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We propose a numerical method for resummation of perturbative series, which is based on the stochastic perturbative solution of Schwinger-Dyson equations. The method stochastically estimates the coefficients of perturbative series, and incorporates Borel resummation in a natural way. Similarly to the "worm" algorithm, the method samples open Feynman diagrams, but with an arbitrary number of external legs. As a test of our numerical algorithm, we study the scale dependence of the renormalized coupling constant in a theory of one-component scalar field with quartic interaction. We confirm the triviality of this theory in four and five space-time dimensions, and the instability of the trivial fixed point in three dimensions.

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Off-shell interactions for localized closed-string tachyons in C/Z{sub N} superstring backgrounds are analyzed and a conjecture for the effective height of the tachyon potential is elaborated. At large N, some of the relevant tachyons are nearly massless and their interactions can be deduced from the S-matrix. The cubic interactions between these tachyons and the massless fields are computed in a closed form using orbifold CFT techniques. The cubic interaction between nearly-massless tachyons with different charges is shown to vanish and thus condensation of one tachyon does not source the others. It is shown that to leading order in N, the quartic contact interaction vanishes and the massless exchanges completely account for the four point scattering amplitude. This indicates that it is necessary to go beyond quartic interactions or to include other fields to test the conjecture for the height of the tachyon potential. ...

International Nuclear Information System (INIS)

We investigate the asymptotic properties of the Bianchi type IX cosmological model in the brane-world scenario. The matter content is assumed to be a combination of a perfect fluid and a minimimally coupled scalar field that is restricted to the brane. A detailed qualitative analysis of the Bianchi type IX brane-world containing a scalar field having an exponential potential is undertaken. It is found that the brane-Robertson-Walker solution is a local source for the expanding Bianchi type IX models, and if k"2<2 the ever-expanding Bianchi IX models asymptote to the power-law inflationary solution. The only other local sink is the contracting brane-Robertson Walker solution. An analysis of the Bianchi type IX models with a scalar field with a general potential is discussed, and it is shown that in the case of expanding models, for physical scalar field potentials close to the initial singularity, the ...

CERN Document Server

We perform a systematic analysis of an extension of the Standard Model that includes a complex singlet scalar field and is scale invariant at the tree level. We call such a model the Minimal Scale Invariant extension of the Standard Model (MSISM). The tree-level scale invariance of the model is explicitly broken by quantum corrections, which can trigger electroweak symmetry breaking and potentially provide a mechanism for solving the gauge hierarchy problem. Even though the scale invariant Standard Model is not a realistic scenario, the addition of a complex singlet scalar field may result in a perturbative and phenomenologically viable theory. We present a complete classification of the flat directions which may occur in the classical scalar potential of the MSISM. After calculating the one-loop effective potential of the MSISM, we investigate a number of representative scenarios and determine their ...

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We evaluate various disk level four-point functions involving the massless scalar and tachyon vertex operators in the presence of background B-flux in superstring theory. By studying these amplitudes in specific limits, we find couplings of two scalars with two tachyons, and couplings of four tachyons on the world-volume of non-BPS D-branes of superstring theory. They are fully consistent with the non-commutative tachyonic Dirac-Born-Infeld effective action. They also fix the coefficient of T{sup 4} term in the expansion of the tachyon potential around its maximum.

International Nuclear Information System (INIS)

The mass of the nucleon is studied in a chiral quark-diquark model. Both scalar and axial-vector diquarks are taken into account for the construction of the nucleon state. After the hadronization procedure is used to obtain an effective meson-baryon Lagrangian, the quark-diquark self-energy is calculated to generate the baryon kinetic term as well as determine the mass of the nucleon. It turns out that both the scalar and axial-vector parts of the self-energy are attractive for the mass of the nucleon. We investigate the range of parameters that can reproduce the mass of the nucleon.

International Nuclear Information System (INIS)

We have constructed a Monte Carlo generator (the corresponding FORTRAN code can be obtained from the authors upon request) for lowest-order predictions for the processes #gamma##gamma##->#4f and #gamma##gamma##->#4f#gamma# in the standard model and extensions thereof by an effective #gamma##gamma#H coupling as well as anomalous triple and quartic gauge-boson couplings. Polarization is fully supported, and a realistic photon beam spectrum can be taken into account. For the processes #gamma##gamma##->#4f all helicity amplitudes are explicitly given in a compact form. The presented numerical results contain, in particular, a survey of cross sections for representative final states and their comparison to results obtained with the program package Whizard/Madgraph. The impact of a realistic beam spectrum on cross sections and distributions is illustrated. Moreover, the size of various contributions to cross sections, such as from weak ...

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Straightforward, though formal, arguments are presented to establish that the effective action and potential are gauge covariant at the symmetry-breaking point. We establish that in certain classes of gauge, covariant and axial gauges for Abelian theories and axial gauges for non-Abelian theories, the Nielsen equation for the effective potential can be put into closed form. Scalar electrodynamics is presented in detail in covariant and axial gauges.

Science.gov (United States)

We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the radiative properties of atoms. We calculate the rate of change of the mean atomic energy of the atom for both inertial motion and uniform acceleration. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited inertial atom oscillate near the boundary and this oscillatory behavior may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime. While for accelerated atoms, the transitions from ground states to excited states are found to be possible even in a vacuum due to changes in the vacuum fluctuations induced by both the presence of the boundary and the acceleration of atoms, ...

International Nuclear Information System (INIS)

A path integral evaluation of the Green's function for the hydrogen atom initiated by Duru and Kleinert is studied by recognizing it as a special case of the general treatment of the separable Hamiltonian of Liouville type. The basic dynamical principle involved is identified as Jacobi's principle of least action for given energy which is reparametrization invariant, and thus the appearance of a gauge freedom is naturally understood. The separation of variables in the operator formalism corresponds to a choice of gauge in the path integral, and the Green's function is shown to be gauge independent if the operator ordering is properly taken into account. Unlike the conventional Feynman path integral, which deals with a space-time picture of particle motion, the path integral on the basis of Jacobi's principle sums over orbits in space. We illustrate these properties by evaluating an exact path integral of the Green's function for the hydrogen atom in parabolic coordinates, and thus ...

CERN Document Server

An S-brane solution with two non-composite electric branes and a set of l scalar fields is considered. The intersection rule for branes corresponds to the Lie algebra A_2. The solution contains five factor spaces with the fifth one interpreted as ``our'' 3-dimensional space. It is shown that there exists a time interval where accelerating expansion of ``our'' 3-dimensional space is compatible with small enough value of effective gravitational ``constant'' variation.

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We analyze the potential of the e{sup +}e{sup -} linear colliders, operating in the e{gamma} and {gamma}{gamma} modes, to probe anomalous quartic vector-boson interactions through the multiple production of W's and Z's. We examine all SU(2){sub L}(circle times)U(1){sub Y} chiral operators of order p{sup 4} that lead to new four-gauge-boson interactions but do not alter trilinear vertices. We show that the e{gamma} and {gamma}{gamma} modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10{sup -2} at 90% C.L. Moreover, the information gathered in the e{gamma} mode can be used to reduce the ambiguities of the e{sup +}e{sup -} mode.

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It is the purpose of this paper to prove that a preferred space direction is coupled with each tachyon and, consequently, scalar tachyons, are impossible in principle. Even the notion of a scalar faster-than-light particle cannot be defined in a relativistically invariant way.

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We study an analytical solution to the Einstein's equations in 2 + 1-dimensions. The space-time is dynamical and has a line symmetry. The matter content is a minimally coupled, massless, scalar field. Depending on the value of certain parameters, this solution represents three distinct space-times. The first one is at space-time. Then, we have a big bang model with a negative curvature scalar and a real scalar field. The last case is a big bang model with event horizons where the curvature scalar vanishes and the scalar field changes from real to purely imaginary. (author)

International Nuclear Information System (INIS)

Local-density-functional calculations of the energy bands, equilibrium lattice constant, bulk modulus, and cohesive energy have been performed using a newly developed self-consistent full-potential linearized augmented-plane-wave (LAPW) program. Scalar-relativistic effects are included for the band states, and the core-level states are treated fully relativistically in a central-field approximation. Excellent agreement is obtained with the experimental lattice constant and bulk modulus. Generally good agreement is obtained with the scalar-relativistic pseudopotential results of Bylander and Kleinman. In this context, the impact of various approximations used in including the core states is assessed, and these findings are related to the frozen-core and pseudopotential approximations, especially with regard to the treatment of the somewhat overlapping 5p semicore states and their effect on ground-state ...

CERN Document Server

When quantum gravity is used to discuss the big bang singularity, the most important, though rarely addressed, question is what role genuine quantum degrees of freedom play. Here, complete effective equations are derived for isotropic models with an interacting scalar to all orders in the expansions involved. The resulting coupling terms show that quantum fluctuations do not affect the bounce much. Quantum correlations, however, do have an important role and could even eliminate the bounce. How quantum gravity regularizes the big bang depends crucially on properties of the quantum state.

CERN Document Server

Integration by parts is used to reduce scalar Feynman integrals to master integrals.

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The scalar mixing time scale, a key quantity in many turbulent combustion models, is investigated for reactive scalars in premixed combustion. Direct numerical simulations (DNS) of three-dimensional, turbulent Bunsen flames with reduced methane-air chemistry have been analyzed in the thin reaction zones regime. Previous conclusions from single step chemistry DNS studies are confirmed regarding the role of dilatation and turbulence-chemistry interactions on the progress variable dissipation rate. Compared to the progress variable, the mixing rates of intermediate species is found to be several times greater. The variation of species mixing rates are explained with reference to the structure of one-dimensional premixed laminar flames. According to this analysis, mixing rates are governed by the strong gradients which are imposed by flamelet structures at high Damkoehler numbers. This suggests a modeling approach to estimate the mixing rate of ...

International Nuclear Information System (INIS)

Plasma surface interactions in tokamaks are known to create significant quantities of dust, which settles onto surfaces and accumulates in the vacuum vessel. In ITER, a loss of vacuum accident may result in the release of dust which will be radioactive and/or toxic, and provides increased surface area for chemical reactions or dust explosion. A new method of analysis has been developed for modeling dust resuspension and transport in loss of vacuum accidents. The aerosol dynamic equation is solved via the user defined scalar (UDS) capability in the commercial CFD code Fluent. Fluent solves up to 50 generic transport equations for user defined scalars, and allows customization of terms in these equations through user defined functions (UDF). This allows calculation of diffusion coefficients based on local flow properties, inclusion of body forces such as gravity and thermophoresis in the convection term, and user defined source terms. The code ...

CERN Document Server

A new mathematical framework is formulated to derive the effective equations of motion for the constrained quantum system which possesses an internal clock. In the realm close to classical behavior, the quantum evolution is approximated by a finite system of coupled but ordinary differential equations adhered to the weakly imposed Hamiltonian constraint. For the simplified version of loop quantum cosmology in the Bianchi I model with a free massless scalar filed, the resulting effective equations of motion affirm the bouncing scenario predicted by the previous studies: The big bang singularity is resolved and replaced by the big bounces, which take place up to three times, once in each diagonal direction, whenever the directional density approaches the critical value in the regime of Planckian density. It is also revealed that back-reaction arises from the quantum corrections and modifies the precise value of the ...

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Detectors for a photon-photon collider are envisaged using as guide-lines the physics goals and the interaction point environment. Production of SUSY Higgs scalar and pseudo-scalar is emphasized. Some aspects of the interaction point environment are discussed. ((orig.)).

CERN Document Server

Attention is paid to the production mechanisms of light scalars that reveal their nature. We reveal the chiral shielding of the \\sigma(600) meson. We show that the kaon loop mechanism of the \\phi radiative decays, ratified by experiment, points to the four-quark nature of light scalars. We show also that the light scalars are produced in the two photon collisions via four-quark transitions in contrast to the classic P wave tensor q\\bar q mesons that are produced via two-quark transitions $\\gamma\\gamma\\to q\\bar q$. The history of spontaneous breaking of symmetry in quantum physics is discussed in Appendix.

CERN Document Server

Two quantities play a central role in that part of nonlinear optics which deals with the effects of a finite momentum spread in a particle beam: the orbit position whose derivative with respect to momentum is called 'orbit dispersion' and the betatron wave number whose derivative WRT momentum is the 'chromaticity'. The orbit dispersion varies with the azimuth and is essentially horizontal in a machine with a horizontal symmetry plane; parasitic radial fields induce a vertical component. The chromaticity is a scalar quantity related to the integral of the focusing strength, over one turn of the machine; it is defined for the horizontal and vertical planes. After recalling the general motion equation in the horizontal plane, the orbit dispersion and the chromaticity will be treated. Closed formulae are given for lumped elements and special emphasis is put on dipoles with a high deflection angle. (8 refs).

International Nuclear Information System (INIS)

We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process #gamma##gamma##->#tt at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric extension of the standard model that the H and A contributions can be sizable at future #gamma##gamma# colliders for small values of tan #beta#. The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the Higgs CP-parity is evaluated. (orig.)

International Nuclear Information System (INIS)

Within the framework of the Bianchi type-IX homogeneous space, we set up a system of coupled equations for the cosmic scale factors, scalar field, and radiative energy density. At the tree level, the equations are written in a self-consistent, Hartree-Fock form. For phi"4 theory, the system of nine first-order differential equations is solved numerically for a varying ratio of the energy of anisotropy to the vacuum energy. As the vacuum energy increases, there appears to be less reheating, since the energy of anisotropy is more efficiently converted into isotropic expansion. If the energy of anisotropy is large enough, the inflationary phase is prevented. In this case, a series of cosmological phase transitions will take place each time the square of the effective mass changes its sign.

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In this Brief Report, we analyze a generalized theory of massless scalar QED{sub 2} and show that, unlike the conventional scalar QED{sub 2}, it is free from infrared divergence problems. The model is exactly soluble and may describe, in a (1+1)-dimensional space-time, noninteracting spin-one tachyons. {copyright} {ital 1999} {ital The American Physical Society}

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Casimir operators and the Cartan subalgebra are used to construct the scalar superfields in 10-dimensions. In massless case it is shown that the scalar superfield contains two irreducible pieces, one bosonic and one fermionic. The bosonic one contains the supergravity multiplet. Supersymmetric version of the Cartan subalgebra is used to obtain the explicit expressions of the irreducible superfields. In massive case the scalar superfield contains two bosonic and one fermionic irreducible components. It is shown explicitly that the one of the bosonic pieces reduces to the above mentioned massless bosonic piece containing the supergravity multiplet in the massless limit. Supersymmetric generators corresponding to the root vectors of the Lie algebra are found and used with the Cartan subalgebra to construct the irreducible scalar superfields. Finally this method is also applied to the 4-dimensional case and ...

CERN Document Server

Testing deviation of GR is one of the main goals of the proposed {\\emph{Laser Interferometer Space Antenna}}, a space-based gravitational-wave observatory. For the first time, we consistently compute the generation of gravitational waves from extreme-mass ratio inspirals (stellar compact objects into supermassive black holes) in a well-motivated alternative theory of gravity, that to date remains weakly constrained by double binary pulsar observations. The theory we concentrate on is Chern-Simons (CS) modified gravity, a 4-D, effective theory that is motivated both from string theory and loop-quantum gravity, and which enhances the Einstein-Hilbert action through the addition of a dynamical scalar field and the parity-violating Pontryagin density. We show that although point particles continue to follow geodesics in the modified theory, the background about which they inspiral is a modification to the Kerr metric, which imprints a CS ...

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Let $C$ be a curve of genus two. We denote by $SU_C(3)$ the moduli space of semi-stable vector bundles of rank 3 and trivial determinant over $C$, and by $J^d$ the variety of line bundles of degree $d$ on $C$. In particular, $J^1$ has a canonical theta divisor $\\Theta$. The space $SU_C(3)$ is a double cover of $P^8=|3\\Theta|$ branched along a sextic hypersurface, the Coble sextic. In the dual $\\check{P}^8=|3\\Theta|^*$, where $J^1$ is embedded, there is a unique cubic hypersurface singular along $J^1$, the Coble cubic. We prove that these two hypersurfaces are dual, inducing a non-abelian Torelli result. Moreover, by looking at some special linear sections of these hypersurfaces, we can observe and reinterpret some classical results of algebraic geometry in a context of vector bundles: the duality of the Segre-Igusa quartic with the Segre cubic, the symmetric configuration of 15 lines and 15 points, the Weddle quartic surface and the Kummer ...

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By proposing the four-dimensional, reciprocity transformations the appropriate condition for superluminal electromagnetic Cerenkov radiation is obtained by introducing the hypothesis that tachyons possess vector energy and scalar momentum.

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We use a superspin Hamiltonian defined on an infinite-dimensional Fock space with positive definite scalar product to study localization and delocalization of noninteracting spinless quasiparticles in quasi-one-dimensional quantum wires perturbed by weak quenched disorder. Past works using this approach have considered a single chain. Here, we extend the formalism to treat a quasi-one-dimensional system: a quantum wire with an arbitrary number of channels coupled by random hopping amplitudes. The computations are carried out explicitly for the case of a chiral quasi-one-dimensional wire with broken time-reversal symmetry (chiral-unitary symmetry class). By treating the space direction along the chains as imaginary time, the effects of the disorder are encoded in the time evolution induced by a single site superspin (non-Hermitian) Hamiltonian. We obtain the density of states near the band center of an infinitely long quantum wire. Our results ...

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A first-order one-way wave system has been created based on characteristic analysis of the acoustic wave system and optimization of the dispersion relation. The authors demonstrate that this system is equivalent to a third-order scalar partial-differential equation which, for a homogeneous medium, reduces to a form similar to the 45{degree} paraxial wave equation. This system describes accurately waves propagating in a 2D heterogeneous medium at angles up to 75{degree}. The one-way wave system representing downgoing waves is used for a modified reverse time migration method. As a wavefield extrapolator in migration, the downgoing wave system propagates the reflection events backwards to their reflectors without scattering at the discontinuities in the velocity model. Hence, images with amplitudes proportional to reflectivity can be obtained from this migration technique. They present examples of the application of the new migration method to synthetic seismic data ...

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The Schroedinger equation for nuclear quadruple surface vibrations is linearized with the consequence that a new spin degree of freedom appears in the wave function of the linearized equation. This spin is called collective spin and has a value of 3/2. The linearized Schroedinger equation for quadrupole vibrations is used for the description of certain collective aspects of even-odd {sup 187,189,191}Ir nuclei which have a spin 3/2 in their ground state. As a potential we use the {gamma}-soft collective potential of the neighboring even-even nuclei, which is inserted into the linearized Schroedinger equation via a scalar coupling. This leads to a collective spin-dependent fine structure splitting of the energy levels governed by a collective SO(5) spin-orbit coupling and a correction to the kinetic energy. Further, we consider explicitly spin-dependent potentials which effectively describe the interaction of the valence nucleon with the core of ...

CERN Document Server

Recently the D{\\O} Collaboration reported an observation of like-sign charge asymmetry (CA), which is about $3.2 \\sigma$ deviation from the standard model (SM) prediction. Inspired by the observation we investigate the scalar unparticle effects, under the color charge of $SU(3)_c$ symmetry, in the CP violation in neutral B meson oscillations as well as the dispersive and absorptive parts of $\\bar B_q\\leftrightarrow B_q$ transition, which can be related to the CA directly. In order to illustrate the peculiar properties of unparticle, our analysis is carried out in two scenarios for the right-handed section: (I) $\\lambda_R=\\lambda_L$ and $U_D^R=U_D^L$, where $\\lambda_{L,R}$ and $U_D^{L,R}$ are the couplings and flavor mixing matrix of left- and right-handed section, respectively; (II) $\\lambda_R >> \\lambda_L$ and $U_D^R$ is completely a free parameter. In scenario I we found that the wrong- and like-sign CA cannot be changed ...

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An analysis is given of the evolution of a massive scalar field in a closed mixmaster universe of Bianchi type IX. Although the scalar field violates the strong energy condition, the probability of the model ''bouncing'' at a very early time is infinitesimally small; of the order of the ratio of the minimum to maximum sizes of the universe approx. 10/sup -40/.

Science.gov (United States)

In this work we examine a five-dimensional brane-world model with brane structure driven by a real scalar field. From the deformation of a kink-like defect we find a new class of brane solutions containing internal structures which have implications for the way the background space-time is constructed and the way its curvature behaves. Initially, for spin 0 scalar field, we find a zero mode which can be localized on the deformed brane. However, this result can change by the gravitational interaction with the brane internal structure. Analyzing the massive modes of the scalar field, using two different methods, we find resonance structures similar to those found in the study of gravity localization. The main objective here is to observe the contributions of the deformation procedure to the resonances and to the well known field localization methods.

CERN Document Server

We demonstrate the use of a variational method to determine a quantitative lower bound on the rate of convergence of Markov Chain Monte Carlo (MCMC) algorithms as a function of the target density and proposal density. The bound relies on approximating the second largest eigenvalue in the spectrum of the MCMC operator using a variational principle and the approach is applicable to problems with continuous state spaces. We apply the method to one dimensional examples with Gaussian and quartic target densities, and we contrast the performance of the basic Metropolis-Hastings algorithms with a ``smart'' variant that incorporates gradient information into the trial moves. We find that the variational method agrees quite closely with numerical simulations. We also see that the smart MCMC algorithm often fails to converge geometrically in the tails of the target density except in the simplest case we examine, and even then care must be taken to choose the appropriate ...

CERN Document Server

A major goal in optomechanics is to observe and control quantum behavior in a system consisting of a mechanical resonator coupled to an optical cavity. Work towards this goal has focused on increasing the strength of the coupling between the mechanical and optical degrees of freedom; however, the form of this coupling is crucial in determining which phenomena can be observed in such a system. Here we demonstrate that avoided crossings in the spectrum of an optical cavity containing a flexible dielectric membrane allow us to realize several different forms of the optomechanical coupling. These include cavity detunings that are (to lowest order) linear, quadratic, or quartic in the membrane's displacement, and a cavity finesse that is linear in (or independent of) the membrane's displacement. All these couplings are realized in a single device with extremely low optical loss and can be tuned over a wide range in situ; in particular, we find that the quadratic ...

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We calculate the cross sections for the single production of doubly charged dileptons, both scalar and vector, at [ital e][sup +][ital e][sup [minus

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In this paper we discuss the supersymmetric tachyon and its applications. Both unitary and non-unitary representations for the superalgebra are examined. If we abandon the standpoint that any elementary particle in relativistic quantum theory must be described by unitary irreducible representations of the Poincare algebra or the superalgebra, then we can construct the supersymmetric invariant action for supersymmetric tachyons. The scalar neutrino's mass is lighter than the photino's mass if the neutrino is the tachyon, and the photon is a massless particle in the simplest supersymmetry-breaking model. There is a possibility that the cold dark matter consists of scalar neutrinos.

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Recent work on [ital N]=2 supersymmetric Bianchi type IX cosmologies coupled to a scalar field is extended to a general treatment of homogeneous quantum cosmologies with explicitly solvable momentum constraints, i.e., Bianchi types I, II, VII, VIII in addition to the Bianchi type IX, and special cases, namely, the Freidmann universes, the Kantowski-Sachs space, and Taub-NUT space. In addition to the earlier explicit solution of the Wheeler-DeWitt equation for Bianchi type IX, describing a virtual wormhole fluctuation, an additional explicit solution is given and identified with the no-boundary state.''

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An electroweak singlet scalar can couple to pairs of vector bosons through loop-induced dimension five operators. Compared to a Standard Model Higgs boson, the singlet decay widths in the diphotons and Z gamma channels are generically enhanced, while decays into massive final states like WW and ZZ are kinematically disfavored. The overall event rates into gamma gamma and Z gamma can exceed the Standard Model expectations by orders of magnitude. Such a singlet may appear as a resonant signal in the gamma gamma and Z gamma channels, even with a mass above the WW kinematic threshold.

International Nuclear Information System (INIS)

We show using covariant techniques that the Einstein static universe containing a perfect fluid is always neutrally stable against small inhomogeneous vector and tensor perturbations and neutrally stable against adiabatic scalar density inhomogeneities so long as c"2_s > 1/5, and unstable otherwise. We also show that the stability is not significantly changed by the presence of a self-interacting scalar field source, but we find that spatially homogeneous Bianchi type IX modes destabilize an Einstein static universe. The implications of these results for the initial state of the universe and its pre-inflationary evolution are also discussed. (letter to the editor)

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The curves that describe the M-theoretic extension of type IIA string configurations with non-supersymmetric field theories on their surface exhibit a duality map. The map suggests a continued link between an SU(N) gauge theory with F flavors and an SU(F{minus}N) gauge theory with F flavors (the duality of supersymmetric QCD) even when the gaugino mass is taken to infinity. Within the context of the field theory such a duality only continues to make sense if the scalar fields remain light. We discuss the difficulties of decoupling the scalars within this framework. thinsp {copyright} {ital 1998} {ital The American Physical Society}

CERN Document Server

In the GmSUGRA scenario with the high-dimensional operators containing the GUT Higgs fields, we systematically studied the supersymmetry breaking scalar masses, SM fermion Yukawa coupling terms, and trilinear soft terms in the E_6 SUSY GUT model where the gauge symmetry is broken down to the SO(10)\\tm U(1) gauge symmetry, SU(3)_C\\times SU(3)_L \\times SU(3)_R gauge symmetry, SU(6)\\times SU(2)_a (a={\\rm L,R,X}) gauge symmetry, flipped SU(5) gauge symmetry etc. In addition, we considered the scalar and gaugino mass relations, which can be preserved from the GUT scale to the electroweak scale under one-loop RGE running, in the SU(3)_C\\times SU(3)_L \\times SU(3)_R model arising from the E_6 model. With such relations, we may distinguish the mSUGRA and GmSUGRA scenarios if we can measure the supersymmetric particle spectrum at the LHC and ILC.

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We introduce an ad-hoc electrodynamics with advanced and retarded Lienard-Wiechert interactions plus the dissipative Lorentz-Dirac self-interaction force. We study the covariant dynamical system of the electromagnetic two-body problem, i.e., the hydrogen atom. We perform the linear stability analysis of circular orbits for oscillations perpendicular to the orbital plane. In particular we study the normal modes of the linearized dynamics that have an arbitrarily large imaginary eigenvalue. These large eigenvalues are fast frequencies that introduce a fast (stiff) timescale into the dynamics. As an application, we study the phenomenon of resonant dissipation, i.e., a motion where both particles recoil together in a drifting circular orbit (a bound state), while the atom dissipates center-of-mass energy only. This balancing of the stiff dynamics is established by the existence of a quartic resonant constant that locks the dynamics to the neighborhood of the recoiling ...

International Nuclear Information System (INIS)

The O(#alpha#) electroweak radiative corrections to #gamma##gamma##->#WW#->#4f within the electroweak standard model are calculated in double-pole approximation (DPA). Virtual corrections are treated in DPA, leading to a classification into factorizable and non-factorizable contributions, and real-photonic corrections are based on complete lowest-order matrix elements for #gamma##gamma##->#4f+#gamma#. Soft and collinear singularities appearing in the virtual and real corrections are combined alternatively in two different ways, namely by using the dipole subtraction method or by applying phase-space slicing. The radiative corrections are implemented in a Monte Carlo generator called Coffer #gamma##gamma# - the computer code can be obtained from the authors upon request - which optionally includes anomalous triple and quartic gauge-boson couplings in addition and performs a convolution over realistic spectra of the photon beams. A detailed survey of ...

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Using the operator approach we reexamine the two-dimensional model describing a massive Fermi field interacting via derivative couplings with two massless Bose fields, one scalar and the other pseudoscalar. Performing a canonical transformation on the Bose field algebra, the Fermi field operator is written in terms of the Mandelstam soliton operator and the derivative-coupling (DC) model is mapped into the massive Thirring model with two vector-current-scalar-derivative interactions (Schroer-Thirring model). The DC model with massless fermions can be mapped into the massless Rothe-Stamatescu model with a Thirring interaction (massless Rothe-Stamatescu-Thirring model). Within the present approach the weak equivalence between the fermionic sector of the DC model and the massive Thirring model is exhibited compactly.

CERN Document Server

The full theory and the semiclassical description of loop quantum cosmology (LQC) have been studied in the Friedmann-Robertson-Walker and Bianchi I models. As an extension to include both anisotropy and intrinsic curvature, this paper investigates the cosmological model of Kantowski-Sachs spacetime with a free massless scalar field at the level of phenomenological dynamics with the LQC discreteness corrections. The LQC corrections are implemented in two different improved quantization schemes. In both schemes, the big bang and big crunch singularities of the classical solution are resolved and replaced by the big bounces when the area or volume scale factor approaches the critical values in the Planck regime measured by the reference of the scalar field momentum. Symmetries of scaling are also noted and suggest that the fundamental spatial scale (area gap) may give rise to a temporal scale. The bouncing scenarios are in an analogous fashion of ...

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Versions of parameterized pseudo-Newtonian gravity theories specially designed for cosmology have been introduced in recent cosmology literature. The modifications demand a zero-pressure fluid in the context of versions of modified Poisson-like equation with two different gravitational potentials. We consider such modifications in the context of relativistic gravity theories where the action is a general algebraic function of the scalar curvature, the scalar field, and the kinetic term of the field. In general it is not possible to isolate the zero-pressure fluid component simultaneously demanding a modification in the Poisson-like equation. Only in the small-scale limit we can realize some special forms of the attempted modifications. We address some loopholes in the possibility of showing non-Einstein gravity nature based on pseudo-Newtonian modifications in the cosmological context. We point out that future observations of gravitational weak ...

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Algorithms for generating new exact solutions of the Einstein-Klein-Gordon field equations, which describe inhomogeneous universes with S/sup 3/ topology of spatial sections, are developed. The known exact vacuum and still-fluid solutions with S/sup 3/ topology are used as an input. The methods developed are further applied to derive inhomogeneous generalizations of Bianchi type IX solutions and inhomogeneous S/sup 3/ Gowdy models with gravitational and scalar waves. It is shown that the new solutions, which are generalizations of the Bianchi type IX models, permit identification of the scalar field with the velocity potential of the stiff irrotational fluid. The latter result is further used to study the growth rate of density perturbations of the isotropic and anisotropic Bianchi type IX universes in a fully nonlinear relativistic regime. The role of anisotropy on the rate of growth of density perturbations is studied in detail.

CERN Document Server

No Kerr-like exact solution has yet been found in Chern-Simons modified gravity. Intrigued by this absence, we study stationary and axisymmetric metrics that could represent the exterior field of spinning black holes. For the standard choice of the background scalar, the modified field equations decouple into the Einstein equations and additional constraints. These constraints eliminate essentially all solutions except for Schwarzschild. For non-canonical choices of the background scalar, we find several exact solutions of the modified field equations, including mathematical black holes and pp-waves. We show that the ultrarelativistically boosted Kerr metric can satisfy the modified field equations, and we argue that physical spinning black holes may exist in Chern-Simons modified gravity only if the metric breaks stationarity, axisymmetry or energy-momentum conservation.

CERN Document Server

We consider a minimal model of GUT scalar dark matter (DM) stabilized by the discrete gauge matter parity $P_{X}$ that arises from breaking of $SO(10)$. The dark sector comprises the complex singlet $S$ and the inert doublet $H_{2}$. GUT scale parameters are evaluated to the electroweak scale via Renormalization Group Equations (RGEs). Experimental and theoretical constraints limit the DM mass to the 80 GeV to 2 TeV range. The EW symmetry breaking is radiative and can occur via RGE running and 1-loop matching corrections from integrating out DM. Because the next-to-lightest scalar is almost degenerate with DM, it gives a background free displaced decay vertex at the LHC.

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This paper gives a Coulomb gas representation for level kN = 1 supersymmetric SU(2) Kac-Moody algebra in terms of three free scalar superfields. It is clarified how this representation reduces to a Coulomb gas representation for the corresponding bosonic SU(2) Kac-Moody algebra and the free fermionic algebra. The primary superfields and the correlation functions, which satisfy the supersymmetric Knizhnik-Zamolodchikov equation, are also discussed.

International Nuclear Information System (INIS)

The Klein-Gordan equation in the background of the Schwarzschild curved space-time is considered and the scattering of radial tardyons and tachyons from a black hole is studied. It is shown that black holes of mass below 7x10"1"4g may contain bound states of tardyons of pion mass which will be unstable on account of the presence of an attractive r"-"4 term. (author).

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The success of the Randall-Sundrum scenario relies on stabilization of the modulus field or the radion, which is the scalar field about the background geometry. The stabilization mechanism proposed by Goldberger and Wise has the consequence that this radion is lighter than the graviton Kaluza-Klein states so that the first particle to be discovered is the radion. In this work, we study in detail the decay, production, and detection of the radion at hadronic, e{sup +}e{sup -}, and {gamma}{gamma} colliders.

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The possibility of having inflation in a renormalizable cosmological model is investigated. The cosmic no-hair conjecture is proved to hold for all Bianchi types except Bianchi type IX. By the use of a conformal transformation on the metric we show that these models are equivalent to the ones described by the Einstein-Hilbert action for gravity minimally coupled to a set of scalar fields with inflationary potentials. Henceforth, we prove that inflationary solutions behave as attractors in solution space, making it a natural event in the evolution of such models.

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Nordstroem's first theory of gravitation, which is a Lorentz covariant scalar theory, is discussed, and the cosmological solution to the field equation is derived. It is shown that there are two physically equivalent representations of the theory that differ in the system of units with which measurements are made. The cosmological solution is found to be an infinite, Euclidean universe with a big bang and a big crunch.

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A formula for calculating the Dirac S-matrix for central Lorentz scalar and vector potentials is derived by use of a new amplitude-phase method. The derivation also makes use of certain invariants of the reduced 2-spinor radial Dirac equations.

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This paper proposes a novel control strategy for tracking peak power in a wind or wave energy system using a squirrel cage induction generator. It eliminates wind speed measurement or estimation and uses a simple scalar technique by exploiting the cubic nature of the power curve. The method works even when air velocity is varying dynamically. (author)

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In this paper, the wavefunction of the universe with a tunneling boundary condition is considered in the context of the Brans-Dicke-type scalar-tensor theory with matter. The matter may be interpreted as a D-particle (or D0-brane) in string theory when the Brans-Dicke parameter {omega} is -1. We study two simple examples. The first example, the {gamma}=0 (matter) case, has a scale factor duality even if the low energy string action is coupled to matter. The universe undergoes quantum transition from super-inflationary (pre-big-bang) to deflationary (post-big-bang) phase. We calculate the transition rate by solving the Wheeler-DeWitt equation and find that it is non-vanishing. The two phases are disconnected classically. The second example is the {gamma}=1/3(radiation) case. With the help of earlier work this matter can be identified with a D0-brane in string theory. In this case, due to the absence of the scale factor duality and the complicated relations between ...

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The authors report on a search for pair production of first-generation scalar leptoquarks (LQ) in p{bar p} collisions at {radical}s = 1.96 TeV using an integrated luminosity of 252 pb{sup -1} collected at the Fermilab Tevatron collider by the D0 detector. They observe no evidence for LQ production in the topologies arising from LQ{ovr LQ} {yields} eqeq and LQ{ovr LQ} {yields} eqvq, and derive 95% C.L. lower limits on the LQ mass as a function of {beta}, where {beta} is the branching fraction for LQ {yields} eq. The limits are 241 and 218 GeV/c{sup 2} for {beta} = 1 and 0.5, respectively. These results are combined with those obtained by D0 at {radical}s = 1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c{sup 2}.

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We study the a{sub 0} and {sigma} mesons with the overlap fermion in the chiral regime with the pion mass as low as 182 MeV in the quenched approximation. After the {eta} N ghost states are separated, we find that the a{sub 0} mass with q{bar q} interpolation field to be almost independent of the quark mass in the region below the strange quark mass. The chirally extrapolated results are consistent with a{sub 0}(1450) being the u{bar d} meson and K{sub 0}*(1430) being the u {bar s} meson. We also calculate the scalar mesonium with a tetraquark interpolation field. In addition to the two pion scattering states, we found a state at {approx} 550 MeV. Through the study of volume dependence, we confirm that this state is a one-particle state, in contrast to the two-pion scattering states. This suggests that the observed state is a tetraquark mesonium which is quite possibly the {sigma}(600) meson.

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We find instanton/cosmological solutions with biaxial Bianchi-IX symmetry, involving nontrivial spatial dependence of the CP{sup 1}-CP{sup 2}-sigma-models coupled to gravity. Such manifolds arise in N = 1, d 4 supergravity with supermatter actions and hence the solutions can be embedded in supergravity. There is a natural way in which the standard coordinates of these manifolds can be mapped into the four-dimensional physical space. Due to its special symmetry, we start with CP{sup 2} with its corresponding scalar ansatz; this further requires the spacetime to be SU(2) x U(1)-invariant. The problem then reduces to a set of ordinary differential equations whose analytical properties and solutions are discussed. Among the solutions there is a surprising, special family of exact solutions which owe their existence to the nontrivial topology of CP{sup 2} and are in 1-1 correspondence with matter-free Bianchi-IX metrics. These solutions can also be found by coupling ...

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We develop a general framework for the formulation of the action principle and the noether theorem for classical noncommutative field theories. We give a concrete example of an algebra that fits into this framework. It describes a scalar field theory on noncommutative minkowski space. We develop a notion of locality for this algebra and investigate the locality properties of localised interaction terms. This leads us to the definition of local functionals on the field algebra. We propose a scheme for the quantisation of these functionals. (orig.) [German] Wir entwickeln eine allgemeinen rahmen, der es erlaubt, das wirkungsprinzip und das noether-theorem fuer klassische nichtkommutative feldtheorien zu formulieren. Als ein konkretes beispiel betrachten wir eine algebra, die sich in diesem rahmen einfuegt, und die eine skalare feldtheorie auf dem nichtkommutativen minkowski-raum beschreibt. Fuer diese algebra wird ein lokalitaetsbegriff entwickelt und untersucht, ...

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A generalized integral representation involving two types of charges is explored to construct correlation functions on the plane for c = 1 - 6/(m(m + 1)) < 1 discrete unitary Virasoro series. The various local operator product algebras emerging contain integer, or half-integer, spin fields along with scalar fields. The examples also include a generalization for arbitrary m of the Z/sub 2/sup -// statistics of the Ising model order-disorder fields.

International Nuclear Information System (INIS)

Developed is a simple method alloing one to determine the k-loop coefficient of #beta# function in gauge theories provided the operator expansion is constructed in (k-1) loop for certain two-point functions. The calculation of the two-loop coefficient of the Gell-Mann-Low function becomes trival - it reduces to a few algebraic operations with expressions which are already known. As an example spinor, scalar and supersymmetric electrodynamics are considered. Although the corresponding results for #beta#"("2") are known in the literature, both the method of the calculations and some points referring to the construction of the operator expansion are novel.

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Bhabha scattering is one of the processes at the ILC where high precision data will be expected. The complete NNLO corrections include radiative loop corrections, with contributions from Feynman diagrams with five external legs. We take these diagrams as an example and discuss several features of the evaluation of pentagon diagrams. The tensor functions are usually reduced to simpler scalar functions. Here we study, as an alternative, the application of Mellin-Barnes representations to 5-point functions. There is no evidence for an improved numerical evaluation of their finite, physical parts. However, the approach gives interesting insights into the treatment of the IR- singularities. (orig.)

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Starting with two supersymmetric dual theories, we imagine adding a chiral perturbation that breaks supersymmetry dynamically. At low energy we then get two theories with soft supersymmetry-breaking terms that are generated dynamically. With a canonical K{umlt a}hler potential, some of the scalars of the ``magnetic`` theory typically have negative mass-squared, and the vector-like symmetry is broken. Since for large supersymmetry breaking the ``electric`` theory becomes ordinary QCD, the two theories are then incompatible. For small supersymmetry breaking, if duality still holds, the magnetic theory analysis implies specific patterns of chiral symmetry breaking in supersymmetric QCD with small soft masses.

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This study is targeted to the NLO corrections of multileg processes, very important for the LHC. Starting from the construction of Feynman diagrams, the analytical reduction of general one-loop integrals to scalar master ones, the calculation of color structures, manipulation of spinor lines and other amplitude constituents and finally phase space point selection are obtained by use of a program producing Fortran code for numerical calculation of one-loop corrections for processes like gg{yields}t anti tgg. (orig.)

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This report describes the results obtained during Stage 13 of a long-term research and development program concerning the development of diagnostics and monitoring methods for nuclear reactors. A brief proposal for the continuation of this program in Stage 14 is also given at the end of the report. The program executed in Stage 13 consists of three parts and the work performed in each part is summarized below. 1. Study of criticality, neutron kinetics and neutron noise in molten salt reactors (MSR). Although the original goal of the investigations of the MSR in Stage 13 was to calculate the neutron noise induced by the fluctuations of the fuel temperature, the study, solution and interpretation of the static problem, as well as to define an approximate version of the point kinetic approximation was necessary to perform. As it turned out, these tasks in themselves were more involved, and also very edifying, to solve. Hence, in this report, we confine the study of the reactor physics of ...

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The present thesis presents two different aspects of my work in the L3 experiment, which are on one side the search for supersymmetric particles, the scalar leptons, in two different topologies 'electron + X + E' and '2 leptons + 2 photons + E', each of them being related to two theoretical SUSY models, m-SUGRA and GMSB. On the other side my work has been completed by the study of the BGO crystal electromagnetic calorimeter of L3, and the calibration of the electromagnetic calorimeter EGAP. After the essential motivations being reviewed, the production and disintegration modes are detailed concerning the scalar lepton sector at LEP. Then one presents the analysis techniques which I used to perform my selection, and also the results obtained from the data collected by L3 for center of mass energies between {radical} S =183 GeV and 202 GeV. The selection criteria that allow to isolate the events I looked for, ...

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The stability properties of a class of spacetimes with quasiregular singularities is discussed. Quasiregular singularities are the end points of incomplete, inextendible geodesics at which the Riemann tensor and its derivatives remain at least bounded in all parallel-propagated orthonormal (PPON) frames; observers approaching such a singularity would find that their world lines come to an end in a finite proper time. The Taub-NUT (Newman-Unti-Tamburino)-type cosmologies investigated are R/sup 1/ x T/sup 3/ and R/sup 3/ x S/sup 1/ flat Kasner spacetimes, the two-parameter family of spatially homogeneous but anisotropic Bianchi type-IX Taub-NUT spacetimes, and an infinite-dimensional family of Einstein-Rosen-Gowdy spacetimes studied by Moncrief. The behavior of matter near the quasiregular singularity in each of these spacetimes is explored through an examination of the behavior of the stress-energy tensors and scalars for conformally coupled and minimally coupled, ...

CERN Document Server

We have combined perturbative unitarity and renormalisation group equation arguments in order to find a dynamical way to constrain the space of the gauge couplings ($g'_1$, \\widetilde{g}$) of the so-called "Minimal $Z'$ Models". We have analysed the role of the gauge couplings evolution in the perturbative stability of the two-to-two body scattering amplitudes of the vector and scalar sectors of these models and we have shown that perturbative unitarity imposes an upper bound that is generally stronger than the triviality constraint. We have also demonstrated how this method quantitatively refines the usual triviality bound in the case of benchmark scenarios such as the $U(1)_\\chi$, the $U(1)_R$ or the "pure" $U(1)_{B-L}$ extension of the Standard Model. Finally, a description of the underlying model structure in Feynman gauge is provided.

CERN Document Server

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second order moments of the system are analyzed. These moments back-react on the trajectories of the expectation values of the state and hence alter the energy density at the bounce. This analysis is performed for isotropic loop quantum cosmology coupled to a scalar field with a small but non-zero constant potential, hence in a regime in which the kinetic energy of matter dominates. Analytic restrictions on the existence of dynamical coherent states and the meaning of semi-classicality within these systems are discussed. A numerical investigation of the trajectories of states that remain semi-classical across the bounce demonstrates that, at least for such states, the bounce persists and that its properties are similar to the standard case, in which the moments of the states are ...

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In this paper we present an approach to study the radiative decay modes of the J/{psi} into a photon and one of the tensor mesons f{sub 2}(1270), f' {sub 2}(1525), as well as the scalar ones f{sub 0}(1370) and f{sub 0}(1710). Especially, we compare predictions that emerge from a scheme where the states appear dynamically in the solution of vector meson-vector meson scattering amplitudes to those from a (admittedly naive) quark model. We provide evidence that it might be possible to distinguish amongst the two scenarios, once improved data are available. (orig.)

International Nuclear Information System (INIS)

We calculate the cross sections for the single production of doubly charged dileptons, both scalar and vector, at e"+e"-, e#gamma#, and #gamma##gamma# colliders at #sq root#s =500 GeV and 1 TeV. The e#gamma# mode is by far the most promising---dileptons whose coupling is as weak as #approx#10"-"4#alpha#_e_m can be observed, for masses virtually up to the kinematic limit. Dileptons of mass up to #sq root#s can also be seen in e"+e"- and #gamma##gamma# colliders, for couplings of order #alpha#_e_m. In all three colliders, most of the cross section comes from events in which the only particles detected are e"-e"- (or #mu#"-#mu#"- or #tau#"-#tau#"-), the decay products of the dilepton, yielding an unmistakable experimental signature.

CERN Document Server

We study perturbations of a Schwarzschild black hole in Chern-Simons modified gravity. We begin by showing that Birkhoff's theorem holds for a wide family of Chern-Simons coupling functions, a scalar field present in the theory that controls the strength of the Chern-Simons correction to the Einstein-Hilbert action. After decomposing the perturbations in spherical harmonics, we study the linearized modified field equations and find that axial and polar modes are coupled, in contrast to general relativity. The divergence of the modified equations leads to the Pontryagin constraint, which forces the vanishing of the Cunningham-Price-Moncrief master function associated with axial modes. We analyze the structure of these equations and find that the appearance of the Pontryagin constraint yields an overconstrained system that does not allow for generic black hole oscillations. We illustrate this situation by studying the case characterized by a canonical choice of the ...

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It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at DESY HERA, high precision low energy {nu}N scattering, Bhabha and Mo/ller scattering at linear colliders and both fermion and gluon pair production at {gamma}{gamma} colliders. {copyright} {ital 1999} {ital The American Physical Society}

International Nuclear Information System (INIS)

It has been recently suggested by Arkani-Hamed, Dimopoulos and Dvali that gravity may become strong at energies not far above the electroweak scale and thus remove the hierarchy problem. Such a scenario can be tested at both present and future accelerators since towers of Kaluza-Klein gravitons and associated scalar fields now play an important phenomenological role. In this paper we examine several processes for their sensitivity to a low scale for quantum gravity including deep inelastic ep scattering at HERA, high precision low energy #nu#N scattering, Bhabha and Moller scattering at linear colliders and fermion pair production at #gamma##gamma# colliders

International Nuclear Information System (INIS)

O.K. Andersen has recently introduced a linear augmented plane wave method (LAPW) for the calculation of electronic structure that was shown to be computationally fast. A more general formulation of an LAPW method is presented here. It makes use of a freely disposable number of eigenfunctions of the radial Schroedinger equation. These eigenfunctions can be selected in a self-consistent way. The present formulation also results in a computationally fast method. It is shown that Andersen's LAPW is obtained in a special limit from the present formulation. Self-consistent test calculations for copper show the present method to be remarkably accurate. As an application, scalar-relativistic self-consistent calculations are presented for the band structure of FCC lanthanum. (author).

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This is a set of lecture notes given by the author at the Universities of Gottingen and Wroclaw. The text presents the axiomatic approach to field theory and studies in depth the concepts of symmetry and supersymmetry and their associated generators, currents and charges. It is intended as a one- semester course for graduate students in the field of mathematical physics and high energy physics. Contents: Introduction; Example of a Classical and Quantum Scalar Free Field Theory; Scene and Subject of the Drama. Axiom 1 and 2; Subject of the Drama; Principle of Relativity. Causality. Axiom 3, 4 and 5; Irreducibility of the Field Algebra and Scattering Theory. Axiom 6. Axiom O; Preliminaries about Physical Symmetries; Currents and Charges; Global Symmetries and Supersymmetries of the S - Matrix; Representations of the Super-Lie Algebra; The Case of Massless Particles; Fermionic Charges; Concluding Remarks.

International Nuclear Information System (INIS)

In this paper, we show how to improve and extend the integration by fractional expansion technique (IBFE) by applying it to certain families of scalar massive Feynman diagrams. The strategy is based on combining this method together with the integration by parts technique. In particular, we want to calculate certain Feynman diagrams which have a triangle loop as a subgraph. The main idea is to use the integration by parts technique in this subgraph in order to simplify the topology of the original diagram in which it is immersed, using then, in a second step, the IBFE technique. The result we have obtained, after the application of both techniques, represents a simplification in the complexity of the solution, compared with having used only the IBFE technique.

CERN Document Server

In order to understand the parameters of the standard model of electroweak and strong interactions (coupling constants, masses, mixing angles) one needs to embed the standard model into some larger theory that accounts for the observed values. This means some additional sector is needed that fixes and stabilizes the values of the fundamental constants of nature. In these lecture notes we describe in nontechnical terms how such a sector can be constructed. Our additional sector is based on rapidly fluctuating scalar fields that, although completely deterministic, evolve in the strongest possible chaotic way and exhibit complex behaviour. These chaotic fields generate potentials for moduli fields, which ultimately fix the fundamental parameters. The chaotic dynamics can be physically interpreted in terms of vacuum fluctuations. These vacuum fluctuations are different from those of QED or QCD but coupled with the same moduli fields as QED and QCD are. The vacuum ...

CERN Document Server

We propose central exclusive production of a charged Higgs boson in association with a W boson as a possible signature of certain types of extended Higgs sectors. We calculate the cross section and find that the rate at the LHC could be large enough to allow observation in some models with two Higgs doublets, where the charged Higgs and at least one of the neutral scalars can be light enough. We use the two-Higgs doublet model as a prototype and consider two distinct regions of parameter space, but we also briefly discuss the prospects for the next-to-minimal supersymmetric standard model, where the charged Higgs may very well be quite light.

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A three-dimensional (3-D) prestack reverse-time migration algorithm for common-source P-wave data from anisotropic media is developed and illustrated by application to synthetic data. Both extrapolation of the data and computation of the excitation-time imaging condition are implemented using a second-order finite-difference solution of the 3-D anisotropic scalar-wave equation. Poorly focused, distorted images are obtained if data from anisotropic media are migrated using isotropic extrapolation; well focused, clear images are obtained using anisotropic extrapolation. A priori estimation of the 3-D anisotropic velocity distribution is required. Zones of anomalous, directionally dependent reflectivity associated with anisotropic fracture zones are detectable in both the 3-D common-source data and the corresponding migrated images.

International Nuclear Information System (INIS)

This thesis presents a theoretical analysis of the properties of the Higgs bosons in the standard model (SM) and the minimal supersymmetric extension (MSSM), which can be investigated at the LHC and e"+e"- linear colliders. The final goal is the reconstruction of the Higgs potential and thus the verification of the Higgs mechanism. MSSM Higgs boson production processes at future #gamma##gamma# colliders are calculated in several decay channels. Heavy scalar and pseudoscalar Higgs bosons can be discovered in the bb final state in the investigated mass range 200 to 800 GeV for moderate and large values of tan#beta#. The #tau#"+#tau#"- channel provides a heavy Higgs boson discovery potential for large values of tan#beta#. Several mechanisms that can be exploited at e"+e"- linear colliders for the measurement of the lifetime of a SM Higgs boson in the intermediate mass range are analysed. In the WW mode, the lifetime of Higgs scalars with masses ...

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Mass shift of accelerated charges-sources of a massive vector and massive scalar fields, are considered in an approximation which is classical with respect to the charge motion but quantum with respect to their interaction with their proper field. For uniformly accelerated charges the mass shifts are expressed in terms of cylindrical functions of the quantum parameter ..mu..c/sup 3//h/2..pi..w/sub 0/ which is the ratio of the mass ..mu.. of the proper field quanta to the charge acceleration w/sub 0/. For finite positive values of the parameter both the imaginary and real parts of the shifts are nonvanishing and negative. For ..mu -->..0 the real part of the mass shift of a vector charge tends to the classical value -..cap alpha..h/2..pi..w/sub 0//2c/sup 3/ obtained earlier, thereas that of the scalar charge tends to zero. These and other properties of the shifts as functions of ..mu.. are studied by taking into account the locality of ...

CERN Document Server

The structure of Poisson polynomial algebras of the type obtained as semiclassical limits of quantized coordinate rings is investigated. Sufficient conditions for a rational Poisson action of a torus on such an algebra to leave only finitely many Poisson prime ideals invariant are obtained. Combined with previous work of the first-named author, this establishes the Poisson Dixmier-Moeglin equivalence for large classes of Poisson polynomial rings, such as semiclassical limits of quantum matrices, quantum symplectic and euclidean spaces, quantum symmetric and antisymmetric matrices. For a similarly large class of Poisson polynomial rings, it is proved that the quotient field of the algebra (respectively, of any Poisson prime factor ring) is a rational function field $F(x_1,...,x_n)$ over the base field (respectively, over an extension field of the base field) with $\\{x_i,x_j\\}= \\lambda_{ij} x_ix_j$ for suitable scalars $\\lambda_{ij}$, thus establishing a ...

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We study free and self-interacting scalar quantum field theories in a flat Robertson-Walker metric in the functional Schroedinger picture. We discuss Schroedinger picture quantization, relating it to conventional Heisenberg picture quantization. For the interacting theory, we introduce the time-dependent Gaussian approximation to study time evolution of pure and mixed states and we establish renormalizability of the approximation. We also study the question of computing a finite, renormalized energy-momentum tensor for both the free and the interacting theory in the Gaussian appproximation. Using the adiabatic expansion, we show that the entire subtration necessary to make the the energy-momentum tensor finite in the free theory can be written in terms of covariantly conserved tensors. We further show that the same subtraction is sufficient to make the energy-momentum tensor finite in the Gaussian approximation for the interacting theory provided that the mass and ...

CERN Document Server

We study an exactly solvable model where an uniformly accelerated detector is linearly coupled to a massless scalar field initially in the Minkowski vacuum. Using the exact correlation functions we show that as soon as the coupling is switched on one can see information flowing from the detector to the field and propagating with the radiation into null infinity. By expressing the reduced density matrix of the detector in terms of the two-point functions, we calculate the purity function in the detector and study the evolution of quantum entanglement between the detector and the field. Only in the ultraweak coupling regime could some degree of recoherence in the detector appear at late times, but never in full restoration, as an earlier work seems to suggest. We explicitly show that under the most general conditions the detector never recovers its quantum coherence and the entanglement between the detector and the field remains large at late times. To the extent ...

CERN Document Server

We investigate the signatures of antimatter in cosmic rays that would result from annihilations of the scalar dark matter candidate of the Inert Doublet Model. We consider three benchmark candidates, all consistent with the WMAP cosmic abundance and existing direct detection experiments, and confront the predictions of the model with the recent PAMELA, ATIC and HESS data. For a light IDM WIMP candidate, M_{DM} = 10 GeV, we argue that the positron and antiproton fluxes are large, but consistent with expected backgrounds, unless there is an enhancement in the local density of dark matter. For an IDM WIMP candidate with M_{DM} = 70 GeV, the contribution is lower than the expected backgrounds unless there is a large boost factor. However, the candidate is enable to explain the excesses observed by the recent experiments. Finally, for an IDM WIMP candidate with M_{DM}=10 TeV, it is possible to fit the PAMELA excess, while satisfying the anti-protons data, but, ...

CERN Document Server

We calculate the light `glueball' mass spectrum in N_f=2 lattice QCD using a fermion action that is non--perturbatively O(a) improved. We work at lattice spacings a~0.1 fm and with quark masses that range down to about half the strange quark mass. We find the statistical errors to be moderate and under control on relatively small ensembles. We compare our mass spectrum to that of quenched QCD at the same value of a. Whilst the tensor mass is the same (within errors), the scalar mass is significantly lighter in the dynamical lattice theory, by a factor of ~0.84 +/- 0.03. We discuss what the observed m_q dependence of this suppression tells us about the dynamics of glueballs in QCD. We also calculate the masses of flux tubes that wind around the spatial torus, and extract the string tension from these. As we decrease the quark mass we see a small but growing vacuum expectation value for the corresponding flux tube operators. This provides clear evidence for `string ...

Science.gov (United States)

We report a new measurement of the exclusive electroproduction reaction {gamma}*p{yields}{pi}{sup 0}p to explore the evolution from soft nonperturbative physics to hard processes via the Q{sup 2} dependence of the magnetic (M{sub 1+}), electric (E{sub 1+}), and scalar (S{sub 1+}) multipoles in the N{yields}{delta} transition. 9000 differential cross section data points cover W from threshold to 1.4 GeV/c{sup 2}, 4{pi} center-of-mass solid angle, and Q{sup 2} from 3 to 6 GeV{sup 2}/c{sup 2}, the highest yet achieved. It is found that the magnetic form factor G{sub M}* decreases with Q{sup 2} more steeply than the proton magnetic form factor, the ratio E{sub 1+}/M{sub 1+} is small and negative, indicating strong helicity nonconservation, and the ratio S{sub 1+}/M{sub 1+} is negative, while its magnitude increases with Q{sup 2}.

CERN Document Server

A search for the doubly charged Higgs boson, a member of $SU(2)_L$ scalar triplet $\\Phi$ participating in the seesaw mechanism of type II, in $pp$ collisions at $\\sqrt{s}=7$~TeV is presented. The data correspond to an integrated luminosity of 36 $\\text{pb}^{-1}$ collected by the CMS experiment at the LHC. The inclusive search is performed in events with three and four isolated charged leptons of all flavours originating from the decays of pair produced triplet components $\\Phi^{++}\\Phi^{--}$ and $\\Phi^{++}\\Phi^{-}.$ With the present collected luminosity the CMS experiment is sensitive to the $\\Phi$ mass range in which the possible decays $\\Phi^{++}\\to W^{+}W^{+}$ are forbidden kinematically. No signal excess is observed and lower limits at the 95\\% confidence level are set on the $\\Phi^{++}$ mass of 156\\GeV in the $\\mu\\mu$ channel, $154\\GeV$ in e$\\mu$ channel, of $144\\GeV$ in $ee$ channel and between $116\\GeV$ and $131\\GeV$ in the four defined ...

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We investigate the two-body decay modes {rho}{rho}, {pi}{pi}{sup *} (1300) and {sigma}{sigma} of the f{sub 0}(1500), all leading to the four pion decay channel, in a three-state mixing scheme, where the f{sub 0}(1500) is a mixture of the lowest lying scalar glueball with the nearby isoscalar states of the 0{sup ++}Q Q-bar nonet. In the leading order of this scheme, the decay mechanism of the f{sub 0}(1500) proceeds dominantly via its quarkonium components, which can be described in the framework of the {sup 3}P{sub 0} pair creation model. We predict the hierarchy of decay branching ratios B with B({rho}{rho}) {>=} B({pi}{pi}) {>=} B({sigma}{sigma}) > B({pi}{pi}{sup *}), providing a key signature of the proposed mixing scheme in this leading order approach. (authors)

CERN Document Server

Koide's mass formula is an empirical relation among the charged lepton masses which holds with a striking precision. We present a model of charged lepton sector based on U(3)\\times SU(2) family gauge symmetry, which predicts Koide's formula within the present experimental accuracy. Radiative corrections as well as other corrections to Koide's mass formula are kept under control. We adopt a known mechanism, through which the charged lepton spectrum is determined by the vacuum expectation value of a 9-component scalar field \\Phi. On the basis of this mechanism, we implement the following mechanisms into our model: (1) The radiative correction induced by family gauge interaction cancels the QED radiative correction to Koide's mass formula, assuming a scenario in which the U(3) family gauge symmetry and SU(2)_L weak gauge symmetry are unified at 10^2-10^3 TeV scale; (2) A simple potential of \\Phi invariant under U(3)\\times SU(2) leads to a realistic charged lepton ...

International Nuclear Information System (INIS)

The question concerning the existence of an electronic topological transition (ETT) in Zn metal under quasi-hydrostatic pressure at #approx#6.6 GPa caused a considerable controversy in the literature. We briefly review low-temperature "6"7Zn-Moessbauer data and scalar-relativistic augmented plane wave calculations and give a consistent interpretation in terms of an ETT. To highlight some important aspects of the controversy two theoretical and two experimental publications will be discussed in more detail. At present the existence of an ETT in Zn metal is disputed both from an experimental and from a theoretical point of view. The suggestion of a transition to a commensurate spin-density wave at #approx#6.6 GPa instead of an ETT may reconcile the seemingly contradictory results of "6"7Zn-Moessbauer experiments at 4.2 K and of room temperature inelastic neutron scattering measurements. However, it does not explain the anomalies found in theoretical calculations ...

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The general development of variational methods for fusion reactor blanket studies is given. Important quantities such as tritium breeding ratio and total nuclear heating are linear functionals of the solutions to the Boltzmann transport equation. To estimate a neutronic quantity by variational methods is, in general, to carry out the scalar product formulation of the Roussopoulos variational principle, or the Schwinger variational principle, with the help of the associated adjoint transport equation where the appropriate response function for the estimate is taken as the source. A multipoint interpolation method based on the above variational principles has been developed and compared to other variational approaches. The method of variational interpolation removes the need to compute both forward and adjoint solutions while the error has the characteristic of cancellation of errors between interpolation reference points. Finally, the practical computational ...

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In this thesis, the potential to discover supersymmetric signatures in both e"+e"- and #gamma##gamma# colliders evaluated with a Monte Carlo analysis, is discussed. The analysis was focused on the detection of muons, essentially. First, we study the detection of #mu#"+_R#mu#"-_R in e"-e"+ collisions, whose purpose is the measurement of the #mu#_R mass. It was found that an uncertainty of 0.11 GeV (stat) can be achieved. Under the assumption of the real conditions of the ILC photon collider, a study covering the detection of #mu#"+_R#mu#"-_R and #mu#"+_L#mu#"-_L pairs for #sq root#(s_e_"-_e_"+)=0.5 and 0.6 TeV was performed. According to the simulation, a statistical error for the branching ratios of #mu#"#+-#_L#->##chi#"0_1#mu#"#+-# of 0.98% and #mu#"#+-#_L#->##chi#"0_2#mu#"#+-# of 3.97% can be reached. In order to judge the Monte Carlo results, we have used a technique based on a multidimensional fit to evaluate the impact of the branching ratio measurements on the precision of ...

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We evaluate the neutrino fluxes to be expected from neutralino lightest supersymmetric particle (LSP) annihilations inside the Sun, within the minimal supersymmetric extension of the standard model with supersymmetry-breaking scalar and gaugino masses constrained to be universal at the grand unified theory scale [the constrained minimal supersymmetric standard model (CMSSM)]. We find that there are large regions of typical CMSSM (m_1_/_2,m_0) planes where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate. We show that neutrino fluxes are dependent on the solar model at the 20% level, and adopt the AGSS09 model of Serenelli et al. for our detailed studies. We find that there are large regions of the CMSSM (m_1_/_2,m_0) planes where the capture rate is not dominated by spin-dependent LSP-proton scattering, e.g., at large m_1_/_2 along the CMSSM coannihilation strip. We calculate neutrino fluxes above ...

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In this report, I surveyed physics potential of the #gamma##gamma# option of a linear e"+e"- collider with the following questions in mind: What new discovery can be expected at a #gamma##gamma# collider in addition to what will be learned at its 'parent' e"+e"- linear collider? By taking account of the hard energy spectrum and polarization of colliding photons, produced by Compton back-scattering of laser light off incoming e"- beams, we find that a #gamma##gamma# collider is most powerful when new physics appears in the neutral spin-zero channel at an invariant mass below about 80% of the c.m. energy of the colliding e"-e"- system. If a light Higgs boson exists, its properties can be studied in detail, and if its heavier partners or a heavy Higgs boson exists in the above mass range, they may be discovered at a #gamma##gamma# collider. CP property of the scalar sector can be explored in detail by making use of linear polarization of the colliding photons, decay ...

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Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed (dhcp) americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption energies were optimized with respect to the distance of the adatom from the relaxed surface for three adsorption sites, namely top, bridge, and hollow hcp sites, the ad-layer structure corresponding to the coverage of a 0.25 monolayer in all cases. Chemisorption energies were computed at the scalar-relativistic level (no spin-orbit coupling NSOC) and at the fully relativistic level (with spin-orbit coupling SOC). The two-fold bridge adsorption site was found to be the most stable site for O at both the NSOC and SOC theoretical levels with chemisorption energies of 8.204 eV and 8.368 eV respectively, while the three-fold hollow hcp adsorption ...

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PMID:3726630

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PurposeDescription and analysis of the effects and side-effects of integrated mental health care in the Netherlands.Context of caseDue...Full Text Available

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Development the New Effective Pesticides in the Series of Pyrimine and Sym-Triazine Derivatives

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This standard establishes requirements, verification criteria, and contractor tasks for electromagnetic effects protection of airborne, ground, and support systems. These effects include electromagnetic compatibility, electromagnetic interference, lightni...

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PMID:5089231

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... Title : The Effects of Flame Retardant Combinations in PVC-Epoxidised Natural Rubber Miscible Blends: Antimony Trioxide in Combination with ...

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Studies of the Superheavy-metal Effect as a Stress-factor on Protein Biosynthesis and Cytoskeleton Integrity in Animal Cells

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... biological effects body burden diet intestinal absorption lead lead 203 man

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... Accession Number : ADD323869. Title : EFFECTS OF SHIELDING ON PROPERTIES OF EDDY CURRENT PROBES WITH FERRITE CUP CORES. ...

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... Accession Number : ADA111683. Title : Coherency Effects on Retinal Neural Processes (ERG) of Pseudemys. Descriptive ...

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Full text of publication follows: During calculations of SAR accidents and transients it is necessary to perform steam generator simulation. Best accuracy is 3D transient calculations presented in report. Main outcomes of work was next: 1. There was shown by analysis the applicability of code TRAC (Los-Alamos laboratory) for thermal - hydraulic calculations of horizontal steam generator PGV-1000M. Special nodalization scheme was developed for it purposes. 2. Validation and selection of thermal-hydraulic correlations for improvement of using the code at calculation PGV-1000M were performed. As result Labuntsov formula is recommended for horizontal SG. 3. Calculations of nominal mode operation of PGV-1000M for cross-verification with code STEG (Electrogorsk Research and Engineering Center EREC) during its verification were performed. Solution by TRAC was obtained for transient problem after stabilization time. 4. Development of dynamic SG model as conjugate problem (thermal hydraulic of ...

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In this paper some physical mechanisms are described, which determine some new free-electron laser configurations. These mechanisms comprise some physical effects of the radiant emission of an electron beam at the interaction with the medium it is crossing. They are based on the Cherenkov effect, Smith-Purcell effect, optical klystron, Rumakhov effect and limited interaction effect. (Author).

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Effects of gamma irradiation on the physiological effectiveness of Korean medicinal herbs were investigated. The physiological effectiveness including antioxidant and anticomplement function, nitrite scavenging and electron donating ability of Korean medicinal herbs by gamma irradiation at 10 kGy did not differ from that of the nonirradiated control.

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Recent studies suggest that TJ-41, a herbal drug, possesses chemotherapeutic effects. Accordingly, this study was undertaken to investigate the anticarcinogenic effects of TJ-41 on human breast cancer...Full Text Available

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Investigation of memory effects in air at 0.7 mbar pressure in the presence of vacuum electrical breakdown mechanism has been performed in this paper. The memory effect has been followed using the time delay method.

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This volume presents the collations tables of a six volume comparative epidemiological survey of the effects of low level radiation dose. Data are collated for the effects observed in the following irradiated groups:- Preconception irradiation, intra-uterine irradiation, childhood irradiation, adult irradiation. (UK).

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BackgroundEffective prevention of excessive alcohol use has the potential to reduce the public burden of disease considerably. We investigated the cost-effectiveness of Screening...Full Text Available

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Nitric oxide (NO)-based therapies effectively inhibit neointimal hyperplasia in animal models of arterial injury and bypass grafting, but are not available clinically. We created a simple, effective,...Full Text Available

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This commentary adds effect sizes to the recently published systematic review by De Meester and colleagues and provides a more detailed insight into the effectiveness of interventions to promote physical...Full Text Available

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CT colonography (CTC) is increasingly advocated as an effective initial screening tool for colorectal cancer. Nowadays, policy-makers are increasingly interested in cost-effectiveness issues. A number of studies assessing the cost-effectiveness of CTC have been published to date. The majority of findings indicate that CTC is probably not cost-effective when colonoscopy is available, but this conclusion is sensitive to a number of key parameters. This review discusses the findings of these studies, and considers those factors which most influence final conclusions, notably intervention costs, compliance rates, effectiveness of colonoscopy, and the assumed prevalence and natural history of diminutive advanced polyps. (orig.)

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The pathological effects of lead on the renal, nervous, reproductive, endocrine, and immune systems have been reviewed. Emphasis is placed on reported subclinical effects due to chronic, low-level lead...Full Text Available

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... 1111/j.1558-5646.2007.00203.x THE BALDWIN EFFECT AND GENETIC ASSIMILATION: REVISITING TWO MECHANISMS OF ... to phenotypic plast...

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Wade. Jackson. - Army. VTD at NASA. Langley. ABSTRACT. Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich ...

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A summary of the effects presented here is given in the table. The designation "factor present" implies that there is knowledge (from human or animal studies, or both) of a specific factor(s) present...Full Text Available

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Objective:The present study describes the effect of nebivolol (NBV) either alone or in combination with lamotrigine (LTG) using increasing current electroshock seizures...Full Text Available

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... Title : Flame Retardant Effects in PVC-Epoxidised Natural Rubber Miscible Blends: Halogen and Non-Halogen Based Additives,. Corporate Author : ...

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BackgroundTo investigate the effects of intravenous lignocaine infusions (IV lignocaine) in fibromyalgia.MethodsProspective study...Full Text Available

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... Accession Number : ADA137272. Title : Effects of Yttrium Microalloying on the Epitaxial Grain Growth in Ti-6Al-4V Weld Fusion Zones. ...

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... EFFECT OF GAMMA RADIATION AND BAG PACKAGING MATERIALS ON

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Given growing interest in Functional Data Analysis (FDA) as a useful method for analyzing human movement data, it is critical to understand the effects of standard FDA procedures, including...Full Text Available

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Development of New Methods and Means of Assessing of Consequences of Radionuclide and Heavy Metal Salt Effect, Criteria of Forecasting Physiological State and Productivity of the Farm Animals under Conditions of Ecological Pollution of Environment

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... In the Proceedings of INTC 2003, we studied charging effects on target coverage during electrospinning (16). ... of Fibers from Electrospinning of ...

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... CAMOUFLAGE PATTERS- EFFECTS OFSIZE AND COL0R.-(U I'. * ... Camouflage, survei.Ilance, countersurveiliance, vi~sion, color ...

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... 4. TITLE AND SUBTITLE Atmospheric Scintillation Effects on Electromagnetic Weapons 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. ...

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BackgroundMany difficult problems in evolutionary genomics are related to mutations that have weak effects on fitness, as the consequences of mutations with large effects are often...Full Text Available

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PMID:7177024

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The Essentials of Mathematics, Grades 7-12

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... and testing of unidirectional composites, there are serious doubts about the possibility of obtaining a true ultimate compressive strength for this kind ...

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... organizations irradiation radiation doses radiation effects RADIATIONS.

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New fish cans were prepared in the Institute of Fish Industry, Burgas (BG), containing pectin and additives. A biological experimental study was conducted to investigate the decontaminating effect of the new products. The results demonstrated no decontaminating effect in relation to radiocesium and radiostrontium. A pronounced prophylactic effect was observed in case of external irradiation, judged by endogenous spleen colonies. (author).

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Japanese (Mar 1974). Japan Mabuchi, Toshio Kuwada, Hikaru . Kagawa Univ.,

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PMID:17276750

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the low levels of crystalline silica in this product, chronic health effects are not anticipated with normal

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We study heavy physics effects on the Higgs production in #gamma##gamma# fusion using the effective Lagrangian approach. We find that the effects coming from new physics may enhance the standard model predictions for the number of events expected in the final states b-barb, WW, and ZZ up to one order of magnitude, whereas the corresponding number of events for the final state t-bart may be enhanced up to two orders of magnitude.

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