In this work, we systematically calculate the mass spectra and decay widths of $\mathrm{\Omega }$ baryons with $N\le 3$, where $N=2n_{\rho }+2n_{\lambda }+l_{\rho }+l_{\lambda }$ is the shell of the three-body harmonic oscillator. In our scheme, the newly observed $\mathrm{\Omega }(2109)$ is identified as a $N=2$ candidate, with its quantum numbers tentatively assigned as $\mathrm{\Omega }(2S,3/2^{+})$. However, the experimentally measured mass exhibits a deviation of approximately 50 MeV below the theoretical predictions. The possible reason for this deviation, along with the suggestion for experiments, are discussed in this paper. Additionally, we give possible assignments of $\mathrm{\Omega }(2012{)}^{-}$, $\mathrm{\Omega }(2250{)}^{-}$, $\mathrm{\Omega }(2380{)}^{-}$, and $\mathrm{\Omega }(2470{)}^{-}$. Furthermore, we calculate the masses and widths of other missing $\mathrm{\Omega }$ states, which could provide valuable clues for experimental searches aimed at discovering these states.

Employing a unified Dyson-Schwinger/Bethe-Salpeter equations approach, we calculate the strong decay couplings $D^{*}D\pi$ and $B^{*}B\pi$ within the so-called impulse-approximation in the moving frame. The $B^{*}B\pi$ estimation is reported for the first time based on a Poincaré invariant computation of the associated Bethe-Salpeter amplitudes. Our predictions yield $g_{D^{*}D\pi }=16.22_{-0.01}^{+0.03}$ and $g_{B^{*}B\pi }=40.09_{-1.37}^{+1.51}$, along with corresponding static strong couplings of ${\widehat{g}}_D=0.55_{-<0.01}^{+<0.01}$, ${\widehat{g}}_B=0.50_{-0.02}^{+0.02}$, which are consistent with recent experimental and lattice data.

We have investigated the ${\mathrm{\Lambda }}_c^{+}\to n{\pi }^{+}{\pi }^0$ decay process using the chiral unitary approach, by considering that the nucleon resonance $N(1535)$ could be dynamically generated through $S$-wave pseudoscalar meson-octet baryon interactions. In the invariant mass distributions of ${\pi }^{0}n$ and ${\pi }^{+}n$, we observe a distinct peak structure associated with the resonance states $N(1535{)}^0$ and $N(1535{)}^{+}$, respectively. Our results suggest that the ${\mathrm{\Lambda }}_c^{+}\to n{\pi }^{+}{\pi }^0$ process can be utilized to probe the properties of the nucleon $N(1535)$. Therefore, we encourage more precise experimental measurements of this process in the future.

The thermal view of scalar-tensor gravity is an analogy with a dissipative fluid. The scalar degree of freedom excites gravity to a positive “temperature,” while Einstein gravity is the “zero-temperature” equilibrium state. We extend this thermal analogy to the interior region near the singularity of spherical, vacuum, uncharged black holes by using the universality of the Kasner behavior near spacelike singularities. The singularity is “hot,” meaning that gravity diverges from general relativity. The discussion is then extended to black holes in the presence of perfect or imperfect fluids with constant equation of state—the latter determines whether Einstein gravity is approached or not.

We explore entanglement harvesting using two Unruh-DeWitt (UDW) detectors linearly coupled to the scalar density of a massless spin-$1/2$ field in $1+1$ Schwarzschild spacetime. We consider different vacua, including the Boulware, Hartle-Hawking-Israel (HHI), and Unruh vacua, and investigate various configurations of detector trajectories. We find that the transition rate of the static UDW detector exhibits the expected Planckian behavior in the HHI state, while the Unruh state leads to the Helmholtz free energy density of a fermionic thermal bath. We demonstrate that the near-horizon entanglement properties for static detectors in the HHI state have similar behavior to those in Minkowski vacua for uniformly accelerated detectors in Rindler spacetime. We further consider a different interaction Hamiltonian which breaks local Lorentz symmetry and find that the transition rate of the static detector still exhibits Planckian behavior in the HHI state, while in the Unruh state, it leads to the Helmholtz free energy density of a bosonic or fermionic thermal bath corresponding to the static or conformal 2-bein in interaction, respectively. We observe that the anti-Hawking effect enhances the entanglement between the two detectors while the gravitational redshift and Hawking radiation decrease it. In particular, due to the presence of the anti-Hawking effect, the mutual information and concurrence near the event horizon can be non-zero even for static detectors with static 2-bein, which is in contrast with the case of the scalar field. Conclusions are discussed.

Highly precise and robust waveform models are required as improvements in detector sensitivity enable us to test general relativity with more precision than ever before. In this work, we introduce a spin-aligned surrogate ringdown model. This ringdown surrogate, nrsur3dq8_rd, is built with numerical waveforms produced using Cauchy-characteristic evolution. In addition, these waveforms are in the super-rest frame of the remnant black hole allowing us to do a correct analysis of the ringdown spectrum. The novel prediction of our surrogate model is complex-valued quasinormal mode (QNM) amplitudes, with median relative errors of ${10}^{-2}-{10}^{-3}$ over the parameter space. Like previous remnant surrogates, we also predict the remnant black hole’s mass and spin. The QNM mode amplitude errors translate into median errors on ringdown waveforms of $\sim {10}^{-4}$. The high accuracy and QNM mode content provided by our surrogate will enable high-precision ringdown analyses such as tests of general relativity. Our ringdown model is publicly available through the python package surfinbh.

The phasing for compact binary systems on circular orbits was obtained in [Phys. Rev. Lett. 131, 121402 (2023)] at fourth-and-a-half post-Newtonian (4.5PN) order thanks to two main ingredients: the 4PN conservative energy (associated to a nonradiative spacetime) in terms of the orbital frequency and the 4.5PN flux in terms of the waveform frequency [i.e., the half-frequency of the $(\ell ,m)=(2,2)$ mode]. When obtaining the phasing, a key physical postulate was made: the expression of the binding energy in terms of the waveform frequency was assumed to be identical to the expression of the conservative energy in terms of the orbital frequency. This postulate was necessary to ensure that the frequency evolution obtained through the flux-balance law (which involves the binding energy) was independent of the choice of spacetime foliation. In this work, I show that the binding energy entering the flux-balance law differs from the 4PN conservative energy by a 4PN pseudo-Schott term, associated with radiation-reaction effects due to gravitational tails. Unlike the usual Schott terms (at 2.5PN, 3.5PN, and 4.5PN), the pseudo-Schott term is not a total derivative and is in fact hereditary, so it does not vanish for circular orbits. Remarkably, the binding energy thus obtained is in perfect agreement with the one obtained using the aforementioned physical postulate, which confirms that the 4.5PN phasing associated to the waveform frequency computed in [Phys. Rev. Lett. 131, 121402 (2023)] is indeed correct. This result is extended to the other Poincaré invariants, and “thermodynamic” relations between the binding energy and angular momentum are established. Finally, the chirp and phasing associated to the orbital frequency are presented at 4.5PN, including horizon-absorption effects.

We present an exact analytical investigation of spin precession for a test gyroscope in the magnetized Kerr spacetime—an exact electrovacuum solution to the Einstein-Maxwell equations. Our approach accommodates arbitrary magnetic field strengths, enabling a unified treatment across both weak and ultrastrong field regimes. The analysis reveals distinct spin precession behaviors near rotating collapsed objects, which differ characteristically between black holes and naked singularities, offering a potential observational means to differentiate them. The external magnetic field induces a nontrivial modification of the precession frequency through its interaction with the spacetime’s gravitoelectromagnetic structure. In the weak-field limit, magnetic fields generally reduce the precession rate, though the effect depends sensitively on the motion and orientation of the test gyro close to the collapsed object. As a special case, we show that in the presence of magnetic fields, the spin precession frequency due to gravitomagnetic effect acquires a long-range $1/r$ (where $r$ is the distance from the central object to the test gyro) correction in contrast to the standard $1/r^3$ falloff. In addition, we obtain the exact geodetic precession (gravitoelectric effect) frequency for a gyroscope in magnetized Schwarzschild spacetime, showing that the magnetic field enhances ($\propto r^{1/2}$) geodetic precession in contrast to the standard $1/r^{5/2}$ falloff. Our results provide observationally testable predictions relevant for black holes in strong magnetic environments, including those possibly realized near magnetars or in the early universe. In particular, the strong-field behavior of spin precession could have important implications for transmuted black holes formed via collapse or mergers of magnetized progenitors in both astrophysical and cosmological contexts.

Rotating black holes can amplify ultralight bosonic fields through superradiance, forming macroscopic clouds known as gravitational atoms. When the cloud forms around one of the components of a binary system, it can undergo a series of distinctive interactions, comprising both secular effects, such as dynamical friction or accretion, and resonant behavior. These processes are expected to leave a distinctive signature on the gravitational waveform emitted by the binary, whose detectability we investigate in this paper. To do so, we implement a numerical code that integrates these effects, computed within a Newtonian approximation, for small-to-intermediate mass-ratio binaries on circular equatorial orbits. Realistic waveforms incorporating these environmental influences are generated and analyzed using the Fisher-matrix formalism to evaluate the detectability of bosonic clouds with current and next-generation ground-based gravitational-wave observatories. Our results demonstrate the potential for gravitational-wave astronomy to probe the existence and properties of ultralight bosons.

Einstein-aether theory provides a model to test the validity of local Lorentz invariance in gravitational interactions. The speed of gravitational waves as measured from the binary neutron star event GW170817 sets stringent limits on Einstein-aether theory, but only on a combination of the theory’s free parameters. For this reason, a significant part of the theory’s parameter space remains unconstrained by observations. Motivated by this, we explore the propagation of gravitational waves in Einstein-aether theory over an inhomogeneous background (i.e., gravitational wave lensing) as a potential mechanism to break the degeneracies between the theory’s free parameters, and hence enable new constraints on the theory to be obtained. We reduce our analysis to gravitational waves that pass far from the lens’ center and short wavelength signals, both compared to the lens’ gravitational radius (eikonal limit). By applying these approximations and bringing the field equations into the form of the so-called kinetic matrix and applying a formalism known as the propagation eigenstate framework, we find that the speed of gravitational waves is modified by inhomogeneities in the aether field. However, the modification is common to both gravitational polarizations and vanishes in the limit in which gravitational waves propagate with luminal speed. This lens-dependent gravitational wave speed contrasts with the lens-induced birefringence observed in other theories beyond general relativity, like Horndeski’s theory. While the potential to improve tests based on gravitational-wave speed is limited, our formalism sets the basis to fully describe signal propagation over inhomogeneous spacetimes in Einstein-aether theory and other extensions of general relativity.

We investigate strong gravitational lensing by a marginally unstable photon sphere in a Reissner-Nordström naked singularity spacetime. Using the Picard-Fuchs equation, we derive full-order power series expressions for the deflection angle in various regimes, including the strong deflection limits from both outside and inside the photon sphere. We show that the deflection angle diverges nonlogarithmically in both cases, refining existing asymptotic formulas. Comparing truncated approximations with numerical results, we find that higher-order corrections are essential to achieve comparable accuracy to logarithmic divergence cases. Using these improved formulas, we also derive precise approximations for image positions that are not restricted to the almost perfectly aligned cases.

Gravitational wave data are often contaminated by non-Gaussian noise transients, “glitches,” which can bias the inference of astrophysical signal parameters. Traditional approaches either subtract glitches in a preprocessing step, or a glitch model can be included from an agnostic wavelet basis (e.g., BayesWave). In this work, we introduce a machine-learning-based approach to build a parametrized model of glitches. We train a normalizing flow on known glitches from the Gravity Spy catalog, constructing an informative prior on the glitch model. By incorporating this model into the Bayesian inference analysis with bilby, we estimate glitch and signal parameters simultaneously. We demonstrate the performance of our method through bias reduction, glitch identification, and Bayesian model selection on real glitches. Our results show that this approach effectively removes glitches from the data, significantly improving source parameter estimation and reducing bias.

With ongoing advancements in nuclear theory and experimentation, together with a growing body of neutron star (NS) observations, a wealth of information on the equation of state (EOS) for matter at extreme densities has become accessible. Here, we utilize a hybrid EOS formulation that combines an empirical parametrization centered around the nuclear saturation density with a generic three-segment piecewise polytrope model at higher densities. We incorporate data derived from chiral effective field theory ($\chi \mathrm{EFT}$), perturbative quantum chromodynamics (pQCD), and experiments such as PREX-II and CREX. Furthermore, we examine the influence of a total of 70 NS mass measurements up to April 2023, as well as simultaneous mass and radius measurements derived from the x-ray emission from surface hot spots on NSs. Additionally, we consider constraints on tidal properties inferred from the gravitational waves emitted by coalescing NS binaries. To integrate this extensive and varied array of constraints, we utilize a hierarchical Bayesian statistical framework to simultaneously deduce the EOS and the distribution of NS masses. We find that incorporating data from $\chi \mathrm{EFT}$ significantly tightens the constraints on the EOS of NSs near or below the nuclear saturation density. However, constraints derived from pQCD computations and nuclear experiments such as PREX-II and CREX have minimal impact. Taking into account all available data, we derive estimates for key parameters characterizing the EOS of dense nuclear matter. Specifically, we determine the slope ($L$) and curvature ($K_{\mathrm{sym}}$) of the symmetry energy to be ${54}_{-10}^{+10}$ and $-158_{-63}^{+73}\mathrm{MeV}$ with 90% credibility, respectively. Additionally, we infer the radius and tidal deformability of an NS with a mass of 1.4 solar masses ($M_{\odot }$) to be ${12.34}_{-0.53}^{+0.43}\mathrm{km}$ and ${436}_{-117}^{+109}$, respectively. Furthermore, we estimate the maximum mass of a nonrotating NS to be ${2.22}_{-0.19}^{+0.21}{M}_{\odot }$ with 90% credibility.

In this paper, a simulation environment for a Hartmann wavefront sensor is presented and discussed in the context of a gravitational wave detectors. Thermal effects occur in the optics of the gravitational wave detector and precise measurements is crucial. Hartmann wavefront sensors have been used for this purpose but need to be configured individually. In this work, an optical simulation is implemented to test different Hartmann wavefront sensor configurations. A figure of merit is developed allowing to quantize the wavefront sensor performance. Theoretical evaluations allow to define parameter sets of common measurement range and to fairly compare them across the parameter space. Core parameters are the number of apertures, aperture diameter, and the Hartmann-plate-to-camera distance. The approach is demonstrated based on a thermal deformation estimate with a measurement range represented by a maximum displacement angle of ${\alpha }_{\max }=4\mathrm{mrad}$. A parameter set including sixty-one apertures is derived allowing best resolution of $\mathrm{res}=3\mathrm{pm}$ for ten-fold averaging. This work can be used to find parameters for an optimal Hartmann wavefront sensor for a third-generation gravitational wave detector such as the Einstein Telescope once the thermal deformation due to the coating and the material of the gravitational wave detector test masses is known.

We use a worldline-instanton formalism to study the momentum spectrum of Schwinger pair production in spacetime fields with multiple stationary points. We show that the interference structure changes fundamentally when going from purely time-dependent to space-time-dependent fields. For example, it was known that two time-dependent pulses give interference if they are antiparallel, i.e., $E_z(t)-E_z(t-\mathrm{\Delta }t)$, but here we show that two spacetime pulses will typically give interference if they instead are parallel, i.e., $E_z(t,z)+E_z(t-\mathrm{\Delta }t,z-\mathrm{\Delta }z)$. We take into account the fact that the momenta of the electron, $p_z$, and of the positron, $p_z^{\prime }$, are independent for $E_z(t,z)$ [it would be $p_z+p_z^{\prime }=0$ for $E(t)$], and find a type of fields which give moiré patterns in the $p_z-p_z^{\prime }$ plane. Depending on the separation of the two pulses, we also find an Aharonov-Bohm phase. We also study complex momentum saddle points in order to obtain the integrated probability from the spectrum. Finally, we calculate an asymptotic expansion for the eigenvalues of the Sturm-Liouville equation that corresponds to the saddle-point approximation of the worldline path integral, use that expansion to compute the product of the eigenvalues, and compare this with the result obtained with the Gelfand-Yaglom method.

Gauge-field configurations with nontrivial topology have profound consequences for the physics of Abelian and non-Abelian gauge theories. Over time, arguments have been gathering for the existence of gauge-field configurations with fractional topological charge, called fractons. Ground-state properties of gauge theories can drastically change in presence of fractons in the path integral. However, understanding the origin of such fractons is usually restricted to semiclassical argumentation. Here, we show that fractons persist in strongly correlated many-body systems, using the multiflavor Schwinger model of quantum electrodynamics as a paradigm example. Through detailed numerical tensor-network analysis, we find strong fracton signatures even in highly discretized lattice models, at sizes that are implementable on already existing quantum-simulation devices. Our work sheds light on how the nontrivial topology of gauge theories persists in challenging nonperturbative regimes, and it shows a path forward to probing it in tabletop experiments.

The Belle II experiment has recently reported the first measurement of $B^{+}\to K^{+}\nu \overline{\nu }$ decay which exceeds the Standard Model prediction by approximately $2.7\sigma$. The deviation may indicate the presence of new physics beyond the Standard Model in the $b\to s\nu \overline{\nu }$ sector. Under this assumption, we study the hadronic ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(\to p\pi )\nu \overline{\nu }$ and ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}^{*}(\to N\overline{K})\nu \overline{\nu }$ decays within both the Standard Model and beyond. We work in a low-energy effective field theory framework with additional light right-handed neutrinos. We calculate the differential branching ratios of these decay modes and explore the implications of the Belle II results through various observables.

Electron-capture decays of ${}^{125}\mathrm{Xe}$ and ${}^{127}\mathrm{Xe}$, and double-electron-capture decays of ${}^{124}\mathrm{Xe}$, are backgrounds in searches for weakly interacting massive particles (WIMPs) conducted by dual-phase xenon time projection chambers such as LUX-ZEPLIN (LZ). These decays produce signals with more light and less charge than equivalent-energy $\beta$ decays and correspondingly overlap more with WIMP signals. We measure three electron-capture charge yields in LZ: the 1.1 keV M-shell, 5.2 keV L-shell, and 33.2 keV K-shell at drift fields of 193 and $96.5\mathrm{V}/\mathrm{cm}$. The LL double-electron-capture decay of ${}^{124}\mathrm{Xe}$ exhibits even more pronounced shifts in charge and light. We provide a first model of double-electron-capture charge yields using the link between ionization density and electron-ion recombination, and identify a need for more accurate calculations. Finally, we discuss the implications of the reduced charge yield of these decays and other interactions creating inner-shell vacancies for future dark matter searches.

The dynamics of superfluid systems exhibit significant similarities to their classical counterparts, particularly in the phenomenon of vortex shedding triggered by a moving obstacle. In such systems, the universal behavior of shedding patterns can be classified using the classical concept of the Reynolds number $\mathrm{Re}=\frac{v\sigma }{\nu }$ (characteristic length scale $\sigma$, velocity $v$, and viscosity $\nu$), which has been shown to generalize to quantum systems at absolute zero temperature. However, it remains unclear whether this universal behavior holds at finite temperatures, where viscosity arises from two distinct sources: thermal excitations and quantum vortex viscosity. Using a holographic model of finite-temperature superfluids, we investigate the vortex shedding patterns and identify two distinct regimes without classical counterparts: a periodic vortex dipole pattern and a vortex dipole train pattern. By calculating the shedding frequency, Reynolds number, and Strouhal number at different temperatures, we find that the relations between these quantities are qualitatively similar to empirical observations that are extracted from both classical and quantum vortex shedding systems, which implies the robustness of vortex shedding dynamics at finite-temperature superfluid systems.

In this paper, we aim to study the quantum transition between a Schwarzschild black hole and a string black hole in the large $D$ limit. Classically, such a transition between these two distinct black hole geometries is forbidden. The only feasible discussion is centered on how a black hole evaporates, loses mass, and transitions into highly excited fundamental strings. Building upon our previous work on T-duality between the Schwarzschild and string black holes, we reduce the problem to two dimensions, where the corresponding Wheeler–de Witt equation can be derived. Using this equation, we identify the two black hole geometries as distinct wave function states. This allows us to easily compute the transition probability between these two geometries, driven by the string coupling.