arXiv subjects

Jinan Zhao

Publications and source records attributed to Jinan Zhao.

4 recordsLinked to original sources

arXiv2026

Canonical quantization of the Pais-Uhlenbeck oscillator with a higher-derivative perturbation: a covariant phase space approach

In this paper, we apply the covariant phase space formalism to the perturbative canonical quantization of the Pais-Uhlenbeck oscillator, with the acceleration-squared term treated as a perturbation. We quantize this model by constructing the symplectic form on the low-energy solution space. We then compute the energy spectrum and the unequal-time commutator in a perturbative way, and obtain the results that agree with the expansion of the exact low-energy theory. The perturbation method bypasses the standard Ostrogradsky construction and naturally decouples the Ostrogradsky ghost. This work extends our previous perturbative quantization scheme to genuine higher-derivative theories.

quant-ph↗

arXiv2026

Canonical quantization for effective theories with perturbations altering degrees of freedom: a covariant phase space approach

The standard approach to canonical quantization encounters difficulties in dealing with perturbations that alter the kinetic structure of unperturbed theories. We show that the covariant phase space formalism provides a natural and technically efficient way to circumvent this obstruction. We illustrate the method with an exactly solvable model: a two-dimensional non-relativistic charged particle moving in a magnetic field and a harmonic confining potential, with its kinetic energy viewed as a perturbation. We quantize this model with covariant phase space formalism by constructing the solution perturbatively. We then calculate the energy spectrum and the unequal-time commutators of this model, and obtain the results that agree with the expansion of the exact theory. The procedure developed here is intended to serve as a systematic framework for the canonical quantization of more complex effective theories with higher-derivative or velocity-dependent perturbations.

hep-th↗

arXiv2025

The entropy of dynamical de Sitter horizons

Recently Hollands, Wald and Zhang proposed a new formula for the entropy of a dynamical black hole. We lift this construction to the dynamical cosmological event horizon of an asymptotically de Sitter spacetime. By introducing a nontrivial correction term in the formula for the entropy, we generalize Gibbons and Hawking's "first law of event horizons" to non-stationary eras. We also develop the non-stationary physical process first law between two arbitrary horizon cross-sections for the cosmological event horizon.

gr-qc↗

arXiv2025

Dynamical black hole entropy beyond general relativity from the Einstein frame

Recently Hollands, Wald and Zhang proposed a new formula for the entropy of a dynamical black hole for an arbitrary theory of gravity obtained from a diffeomorphism covariant Lagrangian via the Noether charge method. We present an alternative, pedagogical derivation of the dynamical black hole entropy for $f(R)$ gravity as well as canonical scalar-tensor theory by means of conformal transformations. First, in general relativity we generalize Visser and Yan's pedagogical proof of the non-stationary physical process first law to black holes that may not be in vacuum, and give a pedagogical derivation of the second-order behavior of the dynamical black hole entropy for vacuum perturbations by considering the second-order variation of the Raychaudhuri equation. Second, we apply the derivation for general relativity to theories in the Einstein frames, and then recast the conclusions in their original frames. We show that the dynamical black hole entropy formulae of these theories satisfy both the non-stationary physical process first law and the non-stationary comparison first law via the Einstein frame. We further study the second-order behavior of the dynamical black hole entropy for vacuum perturbations, and observe that the second law is obeyed at second order in those theories. Using the Einstein frame, we also determine the relationship between the dynamical black hole entropy and the Wald entropy of the generalized apparent horizon in the original frame.

hep-th↗