Absorption and quasinormal modes of classical fields propagating on 3D and 4D de Sitter spacetime

We extensively study the exact solutions of the massless Dirac equation in 3D de Sitter spacetime that we published recently. Using the Newman-Penrose formalism, we find exact solutions of the equations of motion for the massless classical fields of spin s= 12,1,2 and to the massive Dirac equation in 4D de Sitter metric. Employing these solutions, we analyze the absorption by the cosmological horizon and de Sitter quasinormal modes. We also comment on the results given by other authors.     

高维de Sitter时空中宇宙视界处的Fermi子隧穿

运用半经典近似理论,本文研究了来自静态高维de Sitter时空和高维Schwarzschild-de Sitter时空宇宙视界处的Fermi子隧穿辐射.在文中,描述1/2自旋粒子行为的Dirac方程被简化为一个简单的形式,接着运用方程组有非平凡解的条件,可以得到了半经典的Hamilton-Jacobi方程,从而使得问题大大得以简化,最终得到了静态de Sitter时空中宇宙视界处的Fermi子隧穿率和Hawking温度.     

高维de Sitter时空中宇宙视界处的Fermi子隧穿

运用半经典近似理论,本文研究了来自静态高维deSitter时空和高维Schwarzschild-de Sitter时空宇宙视界处的Fermi子隧穿辐射.在文中,描述1/2自旋粒子行为的Dirac方程被简化为一个简单的形式,接着运用方程组有非平凡解的条件,可以得到了半经典的Hamilton-Jacobi方程,从而使得问题大大得以简化,最终得到了静态de Sitter时空中宇宙视界处的Fermi子隧穿率和Hawking温度.     

Schwarzchild-de Sitter 黑洞的热力学性质

在考虑黑洞视界与宇宙视界具有关联性的基础上,证明de Sitter时空的热力学熵为黑洞视界热力学熵与宇宙视界热力学熵之和.给出了考虑两视界具有关联性后的de Sitter时空的热力学特性.研究表明,de Sitter时空的能量上限为纯de Sitter时空能量,deSitter时空的热容量是负的,de Sitter时空一般是量子力学不稳定的.     

Dirac quasinormal modes of <Emphasis Type="Italic">D</Emphasis>-dimensional de Sitter spacetime

We find exact solutions to the Dirac equation in D-dimensional de Sitter spacetime. Using these solutions we analytically calculate the de Sitter quasinormal (QN) frequencies of the Dirac field. For the massive Dirac field this computation is similar to that previously published for massive fields of half-integer spin moving in four dimensions. However to calculate the QN frequencies of the massless Dirac field we must use distinct methods in odd and even dimensions, therefore the computation is different from that already known for other massless fields of integer spin.     

The Cardy-Verlinde formula and entropyof topological Kerr- Newman black holes in de Sitter spaces

In this paper we show that the entropy of a cosmological horizon in 4-dimensional topological Kerr-Newman-de Sitter spaces can be described by the Cardy-Verlinde formula, which is supposed to be an entropy formula of conformal field theory in any number of dimensions. Furthermore, we find that the entropy of a black hole horizon can also be rewritten in terms of the Cardy-Verlinde formula for these black holes in de Sitter spaces, if we use the definition due to Abbott and Deser for conserved charges in asymptotically de Sitter spaces. Such results presume a well-defined dS/CFT correspondence, which has not yet attained the credibility of its AdS analogue.Received: 7 April 2003, Revised: 18 June 2003, Published online: 29 August 2003     

Anomalies and Hawking Radiation of NUT-Kerr-Newman de Sitter Black Hole

Hawking radiation of NUT-Kerr-Newman de Sitter black hole is studied via anomalous point of view in this paper. The results show that the charged current and energy-momentum tensor fluxes, to restore gauge invariance and general coordinate covariance at the quantum level in the effective field theory, are exactly equal to those of Hawking radiation from the event horizon (EH) and the cosmological horizon (CH) of NUT-Kerr-Newman de Sitter black hole, respectively.     

Dirac’s Equation in R-Minkowski Spacetime

We recently constructed the R-Poincaré algebra from an appropriate deformed Poisson brackets which reproduce the Fock coordinate transformation. We showed then that the spacetime of this transformation is the de Sitter one. In this paper, we derive in the R-Minkowski spacetime the Dirac equation and show that this is none other than the Dirac equation in the de Sitter spacetime given by its conformally flat metric. Furthermore, we propose a new approach for solving Dirac’s equation in the de Sitter spacetime using the Schrödinger picture.     

Kerr-Newman-De Sitter时空中的Dirac方程的退耦和分离变量

本文给出了Kerr-Newman-De Sitter时空中的Dirac方程的退耦和分离变量,并在Kerr-Newman-De Sitter时空的视界附近通过适当的变换找到了静止质量不为零的Dirac方程的有物理意义的解,导出了Hawking热谱公式,从而解决了Dirac粒子在Kerr-Newman-De Sitter黑洞背景下的Hawking蒸发问题。 关键词：     

Neutrino Tunneling from NUT Kerr Newman de Sitter Black Hole

In this paper, the method of semi-classical is applied to explore the Hawking radiation of a NUT-Kerr-Newman de Sitter Black Hole from tunneling point of view. The Hamilton-Jacobi equation in NUT-Kerr-Newman de Sitter space time is derived by the method presented by Lin and Yang (Chin. Phys. B, 20:110403, 2011). We obtain the Hawking temperatures at the event horizon and cosmological horizon and we also obtain the tunneling probability of neutrino following the semi-classical quantum equation. The results show the common features of NUT-Kerr-Newman de Sitter Black Hole.     

Localization of five-dimensional Elko spinors on dS/AdS thick branes

Owing to the special structure of a five-dimensional Elko spinor, its localization on a brane with codimension one becomes completely different from that of a Dirac spinor. By introducing the coupling between the Elko spinor and the scalar field that can generate the brane, we have two types of localization mechanism for the five-dimensional Elko spinor zero mode on a brane. One is the Yukawa-type coupling, and the other is the non-minimal coupling. In this study, we investigate the localization of the Elko zero mode on de Sitter and Anti-de Sitter thick branes with the two localization mechanisms, respectively. The results show that both the mechanisms can achieve localization. The forms of the scalar coupling function in both localization mechanisms have similar properties, and they play a similar role in localization.     

Hawking Radiation from Horizons of Reissner-Nordström de Sitter Black Hole with a Global Monopole via Anomalies

Hawking radiation from cosmological horizon and event horizon of the Reissner-Nordström de Sitter black hole with a global monopole is studied via a new method that was propounded by Robinson and Wilzek and elaborated by Banerjee and Kulkarni. The results show that the gauge current and energy-momentum tensor fluxes, which required keeping gauge covariance and general coordinate invariance at the quantum level in the effective field theory, are exactly equivalent to those of Hawking radiation from the event horizon and the cosmological horizon, respectively.     

Unruh–DeWitt Detectors in Spherically Symmetric Dynamical Space-Times

In the present paper, Unruh–DeWitt detectors are used in order to investigate the issue of temperature associated with a spherically symmetric dynamical space-times. Firstly, we review the semi-classical tunneling method, then we introduce the Unruh–DeWitt detector approach. We show that for the generic static black hole case and the FRW de Sitter case, making use of peculiar Kodama trajectories, semiclassical and quantum field theoretic techniques give the same standard and well known thermal interpretation, with an associated temperature, corrected by appropriate Tolman factors. For a FRW space-time interpolating de Sitter space with the Einstein–de Sitter universe (that is a more realistic situation in the frame of ΛCDM cosmologies), we show that the detector response splits into a de Sitter contribution plus a fluctuating term containing no trace of Boltzmann-like factors, but rather describing the way thermal equilibrium is reached in the late time limit. As a consequence, and unlike the case of black holes, the identification of the dynamical surface gravity of a cosmological trapping horizon as an effective temperature parameter seems lost, at least for our co-moving simplified detectors. The possibility remains that a detector performing a proper motion along a Kodama trajectory may register something more, in which case the horizon surface gravity would be associated more likely to vacuum correlations than to particle creation.     

The physical meaning of the de Sitter invariants

We study the Lie algebras of the covariant representations transforming the matter fields under the de Sitter isometries. We point out that the Casimir operators of these representations can be written in closed forms and we deduce how their eigenvalues depend on the field’s rest energy and spin. For the scalar, vector and Dirac fields, which have well-defined field equations, we express these eigenvalues in terms of mass and spin obtaining thus the principal invariants of the theory of free fields on the de Sitter spacetime. We show that in the flat limit we recover the corresponding invariants of the Wigner irreducible representations of the Poincaré group.     

Hawking Radiation from the Higher-Dimensional Schwarzschild de Sitter and Anti-de Sitter Black Holes via Covariant Anomaly

Very recently, a conceptually clean and economical anomaly cancellation method, based on the initial work of Robinson and Wilczek, on Hawking radiation was proposed. On the basis of this formalism, we investigate Hawking radiation from the higher dimensional Schwarzschild de Sitter and Anti-de Sitter black holes. To describe the observable physics in de Sitter space, we construct the effective field theory between the event horizon and cosmological horizon. Our result shows that when the underlying diffeomorphism symmetries are saved at the quantum level, Hawking radiation, from not only the event horizon but also the cosmological horizon in the higher dimensional space time, can be determined by the covariant compensating fluxes of energy momentum tensor. Meanwhile, we also discuss the exact radiation spectrum by incorporating the self-gravitational interaction and back reaction of the outgoing modes.     

On thermodynamics of RN-dS black hole surrounded by the quintessence

De Sitter black holes have the black hole horizon and the cosmological horizon, and the thermodynamic quantities on the two horizons all satisfy the first law of thermodynamics. The thermodynamic quantities on the two horizons are not independent but are correlated to each other. Taking de Sitter space-time as thermodynamic system, we investigated the effective thermodynamic quantities of Reissner–Nordström de Sitter black hole surrounded by the quintessence (RN-DSQ). We obtained the effective temperature and entropy of the system by considering the corrections between the black hole horizon and the cosmological horizon. We found that the entropy of the RN-DSQ is in agreement with that of Reissner–Nordström de Sitter black hole. It offers a basis for further studying of the thermodynamic properties of de Sitter space-time.     

Klein–Gordon and Dirac Equations in de Sitter Space–Time

We present and discuss the Klein–Gordonand Dirac wave equations in the de Sitter universe. Toobtain the Dirac wave equation we use the factorizationof the second-order invariant Casimir operatorassociated to the Fantappie–de Sitter group. Boththe Klein–Gordon and Dirac wave equations arediscussed in terms of the spherical harmonics with spinweight. A particular case of Dirac wave equation issolved in terms of a new class of polynomials.     

Asymmetry of Hawking Radiation of Dirac Particles in a Charged Vaidya–de Sitter Black Hole

The Hawking radiation of Dirac particles in a charged Vaidya–de Sitter black hole is investigated by using the method of generalized tortoise coordinate transformation. It is shown that the Hawking radiation of Dirac particles does not exist for P₁, Q₂ components, but for P₂, Q₁ components it does. Both the location and the temperature of the event horizon change with time. The thermal radiation spectrum of Dirac particles is the same as that of Klein-Gordon particles.     

Entropy of the Dirac Field in Schwarzschild–de Sitter Space-Time via the Membrane Model

There are two event horizons in Schwarzschild–de Sitter space-time, a blackhole horizon and a cosmological horizon. They have different temperatures. Theradiation between them is of course not in thermal equilibrium. According to themembrane model suggested by us, the two horizons can be thought of as twoindependent thermodynamic systems in equilibrium. Their Dirac field entropiesare calculated via a membrane model. The result shows that the entropy of theDirac field is proportional to the sum of the areas of the two event horizons. Ifwe choose the same cutoff as that of Klein–Gordon field, the entropy of theDirac field is times that of Klein–Gordon field. This agrees with previousresults.     

Some classical solutions of the sourceless SO(4,1) gauge field equations

Some new classical solutions of the sourceless SO(4,1) gauge field equations are found by identifying the internal symmetry indices with the space-time indices as in the cases of the instanton or the meron solutions. This identification of the internal and the space-time indices takes the simplest form when the gauge field equation is expressed in (4,1) de Sitter space, which is conformal to the Minkowski space having the de Sitter group SO(4,1) as a group of motions. The form of the solutions is close to the de Sitter ‘plane wave’ solutions found recently, i.e. the solutions of the Klein-Gordon, Dirac and Maxwell-Proca equations in de Sitter space. The group theoretical structure of the new solutions is discussed and their relations to the Iwasawa decomposition of the non-compact semisimple group SO(4,1) are pointed out.