In this work we investigate the properties of neutron stars admixed with self-interacting scalar bosonic dark matter. The dark matter interaction is described by a generalized ${\varphi }^n$ power-law potential. We perform a stability analysis of these two-fluid objects by studying the onset of the unstable radial modes. We find ultracompact neutron star-dark matter configurations where the neutron star matter is confined to a core radius of values below 7 km which is unreachable for pure neutron stars. The total gravitational maximum mass of these ultracompact configurations can have values of $3.4M_{\odot }$. With our general ansatz of the power-law potential we show that the compactness of these solutions can be extreme, i.e. the compactness is $C=1/3$ or even larger, making them compact enough to have a light-ring mimicking black holes. These ultracompact objects are stable and possess a dark matter halo while having a hadronic matter core. With the addition of dark matter to neutron stars recent unusual mass-radius measurements of compact stars can be explained. We conclude that apparently contradictory measurements of neutron star masses and radii could be not only an indication of the presence of dark matter around a the hadronic matter core which is stabilized by the gravitational potential of dark matter but could also serve to disentangle the self-interaction strength of dark matter. Our work points to a stiff equation of state for the dark matter fluid, rather than a soft one.

We simulate Floquet time evolution of a truncated SU(3) lattice Yang-Mills theory on a two-leg ladder geometry under open boundary conditions using IBM’s superconducting 156-qubit device ibm_fez. To this end, we derive the quantum spin representation of the lattice Yang-Mills theory and compose a quantum circuit carefully tailored to hardware, reducing the number of controlled-Z gates. Since it is still challenging to simulate Hamiltonian evolution in present noisy quantum processors, we make the step size in the Suzuki-Trotter decomposition very large and simulate thermalization dynamics in Floquet circuit composed of the Suzuki-Trotter evolution. We demonstrate that IBM’s Heron quantum processor can simulate, by error mitigation, Floquet thermalization dynamics in a large system consisting of 62 qubits. Our work would be a benchmark for further quantum simulations of lattice gauge theories using real devices.

We describe a generalization of the hybrid Monte Carlo (HMC) algorithm in which the molecular dynamics steps utilize Nambu generalized Hamiltonian dynamics. Nambu mechanics contains multiple Hamiltonian functions. Using one of these Hamiltonians in the Metropolis accept/reject step is enough to guarantee the correct target distribution. The other Hamiltonians can include arbitrary functions of the gauge field. We examine the simplest case with two Hamiltonians and choose the second to include nonlocal functions of the gauge field. In this way, the links are updated with instantaneous knowledge of far-separated link variables. This represents a promising method for reducing critical slowing down in lattice QCD simulations.

We have studied the $N{D}^{*}{\overline{K}}^{*}$ system in the framework of the fixed center approximation to the Faddeev equations, taking the exotic $D^{*}{\overline{K}}^{*}$ system as the cluster and allowing the $N$ to interact with the components of the cluster. Previous studies have determined the existence of three states of spin 0, 1, 2 for the $D^{*}{\overline{K}}^{*}$ system, the one of spin 0 associated to the $X_0(2900)$ state observed by the LHCb Collaboration. From this perspective, we find five states with total spin $1/2,3/2,5/2$, with bindings from 10 to 30 MeV and widths below 60 MeV, which could be well identified. We also discuss the decay channels of these states that should help in future experimental searches for these states.

In a recent paper [Phys. Rev. Lett. 126, 132001 (2021)], the LHCb data on the di-$J/\psi$ production in proton-proton collisions were analyzed in a coupled-channel framework based on double-vector-charmonium channels. This investigation identified a robust pole near the $J/\psi J/\psi$ threshold, tagged $X(6200)$, suggesting it as a new state. The present work extends that investigation by incorporating recent di-$J/\psi$ production data from the CMS and ATLAS Collaborations and performing a combined analysis of all three datasets. This study confirms the existence of the $X(6200)$, and its pole position is now determined with a higher precision than in the previous study, where only a single dataset was employed. The pole corresponding to the $X(6900)$ is also extracted, though its actual position and residue depend on a particular coupled-channel model employed and deviate from values reported in the experimental investigations. Moreover, we demonstrate that the currently available data do not allow one to determine whether there is an additional pole in the studied mass range. The dielectron width of the $X(6200)$ is estimated under different conjectures on its quantum numbers, and the number of such states that can be annually produced at the future Super $\tau$-Charm Facility is estimated. The line shape in the complimentary $J/\psi \psi (2S)$ channel is discussed, and a good agreement with the ATLAS data is found.

We use quantum chromodynamics (QCD) kinetic theory to compute dilepton production coming from the pre-equilibrium phase of the quark-gluon plasma created in high-energy heavy-ion collisions. We demonstrate that the dilepton spectrum exhibits a simple scaling in terms of the specific shear viscosity $\eta /s$ and entropy density $dS/d\zeta \sim {(T{\tau }^{1/3})}_{\infty }^{3/2}$, which can be derived from dimensional analysis in the presence of a pre-equilibrium attractor. Based on this scaling we perform event-by-event calculations of in-medium dilepton production and determine the invariant mass range where the pre-equilibrium yield is the leading contribution.

The PROSPECT-I detector has several features that enable measurement of the direction of a compact neutrino source. In this paper, a detailed report on the directional measurements made on electron antineutrinos emitted from the High Flux Isotope Reactor is presented. With an estimated true neutrino (reactor to detector) direction of $\varphi =40.8°\pm 0.7°$ and $\theta =98.6°\pm 0.4°$, the PROSPECT-I detector is able to reconstruct an average neutrino direction of $\varphi =39.4°\pm 2.9°$ and $\theta =97.6°\pm 1.6°$. This measurement is made with approximately 48 000 inverse beta decay signal events and is the most precise directional reconstruction of reactor antineutrinos to date.

We measure the branching fraction of the decay $B^0\to J/\psi \omega$ using data collected with the Belle II detector at the SuperKEKB collider. The data contain $(387\pm 6)\times {10}^{6}B\overline{B}$ meson pairs produced in energy-asymmetric $e^{+}{e}^{-}$ collisions at the $\mathrm{\Upsilon }(4S)$ resonance. The measured branching fraction $\mathcal{B}(B^0\to J/\psi \omega )=(2.16\pm 0.30\pm 0.14)\times {10}^{-5}$, where the first uncertainty is statistical and the second is systematic, is more precise than previous results and constitutes the first observation of the decay with a significance of 6.5 standard deviations.

The nonlinear nature of general relativity manifests prominently throughout the merger of two black holes from the inspiral phase to the final ringdown. Notably, the quasinormal modes generated during the ringdown phase display significant nonlinearities. We show that these nonlinear effects can be effectively captured by approaching the photon ring through the Penrose limit. Specifically, we model the quasinormal modes as null particles trapped in unstable circular orbits around the black holes and show that they can be interpreted as adiabatic modes, perturbations that are arbitrarily close to large diffeomorphisms. This enables the derivation of a simple analytical expression for the QNM nonlinearities for Schwarzschild and Kerr black holes which reproduces reasonably well the existing numerical results given the simplicity of the derivation.

Recently, it was shown that essentially all regular black hole models constructed so far can be obtained as solutions of vacuum gravity equations, upon considering an infinite series of quasitopological higher curvature corrections. Here, we show that such a construction can be upgraded to yield regular black holes with vanishing inner horizon surface gravity. In four dimensions, such a condition is necessary for the absence of classical instabilities associated with mass inflation on the inner horizon.

The nonlocal effects originating from the charm quark loops at dilepton invariant masses smaller than the charmonium threshold in $B\to K\ell \ell$ are evaluated with light-meson distribution amplitudes. The revised estimates with $B$-meson distribution amplitude within a light cone sum rule approach yielded results about three orders smaller than the original computation. In view of the importance of these nonfactorizable soft gluon effects, both conceptually and phenomenologically, an independent evaluation is necessary. It is found that to twist-4 accuracy, these soft gluon effects vanish when evaluated employing the kaon distribution amplitude. Similar results hold for $B\to K^{*}\ell \ell$ to the leading twist. This eliminates one of the major sources of potential uncertainty which usually makes it difficult for a clear case of new physics, should the data show deviations from the standard model.

We investigate the interplay between quantum theory and gravity by exploring gravitational lensing and Einstein ring images in a weak gravitational field induced by a mass source in spatial quantum superposition. We analyze a quantum massless scalar field propagating in two distinct models of gravity: the first quantized Newtonian gravity (QG) model, which generates quantum entanglement between the mass source and other systems, and the Schrödinger-Newton (SN) gravity model, which does not produce entanglement. Visualizing the two-point correlation function of the scalar field, we find that the QG model produces a composition of multiple Einstein rings, reflecting the spatial superposition of the mass source. By contrast, the SN model yields a single deformed ring image, representing a classical spacetime configuration. Furthermore, we introduce a specific quantity named the which-path information indicator and visualize its image. The QG model again reveals multiple Einstein rings, while the image intensity in the SN model notably vanishes. Our findings provide a visual approach to witness gravity-induced entanglement through distinct features in Einstein ring images. This study advances our understanding of quantum effects in general relativistic contexts and establishes a foundation for future studies of other relativistic phenomena.

We introduce a general class of toric gravitational instantons in $D=4$, $\mathcal{N}=2$ gauged supergravity, namely Euclidean supersymmetric solutions with $U(1{)}^2$ isometry. Such solutions are specified by a “supergravity labeled polytope,” where the labels encode the four-manifold topology, the choice of magnetic fluxes, and certain signs associated with the Killing spinor. Equivariant localization allows us to write down the gravitational free energy for such a solution, assuming it exists, and study its properties. These results open the way for a systematic study of holography in this setting, where the dual large $N$ field theories are defined on the boundary three-manifolds, which are (squashed) lens spaces $L(p,q)$ or generalizations with orbifold singularities.

We consider half-BPS Wilson loops in $\mathcal{N}=2$ long circular quiver gauge theories at large $N$ with continuous limit shape of ’t Hooft couplings. In the limit of an infinite number of nodes $L$, the solution to the localization matrix model is given by Wigner semicircles for any profile of couplings. Higher-order corrections in $1/L$ can be calculated iteratively. Combining large $L$ with a strong coupling regime, we identify a double scaling limit that describes dynamics along a fifth dimension, which emerges dynamically from the quiver diagram. We solve the resulting integro-differential equation exactly for a certain range of parameters.

A new set of twisted geometric variables is introduced to parametrize the holonomy-flux phase space in loop quantum gravity. It is verified that these new geometric variables, after symplectic reduction with respect to the Gauss constraint, form a Poisson algebra which is analogous to that in quantum mechanics. This property ensures that these new geometric variables provide a simple path measure, upon which a new formulation of coherent-state path integral based on twisted geometry coherent state is established in loop quantum gravity (LQG). Especially, this path integral is analytically computable by expanding the corresponding effective action around the complex evolution trajectories at second order, and the result gives the semiclassical approximation of the quantum propagator between twisted geometry coherent state in LQG.

We analyze the semiclassical Schwarzschild geometry in the Boulware quantum state in the framework of two-dimensional (2D) dilaton gravity. The classical model is defined by the spherical reduction of Einstein’s gravity sourced with conformal scalar fields. The expectation value of the stress-energy tensor in the Boulware state is singular at the classical horizon of the Schwarzschild spacetime, but when backreaction effects are considered, previous results have shown that the 2D geometry is horizonless and described by a nonsymmetric wormhole with a curvature singularity on the other side of the throat. In this work we show that reversing the sign of the central charge of the conformal matter removes the curvature singularity of the 2D backreacted geometry, which happens to be horizonless and asymptotically flat. This result is consistent with a similar analysis recently performed for the Callan-Giddings-Harvey-Strominger model. We also argue the physical significance of negative central charges in conformal anomalies from a four-dimensional perspective.

If two particles collide in the vicinity of a black hole horizon, their center of mass energy is practically unlimited, so another black hole with a large mass and thus entropy can be created. The resulting black hole can then merge with the original one. If the black hole is created very close to the horizon, its energy will be highly redshifted for an asymptotic observer. However, its entropy is not redshifted. We demonstrated that the newly created entropy can be higher than the Bekenstein-Hawking entropy of the final black hole, though we neglect that a certain amount of energy can escape to infinity, carrying away part of the entropy produced in the process. This is a counterexample to the statement that the black hole thermal entropy counts all the states inside the black hole. Unlike similar examples, this colliding process does not involve exotic matter, alternative theories of gravity, nor artificial ad hoc gluing of two different spacetimes.

We develop a perturbation theory for surfaces confining photons and massive particles in static spherically symmetric spacetimes in terms of two parameters: the mass-to-energy ratio and the deviation of metric functions from a given form, e.g., the Schwarzschild solution. Expansions of the gravitational shadow radius in terms of these parameters are constructed up to the second order. The metric expansion in terms of the Schwarzschild mass-to-radius ratio is then reconstructed. Explicit analytical examples of nonstandard black hole metrics are considered as an illustration. In some cases perturbative results demonstrate good accuracy even for nonsmall deviations.

Time-series data from observations of black-hole ringdown gravitational waves are often analyzed in the time domain by using damped sinusoid models with acyclic boundary conditions. Data conditioning operations, including downsampling, filtering, and the choice of data segment duration, reduce the computational cost of such analyses and can improve numerical stability. Here we analyze simulated damped sinsuoid signals to illustrate how data conditioning operations, if not carefully applied, can undesirably alter the analysis’s posterior distributions. We discuss how currently implemented downsampling and filtering methods, if applied too aggressively, can introduce systematic errors and skew tests of general relativity. These issues arise because current downsampling and filtering methods do not operate identically on the data and model. Alternative downsampling and filtering methods which operate identically on the data and model may be achievable, but we argue that the current operations can still be implemented safely. We also show that our preferred antialias filtering technique, which has an instantaneous frequency-domain response at its roll-off frequency, preserves the structure of posterior distributions better than other commonly used filters with transient frequency-domain responses. Lastly, we highlight that exceptionally long data segments may need to be analyzed in cases where thin lines in the noise power spectral density overlap with central signal frequencies. Our findings may be broadly applicable to any analysis of truncated time domain data with acyclic boundary conditions.

Tidal Love numbers quantify the conservative static response of compact objects to external tidal fields, and are found to vanish exactly for asymptotically flat black holes in four-dimensional general relativity. Many aspects of the physics of black holes have an analog in the theory of supersonic acoustic flows, including the existence of an event horizon and associated phenomena, such as quasinormal modes and superradiance. In this paper, we investigate the tidal Love numbers of acoustic black holes in different number of dimensions. We find that they exhibit a number of similar properties as higher-dimensional general relativistic black holes, such as logarithmic running with radial distance, and vanishing tidal response for special multipole moments. We show that the latter is a consequence of ladder symmetries, analogous to those identified for black holes.