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Ding-fang Zeng

Publications and source records attributed to Ding-fang Zeng.

At least 19 recordsLinked to original sources

Complementarity of Gravitation Collapse (II) XOB and the Damping Gravitational Waveform as Evidences

This is the second paper of our working series on the complementarity of gravitational collapse. In this paper we prove that dynamics of XOB (an eXact One-Body Method) under the weak-field-low-speed expansion matches with the post-newtonian series to all orders for the conservative part of binary dynamics in general relativity. Using XOB and an inner-structure modulated quadrupole formula, we generate gravitational waveforms for the black hole binary merger process agreeing with numeric relativity to 99\% degree. Basing on this agreement, we argue that black holes in numerical relativities have inner structures we propose in the complementarity of gravitational collapse.

gr-qc↗

Complementarity of Gravitational Collapse (I) Origin of the Bekenstein-Hawking Entropy

Through two exact solution families to Einstein equation and one-to-one correspondence between their free parameters, we show that the ensemble of collapsars with arbitrarily close-to-implementing horizon in the Schwarzschild time definition and the over-cross-oscillatory solid-ball ergodically experiencing all possible modes in the Lemaître time definition constitute two complementary description for the inner structure of black holes formed through gravitational collapse. As a support for this complementarity, we prove that the area law formula of Bekenstein-Hawking entropy by counting the degeneracy of collapsing material's wave functional directly. In two companion works, observational signals of this inner structure picture will be reported independently.

gr-qc↗

Quasinormal modes of Reissner-Nordström-AdS black holes under physical field-vanishing boundary conditions

Boundary conditions play a key role in determining the perturbation behavior of a black hole. Motivated by two guiding principles for single-field perturbations -- the non-deformation of the boundary metric and the vanishing of electromagnetic energy flux at the AdS boundary -- we impose a boundary condition for Reissner-Nordström-AdS (RN-AdS) black holes requiring both the metric and electromagnetic field-strength perturbations to vanish at the AdS boundary, which we term the physical field-vanishing (PFV) condition. Using the formulas for perturbation reconstruction, we translate the PFV condition into boundary conditions on the master functions: Dirichlet-type for odd-parity modes and Robin-type for even-parity modes. With these boundary conditions, we compute the quasinormal frequencies of RN-AdS black holes and identify new spectral features. The PFV prescription introduced here could be applied to other multifield perturbation systems in asymptotically AdS spacetimes.

gr-qc↗

Gravitational-Bumblebee perturbations: Exact decoupling and isospectrality

In this paper, we present the exact decoupling of the full metric and bumblebee field perturbations in a Schwarzschild-like background. The coupled system reduces to four decoupled master equations, revealing in each parity sector a Schwarzschild-like gravitational sector and a Lorentz-violating Maxwell-like vector sector. While Lorentz violation modifies the propagation speed of the emergent vector modes, we demonstrate that the gravitational master modes exhibit a ``dynamical immunity'' to the non-minimal Lorentz-violating coupling, and that the odd- and even-parity perturbations remain strictly isospectral. Our work provides a rare example in which Lorentz-violating couplings reshape the field reconstruction while leaving the gravitational ringdown spectrum intact. This mismatch in propagation speeds suggests a possible timing signature of bumblebee vector dynamics in black hole perturbations, offering a theoretical route to testing spontaneous Lorentz symmetry breaking in the era of multi-messenger astronomy.

gr-qc↗

Gravitational Deflection of Vector Photons via Effective Field Theory

Gravitational scattering of the electromagnetic field from a heavy scalar field provides a fundamental testbed for understanding the deflection of light by massive bodies. In many approaches based on effective field theory, the calculation of scattering amplitudes quickly becomes complicated due to the large number of Feynman integrals required, especially beyond leading order. In this work, we study this problem using effective field theory in the weak field approximation. We utilize Integration-By-Parts reduction techniques to precisely examine the long-range contributions governed by terms in the amplitude which are non-analytic in momentum transfer. Using geometric optics and the eikonal approximation, we derive expressions for the deflection angle and find the origin of differences relative to earlier works.

hep-th↗

Master functions of Reissner-Nordstrom black hole perturbations and their Darboux transformation

Lenzi and Sopuerta developed a new method to construct master functions for the perturbation of vacuum black holes. We extend this method to black holes coupled with electromagnetic field and cosmological constant by allowing the master functions to be linear combinations of the metric and electromagnetic-potential perturbations, as well as their first-order derivatives. Requiring these master functions satisfy wave equations with yet-to-be-determined effective potentials, we reduce the linearized Einstein--Maxwell system to a set of algebraic-differential constraints. Solving these constraints reveals four master function branches in each parity sector: two standard branches, which coincide with the Zerilli-Moncrief formalism, and two Darboux branches, characterized by their effective potentials. Within each parity sector, a Darboux transformation exists which connects the standard and Darboux branches, preserving the quasinormal mode spectrum and confirming their physical equivalence.

gr-qc↗

Microscopic State of BHs and an Exact One Body Method for Binary Dynamics in General Relativity

In gravitational collapses, the horizon and singularity's realisation in the finite future of the proper time used co-moving observer happens in the future of infinitely far away future of the normal time used outside probe. To the latter the horizon and singularity of a black hole formed through gravitational collapse are physical realities only in the sense of uncertainty principle and ensemble interpretation. We provide two exact time dependent solution families to the Einstein equation and show that they form a pair of complementarity description for the microscopic state of black holes by showing that the Bekenstein-Hawking entropy formula follows properly from their canonical wave function's degeneracy. We also develop an eXact One Body method for general relativity two-body dynamics whose conservative part requires no perturbative input from post newtonian approximation and applies to the full three stages of black hole binary merger events. By this method, we analytically calculate the gravitational wave forms following from such merger processes. In the case black holes carry exact and apriori horizon and singularity our wave forms agree with those following from conventional effective one body method but exhibit more consistent late time behaviour. In the case the black holes carry only asymptotic horizon and extended inner structure thus experiencing banana shape deformation as the merger progresses, our wave forms exhibit all features especially the late time quasi-normal mode type oscillation seen in real observations.

gr-qc↗

Gravity Induced Spontaneous Radiation

We suggest that behind the black hole information paradox is a new and universal radiation mechanism, Gravity Induced Spontaneous Radiation, or GISR hereafter. This mechanism happens to all kinds of compositional objects and it requires only their microscopic structure as the basis. It's always accompanied with such inner structures' variation and allows for explicitly hermitian hamiltonian description. For black holes, by Wigner-Wiesskopf approximation we show that such a radiation has a thermal spectrum exactly the same as hawking radiation; while through numeric integration, we show that the variation of the radiation particles' entropy exhibits all features of Page curve as expected. We also provide exact and analytic solutions to the Einstein equation describing microscopic structures required by the GISR of black holes and show that, after quantisation the degeneracy of wave functions corresponding with those solutions are consistent with the area law formula of Bekenstein-Hawking entropy.

hep-th↗

Quantum Chaology of Double Rod Pendulum

The double rod pendulum is a well known classic chaotic system, so its quantum version is an ideal laboratory to test various diagnosis for quantum chaos. We quantise this system canonically and calculate its lowest $10^4$ eigenvalues and eigenstate wave functions with at least $10^{-4}$ relative precision by the spectral analysis method. With these eigenvalues and eigenstate wave functions, we calculate and examine the three popular diagnosis on quantum chaos. On the NNSD diagnosis, we find that, either the GOE feature of NNSD is not a necessary condition for a quantum system to be chaotic at classic limit, or the double rod pendulum is not strong chaotic at the classic level. On the OTOC diagnosis, we observed that the early time exponential growth and late time constance approaching feature of OTOC is well conformed by the double rod pendulum. On the CC diagnosis, the status is similar with NNSD. Its linear growth feature at long time limit is either not a good diagnosis for a quantum system to be chaotic at classic limit or the double rod pendulum is not a strong chaotic system at classic levels.

quant-ph↗

Spontaneous Radiation of Black Holes

We provide an explicitly hermitian hamiltonian description for the spontaneous radiation of black holes, which is a many-level, multiple-degeneracy generalization of the usual Janeys-Cummings model for two-level atoms. By standard Wigner-Wiesskopf approximation, we show that for the first one or few particles' radiation our model yields completely the same power spectrum as hawking radiation requires. While in the many-particle radiation cases, numeric methods allow us to follow the evolution of microscopic state of a black hole exactly, from which we can get the firstly increasing then decreasing entropy variation trend for the radiation particles just as the Page-curve exhibited. Basing on this model analysis, we claim that two ingredients are necessary for resolutions of the information missing puzzle, a spontaneous radiation like mechanism for the production of hawking particles and proper account of the macroscopic superposition happening in the full quantum description of a black hole radiation evolution and, the working logic of replica wormholes is an effect account of this latter ingredient. As the basis for our interpretation of black hole Hawking radiation as their spontaneous radiation, we also provide a fully atomic like inner structure models for their microscopic states definition and origins of their Bekenstein-Hawking entropy, that is, exact solution families to the Einstein equation sourced by matter constituents oscillating across the central point and their quantization. Such a first quantization model for black holes' microscopic state is non necessary for our spontaneous radiation description, but has advantages comparing with other alternatives, such as string theory fuzzball or brick wall models.

hep-th↗

Cosmological Complexity in K-essence

We calculate the cosmological complexity under the framework of scalar curvature perturbations for a K-essence model with constant potential. In particular, the squeezed quantum states are defined by acting a two-mode squeezed operator which is characterized by squeezing parameters $r_k$ and $ϕ_k$ on vacuum state. The evolution of these squeezing parameters are governed by the $Schr\ddot{o}dinger$ equation, in which the Hamiltonian operator is derived from the cosmological perturbative action. With aid of the solutions of $r_k$ and $ϕ_k$, one can calculate the quantum circuit complexity between unsqueezed vacuum state and squeezed quantum states via the wave-function approach. One advantage of K-essence is that it allows us to explore the effects of varied sound speeds on evolution of cosmological complexity. Besides, this model also provides a way for us to distinguish the different cosmological phases by extracting some basic informations, like the scrambling time and Lyapunov exponent etc, from the evolution of cosmological complexity.

gr-qc↗

Scrutinizing Various Phenomenological Interactions In The Context Of Holographic Ricci Dark Energy Models

In this paper, we examine two types of interacting holographic dark energy model using Pantheon supernova data, BAO BOSS DR12, CMB Planck 2015, fgas (gas mass fraction) and SZ/Xray (Sunyaev-Zeldovich effect and X-ray emission) data from galaxy clusters (GC). In particular, we considered the Holographic Ricci dark energy and Extended holographic Ricci dark energy models. During this analysis we considered seven type of phenomenological interaction terms (three linear and four non-linear) $Q_1=3Hbρ_{D}$, $Q_2=3Hbρ_{m}$, $Q_3=3Hb\left(ρ_{D}+ρ_m\right)$, $Q_4=3Hb\left(ρ_{D}+\frac{ρ_{D}^2}{ρ_{D}+ρ_m}\right)$, $Q_5=3Hb\left(ρ_{m}+\frac{ρ_{m}^2}{ρ_{D}+ρ_m}\right)$, $Q_6=3Hb\left(ρ_{D}+ρ_{m}+\frac{ρ_{D}^2}{ρ_{D}+ρ_m}\right)$, $Q_7=3Hb\left(ρ_{D}+ρ_{m}+\frac{ρ_{m}^2}{ρ_{D}+ρ_m}\right)$ respectively. To find the best model we apply Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) and use the $Λ$CDM as the referring model for comparison. Using AIC and BIC models selection method we note that the $Q_1$ and $Q_4$ interaction terms are favored by observational data within the context of the holographic Ricci dark energy models. The obtained results also demonstrated that the considered types of holographic Ricci dark energy model are not favored by observational data since the $Λ$CDM is considered as the reference model. We also observed that the values of the deceleration parameter and the transition redshift for all models are compatible with the latest observational data and Planck 2015. In addition, we studied the jerk parameter for all models. Using our modified CAMB code, we observed that the interacting models suppress the CMB spectrum at low multi-poles and enhances the acoustic peaks.

gr-qc↗

Exact Inner Metric and Microscopic State of AdS$_3$-Schwarzschld BHs

Through full solvability of 2+1 dimensional general relativity we derive out exact dynamic inner metric of collapsing stars with inhomogeneous initial mass distribution but joining with outside Anti-deSitt-Schwarzschild black holes smoothly. We prove analytically by standard quantum mechanics that the log-number of such solutions, or microscopic states of the system is proportional to the perimeter of the outside black holes. Key formulas for generalizing to 3+1D Schwarzschild black holes are also presented. Our result provides a bulk space viewpoint to questions on what the microscopic degrees of freedom are and who their carriers are in various holographic and/or asymptotic symmetry methods to black hole entropies. It may also shed light for singularity theorem and cosmic censorship related researches.

hep-th↗

Chaotic D1-D5 Black Hole Dynamics through Networks

This work studies dynamics controlling the transition between different microstates of two charge D1-D5 black holes by network methods, in which microstates of the system are defined as network nodes, while transitions between them are defined as edges. It is found that the eigenspectrum of this network's Laplacian matrix, which is identified with Hamiltonians of the microstate system, has completely the same Nearest-Neighbor Spacing Distribution as that of general Gaussian Orthogonal Ensemble of Random Matrices. According to the BGS, i.e. Bohigas, Giannoni and Schmit conjecture, this forms evidence for chaotic features of the D1-D5 microstate dynamics. This evidence is further strengthened by observations that inverse of the first/minimal nonzero eigenvalue of the Laplacian matrix is proportional to logarithms of the microstate number of the system. By Sekino and Susskind, this means that dynamics of the D1-D5 black hole microstates are not only chaotic, but also the fastest scrambler in nature.

hep-th↗

Neural-network Quantum State of Transverse-field Ising Model

Along the way initiated by Carleo and Troyer [1], we construct the neural-network quantum state of transverse-field Ising model(TFIM) by an unsupervised machine learning method. Such a wave function is a map from the spin-configuration space to the complex number field determined by an array of network parameters. To get the ground state of the system, values of the network parameters are calculated by a Stochastic Reconfiguration(SR) method. We provide for this SR method an understanding from action principle and information geometry aspects. With this quantum state, we calculate key observables of the system, the energy, correlation function, correlation length, magnetic moment and susceptibility. As innovations, we provide a high efficiency method and use it to calculate entanglement entropy (EE) of the system and get results consistent with previous work very well.

cond-mat.dis-nn↗

Information Missing Puzzle, Where Is Hawking's Error?

Matters falling into and consisting of a blackhole can oscillate periodically across instead of accumulate statically on the central point and form singularities there. In quantum language, this oscillation not only resolves central singularities of the blackhole but also blurs its horizon remarkably. This blurring makes the horizon not a zero-thickness geometric surface any more, but an extended physic region whose thickness is comparable with the horizon radius itself. It is our negligence of this fact that leads to the information missing puzzle, and other related question in blackhole physics. Besides the title question and Schwarzschild singularity's resolving, the current work also provides interpretations for the origin of Bekenstein-Hawking entropy and an explicitly unitary formulation of Hawking radiations.

physics.gen-ph↗

Linear Stability Analysis of Evolving Thin Shell Wormholes

Using ideas from the brane world cosmological perturbation theory, we make linear stability analysis of dynamic thin shell wormholes constructed by cutting-and-pasting two building-block spacetime at arbitrary joining shell radiuses. We observed that in appropriate parameter choices, dynamical thin shell wormholes following from such a cut-and-paste procedure can be kept stable during the whole evolution process towards the final extreme point on which the joining-shell radius arrives on static values. Our work forms a valuable complementarity to previous analysis basing on virtual radial perturbations around the born-static value of the joining-shell radius which allows no real evolution of the wormhole.

hep-th↗

Schwarzschild Fuzzball and Explicitly Unitary Hawking Radiations

We provide a fuzzball picture for Schwarzshild black holes, in which matters and energy consisting the hole are not positioned on the central point exclusively but oscillate around there in a serial of eigen-modes, each of which features a special level of binding degrees and are quantum mechanically possible to be measured outside the horizon. By listing these modes explicitly for holes as large as $6M_\mathrm{pl}$, we find that their number increases exponentially with the area. Basing on this picture, we present a simple but explicitly unitary derivation of hawking radiations.

hep-th↗