We construct Carrollian higher spin field theories by reducing the bosonic Fronsdal theories in flat spacetime to future null infinity. We extend the Poincaré fluxes to quantum flux operators, which generate Carrollian diffeomorphism, namely supertranslation and superrotation. These flux operators form a closed symmetry algebra once including a helicity flux operator, which follows from higher spin superduality transformation. The superduality transformation is an angle-dependent transformation at future null infinity, which generalizes the usual electromagnetic duality transformation. The results agree with the lower spin cases when restricted to $s=0$, 1, 2.

We compute the quasinormal modes of static and spherically symmetric black holes (BHs) with electric and magnetic charges. For the electrically charged case, the dynamics of perturbations separates into the odd- and even-parity sectors with two coupled differential equations in each sector. In the presence of both electric and magnetic charges, the differential equations of four dynamical degrees of freedom are coupled with each other between odd- and even-parity perturbations. Despite this notable modification, we show that, for a given total charge and mass, a BH with mixed electric and magnetic charges gives rise to the same quasinormal frequencies for fundamental modes. This includes the case in which two BHs have equal electric and magnetic charges for each of them. Thus, the gravitational-wave observations of quasinormal modes during the ringdown phase alone do not distinguish between electrically and magnetically charged BHs.

We study the optical appearance of Schwarzschild–de Sitter and Reissner–Nordström–de Sitter black holes viewed by distant observers inside cosmological horizons. Unlike their asymptotically flat counterparts, due to the positive cosmological constant, there are outermost stable circular orbits in the spacetimes, resulting in significant outer edges in the images. Besides this, when the Reissner–Nordström–de Sitter black hole has a stable Cauchy horizon, the photons from the preceding companion universe can be received by the observer in our universe. These rays create a multiring structure in the image. Since the stable Cauchy horizon violates the strong cosmic censorship conjecture, this novel image sheds some light on the test of the conjecture by astronomical observations.

We present an exact solution for a non-Bogomol’nyi-Prasad-Sommerfield (non-BPS) charged rotating black ring endowed with a dipole charge in the bosonic sector of five-dimensional minimal supergravity. Utilizing the electric Harrison transformation, we derive this solution by converting a five-dimensional vacuum solution into a charged solution within the realm of five-dimensional minimal supergravity. As the seed solution for the Harrison transformation, we use a vacuum solution of a rotating black ring possessing a Dirac-Misner string singularity. The resulting solution exhibits regularity, indicating the absence of curvature singularities, conical singularities, orbifold singularities, Dirac-Misner string singularities, and closed timelike curves both on and outside the horizon. This obtained solution carries the mass, two angular momenta, an electric charge, and a dipole charge, with only three of these quantities being independent, similar to the charged rotating dipole black ring found previously by Elvang, Emparan and Figueras. However, aside from the vacuum case, these two solutions do not coincide. We discuss the difference between them in the phase space.

We show that the seemingly different methods used to derive non-Lorentzian (Galilean and Carrollian) gravitational theories from Lorentzian ones are equivalent. Specifically, the pre-nonrelativistic and the pre-ultralocal parametrizations can be constructed from the gauging of the Galilei and Carroll algebras, respectively. Also, the pre-ultralocal approach of taking the Carrollian limit is equivalent to performing the Arnowitt-Deser-Misner decomposition and then setting the signature of the Lorentzian manifold to zero. We use this uniqueness to write a generic expansion for the curvature tensors and construct Galilean and Carrollian limits of all metric theories of gravity of finite order ranging from the $f(R)$ gravity to a completely generic higher derivative theory, the $f(g_{\mu \nu },R_{\mu \nu \sigma \rho },{\nabla }_{\mu })$ gravity. We present an algorithm for calculation of the $n$th order of the Galilean and Carrollian expansions that transforms this problem into a constrained optimization problem. We also derive the condition under which a gravitational theory becomes a modification of general relativity in both limits simultaneously.

Massive perturbations in asymptotic flat black holes leave a distinct signature in their late-time evolution “tail”: an oscillatory behavior modulated by the Compton wavelength of the field, which can be associated with the so-called quasibound state spectrum. In asymptotically de Sitter spacetimes, however, the massive perturbations always leak to the cosmological horizon, which indicates the absence of a quasibound part of the spectrum. In this work, we show that an additional mode exists in asymptotically de Sitter black holes that produces an imprint similar to that of the quasibound states in the late-time behavior of massive scalar perturbations. If the Compton wavelength is larger than a certain critical value (which depends on the cosmological constant), the oscillatory behavior of the tail turns into an exponential decay due to the fact that the de Sitter mode is purely imaginary. Even for black holes with typical length scales small in comparison to the size of the cosmological horizon, the late-time tail behavior of the massive perturbations is modified as compared to the usual $t^{-5/6}$ for Schwarzschild black holes, thus being a distinctive feature induced by the presence of a cosmological constant.

Space-based gravitational wave (GW) detection is one of the most anticipated GW detection projects in the next decade, which promises to detect abundant compact binary systems. At present, deep learning methods have not been widely explored for GW waveform generation and extrapolation. To solve the data processing difficulty and the increasing waveform complexity caused by the detector’s response and second-generation time-delay interferometry (TDI 2.0), an interpretable pretrained large model named Compact Binary Systems Waveform Generation with Generative Pretrained Transformer (CBS-GPT) is proposed. For compact binary system waveforms, three models were trained to predict the waveforms of massive black hole binaries, extreme mass-ratio inspirals, and galactic binaries, achieving prediction accuracies of at most 99%, 91%, and 99%, respectively. The CBS-GPT model exhibits notable generalization and interpretability, with its hidden parameters effectively capturing the intricate information of waveforms, even with the complex instrument response and a wide parameter range. Our research demonstrates the potential of large models in the GW realm, opening up new opportunities and guidance for future researches such as complex waveforms generation, gap completion, and deep learning model design for GW science.

In a space with fixed positive cosmological constant $\mathrm{\Lambda }$, we consider a system with a black hole surrounded by a heat reservoir at radius $R$ and fixed temperature $T$, i.e., we analyze the Schwarzschild–de Sitter black hole space in a cavity. We use results from the Euclidean path integral approach to quantum gravity to study, in a semiclassical approximation, the corresponding canonical ensemble and its thermodynamics. We give the action for the Schwarzschild–de Sitter black hole space and calculate expressions for the thermodynamic energy, entropy, temperature, and heat capacity. The reservoir radius $R$ gauges the other scales. Thus, the temperature $T$, the cosmological constant $\mathrm{\Lambda }$, the black hole horizon radius $r_{+}$, and the cosmological horizon radius $r_{\mathrm{c}}$, are gauged to $RT$, $\mathrm{\Lambda }{R}^2$, $\frac{r_{+}}{R}$, and $\frac{r_{\mathrm{c}}}{R}$. The whole extension of $\mathrm{\Lambda }{R}^2$, $0\le \mathrm{\Lambda }{R}^2\le 3$, can be split into three ranges. The first range, $0\le \mathrm{\Lambda }{R}^2<1$, includes York’s pure Schwarzschild black holes. The other values of $\mathrm{\Lambda }{R}^2$ within this range also have black holes. The second range, $\mathrm{\Lambda }{R}^2=1$, opens up a folder containing Nariai universes, rather than black holes. The third range, $1<\mathrm{\Lambda }{R}^2\le 3$, is unusual. One striking feature here is that it interchanges the cosmological horizon with the black hole horizon. The end of this range, $\mathrm{\Lambda }{R}^2=3$, only existing for infinite temperature, represents a cavity filled with de Sitter space inside, except for a black hole with zero radius, i.e., a singularity, and with the cosmological horizon coinciding with the reservoir radius. For the three ranges, for sufficiently low temperatures, which for quantum systems involving gravitational fields can be very high when compared to normal scales, there are no black hole solutions and no Nariai universes, and the space inside the reservoir is hot de Sitter. The limiting value $RT$ that divides the nonexistence from existence of black holes or Nariai universes, depends on the value of $\mathrm{\Lambda }{R}^2$. For each $\mathrm{\Lambda }{R}^2$ different from one, for sufficiently high temperatures there are two black holes, one small and thermodynamically unstable, and one large and stable. For $\mathrm{\Lambda }{R}^2=1$, for any sufficiently high temperature there is the small unstable black hole, and the neutrally stable hot Nariai universe. Phase transitions can be analyzed, the dominant phase has the least action. The transitions are between Schwarzschild-de Sitter black hole and hot de Sitter phases and between Nariai and hot de Sitter. For small cosmological constant, the action for the stable black hole equals the pure de Sitter action at a certain black hole radius and temperature, and so the phases coexist equally. For $0<\mathrm{\Lambda }{R}^2<1$ the equal action black hole radius is smaller than the Buchdahl radius, the radius for total collapse, and the corresponding Buchdahl temperature is greater than the equal action temperature. So above the Buchdahl temperature, the system collapses and the phase is constituted by a black hole. For $\mathrm{\Lambda }{R}^2\ge 1$ a phase analysis is also made.

We consider a phenomenological model of dark matter with an equation-of-state $w$ that is negative and changing at late times. We show this couples the $H_0$ and $S_8$ tensions, alleviating them both simultaneously, reducing the $H_0$ tension from $\sim 5\sigma$ to $\sim 3\sigma$ and the $S_8$ tension from $\sim 3\sigma$ to $\sim 1\sigma$. Furthermore, the model provides an explanation for the anomalously large integrated Sachs-Wolfe (ISW) effect from cosmic voids, a unique consequence of the changing and negative equation-of-state. Observations of high ISW from cosmic voids may therefore be evidence that dark matter plays a significant role in both the $H_0$ and $S_8$ tensions. We predict the ISW from cosmic voids to be a factor of up to $\sim 2$ greater in this model than what is expected from the standard model $\mathrm{\Lambda }\mathrm{CDM}$. These results extend to other degenerate models of dark matter, such as unified or interacting dark matter and dark energy models.

The speed of sound squared (SSS) $s^2$ in massive neutron stars (NSs) characterizes not only the stiffness of supradense neutron-rich matter within but also equivalently properties of the curved geometry due to the strong-field gravity and matter-geometry coupling. A peaked density or radius profile of $s^2$ has been predicted for massive NSs using various NS equation of state (EOS) models. However, the nature, cause, location and size of the peak in $s^2$ profiles are still very EOS model dependent. In this work, we investigate systematically $s^2$ profiles in massive NSs in a new approach that is independent of the nuclear EOS model and without any presumption about the NS structure and/or composition. In terms of the small quantities (reduced radius, the energy density and pressure scaled by their central values), we perform double-element perturbative expansions in solving perturbatively the scaled Tolman-Oppenheimer-Volkoff (TOV) equations and analyzing $s^2$ profiles from the Newtonian limit to the general relativistic (GR) case. The GR term in the TOV equations plays a twofold role: it compresses NS matter and modifies the pressure/energy density ratio from small values in Newtonian stars showing no $s^2$ peak to large ones for massive NSs possessing a peak in their $s^2$ profiles, and eventually takes away the peak in extremely compact/massive NSs approaching the causality limit. In particular, the peaked behavior in $s^2$ is expected to emerge near the center of massive NSs like PSR $\mathrm{J}0740+6620$, while a sharp phase transition is unlikely to occur there. These features revealed from our analyses are universal as they are intrinsic properties of the GR stellar structure equations independent of the still very uncertain EOS of supradense neutron-rich matter in NSs.

The Axion Dark Matter eXperiment (ADMX) has previously excluded Dine-Fischler-Srednicki-Zhitnisky (DFSZ) axions between 680–790 MHz under the assumption that the dark matter is described by the isothermal halo model. However, the precise nature of the velocity distribution of dark matter is still unknown, and alternative models have been proposed. We report the results of a nonvirialized axion search over the mass range $2.81–3.31\mathrm{\mu }\mathrm{eV}$, corresponding to the frequency range 680–800 MHz. This analysis marks the most sensitive search for nonvirialized axions sensitive to Doppler effects in the Milky Way Halo to date. Accounting for frequency shifts due to the detector’s motion through the Galaxy, we exclude cold flow relic axions with a velocity dispersion of $\mathcal{O}({10}^{-7})\mathrm{c}$ with 95% confidence.

QCD axion models have been proposed as a solution to the strong $CP$ problem. QCD instanton effects explicitly violate the global U(1) Peccei-Quinn (PQ) symmetry, and the axion potential is minimized at the $CP$ conserving points. However, it is expected that the global U(1) PQ symmetry is explicitly violated by quantum gravity. This gravitational violation may potentially undermine the PQ solution to the strong $CP$ problem, which is referred to as the axion quality problem. One source of explicit PQ violation is axionic wormholes, such as the Giddings-Strominger model. Generally speaking, the extent to which the U(1) PQ symmetry is violated depends on models. One straightforward extension of Einstein gravity involves quadratic scalar curvature, which is motivated in cosmological contexts, such as inflation. The aim of this work is to investigate the effects of $R^2$ corrections on axionic wormholes. In this paper, we compute wormhole solutions and evaluate the size of explicit PQ violation in the models with the $R^2$ term. Furthermore, we illustrate the differences between the metric and Palatini formulations.

Using Wilsonian renormalization, we calculate the quantum correction to observable quantities, rather than the bare parameters, of the Higgs field. A physical parameter, such as a mass-squared or a quartic coupling, at an energy scale $\mu$ is obtained from that at a reference scale by integrating in the degrees of freedom in between. In this process, heavy modes decouple and the ultraviolet scale dependence is canceled in the observables. An exact renormalization group equation is parametrized by the low-energy scale $\mu$.

Building on work by Hang and He, we show how the residual five-dimensional diffeomorphism symmetries of compactified gravitational theories with a warped extra dimension imply equivalence theorems which ensure that the scattering amplitudes of helicity-0 and helicity-1 spin-2 Kaluza-Klein states equal (to leading order in scattering energy) those of the corresponding Goldstone bosons present in the ’t-Hooft-Feynman gauge. We derive a set of Ward identities that leads to a transparent power-counting of the scattering amplitudes involving spin-2 Kaluza-Klein states. We explicitly calculate these amplitudes in terms of the Goldstone bosons in the Randall-Sundrum model, check the correspondence to previous unitary-gauge computations, and demonstrate the efficacy of ’t-Hooft-Feynman gauge for accurately computing amplitudes for scattering of the spin-2 states both among themselves and with matter. Power-counting for the Goldstone boson interactions establishes that the scattering amplitudes grow no faster than $\mathcal{O}(s)$, explaining the origin of the behavior previously shown to arise from intricate cancellations between different contributions to these scattering amplitudes in unitary gauge. We describe how our results apply to more general warped geometries, including models with a stabilized extra dimension. We explicitly identify the symmetry algebra of the residual 5D diffeomorphisms of a Randall-Sundrum extra-dimensional theory.

In this paper, we present predictions for scattering cross section the of Higgs boson pair production via photon fusion at future muon colliders, focusing specifically the production processes ${\mu }^{+}{\mu }^{-}\to \gamma \gamma \to h^0{h}^0,A^0{A}^0$. We investigated the impact of three choices the photon structure functions on cross-section predictions for a range model input parameters within the theoretical framework of the Higgs triplet model [Phys. Rev. D 84, 095005 (2011); Eur. Phys. J. C 79, 940 (2019); Phys. Rev. D 22, 2227 (1980); Phys. Rev. D 25, 2951 (1982)].

Radiative decays $X\to \psi (1S)\gamma$ and $X\to {\psi }^{\prime }(2S)\gamma$ might be expected to have a ratio of branching fractions following the phase space volumes ratio. However data suggest the opposite, indicating a value for $\mathcal{R}=\mathcal{B}({\psi }^{\prime }\gamma )/\mathcal{B}(\psi \gamma )$ consistently larger than one. In this paper we present a calculation of $\mathcal{R}$ for both a compact diquark-antidiquark $(cq)(\overline{c}\overline{q})$ state and a $D{\overline{D}}^{*}$ molecule. In the former case $\mathcal{R}\sim 1$ or larger is found. In contrast, in the molecular picture, with $D$ and ${\overline{D}}^{*}$ mesons described by the universal wave function used by Voloshin, Braaten and Kusunoki, we find $\mathcal{R}$ to be of order ${10}^{-2}$. These starkly different predictions are to be confronted with forthcoming high-statistics data analyses; a more precise experimental measure would be extremely helpful in clarifying the true nature of the $X(3872)$.

We explore the quantum chromodynamics (QCD) phase diagram’s complexities, including quark deconfinement transitions, liquid-gas phase changes, and critical points by using the chiral mean-field (CMF) model that is able to capture all these features. We introduce a vector meson field redefinition within the CMF framework, enabling precise adjustments of meson masses and coupling strengths related to vector meson interactions. Performing a new fit to the deconfinement potential, we are able to replicate recent lattice QCD results, low-energy nuclear physics properties, neutron star observational data, and key phase diagram features as per modern constraints. This approach enhances our understanding of vector mesons’ roles in mediating nuclear interactions and their impact on the equation of state, contributing to a more comprehensive understanding of the QCD phase diagram and its implications for nuclear and astrophysical phenomena.

We show that the negative polarized gluon distribution $\mathrm{\Delta }g$ found in a recent global next-to-leading-order QCD analysis of the nucleon helicity structure is incompatible with the fundamental requirement that physical cross sections must not be negative. Specifically, we show that the fact that this polarized gluon strongly violates the positivity condition $|\mathrm{\Delta }g|\le g$ in terms of the unpolarized gluon distribution $g$ leads to negative cross sections for Higgs boson production at RHIC as a physical process, implying that this negative $\mathrm{\Delta }g$ is unphysical.

We find bounds on the Wilson coefficients of effective field theories (EFTs) living in a universe undergoing expansion by requiring that its modes do not propagate further than a minimally coupled photon by a resolvable amount. To do so, we compute the spatial shift suffered by the EFT modes at a fixed time slice within the WKB approximation and the regime of validity of the EFT. We analyze the bounds arising on shift-symmetric scalars and curved space generalizations of Galileons.

Upgrades beyond the current second generation of ground-based gravitational wave detectors will allow them to observe tens of thousands neutron star and black hole binaries. Given the typical minute-to-hour duration of neutron star signals in the detector frequency band, a number of them will overlap in the time-frequency plane, resulting in a nonzero cross-correlation. We examine “source confusion” arising from overlapping signals whose time-frequency tracks cross. Adopting the median observed merger rate of $100{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1}$, each neutron star binary signal overlaps with an average of 42(4)[0.5] other signals when observed from 2(5)[10] Hz. The vast majority of overlaps occur at low frequencies where the inspiral evolution is slow: 91% of time-frequency overlaps occur in band below 5 Hz. The combined effect of overlapping signals does not satisfy the central limit theorem and source confusion cannot be treated as stationary, Gaussian noise: on average 0.91(0.17)[0.05] signals are present in a single adaptive time-frequency bin centered at 2(5)[10] Hz. We quantify source confusion under a realistic neutron star binary population and find that parameter uncertainty typically increases by less than 1% unless there are overlapping signals whose detector-frame chirp mass difference is $\lesssim 0.01M_{\odot }$ and the overlap frequency is $\gtrsim 40\mathrm{Hz}$. Out of $1\times {10}^6$ simulated signals, 0.14% fall within this region of detector-frame chirp mass differences, but their overlap frequencies are typically lower than 40 Hz. Source confusion for ground-based detectors, where events overlap instantaneously, is significantly milder than the equivalent Laser Interferometer Space Antenna problem, where many classes of events overlap for the lifetime of the mission.