We test the hypothesis of $K(1460)$ being a hadronic $J^P=0^{-}$ molecule through nonperturbative $S$-wave $KK\overline{K}$, $K\pi \pi$, $K\pi \eta$ coupled-channel dynamics in a three-body unitary isobar approach. The scalar two-body coupled-channel resonances $f_0(500)$, $f_0(980)$, $a_0(980)$, and $K_0^{*}(700)$ are generated in the subsytems in amplitudes that match phase shifts from experiment. In a first step, previous results in the limit of mass-degenerate, stable $f_0$ and $a_0$ isobars are reproduced. Once the full seven-coupled channel model is switched on, other $S$-matrix effects obscure and modify the resonance signal, including complex thresholds, a two-body cusp, and a triangle singularity at threshold.

We consider the most general form of soft and collinear factorization for hard-scattering amplitudes to all orders in perturbative quantum chromodynamics. Specifically, we present the generalization of collinear factorization to configurations with several collinear directions, where the most singular behavior is encoded by generalized collinear splitting amplitudes that manifestly embed the breaking of strict collinear factorization in spacelike collinear configurations. We also extend the analysis to the simultaneous soft-collinear factorization with multiple collinear directions where naive multiplicative factorization does not hold. As an illustrative example of factorization breaking, we present explicit results at the one-loop level in the soft-collinear limit.

We propose a new supersymmetry index for the D1-D5 conformal field theory (CFT) for $T^4$, relevant to the ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ correspondence. In a novel formulation of symmetric orbifold CFTs based on the Schur-Weyl duality, we show how this index can be naturally described and its protection is argued based on the detailed nature of exactly marginal operators in these theories. This index is a one-parameter generalization of the standard index and gives more fine-grained information about the structure of microstates than previously available. We demonstrate precise matching of the new index between supergravity and CFT below the black-hole threshold, where the standard index—the modified elliptic genus—is trivial. Above the threshold, we uncover a decomposition of black-hole microstates into distinct sectors, invisible to the modified elliptic genus.

Near-horizon (equivalently high acceleration) observers in spherically symmetric black hole spacetimes have a particularly simple form of the quasilocal energy. Using this energy and indistinguishable area quanta satisfying quantum statistics, a statistical mechanical description of the Schwarzschild black hole geometry for uniformly accelerating observers is developed. The resulting model has several phases including one with highly excited states, Bose-Einstein condensates, condensates distinct from the usual Bose gas, and degenerate Fermi gases. In the large area limit, relevant for comparison to the Bekenstein-Hawking entropy, the new condensed state is favored over Bose-Einstein condensation and the degenerate Fermi gas. The entropies of the phases, and the entropy of mixing, are computed. The resulting low-entropic condensed state, in which the quanta are essentially all in the lowest Bose energy state, provides the framework for the quantization of near-horizon geometric fluctuations, which is explored in S. Major et al. [arXiv:2601.08794].

In this paper, we revisit the interpretation of the circular Unruh effect. To this aim, we rely on the principle of general covariance applied to the decay properties of noninertial particles. Specifically, we show how the tree-level decay rate of an inverse-$\beta$ process involving scalar fields does not require the introduction of a thermal (or nonthermal) bath in the comoving frame to be a scalar under general coordinate transformations. Instead, we interpret any decay process as an emission of negative-energy quanta, whose existence is motivated by the absence of a global vacuum state for uniformly rotating observers. This implies that, in principle, no uniformly rotating particle can be regarded as stable.

We study the tree-level scattering of massless scalars followed by an emission of a soft graviton in the small compact region inside the static patch in de Sitter space. We derive in the small cosmological constant limit the perturbative corrections to the Weinberg soft graviton theorem. Exploiting the remarkable relationship between asymptotic symmetries and soft theorems in flat space, we derive perturbative corrections to the supertranslation Ward identity. We further show that the derived supertranslation Ward identity reduces to the perturbative soft graviton theorem for the same choice of the supertranslation parameter as in flat space.

It is expected that a quantum theory of gravity will radically alter our current notion of spacetime geometry. However, contrary to what was commonly assumed for many decades, quantum gravity effects could manifest in scales much larger than the Planck scale, provided that there is enough coherence in the superposition of geometries. Quantum clocks, i.e., quantum mechanical systems whose internal dynamics can keep track of proper-time lapses, are a very promising tool for probing such low-energy quantum gravity effects. In this work, we contribute to this subject by proposing a spacetime-covariant formalism to describe clocks in first quantization. In particular, we account for the possibility of dynamically accelerated clocks via suitable couplings with external fields. We find that a particular decomposition of the (quadratic) clock Hamiltonian into positive- and negative-mass sectors, when attainable, enables one to compute the evolution of the system directly in terms of the clock’s proper-time while maintaining explicit covariance. When this decomposition is possible, the evolution obtained is always unitary, even with couplings with external fields used to, e.g., accelerate the clocks. We then apply this formulation to compute the joint time evolution of a pair of quantum clocks in two cases: (i) inertial clocks with relative motion and (ii) charged clocks accelerated by a uniform magnetic field. In both cases, when our clocks are prepared in coherent states, we find that the density matrix ${\rho }_{{\tau }_2|{\tau }_1}$ describing time measurements of the two clocks yields not only conditional probabilities whose peaks match exactly the classical expected values for time dilation, but also yields coherent quantum fluctuations around that peak, with a profile that is either (i) a pure Gaussian or (ii) a Gaussian combined with a periodic modulation.

We investigate the superradiant instability of Kerr-Newman black holes in the presence of a massive, charged scalar field using the Vieira-Bezerra-Kokkotas (VBK) method. We study the solutions of the exact polynomial condition for quasibound state frequencies and determine the domain of superradiant instability in parameter space without relying on the hydrogenic approximation or numerics. We derive the minimum scalar mass needed for quasibound states to exist, and identify the precise overlap region between the quasibound and superradiant conditions where instability can occur. We obtain perturbative and exact analytic expressions for the instability boundaries and growth rates, and clarify their relation to previous numerical results. Our analysis reveals how the instability region shifts from nearly neutral Kerr black holes for light fields to highly charged near-extremal Kerr-Newman black holes for heavier fields, while remaining absent in the Reissner-Nordström limit.

The perturbation spectra of black holes beyond standard vacuum black hole solutions within general relativity (GR) may exhibit complex structures with long-lived modes. This usually generates echolike modulations on the ringdown signal, which typically originate from modified boundary conditions associated with exotic compact objects. Recent studies also reveal that they can instead arise from the multipeaked structure of the perturbation potential. However, while some case-by-case studies have been carried out, a framework for understanding the internal structure of such spectra, the physical nature of different mode families, and their dynamical excitation remains to be fully systematized. In this paper, we address this issue by proposing a potential methodology that combines frequency-domain classification with time-domain analysis, using a hairy Schwarzschild black hole that admits a double-peak perturbative potential as a theoretical platform. Our analysis of the quasinormal mode spectrum identifies two distinct families of modes: the photon sphere (PS) family, arising from delocalized scattering resonances, and the echo family, corresponding to highly localized quasibound states. We then develop a windowed energy analysis framework in the time domain, which discloses a dynamic competition for dominance between these families. In particular, our results explicitly show that this competition is sensitive to the properties of the initial perturbation source, and that higher-overtone echo modes can dominate in the observed signal, which are in contrast to the standard PS mode in GR. This study establishes the dynamic evolution of this energy competition as a new observational signature for probing new physics and further motivates a supplemental framework for analyzing long-lived ringdown signals.

The degree of freedom of the scalar field in scalar-tensor gravity is employed as “time” to deparametrize the Hamiltonian constraint of the theory. The deparametrized system is then nonperturbatively quantized by the approach of loop quantum gravity. This results in a discrete time evolution of the physical states with respect to the gravitational degree of freedom in the quantum theory. In the corresponding Brans-Dicke cosmological model, the physical solutions to the quantum Hamiltonian constraint are obtained in the light of the deparametrization. The quantum dynamics indicates that the classical big bang singularity is replaced by a quantum bounce.

We present the full Hamiltonian analysis of electrodynamics, including fermions, photons, and their interaction, on a general curved spacetime in Ashtekar-Barbero variables. Only the time gauge is imposed and the theory is background independent. The details of the constraints of the theory for fermionic and electromagnetic fields coupled to gravity are presented. Moreover, the equations of motion are derived and it is shown that they reduce to the Dirac equation, Maxwell equation, and their interaction term in curved or flat spacetime in the appropriate limits. Finally, the behavior of the theory under parity transformation is analyzed. This result presents a suitable foundation for loop or polymer quantization.

We present HEALFormer, a transformer-based neural network architecture for weak gravitational lensing mass mapping that reconstructs convergence maps from incomplete and noisy shear observations on the celestial sphere. The model operates directly on the Hierarchical Equal Area isoLatitude Pixelization and employs learnable mask tokens to handle arbitrary survey geometries without requiring preprocessing. Through a progressive training strategy, HEALFormer efficiently processes high-resolution maps up to $N_{\mathrm{side}}=1024$ and demonstrates excellent performance across diverse survey footprints including KiDS, DES, DECaLS, and Planck. The model generalizes robustly to cosmological parameters beyond its training set, producing nearly unbiased reconstructions with superior noise suppression compared to traditional Kaiser-Squires and Wiener filter methods. Remarkably, HEALFormer exceeds the theoretical phase recovery limits of linear reconstruction methods at small scales, achieving a fundamental breakthrough in weak lensing analysis. The combination of computational efficiency, reconstruction accuracy, and adaptability to varying survey configurations makes HEALFormer well-suited for current and next-generation cosmological surveys. Code is available at GitHub.

The gravitational lensing effect of gravitational waves (GWs) has been extensively discussed as a probe of small-mass dark matter halos, which can provide missing information about dark matter. We propose a multiband observation of lensed GWs from a compact binary to observe both geometrical optics (GO) and wave optics (WO) effects from the same source. This method is expected to be advantageous in breaking parameter degeneracies between a GW source and a dark matter halo acting as a lens. We assume DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) or B-DECIGO as a space-based detector observing the early inspiral phase, and the Einstein Telescope (ET) as a ground-based detector observing the merger phase. We perform a Fisher analysis of multi-band detection for a source with masses $m_1=30M_{\odot },m_2=20M_{\odot }$ at redshift $z=1.5$, and a lens with mass $3\times {10}^3{M}_{\odot }$ at redshift $z=1.0$. With this setup, the GO effect appears in the ET frequency band, and the WO effect in that of DECIGO. For the halo density profile, we adopt singular isothermal sphere, cored isothermal sphere (CIS), and Navarro-Frenk-White models. We find that multiband observation resolves parameter degeneracies and significantly reduces errors in estimated parameters. For the CIS model, in particular, we show that, by combining ET and DECIGO observations, the lens mass error improves by about 72% and 37% compared to ET and DECIGO alone, respectively. Similarly, the impact parameter error is reduced by about 65% and 71%, and the core size error by 34% and 68%, respectively. From these results, we conclude that the multiband observation of GWs from compact binaries improves the estimation of the lens object properties by breaking the parameter degeneracy.

We compare cosmological parameters from different Planck sky maps and likelihood pipelines, assessing the robustness of cosmological results with respect to the choice of the latest Planck maps-likelihood combination. We show that, for the Planck multipole range retained in combination with ground-based observations, different products give very similar cosmological solutions; small remaining differences are reduced by the addition of other CMB datasets to Planck. In particular, constraints on extended cosmological models benefit from the addition of small-scale power from ground-based experiments and are completely insensitive to the choice of Planck maps and likelihood. For this work, we derive and release a nuisance-marginalized dataset and CamSpec-NPIPE-lite likelihood for the Planck NPIPE data injected into the CamSpec likelihood—which are usually used to obtain the reference Planck PR4 cosmology. Using the extracted CMB spectra, we show that the additional constraining power for cosmology is coming from polarization at all scales and from temperature at multipoles above 1500 when going from PR3 to PR4. We also show that full marginalization over the CamSpec foreground nuisance parameters can impact parameter inference and model selections when truncating some scales; our new likelihood enables correct combinations with other CMB datasets.

Hybrid foreground residual subtraction (HyFoReS) is a new family of algorithms designed to remove systematics-induced foreground contamination for 21-cm intensity mapping data. Previously, the algorithm was shown to be effective in mitigating beam perturbations in sky maps from the Canadian Hydrogen Intensity Mapping Experiment (CHIME). In this study, we apply HyFoReS to CHIME simulations and test the algorithm’s ability to mitigate antenna gain-type systematics in polarized visibilities. Simulating a two-cylinder telescope similar to the CHIME pathfinder, we find that HyFoReS reduces foreground bias caused by bandpass perturbations to a level below the thermal noise, provided that the rms value of the perturbations is on the order of ${10}^{-4}$ or lower. When tested with complex antenna-dependent gain errors, HyFoReS can reduce residual foreground bias in the power spectrum by up to 3 orders of magnitude. While noise bias and second-order perturbations are currently the limiting factors for the algorithm, we have demonstrated that HyFoReS can suppress gain-induced foreground leakage in polarized data from 21-cm telescopes, aiding in the detection of the 21-cm autopower spectrum for hydrogen intensity mapping experiments.

We consider the hypothetical possibility that nonstationary glitch features in the noise of ground-based gravitational-wave detectors could be produced by small dark matter clumps that pass through the earth in the vicinity of gravitational-wave detectors. We first derive the gravitational-wave strain that would be generated by the passage of such a dark matter clump. We find that the strain is primarily sourced by the Newtonian gravitational acceleration of the mirrors toward the clump and by the Shapiro time delay of the photons in the laser beams as they pass through the gravitational potential created by the dark matter clump. We also find that the Newtonian acceleration effect dominates the gravitational-wave strain for both ground and space-based interferometers. We then compare our dark matter clump, gravitational-wave strain model to 84 Koi-Fish glitches detected during the second observing run of the LIGO/Virgo/KAGRA Collaboration through a Markov chain Monte Carlo Bayesian analysis. We find that all glitches but nine can be confidently rejected as having originated from dark matter clumps. For the remaining glitches, the dark matter hypothesis cannot be excluded, and the maximum a posteriori parameters yield minimum densities of about ${10}^{-7}\mathrm{g}/{\mathrm{cm}}^3$, within the model. These results allow us to place the first direct upper limits with gravitational-wave detectors on the local over-density of dark matter in the form of clumps in the local neighborhood of Earth, namely ${\rho }_{\mathrm{DM}\text{clumps}}\lesssim {10}^{-15}\mathrm{g}/{\mathrm{cm}}^{-3}$.

In extreme/intermediate mass-ratio inspirals (E/IMRIs) embedded in dark-matter (DM) spikes, the secondary black hole can accrete collisionless particles from the surrounding halo. We study how the companion’s spin controls this process, and the ensuing backreaction on the magnitude and direction of the companion’s spin vector. We find that higher spin suppresses the mass accretion rate but enhances the accretion-induced torques, driving spin down and secular alignment of the companion’s spin with the orbital plane. Collisionless DM accretion generically imprints a near-universal mass-spin correlation characterized by a spin-evolution parameter $s\simeq 2.8$, much larger than is the case for typical astrophysical environments, and largely independent of the local DM density and the spike slope. The associated spin down proceeds on astrophysically relevant timescales; thus, observations of rapidly spinning IMRI companions would disfavor the presence of dense DM environments, providing constraints complementary to those arising from dynamical friction.

Gravitational waves from black hole binary mergers carry information about the component spins, but inference is sensitive to analysis assumptions, which may be broken by terrestrial noise transients known as glitches. Using a variety of simulated glitches and gravitational wave signals, we study the conditions under which glitches can bias spin measurements. We confirm the theoretical expectation that inference and subtraction of glitches invariably leaves behind residual power due to statistical uncertainty, no matter the strength (signal-to-noise ratio, SNR) of the original glitch. Next we show that low-SNR glitches—including those below the threshold for flagging data-quality issues—can still significantly bias spin inference. Such biases occur for a range of glitch morphologies, even in cases where glitches and signals are not precisely aligned in phase. Furthermore, we find that residuals of glitch subtraction can result in biases as well. Our results suggest that joint inference of the glitch and gravitational wave parameters, with appropriate models and priors, is required to address these uncertainties inherent in glitch mitigation via subtraction.

We study vorticity-induced effects arising from the Wess-Zumino-Witten terms for Nambu-Goldstone modes in chiral perturbation theory. We first provide an alternative derivation of the Wess-Zumino-Witten terms in the presence of external vector, axial-vector, and pseudoscalar fields using a derivative expansion of the fermion determinant. We then employ the previously found correspondence in which vorticity is treated as an axial-vector field coupled to Dirac fermions in flat spacetime. Using this, we derive vorticity-induced contributions for Nambu-Goldstone modes in the presence of electromagnetic fields at finite baryon and isospin chemical potentials, including a vorticity-induced current, a magnetic-field-induced angular momentum, and a vorticity-modified photon–pion coupling. We also briefly discuss the phenomenological implications of these vorticity-induced effects.

We revisit the total decay rate of a muon being in the ground state of a Coulomb potential with atomic charge numbers $4\le Z\le 9$. The discrepancy between the perturbative $(\alpha Z{)}^2$ result in H. Überall [Phys. Rev. 119, 365 (1960)] and the fully relativistic partial-wave calculation of R. Watanabe et al. [At. Data Nucl. Data Tables 54, 165 (1993)] for oxygen ($Z=8$) is shown to originate from insufficient convergence of the partial-wave series in the latter work. Our accurate relativistic calculations restore agreement with the perturbative $\alpha Z$ expansion and indicate a negative sign for the next-order $(\alpha Z{)}^3$ correction.