Xin Zhang

We investigate the dynamical stability and phase transition behavior in a holographic superfluid model incorporating higher-order self-interaction terms λ | ψ | 4 , τ | ψ | 6 and a non-minimal coupling h ( ψ ) = e α | ψ | 2 . Thermodynamic and dynamical stability analyses show that the thermodynamic stability and dynamical stability of the system are consistent. Phase diagram analysis reveals rich critical and supercritical phenomena. For fixed λ < 0 and α , increasing τ shrinks the first-order phase transition region to a critical point and then enters the supercritical region. When varying α , the system can exhibit no critical point or, most notably, a double critical phenomenon in which, as α increases, the system first enters the supercritical region and then re-enters the first-order phase transition region. This double critical phenomenon driven by a single parameter is reported for the first time in holographic superfluid models, revealing a complex nonmonotonic coupling effect between the non-minimal coupling and higher-order interaction terms.

Entropy production in cosmological nonequilibrium processes can be difficult to characterize when intermediate states lack a well-defined local thermodynamic entropy. Motivated by monopole production and strongly supercooled cosmological phase transitions, we introduce the equilibrium-completion entropy potential (ECEP), a counterfactual measure of equilibrium entropy capacity. For a given underlying theory, the Landau-frame energy density of the actual local state defines a maximum-entropy equilibrium-completion state, whose equilibrium entropy density gives the ECEP. We derive an exact local identity relating the divergence of the associated ECEP current to the mismatch between the actual and equilibrium-completion stresses, and develop corresponding finite-domain balance and resolved-hard matching formulations. As cosmological benchmarks, we show that a strictly equilibrium crossover transition conserves comoving ECEP despite changes in the equation of state and relativistic degrees of freedom, while the equilibrium-completion target of a first-order phase transition generally includes the phase-coexistence branch.

The direct detection of gravitational waves (GWs) by LIGO has confirmed general relativity (GR), but testing GR via GWs requires estimating parameterized post-Einsteinian (ppE) deviation parameters in waveform models. Traditional Bayesian inference methods like Markov chain Monte Carlo (MCMC) provide reliable estimates but suffer from prohibitive computational costs, failing to meet the real-time demands and surging data volume of future GW detectors. Here, we propose a factorized neural posterior estimation framework: we construct independent normalizing flow models for each of the nine ppE deviation parameters, and effectively integrate prior information from other source parameters via a conditional embedding network. Leveraging a hybrid neural network with a convolutional neural network and a residual neural network for feature extraction, our method performs rapid and statistically reliable posterior inference directly from binary black hole signals. Compared to conventional MCMC, our approach achieves millisecond-scale inference time with a speedup factor of 9 × 10 4 . Comprehensive validations show that the posterior estimates pass the Kolmogorov–Smirnov test and achieve empirical coverage probabilities close to theoretical targets. We apply this method to the GW150914 event and find that the resulting posterior distributions are in good agreement with existing results. This work demonstrates the great potential of deep learning for GW parameter estimation and provides a viable technical solution for real-time GR tests with next-generation detectors.

In the JWST and DESI era, the JWST high-redshift galaxy observations and DESI baryon acoustic oscillation (BAO) measurements severely challenge the standard ΛCDM model, while the H ₀ tension becomes increasingly prominent. In this work, we investigate the capability of the early dark energy (EDE) model to alleviate the H ₀ tension utilizing cosmic microwave background (CMB) data from Planck, the Atacama Cosmology Telescope, and the South Pole Telescope, BAO data from DESI, and ultraviolet luminosity function observations from the JWST. Within the canonical Axion-EDE framework, the CMB+DESI+JWST data significantly increase the H ₀ value to 71.58 ± 1.05 km s ⁻¹ Mpc ⁻¹ , with the residual H ₀ tension quantified by Q _DMAP reduced to 0.6 σ . Simultaneously, this model improves the fit to the JWST data and exhibits statistical performance significantly better than the ΛCDM model, with Δ χ tot 2 = − 18.26 and a change in the deviance information criterion (DIC) of ΔDIC = −11.89. Our results highlight the complementary advantages of JWST high-redshift galaxy data alongside early- and late-time observations in testing EDE and alleviating the H ₀ tension.

With the increasing number of high-precision astronomical observations, physical quantities that were previously inaccessible to accurate calculations, such as cosmic birefringence, have once again become a focal point of interest. Such phenomena induce a nonvanishing cross-correlation between the E - and B -mode polarizations of the cosmic microwave background (CMB), thereby providing a direct observational signature of parity violation. The Chern-Simons coupling between the scalar field in early dark energy (EDE) models and CMB photons is regarded as a plausible mechanism for generating cosmic birefringence. Recent data from the Atacama Cosmology Telescope (ACT) deliver EB measurements at higher multipole moments than those previously achieved by Planck, while DESI and PantheonPlus datasets provide new and stringent constraints on the late-time expansion history. Using a joint analysis of Planck, DESI DR2, PantheonPlus, and ACT data, we perform a full-parameter constraint on the cosmic birefringence effects induced by the EDE-CMB photon coupling. Our results favor a higher Hubble constant, H ₀ = 76.9 ^+2.9 _-2.5 km s ^-1 Mpc ^-1 , and a relatively large EDE fraction, f _EDE = 0.232 ^+0.074 _-0.047 . By comparing the cosmological evolution of this model across different data combinations, we find that the ACT- EB data combined with Planck + DESI + PantheonPlus provide consistent constraints.