14122115
Bubbles created from vacuum fluctuation
We show that the bubbles S ×S2can be created from vacuum fluctuation in certain De Sitter universe, so the space-time foam-like structure might really be constructed from bubbles of S × S in the very early inflating phase of our universe. But whether such foam-like structure persisted during the later evolution of the universe is a problem unsolved now. PACS: 04.20.Gz, 04.60.Ds Typeset using REVTEX Supported by the National Natural Science Foundation of China under No. 19473005, and the Education Committee of Hunan Province. Email address: liaoliu@class1.bao.ac.cn or fhedoc@263.net 1 J.A.Wheeler was the first one who pointed out that the space-time might have a foam-like structure around the Plank scale [1],though it is simply connected and smooth at large scale. But what is the constituents of the space-time foam is a problem long unsolved. Hawking himself oscillated between the wormhole pictured and bubble pictured foam-like structure [2].However according to our point of view, the essential point is whether the bubble or wormhole could be really solutions of the semi-classical Einstein gravitational equation Gμ = − 8πG c 〈0 | T ν μ | 0〉ren, (1) where Gμ = R ν μ − 1 2Rδν μ is the Einstein tensor of the bubbles or wormhole, 〈0 | T ν μ | 0〉ren is however the renormalized matter stress-energy tensor of vacuum fluctuation in certain given classical background space-time, G is gravitational constant, c is velocity of light. The signature in our paper is -2. Early in 1993, one of the authors (L.Liu) had found a transient Lorentzian wormhole solution [3] ds = d(ct) − l p cosh2(ct/lp)dΩ23, (2) where lp is the Planck length. From (1), this Lorentzian mini-wormhole creates at certain early time and annihilates later under vacuum fluctuation in a closed inflating de Sitter background space-time of metric ds = d(ct) − αedΩ 3 , (3) where α = √ 3/Λ, Λ is the cosmological constant of the background de Sitter universe. Now the problem is whether the Euclidean bubble S × S can also be a solution of the semiclassical Euclidean Einstein field equation (1)? As is known, the Euclidean metric of S2×S2 is the Nariai instanton of metric [4] ds = −λ(sin χd ψ2 +dχ + dΩ 2 ), (4) where ψ is the imaginary time and √ 1/λ is the radius of the 2-sphere S. λ in our paper is nothing to do with the so-called cosmological constant, though it is so in the degenerated De Sitter-Schwarzschild spacetime historically. The Lorentzian Nariai metric is [4] 2 ds = λ sin χdψ − λdχ − λdθ − λ sin θdφ), (5) where ψ = −i ψ is a real time variable. From the Lorentzian Nariai metric (5) and (1), the renormalized vacuum matter stressenergy tensor can be obtained straightforward as (Appendix) 〈0 | T ν μ | 0〉ren = − c 8πG Gμ = c 8πG λδ μ. (6) However expression (6) is just the well-known vacuum matter stress-energy tensor in one-loop approximation for scalar field [5] 〈0 | T ν μ | 0〉ren = h̄c 960πα δ μ = cΛl p 8640πG δ μ, (α ≡ √ 3 Λ , Λ is the cosmological constant). (7) of the inflating flat de Sitter universe ds = d(ct) − e 2ct α dxdxi (8) or the inflating closed de Sitter universe ds = d(ct) − α cosh(ct/α)dΩ 3 (9)
16924371
The cosmological origin of Higgs particles
A proposal of the cosmological origin of Higgs particles is given. We show, that the Higgs field could be created from the vacuum quantum conformal fluctuation of Anti-de Sitter space-time, the spontaneous breaking of vacuum symmetry, and the mass of Higgs particle are related to the cosmological constant of our universe,especially the theoretical estimated mass m$_{H}$ of Higgs particles is m$_{H}=\sqrt{-2\mu ^{2}}$ =$\sqrt{|\Lambda /\pi}$.
120532477
Thermodynamics of de Sitter universes
It is shown that the first law of thermodynamics can be applied to the de Sitter universe to relate its vacuum energy, pressure, entropy of horizon, chemical potential, etc., when the cosmological constant changes due to the fluctuation of the vacuum or other reasons. The second law should be reformulated in the form that the spontaneous decay of the vacuum never makes the entropy of the de Sitter universe decrease. The third law of thermodynamics, applying to the de Sitter universe, implies that the cosmological constant cannot reach zero by finite physical processes. The relation to the holographic principle is also briefly discussed.
121055509
The quantum cosmology in the Brans-Dicke theory
In this paper, we try to establish the quantum cosmology based on the Brans-Dicke gravitational theory. The most remarkable property of it is that the scale factora(t) has a lower limit, where the cosmological wave function approaches zero.
120926032
Classical Instability of Anti-de Sitter Universe
This article discusses the gravitational stability of anti-de Sitter universe. It turns out that anti-de Sitter universe with closed timelike curves is unstable to gravitational perturbations.
120249108
Quantum-gravity interpretation of Brans-Cicke theory?the back-reaction of the vacuum matter field upon the Einstein space-time
A quantum gravity version is given to the Brans-Dicke theory. We find that the matter field quantum fluctuation induces the conformal quantum fluctuation of space-time, and that the latter backreacts to the classical space-time and transforms it from Einstein space-time into the Brans-Dicke one.
119221894
Holographic renormalization in no-boundary quantum cosmology
Recent results of Hartle-Hawking wave functions on asymptotic dS boundaries show non-normalizability, while the bulk origin is not clear. This paper attempts to addresse this problem by studying (Kerr-)dS_3 cosmology in Einstein gravity deformed by a minimally coupled scalar field. Various saddle-point contributions exp[i(saddle-point action)] to the Hartle-Hawking wave functions are computed with mini-superspace formalism. The saddle-point actions are first obtained in the spacetime bulks by direct computation, then on the asymptotic dS boundary by holographic renormalization. It is found that the imaginary part of the saddle-point actions, as functions of scalar field deformation, are generally bounded in the bulk, but can diverge to -infty on the boundary. This can probably be a source of the scalar field-related non-normalizability of the boundary Hartle-Hawking wave functions. For Kerr-dS_3 cosmology, some saddle-point actions have imaginary parts diverging to -infty both in the bulk and on the boundary, when the boundary T^2 is stretched to infinitely long. This can be an origin of non-normalizability of the boundary Hartle-Hawking wave functions related to temperature divergence. Finally the holographic renormalization is extended to scalar-deformed dS_{d+1} (d>= 3) cosmologies for the imaginary part of the saddle-point actions. The result is tested on a 5d example, and saddle points leading to divergent contribution to the boundary Hartle-Hawking wave function are shown to exist.
119684494
New results for charmonium spectroscopy from lattice QCD
We study the charmonium spectrum in full QCD on anisotropic lattices generated by Hadron Spectrum Collaboration. We adopt a large basis of interpolating operators to extract the excited charmonium states using the variational method. A detailed spectrum of excited charmonium mesons in many JPC channels is obtained. Some exotic hybrid states (with JPC = 0+−, 2−+) are also studied.
118644408
Topological limit of gravity admitting an SU(2) connection formulation
We study the Hamiltonian formulation of the generally covariant theory defined by the Lagrangian 4-form L=e{sub I} and e{sub J} and F{sup IJ}({omega}), where e{sup I} is a tetrad field and F{sup IJ} is the curvature of a Lorentz connection {omega}{sup IJ}. This theory can be thought of as the limit of the Holst action for gravity for the Newton constant G{yields}{infinity} and Immirzi parameter {gamma}{yields}0, while keeping the product G{gamma} fixed. This theory has for a long time been conjectured to be topological. We prove this statement both in the covariant phase space formulation as well as in the standard Dirac formulation. In the time gauge, the unconstrained phase space of theory admits an SU(2) connection formulation which makes it isomorphic to the unconstrained phase space of gravity in terms of Ashtekar-Barbero variables. Among possible physical applications, we argue that the quantization of this topological theory might shed new light on the nature of the degrees of freedom that are responsible for black entropy in loop quantum gravity.
39191409
Charmonium spectroscopy from an anisotropic lattice study
We present a progress report on our study of the charmonium spectrum in full QCD on anisotropic lattices generated by the Hadron Spectrum Collaboration. We adopt a large basis of interpolating operators to extract the excited charmonium states using the variational method. A detailed spectrum of excited charmonium mesons in many J PC channels is obtained. Hybrid states with exotic and non-exotic quantum numbers are determined and preliminary results from a study of disconnected contributions to the hc are presented.
119199648
Renormalization Invariants and Quark Flavor Mixings
A set of renormalization invariants is constructed using approximate, two-flavor, analytic solutions to RGE's. These invariants exhibit explicitly the correlation between quark flavor mixings and mass ratios from electroweak scale to GUT scale in the context of the SM, DHM and MSSM models. The well-known empirical relations θ23 ∝ ms/mb, θ13 ∝ md/mb at electroweak scale can thus be understood as the result of renormalization evolution toward the infrared point. The validity of this approximation is evaluated by comparing the numerical solutions with the analytical approach. It is found that the scale dependence of these quantities for general three-flavor mixing follows closely these invariants up to the GUT scale.