Entropic quantization of scalar fields
International Nuclear Information System (INIS)
Ipek, Selman; Caticha, Ariel
2015-01-01
Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation
Entropic quantization of scalar fields
Energy Technology Data Exchange (ETDEWEB)
Ipek, Selman; Caticha, Ariel [Department of Physics, University at Albany-SUNY, Albany, NY 12222 (United States)
2015-01-13
Entropic Dynamics is an information-based framework that seeks to derive the laws of physics as an application of the methods of entropic inference. The dynamics is derived by maximizing an entropy subject to constraints that represent the physically relevant information that the motion is continuous and non-dissipative. Here we focus on the quantum theory of scalar fields. We provide an entropic derivation of Hamiltonian dynamics and using concepts from information geometry derive the standard quantum field theory in the Schrödinger representation.
Quantization of a scalar field in the Kerr spacetime
International Nuclear Information System (INIS)
Ford, L.H.
1974-01-01
A discussion of field quantization in a curved background spacetime is presented, with emphasis on the quantization of a scalar field in the Kerr spacetime. The ambiguity in the choice of a Fock space is discussed. The example of quantized fields in a rotating frame of reference in Minkowski space is analyzed, and it is shown that there is a preferred choice of states which makes particle number an invariant under transformation to the rotating frame. This choice allows the existence of negative energy quanta of the field
Background independent quantizations-the scalar field: II
International Nuclear Information System (INIS)
Kaminski, Wojciech; Lewandowski, Jerzy; Okolow, Andrzej
2006-01-01
We are concerned with the issue of the quantization of a scalar field in a diffeomorphism invariant manner. We apply the method used in loop quantum gravity. It relies on the specific choice of scalar field variables referred to as the polymer variables. The quantization, in our formulation, amounts to introducing the 'quantum' polymer *-star algebra and looking for positive linear functionals, called states. As assumed in our paper, homeomorphism invariance allows us to derive the complete class of the states. They are determined by the homeomorphism invariant states defined on the CW-complex *-algebra. The corresponding GNS representations of the polymer *-algebra and their self-adjoint extensions are derived, the equivalence classes are found, and invariant subspaces characterized. In part I we outlined those results. Here, we present the technical details
Propagators for a quantized scalar field in a static closed universe
International Nuclear Information System (INIS)
Nariai, Hidekazu; Azuma, Takahiro.
1978-07-01
In a previous paper, a massive scalar field in an expanding closed universe was canonically quantized by taking full account of its coupling-type with the background universe and of the latter's topological (spherical or elliptic) nature. General formulae (including the parts of vacuum fluctuation which should after all be removed by a suitable regularization) for the energy density and pressure of the quantized medium were derived. Various propagators for the quantized scalar field were also dealt with, because the Feynman propagator in particular became important as soon as the pair-creation of those particles was called for. However, there will be an intimate relation between the former hydrodynamic quantities and the pair-creation of their constituents. Accordingly, this problem is studied in detail by adopting a static closed universe (for simplicity in the reduction of various expressions derived in the previous paper) and examining the behavior of various bi-scalar propagators in the universe. (author)
On a quantized scalar field in the de Sitter and Nariai universes
International Nuclear Information System (INIS)
Nariai, Hidekazu.
1984-08-01
After canonical quantization of a massive or massless scalar field in the de Sitter and Nariai universes (both of which satisfy the same Einstein equations with a non-vanishing cosmological constant, Rsub(μν)=Agsub(μν), but their topological structures differ from each other), the uniquely obtained 4-dimensional commutation functions in both universes are comparatively studied with due emphasis on their topological structures, as well as the difference of couplings to the background universe. (author)
International Nuclear Information System (INIS)
Nariai, Hidekazu
1981-01-01
As a sequel to previous works on the definition of a positive frequency part of a quantized scalar field near an initial stage of several Robertson-Walker universes with flat, open or closed 3-space and the associated pair-creation of those particles, an attempt is made to seek for the same concept in several Bianchi-type I anisotropic universes. It is shown that, if the positive frequency part is introduced, the pair-creation of scalar particles and their spectral law are uniquely determined, as in the case of isotropic universes. (author)
Uniqueness of the Fock quantization of scalar fields in spatially flat cosmological spacetimes
Energy Technology Data Exchange (ETDEWEB)
Gomar, Laura Castelló [Facultad de Ciencias Físicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Cortez, Jerónimo [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico D.F. 04510 (Mexico); Blas, Daniel Martín-de; Marugán, Guillermo A. Mena [Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Velhinho, José M., E-mail: laucaste@estumail.ucm.es, E-mail: jacq@ciencias.unam.mx, E-mail: daniel.martin@iem.cfmac.csic.es, E-mail: jvelhi@ubi.pt [Departamento de Física, Faculdade de Ciências, Universidade da Beira Interior, R. Marquês D' Ávila e Bolama, 6201-001 Covilhã (Portugal)
2012-11-01
We study the Fock quantization of scalar fields in (generically) time dependent scenarios, focusing on the case in which the field propagation occurs in –either a background or effective– spacetime with spatial sections of flat compact topology. The discussion finds important applications in cosmology, like e.g. in the description of test Klein-Gordon fields and scalar perturbations in Friedmann-Robertson-Walker spacetime in the observationally favored flat case. Two types of ambiguities in the quantization are analyzed. First, the infinite ambiguity existing in the choice of a Fock representation for the canonical commutation relations, understandable as the freedom in the choice of inequivalent vacua for a given field. Besides, in cosmological situations, it is customary to scale the fields by time dependent functions, which absorb part of the evolution arising from the spacetime, which is treated classically. This leads to an additional ambiguity, this time in the choice of a canonical pair of field variables. We show that both types of ambiguities are removed by the requirements of (a) invariance of the vacuum under the symmetries of the three-torus, and (b) unitary implementation of the dynamics in the quantum theory. In this way, one arrives at a unique class of unitarily equivalent Fock quantizations for the system. This result provides considerable robustness to the quantum predictions and renders meaningful the confrontation with observation.
Polymer quantization of the free scalar field and its classical limit
Energy Technology Data Exchange (ETDEWEB)
Laddha, Alok; Varadarajan, Madhavan, E-mail: alok@rri.res.i, E-mail: madhavan@rri.res.i [Raman Research Institute, Bangalore 560 080 (India)
2010-09-07
Building on prior work, a generally covariant reformulation of a free scalar field theory on the flat Lorentzian cylinder is quantized using loop quantum gravity (LQG)-type 'polymer' representations. This quantization of the continuum classical theory yields a quantum theory which lives on a discrete spacetime lattice. We explicitly construct a state in the polymer Hilbert space which reproduces the standard Fock vacuum two-point functions for long-wavelength modes of the scalar field. Our construction indicates that the continuum classical theory emerges under coarse graining. All our considerations are free of the 'triangulation' ambiguities which plague attempts to define quantum dynamics in LQG. Our work constitutes the first complete LQG-type quantization of a generally covariant field theory together with a semi-classical analysis of the true degrees of freedom and thus provides a perfect infinite-dimensional toy model to study open issues in LQG, particularly those pertaining to the definition of quantum dynamics.
The canonical quantization of local scalar fields over quantum space-time
International Nuclear Information System (INIS)
Banai, M.
1983-05-01
Canonical quantization of a classical local field theory (CLFT) consisting of N real scalar fields is formulated in the Hilbert space over the sup(*)-algebra A of linear operators of L 2 (R 3 ). The canonical commutation relations (CCR) have an irreducible solution, unique up to A-unitary equivalence. The canonical equations as operator equations are equivalent to the classical (c) field equations. The interaction picture can be introduced in a well-defined manner. The main adventage of this treatment is that the corresponding S-matrix is free of divergences. The Feynman's graph technique is adaptable in a straightforward manner. This approach is a natural extension of the conventional canonical quantization method of quantum mechanics. (author)
A uniqueness criterion for the Fock quantization of scalar fields with time-dependent mass
International Nuclear Information System (INIS)
Cortez, Jeronimo; Mena Marugan, Guillermo A; Olmedo, Javier; Velhinho, Jose M
2011-01-01
A major problem in the quantization of fields in curved spacetimes is the ambiguity in the choice of a Fock representation for the canonical commutation relations. There exists infinite number of choices leading to different physical predictions. In stationary scenarios, a common strategy is to select a vacuum (or a family of unitarily equivalent vacua) by requiring invariance under the spacetime symmetries. When stationarity is lost, a natural generalization consists in replacing time invariance by unitarity in the evolution. We prove that when the spatial sections are compact, the criterion of a unitary dynamics, together with the invariance under the spatial isometries, suffices to select a unique family of Fock quantizations for a scalar field with time-dependent mass. (fast track communication)
An unconventional canonical quantization of local scalar fields over quantum space-time
International Nuclear Information System (INIS)
Banai, M.
1985-12-01
An unconventional extension of the canonical quantization method is presented for a classical local field theory. The proposed canonical commutation relations have a solution in the A-valued Hilbert space where A is the algebra of the bounded operators of the Hilbert space Lsup(2) (IRsup(3)). The canonical equations as operator equations are equivalent formally with the classical field equations, and are well defined for interacting systems, too. This model of quantized field lacks some of the difficulties of the conventional approach. Examples satisfying the asymptotic condition provide examples for Haag-Kastler's axioms, however, they satisfy Wightman's axioms only partially. (author)
Quantization of scalar-spinor instanton
International Nuclear Information System (INIS)
Inagaki, H.
1977-04-01
A systematic quantization to the scalar-spinor instanton is given in a canonical formalism of Euclidean space. A basic idea is in the repair of the symmetries of the 0(5) covariant system in the presence of the instanton. The quantization of the fermion is carried through in such a way that the fermion number should be conserved. Our quantization enables us to get well-defined propagators for both the scalar and the fermion, which are free from unphysical poles
Unique Fock quantization of scalar cosmological perturbations
Fernández-Méndez, Mikel; Mena Marugán, Guillermo A.; Olmedo, Javier; Velhinho, José M.
2012-05-01
We investigate the ambiguities in the Fock quantization of the scalar perturbations of a Friedmann-Lemaître-Robertson-Walker model with a massive scalar field as matter content. We consider the case of compact spatial sections (thus avoiding infrared divergences), with the topology of a three-sphere. After expanding the perturbations in series of eigenfunctions of the Laplace-Beltrami operator, the Hamiltonian of the system is written up to quadratic order in them. We fix the gauge of the local degrees of freedom in two different ways, reaching in both cases the same qualitative results. A canonical transformation, which includes the scaling of the matter-field perturbations by the scale factor of the geometry, is performed in order to arrive at a convenient formulation of the system. We then study the quantization of these perturbations in the classical background determined by the homogeneous variables. Based on previous work, we introduce a Fock representation for the perturbations in which: (a) the complex structure is invariant under the isometries of the spatial sections and (b) the field dynamics is implemented as a unitary operator. These two properties select not only a unique unitary equivalence class of representations, but also a preferred field description, picking up a canonical pair of field variables among all those that can be obtained by means of a time-dependent scaling of the matter field (completed into a linear canonical transformation). Finally, we present an equivalent quantization constructed in terms of gauge-invariant quantities. We prove that this quantization can be attained by a mode-by-mode time-dependent linear canonical transformation which admits a unitary implementation, so that it is also uniquely determined.
International Nuclear Information System (INIS)
Nariai, Hidekazu.
1981-01-01
The concept of a positive frequency part near the initial epoch in a big-bang universe or its counterpart in other (say, de Sitter) one for a canonically quantized scalar field is important in discussing the associated pair-creation of those particles. Therefore, an attempt is made to define the positive frequency part in such isotropic closed and open universes that the scalar wave equation can be exactly solved. Except for some closed universe, the parts in question and, therefore, the Feynman propagators in the remaining universes are uniquely settled. Then it is shown that (1) the pair-creation in the Friedmann open universe (which is very interesting not only from observational, but also from theoretical viewpoints) is essentially equivalent to that in the Chitre-Hartle universe with flat 3-space and (2) the respective pair-creations in expanding metrics with open and flat 3-spaces of the de Sitter universe are different from each other, as insisted upon by Gibbons and Hawking basing on the original static metric. (author)
International Nuclear Information System (INIS)
Nariai, Hidekazu
1982-01-01
The concept of a positive frequency part near the initial epoch in a big-bang universe or its counterpart in other (say, de Sitter) one for a canonically quantized scalar field is important in discussing the associated pair-creation of those particles. Therefore, an attempt is made to define the positive frequency part in such isotropic closed and open universes that the scalar wave equation can be exactly solved. Except for some closed universe, the parts in question and, therefore, the Feynman propagators in the remaining universes are uniquely settled. Then it is shown that (1) the pair-creation in the Friedmann open universe (which is very interesting not only from observational, but also from theoretical viewpoints) is essentially equivalent to that in the Chitre-Hartle universe with flat 3-space and (2) the respective pair-creations in expanding metrics with open and flat 3-spaces of the de Sitter universe are different from each other, as insisted upon by Gibbons and Hawking basing on the original static metric. (author)
International Nuclear Information System (INIS)
Haro, Jaume; Amoros, Jaume
2011-01-01
There are two nonequivalent ways to check if quantum effects in the context of semiclassical gravity can moderate or even cancel the final singularity appearing in a universe filled with dark energy: The method followed in [J. D. Bates and P. R. Anderson, Phys. Rev. D 82, 024018 (2010).] is to introduce the classical Friedmann solution in the energy density of the quantum field, and to compare the result with the density of dark energy determined by the Friedmann equation. The method followed in this comment is to solve directly the semiclassical equations. The results obtained by either method are very different, leading to opposed conclusions. The authors of [J. D. Bates and P. R. Anderson, Phys. Rev. D 82, 024018 (2010)] find that for a perfect fluid with state equation p=ωρ and ω<-1 (phantom fluid), considering realistic values of ω leads to a quantum field energy density that remains small compared to the dark energy density until the curvature reaches the Planck scale or higher, at which point the semiclassical approach stops being valid. The conclusion is that quantum effects do not affect significantly the expansion of the universe until the scalar curvature reaches the Planck scale. In this comment we will show by numerical integration of the semiclassical equations that quantum effects modify drastically the expansion of the universe from an early point. We also present an analytic argument explaining why the method of [J. D. Bates and P. R. Anderson, Phys. Rev. D 82, 024018 (2010)] fails to detect this. The units employed are the same as in [J. D. Bates and P. R. Anderson, Phys. Rev. D 82, 024018 (2010)] (c=(ℎ/2π)=G=1).
International Nuclear Information System (INIS)
Arodz, H.
1987-01-01
The two formulations of quantum theory of the free electromagnetic field are presented. In the Coulomb gauge approach the independent dynamical variables have been identified and then, in order to quantize the theory, it has been sufficient to apply the straightforward canonical quantization. In the Gupta-Bleuler approach the auxilliary theory is first considered. The straightforward canonical quantization of it leads to the quantum theory defined in the space G with indefinite norm. 15 refs. (author)
Quantized fields in external field. Pt. 2
International Nuclear Information System (INIS)
Bellissard, J.
1976-01-01
The case of a charged scalar field is considered first. The existence of the corresponding Green's functions is proved. For weak fields, as well as pure electric or scalar external fields, the Bogoliubov S-operator is shown to be unitary, covariant, causal up-to-a-phase. These results are generalised to a class of higher spin quantized fields, 'nicely' coupled to external fields, which includes the Dirac theory, and in the case of minimal and magnetic dipole coupling, the spin one Petiau-Duffin-Kemmer theory. (orig.) [de
Immirzi parameter without Immirzi ambiguity: Conformal loop quantization of scalar-tensor gravity
Veraguth, Olivier J.; Wang, Charles H.-T.
2017-10-01
Conformal loop quantum gravity provides an approach to loop quantization through an underlying conformal structure i.e. conformally equivalent class of metrics. The property that general relativity itself has no conformal invariance is reinstated with a constrained scalar field setting the physical scale. Conformally equivalent metrics have recently been shown to be amenable to loop quantization including matter coupling. It has been suggested that conformal geometry may provide an extended symmetry to allow a reformulated Immirzi parameter necessary for loop quantization to behave like an arbitrary group parameter that requires no further fixing as its present standard form does. Here, we find that this can be naturally realized via conformal frame transformations in scalar-tensor gravity. Such a theory generally incorporates a dynamical scalar gravitational field and reduces to general relativity when the scalar field becomes a pure gauge. In particular, we introduce a conformal Einstein frame in which loop quantization is implemented. We then discuss how different Immirzi parameters under this description may be related by conformal frame transformations and yet share the same quantization having, for example, the same area gaps, modulated by the scalar gravitational field.
Quantization and nonlocal fields
International Nuclear Information System (INIS)
Kolerov, G.I.
1977-01-01
A relation between the postulate of causality and quatization conditions is considered for the scalar field. A formalism of outer forms given on the functional space is used. A current commutator is obtained for nonlogical fields in the space-like region
Magnetic resonance image compression using scalar-vector quantization
Mohsenian, Nader; Shahri, Homayoun
1995-12-01
A new coding scheme based on the scalar-vector quantizer (SVQ) is developed for compression of medical images. SVQ is a fixed-rate encoder and its rate-distortion performance is close to that of optimal entropy-constrained scalar quantizers (ECSQs) for memoryless sources. The use of a fixed-rate quantizer is expected to eliminate some of the complexity issues of using variable-length scalar quantizers. When transmission of images over noisy channels is considered, our coding scheme does not suffer from error propagation which is typical of coding schemes which use variable-length codes. For a set of magnetic resonance (MR) images, coding results obtained from SVQ and ECSQ at low bit-rates are indistinguishable. Furthermore, our encoded images are perceptually indistinguishable from the original, when displayed on a monitor. This makes our SVQ based coder an attractive compression scheme for picture archiving and communication systems (PACS), currently under consideration for an all digital radiology environment in hospitals, where reliable transmission, storage, and high fidelity reconstruction of images are desired.
Quantization of fields with constraints
Energy Technology Data Exchange (ETDEWEB)
Gitman, D.M.; Tyutin, I.V.
1990-01-01
The quantization of singular field theories, in particular, gauge theories, is one of the key problems in quantum field theory. This book - which addresses the reader acquainted with the foundations of quantum field theory - provides a comprehensive analysis of this problem and techniques for its solution. The main topics are canonical and Lagrangian quantization and the path integral method. (orig.).
Path integral quantization of parametrized field theory
International Nuclear Information System (INIS)
Varadarajan, Madhavan
2004-01-01
Free scalar field theory on a flat spacetime can be cast into a generally covariant form known as parametrized field theory in which the action is a functional of the scalar field as well as the embedding variables which describe arbitrary, in general curved, foliations of the flat spacetime. We construct the path integral quantization of parametrized field theory in order to analyze issues at the interface of quantum field theory and general covariance in a path integral context. We show that the measure in the Lorentzian path integral is nontrivial and is the analog of the Fradkin-Vilkovisky measure for quantum gravity. We construct Euclidean functional integrals in the generally covariant setting of parametrized field theory using key ideas of Schleich and show that our constructions imply the existence of nonstandard 'Wick rotations' of the standard free scalar field two-point function. We develop a framework to study the problem of time through computations of scalar field two-point functions. We illustrate our ideas through explicit computation for a time independent (1+1)-dimensional foliation. Although the problem of time seems to be absent in this simple example, the general case is still open. We discuss our results in the contexts of the path integral formulation of quantum gravity and the canonical quantization of parametrized field theory
A geometrical approach to free-field quantization
International Nuclear Information System (INIS)
Tabensky, R.; Valle, J.W.F.
1977-01-01
A geometrical approach to the quantization of free relativistic fields is given. Complex probability amplitudes are assigned to the solutions of the classical evolution equation. It is assumed that the evolution is stricly classical, according to the scalar unitary representation of the Poincare group in a functional space. The theory is equivalent to canonical quantization [pt
Light-front quantization of field theory
Energy Technology Data Exchange (ETDEWEB)
Srivastava, Prem P. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
1996-07-01
Some basic topics in Light-Front (LF) quantized field theory are reviewed. Poincare algebra and the LF spin operator are discussed. The local scalar field theory of the conventional framework is shown to correspond to a non-local Hamiltonian theory on the LF in view of the constraint equations on the phase space, which relate the bosonic condensates to the non-zero modes. This new ingredient is useful to describe the spontaneous symmetry breaking on the LF. The instability of the symmetric phase in two dimensional scalar theory when the coupling constant grows is shown in the LF theory renormalized to one loop order. Chern-Simons gauge theory, regarded to describe excitations with fractional statistics, is quantized in the light-cone gauge and a simple LF Hamiltonian obtained which may allow us to construct renormalized theory of anyons. (author). 20 refs.
Light-front quantization of field theory
International Nuclear Information System (INIS)
Srivastava, Prem P.
1996-07-01
Some basic topics in Light-Front (LF) quantized field theory are reviewed. Poincare algebra and the LF spin operator are discussed. The local scalar field theory of the conventional framework is shown to correspond to a non-local Hamiltonian theory on the LF in view of the constraint equations on the phase space, which relate the bosonic condensates to the non-zero modes. This new ingredient is useful to describe the spontaneous symmetry breaking on the LF. The instability of the symmetric phase in two dimensional scalar theory when the coupling constant grows is shown in the LF theory renormalized to one loop order. Chern-Simons gauge theory, regarded to describe excitations with fractional statistics, is quantized in the light-cone gauge and a simple LF Hamiltonian obtained which may allow us to construct renormalized theory of anyons. (author). 20 refs
Wavelet/scalar quantization compression standard for fingerprint images
Energy Technology Data Exchange (ETDEWEB)
Brislawn, C.M.
1996-06-12
US Federal Bureau of Investigation (FBI) has recently formulated a national standard for digitization and compression of gray-scale fingerprint images. Fingerprints are scanned at a spatial resolution of 500 dots per inch, with 8 bits of gray-scale resolution. The compression algorithm for the resulting digital images is based on adaptive uniform scalar quantization of a discrete wavelet transform subband decomposition (wavelet/scalar quantization method). The FBI standard produces archival-quality images at compression ratios of around 15 to 1 and will allow the current database of paper fingerprint cards to be replaced by digital imagery. The compression standard specifies a class of potential encoders and a universal decoder with sufficient generality to reconstruct compressed images produced by any compliant encoder, allowing flexibility for future improvements in encoder technology. A compliance testing program is also being implemented to ensure high standards of image quality and interchangeability of data between different implementations.
2-Step scalar deadzone quantization for bitplane image coding.
Auli-Llinas, Francesc
2013-12-01
Modern lossy image coding systems generate a quality progressive codestream that, truncated at increasing rates, produces an image with decreasing distortion. Quality progressivity is commonly provided by an embedded quantizer that employs uniform scalar deadzone quantization (USDQ) together with a bitplane coding strategy. This paper introduces a 2-step scalar deadzone quantization (2SDQ) scheme that achieves same coding performance as that of USDQ while reducing the coding passes and the emitted symbols of the bitplane coding engine. This serves to reduce the computational costs of the codec and/or to code high dynamic range images. The main insights behind 2SDQ are the use of two quantization step sizes that approximate wavelet coefficients with more or less precision depending on their density, and a rate-distortion optimization technique that adjusts the distortion decreases produced when coding 2SDQ indexes. The integration of 2SDQ in current codecs is straightforward. The applicability and efficiency of 2SDQ are demonstrated within the framework of JPEG2000.
Phase-space quantization of field theory
International Nuclear Information System (INIS)
Curtright, T.; Zachos, C.
1999-01-01
In this lecture, a limited introduction of gauge invariance in phase-space is provided, predicated on canonical transformations in quantum phase-space. Exact characteristic trajectories are also specified for the time-propagating Wigner phase-space distribution function: they are especially simple--indeed, classical--for the quantized simple harmonic oscillator. This serves as the underpinning of the field theoretic Wigner functional formulation introduced. Scalar field theory is thus reformulated in terms of distributions in field phase-space. This is a pedagogical selection from work published and reported at the Yukawa Institute Workshop ''Gauge Theory and Integrable Models'', 26-29 January, 1999
Creation of quantized particles, gravitons, and scalar perturbations by the expanding universe
International Nuclear Information System (INIS)
Parker, Leonard
2015-01-01
Quantum creation processes during the very rapid early expansion of the universe are believed to give rise to temperature anisotropies and polarization patterns in the CMB radiation. These have been observed by satellites such as COBE, WMAP, and PLANCK, and by bolometric instruments placed near the South Pole by the BICEP collaborations. The expected temperature anisotropies are well-confirmed. The B-mode polarization patterns in the CMB are currently under measurement jointly by the PLANCK and BICEP groups to determine the extent to which the B-modes can be attributed to gravitational waves from the creation of gravitons in the earliest universe.As the original discoverer of the quantum phenomenon of particle creation from vacuum by the expansion of the universe, I will explain how the discovery came about and how it relates to the current observations. The first system that I considered when I started my Ph.D. thesis in 1962 was the quantized minimally-coupled scalar field in an expanding FLRW (Friedmann, Lemaitré, Robertson, Walker) universe having a general continuous scale factor a(t) with continuous time derivatives. I also considered quantized fermion fields of spin-1/2 and the spin-1 massless photon field, as well as the quantized conformally-invariant field equations of arbitrary integer and half-integer spins that had been written down in the classical context for general gravitational metrics by Penrose.It was during 1962 that I proved that quanta of the minimally-coupled scalar field were created by the general expanding FLRW universe. This was relevant also to the creation of quantized perturbations of the gravitational field, since these perturbations satisfied linear field equations that could be quantized in the same way as the minimally-coupled scalar field equation. In fact, in 1946, E.M. Lifshitz had considered the classical Einstein gravitational field in FLRW expanding universes and had shown that the classical linearized Einstein field
Stochastic quantization of Proca field
International Nuclear Information System (INIS)
Lim, S.C.
1981-03-01
We discuss the complications that arise in the application of Nelson's stochastic quantization scheme to classical Proca field. One consistent way to obtain spin-one massive stochastic field is given. It is found that the result of Guerra et al on the connection between ground state stochastic field and the corresponding Euclidean-Markov field extends to the spin-one case. (author)
Quantization of the Radiation Field
Indian Academy of Sciences (India)
field,quantization,Lamb shift. Avinash Khare ... actions as well as for theories beyond like grand unified theories. Further, the same ... cules as well as condensed matter physics, not to men- tion their ... of an electromagnetic field by a moving electron, and of the reaction of this field on the electron have not yet been touched.".
Nonperturbative loop quantization of scalar-tensor theories of gravity
International Nuclear Information System (INIS)
Zhang Xiangdong; Ma Yongge
2011-01-01
The Hamiltonian formulation of scalar-tensor theories of gravity is derived from their Lagrangian formulation by Hamiltonian analysis. The Hamiltonian formalism marks off two sectors of the theories by the coupling parameter ω(φ). In the sector of ω(φ)=-(3/2), the feasible theories are restricted and a new primary constraint generating conformal transformations of spacetime is obtained, while in the other sector of ω(φ)≠-(3/2), the canonical structure and constraint algebra of the theories are similar to those of general relativity coupled with a scalar field. By canonical transformations, we further obtain the connection-dynamical formalism of the scalar-tensor theories with real su(2) connections as configuration variables in both sectors. This formalism enables us to extend the scheme of nonperturbative loop quantum gravity to the scalar-tensor theories. The quantum kinematical framework for the scalar-tensor theories is rigorously constructed. Both the Hamiltonian constraint operator and master constraint operator are well defined and proposed to represent quantum dynamics. Thus the loop quantum gravity method is also valid for general scalar-tensor theories.
Topological quantization of gravitational fields
International Nuclear Information System (INIS)
Patino, Leonardo; Quevedo, Hernando
2005-01-01
We introduce the method of topological quantization for gravitational fields in a systematic manner. First we show that any vacuum solution of Einstein's equations can be represented in a principal fiber bundle with a connection that takes values in the Lie algebra of the Lorentz group. This result is generalized to include the case of gauge matter fields in multiple principal fiber bundles. We present several examples of gravitational configurations that include a gravitomagnetic monopole in linearized gravity, the C-energy of cylindrically symmetric fields, the Reissner-Nordstroem and the Kerr-Newman black holes. As a result of the application of the topological quantization procedure, in all the analyzed examples we obtain conditions implying that the parameters entering the metric in each case satisfy certain discretization relationships
Quantized fields in interaction with external fields. Pt. 1
International Nuclear Information System (INIS)
Bellissard, J.
1975-01-01
We consider a massive, charged, scalar quantized field interacting with an external classical field. Guided by renormalized perturbation theory we show that whenever the integral equations defining the Feynman or retarded or advanced interaction kernel possess non perturbative solutions, there exists an S-operator which satisfies, up to a phase, the axioms of Bogoliubov, and is given for small external fields by a power series which converges on coherent states. Furthermore this construction is shown to be equivalent to the one based on the Yang-Kaellen-Feldman equation. This is a consequence of the relations between chronological and retarded Green's functions which are described in detail. (orig.) [de
Twisted condensates of quantized fields
International Nuclear Information System (INIS)
Gallone, F.; Sparzani, A.; Ubertone, G.; Streater, R.F.
We construct some quasi-free pure states of free quantized fields in 1+1 dimensions, that are localized in the sense of Knight. We consider massless or massive Dirac fields forming a U(n), n >= 1, multiplet and subject it to a local gauge transformation. We also subject a doublet of massive Klein-Gordon fields to local SO(2) transformations. We find the conditions that the resulting automorphism is spatial in Fock space. In some cases the conditions turn out to require that certain parameters, identified as the winding numbers of the gauge, are integers. It is argued that this integer labels states of various charge. (orig.)
The wavelet/scalar quantization compression standard for digital fingerprint images
Energy Technology Data Exchange (ETDEWEB)
Bradley, J.N.; Brislawn, C.M.
1994-04-01
A new digital image compression standard has been adopted by the US Federal Bureau of Investigation for use on digitized gray-scale fingerprint images. The algorithm is based on adaptive uniform scalar quantization of a discrete wavelet transform image decomposition and is referred to as the wavelet/scalar quantization standard. The standard produces archival quality images at compression ratios of around 20:1 and will allow the FBI to replace their current database of paper fingerprint cards with digital imagery.
International Nuclear Information System (INIS)
Klauder, J.R.
1983-01-01
The author provides an introductory survey to stochastic quantization in which he outlines this new approach for scalar fields, gauge fields, fermion fields, and condensed matter problems such as electrons in solids and the statistical mechanics of quantum spins. (Auth.)
Symmetry inheritance of scalar fields
International Nuclear Information System (INIS)
Ivica Smolić
2015-01-01
Matter fields do not necessarily have to share the symmetries with the spacetime they live in. When this happens, we speak of the symmetry inheritance of fields. In this paper we classify the obstructions of symmetry inheritance by the scalar fields, both real and complex, and look more closely at the special cases of stationary and axially symmetric spacetimes. Since the symmetry noninheritance is present in the scalar fields of boson stars and may enable the existence of the black hole scalar hair, our results narrow the possible classes of such solutions. Finally, we define and analyse the symmetry noninheritance contributions to the Komar mass and angular momentum of the black hole scalar hair. (paper)
Spherically symmetric scalar field collapse
Indian Academy of Sciences (India)
2013-03-01
Mar 1, 2013 ... The very recent interest in scalar field collapse stems from a cosmological ... The objective of the present investigation is to explore the collapsing modes of a simple ..... The authors thank the BRNS (DAE) for financial support.
Quantization in presence of external soliton fields
International Nuclear Information System (INIS)
Grosse, H.; Karner, G.
1986-01-01
Quantization of a fermi field interacting with an external soliton protential is considered. Classes of interactions leading to unitarily equivalent representations of the canonical anticommutation relations are determined. Soliton-like potentials compared to trivial ones yield inequivalent representations. (Author)
On the Uniqueness of the Fock Quantization of the Dirac Field in the Closed FRW Cosmology
Directory of Open Access Journals (Sweden)
Jerónimo Cortez
2018-01-01
Full Text Available The Fock quantization of free fields propagating in cosmological backgrounds is in general not unambiguously defined due to the nonstationarity of the space-time. For the case of a scalar field in cosmological scenarios, it is known that the criterion of unitary implementation of the dynamics serves to remove the ambiguity in the choice of Fock representation (up to unitary equivalence. Here, applying the same type of arguments and methods previously used for the scalar field case, we discuss the issue of the uniqueness of the Fock quantization of the Dirac field in the closed FRW space-time proposed by D’Eath and Halliwell.
Random scalar fields and hyperuniformity
Ma, Zheng; Torquato, Salvatore
2017-06-01
Disordered many-particle hyperuniform systems are exotic amorphous states of matter that lie between crystals and liquids. Hyperuniform systems have attracted recent attention because they are endowed with novel transport and optical properties. Recently, the hyperuniformity concept has been generalized to characterize two-phase media, scalar fields, and random vector fields. In this paper, we devise methods to explicitly construct hyperuniform scalar fields. Specifically, we analyze spatial patterns generated from Gaussian random fields, which have been used to model the microwave background radiation and heterogeneous materials, the Cahn-Hilliard equation for spinodal decomposition, and Swift-Hohenberg equations that have been used to model emergent pattern formation, including Rayleigh-Bénard convection. We show that the Gaussian random scalar fields can be constructed to be hyperuniform. We also numerically study the time evolution of spinodal decomposition patterns and demonstrate that they are hyperuniform in the scaling regime. Moreover, we find that labyrinth-like patterns generated by the Swift-Hohenberg equation are effectively hyperuniform. We show that thresholding (level-cutting) a hyperuniform Gaussian random field to produce a two-phase random medium tends to destroy the hyperuniformity of the progenitor scalar field. We then propose guidelines to achieve effectively hyperuniform two-phase media derived from thresholded non-Gaussian fields. Our investigation paves the way for new research directions to characterize the large-structure spatial patterns that arise in physics, chemistry, biology, and ecology. Moreover, our theoretical results are expected to guide experimentalists to synthesize new classes of hyperuniform materials with novel physical properties via coarsening processes and using state-of-the-art techniques, such as stereolithography and 3D printing.
Stochastic quantization of gravity and string fields
International Nuclear Information System (INIS)
Rumpf, H.
1986-01-01
The stochastic quantization method of Parisi and Wu is generalized so as to make it applicable to Einstein's theory of gravitation. The generalization is based on the existence of a preferred metric in field configuration space, involves Ito's calculus, and introduces a complex stochastic process adapted to Lorentzian spacetime. It implies formally the path integral measure of DeWitt, a causual Feynman propagator, and a consistent stochastic perturbation theory. The lineraized version of the theory is also obtained from the stochastic quantization of the free string field theory of Siegel and Zwiebach. (Author)
Higgs mechanism in light-front quantized field theory
Energy Technology Data Exchange (ETDEWEB)
Srivastava, P P
1993-12-31
The spontaneous symmetry breaking of continuous symmetry in light-front quantized scalar field theory is studied following the standard Dirac procedure for constrained dynamical systems. A non-local constraint is found to follow. The values of the constant backgrounds fields (zero modes) at the tree level, as a consequence, are shown to given by minimizing the light-front energy. The zero modes are shown to commute with the non-zero ones and the isovector built from them is seen to characterize a (non-perturbative) vacuum state and the corresponding physical sector. The infinite degeneracy of the vacuum is described by the continuum of the allowed orientations of this background isovector in the isospin space. The symmetry generators in the quantized field theory annihilate the vacuum is contrast to the case of equal-time quantization. Not all of them are conserved and the conserved ones determine the surviving symmetry of the quantum theory Lagrangian. The criteria for determining the background isovector and the counting of the number of Goldstone bosons goes as in the equal-time case. A demonstration in favour of the absence of Goldstone bosons in two dimensions is also found. Finally, is extended to an understanding of the Higgs mechanism in light-front frame. (author). 13 refs.
Higgs mechanism in light-front quantized field theory
International Nuclear Information System (INIS)
Srivastava, P.P.
1992-01-01
The spontaneous symmetry breaking of continuous symmetry in light-front quantized scalar field theory is studied following the standard Dirac procedure for constrained dynamical systems. A non-local constraint is found to follow. The values of the constant backgrounds fields (zero modes) at the tree level, as a consequence, are shown to given by minimizing the light-front energy. The zero modes are shown to commute with the non-zero ones and the isovector built from them is seen to characterize a (non-perturbative) vacuum state and the corresponding physical sector. The infinite degeneracy of the vacuum is described by the continuum of the allowed orientations of this background isovector in the isospin space. The symmetry generators in the quantized field theory annihilate the vacuum is contrast to the case of equal-time quantization. Not all of them are conserved and the conserved ones determine the surviving symmetry of the quantum theory Lagrangian. The criteria for determining the background isovector and the counting of the number of Goldstone bosons goes as in the equal-time case. A demonstration in favour of the absence of Goldstone bosons in two dimensions is also found. Finally, is extended to an understanding of the Higgs mechanism in light-front frame. (author). 13 refs
The generalized Fenyes-Nelson model for free scalar field theory
International Nuclear Information System (INIS)
Davidson, M.
1980-01-01
The generalized Fenyes-Nelson model of quantum mechanics is applied to the free scalar field. The resulting Markov field is equivalent to the Euclidean Markov field with the times scaled by a common factor which depends on the diffusion parameter. This result is consistent with Guerra's earlier work on stochastic quantization of scalar fields. It suggests a deep connection between Euclidean field theory and the stochastic interpretation of quantum mechanics. The question of Lorentz covariance is also discussed. (orig.)
Particle states of a quantized meson field
International Nuclear Information System (INIS)
Skyrme, T.H.R.
1994-01-01
A simple non-linear field theory is considered as the model for a recently proposed classical field theory of mesons and their particle sources. Quantization may be made according to canonical procedures; the problem is to show the existence of quantum states corresponding with the particle-like solutions of the classical field equations. A plausible way to do this is suggested. (author). 5 refs
Scalar field cosmology in three-dimensions
International Nuclear Information System (INIS)
Oliveira Neto, G.
2001-01-01
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)
Functional representations for quantized fields
International Nuclear Information System (INIS)
Jackiw, R.
1988-01-01
This paper provides information on Representing transformations in quantum theory bosonic quantum field theories: Schrodinger Picture; Represnting Transformations in Bosonic Quantum Field Theory; Two-Dimensional Conformal Transformations, Schrodinger picture representation, Fock space representation, Inequivalent Schrodinger picture representations; Discussion, Self-Dual and Other Models; Field Theory in de Sitter Space. Fermionic Quantum Field Theories: Schroedinger Picture; Schrodinger Picture Representation for Two-Dimensional; Conformal Transformations; Fock Space Dynamics in the Schrodinger Picture; Fock Space Evaluation of Anomalous Current and Conformal Commutators
Ionization in a quantized electromagnetic field
International Nuclear Information System (INIS)
Gonoskov, I. A.; Vugalter, G. A.; Mironov, V. A.
2007-01-01
An analytical expression for a matrix element of the transition from a bound state of an electron in an atom to continuum states is obtained by solving the problem of interaction of the electron with a quantized electromagnetic field. This expression is used to derive formulas for the photoelectron spectrum and the rate of ionization of the simplest model atomic system upon absorption of an arbitrary number of photons. The expressions derived are analyzed and compared with the corresponding relationships obtained via other approaches. It is demonstrated that there are differences as compared to the case of the classical field. In particular, the photoelectron spectrum exhibits dips due to the destructive interference of the transition amplitudes in the quantized electromagnetic field
Stochastic quantization and mean field approximation
International Nuclear Information System (INIS)
Jengo, R.; Parga, N.
1983-09-01
In the context of the stochastic quantization we propose factorized approximate solutions for the Fokker-Planck equation for the XY and Zsub(N) spin systems in D dimensions. The resulting differential equation for a factor can be solved and it is found to give in the limit of t→infinity the mean field or, in the more general case, the Bethe-Peierls approximation. (author)
The FBI wavelet/scalar quantization standard for gray-scale fingerprint image compression
Energy Technology Data Exchange (ETDEWEB)
Bradley, J.N.; Brislawn, C.M. [Los Alamos National Lab., NM (United States); Hopper, T. [Federal Bureau of Investigation, Washington, DC (United States)
1993-05-01
The FBI has recently adopted a standard for the compression of digitized 8-bit gray-scale fingerprint images. The standard is based on scalar quantization of a 64-subband discrete wavelet transform decomposition of the images, followed by Huffman coding. Novel features of the algorithm include the use of symmetric boundary conditions for transforming finite-length signals and a subband decomposition tailored for fingerprint images scanned at 500 dpi. The standard is intended for use in conjunction with ANSI/NBS-CLS 1-1993, American National Standard Data Format for the Interchange of Fingerprint Information, and the FBI`s Integrated Automated Fingerprint Identification System.
The FBI wavelet/scalar quantization standard for gray-scale fingerprint image compression
Energy Technology Data Exchange (ETDEWEB)
Bradley, J.N.; Brislawn, C.M. (Los Alamos National Lab., NM (United States)); Hopper, T. (Federal Bureau of Investigation, Washington, DC (United States))
1993-01-01
The FBI has recently adopted a standard for the compression of digitized 8-bit gray-scale fingerprint images. The standard is based on scalar quantization of a 64-subband discrete wavelet transform decomposition of the images, followed by Huffman coding. Novel features of the algorithm include the use of symmetric boundary conditions for transforming finite-length signals and a subband decomposition tailored for fingerprint images scanned at 500 dpi. The standard is intended for use in conjunction with ANSI/NBS-CLS 1-1993, American National Standard Data Format for the Interchange of Fingerprint Information, and the FBI's Integrated Automated Fingerprint Identification System.
Scalar field dark matter in hybrid approach
Friedrich, Pavel; Prokopec, Tomislav
2017-01-01
We develop a hybrid formalism suitable for modeling scalar field dark matter, in which the phase-space distribution associated to the real scalar field is modeled by statistical equal-time two-point functions and gravity is treated by two stochastic gravitational fields in the longitudinal gauge (in
On a gauge theory of the self-dual field and its quantization
International Nuclear Information System (INIS)
Srivastava, P.P.
1990-01-01
A gauge theory of self-dual fields is constructed by adding a Wess-Zumino term to the recently studied formulation based on a second-order scalar field lagrangian carrying with it an auxiliary vector field to take care of the self-duality constraint in a linear fashion. The two versions are quantized using the BRST formulation following the BFV procedure. No violation of microcausality occurs and the action of the ordinary scalar field may not be written as the sum of the actions of the self- and anti-self-dual fields. (orig.)
Massless scalar field in de Sitter spacetime: unitary quantum time evolution
International Nuclear Information System (INIS)
Cortez, Jerónimo; Blas, Daniel Martín-de; Marugán, Guillermo A Mena; Velhinho, José M
2013-01-01
We prove that, under the standard conformal scaling, a free scalar field in de Sitter spacetime admits an O(4)-invariant Fock quantization such that time evolution is unitarily implemented. Since this applies in particular to the massless case, this result disproves previous claims in the literature. We discuss the relationship between this quantization with unitary dynamics and the family of O(4)-invariant Hadamard states given by Allen and Folacci, as well as with the Bunch–Davies vacuum. (paper)
A note on perfect scalar fields
International Nuclear Information System (INIS)
Unnikrishnan, Sanil; Sriramkumar, L.
2010-01-01
We derive a condition on the Lagrangian density describing a generic, single, noncanonical scalar field, by demanding that the intrinsic, nonadiabatic pressure perturbation associated with the scalar field vanishes identically. Based on the analogy with perfect fluids, we refer to such fields as perfect scalar fields. It is common knowledge that models that depend only on the kinetic energy of the scalar field (often referred to as pure kinetic models) possess no nonadiabatic pressure perturbation. While we are able to construct models that seemingly depend on the scalar field and also do not contain any nonadiabatic pressure perturbation, we find that all such models that we construct allow a redefinition of the field under which they reduce to pure kinetic models. We show that, if a perfect scalar field drives inflation, then, in such situations, the first slow roll parameter will always be a monotonically decreasing function of time. We point out that this behavior implies that these scalar fields cannot lead to features in the inflationary, scalar perturbation spectrum.
Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
International Nuclear Information System (INIS)
Singh, Parampreet; Wilson-Ewing, Edward
2014-01-01
We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed Friedmann–Lemaître–Robertson–Walker cosmology, we find that using open holonomies of the extrinsic curvature, which due to gauge-fixing can be treated as a connection, leads to the same quantum geometry effects that are found in spatially flat cosmologies. More specifically, in contrast to the quantization based on open holonomies of the Ashtekar–Barbero connection, the expansion and shear scalars in the effective theories of the Bianchi type II and Bianchi type IX models have upper bounds, and these are in exact agreement with the bounds found in the effective theories of the Friedmann–Lemaître–Robertson–Walker and Bianchi type I models in loop quantum cosmology. We also comment on some ambiguities present in the definition of inverse triad operators and their role. (paper)
Quantization ambiguities and bounds on geometric scalars in anisotropic loop quantum cosmology
Singh, Parampreet; Wilson-Ewing, Edward
2014-02-01
We study quantization ambiguities in loop quantum cosmology that arise for space-times with non-zero spatial curvature and anisotropies. Motivated by lessons from different possible loop quantizations of the closed Friedmann-Lemaître-Robertson-Walker cosmology, we find that using open holonomies of the extrinsic curvature, which due to gauge-fixing can be treated as a connection, leads to the same quantum geometry effects that are found in spatially flat cosmologies. More specifically, in contrast to the quantization based on open holonomies of the Ashtekar-Barbero connection, the expansion and shear scalars in the effective theories of the Bianchi type II and Bianchi type IX models have upper bounds, and these are in exact agreement with the bounds found in the effective theories of the Friedmann-Lemaître-Robertson-Walker and Bianchi type I models in loop quantum cosmology. We also comment on some ambiguities present in the definition of inverse triad operators and their role.
Scalar field mass in generalized gravity
International Nuclear Information System (INIS)
Faraoni, Valerio
2009-01-01
The notions of mass and range of a Brans-Dicke-like scalar field in scalar-tensor and f(R) gravity are subject to an ambiguity that hides a potential trap. We spell out this ambiguity and identify a physically meaningful and practical definition for these quantities. This is relevant when giving a mass to this scalar in order to circumvent experimental limits on the PPN parameters coming from solar system experiments.
Discrete phase space - II: The second quantization of free relativistic wave fields
International Nuclear Information System (INIS)
Das, A.
2010-01-01
The Klein-Gordon equation, the Maxwell equation, and the Dirac equation are presented as partial difference equations in the eight-dimensional covariant discrete phase space. These equations are also furnished as difference-differential equations in the arena of discrete phase space and continuous time. The scalar field and electromagnetic fields are quantized with commutation relations. The spin-1/2 field is quantized with anti-commutation relations. Moreover, the total momentum, energy and charge of these free relativisitic quantized fields in the discrete phase space and continuous time are computed exactly. The results agree completely with those computed from the relativisitic fields defined on the space-time continuum. (author)
Remarks on the quantization of conformal fields
International Nuclear Information System (INIS)
Bakas, I.
1988-01-01
The quantization of a general (b,c) system in two dimensions is formulated in terms of an infinite hierarchy of modules for the Virasoro algebra that interpolate between the space of classical conformal fields of weight j and the Dirac sea of semi-infinite forms. This provides a natural framework in which to study the relation between algebraic geometry and representations of the Virasoro algebra with central charge c j = -2(6j 2 -6j+1). The importance of the construction is discussed in the context of string theory. (orig.)
Anomalous coupling of scalars to gauge fields
Energy Technology Data Exchange (ETDEWEB)
Brax, Philippe [CEA, IPhT, CNRS, URA 2306, Gif-sur-Yvette (France). Inst. de Physique Theorique; Burrage, Clare [Geneve Univ. (Switzerland). Dept. de Physique Theorique; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Davis, Anne-Christine [Centre for Mathematical Sciences, Cambridge (United Kingdom). Dept. of Applied Mathematics and Theoretical Physics; Seery, David [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy; Weltman, Amanda [Cape Town Univ., Rondebosch (South Africa). Astronomy, Cosmology and Gravity Centre
2010-10-15
We study the transformation properties of a scalar-tensor theory, coupled to fermions, under the Weyl rescaling associated with a transition from the Jordan to the Einstein frame. We give a simple derivation of the corresponding modification to the gauge couplings. After changing frames, this gives rise to a direct coupling between the scalar and the gauge fields. (orig.)
Anomalous coupling of scalars to gauge fields
International Nuclear Information System (INIS)
Brax, Philippe; Davis, Anne-Christine; Seery, David; Weltman, Amanda
2010-10-01
We study the transformation properties of a scalar-tensor theory, coupled to fermions, under the Weyl rescaling associated with a transition from the Jordan to the Einstein frame. We give a simple derivation of the corresponding modification to the gauge couplings. After changing frames, this gives rise to a direct coupling between the scalar and the gauge fields. (orig.)
On quantization of the electromagnetic field in radiation gauge
International Nuclear Information System (INIS)
Burzynski, A.
1982-01-01
This paper contains a detailed description of quantization of the electromagnetic field (in radiation gauge) and quantization of some basic physical variables connected with radiation field as energy, momentum and spin. The dynamics of the free quantum radiation field and the field interacting with external classical sources is described. The canonical formalism is not used explicity. (author)
Fedosov quantization and perturbative quantum field theory
Energy Technology Data Exchange (ETDEWEB)
Collini, Giovanni
2016-12-12
Fedosov has described a geometro-algebraic method to construct in a canonical way a deformation of the Poisson algebra associated with a finite-dimensional symplectic manifold (''phase space''). His algorithm gives a non-commutative, but associative, product (a so-called ''star-product'') between smooth phase space functions parameterized by Planck's constant ℎ, which is treated as a deformation parameter. In the limit as ℎ goes to zero, the star product commutator goes to ℎ times the Poisson bracket, so in this sense his method provides a quantization of the algebra of classical observables. In this work, a generalization of Fedosov's method is developed which applies to the infinite-dimensional symplectic ''manifolds'' that occur in Lagrangian field theories. We show that the procedure remains mathematically well-defined, and we explain the relationship of the method to more standard perturbative quantization schemes in quantum field theory.
Enhanced quantization particles, fields and gravity
Klauder, John R
2015-01-01
This pioneering book addresses the question: Are the standard procedures of canonical quantization fully satisfactory, or is there more to learn about assigning a proper quantum system to a given classical system? As shown in this book, the answer to this question is: The standard procedures of canonical quantization are not the whole story! This book offers alternative quantization procedures that complete the story of quantization. The initial chapters are designed to present the new procedures in a clear and simple manner for general readers. As is necessary, systems that exhibit acceptable results with conventional quantization lead to the same results when the new procedures are used for them. However, later chapters examine selected models that lead to unacceptable results when quantized conventionally. Fortunately, these same models lead to acceptable results when the new quantization procedures are used.
On the general theory of quantized fields
International Nuclear Information System (INIS)
Fredenhagen, K.
1991-10-01
In my lecture I describe the present stage of the general theory of quantized fields on the example of 5 subjects. They are ordered in the direction from large to small distances. The first one is the by now classical problem of the structure of superselection sectors. It involves the behavior of the theory at spacelike infinity and is directly connected with particle statistics and internal symmetries. It has become popular in recent years by the discovery of a lot of nontrivial models in 2d conformal-field theory, by connections to integrable models and critical behavior in statistical mechanics and by the relations to the Jones' theory of subfactors in von Neumann algebras and to the corresponding geometrical objects (braids, knots, 3d manifolds, ...). At large timelike distances the by far most important feature of quantum field theory is the particle structure. This will be the second subject of my lecture. It follows the technically most involved part which is concerned with the behavior at finite distances. Two aspets, nuclearity which emphasizes the finite density of states in phase space, and the modular structure which relies on the infinite number of degrees of freedom present even locally, and their mutual relations will be treated. The next point, involving the structure at infinitesimal distances, is the connection between the Haag-Kastler framework of algebras of local and the framework of Wightman fields. Finally, problems in approaches to quantum gravity will be discussed, as far as they are accessible by the methods of the general theory of quantized fields. (orig.)
Exotic Material as Interactions Between Scalar Fields
Directory of Open Access Journals (Sweden)
Robertson G. A.
2015-10-01
Full Text Available Many theoretical papers refer to the need to create exotic materials with average negative energies for the formation of space propulsion anomalies such as “wormholes” and “warp drives”. However, little hope is given for the existence of such material to resolve its creation for such use. From the standpoint that non-minimally coupled scalar fields to gravity appear to be the current direction mathematically. It is proposed that exotic material is really scalar field interactions. Within this paper the Ginzburg- Landau (GL scalar fields associated with superconductor junctions is investigated as a source for negative vacuum energy fluctuations, which could be used to study the interactions among energy fluctuations, cosmological scalar (i. e., Higgs fields, and gravity.
Exotic Material as Interactions Between Scalar Fields
Directory of Open Access Journals (Sweden)
Robertson G. A.
2006-04-01
Full Text Available Many theoretical papers refer to the need to create exotic materials with average negative energies for the formation of space propulsion anomalies such as "wormholes" and "warp drives". However, little hope is given for the existence of such material to resolve its creation for such use. From the standpoint that non-minimally coupled scalar fields to gravity appear to be the current direction mathematically. It is proposed that exotic material is really scalar field interactions. Within this paper the Ginzburg-Landau (GL scalar fields associated with superconductor junctions isinvestigated as a source for negative vacuum energy fluctuations, which could be used to study the interactions among energyfluctuations, cosmological scalar (i.e., Higgs fields, and gravity.
Oscillating scalar fields in extended quintessence
Li, Dan; Pi, Shi; Scherrer, Robert J.
2018-01-01
We study a rapidly oscillating scalar field with potential V (ϕ )=k |ϕ |n nonminimally coupled to the Ricci scalar R via a term of the form (1 -8 π G0ξ ϕ2)R in the action. In the weak coupling limit, we calculate the effect of the nonminimal coupling on the time-averaged equation of state parameter γ =(p +ρ )/ρ . The change in ⟨γ ⟩ is always negative for n ≥2 and always positive for n change to be infinitesimally small at the present time whenever the scalar field dominates the expansion, but constraints in the early universe are not as stringent. The rapid oscillation induced in G also produces an additional contribution to the Friedman equation that behaves like an effective energy density with a stiff equation of state, but we show that, under reasonable assumptions, this effective energy density is always smaller than the density of the scalar field itself.
Canonical quantization of the Proca field in the Rindler wedge
International Nuclear Information System (INIS)
Castineiras, Jorge; Correa, Emerson Benedito Sousa; Crispino, Luis Carlos Bassalo; Matsas, George Emanuel Avraam
2009-01-01
Full text. We perform the canonical quantization of a massive vector field in Rindler spacetime. We pay special attention to the zero frequency modes of the Proca field because these are the modes that interact with structureless sources which are static in the Rindler spacetime. Our motivation is the computation of the total response of a static source with some fixed proper acceleration a 0 in Rindler spacetime interacting with the zero energy massive vector particle of the Fulling-Davies-Unruh (FDU) thermal bath and compare it with the response of a static source with the same proper acceleration a 0 outside a Schwarzschild black hole interacting with the massive vector particles of the Hawking thermal radiation. Surprisingly, as it was already shown in a resent article, these responses would be identical if a massless scalar field is consider instead of the massive vector field, the field outside the Schwarzschild black hole is supposed to be in the Unruh vacuum and the source proper acceleration is the same in both cases. This came as a surprise because structureless static sources can only interact with zero-frequency field modes. Such modes can probe the global geometry of spacetime and are accordingly quite different in Schwarzschild spacetime and in the Rindler wedge. (author)
Perturbation theory for quantized string fields
International Nuclear Information System (INIS)
Thorn, C.B.; Florida Univ., Gainesville
1987-01-01
We discuss the problem of gauge fixing in string field theory. We show that BRST invariance requires the gauge-fixed action to contain terms cubic in the ghost... of ghost of ghost fields. The final BRST invariant gauge-fixed action for the gauge b 0 A=0 is extremely simple: with the proper interpretation (as given in this article), it is essentially the one anticipated earlier in the work of Giddings, Martinec, and Witten in their analysis of the BRST invariant world-sheet approach to string theory. We derive the Feynman rules from this action and explain in detail how the sum over sufaces of the BRST first-quantized string is reproduced. This result depends crucially on the correct assignment for the Grassmann character of the string field and its ghost... of ghost of ghost string fields. If all these fields are unified in a single string field Φ containing all ghost numbers, the requirements is that Φ be uniformly Grassmann odd. Finally, we do some sample calculations which provide some simple checks on our general results. (orig.)
Symmetries of noncommutative scalar field theory
International Nuclear Information System (INIS)
De Goursac, Axel; Wallet, Jean-Christophe
2011-01-01
We investigate symmetries of the scalar field theory with a harmonic term on the Moyal space with the Euclidean scalar product and general symplectic form. The classical action is invariant under the orthogonal group if this group acts also on the symplectic structure. We find that the invariance under the orthogonal group can also be restored at the quantum level by restricting the symplectic structures to a particular orbit.
Constraints and Hamiltonian in light-front quantized field theory
International Nuclear Information System (INIS)
Srivastava, P.P.
1993-01-01
Self-consistent hamiltonian formulation of scalar theory on the null plane is constructed and quantized following the Dirac procedure. The theory contains also constraint equations which would give, if solved, to a nonlocal Hamiltonian. In contrast to the equal-time formulation we obtain a different description of the spontaneous symmetry breaking in the continuum and the symmetry generators are found to annihilate the light-front vacuum. Two examples are given where the procedure cannot be applied self-consistently. The corresponding theories are known to be ill-defined from the equal-time quantization. (author)
Gravitational Field Shielding by Scalar Field and Type II Superconductors
Directory of Open Access Journals (Sweden)
Zhang B. J.
2013-01-01
Full Text Available The gravitational field shielding by scalar field and type II superconductors are theoret- ically investigated. In accord with the well-developed five-dimensional fully covariant Kaluza-Klein theory with a scalar field, which unifies the Einsteinian general relativity and Maxwellian electromagnetic theory, the scalar field cannot only polarize the space as shown previously, but also flatten the space as indicated recently. The polariza- tion of space decreases the electromagnetic field by increasing the equivalent vacuum permittivity constant, while the flattening of space decreases the gravitational field by decreasing the equivalent gravitational constant. In other words, the scalar field can be also employed to shield the gravitational field. A strong scalar field significantly shield the gravitational field by largely decreasing the equivalent gravitational constant. According to the theory of gravitational field shielding by scalar field, the weight loss experimentally detected for a sample near a rotating ceramic disk at very low tempera- ture can be explained as the shielding of the Earth gravitational field by the Ginzburg- Landau scalar field, which is produced by the type II superconductors. The significant shielding of gravitational field by scalar field produced by superconductors may lead to a new spaceflight technology in future.
Kundt spacetimes minimally coupled to scalar field
Energy Technology Data Exchange (ETDEWEB)
Tahamtan, T. [Charles University, Institute of Theoretical Physics, Faculty of Mathematics and Physics, Prague 8 (Czech Republic); Astronomical Institute, Czech Academy of Sciences, Prague (Czech Republic); Svitek, O. [Charles University, Institute of Theoretical Physics, Faculty of Mathematics and Physics, Prague 8 (Czech Republic)
2017-06-15
We derive an exact solution belonging to the Kundt class of spacetimes both with and without a cosmological constant that are minimally coupled to a free massless scalar field. We show the algebraic type of these solutions and give interpretation of the results. Subsequently, we look for solutions additionally containing an electromagnetic field satisfying nonlinear field equations. (orig.)
Can dark matter be a scalar field?
Energy Technology Data Exchange (ETDEWEB)
Jesus, J.F.; Malatrasi, J.L.G. [Universidade Estadual Paulista ' Júlio de Mesquita Filho' , Campus Experimental de Itapeva—R. Geraldo Alckmin, 519, Itapeva, SP (Brazil); Pereira, S.H. [Universidade Estadual Paulista ' Júlio de Mesquita Filho' , Departamento de Física e Química, Campus de Guaratinguetá, Av. Dr. Ariberto Pereira da Cunha, 333, 12516-410—Guaratinguetá, SP (Brazil); Andrade-Oliveira, F., E-mail: jfjesus@itapeva.unesp.br, E-mail: shpereira@gmail.com, E-mail: malatrasi440@gmail.com, E-mail: felipe.oliveira@port.ac.uk [Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, PO1 3FX, Portsmouth (United Kingdom)
2016-08-01
In this paper we study a real scalar field as a possible candidate to explain the dark matter in the universe. In the context of a free scalar field with quadratic potential, we have used Union 2.1 SN Ia observational data jointly with a Planck prior over the dark matter density parameter to set a lower limit on the dark matter mass as m ≥0.12 H {sub 0}{sup -1} eV ( c = h-bar =1). For the recent value of the Hubble constant indicated by the Hubble Space Telescope, namely H {sub 0}=73±1.8 km s{sup -1}Mpc{sup -1}, this leads to m ≥1.56×10{sup -33} eV at 99.7% c.l. Such value is much smaller than m ∼ 10{sup -22} eV previously estimated for some models. Nevertheless, it is still in agreement with them once we have not found evidences for a upper limit on the scalar field dark matter mass from SN Ia analysis. In practice, it confirms free real scalar field as a viable candidate for dark matter in agreement with previous studies in the context of density perturbations, which include scalar field self interaction.
Quantization of fermions in external soliton fields and index calculation
International Nuclear Information System (INIS)
Grosse, H.
1986-01-01
We review recent results on the quantization of fermions in external fields, discuss equivalent and inequivalent representations of the canonical anticommutation relations, indicate how the requirement of implementability of gauge transformations leads to quantization conditions, determine the algebra of charges, identify the Schwinger term and remark finally how one may calculate a ground state charge. (Author)
Scalar and electromagnetic fields in the Kazner metric. Interaction as a mechanism of isotronization
International Nuclear Information System (INIS)
Krechet, V.G.; Shikin, G.N.
1981-01-01
Within the framework of the Willer-de Vitt superspatial quantization the quantum anisotropic cosmological model with interacting, scalar and electromagnetic fields is considered. It is shown that as a result of direct interaction of the scalar and electromagnetic fields isotropization of the model occurs as in the classical case. While comparing the classical and quantum approaches the conclusion is made that in the quantum approach there are states without initial singularity, that fails in the classical approach; both in the quantum and classical approaches there is isotropization of evolution of the interacting field system (in the quantum approach in α, and β), and in both approaches this process is a consequence of direct interaction of the scalar and electromagnetic fields; in the quantum approach, unlike the classical one, there exists isotropization of the considered model at an infinite growth of the scalar field [ru
Anisotropic scalar field with cosmological time
International Nuclear Information System (INIS)
Kleber, A.; Teixeira, A.F.F.
1978-04-01
A static, nonsingular, plane-symmetric scalar field of long range is considered under the general relativity, and a one-parametric class of exact solutions with cosmological time is obtained, in harmonic coordinates. In the absence of any material source, the gravitation originated by the pure scalar field can be studied in detail. A velocity-dependent acceleration field is found, acting attractively on the component of the velocity normal to the plane of symmetry, and repulsively on the component parallel to that plane. Particles at rest are insensitive to the gravitation, although the time component of the energy momentum tensor is point dependent and positive definite
Exploring extra dimensions with scalar fields
Brown, Katherine; Mathur, Harsh; Verostek, Mike
2018-05-01
This paper provides a pedagogical introduction to the physics of extra dimensions by examining the behavior of scalar fields in three landmark models: the ADD, Randall-Sundrum, and DGP spacetimes. Results of this analysis provide qualitative insights into the corresponding behavior of gravitational fields and elementary particles in each of these models. In these "brane world" models, the familiar four dimensional spacetime of everyday experience is called the brane and is a slice through a higher dimensional spacetime called the bulk. The particles and fields of the standard model are assumed to be confined to the brane, while gravitational fields are assumed to propagate in the bulk. For all three spacetimes, we calculate the spectrum of propagating scalar wave modes and the scalar field produced by a static point source located on the brane. For the ADD and Randall-Sundrum models, at large distances, the field looks like that of a point source in four spacetime dimensions, but at short distances, it crosses over to a form appropriate to the higher dimensional spacetime. For the DGP model, the field has the higher dimensional form at long distances rather than short. The behavior of these scalar fields, derived using only undergraduate level mathematics, closely mirror the results that one would obtain by performing the far more difficult task of analyzing the behavior of gravitational fields in these spacetimes.
Gravitational peculiarities of a scalar field
International Nuclear Information System (INIS)
Kleber, A.; Fonseca Teixeira, A.F. da
1979-11-01
The zero-adjoint of a time-static Ricci-flat solution to Einstein's field equations is investigated. It represents a spacetime curved solely by a massless scalar field. The cylindrical symmetry is assumed to permit both planar and non-planar geodetic motions. Unusual, velocity-dependent gravitational features are encountered from these geodesics. (Author) [pt
Astrophysical constraints on scalar field models
International Nuclear Information System (INIS)
Bertolami, O.; Paramos, J.
2005-01-01
We use stellar structure dynamics arguments to extract bounds on the relevant parameters of two scalar field models: the putative scalar field mediator of a fifth force with a Yukawa potential and the new variable mass particle models. We also analyze the impact of a constant solar inbound acceleration, such as the one reported by the Pioneer anomaly, on stellar astrophysics. We consider the polytropic gas model to estimate the effect of these models on the hydrostatic equilibrium equation and fundamental quantities such as the central temperature. The current bound on the solar luminosity is used to constrain the relevant parameters of each model
Scalar fields: at the threshold of astrophysics
Energy Technology Data Exchange (ETDEWEB)
Guzman, F S [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo. Edificio C-3, Cd. Universitaria, A. P. 2-82, 58040 Morelia, Michoacan (Mexico)
2007-11-15
In this manuscript the potential existence of self-gravitating complex scalar field configurations is explored. Stable boson stars are presented as potential black hole candidates, and the strengths and weaknesses of such idea are described. On the other hand, Newtonian boson systems are also studied because they are the bricks of the structure within the scalar field dark matter model or the Bose condensate dark matter; the collapse of density fluctuations is described; also the interaction between two structures is shown to allow solitonic behavior, which in turn allows the formation of ripples of dark matter. The processes related to potential observations are also discussed.
New approach to the problem of gauge field quantization
International Nuclear Information System (INIS)
Skachkov, N.B.; Shevchenko, O.Yu.
1987-01-01
A new scheme of calibration field quantization containing considerable change of the procedure of calibration conditions application on field variables is suggested. The above approach is based on a proved theorem on the subordination of fields to the additional Lorenz condition when applying a wide class of initial calibration conditions on these fields. This condition has the sense of the secondary bond, which must be included in the system of bonds during field quantization. The fact of secondary bond presence in the form of Lorenz condition was not earlier considered in literature and used in quantization. Due to this, the report suggests modification of all existing methods of field quantization: according to Dirac-Bergman, covariant approach using an indefinite metric and the method of functional integration
Anisotropic inflation from charged scalar fields
International Nuclear Information System (INIS)
Emami, Razieh; Firouzjahi, Hassan; Movahed, S.M. Sadegh; Zarei, Moslem
2011-01-01
We consider models of inflation with U(1) gauge fields and charged scalar fields including symmetry breaking potential, chaotic inflation and hybrid inflation. We show that there exist attractor solutions where the anisotropies produced during inflation becomes comparable to the slow-roll parameters. In the models where the inflaton field is a charged scalar field the gauge field becomes highly oscillatory at the end of inflation ending inflation quickly. Furthermore, in charged hybrid inflation the onset of waterfall phase transition at the end of inflation is affected significantly by the evolution of the background gauge field. Rapid oscillations of the gauge field and its coupling to inflaton can have interesting effects on preheating and non-Gaussianities
Creation of particles in the gravitational field and the boundary conditions for quantized fields
International Nuclear Information System (INIS)
Khrustalev, O.A.; Silaev, P.K.
1995-01-01
We prove, that if one impose the linear constraints on the quantized fields that satisfy different boundary conditions, it can leads to such a transformation between creation-annihilation operators, that corresponds to particle creation. We also prove, that the correspondence between field, quantized in Minkowski space and the field, quantized in Rindler space has Rindler space can't be observed. 7 refs
A physically motivated quantization of the electromagnetic field
International Nuclear Information System (INIS)
Bennett, Robert; Barlow, Thomas M; Beige, Almut
2016-01-01
The notion that the electromagnetic field is quantized is usually inferred from observations such as the photoelectric effect and the black-body spectrum. However accounts of the quantization of this field are usually mathematically motivated and begin by introducing a vector potential, followed by the imposition of a gauge that allows the manipulation of the solutions of Maxwell’s equations into a form that is amenable for the machinery of canonical quantization. By contrast, here we quantize the electromagnetic field in a less mathematically and more physically motivated way. Starting from a direct description of what one sees in experiments, we show that the usual expressions of the electric and magnetic field observables follow from Heisenberg’s equation of motion. In our treatment, there is no need to invoke the vector potential in a specific gauge and we avoid the commonly used notion of a fictitious cavity that applies boundary conditions to the field. (paper)
Gravitational waves from scalar field accretion
International Nuclear Information System (INIS)
Nunez, Dario; Degollado, Juan Carlos; Moreno, Claudia
2011-01-01
Our aim in this work is to outline some physical consequences of the interaction between black holes and scalar field halos in terms of gravitational waves. In doing so, the black hole is taken as a static and spherically symmetric gravitational source, i.e. the Schwarzschild black hole, and we work within the test field approximation, considering that the scalar field lives in the curved space-time outside the black hole. We focused on the emission of gravitational waves when the black hole is perturbed by the surrounding scalar field matter. The symmetries of the space-time and the simplicity of the matter source allow, by means of a spherical harmonic decomposition, to study the problem by means of a one-dimensional description. Some properties of such gravitational waves are discussed as a function of the parameters of the infalling scalar field, and allow us to make the conjecture that the gravitational waves carry information on the type of matter that generated them.
Minimally coupled scalar field cosmology in anisotropic ...
Indian Academy of Sciences (India)
2017-01-03
Jan 3, 2017 ... So far, a large class of scalar field dark energy mod- els have been ... gains a lot of interest, under the light of the recently announced Planck Probe ...... Figure 1. wm vs. t for c2 = 1, V0 = 1 and some values of λ and α. Figure 2.
Free massless scalar fields in two dimensions
International Nuclear Information System (INIS)
Hadjiivanov, L.K.
1980-01-01
A common Fock space for two free massless scalar fields, nonlocal with respect to each other, is constructed. The operators corresponding to the two formal charges are correctly defined and it is shown that they generate translationally invariant states from the vacuum
Reconstructing bidimensional scalar field theory models
International Nuclear Information System (INIS)
Flores, Gabriel H.; Svaiter, N.F.
2001-07-01
In this paper we review how to reconstruct scalar field theories in two dimensional spacetime starting from solvable Scrodinger equations. Theree different Schrodinger potentials are analyzed. We obtained two new models starting from the Morse and Scarf II hyperbolic potencials, the U (θ) θ 2 In 2 (θ 2 ) model and U (θ) = θ 2 cos 2 (In(θ 2 )) model respectively. (author)
Scalar fields nonminimally coupled to pp waves
International Nuclear Information System (INIS)
Ayon-Beato, Eloy; Hassaiene, Mokhtar
2005-01-01
Here, we report pp waves configurations of three-dimensional gravity for which a scalar field nonminimally coupled to them acts as a source. In absence of self-interaction the solutions are gravitational plane waves with a profile fixed in terms of the scalar wave. In the self-interacting case, only power-law potentials parameterized by the nonminimal coupling constant are allowed by the field equations. In contrast with the free case the self-interacting scalar field does not behave like a wave since it depends only on the wave-front coordinate. We address the same problem when gravitation is governed by topologically massive gravity and the source is a free scalar field. From the pp waves derived in this case, we obtain at the zero topological mass limit, new pp waves solutions of conformal gravity for any arbitrary value of the nonminimal coupling parameter. Finally, we extend these solutions to the self-interacting case of conformal gravity
Quantized Dirac field interacting with a classical Maxwell field
International Nuclear Information System (INIS)
Kolsrud, M.
1987-10-01
The S operator for the quantized and the s matrix for the unquantized Dirac field, both fields interacting with an unquantized Maxwell field, are shown to be related in the following way: S=exp(-ic†kc) and s=exp(-ik). Here c is the column matrix of the particle operators, and k is a Hermitian matrix. With splitting of c into an electron and a positron part, a corresponding factorization of S is performed. Exact expressions for the probability amplitude for various electron and/or positron processes are then obtained
Propagators for a scalar field in some Bianchi-type I universe
International Nuclear Information System (INIS)
Nariai, Hidekazu.
1976-05-01
As a sequel to previous papers on bi-scalar propagators in the Friedmann universes and a special Kasner universe (whose underlying space-time is flat), their counterparts for a massless scalar field in some Bianchi-type I universe (which is intrinsically curved and anisotropic) are derived by means of Hadamard's procedure and ours, the latter of which becomes inevitable in the realm of quantized field. The retarded propagator thus obtained is applied to the generation of the scalar field from a point source and a spatially uniform distribution of sources, respectively. In the former case, the luminosity formula for a point source is derived, which is an anisotropic version of Robertson's formula in the Friedmann universes. In the latter case, it is shown that the scalar field may behave as either a perfect fluid obeying Zel'dovich's hardest equation of state or an imperfect fluid whose equation of state violates the energy condition. Implication of the above three works on the occasion of quantizing the scalar field is also touched upon. (auth.)
Scalar fields in black hole spacetimes
Thuestad, Izak; Khanna, Gaurav; Price, Richard H.
2017-07-01
The time evolution of matter fields in black hole exterior spacetimes is a well-studied subject, spanning several decades of research. However, the behavior of fields in the black hole interior spacetime has only relatively recently begun receiving some attention from the research community. In this paper, we numerically study the late-time evolution of scalar fields in both Schwarzschild and Kerr spacetimes, including the black hole interior. We recover the expected late-time power-law "tails" on the exterior (null infinity, timelike infinity, and the horizon). In the interior region, we find an interesting oscillatory behavior that is characterized by the multipole index ℓ of the scalar field. In addition, we also study the extremal Kerr case and find strong indications of an instability developing at the horizon.
The Rainich problem for coupled gravitational and scalar meson fields
International Nuclear Information System (INIS)
Hyde, J.M.
1975-01-01
The equations of the coupled gravitational and scalar meson fields in general relativity are considered. It is shown that the wave equation for the scalar meson field which is usually specified explicitly in addition to the Einstein field equations is implied by Einstein's equations. Using this result it is then shown how the scalar field may be eliminated explicitly from the field equations, thus solving the Rainich problem for the coupled gravitational and scalar meson fields. (author) [fr
From the geometric quantization to conformal field theory
International Nuclear Information System (INIS)
Alekseev, A.; Shatashvili, S.
1990-01-01
Investigation of 2d conformal field theory in terms of geometric quantization is given. We quantize the so-called model space of the compact Lie group, Virasoro group and Kac-Moody group. In particular, we give a geometrical interpretation of the Virasoro discrete series and explain that this type of geometric quantization reproduces the chiral part of CFT (minimal models, 2d-gravity, WZNW theory). In the appendix we discuss the relation between classical (constant) r-matrices and this geometrical approach. (orig.)
Modeling quantization effects in field effect transistors
International Nuclear Information System (INIS)
Troger, C.
2001-06-01
Numerical simulation in the field of semiconductor device development advanced to a valuable, cost-effective and flexible facility. The most widely used simulators are based on classical models, as they need to satisfy time and memory constraints. To improve the performance of field effect transistors such as MOSFETs and HEMTs these devices are continuously scaled down in their dimensions. Consequently the characteristics of such devices are getting more and more determined by quantum mechanical effects arising from strong transversal fields in the channel. In this work an approach based on a two-dimensional electron gas is used to describe the confinement of the carriers. Quantization is considered in one direction only. For the derivation of a one-dimensional Schroedinger equation in the effective mass framework a non-parabolic correction for the energy dispersion due to Kane is included. For each subband a non-parabolic dispersion relation characterized by subband masses and subband non-parabolicity coefficients is introduced and the parameters are calculated via perturbation theory. The method described in this work has been implemented in a software tool that performs a self-consistent solution of Schroedinger- and Poisson-equation for a one-dimensional cut through a MOS structure or heterostructure. The calculation of the carrier densities is performed assuming Fermi-Dirac statistics. In the case of a MOS structure a metal or a polysilicon gate is considered and an arbitrary gate bulk voltage can be applied. This allows investigating quantum mechanical effects in capacity calculations, to compare the simulated data with measured CV curves and to evaluate the results obtained with a quantum mechanical correction for the classical electron density. The behavior of the defined subband parameters is compared to the value of the mass and the non-parabolicity coefficient from the model due to Kane. Finally the presented characterization of the subbands is applied
Dissipation element analysis of turbulent scalar fields
International Nuclear Information System (INIS)
Wang Lipo; Peters, Norbert
2008-01-01
Dissipation element analysis is a new approach for studying turbulent scalar fields. Gradient trajectories starting from each material point in a scalar field Φ'(x-vector,t) in ascending directions will inevitably reach a maximal and a minimal point. The ensemble of material points sharing the same pair ending points is named a dissipation element. Dissipation elements can be parameterized by the length scale l and the scalar difference Δφ ', which are defined as the straight line connecting the two extremal points and the scalar difference at these points, respectively. The decomposition of a turbulent field into dissipation elements is space-filling. This allows us to reconstruct certain statistical quantities of fine scale turbulence which cannot be obtained otherwise. The marginal probability density function (PDF) of the length scale distribution based on a Poisson random cutting-reconnection process shows satisfactory agreement with the direct numerical simulation (DNS) results. In order to obtain the further information that is needed for the modeling of scalar mixing in turbulence, such as the marginal PDF of the length of elements and all conditional moments as well as their scaling exponents, there is a need to model the joint PDF of l and Δφ ' as well. A compensation-defect model is put forward in this work to show the dependence of Δφ ' on l. The agreement between the model prediction and DNS results is satisfactory, which may provide another explanation of the Kolmogorov scaling and help to improve turbulent mixing models. Furthermore, intermittency and cliff structure can also be related to and explained from the joint PDF.
Linear spin-zero quantum fields in external gravitational and scalar fields
International Nuclear Information System (INIS)
Kay, B.S.
1977-10-01
Mathematically rigorous results are given on the quantization of the covariant Klein-Gordon field with an external stationary scalar interaction in a stationary curved space-time. It is shown how, following Segal, Weinless etc., the problem reduces to finding a ''one-particle structure'' for the corresponding classical system. The main result is an existence theorem for such a one-particle structure for a precisely specified class of stationary space-times. Byproducts of our approach are (1)a discussion of when the equal-time hypersurfaces in a given stationary space-time are Cauchy; (2)a proof that when a one-particle structure exists it is unique a result of general interest for the quantization of linear systems; (3)a modification and extension of the methods of Chernoff [3] for proving the essential self-adjointness of ceratin partial differential operators
Stability of a collapsed scalar field and cosmic censorship
International Nuclear Information System (INIS)
Abe, S.
1988-01-01
The static and asymptotically flat solution to the Einstein-massless-scalar model with spherical symmetry describes the spacetime with a naked singularity when it has a nonvanishing scalar charge. We show that such a solution is unstable against the spherical scalar monopole perturbation. This suggests the validity of the cosmic censorship hypothesis in the spherical collapse of the scalar field
Effect of scalar field mass on gravitating charged scalar solitons and black holes in a cavity
Energy Technology Data Exchange (ETDEWEB)
Ponglertsakul, Supakchai, E-mail: supakchai.p@gmail.com; Winstanley, Elizabeth, E-mail: E.Winstanley@sheffield.ac.uk
2017-01-10
We study soliton and black hole solutions of Einstein charged scalar field theory in cavity. We examine the effect of introducing a scalar field mass on static, spherically symmetric solutions of the field equations. We focus particularly on the spaces of soliton and black hole solutions, as well as studying their stability under linear, spherically symmetric perturbations of the metric, electromagnetic field, and scalar field.
Covariant canonical quantization of fields and Bohmian mechanics
International Nuclear Information System (INIS)
Nikolic, H.
2005-01-01
We propose a manifestly covariant canonical method of field quantization based on the classical De Donder-Weyl covariant canonical formulation of field theory. Owing to covariance, the space and time arguments of fields are treated on an equal footing. To achieve both covariance and consistency with standard non-covariant canonical quantization of fields in Minkowski spacetime, it is necessary to adopt a covariant Bohmian formulation of quantum field theory. A preferred foliation of spacetime emerges dynamically owing to a purely quantum effect. The application to a simple time-reparametrization invariant system and quantum gravity is discussed and compared with the conventional non-covariant Wheeler-DeWitt approach. (orig.)
Electromagnetically induced transparency with quantized fields in optocavity mechanics
International Nuclear Information System (INIS)
Huang Sumei; Agarwal, G. S.
2011-01-01
We report electromagnetically induced transparency (EIT) using quantized fields in optomechanical systems. The weak probe field is a narrowband squeezed field. We present a homodyne detection of EIT in the output quantum field. We find that the EIT dip exists even though the photon number in the squeezed vacuum is at the single-photon level. The EIT with quantized fields can be seen even at temperatures on the order of 100 mK, thus paving the way for using optomechanical systems as memory elements.
Euclidean wormholes with minimally coupled scalar fields
International Nuclear Information System (INIS)
Ruz, Soumendranath; Modak, Bijan; Debnath, Subhra; Sanyal, Abhik Kumar
2013-01-01
A detailed study of quantum and semiclassical Euclidean wormholes for Einstein's theory with a minimally coupled scalar field has been performed for a class of potentials. Massless, constant, massive (quadratic in the scalar field) and inverse (linear) potentials admit the Hawking and Page wormhole boundary condition both in the classically forbidden and allowed regions. An inverse quartic potential has been found to exhibit a semiclassical wormhole configuration. Classical wormholes under a suitable back-reaction leading to a finite radius of the throat, where the strong energy condition is satisfied, have been found for the zero, constant, quadratic and exponential potentials. Treating such classical Euclidean wormholes as an initial condition, a late stage of cosmological evolution has been found to remain unaltered from standard Friedmann cosmology, except for the constant potential which under the back-reaction produces a term like a negative cosmological constant. (paper)
Scalar field cosmologies with inverted potentials
Energy Technology Data Exchange (ETDEWEB)
Boisseau, B.; Giacomini, H. [Université de Tours, Laboratoire de Mathématiques et Physique Théorique, CNRS/UMR 7350, 37200 Tours (France); Polarski, D., E-mail: bruno.boisseau@lmpt.univ-tours.fr, E-mail: hector.giacomini@lmpt.univ-tours.fr, E-mail: david.polarski@umontpellier.fr [Université Montpellier and CNRS, Laboratoire Charles Coulomb, UMR 5221, F-34095 Montpellier (France)
2015-10-01
Regular bouncing solutions in the framework of a scalar-tensor gravity model were found in a recent work. We reconsider the problem in the Einstein frame (EF) in the present work. Singularities arising at the limit of physical viability of the model in the Jordan frame (JF) are either of the Big Bang or of the Big Crunch type in the EF. As a result we obtain integrable scalar field cosmological models in general relativity (GR) with inverted double-well potentials unbounded from below which possess solutions regular in the future, tending to a de Sitter space, and starting with a Big Bang. The existence of the two fixed points for the field dynamics at late times found earlier in the JF becomes transparent in the EF.
Scalar field cosmologies with inverted potentials
International Nuclear Information System (INIS)
Boisseau, B.; Giacomini, H.; Polarski, D.
2015-01-01
Regular bouncing solutions in the framework of a scalar-tensor gravity model were found in a recent work. We reconsider the problem in the Einstein frame (EF) in the present work. Singularities arising at the limit of physical viability of the model in the Jordan frame (JF) are either of the Big Bang or of the Big Crunch type in the EF. As a result we obtain integrable scalar field cosmological models in general relativity (GR) with inverted double-well potentials unbounded from below which possess solutions regular in the future, tending to a de Sitter space, and starting with a Big Bang. The existence of the two fixed points for the field dynamics at late times found earlier in the JF becomes transparent in the EF
Scalar field Green functions on causal sets
International Nuclear Information System (INIS)
Nomaan Ahmed, S; Surya, Sumati; Dowker, Fay
2017-01-01
We examine the validity and scope of Johnston’s models for scalar field retarded Green functions on causal sets in 2 and 4 dimensions. As in the continuum, the massive Green function can be obtained from the massless one, and hence the key task in causal set theory is to first identify the massless Green function. We propose that the 2d model provides a Green function for the massive scalar field on causal sets approximated by any topologically trivial 2-dimensional spacetime. We explicitly demonstrate that this is indeed the case in a Riemann normal neighbourhood. In 4d the model can again be used to provide a Green function for the massive scalar field in a Riemann normal neighbourhood which we compare to Bunch and Parker’s continuum Green function. We find that the same prescription can also be used for de Sitter spacetime and the conformally flat patch of anti-de Sitter spacetime. Our analysis then allows us to suggest a generalisation of Johnston’s model for the Green function for a causal set approximated by 3-dimensional flat spacetime. (paper)
Gaussian processes and constructive scalar field theory
International Nuclear Information System (INIS)
Benfatto, G.; Nicolo, F.
1981-01-01
The last years have seen a very deep progress of constructive euclidean field theory, with many implications in the area of the random fields theory. The authors discuss an approach to super-renormalizable scalar field theories, which puts in particular evidence the connections with the theory of the Gaussian processes associated to the elliptic operators. The paper consists of two parts. Part I treats some problems in the theory of Gaussian processes which arise in the approach to the PHI 3 4 theory. Part II is devoted to the discussion of the ultraviolet stability in the PHI 3 4 theory. (Auth.)
Renormalization group study of scalar field theories
International Nuclear Information System (INIS)
Hasenfratz, A.; Hasenfratz, P.
1986-01-01
An approximate RG equation is derived and studied in scalar quantum field theories in d dimensions. The approximation allows for an infinite number of different couplings in the potential, but excludes interactions containing derivatives. The resulting non-linear partial differential equation can be studied by simple means. Both the gaussian and the non-gaussian fixed points are described qualitatively correctly by the equation. The RG flows in d=4 and the problem of defining an ''effective'' field theory are discussed in detail. (orig.)
The general theory of quantized fields in the 1950s
International Nuclear Information System (INIS)
Wightman, A.S.
1989-01-01
This review describes developments in theoretical particle physics in the 1950s which were important in the race to develop a putative general theory of quantized fields, especially ideas that offered a mathematically rigorous theory. Basic theoretical concepts then available included the Hamiltonian formulation of quantum dynamics, canonical quantization, perturbative renormalization theory and the theory of distributions. Following a description of various important theoretical contributions of this era, the review ends with a summary of the most important contributions of axiomatic field theory to concrete physics applications. (UK)
Group quantization on configuration space: Gauge symmetries and linear fields
International Nuclear Information System (INIS)
Navarro, M.; Aldaya, V.; Calixto, M.
1997-01-01
A new, configuration-space picture of a formalism of group quantization, the GAQ formalism, is presented in the context of a previous algebraic generalization. This presentation serves to make a comprehensive discussion in which other extensions of the formalism, principally to incorporate gauge symmetries, are developed as well. Both images are combined in order to analyze, in a systematic manner and with complete generality, the case of linear fields (Abelian current groups). To illustrate these developments we particularize them for several fields and, in particular, we carry out the quantization of the Abelian Chern endash Simons models over an arbitrary closed surface in detail. copyright 1997 American Institute of Physics
Thermal inflation with a thermal waterfall scalar field coupled to a light spectator scalar field
Dimopoulos, Konstantinos; Lyth, David H.; Rumsey, Arron
2017-05-01
A new model of thermal inflation is introduced, in which the mass of the thermal waterfall field is dependent on a light spectator scalar field. Using the δ N formalism, the "end of inflation" scenario is investigated in order to ascertain whether this model is able to produce the dominant contribution to the primordial curvature perturbation. A multitude of constraints are considered so as to explore the parameter space, with particular emphasis on key observational signatures. For natural values of the parameters, the model is found to yield a sharp prediction for the scalar spectral index and its running, well within the current observational bounds.
Duality property for a hermitian scalar field
International Nuclear Information System (INIS)
Bisognano, J.J.
1975-01-01
A general hermitian scalar Wightman field is considered. On the Hilbert space of physical states ''natural'' domains for certain complex Lorentz transformations are constructed, and a theorem relating these transformations to the TCP symmetry is stated and proved. Under the additional assumption that the field is ''locally'' essentially self-adjoint, duality is considered for the algebras generated by spectral projections of smeared fields. For a class of unbounded regions duality is proved, and for certain bounded regions ''local'' extensions of the algebras are constructed which satisfy duality. The relationship of the arguments presented to the Tomita--Takesaki theory of modular Hilbert algebras is discussed. A separate analysis for the free field is also given. (auth)
Global integrability of cosmological scalar fields
Maciejewski, Andrzej J.; Przybylska, Maria; Stachowiak, Tomasz; Szydłowski, Marek
2008-11-01
We investigate the Liouvillian integrability of Hamiltonian systems describing a universe filled with a scalar field (possibly complex). The tool used is the differential Galois group approach, as introduced by Morales-Ruiz and Ramis. The main result is that the generic systems with minimal coupling are non-integrable, although there still exist some values of parameters for which integrability remains undecided; the conformally coupled systems are only integrable in four known cases. We also draw a connection with the chaos present in such cosmological models, and the issues of the integrability restricted to the real domain.
Global integrability of cosmological scalar fields
International Nuclear Information System (INIS)
Maciejewski, Andrzej J; Przybylska, Maria; Stachowiak, Tomasz; Szydlowski, Marek
2008-01-01
We investigate the Liouvillian integrability of Hamiltonian systems describing a universe filled with a scalar field (possibly complex). The tool used is the differential Galois group approach, as introduced by Morales-Ruiz and Ramis. The main result is that the generic systems with minimal coupling are non-integrable, although there still exist some values of parameters for which integrability remains undecided; the conformally coupled systems are only integrable in four known cases. We also draw a connection with the chaos present in such cosmological models, and the issues of the integrability restricted to the real domain
Boundaries immersed in a scalar quantum field
International Nuclear Information System (INIS)
Actor, A.A.; Bender, I.
1996-01-01
We study the interaction between a scalar quantum field φ(x), and many different boundary configurations constructed from (parallel and orthogonal) thin planar surfaces on which φ(x) is constrained to vanish, or to satisfy Neumann conditions. For most of these boundaries the Casimir problem has not previously been investigated. We calculate the canonical and improved vacuum stress tensors left angle T μv (x) right angle and left angle direct difference μv (x) right angle of φ(x) for each example. From these we obtain the local Casimir forces on all boundary planes. For massless fields, both vacuum stress tensors yield identical attractive local Casimir forces in all Dirichlet examples considered. This desirable outcome is not a priori obvious, given the quite different features of left angle T μv (x) right angle and left angle direct difference μv (x) right angle. For Neumann conditions, left angle T μv (x) right angle and left angle direct difference μv (x) right angle lead to attractive Casimir stresses which are not always the same. We also consider Dirichlet and Neumann boundaries immersed in a common scalar quantum field, and find that these repel. The extensive catalogue of worked examples presented here belongs to a large class of completely solvable Casimir problems. Casimir forces previously unknown are predicted, among them ones which might be measurable. (orig.)
BRS symmetry in stochastic quantization of the gravitational field
International Nuclear Information System (INIS)
Nakazawa, Naohito.
1989-12-01
We study stochastic quantization of gravity in terms of a BRS invariant canonical operator formalism. By introducing artificially canonical momentum variables for the original field variables, a canonical formulation of stochastic quantization is proposed in a sense that the Fokker-Planck hamiltonian is the generator of the fictitious time translation. Then we show that there exists a nilpotent BRS symmetry in an enlarged phase space for gravity (in general, for the first-class constrained systems). The stochastic action of gravity includes explicitly an unique De Witt's type superspace metric which leads to a geometrical interpretation of quantum gravity analogous to nonlinear σ-models. (author)
Force field refinement from NMR scalar couplings
Energy Technology Data Exchange (ETDEWEB)
Huang Jing [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland); Meuwly, Markus, E-mail: m.meuwly@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel (Switzerland)
2012-03-02
Graphical abstract: We show that two classes of H-bonds are sufficient to quantitatively describe scalar NMR coupling constants in small proteins. Highlights: Black-Right-Pointing-Pointer We present force field refinements based on explicit MD simulations using scalar couplings across hydrogen bonds. Black-Right-Pointing-Pointer This leads to {sup h3}J{sub NC{sup }{sup P}{sup r}{sup i}{sup m}{sup e}} couplings to within 0.03 Hz at best compared to experiment. Black-Right-Pointing-Pointer A classification of H-bonds according to secondary structure is not sufficiently robust. Black-Right-Pointing-Pointer Grouping H-bonds into two classes and reparametrization yields an RMSD of 0.07 Hz. Black-Right-Pointing-Pointer This is an improvement of 50. - Abstract: NMR observables contain valuable information about the protein dynamics sampling a high-dimensional potential energy surface. Depending on the observable, the dynamics is sensitive to different time-windows. Scalar coupling constants {sup h3}J{sub NC{sup }{sup P}{sup r}{sup i}{sup m}{sup e}} reflect the pico- to nanosecond motions associated with the intermolecular hydrogen bond network. Including an explicit H-bond in the molecular mechanics with proton transfer (MMPT) potential allows us to reproduce experimentally determined {sup h3}J{sub NC{sup }{sup P}{sup r}{sup i}{sup m}{sup e}} couplings to within 0.02 Hz at best for ubiquitin and protein G. This is based on taking account of the chemically changing environment by grouping the H-bonds into up to seven classes. However, grouping them into two classes already reduces the RMSD between computed and observed {sup h3}J{sub NC{sup }{sup P}{sup r}{sup i}{sup m}{sup e}} couplings by almost 50%. Thus, using ensemble-averaged data with two classes of H-bonds leads to substantially improved scalar couplings from simulations with accurate force fields.
Scalar field dark matter and the Higgs field
Directory of Open Access Journals (Sweden)
O. Bertolami
2016-08-01
Full Text Available We discuss the possibility that dark matter corresponds to an oscillating scalar field coupled to the Higgs boson. We argue that the initial field amplitude should generically be of the order of the Hubble parameter during inflation, as a result of its quasi-de Sitter fluctuations. This implies that such a field may account for the present dark matter abundance for masses in the range 10−6–10−4eV, if the tensor-to-scalar ratio is within the range of planned CMB experiments. We show that such mass values can naturally be obtained through either Planck-suppressed non-renormalizable interactions with the Higgs boson or, alternatively, through renormalizable interactions within the Randall–Sundrum scenario, where the dark matter scalar resides in the bulk of the warped extra-dimension and the Higgs is confined to the infrared brane.
International Nuclear Information System (INIS)
Cheng Hung; Tsai Ercheng
1986-01-01
We give a correspondence formula which equates transition amplitudes in a quantum gauge field theory without ghost fields to those in a quantum theory with the gauge fields covariantly quantized and coupled to ghost fields. (orig.)
International Nuclear Information System (INIS)
Srivastava, Prem P.
1994-01-01
The Dirac procedure is used to construct the Hamiltonian formulation of the scalar field theory on the light-front. The theory is quantized and the mechanism of the spontaneous symmetry breaking in the front form and the instant form dynamics are compared. The phase transition in (φ 4 )2 theory is also discussed and found to be of the second order. (author). 36 refs
Relaxation and kinetics in scalar field theories
International Nuclear Information System (INIS)
Boyanovsky, D.; Lawrie, I.D.; Lee, D.
1996-01-01
A new approach to the dynamics of relaxation and kinetics of thermalization in a scalar field theory is presented that incorporates the relevant time scales through the resummation of hard thermal loops. An alternative derivation of the kinetic equations for the open-quote open-quote quasiparticle close-quote close-quote distribution functions is obtained that allows a clear understanding of the different open-quote open-quote coarse-graining close-quote close-quote approximations usually involved in a kinetic description. This method leads to a systematic perturbative expansion to obtain the kinetic equations including hard thermal loop resummation and to an improvement including renormalization, off-shell effects, and contributions that change chemical equilibrium on short time scales. As a by-product of these methods we establish the equivalence between the relaxation time scale in the linearized equation of motion of the quasiparticles and the thermalization time scale of the quasiparticle distribution function in the open-quote open-quote relaxation time approximation close-quote close-quote including hard thermal loop effects. Hard thermal loop resummation dramatically modifies the scattering rate for long wavelength modes as compared to the usual (semi)classical estimate. Relaxation and kinetics are studied both in the unbroken and broken symmetry phases of the theory. The broken symmetry phase also provides the setting to obtain the contribution to the kinetic equations from processes that involve decay of a heavy scalar into light scalar particles in the medium. copyright 1996 The American Physical Society
Vacuum instability in scalar field theories
International Nuclear Information System (INIS)
McKane, A.J.
1978-09-01
Scalar field theories with an interaction of the form gphisup(N) have no stable vacuum state for some range of values of their coupling constant, g. This thesis reports calculations of vacuum instability in such theories. Using the idea that the tunnelling out of the vacuum state is described by the instanton solutions of the theory, the imaginary part of the vertex functions is calculated for the massless theory in the one-loop approximation, near the dimension dsub(c) = 2N/N-2, where the theory is just renormalisable. The calculation differs from previous treatments in that dimensional regularisation is used to control the ultra-violet divergences of the theory. In this way previous analytic calculations in conformally invariant field theories are extended to the case where the theory is almost conformally invariant, since it is now defined in dsub(c) - epsilon dimensions (epsilon > 0). (author)
Grassmann scalar fields and asymptotic freedom
Energy Technology Data Exchange (ETDEWEB)
Palumbo, F [INFN, Laboratori Nazionali di Frascati, Rome (Italy)
1996-03-01
The authors extend previous results about scalar fields whose Fourier components are even elements of a Grassmann algebra with given index of nilpotency. Their main interest in particle physics is related to the possibility that they describe fermionic composites analogous to the Copper pairs of superconductivity. The authors evaluate the free propagators for arbitrary index of nilpotency and they investigate a {phi}{sup 4} model to one loop. Due to the nature of the integral over even Grassmann fields such as a model exists for repulsive as well as attractive self interaction. In the first case the {beta}-function is equal to that of the ordinary theory, while in the second one the model is asymptotically free. The bare mass has a peculiar dependence on the cutoff, being quadratically decreasing/increasing for attractive/repulsive self interaction.
Massive scalar field evolution in de Sitter
Energy Technology Data Exchange (ETDEWEB)
Markkanen, Tommi [Department of Physics, King’s College London,Strand, London WC2R 2LS (United Kingdom); Rajantie, Arttu [Department of Physics, Imperial College London,London SW7 2AZ (United Kingdom)
2017-01-30
The behaviour of a massive, non-interacting and non-minimally coupled quantised scalar field in an expanding de Sitter background is investigated by solving the field evolution for an arbitrary initial state. In this approach there is no need to choose a vacuum in order to provide a definition for particle states, nor to introduce an explicit ultraviolet regularization. We conclude that the expanding de Sitter space is a stable equilibrium configuration under small perturbations of the initial conditions. Depending on the initial state, the energy density can approach its asymptotic value from above or below, the latter of which implies a violation of the weak energy condition. The backreaction of the quantum corrections can therefore lead to a phase of super-acceleration also in the non-interacting massive case.
Stability of a Noncanonical Scalar Field Model during Cosmological Date
Directory of Open Access Journals (Sweden)
Z. Ossoulian
2016-01-01
Full Text Available Using the noncanonical model of scalar field, the cosmological consequences of a pervasive, self-interacting, homogeneous, and rolling scalar field are studied. In this model, the scalar field potential is “nonlinear” and decreases in magnitude with increasing the value of the scalar field. A special solution of the nonlinear field equations of ϕ that has time dependency as fixed point is obtained. The fixed point relies on the noncanonical term of action and γ-parameter; this parameter appeared in energy density of scalar field redshift. By means of such fixed point the different eigenvalues of the equation of motion will be obtained. In different epochs in the evolution of the Universe for different values of q and n, the potentials as a function of scalar field are attained. The behavior of baryonic perturbations in linear perturbation scenario as a considerable amount of energy density of scalar field at low redshifts prevents the growth of perturbations in the ordinary matter fluid. The energy density in the scalar field is not appreciably perturbed by nonrelativistic gravitational fields, in either the radiation or matter dominant or scalar field dominated epoch.
Chameleon scalar fields in relativistic gravitational backgrounds
International Nuclear Information System (INIS)
Tsujikawa, Shinji; Tamaki, Takashi; Tavakol, Reza
2009-01-01
We study the field profile of a scalar field φ that couples to a matter fluid (dubbed a chameleon field) in the relativistic gravitational background of a spherically symmetric spacetime. Employing a linear expansion in terms of the gravitational potential Φ c at the surface of a compact object with a constant density, we derive the thin-shell field profile both inside and outside the object, as well as the resulting effective coupling with matter, analytically. We also carry out numerical simulations for the class of inverse power-law potentials V(φ) = M 4+n φ −n by employing the information provided by our analytical solutions to set the boundary conditions around the centre of the object and show that thin-shell solutions in fact exist if the gravitational potential Φ c is smaller than 0.3, which marginally covers the case of neutron stars. Thus the chameleon mechanism is present in the relativistic gravitational backgrounds, capable of reducing the effective coupling. Since thin-shell solutions are sensitive to the choice of boundary conditions, our analytic field profile is very helpful to provide appropriate boundary conditions for Φ c ∼< O(0.1)
Chameleon scalar fields in relativistic gravitational backgrounds
Energy Technology Data Exchange (ETDEWEB)
Tsujikawa, Shinji [Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 (Japan); Tamaki, Takashi [Department of Physics, Waseda University, Okubo 3-4-1, Tokyo 169-8555 (Japan); Tavakol, Reza, E-mail: shinji@rs.kagu.tus.ac.jp, E-mail: tamaki@gravity.phys.waseda.ac.jp, E-mail: r.tavakol@qmul.ac.uk [Astronomy Unit, School of Mathematical Sciences, Queen Mary University of London, London E1 4NS (United Kingdom)
2009-05-15
We study the field profile of a scalar field {phi} that couples to a matter fluid (dubbed a chameleon field) in the relativistic gravitational background of a spherically symmetric spacetime. Employing a linear expansion in terms of the gravitational potential {Phi}{sub c} at the surface of a compact object with a constant density, we derive the thin-shell field profile both inside and outside the object, as well as the resulting effective coupling with matter, analytically. We also carry out numerical simulations for the class of inverse power-law potentials V({phi}) = M{sup 4+n}{phi}{sup -n} by employing the information provided by our analytical solutions to set the boundary conditions around the centre of the object and show that thin-shell solutions in fact exist if the gravitational potential {Phi}{sub c} is smaller than 0.3, which marginally covers the case of neutron stars. Thus the chameleon mechanism is present in the relativistic gravitational backgrounds, capable of reducing the effective coupling. Since thin-shell solutions are sensitive to the choice of boundary conditions, our analytic field profile is very helpful to provide appropriate boundary conditions for {Phi}{sub c}{approx}
Canonical action-angle formalism for quantized nonlinear fields
International Nuclear Information System (INIS)
Garbaczewki, P.
1987-01-01
The canonical quantizations of field and action-angle coordinates which (locally) parameterize the phase manifold for the same nonlinear field theory model (e.g. sine-Gordon and nonlinear Schrodinger with the attractive coupling) are reconciled on the common for both cases state space. The classical-quantum relationship is maintained in the mean: coherent state expectation values of operators give rise to classical objects
Generalized field quantization and the Pauli principle
International Nuclear Information System (INIS)
Govorkov, A.B.
1990-01-01
The work is an attempt to prove that the generalized Pauli principle (i.e. Fermi statistics) for the half-integer spin fields and the Bose statistics for the integer spin fields with allowance for the existence of internal gauge symmetries are consequences of more general assumptions of the local quantum field theory. 32 refs.; 1 tab
On symmetry inheritance of nonminimally coupled scalar fields
Barjašić, Irena; Smolić, Ivica
2018-04-01
We present the first symmetry inheritance analysis of fields non-minimally coupled to gravity. In this work we are focused on the real scalar field ϕ with nonminimal coupling of the form ξφ2 R . Possible cases of symmetry noninheriting fields are constrained by the properties of the Ricci tensor and the scalar potential. Examples of such spacetimes can be found among those which are ‘dressed’ with the stealth scalar field, a nontrivial scalar field configuration with the vanishing energy–momentum tensor. We classify the scalar field potentials which allow symmetry noninheriting stealth field configurations on top of the exact solutions of the Einstein’s gravitational field equation with the cosmological constant.
Decoding the hologram: Scalar fields interacting with gravity
Kabat, Daniel; Lifschytz, Gilad
2014-03-01
We construct smeared conformal field theory (CFT) operators which represent a scalar field in anti-de Sitter (AdS) space interacting with gravity. The guiding principle is microcausality: scalar fields should commute with themselves at spacelike separation. To O(1/N) we show that a correct and convenient criterion for constructing the appropriate CFT operators is to demand microcausality in a three-point function with a boundary Weyl tensor and another boundary scalar. The resulting bulk observables transform in the correct way under AdS isometries and commute with boundary scalar operators at spacelike separation, even in the presence of metric perturbations.
Scalar field collapse in Gauss-Bonnet gravity
Banerjee, Narayan; Paul, Tanmoy
2018-02-01
We consider a "scalar-Einstein-Gauss-Bonnet" theory in four dimension, where the scalar field couples non-minimally with the Gauss-Bonnet (GB) term. This coupling with the scalar field ensures the non-topological character of the GB term. In this scenario, we examine the possibility for collapsing of the scalar field. Our result reveals that such a collapse is possible in the presence of Gauss-Bonnet gravity for suitable choices of parametric regions. The singularity formed as a result of the collapse is found to be a curvature singularity which is hidden from the exterior by an apparent horizon.
Scalar field collapse in Gauss-Bonnet gravity
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Narayan [Indian Institute of Science Education and Research Kolkata, Department of Physical Sciences, Nadia, West Bengal (India); Paul, Tanmoy [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2018-02-15
We consider a ''scalar-Einstein-Gauss-Bonnet'' theory in four dimension, where the scalar field couples non-minimally with the Gauss-Bonnet (GB) term. This coupling with the scalar field ensures the non-topological character of the GB term. In this scenario, we examine the possibility for collapsing of the scalar field. Our result reveals that such a collapse is possible in the presence of Gauss-Bonnet gravity for suitable choices of parametric regions. The singularity formed as a result of the collapse is found to be a curvature singularity which is hidden from the exterior by an apparent horizon. (orig.)
Mathematical aspects of field quantization. Quantum electrodynamics
International Nuclear Information System (INIS)
Bongaarts, P.J.M.
1983-01-01
Fundamental mathematical aspects of quantum field theory are discussed. A brief review of various approaches to mathematical problems of quantum electrodynamics is given, preceded by a more extensive account of the development of ideas on the mathematical nature of quantum fields in general, providing an appropriate historical context. (author)
Scalar field dark matter: behavior around black holes
Energy Technology Data Exchange (ETDEWEB)
Cruz-Osorio, Alejandro; Guzmán, F. Siddhartha; Lora-Clavijo, Fabio D., E-mail: alejandro@ifm.umich.mx, E-mail: guzman@ifm.umich.mx, E-mail: fadulora@ifm.umich.mx [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Cd. Universitaria, 58040 Morelia, Michoacán (Mexico)
2011-06-01
We present the numerical evolution of a massive test scalar fields around a Schwarzschild space-time. We proceed by using hyperboloidal slices that approach future null infinity, which is the boundary of scalar fields, and also demand the slices to penetrate the event horizon of the black hole. This approach allows the scalar field to be accreted by the black hole and to escape toward future null infinity. We track the evolution of the energy density of the scalar field, which determines the rate at which the scalar field is being diluted. We find polynomial decay of the energy density of the scalar field, and use it to estimate the rate of dilution of the field in time. Our findings imply that the energy density of the scalar field decreases even five orders of magnitude in time scales smaller than a year. This implies that if a supermassive black hole is the Schwarzschild solution, then scalar field dark matter would be diluted extremely fast.
Scalar field dark matter: behavior around black holes
International Nuclear Information System (INIS)
Cruz-Osorio, Alejandro; Guzmán, F. Siddhartha; Lora-Clavijo, Fabio D.
2011-01-01
We present the numerical evolution of a massive test scalar fields around a Schwarzschild space-time. We proceed by using hyperboloidal slices that approach future null infinity, which is the boundary of scalar fields, and also demand the slices to penetrate the event horizon of the black hole. This approach allows the scalar field to be accreted by the black hole and to escape toward future null infinity. We track the evolution of the energy density of the scalar field, which determines the rate at which the scalar field is being diluted. We find polynomial decay of the energy density of the scalar field, and use it to estimate the rate of dilution of the field in time. Our findings imply that the energy density of the scalar field decreases even five orders of magnitude in time scales smaller than a year. This implies that if a supermassive black hole is the Schwarzschild solution, then scalar field dark matter would be diluted extremely fast
Quantized fields and operators on a partial inner product space
International Nuclear Information System (INIS)
Shabani, J.
1985-11-01
We investigate the connection between the space OpV of all operators on a partial inner product space V and the weak sequential completion of the * algebra L + (Vsup(no.)) of all operators X such that Vsup(no.) is contained in D(X) intersection D(X*) and both X and its adjoint X* leave Vsup(no.) invariant. This connection gives a mathematical description of quantized fields in terms of elements of OpV. (author)
The Theory of Quantized Fields. III
Schwinger, J.
1953-05-01
In this paper we discuss the electromagnetic field, as perturbed by a prescribed current. All quantities of physical interest in various situations, eigenvalues, eigenfunctions, and transformation probabilities, are derived from a general transformation function which is expressed in a non-Hermitian representation. The problems treated are: the determination of the energy-momentum eigenvalues and eigenfunctions for the isolated electromagnetic field, and the energy eigenvalues and eigenfunctions for the field perturbed by a time-independent current that departs from zero only within a finite time interval, and for a time-dependent current that assumes non-vanishing time-independent values initially and finally. The results are applied in a discussion of the intra-red catastrophe and of the adiabatic theorem. It is shown how the latter can be exploited to give a uniform formulation for all problems requiring the evaluation of transition probabilities or eigenvalue displacements.
Regular and Chaotic Regimes in Scalar Field Cosmology
Directory of Open Access Journals (Sweden)
Alexey V. Toporensky
2006-03-01
Full Text Available A transient chaos in a closed FRW cosmological model with a scalar field is studied. We describe two different chaotic regimes and show that the type of chaos in this model depends on the scalar field potential. We have found also that for sufficiently steep potentials or for potentials with large cosmological constant the chaotic behavior disappears.
International Nuclear Information System (INIS)
Kalloniatis, A.C.
1996-01-01
SU(2) Yang-Mills theory coupled to massive adjoint scalar matter is studied in 1+1 dimensions using discretized light-cone quantization. This theory can be obtained from pure Yang-Mills theory in 2+1 dimensions via dimensional reduction. On the light cone, the vacuum structure of this theory is encoded in the dynamical zero mode of a gluon and a constrained mode of the scalar field. The latter satisfies a linear constraint, suggesting no nontrivial vacua in the present paradigm for symmetry breaking on the light cone. I develop a diagrammatic method to solve the constraint equation. In the adiabatic approximation I compute the quantum-mechanical potential governing the dynamical gauge mode. Because of a condensation of the lowest momentum modes of the dynamical gluons, a centrifugal barrier is generated in the adiabatic potential. In the present theory, however, the barrier height appears too small to make any impact in this model. Although the theory is superrenormalizable on naive power-counting grounds, the removal of ultraviolet divergences is nontrivial when the constrained mode is taken into account. The solution of this problem is discussed. copyright 1996 The American Physical Society
Precise quantization of anomalous Hall effect near zero magnetic field
Energy Technology Data Exchange (ETDEWEB)
Bestwick, A. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Fox, E. J. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Kou, Xufeng [Univ. of California, Los Angeles, CA (United States); Pan, Lei [Univ. of California, Los Angeles, CA (United States); Wang, Kang L. [Univ. of California, Los Angeles, CA (United States); Goldhaber-Gordon, D. [Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
2015-05-04
In this study, we report a nearly ideal quantum anomalous Hall effect in a three-dimensional topological insulator thin film with ferromagnetic doping. Near zero applied magnetic field we measure exact quantization in the Hall resistance to within a part per 10,000 and a longitudinal resistivity under 1 Ω per square, with chiral edge transport explicitly confirmed by nonlocal measurements. Deviations from this behavior are found to be caused by thermally activated carriers, as indicated by an Arrhenius law temperature dependence. Using the deviations as a thermometer, we demonstrate an unexpected magnetocaloric effect and use it to reach near-perfect quantization by cooling the sample below the dilution refrigerator base temperature in a process approximating adiabatic demagnetization refrigeration.
Generalized field quantization and statistics of elementary particles
International Nuclear Information System (INIS)
Govorkov, A.V.
1994-01-01
Generalized schemes for the quantization of free fields based on the deformed trilinear relations of Green are investigated. A theorem shows that in reality continuous deformation is impossible. In particular, it is shown that a open-quotes smallclose quotes violation of the ordinary Fermi and Bose statistics is impossible both in the framework of local field theory, corresponding to parastatistics of finite orders, and in the framework of nonlocal field theory, corresponding to infinite statistics. The existence of antiparticles plays a decisive role in establishing the matter case. 23 refs
Effect of the chameleon scalar field on brane cosmological evolution
Bisabr, Y.; Ahmadi, F.
2017-11-01
We have investigated a brane world model in which the gravitational field in the bulk is described both by a metric tensor and a minimally coupled scalar field. This scalar field is taken to be a chameleon with an appropriate potential function. The scalar field interacts with matter and there is an energy transfer between the two components. We find a late-time asymptotic solution which exhibits late-time accelerating expansion. We also show that the Universe recently crosses the phantom barrier without recourse to any exotic matter. We provide some thermodynamic arguments which constrain both the direction of energy transfer and dynamics of the extra dimension.
Effect of the chameleon scalar field on brane cosmological evolution
Directory of Open Access Journals (Sweden)
Y. Bisabr
2017-11-01
Full Text Available We have investigated a brane world model in which the gravitational field in the bulk is described both by a metric tensor and a minimally coupled scalar field. This scalar field is taken to be a chameleon with an appropriate potential function. The scalar field interacts with matter and there is an energy transfer between the two components. We find a late-time asymptotic solution which exhibits late-time accelerating expansion. We also show that the Universe recently crosses the phantom barrier without recourse to any exotic matter. We provide some thermodynamic arguments which constrain both the direction of energy transfer and dynamics of the extra dimension.
Two dimensional topological insulator in quantizing magnetic fields
Olshanetsky, E. B.; Kvon, Z. D.; Gusev, G. M.; Mikhailov, N. N.; Dvoretsky, S. A.
2018-05-01
The effect of quantizing magnetic field on the electron transport is investigated in a two dimensional topological insulator (2D TI) based on a 8 nm (013) HgTe quantum well (QW). The local resistance behavior is indicative of a metal-insulator transition at B ≈ 6 T. On the whole the experimental data agrees with the theory according to which the helical edge states transport in a 2D TI persists from zero up to a critical magnetic field Bc after which a gap opens up in the 2D TI spectrum.
DEFF Research Database (Denmark)
Möllers, Jan
2013-01-01
(\\pi)\\subseteq\\mathfrak{p}_{\\mathbb{C}}^*$. The associated variety $Ass(\\pi)$ is the closure of a single nilpotent $K_{\\mathbb{C}}$-orbit $\\mathcal{O}^{K_{\\mathbb{C}}}\\subseteq\\mathfrak{p}_{\\mathbb{C}}^*$ which corresponds by the Kostant-Sekiguchi correspondence to a nilpotent coadjoint $G$-orbit $\\mathcal{O}^G\\subseteq\\mathfrak{g}^*$. The known Schr\\"odinger...... model of $\\pi$ is a realization on $L^2(\\mathcal{O})$, where $\\mathcal{O}\\subseteq\\mathcal{O}^G$ is a Lagrangian submanifold. We construct an intertwining operator from the Schr\\"odinger model to the new Fock model, the generalized Segal-Bargmann transform, which gives a geometric quantization...... and as integral kernel of the Segal-Bargmann transform. As a corollary to our construction we also obtain the integral kernel of the unitary inversion operator in the Schr\\"odinger model in terms of a multivariable $J$-Bessel function....
The 5D Standing Wave Braneworld with Real Scalar Field
Merab Gogberashvili; Pavle Midodashvili
2013-01-01
We introduce the new 5D braneworld with the real scalar field in the bulk. The model represents the brane which bounds collective oscillations of gravitational and scalar field standing waves. These waves are out of phase; that is, the energy of oscillations passes back and forth between the scalar and gravitational waves. When the amplitude of the standing waves is small, the brane width and the size of the horizon in extra space are of a same order of magnitude, and matter fields are locali...
Exact solutions in string-motivated scalar-field cosmology
International Nuclear Information System (INIS)
Oezer, M.; Taha, M.O.
1992-01-01
Two exact cosmological solutions to a scalar-field potential motivated by six-dimensional (6D) Einstein-Maxwell theory are given. The resulting pure scalar-field cosmology is free of singularity and causality problems but conserves entropy. These solutions are then extended into exact cosmological solutions for a decaying scalar field with an approximate two-loop 4D string potential. The resulting cosmology is, for both solutions, free of cosmological problems and close to the standard cosmology of the radiation era
Scalar field vacuum expectation value induced by gravitational wave background
Jones, Preston; McDougall, Patrick; Ragsdale, Michael; Singleton, Douglas
2018-06-01
We show that a massless scalar field in a gravitational wave background can develop a non-zero vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. We propose that this vacuum expectation value, generated by a gravitational wave, can be connected with particle production from gravitational waves and may have consequences for the early Universe where scalar fields are thought to play an important role.
Einstein gravity with torsion induced by the scalar field
Özçelik, H. T.; Kaya, R.; Hortaçsu, M.
2018-06-01
We couple a conformal scalar field in (2+1) dimensions to Einstein gravity with torsion. The field equations are obtained by a variational principle. We could not solve the Einstein and Cartan equations analytically. These equations are solved numerically with 4th order Runge-Kutta method. From the numerical solution, we make an ansatz for the rotation parameter in the proposed metric, which gives an analytical solution for the scalar field for asymptotic regions.
Classical behavior of a scalar field in the inflationary universe
International Nuclear Information System (INIS)
Sasaki, Misao; Nambu, Yasusada; Nakao, Ken-ichi.
1987-09-01
Extending the coarse-graining approach of Starobinsky, we formulate a theory to deal with the dynamics of a scalar field in inflationary universe models. We find a set of classical Langevin equations which describes the large scale behavior of the scalar field, provided that the coarse-grained size is greater than the effective compton wavelength of the scalar field. The corresponding Fokker-Planck equation is also derived which is defined on the phase space of the scalar field. We show that our theory is essentially equivalent to the one-loop field theory in de Sitter space and reduces to that of Starobinsky in a strong limit of the slow roll-over condition. Analysis of a simple Higgs potential model is done and the implications are discussed. (author)
Renormalization in the stochastic quantization of field theories
International Nuclear Information System (INIS)
Brunelli, J.C.
1991-01-01
In the stochastic quantization scheme of Parisi and Wu the renormalization of the stochastic theory of some models in field theory is studied. Following the path integral approach for stochastic process the 1/N expansion of the non linear sigma model is performed and, using a Ward identity obtained, from a BRS symmetry of the effective action of this formulation. It is shown the renormalizability of the model. Using the Langevin approach for stochastic process the renormalizability of the massive Thirring model is studied showing perturbatively the vanishing of the renormalization group's beta functions at finite fictitious time. (author)
A nonlinear dynamics for the scalar field in Randers spacetime
Energy Technology Data Exchange (ETDEWEB)
Silva, J.E.G. [Universidade Federal do Cariri (UFCA), Instituto de formação de professores, Rua Olegário Emídio de Araújo, Brejo Santo, CE, 63.260.000 (Brazil); Maluf, R.V. [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Fortaleza, CE, C.P. 6030, 60455-760 (Brazil); Almeida, C.A.S., E-mail: carlos@fisica.ufc.br [Universidade Federal do Ceará (UFC), Departamento de Física, Campus do Pici, Fortaleza, CE, C.P. 6030, 60455-760 (Brazil)
2017-03-10
We investigate the properties of a real scalar field in the Finslerian Randers spacetime, where the local Lorentz violation is driven by a geometrical background vector. We propose a dynamics for the scalar field by a minimal coupling of the scalar field and the Finsler metric. The coupling is intrinsically defined on the Randers spacetime, and it leads to a non-canonical kinetic term for the scalar field. The nonlinear dynamics can be split into a linear and nonlinear regimes, which depend perturbatively on the even and odd powers of the Lorentz-violating parameter, respectively. We analyze the plane-waves solutions and the modified dispersion relations, and it turns out that the spectrum is free of tachyons up to second-order.
q-bosons and the q-analogue quantized field
International Nuclear Information System (INIS)
Nelson, C.A.
1994-01-01
The q-analogue coherent states |z > q are used to identify physical signatures for the presence of a q-analogue quantized radiation field in the | > q classical limit where |z| is large. In this quantum-optics-like limit, the fractional uncertainties of most physical quantities (momentum, position, amplitude, phase) which characterize the quantum field are O(1). They only vanish as O(1/|z|) when q = 1. However, for the number operator, N, and the N-Hamiltonian for a free q-boson gas, H N = ℎω(N + 1/2), the fractional uncertainties do still approach zero. A signature for q-boson counting statistics is that (ΔN) 2 / → 0 as |z| → ∞. Except for its O(1) fractional uncertainty, the q-generalization of the Hermitian phase operator of Pegg and Barnett, φ q , still exhibits normal classical behavior. The standard number-phase uncertainty-relation, ΔN Δφ q = 1/2, and the approximate commutation relation, [N,φ q ] = i, still hold for the single-mode q-analogue quantized field. So, N and φ q are almost canonically conjugate operators in the |z > q classical limit. The |z > q CS's minimize this uncertainty relation for moderate |z| 2
Uniform and Non-Uniform Optimum Scalar Quantizers Performances: A Comparative Study
Directory of Open Access Journals (Sweden)
Fendy Santoso
2008-05-01
Full Text Available The aim of this research is to investigate source coding, the representation of information source output by finite R bits/symbol. The performance of optimum quantisers subject to an entropy constraint has been studied. The definitive work in this area is best summarised by Shannon’s source coding theorem, that is, a source with entropy H can be encoded with arbitrarily small error probability at any rate R (bits/source output as long as R>H. Conversely, If R the error probability will be driven away from zero, independent of the complexity of the encoder and the decoder employed. In this context, the main objective of engineers is however to design the optimum code. Unfortunately, the rate-distortion theorem does not provide the recipe for such a design. The theorem does, however, provide the theoretical limit so that we know how close we are to the optimum. The full understanding of the theorem also helps in setting the direction to achieve such an optimum. In this research, we have investigated the performances of two practical scalar quantisers, i.e., a Lloyd-Max quantiser and the uniformly defined one and also a well-known entropy coding scheme, i.e., Huffman coding against their theoretically attainable optimum performance due to Shannon’s limit R. It has been shown that our uniformly defined quantiser could demonstrate superior performance. The performance improvements, in fact, are more noticeable at higher bit rates.
Exact spinor-scalar bound states in a quantum field theory with scalar interactions
International Nuclear Information System (INIS)
Shpytko, Volodymyr; Darewych, Jurij
2001-01-01
We study two-particle systems in a model quantum field theory in which scalar particles and spinor particles interact via a mediating scalar field. The Lagrangian of the model is reformulated by using covariant Green's functions to solve for the mediating field in terms of the particle fields. This results in a Hamiltonian in which the mediating-field propagator appears directly in the interaction term. It is shown that exact two-particle eigenstates of the Hamiltonian can be determined. The resulting relativistic fermion-boson equation is shown to have Dirac and Klein-Gordon one-particle limits. Analytical solutions for the bound state energy spectrum are obtained for the case of massless mediating fields
Sun, Jun; Duan, Yizhou; Li, Jiangtao; Liu, Jiaying; Guo, Zongming
2013-01-01
In the first part of this paper, we derive a source model describing the relationship between the rate, distortion, and quantization steps of the dead-zone plus uniform threshold scalar quantizers with nearly uniform reconstruction quantizers for generalized Gaussian distribution. This source model consists of rate-quantization, distortion-quantization (D-Q), and distortion-rate (D-R) models. In this part, we first rigorously confirm the accuracy of the proposed source model by comparing the calculated results with the coding data of JM 16.0. Efficient parameter estimation strategies are then developed to better employ this source model in our two-pass rate control method for H.264 variable bit rate coding. Based on our D-Q and D-R models, the proposed method is of high stability, low complexity and is easy to implement. Extensive experiments demonstrate that the proposed method achieves: 1) average peak signal-to-noise ratio variance of only 0.0658 dB, compared to 1.8758 dB of JM 16.0's method, with an average rate control error of 1.95% and 2) significant improvement in smoothing the video quality compared with the latest two-pass rate control method.
Interacting massless scalar and source-free electromagnetic fields
International Nuclear Information System (INIS)
Ayyangar, B.R.N.; Mohanty, G.
1985-01-01
The relativistic field equations for interacting massless attractive scalar and source-free electromagnetic fields in a cylindrically symmetric spacetime of one degree of freedom with reflection symmetry have been reduced to a first order implicit differential equation depending on time which enables one to generate a class of solution to the field equations. The nature of the scalar and electromagnetic fields is discussed. It is shown that the geometry of the spacetime admits of an irrotational stiff fluid distribution without prejudice to the interacting electromagnetic fields. 10 refs. (author)
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Raoelina Andriambololona; Ranaivoson, R.T.R; Hanitriarivo, R.; Harison, V.
2014-01-01
We establish equations for scalar and fermion fields using results obtained from a study on a phase space representation of quantum theory that we have performed in a previous work. Our approaches are similar to the historical ones to obtain Klein-Gordon and Dirac equations but the main difference is that ours are based on the use of properties of operators called dispersion-codispersion operators. We begin with a brief recall about the dispersion-codispersion operators. Then, introducing a mass operator with its canonical conjugate coordinate and applying rules of quantization, based on the use of dispersion - codispersion operators , we deduce a second order differential operator relation from the relativistic expression relying energy, momentum and mass. Using Dirac matrices, we derive from this second order differential operator relation a first order one. The application of the second order differential operator relation on a scalar function gives the equation for the scalar field and the use of the first order differential operator relation leads to the equation for fermion field.
Quantizing higher-spin gravity in free-field variables
Campoleoni, Andrea; Fredenhagen, Stefan; Raeymaekers, Joris
2018-02-01
We study the formulation of massless higher-spin gravity on AdS3 in a gauge in which the fundamental variables satisfy free field Poisson brackets. This gauge choice leaves a small portion of the gauge freedom unfixed, which should be further quotiented out. We show that doing so leads to a bulk version of the Coulomb gas formalism for W N CFT's: the generators of the residual gauge symmetries are the classical limits of screening charges, while the gauge-invariant observables are classical W N charges. Quantization in these variables can be carried out using standard techniques and makes manifest a remnant of the triality symmetry of W ∞[λ]. This symmetry can be used to argue that the theory should be supplemented with additional matter content which is precisely that of the Prokushkin-Vasiliev theory. As a further application, we use our formulation to quantize a class of conical surplus solutions and confirm the conjecture that these are dual to specific degenerate W N primaries, to all orders in the large central charge expansion.
On quantization of free fields in stationary space-times
International Nuclear Information System (INIS)
Moreno, C.
1977-01-01
In Section 1 the structure of the infinite-dimensional Hamiltonian system described by the Klein-Gordon equation (free real scalar field) in stationary space-times with closed space sections, is analysed, an existence and uniqueness theorem is given for the Lichnerowicz distribution kernel G 1 together with its proper Fourier expansion, and the Hilbert spaces of frequency-part solutions defined by means of G 1 are constructed. In Section 2 an analysis, a theorem and a construction similar to the above are formulated for the free real field spin 1, mass m>0, in one kind of static space-times. (Auth.)
Arbitrary scalar-field and quintessence cosmological models
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Harko, Tiberiu; Lobo, Francisco S.N.; Mak, M.K.
2014-01-01
The mechanism of the initial inflationary scenario of the Universe and of its late-time acceleration can be described by assuming the existence of some gravitationally coupled scalar fields φ, with the inflaton field generating inflation and the quintessence field being responsible for the late accelerated expansion. Various inflationary and late-time accelerated scenarios are distinguished by the choice of an effective self-interaction potential V(φ), which simulates a temporarily non-vanishing cosmological term. In this work, we present a new formalism for the analysis of scalar fields in flat isotropic and homogeneous cosmological models. The basic evolution equation of the models can be reduced to a first-order non-linear differential equation. Approximate solutions of this equation can be constructed in the limiting cases of the scalar-field kinetic energy and potential energy dominance, respectively, as well as in the intermediate regime. Moreover, we present several new accelerating and decelerating exact cosmological solutions, based on the exact integration of the basic evolution equation for scalar-field cosmologies. More specifically, exact solutions are obtained for exponential, generalized cosine hyperbolic, and power-law potentials, respectively. Cosmological models with power-law scalar field potentials are also analyzed in detail. (orig.)
Scalar fields and their applications in astrophysics and cosmology
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Mbelek, Jean-Paul
2003-01-01
This research thesis reports an analysis of the different existing theoretical contexts of occurrence of scalar fields in unified field theories, astrophysics and cosmology. More particularly, most of unified theories (Grand Unified Theories of GUTs, string theories, and so on) can be reduced, within astrophysical and cosmological conditions, to the form of effective theories such as Kaluza-Klein (multi-dimensional theories) or Brans-Dicke (four-dimensional theories) theories which comprise scalar fields. After a presentation of these theories, the author discusses the concept of scalar fields in field quantum theories and in cosmology. He proposes a stabilised model of the Kaluza-Klein theory in 5D, and several experiments designed to measure G. The thesis is completed by several published articles and contributions [fr
Thermodynamics of perfect fluids from scalar field theory
Ballesteros, Guillermo; Pilo, Luigi
2016-01-01
The low-energy dynamics of relativistic continuous media is given by a shift-symmetric effective theory of four scalar fields. These scalars describe the embedding in spacetime of the medium and play the role of Stuckelberg fields for spontaneously broken spatial and time translations. Perfect fluids are selected imposing a stronger symmetry group or reducing the field content to a single scalar. We explore the relation between the field theory description of perfect fluids to thermodynamics. By drawing the correspondence between the allowed operators at leading order in derivatives and the thermodynamic variables, we find that a complete thermodynamic picture requires the four Stuckelberg fields. We show that thermodynamic stability plus the null energy condition imply dynamical stability. We also argue that a consistent thermodynamic interpretation is not possible if any of the shift symmetries is explicitly broken.
N-body simulations for coupled scalar-field cosmology
International Nuclear Information System (INIS)
Li Baojiu; Barrow, John D.
2011-01-01
We describe in detail the general methodology and numerical implementation of consistent N-body simulations for coupled-scalar-field models, including background cosmology and the generation of initial conditions (with the different couplings to different matter species taken into account). We perform fully consistent simulations for a class of coupled-scalar-field models with an inverse power-law potential and negative coupling constant, for which the chameleon mechanism does not work. We find that in such cosmological models the scalar-field potential plays a negligible role except in the background expansion, and the fifth force that is produced is proportional to gravity in magnitude, justifying the use of a rescaled gravitational constant G in some earlier N-body simulation works for similar models. We then study the effects of the scalar coupling on the nonlinear matter power spectra and compare with linear perturbation calculations to see the agreement and places where the nonlinear treatment deviates from the linear approximation. We also propose an algorithm to identify gravitationally virialized matter halos, trying to take account of the fact that the virialization itself is also modified by the scalar-field coupling. We use the algorithm to measure the mass function and study the properties of dark-matter halos. We find that the net effect of the scalar coupling helps produce more heavy halos in our simulation boxes and suppresses the inner (but not the outer) density profile of halos compared with the ΛCDM prediction, while the suppression weakens as the coupling between the scalar field and dark-matter particles increases in strength.
Quasistationary solutions of scalar fields around accreting black holes
Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Izquierdo, Paula; Font, José A.; Montero, Pedro J.
2016-08-01
Massive scalar fields can form long-lived configurations around black holes. These configurations, dubbed quasibound states, have been studied both in the linear and nonlinear regimes. In this paper, we show that quasibound states can form in a dynamical scenario in which the mass of the black hole grows significantly due to the capture of infalling matter. We solve the Klein-Gordon equation numerically in spherical symmetry, mimicking the evolution of the spacetime through a sequence of analytic Schwarzschild black hole solutions of increasing mass. It is found that the frequency of oscillation of the quasibound states decreases as the mass of the black hole increases. In addition, accretion leads to an increase of the exponential decay of the scalar field energy. We compare the black hole mass growth rates used in our study with estimates from observational surveys and extrapolate our results to values of the scalar field masses consistent with models that propose scalar fields as dark matter in the universe. We show that, even for unrealistically large mass accretion rates, quasibound states around accreting black holes can survive for cosmological time scales. Our results provide further support to the intriguing possibility of the existence of dark matter halos based on (ultralight) scalar fields surrounding supermassive black holes in galactic centers.
Constraining scalar fields with stellar kinematics and collisional dark matter
International Nuclear Information System (INIS)
Amaro-Seoane, Pau; Barranco, Juan; Bernal, Argelia; Rezzolla, Luciano
2010-01-01
The existence and detection of scalar fields could provide solutions to long-standing puzzles about the nature of dark matter, the dark compact objects at the centre of most galaxies, and other phenomena. Yet, self-interacting scalar fields are very poorly constrained by astronomical observations, leading to great uncertainties in estimates of the mass m φ and the self-interacting coupling constant λ of these fields. To counter this, we have systematically employed available astronomical observations to develop new constraints, considerably restricting this parameter space. In particular, by exploiting precise observations of stellar dynamics at the centre of our Galaxy and assuming that these dynamics can be explained by a single boson star, we determine an upper limit for the boson star compactness and impose significant limits on the values of the properties of possible scalar fields. Requiring the scalar field particle to follow a collisional dark matter model further narrows these constraints. Most importantly, we find that if a scalar dark matter particle does exist, then it cannot account for both the dark-matter halos and the existence of dark compact objects in galactic nuclei
Supersymmetric gauge theories, quantization of Mflat, and conformal field theory
International Nuclear Information System (INIS)
Teschner, J.; Vartanov, G.S.
2013-02-01
We propose a derivation of the correspondence between certain gauge theories with N=2 supersymmetry and conformal field theory discovered by Alday, Gaiotto and Tachikawa in the spirit of Seiberg-Witten theory. Based on certain results from the literature we argue that the quantum theory of the moduli spaces of flat SL(2,R)-connections represents a nonperturbative ''skeleton'' of the gauge theory, protected by supersymmetry. It follows that instanton partition functions can be characterized as solutions to a Riemann-Hilbert type problem. In order to solve it, we describe the quantization of the moduli spaces of flat connections explicitly in terms of two natural sets of Darboux coordinates. The kernel describing the relation between the two pictures represents the solution to the Riemann Hilbert problem, and is naturally identified with the Liouville conformal blocks.
Scalar, electromagnetic, and gravitational fields interaction: Particlelike solutions
International Nuclear Information System (INIS)
Bronnikov, K.A.; Melnikov, V.N.; Shikin, G.N.; Staniukovich, K.P.
1979-01-01
Particlelike static spherically symmetric solutions to massless scalar and electromagnetic field equations combined with gravitational field equations are considered. Two criteria for particlelike solutions are formulated: the strong one (solutions are required to be singularity free) and the weak one (singularities are admitted but the total energy and material field energy should be finite). Exact solutions for the following physical systems are considered with their own gravitational field: (i) linear scalar (minimally coupled or conformal) plus electromagnetic field; (ii) the same fields with a bare mass source in the form of charged incoherent matter distributions; (iii) nonlinear electromagnetic field with an abritrary dependence on the invariant F/sub alphabeta/F/sup alphabeta/; and (iv) directly interacting scalar and electromagnetic fields. Case (i) solutions are not particlelike (except those with horizons, in which static regions formally satisfy the weak criterion). For systems (ii), examples of nonsingular models are constructed, in particular, a model for a particle--antiparticle pair of a Wheeler-handle type, without scalar field and explict electric charges. Besides, a number of limitations upon nonsingular model parameters is indicated. Systems (iii) are proved to violate the strong criterion for any type of nonlinearity but can satisfy the weak criterion (e.g., the Born--Infeld nonlinearity). For systems (iv) some particlelike solutions by the weak criterion are constructed and a regularizing role of gravitation is demonstrated. Finally, an example of a field system satisfying the strong criterion is given
Stochastic quantization of the Kink solution of phi4 field theory
International Nuclear Information System (INIS)
Kates, R.; Rosenblum, A.
1989-01-01
The method of Parisi-Wu Stochastic quantization in quantum field theory is compared to earlier work in classical field equations. The method is applied to solve for the propagator for Phi 4 field theory by perturbing the Kink solution
Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields
International Nuclear Information System (INIS)
Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.
2009-01-01
We show that a coupling between chameleonlike scalar fields and photons induces linear and circular polarization in the light from astrophysical sources. In this context chameleonlike scalar fields include those of the Olive-Pospelov (OP) model, which describes a varying fine structure constant. We determine the form of this polarization numerically and give analytic expressions in two useful limits. By comparing the predicted signal with current observations we are able to improve the constraints on the chameleon-photon coupling and the coupling in the OP model by over 2 orders of magnitude. It is argued that, if observed, the distinctive form of the chameleon induced circular polarization would represent a smoking gun for the presence of a chameleon. We also report a tentative statistical detection of a chameleonlike scalar field from observations of starlight polarization in our galaxy.
Nonminimally coupled scalar fields may not curve spacetime
International Nuclear Information System (INIS)
Ayon-Beato, Eloy; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2005-01-01
It is shown that flat spacetime can be dressed with a real scalar field that satisfies the nonlinear Klein-Gordon equation without curving spacetime. Surprisingly, this possibility arises from the nonminimal coupling of the scalar field with the curvature, since a footprint of the coupling remains in the energy-momentum tensor even when gravity is switched off. Requiring the existence of solutions with vanishing energy-momentum tensor fixes the self-interaction potential as a local function of the scalar field depending on two coupling constants. The solutions describe shock waves and, in the Euclidean continuation, instanton configurations in any dimension. As a consequence of this effect, the tachyonic solutions of the free massive Klein-Gordon equation become part of the vacuum
Quantum Prisoners' Dilemma in Fluctuating Massless Scalar Field
Huang, Zhiming
2017-12-01
Quantum systems are easily affected by external environment. In this paper, we investigate the influences of external massless scalar field to quantum Prisoners' Dilemma (QPD) game. We firstly derive the master equation that describes the system evolution with initial maximally entangled state. Then, we discuss the effects of a fluctuating massless scalar field on the game's properties such as payoff, Nash equilibrium, and symmetry. We find that for different game strategies, vacuum fluctuation has different effects on payoff. Nash equilibrium is broken but the symmetry of the game is not violated.
Hydrodynamic fluctuations from a weakly coupled scalar field
Jackson, G.; Laine, M.
2018-04-01
Studies of non-equilibrium dynamics of first-order cosmological phase transitions may involve a scalar field interacting weakly with the energy-momentum tensor of a thermal plasma. At late times, when the scalar field is approaching equilibrium, it experiences both damping and thermal fluctuations. We show that thermal fluctuations induce a shear viscosity and a gravitational wave production rate, and propose that including this tunable contribution may help in calibrating the measurement of the gravitational wave production rate in hydrodynamic simulations. Furthermore it may enrich their physical scope, permitting in particular for a study of the instability of growing bubbles.
Entropy for the Quantized Field in the Atom-Field Interaction: Initial Thermal Distribution
Directory of Open Access Journals (Sweden)
Luis Amilca Andrade-Morales
2016-09-01
Full Text Available We study the entropy of a quantized field in interaction with a two-level atom (in a pure state when the field is initially in a mixture of two number states. We then generalise the result for a thermal state; i.e., an (infinite statistical mixture of number states. We show that for some specific interaction times, the atom passes its purity to the field and therefore the field entropy decreases from its initial value.
Implementability of gauge transformations and quantization of fermions in external fields
International Nuclear Information System (INIS)
Grosse, H.; Karner, G.
1986-01-01
Quantization of fermions in an external soliton field, leading to a representation of the CAR which is inequivalent to the representation connected to the massive Dirac operator, is studied. We determine classes of gauge and axial gauge transformations which can be unitarily implemented. In the latter case quantization conditions for gauge functions are obtained; integers entering can be interpreted as winding numbers. (Author)
Response of two-band systems to a single-mode quantized field
Shi, Z. C.; Shen, H. Z.; Wang, W.; Yi, X. X.
2016-03-01
The response of topological insulators (TIs) to an external weakly classical field can be expressed in terms of Kubo formula, which predicts quantized Hall conductivity of the quantum Hall family. The response of TIs to a single-mode quantized field, however, remains unexplored. In this work, we take the quantum nature of the external field into account and define a Hall conductance to characterize the linear response of a two-band system to the quantized field. The theory is then applied to topological insulators. Comparisons with the traditional Hall conductance are presented and discussed.
Quasiclassical approximation for ultralocal scalar fields
International Nuclear Information System (INIS)
Francisco, G.
1984-01-01
It is shown how to obtain the quasiclassical evolution of a class of field theories called ultralocal fields. Coherent states that follow the 'classical' orbit as defined by Klauder's weak corespondence principle and restricted action principle is explicitly shown to approximate the quantum evolutions as (h/2π) → o. (Author) [pt
Merzlikin, Boris S.; Shapiro, Ilya L.; Wipf, Andreas; Zanusso, Omar
2017-12-01
Using covariant methods, we construct and explore the Wetterich equation for a nonminimal coupling F (ϕ )R of a quantized scalar field to the Ricci scalar of a prescribed curved space. This includes the often considered nonminimal coupling ξ ϕ2R as a special case. We consider the truncations without and with scale- and field-dependent wave-function renormalization in dimensions between four and two. Thereby the main emphasis is on analytic and numerical solutions of the fixed point equations and the behavior in the vicinity of the corresponding fixed points. We determine the nonminimal coupling in the symmetric and spontaneously broken phases with vanishing and nonvanishing average fields, respectively. Using functional perturbative renormalization group methods, we discuss the leading universal contributions to the RG flow below the upper critical dimension d =4 .
Does there exist a sensible quantum theory of an ''algebra-valued'' scalar field?
International Nuclear Information System (INIS)
Anco, S.C.; Wald, R.M.
1989-01-01
Consider a scalar field phi in Minkowski spacetime, but let phi be valued in an associative, commutative algebra openA rather than openR. One may view the resulting theory as describing a collection of coupled real scalar fields. At the classical level, theories of this type are completely well behaved and have a global symmetry group which is a nontrivial enlargement of the Poincare group. (They are analogs of the new class of gauge theories for massless spin-2 fields found recently by one of us, whose gauge group is a nontrivial enlargement of the usual diffeomorphism group.) We investigate the quantization of such scalar field theories here by studying the case of a λphi 4 field, with phi valued in the two-dimensional algebra generated by an identity element e and a nilpotent element v satisfying v 2 = 0. The Coleman-Mandula theorem, which states that the symmetry group of a nontrivial quantum field theory cannot be a nontrivial enlargement of the Poincare group, is evaded here because the finite ''extra'' symmetries of the classical theory fail to be implemented in the quantum theory by unitary operators and the infinitesimal symmetries (which can be represented in the quantum theory by quadratic forms) connect the one-particle Hilbert space to multiparticle states. Nevertheless, we find that the conventional Feynman rules for this theory lead to vacuum decay at the tree level and fail to yield a well-defined S matrix. Some alternative approaches are investigated, but these also appear to fail
A few comments on general theory of quantized fields
International Nuclear Information System (INIS)
Yamaguchi, Yoshio
2005-01-01
Several important comments on General Theory of Quantized Fields shall be supplemented here. Our theory is based on (Riemannian) momentum spaces with finite volumes. Our theory is formulated in the specific inertial frame, i.e., the rest frame of the cosmic back-ground radiation (RF-CBR). To go to other reference frame, we reply on general co-ordinate (in our case, energy and momentum variables, p-representation) transformations and the principle of general relativity. We find the degeneracy on energy levels of all elementary particles (same values of all particle energies appear twice) (as compared to the conventional field theories). This doubling of energy levels might be important at the beginning (very early stage) of our evolutional universe. However, we may not wish to have such a doubling at the present epoch. We can avoid the doubling by introducing appropriate (natural and rational, of course) Yukawa interactions among fermions and bosons. Then it is easy to realize the situation in which elementary particles populated in the half of the energy levels (called 'our particles' having normal spin multiplicity) shall not 'interact' with particles populated in the other half of energy levels except gravity. The particles in the latter group may be called 'dark matter particles', which give the most natural candidates of dark matter. We have already emphasized that other candidates of dark matter are zero-point vibration energy of all elementary particles and the energy of the vacuum due to interaction Hamiltonians. (author)
Green's function for the scalar field in the early Universe
International Nuclear Information System (INIS)
Chowdhury, A.; Mallik, S.
1987-01-01
We derive the thermal Green's function for the scalar field in a de Sitter space-time and apply it to the problem of the early Universe. Field fluctuations relevant for inflation arise predominantly from wavelengths of the order of the inverse Hubble constant. Sufficient inflation is obtained in a Coleman-Weinberg model, provided the coupling constant is small enough. The results are insensitive to the choice of the vacuum of the field theory
Remarks on the spherical scalar field halo in galaxies
International Nuclear Information System (INIS)
Nandi, Kamal K.; Valitov, Ildar; Migranov, Nail G.
2009-01-01
Matos, Guzman, and Nunez proposed a model for the galactic halo within the framework of scalar field theory. We argue that an analysis involving the full metric can reveal the true physical nature of the halo only when a certain condition is maintained. We fix that condition and also calculate its impact on observable parameters of the model.
Superconvergent perturbation theory for euclidean scalar field theories
International Nuclear Information System (INIS)
Ushveridze, A.G.
1984-01-01
It is shown that the bare (unrenormalized) correlation functions in the euclidean scalar field theories can be expanded in a series whose terms, being computable in a relatively simple way, are free from ultraviolet and infrared divergencies. This series is convergent (divergent) for finite (infinite) values of the correlation functions. (orig.)
Scalar fields and cosmic censorship hypothesis in general relativity
International Nuclear Information System (INIS)
Parnovs'kij, S.L.; Gajdamaka, O.Z.
2004-01-01
We discuss an influence of the presence of some nonstandard scalar fields in the vicinity of naked time-like singularity on the type and properties of this singularity. The main goal is to study the validity of the Penrose's Cosmic Censorship hypothesis in the General Relativity
Absorption of massive scalar field by a charged black hole
Energy Technology Data Exchange (ETDEWEB)
Nakamura, T [Kyoto Univ. (Japan). Dept. of Physics; Sato, H [Kyoto Univ. (Japan). Research Inst. for Fundamental Physics
1976-04-12
Absorption and reflection of charged, massive scalar field by the Reisner-Nordstrom black hole are investigated through a numerical computation. The absorption is suppressed when (Schwarzschild radius)<(Compton wave length) and the amplification of the wave occurs when the level crossing condition is satisfied.
Ivanov, K. A.; Nikolaev, V. V.; Gubaydullin, A. R.; Kaliteevski, M. A.
2017-10-01
Based on the scattering matrix formalism, we have developed a method of quantization of an electromagnetic field in two-dimensional photonic nanostructures ( S-quantization in the two-dimensional case). In this method, the fields at the boundaries of the quantization box are expanded into a Fourier series and are related with each other by the scattering matrix of the system, which is the product of matrices describing the propagation of plane waves in empty regions of the quantization box and the scattering matrix of the photonic structure (or an arbitrary inhomogeneity). The quantization condition (similarly to the onedimensional case) is formulated as follows: the eigenvalues of the scattering matrix are equal to unity, which corresponds to the fact that the set of waves that are incident on the structure (components of the expansion into the Fourier series) is equal to the set of waves that travel away from the structure (outgoing waves). The coefficients of the matrix of scattering through the inhomogeneous structure have been calculated using the following procedure: the structure is divided into parallel layers such that the permittivity in each layer varies only along the axis that is perpendicular to the layers. Using the Fourier transform, the Maxwell equations have been written in the form of a matrix that relates the Fourier components of the electric field at the boundaries of neighboring layers. The product of these matrices is the transfer matrix in the basis of the Fourier components of the electric field. Represented in a block form, it is composed by matrices that contain the reflection and transmission coefficients for the Fourier components of the field, which, in turn, constitute the scattering matrix. The developed method considerably simplifies the calculation scheme for the analysis of the behavior of the electromagnetic field in structures with a two-dimensional inhomogeneity. In addition, this method makes it possible to obviate
Ultraviolet stability in euclidean scalar field theories
Energy Technology Data Exchange (ETDEWEB)
Benfatto, G; Cassandro, M; Gallavotti, G; Nicolo, F; Olivieri, E; Presutti, E; Scacciatelli, E [Rome Univ. (Italy). Istituto di Matematica; Rome Univ. (Italy). Istituto di Fisica)
1980-01-01
We develop a technique for reducing the problem of the ultraviolet divergences and their removal to a free field problem. This work is an example of a problem to which a rather general method can be applied. It can be thought as an attempt towards a rigorous version (in 2 or 3 space-time dimensions) of the analysis of the structure of the functional integrals, the underlying mechanism being essentially the same as in Glimms approach.
Electromagnetic fields with vanishing scalar invariants
Czech Academy of Sciences Publication Activity Database
Ortaggio, Marcello; Pravda, Vojtěch
2016-01-01
Roč. 33, č. 11 (2016), s. 115010 ISSN 0264-9381 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : electromagnetic fields * n-dimensional spacetime * Einstein-Maxwell equations Subject RIV: BA - General Mathematics Impact factor: 3.119, year: 2016 http://dx.doi.org/10.1088/0264-9381/33/11/115010
Anderson, David; Yunes, Nicolás
2017-09-01
Scalar-tensor theories of gravity modify general relativity by introducing a scalar field that couples nonminimally to the metric tensor, while satisfying the weak-equivalence principle. These theories are interesting because they have the potential to simultaneously suppress modifications to Einstein's theory on Solar System scales, while introducing large deviations in the strong field of neutron stars. Scalar-tensor theories can be classified through the choice of conformal factor, a scalar that regulates the coupling between matter and the metric in the Einstein frame. The class defined by a Gaussian conformal factor with a negative exponent has been studied the most because it leads to spontaneous scalarization (i.e. the sudden activation of the scalar field in neutron stars), which consequently leads to large deviations from general relativity in the strong field. This class, however, has recently been shown to be in conflict with Solar System observations when accounting for the cosmological evolution of the scalar field. We here study whether this remains the case when the exponent of the conformal factor is positive, as well as in another class of theories defined by a hyperbolic conformal factor. We find that in both of these scalar-tensor theories, Solar System tests are passed only in a very small subset of coupling parameter space, for a large set of initial conditions compatible with big bang nucleosynthesis. However, while we find that it is possible for neutron stars to scalarize, one must carefully select the coupling parameter to do so, and even then, the scalar charge is typically 2 orders of magnitude smaller than in the negative-exponent case. Our study suggests that future work on scalar-tensor gravity, for example in the context of tests of general relativity with gravitational waves from neutron star binaries, should be carried out within the positive coupling parameter class.
Entanglement entropy in scalar field theory on the fuzzy sphere
International Nuclear Information System (INIS)
Okuno, Shizuka; Suzuki, Mariko; Tsuchiya, Asato
2016-01-01
We study entanglement entropy on the fuzzy sphere. We calculate it in a scalar field theory on the fuzzy sphere, which is given by a matrix model. We use a method that is based on the replica method and applicable to interacting fields as well as free fields. For free fields, we obtain results consistent with the previous study, which serves as a test of the validity of the method. For interacting fields, we perform Monte Carlo simulations at strong coupling and see a novel behavior of entanglement entropy
Infrared and ultraviolet behaviour of effective scalar field theory
International Nuclear Information System (INIS)
Ball, R.D.; Thorne, R.S.
1995-01-01
We consider the infrared and ultraviolet behaviour of the effective quantum field theory of a single Z 2 symmetric scalar field. In a previous paper we proved to all orders in perturbation theory the renormalizability of massive effective scalar field theory using Wilson's exact renormalization group equation. Here we show that away from exceptional momenta the massless theory is similarly renormalizable, and we prove detailed bounds on Green's functions as arbitrary combinations of exceptional Euclidean momenta are approached. As a corollary we also Weinberg's Theorem for the massive effective theory, n the form of bounds on Green's functions at Euclidean momenta much greater than the particle mass but below the naturalness scale of theory. 12 refs
Infrared and ultraviolet behaviour of effective scalar field theory
Ball, R D
1995-01-01
We consider the infrared and ultraviolet behaviour of the effective quantum field theory of a single Z_2 symmetric scalar field. In a previous paper we proved to all orders in perturbation theory the renormalizability of massive effective scalar field theory using Wilson's exact renormalization group equation. Here we show that away from exceptional momenta the massless theory is similarly renormalizable, and we prove detailed bounds on Green's functions as arbitrary combinations of exceptional Euclidean momenta are approached. As a corollary we also prove Weinberg's Theorem for the massive effective theory, in the form of bounds on Green's functions at Euclidean momenta much greater than the particle mass but below the naturalness scale of the theory.
On the stability of the asymptotically free scalar field theories
Energy Technology Data Exchange (ETDEWEB)
Shalaby, A M. [Department of Mathematics, Statistics and Physics, College of Arts and Sciences, Qatar University, Doha (Qatar); Physics Department, Faculty of Science, Mansoura University, Egypt. amshalab@qu.edu.qa (Egypt)
2015-03-30
Asymptotic freedom plays a vital role in our understanding of the theory of particle interactions. To have this property, one has to resort to a Non-abelian gauge theory with the number of colors equal to or greater than three (QCD). However, recent studies have shown that simple scalar field theories can possess this interesting property. These theories have non-Hermitian effective field forms but their classical potentials are bounded from above. In this work, we shall address the stability of the vacua of the bounded from above (−Φ{sup 4+n}) scalar field theories. Moreover, we shall cover the effect of the distribution of the Stokes wedges in the complex Φ-plane on the features of the vacuum condensate within these theories.
Energy momentum tensor in theories with scalar field
International Nuclear Information System (INIS)
Joglekar, S.D.
1992-01-01
The renormalization of energy momentum tensor in theories with scalar fields and two coupling constants is considered. The need for addition of an improvement term is shown. Two possible forms for the improvement term are: (i) One in which the improvement coefficient is a finite function of bare parameters of the theory (so that the energy-momentum tensor can be derived from an action that is a finite function of bare quantities), (ii) One in which the improvement coefficient is a finite quantity, i.e. finite function of the renormalized quantities are considered. Four possible model of such theories are (i) Scalar Q.E.D. (ii) Non-Abelian theory with scalars, (iii) Yukawa theory, (iv) A model with two scalars. In all these theories a negative conclusion is established: neither forms for the improvement terms lead to a finite energy momentum tensor. Physically this means that when interaction with external gravity is incorporated in such a model, additional experimental input in the form of root mean square mass radius must be given to specify the theory completely, and the flat space parameters are insufficient. (author). 12 refs
Non-Gaussianity from self-ordering scalar fields
International Nuclear Information System (INIS)
Figueroa, Daniel G.; Caldwell, Robert R.; Kamionkowski, Marc
2010-01-01
The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide a simple approximation that may be useful for data analysis. The bispectrum is largest for triangles that are aligned (have edges k 1 ≅2k 2 ≅2k 3 ) as opposed to the local-model bispectrum, which peaks for squeezed triangles (k 1 ≅k 2 >>k 3 ), and the equilateral bispectrum, which peaks at k 1 ≅k 2 ≅k 3 . We estimate that this non-Gaussianity should be detectable by the Planck satellite if the contribution from self-ordering scalar fields to primordial perturbations is near the current upper limit.
Quantization of bag-like solitons
International Nuclear Information System (INIS)
Breit, J.D.
1982-01-01
The method of collective coordinates is used to quantize bag-like solitons formed by scalar and spinor fields. This method leads to approximate wave functions for quarks in the bag that are orthogonal to the translational modes. Solutions are given for the MIT bag limit of the fields. (orig.)
New techniques in 3D scalar and vector field visualization
International Nuclear Information System (INIS)
Max, N.; Crawfis, R.; Becker, B.
1993-01-01
At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ''splatting'' scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ''flow volume'' of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity
New techniques in 3D scalar and vector field visualization
Energy Technology Data Exchange (ETDEWEB)
Max, N.; Crawfis, R.; Becker, B.
1993-05-05
At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.
Structures of conserved currents and mass spectra for scalar fields
International Nuclear Information System (INIS)
Shintani, Meiun.
1979-05-01
Considering the commutators between a scalar field and a conserved current, we shall clarify the connection between the mass spectrum for a scalar field and the structures of a current. For a special form of currents involving c-number functions, non-invariance of the vacuum under the corresponding transformation entails the existence of a massive mode. It is shown that once a type of currents is specified, the pole structures for sub(o) depend only on c-number parts of J sub(μ)(x). We shall show that non-vanishing Goldstone commutator does not automatically imply the degeneracy of the vacuum state, and discuss the applicability of the Goldstone theorem. (author)
Stochastic quantization and gauge-fixing of the linearized gravitational field
International Nuclear Information System (INIS)
Hueffel, H.; Rumpf, H.
1984-01-01
Due to the indefiniteness of the Euclidean gravitational action the Parisi-Wu stochastic quantization scheme fails in the case of the gravitational field. Therefore we apply a recently proposed modification of stochastic quantization that works in Minkowski space and preserves all the advantages of the original Parisi-Wu method; in particular no gauge-fixing is required. Additionally stochastic gauge-fixing may be introduced and is also studied in detail. The graviton propagators obtained with and without stochastic gauge-fixing all exhibit a noncausal contribution, but apart from this effect the gauge-invariant quantities are the same as those of standard quantization. (Author)
d and f electrons in a qp-quantized cubical field
International Nuclear Information System (INIS)
Kibler, M.; Sztucki, J.
1993-03-01
A procedure for qp-quantizing a crystal-field potential V with an arbitrary symmetry G is developed. Such a procedure is applied to the case where V involves cubic components (G=0) of the degrees 4 and 6. This case corresponds to d and f electrons in a qp-quantized cubical potential. It is shown that the qp-quantization of the considered cubical potential is equivalent to a symmetry breaking of type O→D 4 . A general conjecture about this symmetry breaking phenomenon is given. (author) 21 refs
Scalar field critical collapse in 2+1 dimensions
Jałmużna, Joanna; Gundlach, Carsten; Chmaj, Tadeusz
2015-01-01
We carry out numerical experiments in the critical collapse of a spherically symmetric massless scalar field in 2+1 spacetime dimensions in the presence of a negative cosmological constant and compare them against a new theoretical model. We approximate the true critical solution as the $n=4$ Garfinkle solution, matched at the lightcone to a Vaidya-like solution, and corrected to leading order for the effect of $\\Lambda
Ermakov-Pinney equation in scalar field cosmologies
International Nuclear Information System (INIS)
Hawkins, Rachael M.; Lidsey, James E.
2002-01-01
It is shown that the dynamics of cosmologies sourced by a mixture of perfect fluids and self-interacting scalar fields are described by the nonlinear, Ermakov-Pinney equation. The general solution of this equation can be expressed in terms of particular solutions to a related, linear differential equation. This characteristic is employed to derive exact cosmologies in the inflationary and quintessential scenarios. The relevance of the Ermakov-Pinney equation to the braneworld scenario is discussed
Coupled oscillators as models of phantom and scalar field cosmologies
International Nuclear Information System (INIS)
Faraoni, Valerio
2004-01-01
We study a toy model for phantom cosmology recently introduced in the literature and consisting of two oscillators, one of which carries negative kinetic energy. The results are compared with the exact phase space picture obtained for similar dynamical systems describing, respectively, a massive canonical scalar field conformally coupled to the spacetime curvature and a conformally coupled massive phantom. Finally, the dynamical system describing exactly a minimally coupled phantom is studied and compared with the toy model
Higgs particles interacting via a scalar Dark Matter field
Directory of Open Access Journals (Sweden)
Bhattacharya Yajnavalkya
2016-01-01
Full Text Available We study a system of two Higgs particles, interacting via a scalar Dark Matter mediating field. The variational method in the Hamiltonian formalism of QFT is used to derive relativistic wave equations for the two-Higgs system, using a truncated Fock-space trial state. Approximate solutions of the two-body equations are used to examine the existence of Higgs bound states.
On dipole interaction of the oxcillator with a scalar field
International Nuclear Information System (INIS)
Razumov, A.V.; Taranov, A.Yu.
1979-01-01
Dipole interaction of the oscillator with scalar field in one-dimensional case is studied. Solutions of the classical equations of motion are found and the conditions of the boundedness of the classical Hamiltonian from below are obtained. In the quantum theory the problem of choosing the zeroth approximation of perturbation theory in the case when the spectra of the free and complete Hamiltonian do not coincide with each other, is analysed
Functional equations and Green's functions for augmented scalar fields
International Nuclear Information System (INIS)
Klauder, J.R.
1977-01-01
Certain noncanonical self-coupled scalar quantum field theories, previously formulated by means of functional integration, are herein recast into the form of functional differential equations for the Green's functional. From these expressions the set of coupled equations relating the Green's functions is obtained. The new equations are compared with those of the conventional formulation, and are proposed as alternatives, especially for nonrenormalizable models when the conventional equations fail
Field-Theoretic Weyl Deformation Quantization of Enlarged Poisson Algebras
Directory of Open Access Journals (Sweden)
Lothar Schlafer
2008-05-01
Full Text Available C*-algebraic Weyl quantization is extended by allowing also degenerate pre-symplectic forms for the Weyl relations with infinitely many degrees of freedom, and by starting out from enlarged classical Poisson algebras. A powerful tool is found in the construction of Poisson algebras and non-commutative twisted Banach-*-algebras on the stage of measures on the not locally compact test function space. Already within this frame strict deformation quantization is obtained, but in terms of Banach-*-algebras instead of C*-algebras. Fourier transformation and representation theory of the measure Banach-*-algebras are combined with the theory of continuous projective group representations to arrive at the genuine C*-algebraic strict deformation quantization in the sense of Rieffel and Landsman. Weyl quantization is recognized to depend in the first step functorially on the (in general infinite dimensional, pre-symplectic test function space; but in the second step one has to select a family of representations, indexed by the deformation parameter h. The latter ambiguity is in the present investigation connected with the choice of a folium of states, a structure, which does not necessarily require a Hilbert space representation.
Production of particles by a variable scalar field
International Nuclear Information System (INIS)
Dolgov, A.D.; Kirilova, D.P.
1990-01-01
The probability of particle production by a spatially homogeneous scalar field χ(t) is calculated. Explicit analytic expressions are obtained in two opposite limiting cases: in perturbation theory and in the quasiclassical approximation. It is shown that if the mass of the produced particles is determined by the field χ(t) is accordance with the expression gχ(t) anti ψψ, then for an oscillatory field χ(t) = χ 0 cos(ωt) the production probability in the limit of small ω is suppressed not exponentially, but only as ω 1/2 . Cosmological applications of these results are discussed
Study of inflationary generalized cosmic Chaplygin gas for standard and tachyon scalar fields
Energy Technology Data Exchange (ETDEWEB)
Sharif, M.; Saleem, Rabia [University of the Punjab, Department of Mathematics, Lahore (Pakistan)
2014-07-15
We consider an inflationary universe model in the context of the generalized cosmic Chaplygin gas by taking the matter field as standard and tachyon scalar fields. We evaluate the corresponding scalar fields and scalar potentials during the intermediate and logamediate inflationary regimes by modifying the first Friedmann equation. In each case, we evaluate the number of e-folds, scalar as well as tensor power spectra, scalar spectral index, and the important observational parameter, the tensor-scalar ratio in terms of inflation. The graphical behavior of this parameter shows that the model remains incompatible with WMAP7 and Planck observational data in each case. (orig.)
Study of inflationary generalized cosmic Chaplygin gas for standard and tachyon scalar fields
International Nuclear Information System (INIS)
Sharif, M.; Saleem, Rabia
2014-01-01
We consider an inflationary universe model in the context of the generalized cosmic Chaplygin gas by taking the matter field as standard and tachyon scalar fields. We evaluate the corresponding scalar fields and scalar potentials during the intermediate and logamediate inflationary regimes by modifying the first Friedmann equation. In each case, we evaluate the number of e-folds, scalar as well as tensor power spectra, scalar spectral index, and the important observational parameter, the tensor-scalar ratio in terms of inflation. The graphical behavior of this parameter shows that the model remains incompatible with WMAP7 and Planck observational data in each case. (orig.)
Background field method for nonlinear σ-model in stochastic quantization
International Nuclear Information System (INIS)
Nakazawa, Naohito; Ennyu, Daiji
1988-01-01
We formulate the background field method for the nonlinear σ-model in stochastic quantization. We demonstrate a one-loop calculation for a two-dimensional non-linear σ-model on a general riemannian manifold based on our formulation. The formulation is consistent with the known results in ordinary quantization. As a simple application, we also analyse the multiplicative renormalization of the O(N) nonlinear σ-model. (orig.)
Computing the scalar field couplings in 6D supergravity
Saidi, El Hassan
2008-11-01
Using non-chiral supersymmetry in 6D space-time, we compute the explicit expression of the metric the scalar manifold SO(1,1)×{SO(4,20)}/{SO(4)×SO(20)} of the ten-dimensional type IIA superstring on generic K3. We consider as well the scalar field self-couplings in the general case where the non-chiral 6D supergravity multiplet is coupled to generic n vector supermultiplets with moduli space SO(1,1)×{SO(4,n)}/{SO(4)×SO(n)}. We also work out a dictionary giving a correspondence between hyper-Kähler geometry and the Kähler geometry of the Coulomb branch of 10D type IIA on Calabi-Yau threefolds. Others features are also discussed.
Synthesis of magnetic systems producing field with maximal scalar characteristics
International Nuclear Information System (INIS)
Klevets, Nickolay I.
2005-01-01
A method of synthesis of the magnetic systems (MSs) consisting of uniformly magnetized blocks is proposed. This method allows to synthesize MSs providing maximum value of any magnetic field scalar characteristic. In particular, it is possible to synthesize the MSs providing the maximum of a field projection on a given vector, a gradient of a field modulus and a gradient of a field energy on a given directing vector, a field magnitude, a magnetic flux through a given surface, a scalar product of a field or a force by a directing function given in some area of space, etc. The synthesized MSs provide maximal efficiency of permanent magnets utilization. The usage of the proposed method of MSs synthesis allows to change a procedure of projecting in principal, namely, to execute it according to the following scheme: (a) to choose the sizes, a form and a number of blocks of a system proceeding from technological (economical) reasons; (b) using the proposed synthesis method, to find an orientation of site magnetization providing maximum possible effect of magnet utilization in a system obtained in (a). Such approach considerably reduces a time of MSs projecting and guarantees maximal possible efficiency of magnets utilization. Besides it provides absolute assurance in 'ideality' of a MS design and allows to obtain an exact estimate of the limit parameters of a field in a working area of a projected MS. The method is applicable to a system containing the components from soft magnetic material with linear magnetic properties
International Nuclear Information System (INIS)
Srivastava, P.P.
1993-01-01
The field theory quantized on the light-front is compared with the conventional equal-time quantized theory. The arguments based on the micro causality principle would imply that the light-front field theory may become nonlocal with respect to the longitudinal coordinate even though the corresponding equal-time formulation is local. This is found to be the case for the scalar theory. The conventional instant form theory is sometimes required to be constrained by invoking external physical considerations; the analogous conditions seem to be already built in the theory on the light-front. In spite of the different mechanisms of the spontaneous symmetry breaking in the two forms of dynamics they result in the same physical content. The phase transition in (φ 4 ) 2 theory is also discussed. The symmetric vacuum state for vanishingly small couplings is found to turn into an unstable symmetric one when the coupling is increased and may result in a phase transition of the second order in contrast to the first order transition concluded from the usual variational methods. (author)
Classical limit for scalar fields at high temperature
International Nuclear Information System (INIS)
Buchmueller, W.; Jakovac, A.
1998-01-01
We study real-time correlation functions in scalar quantum field theories at temperature T=1/β. We show that the behaviour of soft, long-wavelength modes is determined by classical statistical field theory. The loss of quantum coherence is due to interactions with the soft modes of the thermal bath. The soft modes are separated from the hard modes by an infrared cutoff Λ<<1/(ℎβ). Integrating out the hard modes yields an effective theory for the soft modes. The infrared cutoff Λ controls corrections to the classical limit which are O(ℎβΛ). As an application, the plasmon damping rate is calculated. (orig.)
Conformal conservation laws for second-order scalar fields
International Nuclear Information System (INIS)
Blakeskee, J.S.; Logan, J.D.
1976-01-01
It is considered an action integral over space-time whose Lagrangian depends upon a scalar field an upon derivatives of the field function up to second order. From invariance identities obtained by the authors in an earlier work it is shown how a new proof of Noether's theorem for this second-order problem follows in the multiple integral case. Finally, conservation laws are written down in the case that the given action integral be invariant under the fifteen-parameter special conformal group
On particle creation by a time-dependent scalar field
International Nuclear Information System (INIS)
Dolgov, A.D.; Kirilova, D.P.
1989-01-01
The probability of particles creation by a homogeneous scalar field Χ (t) is calculated. Explicit analytical expressions are obtained in two limiting cases in the quasiclassical approximation and in the framework of perturbation theory. In the case when the mass of the created particles is defined by the time-dependent field Χ (t) according to the expression g Χ (t) Ψ-barΨ, where Χ (t) =Χ 0 cos (ωt), it is shown that the creation probability is suppresed not exponentially, but as ω 1/2 . Some cosmological consequences of the results are discussed. 13 refs
Unitarity constraints in the standard model with a singlet scalar field
International Nuclear Information System (INIS)
Kang, Sin Kyu; Park, Jubin
2015-01-01
Motivated by the discovery of a new scalar field and amelioration of the electroweak vacuum stability ascribed to a singlet scalar field embedded in the standard model (SM), we examine the implication of the perturbative unitarity in the SM with a singlet scalar field. Taking into account the full contributions to the scattering amplitudes, we derive unitarity conditions on the scattering matrix which can be translated into bounds on the masses of the scalar fields. In the case that the singlet scalar field develops vacuum expectation value (VEV), we get the upper bound on the singlet scalar mass varying with the mixing between the singlet and Higgs scalars. On the other hand, the mass of the Higgs scalar can be constrained by the unitarity condition in the case that the VEV of the singlet scalar is not generated. Applying the upper bound on the Higgs mass to the scenario of the unitarized Higgs inflation, we discuss how the unitarity condition can constrain the Higgs inflation. The singlet scalar mass is not constrained by the unitarity itself when we impose Z 2 in the model because of no mixing with the Higgs scalar. But, regarding the singlet scalar field as a cold dark matter candidate, we derive upper bound on the singlet scalar mass by combining the observed relic abundance with the unitarity condition.
Relativistic gravitation from massless systems of scalar and vector fields
International Nuclear Information System (INIS)
Fonseca Teixeira, A.F. da.
1979-01-01
Under the laws of Einstein's gravitational theory, a massless system consisting of the diffuse sources of two fields is discussed. One fields is scalar, of long range, the other is a vector field of short range. A proportionality between the sources is assumed. Both fields are minimally coupled to gravitation, and contribute positive definitely to the time component of the energy momentum tensor. A class of static, spherically symmetric solutions of the equations is obtained, in the weak field limit. The solutions are regular everywhere, stable, and can represent large or small physical systems. The gravitational field presents a Schwarzschild-type asymptotic behavior. The dependence of the energy on the various parameters characterizing the system is discussed in some detail. (Author) [pt
Scalar-field amplitudes in black-hole evaporation
International Nuclear Information System (INIS)
Farley, A.N.St.J.; D'Eath, P.D.
2004-01-01
We consider the quantum-mechanical decay of a Schwarzschild-like black hole into almost-flat space and weak radiation at a very late time. That is, we are concerned with evaluating quantum amplitudes (not just probabilities) for transitions from initial to final states. In this quantum description, no information is lost because of the black hole. The Lagrangian is taken, in the first instance, to consist of the simplest locally supersymmetric generalization of Einstein gravity and a massless scalar field. The quantum amplitude to go from given initial to final bosonic data in a slightly complexified time-interval T=τexp(-iθ) at infinity may be approximated by the form constxexp(-I), where I is the (complex) Euclidean action of the classical solution filling in between the boundary data. Additionally, in a pure supergravity theory, the amplitude constxexp(-I) is exact. Suppose that Dirichlet boundary data for gravity and the scalar field are posed on an initial spacelike hypersurface extending to spatial infinity, just prior to collapse, and on a corresponding final spacelike surface, sufficiently far to the future of the initial surface to catch all the Hawking radiation. Only in an averaged sense will this radiation have an approximately spherically-symmetric distribution. If the time-interval T had been taken to be exactly real, then the resulting 'hyperbolic Dirichlet boundary-value problem' would, as is well known, not be well posed. Provided instead ('Euclidean strategy') that one takes T complex, as above (0<θ=<π/2), one expects that the field equations become strongly elliptic, and that there exists a unique solution to the classical boundary-value problem. Within this context, by expanding the bosonic part of the action to quadratic order in perturbations about the classical solution, one obtains the quantum amplitude for weak-field final configurations, up to normalization. Such amplitudes are here calculated for weak final scalar fields
Conditional expectations on the von Neumann algebras and causal independence of quantized fields
International Nuclear Information System (INIS)
Dadashyan, K.Yu.; Khoruzhij, S.S.
1981-01-01
Implementation of the condition of casual independence of quantized fields has been established for a number of quantum-field systems. Implementation of a property of the Haag-Castler casual independence has been proved for a net of the von Neumann local algebras in a number of models of free and quantized fields interacting in the Fock local way. In particular, proved is a theorem of meeting the condition of casual independence with the net of local albegras of the Dirac free field. A new method based on the techniques of noncommutative probability law has been used for the proof [ru
International Nuclear Information System (INIS)
Lobashev, A.A.; Mostepanenko, V.M.
1993-01-01
Heisenberg formalism is developed for creation-annihilation operators of quantum fields propagating in nonstationary external fields. Quantum fields with spin 0,1/2, 1 are considered in the presence of such external fields as electromagnetic, scalar and the field of nonstationary dielectric properties of nonlinear medium. Elliptic operator parametrically depending on time is constructed. In Heisenberg representation field variables are decomposed over eigenfunction of this operator. The relation between Heisenberg creation-annihilation operators and the operators obtained in the frame of diagonalization of Hamiltonian with Bogoliubov transformations is set up
Renormalization of an abelian gauge theory in stochastic quantization
International Nuclear Information System (INIS)
Chaturvedi, S.; Kapoor, A.K.; Srinivasan, V.
1987-01-01
The renormalization of an abelian gauge field coupled to a complex scalar field is discussed in the stochastic quantization method. The super space formulation of the stochastic quantization method is used to derive the Ward Takahashi identities associated with supersymmetry. These Ward Takahashi identities together with previously derived Ward Takahashi identities associated with gauge invariance are shown to be sufficient to fix all the renormalization constants in terms of scaling of the fields and of the parameters appearing in the stochastic theory. (orig.)
An axion-like scalar field environment effect on binary black hole merger
Yang, Qing; Ji, Li-Wei; Hu, Bin; Cao, Zhou-Jian; Cai, Rong-Gen
2018-06-01
The environment, such as an accretion disk, could modify the signal of the gravitational wave from astrophysical black hole binaries. In this article, we model the matter field around intermediate-mass binary black holes by means of an axion-like scalar field and investigate their joint evolution. In detail, we consider equal mass binary black holes surrounded by a shell of axion-like scalar field both in spherically symmetric and non-spherically symmetric cases, and with different strengths of the scalar field. Our result shows that the environmental scalar field could essentially modify the dynamics. Firstly, in the spherically symmetric case, with increase of the scalar field strength, the number of circular orbits for the binary black hole is reduced. This means that the scalar field could significantly accelerate the merger process. Secondly, once the scalar field strength exceeds a certain critical value, the scalar field could collapse into a third black hole with its mass being larger than that of the binary. Consequently, the new black hole that collapses from the environmental scalar field could accrete the binary promptly and the binary collides head-on with each other. In this process, there is almost no quadrupole signal produced, and, consequently, the gravitational wave is greatly suppressed. Thirdly, when the scalar field strength is relatively smaller than the critical value, the black hole orbit could develop eccentricity through accretion of the scalar field. Fourthly, during the initial stage of the inspiral, the gravitational attractive force from the axion-like scalar field could induce a sudden turn in the binary orbits, hence resulting in a transient wiggle in the gravitational waveform. Finally, in the non-spherical case, the scalar field could gravitationally attract the binary moving toward the center of mass for the scalar field and slow down the merger process.
The extended local gauge invariance and the BRS symmetry in stochastic quantization of gauge fields
International Nuclear Information System (INIS)
Nakazawa, Naohito.
1989-05-01
We investigate the BRS invariance of the first-class constrained systems in the context of the stochastic quantization. For the first-class constrained systems, we construct the nilpotent BRS transformation and the BRS invariant stochastic effective action based on the D+1 dimensional field theoretical formulation of stochastic quantization. By eliminating the multiplier field of the gauge fixing condition and an auxiliary field, it is shown that there exists a truncated BRS transformation which satisfies the nilpotency condition. The truncated BRS invariant stochastic action is also derived. As the examples of the general formulation, we investigate the BRS invariant structure in the massless and massive Yang-Mills fields in stochastic quantization. (author)
Scalar fields and higher-derivative gravity in brane worlds
International Nuclear Information System (INIS)
Pichler, S.
2004-01-01
We consider the brane world picture in the context of higher-derivative theories of gravity and tackle the problematic issues fine-tuning and brane-embedding. First, we give an overview of extra-dimensional physics, from the Kaluza-Klein picture up to modern brane worlds with large extra dimensions. We describe the different models and their physical impact on future experiments. We work within the framework of Randall-Sundrum models in which the brane is a gravitating object, which warps the background metric. We add scalar fields to the original model and find new and self-consistent solutions for quadratic potentials of the fields. This gives us the tools to investigate higher-derivative gravity theories in brane world models. Specifically, we take gravitational Lagrangians that depend on an arbitrary function of the Ricci scalar only, so-called f(R)-gravity. We make use of the conformal equivalence between f(R)-gravity and Einstein-Hilbert gravity with an auxiliary scalar field. We find that the solutions in the higher-derivative gravity framework behave very differently from the original Randall-Sundrum model: the metric functions do not have the typical kink across the brane. Furthermore, we present solutions that do not rely on a cosmological constant in the bulk and so avoid the fine-tuning problem. We address the issue of brane-embedding, which is important in perturbative analyses. We consider the embedding of codimension one hypersurfaces in general and derive a new equation of motion with which the choice for the embedding has to comply. In particular, this allows for a consistent consideration of brane world perturbations in the case of higher-derivative gravity. We use the newly found background solutions for quadratic potentials and find that gravity is still effectively localized on the brane, i.e that the Newtonian limit holds
Topological geons with self-gravitating phantom scalar field
Kratovitch, P. V.; Potashov, I. M.; Tchemarina, Ju V.; Tsirulev, A. N.
2017-12-01
A topological geon is the quotient manifold M/Z 2 where M is a static spherically symmetric wormhole having the reflection symmetry with respect to its throat. We distinguish such asymptotically at solutions of the Einstein equations according to the form of the time-time metric function by using the quadrature formulas of the so-called inverse problem for self-gravitating spherically symmetric scalar fields. We distinguish three types of geon spacetimes and illustrate them by simple examples. We also study possible observational effects associated with bounded geodesic motion near topological geons.
Non-relativistic scalar field on the quantum plane
International Nuclear Information System (INIS)
Jahan, A.
2005-01-01
We apply the coherent state approach to the non-commutative plane to check the one-loop finiteness of the two-point and four-point functions of a non-relativistic scalar field theory in 2+1 dimensions. We show that the two-point and four-point functions of the model are finite at one-loop level and one recovers the divergent behavior of the model in the limit θ->0 + by appropriate redefinition of the non-commutativity parameter
On the stability of solitary waves for classical scalar fields
International Nuclear Information System (INIS)
Blanchard, P.; Stubbe, J.; Vazquez, L.
1986-01-01
We study the stability for the bound states of lowest action of certain nonlinear Klein-Gordon and Schroedinger equations by applying the Shatah-Strauss formalism. We extend the range of application of this formalism by using a recent existence theorem for minimum action solutions to a large class of equations including logarithmic Klein-Gordon equation and logarithmic Schroedinger equation and scalar fields with fractional non-linearities. Furthermore we discuss the relation between different stability criteria considered in the literature. (orig.)
Scalar field collapse in a conformally flat spacetime
Energy Technology Data Exchange (ETDEWEB)
Chakrabarti, Soumya; Banerjee, Narayan [Indian Institute of Science Education and Research, Kolkata, Department of Physical Sciences, Mohanpur, West Bengal (India)
2017-03-15
The collapse scenario of a scalar field along with a perfect fluid distribution was investigated for a conformally flat spacetime. The theorem for the integrability of an anharmonic oscillator has been utilized. For a pure power-law potential of the form φ{sup n+1}, it was found that a central singularity is formed which is covered by an apparent horizon for n > 0 and n < -3. Some numerical results have also been presented for a combination of two different powers of φ in the potential. (orig.)
Symplectic geometry of field theories and covariant quantization of superstrings and superparticles
International Nuclear Information System (INIS)
Crnkovic, C.
1987-01-01
A detailed development of the symplectic geometry formalism for a general Lagrangian field theory is presented. Special attention is paid to the theories with constraints and/or gauge degrees of freedom. Special cases of Yang-Mills theory, general relativity and Witten's string field theory are studied and the generators of (super-) Poincare transformations are derived using their respective symplectic forms. The formalism extends naturally to theories formulated in the superspace. The second part of the thesis deals with issues in covariant quantization. By studying the symplectic geometry of the Green-Schwarz covariant superstring action, we elucidate some aspects of its covariant quantization. We derive the on-shell gauge-fixed action and the equations of motion for all the fields. Finally, turning to Siegel's version of the superparticle action, we perform its BRST quantization
A new approach to quantum field theory and a spacetime quantization
International Nuclear Information System (INIS)
Banai, I.
1982-09-01
A quantum logical approach to achieve a sound kinematical picture for LQFT (local quantum field theory) is reviewed. Then a general language in the framework of axiomatic set theory is presented, in which the 'local' description of a LQFT can be formulated in almost the same form as quantum mechanics was formulated by von Neumann. The main physical implication of this approach is that, in this framework, the quantization of a CRLFT (classical relativistic local field theory) requires not only the quantization of physical fields over M 4 but the quantization of spacetime M 4 itself, too. The uncertainty priciple is compatible with the Heisenberg uncertainty principle, but it requires the generalization of Poincare symmetries to all unitary symmetries. Some indications show that his approach might be successful in describing low laying hadronic phenomena. (author)
Spectral analysis for systems of atoms and molecules coupled to the quantized radiation field
International Nuclear Information System (INIS)
Bach, V.; Sigal, I.M.
1999-01-01
We consider systems of static nuclei and electrons - atoms and molecules - coupled to the quantized radiation field. The interactions between electrons and the soft modes of the quantized electromagnetic field are described by minimal coupling, p→p-eA(x), where A(x) is the electromagnetic vector potential with an ultraviolet cutoff. If the interactions between the electrons and the quantized radiation field are turned off, the atom or molecule is assumed to have at least one bound state. We prove that, for sufficiently small values of the fine structure constant α, the interacting system has a ground state corresponding to the bottom of its energy spectrum. For an atom, we prove that its excited states above the ground state turn into metastable states whose life-times we estimate. Furthermore the energy spectrum is absolutely continuous, except, perhaps,in a small interval above the ground state energy and around the threshold energies of the atom or molecule. (orig.)
Leading quantum gravitational corrections to scalar QED
Bjerrum-Bohr, N. E. J.
2002-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The n...
Linear spin-zero quantum fields in external gravitational and scalar fields
International Nuclear Information System (INIS)
Kay, B.S.
1977-11-01
A general formalism for quantizing the covariant Klein Gordon equation in an arbitrary globally hyperbolic space-time is presented. It is argued that much of the conceptual confusion surrounding ''quantum field theory in curved space-time'' has been caused by the misapplication of a quantization procedure (the single representation formalism) which is really only suitable for quantizing stationary systems. Drawing on a close analogy with time-dependent external field problems in flat space-time, it is argued for the introduction of a new quantization procedure: the many vacuum formalism which accommodates non-stationary situations. In the many vacuum formalism, a whole family of different representations of the field algebra plays a role and dynamics is necessarily described in terms of isomorphisms between different algebras rather than automorphisms of a single algebra. It is shown how this many vacuum approach gives physically sensible results in the flat space-time case. In the curved space-time case, corresponding well defined formalism is obtained relying on rigorous results established in I. A principal feature is that a different vacuum state is obtained for each choice of Cauchy surface together with a choice of lapse and shift functions on that surface. Several questions-mathematical and interpretational- raised by the scheme are discussed
International Nuclear Information System (INIS)
Tsoupros, George
2002-01-01
The character of quantum corrections to the gravitational action of a conformally invariant field theory for a self-interacting scalar field on a manifold with boundary is considered at third loop-order in the perturbative expansion of the zero-point function. Diagramatic evaluations and higher loop-order renormalization can be best accomplished on a Riemannian manifold of positive constant curvature accommodating a boundary of constant extrinsic curvature. The associated spherical formulation for diagramatic evaluations reveals a non-trivial effect which the topology of the manifold has on the vacuum processes and which ultimately dissociates the dynamical behaviour of the quantized field from its behaviour in the absence of a boundary. The first surface divergence is evaluated and the necessity for simultaneous renormalization of volume and surface divergences is shown
A unique Fock quantization for fields in non-stationary spacetimes
International Nuclear Information System (INIS)
Cortez, Jerónimo; Marugán, Guillermo A. Mena; Olmedo, Javier; Velhinho, José M.
2010-01-01
In curved spacetimes, the lack of criteria for the construction of a unique quantization is a fundamental problem undermining the significance of the predictions of quantum field theory. Inequivalent quantizations lead to different physics. Recently, however, some uniqueness results have been obtained for fields in non-stationary settings. In particular, for vacua that are invariant under the background symmetries, a unitary implementation of the classical evolution suffices to pick up a unique Fock quantization in the case of Klein-Gordon fields with time-dependent mass, propagating in a static spacetime whose spatial sections are three-spheres. In fact, the field equation can be reinterpreted as describing the propagation in a Friedmann-Robertson-Walker spacetime after a suitable scaling of the field by a function of time. For this class of fields, we prove here an even stronger result about the Fock quantization: the uniqueness persists when one allows for linear time-dependent transformations of the field in order to account for a scaling by background functions. In total, paying attention to the dynamics, there exists a preferred choice of quantum field, and only one SO(4)-invariant Fock representation for it that respects the standard probabilistic interpretation along the evolution. The result has relevant implications e.g. in cosmology
Unified Dark Matter scalar field models with fast transition
Energy Technology Data Exchange (ETDEWEB)
Bertacca, Daniele [Dipartimento di Fisica Galileo Galilei, Università di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Bruni, Marco [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom); Piattella, Oliver F. [Department of Physics, Universidade Federal do Espírito Santo, avenida Ferrari 514, 29075-910, Vitória, ES (Brazil); Pietrobon, Davide, E-mail: daniele.bertacca@pd.infn.it, E-mail: marco.bruni@port.ac.uk, E-mail: oliver.piattella@gmail.com, E-mail: davide.pietrobon@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, 91109 Pasadena CA U.S.A. (United States)
2011-02-01
We investigate the general properties of Unified Dark Matter (UDM) scalar field models with Lagrangians with a non-canonical kinetic term, looking specifically for models that can produce a fast transition between an early Einstein-de Sitter CDM-like era and a later Dark Energy like phase, similarly to the barotropic fluid UDM models in JCAP01(2010)014. However, while the background evolution can be very similar in the two cases, the perturbations are naturally adiabatic in fluid models, while in the scalar field case they are necessarily non-adiabatic. The new approach to building UDM Lagrangians proposed here allows to escape the common problem of the fine-tuning of the parameters which plague many UDM models. We analyse the properties of perturbations in our model, focusing on the the evolution of the effective speed of sound and that of the Jeans length. With this insight, we can set theoretical constraints on the parameters of the model, predicting sufficient conditions for the model to be viable. An interesting feature of our models is that what can be interpreted as w{sub DE} can be < −1 without violating the null energy conditions.
Conserved charges of minimal massive gravity coupled to scalar field
Setare, M. R.; Adami, H.
2018-02-01
Recently, the theory of topologically massive gravity non-minimally coupled to a scalar field has been proposed, which comes from the Lorentz-Chern-Simons theory (JHEP 06, 113, 2015), a torsion-free theory. We extend this theory by adding an extra term which makes the torsion to be non-zero. We show that the BTZ spacetime is a particular solution to this theory in the case where the scalar field is constant. The quasi-local conserved charge is defined by the concept of the generalized off-shell ADT current. Also a general formula is found for the entropy of the stationary black hole solution in context of the considered theory. The obtained formulas are applied to the BTZ black hole solution in order to obtain the energy, the angular momentum and the entropy of this solution. The central extension term, the central charges and the eigenvalues of the Virasoro algebra generators for the BTZ black hole solution are thus obtained. The energy and the angular momentum of the BTZ black hole using the eigenvalues of the Virasoro algebra generators are calculated. Also, using the Cardy formula, the entropy of the BTZ black hole is found. It is found that the results obtained in two different ways exactly match, just as expected.
Scalar meson field and many-body forces. Chapter 23
International Nuclear Information System (INIS)
Nyman, E.M.
1979-01-01
In applications of field theory to the theory of the nuclear forces, one has frequently assumed that there is a scalar meson. It will then be responsible for most of the medium-range attraction between the nucleons. According to current ideas, however, it is possible to account for the medium-range attraction without an elementary sigma meson. This approach requires a careful treatment of the exchange of interacting pairs of π mesons, such as to include those ππ interactions which are responsible for the formation and decay of the sigma meson. Recently, the scalar field in the nuclear many-body problem has begun to receive more attention. There are two reasons for this change of philosophy. One reason is the discovery of neutron stars. In neutron stars, the nucleon number density can be much higher than in nuclei. One therefore wants to derive the equation of state from a relativistic many-body theory. This forces one to deal explicitly with a set of mesons, such that in the non-relativistic limit one recovers the one-boson-exchange potential. (Auth.)
Conserved charges of minimal massive gravity coupled to scalar field
International Nuclear Information System (INIS)
Setare, M.R.; Adami, H.
2018-01-01
Recently, the theory of topologically massive gravity non-minimally coupled to a scalar field has been proposed, which comes from the Lorentz-Chern-Simons theory (JHEP 06, 113, 2015), a torsion-free theory. We extend this theory by adding an extra term which makes the torsion to be non-zero. We show that the BTZ spacetime is a particular solution to this theory in the case where the scalar field is constant. The quasi-local conserved charge is defined by the concept of the generalized off-shell ADT current. Also a general formula is found for the entropy of the stationary black hole solution in context of the considered theory. The obtained formulas are applied to the BTZ black hole solution in order to obtain the energy, the angular momentum and the entropy of this solution. The central extension term, the central charges and the eigenvalues of the Virasoro algebra generators for the BTZ black hole solution are thus obtained. The energy and the angular momentum of the BTZ black hole using the eigenvalues of the Virasoro algebra generators are calculated. Also, using the Cardy formula, the entropy of the BTZ black hole is found. It is found that the results obtained in two different ways exactly match, just as expected. (orig.)
Spikes and matter inhomogeneities in massless scalar field models
International Nuclear Information System (INIS)
Coley, A A; Lim, W C
2016-01-01
We shall discuss the general relativistic generation of spikes in a massless scalar field or stiff perfect fluid model. We first investigate orthogonally transitive (OT) G 2 stiff fluid spike models both heuristically and numerically, and give a new exact OT G 2 stiff fluid spike solution. We then present a new two-parameter family of non-OT G 2 stiff fluid spike solutions, obtained by the generalization of non-OT G 2 vacuum spike solutions to the stiff fluid case by applying Geroch’s transformation on a Jacobs seed. The dynamics of these new stiff fluid spike solutions is qualitatively different from that of the vacuum spike solutions in that the matter (stiff fluid) feels the spike directly and the stiff fluid spike solution can end up with a permanent spike. We then derive the evolution equations of non-OT G 2 stiff fluid models, including a second perfect fluid, in full generality, and briefly discuss some of their qualitative properties and their potential numerical analysis. Finally, we discuss how a fluid, and especially a stiff fluid or massless scalar field, affects the physics of the generation of spikes. (paper)
Conserved charges of minimal massive gravity coupled to scalar field
Energy Technology Data Exchange (ETDEWEB)
Setare, M.R.; Adami, H. [University of Kurdistan, Department of Science, Sanandaj (Iran, Islamic Republic of)
2018-02-15
Recently, the theory of topologically massive gravity non-minimally coupled to a scalar field has been proposed, which comes from the Lorentz-Chern-Simons theory (JHEP 06, 113, 2015), a torsion-free theory. We extend this theory by adding an extra term which makes the torsion to be non-zero. We show that the BTZ spacetime is a particular solution to this theory in the case where the scalar field is constant. The quasi-local conserved charge is defined by the concept of the generalized off-shell ADT current. Also a general formula is found for the entropy of the stationary black hole solution in context of the considered theory. The obtained formulas are applied to the BTZ black hole solution in order to obtain the energy, the angular momentum and the entropy of this solution. The central extension term, the central charges and the eigenvalues of the Virasoro algebra generators for the BTZ black hole solution are thus obtained. The energy and the angular momentum of the BTZ black hole using the eigenvalues of the Virasoro algebra generators are calculated. Also, using the Cardy formula, the entropy of the BTZ black hole is found. It is found that the results obtained in two different ways exactly match, just as expected. (orig.)
Quantization of the minimal and non-minimal vector field in curved space
Toms, David J.
2015-01-01
The local momentum space method is used to study the quantized massive vector field (the Proca field) with the possible addition of non-minimal terms. Heat kernel coefficients are calculated and used to evaluate the divergent part of the one-loop effective action. It is shown that the naive expression for the effective action that one would write down based on the minimal coupling case needs modification. We adopt a Faddeev-Jackiw method of quantization and consider the case of an ultrastatic...
The Berry phase in GaAs semiconductor with a quantized field
International Nuclear Information System (INIS)
Chen Gang; Chen Zidong; Yu Lixian
2007-01-01
In this paper we investigate the Berry phase in GaAs semiconductor with a quantized magnetic field in the rotating wave approximation. The eigenfunctions of the nuclear spin in the quantized external field are obtained and thus the Berry phase is evaluated explicitly in terms of the introduction of the phase shift. It is shown that the Berry phase can be easily controlled by the coupling strength, the anisotropy constant and the frequency of the electromagnetic wave, which can be important in applications in geometric quantum computing
Quantization of spin-two field in terms of Fierz variables the linear case
International Nuclear Information System (INIS)
Novello, M.; Freitas, L.R. de; Neto, N.P.; Svaiter, N.F.
1991-01-01
We give a complete self-contained presentation of the description of spin-two fields using Fierz variables A sub(α β μ) instead of the conventional standard approach which deals with second order symmetric tensor φ sub(μ ν). After a short review of the classical properties of the Gierz field we present the quantization procedure. The theory presents a striking similitude with electrodynamics which induced us to follow analogy with the Fermi-Gupta-Breuler scheme of quantization. (author)
Nelson's stochastic quantization of free linearized gravitational field and its Markovian structure
International Nuclear Information System (INIS)
Lim, S.C.
1983-05-01
It is shown that by applying Nelson's stochastic quantization scheme to free linearized gravitational field tensor one can associate with the resulting stochastic system a stochastic tensor field which coincides with the ''space'' part of the Riemannian tensor in Euclidean space-time. However, such a stochastic field fails to satisfy the Markov property. Instead, it satisfies the reflection positivity. The Markovian structure of the stochastic fields associated with the electromagnetic field is also discussed. (author)
Coupled scalar fields in a flat FRW universe. Renormalisation
Energy Technology Data Exchange (ETDEWEB)
Baacke, Juergen [Technische Univ. Dortmund (Germany). Fakultaet Physik; Covi, Laura [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kevlishvili, Nina [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Andronikashvili Institute of Physics, Tbilisi (Georgia)
2010-06-15
We study the non-equilibrium dynamics of a system of coupled scalar fields in a Friedmann-Robertson-Walker (FRW) universe. We consider the evolution of spatially homogeneous ''classical'' fields and of their quantum fluctuations including the quantum backreaction in the one-loop approximation. We discuss in particular the dimensional regularisation of the coupled system and a special subtraction procedure in order to obtain the renormalised equations of motion and the renormalised energy-momentum tensor and ensure that the energy is well-defined and covariantly conserved. These results represent at the same time a theoretical analysis and a viable scheme for stable numerical simulations. As an example for an application of the general formalism, we present simulations for a hybrid inflationary model. (orig.)
Massless Interacting Scalar Fields in de Sitter space
López Nacir, Diana
2016-10-28
We present a method to compute the two-point functions for an $O(N)$ scalar field model in de Sitter spacetime, avoiding the well known infrared problems for massless fields. The method is based on an exact treatment of the Euclidean zero modes and a perturbative one of the nonzero modes, and involves a partial resummation of the leading secular terms. This resummation, crucial to obtain a decay of the correlation functions, is implemented along with a double expansion in an effective coupling constant $\\sqrt\\lambda$ and in $1/N$. The results reduce to those known in the leading infrared approximation and coincide with the ones obtained directly in Lorentzian de Sitter spacetime in the large $N$ limit. The new method allows for a systematic calculation of higher order corrections both in $\\sqrt\\lambda$ and in $1/N$.
Solitons of scalar field with induced nonlinearity and their stability
International Nuclear Information System (INIS)
Saha, B.
1999-09-01
Exact particle-like static, spherically and/or cylindrically symmetric solutions to the equations of interacting scalar and electromagnetic field system have been obtained. We considered FRW and Goedel universes as external gravitational field with spherical and cylindrical symmetry respectively. Beside the usual solitons some special regular solutions known as droplets, anti-droplets and hats (confined in finite interval and having trivial value beyond it) have been obtained. It has been shown that in FRW space-time equations with different interaction terms may have stable solutions while within the scope of Goedel model only the droplet-like and the hat-like configurations may be stable, providing that they are located in the region where g 00 > 0. (author)
Quantization of the Coulomb Chain in an External Focusing Field
International Nuclear Information System (INIS)
Kabel, Andreas C.
2001-01-01
With the appropriate choice of parameters and sufficient cooling, charged particles in a circular accelerator are believed to undergo a transition to a highly-ordered crystalline state[1]. The simplest possible crystalline configuration is a one-dimensional chain of particles. In this paper, we write down the quantized version of its dynamics. We show that in a low-density limit, the dynamics is that of a theory of interacting phonons. There is an infinite sequence of n-phonon interaction terms, we write down the first orders, which involve phonon scattering and decay processes. The quantum formulation developed here can serve as a first step towards a quantum-mechanical treatment of the system at finite temperatures
AdS Black Hole with Phantom Scalar Field
Directory of Open Access Journals (Sweden)
Limei Zhang
2017-01-01
Full Text Available We present an AdS black hole solution with Ricci flat horizon in Einstein-phantom scalar theory. The phantom scalar fields just depend on the transverse coordinates x and y, which are parameterized by the parameter α. We study the thermodynamics of the AdS phantom black hole. Although its horizon is a Ricci flat Euclidean space, we find that the thermodynamical properties of the black hole solution are qualitatively the same as those of AdS Schwarzschild black hole. Namely, there exists a minimal temperature and the large black hole is thermodynamically stable, while the smaller one is unstable, so there is a so-called Hawking-Page phase transition between the large black hole and the thermal gas solution in the AdS space-time in Poincare coordinates. We also calculate the entanglement entropy for a strip geometry dual to the AdS phantom black holes and find that the behavior of the entanglement entropy is qualitatively the same as that of the black hole thermodynamical entropy.
Stability of braneworlds with non-minimally coupled multi-scalar fields
Energy Technology Data Exchange (ETDEWEB)
Chen, Feng-Wei; Gu, Bao-Min [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Lanzhou University, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou (China); Liu, Yu-Xiao [Lanzhou University, Research Center of Gravitation, Lanzhou (China)
2018-02-15
Linear stability of braneworld models constructed with multi-scalar fields is very different from that of single-scalar field models. It is well known that both the tensor and the scalar perturbations of the latter are stable at linear level. However, in general there is no effective method to deal with the stability problem of the scalar perturbations for braneworld models constructed with non-minimally coupled multi-scalar fields. In this work we present a systematic covariant approach to deal with the scalar perturbations. By introducing the orthonormal bases in field space and making the Kaluza-Klein decomposition, we get a set of coupled Schroedinger-like equations of the scalar perturbation modes. Using the nodal theorem, we show that the result is model-dependent. For superpotential derived brane models, the scalar perturbations are stable, but there exist normalizable scalar zero modes, which will result in unacceptable fifth force on the brane. We also use this method to analyze the f(R) braneworld model with an explicit solution and find that the scalar perturbations are stable and the scalar zero modes cannot be localized on the brane, which ensures that there is no extra long-range force and the Newtonian potential on the brane can be recovered. (orig.)
Synthetic three-dimensional turbulent passive scalar fields via the minimal Lagrangian map
Rosales, Carlos
2011-07-01
A method for simple but realistic generation of three-dimensional synthetic turbulent passive scalar fields is presented. The method is an extension of the minimal turnover Lagrangian map approach (MTLM) [C. Rosales and C. Meneveau, Phys. Rev. E 78, 016313 (2008)] formulated for the generation of synthetic turbulent velocity fields. In this development, the minimal Lagrangian map is applied to deform simultaneously a vector field and an advected scalar field. This deformation takes place over a hierarchy of spatial scales encompassing a range from integral to dissipative scales. For each scale, fluid particles are mapped transporting the scalar property, without interaction or diffusional effects, from their initial configuration to new positions determined only by their velocity at the beginning of the motion and a parameter chosen to accumulate deformation for the equivalent of the phenomenological "turn-over" time scale. The procedure is studied for the case of inertial-convective regime. It is found that many features of passive scalar turbulence are well reproduced by this simple kinematical construction. Fundamental statistics of the resulting synthetic scalar fields, evaluated through the flatness and probability density functions of the scalar gradient and scalar increments, reproduce quite well the known statistical characteristics of passive scalars in turbulent fields. High-order statistics are also consistent with those observed in real hydrodynamic turbulence. The anomalous scaling of real turbulence is well reproduced for different kind of structure functions, with good quantitative agreement in general, for the scaling exponents. The spatial structure of the scalar field is also quite realistic, as well as several characteristics of the dissipation fields for the scalar variance and kinetic energy. Similarly, the statistical geometry at dissipative scales that ensues from the coupling of velocity and scalar gradients behaves in agreement with what is
A Note on Equivalence Among Various Scalar Field Models of Dark Energies
Mandal, Jyotirmay Das; Debnath, Ujjal
2017-08-01
In this work, we have tried to find out similarities between various available models of scalar field dark energies (e.g., quintessence, k-essence, tachyon, phantom, quintom, dilatonic dark energy, etc). We have defined an equivalence relation from elementary set theory between scalar field models of dark energies and used fundamental ideas from linear algebra to set up our model. Consequently, we have obtained mutually disjoint subsets of scalar field dark energies with similar properties and discussed our observation.
Neutron Star Structure in the Presence of Conformally Coupled Scalar Fields
Sultana, Joseph; Bose, Benjamin; Kazanas, Demosthenes
2014-01-01
Neutron star models are studied in the context of scalar-tensor theories of gravity in the presence of a conformally coupled scalar field, using two different numerical equations of state (EoS) representing different degrees of stiffness. In both cases we obtain a complete solution by matching the interior numerical solution of the coupled Einstein-scalar field hydrostatic equations, with an exact metric on the surface of the star. These are then used to find the effect of the scalar field and its coupling to geometry, on the neutron star structure, particularly the maximum neutron star mass and radius. We show that in the presence of a conformally coupled scalar field, neutron stars are less dense and have smaller masses and radii than their counterparts in the minimally coupled case, and the effect increases with the magnitude of the scalar field at the center of the star.
Greybody factor of scalar fields from black strings
Ahmed, Jamil; Saifullah, K.
2017-12-01
The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of the coupling constant. For this purpose we analyze the wave equation which is obtained from Klein-Gordon equation. The radial part of the wave equation is solved in the form of the hypergeometric function in the near horizon region, whereas in the far region the solution is of the form of Bessel's function. Finally, considering continuity of the wave function we smoothly match the two solutions in the low-energy approximation to get the formula for the absorption probability.
Free ◻{sup k} scalar conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Brust, Christopher [Perimeter Institute for Theoretical Physics,31 Caroline St. N, Waterloo, Ontario N2L 2Y5 (Canada); Hinterbichler, Kurt [CERCA, Department of Physics, Case Western Reserve University,10900 Euclid Ave, Cleveland, OH 44106 (United States)
2017-02-13
We consider the generalizations of the free U(N) and O(N) scalar conformal field theories to actions with higher powers of the Laplacian ◻{sup k}, in general dimension d. We study the spectra, Verma modules, anomalies and OPE of these theories. We argue that in certain d and k, the spectrum contains zero norm operators which are both primary and descendant, as well as extension operators which are neither primary nor descendant. In addition, we argue that in even dimensions d≤2k, there are well-defined operator algebras which are related to the ◻{sup k} theories and are novel in that they have a finite number of single-trace states.
Greybody factor of scalar fields from black strings
Energy Technology Data Exchange (ETDEWEB)
Ahmed, Jamil [Quaid-i-Azam University, Department of Mathematics, Islamabad (Pakistan); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); Saifullah, K. [Quaid-i-Azam University, Department of Mathematics, Islamabad (Pakistan); Harvard University, Center for the Fundamental Laws of Nature, Cambridge, MA (United States)
2017-12-15
The greybody factor of massless, uncharged scalar fields is studied in the background of cylindrically symmetric spacetimes, in the low-energy approximation. We discuss two cases. In the first case we derive analytical expression for the absorption probability when the spacetime is kinetically coupled with the Einstein tensor. In the second case we do the analysis in the absence of the coupling constant. For this purpose we analyze the wave equation which is obtained from Klein-Gordon equation. The radial part of the wave equation is solved in the form of the hypergeometric function in the near horizon region, whereas in the far region the solution is of the form of Bessel's function. Finally, considering continuity of the wave function we smoothly match the two solutions in the low-energy approximation to get the formula for the absorption probability. (orig.)
Extended BPH renormalization of cutoff scalar field theories
International Nuclear Information System (INIS)
Chalmers, G.
1996-01-01
We show through the use of diagrammatic techniques and a newly adapted BPH renormalization method that general momentum cutoff scalar field theories in four dimensions are perturbatively renormalizable. Weinberg close-quote s convergence theorem is used to show that operators in the Lagrangian with dimension greater than four, which are divided by powers of the cutoff, produce perturbatively only local divergences in the two-, three-, and four-point correlation functions. The naive use of the convergence theorem together with the BPH method is not appropriate for understanding the local divergences and renormalizability of these theories. We also show that the renormalized Green close-quote s functions are the same as in ordinary Φ 4 theory up to corrections suppressed by inverse powers of the cutoff. These conclusions are consistent with those of existing proofs based on the renormalization group. copyright 1996 The American Physical Society
Nonequlibrium dynamics of scalar fields in a thermal bath
International Nuclear Information System (INIS)
Anisimov, A.; Buchmueller, W.; Drewes, M.; Mendizabal, S.
2008-12-01
We study the approach to equilibrium for a scalar field which is coupled to a large thermal bath. Our analysis of the initial value problem is based on Kadanoff-Baym equations which are shown to be equivalent to a stochastic Langevin equation. The interaction with the thermal bath generates a temperature-dependent spectral density, either through decay and inverse decay processes or via Landau damping. In equilibrium, energy density and pressure are determined by the Bose-Einstein distribution function evaluated at a complex quasi-particle pole. The time evolution of the statistical propagator is compared with solutions of the Boltzmann equations for particles as well as quasi-particles. The dependence on initial conditions and the range of validity of the Boltzmann approximation are determined. (orig.)
Simultaneous dense coding affected by fluctuating massless scalar field
Huang, Zhiming; Ye, Yiyong; Luo, Darong
2018-04-01
In this paper, we investigate the simultaneous dense coding (SDC) protocol affected by fluctuating massless scalar field. The noisy model of SDC protocol is constructed and the master equation that governs the SDC evolution is deduced. The success probabilities of SDC protocol are discussed for different locking operators under the influence of vacuum fluctuations. We find that the joint success probability is independent of the locking operators, but other success probabilities are not. For quantum Fourier transform and double controlled-NOT operators, the success probabilities drop with increasing two-atom distance, but SWAP operator is not. Unlike the SWAP operator, the success probabilities of Bob and Charlie are different. For different noisy interval values, different locking operators have different robustness to noise.
BQP-completeness of scattering in scalar quantum field theory
Directory of Open Access Journals (Sweden)
Stephen P. Jordan
2018-01-01
Full Text Available Recent work has shown that quantum computers can compute scattering probabilities in massive quantum field theories, with a run time that is polynomial in the number of particles, their energy, and the desired precision. Here we study a closely related quantum field-theoretical problem: estimating the vacuum-to-vacuum transition amplitude, in the presence of spacetime-dependent classical sources, for a massive scalar field theory in (1+1 dimensions. We show that this problem is BQP-hard; in other words, its solution enables one to solve any problem that is solvable in polynomial time by a quantum computer. Hence, the vacuum-to-vacuum amplitude cannot be accurately estimated by any efficient classical algorithm, even if the field theory is very weakly coupled, unless BQP=BPP. Furthermore, the corresponding decision problem can be solved by a quantum computer in a time scaling polynomially with the number of bits needed to specify the classical source fields, and this problem is therefore BQP-complete. Our construction can be regarded as an idealized architecture for a universal quantum computer in a laboratory system described by massive phi^4 theory coupled to classical spacetime-dependent sources.
International Nuclear Information System (INIS)
Menezes, G.; Svaiter, N.F.
2006-04-01
We use the method of stochastic quantization in a topological field theory defined in an Euclidean space, assuming a Langevin equation with a memory kernel. We show that our procedure for the Abelian Chern-Simons theory converges regardless of the nature of the Chern-Simons coefficient. (author)
Construction of quantized gauge fields: continuum limit of the Abelian Higgs model in two dimensions
International Nuclear Information System (INIS)
Seiler, E.
1981-01-01
The author proves the existence of the continuum limit of the two-dimensional Higgs model for two cases: External gauge fields that are Hoelder continuous and may be non-Abelian, and the fully quantized Abelian model. In the latter case all Wightman axioms are verified except clustering. Important ingredients are a universal diamagnetic bound and correlation inequalities. (Auth.)
Weaver, Nik
2001-01-01
With a unique approach and presenting an array of new and intriguing topics, Mathematical Quantization offers a survey of operator algebras and related structures from the point of view that these objects are quantizations of classical mathematical structures. This approach makes possible, with minimal mathematical detail, a unified treatment of a variety of topics.Detailed here for the first time, the fundamental idea of mathematical quantization is that sets are replaced by Hilbert spaces. Building on this idea, and most importantly on the fact that scalar-valued functions on a set correspond to operators on a Hilbert space, one can determine quantum analogs of a variety of classical structures. In particular, because topologies and measure classes on a set can be treated in terms of scalar-valued functions, we can transfer these constructions to the quantum realm, giving rise to C*- and von Neumann algebras.In the first half of the book, the author quickly builds the operator algebra setting. He uses this ...
Diffraction of ultracold fermions by quantized light fields: Standing versus traveling waves
International Nuclear Information System (INIS)
Meiser, D.; Search, C.P.; Meystre, P.
2005-01-01
We study the diffraction of quantum-degenerate fermionic atoms off of quantized light fields in an optical cavity. We compare the case of a linear cavity with standing-wave modes to that of a ring cavity with two counterpropagating traveling wave modes. It is found that the dynamics of the atoms strongly depends on the quantization procedure for the cavity field. For standing waves, no correlations develop between the cavity field and the atoms. Consequently, standing-wave Fock states yield the same results as a classical standing wave field while coherent states give rise to a collapse and revivals in the scattering of the atoms. In contrast, for traveling waves the scattering results in quantum entanglement of the radiation field and the atoms. This leads to a collapse and revival of the scattering probability even for Fock states. The Pauli exclusion principle manifests itself as an additional dephasing of the scattering probability
Canonical field quantization in an external time-dependent gravitational field
International Nuclear Information System (INIS)
Il'yn, S.B.; Tagirov, E.A.
1975-01-01
The Green functions of the quantum scalar fiels interacting with gravitation of the homogeneous isotropic closed Universe are studied. They have been determined as an expectation value of the time-ordered product of two field operators in the cyclic states of various, in general, unitary-nonequivalent representations of canonical commutation relations. The reqularity properties of these functions are shown to be the same as of the Feynman propagator obtained for arbitrary Riemannian space-time only in the representations that from a class unitary equivalence
Quantum paradoxes, entanglement and their explanation on the basis of quantization of fields
Melkikh, A. V.
2017-01-01
Quantum entanglement is discussed as a consequence of the quantization of fields. The inclusion of quantum fields self-consistently explains some quantum paradoxes (EPR and Hardy’s paradox). The definition of entanglement was introduced, which depends on the maximum energy of the interaction of particles. The destruction of entanglement is caused by the creation and annihilation of particles. On this basis, an algorithm for quantum particle evolution was formulated.
Quasiperiodical orbits in the scalar classical lambdaphi4 field theory
International Nuclear Information System (INIS)
Belova, T.I.; Kudryavtsev, A.E.
1985-01-01
New numerical and theoretical results of resonance kink-antikink (Kanti K) interactions in the classical one-dimentional space Higgs theory are presented. Earlier studies of these interactions revealed nine initial relative velocity-intervals with two-bounce Kanti K-collisions followed by the escape of kinks to infinite separations, the breathing solution was formed outside those intervals. Two-bounce Kanti K-interactions with the number of small oscillations between Kanti K-bounces up to 35 in the initial kink velocity interval 0.18 <= Vsub(infinite) <= 0.26 were found. Several examples for n-bounces Kanti K-interaction (n <= 6) are also found. The observed phenomenon can be explaned by the existence of quasi-two-periodical solutions of the nonlinear wave equation. The simple Hamiltonian with two degrees of freedom is studied. This model supplies quantitative descrtiptions of all numerical results for the field theory considered above. The considered phenomenon may be called ''autoquantization'' of a nonlinear classical scalar selfinteracting field
Bianchi type-I model with conformally invariant scalar and electromagnetic field
International Nuclear Information System (INIS)
Accioly, A.J.; Vaidya, A.N.; Som, M.M.
1983-01-01
A Bianchi type-I exact solution of the Einstein theory representing the homogeneous anisotropic models with the electromagnetic field and the conformally invariant scalar field is studied. The solution contains Kasner model, pure electromagnetic and pure scalar models as special cases. It is found that the models evolve from an initial Kasner type to a final open Friedmann type universe. (Author) [pt
Perspectives of Light-Front Quantized Field Theory: Some New Results
Energy Technology Data Exchange (ETDEWEB)
Srivastava, Prem P.
1999-08-13
A review of some basic topics in the light-front (LF) quantization of relativistic field theory is made. It is argued that the LF quantization is equally appropriate as the conventional one and that they lead, assuming the microcausality principle, to the same physical content. This is confirmed in the studies on the LF of the spontaneous symmetry breaking (SSB), of the degenerate vacua in Schwinger model (SM) and Chiral SM (CSM), of the chiral boson theory, and of the QCD in covariant gauges among others. The discussion on the LF is more economical and more transparent than that found in the conventional equal-time quantized theory. The removal of the constraints on the LF phase space by following the Dirac method, in fact, results in a substantially reduced number of independent dynamical variables. Consequently, the descriptions of the physical Hilbert space and the vacuum structure, for example, become more tractable. In the context of the Dyson-Wick perturbation theory the relevant propagators in the front form theory are causal. The Wick rotation can then be performed to employ the Euclidean space integrals in momentum space. The lack of manifest covariance becomes tractable, and still more so if we employ, as discussed in the text, the Fourier transform of the fermionic field based on a special construction of the LF spinor. The fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of the hyperbolic partial differential equation is found irrelevant in the quantized theory; it seems sufficient to quantize the theory on one of the characteristic hyperplanes.
The continuous tower of scalar fields as a system of interacting dark matter–dark energy
International Nuclear Information System (INIS)
Santos, Paulo
2015-01-01
This paper aims to introduce a new parameterisation for the coupling Q in interacting dark matter and dark energy models by connecting said models with the Continuous Tower of Scalar Fields model. Based upon the existence of a dark matter and a dark energy sectors in the Continuous Tower of Scalar Fields, a simplification is considered for the evolution of a single scalar field from the tower, validated in this paper. This allows for the results obtained with the Continuous Tower of Scalar Fields model to match those of an interacting dark matter–dark energy system, considering that the energy transferred from one fluid to the other is given by the energy of the scalar fields that start oscillating at a given time, rather than considering that the energy transference depends on properties of the whole fluids that are interacting.
Linearized interactions of scalar and vector fields with the higher spin field in AdSD
International Nuclear Information System (INIS)
Mkrtchyan, K.
2011-01-01
The explicit form of linearized gauge and generalized 'Weyl invariant' interactions of scalar and general higher even spin fields in the AdS D space is reviewed. Also a linearized interaction of vector field with general higher even spin gauge field is obtained. It is shown that the gauge-invariant action of linearized vector field interacting with the higher spin field also includes the whole tower of invariant actions for couplings of the same vector field with the gauge fields of smaller even spin
Second quantization of classical nonlinear relativistic field theory. Pt. 2
International Nuclear Information System (INIS)
Balaban, T.
1976-01-01
The construction of a relativistic interacting local quantum field is given in two steps: first the classical nonlinear relativistic field theory is written down in terms of Poisson brackets, with initial conditions as canonical variables: next a representation of Poisson bracket Lie algebra by means of linear operators in the topological vector space is given and an explicit form of a local interacting relativistic quantum field PHI is obtained. (orig./BJ) [de
Comparison between two scalar field models using rotation curves of spiral galaxies
Fernández-Hernández, Lizbeth M.; Rodríguez-Meza, Mario A.; Matos, Tonatiuh
2018-04-01
Scalar fields have been used as candidates for dark matter in the universe, from axions with masses ∼ 10-5eV until ultra-light scalar fields with masses ∼ Axions behave as cold dark matter while the ultra-light scalar fields galaxies are Bose-Einstein condensate drops. The ultra-light scalar fields are also called scalar field dark matter model. In this work we study rotation curves for low surface brightness spiral galaxies using two scalar field models: the Gross-Pitaevskii Bose-Einstein condensate in the Thomas-Fermi approximation and a scalar field solution of the Klein-Gordon equation. We also used the zero disk approximation galaxy model where photometric data is not considered, only the scalar field dark matter model contribution to rotation curve is taken into account. From the best-fitting analysis of the galaxy catalog we use, we found the range of values of the fitting parameters: the length scale and the central density. The worst fitting results (values of χ red2 much greater than 1, on the average) were for the Thomas-Fermi models, i.e., the scalar field dark matter is better than the Thomas- Fermi approximation model to fit the rotation curves of the analysed galaxies. To complete our analysis we compute from the fitting parameters the mass of the scalar field models and two astrophysical quantities of interest, the dynamical dark matter mass within 300 pc and the characteristic central surface density of the dark matter models. We found that the value of the central mass within 300 pc is in agreement with previous reported results, that this mass is ≈ 107 M ⊙/pc2, independent of the dark matter model. And, on the contrary, the value of the characteristic central surface density do depend on the dark matter model.
Extended pure Yang-Mills gauge theories with scalar and tensor gauge fields
International Nuclear Information System (INIS)
Gabrielli, E.
1991-01-01
The usual abelian gauge theory is extended to an interacting Yang-Mills-like theory containing vector, scalar and tensor gauge fields. These gauge fields are seen as components along the Clifford algebra basis of a gauge vector-spinorial field. Scalar fields φ naturally coupled to vector and tensor fields have been found, leading to a natural φ 4 coupling in the lagrangian. The full expression of the lagrangian for the euclidean version of the theory is given. (orig.)
Intermediate inflation from a non-canonical scalar field
Energy Technology Data Exchange (ETDEWEB)
Rezazadeh, K.; Karami, K. [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Karimi, P., E-mail: rezazadeh86@gmail.com, E-mail: KKarami@uok.ac.ir, E-mail: parvin.karimi67@yahoo.com [Center for Excellence in Astronomy and Astrophysics (CEAA-RIAAM), P.O. Box 55134-441, Maragha (Iran, Islamic Republic of)
2015-09-01
We study the intermediate inflation in a non-canonical scalar field framework with a power-like Lagrangian. We show that in contrast with the standard canonical intermediate inflation, our non-canonical model is compatible with the observational results of Planck 2015. Also, we estimate the equilateral non-Gaussianity parameter which is in well agreement with the prediction of Planck 2015. Then, we obtain an approximation for the energy scale at the initial time of inflation and show that it can be of order of the Planck energy scale, i.e. M{sub P} ∼ 10{sup 18}GeV. We will see that after a short period of time, inflation enters in the slow-roll regime that its energy scale is of order M{sub P}/100 ∼ 10{sup 16}GeV and the horizon exit takes place in this energy scale. We also examine an idea in our non-canonical model to overcome the central drawback of intermediate inflation which is the fact that inflation never ends. We solve this problem without disturbing significantly the nature of the intermediate inflation until the time of horizon exit.
Gravitational waves from self-ordering scalar fields
International Nuclear Information System (INIS)
Fenu, Elisa; Durrer, Ruth; Figueroa, Daniel G.; García-Bellido, Juan
2009-01-01
Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as Ω GW (f) ∝ f 3 with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer time, until a given mode which is initially superhorizon (kη * 1, we find that the gravitational wave energy density is frequency independent, i.e. scale invariant. Moreover, its amplitude for a GUT scale scenario turns out to be within the range and sensitivity of BBO and marginally detectable by LIGO and LISA. This new gravitational wave background can compete with the one generated during inflation, and distinguishing both may require extra information
Self-interacting scalar fields at high-temperature
Energy Technology Data Exchange (ETDEWEB)
Deur, Alexandre [University of Virginia, Charlottesville, VA (United States)
2017-06-15
We study two self-interacting scalar field theories in their high-temperature limit using path integrals on a lattice. We first discuss the formalism and recover known potentials to validate the method. We then discuss how these theories can model, in the high-temperature limit, the strong interaction and General Relativity. For the strong interaction, the model recovers the known phenomenology of the nearly static regime of heavy quarkonia. The model also exposes a possible origin for the emergence of the confinement scale from the approximately conformal Lagrangian. Aside from such possible insights, the main purpose of addressing the strong interaction here - given that more sophisticated approaches already exist - is mostly to further verify the pertinence of the model in the more complex case of General Relativity for which non-perturbative methods are not as developed. The results have important implications on the nature of Dark Matter. In particular, non-perturbative effects naturally provide flat rotation curves for disk galaxies, without need for non-baryonic matter, and explain as well other observations involving Dark Matter such as cluster dynamics or the dark mass of elliptical galaxies. (orig.)
Three-dimensional Casimir piston for massive scalar fields
International Nuclear Information System (INIS)
Lim, S.C.; Teo, L.P.
2009-01-01
We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a 4 when a→0 + and decays exponentially when a→∞. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.
Gravitational waves from self-ordering scalar fields
Fenu, Elisa; Durrer, Ruth; Garcia-Bellido, Juan
2009-01-01
Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as $\\Omega_{\\rm GW}(f) \\propto f^3$ with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer tim...
Noncommutative conformally coupled scalar field cosmology and its commutative counterpart
International Nuclear Information System (INIS)
Barbosa, G.D.
2005-01-01
We study the implications of a noncommutative geometry of the minisuperspace variables for the Friedmann-Robertson-Walker universe with a conformally coupled scalar field. The investigation is carried out by means of a comparative study of the universe evolution in four different scenarios: classical commutative, classical noncommutative, quantum commutative, and quantum noncommutative, the last two employing the Bohmian formalism of quantum trajectories. The role of noncommutativity is discussed by drawing a parallel between its realizations in two possible frameworks for physical interpretation: the NC frame, where it is manifest in the universe degrees of freedom, and in the C frame, where it is manifest through θ-dependent terms in the Hamiltonian. As a result of our comparative analysis, we find that noncommutative geometry can remove singularities in the classical context for sufficiently large values of θ. Moreover, under special conditions, the classical noncommutative model can admit bouncing solutions characteristic of the commutative quantum Friedmann-Robertson-Walker universe. In the quantum context, we find nonsingular universe solutions containing bounces or being periodic in the quantum commutative model. When noncommutativity effects are turned on in the quantum scenario, they can introduce significant modifications that change the singular behavior of the universe solutions or that render them dynamical whenever they are static in the commutative case. The effects of noncommutativity are completely specified only when one of the frames for its realization is adopted as the physical one. Nonsingular solutions in the NC frame can be mapped into singular ones in the C frame
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Directory of Open Access Journals (Sweden)
Babak Vakili
2014-11-01
Full Text Available We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann–Robertson–Walker (FRW model, a scalar field with potential function V(ϕ with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f(ϕ. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion. Keywords: Noether symmetry, Scalar field cosmology, Vector field cosmology
Stochastic quantization of field theories on the lattice and supersymmetrical models
International Nuclear Information System (INIS)
Aldazabal, Gerardo.
1984-01-01
Several aspects of the stochastic quantization method are considered. Specifically, field theories on the lattice and supersymmetrical models are studied. A non-linear sigma model is studied firstly, and it is shown that it is possible to obtain evolution equations written directly for invariant quantities. These ideas are generalized to obtain Langevin equations for the Wilson loops of non-abelian lattice gauge theories U (N) and SU (N). In order to write these equations, some different ways of introducing the constraints which the fields must satisfy are discussed. It is natural to have a strong coupling expansion in these equations. The correspondence with quantum field theory is established, and it is noticed that at all orders in the perturbation theory, Langevin equations reduce to Schwinger-Dyson equations. From another point of view, stochastic quantization is applied to large N matrix models on the lattice. As a result, a simple and systematic way of building reduced models is found. Referring to stochastic quantization in supersymmetric theories, a simple supersymmetric model is studied. It is shown that it is possible to write an evolution equation for the superfield wich leads to quantum field theory results in equilibrium. As the Langevin equation preserves supersymmetry, the property of dimensional reduction known for the quantum model is shown to be valid at all times. (M.E.L.) [es
On the Generation of Intermediate Number Squeezed State of the Quantized Radiation Field
Baseia, B.; de Lima, A. F.; Bagnato, V. S.
Recently, a new state of the quantized radiation field — the intermediate number squeezed state (INSS) — has been introduced in the literature: it interpolates between the number state |n> and the squeezed state |z, α>=Ŝ(z)|α>, and exhibits interesting nonclassical properties as antibunching, sub-Poissonian statistics and squeezing. Here we introduce a slight modification in the previous definition allowing us a proposal to generate the INSS. Nonclassical properties using a new set of parameters are also studied.
Electrical resistance of flaky crystals in the longitudinal quantizing magnetic field
International Nuclear Information System (INIS)
Askerov, B.M.; Figarova, S.R.; Makhmudov, M.M.
2005-01-01
Specific resistance of the quasi-two-dimensional electrical gas in the longitudinal quantizing magnetic field is investigated in this work. Common expression for resistivity in the flaky crystals was received. In quantum limit was analyzed dependence of the resistivity from the size of magnetic field and parameters energetic spectra in case of strong degenerate gas. It was tagged that, the conduct of specific resistance is formed by the dependence of chemical potential from the size of magnetic field. At the defined value of the chemical potential and size of magnetic field obtains inflation of the specific resistance. (author)
Asymptotic behavior and Hamiltonian analysis of anti-de Sitter gravity coupled to scalar fields
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2007-01-01
We examine anti-de Sitter gravity minimally coupled to a self-interacting scalar field in D>=4 dimensions when the mass of the scalar field is in the range m * 2 = 2 * 2 +l -2 . Here, l is the AdS radius, and m * 2 is the Breitenlohner-Freedman mass. We show that even though the scalar field generically has a slow fall-off at infinity which back reacts on the metric so as to modify its standard asymptotic behavior, one can still formulate asymptotic conditions (i) that are anti-de Sitter invariant; and (ii) that allows the construction of well-defined and finite Hamiltonian generators for all elements of the anti-de Sitter algebra. This requires imposing a functional relationship on the coefficients a, b that control the two independent terms in the asymptotic expansion of the scalar field. The anti-de Sitter charges are found to involve a scalar field contribution. Subtleties associated with the self-interactions of the scalar field as well as its gravitational back reaction, not discussed in previous treatments, are explicitly analyzed. In particular, it is shown that the fields develop extra logarithmic branches for specific values of the scalar field mass (in addition to the known logarithmic branch at the B-F bound)
Effect of field quantization on Rabi oscillation of equidistant cascade ...
Indian Academy of Sciences (India)
acting with a single-mode radiation field both semiclassically and quantum ... the equidistant cascade four-level system modeled by the generators of the spin-3. 2 ... (1), hω0 is the equidistant energy gap between the levels, Ω is the frequency.
Semicalssical quantization of interacting anyons in a strong magnetic field
International Nuclear Information System (INIS)
Levit, S.; Sivan, N.
1992-01-01
We represent a semiclassical theory of charged interacting anyons in strong magnetic fields. We apply this theory to a number of few anyons systems including two interacting anyons in the presence of an impurity and three interacting anyons. We discuss the dependence of their energy levels on the statistical parameter and find regions in which this dependence follows very different patterns. The semiclassical arguments allow to correlate these patterns with the change in the character of the classical motion of the system. (author)
Imprint of thawing scalar fields on the large scale galaxy overdensity
Dinda, Bikash R.; Sen, Anjan A.
2018-04-01
We investigate the observed galaxy power spectrum for the thawing class of scalar field models taking into account various general relativistic corrections that occur on very large scales. We consider the full general relativistic perturbation equations for the matter as well as the dark energy fluid. We form a single autonomous system of equations containing both the background and the perturbed equations of motion which we subsequently solve for different scalar field potentials. First we study the percentage deviation from the Λ CDM model for different cosmological parameters as well as in the observed galaxy power spectra on different scales in scalar field models for various choices of scalar field potentials. Interestingly the difference in background expansion results from the enhancement of power from Λ CDM on small scales, whereas the inclusion of general relativistic (GR) corrections results in the suppression of power from Λ CDM on large scales. This can be useful to distinguish scalar field models from Λ CDM with future optical/radio surveys. We also compare the observed galaxy power spectra for tracking and thawing types of scalar field using some particular choices for the scalar field potentials. We show that thawing and tracking models can have large differences in observed galaxy power spectra on large scales and for smaller redshifts due to different GR effects. But on smaller scales and for larger redshifts, the difference is small and is mainly due to the difference in background expansion.
Quantized field formulation of the free-electron laser in the Heisenberg picture
International Nuclear Information System (INIS)
Takeda, H.
1985-01-01
The phase and amplitude operator equations valid for field intensities ranging from a single photon state to an intense laser state are derived by means of quantized field theory. Using the Dirac equation, driving current operators, which are expressed by radiation and electron fields, are separated into spontaneous, stimulated, and spin terms. Then, utilizing the semiclassical nature of the electron state, coherence condition and spectral equations are derived. From the spectral phase equation, a delay-time scaling for oscillator operation is obtained in good agreement with experiments. 1 ref
On propagation of sound waves in Q2D conductors in a quantizing magnetic field
Kirichenko, O V; Galbova, O; Ivanovski, G; Krstovska, D
2003-01-01
The attenuation of sound waves propagating normally to the layers of a Q2D conductor is analysed at low enough temperatures when quantization of the energy of conduction electrons results in an oscillatory dependence of the sound attenuation rate on the inverse magnetic field. The sound wave decrement is found for different orientations of the magnetic field with respect to the layers. A layered conductor is shown to be most transparent in the case when the magnetic field is orthogonal to the layers.
On propagation of sound waves in Q2D conductors in a quantizing magnetic field
International Nuclear Information System (INIS)
Kirichenko, O.V.; Peschansky, V.G.; Galbova, O.; Ivanovski, G.; Krstovska, D.
2003-01-01
The attenuation of sound waves propagating normally to the layers of a Q2D conductor is analysed at low enough temperatures when quantization of the energy of conduction electrons results in an oscillatory dependence of the sound attenuation rate on the inverse magnetic field. The sound wave decrement is found for different orientations of the magnetic field with respect to the layers. A layered conductor is shown to be most transparent in the case when the magnetic field is orthogonal to the layers
Quantized normal matrices: some exact results and collective field formulation
International Nuclear Information System (INIS)
Feinberg, Joshua
2005-01-01
We formulate and study a class of U(N)-invariant quantum mechanical models of large normal matrices with arbitrary rotation-invariant matrix potentials. We concentrate on the U(N) singlet sector of these models. In the particular case of quadratic matrix potential, the singlet sector can be mapped by a similarity transformation onto the two-dimensional Calogero-Marchioro-Sutherland model at specific couplings. For this quadratic case we were able to solve the N-body Schrodinger equation and obtain infinite sets of singlet eigenstates of the matrix model with given total angular momentum. Our main object in this paper is to study the singlet sector in the collective field formalism, in the large-N limit. We obtain in this framework the ground state eigenvalue distribution and ground state energy for an arbitrary potential, and outline briefly the way to compute bona-fide quantum phase transitions in this class of models. As explicit examples, we analyze the models with quadratic and quartic potentials. In the quartic case, we also touch upon the disk-annulus quantum phase transition. In order to make our presentation self-contained, we also discuss, in a manner which is somewhat complementary to standard expositions, the theory of point canonical transformations in quantum mechanics for systems whose configuration space is endowed with non-Euclidean metric, which is the basis for constructing the collective field theory
Scalar field localization on a brane with cosmological constant
International Nuclear Information System (INIS)
Ghoroku, Kazuo; Yahiro, Masanobu
2003-01-01
We investigate the localization of a massive scalar for both dS and AdS branes, where the scalar mass is varied from the massive-particle region to the tachyon region. We find that the eigenmass m of the localized mode satisfies a simple relation m 2 = cM 2 with a positive constant c for the dS brane, and m 2 = c 1 M 2 + c 2 with positive constants c 1 and c 2 for the AdS brane. We discuss the relation of these results to the stability of the brane and also some cosmological problems
Interacting viscous ghost tachyon, K-essence and dilaton scalar field models of dark energy
International Nuclear Information System (INIS)
Karami, K; Fahimi, K
2013-01-01
We study the correspondence between the interacting viscous ghost dark energy model with the tachyon, K-essence and dilaton scalar field models in the framework of Einstein gravity. We consider a spatially non-flat FRW universe filled with interacting viscous ghost dark energy and dark matter. We reconstruct both the dynamics and potential of these scalar field models according to the evolutionary behavior of the interacting viscous ghost dark energy model, which can describe the accelerated expansion of the universe. Our numerical results show that the interaction and viscosity have opposite effects on the evolutionary properties of the ghost scalar field models. (paper)
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar, E-mail: shaharhod@gmail.com [The Ruppin Academic Center, Emeq Hefer 40250 (Israel); The Hadassah Academic College, Jerusalem 91010 (Israel)
2017-05-10
We study analytically the characteristic resonance spectrum of charged massive scalar fields linearly coupled to a spherically symmetric charged reflecting shell. In particular, we use analytical techniques in order to solve the Klein–Gordon wave equation for the composed charged-shell–charged-massive-scalar-field system. Interestingly, it is proved that the resonant oscillation frequencies of this composed physical system are determined by the characteristic zeroes of the confluent hypergeometric function. Following this observation, we derive a remarkably compact analytical formula for the resonant oscillation frequencies which characterize the marginally-bound charged massive scalar field configurations. The analytically derived resonance spectrum is confirmed by numerical computations.
Transport equation for the time scale of a turbulent scalar field
International Nuclear Information System (INIS)
Kurbatskij, A.F.
1999-01-01
The two-parametric turbulence models cause serious difficulties by modeling the near-wall flows due to absence of the natural boundary condition on the wall for dissipation of the ε turbulence energy and the ε θ scalar field destruction. This difficulty may be overcome, if instead of the ε and ε θ , as the second parameter of the model, to apply the time scales of the turbulent dynamic and scalar fields. The equation of the scalar field is derived and numerical coefficients included therein, are determined from the simplest problems on the turbulent heat transfer [ru
arXiv Tensor to scalar ratio from single field magnetogenesis
Giovannini, Massimo
2017-08-10
The tensor to scalar ratio is affected by the evolution of the large-scale gauge fields potentially amplified during an inflationary stage of expansion. After deriving the exact evolution equations for the scalar and tensor modes of the geometry in the presence of dynamical gauge fields, it is shown that the tensor to scalar ratio is bounded from below by the dominance of the adiabatic contribution and it cannot be smaller than one thousands whenever the magnetogenesis is driven by a single inflaton field.
Quantizing the electromagnetic field near two-sided semitransparent mirrors
Furtak-Wells, Nicholas; Clark, Lewis A.; Purdy, Robert; Beige, Almut
2018-04-01
This paper models light scattering through flat surfaces with finite transmission, reflection, and absorption rates, with wave packets approaching the mirror from both sides. While using the same notion of photons as in free space, our model also accounts for the presence of mirror images and the possible exchange of energy between the electromagnetic field and the mirror surface. To test our model, we derive the spontaneous decay rate and the level shift of an atom in front of a semitransparent mirror as a function of its transmission and reflection rates. When considering limiting cases and using standard approximations, our approach reproduces well-known results but it also paves the way for the modeling of more complex scenarios.
The dark sector from interacting canonical and non-canonical scalar fields
International Nuclear Information System (INIS)
De Souza, Rudinei C; Kremer, Gilberto M
2010-01-01
In this work general models with interactions between two canonical scalar fields and between one non-canonical (tachyon type) and one canonical scalar field are investigated. The potentials and couplings to the gravity are selected through the Noether symmetry approach. These general models are employed to describe interactions between dark energy and dark matter, with the fields being constrained by the astronomical data. The cosmological solutions of some cases are compared with the observed evolution of the late Universe.
International Nuclear Information System (INIS)
Zamolodchikov, A.B.
1987-01-01
A multipoint conformal block of Ramond states of the two-dimensional free scalar field is calculated. This function is related to the free energy of the scalar field on the hyperelliptic Riemann surface under a particular choice of boundary conditions. Being compactified on the circle this field leads to the crossing symmetric correlation functions with a discrete spectrum of scale dimensions. These functions are supposed to describe multipoint spin correlations of the critical Ashkin-Teller model. (orig.)
Resonance properties of a three-level atom with quantized field modes
International Nuclear Information System (INIS)
Yoo, H.I.
1984-01-01
A system of one three-level atom and one or two quantized electro-magnetic field modes coupled to each other by the dipole interaction, with the rotating wave approximation is studied. All three atomic configurations, i.e., cascade Lambda- and V-types, are treated simultaneously. The system is treated as closed, i.e., no interaction with the external radiation field modes, to reveal the internal structures and symmetries in the system. The general dynamics of the system are investigated under several distinct initial conditions and their similarities and differences with the dynamics of the Jaynes-Cummings model are revealed. Also investigated is the possibility of so-called coherent trapping of the atom in the quantized field modes in a resonator. An atomic state of coherent trapping exists only for limited cases, and it generally requires the field to be in some special states, depending on the system. The discussion of coherent trapping is extended into a system of M identical three-level atoms. The stability of a coherent-trapping state when fluorescence can take place is discussed. The distinction between a system with resonator field modes and one with ideal laser modes is made clear, and the atomic relaxation to the coherent-trapping atomic state when a Lambda-type atom is irradiated by two ideal laser beams is studied. The experimental prospects to observe the collapse-revival phenomena in the atomic occupation probabilities, which is characteristic of a system with quantized resonator field modes is discussed
Particle on a torus knot: Constrained dynamics and semi-classical quantization in a magnetic field
Energy Technology Data Exchange (ETDEWEB)
Das, Praloy, E-mail: praloydasdurgapur@gmail.com; Pramanik, Souvik, E-mail: souvick.in@gmail.com; Ghosh, Subir, E-mail: subirghosh20@gmail.com
2016-11-15
Kinematics and dynamics of a particle moving on a torus knot poses an interesting problem as a constrained system. In the first part of the paper we have derived the modified symplectic structure or Dirac brackets of the above model in Dirac’s Hamiltonian framework, both in toroidal and Cartesian coordinate systems. This algebra has been used to study the dynamics, in particular small fluctuations in motion around a specific torus. The spatial symmetries of the system have also been studied. In the second part of the paper we have considered the quantum theory of a charge moving in a torus knot in the presence of a uniform magnetic field along the axis of the torus in a semiclassical quantization framework. We exploit the Einstein–Brillouin–Keller (EBK) scheme of quantization that is appropriate for multidimensional systems. Embedding of the knot on a specific torus is inherently two dimensional that gives rise to two quantization conditions. This shows that although the system, after imposing the knot condition reduces to a one dimensional system, even then it has manifested non-planar features which shows up again in the study of fractional angular momentum. Finally we compare the results obtained from EBK (multi-dimensional) and Bohr–Sommerfeld (single dimensional) schemes. The energy levels and fractional spin depend on the torus knot parameters that specifies its non-planar features. Interestingly, we show that there can be non-planar corrections to the planar anyon-like fractional spin.
Hamiltonian quantization of self-dual tensor fields and a bosonic Nielsen-Ninomiya theorem
International Nuclear Information System (INIS)
Tang Waikeung
1989-01-01
The quantization of self-dual tensor fields is carried out following the procedure of Batalin and Fradkin. The (anti) self-duality constraints (either fermionic or bosonic) in the action leads to the gravitational anomaly. In the process of gauge fixing, the impossibility of the co-existence of a positive hamiltonian and covariant action is shown. A version of the Nielsen-Ninomiya theorem applies to self-dual tensor fields viz. the lattice version of the theory shows species doubling with zero net chirality. (orig.)
Kuang-Leman; Wu Yong Shi
2003-01-01
We study linear and nonlinear optical properties of an electromagnetically induced transparency (EIT) medium interacting with two quantized laser fields in the adiabatic EIT case. We show that the EIT medium exhibits normal dispersion. Kerr and higher-order nonlinear refractive index coefficients are also calculated in a completely analytical form. It is indicated that the EIT medium exhibits giant resonantly enhanced nonlinearities. We discuss the response of the EIT medium to nonclassical light fields and find that the polarization vanishes when the probe laser is initially in a nonclassical state of no single-photon coherence.
Effect of electrical field on the quantized vortices in He II
International Nuclear Information System (INIS)
Natsik, V.D.
2007-01-01
Electrical polarization and interaction of quantized vortices with electrical field in superfluid Bose fluid are studied. Two types of the vortices polarization are considered; both of them are caused by action of centrifugal forces upon the fluid atoms at their azimuthal motion around the vortex line. Firstly, atoms obtain dipole moments (internal polarization when external polarization when external field is absent) and a nonuniform symmetrical distribution of the polarization density arises; at that, a vortex has no integral dipole moment but each element of the vortex line bears a quadrupole moment. Secondly, action of the centrifugal forces leads to a nonuniform distribution of the atomic density around the vortex line; therefore, the polarization density of the fluid in the external electrical field is also nonuniform in the vicinity of this line and each isolated element of the vortex line obtains dipole moment proportional to the field magnitude (inductive polarization). Analytical expressions for the polarization density around the straight and circular vortex lines are obtained and the effective dipole and quadrupole moments of the vortices are determined. A distribution of the ponderomotive forces acting on the superfluid fluid with quantized vortices in the external electrical field has been analyzed and the caused by field additives to the energy of the straight and circular vortices are found. Numerical estimations of the effects considered are given for He II
Correspondence of f(R,∇R) Modified Gravity with Scalar Field Models
International Nuclear Information System (INIS)
Jawad, Abdul; Debnath, Ujjal
2014-01-01
This paper is devoted to study the scalar field dark energy models by taking its different aspects in the framework of f(R,∇R) gravity. We consider flat FRW universe to construct the equation of state parameter governed by f(R,∇R) gravity. The stability of the model is discussed with the help of squared speed of sound parameter. It is found that models show quintessence behavior of the universe in stable as well as unstable modes. We also develop the correspondence of f(R,∇R) model with some scalar field dark energy models like quintessence, tachyonic field, k-essence, dilaton, hessence, and DBI-essence. The nature of scalar fields and corresponding scalar potentials is being analyzed in f(R,∇R) gravity graphically which show consistency with the present day observations about accelerated phenomenon
Spontaneous scalarization with an extremely massive field and heavy neutron stars
Morisaki, Soichiro; Suyama, Teruaki
2017-10-01
We investigate the internal structure and the mass-radius relation of neutron stars in a recently proposed scalar-tensor theory dubbed asymmetron in which a massive scalar field undergoes spontaneous scalarization inside neutron stars. We focus on the case where the Compton wavelength is shorter than 10 km, which has not been investigated in the literature. By solving the modified Einstein equations, either purely numerically or by partially using a semianalytic method, we find that not only the weakening of gravity by spontaneous scalarization but also the scalar force affect the internal structure significantly in the massive case. We also find that the maximum mass of neutron stars is larger for certain parameter sets than that in general relativity and reaches 2 M⊙ even if the effect of strange hadrons is taken into account. There is even a range of parameters where the maximum mass of neutron stars largely exceeds the threshold that violates the causality bound in general relativity.
Directory of Open Access Journals (Sweden)
Kazuharu Bamba
2014-10-01
Full Text Available We reconstruct scalar field theories to realize inflation compatible with the BICEP2 result as well as the Planck. In particular, we examine the chaotic inflation model, natural (or axion inflation model, and an inflationary model with a hyperbolic inflaton potential. We perform an explicit approach to find out a scalar field model of inflation in which any observations can be explained in principle.
Wheeler-DeWitt equation and Lie symmetries in Bianchi scalar-field cosmology
Energy Technology Data Exchange (ETDEWEB)
Paliathanasis, A. [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Karpathopoulos, L. [University of Athens, Faculty of Physics, Department of Astronomy-Astrophysics-Mechanics, Athens (Greece); Wojnar, A. [Institute for Theoretical Physics, Wroclaw (Poland); Universita' di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Complesso Universitario di Monte S. Angelo, Naples (Italy); Istituto Nazionale di Fisica Nucleare (INFN) Sez. di Napoli, Naples (Italy); Capozziello, S. [Universita' di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Naples (Italy); Complesso Universitario di Monte S. Angelo, Naples (Italy); Gran Sasso Science Institute (INFN), L' Aquila (Italy); Istituto Nazionale di Fisica Nucleare (INFN) Sez. di Napoli, Naples (Italy)
2016-04-15
Lie symmetries are discussed for the Wheeler-De Witt equation in Bianchi Class A cosmologies. In particular, we consider general relativity, minimally coupled scalar-field gravity and hybrid gravity as paradigmatic examples of the approach. Several invariant solutions are determined and classified according to the form of the scalar-field potential. The approach gives rise to a suitable method to select classical solutions and it is based on the first principle of the existence of symmetries. (orig.)
Hawking radiation of five-dimensional charged black holes with scalar fields
Directory of Open Access Journals (Sweden)
Yan-Gang Miao
2017-09-01
Full Text Available We investigate the Hawking radiation cascade from the five-dimensional charged black hole with a scalar field coupled to higher-order Euler densities in a conformally invariant manner. We give the semi-analytic calculation of greybody factors for the Hawking radiation. Our analysis shows that the Hawking radiation cascade from this five-dimensional black hole is extremely sparse. The charge enhances the sparsity of the Hawking radiation, while the conformally coupled scalar field reduces this sparsity.
Supplying Dark Energy from Scalar Field Dark Matter
Gogberashvili, Merab; Sakharov, Alexander S.
2017-01-01
We consider the hypothesis that dark matter and dark energy consists of ultra-light self-interacting scalar particles. It is found that the Klein-Gordon equation with only two free parameters (mass and self-coupling) on a Schwarzschild background, at the galactic length-scales has the solution which corresponds to Bose-Einstein condensate, behaving as dark matter, while the constant solution at supra-galactic scales can explain dark energy.
Is Sextans dwarf galaxy in a scalar field dark matter halo?
International Nuclear Information System (INIS)
Lora, V.; Magaña, Juan
2014-01-01
The Bose-Einstein condensate/scalar field dark matter model, considers that the dark matter is composed by spinless-ultra-light particles which can be described by a scalar field. This model is an alternative model to the Λ-cold dark matter paradigm, and therefore should be studied at galactic and cosmological scales. Dwarf spheroidal galaxies have been very useful when studying any dark matter theory, because the dark matter dominates their dynamics. In this paper we study the Sextans dwarf spheroidal galaxy, embedded in a scalar field dark matter halo. We explore how the dissolution time-scale of the stellar substructures in Sextans, constrain the mass, and the self-interacting parameter of the scalar field dark matter boson. We find that for masses in the range (0.12< m φ <8) ×10 -22 eV, scalar field dark halos without self-interaction would have cores large enough to explain the longevity of the stellar substructures in Sextans, and small enough mass to be compatible with dynamical limits. If the self-interacting parameter is distinct to zero, then the mass of the boson could be as high as m φ ≈2×10 -21 eV, but it would correspond to an unrealistic low mass for the Sextans dark matter halo . Therefore, the Sextans dwarf galaxy could be embedded in a scalar field/BEC dark matter halo with a preferred self-interacting parameter equal to zero
International Nuclear Information System (INIS)
Melas, Evangelos
2011-01-01
The 3+1 (canonical) decomposition of all geometries admitting two-dimensional space-like surfaces is exhibited as a generalization of a previous work. A proposal, consisting of a specific re-normalization Assumption and an accompanying Requirement, which has been put forward in the 2+1 case is now generalized to 3+1 dimensions. This enables the canonical quantization of these geometries through a generalization of Kuchar's quantization scheme in the case of infinite degrees of freedom. The resulting Wheeler-deWitt equation is based on a re-normalized manifold parameterized by three smooth scalar functionals. The entire space of solutions to this equation is analytically given, a fact that is entirely new to the present case. This is made possible by exploiting the freedom left by the imposition of the Requirement and contained in the third functional.
Geometro-stochastic quantization of gauge fields in curved space-time
International Nuclear Information System (INIS)
Prugovecki, E.
1988-01-01
It is shown that the geometro-stochastic method of quantization of massive fields in curved space-time can be extended to the massless cases of electromagnetic fields and general Yang-Mills fields. The Fock fibres of the massive case are replaced in the present context by fibres with indefinite inner products, such as Gupta-Bleuler fibres in the electromagnetic case. The quantum space-time form factor used in the massive case gives rise in the present case to quantum gauge frames whose elements are generalized coherent states corresponding to pseudounitary spin-one representations of direct products of the Poincare group with the U(1), SU(N) or other internal gauge groups. Quantum connections are introduced on bundles of second-quantized frames, and the corresponding parallel transport is expressed in terms of path integrals for quantum frame propagators. In the Yang-Mills case, these path integral make use of Faddeev-Popov quantum frames. It is shown, however, that in the present framework the ghost fields that give rise to these frames possess a geometric interpretation related to the presence of a super-gauge group that, in addition to the external Poincare and Yang-Mills gauge degrees of freedom, involves also the internal ones related to choices of gauge bases within the quantum fibres
Dark sector impact on gravitational collapse of an electrically charged scalar field
Energy Technology Data Exchange (ETDEWEB)
Nakonieczna, Anna [Institute of Physics, Maria Curie-Skłodowska University,Plac Marii Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Institute of Agrophysics, Polish Academy of Sciences,Doświadczalna 4, 20-290 Lublin (Poland); Rogatko, Marek [Institute of Physics, Maria Curie-Skłodowska University,Plac Marii Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Nakonieczny, Łukasz [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warszawa (Poland)
2015-11-04
Dark matter and dark energy are dominating components of the Universe. Their presence affects the course and results of processes, which are driven by the gravitational interaction. The objective of the paper was to examine the influence of the dark sector on the gravitational collapse of an electrically charged scalar field. A phantom scalar field was used as a model of dark energy in the system. Dark matter was modeled by a complex scalar field with a quartic potential, charged under a U(1)-gauge field. The dark components were coupled to the electrically charged scalar field via the exponential coupling and the gauge field-Maxwell field kinetic mixing, respectively. Complete non-linear simulations of the investigated process were performed. They were conducted from regular initial data to the end state, which was the matter dispersal or a singularity formation in a spacetime. During the collapse in the presence of dark energy dynamical wormholes and naked singularities were formed in emerging spacetimes. The wormhole throats were stabilized by the violation of the null energy condition, which occurred due to a significant increase of a value of the phantom scalar field function in its vicinity. The square of mass parameter of the dark matter scalar field potential controlled the formation of a Cauchy horizon or wormhole throats in the spacetime. The joint impact of dark energy and dark matter on the examined process indicated that the former decides what type of an object forms, while the latter controls the amount of time needed for the object to form. Additionally, the dark sector suppresses the natural tendency of an electrically charged scalar field to form a dynamical Reissner-Nordström spacetime during the gravitational collapse.
One-loop masses of open-string scalar fields in string theory
International Nuclear Information System (INIS)
Kitazawa, Noriaki
2008-01-01
In phenomenological models with D-branes, there are in general open-string massless scalar fields, in addition to closed-string massless moduli fields corresponding to the compactification. It is interesting to focus on the fate of such scalar fields in models with broken supersymmetry, because no symmetry forbids their masses. The one-loop effect may give non-zero masses to them, and in some cases mass squared may become negative, which means the radiative gauge symmetry breaking. In this article we investigate and propose a simple method for calculating the one-loop corrections using the boundary state formalism. There are two categories of massless open-string scalar fields. One consists the gauge potential fields corresponding to compactified directions, which can be understood as scalar fields in uncompactified space-time (related with Wilson line degrees of freedom). The other consists 'gauge potential fields' corresponding to transverse directions of D-brane, which emerge as scalar fields in D-brane world-volume (related with brane moduli fields). The D-brane boundary states with constant backgrounds of these scalar fields are constructed, and one-loop scalar masses are calculated in the closed string picture. Explicit calculations are given in the following four concrete models: one D25-brane with a circle compactification in bosonic string theory, one D9-brane with a circle compactification in superstring theory, D3-branes at a supersymmetric C 3 /Z 3 orbifold singularity, and a model of brane supersymmetry breaking with D3-branes and anti-D7-branes at a supersymmetric C 3 /Z 3 orbifold singularity. We show that the sign of the mass squared has a strong correlation with the sign of the related open-string one-loop vacuum amplitude.
Group theoretical quantization of isotropic loop cosmology
Livine, Etera R.; Martín-Benito, Mercedes
2012-06-01
We achieve a group theoretical quantization of the flat Friedmann-Robertson-Walker model coupled to a massless scalar field adopting the improved dynamics of loop quantum cosmology. Deparemetrizing the system using the scalar field as internal time, we first identify a complete set of phase space observables whose Poisson algebra is isomorphic to the su(1,1) Lie algebra. It is generated by the volume observable and the Hamiltonian. These observables describe faithfully the regularized phase space underlying the loop quantization: they account for the polymerization of the variable conjugate to the volume and for the existence of a kinematical nonvanishing minimum volume. Since the Hamiltonian is an element in the su(1,1) Lie algebra, the dynamics is now implemented as SU(1, 1) transformations. At the quantum level, the system is quantized as a timelike irreducible representation of the group SU(1, 1). These representations are labeled by a half-integer spin, which gives the minimal volume. They provide superselection sectors without quantization anomalies and no factor ordering ambiguity arises when representing the Hamiltonian. We then explicitly construct SU(1, 1) coherent states to study the quantum evolution. They not only provide semiclassical states but truly dynamical coherent states. Their use further clarifies the nature of the bounce that resolves the big bang singularity.
Superposition of number and squeezed states of the quantized light field
International Nuclear Information System (INIS)
De Brito, A.L.; Marques, G.A.; Baseia, B.; Dias, H.
1998-01-01
A recent paper in the literature (Mod. Phys. Lett. B, 9 (1995) 1673) introduced the Intermediate Number Squeezed State (INSS) of the quantized radiation field interpolating between the number state (n) and the squeezed-coherent state (z, α), exhibiting various nonclassical properties. Here, it's introduced an alternative state, interpolating between those limiting states and show that nonclassical effects in this new intermediate state can be greater than those exhibited by the INSS, depending on the values of the interpolating parameters. Although constituting an application of a general approach (Nuovo Cimento D, 18 (1996) 425), it concludes another case in the literature (Phys. Scr., 55 (1997) 179) as a particularisation of this
Absorption and radiation of nonminimally coupled scalar field from charged BTZ black hole
Huang, Lu; Chen, Juhua; Wang, Yongjiu
2018-06-01
In this paper we investigate the absorption and radiation of nonminimally coupled scalar field from the charged BTZ black hole. We find the analytical expressions for the reflection coefficient, the absorption cross section and the decay rate in strong coupling case. We find that the reflection coefficient is directly governed by Hawking temperature TH, scalar wave frequency ω , Bekenstein-Hawking entropy S_{BH}, angular momentum m and coupling constant ξ.
Conformal scalar fields and chiral splitting on super Riemann surfaces
International Nuclear Information System (INIS)
D'Hoker, E.; Phong, D.H.
1989-01-01
We provide a complete description of correlation functions of scalar superfields on a super Riemann surface, taking into account zero modes and non-trivial topology. They are built out of chirally split correlation functions, or conformal blocks at fixed internal momenta. We formulate effective rules which determine these completely in terms of geometric invariants of the super Riemann surface. The chirally split correlation functions have non-trivial monodromy and produce single-valued amplitudes only upon integration over loop momenta. Our discussion covers the even spin structure as well as the odd spin structure case which had been the source of many difficulties in the past. Super analogues of Green's functions, holomorphic spinors, and prime forms emerge which should pave the way to function theory on super Riemann surfaces. In superstring theories, chirally split amplitudes for scalar superfields are crucial in enforcing the GSO projection required for consistency. However one really knew how to carry this out only in the operator formalism to one-loop order. Our results provide a way of enforcing the GSO projection to any loop. (orig.)
Conformal generally covariant quantum field theory. The scalar field and its Wick products
Energy Technology Data Exchange (ETDEWEB)
Pinamonti, N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik
2008-06-15
In this paper we generalize the construction of generally covariant quantum theories given in [R. Brunetti, K. Fredenhagen, R. Verch, Commun. Math. Phys. 237, 31 (2003)] to encompass the conformal covariant case. After introducing the abstract framework, we discuss the massless conformally coupled Klein Gordon field theory, showing that its quantization corresponds to a functor between two certain categories. At the abstract level, the ordinary fields, could be thought as natural transformations in the sense of category theory. We show that, the Wick monomials without derivatives (Wick powers), can be interpreted as fields in this generalized sense, provided a non trivial choice of the renormalization constants is given. A careful analysis shows that the transformation law of Wick powers is characterized by a weight, and it turns out that the sum of fields with different weights breaks the conformal covariance. At this point there is a difference between the previously given picture due to the presence of a bigger group of covariance. It is furthermore shown that the construction does not depend upon the scale {mu} appearing in the Hadamard parametrix, used to regularize the fields. Finally, we briefly discuss some further examples of more involved fields. (orig.)
Conformal generally covariant quantum field theory. The scalar field and its Wick products
International Nuclear Information System (INIS)
Pinamonti, N.
2008-06-01
In this paper we generalize the construction of generally covariant quantum theories given in [R. Brunetti, K. Fredenhagen, R. Verch, Commun. Math. Phys. 237, 31 (2003)] to encompass the conformal covariant case. After introducing the abstract framework, we discuss the massless conformally coupled Klein Gordon field theory, showing that its quantization corresponds to a functor between two certain categories. At the abstract level, the ordinary fields, could be thought as natural transformations in the sense of category theory. We show that, the Wick monomials without derivatives (Wick powers), can be interpreted as fields in this generalized sense, provided a non trivial choice of the renormalization constants is given. A careful analysis shows that the transformation law of Wick powers is characterized by a weight, and it turns out that the sum of fields with different weights breaks the conformal covariance. At this point there is a difference between the previously given picture due to the presence of a bigger group of covariance. It is furthermore shown that the construction does not depend upon the scale μ appearing in the Hadamard parametrix, used to regularize the fields. Finally, we briefly discuss some further examples of more involved fields. (orig.)
The Scalar, Vector and Tensor Fields in Theory of Elasticity and Plasticity
Directory of Open Access Journals (Sweden)
František FOJTÍK
2014-06-01
Full Text Available This article is devoted to an analysis of scalar, vector and tensor fields, which occur in the loaded and deformed bodies. The aim of this article is to clarify and simplify the creation of an understandable idea of some elementary concepts and quantities in field theories, such as, for example equiscalar levels, scalar field gradient, Hamilton operator, divergence, rotation and gradient of vector or tensor and others. Applications of those mathematical terms are shown in simple elasticity and plasticity tasks. We hope that content of our article might help technicians to make their studies of necessary mathematical chapters of vector and tensor analysis and field theories easier.
Master formulas for the dressed scalar propagator in a constant field
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Aftab Ahmad
2017-06-01
Full Text Available The worldline formalism has previously been used for deriving compact master formulas for the one-loop N-photon amplitudes in both scalar and spinor QED, and in the vacuum as well as in a constant external field. For scalar QED, there is also an analogous master formula for the propagator dressed with N photons in the vacuum. Here, we extend this master formula to include a constant field. The two-photon case is worked out explicitly, yielding an integral representation for the Compton scattering cross section in the field suitable for numerical integration in the full range of electric and magnetic field strengths.
Master formulas for the dressed scalar propagator in a constant field
Energy Technology Data Exchange (ETDEWEB)
Ahmad, Aftab [Department of Physics, Gomal University, 29220 D.I. Khan, K.P.K (Pakistan); Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, Morelia 58040, Michoacán (Mexico); Ahmadiniaz, Naser, E-mail: Ahmadiniaz@ibs.re.kr [Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005 (Korea, Republic of); Department of Physics, Kunsan National University, Kunsan 54150 (Korea, Republic of); Corradini, Olindo [Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via Campi 213/A, I-41125 Modena (Italy); INFN, Sezione di Bologna, Via Irnerio 46, I-40126 Bologna (Italy); Kim, Sang Pyo [Center for Relativistic Laser Science, Institute for Basic Science, Gwangju 61005 (Korea, Republic of); Department of Physics, Kunsan National University, Kunsan 54150 (Korea, Republic of); Schubert, Christian [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, Morelia 58040, Michoacán (Mexico)
2017-06-15
The worldline formalism has previously been used for deriving compact master formulas for the one-loop N-photon amplitudes in both scalar and spinor QED, and in the vacuum as well as in a constant external field. For scalar QED, there is also an analogous master formula for the propagator dressed with N photons in the vacuum. Here, we extend this master formula to include a constant field. The two-photon case is worked out explicitly, yielding an integral representation for the Compton scattering cross section in the field suitable for numerical integration in the full range of electric and magnetic field strengths.
Relativistic n-body wave equations in scalar quantum field theory
International Nuclear Information System (INIS)
Emami-Razavi, Mohsen
2006-01-01
The variational method in a reformulated Hamiltonian formalism of Quantum Field Theory (QFT) is used to derive relativistic n-body wave equations for scalar particles (bosons) interacting via a massive or massless mediating scalar field (the scalar Yukawa model). Simple Fock-space variational trial states are used to derive relativistic n-body wave equations. The equations are shown to have the Schroedinger non-relativistic limits, with Coulombic interparticle potentials in the case of a massless mediating field and Yukawa interparticle potentials in the case of a massive mediating field. Some examples of approximate ground state solutions of the n-body relativistic equations are obtained for various strengths of coupling, for both massive and massless mediating fields
A mapping closure for turbulent scalar mixing using a time-evolving reference field
Girimaji, Sharath S.
1992-01-01
A general mapping-closure approach for modeling scalar mixing in homogeneous turbulence is developed. This approach is different from the previous methods in that the reference field also evolves according to the same equations as the physical scalar field. The use of a time-evolving Gaussian reference field results in a model that is similar to the mapping closure model of Pope (1991), which is based on the methodology of Chen et al. (1989). Both models yield identical relationships between the scalar variance and higher-order moments, which are in good agreement with heat conduction simulation data and can be consistent with any type of epsilon(phi) evolution. The present methodology can be extended to any reference field whose behavior is known. The possibility of a beta-pdf reference field is explored. The shortcomings of the mapping closure methods are discussed, and the limit at which the mapping becomes invalid is identified.
International Nuclear Information System (INIS)
Dey, Prasanta K.; Zikanov, Oleg
2012-01-01
Highlights: ► Turbulent passive scalar transport in an MHD flow in a channel is studied using DNS. ► Magnetic fields of wall-normal, spanwise, and streamwise orientations are considered. ► Magnetic fields suppress turbulent transport and modifies scalar distribution. ► The effect is particularly strong at wall-normal and spanwise magnetic fields. ► Decrease of Nusselt number is approximated by a linear function of magnetic interaction parameter. - Abstract: DNS of turbulent flow and passive scalar transport in a channel are conducted for the situation when the fluid is electrically conducting (for example, a liquid metal) and the flow is affected by an imposed magnetic field. The cases of wall-normal, spanwise, and streamwise orientation of the magnetic field are considered. As main results, we find that the magnetic fields, especially those in the wall-normal and spanwise directions, significantly reduce the turbulent scalar transport and modify the properties of the scalar distribution.
Analytical study of a Kerr-Sen black hole and a charged massive scalar field
Bernard, Canisius
2017-11-01
It is reported that Kerr-Newman and Kerr-Sen black holes are unstable to perturbations of charged massive scalar field. In this paper, we study analytically the complex frequencies which characterize charged massive scalar fields in a near-extremal Kerr-Sen black hole. For near-extremal Kerr-Sen black holes and for charged massive scalar fields in the eikonal large-mass M ≫μ regime, where M is the mass of the black hole, and μ is the mass of the charged scalar field, we have obtained a simple expression for the dimensionless ratio ωI/(ωR-ωc) , where ωI and ωR are, respectively, the imaginary and real parts of the frequency of the modes, and ωc is the critical frequency for the onset of super-radiance. We have also found our expression is consistent with the result of Hod [Phys. Rev. D 94, 044036 (2016), 10.1103/PhysRevD.94.044036] for the case of a near-extremal Kerr-Newman black hole and the result of Zouros and Eardly [Ann. Phys. (N.Y.) 118, 139 (1979), 10.1016/0003-4916(79)90237-9] for the case of neutral scalar fields in the background of a near-extremal Kerr black hole.
Dynamical system of scalar field from 2-dimension to 3-D and its cosmological implications
Energy Technology Data Exchange (ETDEWEB)
Fang, Wei [Shanghai Normal University, Department of Physics, Shanghai (China); The Shanghai Key Lab for Astrophysics, Shanghai (China); Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Tu, Hong [Shanghai Normal University, Department of Physics, Shanghai (China); The Shanghai Key Lab for Astrophysics, Shanghai (China); Huang, Jiasheng [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Shu, Chenggang [The Shanghai Key Lab for Astrophysics, Shanghai (China)
2016-09-15
We give the three-dimensional dynamical autonomous systems for most of the popular scalar field dark energy models including (phantom) quintessence, (phantom) tachyon, K-essence, and general non-canonical scalar field models, change the dynamical variables from variables (x, y, λ) to observable related variables (w{sub φ}, Ω{sub φ}, λ), and show the intimate relationships between those scalar fields that the three-dimensional system of K-essence can reduce to (phantom) tachyon, general non-canonical scalar field can reduce to (phantom) quintessence and K-essence can also reduce to (phantom) quintessence for some special cases. For the applications of the three-dimensional dynamical systems, we investigate several special cases and give the exactly dynamical solutions in detail. In the end of this paper, we argue that it is more convenient and also has more physical meaning to express the differential equations of dynamical systems in (w{sub φ}, Ω{sub φ}, λ) instead of variables (x, y, λ) and to investigate the dynamical system in three dimensions instead of two dimensions. We also raise a question about the possibility of the chaotic behavior in the spatially flat single scalar field FRW cosmological models in the presence of ordinary matter. (orig.)
Are black holes a serious threat to scalar field dark matter models?
International Nuclear Information System (INIS)
Barranco, Juan; Degollado, Juan Carlos; Bernal, Argelia; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Nunez, Dario; Sarbach, Olivier
2011-01-01
Classical scalar fields have been proposed as possible candidates for the dark matter component of the universe. Given the fact that supermassive black holes seem to exist at the center of most galaxies, in order to be a viable candidate for the dark matter halo a scalar field configuration should be stable in the presence of a central black hole, or at least be able to survive for cosmological time scales. In the present work we consider a scalar field as a test field on a Schwarzschild background, and study under which conditions one can obtain long-lived configurations. We present a detailed study of the Klein-Gordon equation in the Schwarzschild space-time, both from an analytical and numerical point of view, and show that indeed there exist quasistationary solutions that can remain surrounding a black hole for large time scales.
Decoherence and disentanglement of qubits detecting scalar fields in an expanded spacetime
International Nuclear Information System (INIS)
Li, Yujie; Dai, Yue; Shi, Yu
2017-01-01
We consider Unruh-Wald qubit detector model adopted for the far future region of an exactly solvable 1 + 1 dimensional scalar field theory in a toy model of Robertson-Walker expanding spacetime. It is shown that the expansion of the spacetime in its history enhances the decoherence of the qubit coupled with a scalar field. Moreover, we consider two entangled qubits, each locally coupled with a scalar field. The expansion of the spacetime in its history degrades the entanglement between the qubits, and it can lead to entanglement's sudden death if the initial entanglement is small enough. The details depend on the parameters characterizing the expansion of the spacetime. This work, on a toy model, suggests that the history of the spacetime might be probed through the coherent and entanglement behavior of the future detectors of quantum fields. In the present toy model, the two cosmological parameters can be determined from the quantum informational quantities of the detectors. (orig.)
Black holes and asymptotics of 2+1 gravity coupled to a scalar field
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2002-01-01
We consider 2+1 gravity minimally coupled to a self-interacting scalar field. The case in which the fall-off of the fields at infinity is slower than that of a localized distribution of matter is analyzed. It is found that the asymptotic symmetry group remains the same as in pure gravity (i.e., the conformal group). The generators of the asymptotic symmetries, however, acquire a contribution from the scalar field, but the algebra of the canonical generators possesses the standard central extension. In this context, new massive black hole solutions with a regular scalar field are found for a one-parameter family of potentials. These black holes are continuously connected to the standard zero mass black hole
Asymptotically anti-de Sitter spacetimes and scalar fields with a logarithmic branch
International Nuclear Information System (INIS)
Henneaux, Marc; Martinez, Cristian; Troncoso, Ricardo; Zanelli, Jorge
2004-01-01
We consider a self-interacting scalar field whose mass saturates the Breitenlohner-Freedman bound, minimally coupled to Einstein gravity with a negative cosmological constant in D≥3 dimensions. It is shown that the asymptotic behavior of the metric has a slower fall-off than that of pure gravity with a localized distribution of matter, due to the back-reaction of the scalar field, which has a logarithmic branch decreasing as r -(D-1)/2 ln r for large radius r. We find the asymptotic conditions on the fields which are invariant under the same symmetry group as pure gravity with negative cosmological constant (conformal group in D-1 dimensions). The generators of the asymptotic symmetries are finite even when the logarithmic branch is considered but acquire, however, a contribution from the scalar field
Charge quantization without superheavy masses in a Kaluza--Klein description of electromagnetism
International Nuclear Information System (INIS)
Ross, D.K.
1987-01-01
A scalar matter field coupled to general relativity and electromagnetism in a five-dimensional Kaluza--Klein model is considered. The five-dimensional space is assumed to be a fiber bundle as in the usual description of a gauge theory and not a more general manifold. Properly taking this into account allows one to use a Lagrangian density for the scalar field which includes charge quantization but not the unphysical superheavy masses found by other authors. A natural, satisfactory explanation of why charge is quantized results
International Nuclear Information System (INIS)
Sivan, N.; Levit, S.
1992-01-01
We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)
Semi-classical derivation of charge-quantization through charge-field self-interaction
International Nuclear Information System (INIS)
Kosok, M.; Madhyastha, V.L.
1990-01-01
A semi-classical synthesis of classical mechanics, wave mechanics, and special relativity yields a unique nonlinear energy-wave structure of relations (velocity triad uv = c 2 ) fundamental to modern physics. Through the above vehicle, using Maxwell's equations, charge quantization and the fine structure constant are derived. It is shown that the numerical value of the nonlinear charge-field self-interaction range for the electron is of the order of 10 -13 m, which is greater than the classical electron radius but less than the Compton wavelength of the electron. Finally, it is suggested that the structure of the electron-in-space is expressed by a self-extending nonlinear ''fractal geometry'' based on derived numerical values obtained from our model, thus opening this presentation of charge-field structure to experimental testing for possible verification
Quantization in the neighborhood of a classical solution in the theory of a Fermi field
International Nuclear Information System (INIS)
Sveshnikov, K.A.
1988-01-01
The quantization of a Fermi-Bose field system in the neighborhood of a classical solution of the equations of motion that contains both bosonic and spinor components is considered. The latter is regarded as an absolutely anticommuting (Grassmann) component of a fermion field. On account of the transport of the fermion number, such an object mixes the fermionic and bosonic and fermionic and antifermionic degrees of freedom already at the level of the single-particle states (in the approximately of quadratic forms). Explicit expressions are obtained for the operator of the S matrix, which describes such transport processes, and the total Hamiltonian and total fermion charge of the system in this approximation
Quantized Dirac field in curved Riemann--Cartan background. I. Symmetry properties, Green's function
International Nuclear Information System (INIS)
Nieh, H.T.; Yan, M.L.
1982-01-01
In the present series of papers, we study the properties of quantized Dirac field in curved Riemann--Cartan space, with particular attention on the role played by torsion. In this paper, we give, in the spirit of the original work of Weyl, a systematic presentation of Dirac's theory in curved Riemann--Cartan space. We discuss symmetry properties of the system, and derive conservation laws as direct consequences of these symmetries. Also discussed is conformal gauge symmetry, with torsion effectively playing the role of a conformal gauge field. To obtain short-distance behavior, we calculate the spinor Green's function, in curved Riemann--Cartan background, using the Schwinger--DeWitt method of proper-time expansion. The calculation corresponds to a generalization of DeWitt's calculation for a Riemannian background
International Nuclear Information System (INIS)
Barut, A.O.; Cruz, M.G.
1992-08-01
We use the method of analytic continuation of the equation of motion including the self-fields to evaluate the radiation reaction for a classical relativistic spinning point particle in interaction with scalar, tensor and linearized gravitational fields in flat spacetime. In the limit these equations reduce to those of spinless particles. We also show the renormalizability of these theories. (author). 10 refs
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Academic College, Jerusalem (Israel)
2017-12-15
It has recently been demonstrated that asymptotically flat neutral reflecting stars are characterized by an intriguing no-hair property. In particular, it has been proved that these horizonless compact objects cannot support spatially regular static matter configurations made of scalar (spin-0) fields, vector (spin-1) fields and tensor (spin-2) fields. In the present paper we shall explicitly prove that spherically symmetric compact reflecting stars can support stationary (rather than static) bound-state massive scalar fields in their exterior spacetime regions. To this end, we solve analytically the Klein-Gordon wave equation for a linearized scalar field of mass μ and proper frequency ω in the curved background of a spherically symmetric compact reflecting star of mass M and radius R{sub s}. It is proved that the regime of existence of these stationary composed star-field configurations is characterized by the simple inequalities 1 - 2M/R{sub s} < (ω/μ){sup 2} < 1. Interestingly, in the regime M/R{sub s} << 1 of weakly self-gravitating stars we derive a remarkably compact analytical equation for the discrete spectrum {ω(M,R_s, μ)}{sup n=∞}{sub n=1} of resonant oscillation frequencies which characterize the stationary composed compact-reflecting-star-linearized-massive-scalar-field configurations. Finally, we verify the accuracy of the analytically derived resonance formula of the composed star-field configurations with direct numerical computations. (orig.)
Holographic dark energy in Brans-Dicke cosmology with chameleon scalar field
International Nuclear Information System (INIS)
Setare, M.R.; Jamil, Mubasher
2010-01-01
We study a cosmological implication of holographic dark energy in the Brans-Dicke gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our analysis shows that one can obtain the phantom crossing scenario if the model parameter α (of order unity) is tuned accordingly. Moreover, this behavior is achieved by treating the Brans-Dicke scalar field as a Chameleon scalar field and taking a non-minimal coupling of the scalar field with matter. Hence one can generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans-Dicke cosmology framework.
Holographic dark energy in Brans-Dicke cosmology with chameleon scalar field
Energy Technology Data Exchange (ETDEWEB)
Setare, M.R., E-mail: rezakord@ipm.i [Department of Science of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of); Jamil, Mubasher, E-mail: mjamil@camp.edu.p [Center for Advanced Mathematics and Physics, National University of Sciences and Technology, Rawalpindi 46000 (Pakistan)
2010-06-07
We study a cosmological implication of holographic dark energy in the Brans-Dicke gravity. We employ the holographic model of dark energy to obtain the equation of state for the holographic energy density in non-flat (closed) universe enclosed by the event horizon measured from the sphere of horizon named L. Our analysis shows that one can obtain the phantom crossing scenario if the model parameter {alpha} (of order unity) is tuned accordingly. Moreover, this behavior is achieved by treating the Brans-Dicke scalar field as a Chameleon scalar field and taking a non-minimal coupling of the scalar field with matter. Hence one can generate phantom-like equation of state from a holographic dark energy model in non-flat universe in the Brans-Dicke cosmology framework.
Energy Technology Data Exchange (ETDEWEB)
Coelho, L A A [Programa de Pos-Graduacao em Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana, Rio de Janeiro, RJ, 20550-900 (Brazil); Skea, J E F [Departamento de Fisica Teorica, Instituto de Fisica, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana, Rio de Janeiro, RJ, 20550-900 (Brazil); Stuchi, T J [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Ilha do Fundao, Caixa Postal 68528, Rio de Janeiro, RJ, 21945-970 (Brazil)], E-mail: luis@dft.if.uerj.br, E-mail: jimsk@dft.if.uerj.br, E-mail: tstuchi@if.ufrj.br
2008-02-22
In this paper, we use a nonintegrability theorem by Morales and Ramis to analyse the integrability of Friedmann-Robertson-Walker cosmological models with a conformally coupled massive scalar field. We answer the long-standing question of whether these models with a vanishing cosmological constant and non-self-interacting scalar field are integrable: by applying Kovacic's algorithm to the normal variational equations, we prove analytically and rigorously that these equations and, consequently, the Hamiltonians are nonintegrable. We then address the models with a self-interacting massive scalar field and cosmological constant and show that, with the exception of a set of measure zero, the models are nonintegrable. For the spatially curved cases, we prove that there are no additional integrable cases other than those identified in the previous work based on the non-rigorous Painleve analysis. In our study of the spatially flat model, we explicitly obtain a new possibly integrable case.
New holographic scalar field models of dark energy in non-flat universe
Energy Technology Data Exchange (ETDEWEB)
Karami, K., E-mail: KKarami@uok.ac.i [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Fehri, J. [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of)
2010-02-08
Motivated by the work of Granda and Oliveros [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199], we generalize their work to the non-flat case. We study the correspondence between the quintessence, tachyon, K-essence and dilaton scalar field models with the new holographic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe. In the limiting case of a flat universe, i.e. k=0, all results given in [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199] are obtained.
New holographic scalar field models of dark energy in non-flat universe
International Nuclear Information System (INIS)
Karami, K.; Fehri, J.
2010-01-01
Motivated by the work of Granda and Oliveros [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199], we generalize their work to the non-flat case. We study the correspondence between the quintessence, tachyon, K-essence and dilaton scalar field models with the new holographic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe. In the limiting case of a flat universe, i.e. k=0, all results given in [L.N. Granda, A. Oliveros, Phys. Lett. B 671 (2009) 199] are obtained.
Search for Chameleon Scalar Fields with the Axion Dark Matter Experiment
International Nuclear Information System (INIS)
Rybka, G.; Hotz, M.; Rosenberg, L. J; Asztalos, S. J.; Carosi, G.; Hagmann, C.; Kinion, D.; van Bibber, K.; Hoskins, J.; Martin, C.; Sikivie, P.; Tanner, D. B.; Bradley, R.; Clarke, J.
2010-01-01
Scalar fields with a 'chameleon' property, in which the effective particle mass is a function of its local environment, are common to many theories beyond the standard model and could be responsible for dark energy. If these fields couple weakly to the photon, they could be detectable through the afterglow effect of photon-chameleon-photon transitions. The ADMX experiment was used in the first chameleon search with a microwave cavity to set a new limit on scalar chameleon-photon coupling β γ excluding values between 2x10 9 and 5x10 14 for effective chameleon masses between 1.9510 and 1.9525 μeV.
International Nuclear Information System (INIS)
Pozdeeva, Ekaterina O.; Vernov, Sergey Yu.; Skugoreva, Maria A.; Toporensky, Alexey V.
2016-01-01
We explore dynamics of cosmological models with bounce solutions evolving on a spatially flat Friedmann-Lemaître-Robertson-Walker background. We consider cosmological models that contain the Hilbert-Einstein curvature term, the induced gravity term with a negative coupled constant, and even polynomial potentials of the scalar field. Bounce solutions with non-monotonic Hubble parameters have been obtained and analyzed. The case when the scalar field has the conformal coupling and the Higgs-like potential with an opposite sign is studied in detail. In this model the evolution of the Hubble parameter of the bounce solution essentially depends on the sign of the cosmological constant.
International Nuclear Information System (INIS)
Wang Fan; Chen Xiangsong; Lue Xiaofu; Sun Weiming; Goldman, T.
2010-01-01
It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However, we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relations. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relations, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed.
Supersymmetric gauge theories, quantization of M{sub flat}, and conformal field theory
Energy Technology Data Exchange (ETDEWEB)
Teschner, J.; Vartanov, G.S.
2013-02-15
We propose a derivation of the correspondence between certain gauge theories with N=2 supersymmetry and conformal field theory discovered by Alday, Gaiotto and Tachikawa in the spirit of Seiberg-Witten theory. Based on certain results from the literature we argue that the quantum theory of the moduli spaces of flat SL(2,R)-connections represents a nonperturbative ''skeleton'' of the gauge theory, protected by supersymmetry. It follows that instanton partition functions can be characterized as solutions to a Riemann-Hilbert type problem. In order to solve it, we describe the quantization of the moduli spaces of flat connections explicitly in terms of two natural sets of Darboux coordinates. The kernel describing the relation between the two pictures represents the solution to the Riemann Hilbert problem, and is naturally identified with the Liouville conformal blocks.
Flux quantization and quantum mechanics on Riemann surfaces in an external magnetic field
International Nuclear Information System (INIS)
Bolte, J.; Steiner, F.
1990-10-01
We investigate the possibility to apply an external constant magnetic field to a quantum mechanical system consisting of a particle moving on a compact or non-compact two-dimensional manifold of constant negative Gaussian curvature and of finite volume. For the motion on compact Riemann surfaces we find that a consistent formulation is only possible if the magnetic flux is quantized, as it is proportional to the (integrated) first Chern class of a certain complex line bundle over the manifold. In the case of non-compact surfaces of finite volume we obtain the striking result that the magnetic flux has to vanish identically due to the theorem that any holomorphic line bundle over a non-compact Riemann surface is holomorphically trivial. (orig.)
Reconstruction of the Scalar Field Potential in Inflationary Models with a Gauss-Bonnet term
Koh, Seoktae; Lee, Bum-Hoon; Tumurtushaa, Gansukh
2017-06-01
We consider inflationary models with a Gauss-Bonnet term to reconstruct the scalar-field potentials and the Gauss-Bonnet coupling functions. Both expressions are derived from the observationally favored configurations of ns and r . Our result implies that, for the reconstructed potentials and coupling functions, the blue tilt of inflationary tensor fluctuations can be realized. To achieve a blue tilt for the inflationary tensor fluctuations, a scalar field must climb up its potential before rolling down. We further investigate the properties of propagation of the perturbation modes in Friedmann-Robertson-Walker spacetime. For the reconstructed configurations that give rise to the blue tilt for the inflationary tensor fluctuations, we show that the ghosts and instabilities are absent with the superluminal propagation speeds for the scalar perturbation modes, whereas the propagation speeds of the tensor perturbations are subluminal.
Open Wilson lines and generalized star product in noncommutative scalar field theories
International Nuclear Information System (INIS)
Kiem, Youngjai; Sato, Haru-Tada; Rey, Soo-Jong; Yee, Jung-Tay
2002-01-01
Open Wilson line operators and a generalized star product have been studied extensively in noncommutative gauge theories. We show that they also show up in noncommutative scalar field theories as universal structures. We first point out that the dipole picture of noncommutative geometry provides an intuitive argument for the robustness of the open Wilson lines and generalized star products therein. We calculate the one-loop effective action of noncommutative scalar field theory with a cubic self-interaction and show explicitly that the generalized star products arise in the nonplanar part. It is shown that, at the low-energy, large noncommutativity limit, the nonplanar part is expressible solely in terms of the scalar open Wilson line operator and descendants
International Nuclear Information System (INIS)
Hueffel, H.
1990-01-01
After a brief review of the BRST formalism and of the Parisi-Wu stochastic quantization method we introduce the BRST stochastic quantization scheme. It allows the second quantization of constrained Hamiltonian systems in a manifestly gauge symmetry preserving way. The examples of the relativistic particle, the spinning particle and the bosonic string are worked out in detail. The paper is closed by a discussion on the interacting field theory associated to the relativistic point particle system. 58 refs. (Author)
Finite size effects in the thermodynamics of a free neutral scalar field
Parvan, A. S.
2018-04-01
The exact analytical lattice results for the partition function of the free neutral scalar field in one spatial dimension in both the configuration and the momentum space were obtained in the framework of the path integral method. The symmetric square matrices of the bilinear forms on the vector space of fields in both configuration space and momentum space were found explicitly. The exact lattice results for the partition function were generalized to the three-dimensional spatial momentum space and the main thermodynamic quantities were derived both on the lattice and in the continuum limit. The thermodynamic properties and the finite volume corrections to the thermodynamic quantities of the free real scalar field were studied. We found that on the finite lattice the exact lattice results for the free massive neutral scalar field agree with the continuum limit only in the region of small values of temperature and volume. However, at these temperatures and volumes the continuum physical quantities for both massive and massless scalar field deviate essentially from their thermodynamic limit values and recover them only at high temperatures or/and large volumes in the thermodynamic limit.
Finite action for three dimensional gravity with a minimally coupled scalar field
International Nuclear Information System (INIS)
Gegenberg, Jack; Martinez, Cristian; Troncoso, Ricardo
2003-01-01
Three-dimensional gravity with a minimally coupled self-interacting scalar is considered. The falloff of the fields at infinity is assumed to be slower than that of a localized distribution of matter in the presence of a negative cosmological constant. However, the asymptotic symmetry group remains to be the conformal group. The counterterm Lagrangian needed to render the action finite is found by demanding that the action attain an extremum for the boundary conditions implied by the above falloff of the fields at infinity. These counterterms explicitly depend on the scalar field. As a consequence, the Brown-York stress-energy tensor acquires a nontrivial contribution from the matter sector. Static circularly symmetric solutions with a regular scalar field are explored for a one-parameter family of potentials. Their masses are computed via the Brown-York quasilocal stress-energy tensor, and they coincide with the values obtained from the Hamiltonian approach. The thermal behavior, including the transition between different configurations, is analyzed, and it is found that the scalar black hole can decay into the Banados-Teitelboim-Zanelli solution irrespective of the horizon radius. It is also shown that the AdS conformal field theory correspondence yields the same central charge as for pure gravity
Gupta-Bleuler Quantization of the Maxwell Field in Globally Hyperbolic Space-Times
Finster, Felix; Strohmaier, Alexander
2015-08-01
We give a complete framework for the Gupta-Bleuler quantization of the free electromagnetic field on globally hyperbolic space-times. We describe one-particle structures that give rise to states satisfying the microlocal spectrum condition. The field algebras in the so-called Gupta-Bleuler representations satisfy the time-slice axiom, and the corresponding vacuum states satisfy the microlocal spectrum condition. We also give an explicit construction of ground states on ultrastatic space-times. Unlike previous constructions, our method does not require a spectral gap or the absence of zero modes. The only requirement, the absence of zero-resonance states, is shown to be stable under compact perturbations of topology and metric. Usual deformation arguments based on the time-slice axiom then lead to a construction of Gupta-Bleuler representations on a large class of globally hyperbolic space-times. As usual, the field algebra is represented on an indefinite inner product space, in which the physical states form a positive semi-definite subspace. Gauge transformations are incorporated in such a way that the field can be coupled perturbatively to a Dirac field. Our approach does not require any topological restrictions on the underlying space-time.
Anomalous scaling of a scalar field advected by turbulence
Energy Technology Data Exchange (ETDEWEB)
Kraichnan, R.H. [Robert H. Kraichnan, Inc., Santa Fe, NM (United States)
1995-12-31
Recent work leading to deduction of anomalous scaling exponents for the inertial range of an advected passive field from the equations of motion is reviewed. Implications for other turbulence problems are discussed.
AdS collapse of a scalar field in higher dimensions
International Nuclear Information System (INIS)
Jalmuzna, Joanna; Rostworowski, Andrzej; Bizon, Piotr
2011-01-01
We show that the weakly turbulent instability of anti-de Sitter space, recently found in P. Bizon and A. Rostworowski, Phys. Rev. Lett. 107, 031102 (2011) for 3+1-dimensional spherically symmetric Einstein-massless-scalar field equations with negative cosmological constant, is present in all dimensions d+1 for d≥3.
A comment on AdS collapse of a scalar field in higher dimensions
Jałmużna, Joanna; Rostworowski, Andrzej; Bizoń, Piotr
2011-01-01
We point out that the weakly turbulent instability of anti-de Sitter space, recently found in arXiv:1104.3702 for four dimensional spherically symmetric Einstein-massless-scalar field equations with negative cosmological constant, is present in all dimensions $d+1$ for $d\\geq 3$, contrary to a claim made in arXiv:1106.2339.
Wormhole solutions with a complex ghost scalar field and their instability
Dzhunushaliev, Vladimir; Folomeev, Vladimir; Kleihaus, Burkhard; Kunz, Jutta
2018-01-01
We study compact configurations with a nontrivial wormholelike spacetime topology supported by a complex ghost scalar field with a quartic self-interaction. For this case, we obtain regular asymptotically flat equilibrium solutions possessing reflection symmetry. We then show their instability with respect to linear radial perturbations.
Stochastic quantum inflation for a canonical scalar field with linear self-interaction potential
Energy Technology Data Exchange (ETDEWEB)
Panotopoulos, Grigoris [CENTRA, Instituto Superior Tecnico, Universidade de Lisboa, Lisboa (Portugal)
2017-10-15
We apply Starobinsky's formalism of stochastic inflation to the case of a massless minimally coupled scalar field with linear self-interaction potential. We solve the corresponding Fokker-Planck equation exactly, and we obtain analytical expressions for the stochastic expectation values. (orig.)
Green's functions for a scalar fields in a class of Robertson-Walker space-times
International Nuclear Information System (INIS)
Mankin, Romi; Ainsaar, Ain
1997-01-01
The retarded and advanced Green's functions for a massless non conformally-coupled scalar field in a class of Robertson-Walker space-times are calculated analytically. The results are applied to the calculation of the Hadamard fundamental solutions in some special cases. (author)
Note on the evolution of the gravitational potential in Rastall scalar field theories
International Nuclear Information System (INIS)
Fabris, J.C.; Hamani Daouda, M.; Piattella, O.F.
2012-01-01
We investigate the evolution of the gravitational potential in Rastall scalar field theories. In a single component model a consistent perturbation theory, formulated in the Newtonian gauge, is possible only for γ=1, which is the General Relativity limit. On the other hand, the addition of another canonical fluid component allows to consider the case γ≠1.
Solar system tests of scalar field models with an exponential potential
International Nuclear Information System (INIS)
Paramos, J.; Bertolami, O.
2008-01-01
We consider a scenario where the dynamics of a scalar field is ruled by an exponential potential, such as those arising from some quintessence-type models, and aim at obtaining phenomenological manifestations of this entity within our Solar System. To do so, we assume a perturbative regime, derive the perturbed Schwarzschild metric, and extract the relevant post-Newtonian parameters.
Propagators for a scalar field in a homogeneous expanding universe, 1
International Nuclear Information System (INIS)
Nariai, Hidekazu; Tanabe, Kenji.
1975-11-01
In view of a recent interest in the quantum field-theoretical creation of particles in a big-bang universe (which, via the problem how their vacuum state should be defined, will be connected with their propagators whose structure depends also on that of the universe), our previous formulae for bi-scalar Green's functions corresponding to a massless scalar field in the radiation- and matter-dominated stages of the Friedmann universe with flat 3-space are extended in a classical level. One is to derive the formulae for a massive scalar field in the same universe, and another lies in deriving the ones applicable to the respective stages of a closed universe with spherical topology. As an application, we discuss a massless scalar field (e.g., photons or gravitons defined suitably) and its physical property in the cases where its source distribution is spatially uniform and where that is of a delta-singularity. It is shown that the energy-momentum tensor in the first case is formally the same as a perfect fluid whose sound velocity relative to the light velocity is unity, while the tensor in the second case leads naturally to Robertson's formula for the apparent luminosity of a receding galaxy. The behavior of photons or gravitons generated from a turbulent medium in an early universe is also dealt with. (auth.)
Hawking temperature and scalar field fluctuations in the de-Sitter space
International Nuclear Information System (INIS)
Rozhanskij, L.V.
1988-01-01
It is shown that diffusion equation for scalar field fluctuations in the de-Sitter space corresponds to Hawking temperature. The relationship between stationary solution of the equation and Hartle-Hawking instanton at random space dimensionality and any type of gravitational effect has been established
Alternative mechanism of avoiding the big rip or little rip for a scalar phantom field
International Nuclear Information System (INIS)
Xi Ping; Zhai Xianghua; Li Xinzhou
2012-01-01
Depending on the choice of its potential, the scalar phantom field φ (the equation of state parameter w 2 correction. The singularity is avoidable under all these potentials. Hence, we conclude that the avoidance of big or little rip is hardly dependent on special potential.
Relating double field theory to the scalar potential of N=2 gauged supergravity
Energy Technology Data Exchange (ETDEWEB)
Blumenhagen, Ralph [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, München, 80805 (Germany); Font, Anamaria [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, München, 80805 (Germany); Arnold Sommerfeld Center for Theoretical Physics, LMU,Theresienstr. 37, München, 80333 (Germany); Plauschinn, Erik [Arnold Sommerfeld Center for Theoretical Physics, LMU,Theresienstr. 37, München, 80333 (Germany)
2015-12-18
The double field theory action in the flux formulation is dimensionally reduced on a Calabi-Yau three-fold equipped with non-vanishing type IIB geometric and non-geometric fluxes. First, we rewrite the metric-dependent reduced DFT action in terms of quantities that can be evaluated without explicitly knowing the metric on the Calabi-Yau manifold. Second, using properties of special geometry we obtain the scalar potential of N=2 gauged supergravity. After an orientifold projection, this potential is consistent with the scalar potential arising from the flux-induced superpotential, plus an additional D-term contribution.
Revisiting the conformal invariance of the scalar field: From Minkowski space to de Sitter space
International Nuclear Information System (INIS)
Huguet, E.; Queva, J.; Renaud, J.
2008-01-01
In this article, we clarify the link between the conformal (i.e. Weyl) correspondence from the Minkowski space to the de Sitter space and the conformal [i.e. SO(2,d)] invariance of the conformal scalar field on both spaces. We exhibit the realization on de Sitter space of the massless scalar representation of SO(2,d). It is obtained from the corresponding representation in Minkowski space through an intertwining operator inherited from the Weyl relation between the two spaces. The de Sitter representation is written in a form which allows one to take the point of view of a Minkowskian observer who sees the effect of curvature through additional terms
Neutral and charged scalar mesons, pseudoscalar mesons, and diquarks in magnetic fields
Liu, Hao; Wang, Xinyang; Yu, Lang; Huang, Mei
2018-04-01
We investigate both (pseudo)scalar mesons and diquarks in the presence of external magnetic field in the framework of the two-flavored Nambu-Jona-Lasinio (NJL) model, where mesons and diquarks are constructed by infinite sum of quark-loop chains by using random phase approximation. The polarization function of the quark-loop is calculated to the leading order of 1 /Nc expansion by taking the quark propagator in the Landau level representation. We systematically investigate the masses behaviors of scalar σ meson, neutral and charged pions as well as the scalar diquarks, with respect to the magnetic field strength at finite temperature and chemical potential. It is shown that the numerical results of both neutral and charged pions are consistent with the lattice QCD simulations. The mass of the charge neutral pion keeps almost a constant under the magnetic field, which is preserved by the remnant symmetry of QCD ×QED in the vacuum. The mass of the charge neutral scalar σ is around two times quark mass and increases with the magnetic field due to the magnetic catalysis effect, which is an typical example showing that the polarized internal quark structure cannot be neglected when we consider the meson properties under magnetic field. For the charged particles, the one quark-antiquark loop contribution to the charged π± increases essentially with the increase of magnetic fields due to the magnetic catalysis of the polarized quarks. However, the one quark-quark loop contribution to the scalar diquark mass is negative comparing with the point-particle result and the loop effect is small.
Barbero-Immirzi parameter as a scalar field: K-inflation from loop quantum gravity?
International Nuclear Information System (INIS)
Taveras, Victor; Yunes, Nicolas
2008-01-01
We consider a loop-quantum gravity inspired modification of general relativity, where the Holst action is generalized by making the Barbero-Immirzi (BI) parameter a scalar field, whose value could be dynamically determined. The modified theory leads to a nonzero torsion tensor that corrects the field equations through quadratic first derivatives of the BI field. Such a correction is equivalent to general relativity in the presence of a scalar field with nontrivial kinetic energy. This stress energy of this field is automatically covariantly conserved by its own dynamical equations of motion, thus satisfying the strong equivalence principle. Every general relativistic solution remains a solution to the modified theory for any constant value of the BI field. For arbitrary time-varying BI fields, a study of cosmological solutions reduces the scalar-field stress energy to that of a pressureless perfect fluid in a comoving reference frame, forcing the scale-factor dynamics to be equivalent to those of a stiff equation of state. Upon ultraviolet completion, this model could provide a natural mechanism for k inflation, where the role of the inflaton is played by the BI field and inflation is driven by its nontrivial kinetic energy instead of a potential.
Entanglement growth after a global quench in free scalar field theory
Energy Technology Data Exchange (ETDEWEB)
Cotler, Jordan S. [Stanford Institute for Theoretical Physics, Department of Physics, Stanford University, Stanford, CA 94305 (United States); Hertzberg, Mark P. [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Mezei, Márk [Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544 (United States); Mueller, Mark T. [Center for Theoretical Physics, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2016-11-28
We compute the entanglement and Rényi entropy growth after a global quench in various dimensions in free scalar field theory. We study two types of quenches: a boundary state quench and a global mass quench. Both of these quenches are investigated for a strip geometry in 1, 2, and 3 spatial dimensions, and for a spherical geometry in 2 and 3 spatial dimensions. We compare the numerical results for massless free scalars in these geometries with the predictions of the analytical quasiparticle model based on EPR pairs, and find excellent agreement in the limit of large region sizes. At subleading order in the region size, we observe an anomalous logarithmic growth of entanglement coming from the zero mode of the scalar.
Vacuum stability of a general scalar potential of a few fields
Energy Technology Data Exchange (ETDEWEB)
Kannike, Kristjan [NICPB, Tallinn (Estonia)
2016-06-15
We calculate analytical vacuum stability or bounded from below conditions for general scalar potentials of a few fields. After a brief review of copositivity, we show how to find positivity conditions for more complicated potentials. We discuss the vacuum stability conditions of the general potential of two real scalars, without and with the Higgs boson included in the potential. As further examples, we give explicit vacuum stability conditions for the two Higgs doublet model with no explicit CP breaking, and for the Z{sub 3} scalar dark matter with an inert doublet and a complex singlet. We give a short overview of positivity conditions for tensors of quartic couplings via tensor eigenvalues. (orig.)
PDF approach for turbulent scalar field: Some recent developments
Gao, Feng
1993-01-01
The probability density function (PDF) method has been proven a very useful approach in turbulence research. It has been particularly effective in simulating turbulent reacting flows and in studying some detailed statistical properties generated by a turbulent field There are, however, some important questions that have yet to be answered in PDF studies. Our efforts in the past year have been focused on two areas. First, a simple mixing model suitable for Monte Carlo simulations has been developed based on the mapping closure. Secondly, the mechanism of turbulent transport has been analyzed in order to understand the recently observed abnormal PDF's of turbulent temperature fields generated by linear heat sources.
Topological black holes dressed with a conformally coupled scalar field and electric charge
International Nuclear Information System (INIS)
Martinez, Cristian; Troncoso, Ricardo; Staforelli, Juan Pablo
2006-01-01
Electrically charged solutions for gravity with a conformally coupled scalar field are found in four dimensions in the presence of a cosmological constant. If a quartic self-interaction term for the scalar field is considered, there is a solution describing an asymptotically locally AdS charged black hole dressed with a scalar field that is regular on and outside the event horizon, which is a surface of negative constant curvature. This black hole can have negative mass, which is bounded from below for the extremal case, and its causal structure shows that the solution describes a ''black hole inside a black hole''. The thermodynamics of the nonextremal black hole is analyzed in the grand canonical ensemble. The entropy does not follow the area law, and there is an effective Newton constant which depends on the value of the scalar field at the horizon. If the base manifold is locally flat, the solution has no electric charge, and the scalar field has a vanishing stress-energy tensor so that it dresses a locally AdS spacetime with a nut at the origin. In the case of vanishing self interaction, the solutions also dress locally AdS spacetimes, and if the base manifold is of negative constant curvature a massless electrically charged hairy black hole is obtained. The thermodynamics of this black hole is also analyzed. It is found that the bounds for the black holes parameters in the conformal frame obtained from requiring the entropy to be positive are mapped into the ones that guarantee cosmic censorship in the Einstein frame
Inflation and inhomogeneities: a hybrid quantization
International Nuclear Information System (INIS)
Olmedo, J; Fernández-Méndez, M; Mena Marugán, G A
2012-01-01
We provide a complete quantization of a homogeneous and isotropic spacetime with positive spatial curvature coupled to a massive scalar field in the framework of Loop Quantum Cosmology. The physical Hilbert space is constructed out of the space of initial data on the minimum volume section. By means of a perturbative treatment we introduce inhomogeneities and thereafter we adopt a hybrid quantum approach, in which these inhomogeneous degrees of freedom are described by a standard Fock quantization. For the considered case of compact spatial topology, the requirements of: i) invariance of the vacuum state under the spatial isometries, and ii) unitary implementation of the quantum dynamics, pick up a privileged set of canonical fields and a unique Fock representation (up to unitary equivalence).
Energy Technology Data Exchange (ETDEWEB)
Karami, K., E-mail: KKarami@uok.ac.i [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Khaledian, M.S.; Felegary, F.; Azarmi, Z. [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of)
2010-03-29
We study the correspondence between the tachyon, K-essence and dilaton scalar field models with the interacting new agegraphic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe.
International Nuclear Information System (INIS)
Karami, K.; Khaledian, M.S.; Felegary, F.; Azarmi, Z.
2010-01-01
We study the correspondence between the tachyon, K-essence and dilaton scalar field models with the interacting new agegraphic dark energy model in the non-flat FRW universe. We reconstruct the potentials and the dynamics for these scalar field models, which describe accelerated expansion of the universe.
Power-law modulation of the scalar power spectrum from a heavy field with a monomial potential
Huang, Qing-Guo; Pi, Shi
2018-04-01
The effects of heavy fields modulate the scalar power spectrum during inflation. We analytically calculate the modulations of the scalar power spectrum from a heavy field with a separable monomial potential, i.e. V(phi)~ phin. In general the modulation is characterized by a power-law oscillation which is reduced to the logarithmic oscillation in the case of n=2.
International Nuclear Information System (INIS)
Accioly, A.J.
1985-01-01
Exact solutions of the Einstein-Conformally Invariant Scalar Field Equations are obtained for Kantowski-Sachs and Bianchi types I and III cosmologies. The presence of the conformally invariant scalar field is responsible for some interesting features of the solutions. In particular it is found that the Bianchi I model is consistent with the big-bang theory of cosmology. (Author) [pt
Gravitational self-interactions of a degenerate quantum scalar field
Chakrabarty, Sankha S.; Enomoto, Seishi; Han, Yaqi; Sikivie, Pierre; Todarello, Elisa M.
2018-02-01
We develop a formalism to help calculate in quantum field theory the departures from the description of a system by classical field equations. We apply the formalism to a homogeneous condensate with attractive contact interactions and to a homogeneous self-gravitating condensate in critical expansion. In their classical descriptions, such condensates persist forever. We show that in their quantum description, parametric resonance causes quanta to jump in pairs out of the condensate into all modes with wave vector less than some critical value. We calculate, in each case, the time scale over which the homogeneous condensate is depleted and after which a classical description is invalid. We argue that the duration of classicality of inhomogeneous condensates is shorter than that of homogeneous condensates.
Field-induced Gap and Quantized Charge Pumping in Nano-helix
Energy Technology Data Exchange (ETDEWEB)
Qi, Xiao-Liang; /Stanford U., Phys. Dept. /Tsinghua U., Beijing; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.
2010-02-15
We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to 'geometrically' constructing one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a new standard for the high precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nano-scale electro-mechanical motors. Finally, our methodology also enables new ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.
The average action for scalar fields near phase transitions
International Nuclear Information System (INIS)
Wetterich, C.
1991-08-01
We compute the average action for fields in two, three and four dimensions, including the effects of wave function renormalization. A study of the one loop evolution equations for the scale dependence of the average action gives a unified picture of the qualitatively different behaviour in various dimensions for discrete as well as abelian and nonabelian continuous symmetry. The different phases and the phase transitions can be infered from the evolution equation. (orig.)
A sensitive search for dark energy through chameleon scalar fields using neutron interferometry
International Nuclear Information System (INIS)
Snow, W M; Li, K; Skavysh, V; Arif, M; Huber, M; Heacock, B; Young, A R; Pushin, D
2015-01-01
The physical origin of the dark energy, which is postulated to cause the accelerated expansion rate of the universe, is one of the major open questions of cosmology. A large subset of theories postulate the existence of a scalar field with a nonlinear coupling to matter chosen so that the effective range and/or strength of the field is greatly suppressed unless the source is placed in vacuum. We describe a measurement using neutron interferometry which can place a stringent upper bound on chameleon fields proposed as a solution to the problem of the origin of dark energy of the universe in the regime with a strongly-nolinear coupling term. In combination with other experiments searching for exotic short-range forces and laser-based measurements, slow neutron experiments are capable of eliminating this and many similar types of scalar-field-based dark energy models by laboratory experiments
Hamiltonian description of the parametrized scalar field in bounded spatial regions
International Nuclear Information System (INIS)
Barbero G, J Fernando; Margalef-Bentabol, Juan; Villaseñor, Eduardo J S
2016-01-01
We study the Hamiltonian formulation for a parametrized scalar field in a regular bounded spatial region subject to Dirichlet, Neumann and Robin boundary conditions. We generalize the work carried out by a number of authors on parametrized field systems to the interesting case where spatial boundaries are present. The configuration space of our models contains both smooth scalar fields defined on the spatial manifold and spacelike embeddings from the spatial manifold to a target spacetime endowed with a fixed Lorentzian background metric. We pay particular attention to the geometry of the infinite dimensional manifold of embeddings and the description of the relevant geometric objects: the symplectic form on the primary constraint submanifold and the Hamiltonian vector fields defined on it. (paper)
Matrix model approximations of fuzzy scalar field theories and their phase diagrams
Energy Technology Data Exchange (ETDEWEB)
Tekel, Juraj [Department of Theoretical Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska Dolina, Bratislava, 842 48 (Slovakia)
2015-12-29
We present an analysis of two different approximations to the scalar field theory on the fuzzy sphere, a nonperturbative and a perturbative one, which are both multitrace matrix models. We show that the former reproduces a phase diagram with correct features in a qualitative agreement with the previous numerical studies and that the latter gives a phase diagram with features not expected in the phase diagram of the field theory.
International Nuclear Information System (INIS)
Buchbinder, I.L.; Lyakhovich, S.L.; Pershin, V.D.; Fradkin, E.S.
1991-01-01
At present, superstring theory is the only candidate to be a unified theory of all fundamental interactions. For this reason, the various aspects of the string theory have been attracting great attention. String theory has a nontrivial gauge symmetry and therefore is an interesting object from the viewpoint of application of general quantization methods. This paper discusses the bosonic string theory. The purpose of this paper is a consistent operator quantization of the theory with the action. The natural basis for it is provided by the method of the generalized canonical quantization
Exact solutions for scalar field cosmology in f(R) gravity
Maharaj, S. D.; Goswami, R.; Chervon, S. V.; Nikolaev, A. V.
2017-09-01
We study scalar field FLRW cosmology in the content of f(R) gravity. Our consideration is restricted to the spatially flat Friedmann universe. We derived the general evolution equations of the model, and showed that the scalar field equation is automatically satisfied for any form of the f(R) function. We also derived representations for kinetic and potential energies, as well as for the acceleration in terms of the Hubble parameter and the form of the f(R) function. Next we found the exact cosmological solutions in modified gravity without specifying the f(R) function. With negligible acceleration of the scalar curvature, we found that the de Sitter inflationary solution is always attained. Also we obtained new solutions with special restrictions on the integration constants. These solutions contain oscillating, accelerating, decelerating and even contracting universes. For further investigation, we selected special cases which can be applied with early or late inflation. We also found exact solutions for the general case for the model with negligible acceleration of the scalar curvature in terms of special Airy functions. Using initial conditions which represent the universe at the present epoch, we determined the constants of integration. This allows for the comparison of the scale factor in the new solutions with that for current stage of the universe evolution in the ΛCDM model.
Massive spin-one fields from couplings with five massless real scalars
Bizdadea, Constantin; Cioroianu, Eugen-Mihaita; Saliu, Solange-Odile
2017-12-01
In this paper we implement a new procedure by which one may generate mass for a vector field in the context of its interactions to a system of five real scalar fields. This purpose will be achieved by means of the general multi-step program from [1] adapted to the present situation: (1) we begin with a free theory in four space-time dimensions whose Lagrangian action is given by the sum between the standard Maxwell action and that for a collection consisting in five massless real scalar fields; (2) we construct a general class of gauge theories whose free limit is that from step (1) by means of the deformation of the solution to the master equation [2, 3] with the help of local BRST cohomology [4-6]; (3) we perform some suitable redefinitions of the free parameters that label interacting theories from (2) such that the mass terms become manifest in the new free limit. The outputs of our procedure can be synthesized in: (A) the vector field acquires mass; (B) the scalar fields gain gauge transformations; (C) the gauge algebras of the interacting theories are Abelian; (D) the propagator of the massive vector field emerging from the gauge-fixed actions behaves, in the limit of large Euclidean momenta, like that from the massless case.
A C*-algebra formulation of the quantization of the electromagnetic field
International Nuclear Information System (INIS)
Carey, A.L.; Gaffney, J.M.; Hurst, C.A.
1977-01-01
A presentation of the Fermi, Gupta--Bleuler, and radiation gauge methods for quantizing the free electromagnetic field is given in the Weyl algebra formalism for quantum field theory first introduced by Segal. The abstract Weyl algebra of the vector potential is defined using the formalism of Manuceau. Then the Fermi and Gupta--Bleuler methods are given as schemes for constructing representations of the algebra. The algebra of the physical photons is shown to be a factor algebra of a certain subalgebra of the original algebra of the vector potential. In this formalism, the application of the supplementary condition in the Fermi method, and the supplementary condition and indefinite metric in the Gupta--Bleuler method, can be interpreted as the means by which a representation of this factor algebra is obtained. The Weyl algebra of the physical photons is the Weyl algebra associated with the radiation gauge method. It is also shown that in the Fock representation of the Weyl algebra given by the Fermi method, automorphisms of the algebra corresponding to Lorentz transformations cannot always be implemented by unitary transformations. This leads us to construct a new representation of the Weyl algebra which provides a covariant representation for the vector potential
Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization
Energy Technology Data Exchange (ETDEWEB)
Cortez, Jerónimo, E-mail: jacq@ciencias.unam.mx [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Elizaga Navascués, Beatriz, E-mail: beatriz.elizaga@iem.cfmac.csic.es [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Martín-Benito, Mercedes, E-mail: m.martin@hef.ru.nl [Radboud University Nijmegen, Institute for Mathematics, Astrophysics and Particle Physics, Heyendaalseweg 135, NL-6525 AJ Nijmegen (Netherlands); Mena Marugán, Guillermo A., E-mail: mena@iem.cfmac.csic.es [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Velhinho, José M., E-mail: jvelhi@ubi.pt [Universidade da Beira Interior, Rua Marquês d’Ávila e Bolama, 6201-001, Covilhã (Portugal)
2017-01-15
We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.
Dirac fields in flat FLRW cosmology: Uniqueness of the Fock quantization
International Nuclear Information System (INIS)
Cortez, Jerónimo; Elizaga Navascués, Beatriz; Martín-Benito, Mercedes; Mena Marugán, Guillermo A.; Velhinho, José M.
2017-01-01
We address the issue of the infinite ambiguity that affects the construction of a Fock quantization of a Dirac field propagating in a cosmological spacetime with flat compact sections. In particular, we discuss a physical criterion that restricts to a unique possibility (up to unitary equivalence) the infinite set of available vacua. We prove that this desired uniqueness is guaranteed, for any possible choice of spin structure on the spatial sections, if we impose two conditions. The first one is that the symmetries of the classical system must be implemented quantum mechanically, so that the vacuum is invariant under the symmetry transformations. The second and more important condition is that the constructed theory must have a quantum dynamics that is implementable as a (non-trivial) unitary operator in Fock space. Actually, this unitarity of the quantum dynamics leads us to identify as explicitly time dependent some very specific contributions of the Dirac field. In doing that, we essentially characterize the part of the dynamics governed by the Dirac equation that is unitarily implementable. The uniqueness of the Fock vacuum is attained then once a physically motivated convention for the concepts of particles and antiparticles is fixed.
Some aspects of reconstruction using a scalar field in f(T) gravity
Energy Technology Data Exchange (ETDEWEB)
Chakrabarti, Soumya [Indian Institute of Technology, Centre for Theoretical Studies, Kharagpur (India); Said, Jackson Levi [University of Malta, Institute of Space Sciences and Astronomy, Msida, MSD (Malta); Farrugia, Gabriel [University of Malta, Department of Physics, Msida, MSD (Malta)
2017-12-15
General relativity characterizes gravity as a geometric property exhibited on spacetime by massive objects, while teleparallel gravity achieves the same results at the level of equations, by taking a torsional perspective of gravity. Similar to the f(R) theory teleparallel gravity can also be generalized to f(T), with the resulting field equations being inherently distinct from f(R) gravity in that they are second order, while in the former case they turn out to be fourth order. In the present case, a minimally coupled scalar field is investigated in the f(T) gravity context for several forms of the scalar field potential. A number of new f(T) solutions are found for these potentials. Their respective state parameters are also being examined. (orig.)
Nonconformal scalar field in uniform isotropic space and the method of Hamiltonian diagonalization
International Nuclear Information System (INIS)
Pavlov, Yu.V.
2001-01-01
One diagonalized metric Hamiltonian of scalar field with arbitrary relation with curvature in N-dimensional uniform isotropic space. One derived spectrum of energies of the appropriate quasi-particles. One calculated energy of quasi-particle appropriate to the canonical Hamiltonian diagonal shape. One structured a modified tensor of energy-pulse with the following features. In case of conformal scalar field it coincides with the metric tensor of energy-pulse. When it is diagonalized the energies of the appropriate particles of nonconformal field are equal to oscillation frequency and the number of such particles produced in non-stationary metric is the finite one. It is shown that Hamiltonian calculated on the basis of the modified tensor of energy-pulse may be derived as a canonical one at certain selection of variables [ru
Radiation tails of the scalar wave equation in a weak gravitational field
International Nuclear Information System (INIS)
Mankin, R.; Piir, I.
1974-01-01
A class of solutions of the linearized Einstein equations is found making use of the Newman-Penrose spin coefficient formalism. These solutions describe a weak retarded gravitational field with an arbitrary multipole structure. The study of the radial propagation of the scalar waves in this gravitational field shows that in the first approximation the tails of the scalar outgoing radiation appear either in the presence of a gravitational mass or in the case of a nonzero linear momentum of the gravitational source. The quadrupole moment and the higher multipole moments of the gravitational field as well as the constant dipole moment and the angular moment of the source do not contribute to the tail
Bose-Einstein condensation and symmetry breaking of a complex charged scalar field
International Nuclear Information System (INIS)
Matos, Tonatiuh; Castellanos, Elias; Suarez, Abril
2017-01-01
In this work the Klein-Gordon equation for a complex scalar field with U(1) symmetry endowed in a mexican-hat scalar field potential with thermal and electromagnetic contributions is written as a Gross-Pitaevskii (GP)-like equation. This equation is interpreted as a charged generalization of the GP equation at finite temperatures found in previous works. Its hydrodynamical representation is obtained and the corresponding thermodynamical properties are derived and related to measurable quantities. The condensation temperature in the non-relativistic regime associated with the aforementioned system within the semiclassical approximation is calculated. Also, a generalized equation for the conservation of energy for a charged bosonic gas is found when electromagnetic fields are introduced, and it is studied how under certain circumstances its breaking of symmetry can give some insight on the phase transition of the system not just into the condensed phase but also on other related systems. (orig.)
Bose-Einstein condensation and symmetry breaking of a complex charged scalar field
Energy Technology Data Exchange (ETDEWEB)
Matos, Tonatiuh [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Castellanos, Elias [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Universidad Autonoma de Chiapas, Mesoamerican Centre for Theoretical Physics, Tuxtla Gutierrez, Chiapas (Mexico); Suarez, Abril [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Universidad Politecnica Metropolitana de Hidalgo, Departamento de Aeronautica, Tolcayuca, Hidalgo (Mexico)
2017-08-15
In this work the Klein-Gordon equation for a complex scalar field with U(1) symmetry endowed in a mexican-hat scalar field potential with thermal and electromagnetic contributions is written as a Gross-Pitaevskii (GP)-like equation. This equation is interpreted as a charged generalization of the GP equation at finite temperatures found in previous works. Its hydrodynamical representation is obtained and the corresponding thermodynamical properties are derived and related to measurable quantities. The condensation temperature in the non-relativistic regime associated with the aforementioned system within the semiclassical approximation is calculated. Also, a generalized equation for the conservation of energy for a charged bosonic gas is found when electromagnetic fields are introduced, and it is studied how under certain circumstances its breaking of symmetry can give some insight on the phase transition of the system not just into the condensed phase but also on other related systems. (orig.)
On scalar and vector fields coupled to the energy-momentum tensor
Jiménez, Jose Beltrán; Cembranos, Jose A. R.; Sánchez Velázquez, Jose M.
2018-05-01
We consider theories for scalar and vector fields coupled to the energy-momentum tensor. Since these fields also carry a non-trivial energy-momentum tensor, the coupling prescription generates self-interactions. In analogy with gravity theories, we build the action by means of an iterative process that leads to an infinite series, which can be resumed as the solution of a set of differential equations. We show that, in some particular cases, the equations become algebraic and that is also possible to find solutions in the form of polynomials. We briefly review the case of the scalar field that has already been studied in the literature and extend the analysis to the case of derivative (disformal) couplings. We then explore theories with vector fields, distinguishing between gauge-and non-gauge-invariant couplings. Interactions with matter are also considered, taking a scalar field as a proxy for the matter sector. We also discuss the ambiguity introduced by superpotential (boundary) terms in the definition of the energy-momentum tensor and use them to show that it is also possible to generate Galileon-like interactions with this procedure. We finally use collider and astrophysical observations to set constraints on the dimensionful coupling which characterises the phenomenology of these models.
Fate of oscillating scalar fields in a thermal bath and their cosmological implications
Yokoyama, Jun'ichi
2004-11-01
Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and in an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.
Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames
International Nuclear Information System (INIS)
Khan, Salman; Khan, Niaz Ali; Khan, M.K.
2014-01-01
The π-tangle is used to study the behavior of entanglement of a nonmaximal tripartite state of both Dirac and scalar fields in accelerated frame. For Dirac fields, the degree of degradation with acceleration of both one-tangle of accelerated observer and π-tangle, for the same initial entanglement, is different by just interchanging the values of probability amplitudes. A fraction of both one-tangles and the π-tangle always survives for any choice of acceleration and the degree of initial entanglement. For scalar field, the one-tangle of accelerated observer depends on the choice of values of probability amplitudes and it vanishes in the range of infinite acceleration, whereas for π-tangle this is not always true. The dependence of π-tangle on probability amplitudes varies with acceleration. In the lower range of acceleration, its behavior changes by switching between the values of probability amplitudes and for larger values of acceleration this dependence on probability amplitudes vanishes. Interestingly, unlike bipartite entanglement, the degradation of π-tangle against acceleration in the case of scalar fields is slower than for Dirac fields. (general)
Leading quantum gravitational corrections to scalar QED
International Nuclear Information System (INIS)
Bjerrum-Bohr, N.E.J.
2002-01-01
We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged scalars in the combined theory of general relativity and scalar QED. The combined theory is treated as an effective field theory. This allows for a consistent quantization of the gravitational field. The appropriate vertex rules are extracted from the action, and the non-analytic contributions to the 1-loop scattering matrix are calculated in the non-relativistic limit. The non-analytical parts of the scattering amplitude, which are known to give the long range, low energy, leading quantum corrections, are used to construct the leading post-Newtonian and quantum corrections to the two-particle non-relativistic scattering matrix potential for two charged scalars. The result is discussed in relation to experimental verifications
International Nuclear Information System (INIS)
Haouat, S.; Chekireb, R.
2012-01-01
The influence of electromagnetic fields on the creation of scalar particles from vacuum in a flat Robertson-Walker space-time is studied. The Klein-Gordon equation with varying electric field and constant magnetic one is solved. The Bogoliubov transformation method is applied to calculate the pair creation probability and the number density of created particles. It is shown that the electric field amplifies the creation of scalar particles while the magnetic field minimizes it. (orig.)
Zero mass field quantization and Kibble's long-range force criterion for the Goldstone theorem
International Nuclear Information System (INIS)
Wright, S.H.
1981-01-01
The central theme of the dissertation is an investigation of the long-range force criterion used by Kibble in his discussion of the Goldstone Theorem. This investigation is broken up into the following sections: I. Introduction. Spontaneous symmetry breaking, the Goldstone Theorem and the conditions under which it holds are discussed. II. Massless Wave Expansions. In order to make explicit calculations of the operator commutators used in applying Kibble's criterion, it is necessary to work out the operator expansions for a massless field. Unusual results are obtained which include operators corresponding to classical macroscopic field modes. III. The Kibble Criterion for Simple Models Exhibiting Spontaneously Broken Symmetries. The results of the previous section are applied to simple models with spontaneously broken symmetries, namely, the real scalar massless field and the Goldstone model without gauge coupling. IV. The Higgs Mechanism in Classical Field Theory. It is shown that the Higgs Mechanism has a simple interpretation in terms of classical field theory, namely, that it arises from a derivative coupling term between the Goldstone fields and the gauge fields. V. The Higgs Mechanism and Kibble's Criterion. This section draws together the material discussed in sections II to IV. Explicit calculations are made to evaluate Kibble's criterion on a Goldstone-Higgs type of model in the Coulomb gauge. It is found, as expected, that the criterion is not met, but not for reasons relating to the range of the mediating force. By referring to the findings of sections III and IV, it is concluded that the common denominator underlying both the Higgs Mechanism and the failure of Kibble's criterion is a structural aspect of the field equations: derivative coupling between fields
Stochastic quantization of instantons
International Nuclear Information System (INIS)
Grandati, Y.; Berard, A.; Grange, P.
1996-01-01
The method of Parisi and Wu to quantize classical fields is applied to instanton solutions var-phi I of euclidian non-linear theory in one dimension. The solution var-phi var-epsilon of the corresponding Langevin equation is built through a singular perturbative expansion in var-epsilon=h 1/2 in the frame of the center of the mass of the instanton, where the difference var-phi var-epsilon -var-phi I carries only fluctuations of the instanton form. The relevance of the method is shown for the stochastic K dV equation with uniform noise in space: the exact solution usually obtained by the inverse scattering method is retrieved easily by the singular expansion. A general diagrammatic representation of the solution is then established which makes a thorough use of regrouping properties of stochastic diagrams derived in scalar field theory. Averaging over the noise and in the limit of infinite stochastic time, the authors obtain explicit expressions for the first two orders in var-epsilon of the pertrubed instanton of its Green function. Specializing to the Sine-Gordon and var-phi 4 models, the first anaharmonic correction is obtained analytically. The calculation is carried to second order for the var-phi 4 model, showing good convergence. 21 refs., 5 fig
Thermal effects in quantized fields in the example of the Gross-Neveu model
International Nuclear Information System (INIS)
Englert, B.G.
1981-01-01
The Gross-Nerau model is applied to discuss thermal effects in quantized fields in an exemplary way. For this the effective potential for arbitrary temperature is calculated in one-loop approximation, i.e. in lowest order of the 1/N-expansion. It is proved to be convenient to regulate the model dimensionally and to renormalize by subtraction in the momentum dimensionally and to renormalize by subtraction in the momentum space. From the effective potential the temperature dependence of the fermion mass generated by dynamical symmetry breaking is obtained. This result can be reproduced by a manifestly selfconsistent calculation which leads in a natural way to the tadpole equation. The calculation of temperature dependent elastic scattering cross sections rounds the one-loop calculations of and gives hints, in which direction the experimental search for thermal effects could possible be successful. Furthermore the tadpole equation is evaluation in two-loop approximation. Thereby it is shown that only a self-consistent renormalization yields evaluable results while in a perturbative renormalization the dimensional transmutation cannot be performed. Indeed no real improvements of the one-loop results are obtained which is due to the fact that not all contributions of the next 1/N-order are taken into account. (orig.) [de
Metric-affine formalism of higher derivative scalar fields in cosmology
International Nuclear Information System (INIS)
Li, Mingzhe; Wang, Xiulian
2012-01-01
Higher derivative scalar field theories have received considerable attention for the potentially explanations of the initial state of the universe or the current cosmic acceleration which they might offer. They have also attracted many interests in the phenomenological studies of infrared modifications of gravity. These theories are mostly studied by the metric variational approach in which only the metric is the fundamental field to account for the gravitation. In this paper we study the higher derivative scalar fields with the metric-affine formalism where the affine connection is treated arbitrarily at the beginning. Because the higher derivative scalar fields couple to the connection directly in a covariant theory these two formalisms will lead to different results. These differences are suppressed by the powers of the Planck mass and are usually expected to have small effects. But in some cases they may cause non-negligible deviations. We show by a higher derivative dark energy model that the two formalisms lead to significantly different pictures of the future universe
Decoherence and disentanglement of qubits detecting scalar fields in an expanded spacetime
Energy Technology Data Exchange (ETDEWEB)
Li, Yujie; Dai, Yue [Fudan University, Department of Physics and State Key Laboratory of Surface Physics, Shanghai (China); Shi, Yu [Fudan University, Department of Physics and State Key Laboratory of Surface Physics, Shanghai (China); Fudan University, Collaborative Innovation Center of Advanced Microstructures, Shanghai (China)
2017-09-15
We consider Unruh-Wald qubit detector model adopted for the far future region of an exactly solvable 1 + 1 dimensional scalar field theory in a toy model of Robertson-Walker expanding spacetime. It is shown that the expansion of the spacetime in its history enhances the decoherence of the qubit coupled with a scalar field. Moreover, we consider two entangled qubits, each locally coupled with a scalar field. The expansion of the spacetime in its history degrades the entanglement between the qubits, and it can lead to entanglement's sudden death if the initial entanglement is small enough. The details depend on the parameters characterizing the expansion of the spacetime. This work, on a toy model, suggests that the history of the spacetime might be probed through the coherent and entanglement behavior of the future detectors of quantum fields. In the present toy model, the two cosmological parameters can be determined from the quantum informational quantities of the detectors. (orig.)
Scalar field propagation in the ϕ 4 κ-Minkowski model
Meljanac, S.; Samsarov, A.; Trampetić, J.; Wohlgenannt, M.
2011-12-01
In this article we use the noncommutative (NC) κ-Minkowski ϕ 4 model based on the κ-deformed star product, (★ h ). The action is modified by expanding up to linear order in the κ-deformation parameter a, producing an effective model on commutative spacetime. For the computation of the tadpole diagram contributions to the scalar field propagation/self-energy, we anticipate that statistics on the κ-Minkowski is specifically κ-deformed. Thus our prescription in fact represents hybrid approach between standard quantum field theory (QFT) and NCQFT on the κ-deformed Minkowski spacetime, resulting in a κ-effective model. The propagation is analyzed in the framework of the two-point Green's function for low, intermediate, and for the Planckian propagation energies, respectively. Semiclassical/hybrid behavior of the first order quantum correction do show up due to the κ-deformed momentum conservation law. For low energies, the dependence of the tadpole contribution on the deformation parameter a drops out completely, while for Planckian energies, it tends to a fixed finite value. The mass term of the scalar field is shifted and these shifts are very different at different propagation energies. At the Planck-ian energies we obtain the direction dependent κ-modified dispersion relations. Thus our κ-effective model for the massive scalar field shows a birefringence effect.
Distributed Sensor Fusion for Scalar Field Mapping Using Mobile Sensor Networks.
La, Hung Manh; Sheng, Weihua
2013-04-01
In this paper, autonomous mobile sensor networks are deployed to measure a scalar field and build its map. We develop a novel method for multiple mobile sensor nodes to build this map using noisy sensor measurements. Our method consists of two parts. First, we develop a distributed sensor fusion algorithm by integrating two different distributed consensus filters to achieve cooperative sensing among sensor nodes. This fusion algorithm has two phases. In the first phase, the weighted average consensus filter is developed, which allows each sensor node to find an estimate of the value of the scalar field at each time step. In the second phase, the average consensus filter is used to allow each sensor node to find a confidence of the estimate at each time step. The final estimate of the value of the scalar field is iteratively updated during the movement of the mobile sensors via weighted average. Second, we develop the distributed flocking-control algorithm to drive the mobile sensors to form a network and track the virtual leader moving along the field when only a small subset of the mobile sensors know the information of the leader. Experimental results are provided to demonstrate our proposed algorithms.
Generalized second law of thermodynamics for non-canonical scalar field model with corrected-entropy
International Nuclear Information System (INIS)
Das, Sudipta; Mamon, Abdulla Al; Debnath, Ujjal
2015-01-01
In this work, we have considered a non-canonical scalar field dark energy model in the framework of flat FRW background. It has also been assumed that the dark matter sector interacts with the non-canonical dark energy sector through some interaction term. Using the solutions for this interacting non-canonical scalar field dark energy model, we have investigated the validity of generalized second law (GSL) of thermodynamics in various scenarios using first law and area law of thermodynamics. For this purpose, we have assumed two types of horizons viz apparent horizon and event horizon for the universe and using first law of thermodynamics, we have examined the validity of GSL on both apparent and event horizons. Next, we have considered two types of entropy-corrections on apparent and event horizons. Using the modified area law, we have examined the validity of GSL of thermodynamics on apparent and event horizons under some restrictions of model parameters. (orig.)
Thermodynamics of de Sitter black holes with a conformally coupled scalar field
International Nuclear Information System (INIS)
Barlow, Anne-Marie; Doherty, Daniel; Winstanley, Elizabeth
2005-01-01
We study the thermodynamics of de Sitter black holes with a conformally coupled scalar field. The geometry is that of the lukewarm Reissner-Nordstroem-de Sitter black holes, with the event and cosmological horizons at the same temperature. This means that the region between the event and cosmological horizons can form a regular Euclidean instanton. The entropy is modified by the nonminimal coupling of the scalar field to the geometry, but can still be derived from the Euclidean action, provided suitable modifications are made to deal with the electrically charged case. We use the first law as derived from the isolated horizons formalism to compute the local horizon energies for the event and cosmological horizons
Future evolution in a backreaction model and the analogous scalar field cosmology
Energy Technology Data Exchange (ETDEWEB)
Ali, Amna; Majumdar, A.S., E-mail: amnaalig@gmail.com, E-mail: archan@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector-III, Salt Lake, Kolkata 700106 (India)
2017-01-01
We investigate the future evolution of the universe using the Buchert framework for averaged backreaction in the context of a two-domain partition of the universe. We show that this approach allows for the possibility of the global acceleration vanishing at a finite future time, provided that none of the subdomains accelerate individually. The model at large scales is analogously described in terms of a homogeneous scalar field emerging with a potential that is fixed and free from phenomenological parametrization. The dynamics of this scalar field is explored in the analogous FLRW cosmology. We use observational data from Type Ia Supernovae, Baryon Acoustic Oscillations, and Cosmic Microwave Background to constrain the parameters of the model for a viable cosmology, providing the corresponding likelihood contours.
Vacuum Expectation Value Profiles of the Bulk Scalar Field in the Generalized Randall-Sundrum Model
International Nuclear Information System (INIS)
Moazzen, M.; Tofighi, A.; Farokhtabar, A.
2015-01-01
In the generalized Randall-Sundrum warped brane-world model the cosmological constant induced on the visible brane can be positive or negative. In this paper we investigate profiles of vacuum expectation value of the bulk scalar field under general Dirichlet and Neumann boundary conditions in the generalized warped brane-world model. We show that the VEV profiles generally depend on the value of the brane cosmological constant. We find that the VEV profiles of the bulk scalar field for a visible brane with negative cosmological constant and positive tension are quite distinct from those of Randall-Sundrum model. In addition we show that the VEV profiles for a visible brane with large positive cosmological constant are also different from those of the Randall-Sundrum model. We also verify that Goldberger and Wise mechanism can work under nonzero Dirichlet boundary conditions in the generalized Randall-Sundrum model.
International Nuclear Information System (INIS)
Poghossian, R.H.
2000-01-01
In an angular quantization approach a perturbation theory for the Massive Thirring Model (MTM) is developed, which allows us to calculate vacuum expectation values of exponential fields in sine-Gordon theory near the free fermion point in first order of the MTM coupling constant g. The Hankel transforms play an important role when carrying out these calculations. The expression we have found coincides with that of the direct expansion over g of the exact formula conjectured by Lukyanov and Zamolodchikov
The phase diagram of scalar field theory on the fuzzy disc
Energy Technology Data Exchange (ETDEWEB)
Rea, Simone; Sämann, Christian [Maxwell Institute for Mathematical Sciences, Department of Mathematics,Heriot-Watt University,Colin Maclaurin Building, Riccarton, Edinburgh EH14 4AS (United Kingdom)
2015-11-17
Using a recently developed bootstrapping method, we compute the phase diagram of scalar field theory on the fuzzy disc with quartic even potential. We find three distinct phases with second and third order phase transitions between them. In particular, we find that the second order phase transition happens approximately at a fixed ratio of the two coupling constants defining the potential. We compute this ratio analytically in the limit of large coupling constants. Our results qualitatively agree with previously obtained numerical results.
LATTICEEASY A Program for Lattice Simulations of Scalar Fields in an Expanding Universe
Felder, G; Tkachev, Igor; Felder, Gary
2008-01-01
We describe a C++ program that we have written and made available for calculating the evolution of interacting scalar fields in an expanding universe. The program is particularly useful for the study of reheating and thermalization after inflation. The program and its full documentation are available on the Web at http://physics.stanford.edu/gfelder/latticeeasy. In this paper we provide a brief overview of what the program does and what it is useful for.
Alternative integral equations and perturbation expansions for self-coupled scalar fields
International Nuclear Information System (INIS)
Ford, L.H.
1985-01-01
It is shown that the theory of a self-coupled scalar field may be expressed in terms of a class of integral equations which include the Yang-Feldman equation as a particular case. Other integral equations in this class could be used to generate alternative perturbation expansions which contain a nonanalytic dependence upon the coupling constant and are less ultraviolet divergent than the conventional perturbation expansion. (orig.)
Resonant frequencies of massless scalar field in rotating black-brane spacetime
Institute of Scientific and Technical Information of China (English)
Jing Ji-Liang; Pan Qi-Yuan
2008-01-01
This paper investigates the resonant frequencies of the massless scalar field in the near extremal Kerr-like black-brahe spacetime. It is shown that the different angular quantum number will present different resonant frequencies. It is also shown that the real part of the resonant frequencies increases as the compact dimensions parameter μi increases, but the magnitude of the imaginary part decreases as μi increases.
Isosurface Display of 3-D Scalar Fields from a Meteorological Model on Google Earth
2013-07-01
facets to four, we have chosen to adopt and implement a revised method discussed and made available by Bourke (1994), which can accommodate up to...five facets for a given grid cube. While the published code from Bourke (1994) is in the public domain, it was originally implemented in the C...and atmospheric temperatures. 17 4. References Bourke , P. Polygonising a Scalar Field. http://paulbourke.net/geometry/polygonise
Scalar field propagation in the phi^4 kappa-Minkowski model
Meljanac, S.; Samsarov, A.; Trampetic, J.; Wohlgenannt, M.
2011-01-01
In this article we use the noncommutative (NC) kappa-Minkowski phi^4 model based on the kappa-deformed star product, ({*}_h). The action is modified by expanding up to linear order in the kappa-deformation parameter a, producing an effective model on commutative spacetime. For the computation of the tadpole diagram contributions to the scalar field propagation/self-energy, we anticipate that statistics on the kappa-Minkowski is specifically kappa-deformed. Thus our prescription in fact repres...
International Nuclear Information System (INIS)
Gibson, C.H.
1991-01-01
Kolmogorov's three universal similarity hypotheses are extrapolated to describe scalar fields like temperature mixed by turbulence. The analogous first and second hypotheses for scalars include the effects of Prandtl number and rate-of-strain mixing. Application of velocity and scalar similarity hypotheses to the ocean must take into account the damping of active turbulence by density stratification and the Earth's rotation to form fossil turbulence. By the analogous Kolmogorov third hypothesis for scalars, temperature dissipation rates χ averaged over lengths r > L K should be lognormally distributed with intermittency factors σ 2 that increase with increasing turbulence energy length scales L O as σ ln r 2 approx = μ θ ln(L O /r). Tests of kolmogorovian velocity and scalar universal similarity hypotheses for very large ranges of turbulence length and timescales are provided by data from the ocean and the galactic interstellar medium. These ranges are from 1 to 9 decades in the ocean, and over 12 decades in the interstellar medium. The universal constant for turbulent mixing intermittency μ θ is estimated from oceanic data to be 0.44±0.01, which is remarkably close to estimates for Kolmorgorov's turbulence intermittency constant μ of 0.45±0.05 from galactic as well as atmospheric data. Extreme intermittency complicates the oceanic sampling problem, and may lead to quantitative and qualitative undersampling errors in estimates of mean oceanic dissipation rates and fluxes. Intermittency of turbulence and mixing in the interstellar medium may be a factor in the formation of stars. (author)
Constraints on Interacting Scalars in 2T Field Theory and No Scale Models in 1T Field Theory
Bars, Itzhak
2010-01-01
In this paper I determine the general form of the physical and mathematical restrictions that arise on the interactions of gravity and scalar fields in the 2T field theory setting, in d+2 dimensions, as well as in the emerging shadows in d dimensions. These constraints on scalar fields follow from an underlying Sp(2,R) gauge symmetry in phase space. Determining these general constraints provides a basis for the construction of 2T supergravity, as well as physical applications in 1T-field theory, that are discussed briefly here, and more detail elsewhere. In particular, no scale models that lead to a vanishing cosmological constant at the classical level emerge naturally in this setting.
Evolution of perturbations in distinct classes of canonical scalar field models of dark energy
International Nuclear Information System (INIS)
Jassal, H. K.
2010-01-01
Dark energy must cluster in order to be consistent with the equivalence principle. The background evolution can be effectively modeled by either a scalar field or by a barotropic fluid. The fluid model can be used to emulate perturbations in a scalar field model of dark energy, though this model breaks down at large scales. In this paper we study evolution of dark energy perturbations in canonical scalar field models: the classes of thawing and freezing models. The dark energy equation of state evolves differently in these classes. In freezing models, the equation of state deviates from that of a cosmological constant at early times. For thawing models, the dark energy equation of state remains near that of the cosmological constant at early times and begins to deviate from it only at late times. Since the dark energy equation of state evolves differently in these classes, the dark energy perturbations too evolve differently. In freezing models, since the equation of state deviates from that of a cosmological constant at early times, there is a significant difference in evolution of matter perturbations from those in the cosmological constant model. In comparison, matter perturbations in thawing models differ from the cosmological constant only at late times. This difference provides an additional handle to distinguish between these classes of models and this difference should manifest itself in the integrated Sachs-Wolfe effect.
Detailed balance condition and ultraviolet stability of scalar field in Horava-Lifshitz gravity
International Nuclear Information System (INIS)
Borzou, Ahmad; Lin, Kai; Wang, Anzhong
2011-01-01
Detailed balance and projectability conditions are two main assumptions when Horava recently formulated his theory of quantum gravity - the Horava-Lifshitz (HL) theory. While the latter represents an important ingredient, the former often believed needs to be abandoned, in order to obtain an ultraviolet stable scalar field, among other things. In this paper, because of several attractive features of this condition, we revisit it, and show that the scalar field can be stabilized, if the detailed balance condition is allowed to be softly broken. Although this is done explicitly in the non-relativistic general covariant setup of Horava-Melby-Thompson with an arbitrary coupling constant λ, generalized lately by da Silva, it is also true in other versions of the HL theory. With the detailed balance condition softly breaking, the number of independent coupling constants can be still significantly reduced. It is remarkable to note that, unlike other setups, in this da Silva generalization, there exists a master equation for the linear perturbations of the scalar field in the flat Friedmann-Robertson-Walker background
Closed star product on noncommutative ℝ{sup 3} and scalar field dynamics
Energy Technology Data Exchange (ETDEWEB)
Jurić, Tajron [Ruđer Bošković Institute, Theoretical Physics Division,Bijenička c. 54, HR-10002 Zagreb (Croatia); Poulain, Timothé; Wallet, Jean-Christophe [Laboratoire de Physique Théorique, CNRS,University of Paris-Sud, University of Paris-Saclay,Bât. 210, 91405 Orsay (France)
2016-05-25
We consider the noncommutative space ℝ{sub θ}{sup 3}, a deformation of ℝ{sup 3} for which the star product is closed for the trace functional. We study one-loop IR and UV properties of the 2-point function for real and complex noncommutative scalar field theories with quartic interactions and Laplacian on ℝ{sup 3} as kinetic operator. We find that the 2-point functions for these noncommutative scalar field theories have no IR singularities in the external momenta, indicating the absence of UV/IR mixing. We also find that the 2-point functions are UV finite with the deformation parameter θ playing the role of a natural UV cut-off. The possible origin of the absence of UV/IR mixing in noncommutative scalar field theories on ℝ{sub θ}{sup 3} as well as on ℝ{sub λ}{sup 3}, another deformation of ℝ{sup 3}, is discussed.
Background field quantization in non-covariant gauges: Renormalization and WTST identities
International Nuclear Information System (INIS)
McKeon, G.; Phillips, S.B.; Samant, S.S.; Sherry, T.N.
1986-01-01
Background field quantization of pure YM theories in non-covariant gauges is treated with particular emphasis on renormalization. Gauge fixing terms of the form (1/2α)n . Qsup(a)fsup(ab)n . Qsup(b) are considered where fsup(ab) can assume the forms fsup(ab)sub((i))=-deltasup(ab) (the axial gauge), fsup(ab)sub((ii))=(n . D(A))sup(2ab)/n 4 and fsup(ab)sub((iii))=D 2 (A)sup(ab)/n 2 (the planar gauge). For the cases where fsup(ab) depends explicitly on the background field Asub(μ)sup(a) the ghost sector is enlarged by the addition of appropriate Nielson-Kallosh ghost fields. The BRS identities for these gauge choices are derived and solved. The quantum-corrected versions of both the bare background field gauge transformations and the bare quantum field gauge transformations are obtained from the BRS analysis. It is also shown that, to one loop, all the counter terms are determined by the background field independent part of the theory and this result is used, in cases (ii) and (iii), to derive all the counter terms and to show that Kallosh's theorem is verified. The result is also used to demonstrate the pathological nature of case (i) for αnot=0, in particular the result that Kallosh's theorem is not applicable. The result that the generating functional of Green functions is independent of the background field Asub(μ)sup(a) in the absence of all external sources is generalized to the case of non-covariant gauges. The equality established by Abbott between the 1PI generating functionals GAMMA tilde[A,0] and GAMMAsub(c)[anti Q; A] sub(anti Q=A), where GAMMAsub(c) is a conventional generating functional in an A-dependent gauge, is analysed. We show that the WTST identities satisfied by GAMMAsub(c) reduce, when anti Q is set equal to A, to the naive Ward-identity satisfied by GAMMA tilde[A,0]. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Yokoyama, Kan-ichi; Kubo, Reijiro
1974-12-01
The framework of the Nakanishi-Lautrup formalism should be enlarged by introducing a scalar dipole ghost field B(x), which is called gauge on field, together with its pair field. By taking free Lagrangian density, Free-field equations can be described. The vacuum is defined by using a neutral vector field U..mu..(x). The state-vector space is generated by the adjoining conjugates of U..mu..sup((+))(x), and auxiliary fields B(x), B/sub 1/(x) and B/sub 2/(x), which were introduced in the form of the Lagrangian density. The physical states can be defined by the supplementary conditions of the form B/sub 1/sup((+))(x) 1 phys>=B/sub 2/sup((+))(x) 1 phys>=0. It is seen that all the field equations and all the commutators are kept form-invariant, and that the gauge parameter ..cap alpha.. is transformed into ..cap alpha..' given by ..cap alpha..'=..cap alpha..+lambda, with epsilon unchanged. The Lagrangian density is specified only by the gauge invariant parameter epsilon. The gauge structure of theory has universal meaning over whole Abelian-gauge field. C-number gauge transformation and the gauge structure in the presence of interaction are also discussed.
International Nuclear Information System (INIS)
Rodionov, V.N.; Studenikin, A.I.
1985-01-01
Consideration of processes with the assistance of virtual and real Higgs scalar neutral σ-bosons in the presence of a constant external crossed electromagnetic field is conducted. In the second order of the perturbation theory in the Weinberg-Jalam model corresponding contribution into mass lepton operator in this base probability dependence of σ-boson emission and radiation field σ-bosn effects on the crossed field parameter is investigated: x=√(eFsub(μν)psup(ν)sup(2)/msup(3)
International Nuclear Information System (INIS)
Finelli, Fabio; Paci, Francesco; Paoletti, Daniela
2008-01-01
We study the impact of a stochastic background of primordial magnetic fields on the scalar contribution of cosmic microwave background (CMB) anisotropies and on the matter power spectrum. We give the correct initial conditions for cosmological perturbations and the exact expressions for the energy density and Lorentz force associated to the stochastic background of primordial magnetic fields, given a power-law for their spectra cut at a damping scale. The dependence of the CMB temperature and polarization spectra on the relevant parameters of the primordial magnetic fields is illustrated.
Energy Technology Data Exchange (ETDEWEB)
Zhuk, Alexander [The International Center of Future Science of the Jilin University, Changchun City (China); Odessa National University, Astronomical Observatory, Odessa (Ukraine); Chopovsky, Alexey; Fakhr, Seyed Hossein [Odessa National University, Astronomical Observatory, Odessa (Ukraine); Shulga, Valerii [The International Center of Future Science of the Jilin University, Changchun City (China); Institut of Radio Astronomy of National Academy of Sciences of Ukraine, Kharkov (Ukraine); Wei, Han [The International Center of Future Science of the Jilin University, Changchun City (China)
2017-11-15
In a multidimensional Kaluza-Klein model with Ricci-flat internal space, we study the gravitational field in the weak-field limit. This field is created by two coupled sources. First, this is a point-like massive body which has a dust-like equation of state in the external space and an arbitrary parameter Ω of equation of state in the internal space. The second source is a static spherically symmetric massive scalar field centered at the origin where the point-like massive body is. The found perturbed metric coefficients are used to calculate the parameterized post-Newtonian (PPN) parameter γ. We define under which conditions γ can be very close to unity in accordance with the relativistic gravitational tests in the solar system. This can take place for both massive or massless scalar fields. For example, to have γ ∼ 1 in the solar system, the mass of scalar field should be μ >or similar 5.05 x 10{sup -49} g ∝ 2.83 x 10{sup -16} eV. In all cases, we arrive at the same conclusion that to be in agreement with the relativistic gravitational tests, the gravitating mass should have tension: Ω = -1/2. (orig.)
A search for neutral Higgs bosons in the MSSM and models with two scalar field doublets
Ackerstaff, K.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Bartoldus, R.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bird, S.D.; Blobel, V.; Bloodworth, I.J.; Bobinski, M.; Bock, P.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Burgard, C.; Burgin, R.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Clarke, P.E.L.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallapiccola, C.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; del Pozo, L.A.; de Roeck, A.; Desch, K.; Dienes, B.; Dixit, M.S.; Doucet, M.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Eatough, D.; Estabrooks, P.G.; Etzion, E.; Evans, H.G.; Evans, M.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Feld, L.; Fiedler, F.; Fierro, M.; Fischer, H.M.; Fleck, I.; Folman, R.; Fong, D.G.; Foucher, M.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Geddes, N.I.; Geich-Gimbel, C.; Geralis, T.; Giacomelli, G.; Giacomelli, P.; Giacomelli, R.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Goodrick, M.J.; Gorn, W.; Grandi, C.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Hargrove, C.K.; Hart, P.A.; Hartmann, C.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hillier, S.J.; Hobson, P.R.; Hocker, James Andrew; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Hutchcroft, D.E.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jawahery, A.; Jeffreys, P.W.; Jeremie, H.; Jimack, M.; Joly, A.; Jones, C.R.; Jones, M.; Jost, U.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kirk, J.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D.S.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kyberd, P.; Lafferty, G.D.; Lahmann, R.; Lai, W.P.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lazic, D.; Lee, A.M.; Lefebvre, E.; Lellouch, D.; Letts, J.; Levinson, L.; List, B.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Markus, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mincer, A.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nellen, B.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oh, A.; Oldershaw, N.J.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Posthaus, A.; Rembser, C.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rooke, A.; Rossi, A.M.; Routenburg, P.; Rozen, Y.; Runge, K.; Runolfsson, O.; Ruppel, U.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharf, F.; Scharff-Hansen, P.; Schieck, J.; Schleper, P.; Schmitt, B.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skillman, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Springer, Robert Wayne; Sproston, M.; Stephens, K.; Steuerer, J.; Stockhausen, B.; Stoll, K.; Strom, David M.; Strohmer, R.; Szymanski, P.; Tafirout, R.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomson, M.A.; von Torne, E.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Utzat, P.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Vikas, P.; Vokurka, E.H.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.
1998-01-01
A search is described for the neutral Higgs bosons h^0 and A^0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z^0 h^0 and h^0 A^0 production channels is based on data corresponding to an integrated luminosity of 25 pb^{-1} from e^+e^- collisions at centre-of-mass energies between 130 and 172GeV collected with the OPAL detector at LEP. The observation of a number of candidates consistent with Standard Model background expectations is used in combination with earlier results from data collected at the Z^0 resonance to set limits on m_h and m_A in general models with two scalar field doublets and in the MSSM. For example, in the MSSM, for tan(beta) > 1, minimal and maximal scalar top quark mixing and soft SUSY-breaking masses of 1 TeV, the 95% confidence level limits m_h > 59.0 GeV and m_A > 59.5 GeV are obtained. For the first time, the MSSM parameter space is explored in a detailed scan.
Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets
Pouransari, Z.; Biferale, L.; Johansson, A. V.
2015-02-01
The concept of local isotropy in a chemically reacting turbulent wall-jet flow is addressed using direct numerical simulation (DNS) data. Different DNS databases with isothermal and exothermic reactions are examined. The chemical reaction and heat release effects on the turbulent velocity, passive scalar, and reactive species fields are studied using their probability density functions (PDFs) and higher order moments for velocities and scalar fields, as well as their gradients. With the aid of the anisotropy invariant maps for the Reynolds stress tensor, the heat release effects on the anisotropy level at different wall-normal locations are evaluated and found to be most accentuated in the near-wall region. It is observed that the small-scale anisotropies are persistent both in the near-wall region and inside the jet flame. Two exothermic cases with different Damköhler numbers are examined and the comparison revealed that the Damköhler number effects are most dominant in the near-wall region, where the wall cooling effects are influential. In addition, with the aid of PDFs conditioned on the mixture fraction, the significance of the reactive scalar characteristics in the reaction zone is illustrated. We argue that the combined effects of strong intermittency and strong persistency of anisotropy at the small scales in the entire domain can affect mixing and ultimately the combustion characteristics of the reacting flow.
Nuclear matter in relativistic mean field theory with isovector scalar meson.
Energy Technology Data Exchange (ETDEWEB)
Kubis, S.; Kutschera, M. [Institute of Nuclear Physics, Cracow (Poland)
1996-12-01
Relativistic mean field (RMF) theory of nuclear matter with the isovector scalar mean field corresponding to the {delta}-meson [a{sub 0}(980)] is studied. While the {delta}-meson field vanishes in symmetric nuclear matter, it can influence properties of asymmetric nuclear matter in neutron stars. The RMF contribution due to {delta}-field to the nuclear symmetry energy is negative. To fit the empirical value, E{sub s}{approx}30 MeV, a stronger {rho}-meson coupling is required than in absence of the {delta}-field. The energy per particle of neutron star matter is than larger at high densities than the one with no {delta}-field included. Also, the proton fraction of {beta}-stable matter increases. Splitting of proton and neutron effective masses due to the {delta}-field can affect transport properties of neutron star matter. (author). 4 refs, 6 figs.
Nuclear matter in relativistic mean field theory with isovector scalar meson
International Nuclear Information System (INIS)
Kubis, S.; Kutschera, M.
1996-12-01
Relativistic mean field (RMF) theory of nuclear matter with the isovector scalar mean field corresponding to the δ-meson [a 0 (980)] is studied. While the δ-meson field vanishes in symmetric nuclear matter, it can influence properties of asymmetric nuclear matter in neutron stars. The RMF contribution due to δ-field to the nuclear symmetry energy is negative. To fit the empirical value, E s ∼30 MeV, a stronger ρ-meson coupling is required than in absence of the δ-field. The energy per particle of neutron star matter is than larger at high densities than the one with no δ-field included. Also, the proton fraction of β-stable matter increases. Splitting of proton and neutron effective masses due to the δ-field can affect transport properties of neutron star matter. (author). 4 refs, 6 figs
JDiffraction: A GPGPU-accelerated JAVA library for numerical propagation of scalar wave fields
Piedrahita-Quintero, Pablo; Trujillo, Carlos; Garcia-Sucerquia, Jorge
2017-05-01
JDiffraction, a GPGPU-accelerated JAVA library for numerical propagation of scalar wave fields, is presented. Angular spectrum, Fresnel transform, and Fresnel-Bluestein transform are the numerical algorithms implemented in the methods and functions of the library to compute the scalar propagation of the complex wavefield. The functionality of the library is tested with the modeling of easy to forecast numerical experiments and also with the numerical reconstruction of a digitally recorded hologram. The performance of JDiffraction is contrasted with a library written for C++, showing great competitiveness in the apparently less complex environment of JAVA language. JDiffraction also includes JAVA easy-to-use methods and functions that take advantage of the computation power of the graphic processing units to accelerate the processing times of 2048×2048 pixel images up to 74 frames per second.
Primordial black holes from scalar field evolution in the early universe
Cotner, Eric; Kusenko, Alexander
2017-11-01
Scalar condensates with large expectation values can form in the early universe, for example, in theories with supersymmetry. The condensate can undergo fragmentation into Q-balls before decaying. If the Q-balls dominate the energy density for some period of time, statistical fluctuations in their number density can lead to formation of primordial black holes (PBH). In the case of supersymmetry the mass range is limited from above by 1 023 g . For a general charged scalar field, this robust mechanism can generate black holes over a much broader mass range, including the black holes with masses of 1-100 solar masses, which is relevant for LIGO observations of gravitational waves. Topological defects can lead to formation of PBH in a similar fashion.
On the zero mode problem of the light-cone quantization
International Nuclear Information System (INIS)
Huang, Suzhou; Lin, Wei
1993-01-01
The light-cone quantization for theories involving arbitrarily interacting scalars is studied systematically. The zero mode, which plays a special role in the light-cone quantization, is treated explicitly. The arguments utilize a lattice regularization and the constrained path-integral method. It is shown, to all orders in coupling constants or the loop expansion, that the ghost fields, introduced to enforce the constraints, decouple from all the virtual processes in the infinite-volume limit. The only possibility for the light-cone quantization to deviate from the equal-time quantization is when the interaction is such that the bosonic ghost fields develop expectation values and consequently alter the location of the minimum point of the effective potential. 24 refs
Some stochastic techniques in quantization, new developments in Markov fields and quantum fields
International Nuclear Information System (INIS)
Albeverio, S.; Zegarlinski, B.
1990-01-01
In these lectures we intend to discuss a few recent developments in the area of interactions between quantum fields and Markow fields in which we have been involved. We stress particularly developments involving techniques of stochastic analysis and where mathematical results have been obtained. In sections 1 and 2 we discuss recent developments in the study and applications of the theory of Dirichlet forms in its relations with quantum mechanics and quantum field theory. In our opinion, this theory provides a natural setting for the study of the singular stochastic processes associated with quantum theory. In section 3 we discuss a recent rigorous construction of a convergent simplicial approximation to quantum fields. We look upon these developments as a first step towards a mathematical realization, at least in 2 space-time dimensions, of a convergent 'Regge-calculus', and as first steps to the mathematical control of more general models (like e.g. models involving actions of Chern-Simons type) in the continuum. In Sect. 4 we discuss applications of some stochastic techniques to the study of gauge fields and Higgs fields, mainly in 2 space time dimensions and certain non linear electromagnetic-type fields in 4-space-time dimensions. (orig./HSI)
Charged Compact Boson Stars in a Theory of Massless Scalar Field
Kumar, Sanjeev
2018-05-01
In this work we present some new results obtained in a study of the phase diagram of charged compact boson stars in a theory involving a complex scalar field with a conical potential coupled to a U(1) gauge field and gravity. We obtain new bifurcation points in this model. We present a detailed discussion of the various regions of the phase diagram with respect to the bifurcation points. The theory is seen to contain rich physics in a particular domain of the phase diagram.
Development of Techniques for Visualization of Scalar and Vector Fields in the Immersive Environment
Bidasaria, Hari B.; Wilson, John W.; Nealy, John E.
2005-01-01
Visualization of scalar and vector fields in the immersive environment (CAVE - Cave Automated Virtual Environment) is important for its application to radiation shielding research at NASA Langley Research Center. A complete methodology and the underlying software for this purpose have been developed. The developed software has been put to use for the visualization of the earth s magnetic field, and in particular for the study of the South Atlantic Anomaly. The methodology has also been put to use for the visualization of geomagnetically trapped protons and electrons within Earth's magnetosphere.
Virtual particle-antiparticle pair formation by a scalar particle bound in an external Coulomb field
International Nuclear Information System (INIS)
Darewych, J.W.; Horbatsch, M.; Lev, B.I.; Shapoval, D.V.
1995-01-01
A Hamiltonian variational Fock-space method is used to describe scalar massive particles in an external Coulomb field with strength f=Zα. The use of an ansatz that includes a three-particle state in addition to a single-particle state built on the field-free vacuum enables one to highlight the role played by particle-antiparticle pair formation. Comparison is made with the Klein-Gordon equation in the Feshbach-Villars representation and it is shown explicitly how the virtual pair contribution corrects an O(f 5 ) deficiency present in the energy spectrum of the naive Schroedinger-type single-particle equation. ((orig.))
Classical and quantum Big Brake cosmology for scalar field and tachyonic models
Energy Technology Data Exchange (ETDEWEB)
Kamenshchik, A. Yu. [Dipartimento di Fisica e Astronomia and INFN, Via Irnerio 46, 40126 Bologna (Italy) and L.D. Landau Institute for Theoretical Physics of the Russian Academy of Sciences, Kosygin str. 2, 119334 Moscow (Russian Federation); Manti, S. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy)
2013-02-21
We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.
Dimensional reduction of the Standard Model coupled to a new singlet scalar field
Energy Technology Data Exchange (ETDEWEB)
Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Tenkanen, Tuomas V.I. [Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland); Tranberg, Anders [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Vuorinen, Aleksi [Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland); Weir, David J. [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Department of Physics and Helsinki Institute of Physics,P.O. Box 64, FI-00014 University of Helsinki (Finland)
2017-03-01
We derive an effective dimensionally reduced theory for the Standard Model augmented by a real singlet scalar. We treat the singlet as a superheavy field and integrate it out, leaving an effective theory involving only the Higgs and SU(2){sub L}×U(1){sub Y} gauge fields, identical to the one studied previously for the Standard Model. This opens up the possibility of efficiently computing the order and strength of the electroweak phase transition, numerically and nonperturbatively, in this extension of the Standard Model. Understanding the phase diagram is crucial for models of electroweak baryogenesis and for studying the production of gravitational waves at thermal phase transitions.
Classical and quantum Big Brake cosmology for scalar field and tachyonic models
International Nuclear Information System (INIS)
Kamenshchik, A. Yu.; Manti, S.
2013-01-01
We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.
Effective action for scalar fields and generalized zeta-function regularization
International Nuclear Information System (INIS)
Cognola, Guido; Zerbini, Sergio
2004-01-01
Motivated by the study of quantum fields in a Friedmann-Robertson-Walker space-time, the one-loop effective action for a scalar field defined in the ultrastatic manifold RxH 3 /Γ, H 3 /Γ being the finite volume, noncompact, hyperbolic spatial section, is investigated by a generalization of zeta-function regularization. It is shown that additional divergences may appear at the one-loop level. The one-loop renormalizability of the model is discussed and, making use of a generalization of zeta-function regularization, the one-loop renormalization group equations are derived
Pappas, T.; Kanti, P.; Pappas, N.
2016-01-01
In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild-de-Sitter black hole as well as on the projected-on-the-brane 4-dimensional background. The scalar fields have also a non-minimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then pro...
International Nuclear Information System (INIS)
Cabrera, J. A.; Martin, R.
1976-01-01
We present in this work a review of the conventional quantization procedure, the proposed by I.E. Segal and a new quantization procedure similar to this one for use in non linear problems. We apply this quantization procedures to different potentials and we obtain the appropriate equations of motion. It is shown that for the linear case the three procedures exposed are equivalent but for the non linear cases we obtain different equations of motion and different energy spectra. (Author) 16 refs
Covarient quantization of heterotic strings in supersymmetric chiral boson formulation
International Nuclear Information System (INIS)
Yu, F.
1992-01-01
This dissertation presents the covariant supersymmetric chiral boson formulation of the heterotic strings. The main feature of this formulation is the covariant quantization of the so-called leftons and rightons -- the (1,0) supersymmetric generalizations of the world-sheet chiral bosons -- that constitute basic building blocks of general heterotic-type string models. Although the (Neveu-Schwarz-Ramond or Green-Schwarz) heterotic strings provide the most realistic string models, their covariant quantization, with the widely-used Siegel formalism, has never been rigorously carried out. It is clarified in this dissertation that the covariant Siegel formalism is pathological upon quantization. As a test, a general classical covariant (NSR) heterotic string action that has the Siegel symmetry is constructed in arbitrary curved space-time coupled to (1,0) world-sheet super-gravity. In the light-cone gauge quantization, the critical dimensions are derived for such an action with leftons and rightons compactified on group manifolds G L x G R . The covariant quantization of this action does not agree with the physical results in the light-cone gauge quantization. This dissertation establishes a new formalism for the covariant quantization of heterotic strings. The desired consistent covariant path integral quantization of supersymmetric chiral bosons, and thus the general (NSR) heterotic-type strings with leftons and rightons compactified on torus circle-times d L S 1 x circle-times d R S 1 are carried out. An infinite set of auxiliary (1,0) scalar superfields is introduced to convert the second-class chiral constraint into first-class ones. The covariant gauge-fixed action has an extended BRST symmetry described by the graded algebra GL(1/1). A regularization respecting this symmetry is proposed to deal with the contributions of the infinite towers of auxiliary fields and associated ghosts
Effect of a chameleon scalar field on the cosmic microwave background
International Nuclear Information System (INIS)
Davis, Anne-Christine; Schelpe, Camilla A. O.; Shaw, Douglas J.
2009-01-01
We show that a direct coupling between a chameleonlike scalar field and photons can give rise to a modified Sunyaev-Zel'dovich (SZ) effect in the cosmic microwave background (CMB). The coupling induces a mixing between chameleon particles and the CMB photons when they pass through the magnetic field of a galaxy cluster. Both the intensity and the polarization of the radiation are modified. The degree of modification depends strongly on the properties of the galaxy cluster such as magnetic field strength and electron number density. Existing SZ measurements of the Coma cluster enable us to place constraints on the photon-chameleon coupling. The constrained conversion probability in the cluster is P Coma (204 GHz) -5 at 95% confidence, corresponding to an upper bound on the coupling strength of g eff (cell) -8 GeV -1 or g eff (Kolmo) -10 GeV -1 , depending on the model that is assumed for the cluster magnetic field structure. We predict the radial profile of the chameleonic CMB intensity decrement. We find that the chameleon effect extends farther toward the edges of the cluster than the thermal SZ effect. Thus we might see a discrepancy between the x-ray emission data and the observed SZ intensity decrement. We further predict the expected change to the CMB polarization arising from the existence of a chameleonlike scalar field. These predictions could be verified or constrained by future CMB experiments.
Abo-Kahla, D. A. M.; Abdel-Aty, M.; Farouk, A.
2018-05-01
An atom with only two energy eigenvalues is described by a two-dimensional state space spanned by the two energy eigenstates is called a two-level atom. We consider the interaction between a two-level atom system with a constant velocity. An analytic solution of the systems which interacts with a quantized field is provided. Furthermore, the significant effect of the temperature on the atomic inversion, the purity and the information entropy are discussed in case of the initial state either an exited state or a maximally mixed state. Additionally, the effect of the half wavelengths number of the field-mode is investigated.
Perturbation theory from stochastic quantization
International Nuclear Information System (INIS)
Hueffel, H.
1984-01-01
By using a diagrammatical method it is shown that in scalar theories the stochastic quantization method of Parisi and Wu gives the usual perturbation series in Feynman diagrams. It is further explained how to apply the diagrammatical method to gauge theories, discussing the origin of ghost effects. (Author)
Emission of massive scalar fields by a higher-dimensional rotating black hole
International Nuclear Information System (INIS)
Kanti, P.; Pappas, N.
2010-01-01
We perform a comprehensive study of the emission of massive scalar fields by a higher-dimensional, simply rotating black hole both in the bulk and on the brane. We derive approximate, analytic results as well as exact numerical ones for the absorption probability, and demonstrate that the two sets agree very well in the low and intermediate-energy regime for scalar fields with mass m Φ ≤1 TeV in the bulk and m Φ ≤0.5 TeV on the brane. The numerical values of the absorption probability are then used to derive the Hawking radiation power emission spectra in terms of the number of extra dimensions, angular-momentum of the black hole and mass of the emitted field. We compute the total emissivities in the bulk and on the brane, and demonstrate that, although the brane channel remains the dominant one, the bulk-over-brane energy ratio is considerably increased (up to 34%) when the mass of the emitted field is taken into account.
Equations of motion for a (non-linear) scalar field model as derived from the field equations
International Nuclear Information System (INIS)
Kaniel, S.; Itin, Y.
2006-01-01
The problem of derivation of the equations of motion from the field equations is considered. Einstein's field equations have a specific analytical form: They are linear in the second order derivatives and quadratic in the first order derivatives of the field variables. We utilize this particular form and propose a novel algorithm for the derivation of the equations of motion from the field equations. It is based on the condition of the balance between the singular terms of the field equation. We apply the algorithm to a non-linear Lorentz invariant scalar field model. We show that it results in the Newton law of attraction between the singularities of the field moved on approximately geodesic curves. The algorithm is applicable to the N-body problem of the Lorentz invariant field equations. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
Computation of 3-D magnetostatic fields using a reduced scalar potential
International Nuclear Information System (INIS)
Biro, O.; Preis, K.; Vrisk, G.; Richter, K.R.
1993-01-01
The paper presents some improvements to the finite element computation of static magnetic fields in three dimensions using a reduced magnetic scalar potential. New methods are described for obtaining an edge element representation of the rotational part of the magnetic field from a given source current distribution. In the case when the current distribution is not known in advance, a boundary value problem is set up in terms of a current vector potential. An edge element representation of the solution can be directly used in the subsequent magnetostatic calculation. The magnetic field in a D.C. arc furnace is calculated by first determining the current distribution in terms of a current vector potential. A three dimensional problem involving a permanent magnet as well as a coil is solved and the magnetic field in some points is compared with measurement results
In-Flight spacecraft magnetic field monitoring using scalar/vector gradiometry
DEFF Research Database (Denmark)
Primdahl, Fritz; Risbo, Torben; Merayo, José M.G.
2006-01-01
Earth magnetic field mapping from planetary orbiting satellites requires a spacecraft magnetic field environment control program combined with the deployment of the magnetic sensors on a boom in order to reduce the measurement error caused by the local spacecraft field. Magnetic mapping missions...... (Magsat, Oersted, CHAMP, SAC-C MMP and the planned ESA Swarm project) carry a vector magnetometer and an absolute scalar magnetometer for in-flight calibration of the vector magnetometer scale values and for monitoring of the inter-axes angles and offsets over time intervals from months to years...... sensors onboard the Oersted satellite. For Oersted, a large difference between the pre-flight determined spacecraft magnetic field and the in-flight estimate exists causing some concern about the general applicability of the dual sensors technique....
Critical collapse of a rotating scalar field in $2+1$ dimensions
Jałmużna, Joanna; Gundlach, Carsten
2017-01-01
We carry out numerical simulations of the collapse of a complex rotating scalar field of the form $\\Psi(t,r,\\theta)=e^{im\\theta}\\Phi(t,r)$, giving rise to an axisymmetric metric, in 2+1 spacetime dimensions with cosmological constant $\\Lambda0$ is very different from the case $m=0$ we have considered before: the thresholds for mass scaling and Ricci scaling are significantly different (for the same family), scaling stops well above the scale set by $\\Lambda$, and the exponents depend strongly...
Time dependent solitons of noncommutative Chern-Simons theory coupled to scalar fields
Hadasz, Leszek; Lindström, Ulf; Roček, Martin; von Unge, Rikard
2004-05-01
We study one- and two-soliton solutions of noncommutative Chern-Simons theory coupled to a nonrelativistic or a relativistic scalar field. In the nonrelativistic case, we find a tower of new stationary time-dependent solutions, all with the same charge density, but with increasing energies. The dynamics of these solitons cannot be studied using traditional moduli space techniques, but we do find a nontrivial symplectic form on the phase space indicating that the moduli space is not flat. In the relativistic case we find the metric on the two soliton moduli space.
Time dependent solitons of noncommutative Chern-Simons theory coupled to scalar fields
International Nuclear Information System (INIS)
Hadasz, Leszek; Lindstroem, Ulf; Rocek, Martin; Unge, Rikard von
2004-01-01
We study one- and two-soliton solutions of noncommutative Chern-Simons theory coupled to a nonrelativistic or a relativistic scalar field. In the nonrelativistic case, we find a tower of new stationary time-dependent solutions, all with the same charge density, but with increasing energies. The dynamics of these solitons cannot be studied using traditional moduli space techniques, but we do find a nontrivial symplectic form on the phase space indicating that the moduli space is not flat. In the relativistic case we find the metric on the two soliton moduli space
Integrable model of Yang-Mills theory with scalar field and quasi-instantons
International Nuclear Information System (INIS)
Yatsun, V.A.
1988-01-01
In the framework of Euclidean conformally invariant Yang-Mills theory with a scalar field a study is made of a Hamiltonian system with two degrees of freedom that is integrable for a definite relationship between the coupling constants. A particular solution of the Hamilton-Jacobi equation leads to first-order equations that ensure a nonself-dual solution of instanton type of the considered model. As generalization of the first-order equations a quasiself-dual equation that can be integrated by means of the 't Hooft ansatz and leads to quasiself-dual instantons - quasi-instantons - is proposed
String dynamics, spontaneous breaking of supersymmetry, and dual scalar field theory
International Nuclear Information System (INIS)
Liu Luxin
2009-01-01
The dynamics of a vortex string, which describes the Nambu-Goldstone modes of the spontaneous breakdown of the target space D=4, N=1 supersymmetry and internal U(1) R symmetry to the world sheet ISO(1,1) symmetry, is constructed by using the approach of nonlinear realization. The resulting action describing the low energy oscillations of the string into the covolume (super)space is found to have an invariant synthesis form of the Akulov-Volkov and Nambu-Goto actions. Its dual scalar field action is obtained by means of introducing two vectorial Lagrangian multipliers into the action of the string.
Numerical calculation of the entanglement entropy for scalar field in dilaton spacetimes
Huang, Shifeng; Fang, Xiongjun; Jing, Jiliang
2018-06-01
Using coupled harmonic oscillators model, we numerical analyze the entanglement entropy of massless scalar field in Gafinkle-Horowitz-Strominger (GHS) dilaton spacetime and Gibbons-Maeda (GM) dilaton spacetime. By numerical fitting, we find that the entanglement entropy of the dilaton black holes receive contribution from dilaton charge and is proportional to the area of the event horizon. It is interesting to note that the results of numerical fitting are coincide with ones obtained by using brick wall method and Euclidean path integral approach.
Berry phase of primordial scalar and tensor perturbations in single-field inflationary models
Balajany, Hamideh; Mehrafarin, Mohammad
2018-06-01
In the framework of the single-field slow-roll inflation, we derive the Hamiltonian of the linear primordial scalar and tensor perturbations in the form of time-dependent harmonic oscillator Hamiltonians. We find the invariant operators of the resulting Hamiltonians and use their eigenstates to calculate the adiabatic Berry phase for sub-horizon modes in terms of the Lewis-Riesenfeld phase. We conclude by discussing the discrepancy in the results of Pal et al. (2013) [21] for these Berry phases, which is resolved to yield agreement with our results.
Solving Schwinger-Dyson equations by truncation in zero-dimensional scalar quantum field theory
International Nuclear Information System (INIS)
Okopinska, A.
1991-01-01
Three sets of Schwinger-Dyson equations, for all Green's functions, for connected Green's functions, and for proper vertices, are considered in scalar quantum field theory. A truncation scheme applied to the three sets gives three different approximation series for Green's functions. For the theory in zero-dimensional space-time the results for respective two-point Green's functions are compared with the exact value calculated numerically. The best convergence of the truncation scheme is obtained for the case of proper vertices
Hees, A.; Guéna, J.; Abgrall, M.; Bize, S.; Wolf, P.
2016-01-01
We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but pr...
{theta}-vacua in the light-front quantized Schwinger model
Energy Technology Data Exchange (ETDEWEB)
Srivastava, Prem P. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
1996-09-01
The light-front quantization of the bosonized Schwinger model is discussed in the continuum formulation. The proposal, successfully used earlier for describing the spontaneous symmetry breaking on the light-front, of separating first the scalar field into the dynamical condensate and the fluctuation fields before employing the standard Dirac method works here as well. Some topics on the front form theory are summarized in the Appendices and attention is drawn to the fact that the theory quantized, at x{sup +} seems already to carry information on equal x{sup -} commutators as well. (author). 21 refs.
θ-vacua in the light-front quantized Schwinger model
International Nuclear Information System (INIS)
Srivastava, Prem P.
1996-09-01
The light-front quantization of the bosonized Schwinger model is discussed in the continuum formulation. The proposal, successfully used earlier for describing the spontaneous symmetry breaking on the light-front, of separating first the scalar field into the dynamical condensate and the fluctuation fields before employing the standard Dirac method works here as well. Some topics on the front form theory are summarized in the Appendices and attention is drawn to the fact that the theory quantized, at x + seems already to carry information on equal x - commutators as well. (author). 21 refs
Scalar field cosmology: I. Asymptotic freedom and the initial-value problem
International Nuclear Information System (INIS)
Huang, Kerson; Low, Hwee-Boon; Tung, Roh-Suan
2012-01-01
The purpose of this work is to use a renormalized quantum scalar field to investigate very early cosmology, in the Planck era immediately following the big bang. Renormalization effects make the field potential dependent on length scale, and are important during the big bang era. We use the asymptotically free Halpern-Huang scalar field, which is derived from renormalization-group analysis, and solve Einstein's equation with Robertson-Walker metric as an initial-value problem. The main prediction is that the Hubble parameter follows a power law: H≡ a-dot /a∼t -p , and the universe expands at an accelerated rate: a ∼ expt 1-p . This gives 'dark energy', with an equivalent cosmological constant that decays in time like t -2p , which avoids the 'fine-tuning' problem. The power law predicts a simple relation for the galactic redshift. Comparison with data leads to the speculation that the universe experienced a crossover transition, which was completed about seven billion years ago. (paper)
A kinetic theory of diffusion in general relativity with cosmological scalar field
International Nuclear Information System (INIS)
Calogero, Simone
2011-01-01
A new model to describe the dynamics of particles undergoing diffusion in general relativity is proposed. The evolution of the particle system is described by a Fokker-Planck equation without friction on the tangent bundle of spacetime. It is shown that the energy-momentum tensor for this matter model is not divergence-free, which makes it inconsistent to couple the Fokker-Planck equation to the Einstein equations. This problem can be solved by postulating the existence of additional matter fields in spacetime or by modifying the Einstein equations. The case of a cosmological scalar field term added to the left hand side of the Einstein equations is studied in some details. For the simplest cosmological model, namely the flat Robertson-Walker spacetime, it is shown that, depending on the initial value of the cosmological scalar field, which can be identified with the present observed value of the cosmological constant, either unlimited expansion or the formation of a singularity in finite time will occur in the future. Future collapse into a singularity also takes place for a suitable small but positive present value of the cosmological constant, in contrast to the standard diffusion-free scenario
Approximate KMS states for scalar and spinor fields in Friedmann-Robertson-Walker spacetimes
Energy Technology Data Exchange (ETDEWEB)
Dappiaggi, Claudio; Hack, Thomas-Paul [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Pinamonti, Nicola [Roma ' ' Tor Vergata' ' Univ. (Italy). Dipt. di Matematica
2010-09-15
We construct and discuss Hadamard states for both scalar and Dirac spinor fields in a large class of spatially flat Friedmann-Robertson-Walker spacetimes characterised by an initial phase either of exponential or of power-law expansion. The states we obtain can be interpreted as being in thermal equilibrium at the time when the scale factor a has a specific value a = a{sub 0}. In the case a{sub 0} = 0, these states fulfil a strict KMS condition on the boundary of the spacetime, which is either a cosmological horizon, or a Big Bang hypersurface. Furthermore, in the conformally invariant case, they are conformal KMS states on the full spacetime. However, they provide a natural notion of an approximate KMS state also in the remaining cases, especially for massive fields. On the technical side, our results are based on a bulk-to-boundary reconstruction technique already successfully applied in the scalar case and here proven to be suitable also for spinor fields. The potential applications of the states we find range over a broad spectrum, but they appear to be suited to discuss in particular thermal phenomena such as the cosmic neutrino background or the quantum state of dark matter. (orig.)
Approximate KMS states for scalar and spinor fields in Friedmann-Robertson-Walker spacetimes
International Nuclear Information System (INIS)
Dappiaggi, Claudio; Hack, Thomas-Paul; Pinamonti, Nicola
2010-09-01
We construct and discuss Hadamard states for both scalar and Dirac spinor fields in a large class of spatially flat Friedmann-Robertson-Walker spacetimes characterised by an initial phase either of exponential or of power-law expansion. The states we obtain can be interpreted as being in thermal equilibrium at the time when the scale factor a has a specific value a = a 0 . In the case a 0 = 0, these states fulfil a strict KMS condition on the boundary of the spacetime, which is either a cosmological horizon, or a Big Bang hypersurface. Furthermore, in the conformally invariant case, they are conformal KMS states on the full spacetime. However, they provide a natural notion of an approximate KMS state also in the remaining cases, especially for massive fields. On the technical side, our results are based on a bulk-to-boundary reconstruction technique already successfully applied in the scalar case and here proven to be suitable also for spinor fields. The potential applications of the states we find range over a broad spectrum, but they appear to be suited to discuss in particular thermal phenomena such as the cosmic neutrino background or the quantum state of dark matter. (orig.)
Casimir-type effects for scalar fields interacting with material slabs
International Nuclear Information System (INIS)
Fialkovsky, I V; Pis'mak, Yu M; Markov, V N
2010-01-01
We study the field theoretical model of a scalar field in the presence of spacial inhomogeneities in the form of one and two finite-width mirrors (material slabs). The interaction of the scalar field with the defect is described with a position-dependent mass term. For a single-layer system we develop a rigorous calculation method and derive explicitly the propagator of the theory, the S-matrix elements and the Casimir self-energy of the slab. Detailed investigation of particular limits of self-energy is presented, and the connection to known cases is discussed. The calculation method is also found applicable to the two-mirror case. With its help we derive the corresponding Casimir energy and analyze it. For particular values of parameters of the model an obtained result recovers the Lifshitz formula. We also propose a procedure to unambiguously obtain the finite Casimir self-energy of a single slab without reference to any renormalization conditions. We hope that our approach can be applied to the calculation of Casimir self-energies in other demanded cases (such as a dielectric ball, etc).
Initial-boundary-value problem of the self-gravitating scalar field in the Bondi-Sachs gauge
International Nuclear Information System (INIS)
Frittelli, Simonetta; Gomez, Roberto
2007-01-01
It is shown that, in the Bondi-Sachs gauge that fixes the speed of incoming light rays to the value 1, the Einstein equations coupled to a scalar field in spherical symmetry are cast into a symmetric-hyperbolic system of equations for the scalar field, lapse and shift as fundamental variables. In this system of equations, the lapse and shift are incoming characteristic fields, and the scalar field has three components: incoming, outgoing and static. A constraint-preserving boundary condition is prescribed by imposing the projection of the Einstein equation normal to the boundary at the outer value of the radial coordinate. The boundary condition specifies one of the two incoming metric fields. The remaining incoming metric field and the incoming scalar field component need to be specified arbitrarily. Numerical simulations of the scattering of the scalar field by a black hole in the nonlinear regime are presented that illustrate interesting facts about black-hole physics and the behavior of the characteristic variables of the problem
Hees, A; Guéna, J; Abgrall, M; Bize, S; Wolf, P
2016-08-05
We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.
International Nuclear Information System (INIS)
Chirde, V.R.; Shekh, S.H.
2016-01-01
The modified theories of gravity have engrossed much attention in the last decade, especially f(R) gravity. In this contextual exploration, we investigate interaction between barotropic fluid and dark energy with zero-mass scalar field for the spatially homogeneous and isotropic flat FRW universe. In this universe, the field equations correspond to the particular choice of f(R) = R+bR m . The exact solutions of the field equations are obtained by applying volumetric power law and exponential law of expansion. In power and exponential law of expansion, the universe shows both matter dominated and DE era for b ≤ 0 and b ≥ 0 and remain present in dark era respectively, but power law model is fully occupying with real matter for b > 0 and for b < 0 exponential model expands with negative pressure and remain present in matter dominated phase respectively. The physical behavior of the universe has been discussed by using some physical quantities
Accretion of a symmetry-breaking scalar field by a Schwarzschild black hole.
Traykova, Dina; Braden, Jonathan; Peiris, Hiranya V
2018-03-06
We simulate the behaviour of a Higgs-like field in the vicinity of a Schwarzschild black hole using a highly accurate numerical framework. We consider both the limit of the zero-temperature Higgs potential and a toy model for the time-dependent evolution of the potential when immersed in a slowly cooling radiation bath. Through these numerical investigations, we aim to improve our understanding of the non-equilibrium dynamics of a symmetry-breaking field (such as the Higgs) in the vicinity of a compact object such as a black hole. Understanding this dynamics may suggest new approaches for studying properties of scalar fields using black holes as a laboratory.This article is part of the Theo Murphy meeting issue 'Higgs Cosmology'. © 2018 The Author(s).
Initial time singularities and admissible initial states for a system of coupled scalar fields
Energy Technology Data Exchange (ETDEWEB)
Baacke, Juergen [Technische Univ. Dortmund (Germany). Fakultaet Physik; Kevlishvili, Nina [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); GAS, Tbilisi (Georgia). Andronikashvili Inst. of Physics
2009-10-15
We discuss the problem of initial states for a system of coupled scalar fields out of equilibrium in the one-loop approximation. The fields consist of classical background fields, taken constant in space, and quantum fluctuations. If the initial state is the adiabatic vacuum, i.e., the ground state of a Fock space of particle excitations that diagonalize the mass matrix, the energy-momentum tensor is infinite at t=0, its most singular part behaves as 1/t. When the system is coupled to gravity this presents a problem that we solve by a Bogoliubov transformation of the naive initial state. As a side result we also discuss the canonical formalism and the adiabatic particle number for such a system. Most of the formalism is presented for Minkowksi space. Embedding the system and its dynamics into a flat FRW universe is straightforward and we briefly address the essential modifications. (orig.)
Initial time singularities and admissible initial states for a system of coupled scalar fields
International Nuclear Information System (INIS)
Baacke, Juergen; Kevlishvili, Nina; GAS, Tbilisi
2009-10-01
We discuss the problem of initial states for a system of coupled scalar fields out of equilibrium in the one-loop approximation. The fields consist of classical background fields, taken constant in space, and quantum fluctuations. If the initial state is the adiabatic vacuum, i.e., the ground state of a Fock space of particle excitations that diagonalize the mass matrix, the energy-momentum tensor is infinite at t=0, its most singular part behaves as 1/t. When the system is coupled to gravity this presents a problem that we solve by a Bogoliubov transformation of the naive initial state. As a side result we also discuss the canonical formalism and the adiabatic particle number for such a system. Most of the formalism is presented for Minkowksi space. Embedding the system and its dynamics into a flat FRW universe is straightforward and we briefly address the essential modifications. (orig.)
2> for a scalar field in 2D black holes: A new uniform approximation
International Nuclear Information System (INIS)
Frolov, V.; Sushkov, S.V.; Zelnikov, A.
2003-01-01
We study nonconformal quantum scalar fields and averages of their local observables (such as 2 > ren and μν > ren ) in the spacetime of a two-dimensional black hole. In order to get an analytical approximation for these expressions the WKB approximation is often used. We demonstrate that at the horizon the WKB approximation is violated for a nonconformal field, that is, when the field mass or/and the parameter of nonminimal coupling does not vanish. We propose a new 'uniform approximation' which solves this problem. We use this approximation to obtain an improved analytical approximation for 2 > ren in the two-dimensional black hole geometry. We compare the results obtained with numerical calculations
Neutron stars in relativistic mean field theory with isovector scalar meson
Energy Technology Data Exchange (ETDEWEB)
Kubis, S.; Kutschera, M.; Stachniewicz, S. [H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland)
1998-03-01
We study the equation of state (EOS) of {beta}-stable dense matter and models of neutron stars in the relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the {delta}-meson (a{sub 0}(980)). A range of values of the {delta}-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E{sub s}{approx}30 MeV. We find that the quantity most sensitive to the {delta}-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the {delta}-field. The energy per baryon also increases but the effect is smaller. The EOS becomes slightly stiffer and the maximum neutron star mass increases for stronger {delta}-meson coupling. (author) 8 refs, 6 figs, 2 tabs
Neutron stars in relativistic mean field theory with isovector scalar meson
International Nuclear Information System (INIS)
Kubis, S.; Kutschera, M.; Stachniewicz, S.
1996-12-01
We study the equation of state (EOS) of neutron star matter in a relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the δ-meson [a 0 (980)]. A range of values of the δ-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E s ∼ 30 MeV. We find that proton fraction of neutron star matter is higher in the presence of the δ-field whereas the energy per particle is lower. The EOS becomes slightly stiffer and the maximum mass of the neutron star increased with increasing δmeson coupling. The effect is stronger for soft EOS. (author). 7 refs, 6 figs, 1 tab
Neutron stars in relativistic mean field theory with isovector scalar meson
International Nuclear Information System (INIS)
Kubis, S.; Kutschera, M.; Stachniewicz, S.
1998-01-01
We study the equation of state (EOS) of β-stable dense matter and models of neutron stars in the relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the δ-meson (a 0 (980)). A range of values of the δ-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E s ∼30 MeV. We find that the quantity most sensitive to the δ-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the δ-field. The energy per baryon also increases but the effect is smaller. The EOS becomes slightly stiffer and the maximum neutron star mass increases for stronger δ-meson coupling. (author)
Neutron stars in relativistic mean field theory with isovector scalar meson
Energy Technology Data Exchange (ETDEWEB)
Kubis, S.; Kutschera, M.; Stachniewicz, S. [Institute of Nuclear Physics, Cracow (Poland)
1996-12-01
We study the equation of state (EOS) of neutron star matter in a relativistic mean field (RMF) theory with the isovector scalar mean field corresponding to the {delta}-meson [a{sub 0}(980)]. A range of values of the {delta}-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E{sub s} {approx} 30 MeV. We find that proton fraction of neutron star matter is higher in the presence of the {delta}-field whereas the energy per particle is lower. The EOS becomes slightly stiffer and the maximum mass of the neutron star increased with increasing {delta}meson coupling. The effect is stronger for soft EOS. (author). 7 refs, 6 figs, 1 tab.
Reheating signature in the gravitational wave spectrum from self-ordering scalar fields
Energy Technology Data Exchange (ETDEWEB)
Kuroyanagi, Sachiko [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Hiramatsu, Takashi [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, 606-8502 Japan (Japan); Yokoyama, Jun' ichi, E-mail: skuro@nagoya-u.jp, E-mail: hiramatz@yukawa.kyoto-u.ac.jp, E-mail: yokoyama@resceu.s.u-tokyo.ac.jp [Research Center for the Early Universe (RESCEU), School of Science, The University of Tokyo, Tokyo, 113-0033 Japan (Japan)
2016-02-01
We investigate the imprint of reheating on the gravitational wave spectrum produced by self-ordering of multi-component scalar fields after a global phase transition. The equation of state of the Universe during reheating, which usually has different behaviour from that of a radiation-dominated Universe, affects the evolution of gravitational waves through the Hubble expansion term in the equations of motion. This gives rise to a different power-law behavior of frequency in the gravitational wave spectrum. The reheating history is therefore imprinted in the shape of the spectrum. We perform 512{sup 3} lattice simulations to investigate how the ordering scalar field reacts to the change of the Hubble expansion and how the reheating effect arises in the spectrum. We also compare the result with inflation-produced gravitational waves, which has a similar spectral shape, and discuss whether it is possible to distinguish the origin between inflation and global phase transition by detecting the shape with future direct detection gravitational wave experiments such as DECIGO.
International Nuclear Information System (INIS)
Neveu, Jeremy
2014-01-01
The nature of dark energy and dark matter is still unknown today. Light scalar field models have been proposed to explain the late-time accelerated expansion of the Universe and the apparent abundance of non-baryonic matter. In the first part of this thesis, the Galileon theory, a well-posed modified gravity theory preserving the local gravitation thanks to the Vainshtein screening effect, is accurately tested against recent cosmological data. Observational constraints are derived on the model parameters using cosmological distance and growth rate of structure measurements. A good agreement is observed between data and theory predictions. The Galileon theory appears therefore as a promising alternative to the cosmological constant scenario. In the second part, the dark matter question is explored through an extra-dimension theory containing massive and stable scalar fields called Branons. Branon production is searched for in the proton-proton collisions that were collected by the Compact Muon Solenoid experiment in 2012 at the Large Hadron Collider. Events with a single photon and transverse missing energy are selected in this data set and compared to the Standard Model and instrumental background estimates. No signature of new physics is observed, so experimental limits on the Branon model parameters are derived. This thesis concludes with some ideas to reach an unified description of both models in the frame of extra-dimension theories. (author) [fr
Energy Technology Data Exchange (ETDEWEB)
Faizal, Mir
2013-12-18
In this Letter we will analyze the creation of the multiverse. We will first calculate the wave function for the multiverse using third quantization. Then we will fourth-quantize this theory. We will show that there is no single vacuum state for this theory. Thus, we can end up with a multiverse, even after starting from a vacuum state. This will be used as a possible explanation for the creation of the multiverse. We also analyze the effect of interactions in this fourth-quantized theory.
System Identification with Quantized Observations
Wang, Le Yi; Zhang, Jifeng; Zhao, Yanlong
2010-01-01
This book presents recently developed methodologies that utilize quantized information in system identification and explores their potential in extending control capabilities for systems with limited sensor information or networked systems. The results of these methodologies can be applied to signal processing and control design of communication and computer networks, sensor networks, mobile agents, coordinated data fusion, remote sensing, telemedicine, and other fields in which noise-corrupted quantized data need to be processed. Providing a comprehensive coverage of quantized identification,
International Nuclear Information System (INIS)
Loran, Farhang
2004-01-01
We solve Klein-Gordon equation for massless scalars on (d+1)-dimensional Minkowski (Euclidean) space in terms of the Cauchy data on the hypersurface t=0. By inserting the solution into the action of massless scalars in Minkowski (Euclidean) space we obtain the action of dual theory on the boundary t=0 which is exactly the holographic dual of conformally coupled scalars on (d+1)-dimensional (Euclidean anti) de Sitter space obtained in (A)dS/CFT correspondence. The observed equivalence of dual theories is explained using the one-to-one map between conformally coupled scalar fields on Minkowski (Euclidean) space and (Euclidean anti) de Sitter space which is an isomorphism between the hypersurface t=0 of Minkowski (Euclidean) space and the boundary of (A)dS space
The effect of the scalar-isovector meson field on hyperon-rich neutron star matter
International Nuclear Information System (INIS)
Mi, Aijun; Zuo, Wei; Li, Ang
2008-01-01
We investigate the effect of the scalar-isovector δ-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the framework of the relativistic mean field theory. The influence of the δ-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npeμ neutron star matter. We find that inclusion of the δ-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the δ-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the δ-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, whereas inclusion of the δ-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the δ-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Σ hyperons. (author)