arXiv subjects

Ji-Rong Ren

Publications and source records attributed to Ji-Rong Ren.

At least 37 records · Page 2Linked to original sources

arXiv2009

Corrected entropy of high dimensional black holes

Using the corrected expression of Hawking temperature derived from the tunneling formalism beyond semiclassical approximation developed by \emph{Banerjee} and \emph{Majhi}\cite{beyond}, we calculate the corrected entropy of a high dimensional Schwarzschild black hole and a 5-dimensional Gauss-Bonnet (GB) black hole. It is shown that the corrected entropy for this two kinds of black hole are in agreement with the corrected entropy formula (\ref{entropy of apparent horiozn}) that derived from tunneling method for a $(n+1)$-dimensional Friedmann-Robertson-Walker (FRW) universe\cite{FRW}. This feature strongly suggests deep universality of the corrected entropy formula (\ref{entropy of apparent horiozn}), which may not depend on the dimensions of spacetime and gravity theories. In addition, the leading order correction of corrected entropy formula always appears as the logarithmic of the semiclassical entropy, rather than the logarithmic of the area of black hole horizon, this might imply that the logarithmic of the semiclassical entropy is more appropriate for quantum correction than the logarithmic of the area.

hep-th↗

arXiv2009

Series expansion in fractional calculus and fractional differential equations

Fractional calculus is the calculus of differentiation and integration of non-integer orders. In a recently paper (Annals of Physics 323 (2008) 2756-2778), the Fundamental Theorem of Fractional Calculus is highlighted. Based on this theorem, in this paper we introduce fractional series expansion method to fractional calculus. We define a kind of fractional Taylor series of an infinitely fractionally-differentiable function. Further, based on our definition we generalize hypergeometric functions and derive corresponding differential equations. For finitely fractionally-differentiable functions, we observe that the non-infinitely fractionally-differentiability is due to more than one fractional indices. We expand functions with two fractional indices and display how this kind of series expansion can help to solve fractional differential equations.

math-ph↗

arXiv2009

Anomaly analysis of Hawking radiation from Kaluza-Klein black hole with squashed horizon

Considering gravitational and gauge anomalies at the horizon, a new method that to derive Hawking radiations from black holes has been developed by Wilczek et al. In this paper, we apply this method to non-rotating and rotating Kaluza-Klein black holes with squashed horizon, respectively. For the rotating case, we found that, after the dimensional reduction, an effective U(1) gauge field is generated by an angular isometry. The results show that the gauge current and energy-momentum tensor fluxes are exactly equivalent to Hawking radiation from the event horizon.

hep-th↗

arXiv2009

Causal diffusions, causal Zeno effect and collision number

We consider diffusion processes with the help of Markov random walk models. Especially the process of diffusion of a relativistic particle in a relativistic equilibrium system is considered. We interpret one of the results as causal Zeno effect for its similarity to quantum Zeno effect. Another problem we considered is about collision number. Basing on our numerical results, we propose that in the considered situation the probability density distribution among different collision numbers is a lognormal distribution.

cond-mat.stat-mech↗

arXiv2009

Fermion Resonances on Multi-field Thick Branes

Motivated by the recent work on the fermion resonances on scalar-constructed thick branes (arXiv:0901.3543 and arXiv:0904.1785), we extend the idea to multi-scalar generated thick branes and complete previous work. The fermion localization and resonances on the three-field and two-field thick branes are investigated. With the Numerov method, our numerical results show that the resonance states also exist in the brane besides the single-field thick branes and the two-field thick branes in the former cases. This interesting phenomenon is related to the internal structure of the brane and the coupling of fermions and scalars. We find that the Kaluza-Klein chiral decomposition of massive fermion resonances is the parity-chiral decomposition. For the couplings $η\barΨϕ^{k}χρΨ$ and $η\barΨϕ^{k}χρΨ$ for three-field and two-field models with odd positive $k$, respectively, the number of the resonant states decreases with $k$. This result is opposite to the one obtained in the single-field de Sitter thick brane (arXiv:0904.1785).

hep-th↗

arXiv2009

Corrected Entropy of Friedmann-Robertson-Walker Universe in Tunneling Method

In this paper, we study the thermodynamic quantities of Friedmann-Robertson-Walker (FRW) universe by using the tunneling formalism beyond semiclassical approximation developed by \emph{Banerjee} and \emph{Majhi}\cite{beyond0}. For this we first calculate the corrected Hawking-like temperature on apparent horizon by considering both scalar particle and fermion tunneling. With this corrected Hawking-like temperature, the explicit expressions of the corrected entropy of apparent horizon for various gravity theories including Einstein gravity, Gauss-Bonnet gravity, Lovelock gravity, $f(R)$ gravity and scalar-tensor gravity, are computed. Our results show that the corrected entropy formula for different gravity theories can be written into a general expression (\ref{entropy-final}) of a same form. It is also shown that this expression is also valid for black holes. This might imply that the expression for the corrected entropy derived from tunneling method is independent of gravity theory, spacetime and dimension of the spacetime. Moreover, it is concluded that the basic thermodynamical property that the corrected entropy on apparent horizon is a state function is satisfied by the FRW universe.

hep-th↗

arXiv2009

Corrections to Hawking-like Radiation for a Friedmann-Robertson-Walker Universe

Recently, a Hamilton-Jacobi method beyond semiclassical approximation in black hole physics was developed by \emph{Banerjee} and \emph{Majhi}\cite{beyond0}. In this paper, we generalize their analysis of black holes to the case of Friedmann-Robertson-Walker (FRW) universe. It is shown that all the higher order quantum corrections in the single particle action are proportional to the usual semiclassical contribution. The corrections to the Hawking-like temperature and entropy of apparent horizon for FRW universe are also obtained. In the corrected entropy, the area law involves logarithmic area correction together with the standard inverse power of area term.

hep-th↗

arXiv2009

Thermodynamics of Friedmann Equation and Masslike Function in General Braneworld

Using the generalized procedure proposed by \emph{Wu et al}\cite{wu} recently, we construct the first law of thermodynamics on apparent horizon in a general braneworld model with curvature correction terms on the brane and in the bulk, respectively. The explicit entropy formulary of apparent horizon in the general braneworld is worked out. We also discuss the masslike function which associated with a new type first law of thermodynamics of the general braneworld in detail. We analyze the difference between the conventional thermodynamics and the new type thermodynamics on apparent horizon. At last, the discussions about the physical meanings of the masslike function have also been given.

gr-qc↗

arXiv2009

Explicit field realizations of W algebras

The fact that certain non-linear $W_{2,s}$ algebras can be linearized by the inclusion of a spin-1 current can provide a simple way to realize $W_{2,s}$ algebras from linear $W_{1,2,s}$ algebras. In this paper, we first construct the explicit field realizations of linear $W_{1,2,s}$ algebras with double-scalar and double-spinor, respectively. Then, after a change of basis, the realizations of $W_{2,s}$ algebras are presented. The results show that all these realizations are Romans-type realizations.

hep-th↗

arXiv2009

Anomaly analysis of Hawking radiation from 2+1 dimensional spinning black hole

Considering gravitational and gauge anomalies at the horizon, a new successful method that to derive Hawking radiations from black holes has been developed recently by Wilczek et al.. By using the dimensional reduction technique, we apply this method to a non-vacuum solution, the 2+1 dimensional spinning black hole. The Hawking temperature and angular velocity on the horizon are obtained. The results may partially imply that this method is independent of the gravity theory, the dimension of spacetime and the topological structure of the event horizon.

hep-th↗

arXiv2009

Topological aspect of disclinations in two-dimensional melting

By using topological current theory, we study the inner topological structure of disclinations during the melting of two-dimensional systems. From two-dimensional elasticity theory, it is found topological currents for topological defects in homogeneous equation. The evolution of disclinations is studied, and the branch conditions for generating, annihilating, crossing, splitting, and merging of disclinations are given.

cond-mat.soft↗

arXiv2009

Physical States and BRST Operators for Higher-spin $W$ Strings

In this paper, we mainly investigate the $W_{2,s}^{M}\otimes W_{2,s}^{L}$ system, in which the matter and the Liouville subsystems generate $W_{2,s}^{M}$ and $W_{2,s}^L$ algebras respectively. We first give a brief discussion of the physical states for corresponding $W$ stings. The lower states are given by freezing the spin-2 and spin-$s$ currents. Then, introducing two pairs of ghost-like fields, we give the realizations of $W_{1,2,s}$ algebras. Based on these linear realizations, BRST operators for $W_{2,s}$ algebras are obtained. Finally, we construct new BRST charges of Liouville system for $W_{2,s}^{L}$ strings at the specific values of central charges $c$: $c=-{22/5}$ for $W_{2,3}^{L}$ algebra, $c=-24$ for $W_{2,4}^{L}$ algebra and $c=-2,-{286/3}$ for $W_{2,6}^{L}$ algebra, at which the corresponding $W_{2,s}^L$ algebras are singular.

hep-th↗

arXiv2009

Influence of Generalized and Extended Uncertainty Principle on Thermodynamics of FRW universe

The influence of the generalized uncertainty principle (GUP) and extended uncertainty principle (EUP) on the thermodynamics of the Friedmann-Robertson-Walker (FRW) universe has been investigated. It is shown that the entropy of the apparent horizon of the FRW universe gets a correction if one considers the effect of the GUP or EUP. Moreover, starting with the modified entropy and applying the first law of thermodynamics, $dE=TdS$, to the apparent horizon of the FRW universe, we obtain the modified Friedmann equations. The influence of the GUP or EUP on the thermodynamics of the FRW universe provides a deep insight into the understanding of the quantum gravity or large length scale corrections to the dynamics of the FRW universe.

hep-th↗

arXiv2009

Quantization of Black Hole Entropy from Quasinormal Modes

In Phys. Rev. D 78 (2008) 104018 [arXiv:0807.1481], the conclusion that "entropy eigenvalues of GB black hole are discrete and equally spaced, but the area spacing is not equidistant" was firstly presented by Kothawala, Padmanabhan and Sarkar. In this paper, using the new physical interpretation of quasinormal modes proposed by Maggiore, we calculate the quantum spectra of entropy for various types of non-rotating black holes with no charge. The spectrum is obtained by imposing Bohr-Sommerfeld quantization condition to the adiabatic invariant quantity. We conjecture that the spacing of entropy spectrum is equidistant and is independent of the dimension of spacetime. However, the spacing of area spectrum depends on gravity theory. In Einstein's gravity, it is equally spaced, otherwise it is non-equidistant. This conjecture agrees with the result of Kothawala, Padmanabhan and Sarkar.

hep-th↗

arXiv2008

Fermions Tunneling from Apparent Horizon of FRW Universe

In the paper [arXiv:0809.1554], the scalar particles' Hawking radiation from the apparent horizon of Friedmann-Robertson-Walker(FRW) universe was investigated by using the tunneling formalism. They obtained the Hawking temperature associated with the apparent horizon, which was extensively applied in investigating the relationship between the first law of thermodynamics and Friedmann equations. In this paper, we calculate Fermions' Hawking radiation from the apparent horizon of FRW universe via tunneling formalism. Applying WKB approximation to the general covariant Dirac equation in FRW spacetime background, the radiation spectrum and Hawking temperature of apparent horizon are correctly recovered, which supports the arguments presented in the paper [arXiv:0809.1554].

gr-qc↗

arXiv2008

Evolution of the Spiral Waves in Excitable System

Spiral wave, whose rotation center can be regarded as a point defect, widely exists in various two dimensional excitable systems. In this paper, by making use of \emph{Duan's topological current theory}, we obtain the charge density of spiral waves and the topological inner structure of its topological charge. The evolution of spiral wave is also studied from the topological properties of a two-dimensional vector field. The spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two-dimensional vector field. Some applications of our theory are also discussed.

nlin.PS↗

arXiv2008

The branch processes of vortex filaments and Hopf Invariant Constraint on Scroll Wave

In this paper, by making use of Duan's topological current theory, the evolution of the vortex filaments in excitable media is discussed in detail. The vortex filaments are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of a complex function $Z(\vec{x},t)$. It is also shown that the Hopf invariant of knotted scroll wave filaments is preserved in the branch processes (splitting, merging, or encountering) during the evolution of these knotted scroll wave filaments. Furthermore, it also revealed that the "exclusion principle" in some chemical media is just the special case of the Hopf invariant constraint, and during the branch processes the "exclusion principle" is also protected by topology.

nlin.PS↗

arXiv2008

The Bifurcation Theory of Magnetic Monopoles in a Charged Two-Condensate Bose-Einstein System

Magnetic monopoles, that are particle-like field configurations with which one can associate a topological charge, widely exist in various three dimensional condensate systems. In this paper, by making use of \emph{Duan}'s topological current theory, we obtain the charge density of magnetic monopoles and their bifurcation theory in a charged two condensate Bose-Einstein system. The evolution of magnetic monopoles is studied from the topological properties of a three-dimensional vector field. The magnetic monopoles are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points.

cond-mat.supr-con↗