共查询到20条相似文献,搜索用时 31 毫秒
1.
Chris Vuille 《General Relativity and Gravitation》2007,39(5):621-632
The Klein–Gordon equations are solved for the case of a plane-symmetric static massless scalar field in general relativity
with cosmological constant, generalizing the solutions found by Taub, Novotny and Horsky, and Singh. A separate class of solutions
is obtained in which the metrics reduce to flat space in the limit that .The static solutions can be used to generate time-dependent cosmological solutions, one of which exhibits rapid inflation
followed by continued exponential expansion at all later times. 相似文献
2.
A new parametrization of the 3-metric allows to find explicitly a York map by means of a partial Shanmugadhasan canonical
transformation in canonical ADM tetrad gravity. This allows to identify the two pairs of physical tidal degrees of freedom
(the Dirac observables of the gravitational field have to be built in term of them) and 14 gauge variables. These gauge quantities,
whose role in describing generalized inertial effects is clarified, are all configurational except one, the York time, i.e.
the trace of the extrinsic curvature of the instantaneous 3-spaces (corresponding to a clock synchronization convention) of a non-inertial frame centered on an arbitrary observer. In the Dirac Hamiltonian is the sum of the weak ADM energy (whose density is coordinate-dependent, containing the inertial potentials) and of the first-class constraints. The main results of the
paper, deriving from a coherent use of constraint theory, are: (i) The explicit form of the Hamilton equations for the two
tidal degrees of freedom of the gravitational field in an arbitrary gauge: a deterministic evolution can be defined only in
a completely fixed gauge, i.e. in a non-inertial frame with its pattern of inertial forces. The simplest such gauge is the
3-orthogonal one, but other gauges are discussed and the Hamiltonian interpretation of the harmonic gauges is given. This
frame-dependence derives from the geometrical view of the gravitational field and is lost when the theory is reduced to a
linear spin 2 field on a background space-time. (ii) A general solution of the super-momentum constraints, which shows the
existence of a generalized Gribov ambiguity associated to the 3-diffeomorphism gauge group. It influences: (a) the explicit
form of the solution of the super-momentum constraint and then of the Dirac Hamiltonian; (b) the determination of the shift
functions and then of the lapse one. (iii) The dependence of the Hamilton equations for the two pairs of dynamical gravitational
degrees of freedom (the generalized tidal effects) and for the matter, written in a completely fixed 3-orthogonal Schwinger
time gauge, upon the gauge variable , determining the convention of clock synchronization. The associated relativistic inertial effects, absent in Newtonian
gravity and implying inertial forces changing from attractive to repulsive in regions with different sign of , are completely unexplored and may have astrophysical relevance in the interpretation of the dark side of the universe. 相似文献
3.
C. F. C. Brandt R. Chan M. A. F. da Silva Jaime F. Villas da Rocha 《General Relativity and Gravitation》2007,39(10):1675-1687
We study the evolution of an inhomogeneous fluid with self-similarity of the second kind and anisotropic pressure. We found
a class of solution to the Einstein field equations by assuming an equation of state where the radial pressure of the fluid
is proportional to its energy density () and that the fluid moves along time-like geodesics. The equation of state combined with the self-similarity of second kind
implies ω = −1. The energy conditions, geometrical and physical properties of the solutions are studied. We have found that,
for the self-similar parameter , the solution represents an accelerated cosmological model ending in a Big Rip stage. 相似文献
4.
Varsha Daftardar-Gejji 《General Relativity and Gravitation》1998,30(5):695-700
Brinkmann has shown that conformally related Einstein spaces are either Ricci flat pp-waves or conformally flat spaces with one as de Sitter space and the other being flat. We herewith show that if gikand
are distinct metrics for which
, then both represent (generalised) pp-waves; and w,iis a homothetic conformal Killing vector of gik. It is further observed that in the situation
we can have many (and also non-conformally flat) conformally related solutions, unlike in Einstein spaces. In particular for perfect fluid coupling, we show that the conformally related solutions have to be Friedman-Robertson-Walker metrics with equation of state as
, or pp-waves depending on whether w,iis timelike, spacelike or null. 相似文献
5.
J. Ponce de Leon 《General Relativity and Gravitation》2006,38(1):61-81
Braneworld theory provides a natural setting to treat, at a classical level, the cosmological effects of vacuum energy. Non-static
extra dimensions can generally lead to a variable vacuum energy, which in turn may explain the present accelerated cosmic
expansion. We concentrate our attention in models where the vacuum energy decreases as an inverse power law of the scale factor.
These models agree with the observed accelerating universe, while fitting simultaneously the observational data for the density
and deceleration parameter. The redshift at which the vacuum energy can start to dominate depends on the mass density of ordinary
matter. For
m
= 0.3, the transition from decelerated to accelerated cosmic expansion occurs at z
T
≈ 0.48 ± 0.20, which is compatible with SNe data. We set a lower bound on the deceleration parameter today, namely > − 1 + 3
m
/2, i.e., > − 0.55 for
m
= 0.3. The future evolution of the universe crucially depends on the time when vacuum starts to dominate over ordinary matter.
If it dominates only recently, at an epoch z < 0.64, then the universe is accelerating today and will continue that way forever. If vacuum dominates earlier, at z > 0.64, then the deceleration comes back and the universe recollapses at some point in the distant future. In the first case,
quintessence and Cardassian expansion can be formally interpreted as the low energy limit of our model, although they are
entirely different in philosophy. In the second case there is no correspondence between these models and ours. 相似文献
6.
Tadayoshi Adachi 《Letters in Mathematical Physics》2007,82(1):1-8
For an N-body Stark Hamiltonian , the resolvent estimate holds uniformly in with Re and Im , where , and is a compact interval. This estimate is well known as the limiting absorption principle. In this paper, we report that by
introducing the localization in the configuration space, a refined resolvent estimate holds uniformly in with Re and Im .
Dedicated to Professor Hideo Tamura on the occasion of his 60th birthday 相似文献
7.
A zero modes’ Fock space is constructed for the extended chiral WZNW model. It gives room to a realization of the fusion ring of representations of the restricted quantum universal enveloping
algebra at an even root of unity, and of its infinite dimensional extension by the Lusztig operators We provide a streamlined derivation of the characteristic equation for the Casimir invariant from the defining relations
of A central result is the characterization of the Grothendieck ring of both and in Theorem 3.1. The properties of the fusion ring in are related to the braiding properties of correlation functions of primary fields of the conformal current algebra model.
相似文献
8.
Consider in the operator family . P
0 is the quantum harmonic oscillator with diophantine frequency vector ω, F
0 a bounded pseudodifferential operator with symbol decreasing to zero at infinity in phase space, and . Then there exist independent of and an open set such that if and , the quantum normal form near P
0 converges uniformly with respect to . This yields an exact quantization formula for the eigenvalues, and for the classical Cherry theorem on convergence of Birkhoff’s normal form for complex frequencies is recovered.
Partially supported by PAPIIT-UNAM IN106106-2. 相似文献
9.
Dyson’s Constants in the Asymptotics of the Determinants of Wiener-Hopf-Hankel Operators with the Sine Kernel 总被引:1,自引:1,他引:0
Torsten Ehrhardt 《Communications in Mathematical Physics》2007,272(3):683-698
Let stand for the integral operators with the sine kernels acting on L
2[0,α]. Dyson conjectured that the asymptotics of the Fredholm determinants of are given by
as α→∞. In this paper we are going to give a proof of these two asymptotic formulas. 相似文献
10.
The relationship between cosmological solutionsof five-dimensional Space-Time-Matter (STM) theory anda Generalized Scalar-Tensor (GST) theory is investigatedin which the cosmological term Lambda depends not only on a scalar field but also onits time derivative
.Identification of these solutions allows us to solve forthe functional form of the cosmological term, and mayhave relevance for the early Universe. 相似文献
11.
Asao Arai 《Letters in Mathematical Physics》2007,80(3):211-221
Let H be a self-adjoint operator on a complex Hilbert space . A symmetric operator T on is called a time operator of H if, for all , (D(T) denotes the domain of T) and . In this paper, spectral properties of T are investigated. The following results are obtained: (i) If H is bounded below, then σ(T), the spectrum of T, is either (the set of complex numbers) or . (ii) If H is bounded above, then is either or . (iii) If H is bounded, then . The spectrum of time operators of free Hamiltonians for both nonrelativistic and relativistic particles is exactly identified.
Moreover spectral analysis is made on a generalized time operator.
This work is supported by the Grant-in-Aid No.17340032 for Scientific Research from the JSPS. 相似文献
13.
We have quantized a flat cosmological model in the context of the metric models, using the causal Bohmian quantum theory. The equations are solved and then we have obtained how the quantum corrections
influence the classical equations. 相似文献
14.
Asit Banerjee Tanwi Bandyopadhyay Subenoy Chakraborty 《General Relativity and Gravitation》2008,40(8):1603-1607
A model of an emergent universe is obtained in brane world. Here the bulk energy is in the form of cosmological constant,
while the brane consists of a fluid satisfying an equation of state of the form , which is effectively a radiation equation of state at high energies. It is shown that with the positive bulk cosmological
constant, one of our models represents an emergent universe. 相似文献
15.
On the Ricci Curvature of Compact Spacelike Hypersurfaces in Einstein Conformally Stationary-Closed Spacetimes 总被引:1,自引:0,他引:1
In this paper we develop an integral formula involving the Ricci and scalar curvatures of a compact spacelike hypersurface M in a spacetime
equipped with a timelike closed conformal vector field K (in short, conformally stationary-closed spacetime), and we apply it, when
is Einstein, in order to establish sufficient conditions for M to be a leaf of the foliation determined by K and to obtain some non-existence results. We also get some interesting consequences for the particular case when
is a generalized Robertson-Walker spacetime. 相似文献
16.
G. S. Khadekar Rupali Wanjari Cenap Ozel 《International Journal of Theoretical Physics》2009,48(9):2550-2557
In this study we have analyzed the Kaluza-Klein type Robertson Walker (RW) cosmological model by considering variable cosmological
constant term Λ of the form:
,
and Λ∼ρ in the presence of strange quark matter with domain wall. The various physical aspects of the model are also discussed. 相似文献
17.
Jonathan Weitsman 《Communications in Mathematical Physics》2008,277(1):101-125
We show how to construct measures on Banach manifolds associated to supersymmetric quantum field theories. These measures
are mathematically well-defined objects inspired by the formal path integrals appearing in the physics literature on quantum
field theory. We give three concrete examples of our construction. The first example is a family of measures on a space of functions on the two-torus, parametrized by a polynomial P (the Wess-Zumino-Landau-Ginzburg model). The second is a family of measures on a space of maps from to a Lie group (the Wess-Zumino-Novikov-Witten model). Finally we study a family of measures on the product of a space of connections on the trivial principal bundle with structure group G on a three-dimensional manifold M with a space of -valued three-forms on M.
We show that these measures are positive, and that the measures are Borel probability measures. As an application we show that formulas arising from expectations in the measures reproduce formulas discovered by Frenkel and Zhu in the theory of vertex operator algebras. We conjecture that a similar
computation for the measures , where M is a homology three-sphere, will yield the Casson invariant of M.
Dedicated to the memory of Raoul Bott
Supported in part by NSF grant DMS 04/05670. 相似文献
18.
A Strong Szegő Theorem for Jacobi Matrices 总被引:1,自引:1,他引:0
E. Ryckman 《Communications in Mathematical Physics》2007,271(3):791-820
We use a classical result of Golinskii and Ibragimov to prove an analog of the strong Szegő theorem for Jacobi matrices on
. In particular, we consider the class of Jacobi matrices with conditionally summable parameter sequences and find necessary
and sufficient conditions on the spectral measure such that and lie in , the linearly-weighted l
2 space.
An erratum to this article can be found at 相似文献
19.
D. Eriksson S. Hesselbach J. Rathsman 《The European Physical Journal C - Particles and Fields》2008,53(2):267-280
We investigate the viability of observing charged Higgs bosons () produced in association with bosons at the CERN large hadron collider, using the leptonic decay and hadronic decay, within different scenarios of the minimal supersymmetric standard model (MSSM) with both real and complex parameters.
Performing a parton level study we show how the irreducible standard model background from jets can be controlled by applying appropriate cuts and find that the size of a possible signal depends on the cuts needed
to suppress QCD backgrounds and misidentifications. In the standard maximal mixing scenario of the MSSM we find a viable signal
for large and intermediate masses () when using softer cuts (, 50 GeV), whereas for harder cuts (, 100 GeV) we only find a viable signal for very large (). We have also investigated a special class of MSSM scenarios with large mass splittings among the heavy Higgs bosons where
the cross-section can be resonantly enhanced by factors up to one hundred, with a strong dependence on the -violating phases. Even so we find that the signal after cuts remains small except for small masses () when using the softer cuts. Finally, in all the scenarios we have investigated we have only found small -asymmetries. 相似文献
20.
Quantum Conjugacy Classes of Simple Matrix Groups 总被引:1,自引:0,他引:1
A. Mudrov 《Communications in Mathematical Physics》2007,272(3):635-660
Let G be a simple complex classical group and its Lie algebra. Let be the Drinfeld-Jimbo quantization of the universal enveloping algebra . We construct an explicit -equivariant quantization of conjugacy classes of G with Levi subgroups as the stabilizers.
Dedicated to the memory of Joseph Donin
This research is partially supported by the Emmy Noether Research Institute for Mathematics, the Minerva Foundation of Germany,
the Excellency Center “Group Theoretic Methods in the study of Algebraic Varieties” of the Israel Science foundation, by the
EPSRC grant C511166, and by the RFBR grant no. 06-01-00451. 相似文献