The fate of the binary neutron star (NS) merger remnants hinges sensitively upon the NS equation of state and the threshold mass, $M_{\mathrm{ls}}$, that separates a long-lived from a short-lived NS remnant. The nature of the electromagnetic counterparts is also influenced by the remnant type, particularly in determining whether a gamma-ray burst from a compact binary merger (cbGRB) is of short or long duration. We propose a novel approach to probe $M_{\mathrm{ls}}$ by linking it to the estimated observed ratio of long to short cbGRBs. We find that current observations broadly favor a relatively high value for this transition, $M_{\mathrm{ls}}\simeq 1.3M_{\mathrm{TOV}}$, for which $M_{\mathrm{TOV}}\lesssim 2.6M_{\odot }$, consistent with numerical simulations, as also shown here. Our results disfavor nuclear physics scenarios that would lead to catastrophic pressure loss at a few times nuclear density and temperatures of tens of MeV, leading to a rapid gravitational collapse of binaries with total mass $M\lesssim 1.3M_{\mathrm{TOV}}$. Future individual gravitational wave events with on-axis cbGRBs can further bound $M_{\mathrm{ls}}$.

The response of the Moon to gravitational waves has previously been modeled using analytical or semianalytical models that assume ideal lunar structures. Such models are advantageous for their high-speed calculation but fail to account for the extremely heterogeneous subsurface and/or interior structures of the Moon. Numerical calculations are needed, but it is challenging to model the topography and lateral heterogeneity of the Moon. In addition, the computational cost is great, because gravitational wave modeling usually requires long-physical-time simulations. As a first step toward overcoming the above difficulties, we employ a two-dimensional high-order finite element method (the spectral element method) to numerically simulate the lunar response to gravitational waves. We verify our method by comparing our numerical results with those semianalytical solutions. Based on such comparison, we also analyze the limitation of the two-dimensional simulation. Our work breaks a new way toward the precise simulation of a realistic lunar response to gravitational waves in the future and lays down a solid foundation for three-dimensional numerical simulations.

Cosmological simulations of fuzzy dark matter (FDM) are computationally expensive, and the resulting halos lack flexibility in parameter adjustments, such as virial mass, density profile, and global velocity. Previous studies have introduced a method for constructing FDM halos with predefined density profiles. In this study, we investigate the initial global velocity of these constructed halos and find that it is nonzero. We provide the theoretical formula for this velocity and illustrate that it arises from the interference between states of odd and even parity. Our calculated results closely match simulation outcomes. Additionally, we showcase how to counteract this velocity and create a halo with a customizable initial global velocity. Our study presents a practical method for adjusting the initial global velocity of halos in controlled FDM simulations, facilitating investigations into tidal effects, galaxy collisions, and other scenarios.

Strong lensing of gravitational waves can produce several detectable images as repeated events in the upcoming observing runs, which can be detected with the posterior overlap analysis (Bayes factor). The choice of the binary black hole population plays an important role in the analysis as two gravitational-wave events could be similar either because of lensing or astrophysical coincidence. In this study, we investigate the biases induced by different population models on the Bayes factor. We build up a mock catalog of gravitational-wave events following a benchmark population and reconstruct it using both nonparametric and parametric methods. Using these reconstructions, we compute the Bayes factor for lensed pair events by utilizing both models and compare the results with a benchmark model. We show that the use of a nonparametric population model gives a smaller bias than parametric population models. Therefore, our study demonstrates the importance of choosing a sufficiently agnostic population model for strong lensing analyses.

Subparsec supermassive black hole (SMBH) binaries are expected to be common in active galactic nuclei as a result of the hierarchical buildup of galaxies via mergers. While direct evidence for these compact binaries is lacking, a few hundred candidates have been identified, most based on the apparent periodicities of their optical light curves. Since these signatures can be mimicked by active galactic nuclei red noise, additional evidence is needed to confirm their binary nature. Recurring self-lensing flares, occurring whenever the two BHs are aligned with the line of sight within their Einstein radii, have been suggested as additional binary signatures. Furthermore, in many cases, lensing flares are also predicted to contain a “dip,” whenever the lensed SMBH’s shadow is comparable in angular size to the binary’s Einstein radius. This feature would unambiguously confirm binaries and additionally identify SMBH shadows that are spatially unresolvable by high-resolution Very Long Baseline Interferometry (VLBI). Here we estimate the number of quasars for which these dips may be detectable by Legacy Survey of Space and Time (LSST) by extrapolating the quasar luminosity function to faint magnitudes and assuming that SMBH binaries are randomly oriented and have mass ratios following those in the Illustris simulations. Under plausible assumptions about quasar lifetimes, binary fractions, and Eddington ratios, we expect tens of thousands of detectable flares, of which several dozen contain measurable dips.

The laser of an intense electromagnetic field provides an important tool to study the strong-field particle physics. The nonlinear Compton scattering was observed in the collision of an ultrarelativistic electron beam with a laser pulse in the 1990s. The precision measurement of the nonlinear Compton scattering shines the light on the studies of strong-field quantum electrodynamics (QED) and nonlinear effects in QED. In this work, we propose to produce new massive particles through the nonlinear Compton scattering in the presence of a high intense laser field. We take dark photon or axionlike particle as illustrative new particle. Compared with other collider and beam dump experiments, the laser induced process provides a complementary and competitive search of new invisible particles lighter than 1 MeV.

We present a lattice calculation of the hadronic vacuum polarization (HVP) contribution of the strange and charm quarks to the anomalous magnetic moment of the muon in isospin symmetric QCD. We employ the gauge configurations generated by the Extended Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ flavors of Wilson-clover twisted-mass quarks at five lattice spacings and at values of the quark mass parameters that are close and/or include the isospin symmetric QCD point of interest. After computing the small corrections necessary to precisely match this point, and carrying out an extrapolation to the continuum limit based on the data at lattice spacings $a\simeq 0.049$, 0.057, 0.068, 0.080 fm and spatial lattice sizes up to $L\simeq 7.6\mathrm{fm}$, we obtain $a_{\mu }^{\mathrm{HVP}}(s)=(53.57\pm 0.63)\times {10}^{-10}$ and $a_{\mu }^{\mathrm{HVP}}(c)=(14.56\pm 0.13)\times {10}^{-10}$, for the quark-connected strange and charm contributions, respectively. Our findings agree well with the corresponding results by other lattice groups.

Dibaryons are the simplest system in which the baryon-baryon interaction, and hence the underlying quark-quark interaction, can be studied in a clear way. Although the only dibaryon known today is the deuteron (and possibly the $d^{*}$), fully heavy dibaryons are good candidates for bound states because in such systems the kinetic energy is small and the high symmetry of the wave function favors binding. In this study, the possible existence of ${\mathrm{\Omega }}_{ccc}{\mathrm{\Omega }}_{ccc}$ and ${\mathrm{\Omega }}_{bbb}{\mathrm{\Omega }}_{bbb}$ dibaryons is investigated in the framework of a constituent quark model that satisfactorily describes the deuteron, the $d^{*}(2380)$ and the $NN$ interaction. $J^P=0^{+}$ candidates are found in both systems with binding energies of the order of MeV. A $\mathrm{\Omega }$-dibaryon candidate is also found.

We propose a microscopic definition of finite cutoff JT quantum gravity on the disk, both in the discretized and in the continuum points of view. The discretized formulation involves a new model of so-called self-overlapping random polygons. The measure is not uniform, implying that the degrees of freedom are not in one-to-one correspondence with the shape of the boundary. The continuum formulation is based on a boundary ${\mathrm{CFT}}_1$ from which we predict some critical exponents of the self-overlapping polygon model. The coupling to an arbitrary bulk matter CFT is also discussed.

In this Letter we propose a new interpretation of the Casimir effect. Concretely, we show that the Casimir energy can be written as the quantum “Von Neumann” entropy associated to a 2-qubit, mixed pseudodensity matrix of the relevant quantum fluctuations. The quantum entropy we introduce draws parallels to the concept of quantum inseparability found in quantum information theory. Our results suggest that the Casimir energy is a measure of the quantum entropy of the vacuum fluctuations.

In this paper, we consider the time evolution of entanglement asymmetry of the black hole radiation in the Hayden-Preskill thought experiment. We assume the black hole is initially in a mixed state since it is entangled with the early radiation. Alice throws a diary maximally entangled with a reference system into the black hole. After the black hole has absorbed the diary, Bob tries to recover the information that Alice thought should be destroyed by the black hole. In this protocol, we found that a $U(1)$ symmetry of the radiation emerges before a certain transition time (the time when the vanishing entanglement asymmetry begins to grow). This emergent symmetry is exact in the thermodynamic limit and can be characterized by the vanishing entanglement asymmetry of the radiation. The transition time depends on the initial entropy and the size of the diary. What is more, when the initial state of the black hole is maximally mixed, this emergent symmetry survives during the whole procedure of the black hole radiation. We successfully explained this novel phenomenon using the decoupling inequality.

The effect of noise induced by gravitons on a Bose-Einstein condensate has been explored in Sen and Gangopadhyay [Probing the quantum nature of gravity using a Bose-Einstein condensate, Phys. Rev. D 110, 026014 (2024)]. In the previous paper, we investigated the effects of graviton while detecting a gravitational wave using a Bose-Einstein condensate. In this work, we shall explicitly calculate the decoherence due to the noise of gravitons for maximally entangled momentum states of the Bose-Einstein condensate. This decoherence happens due to bremsstrahlung from the Bose-Einstein condensates due to the effect of the noise induced by gravitons. It is observed that the maximally entangled state becomes entangled with the graviton state and it decays over time as a result of this gravitational bremsstrahlung. This new entangled state is termed as a Bose-Einstein supercondensate. Using this property of the Bose-Einstein condensate in a quantum gravity background, we propose an experimental test via the use of atom lasers (generated from the condensate) which would, in principle, help to detect gravitons in future generations of very advanced ultracold temperature experiments.

Gravity is derived from an entropic action coupling matter fields with geometry. The fundamental idea is to relate the metric of Lorentzian spacetime to a quantum operator, playing the role of an renormalizable effective density matrix and to describe the matter fields topologically, according to a Dirac-Kähler formalism, as the direct sum of a 0-form, a 1-form and a 2-form. While the geometry of spacetime is defined by its metric, the matter fields can be used to define an alternative metric, the metric induced by the matter fields, which geometrically describes the interplay between spacetime and matter. The proposed entropic action is the quantum relative entropy between the metric of spacetime and the metric induced by the matter fields. The modified Einstein equations obtained from this action reduce to the Einstein equations with zero cosmological constant in the regime of low coupling. By introducing the G-field, which acts as a set of Lagrangian multipliers, the proposed entropic action reduces to a dressed Einstein-Hilbert action with an emergent small and positive cosmological constant only dependent on the G-field. The obtained equations of modified gravity remain second order in the metric and in the G-field. A canonical quantization of this field theory could bring new insights into quantum gravity while further research might clarify the role that the G-field could have for dark matter.

We study the phenomena of neutrino oscillations and flavor mixing by incorporating the gravitational effects through the Dirac equation in curved spacetime inside a spherically symmetric star. We show that the flavor transition probabilities of the neutrinos depend on the interior spacetime metric as they propagate out of the star. As a consequence, we show that one could distinguish between different possible equation of states of nuclear matter even for an isolated neutron star if one could determine the flavor composition of emitted neutrinos near the stellar surface.

Probing quantumness in curved spacetime is regarded as one of the fundamental and important topics in the framework of relativistic quantum information. In this work, we focus on the theoretical feasibility of probing quantum properties in de Sitter (dS) and anti–de Sitter (AdS) spacetimes via detectors. By employing the Unruh-DeWitt detector coupled with a massless scalar field, which is treated as an open system, quantum uncertainty and quantum coherence in both dS and AdS spacetimes are investigated. Our analysis reveals that the acceleration in dS spacetime and the boundary conditions in AdS spacetime significantly impact the detector’s evolution in the initial stage. Notably, both of the uncertainty and coherence will oscillate with the initial state being in a superposition state, however the high temperature is able to suppress their oscillation. Interestingly, it is found that the constant values of the final uncertainty and coherence are identical as those in dS and AdS spacetimes, which are determined by the ratio of energy gap to temperature. Hence, the current exploration offers insight into quantumness in dS and AdS spacetimes, and might be helpful to facilitate the curved-spacetime-based quantum information processing.

We study the finite temperature and edge induced effects on the charge and current densities for a massive spinor field localized on a 2D conical space threaded by a magnetic flux. The field operator is constrained on a circular boundary, concentric with the cone apex, by the bag boundary condition and by the condition with the opposite sign in front of the term containing the normal to the edge. In two-dimensional spaces there exist two inequivalent representations of the Clifford algebra and the analysis is presented for both the fields realizing those representations. The circular boundary divides the conical space into two parts, referred as interior (I-) and exterior (E-) regions. The radial current density vanishes. The edge induced contributions in the expectation values of the charge and azimuthal current densities are explicitly separated in the both regions for the general case of the chemical potential. They are periodic functions of the magnetic flux and odd functions under the simultaneous change of the signs of magnetic flux and chemical potential. An important difference from the fermion condensate, considered previously in the literature, is that the mean charge and current densities are finite in the limit when the observation point tends to the boundary. In the E-region all the spinorial modes are regular and the total charge and current densities are continuous functions of the magnetic flux. In the I-region the corresponding expectation values are discontinuous at half-integer values of the ratio of the magnetic flux to the flux quantum. Those discontinuities come from the contribution of the irregular mode in the I-region. 2D fermionic models, symmetric under the parity and time-reversal transformations (in the absence of magnetic fields) combine two spinor fields realizing the inequivalent representations of the Clifford algebra. The total charge and current densities in those models are discussed for different combinations of the boundary conditions for separate fields. Applications are discussed for electronic subsystem in graphitic cones described by the 2D Dirac model.

A planar superfluid is considered and interpreted in terms of electromagnetism and gravity. It has previously been suggested that the superfluid flow can be regarded as analogous to an electromagnetic field and that a nonvanishing density gradient gives rise to a gravitylike force. The present work seeks to reconcile these hitherto distinct pictures into a unified exposition of vortex electrodynamics in a curved analog space-time. By constructing a theory in which the planar Maxwell’s equations are coupled to a ($d+1$)-dimensional conformally curved space-time, we expose a correspondence between the resulting equations and the dynamics of a planar quantum fluid. Finally, an effective vortex metric whose connection components are torsional is studied and its effect on the superfluid Maxwell’s equations is elucidated upon.

In the 1970s, Fulling, Davies, and Unruh demonstrated that the vacuum state perceived by an inertial observer in Minkowski space appears as a thermal bath to a uniformly accelerated observer. We explore the transformation of the Wigner distribution of a real scalar field from an inertial to a Rindler frame, utilizing both Minkowski and Unruh modes. We present a general expression for the reduced Wigner distribution for a specific set of massless scalar field configurations, and validate it against known distributions within this set. This includes arbitrary Gaussian states of Unruh-Minkowski modes, the Minkowski vacuum state, the Rindler vacuum, and the thermal bath of Unruh particles. Additionally, we analyze several other distributions, such as a peaked frequency distribution, a slight deviation from the Minkowski vacuum, and a distribution with a fermionic component in the Rindler frame. The conclusions are discussed.

We study the zero-dimensional prototype of the path integrals in quantum mechanics and quantum field theory, with the action $S(\varphi )=\frac{\sigma }{2}{\varphi }^2+\frac{\lambda }{4}{\varphi }^4$. Using the Lefschetz thimble decomposition and the saddle point expansion, we derive multiple asymptotic formal series of the correlation function associated with the perturbative and nonperturbative saddle points. Furthermore, we reconstruct the exact correlation function employing the Borel resummation. We then consider how to truncate the Dyson-Schwinger equations to compute two-point functions beginning with the perturbation expansion of the correlation functions, analogous to the one obtained from the Feynman diagram in higher dimensions. For the case $\sigma <0$, we find that, although the asymptotic series around the perturbative saddle point is Borel summable, it does not capture the full information. Consequently, contributions from nonperturbative saddle points must be included to ensure a complete truncation procedure.

The kinematic algebra of Yang-Mills theory can be understood in the framework of homotopy algebras: the $L_{\infty }$ algebra of Yang-Mills theory is the tensor product of the color Lie algebra and a kinematic space that carries a $C_{\infty }$ algebra. There are also hidden structures that generalize Batalin-Vilkovisky algebras, which explain color-kinematics duality and the double copy but are only partially understood. We show that there is a representation of the $C_{\infty }$ algebra, in terms of vertex operators, on the Hilbert space of a first-quantized worldline theory. To this end we introduce $A_{\infty }$ morphisms, which define the vertex operators and which inject the $C_{\infty }$ algebra into the strictly associative algebra of operators on the Hilbert space. We also take the first steps to represent the hidden structures on the same space.