In this paper we extract from a large-$r$ expansion of the vacuum Einstein’s equations a dynamical system governing the time evolution of an infinity of higher-spin charges. Upon integration, we evaluate the canonical action of these charges on the gravity phase space. The truncation of this action to quadratic order and the associated charge conservation laws yield an infinite tower of soft theorems. We show that the canonical action of the higher spin charges on gravitons in a conformal primary basis, as well as conformally soft gravitons reproduces the higher spin celestial symmetries derived from the operator product expansion. Finally, we give direct evidence that these charges form a canonical representation of a $w_{1+\infty }$ loop algebra on the gravitational phase space.

We study extremal surfaces in a traversable wormhole geometry that connects two locally ${\mathrm{AdS}}_5$ asymptotic regions. In the context of the $\mathrm{AdS}/\mathrm{CFT}$ correspondence, we use these to compute the holographic entanglement entropy for different configurations: First, we consider an extremal surface anchored at the boundary on a spatial 2-sphere of radius $R$. The other scenario is a slab configuration which extends in two of the boundary spacelike directions while having a finite size $L$ in the third one. We show that in both cases the divergent and the finite pieces of the holographic entanglement entropy give results consistent with the holographic picture and this is used to explore the phase transitions that the dual theory undergoes. The geometries we consider here are stable thin-shell wormholes with flat codimension-one hypersurfaces at fixed radial coordinate. They appear as electrovacuum solutions of higher-curvature gravity theories coupled to Abelian gauge fields. The presence of the thin shells produces a refraction of the extremal surfaces in the bulk, leading to the presence of cusps in the phase space diagram. Further, the traversable wormhole captures a phase transition for the subsystems made up of a union of disconnected regions in different boundaries. We discuss these and other features of the phase diagram.

To assist the matching of lattice field theory results to the high energy continuum limit we evaluate the Green’s function where the tensor quark bilinear operator is inserted at zero momentum in a quark 2-point function for an arbitrary covariant gauge. This is carried out in both the $\overline{\mathrm{MS}}$ and ${\mathrm{RI}}^{\prime }$ schemes to four loops. The tensor current anomalous dimension is also calculated to four loops in both schemes for an arbitrary color group.

Gravitational-wave observations provide a unique opportunity to test general relativity (GR) in the strong-field and highly dynamical regime of the theory. Parametrized tests of GR are one well-known approach for quantifying violations of GR. This approach constrains deviations in the coefficients of the post-Newtonian phasing formula, which describes the gravitational-wave phase evolution of a compact binary as it inspirals. Current bounds from this test using LIGO/Virgo observations assume that binaries are circularized by the time they enter the detector frequency band. Here, we investigate the impact of residual binary eccentricity on the parametrized tests. We study the systematic biases in the parameter bounds when a phasing based on the circular orbit assumption is employed for a system that has some small residual eccentricity. We find that a systematic bias (for example, on the leading Newtonian deformation parameter) becomes comparable to the statistical errors for even moderate eccentricities of $\sim 0.04$ at 10 Hz in LIGO/Virgo band for binary black holes, and $\sim 0.008$ for binary neutron stars. This happens at even lower values of orbital eccentricity in the frequency band of third-generation (3G) detectors like Cosmic Explorer ($\sim 0.005$ at 10 Hz for binary black holes and $\sim 0.002$ for binary neutron stars). These results demonstrate that incorporating physical effects like eccentricity in waveform models is important for accurately extracting science results from future detectors.

We present the first spectral method to evolve a single black hole treated as a puncture, therefore without singularity excision. We consider the Galerkin-Collocation method in single and multidomains to integrate the extended Baumgarte-Shapiro-Shibata-Nakamura formulation. In addition, we adopt the moving puncture approach but consider distinct Bona-Massó slicing families instead of the standard $1+\log$ slicing condition. Further, we implement the maximal slicing version of the spectral code, where the lapse satisfies an elliptic-like equation.

The Bondi-van der Burg-Metzner-Sachs (BMS) group, which uniquely describes the symmetries of asymptotic infinity and therefore of the gravitational waves that propagate there, has become increasingly important for accurate modeling of waveforms. In particular, waveform models, such as post-Newtonian (PN) expressions, numerical relativity (NR), and black hole perturbation theory, produce results that are in different BMS frames. Consequently, to build a model for the waveforms produced during the merging of compact objects, which ideally would be a hybridization of PN, NR, and black hole perturbation theory, one needs a fast and robust method for fixing the BMS freedoms. In this work, we present the first means of fixing the entire BMS freedom of NR waveforms to match the frame of either PN waveforms or black hole perturbation theory. We achieve this by finding the BMS transformations that change certain charges in a prescribed way—e.g., finding the center-of-mass transformation that maps the center-of-mass charge to a mean of zero. We find that this new method is 20 times faster, and more correct when mapping to the superrest frame, than previous methods that relied on optimization algorithms. Furthermore, in the course of developing this charge-based frame fixing method, we compute the PN expression for the Moreschi supermomentum to 3PN order without spins and 2PN order with spins. This Moreschi supermomentum is effectively equivalent to the energy flux or the null memory contribution at future null infinity ${\mathcal{I}}^{+}$. From this PN calculation, we also compute oscillatory ($m\ne 0$ modes) and spin-dependent memory terms that have not been identified previously or have been missing from strain expressions in the post-Newtonian literature.

We revisit the peculiar electromagnetic quasinormal mode spectrum of an asymptotically anti–de Sitter Schwarzschild black hole. Recent numerical calculations have shown that some quasinormal mode frequencies become purely overdamped at some critical black hole sizes, where the spectrum also bifurcates. In this paper, we shed light on unnoticed and unexplained properties of this spectrum by exploiting some novel analytic results for the large black hole limit. We demonstrate, both numerically and analytically, that the quasinormal mode spectra of large black holes become approximately isospectral, and we refer to this new symmetry property as spectral similarity. We take advantage of this spectral similarity to derive a precise analytic expression for the locations of the bifurcations, in which a surprising Feigenbaum-like constant appears. We derive an exact solution for its spectrum and eigenfunctions, and find that large black holes cannot be made to vibrate with electromagnetic perturbations, independently of the boundary conditions imposed at spatial infinity. Finally, we characterize the insensitivity of the spectrum to different boundary conditions by analyzing the expansion of the quasinormal mode spectrum around the large black hole limit.

Gravitational-wave population studies have become more important in gravitational-wave astronomy because of the rapid growth of the observed catalog. In recent studies, emulators based on different machine learning techniques are used to emulate the outcomes of the population synthesis simulation quickly. In this study, we benchmark the performance of two emulators that learn the truncated power-law phenomenological model by using Gaussian process regression and normalizing flows technique to see which one is a more capable likelihood emulator in the population inference. We benchmark the characteristic of the emulators by comparing their performance in the population inference to the phenomenological model using mock and real observation data. Our results suggest that the normalizing flows emulator can recover the posterior distribution by using the phenomenological model in the population inference with up to 300 mock injections. The normalizing flows emulator also underestimates the uncertainty for some posterior distributions in the population inference on real observation data. On the other hand, the Gaussian process regression emulator has poor performance on the same task and can only be used effectively in low-dimension cases.

We discuss domain walls from spontaneous breaking of Abelian discrete symmetries $Z_N$. A series of different domain wall structures are predicted, depending on the symmetry and charge assignments of scalars leading to the spontaneous symmetry breaking (SSB). A widely existing type of domain walls are those separating degenerate vacua which are adjacent in the field space. We denote these walls as adjacency walls. In the case that $Z_N$ terms are small compared with the $U(1)$ terms, the SSB of $U(1)$ generates strings first and then adjacency walls bounded by strings are generated after the SSB of $Z_N$. For symmetries larger than $Z_3$, nonadjacent vacua exist, and we regard walls separating them as nonadjacency walls. These walls are unstable if $U(1)$ is a good approximation. If the discrete symmetry is broken via multiple steps, then we arrive at a complex structure where one kind of wall is wrapped by another type. On the other hand, if the symmetry is broken in different directions independently, then walls generated from the different breaking chains are blind to each other.

T2HK is an upcoming long-baseline experiment in Japan which will have two water Cherenkov detector tanks of 187 kt volume each at a distance of 295 km from the source. An alternative project, T2HKK is also under consideration where one of the water tanks will be moved to Korea at a distance of 1100 km. The flux at 295 km will cover the first oscillation maximum and the flux at 1100 km will mainly cover the second oscillation maximum. As physics sensitivity at the dual baseline relies on variation in statistics, the dependence of systematic uncertainty, the effect of the second oscillation maximum and matter density, 187 kt detector volume at 295 km and 187 kt detector volume at 1100 km may not be the optimal configuration of T2HKK. Therefore, in this work we have tried to optimize the ratio of the detector volume at both the locations by studying the interplay between the above mentioned parameters. For the analysis of neutrino mass hierarchy, octant of ${\theta }_{23}$ and $CP$ precision, we have considered two values of ${\delta }_{CP}$ as 270° and 0° and for $CP$ violation we have considered the value of ${\delta }_{CP}=270°$. These values are motivated by the current best-fit values of this parameter as obtained from the experiments T2K and $\mathrm{NO}\nu \mathrm{A}$. Interestingly we find that if the systematic uncertainty is negligible then the T2HK setup i.e., when both the detector tanks are placed at 295 km gives the best results in terms of hierarchy sensitivity at ${\delta }_{CP}=270°$, octant sensitivity, $CP$ violation sensitivity, and $CP$ precision sensitivity at ${\delta }_{CP}=0°$. For current values of systematic errors, we find that neither T2HK, nor T2HKK setup is giving better results for hierarchy, $CP$ violation and $CP$ precision sensitivity. The optimal detector volume which is in the range between 255 kt to 345 kt at 1100 km gives better results in the above mentioned parameters.

Based on a sample of $448.1\times {10}^6\psi (3686)$ events collected with the BESIII detector, a study of $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}{\pi }^0$ and $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\eta$ is performed. Evidence of the isospin-violating decay $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}{\pi }^0$ is found for the first time with a statistical significance of $3.7\sigma$, the branching fraction $\mathcal{B}(\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}{\pi }^0)$ is measured to be $(1.42\pm 0.39\pm 0.59)\times {10}^{-6}$, and its corresponding upper limit is determined to be $2.47\times {10}^{-6}$ at 90% confidence level. A partial wave analysis of $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\eta$ shows that the peak around $\mathrm{\Lambda }\eta$ invariant mass threshold favors a ${\mathrm{\Lambda }}^{*}$ resonance with mass and width in agreement with the $\mathrm{\Lambda }(1670)$. The branching fraction of the $\psi (3686)\to \mathrm{\Lambda }\overline{\mathrm{\Lambda }}\eta$ is measured to be $(2.34\pm 0.18\pm 0.52)\times {10}^{-5}$. The first uncertainties are statistical and the second are systematic.

We investigate the second-order effective energy-momentum tensor (2EMT) constructed by the quadratic terms of the linear scalar cosmological perturbations while the universe is dominated by a scalar field. We show that 2EMT is gauge dependent. We then study 2EMT in three (longitudinal, spatially flat, and comoving) gauge conditions in the slow-roll stage of inflation. We find that 2EMT exhibits an effective fluid of $w=-1/3$ on superhorizon scales in all of those gauge conditions.

It has been explicitly shown how a theory with global $GL(d,\mathbb{R})$ coordinate (affine) invariance which is spontaneously broken down to its Lorentz subgroup will have as its Goldstone fields enough degrees of freedom to create a metric and a covariant derivative. Such a theory would constitute an effective theory of gravity. So far however, no explicit model has been found which exhibits this symmetry breaking pattern, mainly due to the difficulty of even writing down a $GL(d,\mathbb{R})$ invariant action in the absence of a metric. In this paper we explicitly construct an affine generalization of the Dirac action employing infinite dimensional spinorial representations of the group. This implies that it is built from an infinite number of spinor Lorentz multiplets. We introduce a systematic procedure for constructing $GL(d,\mathbb{R})$ and $SL(d,\mathbb{R})$ invariant interaction terms to obtain quite general interacting models. Such models have order operators whose expectation value can break affine symmetry to Poincaré symmetry. We discuss possible interactions and mechanisms for this symmetry breaking to occur, which would provide a dynamical explanation of the Lorentzian signature of spacetime.

We investigate the affine perturbation series of the deflection angle of a ray near the photon sphere of an extreme Reissner-Nordström black hole. We compare the 0th and 1st orders of the affine perturbation series with the deflection angle in a strong deflection limit. We conclude that the 0th order of the affine perturbation series is more accurate than the deflection angle in the strong deflection limit and that we should improve a strong-deflection-limit analysis by using the 0th order of the affine perturbation series.

Linear cosmological observables can be used to probe elastic scattering of dark matter (DM) with baryons. Availability of high-precision data requires a critical reassessment of any assumptions that may impact the accuracy of constraints. The standard formalism for constraining DM-baryon scattering prerecombination is based on assuming a Maxwell-Boltzmann (MB) velocity distribution for DM. This assumption is not always physically justified, and does not allow for probing DM self-interactions simultaneously with its interactions with baryons. Lifting the MB assumption requires solving the full collisional Boltzmann equation (CBE), which is highly nontrivial. Earlier work proposed a more tractable Fokker-Planck (FP) approximation to the CBE, but its accuracy remained unknown. In this paper, we numerically solve the exact CBE for the first time, in a homogeneous expanding background. We consider DM-baryon scattering cross sections that are positive power-laws of relative velocity. We derive analytical expressions for the collision operator in the case of isotropic differential scattering cross sections. We then solve the background CBE numerically, and use our solution for the DM velocity distribution to compute the DM-baryon heat-exchange rate, which we compare against those obtained with the MB assumption and FP approximation. Over a broad range of DM-to-baryon mass ratios, we find that the FP approximation leads to a maximum error of 17%, significantly better than the up to 160% error introduced by the MB assumption. While our results strictly apply only to the background evolution, the accuracy of the FP approximation is likely to carry over to perturbations. This motivates its implementation into cosmological Boltzmann codes, where it can supersede the much less accurate MB assumption, and allow for a more general exploration of DM interactions with baryons and with itself.

In many theories of quantum gravity quantum fluctuations of spacetime may serve as an environment for decoherence. Here we study quantum-gravitational decoherence of high-energy astrophysical neutrinos in the presence of fermionic dark sectors and for a realistic three neutrino scenario. We show how violation of global symmetries expected to arise in quantum gravitational interactions provides a possibility to pin down the number of dark matter fermions in the Universe. Furthermore, we predict the expected total neutrino flux and flavor ratios at experiments depending on the flavor composition at the source.

Weakly interacting massive particles (WIMPs) can be captured in compact stars such as white dwarves (WDs) if they are in a dark matter (DM)-rich environment, leading to an increase in the star luminosity through their annihilation process. $N$-body simulations suggest that the core of the Messier 4 globular cluster (where plenty of WDs are observed) is rich of DM. Assuming this is the case, we use a recent improvement in the calculation of the WD equation of state to show that when the WIMP interacts with the nuclear targets within the WD through inelastic scattering, and its mass exceeds a few tens of GeV, the data on low-temperature large-mass WDs in M4 can probe values of the mass splitting as large as $\delta \lesssim 40\mathrm{MeV}$. Such value largely exceeds those ensuing from direct detection and from solar neutrino searches. We apply such improved constraint to the specific DM scenario of a self-conjugate bidoublet in the left-right symmetric model (LRSM), where the standard $SU(2{)}_L$ group with coupling $g_L$ is extended by an additional $SU(2{)}_R$ with coupling $g_R$ in order to explain maximal parity violation in weak interactions. We show that bounds from WDs significantly reduce the cosmologically viable parameter space of such scenario, in particular requiring $g_R>g_L$. For instance, for $g_R/g_L=1.8$ we find the two viable mass ranges $1.2\mathrm{TeV}\lesssim m_{\chi }\lesssim 3\mathrm{TeV}$ and $5\mathrm{TeV}\lesssim m_{\chi }\lesssim 10\mathrm{TeV}$, when the charged $SU(2{)}_R$ gauge boson mass $M_{W_2}$ is lighter than $\simeq 12\mathrm{TeV}$. We also discuss the ultraviolet completion of the LRSM model, when the latter is embedded in a grand unified theory. We show that such low-energy parameter space and compatibility to proton-decay bounds require a nontrivial extension of the particle content of the minimal model. We provide a specific example where $M_{W_2}\lesssim 10\mathrm{TeV}$ is achieved by extending the LRSM at high energy with color triplets that are singlets under all other groups, and $g_R/g_L>1$ is obtained by introducing $SU(2{)}_L$ triplets with no $SU(2{)}_R$ counterparts, i.e., by breaking the symmetry between the multiplets of $SU(2{)}_L$ and $SU(2{)}_R$.