Absence Of Ghosts Research Articles

Withholding potentials, absence of ghosts, and relationship between minimal dilatonic gravity andf(R)theories

We study the relation between minimal dilatonic gravity (MDG) and $f(R)$ theories of gravity and establish strict conditions for their global equivalence. Such equivalence takes place only for a certain class of cosmological potentials, dubbed here ``withholding potentials,'' since they prevent change of the sign of the dilaton $\ensuremath{\Phi}$. The withholding property ensures the attractive character of gravity, as well as absence of ghosts and a tachyon in the gravi-dilaton sector and yields certain asymptotic of the functions $f(R)$. Large classes of withholding cosmological potentials and functions $f(R)$ are found and described in detail. The particle content of the gravi-dilaton sector is found using perturbation theory around the de Sitter vacuum of MDG. Two phenomena, scalaron waves and induction of gravitational waves by the scalaron field, are discussed using the derived wave equations for MDG scalaron and graviton in the de Sitter background. Seemingly, the MDG and $f(R)$ theories offer a unified description of dark energy and dark matter.

Nonlinear massive gravity with additional primary constraint and absence of ghosts

We complete the Hamiltonian analysis of specific model of non-linear massive gravity that was started in arXiv:1112.5267. We identify the primary constraint and corresponding secondary constraint. We show that they are the second class constraints and hence they lead to the elimination of the additional scalar mode. We also find that the remaining constraints are the first class constraints with the structure that corresponds to the manifestly diffeomorphism invariant theory. Finally we determine the number of physical degrees of freedom and we show that it corresponds to the number of physical modes of massive gravity.

Confirmation of the secondary constraint and absence of ghost in massive gravity and bimetric gravity

In massive gravity and in bimetric theories of gravity, two constraints are needed to eliminate the two phase-space degrees of freedom of the Boulware-Deser ghost. For recently proposed non-linear theories, a Hamiltonian constraint has been shown to exist and an associated secondary constraint was argued to arise as well. In this paper we explicitly demonstrate the existence of the secondary constraint. Thus the Boulware-Deser ghost is completely absent from these non-linear massive gravity theories and from the corresponding bimetric theories.

Notes on wormhole existence in scalar-tensor and F(R) gravity

Some recent papers have claimed the existence of static, spherically symmetric wormhole solutions to gravitational field equations in the absence of ghost (or phantom) degrees of freedom. We show that in some such cases the solutions in question are actually not of wormhole nature while in cases where a wormhole is obtained, the effective gravitational constant G eff is negative in some region of space, i.e., the graviton becomes a ghost. In particular, it is confirmed that there are no vacuum wormhole solutions of the Brans-Dicke theory with zero potential and the coupling constant ω > −3/2, except for the case ω = 0; in the latter case, G eff < 0 in the region beyond the throat. The same is true for wormhole solutions of F(R) gravity: special wormhole solutions are only possible if F(R) contains an extremum at which G eff changes its sign.

Degravitation of the cosmological constant and graviton width

We study the possibility of decoupling gravity from the vacuum energy. This is effectively equivalent to promoting Newton's constant to a high-pass filter that degravitates sources of characteristic wavelength larger than a certain macroscopic (super) horizon scale $L$. We study the underlying physics and the consistency of this phenomenon. In particular, the absence of ghosts, already at the linear level, implies that in any such theory the graviton should either have a mass $1/L$, or be a resonance of similar width. This has profound physical implications for the degravitation idea.

Conscious will in the absence of ghosts, hypnotists, and other people

We suggest that certain experiences reported by patients with schizophrenia show that priority, consistency, and exclusivity are not sufficient for the experience of willing an action. Furthermore, we argue that even if priority, consistency, and exclusivity cause the experience of being the author of an action, this does not mean that conscious will is an illusion.

Classical and Quantum Consistency of the DGP Model

We study the Dvali-Gabadadze-Porrati model by the method of the boundary effective action. The truncation of this action to the bending mode \pi consistently describes physics in a wide range of regimes both at the classical and at the quantum level. The Vainshtein effect, which restores agreement with precise tests of general relativity, follows straightforwardly. We give a simple and general proof of stability, i.e. absence of ghosts in the fluctuations, valid for most of the relevant cases, like for instance the spherical source in asymptotically flat space. However we confirm that around certain interesting self-accelerating cosmological solutions there is a ghost. We consider the issue of quantum corrections. Around flat space \pi becomes strongly coupled below a macroscopic length of 1000 km, thus impairing the predictivity of the model. Indeed the tower of higher dimensional operators which is expected by a generic UV completion of the model limits predictivity at even larger length scales. We outline a non-generic but consistent choice of counterterms for which this disaster does not happen and for which the model remains calculable and successful in all the astrophysical situations of interest. By this choice, the extrinsic curvature K_{\mu\nu} acts roughly like a dilaton field controlling the strength of the interaction and the cut-off scale at each space-time point. At the surface of Earth the cutoff is \sim 1 cm but it is unlikely that the associated quantum effects be observable in table top experiments.

“The Absence of Ghosts”: Landscape and Identity in the Archaeology of Australia’s Settler Culture

This article is a case study investigating archaeology as a practice embedded in a complex web of culturally constructed codes of meaning or discourses. A distinctive form of discourse concerning the landscape and its role in determining national identity characterizes Australian culture. This discourse has been central to the construction of the idea of the nation and its past: in particular, concepts of the land as hostile and empty, of the bush as the essence of Australia, and of the landscape as feminine. The paper considers the ways in which this landscape discourse has operated within historical archaeological research and heritage management and discusses the implications of these discursive relationships for past and future research.

Phase transition and absence of ghosts in rigid QED

Ordinary QED formulated in the Feynman's space-time picture is equivalent to a one dimensional field theory. In the large N limit there is no phase transition in such a theory. In this letter, we show a phase transition does exist in a generalization of QED characterized by the addition of the curvature of the world line (rigidity) to the Feynman's space-time action. The large distance scale of the disordered phase essentially coincides with ordinary QED, while the ordered phase is strongly coupled. Although rigid QED exhibits the typical pathologies of higher derivative theories at the classical level, we show that both phases of the quantum theory are free of ghosts and tachyons. Quantum fluctuations prevent taking the naive classical limit and inserting the problems of the classical theory.

The mass and the width of the Higgs in the strongly interacting minimal standard model

By the use of the [1, 1] Padé approximanton to the one-loop amplitude for the W LW L → W LW L scattering in the strongly interacting regime of the minimal standard model we build up a new amplitude for this process which has all the required physical properties such as analyticity, unitarity, absence of ghosts, etc. We also show that the I = J = 0 partial wave amplitude has a simple pole in the unphysical sheet which can be interpreted as the physical Higgs particle. The mass of this Higgs particle is shown to be finite and in particular under 1.4 TeV in the limit λ( m H) going to infinity.

Multidimensional Einstein-Yang-Mills theories: Dimensional reduction, spontaneous compactification, and all that

We study some new aspects of dimensional reduction and spontaneous compactification in multidimensional Einstein-Yang-Mills theories. Relations between physical properties (spontaneous sy symmetry breaking, absence of ghosts and tachyons) of the reduced theory and the metric on the multidimensional space and its symmetries are established. Assuming the space of extra dimensions to be a generic coset space we find an effective potential for the spontaneous compactification equations and investigate a class of models possessing compactifying solutions with remarkable properties: (a) the multidimensional vacuum states correspond to the phase with spontaneous symmetry breaking of the reduced theory, (b) there exist solutions with compact time-like extra-dimensions, (c) one of the solutions leads to enlargement of the initial symmetry group of the metric of the internal space.

Blood platelets are concentrated near the wall and red blood cells, in the center in flowing blood.

Hematocrit and vessel wall shear rate are important factors in the transport and subsequent adherence of platelets to vessel wall subendothelium. When mass transport theory is applied to platelets in flowing blood, the blood is usually considered to be a fluid with platelet and red cell wall concentrations similar to the average tube concentration. With the laser-Doppler technique, we found how red blood cell ghosts and platelets were distributed radially for various hematocrits and wall shear rates. Red cell ghosts are crowded near the axis of the tube, with a local hematocrit higher than the average tube hematocrit, and they decrease steadily toward the wall. In the absence of ghosts, platelets exhibit the 'tubular pinch' effect (rigid particles crowding at 0.6 x tube radius). In the presence of ghosts, the platelets are expelled toward the wall region. This high concentration at the wall increases with higher average tube hematocrit and wall shear rates. Increasing the average tube platelet concentration 10 times causes the wall concentration to increase only three times. The increase in platelet adherence observed with increasing hematocrit and increasing wall shear rate can be partially ascribed to increased platelet concentration near the wall. The observation that the increased platelet concentration does not fully explain the platelet adherence data suggests that platelet transport may also be enhanced by a shear rate-dependent rotary motion.

Lorentz-Covariant Lagrangian Formulation of the Interacting Heterotic String Theory

A manifestly Lorentz·covariant lagrangian formulation of the N eveu·Schwarz· Ramond heterotic string interacting with external fields is presented. The action is derived from the action for fully 26·dimensional semi·superstring by a simple ansatz. The compactification occurs automatically due to the heterotic structure. The requirement of superconformal symmetry, necessary to guarantee the absence of ghosts, plays an important role in the formulation. The so· called twist factors also are involved in the theory without introducing them by hands. The toric internal space necessitates a special treatment with respect to the Poisson brackets. l ) has spark­ ed a new revival of the string model as a strong candidate for the unified theory of fundamental interactions. In the low-energy field theory of the superstring (SST-I) they have found that the gravitational and non-Abelian anomalies cancel if and only if the gauge group incorporated in the model is either 50(32) or E8 X E8. In SST the gauge group has been introduced by the Chan-Paton method, but the phenomenologically promising gauge group E8 X E8 cannot be derived in this way. Therefore, the Frenkel-Kac construction 2 ) of the gauge group has focused much

Spontaneous reduction in multidimensional (D=10, 11) supergravity theories with arbitrary signature

Vacuum solutions in multidimensional Kaluza-Klein theories with arbitrary signature are considered. Solutions of 11- and 10-dimensional supergravity theories satisfying the criteria for the absence of ghosts in the effective massless four-dimensional theory are obtained. Solutions corresponding to two four-dimensional universes are constructed, and their possible cosmological consequences are discussed. For D = 10, N = 2 supergravity vacuum solutions with zero cosmological constant are obtained.

Zero-mass normal modes in linearized Poincaré gauge theories

In the framework of a Poincaré gange theory, we consider a Lagrangian density containing nine terms linear or quadratic in the curvature and the torsion tensors. We consider the zero-mass normal modes of the linearized theory and we derive the conditions which the parameters have to satisfy in order to avoid zero-mass ghosts. We consider in detail the additional gauge transformations and the corresponding constraints on the sources which appear for some special values of the parameters. We conclude that a long-range propagation of the totally antisymmetric part of the torsion is not compatible with the absence of ghosts and of unphysical constraints on the sources.

Ghosts in gravity theories with a scalar field

We consider gravitational theories in which the independent fields are the tetrad vectors, the connection and a scalar field. The actions contain terms quadratic in curvature and torsion and are free of dimensional parameters, a feature that could be interesting in view of their quantum behaviour. We give the conditions for the unitarity of these theories, namely the absence of ghosts and tachyons, and determine the set of the unitary ones. In some cases the introduction of the scalar field allows a larger choice of the terms that contain only curvature and torsion.

Theory of the Dual-Fermion String

'In the string model of the fermion we consider the physical meaning of the DiracRamond equation and the supergauge conditions for both the free and. the interacting cases, The interaction of the string with external fields is determined in such a way that it is conformally invariant and is compatible with the gauge conditions. Any fermion states have zero norm when the ground-state fermion has zero mass. For this reason we consider a definition of S-matrix elements:' The proof of the absence of ghosts is then reexamined. The 10-dimensional Dirac equation is reduced to the usual 4-dimensional Dirac equation with a mass term. Finally the isospin quantum number is introduced into the string in such a way that all the algebraic relations remain unchanged.

Spontaneous dynamical breaking of gauge symmetry in dual models

The consequences of gauge invariance are re-examined in dual models with unit intercept when the dimension of space-time has the maximum value compatible with the absence of ghosts. In that case, reggeon-reggeon bound states of zero mass are formed already at second order of perturbation theory. Gauge invariance no longer guarantees that the initially massless SU(3) singlet vector meson remains massless, and the mixing between the reggeon and pomeron sectors of the model yields a massive unitary singlet vector meson already at order g 2. A Lagrangian model which exhibits similar features to the dual situation is discussed.

Interaction between proteases and bovine erythrocyte membranes. II. Binding of fibrinolytic components

Abstract 1. 1. Bovine erythrocyte ghosts bind plasminogen and plasmin, but do not inhibit the caseinolytic activity of plasmin. 2. 2. Urokinase, which is not bound to ghosts, readily activates plasminogen in the presence and absence of ghosts without an apparent loss in efficiency. 3. 3. Inactivation of trypsin solutions at physiological pH is prevented by the presence of ghosts having the capacity to bind the enzyme. 4. 4. Incomplete activation of plasminogen by trypsin is observed upon addition of trypsin to ghosts-plasminogen mixtures or upon addition of plasminogen to ghosts-trypsin mixtures. 5. 5. Increased binding of [ 3 H]trypsin to ghosts is seen in the presence of plasminogen regardless of the order of addition of the proteins to the ghosts, suggesting that there are separate binding sites on the surface of the membranes for trypsin and plasminogen, and that trypsin might be bound both directly to ghosts and to plasminogen which bind to ghosts. 6. 6. Totally acetylatated trypsin incompletely activates plasminogen in the presence of ghosts in a manner identical to that of trypsin. These results are interpreted to suggest that acetylated sites on trypsin, which reduce binding directly to ghosts, are in no way influential in plasminogen activation, and that the binding of plasminogen to ghosts must be the step which, in an unknown manner, affects conformation of the former thereby reducing the efficiency of native trypsin and acetyltrypsin, while exerting no noticeable influence on urokinase activation. 7. 7. A potential role for the possible transport by membranes of zymogens and enzymes involved in fibrinolysis in the blood is suggested.

Generalized Conformal Gauge Conditions in Dual Models

On the basis of conformal invariance in the string model of hadrons we determine the interaction of the string with external field. It is shown that the string is allowed to couple with the external field only at both end points of. the string with· arbitrary coupling .constants. We find generators L. of the conformal transformation in the interacting case; they satisfy the same conformal gauge algebra as L, in the free case. We also find generalized conformal gauge conditions in the interacting-case. These new conditions assure the absence of ghosts, though the usual off-shell Virasoro conditions do not hold. The same problems are also discussed in the dual pion and fermion models. On the basis of the conformal invariance in the string model of hadrons,t> we determine the interaction of the string with the external field. We shall see that the string is allowed to couple with the external field only at both end points of the string with arbitrary coupling constants (§ 3). Generators Ln .of the conformal transformation in the interacting case will be found;_ they satisfy the same conformal gauge algebra as Ln ~in the free case, i.e.,