arXiv subjects

Ya-Peng Hu

Publications and source records attributed to Ya-Peng Hu.

At least 19 recordsLinked to original sources

arXiv2026

Holographic SU(3) color superconductivity at finite baryon chemical potential

We present a holographic model of SU(3) color superconductivity (CSC) where a global color symmetry is spontaneously broken by a diquark condensate at finite baryon chemical potential. At $\mu_b=0$, a systematic stability analysis over all SU(3) channels recovers the known SU(2) s+p competition. Based on that, the finite $\mu_b$ further generalizes the s-wave order to an S1+iS2 structure. We find that $\mu_b$ enhances the critical temperature of the S1+iS2 phase while suppressing the p-wave -- the latter vanishes beyond a certain $\mu_b$ when backreaction is included. This opposite trend reshapes the phase diagram: with increasing $\mu_b$, the balanced S+ phase (S1=S2) takes over the entire color-superconducting region. Our non-Abelian framework provides a concrete holographic description of global SU(3) symmetry breaking, relevant for understanding color-superconducting phases in dense QCD and may offer new insights into the physics of neutron-star interiors.

hep-th↗

arXiv2026

Chaotic particle dynamics near a traversable wormhole throat

This study investigates the nonlinear dynamics of a test particle near the traversable wormhole throat under an external harmonic potential. One-dimensional radial perturbation analysis shows that the particle is locally linearly stable at the equilibrium position. However, for two-dimensional and high-energy cases, the system exhibits a nonlinear response, leading to large-scale chaos. The analysis indicates that, if the particle is confined on one side of the wormhole, the Poincare section will still retain Kolmogorov-Arnold-Moser (KAM) tori under extremely high-energy conditions, which is distinct from the chaos caused by the event horizon in the black hole. By studying another set of shape functions, the universality of this phase space structure is confirmed. This research clarifies the unique nonlinear dynamical mechanism of a traversable wormhole. It provides a new criterion, based on chaotic dynamics, for identifying black hole mimickers in strong-field astrophysical observations.

gr-qc↗

arXiv2026

Kiselev black hole and the ultra-slow evaporating behavior

Kiselev solution is a metric that describes black holes immersed in a quintessence-like dark energy background. By introducing a dynamic state parameter $w_q$, the Kiselev solution is supposed to help comprehend the effect of quintessential matter on black holes. In this work, we study the evaporation behaviors of Kiselev black holes. By varying the state parameter $w_q$, we find that the decreasing state parameter lowers the non-final stage temperature and markedly prolongs the evaporation lifetime. We also find that the ultra-slow evaporation mechanism of Kiselev black holes differs vastly from the perfect fluid dark matter (PFDM) black holes and Horndeski black holes, which share the analogous ultra-long lifetime. These results illuminate the effects of dynamic dark energy background on black hole evaporation, provide a potential laboratory to constrain the value of $w_q$, and may complement cosmological and astrophysical observations, e.g., the DESI's preference for thawing dark energy and the observation of exploding black holes based on ultra-slow evaporation.

gr-qc↗

arXiv2026

Constraints on non-canonical chaotic inflation from ACT DR6 and BICEP/Keck data

In this study, we precisely evaluated the feasibility of the chaotic inflation model within a non-canonical kinetic framework. By applying the slow-roll approximation and imposing constraints on the equilateral non-Gaussianity $f_{\rm NL}^{\rm equil}$, we imposed constraints on the feasible range of the potential index $n$. We established physical bounds for the non-canonical parameter $\alpha$. To obtain precise parameter constraints, we solved the primordial perturbation equations numerically and conducted a rigorous MCMC analysis by using a comprehensive joint P-ACT-LB-BK18 dataset. For these potentials $n=1/3$, $2/3$, and $1$, our results respectively tightly limit $\alpha$ to the levels of $8.8^{+1.6}_{-2.8}$, $11.7^{+1.7}_{-2.6}$, and $16.4^{+3.7}_{-7.0}$, within the corresponding $1\sigma$ confidence intervals. Meanwhile, the required number of $e$-foldings naturally converges to $N \simeq 54$, without the need for fine-tuning. These findings confirm that non-standard mechanisms can resurrect excluded chaotic inflation models within the $1\sigma$ allowed regions of high-precision cosmological data.

gr-qc↗

arXiv2026

Cosmological coupled black holes immersed in dark sector

Motivated by theoretical and observational developments of cosmological coupled black holes, we construct an exact analytical solution for a black hole immersed in an anisotropic dark sector background, adopting the framework established by [Cadoni et al., JCAP 03 (2024) 026]. By generalizing a static seed metric to a dynamical FLRW background, we derive a solution where the black hole mass co-evolves with the cosmic expansion. We then obtain the explicit form of the radius-dependent coupling exponent, revealing that the interaction is governed by the dark halo profile. Considering the ubiquity of the dark halos surrounding supermassive black holes, our model provides a potential realization of cosmological coupling, interpreting the mass growth as the dynamical response of the surrounding dark sector fluid to the Hubble flow, distinct from the method of modifying the black hole's internal equation of state.

gr-qc↗

arXiv2025

Imprints of Topological Thermodynamics on Black Hole Dynamics

By employing Duan's topological method, we classify critical points by their topological charge Q = +/-1 or 0. Previous work (Wei et al., Phys. Rev. D 105, 104003, 2022) investigated two typical anti-de Sitter (AdS) black holes: the Reissner-Nordstroem (RN) case (with only one critical point Q = -1) and the Born-Infeld (BI) case (with two critical points Q = +/-1). In this work, we first find that all three types of critical points appear in quantum anomalous black holes for 4D spacetime. We then compute the quasinormal modes of massless scalar perturbations near these critical points and find that both the oscillation frequency and damping rate increase with the black hole radius at the critical temperature. Besides such common behavior, although the Q = +1 and Q = 0 cases do not show a discernible pattern due to the limited number of samples, the Q = -1 case exhibits very similar dynamical characteristics across all three black hole solutions, implying a nontrivial connection between topological thermodynamics and dynamics.

gr-qc↗

arXiv2025

Interior structure of the holographic s + p superconductor and chaotic-stable transition near the black hole singularity

In this work, we investigate the interior structure of a holographic multi-band superconductor with the coexistence of s-wave and p-wave order parameters. Especially, we investigate the singularity structure of this multi-band model. Different from the single p-wave case, the alternation rule is jointly determined by parameters involving both s-wave order and p-wave order. In the coexistence region, we derive the Kasner alternation laws from both analytical and numerical methods which fit each other nicely. Furthermore, we find that the occurrence of the s-wave order parameter will lead to a chaotic-stable transition for the near singularity structure which matches the expectation of cosmological billiard approach. This novel transition for the near singularity structure constitutes a holographic counterpart of the secondary condensation in boundary superconducting system, offering a complementary perspective for characterizing the properties of boundary condensed matter systems.

hep-th↗

arXiv2025

Diving into a holographic multi-band superconductor

In this work, we investigate the interior structure of a holographic multi-band superconductor model. We focus on the holographic superconductor system with two scalar fields which correspond to two s-wave order parameters in the dual condensed matter system. We discover a new kind of transition rule among Kasner universe near the black hole singularity which is distinct from the holographic single-band superconductor model. This transition rule is the first generalization of Kasner transition behavior to scenarios involving multiple free parameters, which is useful for uncovering the most general interior structures of hairy black holes. Moreover, we find that the Kasner exponents are sensitive to the details of order parameters in boundary system. These different near singularity structures we found show that the black hole interior plays crucial role in characterizing the boundary dual condensed matter systems.

hep-th↗

arXiv2025

Quantum anomaly triggers the violation of scaling laws in gravitational system

Scaling laws for critical phenomena take pivotal status in almost all branches of physics. However, as scaling laws are commonly guaranteed by the renormalization group theory, systems that violate them have rarely been found. In this letter, we demonstrate that gravitational system can break scaling laws. We derive this result through investigating phase transition and critical phenomenon in a gravitational system with quantum anomaly. For the first time, we outline the key conditions to violate the scaling laws in generic gravitational system viewed from the equation of state $P=P(T,V)$. Our results indicate that quantum effects can magnify the distinctiveness of gravity, which may be significant to understand the microscopic structure of spacetime.

gr-qc↗

arXiv2025

High-Frequency Thermal Graviton Remnant from the End of Inflation

The standard inflationary theory focuses on the freezing of super-horizon fluctuations, which generate a scale-invariant spectrum, while the sub-horizon modes are expected to remain in thermal equilibrium. Building upon recent development of quantum thermodynamics of the de Sitter universe, we investigate the graviton remnant originating from this thermal horizon radiation released at the end of inflation. Unlike the stochastic background from super-horizon fluctuations, this signal represents a snapshot of the thermal dS state, which subsequently decouples and undergoes cosmological redshift. We present a semi-analytical approximation prediction for this relic background, typically peaking in near MHz band, with characteristic energy density of $\log_{10}(\Omega_{\rm G} h^2) \sim \mathcal{O}(-18)$. These signals occupy a High-Frequency band, offering a potential novel probe of the reheating temperature and the thermal history of the early universe.

gr-qc↗

arXiv2025

Curled orbit and epicyclic oscillation of charged particles around the weakly magnetized black hole in the presence of Lorentz violation

In this paper, we investigate the motion of charged particles around the weakly magnetized Schwarzschild-like bumblebee black hole which has Lorentz symmetry breaking. Charged particles have curled orbits around the black hole which can only appear in the presence of external magnetic field. We investigate the effect of Lorentz violation factor on the curled orbit for both the case with and without cosmological constant. Furthermore, we investigate the harmonic oscillation behavior of the charged particles around the stable circular orbit. By using the epicyclic resonance model, we relate the harmonic oscillations of charged particles to the twin high frequency quasi-periodic oscillations observed in micro-quasars. Based on the observations of quasi-periodic oscillation, we provide a stringent constraint on the Lorentz violating parameters by using Markov Chain Monte Carlo algorithm. As the black hole shadow for Schwarzschild-like bumblebee black hole degenerates to the ordinary Schwarzschild black hole, the constraints we obtained from the quasi-period oscillation is crucial for further searching for the imprint of Lorentz symmetry breaking in our universe.

gr-qc↗

arXiv2025

Misner-Sharp Energy and P-V Criticality in Quasi-Topological Cosmology

We presented a sound foundation of thermodynamics for a Friedmann-Robertson-Walker (FRW) universe from the first principle in ground-breaking work [Hu et al., JHEP12 (2022) 168]. Based on such an approach, we explore the thermodynamics of cosmology in quasi-topology gravity. Starting from the unified first law, we first obtain the well-defined Misner-Sharp energy in quasi-topology cosmology. We demonstrate that the Misner-Sharp energy is equal to $ρV$ inside the apparent horizon. Further, the unified first law requires extra terms for generalized force and conjugate generalized position, which are identified as thermodynamic pressure and thermodynamic volume, respectively. Hence we naturally derive the equation of state of the FRW universe in quasi-topology gravity, and show that it undergoes $P$-$V$ phase transitions. We calculate the critical exponents for the phase transition, which may be beneficial to probe the micro theory of quasi-topology gravity.

gr-qc↗

arXiv2025

Einstein-Horndeski gravity and the ultra slowly evaporating black hole

In this work, we study the evaporation behaviors of asymptotically flat charged black holes in the Einstein-Horndeski gravity theory. Based on the thermodynamics of the Horndeski black hole, we present a physical understanding of the scalar charge of the Horndeski black hole and also clarify its connection to the Einstein vector theory. As the presence of non-minimal coupling, the evaporating behaviors of the Horndeski black hole are vastly different from the Reissner-Nordstrom (RN) black hole case. Due to the different spacetime and electric field structures, the evaporation rate of the Horndeski black hole will slow down at the late stage of evaporation and thus gain a lifetime much longer than the RN black hole. These results illuminate the effect of non-minimally coupled matters on the black hole evaporation and provide clues to search for these matter fields in future observations.

gr-qc↗

arXiv2024

Superradiance of rotating black holes surrounded by dark matter

In rotating black hole background surrounded by dark matter, we investigated the super-radiant phenomenon of massive scalar field and its associated instability.Using the method of asymptotic matching, we computed the amplification factor of scalar wave scattering to assess the strength of super-radiance. We discussed the influence of dark matter density on amplification factor in this black hole background. Our result indicates that the presence of dark matter has suppressive influence on black hole super-radiance. We also computed the net extracted energy to further support this result. Finally, we analyzed the super-radiant instability caused by massive scalar field using the black hole bomb mechanism and found that the presence of dark matter has no influence on the super-radiant instability condition.

gr-qc↗

arXiv2024

Different effects of the Lorentz and Gaussian bump functions on the formation of primordial black holes and secondary gravitational waves

Scalar perturbations in the inflation can be amplified when the base inflation potential $V_b(\phi)$ incorporates a local bump $f(\phi)$ such as $V(\phi)=V_b(\phi)(1+f(\phi))$. This modification will lead to a peak in the curvature power spectrum, increasing a significant abundance of primordial black holes (PBHs). However, since there is no underlying physical reason for the choice of $f(\phi)$, it is essential to investigate the effects of various bump functions on PBH generation. In this paper, we choose the well-known Starobinsky potential as the base inflation potential to compare the effects produced by different bumps, specifically focusing on the Lorentz and Gaussian bumps which are widely used. To clearly illustrate the differences between these two bumps, we keep parameters in bump functions the same. We find an interesting and novel result that the Lorentz cases manifest a stronger ability to enhance the power spectrum and produce more abundance of PBHs than Gaussian cases. Moreover, we also investigate the different effects of bump functions on the scalar-induced gravitational waves (SIGWs). The results indicate that the Lorentz bump generates SIGWs with a higher energy density, which can be potentially detected in the future. Our study gives valuable insights into the choice and constraints on the bump functions, and the different effects may distinguish the two bump cases for practical purposes in future experiments.

astro-ph.CO↗

arXiv2024

Equation of State and Joule-Thomson Expansion for the FRW Universe in the Brane World Scenario

We study the thermodynamic properties of the Friedmann-Robertson-Walker (FRW) universe in the brane world scenario, concentrating on the Randall-Sundrum II model. From the first law of thermodynamics for the FRW universe, we find that the work density W can be identified with the thermodynamic pressure P. We construct the equation of state P=P(V,T) for the FRW universe in the brane world scenario, which does not show P-V phase transition. We further study the Joule-Thomson expansion of the FRW universe, and derive the Joule-Thomson coefficient, which has an inversion point that is affected by the brane tension. These results could provide new ways to test the brane world scenario and extra dimension.

gr-qc↗

arXiv2023

Investigating shadow images and rings of the charged Horndeski black hole illuminated by various thin accretions

In this paper, we investigate the shadows and rings of the charged Horndeski black hole illuminated by accretion flow that is both geometrically and optically thin. We consider two types of accretion models: spherical and thin-disk accretion flow. We find that in both types of models, the size of the charged Horndeski black hole shadow decreases with the increase of the charge, and it decreases more slowly for the Reissner-Nordström (RN) black hole. In the spherical accretion flow model, we find that the increase of the charge of Horndeski black hole brightens the light ring around it, and it brightens more significantly in comparison with RN black hole. Due to the Doppler effect, the charged Horndeski black holes with accretion flow of radial motion have darker shadows than those with the static accretion flow, but the size of the shadow is not affected by accretion flow motion. In the thin disk-shaped accretion flow model, we find that the brightness of the light ring around the charged Horndeski black hole is dominated by the direct emission from the accretion flow, and the contribution from lensed rings is relatively small, and that from the photon rings is negligible. We also find that the ring brightness decreases as the charge of Horndeski black hole increases, and the decrease is more significant than that in the RN black hole case. Moreover, the radiation position of the accretion flow can affect the shadow size and the ring brightness of the charged Horndeski black hole.

gr-qc↗

arXiv2023

On the gauge dependence of scalar induced secondary gravitational waves during radiation and matter domination eras

We revisit the vital issue of gauge dependence in the scalar-induced secondary gravitational waves (SIGWs), focusing on the radiation domination (RD) and matter domination (MD) eras. The energy density spectrum is the main physical observable in such induced gravitational waves. For various gauge choices, there has been a divergence in the energy density, $Ω_{\text{GW}}$, of SIGWs. We calculate SIGWs in different gauges to quantify this divergence to address the gauge-dependent problem. In our previous studies, we had found that the energy density diverges in the polynomial power of conformal time (e.g., $η^6$ in uniform density gauge). We try to fix this discrepancy by adding a counter-term that removes the fictitious terms in secondary tensor perturbations. We graphically compare the calculations in various gauges and also comment on the physical origin of the observed gauge dependence.

gr-qc↗