arXiv subjects

Xin-Fei Li

Publications and source records attributed to Xin-Fei Li.

7 recordsLinked to original sources

arXiv2026

Probing quantum chaos near a wormhole throat with a circular string

We investigate whether quantum fluctuations of a circular probe string develop a quantum-chaotic response while traversing a wormhole throat. The classical circular-string embedding is periodic and radially stable, but its two physical transverse polarizations experience time-dependent tidal potentials. Expanding the world-sheet action to quadratic order, we canonically quantize these modes and construct out-of-time-ordered correlator(OTOC) amplitudes from their unequal-time commutators. For the Ellis--Bronnikov wormhole, both polarizations exhibit finite intervals of approximately exponential OTOC growth associated with the first throat passage. The corresponding dimensionless rate measured with respect to physical time is positive over the parameter range studied and generally decreases as the probe energy is increased relative to the throat scale. In the global-monopole extension, increasing the solid-angle deficit narrows the band of locally amplifiable modes and suppresses the extracted rates; a sufficiently strong defect can nearly quench the radial signal, while the angular channel retains a polarization-dependent non-monotonic structure when the energy-to-throat-scale ratio is small. These quantities characterize finite-time dynamical sensitivity in the Gaussian fluctuation sector and should not be identified with asymptotic many-body chaos or a thermodynamic phase transition. Although the numerical analysis uses two representative wormhole geometries, the construction depends only on covariant world-sheet fluctuations and real-time commutators. It therefore provides a transferable, non-holographic framework for applying quantum-chaos diagnostics directly to quantum probes in curved spacetimes.

gr-qc↗

arXiv2026

Quantum Entanglement of Circular Strings as a Probe for Topologically Charged Spacetimes

Motivated by the limited understanding of entanglement entropy in non-asymptotically AdS spacetimes, we develop a framework in which a circular string is embedded as a quantum probe in a spherically symmetric curved spacetime, and its quadratic fluctuations are quantized using the squeezed-state formalism. This construction naturally yields two mode quantum states and the associated von Neumann entropy, providing a direct measure of particle antiparticle entanglement. The resulting entanglement serves as an effective probe of the underlying geometry, granting access to intrinsic features that are not readily captured by classical observables such as geodesic motion. As a concrete application, and as representative toy models of spacetimes with topological defects, including wormhole geometries, we investigate backgrounds with topological charge, focusing on global monopole and monopole wormhole configurations. We show that the entanglement generated by the probe string exhibits a clear qualitative distinction between these backgrounds and is highly sensitive to the global structure of the spacetime, in particular to the deficit angle. These results illustrate the utility of quantum correlations as diagnostic tools for probing geometric properties beyond the classical regime and offer a complementary perspective on the interplay between spacetime structure and quantum entanglement.

gr-qc↗

arXiv2025

Is gamma-ray burst polarization from photosphere emission?

Context: Despite more than half a century of research, the dominant radiation mechanism of gamma-ray burst (GRB) prompt emission remains unsolved. Some progress has been made through the analyses of the observational spectra of Swift/BAT, Konus/Wind, and Fermi/GBM, as well as the spectra of the photosphere or synchrotron models, but it is still insufficient to pin down the answer. Aims: Combining the spectral and polarization observations, we seek new criteria for model evaluation. Methods: We thoughtfully investigate the polarization samples of POLAR and AstroSAT, combining the light curve, the spectral and the polarization parameters. Results: The power-law shape of the X-ray afterglows, the $T_{90} \propto (L_{\text{iso}})^{-0.5}$ correlation, and the hard low-energy spectral index $α$ are revealed, thus supporting the photosphere origin. Furthermore, we discover the positive correlation of the $α$ and the polarization degree (PD), which can be consistently explained by the photosphere polarization scenario involving the jet asymmetry from a moderate viewing angle of $θ_{v}$=0.015.

astro-ph.HE↗

arXiv2025

Gravitational lensing of the wormhole in the Eddington-inspired Born-Infeld spacetime with a cosmic string

In this work we study gravitational lensing of the wormhole in the Eddington-inspired Born-Infeld (EiBI) spacetime that incorporates with a cosmic string. It was found that the presence of cosmic string can enhance the light deflection in strong field limit, compared to the case of the Eills-Bronnikov wormhole. The magnification effects of this composite structure could cause some substantial impacts on the angle separation between the first and the rest of the images, and their relative brightness. Furthermore, based on these observables, we model some observable aspects in the strong and the weak field limits. The presence of a cosmic string can affect some distinguishable observables compared to the wormhole without cosmic string. This work could deepen our understanding of the spacetime structure of the wormhole in EiBI spacetime with one-dimensional topological defects.

gr-qc↗

arXiv2021

Morris-Thorne Wormhole in the Vector-Tensor theories with Abelian gauge symmetry breaking

We construct an asymptotically flat Morris-Thorne wormhole solution supported by anisotropic matter fluid and a vector field which is coupled to gravity in a non-minimal way with broken Abelian gauge symmetry. In this paper, a specific shape function is considered. We find that the ansatz of vector field plays a significant role in determining the spacetime geometry of the wormhole. If there exists the electrostatic potential only, the redshift function could be considered as a constant value, implying the vanishing tidal force. However, when the vector potential in radial-direction is involved, the r-component of extended Maxwell equations at the wormhole's throat is invalid. To solve this issue, a thin shell is introduced near the throat, dividing the spacetime into two parts. Furthermore, it is proved that the spacetime geometry of wormhole could be smooth at junction position if the expressions of redshift function and vector potential are given appropriately. Finally, the energy conditions and the volume integral quantifer are explored.

gr-qc↗

arXiv2021

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↗

arXiv2020

Response relation in Pb-Pb and p-Pb collisions at 5.02 TeV

We carry out simulations using a multi-phase transport (AMPT) model to describe the response relation between $v_2$ and $\varepsilon_2$ in Pb-Pb and p-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV, respectively. To simulate such relation, two methods have been introduced in the calculation: one is the directed response (DR) method, which correlates the outgoing particles with the initial anisotropy directly, and the other one is the cumulants response (CR) method, which is constructed from a cumulants correlation between outgoing particles. Based on calculations of the DR and CR methods, the response relations as a function of the transverse momentum are both shown in Pb-Pb and p-Pb collisions. By comparing the DR and CR methods, we found that the linear response relations are almost identical in all the present collisions. Similar results of linear+cubic response relations are also shown in the higher multiplicity systems, and it has become a significant difference in the lower multiplicity systems, i.e., the peripheral Pb-Pb collisions and p-Pb collisions. Throughout the whole $p_{T}$-dependent simulations, the $κ_2$ in the linear response and in the linear+cubic response are almost identical, except for in the lower multiplicity systems by the DR method. If one implements a pseudorapidity gap by the CR calculation, the $p_{T}$-dependent and $η$-independent response relations are similarly shown in peripheral Pb-Pb systems and p-Pb systems, which may imply that a collective response exists in the most central p-Pb collisions. These collective behaviors are dominantly produced on the stage of the medium expansions.

nucl-th↗