In this paper, based on the $T\overline{T}$ deformed version of ${\mathrm{dS}}_3/{\mathrm{CFT}}_2$ correspondence, we calculate the pseudoentropy for an entangling surface consisting of two antipodal points on a sphere and find it is exactly dual to the complex geodesic in the bulk.

We present a Lagrangian approach to counting degrees of freedom in first-order field theories. The emphasis is on the systematic attainment of a complete set of constraints. In particular, we provide the first comprehensive procedure to ensure the functional independence of all constraints and discuss in detail the possible closures of the constraint algorithm. We argue degrees of freedom can but need not correspond to physical modes. The appendix comprises fully worked out, physically relevant examples of varying complexity.

We discuss spontaneous scalarization of the Reissner-Nordström black hole in the presence of higher derivative gauge field corrections that arise in the context of string, as well as higher-dimensional more fundamental gravity theories. Our theory admits the Reissner-Nordström solution at the scalar vacuum of the theory ($\varphi =0$), and we find that the higher order derivative gauge field correction term results in the tachyonic instability of our system once the coupling function satisfies the condition that its second derivative is positive at the scalar vacuum in the appropriate parameter space. We find that the branches do not end with an extremal black hole, rather with a singularity as indicated by the divergence of the Kretschmann scalar. The black holes can be overcharged in the sense that they may carry larger electric charge in comparison to their mass. Finally, these solutions possess larger entropy at the event horizon radius when compared to the Reissner-Nordström black hole, as well as to scalarized black holes without the higher order derivative gauge field terms, indicating in this way the thermodynamic stability and preferability of our system, when compared to existing literature, while they respect the energy conditions.

We present explicit black holes endowed with primary scalar hair within the shift-symmetric subclass of beyond Horndeski theories. These solutions depend, in addition to the conventional mass parameter, on a second free parameter encoding primary scalar hair. The properties and characteristics of the solutions at hand are analyzed with a varying scalar charge. We observe that when the scalar hair parameter is close to zero or relatively small in comparison to the black-hole mass, the solutions closely resemble the Schwarzschild spacetime. As the scalar hair increases, the metric solutions gradually depart from general relativity. Notably, for a particular relation between mass and scalar hair, the central singularity completely disappears, resulting in the formation of regular black holes or solitons. The scalar field accompanying the solutions is always found to be regular at future or past horizon(s), defining a distinct time direction for each. As a final by-product of our analysis, we demonstrate the existence of a stealth Schwarschild black hole in Horndeski theory with a nontrivial kinetic term.

We investigate quantum cosmology in teleparallel $f(T)$ gravity. We delve extensively into the minisuperspace description within the context of teleparallelism. The $f(T)$ theory constitutes a second-order theory of gravity, whose cosmological counterpart is delineated by a degenerate pointlike Lagrangian. To formulate the Hamiltonian function encompassing all constraints and degrees of freedom inherent to $f(T)$ cosmology, we employ the Dirac-Bergmann algorithm. Subsequently, we determine the wave function of the universe and introduce a “probabilistic” interpretation. We perform comparisons to some classical solutions to see to what extent the quantum approach can cure classical singularities.

The Brazilian Mario Schenberg gravitational-wave detector was initially designed in the early 2000s and remained operational until 2016 when it was disassembled. To assess the feasibility of reassembling the Schenberg antenna, its capability to detect gravitational waves (GW) within its designed sensitivity parameters needs to be evaluated. Detection of significant signals would serve as a catalyst for rebuilding the detector. Although the antenna is currently disassembled, insights can be gleaned from the third observing run (O3) data of the LIGO detectors, given the similarities between Schenberg’s ultimate sensitivity and the interferometers’ sensitivity in the [3150–3260] Hz band. The search focused on signals lasting from milliseconds to seconds, with no assumptions about their morphology, polarization, and arrival sky direction. Data analysis was performed using the coherent WaveBurst pipeline in the frequency range between 512 Hz and 4096 Hz, specifically targeting signals with bandwidths overlapping the Schenberg frequency band. However, the O3 data did not yield statistically significant evidence of GW bursts. This null result allowed for the characterization of the search efficiency in identifying simulated signal morphologies and setting upper limits on the GW burst event rate as a function of strain amplitude. The current search, and by extension the advanced version of the Schenberg antenna (aSchenberg), can detect sources emitting isotropically $5\times {10}^{-6}{M}_{\odot }{c}^2$ in GWs from a distance of 10 kiloparsecs with a 50% detection efficiency at a false alarm rate of 1 per 100 years. Moreover, we revisited estimations of detecting f modes of neutron stars excited by glitches, setting the upper limit of the f-mode energy for the population of Galactic pulsars to $\sim 8\times {10}^{-8}{M}_{\odot }{c}^2$ at 3205 Hz. Our simulations and the defined detection criteria suggest f modes are a very unlikely source of gravitational waves for the aSchenberg. Nevertheless, its potential in probing other types of gravitational wave short transients, such as those arising from supernova explosions, giant flares from magnetars, postmerger phase of binary neutron stars, or the inspiral of binaries of primordial black holes with subsolar masses, remains promising.

We compute the $\mathcal{O}(k^2)$ terms (power corrections) of the photon polarization tensor in a hot and dense medium of particles with a small but finite mass, i.e., $0<m\ll T$, $\mu$. We perform our calculations within the hard thermal loop approximation in the real-time formalism, and evaluate the first nonzero mass corrections. For a renormalization scale $\overline{\mathrm{\Lambda }}\sim T$, these mass contributions determine the temperature dependence of the power corrections. These results have direct implications in the computation of electric and magnetic susceptibilities of hot and dense media in equilibrium. We address such implications and make comparisons with previous results.

We evaluate the entanglement entropy and entropic function of massive two dimensional quantum electrodynamics (Schwinger model) at finite temperature, density, and $\theta$-angle. In the strong coupling regime, the entropic function is dominated by the boson mass for large spatial intervals, and reduces to the conformal field theory result for small spatial intervals. We also discuss the entanglement spectrum at finite temperature and a finite $\theta$-angle.

The attractive feature of supersymmetry is predictive power, due to the large number of calculable properties and to coupling nonrenormalization. This power can be fully expressed in hidden sectors where supersymmetry may be exact, as these sectors are secluded from the visible one where instead supersymmetry must be broken. This suggests a new paradigm for supersymmetric dark sectors, where supersymmetry is exact at the dark matter scale, implying that many properties of hidden supersymmetric dark sectors can be fully computed. As a proof of concept we discuss a concrete example based on $\mathcal{N}=1$ super Yang-Mills.

Charm quark production and its hadronization in $ep$ and $eA$ collisions at the future Electron-ion Collider in China (EicC) will help us understand the quark/gluon fragmentation processes and the hadronization mechanisms in the nuclear medium, especially within a poorly constrained kinematic region ($x<0.1$). In this paper, we report a study on the production of charmed hadrons, $D^0$ and ${\mathrm{\Lambda }}_c^{+}$, reconstructed with a dedicated geant4 simulation of vertex and tracking detectors designed for EicC. The ${\mathrm{\Lambda }}_c^{+}/D^0$ ratios as functions of multiplicity and $p_T$, as well as the $D^0$ double ratio are presented with projected statistical precision.

Continuous phase transitions can be classified into ones characterized by local-order parameters and others that need additional topological constraints. The critical dynamics near the former transitions have been extensively studied, but the latter is less understood. We fill this gap in knowledge by studying the transition dynamics to a parity-breaking topological ground state called the chiral soliton lattice in quantum chromodynamics at finite temperature, baryon chemical potential, and an external magnetic field. We find a slowing down of the soliton’s translational motion as the critical magnetic field approaches, while the local relaxation rate to the solitonic state remains finite. The time required to converge to the stationary state strongly depends on the symmetry of the initial configuration, determining whether translational motion occurs during the dynamic process.

The Belle Collaboration recently reported a promising candidate for the spin-2 $D^{*}{\overline{D}}^{*}$ partner of the $X(3872)$, called the $X_2$ for short, having a mass of $(4014.3\pm 4.0\pm 1.5)\mathrm{MeV}$ and a width of $(4\pm 11\pm 6)\mathrm{MeV}$. Assuming the $X_2$ as a pure molecule of the $D^{*}{\overline{D}}^{*}$, we calculated in detail the hidden charmonium decays of the $X_2\to J/\psi V$ and $X_2\to {\eta }_{c}P$ via the intermediate meson loops, where $V={\rho }^0,\omega$ and $P={\pi }^0,\eta ,{\eta }^{\prime }$. The results indicate that the decay widths are strongly dependent on the $X_2$ mass. At present center value of the mass 4014.3 MeV, the width for the $X_2\to J/\psi {\rho }^0$ is predicted to be a few tens of keV, while it is on the order of ${10}^{2-3}\mathrm{keV}$ for the $X_2\to J/\psi \omega$; the predicted width for the $X_2\to {\eta }_c{\pi }^0$ is about a few keV, while the widths for $X_2\to {\eta }_c\eta$ and ${\eta }_c{\eta }^{\prime }$ are around a few tens and tenths of keV, respectively. We also investigated the dependence of the ratios between these widths on the $X_2$ mass and on the $\eta -{\eta }^{\prime }$ mixing angle, which may be good quantities for experiments. We hope that the present calculations will be checked experimentally in the future.

We study the $J/\psi \pi$ and $D{\overline{D}}^{*}$ coupled-channel system within a covariant framework. The $J/\psi \pi$ and $D{\overline{D}}^{*}$ invariant-mass distributions measured at 4.23 and 4.26 GeV by BESIII and the finite-volume energy levels from recent lattice QCD simulations are simultaneously fitted. Phase shifts and inelasticities of the $J/\psi \pi$ and $D{\overline{D}}^{*}$ scattering are predicted using the resulting amplitudes. Poles corresponding to the $Z_c(3900)$ state are found in the complex energy plane and their couplings with $J/\psi \pi$ and $D{\overline{D}}^{*}$ are determined. Our results indicate that the current lattice data do not preclude the existence of the $Z_c(3900)$ state.

We demonstrate that the recently introduced evanescent particles of a massive scalar field can be emitted and absorbed by an Unruh-DeWitt detector. In doing so the particles carry away from or deposit on the detector a quantized amount of energy, in a manner quite analogous to ordinary propagating particles. In contradistinction to propagating particles the amount of energy is less than the mass of the field, but still positive. We develop relevant methods and provide a study of the detector emission spectrum, emission probability and absorption probability involving both propagating and evanescent particles.

Under the framework of gravitational effective field theory, we propose a theory agnostic strategy of searching for higher-spin particles with gravitational waves from compact binary inspirals. Using this strategy, we analyze gravitational wave signals from the binary black hole merger events GW151226 and GW170608, as well as the binary neutron star merger event GW170817. We find that the existence of higher-spin particles with mass ranged from ${10}^{-12}\mathrm{eV}$ to ${10}^{-11}\mathrm{eV}$ is strongly disfavored by these events unless the particles precisely combine within a supersymmetric supermultiplet. We argue that the gravitational effective field theory also provides a framework to search for signals beyond GR from other GW observations, such as extreme-mass-ratio inspirals.

We study circular orbits that are tilted with respect to the equatorial plane around a Kerr black hole. We write the equations for the parameters of a tilted circular orbit in terms of the orbit’s radius and the Carter constant, or equivalently, the tilt angle. The tilted innermost stable circular orbits (TISCO)s are discussed as well as the last circular orbits. The azimuthal precession of an orbit is then studied, and an approximate expression for the precession speed is given. We finally try to link tilted circular orbits to quaiperiodic oscillations in some astrophysical black hole systems.

In this article, the possibility of generating nonclassical light due to Planck-scale effects is considered. For this purpose, a widely studied model of deformation of the Heisenberg uncertainty relation is applied to single-mode and multimode lights. The model leads to a deformed dispersion relation, which manifests in an advancement in the time of arrival of photons. The key finding is that the model also leads to an oscillatory pattern of squeezing of the state of light. Furthermore, while the amplitude of the oscillations is constant for energy eigenstates, it exhibits linear growth over time for coherent states with the annihilation operator eigenvalue $\alpha \ne 0$. This second case leads to the accumulation of squeezing and phase-space displacement, which can be significant for astrophysical photons. In particular, for $\alpha \sim 1$, coherent light in the optical spectrum emitted at megaparsec distances would acquire squeezing with the amplitude of the order unity. This suggests that measurements of the nonclassical properties of light originating from distant astrophysical sources may open a window to test these predictions.

We investigate quasitopological black holes in ($2+1$) dimensions in the context of electromagnetic-generalized-quasitopological gravities (EM-GQT). For three different families of geometries of quasitopological nature, we study the causal structure and their response to a probe scalar field. To linear order, we verify that the scalar field evolves stably, decaying in different towers of quasinormal modes. The studied black holes are either charged geometries (regular and singular) or a regular Bañados-Teitelboim-Zanelli (BTZ)-like black hole, both coming from the EM-GQT theory characterized by nonminimal coupling parameters between gravity and a background scalar field. We calculate the quasinormal modes applying different numerical methods with convergent results between them. The oscillations demonstrate a very peculiar structure for charged black holes: in the intermediate and near extremal cases, a particular scaling arises, similar to that of the rotating BTZ geometry, with the modes being proportional to the distance between horizons. For the single horizon black hole solution, we identify the presence of different quasinormal families by analyzing the features of that spectrum. In all three considered geometries, no instabilities were found.

This paper introduces the class of omnipotent dark energy (DE) models characterized by nonmonotonic energy densities that are capable of attaining negative values with corresponding equation of state parameters featuring phantom divide line (PDL) crossings and singularities. These nontrivial features are phenomenologically motivated by findings of previous studies that reconstruct cosmological functions from observations, and the success of extensions of $\mathrm{\Lambda }\mathrm{CDM}$, whose actual or effective DE density is omnipotent, in alleviating the observational discordance within $\mathrm{\Lambda }\mathrm{CDM}$. As an example, we focus on one embodiment of omnipotent DE, viz. the DE parametrization introduced in Di Valentino et al. [Dark energy with phantom crossing and the $H_0$ tension, Entropy 23, 404 (2021)] (DMS20). By updating and extending the datasets used in the original paper where it was introduced, we confirm the effectiveness of DMS20 in alleviating the observational discrepancies. Additionally, we uncover that its negative DE density feature, importance of which was not previously investigated, plays a crucial role in alleviating the tensions, along with the PDL crossing feature that the parametrization presupposes. In particular, we find that there is a positive correlation between the $H_0$ parameter and the scale ($a_{\mathrm{p}}$) at which DE density transitions from negative to positive, in agreement with previous studies that incorporate this transition feature. For our full dataset, the model yields $H_0=70.05\pm 0.64$ (68% CL) relaxing the $H_0$ tension with a preference of crossing to negative DE densities ($a_{\mathrm{p}}>0$ at 99% CL), along with the constraint $a_m=0.922_{-0.035}^{+0.041}$ on the scale of the presupposed PDL crossing.