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The hypothesis of strange quark matter (SQM) and the possible existence of strange stars have been extensively investigated within the thermodynamic bag model, typically employing the free Fermi gas approximation with or without perturbative QCD corrections at zero temperature, where quark confinement is modeled by the bag pressure. In this work, based on the perturbative inclusion of quark mass effects, we develop a thermodynamically consistent equation of state (EOS) for SQM at finite temperature, incorporating perturbative corrections up to $\mathcal{O}(α_s)$ in the strong coupling constant $α_s$ while ensuring full adherence to the Maxwell relations. These corrections are essential for accurately describing hot quark stars potentially formed during core-collapse events. We present results for both fixed and running couplings, using a phenomenological model to include the breakdown of the perturbative running of $α_s$ at low momenta. Our results demonstrate that incorporating finite-temperature perturbative QCD corrections leads to SQM configurations that fall within the absolute stability window, with equilibrium energies per baryon lying below that of iron, the most tightly bound nucleus. Our EOS supports compact stars with masses exceeding $1.4\,M_\odot$ (and above $2\,M_\odot$ for some values of the bag constant), in agreement with current astrophysical constraints from pulsar and gravitational-wave observations.

In this paper, we report on the dynamics of the fine structure of a solar quiescent filament observed on September 28, 2023, with the Télescope Héliographique pour l'Etude du Magnétisme et des Instabilités Solaires (THEMIS). The main aim is to understand the relationship between the supersonic downflows measured in H$α$ at the filament end and an associated coronal bright point. We use a cloud-model method to derive the supersonic velocity of the falling, elongated cool blob. Besides, we use H$α$ Global Oscillation Network Group (GONG) data to track the plasma along the filament. Repetitive plasma motions are observed along the northern end of the filament. During one event of plasma motion, the THEMIS field of view was centred on the filament end, where supersonic downflows of 89.8 km s$^{-1}$ were measured with a standard deviation of $\pm$0.25 km s$^{-1}$. We suggest that the plasma moving along the filament could be falling towards the chromosphere. A ballistic trajectory could confirm this first scenario. However, we could not rule out the second scenario, in which coronal rain forms due to the thermal instability of coronal plasma. In the hot AIA channels, we identify a bright point at the same location, with a temperature reaching about 6 MK. In addition, we confirm a counter-streaming flow pattern along the fine filament strands, with widths of less than an arc second, as measured by the high-spatial- and spectral-resolution spectra of THEMIS.

The tip of the red giant branch (TRGB) can be used as a relative distance measure as part of the cosmic distance ladder to infer the Hubble constant. We present a Bayesian framework for TRGB inference that incorporates selection effects and propagates per-star uncertainties, modelling the observed catalogue as a realisation of an inhomogeneous Poisson point process which includes the RGB and contamination from the asymptotic giant branch (AGB). We derive expressions for the predicted TRGB uncertainty in terms of the photometric noise, stellar density fainter than the tip, and the ratio of the AGB to AGB+RGB number densities, $r$. We validate these using synthetic data from a simplified luminosity function. Applying the full model to synthetic catalogues, we find that the dependence on $r$ is the strongest of the three, and that reliable inference requires $r \lesssim 0.5$; beyond this, the posterior is multimodal, and the TRGB cannot reliably be identified. We then fit data from 11 Hubble Space Telescope fields of the calibrator galaxy NGC 4258. We find intrinsic field-to-field scatter beyond measurement noise of $τ= 0.067^{+0.023}_{-0.017}$ mag, and a galaxy-level, extinction-corrected TRGB magnitude of $25.324 \pm 0.026$. Combining this with the maser distance to NGC 4258, we determine the absolute magnitude of the TRGB to be ${M}_{\rm{F814W}}^{\rm{TRGB}} = -4.073 \pm 0.026$ (tip) $ \pm$ $0.032$ (dist), consistent with, but brighter than, other recent analyses of the same data.

Equations of state (EoS) for dense matter are commonly provided in tabulated pressure-energy density relations, complicating numerical implementation and potentially compromising thermodynamic consistency. In this work, we propose a universal, piecewise-continuous functional form with a common parametrization capable of representing a broad class of dense matter EoSs. We validate this parametrization against tabulated EoSs from the CompOSE and LALSimulation repositories. Following the initial deterministic fitting, we employed two distinct Bayesian approaches: one based on synthetic EoSs generated by adding noise to the fitted EoS and another based on multimessenger measurements of neutron-star masses and tidal deformabilities. In both approaches, the initial best-fit parameters are used as reference values. For the considered EoSs, spanning from very soft to very stiff, the resulting fits reproduce the defined tabulated EoSs and the associated macroscopic neutron-star observables in the repositories with sufficient degree of accuracy. The inferred parameters exhibit strong correlations arising from the continuity conditions imposed at the segment boundaries. These correlations persist in the low- and intermediate-density segments under multimessenger inference but become weak in the core, reflecting the limited constraining power of current observations at high densities. The ability of a single functional form to describe EoSs derived from different microscopic frameworks, together with the recurrence of similar parameter correlations, suggests that diverse dense matter EoSs may share a common underlying structure.

We investigate primordial black hole (PBH) formation during an early matter-dominated era using fully nonlinear numerical relativity. The initial condition is set by a functional form of the curvature perturbation including ellipticity, which makes the configuration triaxial. Two kinds of matter descriptions are considered: dust fluid and collisionless particles. In the dust fluid description, numerical computation crashes associated with the appearance of a singularity at which the fluid density diverges, unless the singularity is hidden well inside the apparent horizon. We found that, for the dust fluid description, to observe the horizon formation before calculations crash, the initial amplitude must be larger than the previous analytic estimation by a factor of 2. On the other hand, with the particle system description, calculations do not crash, and we may observe black hole formation after subsequent evolution of the system. Then the threshold of black hole formation is significantly smaller than the previous analytic estimation by an order of magnitude.

The intracluster medium (ICM) in merging galaxy clusters exhibits turbulence and bulk flows. Unraveling these components is crucial not only for elucidating the geometry of the cluster mergers, but also for understanding the physics of magnetic field amplification and relativistic particle acceleration. XRISM/Resolve data for two $3'\times3'$ fields in the core of the Coma cluster reveales that the ICM in the central field moves with $Δcz = -430$~km~s$^{-1}$ relative to the cluster galaxy average, while that in the southern field moves with $Δcz = -730$~km~s$^{-1}$ (see \cite{2025ApJ...985L..20X}, hereinafter ``Paper I''). In this paper, we perform a more detailed analysis of these data sets to search for non-Gaussian features in the Fe-K line complex profiles. In the spectra from the northwest (NW) quadrant of the central field, in addition to the main and redshifted ICM components ($Δcz = -40$ km s$^{-1}$) reported in Paper I, we find evidence of another, blueshifted component, moving with $Δcz = -1250$ km s$^{-1}$. For a systematic search for other significant velocity components, we perform a bias-free 3 eV step multi-component fit to the Resolve full-array spectra from the central and southern fields. This search uncovers another redshifted component in the southern field, moving with $Δcz \sim +1230$ km s$^{-1}$. We estimate the energy densities of the ICM turbulence and bulk motion to be similar to each other and several times greater than the energy density of the cluster's $B\sim 5~μ$G magnetic field.

Ringdown gravitational waves from binary black hole mergers can be modeled as superpositions of quasinormal modes (QNMs), whose frequencies and excitation factors encode properties of the remnant Kerr black hole. Reliable extraction of multiple QNM components is challenging because of mode overlap and noise. We develop an autoencoder-based framework for multi-component QNM analysis, in which the latent space is trained to represent the physical parameters of individual modes, enabling waveform denoising and parameter estimation within a common framework. Using controlled model waveforms constructed as finite sums of Kerr QNMs with recently established high-precision frequencies and excitation factors, including their nontrivial spin dependence near resonant excitation, we assess the method across partitioned spin intervals. The model achieves good in-domain waveform reconstruction and parameter recovery for the two longest-lived components of eight-component input waveforms, while its performance degrades when the validation spins lie far outside the training range. In a selected spin interval, the framework also recovers the 32 parameters of an eight-component waveform with good overall agreement. These results demonstrate the feasibility of physics-informed autoencoder-based inference for a prescribed multi-component ringdown waveform family and motivate further tests with progressively more realistic signals.

We investigate the quasinormal spectra and time-domain evolution of scalar, electromagnetic, and gravitational perturbations of the Einstein-Bronnikov black hole in Einstein gravity coupled to nonlinear electrodynamics. The effective potentials associated with all perturbation sectors are shown to form positive potential barriers that vanish at the event horizon and spatial infinity. Their height increases with the magnetic charge, while the scalar perturbation possesses the largest potential barrier. Unlike the Reissner-Nordström black hole, axial and polar electromagnetic perturbations are characterized by distinct effective potentials, demonstrating the breaking of isospectrality due to nonlinear electrodynamics. Quasinormal frequencies are computed using the sixth-order WKB approximation and the asymptotic iteration method, yielding excellent agreement for both fundamental and higher overtone modes. The oscillation frequencies increase monotonically with the magnetic charge, whereas the damping rates exhibit only moderate variations, confirming the linear stability of the Einstein-Bronnikov black hole under all perturbations considered. Time-domain profiles display exponentially damped ringdown signals consistent with the frequency-domain analysis. These results demonstrate that nonlinear electrodynamics leaves measurable imprints on black hole perturbations and may provide observational signatures for testing regular black hole geometries through future gravitational wave observations.

We apply the quadratic balance relation for linear nonadiabatic pulsations to radial modes of a sequence of post-AGB envelope models covering $3.52\leq\log(T_{\rm eff})\leq4.6$. The relation separates the thermodynamic exchange power $\mathcal{P}_{\rm ex}$, response power $\mathcal{P}_{\rm rsp}$, and surface contribution $ΔB$, and introduces an effective norm through $\mathcal{P}_{\rm ex}+ΔB=2γχ_{\rm eff}\mathcal{E}_{\rm kin}$, where $γ$ is the mode growth rate. For nearly adiabatic modes $χ_{\rm eff}$ is close to unity, whereas in strongly nonadiabatic pulsations the compression and horizontal area deformation contributions can make it change magnitude or even reverse its sign. In the cooler models, a broad family of overtone modes has $χ_{\rm eff}<0$ and is damped despite positive thermodynamic exchange power. For these modes the response power supplies the opposing damping. Conversely, two low frequency modes in the hotter models are excited over a range of effective temperatures, even though their thermodynamic exchange power is negative. Their instability is produced by the positive response power. Strange modes generally have $χ_{\rm eff}>0$, apart from a narrow boundary-sensitive transition during which a cold strange mode transforms into an ordinary p-mode. The excited low frequency solution with $χ_{\rm eff}<0$ persists with a finer numerical mesh and such modes are found under the alternative outer boundary formulations examined, although their frequencies are boundary condition dependent. Thus, for strongly nonadiabatic pulsations, the sign of the thermodynamic exchange power alone does not determine mode stability.

By analyzing slit scanning spectral data obtained during 2024 total solar eclipse, presence of neutral atom corona is revealed along with a hidden inner F-corona detected within heights below half a solar radius. The inner F-corona is found to be essentially different from the Fraunhofer corona formed by dust scattering beyond about 2.3 solar radius heights. The two new kinds of the solar corona are deduced from the intensity difference between the spectral line intensity distribution and their adjacent continuum one acquired during the totality. Through analysis of the recorded spectra ranging from 516.0nm to 540.7nm, the relative depths of strong Fraunhofer lines are found to be changed among the neighboring lines from one place to another and from the photospheric lines acquired before the eclipse. Thus the resonant scattering is regarded to be responsible for the changes. Furthermore, shown in the reconstructed maps at selected spectral lines, the detected inner F-corona is found spreading globally and the neutral atom scattering acts as its dominant source. Both of their distribution patterns generally depend on specific lines and show considerably asymmetrical diffusions. The outward neutral fluxes are observed to be mainly hindered in regions of coronal magnetic loops with roughly estimated concentration above $10^{-5}$. Thus it can play a key role in global coronal heating via Cowling dissipation in these widely spread coronal loops, like heating in Tokamak by neutral beam injection(NBI). The Cowling dissipation can give a consistent interpretation of heating from the chromosphere to the corona. Thus the neutral atom corona is not only a new gradient of the solar corona but also the missed factor critical for concatenating together these coronal heating mechanisms.

We investigate solar-neutrino spin--flavor precession (SFP) induced by magnetic moments in the three-active-flavor framework. For Majorana neutrinos, SFP can convert solar neutrinos into antineutrinos of different active flavors. In the Dirac case, SFP instead produces sterile right-handed states and can lead to the disappearance of active neutrinos. Using the full $6\times6$ Hamiltonians and GS98 and AGSS09 solar profiles, we examine propagation-eigenvalue crossings at $B_\perp=0$ and the projected magnetic couplings between the corresponding states. For normal mass ordering and $1\leq E_ν/\mathrm{MeV}\leq20$, we confirm the absence of finite-density Majorana crossings. A magnetically coupled Dirac crossing emerges above approximately $12~\mathrm{MeV}$ but involves only a subdominant electron-flavor component, limiting resonant disappearance. Nonresonant Majorana conversion nevertheless offers a distinctive lepton-number-violating solar $\barν_e$ signal, motivating our sensitivity study for the Jinping Neutrino Experiment. For a proposed $3~\mathrm{kt}$ detector operating for five to ten years, we project a 90\% C.L. sensitivity of $P(ν_e\to\barν_e)\simeq(0.85-1.3)\times10^{-5}$. In the $μ_{12}$-only benchmark, optimistic solar-core transverse magnetic fields of $B_\perp=7-10~\mathrm{MG}$ imply a reach of $|μ_{12}|\simeq(2.3-4.1)\times10^{-13}\,μ_B$, numerically below existing direct-scattering limits and commonly quoted stellar-cooling bounds. This could enable Jinping to provide one of the most stringent projected terrestrial sensitivities to Majorana transition magnetic moments.

[Abridged] In this work, we compare neutron stars where dark energy or dark matter are present in the core, contrasting them against purely baryonic stars with the same central energy density. From this comparison, we find that the dark energy models are more constrained by neutron star observations than the dark matter models, suggesting that neutron stars can place strong constraints on dark energy parameters. We consider four configurations: purely baryonic neutron stars described by a piecewise polytropic (PP) equation of state (EoS), baryonic stars admixed with bosonic or fermionic asymmetric dark matter (ADM) cores, and stars with a dark energy core and baryonic shell, where the dark energy is described by the modified Chaplygin dark fluid (MCDF). Using the masses and radii of PSR J0740$+$6620, PSR J0437$-$4715, and PSR J0030$+$0451, we employ Bayesian inference to investigate how accounting for bosonic/fermionic ADM and MCDF cores affects the inferred neutron star properties. We find that MCDF cores, more than PP and ADM admixed models, substantially broaden neutron star mass-radius and pressure-energy density posterior distributions. Moreover, the MCDF EoS parameters can be tightly constrained. While bosonic and fermionic ADM cores decrease the inferred maximum mass, their posteriors strongly coincide with those of the PP model for ADM mass-fractions $F_χ\leq 5\%$. These results demonstrate that current mass-radius observations cannot rule out MCDF cores, but they can constrain the MCDF parameter space to narrow regions. ADM admixed neutron stars, however, remain observationally identical to purely baryonic stars for all explored mass-fractions, even with improved mass-radius uncertainties. This suggests that mass-radius measurements alone are insufficient to detect ADM core inside neutron stars and that independent astrophysical or particle physics probes will be required.

The model of Galactic population of stripped helium stars, the remnants of $5 \lesssim M/M_\odot \lesssim 24$ primary components of close binaries after RLOF is presented. These stars emit in the UV range of the spectrum and may be observed by detectors aboard planned "Spektr-UV" (WSO-UV) space telescope. For the current star formation rate in the Galaxy 2$\mathrm {M_\odot yr^{-1}}$, the estimate of the number of 1 to 7 $M_\odot$ objects with $T_{\rm eff} \gtrsim$25,000\,K ranges from 14700 to 28500. The number of 2 to 7 $M_\odot$ objects is 3200 to 5500. The main evolutionary factor influencing the estimate is possible formation of common envelopes and merger of components in them. Detection of candidate stripped helium stars by UV-excess is hampered by the dominance of main-sequence companions to stripped helium stars in the combined spectra of binaries. This effect of observational selection may reduce the number of candidate stripped helium stars potentially detectable by photometry to $\lesssim 1000$.

Please check the paper for full abstract. The Galactic Center Excess (GCE) is an unexplained excess of gamma-ray emission from the Galactic Center. The GRAINE experiment aims to reveal the origin of the GCE using an emulsion gamma-ray telescope with high angular resolutions of 1 deg at 100 MeV and 0.1 deg at 1 GeV. In this study, we search for the GCE in a small region near the Galactic Center using the GRAINE 2023 flight data. In particular, rather than focusing on the spectral peak of the GCE at 2 GeV, we focused on the energy range below 300 MeV, where the spectral differences between the dark matter annihilation and millisecond pulsar scenarios are more pronounced. We searched for the GCE within 1 deg of the Galactic Center in the 75--300 MeV energy range. Although no significant excess was observed, we obtained an upper limit on the GCE flux of 1.70*10^-7 GeV cm^-2 s^-1 at the 2 sigma confidence level for the 1deg-radius ROI centered on the Galactic Center, based on a direct observation of the narrow region around the Galactic Center. This observation requires high angular resolution and represents a unique result from GRAINE. The obtained upper limit is consistent with the GCE flux near the Galactic Center, which was estimated from existing Fermi-LAT observations using a wide ROI and assuming an NFW profile. Although the current upper limit constrains some models, the available statistics are still insufficient to distinguish between the dark matter annihilation and millisecond pulsar scenarios, and both remain consistent with the current results. We also estimated the projected sensitivity of future GRAINE experiments based on the present observation and demonstrated their potential to probe the origin of the GCE by comparing the projected sensitivity with the predicted GCE spectra.

We consider collisions between particles moving freely in the Schwarzschild background. We suggest classification of scenarios that lead to unbounded energy output in the center of mass frame. Although this is forbidden in the exterior of a black hole, the phenomenon becomes possible with account of white hole region and mirror universe in the complete space-time diagram. Also, we scrutinize collisions in the vicinity of the bifurcation point and reveal the role of resting observers in the inner region beyond the horizon. In some scenarios $E_{c.m.}$ not only diverges but becomes seemingly infinite that is, as a matter of fact, impossible according to the principle of so-called kinematic censorship. We resolve a corresponding paradox and argue, why this principle remains valid.

In this work, we derive phenomenological constraints on a symmetric black-bounce geometry supported by an anisotropic fluid. We investigate the effects of the bounce parameter and the matter parameter on classical and strong-field observables, considering the perihelion advance, light deflection, Shapiro time delay, and black-hole shadow. In the weak-field regime, we obtain analytical corrections to the corresponding general-relativistic predictions and use Solar-System measurements to constrain the parameter space. We find that the matter parameter is generally constrained more strongly than the minimum-radius scale, reflecting the suppressed dependence of weak-field observables on the bounce parameter. In the strong-field regime, we show that the asymptotic shadow radius depends directly on the matter parameter, whereas the bounce parameter enters through the existence condition of the outer unstable photon orbit rather than through an independent correction to the shadow size. These results highlight the distinct roles played by the matter and bounce parameters in weak- and strong-field observables and provide complementary constraints on the parameter space of the symmetric black-bounce geometry.

This paper investigates the holographic Casimir effect in AdS/BCFT with a brane-localized scalar field. The scalar field takes different values at the strip's two boundaries, leading to mixed boundary conditions. The massive brane-localized scalar field typically breaks the boundary conformal symmetries, allowing us to study the holographic Casimir effect in non-CFTs. In two-dimensional spacetime, we apply the holographic g-theorem to prove the holographic bound on the Casimir effect for general brane-localized matter fields. In higher dimensions, we find that the brane-localized scalar field reduces the Casimir amplitude when the mass squared \(m^2=0\), but can increase it when \(m^2 < 0\). Additionally, there is a no-hair theorem for the cases where \(m^2>0\). These findings indicate that relevant boundary deformations can enhance the Casimir effect. As a byproduct, we obtain a gravitational dual of the repulsive Casimir force under mixed boundary conditions and argue that it aligns with the cosmic censorship conjecture.

We study a thick braneworld model in asymptotically anti-de Sitter spacetime, supported by a non-topological lump-type scalar field. Unlike in boson stars, which are also non-topological solutions, the complex scalar field in our setup must have zero oscillation frequency. Consequently, the background scalar field is static and real, which breaks the global $U(1)$ symmetry. This is similar to spontaneous symmetry breaking, but it is not the same. We then investigate the localization of vector and fermion fields within this framework. By introducing a specific non-minimal coupling, we demonstrate that the zero modes of both fields can be successfully localized. Notably, this mechanism allows for the simultaneous localization of both left- and right-handed fermion zero modes.

We study extremal mass branches in four-dimensional Einstein gravity coupled to one dilaton and two Maxwell fields with opposite-sign dilaton couplings. For generic couplings the extremal mass is governed by a nonlinear first-order equation with no known closed-form solution. We prove that this equation has a unique positive $C^2$ solution on the full real charge-ratio line and that the solution is real analytic, so positivity on the entire positive charge cone selects a unique global mass branch. Along this branch, any two nonproportional positive charge vectors attract for $ab>-1$, have vanishing leading force at $ab=-1$, and repel for $ab<-1$. The same transition fixes the transverse convexity of the extremal mass surface and the sign of the mass difference under arbitrary finite positive-charge partitions. The sign theorem extends to higher dimensions through the known dimensional rescaling. A radial reconstruction then shows that every point of the mass branch defines an asymptotically flat exterior with a finite-area inner endpoint, while smooth or analytic horizon extension is a separate condition that restricts the couplings and scalar flow.

The LUX-ZEPLIN experiment has reported a single nuclear recoil candidate at $E_R = 248 \pm 23(\mathrm{stat}) \pm 23(\mathrm{sys})$~keV, disfavouring the background-only hypothesis at a global significance of $2.6σ$. The difficulty such an event poses is not the recoil energy itself but the absence of any accompanying excess at low energy as elastic scattering of halo dark matter yields a monotonically falling spectrum, and supplying the required momentum transfer $q \simeq 246$~MeV already demands $m_χ\gtrsim 79$~GeV. We confront the event with the two kinematically distinct mechanisms that evade this limitation, endothermic inelastic dark matter, in which a mass splitting $δ\sim \mathcal{O}(100)$~keV forbids low-energy recoils and boosted dark matter, in which a light relativistic flux supplies the momentum, treating both with the same model-independent scalar--scalar, pseudoscalar--scalar and pseudoscalar--pseudoscalar effective operators. The two scenarios prove spectrally distinguishable. The inelastic spectra sit near the observed energy for every operator, placing only $6$--$17\%$ of events below 150~keV, whereas the boosted spectra depend critically on the operator: the scalar and pseudoscalar--scalar interactions place $99\%$ and $92\%$ of their events below 150~keV, while the pseudoscalar--pseudoscalar interaction places $75\%$ above it. Momentum dependence is thus essential to the boosted interpretation, but in the inelastic case it trades against the splitting, the preferred $δ$ decreasing monotonically from $\mathcal{O}_{ss}$ to $\mathcal{O}_{ps}$ to $\mathcal{O}_{pp}$. Because the scenarios differ across the whole high-energy window, a handful of additional events would separate them, placing the question within reach of the full LZ exposure.

We develop a general framework for constructing massive black bounce geometries from massless wormhole seeds by introducing a position-dependent mass function while preserving the underlying areal-radius profile. We apply this procedure to the generalized Ellis-Bronnikov wormhole and obtain a new family of generalized Bardeen-like black bounce space-times, which continuously interpolates between traversable wormholes and regular black holes. We investigate the motion of massive particles and photons and show that, in contrast with the simpler orbital structure of the massless generalized Ellis-Bronnikov geometry, the generalized Bardeen-like space-time can exhibit multiple circular orbits and a rich light ring structure, including configurations with two unstable circular photon orbits separated by a stable one. We determine the corresponding photon sphere and shadow radii and compare our predictions with Event Horizon Telescope observations of Sgr A*, deriving observational constraints on the parameter space of the model. We further investigate the optical appearance produced by a geometrically and optically thin accretion disk through ray tracing. Multiple light rings generate characteristic nested structures in the high-resolution intensity profiles, whose relative brightness is strongly affected by the mass deformation and gravitational redshift. However, after modeling the finite angular resolution of the EHT with a Gaussian beam convolution, these fine structures are largely washed out, revealing a strong observational degeneracy between these exotic compact objects and standard black hole geometries at current EHT resolution.

We propose a hybrid inflation model based on gauged scale symmetry, in which an axion-like field drives inflation while the Standard Model Higgs serves as the waterfall field. During slow-roll inflation, the Higgs is trapped in the electroweak-symmetric vacuum. When the inflaton reaches a critical value, the Higgs acquires a nonzero vacuum expectation value and and triggers electroweak symmetry breaking (EWSB) through the waterfall dynamics. We identify viable parameter regions that simultaneously accommodate current cosmic microwave background observations and Higgs data from the Large Hadron Collider. The relaxation mechanism connects the inflationary and electroweak scales by reducing the large vacuum-energy contribution required during inflation. Our framework thus provides a dynamical connection between inflation and EWSB.

Recent observations suggest intrinsic links between the stellar components of massive halos and their assembly histories. Using massive halos with $\log[M_{\rm halo}/M_\odot] \geq 13.0$ from the IllustrisTNG-300 simulation, we explore differences in secondary halo properties between samples selected by central galaxy stellar mass and satellite richness. For group-like masses, we find that halos selected by the outskirts stellar mass of their central galaxies between 50 and 100 kpc ($M_{\star,[50,100]}$) have similar halo mass distributions to those selected by intrinsic satellite richness ($λ_{10, R_{200}}$), but differ significantly in assembly history: $M_{\star,[50,100]}$-selected halos are more concentrated and formed earlier. At higher masses ($\sim10^{14}~M_\odot$), intrinsic richness becomes the better halo-mass proxy, but only when projection effects are ignored. We find that the difference-set test selects comparable halo-mass samples most effectively when the two proxies have similar scatter. Projection effects and baryonic physics do not alter the main trends but remain important caveats for observational applications. Our findings show that the central stellar mass-richness plane is a powerful tool for selecting halos with particular accretion histories, offering new insights into the galaxy-halo connection in the era of deep imaging and precision lensing surveys such as Euclid and LSST.

In Einstein-Cartan spinor gravity under the irreversible vierbein postulate, only the spinor among the first-order variables has a kinetic term of its own at tree level. Any nonzero background vierbein breaks the local-Lorentz (LL) symmetry spontaneously. Our previous work showed that the spinor loop generates the kinetic and mass terms of the LL gauge field, manifesting LL as a hidden local symmetry. Here we show that the spinor loop also generates the vierbein two-point function, while respecting the background gauge invariance and satisfying the Ward-Takahashi identities of the true gauge invariance, for both the general-coordinate and LL symmetries. The scheme-independent logarithmic divergence assembles the familiar induced-gravity ingredients: a cosmological constant, an Einstein-Hilbert and a Weyl-squared term for the metric sector, and a mass and a higher-derivative kinetic term for the totally antisymmetric torsion. In the vierbein sector, this torsion is carried by the derivative of the antisymmetric part of the linear vierbein fluctuation. This part is the would-be Nambu-Goldstone boson of the spontaneously broken LL symmetry, and its couplings in the minimally coupled action are all fixed by general-coordinate and LL gauge invariance. The five induced terms form a single effective action, manifestly invariant under both symmetries, completing the vierbein sector of the hidden-local-Lorentz emergent-gravity scenario.

Perturbative quantum gravity is ultraviolet divergent and, as shown by 't Hooft and Veltman, non-renormalizable. A recent object-relative, Lorentz-invariant weighting of internal electromagnetic modes renders selected one-loop contributions of quantum electrodynamics finite without counterterms. Here that weighting is derived rather than postulated: causality defines a mode resonator bounded by the Hubble radius and re-defined in every inertial frame, and the self-gravitation of each mode quantum deforms its spectrum. Applied to linearized gravity, the graviton self-coupling reaches order unity at the Planck wave number, so that the mode content available to a loop is suppressed beyond it. Any suppression exceeding a threshold fixed by the diagram renders the one-loop integrals finite; no cutoff is imposed and no mode structure above the Planck scale need be derived. For pure gravity the same power counting extends to every loop order, and the leading suppression already meets the resulting condition for every topology with more than one vertex; a single class of single-vertex insertions is excluded. The Bianchi identity takes the role of the Ward identity at one loop, and the transformation between the resonators of two inertial frames is unitary. The same finite mode content yields a vacuum energy density of order H^2/G, of the observed sign and magnitude, from the Planck and causal infrared wave numbers alone. A contribution tracking the instantaneous expansion rate is an exact rescaling of the gravitational constant and is excluded by primordial nucleosynthesis, so the mode basis must be frozen in any inertial system; referring it to the stationary de Sitter horizon fixes the remaining coefficient to the geometric value 6/pi and makes a value for the energy density of gravitational vacuum fluctuations possible which can be interpreted as origin of the dark-energy effect.

We study whether orbital redistribution in a self consistent spherical Einstein--Vlasov environment can change the asymptotic normalization of a black hole horizon while the horizon mass, particle rest mass and ADM mass are all held fixed. The matter variable is the occupation of regular bound orbital actions, so the stress tensor, orbital energies and gravitational field are determined by the same distribution. Linearization of the spherical mass constraint gives a kinetic variation law in which orbital energy is conjugate to occupation and the inner lapse ratio multiplies the horizon mass variation. On a locally regular equilibrium branch, mixed variations imply an integrated reciprocity relation between the central mass derivative of orbital energy and the directional response of the horizon normalization. We construct finite mass populations and trace constant mass redistribution curves. For the reference rest mass ratio $0.30$, the calculated endpoint surface gravity shifts are approximately $+15.37$ and $-15.33$ parts per million. The constrained response cancels at simultaneous dilute and Newtonian order, is nonzero for exact Schwarzschild orbits, and is further modified by self gravity. Independent balance, integral, derivative and refinement tests resolve the response well below its reported magnitude.

Observations have established that the circumbinary discs formed around post-asymptotic giant branch (post-AGB) binaries have striking similarities to protoplanetary discs around young stars. In this study, we examine the feasibility of the different stages of growth in the core accretion framework of planet formation in post-AGB discs, in order to assess whether planet formation is possible in these systems. We find that dust coagulation up to mm sizes is possible within the lifetimes of post-AGB discs, consistent with observations. We then investigate the subsequent growth of planetesimals through pebble and planetesimal accretion. If the streaming instability operates in these discs, the resulting planetesimals formed in higher-mass post-AGB discs ($M_{\rm disc}\sim0.1M_\odot$) can enter rapid pebble accretion and reach their isolation mass within the estimated disc lifetime. By contrast, in lower-mass post-AGB discs ($M_{\rm disc}\sim0.01M_\odot$), planetesimal accretion is too inefficient to produce substantial further growth. We also show that the larger aspect ratios of post-AGB discs compared to protoplanetary discs around young stars imply high pebble isolation masses and therefore potential formation of rocky planets with masses extending up to Jupiter masses. After assessing gas accretion and concurrent migration in these discs, we conclude that second generation planet formation in post-AGB discs is theoretically possible within their estimated lifetimes ($10^4$--$10^5$yr) provided that local dust-to-gas ratio enhancements and sufficiently high disc masses are achieved.

A cosmological source can have identically zero comoving energy density and still gravitate through its pressure. This differs from an energy density passing through zero at an isolated time. Maintaining zero density with nonzero pressure requires energy exchange in a nonstatic FLRW universe. We construct proportional-pressure and constant-pressure backgrounds, including steady-state, bouncing, recollapsing, and $Λ$CDM expansion histories, and relate them to creation pressure, bulk viscosity, and time-dependent vacuum descriptions. Scalar fields can realize zero density along a trajectory; imposing it as an identity on a timelike $P(X,φ)$ domain selects $P=A(φ)\sqrt{X}$, locally a signed potential-free cuscuton for nonzero $A$. We formulate linear perturbations without dividing by the vanishing background density. For a nondegenerate $P(X,φ)$ scalar with a timelike field gradient, zero density and negative pressure cannot coexist with positive kinetic and gradient coefficients when the interaction leaves its principal kinetic structure unchanged. Two models couple the scalar to number-conserving dust through a field-dependent mass. The proportional-pressure trajectory is a homogeneous saddle and has no growing power-law dust mode on its accelerating branch in the matter-sourced quasistatic subhorizon approximation. A distinct constant-pressure model reproduces the $Λ$CDM expansion history, but in the same approximation the dust mode that initially grows during matter domination reaches a maximum at low redshift and then decays. These restrictions apply to the stated scalar class and models. Exact Bianchi I solutions demonstrate separately conserved zero-density sources supported by anisotropic stress. An inverse-pressure construction distinguishes the density of an interacting constituent from an inferred dark-energy density that may cross zero.