier numerical methods. To complete the physical picture, the paper ends with a discussion on exchange-correlation dependent scattering potential in MT spheres of optimized radii, a crystal potential model whose dependence on radii and energy dependent inner potential has recently been corroborated by low energy electron diffraction in oxides with many atoms per unit cell.

  2. Elastic electron-atom scattering in amplitude-phase representation with application to electron diffraction and spectroscopy

    SciTech Connect

    Rundgren, J.

    2007-11-15

    The amplitude-phase representation (APR) [W. E. Milne, Phys. Rev. 35, 863 (1930)] is applied to the relativistic radial Schroedinger equation corresponding to the Dirac equations with central potential. The initial conditions, hitherto unspecified, for the nonlinear second-order amplitude equation at the finite radius of a muffin-tin (MT) sphere are established by a semiconvergent method. This opens the possibility of using APR for the calculation of electron scattering phase shifts with a finite MT radius as well as with a large atomic radius, whereby the first wave node is phase of reference equal to a multiple of {pi}, adding nothing to the phase shifts. Furthermore, APR is used for benchmarking wave functions obtained by ordinary differential equation integration of the Dirac equations up to high energy and high orbital quantum number. The present APR procedure is discussed with reference to earlier numerical methods. To complete the physical picture, the paper ends with a discussion on exchange-correlation dependent scattering potential in MT spheres of optimized radii, a crystal potential model whose dependence on radii and energy dependent inner potential has recently been corroborated by low energy electron diffraction in oxides with many atoms per unit cell.

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

    NASA Astrophysics Data System (ADS)

    Mayoral-Astorga, L. A.; Gaspar-Armenta, J. A.; Ramos-Mendieta, F.

    2016-04-01

    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.

  4. Application of amplitude changes of monochromatic scattered light to investigation of dust grain composition

    NASA Astrophysics Data System (ADS)

    Kirkiewicz, Jozef; Chrzanowski, Janusz

    1999-07-01

    The light beam crossing the dust area meets with the loss of energy. We know by experience that the scattering indikatrix depends on the size of the dust particles. The measurement of the light energy scattered into given solid angle enables to identify and specification of the grain composition of the dust particles. Basis on the research a special head has been made to step change of the location of the photodetectors and in result to measure a specific or even desirable dust fraction for the sake of technology. In this paper the graphs of the grain dust distribution are presented with regard to the materials which are transported most frequently by Polish merchant marine.

  5. Integrand reduction of one-loop scattering amplitudes through Laurent series expansion

    NASA Astrophysics Data System (ADS)

    Mastrolia, Pierpaolo; Mirabella, Edoardo; Peraro, Tiziano

    2012-06-01

    We present a semi-analytic method for the integrand reduction of one-loop amplitudes, based on the systematic application of the Laurent expansions to the integrand-decomposition. In the asymptotic limit, the coefficients of the master integrals are the solutions of a diagonal system of equations, properly corrected by counterterms whose parametric form is known a priori. The Laurent expansion of the integrand is implemented through polynomial division. The extension of the integrand-reduction to the case of numerators with rank larger than the number of propagators is discussed as well.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Investigating Persistent and Distributed Scatterers to Better Resolve Low Amplitude Deformation with InSAR in Vegetated Terrains

    NASA Astrophysics Data System (ADS)

    Tong, X.; Schmidt, D. A.

    2014-12-01

    Multi-temporal InSAR methods are successful at revealing low amplitude surface deformation by reducing the noise from the atmosphere and the Digital Elevation Model (DEM). The Persistent Scatters (PS) InSAR and Small baseline (SBAS) methods are used widely by the InSAR community. However, it is still challenging to recover low deformation rates in highly vegetated mountainous areas. Our goal is to explore different approaches to identifying PS or stable Distributed Scatterers (DS) for multi-temporal InSAR processing. We are investigating the following methods: 1) amplitude dispersion (Ferretti et al., 2001); 2) average correlation; 3) spatial correlation of phase (Hooper et al., 2004); 4) comparison of phase against a known mathematical model (Shanker and Zebker, 2007); 5) statistical analysis of the coherence matrix (Ferretti et al., 2011); 6) polarimetric bounce characteristics. We first align the SAR images to form a stack of Single Look Complex (SLC) using "batch processing". We work with this 3-dimensional SLC stack to identify high-quality PS and DS using the aforementioned methods. Next we design a filter based on the characteristics of the scatterers to form interferograms. This comparative study on identifying and filtering PS and DS can be integrated with interferogram stacking or time-series approaches like PSInSAR, SBAS or wavelet-based methods. We are working with the ERS-1, ERS-2 and ALOS-1 SAR data to study landslides and volcano deformation over various terrains in the Cascade Range. From these observations we will be able to construct better physical models to explain various deformation processes.

  8. Pion-kaon scattering amplitude constrained with forward dispersion relations up to 1.6 GeV

    NASA Astrophysics Data System (ADS)

    Pelaez, J. R.; Rodas, A.

    2016-04-01

    In this work we provide simple and precise parametrizations of the existing π K scattering data from threshold up to 1.6 GeV, which are constrained to satisfy forward dispersion relations as well as three additional threshold sum rules. We also provide phenomenological values of the threshold parameters and of the resonance poles that appear in elastic scattering.

  9. Broad-band linear polarization in cool stars. II - Amplitude and wavelength dependence for magnetic and scattering regions

    NASA Technical Reports Server (NTRS)

    Saar, Steven H.; Huovelin, Juhani

    1993-01-01

    We have developed a model to estimate the amplitude and wavelength dependence of broad-band linear polarization (BLP) from magnetic regions on cool stars. The model includes corrections both for line blends and for the partial cancellation of polarization in the vector sum over the stellar disk. Our results agree with recent calculations of BLP in the red, but show larger amplitudes and a different wavelength dependence in the blue. We find that the detailed wavelength dependence of the polarization is complex and varies with effective temperature and gravity due to changes in line blanketing. The BLP amplitudes depend strongly on field strength, blanketing, and magnetic region filling factor and geometry. We make rough estimates of the maximum BLP for stars of various spectral types and demonstrate a method for deriving a lower limit to the filling factor from the maximum observed BLP. This lower limit is related to the fractional area covered by the spatially asymmetric component of magnetic regions.

  10. Measurement of the transverse beam spin asymmetry in elastic electron-proton scattering and the inelastic contribution to the imaginary part of the two-photon exchange amplitude.

    PubMed

    Maas, F E; Aulenbacher, K; Baunack, S; Capozza, L; Diefenbach, J; Gläser, B; Imai, Y; Hammel, T; von Harrach, D; Kabuss, E-M; Kothe, R; Lee, J H; Sanchez-Lorente, A; Schilling, E; Schwaab, D; Stephan, G; Weber, G; Weinrich, C; Altarev, I; Arvieux, J; Elyakoubi, M; Frascaria, R; Kunne, R; Morlet, M; Ong, S; Vandewiele, J; Kowalski, S; Suleiman, R; Taylor, S

    2005-03-01

    We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A( perpendicular), at two Q2 values of 0.106 and 0.230 (GeV/c)(2) and a scattering angle of 30 degrees amplitude. There is no obvious reason why this should be different for the real part of the two-photon amplitude, which enters into the radiative corrections for the Rosenbluth separation measurements of the electric form factor of the proton. PMID:15783877

  11. Remarks on the mixed Ramond-Ramond, open string scattering amplitudes of BPS, non-BPS and brane-anti-brane

    NASA Astrophysics Data System (ADS)

    Hatefi, Ehsan

    2015-11-01

    From the world-sheet point of view we compute three, four and five point BPS and non-BPS scattering amplitudes of type IIA and IIB superstring theory. All these mixed S-matrix elements including a Ramond-Ramond closed string (RR) in the bulk and a scalar/gauge or tachyons with all different pictures (including an RR in asymmetric and symmetric pictures) have been carried out. We have also shown that in asymmetric pictures various equations must be kept fixed. More importantly, by direct calculations on the upper half plane, it is realised that some of the equations (which must be true) for BPS branes cannot be necessarily applied to non-BPS amplitudes. We also derive the S-matrix elements of < V_C^{-2} V_{φ }0V _A0 V_T0 rangle and clarify the fact that in the presence of the scalar field and an RR, the terms carrying momentum of an RR in the transverse directions play an important role in the entire form of the S-matrix and their presence is needed in order to have gauge invariance for the entire S-matrix elements of type IIA (IIB) superstring theory.

  12. Mathematical Aspects of Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Duhr, Claude

    In these lectures we discuss some of the mathematical structures that appear when computing multi-loop Feynman integrals. We focus on a specific class of special functions, the so-called multiple polylogarithms, and introduce their Hopf algebra structure. We show how these mathematical concepts are useful in physics by illustrating on several examples how these algebraic structures are useful to perform analytic computations of loop integrals, in particular to derive functional equations among polylogarithms.

  13. Off-shell extrapolation of Regge-model NN scattering amplitudes describing final state interactions in 2H(e,e'p)

    DOE PAGESBeta

    Ford, William Paul; van Orden, Wally

    2013-11-25

    In this work, an off-shell extrapolation is proposed for the Regge-model NN amplitudes presented in a paper by Ford and Van Orden [ Phys. Rev. C 87 014004 (2013)] and in an eprint by Ford (arXiv:1310.0871 [nucl-th]). The prescriptions for extrapolating these amplitudes for one nucleon off-shell in the initial state are presented. Application of these amplitudes to calculations of deuteron electrodisintegration are presented and compared to the limited available precision data in the kinematical region covered by the Regge model.

  14. Off-shell extrapolation of Regge-model NN scattering amplitudes describing final state interactions in 2H(e,e'p)

    SciTech Connect

    Ford, William Paul; van Orden, Wally

    2013-11-25

    In this work, an off-shell extrapolation is proposed for the Regge-model NN amplitudes presented in a paper by Ford and Van Orden [ Phys. Rev. C 87 014004 (2013)] and in an eprint by Ford (arXiv:1310.0871 [nucl-th]). The prescriptions for extrapolating these amplitudes for one nucleon off-shell in the initial state are presented. Application of these amplitudes to calculations of deuteron electrodisintegration are presented and compared to the limited available precision data in the kinematical region covered by the Regge model.

  15. {sup 12}C-{sup 12}C elastic scattering at 1.016, 1.449, and 2.4 GeV and the NN amplitude

    SciTech Connect

    Chauhan, Deeksha; Khan, Z. A.

    2007-05-15

    Working within the framework of the Coulomb modified Glauber model, we analyze the elastic angular distribution and reaction cross section for the {sup 12}C-{sup 12}C system at 1.016, 1.449, and 2.4 GeV. The elastic S matrix is evaluated using the effective profile function approach, and a correlation expansion for the Glauber amplitude is obtained. We emphasize the parametrization of the basic (input) NN amplitude, which may be used for a wide range of angles. Retaining the first two terms of the correlation expansion and using the realistic densities for the colliding nuclei, we find that (i) the consideration of higher momentum transfer components, and hence the nondiffractive behavior, of the NN amplitude provides a more satisfactory account of the data than does the conventional (one-term) Gaussian parametrization for the NN amplitude, (ii) the in-medium effects seem to reduce the (free) NN total cross section and influence the other parameters of the NN amplitude as well, (iii) the phase of the NN amplitude does not help in improving the theoretical situation, and (iv) the c.m. correlations play an important role at the energies considered. We also discuss the suitability of the effective profile function approach in the present context.

  16. Off-shell CHY amplitudes

    NASA Astrophysics Data System (ADS)

    Lam, C. S.; Yao, York-Peng

    2016-06-01

    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.

  17. CHY formula and MHV amplitudes

    NASA Astrophysics Data System (ADS)

    Du, Yi-Jian; Teng, Fei; Wu, Yong-Shi

    2016-05-01

    In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl supports the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula produces the Parke-Taylor formula for MHV Yang-Mills amplitudes as well as the Hodges formula for MHV gravitational amplitudes, with an arbitrary number of external gluons/gravitons. This is achieved by developing techniques, in a manifestly Möbius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other ( n - 3)! - 1 solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes. Our results reveal a mysterious feature of the CHY formalism that in Yang-Mills and gravity theory, solutions of scattering equations, involving only external momenta, somehow know about the configuration of external polarizations of the scattering amplitudes.

  18. Toward complete pion nucleon amplitudes

    NASA Astrophysics Data System (ADS)

    Mathieu, V.; Danilkin, I. V.; Fernández-Ramírez, C.; Pennington, M. R.; Schott, D.; Szczepaniak, Adam P.; Fox, G.

    2015-10-01

    We compare the low-energy partial-wave analyses of π N scattering with high-energy data via finite-energy sum rules. We construct a new set of amplitudes by matching the imaginary part from the low-energy analysis with the high-energy, Regge parametrization and reconstruct the real parts using dispersion relations.

  19. Toward complete pion nucleon amplitudes

    DOE PAGESBeta

    Mathieu, Vincent; Danilkin, Igor V.; Fernández-Ramírez, Cesar; Pennington, Michael R.; Schott, Diane M.; Szczepaniak, Adam P.; Fox, G.

    2015-10-05

    We compare the low-energy partial wave analyses πN scattering with a high-energy data via finite energy sum rules. We also construct a new set of amplitudes by matching the imaginary part from the low-energy analysis with the high-energy, Regge parametrization and then reconstruct the real parts using dispersion relations.

  20. Positive amplitudes in the amplituhedron

    NASA Astrophysics Data System (ADS)

    Arkani-Hamed, Nima; Hodges, Andrew; Trnka, Jaroslav

    2015-08-01

    The all-loop integrand for scattering amplitudes in planar SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting inside a co-dimension one surface separating "legal" and "illegal" local singularities of the amplitude. We illustrate this in several simple examples, obtaining new expressions for amplitudes not associated with any triangulations, but following in a more invariant manner from a global view of the positive geometry.

  1. On-Shell Methods in Perturbative QCD

    SciTech Connect

    Bern, Zvi; Dixon, Lance J.; Kosower, David A.

    2007-04-25

    We review on-shell methods for computing multi-parton scattering amplitudes in perturbative QCD, utilizing their unitarity and factorization properties. We focus on aspects which are useful for the construction of one-loop amplitudes needed for phenomenological studies at the Large Hadron Collider.

  2. Connecting physical resonant amplitudes and lattice QCD

    NASA Astrophysics Data System (ADS)

    Bolton, Daniel R.; Briceño, Raúl A.; Wilson, David J.

    2016-06-01

    We present a determination of the isovector, P-wave ππ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using mπ = 236 MeV. The finite volume spectra are described using extensions of Lüscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at mπ = 140 MeV. The scattering phase shift is found to agree with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a ρ-resonance pole at Eρ = [ 755 (2) (1) (20 -i/2 129 (3) (1) 7 1) ] MeV. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.

  3. Connecting physical resonant amplitudes and lattice QCD

    NASA Astrophysics Data System (ADS)

    Bolton, Daniel R.; Briceño, Raúl A.; Wilson, David J.

    2016-06-01

    We present a determination of the isovector, P-wave ππ scattering phase shift obtained by extrapolating recent lattice QCD results from the Hadron Spectrum Collaboration using mπ = 236 MeV. The finite volume spectra are described using extensions of Lüscher's method to determine the infinite volume Unitarized Chiral Perturbation Theory scattering amplitude. We exploit the pion mass dependence of this effective theory to obtain the scattering amplitude at mπ = 140 MeV. The scattering phase shift is found to agree with experiment up to center of mass energies of 1.2 GeV. The analytic continuation of the scattering amplitude to the complex plane yields a ρ-resonance pole at Eρ = [ 755 (2) (1) (20 02) -i/2 129 (3) (1) (7 1) ] MeV. The techniques presented illustrate a possible pathway towards connecting lattice QCD observables of few-body, strongly interacting systems to experimentally accessible quantities.

  4. OPE for all helicity amplitudes

    NASA Astrophysics Data System (ADS)

    Basso, Benjamin; Caetano, João; Córdova, Lucía; Sever, Amit; Vieira, Pedro

    2015-08-01

    We extend the Operator Product Expansion (OPE) for scattering amplitudes in planar SYM to account for all possible helicities of the external states. This is done by constructing a simple map between helicity configurations and so-called charged pentagon transitions. These OPE building blocks are generalizations of the bosonic pentagons entering MHV amplitudes and they can be bootstrapped at finite coupling from the integrable dynamics of the color flux tube. A byproduct of our map is a simple realization of parity in the super Wilson loop picture.

  5. Constraining higher derivative supergravity with scattering amplitudes

    SciTech Connect

    Wang, Yifan; Yin, Xi

    2015-08-31

    We study supersymmetry constraints on higher derivative deformations of type IIB supergravity by consideration of superamplitudes. Thus, combining constraints of on-shell supervertices and basic results from string perturbation theory, we give a simple argument for the non-renormalization theorem of Green and Sethi, and some of its generalizations.

  6. DVCS amplitude with kinematical twist-3 terms

    SciTech Connect

    Radyushkin, A.V.; Weiss, C.

    2000-08-01

    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.

  7. Scattering theory for arbitrary potentials

    SciTech Connect

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

    2005-09-15

    The fundamental quantities of potential scattering theory are generalized to accommodate long-range interactions. Definitions for the scattering amplitude and wave operators valid for arbitrary interactions including potentials with a Coulomb tail are presented. It is shown that for the Coulomb potential the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure.

  8. Phase variation of hadronic amplitudes

    SciTech Connect

    Dedonder, J.-P.; Gibbs, W. R.; Nuseirat, Mutazz

    2008-04-15

    The phase variation with angle of hadronic amplitudes is studied with a view to understanding the underlying physical quantities that control it and how well it can be determined in free space. We find that unitarity forces a moderately accurate determination of the phase in standard amplitude analyses but that the nucleon-nucleon analyses done to date do not give the phase variation needed to achieve a good representation of the data in multiple scattering calculations. Models are examined that suggest its behavior near forward angles is related to the radii of the real and absorptive parts of the interaction. The dependence of this phase on model parameters is such that if these radii are modified in the nuclear medium (in combination with the change due to the shift in energy of the effective amplitude in the medium) then the larger magnitudes of the phase needed to fit the data might be attainable but only for negative values of the phase variation parameter.

  9. Relations between closed string amplitudes at higher-order tree level and open string amplitudes

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Xin; Du, Yi-Jian; Ma, Qian

    2010-01-01

    KLT relations almost factorize closed string amplitudes on S by two open string tree amplitudes which correspond to the left- and the right-moving sectors. In this paper, we investigate string amplitudes on D and RP. We find that KLT factorization relations do not hold in these two cases. The relations between closed and open string amplitudes have new forms. On D and RP, the left- and the right-moving sectors are connected into a single sector. Then an amplitude with closed strings on D or RP can be given by one open string tree amplitude except for a phase factor. The relations depends on the topologies of the world-sheets. Under T-duality, the relations on D and RP give the amplitudes between closed strings scattering from D-brane and O-plane respectively by open string partial amplitudes. In the low energy limits of these two cases, the factorization relations for graviton amplitudes do not hold. The amplitudes for gravitons must be given by the new relations instead.

  10. PULSE AMPLITUDE ANALYZER

    DOEpatents

    Greenblatt, M.H.

    1958-03-25

    This patent pertains to pulse amplitude analyzers for sorting and counting a serles of pulses, and specifically discloses an analyzer which ls simple in construction and presents the puise height distribution visually on an oscilloscope screen. According to the invention, the pulses are applied to the vertical deflection plates of an oscilloscope and trigger the horizontal sweep. Each pulse starts at the same point on the screen and has a maximum amplitude substantially along the same vertical line. A mask is placed over the screen except for a slot running along the line where the maximum amplitudes of the pulses appear. After the slot has been scanned by a photocell in combination with a slotted rotating disk, the photocell signal is displayed on an auxiliary oscilloscope as vertical deflection along a horizontal time base to portray the pulse amplitude distribution.

  11. PULSE AMPLITUDE ANALYSERS

    DOEpatents

    Lewis, I.A.D.

    1956-05-15

    This patent pentains to an electrical pulse amplitude analyzer, capable of accepting input pulses having a separation between adjacent pulses in the order of one microsecond while providing a large number of channels of classification. In its broad aspect the described pulse amplitude analyzer utilizes a storage cathode ray tube und control circuitry whereby the amplitude of the analyzed pulses controls both the intensity and vertical defiection of the beam to charge particular spots in horizontal sectors of the tube face as the beam is moved horizontally across the tube face. As soon as the beam has swept the length of the tube the information stored therein is read out by scanning individually each horizontal sector corresponding to a certain range of pulse amplitudes and applying the output signal from each scan to separate indicating means.

  12. Large-N QCD and the Veneziano amplitude

    NASA Astrophysics Data System (ADS)

    Armoni, Adi

    2016-05-01

    We consider four scalar mesons scattering in large-Nc QCD. Using the worldline formalism we show that the scattering amplitude can be written as a formal sum over Wilson loops. The AdS/CFT correspondence maps this sum into a sum over string worldsheets in a confining background. We then argue that for well separated mesons the sum is dominated by flat space configurations. Under additional assumptions about the dual string path integral we obtain the Veneziano amplitude.

  13. Amplitudes in N = 4 Super-Yang-Mills Theory

    NASA Astrophysics Data System (ADS)

    Spradlin, Marcus

    These lecture notes provide a lightning introduction to some aspects of scattering amplitudes in maximally supersymmetric theory, aimed at the audience of students attending the 2014 TASI summer school "Journeys Through the Precision Frontier: Amplitudes for Colliders". Emphasis is placed on explaining modern terminology so that students needing to delve further may more easily access the available literature.

  14. Amplitudes and Ultraviolet Behavior of N = 8 Supergravity

    SciTech Connect

    Bern, Zvi; Carrasco, John Joseph; Dixon, Lance J.; Johansson, Henrik; Roiban, Radu; /Penn State U.

    2011-05-20

    In this contribution we describe computational tools that permit the evaluation of multi-loop scattering amplitudes in N = 8 supergravity, in terms of amplitudes in N = 4 super-Yang-Mills theory. We also discuss the remarkable ultraviolet behavior of N = 8 supergravity, which follows from these amplitudes, and is as good as that of N = 4 super-Yang-Mills theory through at least four loops.

  15. Reinforcing Saccadic Amplitude Variability

    ERIC Educational Resources Information Center

    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…

  16. Subleading soft factor for string disk amplitudes

    NASA Astrophysics Data System (ADS)

    Schwab, Burkhard U. W.

    2014-08-01

    We investigate the behavior of superstring disk scattering amplitudes in the presence of a soft external momentum at finite string tension. We prove that there are no α'-corrections to the field theory form of the subleading soft factor S (1). At the end of this work, we also comment on the possibility to find the corresponding subleading soft factors in closed string theory using our result and the KLT relations.

  17. Amplitude Modulator Chassis

    SciTech Connect

    Erbert, G

    2009-09-01

    The Amplitude Modulator Chassis (AMC) is the final component in the MOR system and connects directly to the PAM input through a 100-meter fiber. The 48 AMCs temporally shape the 48 outputs of the MOR using an arbitrary waveform generator coupled to an amplitude modulator. The amplitude modulation element is a two stage, Lithium Niobate waveguide device, where the intensity of the light passing through the device is a function of the electrical drive applied. The first stage of the modulator is connected to a programmable high performance Arbitrary Waveform Generator (AWG) consisting of 140 impulse generators space 250 ps apart. An arbitrary waveform is generated by independently varying the amplitude of each impulse generator and then summing the impulses together. In addition to the AWG a short pulse generator is also connected to the first stage of the modulator to provide a sub 100-ps pulse used for timing experiments. The second stage of the modulator is connect to a square pulse generator used to further attenuate any pre or post pulse light passing through the first stage of the modulator. The fast rise and fall time of the square pulse generator is also used to produce fast rise and fall times of the AWG by clipping the AWG pulse. For maximum extinction, a pulse bias voltage is applied to each stage of the modulator. A pulse voltage is applied as opposed to a DC voltage to prevent charge buildup on the modulator. Each bias voltage is adjustable to provide a minimum of 50-dB extinction. The AMC is controlled through ICCS to generate the desired temporal pulse shape. This process involves a closed-loop control algorithm, which compares the desired temporal waveform to the produced optical pulse, and iterates the programming of the AWG until the two waveforms agree within an allowable tolerance.

  18. China Amplitude Tomography

    NASA Astrophysics Data System (ADS)

    Hearn, T. M.

    2014-12-01

    Modern data from the China Bulletin and temporary network deployments has been used to update amplitude tomography using ML and MS seismic amplitudes. This work builds on the results of Hearn et al., 2008. ML attenuation estimates are much better resolved due to the inclusion of subnet data. We find that the trade-off between geometrical spreading and attenuation estimates are well constrained; however, both of these parameters have significant trade-off with the frequency dependence of attenuation. Maps of attenuation using the ML amplitudes are similar to those of Lg attenuation found by other authors suggesting that ML attenuation estimates form a suitable proxy for Lg attenuation estimates. We are now able to associate high attenuation directly with the Longmen Shan and the Qilian Shan mountains and also, where resolved, with the Kunlun Shan, Altyn Tag, and Tian Shan mountains. Grabens around the Ordos Platform also show high attenuation. Basins, however, do not in general show high attenuation. The main exception to this is the Bohai Basin. We conclude that the ML waveforms, like the Lg waveforms, interrogate the entire crustal column and are most sensitive to tectonically active structures and rapid changes in crustal structure. Data from MS data do not include subnet readings and do not have the resolution that was obtained with the ML data. Nonetheless, features are similar with the exception that basins appear more highly attenuative.

  19. PULSE AMPLITUDE ANALYZER

    DOEpatents

    Gray, G.W.; Jensen, A.S.

    1957-10-22

    A pulse-height analyzer system of improved design for sorting and counting a series of pulses, such as provided by a scintillation detector in nuclear radiation measurements, is described. The analyzer comprises a main transmission line, a cathode-ray tube for each section of the line with its deflection plates acting as the line capacitance; means to bias the respective cathode ray tubes so that the beam strikes a target only when a prearranged pulse amplitude is applied, with each tube progressively biased to respond to smaller amplitudes; pulse generating and counting means associated with each tube to respond when the beam is deflected; a control transmission line having the same time constant as the first line per section with pulse generating means for each tube for initiating a pulse on the second transmission line when a pulse triggers the tube of corresponding amplitude response, the former pulse acting to prevent successive tubes from responding to the pulse under test. This arrangement permits greater deflection sensitivity in the cathode ray tube and overcomes many of the disadvantages of prior art pulse-height analyzer circuits.

  20. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

    1989-01-01

    The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  1. Remarks on the identities of gluon tree amplitudes

    NASA Astrophysics Data System (ADS)

    Tye, S.-H. Henry; Zhang, Yang

    2010-10-01

    Recently, Bjerrum-Bohr, Damgaard, Feng, and Sondergaard derived a set of new interesting quadratic identities of the Yang-Mills (YM) tree scattering amplitudes, besides Bern-Carrasco-Johansson (BCJ) identities. Here we comment that these quadratic identities of YM amplitudes actually follow directly from the KLT (Kawai-Lewellen-Tye) relation for graviton-dilaton-axion scattering amplitudes (in four-dimensional spacetime). This clarifies their physical origin and also provides a simpler version of the new identities. We also comment that the recently discovered BCJ identities of YM helicity amplitudes, at least for the maximal helicity-violating case, can be verified by using (repeatedly) the Schouten identity. We also point out additional quadratic identities that can be written down from the KLT relations.

  2. Particle Distribution Modification by Low Amplitude Modes

    SciTech Connect

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

    2009-08-28

    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.

  3. Delbrück amplitudes: new calculations

    NASA Astrophysics Data System (ADS)

    Kahane, Sylvian

    1992-06-01

    Calculations of the first-order Delbrück scattering amplitudes were parallelized in a medium-grain mode assuring a very efficient, equal-load implementation, on systems with a moderate number of processors. New numerical values were calculated in the energy range 7.92-28 MeV and in the angular range 0.001°-120° with an estimated accuracy of as good as 1%. The old tables of Bar-Noy and Kahane are improved by these new calculations especially the values of Re A+- amplitudes. Good agreement is found with the calculations of Turrini, Maino and Ventura with a smoother behaviour of the present values. The calculations were performed on a system of eight transputers.

  4. An algebraic approach to the scattering equations

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  5. PULSE AMPLITUDE DISTRIBUTION RECORDER

    DOEpatents

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  6. Tree-level amplitudes in the nonlinear sigma model

    NASA Astrophysics Data System (ADS)

    Kampf, Karol; Novotný, Jirí; Trnka, Jaroslav

    2013-05-01

    We study in detail the general structure and further properties of the tree-level amplitudes in the SU( N) nonlinear sigma model. We construct the flavor-ordered Feynman rules for various parameterizations of the SU( N) fields U ( x), write down the Berends-Giele relations for the semi-on-shell currents and discuss their efficiency for the amplitude calculation in comparison with those of renormalizable theories. We also present an explicit form of the partial amplitudes up to ten external particles. It is well known that the standard BCFW recursive relations cannot be used for reconstruction of the the on-shell amplitudes of effective theories like the SU( N) nonlinear sigma model because of the inappropriate behavior of the deformed on-shell amplitudes at infinity. We discuss possible generalization of the BCFW approach introducing "BCFW formula with subtractions" and with help of Berends-Giele relations we prove particular scaling properties of the semi-on-shell amplitudes of the SU( N) nonlinear sigma model under specific shifts of the external momenta. These results allow us to define alternative deformation of the semi-on-shell amplitudes and derive BCFW-like recursion relations. These provide a systematic and effective tool for calculation of Goldstone bosons scattering amplitudes and it also shows the possible applicability of on-shell methods to effective field theories. We also use these BCFW-like relations for the investigation of the Adler zeroes and double soft limit of the semi-on-shell amplitudes.

  7. On the Period-Amplitude and Amplitude-Period Relationships

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    Examined are Period-Amplitude and Amplitude-Period relationships based on the cyclic behavior of the 12-month moving averages of monthly mean sunspot numbers for cycles 0.23, both in terms of Fisher's exact tests for 2x2 contingency tables and linear regression analyses. Concerning the Period-Amplitude relationship (same cycle), because cycle 23's maximum amplitude is known to be 120.8, the inferred regressions (90-percent prediction intervals) suggest that its period will be 131 +/- 24 months (using all cycles) or 131 +/- 18 months (ignoring cycles 2 and 4, which have the extremes of period, 108 and 164 months, respectively). Because cycle 23 has already persisted for 142 months (May 1996 through February 2008), based on the latter prediction, it should end before September 2008. Concerning the Amplitude-Period relationship (following cycle maximum amplitude versus preceding cycle period), because cycle 23's period is known to be at least 142 months, the inferred regressions (90-percent prediction intervals) suggest that cycle 24's maximum amplitude will be about less than or equal to 96.1 +/- 55.0 (using all cycle pairs) or less than or equal to 91.0 +/- 36.7 (ignoring statistical outlier cycle pairs). Hence, cycle 24's maximum amplitude is expected to be less than 151, perhaps even less than 128, unless cycle pair 23/24 proves to be a statistical outlier.

  8. Weak Deeply Virtual Compton Scattering

    SciTech Connect

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2007-03-01

    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.

  9. Λ scattering equations

    NASA Astrophysics Data System (ADS)

    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.

  10. Planar-transverse amplitude-phase pattern in nonelastic reactions

    NASA Astrophysics Data System (ADS)

    Arash, Firooz; Moravcsik, Michael J.; Goldstein, Gary R.; Bugg, David V.

    1989-01-01

    The first evidence is presented that the phase pattern of the planar-transverse optimal reaction amplitudes found previously for elastic-scattering strong-interaction reactions also holds for nonelastic reactions. The pattern is observed in the reaction p+p-->d+π in the energy range between 300 and 800 MeV.

  11. Eikonal Scattering at Strong Coupling

    NASA Astrophysics Data System (ADS)

    Irizarry-Gelpi, Melvin Eloy

    The scattering of subatomic particles is a source of important physical phenomena. Decades of work have yielded many techniques for the computation of scattering amplitudes. Most of these techniques involve perturbative quantum field theory and thus apply only at weak coupling. Complementary to scattering is the formation of bound states, which are intrinsically nonperturbative. Regge theory arose in the late 1950s as an attempt to describe, with a single framework, both scattering and the formation of bound states. In Regge theory one obtains an amplitude with bound state poles after analytic continuation of a nonperturbative scattering amplitude, corresponding to a sum of an infinite number of Feynman diagrams at large energy and fixed momentum transfer (but with crossed kinematics). Thus, in order to obtain bound states at fixed energy, one computes an amplitude at large momentum transfer. In this dissertation we calculate amplitudes with bound states in the regime of fixed energy and small momentum transfer. We formulate the elastic scattering problem in terms of many-body path integrals, familiar from quantum mechanics. Then we invoke the semiclassical JWKB approximation, where the path integral is dominated by classical paths. The dynamics in the semiclassical regime are strongly coupled, as found by Halpern and Siegel. When the momentum transfer is small, the classical paths are simple straight lines and the resulting semiclassical amplitudes display a spectrum of bound states that agrees with the spectrum found by solving wave equations with potentials. In this work we study the bound states of matter particles with various types of interactions, including electromagnetic and gravitational interactions. Our work has many analogies with the work started by Alday and Maldacena, who computed scattering amplitudes of gluons at strong coupling with semiclassical quantum mechanics of strings in anti de-Sitter spacetime. We hope that in the future we can apply our

  12. Substorm statistics: Occurrences and amplitudes

    SciTech Connect

    Borovsky, J.E.; Nemzek, R.J.

    1994-05-01

    The occurrences and amplitudes of substorms are statistically investigated with the use of three data sets: the AL index, the Los Alamos 3-satellite geosynchronous energetic-electron measurements, and the GOES-5 and -6 geosynchronous magnetic-field measurements. The investigation utilizes {approximately} 13,800 substorms in AL, {approximately} 1400 substorms in the energetic-electron flux, and {approximately} 100 substorms in the magnetic field. The rate of occurrence of substorms is determined as a function of the time of day, the time of year, the amount of magnetotail bending, the orientation of the geomagnetic dipole, the toward/away configuration of the IMF, and the parameters of the solar wind. The relative roles of dayside reconnection and viscous coupling in the production of substorms are assessed. Three amplitudes are defined for a substorms: the jump in the AL index, the peak of the >30-keV integral electron flux at geosynchronous orbit near midnight, and the angle of rotation of the geosynchronous magnetic field near midnight. The substorm amplitudes are statistically analyzed, the amplitude measurements are cross correlated with each other, and the substorm amplitudes are determined as functions of the solar-wind parameters. Periodically occurring and randomly occurring substorms are analyzed separately. The energetic-particle-flux amplitudes are consistent with unloading and the AL amplitudes are consistent with direct driving plus unloading.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

  14. N >= 4 Supergravity Amplitudes from Gauge Theory at Two Loops

    SciTech Connect

    Boucher-Veronneau, C.; Dixon, L.J.; /SLAC

    2012-02-15

    We present the full two-loop four-graviton amplitudes in N = 4, 5, 6 supergravity. These results were obtained using the double-copy structure of gravity, which follows from the recently conjectured color-kinematics duality in gauge theory. The two-loop four-gluon scattering amplitudes in N = 0, 1, 2 supersymmetric gauge theory are a second essential ingredient. The gravity amplitudes have the expected infrared behavior: the two-loop divergences are given in terms of the squares of the corresponding one-loop amplitudes. The finite remainders are presented in a compact form. The finite remainder for N = 8 supergravity is also presented, in a form that utilizes a pure function with a very simple symbol.

  15. Measurement of the light-field amplitude-correlation function through joint photon-count distributions.

    NASA Technical Reports Server (NTRS)

    Furcinitti, P.; Kuppenheimer, J. D.; Narducci, L. M.; Tuft , R. A.

    1972-01-01

    When an amplitude-stabilized He-Ne laser beam is scattered by a rotating ground glass with small surface inhomogeneities, the probability density of the instantaneous scattered-wave amplitude is Gaussian. In this paper, we suggest the use of the joint photon-count probability distribution to measure the absolute value of the electric-field amplitude-correlation function for random Gaussian light fields, and report the results of an experiment in which the Gaussian field is produced by scattering a light beam through a rotating ground glass. This procedure offers an alternative to other conventional methods, such as self-beating spectroscopy and irradiance-correlation techniques. The correlation time of the scattered-field amplitude in the present experiment has been measured with an accuracy of approximately 0.8%.

  16. Amplitude path corrections for regional phases in China

    SciTech Connect

    Phillips, W.S.; Velasco, A.A.; Taylor, S.R.; Randall, G.E.

    1998-12-31

    The authors investigate the effectiveness of amplitude path corrections for regional phases on seismic event discrimination and magnitude estimation. Waveform data from digital stations in China for regional, shallow (< 50 km) events were obtained from the IRIS Data Management Center (DMC) for years 1986 to 1996 using the USGS Preliminary Determination of Epicenters (PDE) and the Chinese State Seismological Bureau (SSB) catalogs. For each event, the amplitudes for each regional phase (P{sub n}, P{sub g}, S{sub n}, L{sub g}) were measured, as well as the P{sub g} and L{sub g} coda. Measured amplitudes were corrected for source scaling using estimates of m{sub b} and for distance using a power law that accounts for attenuation and spreading. The amplitude residuals were interpolated and mapped as 2-D amplitude correction surfaces. The authors employ several methods to create the amplitude correction surfaces: a waveguide method, and two interpolation methods (Baysian kriging and a circular moving window mean smoother). They explore the sensitivities of the surfaces to the method and to regional propagation, and apply these surfaces to correct amplitude data to reduce scatter in discrimination ratios and magnitude estimates.

  17. Helicity Amplitudes for Photoproduction of Baryons with J = 1/2 and JP = 3/2+

    NASA Astrophysics Data System (ADS)

    Liu, Lei-Hua

    2015-12-01

    We derive the separate helicity amplitudes using the partial wave analysis in the process of pseudo-scalar meson photoproduction. For JP = 3/2+, we find the amplitude is model independent. According to parity conservation, the general amplitude in the case of JP = 1/2- is obtained. We prove this general amplitude corresponds to the situation of λ = -1 when adopting the circular polarization. Finally, the formulas of scattering amplitudes involving the meson photoproduction with JP = 3/2+ are obtained from the chiral quark model. Supported by the Chinese Scholarship Council (CSC)

  18. Scalar scattering via conformal higher spin exchange

    NASA Astrophysics Data System (ADS)

    Joung, Euihun; Nakach, Simon; Tseytlin, Arkady A.

    2016-02-01

    Theories containing infinite number of higher spin fields require a particular definition of summation over spins consistent with their underlying symmetries. We consider a model of massless scalars interacting (via bilinear conserved currents) with conformal higher spin fields in flat space. We compute the tree-level four-scalar scattering amplitude using a natural prescription for summation over an infinite set of conformal higher spin exchanges and find that it vanishes. Independently, we show that the vanishing of the scalar scattering amplitude is, in fact, implied by the global conformal higher spin symmetry of this model. We also discuss one-loop corrections to the four-scalar scattering amplitude.

  19. One-loop corrections from higher dimensional tree amplitudes

    NASA Astrophysics Data System (ADS)

    Cachazo, Freddy; He, Song; Yuan, Ellis Ye

    2016-08-01

    We show how one-loop corrections to scattering amplitudes of scalars and gauge bosons can be obtained from tree amplitudes in one higher dimension. Starting with a complete tree-level scattering amplitude of n + 2 particles in five dimensions, one assumes that two of them cannot be "detected" and therefore an integration over their LIPS is carried out. The resulting object, function of the remaining n particles, is taken to be four-dimensional by restricting the corresponding momenta. We perform this procedure in the context of the tree-level CHY formulation of amplitudes. The scattering equations obtained in the procedure coincide with those derived by Geyer et al. from ambitwistor constructions and recently studied by two of the authors for bi-adjoint scalars. They have two sectors of solutions: regular and singular. We prove that the contribution from regular solutions generically gives rise to unphysical poles. However, using a BCFW argument we prove that the unphysical contributions are always homogeneous functions of the loop momentum and can be discarded. We also show that the contribution from singular solutions turns out to be homogeneous as well.

  20. Amplitude and phase modulation with waveguide optics

    SciTech Connect

    Burkhart, S.C.; Wilcox, R.B.; Browning, D.; Penko, F.A.

    1996-12-17

    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.

  1. Rayleigh Scattering.

    ERIC Educational Resources Information Center

    Young, Andrew T.

    1982-01-01

    The correct usage of such terminology as "Rayleigh scattering,""Rayleigh lines,""Raman lines," and "Tyndall scattering" is resolved during an historical excursion through the physics of light-scattering by gas molecules. (Author/JN)

  2. Scattering equations and global duality of residues

    NASA Astrophysics Data System (ADS)

    Søgaard, Mads; Zhang, Yang

    2016-05-01

    We examine the polynomial form of the scattering equations by means of computational algebraic geometry. The scattering equations are the backbone of the Cachazo-He-Yuan (CHY) representation of the S-matrix. We explain how the Bezoutian matrix facilitates the calculation of amplitudes in the CHY formalism, without explicitly solving the scattering equations or summing over the individual residues. Since for n -particle scattering the size of the Bezoutian matrix grows only as (n -3 )×(n -3 ), our algorithm is very efficient for analytic and numeric amplitude computations.

  3. Hadron scattering and resonances in QCD

    NASA Astrophysics Data System (ADS)

    Dudek, Jozef J.

    2016-05-01

    I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study ππ elastic scattering, including the ρ resonance, as well as coupled-channel π >K, ηK scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  4. Shape of Pion Distribution Amplitude

    SciTech Connect

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  5. Phase coherence and pairing amplitude in photo-excited superconductors

    NASA Astrophysics Data System (ADS)

    Perfetti, Luca; Piovera, Christian; Zhang, Zailan

    2016-05-01

    New data on Bi2Sr2CaCu2O8+δ (Bi2212) reveal interesting aspects of photoexcited superconductors. The electrons dynamics show that inelastic scattering by nodal quasiparticles decreases when the temperature is lowered below the critical value of the superconducting phase transition. This drop of electronic dissipation is astonishingly robust and survives to photoexcitation densities much larger than the value sustained by long-range superconductivity. The unconventional behavior of quasiparticle scattering is ascribed to superconducting correlations extending on a length scale comparable to the inelastic mean-free path. Our measurements indicate that strongly driven superconductors enter in a regime without phase coherence but finite pairing amplitude.

  6. An Analysis of Fundamental Mode Surface Wave Amplitude Measurements

    NASA Astrophysics Data System (ADS)

    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.

  7. Amplitude relations in non-linear sigma model

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Du, Yi-Jian

    2014-01-01

    In this paper, we investigate tree-level scattering amplitude relations in U( N) non-linear sigma model. We use Cayley parametrization. As was shown in the recent works [23,24], both on-shell amplitudes and off-shell currents with odd points have to vanish under Cayley parametrization. We prove the off-shell U(1) identity and fundamental BCJ relation for even-point currents. By taking the on-shell limits of the off-shell relations, we show that the color-ordered tree amplitudes with even points satisfy U(1)-decoupling identity and fundamental BCJ relation, which have the same formations within Yang-Mills theory. We further state that all the on-shell general KK, BCJ relations as well as the minimal-basis expansion are also satisfied by color-ordered tree amplitudes. As a consequence of the relations among color-ordered amplitudes, the total 2 m-point tree amplitudes satisfy DDM form of color decomposition as well as KLT relation.

  8. TASI 2014: Lectures on Gauge and Gravity Amplitude Relations

    NASA Astrophysics Data System (ADS)

    Carrasco, John Joseph M.

    In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action, these structures are currently only understood in terms of graphical organizational principles, such as the gauge-theoretic color-kinematics duality and the gravitational double-copy structure, for local representations of multi-loop S-matrix elements. These graphical principles make manifest new relationships in and between gauge and gravity scattering amplitudes. My lectures will focus on arriving at such graphical organizations for generic theories with examples presented from maximal supersymmetry, and their use in unitarity-based multiloop integrand construction.

  9. K- nuclear potentials based on chiral meson-baryon amplitudes

    NASA Astrophysics Data System (ADS)

    Mareš, J.; Cieplý, A.; Gazda, D.; Friedman, E.; Gal, A.

    2012-09-01

    K- nuclear optical potentials are constructed from in-medium subthreshold K¯N scattering amplitudes within a chirally motivated coupled-channel model. We demonstrate how the strong energy and density dependence of the scattering amplitudes at and below threshold leads to a deep K- nuclear potential VK- for kaonic atoms and K- nuclear quasibound states. Selfconsistent evaluations yield K- potential depths -ReVK- (ρ0) of order 100 MeV. Allowing for K- NN absorption, better agreement with K- atoms data is achieved, leading to increased potential depths, -ReVK- (ρ0) ˜ 175 MeV, in accord with density dependent potentials obtained in purely phenomenological fits. Self consistent dynamical calculations of K- nuclear quasibound states are reported and discussed, as well.

  10. Large amplitude drop shape oscillations

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Wang, T. G.

    1982-01-01

    An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.

  11. Employing helicity amplitudes for resummation

    NASA Astrophysics Data System (ADS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.

    2016-05-01

    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 p p →H +0 , 1, 2 jets, p p →W /Z /γ +0 , 1, 2 jets, and p p →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.

  12. N-loop string amplitude

    SciTech Connect

    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. (LEW)

  13. Positivity of spin foam amplitudes

    NASA Astrophysics Data System (ADS)

    Baez, John C.; Christensen, J. Daniel

    2002-04-01

    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 (eiS) 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.

  14. Constant-amplitude RC oscillator

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Westbrook, R. M.

    1970-01-01

    Sinusoidal oscillator has a frequency determined by resistance-capacitance /RC/ values of two charge control devices and a constant-amplitude voltage independent of frequency and RC values. RC elements provide either voltage-control, resistance-control, or capacitance-control of the frequency.

  15. Extracting forward strong amplitudes from elastic differential cross sections

    SciTech Connect

    C.M. Chen; D.J. Ernst; Mikkel B. Johnson

    2001-07-01

    The feasibility of a model-independent extraction of the forward strong amplitude from elastic nuclear cross section data in the Coulomb-nuclear interference region is assessed for {pi} and K{sup +} scattering at intermediate energies. Theoretically-generated ''data'' are analyzed to provide criteria for optimally designing experiments to measure these amplitudes, whose energy dependence (particularly that of the real parts) is needed for disentangling various sources of medium modifications of the projectile-nucleon interaction. The issues considered include determining the angular region over which to make the measurements, the role of the most forward angles measured, and the effects of statistical and systematic errors. We find that there is a region near the forward direction where Coulomb-nuclear interference allows reliable extraction of the strong forward amplitude for both pions and the K{sup +} from .3 to 1 GeV/c.

  16. On the four-dimensional formulation of dimensionally regulated amplitudes

    NASA Astrophysics Data System (ADS)

    Fazio, A. R.; Mastrolia, P.; Mirabella, E.; Torres Bobadilla, W. J.

    2014-12-01

    Elaborating on the four-dimensional helicity scheme, we propose a pure four-dimensional formulation (FDF) of the -dimensional regularization of one-loop scattering amplitudes. In our formulation particles propagating inside the loop are represented by massive internal states regulating the divergences. The latter obey Feynman rules containing multiplicative selection rules which automatically account for the effects of the extra-dimensional regulating terms of the amplitude. We present explicit representations of the polarization and helicity states of the four-dimensional particles propagating in the loop. They allow for a complete, four-dimensional, unitarity-based construction of -dimensional amplitudes. Generalized unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the spinor algebra. Finally we show how the FDF allows for the recursive construction of -dimensional one-loop integrands, generalizing the four-dimensional open-loop approach.

  17. Superstring disk amplitudes in a rolling tachyon background

    SciTech Connect

    Jokela, Niko; Majumder, Jaydeep; Keski-Vakkuri, Esko

    2006-02-15

    We study the tree level scattering or emission of n closed superstrings from a decaying non-BPS brane in Type II superstring theory. We attempt to calculate generic n-point superstring disk amplitudes in the rolling tachyon background. We show that these can be written as infinite power series of Toeplitz determinants, related to expectation values of a periodic function in Circular Unitary Ensembles. Further analytical progress is possible in the special case of bulk-boundary disk amplitudes. These are interpreted as probability amplitudes for emission of a closed string with initial conditions perturbed by the addition of an open string vertex operator. This calculation has been performed previously in bosonic string theory, here we extend the analysis for superstrings. We obtain a result for the average energy of closed superstrings produced in the perturbed background.

  18. Quasi-steady, marginally unstable electron cyclotron harmonic wave amplitudes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaojia; Angelopoulos, Vassilis; Ni, Binbin; Thorne, Richard M.; Horne, Richard B.

    2013-06-01

    Electron cyclotron harmonic (ECH) waves have long been considered a potential driver of diffuse aurora in Earth's magnetotail. However, the scarcity of intense ECH emissions in the outer magnetotail suggests that our understanding of the amplification and the relative importance of these waves for electron scattering is lacking. We conduct a comprehensive study of wave growth and quasi-linear diffusion to estimate the amplitude of loss-cone-driven ECH waves once diffusion and growth balance but before convection or losses alter the background hot plasma sheet population. We expect this to be the most common state of the plasma sheet between episodes of fast convection. For any given wave amplitude, we model electron diffusion caused by interaction with ECH waves using a 2-D bounce-averaged Fokker-Planck equation. After fitting the resultant electron distributions as a superposition of multicomponent subtracted bi-Maxwellians, we estimate the maximum path-integrated gain using the HOTRAY ray-tracing code. We argue that the wave amplitude during quasi-steady state is the inflection point on a gain-amplitude curve. During quasi-steady state, ECH wave amplitudes can be significant (~1 mV/m) at L ~ 8 but drop to very low values (<~0.1 mV/m) in the outer magnetotail (L ~ 16) and likely fall below the sensitivity of typical instrumentation relatively close to Earth mainly because of the smallness of the loss cone. Our result reinforces the potentially important role of ECH waves in driving diffuse aurora and suggests that careful comparison of theoretical wave amplitude estimates and observations is required for resolving the equatorial scattering mechanism of diffuse auroral precipitation.

  19. True amplitude prestack depth migration

    NASA Astrophysics Data System (ADS)

    Deng, Feng

    Reliable analysis of amplitude variation with offset (or with angle) requires accurate amplitudes from prestack migration. In routine seismic data processing, amplitude balancing and automatic gain control are often used to reduce amplitude lateral variations. However, these methods are empirical and lack a solid physical basis; thus, there are uncertainties that might produce erroneous conclusions, and hence cause economic loss. During wavefield propagation, geometrical spreading, intrinsic attenuation, transmission losses and the energy conversion significantly distort the wavefield amplitude. Most current true-amplitude migrations usually compensate only for geometrical spreading. A new prestack depth migration based on the framework of reverse-time migration in the time-space domain was developed in this dissertation with the aim of compensating all of the propagation effects in one integrated algorithm. Geometrical spreading is automatically included because of the use of full two-way wave extrapolation. Viscoelastic wave equations are solved to handle the intrinsic attenuation with a priori quality factor. Transmission losses for both up- and down-going waves are compensated using a two-pass, recursive procedure based on extracting the angle-dependent reflection/transmission coefficients from prestack migration. The losses caused by the conversion of energy from one elastic model to another are accounted for through elastic wave extrapolation; the influence of the S wave velocity contrast on the P wave reflection coefficient is implicitly included by using the Zoeppritz equations to describe the reflection and transmission at an elastic interface. Only smooth background models are assumed to be known. The contrasts/ratios of the model parameters can be estimated by fitting the compensated angle-dependent reflection coefficients obtained from data for multiple sources. This is one useful by-product of the algorithm. Numerical tests on both 2D and 3D scalar

  20. Randomized gap and amplitude estimation

    NASA Astrophysics Data System (ADS)

    Zintchenko, Ilia; Wiebe, Nathan

    2016-06-01

    We provide a method for estimating spectral gaps in low-dimensional systems. Unlike traditional phase estimation, our approach does not require ancillary qubits nor does it require well-characterized gates. Instead, it only requires the ability to perform approximate Haar random unitary operations, applying the unitary whose eigenspectrum is sought and performing measurements in the computational basis. We discuss application of these ideas to in-place amplitude estimation and quantum device calibration.

  1. Genus dependence of superstring amplitudes

    SciTech Connect

    Davis, Simon

    2006-11-15

    The problem of the consistency of the finiteness of the supermoduli space integral in the limit of vanishing super-fixed point distance and the genus-dependence of the integral over the super-Schottky coordinates in the fundamental region containing a neighborhood of |K{sub n}|=0 is resolved. Given a choice of the categories of isometric circles representing the integration region, the exponential form of bounds for superstring amplitudes is derived.

  2. Pulse amplitude modulated chlorophyll fluorometer

    SciTech Connect

    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. Wave-scattering from a gently curved surface

    NASA Astrophysics Data System (ADS)

    Bimonte, Giuseppe

    2016-09-01

    We study wave scattering from a gently curved surface. We show that the recursive relations, implied by shift invariance, among the coefficients of the perturbative series for the scattering amplitude allow to perform an infinite resummation of the perturbative series to all orders in the amplitude of the corrugation. The resummed series provides a derivative expansion of the scattering amplitude in powers of derivatives of the height profile, which is expected to become exact in the limit of quasi-specular scattering. We discuss the relation of our results with the so-called small-slope approximation introduced some time ago by Voronovich.

  4. Type 0 open string amplitudes and the tensionless limit

    NASA Astrophysics Data System (ADS)

    Rojas, Francisco

    2014-12-01

    The sum over planar multiloop diagrams in the NS + sector of type 0 open strings in flat spacetime has been proposed by Thorn as a candidate to resolve nonperturbative issues of gauge theories in the large N limit. With S U (N ) Chan-Paton factors, the sum over planar open string multiloop diagrams describes the 't Hooft limit N →∞ with N gs2 held fixed. By including only planar diagrams in the sum the usual mechanism for the cancellation of loop divergences (which occurs, for example, among the planar and Möbius strip diagrams by choosing a specific gauge group) is not available and a renormalization procedure is needed. In this article the renormalization is achieved by suspending total momentum conservation by an amount p ≡∑ i n ki≠0 at the level of the integrands in the integrals over the moduli and analytically continuing them to p =0 at the very end. This procedure has been successfully tested for the 2 and 3 gluon planar loop amplitudes by Thorn. Gauge invariance is respected and the correct running of the coupling in the limiting gauge field theory was also correctly obtained. In this article we extend those results in two directions. First, we generalize the renormalization method to an arbitrary n -gluon planar loop amplitude giving full details for the 4-point case. One of our main results is to provide a fully renormalized amplitude which is free of both UV and the usual spurious divergences leaving only the physical singularities in it. Second, using the complete renormalized amplitude, we extract the high-energy scattering regime at fixed angle (tensionless limit). Apart from obtaining the usual exponential falloff at high energies, we compute the full dependence on the scattering angle which shows the existence of a smooth connection between the Regge and hard scattering regimes.

  5. Surface-integral formulation of scattering theory

    SciTech Connect

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

    2009-07-15

    We formulate scattering theory in the framework of a surface-integral approach utilizing analytically known asymptotic forms of the two-body and three-body scattering wavefunctions. This formulation is valid for both short-range and long-range Coulombic interactions. New general definitions for the potential scattering amplitude are presented. For the Coulombic potentials, the generalized amplitude gives the physical on-shell amplitude without recourse to a renormalization procedure. New post and prior forms for the Coulomb three-body breakup amplitude are derived. This resolves the problem of the inability of the conventional scattering theory to define the post form of the breakup amplitude for charged particles. The new definitions can be written as surface-integrals convenient for practical calculations. The surface-integral representations are extended to amplitudes of direct and rearrangement scattering processes taking place in an arbitrary three-body system. General definitions for the wave operators are given that unify the currently used channel-dependent definitions.

  6. Massive superstring scatterings in the Regge regime

    SciTech Connect

    He Song; Lee, Jen-Chi; Takahashi, Keijiro; Yang Yi

    2011-03-15

    We calculate four classes of high-energy massive string scattering amplitudes of fermionic string theory at arbitrary mass levels in the Regge regime (RR). We show that all four leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. Based on the summation algorithm of a set of extended signed Stirling number identities, we show that all four ratios calculated previously by the method of decoupling of zero-norm states among scattering amplitudes in the Gross regime can be extracted from this Kummer function in the RR. Finally, we conjecture and give evidence that the existence of these four Gross regime ratios in the RR persists to subleading orders in the Regge expansion of all high-energy fermionic string scattering amplitudes.

  7. Massive superstring scatterings in the Regge regime

    NASA Astrophysics Data System (ADS)

    He, Song; Lee, Jen-Chi; Takahashi, Keijiro; Yang, Yi

    2011-03-01

    We calculate four classes of high-energy massive string scattering amplitudes of fermionic string theory at arbitrary mass levels in the Regge regime (RR). We show that all four leading order amplitudes in the RR can be expressed in terms of the Kummer function of the second kind. Based on the summation algorithm of a set of extended signed Stirling number identities, we show that all four ratios calculated previously by the method of decoupling of zero-norm states among scattering amplitudes in the Gross regime can be extracted from this Kummer function in the RR. Finally, we conjecture and give evidence that the existence of these four Gross regime ratios in the RR persists to subleading orders in the Regge expansion of all high-energy fermionic string scattering amplitudes.

  8. The scattering of the screened Coulomb potential

    NASA Astrophysics Data System (ADS)

    Cao, Xin-Wei; Chen, Wen-Li; Li, Yuan-Yuan; Wei, Gao-Feng

    2014-08-01

    We study the scattering states of the screened Coulomb potential in the nonrelativistic frame. The explicitly calculation formula of phase shift is derived and the normalized radial wave functions of scattering states on the ^{\\prime} k/2\\pi scale^{\\prime} are presented. By studying analytical properties of scattering amplitude the screening effects on bound states are discussed numerically. It is shown that the screening effects increase with increasing screened parameter, especially for large quantum states.

  9. Constraints on string resonance amplitudes

    NASA Astrophysics Data System (ADS)

    Cheung, Kingman; Liu, Yueh-Feng

    2005-07-01

    We perform a global analysis of the tree-level open-string amplitudes in the limit s≪M2S. Based on the present data from the Tevatron, HERA, and LEP 2, we set a lower limit on the string scale MS≥0.69 1.96 TeV at 95% confidence level for the Chan-Paton factors |T|=0-4. We also estimate the expected sensitivities at the CERN LHC, which can be as high as 19 TeV for |T|=4.

  10. Scattering calculations and confining interactions

    NASA Technical Reports Server (NTRS)

    Buck, Warren W.; Maung, Khin M.

    1993-01-01

    Most of the research work performed under this grant were concerned with strong interaction processes ranging from kaon-nucleon interaction to proton-nucleus scattering calculations. Research performed under this grant can be categorized into three groups: (1) parametrization of fundamental interactions, (2) development of formal theory, and (3) calculations based upon the first two. Parametrizations of certain fundamental interactions, such as kaon-nucleon interaction, for example, were necessary because kaon-nucleon scattering amplitude was needed to perform kaon-nucleus scattering calculations. It was possible to calculate kaon-nucleon amplitudes from the first principle, but it was unnecessary for the purpose of the project. Similar work was also done for example for anti-protons and anti-nuclei. Formal developments to some extent were also pursued so that consistent calculations can be done.

  11. Zero energy scattering calculation in Euclidean space

    NASA Astrophysics Data System (ADS)

    Carbonell, J.; Karmanov, V. A.

    2016-03-01

    We show that the Bethe-Salpeter equation for the scattering amplitude in the limit of zero incident energy can be transformed into a purely Euclidean form, as it is the case for the bound states. The decoupling between Euclidean and Minkowski amplitudes is only possible for zero energy scattering observables and allows determining the scattering length from the Euclidean Bethe-Salpeter amplitude. Such a possibility strongly simplifies the numerical solution of the Bethe-Salpeter equation and suggests an alternative way to compute the scattering length in Lattice Euclidean calculations without using the Luscher formalism. The derivations contained in this work were performed for scalar particles and one-boson exchange kernel. They can be generalized to the fermion case and more involved interactions.

  12. One-loop amplitudes on the Riemann sphere

    NASA Astrophysics Data System (ADS)

    Geyer, Yvonne; Mason, Lionel; Monteiro, Ricardo; Tourkine, Piotr

    2016-03-01

    The scattering equations provide a powerful framework for the study of scattering amplitudes in a variety of theories. Their derivation from ambitwistor string theory led to proposals for formulae at one loop on a torus for 10 dimensional supergravity, and we recently showed how these can be reduced to the Riemann sphere and checked in simple cases. We also proposed analogous formulae for other theories including maximal super-Yang-Mills theory and supergravity in other dimensions at one loop. We give further details of these results and extend them in two directions. Firstly, we propose new formulae for the one-loop integrands of Yang-Mills theory and gravity in the absence of supersymmetry. These follow from the identification of the states running in the loop as expressed in the ambitwistor-string correlator. Secondly, we give a systematic proof of the non-supersymmetric formulae using the worldsheet factorisation properties of the nodal Riemann sphere underlying the scattering equations at one loop. Our formulae have the same decomposition under the recently introduced Q-cuts as one-loop integrands and hence give the correct amplitudes.

  13. Constructing Amplitudes from Their Soft Limits

    SciTech Connect

    Boucher-Veronneau, Camille; Larkoski, Andrew J.; /SLAC

    2011-12-09

    The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an (n-1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which 'soft' particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.

  14. Generalized optical theorem for scattering in inhomogeneous media.

    PubMed

    Dacol, Dalcio K; Roy, Dilip G

    2005-09-01

    The scattering of scalar waves by objects embedded in an inhomogeneous medium contained by a bounded volume is discussed using the method of pseudopotentials. The scattering amplitude for the object in an extended uniform medium is assumed known and used as input. The scattering process is described by using an expansion of the scattering amplitude in terms of spherical harmonics. An appropriate multipole decomposition of the Green function in the bounded medium is developed and the effective scattering amplitude in this environment is defined. The generalized optical theorem obeyed by this effective scattering amplitude is obtained and analyzed. The scattering problem is formulated entirely and explicitly in terms of the bounded medium's Green functions. This approach is thus very flexible in regards to the choice of incident field. In the case of waveguides the connection between propagation and scattering is explicit. At the same time it still allows for independent computation of the propagation and scattering aspects of the problem. This is the main advantage of using as input the scattering amplitude in an extended uniform medium. PMID:16241594

  15. Measurements of Dust Oscillations with Laser Heterodyne Receiver of Scattered Radiation

    SciTech Connect

    Serozhkin, Yuriy; Venger, Yevgen

    2011-11-29

    We performed the experiments on measurement of vibration amplitudes for microparticles in gas and water with laser heterodyne receiver of scattered radiation. The measured vibration amplitude values are about 20 nm.

  16. Timelike Compton Scattering

    SciTech Connect

    T. Horn, Y. Illieva, F. J. Klein, P. Nadel‐Turonski, R. Paremuzyan, S. Stepanyan

    2011-10-01

    Generalized Parton Distributions (GPDs) have become a key concept in our studies of hadron structure in QCD. The measurement of suitable experimental observables and the extraction of GPDs from these data is one of the high priority 12 GeV programs at Jefferson Lab. Deeply Virtual Compton Scattering (DVCS) is generally thought of as the most promising channel for probing GPDs in the valence quark region. However, the inverse process, Timelike Compton Scattering (TCS) can provide an important complementary measurement, in particular of the real part of the Compton amplitude and power corrections at intermediate values of Q2. The first studies of TCS using real tagged and quasi-real untagged photons were performed in Hall B at Jefferson Lab.

  17. New identities among gauge theory amplitudes

    NASA Astrophysics Data System (ADS)

    Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Feng, Bo; Søndergaard, Thomas

    2010-08-01

    Color-ordered amplitudes in gauge theories satisfy non-linear identities involving amplitude products of different helicity configurations. We consider the origin of such identities and connect them to the Kawai-Lewellen-Tye (KLT) relations between gravity and gauge theory amplitudes. Extensions are made to one-loop order of the full N = 4 super Yang-Mills multiplet.

  18. Multiple scattering and charged-particle - hydrogen-atom collisions

    NASA Technical Reports Server (NTRS)

    Franco, V.; Thomas, B. K.

    1979-01-01

    Glauber-approximation scattering amplitudes for charged-particle - hydrogen-atom elastic and inelastic collisions are derived directly in terms of the known particle-electron and particle-proton Coulomb scattering amplitudes and the known hydrogen-atom form factors. It is shown that the particle-hydrogen amplitude contains no single-scattering term. The double-scattering term is obtained as a two-dimensional integral in momentum space. It is demonstrated how the result can be used as the starting point for an alternative and relatively simple derivation, in closed form, of the Glauber particle-hydrogen scattering amplitude for transitions from the ground state to an arbitrary (nlm) state.

  19. Decoherence due to Elastic Rayleigh Scattering

    NASA Astrophysics Data System (ADS)

    Uys, H.; Biercuk, M. J.; Vandevender, A. P.; Ospelkaus, C.; Meiser, D.; Ozeri, R.; Bollinger, J. J.

    2010-11-01

    We present theoretical and experimental studies of the decoherence of hyperfine ground-state superpositions due to elastic Rayleigh scattering of light off resonant with higher lying excited states. We demonstrate that under appropriate conditions, elastic Rayleigh scattering can be the dominant source of decoherence, contrary to previous discussions in the literature. We show that the elastic-scattering decoherence rate of a two-level system is given by the square of the difference between the elastic-scattering amplitudes for the two levels, and that for certain detunings of the light, the amplitudes can interfere constructively even when the elastic-scattering rates from the two levels are equal. We confirm this prediction through calculations and measurements of the total decoherence rate for a superposition of the valence electron spin levels in the ground state of Be+9 in a 4.5 T magnetic field.

  20. Decoherence due to elastic Rayleigh scattering.

    PubMed

    Uys, H; Biercuk, M J; Vandevender, A P; Ospelkaus, C; Meiser, D; Ozeri, R; Bollinger, J J

    2010-11-12

    We present theoretical and experimental studies of the decoherence of hyperfine ground-state superpositions due to elastic Rayleigh scattering of light off resonant with higher lying excited states. We demonstrate that under appropriate conditions, elastic Rayleigh scattering can be the dominant source of decoherence, contrary to previous discussions in the literature. We show that the elastic-scattering decoherence rate of a two-level system is given by the square of the difference between the elastic-scattering amplitudes for the two levels, and that for certain detunings of the light, the amplitudes can interfere constructively even when the elastic-scattering rates from the two levels are equal. We confirm this prediction through calculations and measurements of the total decoherence rate for a superposition of the valence electron spin levels in the ground state of 9Be+ in a 4.5 T magnetic field. PMID:21231210

  1. Intermediate energy proton-deuteron elastic scattering

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.

    1973-01-01

    A fully symmetrized multiple scattering series is considered for the description of proton-deuteron elastic scattering. An off-shell continuation of the experimentally known twobody amplitudes that retains the exchange symmeteries required for the calculation is presented. The one boson exchange terms of the two body amplitudes are evaluated exactly in this off-shell prescription. The first two terms of the multiple scattering series are calculated explicitly whereas multiple scattering effects are obtained as minimum variance estimates from the 146-MeV data of Postma and Wilson. The multiple scattering corrections indeed consist of low order partial waves as suggested by Sloan based on model studies with separable interactions. The Hamada-Johnston wave function is shown consistent with the data for internucleon distances greater than about 0.84 fm.

  2. Evaluation of the Cachazo-He-Yuan gauge amplitude

    NASA Astrophysics Data System (ADS)

    Lam, C. S.; Yao, York-Peng

    2016-05-01

    The Cachazo-He-Yuan (CHY) formula for n -gluon scattering is known to give the same amplitude as the one obtained from Feynman diagrams, though the former contains neither vertices nor propagators explicitly. The equivalence was shown by indirect means, not by a direct evaluation of the (n -3 )-dimensional integral in the CHY formula. The purpose of this paper is to discuss how such a direct evaluation can be carried out. There are two basic difficulties in the calculation: how to handle the large number of terms in the reduced Pfaffian, and how to carry out the integrations in the presence of a σ dependence much more complicated than the Parke-Taylor form found in a CHY double-color scalar amplitude. We have solved both of these problems, and have formulated a method that can be applied to any n . Many examples are provided to illustrate these calculations.

  3. BPS amplitudes, helicity supertraces and membranes in M-theory

    NASA Astrophysics Data System (ADS)

    Wit, B. d.; Lüst, D.

    2000-03-01

    We study BPS dominated loop amplitudes in M-theory on T2. For this purpose we generalize the concept of helicity supertraces to nine spacetime dimensions. These traces distinguish between various massive supermultiplets and appear as coefficients in their one-loop contributions to n-graviton scattering amplitudes. This can be used to show that only ultrashort BPS multiplets contribute to the R4 term in the effective action, which was first computed by Green, Gutperle and Vanhove. There are two inequivalent ultrashort BPS multiplets which describe the Kaluza-Klein states and the wrapped membranes that cover the torus a number of times. From the perspective of the type-II strings they correspond to momentum and winding states and D0 or D1 branes.

  4. Amplitudes of the two-nucleon interaction at 579 MeV

    NASA Astrophysics Data System (ADS)

    Arash, Firooz; Moravcsik, Michael J.; Goldstein, Gary

    1985-07-01

    A complete amplitude analysis is presented of the 579-MeV data set for p-p elastic scattering. Although all continua of ambiguities are eliminated by the extensive nature of the data, discrete ambiguities remain, as expected from general criteria for such ambiguities. In particular, four solutions are found. Further experiments are specified which can resolve this remaining ambiguity also. A comparison is also made with previous amplitude results at this energy.

  5. Hedgehog bases for A n cluster polylogarithms and an application to six-point amplitudes

    NASA Astrophysics Data System (ADS)

    Parker, Daniel E.; Scherlis, Adam; Spradlin, Marcus; Volovich, Anastasia

    2015-11-01

    Multi-loop scattering amplitudes in N=4 Yang-Mills theory possess cluster algebra structure. In order to develop a computational framework which exploits this connection, we show how to construct bases of Goncharov polylogarithm functions, at any weight, whose symbol alphabet consists of cluster coordinates on the A n cluster algebra. Using such a basis we present a new expression for the 2-loop 6-particle NMHV amplitude which makes some of its cluster structure manifest.

  6. Amplitude and Width Correlations in COBALT-57 and VANADIUM-49.

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Prabha K.

    Angular distributions of the inelastically scattered protons and of the deexcitation (gamma)-rays in the ('56)Fe(p,p'(gamma)) reaction were measured for d-wave resonances in the proton energy range 3.10 to 4.01 MeV. The experiment was performed with an overall energy resolution of 350 to 400 eV (FWHM) at the Triangle Universities Nuclear Laboratory KN Van de Graaff accelerator and associated high resolution system. Results were obtained for 141 resonances; 83 resonances were assigned J('(pi)) = 5/2('+), while 58 resonances were assigned J('(pi)) = 3/2('+). Mixing parameters for the inelastic decay amplitudes were uniquely determined for the 5/2('+) resonances. For the 3/2('+) resonances sufficient information is not available from this experiment to extract a unique solution for the mixing parameters. Magnitudes and relative signs of three inelastic decay amplitudes were determined for the 5/2('+) resonances in ('57)Co. The angular distributions for the deexcitation (gamma)-rays were measured in coincidence with the inelastically scattered protons for 30 3/2('+) resonances in ('49)V in the proton energy region 2.2 to 3.1 MeV. The singles measurements from a previous experiment were combined with these coincidence measurements to eliminate the ambiguity in the solutions for the mixing parameters. Amplitude and width measurements were determined for the three decay channels for 30 3/2('+) resonances. Statistical analyses were performed on the set of 83 5/2('+) resonances in ('57)Co and on the set of 30 3/2('+) resonances in ('49)V. In both cases, large amplitude and width correlations are observed. These results are interpreted as evidence for direct reactions between the inelastic channels.

  7. Integrable amplitude deformations for N =4 super Yang-Mills and ABJM theory

    NASA Astrophysics Data System (ADS)

    Bargheer, Till; Huang, Yu-Tin; Loebbert, Florian; Yamazaki, Masahito

    2015-01-01

    We study Yangian-invariant deformations of scattering amplitudes in 4d N =4 super Yang-Mills theory and 3d N =6 Aharony-Bergman-Jafferis-Maldacena (ABJM) theory. In particular, we obtain the deformed Graßmannian integral for 4d N =4 supersymmetric Yang-Mills theory, both in momentum and momentum-twistor space. For 3d ABJM theory, we initiate the study of deformed scattering amplitudes. We investigate general deformations of on-shell diagrams, and find the deformed Graßmannian integral for this theory. We furthermore introduce the algebraic R-matrix construction of deformed Yangian invariants for ABJM theory.

  8. Amplitude tests of direct channel resonances: The dibaryon

    NASA Astrophysics Data System (ADS)

    Goldstein, G. R.; Moravosik, M. J.; Arash, F.

    1985-02-01

    A recently formulated polarization amplitude test for the existence of one-particle-exchange mechanisms is modified to deal with direct-channel resonances. The results are applied to proton-proton elastic scattering at and around 800 MeV to test the suggested existence of a dibaryon resonance. This test is sensitive to somewhat different circumstances and parameters than the methods used in the past to find dibaryon resonances. The evidence, on the basis of the SAID data set, is negative for a resonance in any singlet partial wave, but is tantalizingly subliminal for a 3F3 resonance.

  9. Amplitude-phase patterns: A new look at strong interactions

    NASA Astrophysics Data System (ADS)

    Goldstein, Gary R.; Arash, Firooz; Moravcsik, Michael J.

    1994-10-01

    The phases of complex spin-dependent scattering amplitudes for elastic processes NN, πN, πd, along with pp→d π+, are analyzed in various frames of reference for spin quantization. When all available energies and angles are compiled it is seen that the "phase histograms" for each reaction have remarkably simple properties in one choice of optimal frame; the phases tend to be integer multiples of 90°, within existing uncertainties. A two-component model for πN is presented that reproduces the striking pattern of phases and its generalization is discussed.

  10. Measurements of acoustic pressure at high amplitudes and intensities

    NASA Astrophysics Data System (ADS)

    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.

  11. Amplitude tests of direct channel resonances: the dibaryon

    SciTech Connect

    Goldstein, G.R.; Moravcsik, M.J.; Arash, F.

    1984-02-01

    A recently formulated polarization amplitude test for the existence of one-particle-exchange mechanisms is modified to deal with direct-channel resonances. The results are applied to proton-proton elastic scattering at and around 800 MeV to test the suggested existence of a dibaryon resonance. This test is sensitive to somewhat different circumstances and parameters than the methods used in the past to find dibaryon resonances. The evidence, on the basis of the SAID data set, is negative for a resonance in any singlet partial wave, but is tantalizingly subliminal for a /sup 3/F/sub 3/ resonance. 7 refs., 4 figs.

  12. Transition Distribution Amplitudes for γ⋆γ collisions

    NASA Astrophysics Data System (ADS)

    Lansberg, J. P.; Pire, B.; Szymanowski, L.

    2008-11-01

    We study the exclusive production of ππ and ρπ in hard γ⋆γ scattering in the forward kinematical region where the virtuality of one photon provides us with a hard scale in the process. The newly introduced concept of Transition Distribution Amplitudes (TDA) is used to perform a QCD calculation of these reactions thanks to two simple models for TDAs. The sizable cross sections for ρπ and ππ production may be tested at intense electron-positron colliders such as CLEO and B factories (Belle and BABAR).

  13. Amplitude-masked photoacoustic wavefront shaping and application in flowmetry

    PubMed Central

    Tay, Jian Wei; Liang, Jinyang; Wang, Lihong V.

    2014-01-01

    Optical-resolution photoacoustic flowmetry allows non-invasive single-cell flow measurements. However, its operational depth is limited by optical diffusion, which prevents focusing beyond shallow depths in scattering media, as well as reducing the measurement signal-to-noise ratio (SNR). To overcome this limitation, we used binary-amplitude wavefront shaping to enhance light focusing in the presence of scattering. Here, the transmission modes that contributed constructively to the intensity at the optical focus were identified and selectively illuminated, resulting in a 14-fold intensity increase and a corresponding increase in SNR. This technique can potentially extend the operational depth of optical-resolution photoacoustic flowmetry beyond 1 mm in tissue. PMID:25360912

  14. BFKL Pomeron and production amplitudes in N = 4 SUSY

    SciTech Connect

    Lipatov, L. N.

    2009-05-14

    Theoretical approaches to the problem of the high energy hadron-hadron scattering in the Regge kinematics are reviewed. It is shown, that the gluon in QCD is reggeized and the Pomeron is a two gluon composite state. Further, the equation for the multi-gluon composite states is integrable at N{sub c}{yields}{infinity}. Due to the AdS/CFT correspondence in N = 4 SUSY the BFKL Pomeron is equivalent to the reggeized graviton. The important properties of the maximal transcendentality and integrability are realized in this model. Multi-gluon scattering amplitudes are investigated in the Regge limit. The BDS ansatz for them is not valid beyond one loop due to the presence of the Mandelstam cuts. The hamiltonian for the corresonding reggeon states coincides with the hamiltonian of an integrable open Heisenberg spin chain.

  15. Phase diagram for passive electromagnetic scatterers.

    PubMed

    Lee, Jeng Yi; Lee, Ray-Kuang

    2016-03-21

    With the conservation of power, a phase diagram defined by amplitude square and phase of scattering coefficients for each spherical harmonic channel is introduced as a universal map for any passive electromagnetic scatterers. Physically allowable solutions for scattering coefficients in this diagram clearly show power competitions among scattering and absorption. It also illustrates a variety of exotic scattering or absorption phenomena, from resonant scattering, invisible cloaking, to coherent perfect absorber. With electrically small core-shell scatterers as an example, we demonstrate a systematic method to design field-controllable structures based on the allowed trajectories in this diagram. The proposed phase diagram and inverse design can provide tools to design functional electromagnetic devices. PMID:27136839

  16. Scattering Solutions of Bethe-Salpeter Equation in Minkowski and Euclidean Spaces

    NASA Astrophysics Data System (ADS)

    Carbonell, J.; Karmanov, V. A.

    2016-07-01

    We shortly review different methods to obtain the scattering solutions of the Bethe-Salpeter equation in Minkowski space. We emphasize the possibility to obtain the zero energy observables in terms of the Euclidean scattering amplitude.

  17. Scattering Solutions of Bethe-Salpeter Equation in Minkowski and Euclidean Spaces

    NASA Astrophysics Data System (ADS)

    Carbonell, J.; Karmanov, V. A.

    2016-06-01

    We shortly review different methods to obtain the scattering solutions of the Bethe-Salpeter equation in Minkowski space. We emphasize the possibility to obtain the zero energy observables in terms of the Euclidean scattering amplitude.

  18. Scattering of sound waves by a compressible vortex

    NASA Technical Reports Server (NTRS)

    Colonius, Tim; Lele, Sanjiva K.; Moin, Parviz

    1991-01-01

    Scattering of plane sound waves by a compressible vortex is investigated by direct computation of the two-dimensional Navier-Stokes equations. Nonreflecting boundary conditions are utilized, and their accuracy is established by comparing results on different sized domains. Scattered waves are directly measured from the computations. The resulting amplitude and directivity pattern of the scattered waves is discussed, and compared to various theoretical predictions. For compact vortices (zero circulation), the scattered waves directly computed are in good agreement with predictions based on an acoustic analogy. Strong scattering at about + or - 30 degrees from the direction of incident wave propagation is observed. Back scattering is an order of magnitude smaller than forward scattering. For vortices with finite circulation refraction of the sound by the mean flow field outside the vortex core is found to be important in determining the amplitude and directivity of the scattered wave field.

  19. Coupled-channel scattering on a torus

    SciTech Connect

    Guo, Peng; Dudek, Jozef Jon; Edwards, Robert G.; Szczepaniak, Adam Pawel

    2013-07-01

    Based on the Hamiltonian formalism approach, a generalized Luscher's formula for two particle scattering in both the elastic and coupled-channel cases in moving frames is derived from a relativistic Lippmann-Schwinger equation. Some strategies for extracting scattering amplitudes for a coupled-channel system from the discrete finite-volume spectrum are discussed and illustrated with a toy model of two-channel resonant scattering. This formalism will, in the near future, be used to extract information about hadron scattering from lattice QCD computations.

  20. A complete two-loop, five-gluon helicity amplitude in Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Badger, Simon; Mogull, Gustav; Ochirov, Alexander; O'Connell, Donal

    2015-10-01

    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.

  1. Optical scattering methods applicable to drops and bubbles

    NASA Technical Reports Server (NTRS)

    Marston, Philip L.

    1990-01-01

    An overview of optical scattering properties of drops and bubbles is presented. The properties lead to unconventional methods for optically monitoring the size or shape of a scatterer and are applicable to acoustically levitated objects. Several of the methods are applicable to the detection and measurement of small amplitude oscillations. Relevant optical phenomena include: (1) rainbows; (2) diffraction catastrophes from spheroids; (3) critical angle scattering; (4) effects of coatings; (5) glory scattering; and (6) optical levitation.

  2. Toward improving global attenuation models: Interpreting surface-wave amplitudes with approximate theories

    NASA Astrophysics Data System (ADS)

    Dalton, C. A.; Hjorleifsdottir, V.; Ekstrom, G.

    2011-12-01

    Surface-wave amplitudes provide the primary constraint on upper-mantle anelastic structure and are also sensitive to small-scale elastic structure through focusing effects. However, the use of amplitudes for seismic imaging presents several challenges. One, amplitudes are affected not only by propagation through anelastic and elastic heterogeneity but also by uncertainty in the source excitation, local receiver structure, and instrument response. Two, accounting for focusing and defocusing effects, which is important if amplitudes are to be used to study anelasticity, depends considerably on the chosen theoretical treatment. Three, multiple scattering of seismic energy by elastic heterogeneity can be mapped into attenuation, especially at high frequencies. With the objective of improving our ability to image mantle seismic attenuation using real amplitude observations, we investigate how approximations in the theoretical treatment of wave excitation and propagation influence the interpretation of amplitudes. We use a spectral-element wave-propagation solver (SPECFEM3D_GLOBE) to generate accurate seismograms for global Earth models containing one-dimensional attenuation structure and three-dimensional variations in seismic velocity. The seismograms are calculated for 42 realistically distributed earthquakes. Fundamental-mode Rayleigh wave amplitudes in the period range 50--200 seconds are measured using the approach of Ekström et al. (1997), for which PREM is the assumed Earth model. We show that using the appropriate local seismic structure at the source and receiver instead of PREM has a non-negligible effect on the amplitudes and improves their interpretation. The amplitudes due to focusing and defocusing effects are predicted for great-circle ray theory, exact ray theory (JWKB theory), and finite-frequency theory. We assess the ability of each theory to predict amplitudes that agree with those measured from the SPECFEM synthetics for an Earth model that

  3. S-duality and helicity amplitudes

    NASA Astrophysics Data System (ADS)

    Colwell, Kitran; Terning, John

    2016-03-01

    We examine interacting Abelian theories at low energies and show that holomorphically normalized photon helicity amplitudes transform into dual amplitudes under SL(2, {Z} ) as modular forms with weights that depend on the number of positive and negative helicity photons and on the number of internal photon lines. Moreover, canonically normalized helicity amplitudes transform by a phase, so that even though the amplitudes are not duality invariant, their squares are duality invariant. We explicitly verify the duality transformation at one loop by comparing the amplitudes in the case of an electron and the dyon that is its SL(2, {Z} ) image, and extend the invariance of squared amplitudes order by order in perturbation theory. We demonstrate that S-duality is a property of all low-energy effective Abelian theories with electric and/or magnetic charges and see how the duality generically breaks down at high energies.

  4. Gravity and Yang-Mills amplitude relations

    SciTech Connect

    Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Soendergaard, Thomas; FengBo

    2010-11-15

    Using only general features of the S matrix and quantum field theory, we prove by induction the Kawai-Lewellen-Tye relations that link products of gauge theory amplitudes to gravity amplitudes at tree level. As a bonus of our analysis, we provide a novel and more symmetric form of these relations. We also establish an infinite tower of new identities between amplitudes in gauge theories.

  5. Minimal Basis for Gauge Theory Amplitudes

    SciTech Connect

    Bjerrum-Bohr, N. E. J.; Damgaard, Poul H.; Vanhove, Pierre

    2009-10-16

    Identities based on monodromy for integrations in string theory are used to derive relations between different color-ordered tree-level amplitudes in both bosonic and supersymmetric string theory. These relations imply that the color-ordered tree-level n-point gauge theory amplitudes can be expanded in a minimal basis of (n-3)exclamation amplitudes. This result holds for any choice of polarizations of the external states and in any number of dimensions.

  6. Cascaded phase-preserving multilevel amplitude regeneration.

    PubMed

    Roethlingshoefer, Tobias; Onishchukov, Georgy; Schmauss, Bernhard; Leuchs, Gerd

    2014-12-29

    The performance of cascaded in-line phase-preserving amplitude regeneration using nonlinear amplifying loop mirrors has been studied in numerical simulations. As an example of a spectrally efficient modulation format with two amplitude states and multiple phase states, the regeneration performance of a star-16QAM format, basically an 8PSK format with two amplitude levels, was evaluated. An increased robustness against amplified spontaneous emission and nonlinear phase noise was observed resulting in a significantly increased transmission distance. PMID:25607142

  7. Discontinuities of multi-Regge amplitudes

    NASA Astrophysics Data System (ADS)

    Fadin, V. S.

    2015-04-01

    In the BFKL approach, discontinuities of multiple production amplitudes in invariant masses of produced particles are discussed. It turns out that they are in evident contradiction with the BDS ansatz for n-gluon amplitudes in the planar N = 4 SYM at n ≥ 6. An explicit expression for the NLO discontinuity of the two-to-four amplitude in the invariant mass of two produced gluons is is presented.

  8. Two-photon exchange in electron-trinucleon elastic scattering

    NASA Astrophysics Data System (ADS)

    Kobushkin, A. P.; Timoshenko, Ju. V.

    2013-10-01

    We discuss two-photon exchange (TPE) in elastic electron scattering off the trinucleon systems, 3He and 3H. The calculations are done in the semirelativistic approximation with the trinucleon wave functions obtained with the Paris and CD-Bonn nucleon-nucleon potentials. An applicability area of the model is wide enough and includes the main part of kinematical domain where experimental data exist. All three TPE amplitudes (generalized form factors) for electron 3He elastic scattering are calculated. We find that the TPE amplitudes are a few times more significant in the scattering of electrons off 3He then in the electron-proton scattering.

  9. Wilson lines and gauge invariant off-shell amplitudes

    NASA Astrophysics Data System (ADS)

    Kotko, Piotr

    2014-07-01

    We study matrix elements of Fourier-transformed straight infinite Wilson lines as a way to calculate gauge invariant tree-level amplitudes with off-shell gluons. The off-shell gluons are assigned "polarization vectors" which (in the Feynman gauge) are transverse to their off-shell momenta and define the direction of the corresponding Wilson line operators. The infinite Wilson lines are first regularized to prove the correctness of the method. We have implemented the method in a computer FORM program that can calculate gluonic matrix elements of Wilson line operators automatically. In addition we formulate the Feynman rules that are convenient in certain applications, e.g. proving the Ward identities. Using both the program and the Feynman rules we calculate a few examples, in particular the matrix elements corresponding to gauge invariant g * g * g * g and g * g * g * g * g processes. An immediate application of the approach is in the high energy scattering, as in a special kinematic setup our results reduce to the form directly related to Lipatov's vertices. Thus the results we present can be directly transformed into Lipatov's vertices, in particular into RRRP and RRRRP vertices with arbitrary "orientation" of reggeized gluons. Since the formulation itself is not restricted to high-energy scattering, we also apply the method to a decomposition of an ordinary on-shell amplitude into a set of gauge invariant objects.

  10. Born expansions for charged particle scattering

    SciTech Connect

    Macek, J.H. Oak Ridge National Lab., TN ); Barrachina, R.O. . Centro Atomico Bariloche)

    1989-01-01

    High-order terms in Born expansions of scattering amplitudes in powers of charge are frequently divergent when long-range Coulomb interactions are present asymptotically. Expansions which are free from these logarithmic divergences have been constructed recently. We illustrate these expansions with the simplest example, namely the non-relativistic Rutherford scattering of two charged particles. This approach represents an adequate framework for the calculation of transition amplitudes and a comprehensive starting point for the development of consistent perturbation approximations in multi-channel descriptions of strongly interacting atomic systems. 17 refs.

  11. Three applications of a bonus relation for gravity amplitudes

    NASA Astrophysics Data System (ADS)

    Spradlin, Marcus; Volovich, Anastasia; Wen, Congkao

    2009-04-01

    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.

  12. Resonances in pi-K scattering

    SciTech Connect

    Wilson, David J.

    2014-06-23

    We have obtained clear signals of resonances in coupled-channel pi K - eta K scattering. Using distillation and a large basis of operators we are able to extract a precise spectrum of energy levels using the variational method. These energies are analysed using inelastic extensions of the Luescher method to obtain scattering amplitudes that clearly describe S, P and D wave resonances, corresponding to the physical K_0^*(1430), the K^*(892) and the K_2^*(1430).

  13. On a Model-Independent Representation for the Real Part of the Elastic Hadron Amplitude

    SciTech Connect

    Fagundes, D. A.; Menon, M. J.

    2010-11-12

    The applicability of Martin's Real Part Formula in model-independent analysis of elastic proton-proton scattering is discussed. Good reproduction of all the differential cross section data at high-energies (19.4-62.5 GeV) is obtained through an empirical parametrization for the imaginary part of the amplitude and the use of a representation for the Martin's formula without the scaling property. According to the fit results, the scattering amplitude is predominantly imaginary, except at the dip region. One zero (change of sign) is observed in the imaginary part of the amplitude (dip region) and two zeros in the real part (at small and intermediate values of the momentum transfer).

  14. Separating Scattering from Intrinsic Attenuation

    NASA Astrophysics Data System (ADS)

    van Wijk, K.; Scales, J. A.

    2003-12-01

    The subsurface appears disordered at all length-scales. Therefore, wave propatation at seismic or ultrasonic frequencies is subject to complicated scatterings. A pulse propagating in the subsurface loses energy at each scattering off an impedance contrast, but also decreases in amplitude as the impulse interacts with fluids in the rock. We call the latter non-elastic effect "intrinsic Q", while the former is "scattering Q". It is often the fluids in the rocks that are of interest, but conventional reflection and transmission of the incident pulse only cannot deceipher the individual components of Q due to scattering and fluid movement in the pore-space. We present an approach that can unravel these two mechanisms, allowing a separate estimate of absorption. This method treats the propagation of the average intensity in the framework of radiative transfer (RT); the arrival of (what is left of) the incident pulse is modeled as the coherent energy, whereas the later arriving multiply scattered events form the incoherent intensity. The coherent pulse decays exponentially due to a combination of scattering and absorption, and so does the incoherent intensity. However, multiple scattering can re-direct energy back to the receiver, supplying a gain-term at later times that makes up the incoherent intensity. Strictly speaking, one can invert for scattering and absorption from the intensity at late times only, often modeled with the late-time equivalent of RT, diffusion. However, we will show that fitting both early- and late-time signal with RT constrains absorption and scattering constants more rigorously. These ideas are illustrated by laboratory and sonic-logging measurements.

  15. Thermal cracking and amplitude dependent attenuation

    SciTech Connect

    Johnston, D.H.; Toksoez, M.N.

    1980-02-10

    The role of crack and grain boundary contacts in determining seismic wave attenuation in rock is investigated by examining Q as a function of thermal cycling (cracking) and wave strain amplitude. Q values are obtained using a longitudinal resonant bar technique in the 10- to 20-kHz range for maximum strain amplitudes varying from roughly 10/sup -8/ to 10/sup -5/. The samples studied include the Berea and Navajo sandstones, Plexiglas, Westerly granite, Solenhofen limestone, and Frederick diabase, the latter two relatively crack free in their virgin state. Measurements were made at room temperature and pressure in air. Q values for both sandstones are constant at low strains (<10/sup -6/) but decrease rapidly with amplitude at higher strains. There is no hysteresis of Q with amplitude. Q values for Plexiglas show no indication of amplitude dependent behavior. The granite, limestone, and diabase are thermally cycled at both fast and slow heating rates in order to induce cracking. Samples slowly cycled at 400/sup 0/C show a marked increase in Q that cannot be entirely explained by outgassing of volatiles. Cycling may also widen thin cracks and grain boundaries, reducing contact areas. Samples heated beyond 400/sup 0/C, or rapidly heated, result in generally decreasing Q values. The amplitude dependence of Q is found to be coupled to the effects of thermal cycling. For rock slowly cycled 400)C or less, the transition from low-amplitude contant Q to high-amplitude variable Q behavior decreases to lower amplitudes as a function of maximum temperature. Above 400/sup 0/C, and possibly in th rapidly heated samples also, the transition moves to higher amplitudes.

  16. Decoherence due to elastic Rayleigh scattering

    NASA Astrophysics Data System (ADS)

    Uys, H.; Biercuk, M. J.; Vandevender, A. P.; Ospelkaus, C.; Bollinger, J. J.; Meiser, D.

    2010-03-01

    Off-resonant light scattering (spontaneous emission) is an important source of decoherence in many coherent control experiments. Typically one focuses on the effects of Raman scattering, in which an atomic state is changed by a single scattering event. We present theoretical and experimental studies of the decoherence of hyperfine ground-state superpositions due to elastic Rayleigh scattering of off-resonant light. By a master equation technique we show that for a two-level superposition the elastic decoherence rate is the square of the difference between the two elastic scattering amplitudes. Thus, if the light detunings for the two states have opposite sign, the amplitudes interfere constructively and can result in a large decoherence rate. We calculate and measure the total decoherence rate for a superposition state of the valence electron spin in the ground state of ^9Be^+ in a 4.5 T magnetic field. We find that for large (˜20 GHz) detunings, decoherence due to elastic Rayleigh scattering can be 5 times larger than decoherence due to Raman scattering. This is in contrast with workootnotetextR. Ozeri, et al., PRL 95, 030403 (2005) at low magnetic field where decoherence was dominated by Raman scattering.

  17. Cross correlation analysis of plasma perturbation in amplitude modulated reactive dusty plasmas

    NASA Astrophysics Data System (ADS)

    Ito, Teppei; Soejima, Masahiro; Yamashita, Daisuke; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu; Kobayashi, Tatsuya; Inagaki, Shigeru

    2015-09-01

    Interactions between plasmas and nano-interface are one of the most important issues in plasma processing. We have studied effects of plasma perturbation on growth of nanoparticles in amplitude modulated reactive dusty plasmas and have clarified that amplitude modulation (AM) leads to suppression of growth of nanoparticles [1]. Here we report results of cross correlation analysis of time evolution of laser light scattering intensity from nanoparticles in reactive plasmas. Experiments were carried out using a capacitively-coupled rf discharge reactor with a two-dimensional laser light scattering (LLS) system. We employed Ar +DM-DMOS discharge plasmas to generate nanoparticles. The peaks at higher harmonics and subharmonics in spectra of laser light scattering intensity were detected, suggesting nonlinear coupling between plasma and nanoparticle amount. We found high cross correlation t between waves at AM frequency and its higher harmonics. Namely, perturbation at fAM closely correlates with those at higher harmonics.

  18. Helicity amplitudes on the light-front

    NASA Astrophysics Data System (ADS)

    Cruz Santiago, Christian A.

    Significant progress has been made recently in the field of helicity amplitudes. Currently there are on-shell recursion relations with shifted complex momenta, geometric interpretations of amplitudes and gauge invariant off-shell amplitudes. All this points to helicity amplitudes being a rich field with much more to say. In this work we take initial steps in understanding amplitudes through the light-front formalism for the first time. We begin by looking at crossing symmetry. In the light-front it is not obvious that crossing symmetry should be present as there are non-local energy denominators that mix energies of different states. Nevertheless, we develop a systematic approach to relate, for example, 1 → N gluon processes to 2 → N -- 1 processes. Using this method, we give a perturbative proof of crossing symmetry on the light-front. One important caveat is that the proof requires the amplitudes to be on-shell. We also saw that the analytic continuation from outgoing to incoming particle produces a phase that's dependent on the choice of polarizations. Next, we reproduce the Parke-Taylor amplitudes. For this purpose we found a recursion relation for an off-shell object called the fragmentation function. This recursion relies on the factorization property of the fragmentation functions, and it becomes apparent that this recursion is the light-front analog of the Berends-Giele recursion relation. We also found this object's connection to off-shell and on-shell amplitudes. The solution for the off-shell amplitude, which does reproduce the Parke-Taylor amplitudes in the on-shell limit, turns out to be very interesting. It can be written as a linear sum of off-shell objects with the same structure as MHV amplitudes. Finally, we look at the Wilson line approach to generate gauge invariant off-shell amplitudes. It turns out that the exact same recursion relation appears on both frameworks, thereby providing the interpretation that our recursion relation has it

  19. Location of Tremor and Long Period Events Using Seismic Amplitudes

    NASA Astrophysics Data System (ADS)

    Battaglia, J.; Battaglia, J.; Ferrazzini, V.; Okubo, P. G.

    2001-12-01

    Tremor and Long Period (LP) events are of particular interest for understanding the behavior of volcanoes as it is assumed that they directly involve fluids in their source mechanisms. However, those events are usually difficult or impossible to locate using traditional arrival times methods, because of their emergent onsets or because they are stationary for a long time. While techniques have been proposed using seismic arrays, this task remains problematic using data from classical short period volcano monitoring networks. A method based on the use of seismic amplitudes was developed on the Piton de la Fournaise (Réunion island) for locating tremor, LP events or rockfalls. For each event, seismic amplitudes are corrected for the site effects at each station using coda amplification factors. The spatial amplitude distributions are usually smooth and coherent, and the decay of the amplitude as a function of distance can be used to locate their source. In Réunion, this method was applied to locate the source(s) of eruption tremor. Those sources are usually found at shallow depth and close to the eruptive vents. An application of this characteristic is the possibility of using eruption tremor for locating the eruptive fissures at the beginning of eruptions. We apply this technique in Hawaii for locating LP events at Kilauea volcano. We calculated coda amplification factors for all stations of the network, and coherent and smooth amplitude distributions are also obtained after correcting for the site effect. We located about 150 events which occurred in January 1998 during an increased phase of LP activity. This seismicity, which peaked on January 15, was related to a surge of magma that reached the Pu`u`O`o vent on January 14, following a rapid inflation of Kilauea's summit. The use of the amplitude method provides a new image of the LP activity. The events appear to cluster in a single group, while they are much more scattered when located using arrival times

  20. Elliptic scattering equations

    NASA Astrophysics Data System (ADS)

    Cardona, Carlos; Gomez, Humberto

    2016-06-01

    Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a mathbb{C}{P}^2 space. We show that for the simplest integrand, namely the n - gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ-algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.

  1. A link representation for gravity amplitudes

    NASA Astrophysics Data System (ADS)

    He, Song

    2013-10-01

    We derive a link representation for all tree amplitudes in supergravity, from a recent conjecture by Cachazo and Skinner. The new formula explicitly writes amplitudes as contour integrals over constrained link variables, with an integrand naturally expressed in terms of determinants, or equivalently tree diagrams. Important symmetries of the amplitude, such as supersymmetry, parity and (partial) permutation invariance, are kept manifest in the formulation. We also comment on rewriting the formula in a GL( k)-invariant manner, which may serve as a starting point for the generalization to possible Grassmannian contour integrals.

  2. Amplitude- and rise-time-compensated filters

    DOEpatents

    Nowlin, Charles H.

    1984-01-01

    An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.

  3. Form factor and boundary contribution of amplitude

    NASA Astrophysics Data System (ADS)

    Huang, Rijun; Jin, Qingjun; Feng, Bo

    2016-06-01

    The boundary contribution of an amplitude in the BCFW recursion relation can be considered as a form factor involving boundary operator and unshifted particles. At the tree-level, we show that by suitable construction of Lagrangian, one can relate the leading order term of boundary operators to some composite operators of mathcal{N} = 4 superYang-Mills theory, then the computation of form factors is translated to the computation of amplitudes. We compute the form factors of these composite operators through the computation of corresponding double trace amplitudes.

  4. Patterns of high energy massive string scatterings in the Regge regime

    NASA Astrophysics Data System (ADS)

    Ko, Sheng-Lan; Lee, Jen-Chi; Yang, Yi

    2009-06-01

    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 subleading 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.

  5. Real Compton scattering via color dipoles

    SciTech Connect

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2009-09-01

    We study the photoabsorption reaction and real Compton scattering within the color dipole model. We rely on a photon wave function derived in the instanton-vacuum model and on the energy-dependent phenomenological elastic dipole amplitude. Data for the photoabsorption cross section at high energies agree with our parameter-free calculations. We also provide predictions for the differential real Compton scattering cross section. Although no data for small angle Compton scattering are available so far, this process can be measured in ultraperipheral hadronic and nuclear collisions at the LHC.

  6. The isomonodromy method for black hole scattering

    SciTech Connect

    Carneiro da Cunha, Bruno; Novaes, Fábio

    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.

  7. Asymptotic behaviour of backward elastic scattering

    NASA Astrophysics Data System (ADS)

    Germond, J. F.; Lombard, R. J.

    1988-05-01

    We discuss a compact formula proposed by Dias de Deus and Pimenta for the asymptotic value of the elastic scattering amplitude at backward angles. Improvements and generalization are obtained by means of the saddle-point method which corroborate old calculations by Serber.

  8. Shadowing in Compton scattering on nuclei

    SciTech Connect

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2010-05-01

    We evaluate the shadowing effect in deeply virtual and real Compton scattering on nuclei in the framework of the color dipole model. We rely on the soft photon wave function derived in the instanton vacuum model and employ the impact parameter dependent phenomenological elastic dipole amplitude. Both the effects of quark and the gluon shadowing are taken into account.

  9. Constant-amplitude, frequency- independent phase shifter

    NASA Technical Reports Server (NTRS)

    Deboo, G. J.

    1971-01-01

    Electronic circuit using operational amplifiers provides output with constant phase shift amplitude, with respect to sinusoidal input, over wide range of frequencies. New circuit includes field effect transistor, Q, operational amplifiers, A1 and A2, and phase detector.

  10. Amplitude dynamics favors synchronization in complex networks

    PubMed Central

    Gambuzza, Lucia Valentina; Gómez-Gardeñes, Jesus; Frasca, Mattia

    2016-01-01

    In this paper we study phase synchronization in random complex networks of coupled periodic oscillators. In particular, we show that, when amplitude dynamics is not negligible, phase synchronization may be enhanced. To illustrate this, we compare the behavior of heterogeneous units with both amplitude and phase dynamics and pure (Kuramoto) phase oscillators. We find that in small network motifs the behavior crucially depends on the topology and on the node frequency distribution. Surprisingly, the microscopic structures for which the amplitude dynamics improves synchronization are those that are statistically more abundant in random complex networks. Thus, amplitude dynamics leads to a general lowering of the synchronization threshold in arbitrary random topologies. Finally, we show that this synchronization enhancement is generic of oscillators close to Hopf bifurcations. To this aim we consider coupled FitzHugh-Nagumo units modeling neuron dynamics. PMID:27108847

  11. Lorentz violation correction to the Aharonov-Bohm scattering

    NASA Astrophysics Data System (ADS)

    Anacleto, M. A.

    2015-10-01

    In this paper, using a (2 +1 )-dimensional field theory approach, we study the Aharonov-Bohm (AB) scattering with Lorentz symmetry breaking. We obtain the modified scattering amplitude to the AB effect due to the small Lorentz violation correction in the breaking parameter and prove that up to one loop the model is free from ultraviolet divergences.

  12. Symmetry considerations in the scattering of identical composite bodies

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W.; Deutchman, P. A.

    1986-01-01

    Previous studies of the interactions between composite particles were extended to the case in which the composites are identical. The form of the total interaction potential matrix elements was obtained, and guidelines for their explicit evaluation were given. For the case of elastic scattering of identical composites, the matrix element approach was shown to be equivalent to the scattering amplitude method.

  13. Azimuthal decorrelation of forward jets in deep inelastic scattering

    SciTech Connect

    Sabio Vera, Agustin; Schwennsen, Florian

    2008-01-01

    We study the azimuthal angle decorrelation of forward jets in deep inelastic scattering. We make predictions for this observable at HERA describing the high energy limit of the relevant scattering amplitudes with quasi-multi-Regge kinematics together with a collinearly-improved evolution kernel for multiparton emissions.

  14. Seismic directional beamforming using cosine amplitude distribution

    NASA Astrophysics Data System (ADS)

    Jiang, T.; Xu, X.; Song, J.; Jia, H.; Ge, L.

    2013-12-01

    o improve the signal-to-noise ratio in seismic exploration, we studied the method of time domain seismic beam-forming based on receiver array (TSBBRA). TSBBRA is useful to extract reflected waves from some target layers and decrease noise from other direction. When noise is strong enough, the control parameter of the method of TSBBRA need to be increased. It means that we have to use more raw records to form a directional seismic record. Therefore, the signal energy in beam is much denser, and the beam becomes narrower accordingly. When the beam can not cover the receiver array, the signal-to-noise ratios in different traces are quite unbalanced and average quality of data probably is still quite low. Therefore, this paper proposes seismic directional beamforming using the cosine amplitude distribution (SDBCAD). SDBCAD can adjust seismic beam shape by introducing cosine amplitude distribution, an amplitude weighting method, in the procedure of beamforming. We studied cosine amplitude weighting function, analyzed the characteristics of uniform and cosine amplitude distribution in beamforming, and compared directivity of beams from the two kind of amplitude pattern. It shows that the main beam of cosine-weighted amplitude is different from uniform distribution. The coverage of main beam from SDBCAD is wider than uniform amplitude, and the width of beam is varied with different number of cosine order. So we simulated the seismic raw record, and used TSBBRA and SDBCAD to process simulated data at the receiving array. The results show that SDBCAD can broaden directional beam, and the main beam from SDBCAD can cover the entire traces instead of partial coverage in TSBBRA. The average signal-to-noise ratio increased 0.2~4.5dB. It concludes that SDBCAD is competent to stretch beam reasonable, and it is useful to boost signal-to-noise ratio when beam from TSBBRA is too narrow to illuminate receiver array properly. Updated results will be presented at the meeting.

  15. Nucleon Distribution Amplitudes from Lattice QCD

    SciTech Connect

    Goeckeler, Meinulf; Kaltenbrunner, Thomas; Warkentin, Nikolaus; Horsley, Roger; Zanotti, James M.; Nakamura, Yoshifumi; Pleiter, Dirk; Schierholz, Gerrit; Rakow, Paul E. L.; Schaefer, Andreas; Stueben, Hinnerk

    2008-09-12

    We calculate low moments of the leading-twist and next-to-leading-twist nucleon distribution amplitudes on the lattice using two flavors of clover fermions. The results are presented in the MS scheme at a scale of 2 GeV and can be immediately applied in phenomenological studies. We find that the deviation of the leading-twist nucleon distribution amplitude from its asymptotic form is less pronounced than sometimes claimed in the literature.

  16. The amplitude of quantum field theory

    SciTech Connect

    Medvedev, B.V. ); Pavlov, V.P.; Polivanov, M.K. ); Sukhanov, A.D. )

    1989-05-01

    General properties of the transition amplitude in axiomatic quantum field theory are discussed. Bogolyubov's axiomatic method is chosen as the variant of the theory. The axioms of this method are analyzed. In particular, the significance of the off-shell extension and of the various forms of the causality condition are examined. A complete proof is given of the existence of a single analytic function whose boundary values are the amplitudes of all channels of a process with given particle number.

  17. Twistor-strings and gravity tree amplitudes

    NASA Astrophysics Data System (ADS)

    Adamo, Tim; Mason, Lionel

    2013-04-01

    Recently we discussed how Einstein supergravity tree amplitudes might be obtained from the original Witten and Berkovits twistor-string theory when external conformal gravitons are restricted to be Einstein gravitons. Here we obtain a more systematic understanding of the relationship between conformal and Einstein gravity amplitudes in that twistor-string theory. We show that although it does not in general yield Einstein amplitudes, we can nevertheless obtain some partial twistor-string interpretation of the remarkable formulae recently been found by Hodges and generalized to all tree amplitudes by Cachazo and Skinner. The Hodges matrix and its higher degree generalizations encode the world sheet correlators of the twistor string. These matrices control both Einstein amplitudes and those of the conformal gravity arising from the Witten and Berkovits twistor-string. Amplitudes in the latter case arise from products of the diagonal elements of the generalized Hodges matrices and reduced determinants give the former. The reduced determinants arise if the contractions in the worldsheet correlator are restricted to form connected trees at MHV. The (generalized) Hodges matrices arise as weighted Laplacian matrices for the graph of possible contractions in the correlators and the reduced determinants of these weighted Laplacian matrices give the sum of the connected tree contributions by an extension of the matrix-tree theorem.

  18. Multiple scattering of scalar waves by point scatterers in one dimension. II

    SciTech Connect

    Haacke, E.M.; Foldy, L.L.

    1981-04-01

    In the first paper of this series, we studied the problem of scattering in one dimension of a wave interacting with n randomly distributed pointlike scatterers by delta-function potentials. Averaging the wave function for a constant amplitude transmitted wave over an ensemble of configurations allowed us to obtain an analytic expression for the optical potential which, in certain limits, took the form of the scatterer density (rho) times the scattering strength (GAMMA). We examine the domain in parameter space where rhoGAMMA can be regarded as a good approximation to the optical potential for both this problem and the problem in which the amplitude of the incident wave is constant. The conditions on the parameters are found to be the same in both the preceding problems. We then supplement rhoGAMMA by an appropriate imaginary part. The wave function predicted from this effective potential approximation to the optical potential is in good agreement with that from the exact solution.

  19. The scattering of fast nucleons from nuclei

    SciTech Connect

    Kerman, A. K.; McManus, H.; Thaler, R. M.

    2000-04-10

    The formal theory of the scattering of high-energy nucleons by nuclei is developed in terms of the nucleon nucleon scattering amplitude. The most important approximations necessary to make numerical calculation feasible are then examined. The optical model potential is derived on this basis and compared with the optical model parameters found from experiment. The elastic scattering and polarization of nucleons from light nuclei is predicted and compared with experiment. The effect of nuclear correlations is discussed. The polarization of inelastically scattered nucleons is discussed and predictions compared with experiments. To within the validity of the approximations the experimental data on the scattering of nucleons from nuclei at energies above {approx}100 Mev appears to be consistent with the theory. (c) 2000 Academic Press, Inc.

  20. Ultrasound transmission attenuation tomography using energy-scaled amplitude ratios

    NASA Astrophysics Data System (ADS)

    Chen, Ting; Shin, Junseob; Huang, Lianjie

    2016-04-01

    Ultrasound attenuation of breast tumors is related to their types and pathological states, and can be used to detect and characterize breast cancer. Particularly, ultrasound scattering attenuation can infer the margin properties of breast tumors. Ultrasound attenuation tomography quantitatively reconstructs the attenuation properties of the breast. Our synthetic-aperture breast ultrasound tomography system with two parallel transducer arrays records both ultrasound reflection and transmission signals. We develop an ultrasound attenuation tomography method using ultrasound energy-scaled amplitude decays of ultrasound transmission signals and conduct ultrasound attenuation tomography using a known sound-speed model. We apply our ultrasound transmission attenuation tomography method to a breast phantom dataset, and compare the ultrasound attenuation tomography results with conventional beamforming ultrasound images obtained using reflection signals. We show that ultrasound transmission attenuation tomography complements beamforming images in identifying breast lesions.

  1. Picosecond time-domain electromagnetic scattering from conducting cylinders

    NASA Astrophysics Data System (ADS)

    Robertson, W. M.; Kopcsay, G. V.; Arjavalingam, G.

    1991-12-01

    The microwave scattering properties of conducting cylinders are characterized by measuring their response to picosecond-duration electromagnetic pulses. The ultrafast electromagnetic transients are generated and detected with optoelectronically pulsed antennas. The time-domain response gives physical insight into the scattering process. In addition, Fourier analysis is used to obtain the frequency dependence of the scattered amplitude and phase from 15 to 140 GHz.

  2. VLF scattering from Red Sprites-Theory

    NASA Astrophysics Data System (ADS)

    Rodger, C. J.; Wait, J. R.; Dowden, R. L.

    1998-05-01

    A relatively simple model of Red Sprites as a set of conducting columns reproduces the radio physics properties of VLF sprites. The columnar structure of optical sprites is represented by thin vertical conducting columns (or `Spritelets') in free space, with dimensions taken from optical observations. The scattered field from a set of coupled Spritelets has a complex amplitude pattern which normally includes some deep minima reproducing the `perturbation shadows' seen in some experimental events. It is not uncommon for the back scattered amplitudes to be similar to those for forward scatter in the theoretical model, as in experimental reports. As some sprite events appear to have closely spaced Spritelets, the results presented here indicate that there will be a high degree of electrical shielding. This is an application of the theory presented by[Rodger et al. (1997a)].

  3. New optimal polynomial theory for NN-scattering

    SciTech Connect

    Rijken, T A; Signell, P

    1980-01-01

    A new optimal polynomial theory for nucleon-nucleon scattering is presented. For the first time in nucleon-nucleon scattering, the derivative amplitudes originally introduced by Fubini, Furlan, and Rosetti are applied. Based on the properties of these amplitudes we introduce K-matrix functions which have suitable analyticity properties as functions of cos theta, where theta is the center of mass scattering angle. The K-matrix functions enable introduction of a new set of functions for which the optimal mapping techniques of Cutkosky, Deo and Ciulli can be applied. Results are shown for proton-proton phase shift analyses at 210 and 330 MeV.

  4. Tectonic Tremor Source Amplitude in Northern Cascadia

    NASA Astrophysics Data System (ADS)

    Ulberg, C. W.; Creager, K. C.; Klaus, A. J.; Wech, A.

    2012-12-01

    Most studies of tectonic tremor have focused on tremor location and duration. We examine tremor source amplitude in northern Cascadia, and explore its importance in understanding the physical processes generating tremor and slow slip. In Cascadia, we observe a linear increase in tremor source amplitude during the approximately five-day initiation phase of episodic tremor and slip (ETS) events, apparently associated with a linear increase in the area where tremor is occurring. There is also mounting evidence that tremor amplitude during ETS events is strongly modulated by tidal stresses (e.g. Rubinstein et al, Science, 2008), including the most recent northern Cascadia ETS events of 2010 and 2011. This suggests a low coefficient of friction on the subduction interface. We will extend our existing amplitude catalog of the 2010 and 2011 Cascadia ETS events to include all of 2006 to 2012, incorporating multiple data sets and providing more insight into the spatial distribution of tremor, the initiation phase of ETS events, and tidal forcing of ETS and inter-ETS tremor. Tremor source amplitudes are estimated with a method similar to Maeda and Obara (JGR, 2009), using the proportional relationship between source amplitude and the root-mean square of band-limited (1.5 to 5.5 Hz) ground velocity for every 5-minute window. We use horizontal component seismograms from the CAFE (2006-2008) and Array of Arrays (2009-2011) experiments, as well as permanent PNSN stations. Tremor locations were determined using a waveform envelope cross-correlation method (Wech and Creager, GRL, 2008). We perform an inversion using these tremor locations and station ground velocities to determine the tremor source amplitude and station statics, taking into account geometric spreading and seismic attenuation.

  5. Multichannel 1 → 2 transition amplitudes in a finite volume

    SciTech Connect

    Briceno, Raul A.; Hansen, Maxwell T.; Walker-Loud, Andre

    2015-02-03

    We perform a model-independent, non-perturbative investigation of two-point and three-point finite-volume correlation functions in the energy regime where two-particle states can go on-shell. We study three-point functions involving a single incoming particle and an outgoing two-particle state, relevant, for example, for studies of meson decays (e.g., B⁰ → K*l⁺l⁻) or meson photo production (e.g., πγ* → ππ). We observe that, while the spectrum solely depends upon the on-shell scattering amplitude, the correlation functions also depend upon off-shell amplitudes. The main result of this work is a non-perturbative generalization of the Lellouch-Luscher formula relating matrix elements of currents in finite and infinite spatial volumes. We extend that work by considering a theory with multiple, strongly-coupled channels and by accommodating external currents which inject arbitrary four-momentum as well as arbitrary angular-momentum. The result is exact up to exponentially suppressed corrections governed by the pion mass times the box size. We also apply our master equation to various examples, including two processes mentioned above as well as examples where the final state is an admixture of two open channels.

  6. Involution-dependent constants and the cancellation of divergences in the 1-loop open string amplitude

    SciTech Connect

    Nagao, G.

    1987-12-01

    We recalculate the bosonic 1-loop open string scattering amplitude using the results of the bosonic 1-loop closed string amplitude. The results show explicitly how the cancellation of divergences depends upon of a set of involution-dependent constants which relate the torus to the cylinder and Moebius strip. Such a set of involution-dependent constants exists at each loop level and thus provides a means with which to study the cancellation of divergences and the connection between the world-sheet and internal symmetries. 14 refs., 3 figs.

  7. Minimal unitary (covariant) scattering theory

    SciTech Connect

    Lindesay, J.V.; Markevich, A.

    1983-06-01

    In the minimal three particle equations developed by Lindesay the two body input amplitude was an on shell relativistic generalization of the non-relativistic scattering model characterized by a single mass parameter ..mu.. which in the two body (m + m) system looks like an s-channel bound state (..mu.. < 2m) or virtual state (..mu.. > 2m). Using this driving term in covariant Faddeev equations generates a rich covariant and unitary three particle dynamics. However, the simplest way of writing the relativisitic generalization of the Faddeev equations can take the on shell Mandelstam parameter s = 4(q/sup 2/ + m/sup 2/), in terms of which the two particle input is expressed, to negative values in the range of integration required by the dynamics. This problem was met in the original treatment by multiplying the two particle input amplitude by THETA(s). This paper provides what we hope to be a more direct way of meeting the problem.

  8. A description of seismic amplitude techniques

    NASA Astrophysics Data System (ADS)

    Shadlow, James

    2014-02-01

    The acquisition of seismic data is a non-invasive technique used for determining the sub surface geology. Changes in lithology and fluid fill affect the seismic wavelet. Analysing seismic data for direct hydrocarbon indicators (DHIs), such as full stack amplitude anomalies, or amplitude variation with offset (AVO), can help a seismic interpreter relate the geophysical response to real geology and, more importantly, to distinguish the presence of hydrocarbons. Inversion is another commonly used technique that attempts to tie the seismic data back to the geology. Much has been written about these techniques, and attempting to gain an understanding on the theory and application of them by reading through various journals can be quite daunting. The purpose of this paper is to briefly outline DHI analysis, including full stack amplitude anomalies, AVO and inversion and show the relationship between all three. The equations presented have been included for completeness, but the reader can pass over the mathematical detail.

  9. Periodic amplitude variations in Jovian continuum radiation

    NASA Astrophysics Data System (ADS)

    Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.

    1986-12-01

    An analysis of periodic variations in the amplitude of continuum radiation near 3 kHz trapped in the Jovian magnetosphere shows structure with periods near both 5 and 10 horus. Contrary to a plausible initial idea, the continuum amplitudes are not organized by the position of the observer relative to the dense plasma sheet. Instead, there seem to be perferred orientations of system III longitude with respect to the direction to the sun which account for the peaks. This implies a clocklike modulation of the continuum radiation intensity as opposed to a searchlight effect. The importance of the dipole longitude solar wind alignment to the amplitude of the continuum radiation implies that the source region of the radiation is near the magnetopause and may indirectly tie the generation of the radio waves to the clocklike modulation of energetic electron fluxes from Jupiter.

  10. Cut-constructible part of QCD amplitudes

    SciTech Connect

    Britto, Ruth; Feng Bo; Mastrolia, Pierpaolo

    2006-05-15

    Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any particular helicity configurations. Loop momentum integration is reduced to a sequence of algebraic operations. We discuss the extraction of the residues at higher-order poles. Additionally, we offer concise algebraic formulas for expressing coefficients of three-mass triangle integrals. As an application, we compute all remaining coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon amplitudes.

  11. Perturbative type II amplitudes for BPS interactions

    NASA Astrophysics Data System (ADS)

    Basu, Anirban

    2016-02-01

    We consider the perturbative contributions to the {{ R }}4, {D}4{{ R }}4 and {D}6{{ R }}4 interactions in toroidally compactified type II string theory. These BPS interactions do not receive perturbative contributions beyond genus three. We derive Poisson equations satisfied by these moduli dependent string amplitudes. These T-duality invariant equations have eigenvalues that are completely determined by the structure of the integrands of the multi-loop amplitudes. The source terms are given by boundary terms of the moduli space of Riemann surfaces corresponding to both separating and non-separating nodes. These are determined directly from the string amplitudes, as well as from U-duality constraints and logarithmic divergences of maximal supergravity. We explicitly solve these Poisson equations in nine and eight-dimensions.

  12. On the frequency dependence and spatial coherence of PKP precursor amplitudes

    NASA Astrophysics Data System (ADS)

    Mancinelli, Nicholas; Shearer, Peter; Thomas, Christine

    2016-03-01

    Studies now agree that small-scale (˜10 km) weak (˜0.1%) velocity perturbations throughout the lowermost mantle generate the globally averaged amplitudes of 1 Hz precursors to the core phase, . The possible frequency dependence and spatial coherence of this scattered phase, however, has been given less attention. Using a large global data set of ˜150,000 PKP precursor recordings, we characterize the frequency dependence of PKP precursors at central frequencies ranging from 0.5 to 4 Hz. At greater frequencies, we observe more scattered energy (relative to the reference phase PKPdf), particularly at shorter ranges. We model this observation by invoking heterogeneity at length scales from 2 to 30 km. Amplitudes at 0.5 Hz, in particular, suggest the presence of more heterogeneity at scales >8 km than present in previously published models. Using a regional bootstrap approach, we identify large (>20°), spatially coherent regions of anomalously strong scattering beneath the West Pacific, Central/North America, and—to a lesser extent—East Africa. Finally, as proof of concept, we use array processing techniques to locate the origin of scattered energy observed in Southern California by the Anza and Southern California Seismic Networks. The energy appears to come primarily from out-of-plane scattering on the receiver side. We suggest that such improvised arrays can increase global coverage and may reveal whether a majority of precursor energy comes from localized heterogeneity in the lowermost mantle.

  13. Microstrip amplitude-weighted wilkinson power dividers

    NASA Astrophysics Data System (ADS)

    Huck, K. D.

    1986-03-01

    Unequal-split reactive power dividers were examined for use in forming amplitude tapers for microstrip array antennas. Circuits with power ratios of up to 5.0 between arms were constructed on Rexolite substrate, for operation at 4.0 GHz and 7.5 GHz. The 4.0 GHz circuits were very accurate in forming the correct amplitude ratio between outputs, and in maintaining phase balance between outputs. Of those circuits designed for 7.5 GHz, only those with split ratios less than 2.5 worked correctly. This report includes a review of the theory, measured results, and recommendations for improved power dividers.

  14. Dual amplitude pulse generator for radiation detectors

    DOEpatents

    Hoggan, Jerry M.; Kynaston, Ronnie L.; Johnson, Larry O.

    2001-01-01

    A pulsing circuit for producing an output signal having a high amplitude pulse and a low amplitude pulse may comprise a current source for providing a high current signal and a low current signal. A gate circuit connected to the current source includes a trigger signal input that is responsive to a first trigger signal and a second trigger signal. The first trigger signal causes the gate circuit to connect the high current signal to a pulse output terminal whereas the second trigger signal causes the gate circuit to connect the low current signal to the pulse output terminal.

  15. A Simple Discrete Model of Scattering in a Fluctuating Inhomogeneous Medium.

    ERIC Educational Resources Information Center

    West, Bruce J.

    1978-01-01

    Discusses scattering problems in continuous media, and presents a simple discrete model for scalar wave scattering from inhomogeneities on a lattice. Illustrates the relationships between the amplitude of the scattered wave and the characteristic function of the fluctuating motion of a point reflector in one dimension. (Author/GA)

  16. Landau retardation on the occurrence scattering time in quantum electron-hole plasmas

    NASA Astrophysics Data System (ADS)

    Hong, Woo-Pyo; Jung, Young-Dae

    2016-03-01

    The Landau damping effects on the occurrence scattering time in electron collisions are investigated in a quantum plasma composed of electrons and holes. The Shukla-Stenflo-Bingham effective potential model is employed to obtain the occurrence scattering time in a quantum electron-hole plasma. The result shows that the influence of Landau damping produces the imaginary term in the scattering amplitude. It is then found that the Landau damping generates the retardation effect on the occurrence scattering time. It is found that the occurrence scattering time increases in forward scattering domains and decreases in backward scattering domains with an increase of the Landau parameter. It is also found that the occurrence scattering time decreases with increasing collision energy. In addition, it is found that the quantum shielding effect enhances the occurrence scattering time in the forward scattering and, however, suppresses the occurrence scattering time in the backward scattering.

  17. Scattering equations and virtuous kinematic numerators and dual-trace functions

    NASA Astrophysics Data System (ADS)

    Naculich, Stephen G.

    2014-07-01

    Inspired by recent developments on scattering equations, we present a constructive procedure for computing symmetric, amplitude-encoded, BCJ numerators for n-point gauge-theory amplitudes, thus satisfying the three virtues identified by Broedel and Carrasco. We also develop a constructive procedure for computing symmetric, amplitude-encoded dual-trace functions τ for n-point amplitudes. These can be used to obtain symmetric kinematic numerators that automatically satisfy color-kinematic duality. The S n symmetry of n-point gravity amplitudes formed from these symmetric dual-trace functions is completely manifest. Explicit expressions for four- and five-point amplitudes are presented.

  18. Deterministic forward scatter from surface gravity waves.

    PubMed

    Deane, Grant B; Preisig, James C; Tindle, Chris T; Lavery, Andone; Stokes, M Dale

    2012-12-01

    Deterministic structures in sound reflected by gravity waves, such as focused arrivals and Doppler shifts, have implications for underwater acoustics and sonar, and the performance of underwater acoustic communications systems. A stationary phase analysis of the Helmholtz-Kirchhoff scattering integral yields the trajectory of focused arrivals and their relationship to the curvature of the surface wave field. Deterministic effects along paths up to 70 water depths long are observed in shallow water measurements of surface-scattered sound at the Martha's Vineyard Coastal Observatory. The arrival time and amplitude of surface-scattered pulses are reconciled with model calculations using measurements of surface waves made with an upward-looking sonar mounted mid-way along the propagation path. The root mean square difference between the modeled and observed pulse arrival amplitude and delay, respectively, normalized by the maximum range of amplitudes and delays, is found to be 0.2 or less for the observation periods analyzed. Cross-correlation coefficients for modeled and observed pulse arrival delays varied from 0.83 to 0.16 depending on surface conditions. Cross-correlation coefficients for normalized pulse energy for the same conditions were small and varied from 0.16 to 0.06. In contrast, the modeled and observed pulse arrival delay and amplitude statistics were in good agreement. PMID:23231099

  19. Characterizing Rayleigh Wave Velocity and Amplitude Anisotropy in an Alpine Glacier

    NASA Astrophysics Data System (ADS)

    Eilar, C. A.; Mikesell, D.; Malcolm, A. E.; Bradford, J. H.

    2014-12-01

    Regular patterns of fractures in solid materials induce seismic velocity anisotropy. These fracture patterns can also create azimuthally dependent attenuation in seismic amplitudes due to a preferential scattering direction. A parallel set of surface (or bed) crevasses in a glacier is an example of one such fracture pattern. These patterns are caused by the local strains within the glacier. In this study we analyze an active source 3D seismic survey recorded at Bench Glacier, Alaska, USA. We compare the Rayleigh group wave velocity as a function of azimuth and estimate that the mean velocity is 1672 m/s and 1% velocity anisotropy exists. We present an interpretation for the observed anisotropy by comparing our results with satellite imagery of the glacier in the survey area. Finally, we present the results of ongoing analysis of the Rayleigh wave amplitudes and compare with existing studies of glacier attenuation that do not take into account scattering attenuation when estimating the ice temperature from attenuation.

  20. Kaonic atoms and in-medium K-N amplitudes II: Interplay between theory and phenomenology

    NASA Astrophysics Data System (ADS)

    Friedman, E.; Gal, A.

    2013-02-01

    A microscopic kaonic-atom optical potential VK-(1) is constructed, using the Ikeda-Hyodo-Weise NLO chiral K-N subthreshold scattering amplitudes constrained by the kaonic hydrogen SIDDHARTA measurement, and incorporating Pauli correlations within the Waas-Rho-Weise generalization of the Ericson-Ericson multiple-scattering approach. Good fits to kaonic atom data over the entire periodic table require additionally sizable K-NN-motivated absorptive and dispersive phenomenological terms, in agreement with our former analysis based on a post-SIDDHARTA in-medium chirally-inspired NLO separable model by Cieplý and Smejkal. Such terms are included by introducing a phenomenological potential VK-(2) and coupling it self-consistently to VK-(1). Properties of resulting kaonic atom potentials are discussed with special attention paid to the role of K--nuclear absorption and to the extraction of density-dependent amplitudes representing K- multi-nucleon processes.

  1. Statistical modeling of in situ hiss amplitudes using ground measurements

    NASA Astrophysics Data System (ADS)

    Golden, D. I.; Spasojevic, M.; Li, W.; Nishimura, Y.

    2012-05-01

    Plasmaspheric hiss is a naturally occurring extremely low frequency electromagnetic emission that is often observed within the Earth's plasmasphere. Plasmaspheric hiss plays a major role in the scattering and loss of electrons from the Earth's radiation belts, thereby contributing to the maintenance of the slot region between the inner and outer electron belt. Traditionally, in situ satellite observations have been the measurement modality of choice for studies of plasmaspheric hiss due to their ability to directly measure the hiss source region. However, satellite studies are relatively short-lived and very few satellite receivers remain operational for an entire 11-year solar cycle. Ground stations, in contrast, may collect multiple solar cycles' worth of data during their lifetime, yet they cannot directly measure the hiss source region. This study aims to determine the extent to which measurements of hiss at midlatitude ground stations may be used to predict the mean amplitude of in situ measurements of plasmaspheric hiss. We use coincident measurements between Palmer Station, Antarctica (L = 2.4, 50°S invariant latitude) and the THEMIS spacecraft from June 2008 through May 2010, during solar minimum. Using an autoregressive multiple regression model, we show that in the local time sector from 00 < MLT < 12, when the ionosphere above Palmer Station is in darkness and hiss is observed at Palmer, the amplitude of plasmaspheric hiss observed by the THEMIS spacecraft is 1.4 times higher than when hiss is not observed at Palmer. In the same local time sector when the ground station is in daylight and hiss is observed, the THEMIS observed amplitudes are not significantly different from those when hiss is not observed on the ground. A stronger relationship is found in the local time sector from 12 < MLT < 24 where, when Palmer is in daylight and hiss is observed, THEMIS plasmaspheric hiss amplitudes are 2 times higher compared to when hiss is not observed at Palmer

  2. Amplitude Frequency Response Measurement: A Simple Technique

    ERIC Educational Resources Information Center

    Satish, L.; Vora, S. C.

    2010-01-01

    A simple method is described to combine a modern function generator and a digital oscilloscope to configure a setup that can directly measure the amplitude frequency response of a system. This is achieved by synchronously triggering both instruments, with the function generator operated in the "Linear-Sweep" frequency mode, while the oscilloscope…

  3. Amplitude analyses of charmless B decays

    NASA Astrophysics Data System (ADS)

    Latham, Thomas

    2016-05-01

    We present recent results from the LHCb experiment of Amplitude Analyses of charmless decays of B0 and BS0 mesons to two vector mesons. Measurements obtained include the branching fractions and polarization fractions, as well as CP asymmetries. The analyses use the data recorded by the LHCb experiment during Run 1 of the LHC.

  4. Cardiac phase: Amplitude analysis using macro programming

    SciTech Connect

    Logan, K.W.; Hickey, K.A.

    1981-11-01

    The analysis of EKG gated radionuclide cardiac imaging data with Fourier amplitude and phase images is becoming a valuable clinical technique, demonstrating location, size, and severity of regional ventricular abnormalities. Not all commercially available nuclear medicine computer systems offer software for phase and amplitude analysis; however, many systems do have the capability of linear image arithmetic using simple macro commands which can easily be sequenced into stored macro-strings or programs. Using simple but accurate series approximations for the Fourier operations, macro programs have been written for a Digital Equipment Corporation Gamma-11 system to obtain phase and amplitude images from routine gated cardiac studies. In addition, dynamic cine-mode presentation of the onset of mechanical systole is generated from the phase data, using only a second set of macro programs. This approach is easily adapted to different data acquisition protocols, and can be used on any system with macro commands for image arithmetic. Key words: Fourier analysis, cardiac cycle, gated blood pool imaging, amplitude image, phase image

  5. High-Energy Amplitudes in the Next-to-Leading Order

    SciTech Connect

    Ian Balitsky

    2011-03-01

    High-energy scattering in the saturation region is described by the evolution of color dipoles. In the leading order this evolution is governed by the non-linear BK equation. To see if this equation is relevant for existing or future accelerators (like EIC or LHeC) one needs to know how big are the next-to-leading order (NLO) corrections. I review the calculation of the NLO corrections to high-energy amplitudes in QCD.

  6. Compton scattering profile for in vivo XRF techniques.

    PubMed

    Tartari, A; Baraldi, C; Felsteiner, J; Casnati, E

    1991-05-01

    The contribution from single Compton scattered photons to the background in in vivo x-ray fluorescence analysis is evaluated by taking into account the energy broadening of the scattered photons which reflects the momentum distribution of the target electrons. A general-purpose Monte Carlo evaluation of multiple scattering components, as well as accurate experimental verifications with 59.54 keV photons impinging on various targets of interest for real-life irradiation, confirm that the single Compton scattering profiles of the elements composing the biological matrix dominate the trend and amplitude of the background in the region of interest with near-backscatter configurations. Step features are likewise explained in terms of single Compton phenomenology. Other probable sources of background, such as photoelectron Bremsstrahlung and pile-up distribution, are studied both theoretically and experimentally in order to compare their amplitude and features with those of single Compton scattered photon profiles. PMID:2068224

  7. Nucleon-nucleon scattering contribution to the triton binding energy

    SciTech Connect

    Noyes, H.P.

    1983-04-01

    We conjectured in 1972 that much of the dynamics of a few nucleon systems could be computed from the on-shell nucleon-nucleon scatterings provided that a consistent few body theory using this input could be constructed. Such a Zero Range Scattering Theory has been shown to lead to unitary three and four particle scattering amplitudes provided only the two particle amplitudes have no singularities other than bound state poles when continued to negative energies, which restricts the theory to Castillejo-Dalitz-Dyson solutions of the Low equation. We extend the model by rewriting the off-shell amplitude which drives the Faddeev equations. This amplitude retains full off-shell unitarity and still leads to unitary on-shell three particle amplitudes. This amounts to keeping any unitary two-nucleon amplitude on-shell and restricting the analytic continuation to negative energies to the term which represents the correct continuation of the two particle total partial wave cross section; the meson exchange or potential contributions are eliminated in the unphysical region, thus excising the left-hand cut. Using this model in the zero range Faddeev equations for the three nucleon system our preliminary results show that the on-shell scatterings bind the triton with about 2.5 MeV and are insensitive to the details of the fit.

  8. Classical ultra-relativistic scattering in ADD

    NASA Astrophysics Data System (ADS)

    Gal'tsov, Dmitry V.; Kofinas, Georgios; Spirin, Pavel; Tomaras, Theodore N.

    2009-05-01

    The classical differential cross-section is calculated for high-energy small-angle gravitational scattering in the factorizable model with toroidal extra dimensions. The three main features of the classical computation are: (a) It involves summation over the infinite Kaluza-Klein towers but, contrary to the Born amplitude, it is finite with no need of an ultraviolet cutoff. (b) It is shown to correspond to the non-perturbative saddle-point approximation of the eikonal amplitude, obtained by the summation of an infinite number of ladder graphs of the quantum theory. (c) In the absence of extra dimensions it reproduces all previously known results.

  9. Manifest Ultraviolet Behavior in the Three-Loop Four-Point Amplitude of N=8 Supergravity

    SciTech Connect

    Bern, Z.; Carrasco, J.J.M.; Dixon, L.J.; Johansson, H.; Roiban, R.; /Penn State U.

    2008-09-03

    Using the method of maximal cuts, we obtain a form of the three-loop four-point scattering amplitude of N = 8 supergravity in which all ultraviolet cancellations are made manifest. The Feynman loop integrals that appear have a graphical representation with only cubic vertices, and numerator factors that are quadratic in the loop momenta, rather than quartic as in the previous form. This quadratic behavior reflects cancellations beyond those required for finiteness, and matches the quadratic behavior of the three-loop four-point scattering amplitude in N = 4 super-Yang-Mills theory. By direct integration we confirm that no additional cancellations remain in the N = 8 supergravity amplitude, thus demonstrating that the critical dimension in which the first ultraviolet divergence occurs at three loops is D{sub c} = 6. We also give the values of the three-loop divergences in D = 7, 9, 11. In addition, we present the explicitly color-dressed three-loop four-point amplitude of N = 4 super-Yang-Mills theory.

  10. Stimulated Raman scattering in large plasmas

    SciTech Connect

    Phillion, D.W.; Banner, D.L.

    1980-11-06

    Stimulated Raman scattering is of concern to laser fusion since it can create a hot electron environment which can increase the difficulty of achieving high final fuel densities. In earlier experiments with one micron laser light, the energy measured in Raman-scattered light has been insignificant. But these experiments were done with, at most, about 100 joules of laser energy. The Raman instability has a high threshold which also requires a large plasma to be irradiated with a large diameter spot. Only with a long interaction length can the Raman-scattered light wave convectively grow to a large amplitude, and only in recent long pulse, high energy experiments (4000 joules in 2 ns) at the Shiva laser facility have we observed as much as several percent of the laser light to be Raman-scattered. We find that the Raman instability has a much lower intensity threshold for longer laser pulselength and larger laser spot size on a solid target.

  11. Conformal bootstrap, universality and gravitational scattering

    NASA Astrophysics Data System (ADS)

    Jackson, Steven; McGough, Lauren; Verlinde, Herman

    2015-12-01

    We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large c and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles) between two heavy states (BTZ black holes). We find that the operator algebra in this regime is (i) universal and identical to that of Liouville CFT, and (ii) takes the form of an exchange algebra, specified by an R-matrix that exactly matches the scattering amplitude of 2 + 1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.

  12. Polaris: Amplitude, Period Change, and Companions

    NASA Astrophysics Data System (ADS)

    Evans, N. R.; Sasselov, D. D.; Short, C. I.

    2000-12-01

    Amplitude: Polaris has presented us with the rare phenomenon of a Cepheid with a pulsation amplitude which has decreased over the last 50 years. In this study we investigate whether the amplitude decrease during the last 15 years has had any effect on upper atmosphere heating. We obtained IUE high and low resolution spectra but found no change in either the Mg II chromospheric emission or the flux at 1800 Å/ between 1978 and 1993 when the pulsation amplitude dropped by 50 % (from 2.8 to 1.6 km sec-1). The energy distribution from 1700 Å/ through V, B, R(KC), and I(KC) is like that of a nonvariable supergiant of the same color rather than a full amplitude Cepheid in that it has nonradiative flux at 1800 Å/ which the full amplitude Cepheid δ Cep lacks. Period Change: Polaris also has a rapidly changing period (3.2 sec/year), in common with other overtone pulsators. We argue that this is a natural consequence of the different envelope locations which dominate in growth rates in fundamental and overtone pulsation. In fundamental mode pulsators, the deeper envelope is more important in determining growth rates than for overtone pulsators. For fundamental mode pulsators, evolutionary changes in the radius produce approximately linear changes in period. In overtone pulsators, pulsation reacts to small evolutionary changes in a more unstable way because the modes are more sensitive to high envelope features such as opacity bumps, and the growth rates for the many closely spaced overtone modes change easily. Companions: The upper limit to the X-ray flux from an Einstein observation implies that the companion in the astrometric orbit is probably earlier than F4 V. The combination of upper and lower limits on the companion from IUE and Einstein respectively catch the companion mass between 1.7 and 1.4 M⊙ . The X-ray limit is consistent with the more distant companion α UMi B being a physical companion in a hierarchal triple system. However the X-ray limits imply that

  13. Theory of magnetic circular dichroism of nonresonant x-ray Raman scattering

    NASA Astrophysics Data System (ADS)

    Takahashi, Manabu; Hiraoka, Nozomu

    2015-09-01

    We develop a theory of magnetic circular dichroism (MCD) of hard x-ray Raman scattering (XRS) to analyze the MCD signal at iron L edge from pure ferromagnetic iron. The obtained formula of scattering amplitude has terms corresponding to the charge (Thomson) scattering process, and the orbital and spin scattering processes in the elastic x-ray magnetic scattering. The total scattering intensity is almost independent of incident photon helicity since it is mainly produced by the charge scattering. The weak MCD signals are caused primarily by interference between the charge scattering amplitude and each of the orbital and spin scattering amplitudes. The shape of the MCD spectra depends on angle αM between the wave vector of the incident photon and the magnetization vector. At αM=0∘ , the spin scattering is suppressed so that the MCD spectrum becomes analogous to that observed in the x-ray absorption spectroscopy. At αM=135∘ , the orbital scattering is suppressed, and the spin scattering plays central roles in producing the MCD signal. The magnitude of the MCD signal turns out to be proportional to the spin density of states projected onto the 3 d states in the unoccupied state. Consequently, the value of the integrated MCD signal is proportional to the spin moment in the 3 d states at the scattering site. The calculated MCD spectra with the help of a band structure calculation well reproduce the observed spectra.

  14. FEFF5: An ab initio multiple scattering XAFS code

    SciTech Connect

    Rehr, J.J.; Zabinsky, S.I.

    1992-12-31

    FEFF5 is an efficient automated code which calculates multiple scattering (MS) curved wave XAFS spectra for molecules and solids. The theoretical ingredients and approximations contained in the code are revised, with the aim of describing the how XAFS spectra are efficiently simulated. The FEFF5 code consists of 4 independent modules: a scattering potential and phase shift module, a path finder module, a scattering amplitude module and an XAFS module. Multiple scattering Debye-Waller factors are built in using a correlated Debye model.

  15. The Construction of Spin Foam Vertex Amplitudes

    NASA Astrophysics Data System (ADS)

    Bianchi, Eugenio; Hellmann, Frank

    2013-01-01

    Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.

  16. Differential equations, associators, and recurrences for amplitudes

    NASA Astrophysics Data System (ADS)

    Puhlfürst, Georg; Stieberger, Stephan

    2016-01-01

    We provide new methods to straightforwardly obtain compact and analytic expressions for ɛ-expansions of functions appearing in both field and string theory amplitudes. An algebraic method is presented to explicitly solve for recurrence relations connecting different ɛ-orders of a power series solution in ɛ of a differential equation. This strategy generalizes the usual iteration by Picard's method. Our tools are demonstrated for generalized hypergeometric functions. Furthermore, we match the ɛ-expansion of specific generalized hypergeometric functions with the underlying Drinfeld associator with proper Lie algebra and monodromy representations. We also apply our tools for computing ɛ-expansions for solutions to generic first-order Fuchsian equations (Schlesinger system). Finally, we set up our methods to systematically get compact and explicit α‧-expansions of tree-level superstring amplitudes to any order in α‧.

  17. Flutter of articulated pipes at finite amplitude

    NASA Technical Reports Server (NTRS)

    Rousselet, J.; Herrmann, G.

    1975-01-01

    Previous studies of the behavior of pipes conveying fluid have assumed that the fluid velocity relative to the pipe is a known quantity and is unaffected by the motion of the pipe. This approach eliminates the need to find the flow equations of motion, and is adequate for infinitesimal transverse amplitudes of motion of the pipe system, but is incapable of predicting what will be the effect of larger amplitudes. This last shortcoming may be of importance when flow velocities are near critical velocities, that is, velocities at which the system begins to flutter. It is the purpose of the present study to investigate in greater detail the dynamic behavior of pipes in the vicinity of critical velocities.

  18. Multilayered models for electromagnetic reflection amplitudes

    NASA Technical Reports Server (NTRS)

    Linlor, W. I.

    1976-01-01

    The remote sensing of snowpack characteristics with surface installations or with an airborne system could have important applications in water resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multilayer snow models is analyzed. Normally incident plane waves are assumed at frequencies ranging from 10 to the 6th power to 10 to the 10th power Hz, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice sheets. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients, versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the reflection coefficient variations as a function of frequency.

  19. Amplitudes of MHD Waves in Sunspots

    NASA Astrophysics Data System (ADS)

    Norton, Aimee Ann; Cally, Paul; Baldner, Charles; Kleint, Lucia; Tarbell, Theodore D.; De Pontieu, Bart; Scherrer, Philip H.; Rajaguru, Paul

    2016-05-01

    The conversion of p-modes into MHD waves by strong magnetic fields occurs mainly in the sub-photospheric layers. The photospheric signatures of MHD waves are weak due to low amplitudes at the beta=1 equipartion level where mode-conversion occurs. We report on small amplitude oscillations observed in the photosphere with Hinode SOT/SP in which we analyze time series for sunspots ARs 12186 (11.10.2014) and 12434 (17.10.2015). No significant magnetic field oscillations are recovered in the umbra or penumbra in the ME inversion. However, periodicities in the inclination angle are found at the umbral/penumbral boundary with 5 minute periods. Upward propagating waves are indicated in the intensity signals correlated between HMI and AIA at different heights. We compare SP results with the oscillations observed in HMI data. Simultaneous IRIS data shows transition region brightening above the umbral core.

  20. Chiral extrapolation of SU(3) amplitudes

    SciTech Connect

    Ecker, Gerhard

    2011-05-23

    Approximations of chiral SU(3) amplitudes at NNLO are proposed to facilitate the extrapolation of lattice data to the physical meson masses. Inclusion of NNLO terms is essential for investigating convergence properties of chiral SU(3) and for determining low-energy constants in a controllable fashion. The approximations are tested with recent lattice data for the ratio of decay constants F{sub K}/F{sub {pi}}.

  1. Understanding the amplitudes of noise correlation measurements

    USGS Publications Warehouse

    Tsai, Victor C.

    2011-01-01

    Cross correlation of ambient seismic noise is known to result in time series from which station-station travel-time measurements can be made. Part of the reason that these cross-correlation travel-time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding theoretical results do not currently exist to describe how the amplitudes of the cross correlation depend on such features. For example, currently it is not possible to take a given distribution of noise sources and calculate the cross correlation amplitudes one would expect from such a distribution. Here, we provide a ray-theoretical framework for calculating cross correlations. This framework differs from previous work in that it explicitly accounts for attenuation as well as the spatial distribution of sources and therefore can address the issue of quantifying amplitudes in noise correlation measurements. After introducing the general framework, we apply it to two specific problems. First, we show that we can quantify the amplitudes of coherency measurements, and find that the decay of coherency with station-station spacing depends crucially on the distribution of noise sources. We suggest that researchers interested in performing attenuation measurements from noise coherency should first determine how the dominant sources of noise are distributed. Second, we show that we can quantify the signal-to-noise ratio of noise correlations more precisely than previous work, and that these signal-to-noise ratios can be estimated for given situations prior to the deployment of seismometers. It is expected that there are applications of the theoretical framework beyond the two specific cases considered, but these applications await future work.

  2. Continuous phase and amplitude holographic elements

    NASA Technical Reports Server (NTRS)

    Maker, Paul D. (Inventor); Muller, Richard E. (Inventor)

    1995-01-01

    A method for producing a phase hologram using e-beam lithography provides n-ary levels of phase and amplitude by first producing an amplitude hologram on a transparent substrate by e-beam exposure of a resist over a film of metal by exposing n is less than or equal to m x m spots of an array of spots for each pixel, where the spots are randomly selected in proportion to the amplitude assigned to each pixel, and then after developing and etching the metal film producing a phase hologram by e-beam lithography using a low contrast resist, such as PMMA, and n-ary levels of low doses less than approximately 200 micro-C/sq cm and preferably in the range of 20-200 micro-C/sq cm, and aggressive development using pure acetone for an empirically determined time (about 6 s) controlled to within 1/10 s to produce partial development of each pixel in proportion to the n-ary level of dose assigned to it.

  3. Amplitude-integrated electroencephalography in neonates.

    PubMed

    El-Dib, Mohamed; Chang, Taeun; Tsuchida, Tammy N; Clancy, Robert R

    2009-11-01

    Conventional electroencephalography (EEG) has been used for decades in the neonatal intensive care unit for formulating neurologic prognoses, demonstrating brain functional state and degree of maturation, revealing cerebral lesions, and identifying the presence and number of electrographic seizures. However, both the immediate availability of conventional EEG and the expertise with which it is interpreted are variable. Amplitude-integrated EEG provides simplified monitoring of cerebral function, and is rapidly gaining popularity among neonatologists, with growing use in bedside decision making and inclusion criteria for randomized clinical studies. Nonetheless, child neurologists and neurophysiologists remain cautious about relying solely on this tool and prefer interpreting conventional EEG. The present review examines the technical aspects of generating, recording, and interpreting amplitude-integrated EEG and contrasts this approach with conventional EEG. Finally, several proposed amplitude-integrated EEG classification schemes are reviewed. A clear understanding of this emerging technology of measuring brain health in the premature or sick neonate is critical in modern care of the newborn infant. PMID:19818932

  4. Timelike Compton Scattering - A First Look (CLAS)

    SciTech Connect

    Pawel Nadel-Turonski

    2009-12-01

    A major goal of the 12 GeV upgrade at Jefferson Lab is to map out the Generalized Parton Distributions (GPDs) in the valence region. This is primarily done through Deeply Virtual Compton Scattering (DVCS), which provides the simplest and cleanest way of accessing the GPDs. However, the “inverse” process, Timelike Compton Scattering (TCS), can provide an important complement, in particular formeasuring the real part of the amplitude and understanding corrections at finite Q2. The first measurements of TCS have recently been carried out in Hall B at Jefferson Lab, using both tagged and untagged photon beams.

  5. Scattering States in AdS/CFT

    SciTech Connect

    Fitzpatrick, A.Liam; Kaplan, Jared; /SLAC

    2012-02-14

    We show that suitably regulated multi-trace primary states in large N CFTs behave like 'in' and 'out' scattering states in the flat-space limit of AdS. Their transition matrix elements approach the exact scattering amplitudes for the bulk theory, providing a natural CFT definition of the flat space S-Matrix. We study corrections resulting from the AdS curvature and particle propagation far from the center of AdS, and show that AdS simply provides an IR regulator that disappears in the flat space limit.

  6. Polaris: Amplitude, Period Change, and Companions

    NASA Astrophysics Data System (ADS)

    Evans, Nancy Remage; Sasselov, Dimitar D.; Short, C. Ian

    2002-03-01

    Polaris has presented us with the rare phenomenon of a Cepheid with a pulsation amplitude that has decreased over the last 50 yr. In this study we have used this property to see whether the amplitude decrease during the last 15 yr has had any effect on upper atmosphere heating. We obtained IUE high- and low-resolution spectra but found no change in either the Mg II chromospheric emission or the flux at 1800 Å between 1978 and 1993 when the pulsation amplitude dropped by 50% (from 2.8 to 1.6 km s-1). The energy distribution from 1700 Å through V, B, R(KC), and I(KC) is like that of a nonvariable supergiant of the same color rather than a full amplitude Cepheid in that it has more flux at 1800 Å than the full amplitude Cepheid δ Cep. Polaris also has a rapidly changing period (3.2 s yr-1), in common with other overtone pulsators. We argue that this is a natural consequence of the different envelope locations that dominate pulsation growth rates in fundamental and overtone pulsation. In fundamental mode pulsators, the deeper envelope is more important in determining growth rates than for overtone pulsators. For fundamental mode pulsators, evolutionary changes in the radius produce approximately linear changes in period. In overtone pulsators, pulsation reacts to small evolutionary changes in a more unstable way because the modes are more sensitive to high envelope features such as opacity bumps, and the growth rates for the many closely spaced overtone modes change easily. Finally, the upper limit to the X-ray flux from an Einstein observation implies that the companion in the astrometric orbit is earlier than F4 V. The combination of upper and lower limits on the companion from IUE and Einstein respectively catch the companion mass between 1.7 and 1.4 Msolar. The X-ray limit is consistent with the more distant companion α UMi B being a physical companion in a hierarchal triple system. However the X-ray limits require that the even more distant companions α UMi

  7. All-optical phase-preserving multilevel amplitude regeneration.

    PubMed

    Roethlingshoefer, Tobias; Richter, Thomas; Schubert, Colja; Onishchukov, Georgy; Schmauss, Bernhard; Leuchs, Gerd

    2014-11-01

    The possibility of all-optical phase-preserving amplitude regeneration for star-8QAM is demonstrated using a modified nonlinear optical loop mirror. Experiments show a reduction in amplitude noise on both amplitude levels simultaneously, considering two different types of signal distortions: deterministic low-frequency amplitude modulation and broadband amplitude noise. Furthermore, using this amplitude regeneration, the robustness against nonlinear phase noise from fiber nonlinearity in a transmission line is increased. The scheme suppresses the conversion of amplitude noise to nonlinear phase noise. This is shown for simultaneous amplitude regeneration of the two amplitude states as well as for amplitude regeneration of the high-power states only. If the transmission is limited by nonlinear phase noise, single-level operation at the more critical higher-power state will benefit because of the wider plateau region. Numerical simulations confirm the experimental results. PMID:25401858

  8. Four loop scattering in the Nambu-Goto theory

    NASA Astrophysics Data System (ADS)

    Conkey, Peter; Dubovsky, Sergei

    2016-05-01

    We initiate the study of multiloop scattering amplitudes in the Nambu-Goto theory on the worldsheet of a non-critical string. We start with a brute force calculation of two loop four particle scattering. Somewhat surprisingly, even though non-trivial UV counterterms are present at this order, on-shell amplitudes remain polynomial in the momenta of colliding particles. We show that this can be understood as a consequence of existence of certain close by (semi)integrable models. Furthermore, these arguments can be extended to obtain the answer for three and four loop scattering, bypassing the brute force calculation. The resulting amplitudes develop non-polynomial (logarithmic) dependence on the momenta starting at three loops.

  9. Low-energy pion-nucleon scattering

    NASA Astrophysics Data System (ADS)

    Gibbs, W. R.; Ai, Li; Kaufmann, W. B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent π+/-p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f2=0.0756+/-0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P31 and P13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided.

  10. Low-energy pion-nucleon scattering

    SciTech Connect

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-02-01

    An analysis of low-energy charged pion-nucleon data from recent {pi}{sup {plus_minus}}p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f{sup 2}=0.0756{plus_minus}0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P{sub 31} and P{sub 13} partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the {Sigma} term. Off-shell amplitudes are also provided. {copyright} {ital 1998} {ital The American Physical Society}

  11. Amplitude Scintillation due to Atmospheric Turbulence for the Deep Space Network Ka-Band Downlink

    NASA Technical Reports Server (NTRS)

    Ho, C.; Wheelon, A.

    2004-01-01

    Fast amplitude variations due to atmospheric scintillation are the main concerns for the Deep Space Network (DSN) Ka-band downlink under clear weather conditions. A theoretical study of the amplitude scintillation variances for a finite aperture antenna is presented. Amplitude variances for weak scattering scenarios are examined using turbulence theory to describe atmospheric irregularities. We first apply the Kolmogorov turbulent spectrum to a point receiver for three different turbulent profile models, especially for an exponential model varying with altitude. These analytic solutions then are extended to a receiver with a finite aperture antenna for the three profile models. Smoothing effects of antenna aperture are expressed by gain factors. A group of scaling factor relations is derived to show the dependences of amplitude variances on signal wavelength, antenna size, and elevation angle. Finally, we use these analytic solutions to estimate the scintillation intensity for a DSN Goldstone 34-m receiving station. We find that the (rms) amplitude fluctuation is 0.13 dB at 20-deg elevation angle for an exponential model, while the fluctuation is 0.05 dB at 90 deg. These results will aid us in telecommunication system design and signal-fading prediction. They also provide a theoretical basis for further comparison with other measurements at Ka-band.

  12. High-energy photon-hadron scattering in holographic QCD

    SciTech Connect

    Nishio, Ryoichi; Watari, Taizan

    2011-10-01

    This article provides an in-depth look at hadron high-energy scattering by using gravity dual descriptions of strongly coupled gauge theories. Just like deeply inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) serve as clean experimental probes into nonperturbative internal structure of hadrons, elastic scattering amplitude of a hadron and a (virtual) photon in gravity dual can be exploited as a theoretical probe. Since the scattering amplitude at sufficiently high energy (small Bjorken x) is dominated by parton contributions (=Pomeron contributions) even in strong coupling regime, there is a chance to learn a lesson for generalized parton distribution (GPD) by using gravity dual models. We begin with refining derivation of the Brower-Polchinski-Strassler-Tan (BPST) Pomeron kernel in gravity dual, paying particular attention to the role played by the complex spin variable j. The BPST Pomeron on warped spacetime consists of a Kaluza-Klein tower of 4D Pomerons with nonlinear trajectories, and we clarify the relation between Pomeron couplings and the Pomeron form factor. We emphasize that the saddle-point value j* of the scattering amplitude in the complex j-plane representation is a very important concept in understanding qualitative behavior of the scattering amplitude. The total Pomeron contribution to the scattering is decomposed into the saddle-point contribution and at most a finite number of pole contributions, and when the pole contributions are absent (which we call saddle-point phase), kinematical variable (q,x,t)-dependence of ln(1/q) evolution and ln(1/x) evolution parameters {gamma}{sub eff} and {lambda}{sub eff} in DIS and t-slope parameter B of DVCS in HERA experiment are all reproduced qualitatively in gravity dual. All of these observations shed a new light on modeling of GPD. Straightforward application of those results to other hadron high-energy scattering is also discussed.

  13. Stress-dependent ultrasonic scattering in polycrystalline materials.

    PubMed

    Kube, Christopher M; Turner, Joseph A

    2016-02-01

    Stress-dependent elastic moduli of polycrystalline materials are used in a statistically based model for the scattering of ultrasonic waves from randomly oriented grains that are members of a stressed polycrystal. The stress is assumed to be homogeneous and can be either residual or generated from external loads. The stress-dependent elastic properties are incorporated into the definition of the differential scattering cross-section, which defines how strongly an incident wave is scattered into various directions. Nine stress-dependent differential scattering cross-sections or scattering coefficients are defined to include all possibilities of incident and scattered waves, which can be either longitudinal or (two) transverse wave types. The evaluation of the scattering coefficients considers polycrystalline aluminum that is uniaxially stressed. An analysis of the influence of incident wave propagation direction, scattering direction, frequency, and grain size on the stress-dependency of the scattering coefficients follows. Scattering coefficients for aluminum indicate that ultrasonic scattering is much more sensitive to a uniaxial stress than ultrasonic phase velocities. By developing the stress-dependent scattering properties of polycrystals, the influence of acoustoelasticity on the amplitudes of waves propagating in stressed polycrystalline materials can be better understood. This work supports the ongoing development of a technique for monitoring and measuring stresses in metallic materials. PMID:26936563

  14. Hadron Optics: Diffraction Patterns in Deeply Virtual Compton Scattering

    SciTech Connect

    Brodsky, S

    2006-05-16

    We show that the Fourier transform of the Deeply Virtual Compton Scattering (DVCS) amplitude with respect to the skewness variable {zeta} provides a unique way to visualize the light-front wavefunctions (LFWFs) of the target state in the boost-invariant longitudinal coordinate space variable ({sigma} = P{sup +}y{sup -}/2). The results are analogous to the diffractive scattering of a wave in optics in which the dependence of the amplitude on {sigma} measures the physical size of the scattering center of a one-dimensional system. If one combines this longitudinal transform with the Fourier transform of the DVCS amplitude with respect to the transverse momentum transfer {Delta}{sup {perpendicular}}, one can obtain a complete three-dimensional description of hadron optics at fixed light-front time {tau} = t + z/c. As a specific example, we utilize the quantum fluctuations of a fermion state at one loop in QED to obtain the behavior of the DVCS amplitude for electron-photon scattering. We then simulate the wavefunctions for a hadron by differentiating the above LFWFs with respect to M{sup 2} and study the corresponding DVCS amplitudes in {sigma} space.

  15. Phase amplitude conformal symmetry in Fourier transforms

    NASA Astrophysics Data System (ADS)

    Kuwata, S.

    2015-04-01

    For the Fourier transform ℑ : L2(R) → L2(R) of a complex-valued even or odd function ψ, it is found that the amplitude invariance |ℑψ| = |ψ| leads to a phase invariance or inversion as arg(ℑψ) = ±argψ + θ (θ = constant). The converse holds unless arg ψ = constant. The condition |ψ| = |ℑψ| is required in dealing with, for example, the minimum uncertainty relation between position and momentum. Without the evenness or oddness of ψ, |ℑψ| = |ψ| does not necessarily imply arg(ℑψ) = ±argψ + θ, nor is the converse.

  16. The small amplitude magnetohydrodynamic Riemann problem

    NASA Technical Reports Server (NTRS)

    Wu, C. C.; Kennel, C. F.

    1993-01-01

    The small-amplitude MHD Riemann problem is studied using the Cohen-Kulsrud-Burgers equations. Unlike the coplanar Riemann problem, the evolution of noncoplanar Riemann problems is not self-similar and its flow structures could change in time. But its large-time behavior is very simple and a time-dependent 2 - 3 intermediate shock is always involved for the noncoplanar field rotations. The time-dependent 2 - 3 intermediate shock has a well-defined structure and exists for any degree of field rotation.

  17. Information transfer for small-amplitude signals

    NASA Astrophysics Data System (ADS)

    Kostal, Lubomir; Lansky, Petr

    2010-05-01

    We study the optimality conditions of information transfer in systems with memory in the low signal-to-noise ratio regime of vanishing input amplitude. We find that the optimal mutual information is represented by a maximum variance of the signal time course, with correlation structure determined by the Fisher information matrix. We provide illustration of the method on a simple biologically inspired model of electrosensory neuron. Our general results apply also to the study of information transfer in single neurons subject to weak stimulation, with implications to the problem of coding efficiency in biological systems.

  18. Fatigue crack growth under variable amplitude loading

    NASA Astrophysics Data System (ADS)

    Sidawi, Jihad A.

    1994-09-01

    Fatigue crack growth tests were conducted on an Fe 510 E C-Mn steel and a submerged arc welded joint from the same material under constant, variable, and random loading amplitudes. Paris-Erdogan's crack growth rate law was tested for the evaluation of m and C using the stress intensity factor K, the J-integral, the effective stress intensity factor K(sub eff), and the root mean square stress intensity factor K(sub rms) fracture mechanics concepts. The effect of retardation and residual stresses resulting from welding was also considered. It was found that all concepts gave good life predictions in all cases.

  19. Stochastic aspects of nuclear large amplitude motion

    SciTech Connect

    Kolomietz, V.M.

    1995-08-01

    A consistent description of the macroscopic large amplitude dynamics and processes of internal excitation of a nucleus is suggested. The cranking model approach is used for the calculation of the response function of the nucleus in a moving frame. Using spectral statistics smearing, the collective mass, friction, and diffusion coefficients are derived. The relation of the response function in a moving frame to the correlation function in a classical chaotic system is established. The rate of dissipation due to the Landau-Zener transitions and through the Kubo mechanism is considered.

  20. Normal Spin Asymmetries in Elastic Electron-Proton Scattering

    SciTech Connect

    M. Gorchtein; P.A.M. Guichon; M. Vanderhaeghen

    2004-10-01

    We discuss the two-photon exchange contribution to observables which involve lepton helicity flip in elastic lepton-nucleon scattering. This contribution is accessed through the single spin asymmetry for a lepton beam polarized normal to the scattering plane. We estimate this beam normal spin asymmetry at large momentum transfer using a parton model and we express the corresponding amplitude in terms of generalized parton distributions. We further discuss this observable in the quasi-RCS kinematics which may be dominant at certain kinematical conditions and find it to be governed by the photon helicity-flip RCS amplitudes.

  1. Stimulated Brillouin scattering in the field of a two-dimensionally localized pumping wave

    NASA Astrophysics Data System (ADS)

    Solikhov, D. K.; Dvinin, S. A.

    2016-06-01

    Stimulated Brillouin scattering of electromagnetic waves in the field of a two-dimensionally localized pump wave at arbitrary scattering angles in the regime of forward scattering is analyzed. Spatial variations in the amplitudes of interacting waves are studied for different values of the pump field and different dimensions of the pump wave localization region. The intensity of scattered radiation is determined as a function of the scattering angle and the dimensions of the pump wave localization region. It is shown that the intensity increases with increasing scattering angle.

  2. Recursion relations for multi-gluon off-shell amplitudes on the light-front and Wilson lines

    NASA Astrophysics Data System (ADS)

    Cruz-Santiago, C.; Kotko, P.; Staśto, A. M.

    2015-06-01

    We analyze the off-shell scattering amplitudes in the framework of the light-front perturbation theory. It is shown that the previously derived recursion relation between tree level off-shell amplitudes in this formalism actually resums whole classes of graphs into a Wilson line. More precisely, we establish a correspondence between the light-front methods for the computation of the off-shell amplitudes and the approach which makes use of the matrix elements of straight infinite Wilson lines, which are manifestly gauge invariant objects. Furthermore, since it is needed to explicitly verify the gauge invariance of light-front amplitudes, it is demonstrated that the Ward identities in this framework need additional instantaneous terms in the light-front graphs.

  3. Momentum space dipole amplitude for DIS and inclusive hadron production

    SciTech Connect

    Basso, E. A.; Gay Ducati, M. B.; De Oliveira, E. G.

    2013-03-25

    We show how the AGBS model, originally developed for deep inelastic scattering applied to HERA data on the proton structure function, can also describe the RHIC data on single inclusive hadron yield for d+Au and p+p collisions through a new simultaneous fit. The single inclusive hadron production is modeled through the color glass condensate, which uses the quark(and gluon) condensate amplitudes in momentum space. The AGBS model is also a momentum space model based on the asymptotic solutions of the BK equation, although a different definition of the Fourier transform is used. This description entirely in transverse momentum of both processes arises for the first time. The small difference between the simultaneous fit and the one for HERA data alone suggests that the AGBS model describes very well both kind of processes and thus emerges as a good tool to investigate the inclusive hadron production data. We use this model for predictions at LHC energies, which agree quite well with available experimental data.

  4. Multiphonon scattering from surfaces

    NASA Astrophysics Data System (ADS)

    Manson, J. R.; Celli, V.; Himes, D.

    1994-01-01

    We consider the relationship between several different formalisms for treating the multiphonon inelastic scattering of atomic projectiles from surfaces. Starting from general principles of formal scattering theory, the trajectory approximation to the scattering intensity is obtained. From the trajectory approximation, the conditions leading to the fast-collision approximation for multiquantum inelastic scattering are systematically derived.

  5. Small-amplitude synchrotron tune near transition

    SciTech Connect

    Ng, K.Y.; /Fermilab

    2010-05-01

    The separatrices of the rf buckets near transition are mapped when the synchronous phase is neither 0 or {pi}. The small-amplitude synchronous tune is derived when the rf frequency is changed. Synchrotron radiation is present in all electron storage ring. As a result, the synchronous phase is always offset from {phi}{sub s} = {pi} to compensate for the power loss. Even for proton storage rings with negligible synchrotron radiation, the synchronous phase is also required to be offset from {phi}{sub s} = 0 or {pi} slightly to compensate for beam loading. Thus for all storage rings operating near transition, beam particles reside in accelerating buckets instead of stationary bucket. It is of interest to map these buckets and see how they evolve near transition. When the rf frequency is varied, the closed orbit is pushed radially inward or outward. The momentum of the particle synchronous with the rf is thus changed. By measuring the small-amplitude synchrotron tune as a function of the rf frequency, the lowest first few orders of the slip factor can be inferred. Here, we derive this relationship up to the lowest first three orders of the slip factor when the particle velocity is not ultra-relativistic.

  6. Spurious cross-frequency amplitude-amplitude coupling in nonstationary, nonlinear signals

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Lo, Men-Tzung; Hu, Kun

    2016-07-01

    Recent studies of brain activities show that cross-frequency coupling (CFC) plays an important role in memory and learning. Many measures have been proposed to investigate the CFC phenomenon, including the correlation between the amplitude envelopes of two brain waves at different frequencies - cross-frequency amplitude-amplitude coupling (AAC). In this short communication, we describe how nonstationary, nonlinear oscillatory signals may produce spurious cross-frequency AAC. Utilizing the empirical mode decomposition, we also propose a new method for assessment of AAC that can potentially reduce the effects of nonlinearity and nonstationarity and, thus, help to avoid the detection of artificial AACs. We compare the performances of this new method and the traditional Fourier-based AAC method. We also discuss the strategies to identify potential spurious AACs.

  7. Fatigue life prediction of rotor blade composites: Validation of constant amplitude formulations with variable amplitude experiments

    NASA Astrophysics Data System (ADS)

    Westphal, T.; Nijssen, R. P. L.

    2014-12-01

    The effect of Constant Life Diagram (CLD) formulation on the fatigue life prediction under variable amplitude (VA) loading was investigated based on variable amplitude tests using three different load spectra representative for wind turbine loading. Next to the Wisper and WisperX spectra, the recently developed NewWisper2 spectrum was used. Based on these variable amplitude fatigue results the prediction accuracy of 4 CLD formulations is investigated. In the study a piecewise linear CLD based on the S-N curves for 9 load ratios compares favourably in terms of prediction accuracy and conservativeness. For the specific laminate used in this study Boerstra's Multislope model provides a good alternative at reduced test effort.

  8. Thomson scattering in dense plasmas with density and temperature gradients

    NASA Astrophysics Data System (ADS)

    Fortmann, C.; Thiele, R.; Fäustlin, R. R.; Bornath, Th.; Holst, B.; Kraeft, W.-D.; Schwarz, V.; Toleikis, S.; Tschentscher, Th.; Redmer, R.

    2009-09-01

    Collective X-ray Thomson scattering has become a versatile tool for the diagnostics of dense plasmas. Assuming homogeneous density and temperature throughout the target sample, these parameters can be determined directly from the plasmon dispersion and the ratio of plasmon amplitudes via detailed balance. In inhomogeneous media, the scattering signal is an average of the density and temperature dependent scattering cross-section weighted with the density and temperature profiles. We analyse Thomson scattering spectra in the XUV range from near solid density hydrogen targets generated by free electron laser radiation. The influence of plasma inhomogeneities on the scattering spectrum is investigated by comparing density and temperature averaged scattering signals to calculations assuming homogeneous targets. We find discrepancies larger than 10% between the mean electron density and the effective density as well as between the mean temperature and the effective temperature.

  9. Roy-Steiner equations for πN scattering

    NASA Astrophysics Data System (ADS)

    de Elvira, J. Ruiz; Ditsche, C.; Hoferichter, M.; Kubis, B.; Meißner, U.-G.

    2015-10-01

    In this talk, we briefly review our ongoing collaboration to precisely determine the low-energy πN scattering amplitude by means of Roy-Steiner equations. After giving a brief overview of this system of dispersive equations and their application to πN scattering, we proceed to solve for the lower partial waves of the s-channel (πN → πN) and the t-channel l( {π π to bar NN} right) sub-problems.

  10. Strong WW scattering chiral lagrangians, unitarity and resonances

    SciTech Connect

    Pelaez, J.R.

    1996-08-01

    Chiral lagrangians provide a model independent description of the strongly interacting symmetry breaking sector. In this work, first we review the LHC sensitivity to the chiral parameters (in the hardest case of non-resonant low-energy WW scattering). Later we show how to reproduce or predict the resonance spectrum by means of dispersion theory and the inverse amplitude method. We present a parameter space scan that covers many different strong WW scattering scenarios.

  11. Analysis of elastic {alpha}-nucleus scattering data at 240 MeV

    SciTech Connect

    Alvi, M. A.; Madani, J. H.; Hakmi, A. M.

    2007-06-15

    Working within the framework of the Coulomb modified Glauber model we fit the elastic differential scattering cross section of 240 MeV {alpha} particle on {sup 58}Ni using the effective N-{alpha} amplitude with one adjustable parameter. It is found that once the effective amplitude is calibrated on {sup 58}Ni by varying the adjustable parameter, it very nicely reproduces the available elastic {alpha} scattering data on other nuclei at the same energy.

  12. Resonances in Coupled πK-ηK Scattering from Quantum Chromodynamics

    DOE PAGESBeta

    Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.; Wilson, David J.

    2014-10-01

    Using first-principles calculation within Quantum Chromodynamics, we are able to reproduce the pattern of experimental strange resonances which appear as complex singularities within coupled πK, ηK scattering amplitudes. We make use of numerical computation within the lattice discretized approach to QCD, extracting the energy dependence of scattering amplitudes through their relation- ship to the discrete spectrum of the theory in a finite-volume, which we map out in unprecedented detail.

  13. Hard elastic scattering in QCD: Leading behavior

    SciTech Connect

    Botts, J.F.

    1989-01-01

    The author derives the asymptotic behavior of elastic meson-meson and baryon-baryon scattering at high energy and large angle t/s {approximately} O(1). The results organize both Sudakov and nonleading logarithmic corrections to independent (Landshoff) scatterings of valence quarks. He shows how to separate these contributions systematically from single scattering contributions, in a manner which suggests that the complete amplitudes should be computable perturbatively down to the dimensional counting power, in terms of hadronic wave functions. In the final chapter, the perturbative asymptotic amplitude and differential cross section for elastic pion-pion scattering is calculated numerically. For various choices of pion wave function and running coupling, the onset of power law behavior, d{sigma}/dt {approximately} s{sup {minus}5.8}, was observed. The dependence in d{sigma}/dt on the cutoff in gluon momentum, chosen to be O({Lambda}{sub QCD}/Q), was observed to be sharp for ln(s/1GeV{sup 2}) less than 1. Very small oscillations in d{sigma}/dt appear in physically realizable energies, but these are cutoff dependent, and their interpretation unclear. Higher twist effects were estimated to be roughly {approximately}15% for 2 < ln(s/1GeV{sup 2}) < 10.

  14. The kinematic algebras from the scattering equations

    NASA Astrophysics Data System (ADS)

    Monteiro, Ricardo; O'Connell, Donal

    2014-03-01

    We study kinematic algebras associated to the recently proposed scattering equations, which arise in the description of the scattering of massless particles. In particular, we describe the role that these algebras play in the BCJ duality between colour and kinematics in gauge theory, and its relation to gravity. We find that the scattering equations are a consistency condition for a self-dual-type vertex which is associated to each solution of those equations. We also identify an extension of the anti-self-dual vertex, such that the two vertices are not conjugate in general. Both vertices correspond to the structure constants of Lie algebras. We give a prescription for the use of the generators of these Lie algebras in trivalent graphs that leads to a natural set of BCJ numerators. In particular, we write BCJ numerators for each contribution to the amplitude associated to a solution of the scattering equations. This leads to a decomposition of the determinant of a certain kinematic matrix, which appears naturally in the amplitudes, in terms of trivalent graphs. We also present the kinematic analogues of colour traces, according to these algebras, and the associated decomposition of that determinant.

  15. True and false symmetries in the classification of optical scatterers

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.; Videen, Gorden

    2014-05-01

    A plane wave is scattered by a potential of bounded support. Translation, rotation and reflection of the potential, q0 induce transformations of the scattered wave. The latter can be represented by means of Born sequences, where q0 appears under the integral sign: non-local formulas are thus derived, the properties of which are discussed. Next, the symmetries induced by the 1st BORN approximation are addressed. Invariance of the squared modulus of the scattering amplitude holds for translation and reflection. The transformation Tɛ := 13 +Σ3ℓ=1ɛℓAℓ, with {ɛℓ;} real and {Aℓ} the generators of rotations in IR3, is investigated. Conditions on the {ɛ ℓ} are derived, by which the scattering amplitude coming from the first BORN approximation is invariant to Tɛ. As an application, these "false symmetries" are compared to those induced by limited angular resolution of a detector in light scattering experiments. Namely, scattering patterns are made available by the TAOS (Two-dimensional Angle-resolved Optical Scattering) method, which consists of detecting single airborne aerosol particles and collecting the intensity of the light they scatter from a pulsed, monochromatic laser beam. The optics and the detector properties determine the resolution at which a pattern is saved. The implications on the performance of TAOS pattern analysis are briefly discussed.

  16. Multiple Scattering Theory for Inelastic Processes

    NASA Astrophysics Data System (ADS)

    Braun, V. M.; Shabelski, Yu. M.

    The review is devoted to the description of inelastic interactions of composite systems in the framework of the multiple scattering approach. Quasielastic scattering and multiple hadron production processes are considered for hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions at high energies. We show that important information on inelastic processes follows on very general grounds from the classification of various intermediate states in the elastic amplitude, as similarly AGK cutting rules arise for reggeon diagrams. Attention is mainly given to the appropriate technique, which is illustrated with several examples of increasing complexity. The general formalism for the inelastic screening corrections is presented and its particular applications to various reactions. The review does not aim at the systematic study of numerous versions of the multiple scattering calculus confronting each other and to the extensive experimental data. Instead, we concentrate on a few simple examples to make clear the underlying physics and to work out the needed machinery employed in practical calculations.

  17. Effects of periodic forcing in chaotic scattering.

    PubMed

    Blesa, Fernando; Seoane, Jesús M; Barrio, Roberto; Sanjuán, Miguel A F

    2014-04-01

    The effects of a periodic forcing on chaotic scattering are relevant in certain situations of physical interest. We investigate the effects of the forcing amplitude and the external frequency in both the survival probability of the particles in the scattering region and the exit basins associated to phase space. We have found an exponential decay law for the survival probability of the particles in the scattering region. A resonant-like behavior is uncovered where the critical values of the frequencies ω≃1 and ω≃2 permit the particles to escape faster than for other different values. On the other hand, the computation of the exit basins in phase space reveals the existence of Wada basins depending of the frequency values. We provide some heuristic arguments that are in good agreement with the numerical results. Our results are expected to be relevant for physical phenomena such as the effect of companion galaxies, among others. PMID:24827315

  18. Multipole radiation in charged-particle scattering

    NASA Technical Reports Server (NTRS)

    Gould, Robert J.

    1990-01-01

    This paper formulates the general problem of photon emission in particle scattering using a classical and quantum mechanical approach. The connection between the classical short collision time (SCT) and Born results is examined for various special classifications of problems. In the dipole case the two formulations yield results that can be expressed in the same form and for arbitrary scattering potential. For quadrupole emission the SCT and Born results are the same only for a short-range potential, however. The quadrupole problem is more sensitive to details in the process because the calculation requires an expansion of the total amplitude for the process to lowest order in the photon wave number or momentum. The special case of photon emission associated with spin-flip transitions during scattering is considered for spin-1/2 particles. Like classical magnetic dipole radiation, there is no infrared divergence feature for this type of emission.

  19. Large Amplitude Whistler Waves and Electron Acceleration in the Earth's Radiation Belts: A Review of STEREO and Wind Observations

    NASA Technical Reports Server (NTRS)

    Cattell, Cynthia; Breneman, A.; Goetz, K.; Kellogg, P.; Kersten, K.; Wygant, J.; Wilson, L. B., III; Looper, Mark D.; Blake, J. Bernard; Roth, I.

    2012-01-01

    One of the critical problems for understanding the dynamics of Earth's radiation belts is determining the physical processes that energize and scatter relativistic electrons. We review measurements from the Wind/Waves and STEREO S/Waves waveform capture instruments of large amplitude whistler-mode waves. These observations have provided strong evidence that large amplitude (100s mV/m) whistler-mode waves are common during magnetically active periods. The large amplitude whistlers have characteristics that are different from typical chorus. They are usually nondispersive and obliquely propagating, with a large longitudinal electric field and significant parallel electric field. We will also review comparisons of STEREO and Wind wave observations with SAMPEX observations of electron microbursts. Simulations show that the waves can result in energization by many MeV and/or scattering by large angles during a single wave packet encounter due to coherent, nonlinear processes including trapping. The experimental observations combined with simulations suggest that quasilinear theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.

  20. Toward improved photon-atom scattering predictions

    NASA Astrophysics Data System (ADS)

    Kissel, Lynn

    1995-05-01

    Photon-atom scattering is important in a variety of applications, but scattering from a composite system depends on the accurate characterization of the scattering from an isolated atom or ion. We have been examining the validity of simpler approximations of elastic scattering in the light of second-order S-matrix theory. Partitioning the many-body amplitude into Rayleigh and Delbrück components, processes beyond photoionization contribute. Subtracted cross sections for bound-bound atomic transitions and bound pair annihilation are required in anomalous scattering factors for: (1) convergence of the dispersion integral; (2) agreement with predictions of the more sophisticated S-matrix approach; (3) satisfying the Thomas-Reiche-Kuhn sum rule. New accurate tabulations of anomalous scattering factors have been prepared for all Z, for energies 0-10 000 keV, within the independent particle approximation (IPA) using a Dirac-Slater model of the atom. Separately, experimental atomic photoabsorption threshold information has been used to modify these IPA predictions for improved comparison with experiment.

  1. Toward improved photon-atom scattering predictions

    NASA Astrophysics Data System (ADS)

    Kissel, Lynn

    1994-10-01

    Photon-atom scattering is important in a variety of applications, but scattering from a composite system depends on the accurate characterization of the scattering from an isolated atom or ion. We have been examining the validity of simpler approximations of elastic scattering in the light of second-order S-matrix theory. Partitioning the many-body amplitude into Rayleigh and Delbrueck components, processes beyond photoionization contribute. Subtracted cross sections for bound-bound atomic transitions, bound pair annihilation, and bound pair production are required in anomalous scattering factors for: (1) convergence of the dispersion integral; (2) agreement with predictions of the more sophisticated S-matrix approach; (3) satisfying the Thomas-Reiche-Kuhn sum rule. New accurate tabulations of anomalous scattering factors have been prepared for all Z, for energies 0-10,000 keV, within the independent particle approximation (IPA) using a Dirac-Slater model of the atom. Separately, experimental atomic photoabsorption threshold information has been used to modify these IPA predictions for improved comparison with experiment.

  2. TOPICAL REVIEW: A first course on twistors, integrability and gluon scattering amplitudes

    NASA Astrophysics Data System (ADS)

    Wolf, Martin

    2010-10-01

    These notes accompany an introductory lecture course on the twistor approach to supersymmetric gauge theories aimed at early stage PhD students. It was held by the author at the University of Cambridge during the Michaelmas term in 2009. The lectures assume a working knowledge of differential geometry and quantum field theory. No prior knowledge of twistor theory is required.

  3. On the Resonance-Like Behavior in the pp Scattering Amplitudes

    NASA Astrophysics Data System (ADS)

    Otofuji, T.; Sakai, K.; Kanada, H.; Saito, S.; Yasuno, M.

    1985-03-01

    The series of ``dibaryons'' is investigated in detail by means of a coupled-channel model of the NN, N Delta and Delta Delta channels. The π and rho meson exchange potential is employed with cutoff form factors and inner hard core. It is shown that the model reproduces the series of the ``dibaryons'' of the natural-parity states; that is the resonance-like behavior (RLB) in the 1D2, 3F3, 1G4, (3H5) and 1I6 states. The masses and widths of these ``resonances'' agree well with those given by Auer et al. A detailed study shows that the RLB is mainly due to the coupling with the N Delta aligned states (NDAS) (L=J-2 and S=2), and that the NDAS give rise to a spectrum of rotational-like structure. It is suggested that aligned states (SAS) of L=J and S=2 bring about resonance-like behavior for the even-parity states in the higher energy region.

  4. Experimental generation of amplitude squeezed vector beams.

    PubMed

    Chille, Vanessa; Berg-Johansen, Stefan; Semmler, Marion; Banzer, Peter; Aiello, Andrea; Leuchs, Gerd; Marquardt, Christoph

    2016-05-30

    We present an experimental method for the generation of amplitude squeezed high-order vector beams. The light is modified twice by a spatial light modulator such that the vector beam is created by means of a collinear interferometric technique. A major advantage of this approach is that it avoids systematic losses, which are detrimental as they cause decoherence in continuous-variable quantum systems. The utilisation of a spatial light modulator (SLM) gives the flexibility to switch between arbitrary mode orders. The conversion efficiency with our setup is only limited by the efficiency of the SLM. We show the experimental generation of Laguerre-Gauss (LG) modes with radial indices 0 or 1 and azimuthal indices up to 3 with complex polarization structures and a quantum noise reduction up to -0.9dB±0.1dB. The corresponding polarization structures are studied in detail by measuring the spatial distribution of the Stokes parameters. PMID:27410153

  5. Evaluation of new spin foam vertex amplitudes

    NASA Astrophysics Data System (ADS)

    Khavkine, Igor

    2009-06-01

    The Christensen-Egan algorithm is extended and generalized to efficiently evaluate new spin foam vertex amplitudes proposed by Engle, Pereira and Rovelli and Freidel and Krasnov, with or without (factored) boundary states. A concrete pragmatic proposal is made for comparing the different models using uniform methodologies, applicable to the behavior of large spin asymptotics and of expectation values of specific semiclassical observables. The asymptotics of the new models exhibit non-oscillatory, power-law decay similar to that of the Barrett-Crane model, though with different exponents. Also, an analysis of the semiclassical wave packet propagation problem indicates that the Magliaro, Rovelli and Perini's conjecture of good semiclassical behavior of the new models does not hold for generic factored states, which neglect spin-spin correlations.

  6. Flutter of articulated pipes at finite amplitude

    NASA Technical Reports Server (NTRS)

    Rousselet, J.; Herrmann, G.

    1977-01-01

    The plane motion of an articulated pipe made of two segments is examined and the flow velocity at which flutter manifests itself is sought. The pressure in the reservoir feeding the pipe is kept constant. In contrast to previous works, the flow velocity is not taken as a prescribed parameter of the system but is left to follow the laws of motion. This approach requires a nonlinear formulation of the problem and the equations of motion are solved using Krylov-Bogoliubov's method. A graph of the amplitude of the limit cycles, as a function of the fluid-system mass ratio, is presented and conclusions are drawn as to the necessity of considering nonlinearities in the analysis.

  7. Amplitude Scaling of Active Separation Control

    NASA Technical Reports Server (NTRS)

    Stalnov, Oksana; Seifert, Avraham

    2010-01-01

    Three existing and two new excitation magnitude scaling options for active separation control at Reynolds numbers below one Million. The physical background for the scaling options was discussed and their relevance was evaluated using two different sets of experimental data. For F+ approx. 1, 2D excitation: a) The traditional VR and C(mu) - do not scale the data. b) Only the Re*C(mu) is valid. This conclusion is also limited for positive lift increment.. For F+ > 10, 3D excitation, the Re corrected C(mu), the St corrected velocity ratio and the vorticity flux coefficient, all scale the amplitudes equally well. Therefore, the Reynolds weighted C(mu) is the preferred choice, relevant to both excitation modes. Incidence also considered, using Ue from local Cp.

  8. Speech recognition with amplitude and frequency modulations

    NASA Astrophysics Data System (ADS)

    Zeng, Fan-Gang; Nie, Kaibao; Stickney, Ginger S.; Kong, Ying-Yee; Vongphoe, Michael; Bhargave, Ashish; Wei, Chaogang; Cao, Keli

    2005-02-01

    Amplitude modulation (AM) and frequency modulation (FM) are commonly used in communication, but their relative contributions to speech recognition have not been fully explored. To bridge this gap, we derived slowly varying AM and FM from speech sounds and conducted listening tests using stimuli with different modulations in normal-hearing and cochlear-implant subjects. We found that although AM from a limited number of spectral bands may be sufficient for speech recognition in quiet, FM significantly enhances speech recognition in noise, as well as speaker and tone recognition. Additional speech reception threshold measures revealed that FM is particularly critical for speech recognition with a competing voice and is independent of spectral resolution and similarity. These results suggest that AM and FM provide independent yet complementary contributions to support robust speech recognition under realistic listening situations. Encoding FM may improve auditory scene analysis, cochlear-implant, and audiocoding performance. auditory analysis | cochlear implant | neural code | phase | scene analysis

  9. Oscillation quenching mechanisms: Amplitude vs. oscillation death

    NASA Astrophysics Data System (ADS)

    Koseska, Aneta; Volkov, Evgeny; Kurths, Jürgen

    2013-10-01

    Oscillation quenching constitutes a fundamental emergent phenomenon in systems of coupled nonlinear oscillators. Its importance for various natural and man-made systems, ranging from climate, lasers, chemistry and a wide range of biological oscillators can be projected from two main aspects: (i) suppression of oscillations as a regulator of certain pathological cases and (ii) a general control mechanism for technical systems. We distinguish two structurally distinct oscillation quenching types: oscillation (OD) and amplitude death (AD) phenomena. In this review we aim to set clear boundaries between these two very different oscillation quenching manifestations and demonstrate the importance for their correct identification from the aspect of theory as well as of applications. Moreover, we pay special attention to the physiological interpretation of OD and AD in a large class of biological systems, further underlying their different properties. Several open issues and challenges that await further resolving are also highlighted.

  10. Two-Photon Exchange in Elastic Electron-Proton Scattering: A QCD Factorization Approach

    SciTech Connect

    Kivel, Nikolai; Vanderhaeghen, Marc

    2009-08-28

    We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer Q{sup 2}. It is shown that the leading two-photon exchange amplitude behaves as 1/Q{sup 4}, and can be expressed in a model independent way in terms of the leading twist nucleon distribution amplitudes. Using several models for the nucleon distribution amplitudes, we provide estimates for existing data and for ongoing experiments.

  11. Localized finite-amplitude disturbances and selection of solitary waves

    PubMed

    Kliakhandler; Porubov; Velarde

    2000-10-01

    It turns out that evolution of localized finite-amplitude disturbances in perturbed KdV equation is qualitatively different compared with conventional small-amplitude initial conditions. Namely, relatively fast solitary waves, with one and the same amplitude and velocity, are formed ahead of conventional chaotic-like irregular structures. The amplitude and velocity of the waves, obtained from the asymptotic theory, are in excellent agreement with numerics. PMID:11089043

  12. Backward pion-nucleon scattering

    SciTech Connect

    F. Huang; Sibirtsev, Alex; Haidenbauer, Johann; Meissner, Ulf-G.

    2010-02-01

    A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the $N_\\alpha$, $N_\\gamma$, $\\Delta_\\delta$ and $\\Delta_\\beta$ trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable $u$, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a $G_{39}$ resonance with a mass of 2.83 GeV as member of the $\\Delta_{\\beta}$ trajectory from the corresponding Chew-Frautschi plot.

  13. Scattering in Quantum Lattice Gases

    NASA Astrophysics Data System (ADS)

    O'Hara, Andrew; Love, Peter

    2009-03-01

    Quantum Lattice Gas Automata (QLGA) are of interest for their use in simulating quantum mechanics on both classical and quantum computers. QLGAs are an extension of classical Lattice Gas Automata where the constraint of unitary evolution is added. In the late 1990s, David A. Meyer as well as Bruce Boghosian and Washington Taylor produced similar models of QLGAs. We start by presenting a unified version of these models and study them from the point of view of the physics of wave-packet scattering. We show that the Meyer and Boghosian-Taylor models are actually the same basic model with slightly different parameterizations and limits. We then implement these models computationally using the Python programming language and show that QLGAs are able to replicate the analytic results of quantum mechanics (for example reflected and transmitted amplitudes for step potentials and the Klein paradox).

  14. Subleading terms in the collinear limit of Yang-Mills amplitudes

    NASA Astrophysics Data System (ADS)

    Stieberger, Stephan; Taylor, Tomasz R.

    2015-11-01

    For two massless particles i and j, the collinear limit is a special kinematic configuration in which the particles propagate with parallel four-momentum vectors, with the total momentum P distributed as pi = xP and pj = (1 - x) P, so that sij ≡(pi +pj) 2 =P2 = 0. In Yang-Mills theory, if i and j are among N gauge bosons participating in a scattering process, it is well known that the partial amplitudes associated to the (single trace) group factors with adjacent i and j are singular in the collinear limit and factorize at the leading order into (N - 1)-particle amplitudes times the universal, x-dependent Altarelli-Parisi factors. We give a precise definition of the collinear limit and show that at the tree level, the subleading, non-singular terms are related to the amplitudes with a single graviton inserted instead of two collinear gauge bosons. To that end, we argue that in one-graviton Einstein-Yang-Mills amplitudes, the graviton with momentum P can be replaced by a pair of collinear gauge bosons carrying arbitrary momentum fractions xP and (1 - x) P.

  15. Focusing through a turbid medium by amplitude modulation with genetic algorithm

    NASA Astrophysics Data System (ADS)

    Dai, Weijia; Peng, Ligen; Shao, Xiaopeng

    2014-05-01

    Multiple scattering of light in opaque materials such as white paint and human tissue forms a volume speckle field, will greatly reduce the imaging depth and degrade the imaging quality. A novel approach is proposed to focus light through a turbid medium using amplitude modulation with genetic algorithm (GA) from speckle patterns. Compared with phase modulation method, amplitude modulation approach, in which the each element of spatial light modulator (SLM) is either zero or one, is much easier to achieve. Theoretical and experimental results show that, the advantage of GA is more suitable for low the signal to noise ratio (SNR) environments in comparison to the existing amplitude control algorithms such as binary amplitude modulation. The circular Gaussian distribution model and Rayleigh Sommerfeld diffraction theory are employed in our simulations to describe the turbid medium and light propagation between optical devices, respectively. It is demonstrated that the GA technique can achieve a higher overall enhancement, and converge much faster than others, and outperform all algorithms at high noise. Focusing through a turbid medium has potential in the observation of cells and protein molecules in biological tissues and other structures in micro/nano scale.

  16. Two-pion exchange potential and the {pi}N amplitude

    SciTech Connect

    M. T. Pena; Franz Gross; Yohanes Surya

    1996-05-01

    The authors discuss the two-pion exchange potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant {pi}N scattering amplitude which includes {Delta}, Roper, and D{sub 13} isobars, as well as contact terms and off-shell (non-pole) dressed nucleon terms. The {pi}N amplitude satisfies chiral symmetry constraints and fits {pi}N data below {approximately} 700 MeV pion energy. They find that this TPE potential can be well approximated by the exchange of an effective sigma and delta meson, with parameters close to the ones used in one-boson-exchange models that fit NN data below the pion production threshold.

  17. Counting loop diagrams: computational complexity of higher-order amplitude evaluation

    NASA Astrophysics Data System (ADS)

    van Eijk, E.; Kleiss, R.; Lazopoulos, A.

    2004-08-01

    We discuss the computational complexity of the perturbative evaluation of scattering amplitudes, both by the Caravaglios-Moretti algorithm and by direct evaluation of the individual diagrams. For a self-interacting scalar theory, we determine the complexity as a function of the number of external legs. We describe a method for obtaining the number of topologically inequivalent Feynman graphs containing closed loops, and apply this to 1- and 2-loop amplitudes. We also compute the number of graphs weighted by their symmetry factors, thus arriving at exact and asymptotic estimates for the average symmetry factor of diagrams. We present results for the asymptotic number of diagrams up to 10 loops, and prove that the average symmetry factor approaches unity as the number of external legs becomes large.

  18. Tissue characterization of skin ulcer for bacterial infection by multiple statistical analysis of echo amplitude envelope

    NASA Astrophysics Data System (ADS)

    Omura, Masaaki; Yoshida, Kenji; Kohta, Masushi; Kubo, Takabumi; Ishiguro, Toshimichi; Kobayashi, Kazuto; Hozumi, Naohiro; Yamaguchi, Tadashi

    2016-07-01

    To characterize skin ulcers for bacterial infection, quantitative ultrasound (QUS) parameters were estimated by the multiple statistical analysis of the echo amplitude envelope based on both Weibull and generalized gamma distributions and the ratio of mean to standard deviation of the echo amplitude envelope. Measurement objects were three rat models (noninfection, critical colonization, and infection models). Ultrasound data were acquired using a modified ultrasonic diagnosis system with a center frequency of 11 MHz. In parallel, histopathological images and two-dimensional map of speed of sound (SoS) were observed. It was possible to detect typical tissue characteristics such as infection by focusing on the relationship of QUS parameters and to indicate the characteristic differences that were consistent with the scatterer structure. Additionally, the histopathological characteristics and SoS of noninfected and infected tissues were matched to the characteristics of QUS parameters in each rat model.

  19. Two-pion-exchange potential and the {pi}{ital N} amplitude

    SciTech Connect

    Pena, M.T.; Gross, F.; Surya, Y.

    1996-11-01

    We discuss the two-pion-exchange (TPE) potential which emerges from a box diagram with one nucleon (the spectator) restricted to its mass shell, and the other nucleon line replaced by a subtracted, covariant {pi}{ital N} scattering amplitude which includes {Delta}, Roper, and {ital D}{sub 13} isobars, as well as contact terms and off-shell (nonpole) dressed nucleon terms. The {pi}{ital N} amplitude satisfies chiral symmetry constraints and fits {pi}{ital N} data below {approximately} 700 MeV pion energy. We find that this TPE potential can be well approximated by the exchange of an effective sigma and delta meson, with parameters close to the ones used in one-boson-exchange models that fit {ital NN} data below the pion production threshold. {copyright} {ital 1996 The American Physical Society.}

  20. A note on generalized hypergeometric functions, KZ solutions, and gluon amplitudes

    NASA Astrophysics Data System (ADS)

    Abe, Yasuhiro

    2016-06-01

    Some aspects of Aomoto's generalized hypergeometric functions on Grassmannian spaces Gr (k + 1 , n + 1) are reviewed. Particularly, their integral representations in terms of twisted homology and cohomology are clarified with an example of the Gr (2 , 4) case which corresponds to Gauss' hypergeometric functions. The cases of Gr (2 , n + 1) in general lead to (n + 1)-point solutions of the Knizhnik-Zamolodchikov (KZ) equation. We further analyze the Schechtman-Varchenko integral representations of the KZ solutions in relation to the Gr (k + 1 , n + 1) cases. We show that holonomy operators of the so-called KZ connections can be interpreted as hypergeometric-type integrals. This result leads to an improved description of a recently proposed holonomy formalism for gluon amplitudes. We also present a (co)homology interpretation of Grassmannian formulations for scattering amplitudes in N = 4 super Yang-Mills theory.

  1. Involution-dependent constants and the cancellation of divergences in the one-loop open-string amplitude

    SciTech Connect

    Nagao, G.

    1988-07-15

    We recalculate the bosonic one-loop open-string scattering amplitude using the results of the bosonic one-loop closed-string amplitude. The results show explicitly how the cancellation of divergences depends upon a set of involution-dependent constants which relate the torus to the cylinder and Moebius strip. Such a set of involution-dependent constants exists at each loop level and thus provides a means with which to study the cancellation of divergences and the connection between the world sheet and internal symmetries.

  2. Analytic Form of the Two-Loop Planar Five-Gluon All-Plus-Helicity Amplitude in QCD.

    PubMed

    Gehrmann, T; Henn, J M; Lo Presti, N A

    2016-02-12

    Virtual two-loop corrections to scattering amplitudes are a key ingredient to precision physics at collider experiments. We compute the full set of planar master integrals relevant to five-point functions in massless QCD, and use these to derive an analytical expression for the two-loop five-gluon all-plus-helicity amplitude. After subtracting terms that are related to the universal infrared and ultraviolet pole structure, we obtain a remarkably simple and compact finite remainder function, consisting only of dilogarithms. PMID:26918981

  3. A method to measure the distance among scatters and the scatters' diameter in artificial composite materials.

    PubMed

    Sun, Li; Ji, Aiming; Hu, Jialing; Zhu, Canyan; Zhang, Lijun; Yang, Jianfeng; Liu, Yongsong; Mao, Ling-Feng

    2016-04-01

    A new method to measure the distance among scatters, the density of scatters, and the scatters' diameter in artificial composite materials has been proposed. This method is based on detecting the reflection amplitude change (amp) of the echo signal reflected from scatters. Simulation results show that such a method is valid for the distance less than four times of the acoustic wavelength, because the coupling between the scatters can be neglected for the distance larger than four times of the acoustic wavelength. Therefore, this new measure method can be always valid by choosing appropriate frequency according to the scaling rule discussed in this paper. At the same time, it is found that the diameter of scatters is the half of the wavelength where the curve peak of the amp vs frequency occurs. It implies that such a new method can also be used to measure the diameter of scatters in solids and liquids, and even in PM2.5 pollution particles in air. PMID:26799127

  4. A new SERS: scattering enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Bixler, Joel N.; Yakovlev, Vladislav V.

    2014-03-01

    Raman spectroscopy is a powerful technique that can be used to obtain detailed chemical information about a system without the need for chemical markers. It has been widely used for a variety of applications such as cancer diagnosis and material characterization. However, Raman scattering is a highly inefficient process, where only one in 1011 scattered photons carry the needed information. Several methods have been developed to enhance this inherently weak effect, including surface enhanced Raman scattering and coherent anti-Stokes Raman scattering. These techniques suffer from drawbacks limiting their commercial use, such as the need for spatial localization of target molecules to a `hot spot', or the need for complex laser systems. Here, we present a simple instrument to enhance spontaneous Raman scattering using elastic light scattering. Elastic scattering is used to substantially increase the interaction volume. Provided that the scattering medium exhibits very low absorption in the spectral range of interest, a large enhancement factor can be attained in a simple and inexpensive setting. In our experiments, we demonstrate an enhancement of 107 in Raman signal intensity. The proposed novel device is equally applicable for analyzing solids, liquids, and gases.

  5. A probabilistic theory of electromagnetic wave scattering from a slightly random surface 2. Vertical polarization

    NASA Astrophysics Data System (ADS)

    Nakayama, J.; Sakata, M.; Ogura, H.

    1981-09-01

    The scattering of an electromagnetic wave from an infinite random surface is studied by the probabilistic method developed in a previous paper. For a vertical polarized plane wave incident on a slightly random and perfectly conductive surface a new stochastic wave solution involving multiple scattering is obtained. The stochastic solution is free from the divergence difficulty as in the small perturbation method but gives an anomaly such that for a grazing angle of incidence the coherent scattering almost disappears and instead the incoherent scattering becomes dominant. In terms of the stochastic solution, a number of statistical properties of the scattering are calculated concretely for a perfectly conductive surface, such as the complex amplitude of the coherent scattering, the variance of the electric field, the optical theorem describing the power relation between the coherent and the incoherent scattering, the angular distribution of the incoherent scattering, the scattering cross section per unit area, and the surface wave flow, which are all illustrated in the figures.

  6. Confocal zero-angle dynamic depolarized light scattering.

    PubMed

    Potenza, M A C; Sanvito, T; Alaimo, M D; Degiorgio, V; Giglio, M

    2010-01-01

    We present a novel Dynamic Depolarized Scattering method based on a tight confocal, zero scattering angle, heterodyne scheme. The method is highly immune from parasitic multiple-scattering contributions, so that it can operate with non-index-matched samples presenting large turbidity. It provides measurements of both rotational and translational diffusion coefficients, the latter via number fluctuation spectroscopy. In addition, the amplitude ratio between the two baselines for the fast rotational mode and the slow translational mode can be used to determine the particles intrinsic birefringence. PMID:20087622

  7. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, D.U.L.; Conway, P.H.

    1994-11-15

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The phase and amplitude of subsequent are modified by output signals from the correction system. 11 figs.

  8. Feed-forward digital phase and amplitude correction system

    DOEpatents

    Yu, David U. L.; Conway, Patrick H.

    1994-01-01

    Phase and amplitude modifications in repeatable RF pulses at the output of a high power pulsed microwave amplifier are made utilizing a digital feed-forward correction system. A controlled amount of the output power is coupled to a correction system for processing of phase and amplitude information. The correction system comprises circuitry to compare the detected phase and amplitude with the desired phase and amplitude, respectively, and a digitally programmable phase shifter and attenuator and digital logic circuitry to control the phase shifter and attenuator. The Phase and amplitude of subsequent are modified by output signals from the correction system.

  9. Characterization of Source and Wave Propagation Effects of Volcano-seismic Events and Tremor Using the Amplitude Source Location Method

    NASA Astrophysics Data System (ADS)

    Kumagai, H.; Londono, J. M.; López, C. M.; Ruiz, M. C.; Mothes, P. A.; Maeda, Y.

    2015-12-01

    We propose application of the amplitude source location (ASL) method to characterize source and wave propagation effects of volcano-seismic events and tremor observed at different volcanoes. We used this method to estimate the source location and source amplitude from high-frequency (5-10 Hz) seismic amplitudes under the assumption of isotropic S-wave radiation. We estimated the cumulative source amplitude (Is) as the offset value of the time-integrated envelope of the vertical seismogram corrected for geometrical spreading and medium attenuation in the 5-10 Hz band. We studied these parameters of tremor signals associated with eruptions and explosion events at Tungurahua volcano, Ecuador; long-period (LP) events at Cotopaxi volcano, Ecuador; and LP events at Nevado del Ruiz volcano, Colombia. We identified two types of eruption tremor at Tungurahua; noise-like inharmonic waveforms and harmonic oscillatory signals. We found that Is increased linearly with increasing source amplitude for explosion events and LP events, and that Is increased exponentially with increasing source amplitude for inharmonic eruption tremor signals. The source characteristics of harmonic eruption tremor signals differed from those of inharmonic tremor signals. The Is values we estimated for inharmonic eruption tremor were consistent with previous estimates of volumes of tephra fallout. The linear relationship between the source amplitude and Is for LP events can be explained by the wave propagation effects in the diffusion model for multiple scattering assuming a diffusion coefficient of 105 m2/s and an intrinsic Q factor of around 50. The resultant mean free path is approximately 100 m. Our results suggest that Cotopaxi and Nevado del Ruiz volcanoes have similar highly scattering and attenuating structures. Our approach provides a systematic way to compare the size of volcano-seismic signals observed at different volcanoes. The scaling relations among source parameters that we identified

  10. Leading Wave Amplitude of a Tsunami

    NASA Astrophysics Data System (ADS)

    Kanoglu, U.

    2015-12-01

    Okal and Synolakis (EGU General Assembly 2015, Geophysical Research Abstracts-Vol. 17-7622) recently discussed that why the maximum amplitude of a tsunami might not occur for the first wave. Okal and Synolakis list observations from 2011 Japan tsunami, which reached to Papeete, Tahiti with a fourth wave being largest and 72 min later after the first wave; 1960 Chilean tsunami reached Hilo, Hawaii with a maximum wave arriving 1 hour later with a height of 5m, first wave being only 1.2m. Largest later waves is a problem not only for local authorities both in terms of warning to the public and rescue efforts but also mislead the public thinking that it is safe to return shoreline or evacuated site after arrival of the first wave. Okal and Synolakis considered Hammack's (1972, Ph.D. Dissertation, Calif. Inst. Tech., 261 pp., Pasadena) linear dispersive analytical solution with a tsunami generation through an uplifting of a circular plug on the ocean floor. They performed parametric study for the radius of the plug and the depth of the ocean since these are the independent scaling lengths in the problem. They identified transition distance, as the second wave being larger, regarding the parameters of the problem. Here, we extend their analysis to an initial wave field with a finite crest length and, in addition, to a most common tsunami initial wave form of N-wave as presented by Tadepalli and Synolakis (1994, Proc. R. Soc. A: Math. Phys. Eng. Sci., 445, 99-112). We compare our results with non-dispersive linear shallow water wave results as presented by Kanoglu et al. (2013, Proc. R. Soc. A: Math. Phys. Eng. Sci., 469, 20130015), investigating focusing feature. We discuss the results both in terms of leading wave amplitude and tsunami focusing. Acknowledgment: The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 603839 (Project ASTARTE - Assessment, Strategy and Risk

  11. Scattering of stringy states in compactified closed bosonic string

    NASA Astrophysics Data System (ADS)

    Maharana, Jnanadeva

    2015-07-01

    We present scattering of stringy states of closed bosonic string compactified on torus Td. We focus our attention on scattering of moduli and gauge bosons. These states appear when massless excitations such as graviton and antisymmetric tensor field of the uncompactified theory are dimensionally reduced to lower dimension. The toroidally compactified theory is endowed with the T-duality symmetry, O (d, d). Therefore, it is expected that the amplitude for scattering of such states will be T-duality invariant. The formalism of Kawai-Lewellen-Tye is adopted and appropriately tailored to construct the vertex operators of moduli and gauge bosons. It is shown, in our approach, that N-point amplitude is T-duality invariant. We present illustrative examples for the four point amplitude to explicitly demonstrate the economy of our formalism when three spatial dimensions are compactified on T3. It is also shown that if we construct an amplitude with a set of 'initial' backgrounds, the T-duality operation transforms it to an amplitude associated with another set backgrounds. We propose a modified version of KLT approach to construct vertex operators for nonabelian massless gauge bosons which appear in certain compactification schemes.

  12. Robust discrimination of permanent scatterers using Cameron Decomposition

    NASA Astrophysics Data System (ADS)

    Kouroupis, G.; Elias, P.; Anastassopoulos, V.

    2014-10-01

    One of the main difficulties encountered in Differential Interferometry (DInSAR) applications is temporal and spatial decorrelation over time. Single pixels, called Permanent Scatterers (PS), overcome this difficulty since they are coherent over time and over wide look-angle variations. Permanent Scatterers identification using interferographic techniques is unfeasible since they require the use of many acquisitions. Samsonov and Tiampo have presented a technique that selects Permanent Scatterers by analyzing their Polarization Phase Difference (PPD). The PPD approach would work just fine looking for single bounce scatterers because they are invariant to any initial arbitrary rotation between the scatterer and the radar Line of Sight (LOS). We propose to replace the PPD technique with Cameron's Coherent Target Decomposition (CTD) because it is more accurate in finding the single and double bounce scatterers as it eliminates the initial orientation angle of the scatterer. Additionally, Cameron's CTD is capable of recognizing more scattering mechanisms which means that more pixels, depending on their amplitude and stability over time, can be classified as Permanent Scatterers. A sample scene of fully polarimetric SAR image depicting the San Francisco bay was employed for experimentation. Our results demonstrate the superiority of the Cameron's CTD approach compared to PPD's approach for the selection of pixels classified as Permanent Scatterers.

  13. Imaging scattering orientation with spatial frequency domain imaging

    PubMed Central

    Konecky, Soren D.; Rice, Tyler; Durkin, Anthony J.; Tromberg, Bruce J.

    2011-01-01

    Optical imaging techniques based on multiple light scattering generally have poor sensitivity to the orientation and direction of microscopic light scattering structures. In order to address this limitation, we introduce a spatial frequency domain method for imaging contrast from oriented scattering structures by measuring the angular-dependence of structured light reflectance. The measurement is made by projecting sinusoidal patterns of light intensity on a sample, and measuring the degree to which the patterns are blurred as a function of the projection angle. We derive a spatial Fourier domain solution to an anisotropic diffusion model. This solution predicts the effects of bulk scattering orientation on the amplitude and phase of the projected patterns. We introduce a new contrast function based on a scattering orientation index (SOI) which is sensitive to the degree to which light scattering is directionally dependent. We validate the technique using tissue simulating phantoms, and ex vivo samples of muscle and brain. Our results show that SOI is independent of the overall amount of bulk light scattering and absorption, and that isotropic versus oriented scattering structures can be clearly distinguished. We determine the orientation of subsurface microscopic scattering structures located up to 600 μm beneath highly scattering (μ′s = 1.5 mm−1) material. PMID:22191918

  14. High energy parton-parton elastic scattering in QCD

    SciTech Connect

    Tang, W.K.

    1993-08-01

    We show that the high energy limit of quark-quark, or gluon-gluon, elastic scattering is calculable in terms of the BFKL pomeron when {minus}t {much_gt} {Lambda}{sub QCD}{sup 2}. Surprisingly, this on-shell amplitudes does not have infrared divergences in the high energy limit.

  15. Unitary formalism for scattering from a hard corrugated wall

    NASA Astrophysics Data System (ADS)

    Brown, G. C.; Celli, V.; Coopersmith, M.; Haller, M.

    1982-07-01

    We obtain two coupled integral equations for the diffraction of waves from a hard corrugated surface. This rearrangement is shown to be equivalent to the integral equation for the scattering amplitude obtained by an application of the Rayleigh method. The formalism presented here, analogous to K-matrix theory, makes the unitarity of the theory apparent at each stage of approximation.

  16. High energy scattering of Dirac particles on smooth potentials

    NASA Astrophysics Data System (ADS)

    Han, Nguyen Suan; Dung, Le Anh; Xuan, Nguyen Nhu; Thang, Vu Toan

    2016-08-01

    The derivation of the Glauber type representation for the high energy scattering amplitude of particles of spin 1/2 is given within the framework of the Dirac equation in the Foldy-Wouthuysen (FW) representation and two-component formalism. The differential cross-sections on the Yukawa and Gaussian potentials are also considered and discussed.

  17. OBE approximation of NN scattering in bag-model QCD

    NASA Astrophysics Data System (ADS)

    Bakker, B. L. G.; Maslow, J. N.; Weber, H. J.

    1981-09-01

    A partial-wave helicity-state analysis of nucleon-nucleon scattering is carried out in momentum space. Its basis is a one-boson and two-pion exchange amplitude from bag-model quantum chromodynamics. The resulting phase shifts and bound-state parameters of the deuteron are compared with data up to laboratory energies of ≈350 MeV.

  18. Exclusive two-photon processes: Tests of QCD at the amplitude level

    SciTech Connect

    Brodsky, S.J.

    1992-07-01

    Exclusive two-photon processes at large momentum transfer, particularly Compton scattering {gamma}p{yields}{gamma}p and its crossed-channel reactions {gamma}{gamma}{yields}{bar p}p and {bar p}p{yields}{gamma}{gamma}, can provide definitive information on the bound-state distributions of quarks in hadrons at the amplitude level. Recent theoretical work has shown that QCD predictions based on the factorization of long and short distance physics are already applicable at momentum transfers of order of a few GeV.

  19. Calculations of kaonic nuclei based on chiral meson-baryon amplitudes

    NASA Astrophysics Data System (ADS)

    Gazda, Daniel; Mareš, Jiří

    2013-09-01

    In-medium KbarN scattering amplitudes developed within a chirally motivated coupled-channel model are used to construct K- nuclear potentials for calculations of K- nuclear quasi-bound states. Self-consistent evaluations yield K- potential depths -Re VK(ρ0) of order 100 MeV. Dynamical polarization effects and two-nucleon KbarNN→YN absorption modes are discussed. The widths ΓK of allK- nuclear quasi-bound states are comparable or even larger than the corresponding binding energies BK, exceeding considerably the energy level spacing.

  20. Multiple scattering of scalar waves by point scatterers in one dimension. I

    SciTech Connect

    Haacke, E.M.; Foldy, L.L.

    1981-04-01

    We discuss the problem of scalar wave multiple scattering in one dimension on a target of n identical fixed scatterers with delta-function potentials. We consider in detail a statistical ensemble of configurations of scatterers whose positions are uniformly distributed throughout the scattering region. We succeed in analytically performing a configurational average (over all scatterer positions) for the wave function for the problem of a transmitted wave with constant amplitude. We discuss the relationship between this problem and the standard problem of an incident wave with constant amplitude. From the simple closed form for the average of the wave function, the optical potential for the system is obtained. We then present the large and small incident particle wavelength limits (with respect to the length (L) of the scattering region) for both the average of the wave function and the optical potential. We also examine the question as to where the optical potential can be approximated by the form it takes in the limit of infinite n. (The question of where in parameter space this occurs and how well the transmitted and reflected waves can be predicted with this form is discussed in the following paper.) Furthermore, we consider the large incident particle wave number limit for the average wave function and the optical potential for a general distribution of the scatterer positions in the limit of both n and L approaching infinity but with n/L remaining fixed. Lastly, knowing the simple closed form for the average of the wave function, we prove that the effective field approximation becomes exact in the limit of infinite n with all other parameters held fixed.

  1. Optics as Scattering

    ERIC Educational Resources Information Center

    di Francia, Giuliano Toraldo

    1973-01-01

    The art of deriving information about an object from the radiation it scatters was once limited to visible light. Now due to new techniques, much of the modern physical science research utilizes radiation scattering. (DF)

  2. A new polarisation amplitude bias reduction method.

    NASA Astrophysics Data System (ADS)

    Vidal, M.; Leahy, J. P.; Dickinson, C.

    2016-06-01

    Polarisation amplitude estimation is affected by a positive noise bias, particularly important in regions with low signal-to-noise ratio (SNR). We present a new approach to correct for this bias in the case there is additional information about the polarisation angle. We develop the `known-angle estimator' that works in the special case when there is an independent and high signal-to-noise ratio (≳ 2σ) measurement of the polarisation angle. It is derived for the general case where the uncertainties in the Q, U Stokes parameters are not symmetric. This estimator completely corrects for the polarisation bias if the polarisation angle is perfectly known. In the realistic case, where the angle template has uncertainties, a small residual bias remains, but that is shown to be much smaller that the one left by other classical estimators. We also test our method with more realistic data, using the noise properties of the three lower frequency maps of WMAP. In this case, the known-angle estimator also produces better results than methods that do not include the angle information. This estimator is therefore useful in the case where the polarisation angle is expected to be constant over different data sets with different SNR.

  3. Automated phase/amplitude EHF measurement system

    NASA Astrophysics Data System (ADS)

    Potts, B. M.

    1981-05-01

    An automated, computer-controlled measurement system capable of conducting transmission and reflection measurements on components over the 40 to 47 GHz frequency range is described. The measurement system utilizes harmonic mixing in conjunction with a phase locked, dual channel receiver to downconvert signals in the 7 GHz bandwidth to a lower intermediate frequency (1 KHz) where phase and amplitude measurements are made. The system is capable of operating over a dynamic range in excess of 50 dB when used with an EHF source producing a minimum -10 dBm output. Following a description of the system and its operation, some performance characteristics are presented. The measurement system accuracy is demonstrated using two types of reference standards: (1) a rotary vane attenuator for the transmission measurements, and (2) a set of reduced-height waveguide VSWR standards for the return loss measurements. Results obtained using these standards have indicated that measurement accuracies of 0.25 dB and 3 deg are achievable over a 50 dB dynamic range.

  4. A generalized fidelity amplitude for open systems.

    PubMed

    Gorin, T; Moreno, H J; Seligman, T H

    2016-06-13

    We consider a central system which is coupled via dephasing to an open system, i.e. an intermediate system which in turn is coupled to another environment. Considering the intermediate and far environment as one composite system, the coherences in the central system are given in the form of fidelity amplitudes for a certain perturbed echo dynamics in the composite environment. On the basis of the Born-Markov approximation, we derive a master equation for the reduction of that dynamics to the intermediate system alone. In distinction to an earlier paper (Moreno et al 2015 Phys. Rev. A 92, 030104. (doi:10.1103/PhysRevA.92.030104)), where we discussed the stabilizing effect of the far environment on the decoherence in the central system, we focus here on the possibility of using the measurable coherences in the central system for probing the open quantum dynamics in the intermediate system. We illustrate our results for the case of chaotic dynamics in the near environment, where we compare random matrix simulations with our analytical result. PMID:27140969

  5. Sensitivity to changes in amplitude envelope

    NASA Astrophysics Data System (ADS)

    Gallun, Erick; Hafter, Ervin R.; Bonnel, Anne-Marie

    2002-05-01

    Detection of a brief increment in a tonal pedestal is less well predicted by energy-detection (e.g., Macmillan, 1973; Bonnel and Hafter, 1997) than by sensitivity to changes in the stimulus envelope. As this implies a mechanism similar to an envelope extractor (Viemeister, 1979), sinusoidal amplitude modulation was used to mask a single ramped increment (10, 45, or 70 ms) added to a 1000-ms pedestal with carrier frequency (cf)=477 Hz. As in informational masking (Neff, 1994) and ``modulation-detection interference'' (Yost and Sheft, 1989), interference occurred with masker cfs of 477 and 2013 Hz. While slight masking was found with modulation frequencies (mfs) from 16 to 96 Hz, masking grew inversely with still lower mfs, being greatest for mf=4 Hz. This division is reminiscent of that said to separate sensations of ``roughness'' and ``beats,'' respectively (Terhardt, 1974), with the latter also being related to durations associated with auditory groupings in music and speech. Importantly, this result held for all of the signal durations and onset-offset ramps tested, suggesting that an increment on a pedestal is treated as a single auditory object whose detection is most difficult in the presence of other objects (in this case, ``beats'').

  6. The pulsed amplitude unit for the SLC

    SciTech Connect

    Rolfe, J.; Browne, M.J.; Jobe, R.K.

    1987-02-01

    There is a recurring requirement in the SLC for the control of devices such as magnets, phase shifters, and attenuators on a beam-by-beam basis. The Pulsed Amplitude Unit (PAU) is a single width CAMAC module developed for this purpose. It provides digitally programmed analog output voltages on a beam-by-beam basis. Up to 32 preprogrammed values of output voltage are available from the single analog output of the module, and any of these values can be associated with any of the 256 possible SLC beam definitions. A 12-bit Analog-to-Digital Converter (ADC) digitizes an analog input signal at the appropriate beam time and stores it in a buffer memory. This feature is normally used to monitor the response of the device being controlled by the PAU at each beam time. Initial application of the PAU is a part of the system that controls the output of Klystrons in the SLC. The PAU combines several different functions in a single module. In order to accommodate these functions in a single width CAMAC module, field programmed logic is used extensively. Field Programmable Logic Arrays, Programmed Array Logic, and a Field Programmable Logic Sequencer are employed.

  7. A new polarization amplitude bias reduction method

    NASA Astrophysics Data System (ADS)

    Vidal, Matias; Leahy, J. P.; Dickinson, C.

    2016-09-01

    Polarization amplitude estimation is affected by a positive noise bias, particularly important in regions with low signal-to-noise ratio (SNR). We present a new approach to correct for this bias in the case there is additional information about the polarization angle. We develop the `known-angle estimator' that works in the special case when there is an independent and high SNR (≳ 2σ) measurement of the polarization angle. It is derived for the general case where the uncertainties in the Q, U Stokes parameters are not symmetric. This estimator completely corrects for the polarization bias if the polarization angle is perfectly known. In the realistic case, where the angle template has uncertainties, a small residual bias remains, but that is shown to be much smaller that the one left by other classical estimators. We also test our method with more realistic data, using the noise properties of the three lower frequency maps of Wilkinson Microwave Anisotropy Probe. In this case, the known-angle estimator also produces better results than methods that do not include the angle information. This estimator is therefore useful in the case where the polarization angle is expected to be constant over different data sets with different SNR.

  8. New Fermionic Soft Theorems for Supergravity Amplitudes.

    PubMed

    Chen, Wei-Ming; Huang, Yu-Tin; Wen, Congkao

    2015-07-10

    Soft limits of a massless S matrix are known to reflect the symmetries of the theory. In particular, for theories with Goldstone bosons, the double-soft limit of scalars reveals the coset structure of the vacuum manifold. In this Letter, we propose that such universal double-soft behavior is not only true for scalars, but also for spin-1/2 particles in four dimensions and fermions in three dimensions. We first consider the Akulov-Volkov theory and demonstrate that the double-soft limit of Goldstinos yields the supersymmetry algebra. More surprisingly, we also find that amplitudes in 4≤N≤8 supergravity theories in four dimensions as well as N=16 supergravity in three dimensions behave universally in the double-soft-fermion limit, analogous to the scalar ones. The validity of the new soft theorems at loop level is also studied. The results for supergravity are beyond what is implied by supersymmetry Ward identities and may impose nontrivial constraints on the possible counterterms for supergravity theories. PMID:26207460

  9. Resonating Rays in Light Ion Scattering from AN Optical Potential.

    NASA Astrophysics Data System (ADS)

    Stoyanov, Basil John

    Recent experimental investigations reveal that resonances of composite ion-ion systems are a general phenomenon in light- and heavy-ion scattering. The experimentally observed phenomenon known as the anomalous large-angle scattering (ALAS) of alpha-particle from certain isotopes, such as (alpha)-('40)Ca, manifests itself in the form of successive peaks in the back-scattering excitation function. Earlier theoretical studies were mainly concentrated either on the surface-wave or geometrical-wave description of these phenomena, whereas the pont of view taken here, which is based on the results of physical acoustics, is that the ion-ion scattering amplitude contains both the surface-wave and the geometrical-wave contributions. Therefore a comprehensive approach would be to investigate both of these contributions simultaneously. This is achieved in the present work through a decomposition, by applying the Sommerfeld-Watson and Imai transformations, of the scattering amplitude into its ingredients and by analyzing both the resulting geometrical rays and the surface waves in terms of resonances. This procedure generates a precise mathematical description of resonance processes in ion scattering (via the S-function poles) and at the same time leads in a semi -classical framework to their thorough physical interpretation (via the generalized Bohr-Sommerfeld quantization condition). The existence of resonances in both the geometrical and surface waves emerges from such a description, and is exemplified by numerical calculations for (alpha)-('40)Ca elastic scattering.

  10. Improvement in underwater phase measurement of an amplitude-modulated laser beam by polarimetric techniques.

    PubMed

    Bartolini, L; De Dominicis, L; Fornetti, G; Francucci, M; Guarneri, M; Poggi, C; Ricci, R

    2007-06-01

    The phase of the amplitude-modulated radiation reflected by a Lambertian target immersed in water was measured by using a linearly and circularly polarized sounding laser beam. Different values of the water extinction coefficient in the range of 0.06 - 2 m(-1) were realized by adding skim milk as a scattering element. It is shown that very efficient rejection of optical noise, resulting in reliable phase measurements, is accomplished with a cross-polarized and copolarized detection scheme for linear and circular polarization, respectively. The experiment demonstrates that phase measurements are very sensitive to optical noise suppression and that, as far as single scattering is the main involved mechanism, significant improvements can be achieved by adopting a polarization control on both the transmitter and the receiver stages of the apparatus. PMID:17546135

  11. Observations of Large Amplitude, Monochromatic Whistlers at Stream Interaction Regions

    NASA Astrophysics Data System (ADS)

    Breneman, A. W.; Cattell, C. A.; Kersten, K.; Wilson, L. B., III; Kellogg, P. J.; Schreiner, S.; Goetz, K.

    2009-12-01

    We present the first solar wind observations of monochromatic waveforms in the frequency range 10-100 Hz, consistent with the whistler mode. These waveforms are only observable in the high time resolution waveform data provided by the Time Domain Sampler (TDS) instrument on STEREO. The whistlers occur in groups that are strongly correlated with stream interaction regions (SIRs). The groups persist from a few seconds to minutes and are observed at 90% of SIRs and 20% of shocks from available 2007 data. A more detailed look shows that the whistler groups are closely related to sudden disturbances of the solar wind magnetic field and plasma. An example is presented of whistlers in association with a small reverse shock upstream of a SIR. Wave amplitudes range from a few to >25mV/m peak-to-peak, one to four orders of magnitude larger than any previous observations of whistler mode waves near SIRs or shocks. The whistlers are oblique by propagating with a large electrostatic component and are right-handed elliptically polarized in the spacecraft frame. We suggest that, due to the oblique and monochromatic nature of these waves, an electron or ion beam instability may be responsible for their creation. Test particle simulations show that the waves can interact strongly with halo (>60 eV) electrons. Test electrons were scattered by 10s of degrees and energized/de-energized by up to 50% in a few 10s of msec. Thus these whistlers may play an important role in the dynamics of solar wind electrons within SIRs and near some shocks.

  12. Beam normal spin asymmetry in the quasireal Compton scattering approximation

    SciTech Connect

    Gorchtein, M.

    2006-05-15

    The two-photon exchange contribution to the single spin asymmetries with the spin orientation normal to the reaction plane is discussed for elastic electron-proton scattering in the equivalent photon approximation. In this case, the hadronic part of the two-photon exchange amplitude describes real Compton scattering (RCS). We show that in the case of the beam normal spin asymmetry this approximation selects only the photon helicity flip amplitudes of RCS. At low energies, we make use of unitarity and estimate the contribution of the {pi}N multipoles to the photon helicity flip amplitudes. In the Regge regime, the quasi-RCS (QRCS) approximation allows for a contribution from two-pion exchange, and we provide an estimate of such contributions.

  13. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma.

    PubMed

    Tejero, E M; Crabtree, C; Blackwell, D D; Amatucci, W E; Mithaiwala, M; Ganguli, G; Rudakov, L

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10(-6) times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth's plasma environment. PMID:26647962

  14. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

    PubMed Central

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10−6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment. PMID:26647962

  15. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

    NASA Astrophysics Data System (ADS)

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.

    2015-12-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10-6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment.

  16. Attenuation of Elastic Waves due to Scattering from Spherical Cavities and Elastic Inclusions.

    NASA Astrophysics Data System (ADS)

    Hinders, Mark Karl

    1990-01-01

    The attenuation of elastic waves due to scattering from a spherical inclusion of arbitrary size in an infinitely extended medium is investigated. The spherical scatterer and the exterior medium are isotropic, homogeneous, and linearly elastic, but of arbitrarily differing material parameters, with compressional and shear waves supported in both media. Exact expressions for scattered and transmitted fields caused by an incident plane compressional or shear wave of unit amplitude are calculated analytically and general expressions for extinction and scattering cross -sections are derived for both lossy and lossless scattering. Application to ultrasonic determination of porosity in cast aluminum is investigated.

  17. Siegert pseudostate formulation of scattering theory: General three-dimensional case

    NASA Astrophysics Data System (ADS)

    Krainov, Lev O.; Batishchev, Pavel A.; Tolstikhin, Oleg I.

    2016-04-01

    This paper generalizes the Siegert pseudostate (SPS) formulation of scattering theory to arbitrary finite-range potentials without any symmetry in the three-dimensional (3D) case. The orthogonality and completeness properties of 3D SPSs are established. The SPS expansions for scattering states, outgoing-wave Green's function, scattering matrix, and scattering amplitude, that is, all major objects of scattering theory, are derived. The theory is illustrated by calculations for several model potentials. The results enable one to apply 3D SPSs as a purely discrete basis capable of representing both discrete and continuous spectra in solving various stationary and time-dependent quantum-mechanical problems.

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

    SciTech Connect

    Huang, Danhong; Cardimona, Dave; Easter, Michelle; Gumbs, Godfrey; Maradudin, A. A.; Lin, Shawn-Yu; Zhang, Xiang

    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.

  19. Refraction and scattering of sound by a shear layer

    NASA Technical Reports Server (NTRS)

    Schlinker, R. H.; Amiet, R. K.

    1980-01-01

    The angle and amplitude changes for acoustic waves refracted by a circular open jet shear layer were determined. The generalized refraction theory was assessed experimentally for on axis and off axis acoustic source locations as source frequency varied from 1 kHz to 10 kHz and free stream Mach number varied from 0.1 to 0.4. Angle and amplitude changes across the shear layer show good agreement with theory. Experiments confirm that the refraction theory is independent of shear layer thickness, acoustic source frequency, and source type. A generalized theory is, thus, available for correcting far field noise data acquired in open jet test facilities. The effect of discrete tone scattering by the open jet turbulent shear layer was also studied. Scattering effects were investigated over the same Mach number range as frequency varied from 5 kHz to 15 kHz. Attenuation of discrete tone amplitude and tone broadening were measured as a function of acoustic source position and radiation angle. Scattering was found to be stronger at angles close to the open jet axis than at 90 deg, and becomes stronger as the acoustic source position shifts downstream. A scattering analysis provided an estimate of the onset of discrete tone scattering.

  20. Submarine UXO Detection Using Resonance Scattering Sonar

    NASA Astrophysics Data System (ADS)

    Gritto, R.; Korneev, V. A.; Johnson, L. R.

    2010-12-01

    Resonance scattered waves from a dataset collected in a pond setting were utilized to detect and characterize unexploded ordnance (UXO) located proud off the bottom sediments. Furthermore, it was investigated whether UXO can be characterized by their size and filler velocities and whether medium velocities can be derived from the field data. Analysis of the field data was supported by numerical modeling. It was found that resonance scattered waves were present in all numerical data and in the field cases of a proud sphere and a buried cylinder. In all other cases of proud UXO the field data revealed frequency dependent scattered waves that were part of the direct reflected waves. Imaging UXO with monochromatic data produces surprisingly good results considering that in most investigated cases a small fraction of the data with very low amplitudes were used in comparison to data typically used for Kirchhoff migration or SAS imaging. The images derived from resonance scattered waves were generated by data obtained from narrow passbands throughout the whole frequency spectrum such that different parts of the UXO can be illumination separately. Range resolution is reduced when imaging is done with monochromatic signals. However, the image resolution can be dramatically improved by adding data from different azimuth as was demonstrated for the cases of a proud sphere and bomb. A suite of results ranging from numerical calculations to field data will be presented to show how the properties of resonance scattering can be utilized to detect, locate and characterize an UXO in littoral environments.

  1. Acousto-optic tomography using amplitude-modulated focused ultrasound and a near-IR laser

    SciTech Connect

    Yao Yong; Xing Da; He Yonghong; Ueda, Ken-ichi

    2001-11-30

    A novel tomographic method that can be applied in strongly scattering optical media is proposed. 1-MHz focused ultrasound is used to tag the scattering photons in the biological tissue; it carries a 10-KHz sinusoidal wave to act as a detection wave through amplitude-modulation (AM). The scattering photons that come from the focused zone carry the modulated information. Their optoelectronic signal is demodulated by real-time FFT. By detecting and discriminating ultrasound-modulated information carried by scattered photons, the optical tomographic images of the media simulating biological tissue and of a buried object are reconstructed by the AM spectral intensity. This ultrasound-tagged optical tomography can be applied to tissue structures with different optical parameters. For the first time, by using this method, we obtained the tomographic image of a 5 mm-wide soft rubber cube buried in a biological tissue-simulating media with a detecting depth of 30 mm. (laser applications and other topics in quantum electronics)

  2. Phase Shift Analyses of pp Elastic Scattering between 500 and 800 MeV

    NASA Astrophysics Data System (ADS)

    Nagata, J.; Yoshino, H.; Matsuda, M.

    1995-03-01

    The single-energy phase-shift analyses of pp elastic scattering have been made by using double-spin and triple-spin correlation parameters measured at SIN in the incident energy region TL = 447-580 MeV, and at LAMPF at TL = 735 MeV. The scattering amplitudes have been almost uniquely determined at TL = 500, 530, 560, 580 and 735 MeV. The Argand diagrams of 1D2-, 3P2- and 3F3-wave amplitudes show counter clockwise behavior. The obtained I = 1 amplitudes in the present analysis will contribute to the determination of the I = 0 amplitudes of np scattering in the same energy region.

  3. Theory of direct scattering of neutral and charged atoms

    NASA Technical Reports Server (NTRS)

    Franco, V.

    1979-01-01

    The theory for direct elastic and inelastic collisions between composite atomic systems formulated within the framework of the Glauber approximation is presented. It is shown that the phase-shift function is the sum of a point Coulomb contribution and of an expression in terms of the known electron-hydrogen-atom and proton-hydrogen-atom phase shift function. The scattering amplitude is reexpressed, the pure Coulomb scattering in the case of elastic collisions between ions is isolated, and the exact optical profile function is approximated by a first-order expansion in Glauber theory which takes into account some multiple collisions. The approximate optical profile function terms corresponding to interactions involving one and two electrons are obtained in forms of Meijer G functions and as a one-dimensional integral, and for collisions involving one or two neutral atoms, the scattering amplitude is further reduced to a simple closed-form expression.

  4. Halo-independent methods for inelastic dark matter scattering

    SciTech Connect

    Bozorgnia, Nassim; Schwetz, Thomas; Herrero-Garcia, Juan; Zupan, Jure E-mail: juan.a.herrero@uv.es E-mail: jure.zupan@cern.ch

    2013-07-01

    We present halo-independent methods to analyze the results of dark matter direct detection experiments assuming inelastic scattering. We focus on the annual modulation signal reported by DAMA/LIBRA and present three different halo-independent tests. First, we compare it to the upper limit on the unmodulated rate from XENON100 using (a) the trivial requirement that the amplitude of the annual modulation has to be smaller than the bound on the unmodulated rate, and (b) a bound on the annual modulation amplitude based on an expansion in the Earth's velocity. The third test uses the special predictions of the signal shape for inelastic scattering and allows for an internal consistency check of the data without referring to any astrophysics. We conclude that a strong conflict between DAMA/LIBRA and XENON100 in the framework of spin-independent inelastic scattering can be established independently of the local properties of the dark matter halo.

  5. Scattering equations and Kawai-Lewellen-Tye orthogonality

    NASA Astrophysics Data System (ADS)

    Cachazo, Freddy; He, Song; Yuan, Ellis Ye

    2014-09-01

    Several recent developments point to the fact that rational maps from n-punctured spheres to the null cone of D-dimensional momentum space provide a natural language for describing the scattering of massless particles in D dimensions. In this paper we identify and study equations relating the kinematic invariants sab and the puncture locations σc, which we call the scattering equations. We provide an inductive algorithm in the number of particles for their solutions and prove a remarkable property which we call Kawai-Lewellen-Tye (KLT) orthogonality. In a nutshell, KLT orthogonality means that "Parke-Taylor" vectors constructed from the solutions to the scattering equations are mutually orthogonal with respect to the KLT bilinear form. We end with comments on possible connections to gauge theory and gravity amplitudes in any dimension and to the high-energy limit of string theory amplitudes.

  6. Further study of a new dispersion relation for electron-atom scattering

    SciTech Connect

    Bhatia, A.K.; Temkin, A.

    1988-03-01

    A new recently proposed dispersion relation (DR) (Temkin, Bhatia, and Kim, J. Phys. B 19, L707 (1986)) is tested for e-He scattering; the results show that the new DR is not satisfied. Therefore we start to investigate the analytic structure of the difference amplitude, previously assumed to be nonsingular, on the negative scattering energy axis. Even under severe approximations we find that the difference amplitude contains both poles and branch points. This suggests, however, a useful approximation of these contributions to the DR which gives very satisfactory agreement in both e-H and e-He scattering. We conclude with some brief general remarks on this problem.

  7. Acoustic and photoacoustic scattering from transverse isotropic tissues

    NASA Astrophysics Data System (ADS)

    Sheu, Yae-lin; Ho, Yi-Ching; Li, Pai-Chi

    2013-03-01

    This research investigated anisotropic scattering of ultrasonic and photoacoustic waves from tissues consisting of transverse isotropic structures. Anisotropic scattering refers to the systematic variation in acoustic scattered energy. Take tendon as an example, the maximum occurs when the arrangement of the transducer and fiber orientation is perpendicular and minimum occurs when the arrangement is parallel. Experimental results indicate the apparent integrated backscatter (AIB), which is widely adopted to compute the scattered energy, for photoacoustic as well as ultrasonic waves decayed as the arrangement changed from perpendicular to parallel. The AIB decrement using transducers with center frequency of 3.5 MHz, 5 MHz, and 20 MHz were 10.50 dB, 18.01 dB, and 20.98 dB, respectively. Photoacoustic AIB decrement detected by transducers with center frequency of 3.5 MHz, 5 MHz, and 20 MHz were 7.63 dB, 15.54 dB, and 17.76 dB, respectively. It is shown that higher detection frequency resulted in a larger decrement. A hypothesis is proposed to explain why photoacoustic waves are less affected by the fibrous tissue. In ultrasonic scattering, incident direction for each scatterer were similar due to the relatively planar wavefront, hence the signal amplitudes scattered at the transducer direction are also similar. In photoacoustic scattering, the spherical-like wavefront causes different incident directions for different scatterers, therefore the variation of the signal amplitude collected by the transducer increases, resulting in a lower correlation with the microstructure. In addition, the decrement of backscattered energy decreased for a single scatterer when the incident wave was spherical. Experimental and simulation results verified the hypothesis. The discovery implies that photoacoustic imaging has the potential to detect tissues with transverse isotropic structure that may be overlooked by conventional ultrasound imaging.

  8. Electromagnetic inverse scattering

    NASA Technical Reports Server (NTRS)

    Bojarski, N. N.

    1972-01-01

    A three-dimensional electromagnetic inverse scattering identity, based on the physical optics approximation, is developed for the monostatic scattered far field cross section of perfect conductors. Uniqueness of this inverse identity is proven. This identity requires complete scattering information for all frequencies and aspect angles. A nonsingular integral equation is developed for the arbitrary case of incomplete frequence and/or aspect angle scattering information. A general closed-form solution to this integral equation is developed, which yields the shape of the scatterer from such incomplete information. A specific practical radar solution is presented. The resolution of this solution is developed, yielding short-pulse target resolution radar system parameter equations. The special cases of two- and one-dimensional inverse scattering and the special case of a priori knowledge of scatterer symmetry are treated in some detail. The merits of this solution over the conventional radar imaging technique are discussed.

  9. Image measurement technique on vibration amplitude of ultrasonic horn

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-bin; Wu, Zhi-qun; Zhu, Jian-ping; He, Jian-guo; Liu, Guang-min

    2013-10-01

    The paper proposes a method to measure vibration amplitude of ultrasonic horn which is a very important component in the spindle for micro-electrical-chemical discharging machining. The method of image measuring amplitude on high frequency vibration is introduced. Non-contact measurement system based on vision technology is constructed. High precision location algorithm on image centroid, quadratic location algorithm, is presented to find the center of little light spot. Measurement experiments have been done to show the effect of image measurement technique on vibration amplitude of ultrasonic horn. In the experiments, precise calibration of the vision system is implemented using a normal graticule to obtain the scale factor between image pixel and real distance. The vibration amplitude of ultrasonic horn is changed by modifying the voltage amplitude of pulse power supply. The image of feature on ultrasonic horn is captured and image processing is carried out. The vibration amplitudes are got at different voltages.

  10. Multigluon scattering in open superstring theory

    SciTech Connect

    Stieberger, Stephan; Taylor, Tomasz R.

    2006-12-15

    We discuss the amplitudes describing N-gluon scattering in type I superstring theory, on a disk world sheet. After reviewing the general structure of amplitudes and the complications created by the presence of a large number of vertices at the boundary, we focus on the most promising case of maximally helicity violating (MHV) configurations because in this case, the zero Regge slope limit ({alpha}{sup '}{yields}0) is particularly simple. We obtain the full-fledged MHV disk amplitudes for N=4, 5, and N=6 gluons, expressed in terms of one, two and six functions of kinematic invariants, respectively. These functions represent certain boundary integrals--generalized Euler integrals--which for N{>=}6 correspond to multiple hypergeometric series (generalized Kampe de Feriet functions). Their {alpha}{sup '} expansions lead to Euler-Zagier sums. For arbitrary N, we show that the leading string corrections to the Yang-Mills amplitude, of order O({alpha}{sup '2}), originate from the well-known {alpha}{sup '2} TrF{sup 4} effective interactions of four gauge field strength tensors. By using iteration based on the soft gluon limit, we derive a simple formula valid to that order for arbitrary N. We argue that such a procedure can be extended to all orders in {alpha}{sup '}. If nature gracefully picked a sufficiently low string mass scale, our results would be important for studying string effects in multijet production at the Large Hadron Collider (LHC)

  11. Resonance scattering by fish schools: A comparison of two models.

    PubMed

    Raveau, M; Feuillade, C

    2016-01-01

    The effective medium method is used to investigate resonance scattering from schools of fish with gas-filled swim bladders, as a function of frequency and azimuth. Calculations are also performed with a coupled differential equation model, which incorporates both multiple scattering between fish and wave interference interactions of their scattered fields [Feuillade, Nero, and Love, J. Acoust. Soc. Am. 99, 196-208 (1996)]. A theoretical comparison of the models for idealized spherical schools shows good agreement over the entire resonance region in the forward direction, where interference interactions have a minimal effect. Good agreement is also seen in back scattering at low frequencies, where the wavelength λ≥4s, and s is the average nearest neighbor fish separation. If λ<4s, the models diverge in back scattering, and the effective medium method fails. This can be critically important when migrations of schools to deeper water cause the collective resonance frequency to increase. Multiple scattering interactions are negligible when |4πnf(b)(2)/k|⪅0.01, where n is the fish number density, f(b) is the individual fish scattering amplitude, and k=2π/λ. A comparison with forward scattering data shows very good agreement for both models, and indicates a method for estimating fish abundance. For back scattering data, the effective medium method diverges strongly when λ<4s. PMID:26827014

  12. Scattering of matter waves in spatially inhomogeneous environments

    SciTech Connect

    Tsitoura, F.; Krüger, P.; Kevrekidis, P. G.; Frantzeskakis, D. J.

    2015-03-30

    In this article, we study scattering of quasi-one-dimensional matter waves at an interface of two spatial domains, one with repulsive and one with attractive interatomic interactions. It is shown that the incidence of a Gaussian wave packet from the repulsive to the attractive region gives rise to generation of a soliton train. More specifically, the number of emergent solitons can be controlled, e.g., by the variation of the amplitude or the width of the incoming wave packet. Furthermore, we study the reflectivity of a soliton incident from the attractive region to the repulsive one. We find the reflection coefficient numerically and employ analytical methods, which treat the soliton as a particle (for moderate and large amplitudes) or a quasilinear wave packet (for small amplitudes), to determine the critical soliton momentum (as a function of the soliton amplitude) for which total reflection is observed.

  13. Scattering of matter waves in spatially inhomogeneous environments

    DOE PAGESBeta

    Tsitoura, F.; Krüger, P.; Kevrekidis, P. G.; Frantzeskakis, D. J.

    2015-03-30

    In this article, we study scattering of quasi-one-dimensional matter waves at an interface of two spatial domains, one with repulsive and one with attractive interatomic interactions. It is shown that the incidence of a Gaussian wave packet from the repulsive to the attractive region gives rise to generation of a soliton train. More specifically, the number of emergent solitons can be controlled, e.g., by the variation of the amplitude or the width of the incoming wave packet. Furthermore, we study the reflectivity of a soliton incident from the attractive region to the repulsive one. We find the reflection coefficient numericallymore » and employ analytical methods, which treat the soliton as a particle (for moderate and large amplitudes) or a quasilinear wave packet (for small amplitudes), to determine the critical soliton momentum (as a function of the soliton amplitude) for which total reflection is observed.« less

  14. N >= 4 Supergravity Amplitudes from Gauge Theory at One Loop

    SciTech Connect

    Bern, Z.; Boucher-Veronneau, C.; Johansson, H.; /Saclay

    2011-08-19

    We expose simple and practical relations between the integrated four- and five-point one-loop amplitudes of N {ge} 4 supergravity and the corresponding (super-)Yang-Mills amplitudes. The link between the amplitudes is simply understood using the recently uncovered duality between color and kinematics that leads to a double-copy structure for gravity. These examples provide additional direct confirmations of the duality and double-copy properties at loop level for a sample of different theories.

  15. Topological field theory amplitudes for A N-1 fibration

    NASA Astrophysics Data System (ADS)

    Iqbal, Amer; Khan, Ahsan Z.; Qureshi, Babar A.; Shabbir, Khurram; Shehper, Muhammad A.

    2015-12-01

    We study the partition function N=1 5D U( N) gauge theory with g adjoint hypermultiplets and show that for massless adjoint hypermultiplets it is equal to the partition function of a two dimensional topological field on a genus g Riemann surface. We describe the topological field theory by its amplitudes associated with cap, propagator and pair of pants. These basic amplitudes are open topological string amplitudes associated with certain Calabi-Yau threefolds in the presence of Lagrangian branes.

  16. Investigation of the effect of bilayer membrane structures and fluctuation amplitudes on SANS/SAXS profile for short membrane wavelength

    SciTech Connect

    Lee, Victor; Hawa, Takumi

    2013-09-28

    The effect of bilayer membrane structures and fluctuation amplitudes on small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) profile is investigated based on harmonic motions of the surfactant bilayers with bending as well as thickness fluctuation motions. In this study we consider the case in which the wavelength of the bilayer membrane is shorter than the thickness of the membrane. We find that the thickness of the surfactant bilayer membrane, d{sub m}, affects both q{sub dip} and q{sub peak} of I(q,0) profile, and that the fluctuation amplitude, a, of the membrane changes the peak of I(q,0). A simple formula is derived to estimate the thickness of the bilayer based on the q{sub dip} of the profile obtained from the simulation. The resulting estimates of the thickness of the bilayer with harmonic motion showed accuracy within 1%. Moreover, the bilayer thicknesses estimated from the proposed formula show an excellent agreement with the SANS and SAXS experimental results available in the literatures. We also propose a curve fit model, which describes the relationship between the fluctuation amplitude and the normalized q{sub peak} ratio. The present results show the feasibility of the simple formula to estimate the fluctuation amplitude based on the SANS and SAXS profiles.

  17. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-07-03

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  18. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2008-10-21

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  19. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-07-17

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  20. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2007-10-02

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  1. Method of differential-phase/absolute-amplitude QAM

    DOEpatents

    Dimsdle, Jeffrey William

    2009-09-01

    A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2.sup.N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

  2. Transition to amplitude death in scale-free networks

    NASA Astrophysics Data System (ADS)

    Liu, Weiqing; Wang, Xingang; Guan, Shuguang; Lai, Choy-Heng

    2009-09-01

    Transition to amplitude death in scale-free networks of nonlinear oscillators is investigated both numerically and analytically. It is found that, as the coupling strength increases, the network will undergo three different stages in approaching the state of complete amplitude death (CAD). In the first stage of the transition, the amplitudes of the oscillators present a 'stair-like' arrangement, i.e. the squared amplitude of an oscillator linearly decreases with the number of links that the oscillator receives (node degree). In this stage, as the coupling strength increases, the amplitude stairs are eliminated hierarchically by descending order of the node degree. At the end of the first stage, except for a few synchronized oscillators, all other oscillators in the network have small amplitudes. Then, in the second stage of the transition, the synchronous clusters formed in the first stage gradually disappear and, as a consequence, the number of small-amplitude oscillators is increased. At the end of the second stage, almost all oscillators in the network have small but finite amplitudes. Finally, in the third stage of the transition, without the support of the synchronous clusters, the amplitudes of the oscillators are quickly decreased, eventually leading to the state of CAD.

  3. Achieving Seventh-Order Amplitude Accuracy in Leapfrog Integrations

    NASA Astrophysics Data System (ADS)

    Williams, P. D.

    2014-12-01

    The leapfrog time-stepping scheme is commonly used in general circulation models of the atmosphere and ocean. The Robert-Asselin filter is used in conjunction with it, to damp the computational mode. Although the leapfrog scheme makes no amplitude errors when integrating linear oscillations, the Robert-Asselin filter introduces first-order amplitude errors. The RAW filter, which was recently proposed as an improvement, eliminates the first-order amplitude errors and yields third-order amplitude accuracy. This development has been shown to significantly increase the skill of medium-range weather forecasts. However, it has not previously been shown how to further improve the accuracy by eliminating the third- and higher-order amplitude errors. This presentation will show that leapfrogging over a suitably weighted blend of the filtered and unfiltered tendencies eliminates the third-order amplitude errors and yields fifth-order amplitude accuracy. It will also show that the use of a more discriminating (1, -4, 6, -4, 1) filter instead of a (1, -2, 1) filter eliminates the fifth-order amplitude errors and yields seventh-order amplitude accuracy. Other related schemes are obtained by varying the values of the filter parameters, and it is found that several combinations offer an appealing compromise of stability and accuracy. The proposed new schemes are shown to yield substantial forecast improvements in a medium-complexity atmospheric general circulation model. They appear to be attractive alternatives to the filtered leapfrog schemes currently used in many weather and climate models.

  4. Amplitude and phase noise of magnetic tunnel junction oscillators

    NASA Astrophysics Data System (ADS)

    Quinsat, M.; Gusakova, D.; Sierra, J. F.; Michel, J. P.; Houssameddine, D.; Delaet, B.; Cyrille, M.-C.; Ebels, U.; Dieny, B.; Buda-Prejbeanu, L. D.; Katine, J. A.; Mauri, D.; Zeltser, A.; Prigent, M.; Nallatamby, J.-C.; Sommet, R.

    2010-11-01

    The microwave emission linewidth of spin transfer torque nano-oscillators is closely related to their phase and amplitude noise that can be extracted from the magnetoresistive voltage signal V(t ) using single shot time domain techniques. Here we report on phase and amplitude noise studies for MgO based magnetic tunnel junction oscillators. The analysis of the power spectral densities allows one to separate the linear and nonlinear contributions to the phase noise, the nonlinear contribution being due to the coupling between phase and amplitude. The coupling strength as well as the amplitude relaxation rate can be directly extracted.

  5. Far field elastodynamic Born scattering revisited

    NASA Astrophysics Data System (ADS)

    Geerits, Tim W.; Veile, Ines; Hellwig, Olaf

    2013-02-01

    This paper summarizes part of an ongoing feasibility study that investigates the possible use of the full elastic Born approximation in multipole borehole acoustics. As a first step we exclude the fluid-filled borehole with the motivation that one or two wavelengths away from the fluid-filled borehole, radiating borehole mode amplitudes (e.g., Stoneley wave, formation dipole wave, etc.) are small compared to body wave amplitudes (P-, SV- and SH-waves). Consequently, for scatterers one or two wavelengths away from the fluid-filled borehole, it suffices to only consider their interaction with body waves. In this paper we apply the contrast-source stress-velocity forward scattering (integral equation) formulation for solid configurations in its first order (Born-) approximation (De Hoop, 1995) assuming a multipole force source excitation in a zero-offset configuration. To scrutinize the validity of the Born approximation, we consider the simplest type of scatterer, i.e., one characterized by a (Heaviside) step function change in one or more of the contrast (perturbation) parameters and we derive analytic zero-offset formulas for the scattered wave particle velocity and displacement in both the space-frequency and space-time domain, respectively. We assume the scatterer to be located in the far-field. More complicated layered configurations can easily be derived by superposition of the given solution types. Explicit results are given for the dipole and quadrupole excitation, where the former is allowed to have an arbitrary orientation relative to the scatterer and where the latter one is located in a plane perpendicular to the scatterer. In the time domain it is shown, how the scattered wave field decomposes in a specular and diffuse wave field (two terms borrowed from ‘Optics'), where the former contribution vanishes in the absence of an imaging condition and where the latter is always present. For the dipole case, we subject our results to a sensitivity analysis

  6. Calculations of K- nuclear quasi-bound states based on chiral meson-baryon amplitudes

    NASA Astrophysics Data System (ADS)

    Gazda, Daniel; Mareš, Jiří

    2012-05-01

    In-medium K¯N scattering amplitudes developed within a new chirally motivated coupled-channel model due to Cieplý and Smejkal that fits the recent SIDDHARTA kaonic hydrogen 1s level shift and width are used to construct K- nuclear potentials for calculations of K- nuclear quasi-bound states. The strong energy and density dependence of scattering amplitudes at and near threshold leads to K- potential depths -Re VK≈80-120 MeV. Self-consistent calculations of all K- nuclear quasi-bound states, including excited states, are reported. Model dependence, polarization effects, the role of p-wave interactions, and two-nucleon K-NN→YN absorption modes are discussed. The K- absorption widths ΓK are comparable or even larger than the corresponding binding energies BK for allK- nuclear quasi-bound states, exceeding considerably the level spacing. This discourages search for K- nuclear quasi-bound states in any but the lightest nuclear systems.

  7. Low energy neutron deuteron scattering to N3LO

    NASA Astrophysics Data System (ADS)

    Margaryan, Arman; Vanasse, Jared; Springer, Roxanne

    2015-10-01

    We calculate the next-to-next-to-next-to-leading order (N3LO) nd scattering amplitude in the framework of nonrelativistic pionless effective field theory (EFTπ/). This theory is only valid when the typical momentum exchange in the scattering is smaller then the mass of the pion. The power counting parameter for EFTπ/ is the ratio Q/Λπ /, where Q is the typical momentum exchange in the scattering and Λπ / is the EFTπ/ breakdown scale, Λπ / amplitude for nd scattering at leading order requires summing an infinite set of diagrams. The first nonzero polarization-dependent observables occur at N2LO. At N3LO new 2-body forces appear, which introduce four new EFTπ/ coefficients. These coefficients are fixed by the 3PJ and 1P1 phase shifts of NN scattering. We find that these terms have an important impact. The results of this calculation at N3LO will be important for understanding spin polarization observables in nd scattering, in particular the longstanding Ay puzzle. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics, under Award Number DE-FG02-05ER41368.

  8. Reconstruction of Rain Microstructure From Spectrum of Scattering Light

    NASA Astrophysics Data System (ADS)

    Sterlyadkin, V.; Gluschenko, A.

    Night photoregistration of light, scattered by drops had proved that practically all drops oscillate as they fall. As drop oscillation frequency W monotony diminish with drop volume V rise, so different fractions of rain form different parts of spectrum. Thereby it is possible to reconstruct rain microstructure from remote optical measure- ments. In common case the form of spectrum depends not only on drop size distri- bution N(V) but also on oscillation amplitudes function, scattering phase function for oscillating drops and on frequency dependence W(V). The statistical treatment of our field data had shown that average oscillation amplitude rise with drop volume V as , where A is a some constant. This result allows to solve the inverse problem: to re- construct drop size distribution N(V) from the power spectrum of light, scattering by rain. Scattering phase function for nonspherical and oscillating drops was calculated in straight-line approximation. Analysis of optical properties of oscillating water drop had shown some optimal measurement geometry for registration of rain microstruc- ture. For low intensity rains it is reasonable to use the effect of abnormal high modu- lation of light scattered by oscillating drops, which we discovered earlier in laboratory condition and under field measurements. (The effect of abnormal high modulation al- lows us to detect 2-3 mm raindrop deformations from 5 m distance). The results of reconstruction of drop size distributions from spectra of light, scattered by rains are presented and discussed.

  9. Two space scatterer formalism calculation of bulk parameters of thunderclouds

    NASA Technical Reports Server (NTRS)

    Phanord, Dieudonne D.

    1994-01-01

    In a previous study, we used a modified two-space scatterer formalism of Twersky to establish for a cloud modeled as a statistically homogeneous distribution of spherical water droplets, the dispersion relations that determine its bulk propagation numbers and bulk indexes of refraction in terms of the vector equivalent scattering amplitude and the dyadic scattering amplitude of the single water droplet in isolation. The results were specialized to the forward direction of scattering while demanding that the scatterers preserve the incident polarization. We apply this approach to obtain specific numerical values for the macroscopic parameters of the cloud. We work with a cloud of density rho = 100 cm(exp -3), a wavelength lambda = 0.7774 microns, and with spherical water droplets of common radius alpha = 10 microns. In addition, the scattering medium is divided into three parts, the medium outside the cloud, moist air (the medium inside the cloud but outside the droplets), and the medium inside the spherical water droplets. The results of this report are applicable to a cloud of any geometry since the boundary does not interfere with the calculations. Also, it is important to notice the plane wave nature of the incidence wave in the moist atmosphere.

  10. Deeply Virtual Compton Scattering off the Neutron

    SciTech Connect

    Mazouz, M.; Guillon, B.; Real, J.-S.; Voutier, E.

    2007-12-14

    The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e-vector,e{sup '}{gamma})X cross section measured at Q{sup 2}=1.9 GeV{sup 2} and x{sub B}=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E{sub q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  11. Quadratic electroweak corrections for polarized Moller scattering

    SciTech Connect

    A. Aleksejevs, S. Barkanova, Y. Kolomensky, E. Kuraev, V. Zykunov

    2012-01-01

    The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments.

  12. Evolution of hadron beams under intrabeam scattering

    SciTech Connect

    Wei, Jie.

    1993-01-01

    Based on assumptions applicable to many circular accelerators, we simplify into analytical form the growth rates of a hadron beam under Coulomb intrabeam scattering (IBS). Because of the dispersion that correlates the horizontal closed orbit to the momentum, the scaling behavior of the growth rates are drastically different at energies low and high compared with the transition energy. At high energies the rates are approximately independent of the energy. Asymptotically, the horizontal and longitudinal beam amplitudes are linearly related by the average dispersion. At low energies, the beam evolves such that the velocity distribution in the rest frame becomes isotropic in all the directions.

  13. Evolution of hadron beams under intrabeam scattering

    SciTech Connect

    Wei, Jie

    1993-06-01

    Based on assumptions applicable to many circular accelerators, we simplify into analytical form the growth rates of a hadron beam under Coulomb intrabeam scattering (IBS). Because of the dispersion that correlates the horizontal closed orbit to the momentum, the scaling behavior of the growth rates are drastically different at energies low and high compared with the transition energy. At high energies the rates are approximately independent of the energy. Asymptotically, the horizontal and longitudinal beam amplitudes are linearly related by the average dispersion. At low energies, the beam evolves such that the velocity distribution in the rest frame becomes isotropic in all the directions.

  14. Systematics of meson-Skyrmion scattering

    SciTech Connect

    Mattis, M.P.

    1986-02-01

    The S-matrix characterizing the scattering of pions from nucleons is calculated in the context of skyrmion models of the nucleon. These are models in which the nucleon is considered a soliton in the field of pions. The spectrum of nucleon and delta resonances in the Skyrme model is calculated and found to be in overall good agreement with Nature. Model-independent sum rules between amplitudes in the same partial wave are derived and examined. An extension of the formalism to the case of three light flavors is presented. 31 refs., 26 figs., 6 tabs.

  15. Deeply virtual compton scattering off the neutron.

    PubMed

    Mazouz, M; Camsonne, A; Camacho, C Muñoz; Ferdi, C; Gavalian, G; Kuchina, E; Amarian, M; Aniol, K A; Beaumel, M; Benaoum, H; Bertin, P; Brossard, M; Chen, J-P; Chudakov, E; Craver, B; Cusanno, F; de Jager, C W; Deur, A; Feuerbach, R; Fieschi, J-M; Frullani, S; Garçon, M; Garibaldi, F; Gayou, O; Gilman, R; Gomez, J; Gueye, P; Guichon, P A M; Guillon, B; Hansen, O; Hayes, D; Higinbotham, D; Holmstrom, T; Hyde, C E; Ibrahim, H; Igarashi, R; Jiang, X; Jo, H S; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissiere, G; Lerose, J J; Lindgren, R; Liyanage, N; Lu, H-J; Margaziotis, D J; Meziani, Z-E; McCormick, K; Michaels, R; Michel, B; Moffit, B; Monaghan, P; Nanda, S; Nelyubin, V; Potokar, M; Qiang, Y; Ransome, R D; Réal, J-S; Reitz, B; Roblin, Y; Roche, J; Sabatié, F; Saha, A; Sirca, S; Slifer, K; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

    2007-12-14

    The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e,e'gamma)X cross section measured at Q2=1.9 GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E_{q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced. PMID:18233443

  16. Deeply Virtual Compton Scattering off the neutron

    SciTech Connect

    M. Mazouz; A. Camsonne; C. Munoz Camacho; C. Ferdi; G. Gavalian; E. Kuchina; M. Amarian; K. A. Aniol; M. Beaumel; H. Benaoum; P. Bertin; M. Brossard; J.-P. Chen; E. Chudakov; B. Craver; F. Cusanno; C.W. de Jager; A. Deur; R. Feuerbach; J.-M. Fieschi; S. Frullani; M. Garcon; F. Garibaldi; O. Gayou; R. Gilman; J. Gomez; P. Gueye; P.A.M. Guichon; B. Guillon; O. Hansen; D. Hayes; D. Higinbotham; T. Holmstrom; C.E. Hyde; H. Ibrahim; R. Igarashi; X. Jiang; H.S. Jo; L.J. Kaufman; A. Kelleher; A. Kolarkar; G. Kumbartzki; G. Laveissiere; J.J. LeRose; R. Lindgren; N. Liyanage; H.-J. Lu; D.J. Margaziotis; Z.-E. Meziani; K. McCormick; R. Michaels; B. Michel; B. Moffit; P. Monaghan; S. Nanda; V. Nelyubin; M. Potokar; Y. Qiang; R.D. Ransome; J.-S. Real; B. Reitz; Y. Roblin; J. Roche; F. Sabatie; A. Saha; S. Sirca; K. Slifer; P. Solvignon; R. Subedi; V. Sulkosky; P.E. Ulmer; E. Voutier; K. Wang; L.B. Weinstein; B. Wojtsekhowski; X. Zheng; L. Zhu

    2007-12-01

    The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  17. Source-Space Cross-Frequency Amplitude-Amplitude Coupling in Tinnitus

    PubMed Central

    Zobay, Oliver; Adjamian, Peyman

    2015-01-01

    The thalamocortical dysrhythmia (TCD) model has been influential in the development of theoretical explanations for the neurological mechanisms of tinnitus. It asserts that thalamocortical oscillations lock a region in the auditory cortex into an ectopic slow-wave theta rhythm (4–8 Hz). The cortical area surrounding this region is hypothesized to generate abnormal gamma (>30 Hz) oscillations (“edge effect”) giving rise to the tinnitus percept. Consequently, the model predicts enhanced cross-frequency coherence in a broad range between theta and gamma. In this magnetoencephalography study involving tinnitus and control cohorts, we investigated this prediction. Using beamforming, cross-frequency amplitude-amplitude coupling (AAC) was computed within the auditory cortices for frequencies (f1, f2) between 2 and 80 Hz. We find the AAC signal to decompose into two distinct components at low (f1, f2 < 30 Hz) and high (f1, f2 > 30 Hz) frequencies, respectively. Studying the correlation of AAC with several key covariates (age, hearing level (HL), tinnitus handicap and duration, and HL at tinnitus frequency), we observe a statistically significant association between age and low-frequency AAC. Contrary to the TCD predictions, however, we do not find any indication of statistical differences in AAC between tinnitus and controls and thus no evidence for the predicted enhancement of cross-frequency coupling in tinnitus. PMID:26665004

  18. Off-shell amplitudes as boundary integrals of analytically continued Wilson line slope

    NASA Astrophysics Data System (ADS)

    Kotko, P.; Serino, M.; Stasto, A. M.

    2016-08-01

    One of the methods to calculate tree-level multi-gluon scattering amplitudes is to use the Berends-Giele recursion relation involving off-shell currents or off-shell amplitudes, if working in the light cone gauge. As shown in recent works using the light-front perturbation theory, solutions to these recursions naturally collapse into gauge invariant and gauge-dependent components, at least for some helicity configurations. In this work, we show that such structure is helicity independent and emerges from analytic properties of matrix elements of Wilson line operators, where the slope of the straight gauge path is shifted in a certain complex direction. This is similar to the procedure leading to the Britto-Cachazo-Feng-Witten (BCFW) recursion, however we apply a complex shift to the Wilson line slope instead of the external momenta. While in the original BCFW procedure the boundary integrals over the complex shift vanish for certain deformations, here they are non-zero and are equal to the off-shell amplitudes. The main result can thus be summarized as follows: we derive a decomposition of a helicity-fixed off-shell current into gauge invariant component given by a matrix element of a straight Wilson line plus a reminder given by a sum of products of gauge invariant and gauge dependent quantities. We give several examples realizing this relation, including the five-point next-to-MHV helicity configuration.

  19. The neutron-proton charge-exchange amplitudes measured in the dp → ppn reaction

    NASA Astrophysics Data System (ADS)

    Mchedlishvili, D.; Barsov, S.; Carbonell, J.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Engels, R.; Gebel, R.; Glagolev, V.; Grigoryev, K.; Goslawski, P.; Hartmann, M.; Kacharava, A.; Kamerdzhiev, V.; Keshelashvili, I.; Khoukaz, A.; Komarov, V.; Kulessa, P.; Kulikov, A.; Lehrach, A.; Lomidze, N.; Lorentz, B.; Macharashvili, G.; Maier, R.; Merzliakov, S.; Mielke, M.; Mikirtychyants, M.; Mikirtychyants, S.; Nioradze, M.; Ohm, H.; Papenbrock, M.; Prasuhn, D.; Rathmann, F.; Serdyuk, V.; Seyfarth, H.; Stein, H. J.; Steffens, E.; Stockhorst, H.; Ströher, H.; Tabidze, M.; Trusov, S.; Uzikov, Yu.; Valdau, Yu.; Wilkin, C.

    2013-04-01

    The unpolarised differential cross section and the two deuteron tensor analysing powers A xx and A yy of the ěc dp to \\{ pp\\} _s n charge-exchange reaction have been measured with the ANKE spectrometer at the COSY storage ring. Using deuteron beams with energies 1.2, 1.6, 1.8, and 2.27GeV, data were obtained for small momentum transfers to a { pp} s system with low excitation energy. The results at the three lower energies are consistent with impulse approximation predictions based upon the current knowledge of the neutron-proton amplitudes. However, at 2.27GeV, where these amplitudes are far more uncertain, agreement requires a reduction in the overall double-spin-flip contribution, with an especially significant effect in the longitudinal direction. These conclusions are supported by measurements of the deuteron-proton spin-correlation parameters C x,x and C y,y that were carried out in the ěc děc p to \\{ pp\\} _s n reaction at 1.2 and 2.27GeV. The values obtained for the proton analysing power A {/y p } also suggest the need for a radical re-evaluation of the neutron-proton elastic scattering amplitudes at the higher energy. It is therefore clear that such measurements can provide a valuable addition to the neutron-proton database in the charge-exchange region.

  20. Closed string Ramond-Ramond proposed higher derivative interactions on fermionic amplitudes in IIB

    NASA Astrophysics Data System (ADS)

    Hatefi, Ehsan

    2014-03-01

    The complete form of the amplitude of one closed string Ramond-Ramond (RR), two fermionic strings and one scalar field in IIB superstring theory has been computed in detail. Deriving by using suitable gauge fixing, we discover some new vertices and their higher derivative corrections. We investigate both infinite gauge and scalar u-channel poles of this amplitude. In particular, by using the fact that the kinetic term of fermion fields has no correction, employing Born-Infeld action, the Wess-Zumino terms and their higher derivative corrections, we discover all infinite t,s-channel fermion poles. The couplings between one RR and two fermions and all their infinite higher derivative corrections have been explored. In order to look for all infinite (s+t+u)-channel scalar/gauge poles for p+2=n, p=n cases, we obtain the couplings between two fermions-two scalars and two fermions, one scalar and one gauge field as well as all their infinite higher derivative corrections in type IIB. Specifically we make various comments based on arXiv:1205.5079 in favor of universality conjecture for all order higher derivative corrections (with or without low energy expansion) and the relation of open/closed string that is responsible for all superstring scattering amplitudes in IIA, IIB.

  1. Nontidal ocean loading: amplitudes and potential effects in GPS height time series

    NASA Astrophysics Data System (ADS)

    van Dam, T.; Collilieux, X.; Wuite, J.; Altamimi, Z.; Ray, J.

    2012-11-01

    Ocean bottom pressure (OBP) changes are caused by a redistribution of the ocean's internal mass that are driven by atmospheric circulation, a change in the mass entering or leaving the ocean, and/or a change in the integrated atmospheric mass over the ocean areas. The only previous global analysis investigating the magnitude of OBP surface displacements used older OBP data sets (van Dam et al. in J Geophys Res 129:507-517, 1997). Since then significant improvements in meteorological forcing models used to predict OBP have been made, augmented by observations from satellite altimetry and expendable bathythermograph profiles. Using more recent OBP estimates from the Estimating the Circulation and Climate of the Ocean (ECCO) project, we reassess the amplitude of the predicted effect of OBP on the height coordinate time series from a global distribution of GPS stations. OBP-predicted loading effects display an RMS scatter in the height of between 0.2 and 3.7 mm, larger than previously reported but still much smaller (by a factor of 2) than the scatter observed due to atmospheric pressure loading. Given the improvement in GPS hardware and data analysis techniques, the OBP signal is similar to the precision of weekly GPS height coordinates. We estimate the effect of OBP on GPS height coordinate time series using the MIT reprocessed solution, mi1. When we compare the predicted OBP height time series with mi1, we find that the scatter is reduced over all stations by 0.1 mm on average with reductions as high as 0.7 mm at some stations. More importantly we are able to reduce the scatter on 65 % of the stations investigated. The annual component of the OBP signal is responsible for 80 % of the reduction in scatter on average. We find that stations located close to semi-enclosed bays or seas are affected by OBP loading to a greater extent than other stations.

  2. Multiple scattering tomography.

    PubMed

    Modregger, Peter; Kagias, Matias; Peter, Silvia; Abis, Matteo; Guzenko, Vitaliy A; David, Christian; Stampanoni, Marco

    2014-07-11

    Multiple scattering represents a challenge for numerous modern tomographic imaging techniques. In this Letter, we derive an appropriate line integral that allows for the tomographic reconstruction of angular resolved scattering distributions, even in the presence of multiple scattering. The line integral is applicable to a wide range of imaging techniques utilizing various kinds of probes. Here, we use x-ray grating interferometry to experimentally validate the framework and to demonstrate additional structural sensitivity, which exemplifies the impact of multiple scattering tomography. PMID:25062159

  3. Environment scattering in GADRAS.

    SciTech Connect

    Thoreson, Gregory G.; Mitchell, Dean James; Theisen, Lisa Anne; Harding, Lee T.

    2013-09-01

    Radiation transport calculations were performed to compute the angular tallies for scattered gamma-rays as a function of distance, height, and environment. Green's Functions were then used to encapsulate the results a reusable transformation function. The calculations represent the transport of photons throughout scattering surfaces that surround sources and detectors, such as the ground and walls. Utilization of these calculations in GADRAS (Gamma Detector Response and Analysis Software) enables accurate computation of environmental scattering for a variety of environments and source configurations. This capability, which agrees well with numerous experimental benchmark measurements, is now deployed with GADRAS Version 18.2 as the basis for the computation of scattered radiation.

  4. Bubble nonlinear dynamics and stimulated scattering process

    NASA Astrophysics Data System (ADS)

    Jie, Shi; De-Sen, Yang; Sheng-Guo, Shi; Bo, Hu; Hao-Yang, Zhang; Shi-Yong, Hu

    2016-02-01

    A complete understanding of the bubble dynamics is deemed necessary in order to achieve their full potential applications in industry and medicine. For this purpose it is first needed to expand our knowledge of a single bubble behavior under different possible conditions including the frequency and pressure variations of the sound field. In addition, stimulated scattering of sound on a bubble is a special effect in sound field, and its characteristics are associated with bubble oscillation mode. A bubble in liquid can be considered as a representative example of nonlinear dynamical system theory with its resonance, and its dynamics characteristics can be described by the Keller-Miksis equation. The nonlinear dynamics of an acoustically excited gas bubble in water is investigated by using theoretical and numerical analysis methods. Our results show its strongly nonlinear behavior with respect to the pressure amplitude and excitation frequency as the control parameters, and give an intuitive insight into stimulated sound scattering on a bubble. It is seen that the stimulated sound scattering is different from common dynamical behaviors, such as bifurcation and chaos, which is the result of the nonlinear resonance of a bubble under the excitation of a high amplitude acoustic sound wave essentially. The numerical analysis results show that the threshold of stimulated sound scattering is smaller than those of bifurcation and chaos in the common condition. Project supported by the Program for Changjiang Scholars and Innovative Research Team in University, China (Grant No. IRT1228) and the Young Scientists Fund of the National Natural Science Foundation of China (Grant Nos. 11204050 and 11204049).

  5. Automated force controller for amplitude modulation atomic force microscopy.

    PubMed

    Miyagi, Atsushi; Scheuring, Simon

    2016-05-01

    Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollable drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed. PMID:27250433

  6. Broadband metasurfaces with simultaneous control of phase and amplitude.

    PubMed

    Liu, Lixiang; Zhang, Xueqian; Kenney, Mitchell; Su, Xiaoqiang; Xu, Ningning; Ouyang, Chunmei; Shi, Yunlong; Han, Jiaguang; Zhang, Weili; Zhang, Shuang

    2014-08-01

    By combining the freedom of both the structural design and the orientation of split ring resonator antennas, we demonstrate terahertz metasurfaces that are capable of controlling both the phase and amplitude profiles over a very broad bandwidth. As an example, we show that the phase-amplitude metasurfaces can be engineered to control the diffraction orders arbitrarily. PMID:24863731

  7. High Frequency Amplitude Detector for GMI Magnetic Sensors

    PubMed Central

    Asfour, Aktham; Zidi, Manel; Yonnet, Jean-Paul

    2014-01-01

    A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI) sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted. PMID:25536003

  8. Nitinol Fatigue Life for Variable Strain Amplitude Fatigue

    NASA Astrophysics Data System (ADS)

    Lin, Z.; Pike, K.; Schlun, M.; Zipse, A.; Draper, J.

    2012-12-01

    Nitinol fatigue testing results are presented for variable strain amplitude cycling. The results indicate that cycles smaller than the constant amplitude fatigue limit may contribute to significant fatigue damage when they occur in a repeating sequence of large and small amplitude cycles. The testing utilized two specimen types: stent-like diamond specimens and Z-shaped wire specimens. The diamond specimens were made from nitinol tubing with stent-like manufacturing processes and the Z-shaped wire specimens were made from heat set nitinol wire. The study explored the hypothesis that duty cycling can have an effect on nitinol fatigue life. Stent-like structures were subjected to different in vivo loadings in order to create more complex strain amplitudes. The main focus in this study was to determine whether a combination of small and large amplitudes causes additional damage that alters the fatigue life of a component.

  9. Amplitude transitions of swimmers and flexors in viscoelastic fluids

    NASA Astrophysics Data System (ADS)

    Guy, Robert; Thomases, Becca

    2015-11-01

    In both theoretical and experimental studies of the effect of fluid elasticity on micro-organism swimming, very different behavior has been observed for small and large amplitude strokes. We present simulations of an undulatory swimmer in an Oldroyd-B fluid and show that the resulting viscoelastic stresses are a nonlinear function of the amplitude. Specifically, there appears to be an amplitude dependent transition that is key to obtaining a speed-up over the Newtonian swimming speed. To understand the physical mechanism of the transition, we examine the stresses in a time-symmetric oscillatory bending beam, or flexor. We compare the flow in a neighborhood of the flexor tips with a large-amplitude oscillatory extensional flow, and we see similar amplitude dependent transitions. We relate these transitions to observed speed-ups in viscoelastic swimmers.

  10. Renormalization of massless Feynman amplitudes in configuration space

    NASA Astrophysics Data System (ADS)

    Nikolov, Nikolay M.; Stora, Raymond; Todorov, Ivan

    2014-05-01

    A systematic study of recursive renormalization of Feynman amplitudes is carried out both in Euclidean and in Minkowski configuration spaces. For a massless quantum field theory (QFT), we use the technique of extending associate homogeneous distributions to complete the renormalization recursion. A homogeneous (Poincaré covariant) amplitude is said to be convergent if it admits a (unique covariant) extension as a homogeneous distribution. For any amplitude without subdivergences — i.e. for a Feynman distribution that is homogeneous off the full (small) diagonal — we define a renormalization invariant residue. Its vanishing is a necessary and sufficient condition for the convergence of such an amplitude. It extends to arbitrary — not necessarily primitively divergent — Feynman amplitudes. This notion of convergence is finer than the usual power counting criterion and includes cancellation of divergences.

  11. Simplicity in the structure of QED and gravity amplitudes

    NASA Astrophysics Data System (ADS)

    Badger, Simon; Bjerrum-Bohr, N. E. J.; Vanhove, Pierre

    2009-02-01

    We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED `no-triangle' property is true for all helicity configurations and has similarities to the `no-triangle' property found in the case of maximal Script N = 8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude.

  12. Discontinuities of BFKL amplitudes and the BDS ansatz

    NASA Astrophysics Data System (ADS)

    Fadin, V. S.; Fiore, R.

    2015-12-01

    We perform an examination of discontinuities of multiple production amplitudes, which are required for further development of the BFKL approach. It turns out that the discontinuities of 2 → 2 + n amplitudes obtained in the BFKL approach contradict to the BDS ansatz for amplitudes with maximal helicity violation in N = 4 supersymmetric Yang-Mills theory with large number of colors starting with n = 2. Explicit expressions for the discontinuities of the 2 → 3 and 2 → 4 amplitudes in the invariant mass of pairs of produced gluons are obtained in the planar N = 4 SYM in the next-to-leading logarithmic approximation. These expressions can be used for checking the conjectured duality between the light-like Wilson loops and the MHV amplitudes.

  13. Nucleon Compton scattering in the Dyson-Schwinger approach

    NASA Astrophysics Data System (ADS)

    Eichmann, Gernot; Fischer, Christian S.

    2013-02-01

    We analyze the nucleon’s Compton scattering amplitude in the Dyson-Schwinger/Faddeev approach. We calculate a subset of diagrams that implements the nonperturbative handbag contribution as well as all t-channel resonances. At the quark level, these ingredients are represented by the quark Compton vertex whose analytic properties we study in detail. We derive a general form for a fermion two-photon vertex that is consistent with its Ward-Takahashi identities and free of kinematic singularities, and we relate its transverse part to the on-shell nucleon Compton amplitude. We solve an inhomogeneous Bethe-Salpeter equation for the quark Compton vertex in rainbow-ladder truncation and implement it in the nucleon Compton scattering amplitude. The remaining ingredients are the dressed quark propagator and the nucleon’s bound-state amplitude which are consistently solved from Dyson-Schwinger and covariant Faddeev equations. We verify numerically that the resulting quark Compton vertex and nucleon Compton amplitude both reproduce the πγγ transition form factor when the pion pole in the t channel is approached.

  14. A scattering model for forested area

    NASA Technical Reports Server (NTRS)

    Karam, M. A.; Fung, A. K.

    1988-01-01

    A forested area is modeled as a volume of randomly oriented and distributed disc-shaped, or needle-shaped leaves shading a distribution of branches modeled as randomly oriented finite-length, dielectric cylinders above an irregular soil surface. Since the radii of branches have a wide range of sizes, the model only requires the length of a branch to be large compared with its radius which may be any size relative to the incident wavelength. In addition, the model also assumes the thickness of a disc-shaped leaf or the radius of a needle-shaped leaf is much smaller than the electromagnetic wavelength. The scattering phase matrices for disc, needle, and cylinder are developed in terms of the scattering amplitudes of the corresponding fields which are computed by the forward scattering theorem. These quantities along with the Kirchoff scattering model for a randomly rough surface are used in the standard radiative transfer formulation to compute the backscattering coefficient. Numerical illustrations for the backscattering coefficient are given as a function of the shading factor, incidence angle, leaf orientation distribution, branch orientation distribution, and the number density of leaves. Also illustrated are the properties of the extinction coefficient as a function of leaf and branch orientation distributions. Comparisons are made with measured backscattering coefficients from forested areas reported in the literature.

  15. Effect of an electron scattering cloud on X-ray oscillations produced by beaming

    NASA Technical Reports Server (NTRS)

    Brainerd, J.; Lamb, F. K.

    1987-01-01

    The effect of a scattering cloud on the amplitude of oscillations produced by a rotating beam of X-rays is investigated using analytical and Monte Carlo methods. The scattering cloud was modeled as a uniform density sphere, and the source was represented as an anistropic distribution of radiation emerging from a point at the center of the scattering cloud. The intensity distribution produced by the source beam is examined as a function of optical depth. The relation between electron scattering optical depth and the forward-backward ratio is studied. It is observed that the scattering in a central corona of various optical depths reduces the amplitude of the oscillation. The data suggest that the quasi-periodic oscillations observed in the X-ray intensities of some luminous low-mass X-ray binaries are caused by oscillations in the luminosity of the X-ray star.

  16. Achieving seventh-order amplitude accuracy in leapfrog integrations

    NASA Astrophysics Data System (ADS)

    Williams, Paul

    2015-04-01

    The leapfrog time-stepping scheme is commonly used in general circulation models of weather and climate. The Robert-Asselin filter is used in conjunction with it, to damp the computational mode. Although the leapfrog scheme makes no amplitude errors when integrating linear oscillations, the Robert-Asselin filter introduces first-order amplitude errors. The RAW filter, which was recently proposed as an improvement, eliminates the first-order amplitude errors and yields third-order amplitude accuracy. This development has been shown to significantly increase the skill of medium-range weather forecasts. However, it has not previously been shown how to further improve the accuracy by eliminating the third- and higher-order amplitude errors. This presentation will show that leapfrogging over a suitably weighted blend of the filtered and unfiltered tendencies eliminates the third-order amplitude errors and yields fifth-order amplitude accuracy. It will also show that the use of a more discriminating (1,-4,6,-4,1) filter instead of a (1,-2,1) filter eliminates the fifth-order amplitude errors and yields seventh-order amplitude accuracy. Other related schemes are obtained by varying the values of the filter parameters, and it is found that several combinations offer an appealing compromise of stability and accuracy. The proposed new schemes are shown to yield substantial forecast improvements in a medium-complexity atmospheric general circulation model. They appear to be attractive alternatives to the filtered leapfrog schemes currently used in many weather and climate models. Reference Williams PD (2013) Achieving seventh-order amplitude accuracy in leapfrog integrations. Monthly Weather Review 141(9), pp 3037-3051. DOI: 10.1175/MWR-D-12-00303.1

  17. Vibration of low amplitude imaged in amplitude and phase by sideband versus carrier correlation digital holography.

    PubMed

    Verrier, N; Alloul, L; Gross, M

    2015-02-01

    Sideband holography can be used to get field images (E0 and E1) of a vibrating object for both the carrier (E0) and the sideband (E1) frequency with respect to vibration. Here we propose to record E0 and E1 sequentially and to image the product E1E0* or the correlation 〈E1E0*〉. We show that these quantities are insensitive to the phase related to the object roughness and directly reflect the phase of the mechanical motion. The signal to noise can be improved by averaging E1E0* over a neighbor pixel, yielding 〈E1E0*〉. Experimental validation is made with a vibrating cube of wood and a clarinet reed. At 2 kHz, vibrations of amplitude down to 0.01 nm are detected. PMID:25680060

  18. Microstructure and nonlinear signatures of yielding in a heterogeneous colloidal gel under large amplitude oscillatory shear

    SciTech Connect

    Kim, Juntae; Helgeson, Matthew E.; Merger, Dimitri; Wilhelm, Manfred

    2014-09-01

    We investigate yielding in a colloidal gel that forms a heterogeneous structure, consisting of a two-phase bicontinuous network of colloid-rich domains of fractal clusters and colloid-poor domains. Combining large amplitude oscillatory shear measurements with simultaneous small and ultra-small angle neutron scattering (rheo-SANS/USANS), we characterize both the nonlinear mechanical processes and strain amplitude-dependent microstructure underlying yielding. We observe a broad, three-stage yielding process that evolves over an order of magnitude in strain amplitude between the onset of nonlinearity and flow. Analyzing the intracycle response as a sequence of physical processes reveals a transition from elastic straining to elastoplastic thinning (which dominates in region I) and eventually yielding (which evolves through region II) and flow (which saturates in region III), and allows quantification of instantaneous nonlinear parameters associated with yielding. These measures exhibit significant strain rate amplitude dependence above a characteristic frequency, which we argue is governed by poroelastic effects. Correlating these results with time-averaged rheo-USANS measurements reveals that the material passes through a cascade of structural breakdown from large to progressively smaller length scales. In region I, compression of the fractal domains leads to the formation of large voids. In regions II and III, cluster-cluster correlations become increasingly homogeneous, suggesting breakage and eventually depercolation of intercluster bonds at the yield point. All significant structural changes occur on the micron-scale, suggesting that large-scale rearrangements of hundreds or thousands of particles, rather than the homogeneous rearrangement of particle-particle bonds, dominate the initial yielding of heterogeneous colloidal gels.

  19. LINEAR RELATIONS BETWEEN STIMULUS AMPLITUDES AND AMPLITUDES OF RETINAL ACTION POTENTIALS FROM THE EYE OF THE WOLF SPIDER.

    PubMed

    DEVOE, R D

    1963-09-01

    Incremental photic stimuli have been used to elicit small amplitude retinal action potentials from light-adapted ocelli of the wolf spider, Lycosa baltimoriana (Keyserling) in order to see whether or not the amplitudes of these potentials are linearly related to the stimulus amplitudes. Sine wave variations of light intensity around a mean elicit sine wave variations in potential which contain inappreciable harmonics of the stimulus frequency and whose amplitudes are linearly related to the stimulus amplitudes. Likewise, the responses to the first two periodic Fourier components of incremental rectangular wave stimuli of variable duty cycle are directly proportional to the amplitudes of these components and have phases dependent only on the frequencies and phases of these components. Thirdly, a linear transfer function can be found which describes the amplitudes and phases of responses recorded at different frequencies of sine wave stimulation and this transfer function is sufficient to predict the responses to incremental step stimuli. Finally, it is shown that flash response amplitudes are linearly related to incremental flash intensities at all levels of adaptation. The relations of these linear responses to non-linear responses and to physiological mechanisms of the eye are discussed. PMID:14060442

  20. Psinsar Improvement Using Amplitude Dispersion Index Optimization of Dual Polarimetry Data

    NASA Astrophysics Data System (ADS)

    Esmaeili, M.; Motagh, M.

    2015-12-01

    Persistent Scatterer Interferometry for SAR data (PSInSAR) improves the ability of conventional InSAR time-series methods by detecting and analysing pixels where the portion of spatiotemporal decorrelations on the phase is negligible. Using dual/quad polarized SAR data provide us with an additional source of information to improve further the capability of InSAR analysis. In this paper, we present a method to enhance PSInSAR using polarimetric optimization method on multi-temporal polarimetric SAR data. The optimization process has been implemented to minimize the Amplitude dispersion Index (ADI) of pixels in SAR images over the time based on the best scattering mechanism. We evaluated the method on a dataset including 17 dual polarization SAR data (HH/VV) acquired by TerraSAR-X data from July 2013 to January 2014 over Tehran plain, Iran. The area has been affected by high rate (> 20 cm/yr.) of surface subsidence due to groundwater overexploitation. The effectiveness of the method is compared for both agricultural and urban regions affected by land subsidence. Furthermore single pole and optimized polarization results are compared together and with external observations from GPS measurements. The results reveal that using optimum scattering mechanism decreases the ADI values in urban and non-urban regions and increase the PS Candidate pixels (PSC) about three times and subsequently improves the PS density about 50% more than using single channel datasets.

  1. Compton scattering, meson exchange, and the polarizabilities of bound nucleons

    NASA Astrophysics Data System (ADS)

    Feldman, G.; Mellendorf, K. E.; Eisenstein, R. A.; Federspiel, F. J.; Garino, G.; Igarashi, R.; Kolb, N. R.; Lucas, M. A.; MacGibbon, B. E.; Mize, W. K.; Nathan, A. M.; Pywell, R. E.; Wells, D. P.

    1996-11-01

    Elastic photon scattering cross sections on 16O have been measured in the energy range 27-108 MeV. These data are inconsistent with a conventional interpretation in which the electric and magnetic polarizabilities of the bound nucleon are unchanged from the free values and the meson-exchange seagull amplitude is taken in the zero-energy limit. Agreement with the data can be achieved by invoking either strongly modified polarizabilities or a substantial energy dependence to the meson-exchange seagull amplitude. It is argued that these seemingly different explanations are experimentally indistinguishable and probably physically equivalent.

  2. Learning from the scatter in type ia supernovae

    SciTech Connect

    Dodelson, Scott; Vallinotto, Alberto; /Fermilab /Chicago U.

    2005-11-01

    Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here they probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub s}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub s} to within 5% with observations of 2000 Type Ia Supernovae. They identify three sources of systematic error--evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing--which will make this measurement difficult.

  3. Examining the scaling behavior of Delbrueck scattering in experimental data

    SciTech Connect

    Kunwar, B.; Bhadra, A; Sen Gupta, S. K.

    2011-09-15

    The conventional perception is that the amplitudes of Delbrueck scattering calculated to all orders in the charge number Z of the target nucleus should exhibit a scaling behavior at high energies. To examine this hypothesis the available experimental data of differential cross sections of elastic scattering in the energy range between 140 MeV and 7.11 GeV are analyzed. It is found that the experimental data do not show scaling characteristics. Such a finding, though apparently against the standard notion, is not unexpected because at high energies Delbrueck scattering is in very forward direction and the theoretical arguments demand that to observe scaling, not only the energy itself but the product of scattering angles and energy also should be very large.

  4. Learning from the scatter in type Ia supernovae

    SciTech Connect

    Dodelson, Scott; Vallinotto, Alberto

    2006-09-15

    Type Ia Supernovae are standard candles so their mean apparent magnitude has been exploited to learn about the redshift-distance relationship. Besides intrinsic scatter in this standard candle, additional scatter is caused by gravitational magnification by large scale structure. Here we probe the dependence of this dispersion on cosmological parameters and show that information about the amplitude of clustering, {sigma}{sub 8}, is contained in the scatter. In principle, it will be possible to constrain {sigma}{sub 8} to within 5% with observations of 2000 Type Ia Supernovae. We identify three sources of systematic error - evolution of intrinsic scatter, baryon contributions to lensing, and non-Gaussianity of lensing - which will make this measurement difficult.

  5. Nonreciprocal wave scattering on nonlinear string-coupled oscillators

    SciTech Connect

    Lepri, Stefano; Pikovsky, Arkady

    2014-12-01

    We study scattering of a periodic wave in a string on two lumped oscillators attached to it. The equations can be represented as a driven (by the incident wave) dissipative (due to radiation losses) system of delay differential equations of neutral type. Nonlinearity of oscillators makes the scattering non-reciprocal: The same wave is transmitted differently in two directions. Periodic regimes of scattering are analyzed approximately, using amplitude equation approach. We show that this setup can act as a nonreciprocal modulator via Hopf bifurcations of the steady solutions. Numerical simulations of the full system reveal nontrivial regimes of quasiperiodic and chaotic scattering. Moreover, a regime of a “chaotic diode,” where transmission is periodic in one direction and chaotic in the opposite one, is reported.

  6. Path integral approach to electron scattering in classical electromagnetic potential

    NASA Astrophysics Data System (ADS)

    Chuang, Xu; Feng, Feng; Ying-Jun, Li

    2016-05-01

    As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374360, 11405266, and 11505285) and the National Basic Research Program of China (Grant No. 2013CBA01504).

  7. Three-body scattering from nonperturbative flow equations

    SciTech Connect

    Diehl, S.; Krahl, H. C.; Scherer, M.

    2008-09-15

    We consider fermion-dimer scattering in the presence of a large positive scattering length in the frame of functional renormalization group equations. A flow equation for the momentum dependent fermion-dimer scattering amplitude is derived from first principles in a systematic vertex expansion of the exact flow equation for the effective action. The resummation obtained from the nonperturbative flow is shown to be equivalent to the one performed by the integral equation by Skorniakov and Ter-Martirosian (STM). The flow equation approach allows to integrate out fermions and bosons simultaneously, in line with the fact that the bosons are not fundamental but build up gradually as fluctuation induced bound states of fermions. In particular, the STM result for atom-dimer scattering is obtained by choosing the relative cutoff scales of fermions and bosons such that the fermion fluctuations are integrated out already at the initial stage of the RG evolution.

  8. Limitations in scatter propagation

    NASA Astrophysics Data System (ADS)

    Lampert, E. W.

    1982-04-01

    A short description of the main scatter propagation mechanisms is presented; troposcatter, meteor burst communication and chaff scatter. For these propagation modes, in particular for troposcatter, the important specific limitations discussed are: link budget and resulting hardware consequences, diversity, mobility, information transfer and intermodulation and intersymbol interference, frequency range and future extension in frequency range for troposcatter, and compatibility with other services (EMC).

  9. Compton scattering overview

    SciTech Connect

    Hartemann, F V

    2008-12-01

    An overview of linear and nonlinear Compton scattering is presented, along with a comparison with Thomson scattering. Two distinct processes play important roles in the nonlinear regime: multi-photon interactions, leading to the generation of harmonics, and radiation pressure, yielding a downshift of the radiated spectral features. These mechanisms, their influence on the source brightness, and different modeling strategies are also briefly discussed.

  10. Diffractive hard scattering

    SciTech Connect

    Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

    1986-03-01

    I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

  11. REGIONAL SEISMIC AMPLITUDE MODELING AND TOMOGRAPHY FOR EARTHQUAKE-EXPLOSION DISCRIMINATION

    SciTech Connect

    Walter, W R; Pasyanos, M E; Matzel, E; Gok, R; Sweeney, J; Ford, S R; Rodgers, A J

    2008-07-08

    events and discriminating between natural and man-made seismic events, such as earthquakes and mining activities, and nuclear weapons testing. We continue developing, testing, and refining size-, distance-, and location-based regional seismic amplitude corrections to facilitate the comparison of all events that are recorded at a particular seismic station. These corrections, calibrated for each station, reduce amplitude measurement scatter and improve discrimination performance. We test the methods on well-known (ground truth) datasets in the U.S. and then apply them to the uncalibrated stations in Eurasia, Africa, and other regions of interest to improve underground nuclear test monitoring capability.

  12. Bit-string scattering theory

    SciTech Connect

    Noyes, H.P.

    1990-01-29

    We construct discrete space-time coordinates separated by the Lorentz-invariant intervals h/mc in space and h/mc{sup 2} in time using discrimination (XOR) between pairs of independently generated bit-strings; we prove that if this space is homogeneous and isotropic, it can have only 1, 2 or 3 spacial dimensions once we have related time to a global ordering operator. On this space we construct exact combinatorial expressions for free particle wave functions taking proper account of the interference between indistinguishable alternative paths created by the construction. Because the end-points of the paths are fixed, they specify completed processes; our wave functions are born collapsed''. A convenient way to represent this model is in terms of complex amplitudes whose squares give the probability for a particular set of observable processes to be completed. For distances much greater than h/mc and times much greater than h/mc{sup 2} our wave functions can be approximated by solutions of the free particle Dirac and Klein-Gordon equations. Using a eight-counter paradigm we relate this construction to scattering experiments involving four distinguishable particles, and indicate how this can be used to calculate electromagnetic and weak scattering processes. We derive a non-perturbative formula relating relativistic bound and resonant state energies to mass ratios and coupling constants, equivalent to our earlier derivation of the Bohr relativistic formula for hydrogen. Using the Fermi-Yang model of the pion as a relativistic bound state containing a nucleon-antinucleon pair, we find that (G{sub {pi}N}{sup 2}){sup 2} = (2m{sub N}/m{sub {pi}}){sup 2} {minus} 1. 21 refs., 1 fig.

  13. Aureolegraph internal scattering correction.

    PubMed

    DeVore, John; Villanucci, Dennis; LePage, Andrew

    2012-11-20

    Two methods of determining instrumental scattering for correcting aureolegraph measurements of particulate solar scattering are presented. One involves subtracting measurements made with and without an external occluding ball and the other is a modification of the Langley Plot method and involves extrapolating aureolegraph measurements collected through a large range of solar zenith angles. Examples of internal scattering correction determinations using the latter method show similar power-law dependencies on scattering, but vary by roughly a factor of 8 and suggest that changing aerosol conditions during the determinations render this method problematic. Examples of corrections of scattering profiles using the former method are presented for a range of atmospheric particulate layers from aerosols to cumulus and cirrus clouds. PMID:23207299

  14. Massive quark scattering at strong coupling from AdS/CFT

    SciTech Connect

    Barnes, Edwin; Vaman, Diana

    2010-06-15

    We extend the analysis of Alday and Maldacena for obtaining gluon scattering amplitudes at strong coupling to include external massive quark states. Our quarks are actually the N=2 hypermultiplets which arise when D7-brane probes are included in the AdS{sub 5}xS{sup 5} geometry. We work in the quenched approximation, treating the N=2 matter multiplets as external sources coupled to the N=4 supersymmetric Yang-Mills fields. We first derive appropriate massive-particle boundary conditions for the string scattering world sheets. We then find an exact world sheet which corresponds to the scattering of two massive quarks and two massless gluons and extract from this the associated scattering amplitude. We also find the world sheet and amplitude for the scattering of four massive quarks. Our world sheet solutions reduce to the four massless gluon solution of Alday and Maldacena in the limit of zero quark mass. The amplitudes we compute can also be interpreted in terms of 2-2 scattering involving gluons and massive W bosons.

  15. Discriminating Simulated Vocal Tremor Source Using Amplitude Modulation Spectra

    PubMed Central

    Carbonell, Kathy M.; Lester, Rosemary A.; Story, Brad H.; Lotto, Andrew J.

    2014-01-01

    Objectives/Hypothesis Sources of vocal tremor are difficult to categorize perceptually and acoustically. This paper describes a preliminary attempt to discriminate vocal tremor sources through the use of spectral measures of the amplitude envelope. The hypothesis is that different vocal tremor sources are associated with distinct patterns of acoustic amplitude modulations. Study Design Statistical categorization methods (discriminant function analysis) were used to discriminate signals from simulated vocal tremor with different sources using only acoustic measures derived from the amplitude envelopes. Methods Simulations of vocal tremor were created by modulating parameters of a vocal fold model corresponding to oscillations of respiratory driving pressure (respiratory tremor), degree of vocal fold adduction (adductory tremor) and fundamental frequency of vocal fold vibration (F0 tremor). The acoustic measures were based on spectral analyses of the amplitude envelope computed across the entire signal and within select frequency bands. Results The signals could be categorized (with accuracy well above chance) in terms of the simulated tremor source using only measures of the amplitude envelope spectrum even when multiple sources of tremor were included. Conclusions These results supply initial support for an amplitude-envelope based approach to identify the source of vocal tremor and provide further evidence for the rich information about talker characteristics present in the temporal structure of the amplitude envelope. PMID:25532813

  16. Large amplitude ion-acoustic solitons in dusty plasmas

    SciTech Connect

    Tiwari, R. S.; Jain, S. L.; Mishra, M. K.

    2011-08-15

    Characteristics of ion-acoustic soliton in dusty plasma, including the dynamics of heavily charged massive dust grains, are investigated following the Sagdeev Potential formalism. Retaining fourth order nonlinearities of electric potential in the expansion of the Sagdeev Potential in the energy equation for a pseudo particle and integrating the resulting energy equation, large amplitude soliton solution is determined. Variation of amplitude (A), half width (W) at half maxima and the product P = AW{sup 2} of the Korteweg-deVries (KdV), dressed and large amplitude soliton as a function of wide range of dust concentration are numerically studied for recently observed parameters of dusty plasmas. We have also presented the region of existence of large amplitude ion-acoustic soliton in the dusty plasma by analyzing the structure of the pseudo potential. It is found that in the presence of positively charged dust grains, system supports only compressive solitons, on the other hand, in the presence of negatively charged dust grains, the system supports compressive solitons up to certain critical concentration of dust grains and above this critical concentration, the system can support rarefactive solitons also. The effects of dust concentration, charge, and mass of the dust grains, on the characteristics of KdV, dressed and large amplitude the soliton, i.e., amplitude (A), half width at half maxima (W), and product of amplitude (A) and half width at half maxima (P = AW{sup 2}), are discussed in detail.

  17. Broadband metasurface holograms: toward complete phase and amplitude engineering.

    PubMed

    Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Gu, Jianqiang; Li, Yanfeng; Tian, Zhen; Singh, Ranjan; Zhang, Shuang; Han, Jiaguang; Zhang, Weili

    2016-01-01

    As a revolutionary three-dimensional imaging technique, holography has attracted wide attention for its ability to photographically record a light field. However, traditional phase-only or amplitude-only modulation holograms have limited image quality and resolution to reappear both amplitude and phase information required of the objects. Recent advances in metasurfaces have shown tremendous opportunities for using a planar design of artificial meta-atoms to shape the wave front of light by optimal control of both its phase and amplitude. Inspired by the concept of designer metasurfaces, we demonstrate a novel amplitude-phase modulation hologram with simultaneous five-level amplitude modulation and eight-level phase modulation. Such a design approach seeks to turn the perceived disadvantages of the traditional phase or amplitude holograms, and thus enable enhanced performance in resolution, homogeneity of amplitude distribution, precision, and signal-to-noise ratio. In particular, the unique holographic approach exhibits broadband characteristics. The method introduced here delivers more degrees of freedom, and allows for encoding highly complex information into designer metasurfaces, thus having the potential to drive next-generation technological breakthroughs in holography. PMID:27615519

  18. Scattering of spin-polarized electron in an Aharonov Bohm potential

    NASA Astrophysics Data System (ADS)

    Khalilov, V. R.; Ho, Choon-Lin

    2008-05-01

    The scattering of spin-polarized electrons in an Aharonov-Bohm vector potential is considered. We solve the Pauli equation in 3 + 1 dimensions taking into account explicitly the interaction between the three-dimensional spin magnetic moment of electron and magnetic field. Expressions for the scattering amplitude and the cross section are obtained for spin-polarized electron scattered off a flux tube of small radius. It is also shown that bound electron states cannot occur in this quantum system. The scattering problem for the model of a flux tube of zero radius in the Born approximation is briefly discussed.

  19. Broadband active tuning of unidirectional scattering from nanoantenna using combined radially and azimuthally polarized beams.

    PubMed

    Xi, Z; Wei, L; Adam, A J L; Urbach, H P

    2016-01-01

    We propose an approach to actively tune the scattering pattern of a Mie-type spherical antenna. The scheme is based on separate control over the induced electric dipole and induced magnetic dipole using two coherent focused beams of radial polarization and azimuthal polarization, respectively. By carefully tuning the amplitude and phase relation of the two beams, a broadband unidirectional scattering can be achieved, even at the antenna's resonant wavelength where the antenna scatters efficiently. By moving the focus of one beam, a drastic switch of the unidirectional scattering can be observed. Such a scheme enables the design of ultra-compact optical switches and directional couplers based on nanoantennas. PMID:26696151

  20. FEFF5: An ab initio multiple scattering XAFS code. [In FORTRAN 77

    SciTech Connect

    Rehr, J.J.; Zabinsky, S.I.

    1992-01-01

    FEFF5 is an efficient automated code which calculates multiple scattering (MS) curved wave XAFS spectra for molecules and solids. The theoretical ingredients and approximations contained in the code are revised, with the aim of describing the how XAFS spectra are efficiently simulated. The FEFF5 code consists of 4 independent modules: a scattering potential and phase shift module, a path finder module, a scattering amplitude module and an XAFS module. Multiple scattering Debye-Waller factors are built in using a correlated Debye model.

  1. Amplitude Modulation in the δ Sct star KIC 7106205

    NASA Astrophysics Data System (ADS)

    Bowman, Dominic. M.; Kurtz, Donald W.

    2015-09-01

    The δ Sct star KIC 7106205 showed amplitude modulation in a single p mode, whilst all other p and g modes remained stable in amplitude and phase over 1470 d of the Kepler dataset. The data were divided into 30 time bins of equal length and a series of consecutive Fourier transforms was calculated. A fixed frequency, calculated from a least-squares fit of all data, allowed amplitude and phase for every mode in each time bin to be tracked. The missing p mode energy was not transferred to any other visible modes.

  2. Segmentation Of Multifrequency Complex-Amplitude SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Chellappa, Ramalingam

    1994-01-01

    Several mathematical models and associated algorithms implement method of segmenting multifrequency, highly speckled, high-resolution, complex-amplitude (amplitude and phase) synthetic-aperture-radar (SAR) digitized image into regions, within each of which radar backscattering characteristics are similar or homogeneous from place to place. Typically, each region represents different type of terrain or other surface; e.g., forest, agricultural land, sea ice, or water. Method of segmentation of SAR scene into regions is product of generalization, to multifrequency case, of single-frequency method described in "Algorithms for Segmentation of Complex-Amplitude SAR Data" (NPO-18524).

  3. Correction to Molière's formula for multiple scattering

    NASA Astrophysics Data System (ADS)

    Lee, R. N.; Milstein, A. I.

    2009-06-01

    The semiclassical correction to Molière’s formula for multiple scattering is derived. The consideration is based on the scattering amplitude obtained with the first semiclassical correction taken into account for an arbitrary localized but not spherically symmetric potential. Unlike the leading term, the correction to Molière’s formula contains the target density n and thickness L not only in the combination nL (areal density). Therefore, this correction can be referred to as the bulk density correction. It turns out that the bulk density correction is small even for high density. This result explains the wide range of applicability of Molière’s formula.

  4. Spin observables in neutron-proton elastic scattering

    SciTech Connect

    Ahmidouch, A.; Arnold, J.; van den Brandt, B.; Daum, M.; Demierre, P.; Drevenak, R.; Finger, M. |; Finger, M. Jr.; Franz, J.; Goujon, N.; Hautle, P.; Janout, Z. Jr.; Hajdas, W.; Heer, E.; Hess, R.; Koger, R.; Konter, J.A.; Lacker, H.; Lechanoine-LeLuc, C.; Lehar, F.; Mango, S.; Mascarini, C.; Rapin, D.; Roessle, E.; Schmelzbach, P.A.; Schmitt, H.; Sereni, P.; Slunecka, M.

    1995-07-15

    We describe here two experiments presently running at PSI using the NA2 polarized neutron beam. They are devoted to the measurement of 2- and 3-spin observables in {ital np} elastic scattering for kinetic energies from 230 to 590 MeV with a center of mass angular range from 60 to 180 degrees. The goal is to determine the five {ital NN} scattering amplitudes for isospin 0 in a model independent way. Preliminary results for {ital K}{sub {ital OSKO}} and {ital K}{sub {ital OSSO}} spin-transfers are presented.

  5. Deeply virtual Compton scattering via color dipoles: Nonperturbative effects

    SciTech Connect

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2009-02-01

    We study the deeply virtual Compton scattering amplitude within the color dipole approach. The light-cone wave function of a real photon is evaluated in the instanton vacuum model. Our parameter-free calculations are able to describe H1 data, both the absolute values and the t dependences, at medium-high values of Q{sup 2}. The Q{sup 2} dependence is found to be sensitive to the choice of the phenomenological cross section fitted to deep-inelastic scattering data.

  6. Molecular alignment and orientation with a hybrid Raman scattering technique

    NASA Astrophysics Data System (ADS)

    Bustard, Philip J.; Lausten, R.; Sussman, Benjamin J.

    2012-11-01

    We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics.

  7. Partial Wave Dispersion Relations: Application to Electron-Atom Scattering

    NASA Technical Reports Server (NTRS)

    Temkin, A.; Drachman, Richard J.

    1999-01-01

    In this Letter we propose the use of partial wave dispersion relations (DR's) as the way of solving the long-standing problem of correctly incorporating exchange in a valid DR for electron-atom scattering. In particular a method is given for effectively calculating the contribution of the discontinuity and/or poles of the partial wave amplitude which occur in the negative E plane. The method is successfully tested in three cases: (i) the analytically solvable exponential potential, (ii) the Hartree potential, and (iii) the S-wave exchange approximation for electron-hydrogen scattering.

  8. Beam-charge azimuthal asymmetry and deeply virtual Compton scattering

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Andrus, A.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetissian, E.; Bailey, P.; Balin, D.; Beckmann, M.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Borissov, A.; Borysenko, A.; Bouwhuis, M.; Brüll, A.; Bryzgalov, V.; Capiluppi, M.; Capitani, G. P.; Chen, T.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; de Leo, R.; Demey, M.; de Nardo, L.; de Sanctis, E.; Devitsin, E.; di Nezza, P.; Dreschler, J.; Düren, M.; Ehrenfried, M.; Elalaoui-Moulay, A.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Funel, A.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Garrow, K.; Gaskell, D.; Gavrilov, G.; Gharibyan, V.; Grebeniouk, O.; Gregor, I. M.; Hadjidakis, C.; Hafidi, K.; Hartig, M.; Hasch, D.; Hesselink, W. H. A.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hommez, B.; Hristova, I.; Iarygin, G.; Ivanilov, A.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Kaiser, R.; Kinney, E.; Kisselev, A.; Kobayashi, T.; Kopytin, M.; Korotkov, V.; Kozlov, V.; Krauss, B.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Laziev, A.; Lenisa, P.; Liebing, P.; Linden-Levy, L. A.; Lorenzon, W.; Lu, H.; Lu, J.; Lu, S.; Ma, B.-Q.; Maiheu, B.; Makins, N. C. R.; Mao, Y.; Marianski, B.; Marukyan, H.; Masoli, F.; Mexner, V.; Meyners, N.; Michler, T.; Mikloukho, O.; Miller, C. A.; Miyachi, Y.; Muccifora, V.; Murray, M.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Negodaev, M.; Nowak, W.-D.; Oganessyan, K.; Ohsuga, H.; Osborne, A.; Pickert, N.; Potterveld, D. H.; Raithel, M.; Reggiani, D.; Reimer, P. E.; Reischl, A.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanjiev, I.; Savin, I.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seele, J.; Seidl, R.; Seitz, B.; Shanidze, R.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Sinram, K.; Sommer, W.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Tait, P.; Tanaka, H.; Taroian, S.; Tchuiko, B.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P. B.; van der Steenhoven, G.; van Haarlem, Y.; Vikhrov, V.; Vincter, M. G.; Vogel, C.; Volmer, J.; Wang, S.; Wendland, J.; Ye, Y.; Ye, Z.; Yen, S.; Zihlmann, B.; Zupranski, P.

    2007-01-01

    The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions.

  9. Calculates Thermal Neutron Scattering Kernel.

    Energy Science and Technology Software Center (ESTSC)

    1989-11-10

    Version 00 THRUSH computes the thermal neutron scattering kernel by the phonon expansion method for both coherent and incoherent scattering processes. The calculation of the coherent part is suitable only for calculating the scattering kernel for heavy water.

  10. Higgs amplitude mode in massless Dirac fermion systems

    NASA Astrophysics Data System (ADS)

    Lu, Ming; Liu, Haiwen; Wang, Pei; Xie, X. C.

    2016-02-01

    The Higgs amplitude mode in superconductors is the condensed-matter analogy of Higgs bosons in particle physics. We investigate the time evolution of Higgs amplitude mode in massless Dirac systems induced by a weak quench of an attractive interaction. We find that the Higgs amplitude mode in the half-filled honeycomb lattice has a logarithmic decaying behavior, qualitatively different from the 1 /√{t } decay in the normal superconductors. Our study is also extended to the doped cases in honeycomb lattices. As for the three-dimensional Dirac semimetal at half filling, we obtain an undamped oscillation of the amplitude mode. Our finding is not only an important supplement to the previous theoretical studies on normal fermion systems but also provides an experimental signature to characterize the superconductivity in two- or three-dimensional Dirac systems.

  11. Amplitude chimeras and chimera death in dynamical networks

    NASA Astrophysics Data System (ADS)

    Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard

    2016-06-01

    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.

  12. Combination frequencies in high-amplitude δ Scuti stars

    NASA Astrophysics Data System (ADS)

    Balona, L. A.

    2016-06-01

    Short-cadence observations of δ Scuti stars in the Kepler field are used to investigate the physical nature of high-amplitude δ Scuti stars (HADS). Although it is often mentioned that HADS are transition objects between classical Cepheids and δ Scuti stars, neither ground-based or space-based observations support this view. It is found that HADS occur randomly within the instability strip. The possibility that HADS may be defined by the presence of combination frequencies is discussed. There is a weak tendency for the number of combination frequencies to increase with increasing amplitude of the parent frequencies. However, even stars with very low amplitudes may have detectable combination frequencies. Very few parent modes have a period ratio appropriate to first-overtone and fundamental radial modes. It appears that a high amplitude, in itself, is not useful as a distinguishing feature of δ Scuti stars.

  13. Moments of pseudoscalar meson distribution amplitudes from the lattice

    SciTech Connect

    Braun, V. M.; Goeckeler, M.; Horsley, R.; Zanotti, J. M.; Perlt, H.; Schiller, A.; Pleiter, D.; Schroers, W.; Schierholz, G.; Stueben, H.

    2006-10-01

    Based on lattice simulations with two flavors of dynamical, O(a)-improved Wilson fermions we present results for the first two moments of the distribution amplitudes of pseudoscalar mesons at several values of the valence quark masses. By extrapolating our results to the physical masses of up/down and strange quarks, we find the first two moments of the K{sup +} distribution amplitude and the second moment of the {pi}{sup +} distribution amplitude. We use nonperturbatively determined renormalization coefficients to obtain results in the MS scheme. At a scale of 4 GeV{sup 2} we find a{sub 2}{sup {pi}}=0.201(114) for the second Gegenbauer moment of the pion's distribution amplitude, while for the kaon, a{sub 1}{sup K}=0.0453(9)(29) and a{sub 2}{sup K}=0.175(18)(47)

  14. Non-perturbative QCD amplitudes in quenched and eikonal approximations

    SciTech Connect

    Fried, H.M.; Grandou, T.; Sheu, Y.-M.

    2014-05-15

    Even though approximated, strong coupling non-perturbative QCD amplitudes remain very difficult to obtain. In this article, in eikonal and quenched approximations at least, physical insights are presented that rely on the newly-discovered property of effective locality. The present article also provides a more rigorous mathematical basis for the crude approximations used in the previous derivation of the binding potential of quarks and nucleons. Furthermore, the techniques of Random Matrix calculus along with Meijer G-functions are applied to analyze the generic structure of fermionic amplitudes in QCD. - Highlights: • We discuss the physical insight of effective locality to QCD fermionic amplitudes. • We show that an unavoidable delta function goes along with the effective locality property. • The generic structure of QCD fermion amplitudes is obtained through Random Matrix calculus.

  15. High Amplitude (delta)-Scutis in the Large Magellanic Cloud

    SciTech Connect

    Garg, A; Cook, K H; Nikolaev, S; Huber, M E; Rest, A; Becker, A C; Challis, P; Clocchiatti, A; Miknaitis, G; Minniti, D; Morelli, L; Olsen, K; Prieto, J L; Suntzeff, N B; Welch, D L; Wood-Vasey, W M

    2010-01-25

    The authors present 2323 High-Amplitude {delta}-Scutis (HADS) candidates discovered in the Large Magellanic Cloud (LMC) by the SuperMACHO survey (Rest et al. 2005). Frequency analyses of these candidates reveal that several are multimode pulsators, including 119 whose largest amplitude of pulsation is in the fundamental (F) mode and 19 whose largest amplitude of pulsation is in the first overtone (FO) mode. Using Fourier decomposition of the HADS light curves, they find that the period-luminosity (PL) relation defined by the FO pulsators does not show a clear separation from the PL-relation defined by the F pulsators. This differs from other instability strip pulsators such as type c RR Lyrae. They also present evidence for a larger amplitude, subluminous population of HADS similar to that observed in Fornax (Poretti et al. 2008).

  16. Optical vector network analyzer based on amplitude-phase modulation

    NASA Astrophysics Data System (ADS)

    Morozov, Oleg G.; Morozov, Gennady A.; Nureev, Ilnur I.; Kasimova, Dilyara I.; Zastela, Mikhail Y.; Gavrilov, Pavel V.; Makarov, Igor A.; Purtov, Vadim A.

    2016-03-01

    The article describes the principles of optical vector network analyzer (OVNA) design for fiber Bragg gratings (FBG) characterization based on amplitude-phase modulation of optical carrier that allow us to improve the measurement accuracy of amplitude and phase parameters of the elements under test. Unlike existing OVNA based on a single-sideband and unbalanced double sideband amplitude modulation, the ratio of the two side components of the probing radiation is used for analysis of amplitude and phase parameters of the tested elements, and the radiation of the optical carrier is suppressed, or the latter is used as a local oscillator. The suggested OVNA is designed for the narrow band-stop elements (π-phaseshift FBG) and wide band-pass elements (linear chirped FBG) research.

  17. Amplitude sorting of oscillatory burst signals by sampling

    DOEpatents

    Davis, Thomas J.

    1977-01-01

    A method and apparatus for amplitude sorting of oscillatory burst signals is described in which the burst signal is detected to produce a burst envelope signal and an intermediate or midportion of such envelope signal is sampled to provide a sample pulse output. The height of the sample pulse is proportional to the amplitude of the envelope signal and to the maximum burst signal amplitude. The sample pulses are fed to a pulse height analyzer for sorting. The present invention is used in an acoustic emission testing system to convert the amplitude of the acoustic emission burst signals into sample pulse heights which are measured by a pulse height analyzer for sorting the pulses in groups according to their height in order to identify the material anomalies in the test material which emit the acoustic signals.

  18. Movement amplitude and tempo change in piano performance

    NASA Astrophysics Data System (ADS)

    Palmer, Caroline

    2001-05-01

    Music performance places stringent temporal and cognitive demands on individuals that should yield large speed/accuracy tradeoffs. Skilled piano performance, however, shows consistently high accuracy across a wide variety of rates. Movement amplitude may affect the speed/accuracy tradeoff, so that high accuracy can be obtained even at very fast tempi. The contribution of movement amplitude changes in rate (tempo) is investigated with motion capture. Cameras recorded pianists with passive markers on hands and fingers, who performed on an electronic (MIDI) keyboard. Pianists performed short melodies at faster and faster tempi until they made errors (altering the speed/accuracy function). Variability of finger movements in the three motion planes indicated most change in the plane perpendicular to the keyboard across tempi. Surprisingly, peak amplitudes of motion before striking the keys increased as tempo increased. Increased movement amplitudes at faster rates may reduce or compensate for speed/accuracy tradeoffs. [Work supported by Canada Research Chairs program, HIMH R01 45764.

  19. Interference effects in proton scattering on {sup 15}N nuclei at intermediate energies

    SciTech Connect

    Ibraeva, E. T.; Zhusupov, M.A.; Imambekov, O.; Krassovitskiy, P. M.

    2010-08-15

    The differential cross section for proton scattering on {sup 15}N nuclei is calculated within Glauber diffraction theory at energies of 0.2, 0.6, and 1.0 GeV. Use is made of the shell-model wave function for the {sup 15}N nucleus. The contribution of single and double collisions to the Glauber operator {Omega} is taken into account. The sensitivity of the differential cross sections to the contributions of scattering on nucleons from different shells, to the parameters of the elementary pN amplitude, and to the energy of projectile protons is investigated. It is shown that the interference between amplitudes corresponding to different collision multiplicities, as well as between the amplitudes for scattering on nucleons from different shells, determines special features of the cross section.

  20. A FORTRAN code for the scattering of EM plane waves by an infinitely long cylinder at oblique incidence

    NASA Astrophysics Data System (ADS)

    Yousif, Hashim A.; Boutros, Edward

    1992-03-01

    The analytical equations for the scattering of electromagnetic (EM) waves from an infinitely long cylinder of arbitrary radius and refractive index at oblique incidence are programmed in FORTRAN. The calculated quantities include the scattering coefficients, the scattering amplitudes and intensities, cross sections for scattering and extinction, and the Mueller scattering matrix elements ( S ij). The range of the input parameters (radius, refractive index, and the tilt angle) are discussed and it is expected that the program gives reliable results provided that the size parameter of the cylinder is not too small ( k0a≥0.05).

  1. Three-point disc amplitudes in the RNS formalism

    NASA Astrophysics Data System (ADS)

    Becker, Katrin; Becker, Melanie; Robbins, Daniel; Su, Ning

    2016-06-01

    We calculate all tree level string theory vacuum to Dp-brane disc amplitudes involving an arbitrary RR-state and two NS-NS vertex operators. This computation was earlier performed by K. Becker, Guo, and Robbins for the simplest case of a RR-state of type C (p - 3). Here we use the aid of a computer to calculate all possible three-point amplitudes involving a RR-vertex operator of type C (p + 1 + 2 k).

  2. Weak measurements measure probability amplitudes (and very little else)

    NASA Astrophysics Data System (ADS)

    Sokolovski, D.

    2016-04-01

    Conventional quantum mechanics describes a pre- and post-selected system in terms of virtual (Feynman) paths via which the final state can be reached. In the absence of probabilities, a weak measurement (WM) determines the probability amplitudes for the paths involved. The weak values (WV) can be identified with these amplitudes, or their linear combinations. This allows us to explain the "unusual" properties of the WV, and avoid the "paradoxes" often associated with the WM.

  3. Suppression of Rayleigh-scattering-induced noise in OEOs.

    PubMed

    Okusaga, Olukayode; Cahill, James P; Docherty, Andrew; Menyuk, Curtis R; Zhou, Weimin; Carter, Gary M

    2013-09-23

    Optoelectronic oscillators (OEOs) are hybrid RF-photonic devices that promise to be environmentally robust high-frequency RF sources with very low phase noise. Previously, we showed that Rayleigh-scattering-induced noise in optical fibers coupled with amplitude-to-phase noise conversion in photodetectors and amplifiers leads to fiber-length-dependent noise in OEOs. In this work, we report on two methods for the suppression of this fiber-length-dependent noise: altering the amplitude-dependent phase delay of the OEO loops and suppressing the Rayleigh-scattering-induced noise in optical fibers. We report a 20 dB reduction in the flicker phase noise of a 6 km OEO via these suppression techniques. PMID:24104117

  4. Dispersion relation bounds for {pi}{pi} scattering

    SciTech Connect

    Manohar, Aneesh V.; Mateu, Vicent

    2008-05-01

    Axiomatic principles such as analyticity, unitarity, and crossing symmetry constrain the second derivative of the {pi}{pi} scattering amplitudes in some channels to be positive in a region of the Mandelstam plane. Since this region lies in the domain of validity of chiral perturbation theory, we can use these positivity conditions to bound linear combinations of l{sub 1} and l{sub 2}. We compare our predictions with those derived previously in the literature using similar methods. We compute the one-loop {pi}{pi} scattering amplitude in the linear sigma model (LSM) using the MS scheme, a result hitherto absent in the literature. The LSM values for l{sub 1} and l{sub 2} violate the bounds for small values of m{sub {sigma}}/m{sub {pi}}. We show how this can occur, while still being consistent with the axiomatic principles.

  5. MODE CONVERSION BETWEEN DIFFERENT RADIAL ORDERS FOR SOLAR ACOUSTIC WAVES SCATTERED BY SUNSPOTS

    SciTech Connect

    Zhao, Hui; Chou, Dean-Yi

    2013-11-20

    We study the mode conversion between different radial orders for solar acoustic waves interacting with sunspots. Solar acoustic waves are modified in the presence of sunspots. The modification in the wave can be viewed as that the sunspot, excited by the incident wave, generates the scattered wave, and the scattered wave is added to the incident wave to form the total wave inside and around the sunspot. The wavefunction of the acoustic wave on the solar surface is computed from the cross-correlation function. The wavefunction of the scattered wave is obtained by subtracting the wavefunction of the incident wave from that of the total wave. We use the incident waves of radial order n = 0-5 to measure the scattered wavefunctions from n to another radial order n' for NOAAs 11084 and 11092. The strength of scattered waves decreases rapidly with |Δn|, where Δn ≡ n' – n. The scattered waves of Δn = ±1 are visible for n ≤ 1, and significant for n ≥ 2. For the scattered wave of Δn = ±2, only few cases are visible. None of the scattered waves of Δn = ±3 are visible. The properties of scattered waves for Δn = 0 and Δn ≠ 0 are different. The scattered wave amplitude relative to the incident wave amplitude decreases with n for Δn = 0, while it increases with n for Δn ≠ 0. The scattered wave amplitudes of Δn = 0 are greater for the larger sunspot, while those of Δn ≠ 0 are insensitive to the sunspot size.

  6. Test of 600 and 750 MeV NN matrix on elastic scattering Glauber model calculations

    NASA Astrophysics Data System (ADS)

    Brissaud, I.

    1980-09-01

    The 600 and 750 MeV proton nucleus elastic scattering cross section and polarization calculations have been performed in the framework of the Glauber model to test the pp and pn scattering amplitudes deduced from a phase shift analysis by Bystricky, Lechanoine and Lehar. It is well known that up to now we do not possess a non-phenomenological NN scattering matrix at intermediate energies. However proton-nucleus scattering analyses are used to extract information about short range correlations1), Δ resonance2) or pion condensation presences)... etc. Most scattering calculations made at these energies have been done with phenomenological NN amplitudes having a gaussian q-dependence 10050_2005_Article_BF01438168_TeX2GIFE1.gif A(q) = {kσ }/{4π }(α + i) e^{ - β ^2 q^2 /2} and 10050_2005_Article_BF01438168_TeX2GIFE2.gif C(q) = {kσ }/{4π }iq(α + i) D_e - β ^2 q^2 /2 K and σ being respectively the projectile momentum and the total pN total cross section. The parameters α, β and D are badly known and are adjusted by fitting some specific reactions as p+4He elastic scattering4). Even when these amplitudes provide good fits to the data, our understanding of the dynamics of the scattering remains obscure.

  7. Dependence of kink oscillation damping on the amplitude

    NASA Astrophysics Data System (ADS)

    Goddard, C. R.; Nakariakov, V. M.

    2016-05-01

    Context. Kink oscillations of coronal loops are one of the most intensively studied oscillatory phenomena in the solar corona. In the large-amplitude rapidly damped regime, these oscillations are observed to have a low quality factor with only a few cycles of oscillation detected before they are damped. The specific mechanism responsible for rapid damping is commonly accepted to be associated with the linear coupling between collective kink oscillations and localised torsional oscillations, the phenomenon of resonant absorption of the kink mode. The role of finite amplitude effects, however, is still not clear. Aims: We investigated the empirical dependence of the kink oscillation damping time and its quality factor, which is defined as the ratio of damping time to oscillation period, on the oscillation amplitude. Methods: We analysed decaying kink oscillation events detected previously with TRACE, SDO/AIA and and STEREO/EUVI in the extreme ultraviolet (EUV) 171 Å band. Results: We found that the ratio of the kink oscillation damping time to the oscillation period systematically decreases with the oscillation amplitude. We approximated the quality factor dependence on the oscillation displacement amplitude via the power-law dependence with the exponent of -1/2, however we stress that this is a by-eye estimate, and a more rigorous estimation of the scaling law requires more accurate measurements and increased statistics. We conclude that damping of kink oscillations of coronal loops depends on the oscillation amplitude, indicating the possible role of non-linear mechanisms for damping.

  8. Perceptual sensitivity to first harmonic amplitude in the voice source.

    PubMed

    Kreiman, Jody; Gerratt, Bruce R

    2010-10-01

    Little is known about the perceptual importance of changes in the shape of the source spectrum, although many measures have been proposed and correlations with different vocal qualities (breathiness, roughness, nasality, strain...) have frequently been reported. This study investigated just-noticeable differences in the relative amplitudes of the first two harmonics (H1-H2) for speakers of Mandarin and English. Listeners heard pairs of vowels that differed only in the amplitude of the first harmonic and judged whether or not the voice tokens were identical in voice quality. Across voices and listeners, just-noticeable-differences averaged 3.18 dB. This value is small relative to the range of values across voices, indicating that H1-H2 is a perceptually valid acoustic measure of vocal quality. For both groups of listeners, differences in the amplitude of the first harmonic were easier to detect when the source spectral slope was steeply falling so that F0 dominated the spectrum. Mandarin speakers were significantly more sensitive (by about 1 dB) to differences in first harmonic amplitudes than were English speakers. Two explanations for these results are possible: Mandarin speakers may have learned to hear changes in harmonic amplitudes due to changes in voice quality that are correlated with the tones of Mandarin; or Mandarin speakers' experience with tonal contrasts may increase their sensitivity to small differences in the amplitude of F0 (which is also the first harmonic). PMID:20968379

  9. A proposed physical analog for a quantum probability amplitude

    NASA Astrophysics Data System (ADS)

    Boyd, Jeffrey

    What is the physical analog of a probability amplitude? All quantum mathematics, including quantum information, is built on amplitudes. Every other science uses probabilities; QM alone uses their square root. Why? This question has been asked for a century, but no one previously has proposed an answer. We will present cylindrical helices moving toward a particle source, which particles follow backwards. Consider Feynman's book QED. He speaks of amplitudes moving through space like the hand of a spinning clock. His hand is a complex vector. It traces a cylindrical helix in Cartesian space. The Theory of Elementary Waves changes direction so Feynman's clock faces move toward the particle source. Particles follow amplitudes (quantum waves) backwards. This contradicts wave particle duality. We will present empirical evidence that wave particle duality is wrong about the direction of particles versus waves. This involves a paradigm shift; which are always controversial. We believe that our model is the ONLY proposal ever made for the physical foundations of probability amplitudes. We will show that our ``probability amplitudes'' in physical nature form a Hilbert vector space with adjoints, an inner product and support both linear algebra and Dirac notation.

  10. Mapping Pn amplitude spreading and attenuation in Asia

    SciTech Connect

    Yang, Xiaoning; Phillips, William S; Stead, Richard J

    2010-12-06

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  11. One-loop gluonic amplitudes from single unitarity cuts

    NASA Astrophysics Data System (ADS)

    Glover, E. W. Nigel; Williams, Ciaran

    2008-12-01

    We show that one-loop amplitudes in massless gauge theories can be determined from single cuts. By cutting a single propagator and putting it on-shell, the integrand of an n-point one-loop integral is transformed into an (n+2)-particle tree level amplitude. The single-cut approach described here is complementary to the double or multiple unitarity cut approaches commonly used in the literature. In common with these approaches, if the cut is taken in four dimensions, one finds only the cut-constructible parts of the amplitude, while if the cut is in D = 4-2epsilon dimensions, both rational and cut-constructible parts are obtained. We test our method by reproducing the known results for the fully rational all-plus and mostly-plus QCD amplitudes, A(1)4(1+, 2+, 3+, 4+) and A(1)5(1+, 2+, 3+, 4+, 5+). We also rederive expressions for the scalar loop contribution to the four-gluon MHV amplitude, A4(1,Script N = 0)(-, -, +, +) which has both cut-constructible and rational contributions, and the fully cut-constructible n-gluon MHV amplitude in Script N = 4 Supersymmetric Yang-Mills, A4(1,Script N = 4)(-, -, +, ..., +).

  12. A dynamical formulation of one-dimensional scattering theory and its applications in optics

    SciTech Connect

    Mostafazadeh, Ali

    2014-02-15

    We develop a dynamical formulation of one-dimensional scattering theory where the reflection and transmission amplitudes for a general, possibly complex and energy-dependent, scattering potential are given as solutions of a set of dynamical equations. By decoupling and partially integrating these equations, we reduce the scattering problem to a second order linear differential equation with universal initial conditions that is equivalent to an initial-value time-independent Schrödinger equation. We give explicit formulas for the reflection and transmission amplitudes in terms of the solution of either of these equations and employ them to outline an inverse-scattering method for constructing finite-range potentials with desirable scattering properties at any prescribed wavelength. In particular, we construct optical potentials displaying threshold lasing, antilasing, and unidirectional invisibility. -- Highlights: • Proposes a dynamical theory of scattering in one dimension. • Derives and solves dynamical equations for scattering data. • Gives a new inverse scattering prescription. • Constructs optical potentials with desired scattering properties.

  13. Rayleigh Scattering Diagnostics Workshop

    NASA Technical Reports Server (NTRS)

    Seasholtz, Richard (Compiler)

    1996-01-01

    The Rayleigh Scattering Diagnostics Workshop was held July 25-26, 1995 at the NASA Lewis Research Center in Cleveland, Ohio. The purpose of the workshop was to foster timely exchange of information and expertise acquired by researchers and users of laser based Rayleigh scattering diagnostics for aerospace flow facilities and other applications. This Conference Publication includes the 12 technical presentations and transcriptions of the two panel discussions. The first panel was made up of 'users' of optical diagnostics, mainly in aerospace test facilities, and its purpose was to assess areas of potential applications of Rayleigh scattering diagnostics. The second panel was made up of active researchers in Rayleigh scattering diagnostics, and its purpose was to discuss the direction of future work.

  14. Intra-beam scattering

    NASA Astrophysics Data System (ADS)

    Piwinski, A.

    Intra-beam scattering is analysed and the rise times or damping times of the beam dimensions are derived. The theoretical results are compared with experimental values obtained on the CERN AA and SPS machines.

  15. Electron scattering from pyrimidine

    NASA Astrophysics Data System (ADS)

    Colmenares, Rafael; Fuss, Martina C.; Oller, Juan C.; Muñoz, Antonio; Blanco, Francisco; Almeida, Diogo; Limão-Vieira, Paulo; García, Gustavo

    2014-04-01

    Electron scattering from pyrimidine (C4H4N2) was investigated over a wide range of energies. Following different experimental and theoretical approaches, total, elastic and ionization cross sections as well as electron energy loss distributions were obtained.

  16. Cosmic Ray Scattering Radiography

    NASA Astrophysics Data System (ADS)

    Morris, C. L.

    2015-12-01

    Cosmic ray muons are ubiquitous, are highly penetrating, and can be used to measure material densities by either measuring the stopping rate or by measuring the scattering of transmitted muons. The Los Alamos team has studied scattering radiography for a number of applications. Some results will be shown of scattering imaging for a range of practical applications, and estimates will be made of the utility of scattering radiography for nondestructive assessments of large structures and for geological surveying. Results of imaging the core of the Toshiba Nuclear Critical Assembly (NCA) Reactor in Kawasaki, Japan and simulations of imaging the damaged cores of the Fukushima nuclear reactors will be presented. Below is an image made using muons of a core configuration for the NCA reactor.

  17. Positron-rubidium scattering

    NASA Technical Reports Server (NTRS)

    Mceachran, R. P.; Horbatsch, M.; Stauffer, A. D.

    1990-01-01

    A 5-state close-coupling calculation (5s-5p-4d-6s-6p) was carried out for positron-Rb scattering in the energy range 3.7 to 28.0 eV. In contrast to the results of similar close-coupling calculations for positron-Na and positron-K scattering the (effective) total integrated cross section has an energy dependence which is contrary to recent experimental measurements.

  18. Nonlinear damping of a finite amplitude whistler wave due to modified two stream instability

    SciTech Connect

    Saito, Shinji; Nariyuki, Yasuhiro; Umeda, Takayuki

    2015-07-15

    A two-dimensional, fully kinetic, particle-in-cell simulation is used to investigate the nonlinear development of a parallel propagating finite amplitude whistler wave (parent wave) with a wavelength longer than an ion inertial length. The cross field current of the parent wave generates short-scale whistler waves propagating highly oblique directions to the ambient magnetic field through the modified two-stream instability (MTSI) which scatters electrons and ions parallel and perpendicular to the magnetic field, respectively. The parent wave is largely damped during a time comparable to the wave period. The MTSI-driven damping process is proposed as a cause of nonlinear dissipation of kinetic turbulence in the solar wind.

  19. Δ-resonance contribution to the two-photon exchange amplitude

    NASA Astrophysics Data System (ADS)

    Borisyuk, Dmitry; Kobushkin, Alexander

    2012-11-01

    We consider two-photon exchange (TPE) in the elastic electron-proton scattering and study the contribution arising from the production of Δ(1232) resonance in the intermediate state. We calculate all three TPE amplitudes (generalized form factors), and find that the Δ contribution mainly influences the generalized electric form factor (contrary to the elastic contribution, which affects the magnetic form factor), and the effect grows with Q2. If the corresponding correction is applied to the recent polarization transfer measurements of proton form factors, their results will change markedly. Thus we suggest that TPE corrections due to inelastic intermediate states are important to polarization experiments at high Q2, and should not be neglected.

  20. Local integrand representations of all two-loop amplitudes in planar SYM

    NASA Astrophysics Data System (ADS)

    Bourjaily, Jacob L.; Trnka, Jaroslav

    2015-08-01

    We use generalized unitarity at the integrand-level to directly construct local, manifestly dual-conformally invariant formulae for all two-loop scattering amplitudes in planar, maximally supersymmetric Yang-Mills theory (SYM). This representation separates contributions into manifestly finite and manifestly divergent terms — in a way that renders all infrared-safe observables (including ratio functions) calculable without any need for regulation. These results perfectly match the all-loop BCFW recursion relations, to which we provide a closed-form solution valid through two-loop-order. Finally, we describe and document a Mathematica package which implements these results, available as part of this work's source files on the arXiv.