arXiv subjects

Bo-Xuan Ge

Publications and source records attributed to Bo-Xuan Ge.

17 recordsLinked to original sources

arXiv2026

Vanishing Island: Spectral Criticality in Boson Stars

We identify a cusp-type endpoint at which a finite radially stable region of solitonic boson stars disappears. Two fundamental radial zero-mode boundaries coalesce there, while the constrained quadratic stiffness and cubic coefficient vanish and the quartic coefficient remains finite and non-zero. The soft radial mode obeys $Ω_{\mathrm{soft}}\propto (σ_{\mathrm{cusp}}-σ)^{1/2}$, revealing a divergent linear timescale at the endpoint. The same critical structure persists under the tested deformation of the scalar self-interaction.

gr-qc↗

arXiv2026

Massive boson stars: Waveform-based branch diagnosis with neural reconstruction

We investigate whether the dynamical merger branch of massive boson-star collisions can be inferred from the gravitational waveform without supplying the intrinsic source parameters. Using an existing equal-mass, head-on numerical-relativity catalogue, we construct branch-conditioned reduced-basis surrogates for the real $(2,0)$ and $(4,0)$ modes and perform parameter-blind waveform inference. On a frozen test set of 60 held-out samples, the correct branch is recovered for all samples using either mode, showing that the branch information is not confined to the dominant $(2,0)$ channel. The inference also recovers $|ϕ_c|$ with a mean relative error of $4.30\%$ and selects the correct $λ$ from $\{10,50,100,300\}$ in $68.3\%$ of the test samples. These results demonstrate waveform-based branch and source-parameter inference within the present noiseless numerical-relativity catalogue.

gr-qc↗

arXiv2026

From Modal Memory to Topological Relaxation in a Driven Holographic Superfluid

We study how driving history affects the nonlinear topological relaxation of a holographic superfluid. Different histories are constructed to reach the same present driving conditions and then follow the same future protocol. Although they relax to the same final winding sector, their late-time dynamics remain strongly history-dependent: the residence time of the penultimate winding sector changes by about a factor of $3.7$. This variation is organised by the modal imbalance carried into the common amplification stage. Histories with different shapes but matched modal imbalance produce nearly identical relaxation times. The same qualitative behaviour is found for a second pair of competing modes.

hep-th↗

arXiv2026

Relative-Phase Control of Common-Bridge Survival in Collisions of Radially Excited Boson Stars

We show that the relative phase primarily controls the survival, rather than the initial formation, of the common bridge in head-on collisions of radially excited boson stars. In the benchmark configuration, all sampled phases form both a common and a strong bridge. After aligning the evolutions at the same operational weak-contact level, their early post-contact evolution remains similar, while a clear phase hierarchy develops only later, with larger phase offsets producing a weaker and less persistent connection. The same suppression persists under controlled variations of the central scalar amplitude, quartic self-interaction strength, and scalar potential. These results identify relative phase as a control on the nonlinear persistence of the common bridge rather than simply on the instantaneous scalar-field overlap.

gr-qc↗

arXiv2026

Timing-Window Mechanism for Chain-Like Transients in Collisions of Radially Excited Boson Stars

We show that chain-like transients in head-on collisions of radially excited boson stars are controlled by the binary collision time, not by radial excitation alone. For selected $n=2$, $λ=400$ self-interacting configurations, isolated evolutions define breathing windows that serve as reference clocks. Numerical-relativity simulations show that visible chains form only when the collision time is compatible with the isolated breathing clock. A separation scan shifts the collision time relative to the same clock, confirming the timing-window mechanism. An additional fixed-separation check at $λ=500$ shows the same event ordering, indicating that the observed pattern is not unique to the fiducial self-interaction strength.

gr-qc↗

arXiv2026

History-Dependent Mode Selection in a Driven Holographic Superfluid

We study finite-rate mode selection among competing Landau-unstable modes in a holographic superfluid. The selected mode is not generally the instantaneous fastest-growing one, while time-dependent linear evolution on the driven background reproduces the full dynamics. Protocols with identical present driving conditions can exhibit opposite modal ordering, revealing memory of the preceding drive. This memory is quantitatively captured by the accumulated difference between the QNM growth rates of the competing modes.

hep-th↗

arXiv2026

Taiji Resolving Power for the Transverse Scalar Mode of Gravitational Waves

We investigate how small a co-propagating transverse-scalar component can be resolved by Taiji in an already identified bright tensor chirp. Using a source-tracked tensor-null response, we formulate the problem in terms of the minimum resolvable scalar strain fraction and evaluate it over the sky. For a one-year benchmark chirp with tensor signal-to-noise ratio $ρ_T=1000$, we find that Taiji can rule out transverse-scalar strain fractions $ε_b\gtrsim0.532\%$ at the all-sky median level. The threshold scales as $ε_{b,\min}\proptoρ_T^{-1}$, so brighter tensor events can probe correspondingly smaller scalar fractions. We further find that this sub-percent resolving power remains predictable under small source-parameter mismatches through the associated tensor-leakage structure.

gr-qc↗

arXiv2026

Neural variational framework for random Young-diagram limit shapes

We develop a structure-preserving neural variational framework for random Young-diagram ensembles, with representations adapted to the structure and scaling of each measure. The method is validated on the Plancherel, uniform, minimal-difference, and fixed-$q$ $q$-Plancherel ensembles, using known asymptotic profiles only for post-training comparison. We then study a quartically deformed hook-length ensemble without assuming an analytical saddle shape. Large-$n$ neural profiles are compared with finite-size MAP profiles obtained from exact-action searches and with mean profiles obtained from corner-transfer Metropolis--Hastings sampling. Increasing the deformation suppresses the leading rows and broadens the support, while the neural, discrete, and sampled mean profiles agree at the percent level. These results provide numerical evidence for a deformation-dependent macroscopic saddle family.

cond-mat.stat-mech↗

arXiv2026

Massive boson stars: Stability and GW emission in head-on mergers

We investigate quartically self-interacting massive boson stars by constructing equilibrium sequences and performing dynamical evolutions. The mass curve $M(|ϕ_c|)$ along these sequences develops multiple extrema, yet stability changes only at the first maximum; configurations beyond it become highly compact and collapse under numerically induced perturbations, with near-critical models displaying a short-lived double-dive behaviour. Head-on collisions of equal-mass stars yield three distinct outcomes -- boson star remnants, black hole formation at contact, and collapse of each star to a black hole prior to contact. The associated gravitational-wave energies reflect a competition between increasing compactness, which enhances the efficiency of gravitational-wave emission, and decreasing tidal deformability, which suppresses merger asymmetries, and at large self-interaction strengths the collapse-before-contact branch exhibits a pronounced non-monotonic structure. The simulations reported here constitute a substantial catalogue of initial conditions and waveforms, providing a natural basis for constructing surrogate models capable of rapidly predicting gravitational-wave signals across an extended parameter space.

gr-qc↗

arXiv2025

AInsteinBench: Benchmarking Coding Agents on Scientific Repositories

We introduce AInsteinBench, a large-scale benchmark for evaluating whether large language model (LLM) agents can operate as scientific computing development agents within real research software ecosystems. Unlike existing scientific reasoning benchmarks which focus on conceptual knowledge, or software engineering benchmarks that emphasize generic feature implementation and issue resolving, AInsteinBench evaluates models in end-to-end scientific development settings grounded in production-grade scientific repositories. The benchmark consists of tasks derived from maintainer-authored pull requests across six widely used scientific codebases, spanning quantum chemistry, quantum computing, molecular dynamics, numerical relativity, fluid dynamics, and cheminformatics. All benchmark tasks are carefully curated through multi-stage filtering and expert review to ensure scientific challenge, adequate test coverage, and well-calibrated difficulty. By leveraging evaluation in executable environments, scientifically meaningful failure modes, and test-driven verification, AInsteinBench measures a model's ability to move beyond surface-level code generation toward the core competencies required for computational scientific research.

cs.SE↗

arXiv2025

Hair is complicated: Gravitational waves from stable and unstable boson-star mergers

We explore the gravitational-wave emission from head-on collisions of equal-mass solitonic boson-star binaries from simulations spanning a two-dimensional parameter space, consisting of the central scalar-field amplitude of the stars and the solitonic potential parameter. We report the gravitational-wave energies emitted by boson-star binaries which, due to their combination of moderately high compactness with significant deformability, we often find to be louder by up to an order of magnitude than analogous black-hole collisions. The dependence of the radiated energy on the boson-star parameters exhibits striking needle-sharp features and discontinuous jumps to the value emitted by black-hole binaries. We explain these features in terms of the solitonic potential and the stability properties of the respective individual stars.

gr-qc↗

arXiv2023

Unequal-mass boson-star binaries: Initial data and merger dynamics

We present a generalization of the curative initial data construction derived for equal-mass compact binaries in Helfer {\it et al} (2019 Phys. Rev. D 99 044046; 2022 Class. Quantum Grav. 39 074001) to arbitrary mass ratios. We demonstrate how these improved initial data avoid substantial spurious artifacts in the collision dynamics of unequal-mass boson-star binaries in the same way as has previously been achieved with the simpler method restricted to the equal-mass case. We employ the improved initial data to explore in detail the impact of phase offsets in the coalescence of equal- and unequal-mass boson star binaries.

gr-qc↗

arXiv2023

Electromagnetic instability of compact axion stars

If the dark matter is composed of axions, then axion stars are expected to be abundant in the Universe. We demonstrate in fully non-linear (3+1) numerical relativity the instability of compact axion stars due to the electromagnetic Chern-Simons term. We show that above the critical coupling constant $g_{aγ}^\mathrm{crit} \propto M_s^{-1.35}$, compact axion stars of mass $M_s$ are unstable. The instability is caused by parametric resonance between the axion and the electromagnetic field. The existence of stable compact axion stars requires approximately Planck-suppressed couplings to photons. If the coupling exceeds the critical value, then all stable axion stars are necessarily non-compact. Unstable axion stars decay leaving behind a less massive, less compact, remnant. The emitted radiation peaks at frequency $ω\sim 1/R_s$, where $R_s$ is the axion star radius.

hep-ph↗

arXiv2022

The Gravitational Afterglow of Boson Stars

In this work we study the long-lived post-merger gravitational wave signature of a boson-star binary coalescence. We use full numerical relativity to simulate the post-merger and track the gravitational afterglow over an extended period of time. We implement recent innovations for the binary initial data, which significantly reduce spurious initial excitations of the scalar field profiles, as well as a measure for the angular momentum that allows us to track the total momentum of the spatial volume, including the curvature contribution. Crucially, we find the afterglow to last much longer than the spin-down timescale. This prolonged gravitational wave afterglow provides a characteristic signal that may distinguish it from other astrophysical sources.

gr-qc↗

arXiv2022

GRChombo: An adaptable numerical relativity code for fundamental physics

GRChombo is an open-source code for performing Numerical Relativity time evolutions, built on top of the publicly available Chombo software for the solution of PDEs. Whilst GRChombo uses standard techniques in NR, it focusses on applications in theoretical physics where adaptability, both in terms of grid structure, and in terms of code modification, are key drivers.

gr-qc↗

arXiv2021

Malaise and remedy of binary boson-star initial data

Through numerical simulations of boson-star head-on collisions, we explore the quality of binary initial data obtained from the superposition of single-star spacetimes. Our results demonstrate that evolutions starting from a plain superposition of individual boosted boson-star spacetimes are vulnerable to significant unphysical artefacts. These difficulties can be overcome with a simple modification of the initial data suggested in [PRD 99 (2018) 044046] for collisions of oscillatons. While we specifically consider massive complex scalar field boson star models up to a 6th-order-polynomial potential, we argue that this vulnerability is universal and present in other kinds of exotic compact systems and hence needs to be addressed.

gr-qc↗

arXiv2019

Investigating two counting methods of the holographic complexity

We investigated the distinction between two kinds of "Complexity equals Action"(CA) conjecture counting methods which are separately provided by Brown $ et\, al. $ and Lehner $et\, al.$ separately. For the late-time CA complexity growth rate, we show that the difference between two counting methods only comes from the boundary term of the segments on the horizon. However, both counting methods give the identical late-time result. Our proof is general, independent of the underlying theories of higher curvature gravity as well as the explicit stationary spacetime background. To be specific, we calculate the late-time action growth rate in SAdS black hole for F(Ricci) gravity, and show that these two methods actually give the same result. Moreover, by using the Iyer-Wald formalism, we find that the full action rate within the WDW patch can be expressed as some boundary integrations, and the final contribution only comes from the boundary on singularity. Although the definitions of the mass of black hole has been modified in F(Ricci) gravity, its late-time result has the same form with that of SAdS black hole in Einstein gravity.

hep-th↗