We study the recently observed $\mathrm{\Omega }(2012)$ baryon in quantum chromodynamics (QCD) sum rules. We construct the $P$-wave $\mathrm{\Omega }$ baryon currents with a covariant derivative, and perform spin projection to obtain the currents with total spin $1/2$ and $3/2$. We then apply the parity-projected QCD sum rules to separate the contributions of the positive and negative parity states. We extract the masses of $J^P=1/2^{-}$ and $3/2^{-}$ states to be $M_{1/2^{-}}={2.07}_{-0.07}^{+0.07}\mathrm{GeV}$ and $M_{3/2^{-}}={2.05}_{-0.10}^{+0.09}\mathrm{GeV}$. Both results are in good agreement with the experimental result. Therefore, it is likely that the $\mathrm{\Omega }(2012)$ is a negative parity state, which is interpreted as a $P$-wave excited state in the quark model. However, its spin is not determined in the present analysis, which can be done by detailed study on its decay properties.

We provide the analytic waveform in time domain for the scattering of two Kerr black holes at leading order in the post-Minkowskian (weak field, but generic velocity) expansion and up to fourth order in both spins. The result is obtained by the generalization of the Kosower-Maybee-O’Connell formalism to radiative observables, combined with the analytic continuation of the five-point scattering amplitude to complex kinematics. We use analyticity arguments to express the waveform directly in terms of the three-point coupling of the graviton to the spinning particles and the gravitational Compton amplitudes, completely bypassing the need to compute and integrate the five-point amplitude. In particular, this allows us to easily include higher-order spin contributions for any spinning compact body. Finally, in the spinless case, we find a new compact and gauge-invariant representation of the Kovacs-Thorne waveform.

We investigate the first-order phase transition catalyzed by primordial black holes (PBHs) in the early Universe. We find that superhorizon curvature perturbations generated in this scenario lead to the production of gravitational waves when the scalar modes reenter the horizon. If PBHs with masses about ${10}^{-13}{M}_{\odot }$ constitute all dark matter, then the first-order electroweak phase transition catalyzed by PBHs can explain the gravitational wave signal observed by pulsar timing array collaborations without the overproduction of PBHs.

We study the modifications to the fragmentation pattern of partons into charged particles in the presence of a hot and dense quark gluon plasma. To this end, we analyze the perturbative renormalization group equations of the track functions, which describe the energy fraction carried by charged hadrons. Focusing on pure Yang-Mills theory, we compute the lowest-order moments of the medium-modified track functions, which are found to be sensitive to the reduced phase space for emissions in the medium and to energy loss. We use the extracted moments to calculate the energy energy correlator (EEC) on tracks in the collinear limit. The EEC on medium-evolved tracks does not differ qualitatively from the EEC on vacuum tracks despite being sensitive to the color decoherence transition and suppressing the distribution due to quenching, as seen in other jet observables.

We search for the diphoton decay of a light pseudoscalar axionlike particle, $a$, in radiative $J/\psi$ decays, using ${10}^{10}J/\psi$ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the 95% confidence level on the product branching fraction $\mathcal{B}(J/\psi \to \gamma a)\times \mathcal{B}(a\to \gamma \gamma )$ and the axionlike particle photon coupling constant $g_{a\gamma \gamma }$ in the ranges of $(3.7–48.5)\times {10}^{-8}$ and $(2.2–101.8)\times {10}^{-4}{\mathrm{GeV}}^{-1}$, respectively, for $0.18\le m_a\le 2.85\mathrm{GeV}/c^2$. These are the most stringent limits to date in this mass region.

We study the holographic dual of a topological symmetry operator in the context of the AdS/CFT correspondence. Symmetry operators arise from topological field theories localized on a subspace of the boundary conformal field theory spacetime. We use bottom up considerations to construct the topological sector associated with their bulk counterparts. In particular, by exploiting the structure of entanglement wedge reconstruction we argue that the bulk counterpart has a nontopological world volume action, i.e., it describes a dynamical object. As a consequence, we find that there are no global $p$-form symmetries for $p\ge 0$ in asymptotically anti–de Sitter spacetimes, which includes the case of noninvertible symmetries. Provided one has a suitable notion of subregion-subregion duality, our argument for the absence of bulk global symmetries applies to more general spacetimes. These considerations also motivate us to consider for general QFTs (holographic or not) the notion of lower-form symmetries, namely, ($-m$)-form symmetries for $m\ge 2$.

The dimension of the Hilbert space of a quantum gravitational system can be written formally as a path integral partition function over Lorentzian metrics. We implement this in a ($2+1$)-dimensional simplicial minisuperspace model in which the system is a spatial topological disc, and recover by contour deformation through a Euclidean saddle the entropy of the de Sitter static patch, up to discretization artifacts. The model illustrates the importance of integration over both positive and negative lapse to enforce the gravitational constraints, and of restriction to complex metrics for which the fluctuation integrals would converge. Although a strictly Lorentzian path integral is oscillatory, an exponentially large partition function results from unavoidable imaginary contributions to the action. These arise from analytic continuation of the simplicial (Regge) action for configurations with codimension-2 simplices where the metric fails to be Lorentzian. In particular, the dominant contribution comes from configurations with contractible closed timelike curves that encircle the boundary of the disc, in close correspondence with recent continuum results.

We analyze the proposal of defining the Weyl anomaly for classically nonconformal theories as $g^{mn}⟨T_{mn}⟩-⟨g^{mn}{T}_{mn}⟩$, originally put forward by Duff, in the case of a scalar field with quartic self-interaction in 4d. We work in the context of dimensional regularization in curved background to two loops (first order in the coupling). We review the original regularized but not renormalized prescription and its ambiguities; we argue that it cannot be extended to the interacting theory as it fails to provide a finite result. We then propose an alternative prescription via renormalized expectation values. At one loop, our candidate reproduces the local heat kernel result, while its extension to interacting theories contains nonlocal contributions.

This work investigates the thermal Casimir effect associated with a massive spinor field defined on a four-dimensional flat space with a circularly compactified spatial dimension whose periodicity is oriented along a vector in the $xy$ plane. We employ the generalized zeta function method to establish a finite definition for the vacuum free energy density. This definition conveniently separates into the zero-temperature Casimir energy density and additional terms accounting for temperature corrections. The structure of existing divergences is analyzed from the asymptotic behavior of the spinor heat kernel function and removed in the renormalization by subtracting scheme. The only non-null heat coefficient is the one associated with the Euclidean divergence. We also address the need for a finite renormalization to treat the ambiguity in the zeta function regularization prescription associated with this Euclidean heat kernel coefficient and ensure that the renormalization procedure is unique. The high- and low-temperature asymptotic limits are also explored. In particular, we explicitly show that free energy density lacks a classical limit at high temperatures, and the entropy density agrees with the Nernst heat theorem at low temperatures.

This article studies mode stability of a four-dimensional rotating black hole with four pairwise equal U(1) charges derived in the framework of supergravity or the low energy string theory which is known now as STU black hole. We investigate bosonic perturbations in a proposed equation of the Teukolsky type for probe fields of different spins through the transformation technique devised by Whiting in 1989. Finally, we introduce connection relations inspired by the work of Duztaş [Phys. Rev. D 94, 044025 (2016) ] to prove the absence of unstable modes that solve the torsion-modified Dirac equation appropriate for this black hole background.

This paper considers the possibility that, starting from a relativistic Hermitian quantum field theory in the ultraviolet (UV) regime, and applying a nonperturbative renormalization-group (RG) flow, we arrive at a situation where there are infrared (IR) singularities in the RG flow of couplings. The latter can be resolved by assuming that the theory can have a phase described by a related non-Hermitian $\mathcal{PT}$-symmetric modification in the IR. The UV-to-IR (Hermitian-to-$\mathcal{PT}$-symmetric) transition can occur in a single renormalization-group flow of the pertinent couplings, as demonstrated in concrete examples. When embedded in a gravitational setting such a transition can lead to a repulsive gravity phase. If there is a RG flow to a repulsive $\mathcal{PT}$ -symmetric gravity, then this would be an alternative to dark energy. The discussion here is presented in the context of a string-inspired Chern-Simons gravitational effective action, which involves a pseudoscalar (axionlike) field coupled to Abelian gauge fields and gravity; it may also hold more generally in gravity with torsion. The validity of such a scenario in realistic theories might alleviate the need for de Sitter phases in the current epoch of cosmological evolution, thus avoiding their associated conceptual and technical complications.

We study the interplay between higher-curvature terms and the backreaction of quantum fluctuations in three-dimensional massive gravity in asymptotically (anti–)de Sitter space. We focus on the theory at the special point of the parameter space where the two maximally symmetric vacua coincide. In the case of positive cosmological constant, this corresponds to the partially massless point, at which the classical theory admits de Sitter black holes and exhibits an extra conformal symmetry at linear level. We explicitly find the quantum corrected black hole geometry in the semiclassical approximation and show that it induces a relaxation of the standard asymptotic conditions. Nonetheless, the new asymptotic behavior is still preserved by an infinite-dimensional algebra, which, in addition to Virasoro, contains logarithmic supertranslations. Finally, we show that all the results we obtain for the quadratic massive gravity theory can be extended to theories including cubic and quartic terms in the curvature.

It has been reported that the photon ring structure in black hole images produces strong and universal interferometric signatures on long interferometric baselines, holding promise for measuring black hole parameters and testing general relativity. This paper investigates the interferometric signatures of black holes with one or two photon spheres, specifically within the framework of Einstein-Maxwell-scalar models. Notably, for black holes possessing two photon spheres, interference between light rays orbiting the inner and outer photon spheres manifests as beat signals in the visibility amplitude, deviating from the universal signatures observed in the single-photon sphere case.

We revisit static, spherically symmetric solutions to anti–de Sitter (AdS)-Einstein gravity with a conformally coupled scalar field (and no self-interaction potential) in four dimensions. We first observe that a convenient choice of coordinates leads to a significant simplification of the field equations, which enables one to identify various roots of the indicial equations and thus distinct branches of solutions. Next, we construct an explicit 2-parameter hairy black hole solution in terms of an infinite power series around the event horizon. The black hole is nonextremal with a regular scalar field on and outside the event horizon, and it reduces to the Schwarzschild-AdS metric in the limit of vanishing hair. Its properties are illustrated for various values of the parameters and compared with previous numerical results by other authors. In addition, the analysis reveals the presence of a photon sphere and how the scalar field affects its size and the angular radius of the corresponding shadow. The thermodynamics of the solution is also briefly discussed.

The aether scalar-tensor (AeST) theory is an extension of general relativity, proposed for addressing galactic and cosmological observations without dark matter. By casting the AeST theory into a $3+1$ form, we determine its full nonperturbative Hamiltonian formulation and analyze the resulting constraints. We find the presence of four first class and four second class constraints and show that the theory has six physical degrees of freedom at the fully nonlinear level. Our results set the basis for determining the propagation of perturbations on general backgrounds and we present the case of small perturbations around Minkowski spacetime as an example stemming from our analysis.

Kinematic lensing (KL) is a new weak lensing technique that reduces shape noise for disk galaxies by including spectroscopically measured galaxy kinematics in addition to photometrically measured galaxy shapes. Since KL utilizes the Tully-Fisher relation, any correlation of this relation with the local environment may bias the cosmological interpretation. For the first time, we explore such a Tully-Fisher environmental dependence (TED) effect as a potential astrophysical systematic for KL. Our derivation of the TED systematic can be described in a similar analytical form as intrinsic alignment for traditional weak lensing. We demonstrate analytically that TED only impacts KL if intrinsic alignment for disk galaxies is nonzero. We further use IllustrisTNG simulations to quantify the TED effect. Our two-point correlation measurements do not yield any additional coherent signals that would indicate a systematic bias on KL, within the uncertainties set by the simulation volume.

The possibility that quantum geometry effects may alleviate the apparent tensions existing at large angular scales in the observations of the cosmic microwave background explains the increasing interest in considering primordial perturbations within the framework of loop quantum cosmology. In this framework, a number of approximations have been suggested to simplify the study of perturbations and derive analytic expressions for the power spectra. This study requires a new choice of vacuum state that takes into account the preinflationary background geometry, a choice for which we adopt the so-called nonoscillating with asymptotic Hamiltonian diagonalization (NO-AHD) prescription. Here, we apply the aforementioned approximations to the investigation of scalar perturbations. We discuss two approaches to the quantization of perturbations in loop quantum cosmology, namely the hybrid and the dressed metric approaches. We improve previous approximations by including slow-roll corrections in the inflationary era. Moreover, for the first time in the literature of the NO-AHD prescription, we compute numerically the primordial power spectra for the two considered approaches, and show that the analytic estimations are remarkably accurate for all observable modes. We also discuss the similarities and differences between the spectra obtained with those two approaches.

It is currently unknown how matter behaves at the extreme densities found within the cores of neutron stars. Gravitational waves from binary neutron star mergers encode rich information about the stars’ deformability, allowing the equation of state—and hence nuclear physics—to be inferred. Planned third-generation gravitational-wave observatories, having vastly improved sensitivity, are expected to provide tight constraints on the neutron star equation of state. We combine simulated observations of binary neutron star mergers by the third-generation observatories Cosmic Explorer and Einstein Telescope to determine future constraints on the equation of state across a plausible neutron star mass range. In one year of operation, a network consisting of one Cosmic Explorer and the Einstein Telescope is expected to detect $\gtrsim 3\times {10}^5$ binary neutron star mergers. By considering only the 75 loudest events, we show that such a network will be able to constrain the neutron star radius to at least $\lesssim 200\mathrm{m}$ (90% credibility) in the mass range $1–1.97M_{\odot }$—about ten times better than current constraints from LIGO-Virgo-KAGRA and NICER. The constraint is $\lesssim 75\mathrm{m}$ (90% credibility) near $1.4–1.6M_{\odot }$ where we assume the binary neutron star mass distribution is peaked. This constraint is driven primarily from the loudest $\sim 20$ events.

The mass ranges allowed for primordial black holes (PBHs) to constitute all of dark matter (DM) are broadly constrained. However, these constraints rely on the standard semiclassical approximation which assumes that the evaporation process is self-similar. Quantum effects such as memory burden take the evaporation process out of the semiclassical regime latest by the time the black hole loses half of its mass. What happens beyond this time is currently not known. However, theoretical evidence based on prototype models indicates that the evaporation slows down, thereby extending the lifetime of a black hole. This modifies the mass ranges constrained, in particular, by big bang nucleosynthesis (BBN) and cosmic microwave background spectral distortions. We show that previous constraints are largely relaxed when the PBH lifetime is extended, making it possible for PBHs to constitute all of DM in previously excluded mass ranges. In particular, this is the case for PBHs lighter than ${10}^9\mathrm{g}$ that enter the memory burden stage before BBN and are still present today as DM.