In the AdS/CFT correspondence, a topological symmetry operator of the boundary conformal field theory (CFT) is dual to a dynamical brane in the gravitational bulk. Said differently, this predicts a dynamical brane for every global symmetry of the boundary CFT. We analyze this correspondence for continuous symmetries which arise from a consistent truncation of isometries on the “internal” factor $X$ of $\mathrm{AdS}\times X$. In the extra-dimensional geometry, these branes are associated with various metric singularities and do not arise from wrapped D-branes. Boosts relate configurations interpreted as topological symmetry operators and heavy defects in the CFT. From the perspective of the AdS factor, with gravity and bulk gauge fields, these are codimension-2 Gukov-Witten-like vortex configurations which are the gravity duals of 0-form symmetry operators. These effective branes come with an asymptotic tension and size which is also fully fixed by bulk dynamics. We use this higher-dimensional perspective to determine properties of the worldvolume theory for these branes. We also discuss how these considerations generalize to more general quantum field theories engineered via string theory which need not possess a semiclassical gravity dual.

In a previous work, we showed that the two- and three-loop contributions to the partition function of three-dimensional gravity in flat space vanish. This is in agreement with the expected one-loop exactness dictated by the underlying symmetry at the quantum level. To highlight the distinctive nature of the $D=3$ case, we extend the three-loop computation to arbitrary spacetime dimensions $D$. In higher dimensions, the number of contributions increases substantially, reinforcing the view that one-loop exactness is a unique feature of three-dimensional gravity.

An exact and analytical solution, in four-dimensional general relativity coupled with Maxwell electromagnetism, is built by means of a Lie point symmetry of the Ernst equations, the Harrison transformation. The new spacetime describes a Schwarzschild-like black hole embedded into a general external backreacting electromagnetic field, which is the superposition of the Levi-Civita-Bertotti-Robinson and the Bonnor-Melvin ones. The relation between the two homogeneous electromagnetic fields is clarified. Conserved charges and the first law of thermodynamics are analyzed. Swirling generalizations are also considered. Limits to the known metrics such as Schwarzschild-Bertotti-Robinson, Schwarzschild-Bonnor-Melvin, and Bertotti-Robinson-Bonnor-Melvin are discussed.

We investigate the interaction between a nonrotating black hole and incoming gravitational waves using the characteristic formulation of the Einstein field equations, framed as a Bondi problem. By adopting retarded time as the null coordinate and recognizing that the final state is invariably a black hole, we demonstrate that an apparent horizon forms once sufficient mass accretes onto the black hole. We derive the evolution of the Bondi mass and compute its final value, enabling us to quantify the fraction of the incident mass absorbed by the black hole. Additionally, we establish a scaling law for the absorbed mass as a function of initial parameters, such as the amplitude of the gravitational wave data. Furthermore, we explore the dynamics when a reflecting barrier surrounds the black hole. For low-amplitude initial waves, the barrier reflects the waves, leaving the original black hole as the end state. Conversely, high-amplitude waves lead to the formation of an apparent horizon that engulfs the barrier, producing a new, larger black hole.

Advancements in the sensitivity of gravitational wave detectors have increased the detection rate of transient astrophysical signals. We improve the existing BayesWave initialization algorithm and present a rapid, low-latency approximate maximum likelihood solution for reconstructing non-Gaussian features. We include three enhancements: (1) using a modified wavelet basis to eliminate redundant inner product calculations; (2) shifting from traditional time-frequency-quality factor wavelet transforms to time-frequency-time extent transforms to optimize wavelet subtractions; (3) implementing a downsampled heterodyned wavelet transform to accelerate initial calculations. Our model can be used to denoise long-duration signals, which include the stochastic gravitational wave background from numerous unresolved sources and continuous wave signals from isolated sources such as rotating neutron stars. Through our model, we can also supplement machine learning applications that use spectrographic training data to classify and understand glitches by providing nonwhitened, time and frequency domain reconstructions of any glitch.

Recent advances in post-Minkowskian (PM) gravity provide new avenues for the high precision modeling of compact binaries. In conjunction with the effective one body (EOB) formalism, highly accurate PM informed models of binary black holes on scattering trajectories have emerged. Several complementary approaches currently exist, in particular the spinning effective one body (SEOB)-PM model, the $w_{\mathrm{EOB}}$ framework and the recent lagrangian effective one body (LEOB) approach. These models incorporate PM results in fundamentally different ways, employing distinct resummation schemes and gauge choices. Notably, both SEOB-PM and LEOB have been used to compute gravitational waves of bound systems, showing excellent agreement with numerical relativity. The essential component to all of the models is the EOB mass-shell condition describing the dynamics of the two-body spacetime. In this work we will investigate how this mass-shell condition is constructed, paying particular attention to the impact of gauge choices and how they interact with different resummation schemes, showing that there is a strong dependence on both coordinate choice and EOB gauge. For the region of parameter space considered, we find that the best performing gauges coincide with the choices made in SEOB-PM and $w_{\mathrm{EOB}}$, with other choices exhibiting worse performance. The case of spinning black holes is also considered, where the current techniques for spinning EOB-PM are reviewed and compared. We also introduce a new gauge based upon the centrifugal radius, which improves upon previous models, particularly for large and negative spins. This offers a promising avenue for further resummation of spin information within the EOB-PM framework.

We investigate the gravitational memory effect in the full generalized Proca gravity, the most general metric theory including a gravitational Proca field with derivative self-interactions that still maintains second-order equations of motion. Building on our previous works on memory in other massless and massive metric theories, we extend a unified framework for computing displacement memory and apply it to generalized Proca gravity. We identify two nontrivial, physically distinct classes of background conditions of generalized Proca theory within the assumption of asymptotic flatness: a Lorentz-invariant but massive case, and a Lorentz-violating, massless case. The former exhibits dispersive scalar and vector modes and allows a Horndeski-like treatment of memory, while the latter resembles the asymptotic dynamics of Einstein-Æther theory, including the same Lorentz-breaking effects on displacement memory. In both cases, we derive the fully gauge-invariant and dynamical second-order action, derive the effective stress-energy tensor, and study its contribution to the memory integral. We highlight the distinction between phase and group velocity in the tensor memory formula sourced by dispersive propagating modes. Finally, we reemphasize how observational constraints on Lorentz violation may be imposed by the structure of the memory signal.

The Hawking–Penrose singularity theorem weakens the causality assumption of global hyperbolicity used in the Penrose singularity theorem, at the expense of invoking the stronger timelike (instead of null) convergence condition (TCC). We analyze the TCC for a large class of dynamical spherically symmetric spacetimes and show that it decomposes into three independent conditions on the Misner-Sharp mass function. For stationary black holes, only two of these are nontrivial. One of these conditions is already implied by the null convergence condition (NCC), whereas the other one depends explicitly on the TCC and constrains the sign of the second derivative of the mass function. We show that generic asymptotically flat regular black holes with a smooth de Sitter core locally violate this new TCC-induced condition near the core, even if they globally satisfy the other condition imposed by the NCC. Therefore, it is the violation of the TCC which ensures that regular de Sitter core black holes circumvent the Hawking-Penrose theorem. By contrast, we show that asymptotically flat regular black holes with an anti–de Sitter core locally satisfy the new TCC-induced condition near the core, but necessarily violate it at some finite distance away from it. As concrete examples for both types of spacetimes, we consider TCC violations in the Bardeen black-hole spacetime with a de Sitter core, and in a modified Bardeen black-hole spacetime with an anti–de Sitter core.

We investigate the different meanings that the concept of quantum bounce acquires in various formalisms. The original idea refers to the phenomenology that appears in the Klein-Gordon framework when homogeneous cosmologies are considered. In that case, the quantum bounce describes the quantum scattering between a collapsing and an expanding Universe branch, and therefore provides a quantum description of the semiclassical big bounce mechanism. Here, we show that the proposal of the quantum big bounce is well grounded, thanks to the computation of the volume operator mean values and its standard deviation in the Wheeler-DeWitt framework for the isotropic case. Then, we analyze the Bianchi models in the Dirac approach, now showing that the quantum bounce concept can be implemented to describe the Kasner transitions of the Belinski-Khalatnikov-Lifshitz map at a quantum level. In summary, the quantum scattering framework borrowed from particle physics can serve as a good model for different cosmological scenarios, which can exhibit scalarlike or fermioniclike behaviors depending on how the anisotropies are described in the dynamics.

While the (weak) equivalence principle (EP) has been rigorously tested within the solar system, its validity on cosmological scales, particularly in the context of dark matter and dark energy, remains uncertain. In this study, we propose a novel method to test EP on cosmological scales by measuring the peculiar acceleration power spectrum of galaxies using the redshift drift technique. We develop an EP estimator, $E_{\mathrm{ep}}$, to evaluate the consistency of the peculiar acceleration power spectrum across different tracers. By calculating the ratio of the peculiar acceleration power spectra of tracers, the ensemble average of $E_{\mathrm{ep}}$ is expected to be unity if EP holds on cosmological scales for these tracers. We validate this estimator using N-body simulations, focusing on four redshift bins with $z\le 1.5$ and scales of $k$ in the range of 0.007 and $0.2h/\mathrm{Mpc}$. By fitting a single parameter ${\delta }_{\mathrm{ep}}$ across redshifts, we find that dark matter (DM) particle mocks without EP violation yield ${\delta }_{\mathrm{ep}}$ consistent with zero under the small redshift measurement uncertainty case, while the large redshift uncertainty case slightly induces biases at low redshifts. In addition, when using DM halo mocks with controlled EP violations, no-violation and mild-violation cases show no significant detection, while moderate and strong violations produce statistically significant ${\delta }_{\mathrm{ep}}$ values and high ${\chi }^2$, especially at low redshifts, confirming the estimator’s sensitivity. Taking advantage of advanced observing capabilities, such as next-generation facilities that extend beyond the Square Kilometer Array, the proposed method offers a promising approach for future cosmological tests of EP.

We demonstrate the formation of magnetically arrested minidisks (MAM) around equal-mass, nonspinning binary black holes with magnetohydrodynamic simulations of circumbinary disk accretion in full $3+1$ general relativity. The initial separation of $d\sim 30M$ allows the black holes to host large minidisks that suppress the total rest-mass accretion rate variability, which is modulated primarily at $\sim 1.6f_{\mathrm{orb}}$. Each black hole horizon saturates with dimensionless magnetic flux $\varphi \sim 30$. Magnetic reconnection near the horizons drives recurrent eruptions, which are expected to drive flaring in the infrared and x-ray bands. Our results establish MAMs as a new outcome of circumbinary disk accretion, and a promising source of novel electromagnetic counterparts to gravitational waves from binary black holes.

Detecting continuous gravitational waves is challenging due to the high computational cost of template-based searches across large parameter spaces, particularly for all-sky searches. Machine learning offers a promising solution to perform these searches with reasonable computational resources. In this study, we trained an attention U-Net, a convolutional neural network, on $\approx 10.67\mathrm{days}$ simulated data with Gaussian noise for all-sky searches at different frequencies within the 20–1000 Hz band. Our model trained at 20 Hz achieves the best sensitivity, with a 90% detection efficiency sensitivity depth ${\mathcal{D}}^{90\%}=29.97\pm 0.24{\mathrm{Hz}}^{-1/2}$ with 1% false alarm rate per 50 mHz, while the model trained on the entire 20–1000 Hz band yields ${\mathcal{D}}^{90\%}=18.63\pm 0.24{\mathrm{Hz}}^{-1/2}$. The sensitivities achieved are comparable to state-of-the-art results using deep learning approaches, with less than 50% of the training time and data. We find that sensitivity scales as $T^{0.28\pm 0.01}$ with total observation time for the attention U-Net trained at 20 Hz, similar to semicoherent search methods. The neural network demonstrates robustness on datasets with time gaps, with sensitivity dependence on duty factor analyzed. We also investigated the sensitivity dependence of the trained attention U-Net models on sky location. Our findings show that attention U-Net is a scalable and effective approach for all-sky continuous gravitational waves searches.

Space-based gravitational wave (GW) observatories, such as the future Laser Interferometer Space Antenna, employ synthetic time delay interferometry (TDI) to cancel the otherwise overwhelming laser frequency noise. The phase readouts at each spacecraft are combined with a carefully designed collection of time delays that cancel the laser frequency noise. The same collection of time delays must be applied to the GW signal models used for analysis, along with geometrical factors that encode the projection of the wave polarization tensor onto the arms of the interferometer. In principle, fully generic TDI calculations require the GW signal model to be evaluated at dozens of delay times for each data sample, a process that would require tens of millions of evaluations for a year-long signal. Here, a new method is presented that cuts the computational cost by a factor of 10,000 compared to a direct implementation at the data sample cadence, while incurring no loss in accuracy. The approach works for completely general spacecraft orbits and any flavor of TDI.

The correlations between successive measurements of a quantum system can violate a family of Leggett-Garg Inequalities (LGIs) that are analogous to the violation of Bell’s inequalities of measurements performed on spatially separated quantum systems. These LGIs follow from a macrorealistic point of view, imposing that a classical system is at all times in a definite state and that a measurement can, at least in principle, leave this state undisturbed. Violations of LGIs can be probed by neutrino flavor oscillations if the correlators of consecutive flavor measurements are approximately stationary. We discuss here several improvements of the methodology used in previous analyses based on accelerator and reactor neutrino data. We argue that the strong claims of LGI violations made in previous studies are based on an unsuitable modeling of macrorealistic systems in statistical hypothesis tests. We illustrate our improved methodology via the example of the MINOS muon-neutrino survival data, where we find revised statistical evidence for violations of LGIs at the $(2–3)\sigma$ level, depending on macrorealistic background models.

Probing the $CP$ nature of the Higgs Yukawa couplings is a promising avenue for unraveling new physics effects. In this work, we investigate the possible single- and two-field UV origins of $CP$-violating leptonic Yukawa couplings, using the Standard Model effective field theory as a stepping stone. We demonstrate a rich set of constraints on the UV model parameters, including direct Higgs measurements, electric and magnetic dipole moments of leptons, charged lepton flavor violating observables, and electroweak precision tests. Studying representative flavor assumptions we find that the precision constraints are often, but not always, more constraining than the dedicated LHC analyses of modified leptonic Yukawa couplings.

We revisit the contribution of the QCD $\overline{\theta }$ term to the $CP$-violating pion-nucleon couplings and the nucleon electric dipole moment in a combined large-$N_c$ and chiral perturbation theory framework. In particular, we approach this issue through the emergent spin-flavor symmetry of the baryon sector at large but finite $N_c$. We obtain good agreement with previous analyses for the pion-nucleon couplings and show that the large-$N_c$ framework indicates that tree-level contributions to the electric dipole moment possibly play a dominant role. The spin-flavor symmetry also enables us to provide novel constraints on $CP$-violating pion-$\mathrm{\Delta }$ couplings, as well as the $\mathrm{\Delta }$ electric dipole moment and $\mathrm{\Delta }N$ transition moment.

The development of tensor renormalization group (TRG) algorithm in higher dimensions is an important and urgent task, as the TRG is expected to provide a way to overcome the sign problem in lattice quantum chromodynamics (QCD) calculations at finite density. One possible approach that enables faster computations in four-dimensional lattice theories is the anisotropic tensor renormalization group (ATRG). However, the computational cost remains substantial and requires significant computational resources. In this paper, we propose a novel algorithm, called the triad-ATRG, which is based on the ATRG and other improved TRG variants with triad network representation. This method achieves lower scaling with respect to the bond dimension, while minimizing the loss of accuracy in the free energy and other physical quantities. We also present parallel implementations of both the ATRG and triad-ATRG on multiple GPUs, which significantly improve performance compared to CPU-based calculations for the four-dimensional system.

In this work, we propose a new method to detect the composition of the $X(3872)$ state. Based on a widely accepted interpretation that $X(3872)$ is a weakly bound $S$-wave molecule of the $D^{*0}{\overline{D}}^0$ (neutral) and $D^{*+}{D}^{-}$ (charged) configurations, the process $X(3872)\to {\overline{D}}^{*0}{D}^0$ is described by one-loop triangle diagrams with the corresponding components as intermediate particles, and with the parameters constrained by the experimental branching ratio. Unlike the mild behavior of the neutral component, the charged component manifests itself as a distinct structure near the $D^{*+}{D}^{-}$ threshold at 3.880 GeV, in the $M_{{\overline{D}}^{*0}{D}^0}$ invariant mass distribution of the spin density matrix element ${\rho }_{00}^{D^{*}}$. Hence, the line shape of ${\rho }_{00}^{D^{*}}$ near this structure depends sensitively on the proportions of the two configurations. We propose high-precision measurements of this matrix element by future BESIII and Belle experiments to elucidate how a molecular $X(3872)$ state is composed.