We examine the permanent damage caused by the historical breakdown of full diffeomorphism invariance induced by a foliation. We focus on the case where the foliation is allowed to be nongeodesic after the interactions with the foliation switch off. Gravity and other forms of matter recover full diffeomorphism invariance only at the expense of introducing a new matterlike component, carrying the nonvanishing Hamiltonian (and momentum, as it turns out) left over from the violating past interactions. This matter form must be stress-free in the preferred frame; this is the only way a matter action can mimic the evolution of the leftover Hamiltonian (and momentum) driven by the Dirac hypersurface deformation algebra. Hence, if the preferred frame is nongeodesic, the equivalent matter component must have energy and a momentum current in this frame, but still no spatial stresses: an unusual form of “matter.” It is equivalent to a fluid with anisotropic stress in some regimes, reducing to dust in others, or even displaying completely new features in extreme situations. Its stress energy tensor is conserved. We provide two examples based on accelerated frames: Rindler space-time and the canonical Schwarzchild frame.

Field equations of a classical, geometric, theory of gravity, augmented with some semiclassical considerations strongly suggest that the gravitational field representing a stationary black hole can be simply described with a few thermodynamical coordinates and their conjugates that obey the four laws of thermodynamics plus the Smarr formula and the reverse isoperimetric inequality that bounds the maximum entropy for a given effective volume of space. The thermodynamics of black holes is a promising window to the quantum nature of black holes; hence, it is important to understand all the details of these laws. The identification and the meaning of these thermodynamic coordinates depend on the gravity theory under consideration. For example, the existence of dimensionful coupling constants, such as the cosmological constant, changes the scaling properties of the theory, its solutions, and the laws of thermodynamics. Here we show, using the background Killing charge method, which applies to the black hole solutions of any gravity theory that has a maximally symmetric vacuum, to define the mass and angular momentum, instead of using the Komar mass and the angular momentum, how the thermodynamics of black holes such as the $D$ dimensional Kerr-AdS black holes in cosmological Einstein’s theory and the spherically symmetric black holes in the Einstein-Gauss-Bonnet theory changes. We give the effective volume of black holes even without a cosmological constant.

Studying the dynamical, nonlinear regime of modified theories of gravity remains a theoretical challenge that limits our ability to test general relativity. Here we consider two generally applicable, but approximate, methods for treating modifications to full general relativity that have been used to study binary black hole mergers and other phenomena in this regime, and compare solutions obtained by them to those from solving the full equations of motion. The first method evolves corrections to general relativity order by order in a perturbative expansion, while the second method introduces extra dynamical fields in such a way that strong hyperbolicity is recovered. We use shift-symmetric Einstein-scalar-Gauss-Bonnet gravity as a benchmark theory to illustrate the differences between these methods for several spacetimes of physical interest. We study the formation of scalar hair about initially nonspinning black holes, the collision of black holes with scalar charge, and the inspiral and merger of binary black holes. By directly comparing predictions, we assess the extent to which those from the approximate treatments can be meaningfully confronted with gravitational wave observations. We find that the order-by-order approach cannot faithfully track the solutions when the corrections to general relativity are non-negligible. The second approach, however, can provide consistent solutions, provided the ad hoc timescale over which the dynamical fields are driven to their target values is made short compared to the physical timescales.

We introduce the general-relativistic definition of lunar coordinate time (TCL) based on the International Astronomical Union 2000 resolutions that provide a framework for relativistic reference systems. From this foundation, we derive a transformation equation that describes the relative rate of TCL with respect to geocentric coordinate time (TCG) for various locations of a clock on the lunar surface. This equation serves as the cornerstone for constructing a relativistic TCL-TCG time conversion algorithm. Using this algorithm, we can compute both secular and periodic variations in the rate of an atomic clock placed on the Moon, relative to an identical clock on the Earth. The algorithm accounts for various effects, including time dilation caused by the Moon’s orbital motion around Earth, gravitational potentials of both Earth and Moon, and direct and indirect time dilation effects due to tidal perturbations caused by the Sun and other major planets of the Solar System. Our approach provides exquisite details of the TCL-TCG transformation, achieving a precision of several nanoseconds within the spatial volume dominated by the Earth’s gravitational field known as the Hill sphere. This sphere extends from the Earth to a distance of approximately $1.5\times {10}^6\mathrm{km}$, substantially encompassing the Moon’s orbit. To validate our methodology for lunar coordinate time, we compare it with the mathematical formalism of local inertial frames applied to the Earth-Moon system, and confirm their equivalence.

Binary neutron star mergers are among the most energetic events in our Universe, with magnetic fields significantly impacting their dynamics, particularly after the merger. While numerical-relativity simulations that correctly describe the physics are essential to model their rich phenomenology, the inclusion of magnetic fields is crucial for realistic simulations. For this reason, we have extended the bam code to enable general relativistic magnetohydrodynamic (GRMHD) simulations employing a hyperbolic “divergence cleaning” scheme. We present a large set of standard GRMHD tests and compare the bam code to other GRMHD codes, spritz, gram-x, and ${\mathrm{SACRA}}_{\mathrm{KK}22}$, which employ different schemes for the evolution of the magnetic fields. Overall, we find that the bam code shows good performance in simple special-relativistic tests. In addition, we find good agreement and consistent results when comparing GRMHD simulation results between bam and ${\mathrm{SACRA}}_{\mathrm{KK}22}$.

We analyze time-dependent dark energy equations of state through linear and nonlinear structure formation and their quintessence potentials, characterized by fast, recent transitions, inspired by parameter space studies of selected classes of the more general Horndeski models. The influence of dark energy on structures comes from modifications to the background expansion rate and from perturbations as well. In order to compute the structures growth, we employ a generalization of the spherical collapse formalism that includes perturbations of fluids with pressure. We numerically solve the equations of motion for the perturbations and the field. Our analysis suggests that a true Heaviside step transition is a good approximation for most of the considered models, since most of the quantities weakly depend on the transition speed. We find that transitions occurring at redshifts $z_{\mathrm{t}}\gtrsim 2$ cannot be distinguished from the $\mathrm{\Lambda }\mathrm{CDM}$ model if dark energy is freezing, i.e., the corresponding equation of state tends to $-1$. For fast, recent transitions, the redshift at which the properties of dark energy have the most significant effect is $z=0.6\pm 0.2$. We also find that in the freezing regime, the ${\sigma }_8$ values can be lowered by about 8%, suggesting that those models could relieve the ${\sigma }_8$-tension. Additionally, freezing models generally predict faster late-time merging rates but a lower number of massive galaxies at $z=0$. Finally, the nonlinear matter power spectrum for smooth dark energy shows a valley centered in $k\approx 1h{\mathrm{Mpc}}^{-1}$ which in the clustering case is replaced by a sharp increase for $k\gtrsim 0.2h{\mathrm{Mpc}}^{-1}$ and a peak at $k\approx 2h{\mathrm{Mpc}}^{-1}$.

Gravitational waves (GWs) hold great potential for an unobscured view of protoneutron stars (PNSs) formed as a result of stellar collapses. While waiting for discovery, deepening the understanding of GW emission in theory is beneficial for both optimizing searching strategies and deciphering the eventual data. One significant aspect is the spatially dependent contribution to the overall GW signal extracted from sophisticated hydrodynamic simulations. I present the proper way to perform the spatial decomposition of GW strain with the quadrupole formula in the slow-motion and weak-field approximation. Then I demonstrate the approach using the results of a 2D axisymmetric pseudo-Newtonian hydrodynamic simulation of core-collapse supernova. I show a detailed comparison between the proper and improper methods and discuss the possible consequences based on the improper method. Moreover, with the correct approach, the GW spatial profiles agree well with those calculated from a consistent perturbative method.

The gravitational waves emitted by binary neutron star inspirals contain information on nuclear matter above saturation density. However, extracting this information and conducting parameter estimation remains a computationally challenging and expensive task. Wong et al. introduced jim [Astrophys. J. 958, 129 (2023)], a parameter estimation pipeline that combines relative binning and jax features such as hardware acceleration and automatic differentiation into a normalizing flow-enhanced sampler for gravitational waves from binary black hole mergers. In this work, we extend the jim framework to analyze gravitational wave signals from binary neutron star (BNS) mergers with tidal effects included. We demonstrate that jim can be used for full Bayesian parameter estimation of gravitational waves from BNS mergers within a few tens of minutes, which includes the training of the normalizing flow and computing the reference parameters for relative binning. For instance, jim can analyze GW170817 in 20 min (31 min) of total wall time using the TaylorF2 (IMRPhenomD_NRTidalv2) waveform, and GW190425 in around 21 min (25 min). We highlight the importance of such an efficient parameter estimation pipeline for several science cases as well as its ecologically friendly implementation of gravitational wave parameter estimation.

Cooling down test masses to cryogenic temperatures is a way to reduce the thermal noise of gravitational wave detectors. Crystalline materials are considered the most promising materials for fabricating cryogenic test masses and their coatings because of their excellent thermal and optical properties at low temperatures. However, birefringence owing to local impurities and inhomogeneities in the crystal can degrade the performance of the detector. The birefringence measurement or mapping over a two-dimensional area is thus important. This study describes a method for fast birefringence measurements of a large sample by simply combining a series of transmission wavefront error measurements using linearly polarized light with Fizeau interferometers. Using this method, the birefringence inhomogeneity information of KAGRA’s two input test masses with a diameter of 22 cm was fully reconstructed. The birefringence information was then used to calculate the transverse beam shapes of the light fields in orthogonal polarization directions when passing through the substrate. It was possible to find a calculated beam shape consistent with in situ measurements using the KAGRA interferometer. This technique is crucial for birefringence characterization of test masses in future detectors, where even larger sizes are used.

We find the general structure for the two-gluon one-photon vertex in the presence of a constant magnetic field. We show that, when accounting for the symmetries satisfied by the strong and electromagnetic interactions under parity, charge conjugation and gluon interchange, and for gluons and photons on mass-shell, there exist only three possible tensor structures that span the vertex. These correspond to external products of the polarization vectors for each of the particles in the vertex. We also explicitly compute the one-loop approximation to this vertex in the intermediate field strength regime, which is the most appropriate one to describe possible effects of the presence of a magnetic field to enhance photon emission during preequilibrium in peripheral relativistic heavy-ion collisions. We show that the most favored direction for the photon to propagate is in the plane transverse to the field, which is consistent with a positive contribution to ${\nu }_2$ and may help to understand the larger than expected elliptic flow coefficient measured in this kind of reaction.

Energy levels of hydrogen are calculated as one-loop matrix elements of the QED energy-momentum tensor trace in the external field approximation. An explicit connection established between the one-loop trace diagrams and the standard Lamb shift one-loop diagrams. Our calculations provide an argument against inclusion of the anomalous trace contribution as a separate term in the decomposition of the QED quantum field Hamiltonian and serve as an illustration how the trace anomaly is realized in the bound state QED.

We propose two models based on the $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ gauge symmetry, each incorporating distinct inverse seesaw mechanisms for generating neutrino masses at the radiative level. Therefore, neutrino masses are suppressed by the radiative nature of the mass generation mechanism, which occurs after the spontaneous breaking of the global lepton number symmetry. Both scenarios discussed here are characterized by the presence of vectorlike charged leptons, which are involved in generating the masses of the Standard Model charged leptons. These additional vectorlike fermions also contribute to the anomalous magnetic moments of the muon. We perform a detailed analysis of the scalar sectors, show that these models can successfully accommodate the observed baryon asymmetry through resonant leptogenesis, and compute the rates of charged lepton flavor-violating decays, such as $\mu \to e\gamma$. We discuss the constraints of the model arising from these processes and those associated with the nonunitarity of the lepton mixing matrix.

Drawing on recent advances in lattice QCD background-field techniques, the magnetic polarizability of octet baryons is calculated from the first principles of QCD. The results are presented in the context of new constituent quark model calculations providing a framework for understanding the lattice results and a direct comparison with simulation results at unphysical quark masses. Using smeared quark sources, low-lying Laplacian eigenmode projection and final-state Landau-mode projection, considerable attention is devoted to ensuring single-state isolation in the lattice correlation functions. We also introduce new weighting methods to reduce the sensitivity to correlation-function fits, averaging over many fits based on merit drawn from the full correlated ${\chi }^2$ of the fits. The techniques are implemented on the ${32}^3\times 64$, $2+1$-flavor dynamical-fermion lattices provided by the PACS-CS Collaboration following the introduction of uniform magnetic fields quantized to the lowest nontrivial values available. After some scaling of the constituent quark model parameters, we find the model captures the patterns observed in the lattice QCD results very well, providing important insights into the physics underpinning the magnetic polarizabilities. Finally, comparison with the most recent results from experiment proceeds through an effective field theory formalism which incorporates estimates of finite-volume corrections and small electroquenching corrections as the results are brought to the physical point. We find excellent agreement with experiment where available, including the proton and neutron polarizabilities.

The $I=2$ $\pi \pi$ elastic $s$-wave scattering phase shift is measured by lattice quantum chromodynamics with $N_f=3$ flavors of the Asqtad-improved staggered fermions. The lattice-calculated energy-eigenvalues of $\pi \pi$ systems at one center of mass frame and some moving frames using the moving wall source technique are utilized to secure phase shifts by Lüscher’s formula. Our computations are fine enough to obtain threshold parameters: scattering length $a$, effective range $r$, and shape parameter $P$, which can be extrapolated at the physical point by next-to-leading order in chiral perturbation theory, and our relevant next-to-next-to-leading order predictions from expanding nuclear physics with lattice quantum chromo dynamics collaboration’s works are novelly considered as the systematic uncertainties. Our outcomes are consistent with Roy equation determinations, newer experimental data, and lattice estimations. Numerical computations are performed with a coarse ($a\approx 0.12\mathrm{fm}$, $L^{3}T=32^{3}64$), two fine ($a\approx 0.09\mathrm{fm}$, $L^{3}T=40^{3}96$) and a superfine ($a\approx 0.06\mathrm{fm}$, $L^{3}T=48^{3}144$) lattice ensembles at four pion masses of $m_{\pi }\sim 247\mathrm{MeV}$, 249 MeV, 275 MeV, and 384 MeV, respectively.

We show how contour deformations may be used to control the sign problem of lattice Monte Carlo calculations with nonholomorphic Boltzmann factors. Such actions arise naturally in quantum mechanical scattering problems. The approach is demonstrated in conjunction with the holomorphic gradient flow. As our central example we compute the real-time evolution of a particle in a one-dimensional analog of the Yukawa potential.

This study investigates the subleading twist generalized transverse momentum dependent distributions (GTMDs) of a proton within the light-front quark-diquark model framework. We solve the parametrization equations for the Dirac matrix structure, yielding explicit GTMD expressions for both scalar and vector diquark configurations, leading to expressions for active $u$ and $d$ quarks. This analysis addresses the multidimensional nature of GTMDs by exploring their dependencies on one or two variables while keeping others fixed. Additionally, we extract transverse momentum dependent form factors from GTMDs by integrating over the longitudinal momentum fraction $x$. The study uses three-dimensional plots to illustrate the variation of transverse momentum dependent form factors with the quark’s transverse momentum $p_{\perp }$ and the transverse momentum transfer to the proton ${\mathrm{\Delta }}_{\perp }$.

Coherent elastic neutrino-nucleus scattering ($\mathrm{CE}\nu \mathrm{NS}$) provides a unique probe for neutrino properties beyond the Standard Model physics. The reactor neutrino liquid xenon coherent scattering experiment (RELICS), a proposed reactor neutrino program using liquid xenon time projection chamber technology, aims to investigate the $\mathrm{CE}\nu \mathrm{NS}$ process of antineutrinos off xenon atomic nuclei. In this work, the design of the experiment is studied and optimized based on Monte Carlo simulations. To achieve a sufficiently low-energy threshold for $\mathrm{CE}\nu \mathrm{NS}$ detection, an ionization-only analysis channel is adopted for RELICS. A high emission rate of delayed electrons after a big ionization signal is the major background, leading to an analysis threshold of 120 photoelectrons in the $\mathrm{CE}\nu \mathrm{NS}$ search. The second largest background, nuclear recoils induced by cosmic-ray neutrons, is suppressed via a passive water shield. The physics potential of RELICS is explored with a $30\mathrm{kg}·\mathrm{yr}$ exposure at a baseline of 25 m from a reactor core with a 3 GW thermal power. In an energy range of 120–300 photoelectrons, corresponding to an average nuclear recoil from 0.63 to 1.36 keV considering the liquid xenon response and detector-related effect, we expect 4639.7 $\mathrm{CE}\nu \mathrm{NS}$ and 1687.8 background events. The sensitivity of RELICS to the weak mixing angle is investigated at a low momentum transfer. Our study shows that RELICS can further improve the constraints on the nonstandard neutrino interaction compared to the current best results.

We present a generalization of the quantum volume operator quantifying the volume in curved three-dimensional discrete geometries. In its standard form, the quantum volume operator is constructed from tetrahedra whose faces are endowed with irreducible representations of SU(2). Here, we show two equivalent constructions that allow general objects in fusion categories as degrees of freedom. First, we compute the volume operator for ribbon fusion categories. This includes the important class of modular tensor categories (such as quantum doubles), which are the building blocks of anyon models. Second, we further generalize the volume operator to spherical fusion categories by relaxing the categorical analog of the closure constraint (known as tetrahedral symmetry). In both cases, we obtain a volume operator that is Hermitian, provided that the input category is unitary. As an illustrative example, we consider the case of $\mathrm{SU}(2{)}_k$ and show that the standard SU(2) volume operator is recovered in the limit $k\to \infty$.

We analyze the general structure of the three-point functions involving conserved higher-spin “vectorlike” supercurrents $J_s(z)≔J_{\alpha (s)\dot{\alpha }(s)}(z)$ in four-dimensional $\mathcal{N}=1$ superconformal field theory. Using the constraints of superconformal symmetry and superfield conservation equations, we utilize a computational approach to analyze the general structure of the three-point function $⟨J_{s_1}(z_1)J_{s_2}^{\prime }(z_2)J_{s_3}^{\prime \prime }(z_3)⟩$ and provide a general classification of the results. We demonstrate that the three-point function is fixed up to $2\min (s_i)+2$ independent conserved structures, which we propose to hold for arbitrary superspins. In addition, we show that the conserved structures can be classified as parity-even or parity-odd in superspace based on their transformation properties under superinversion.

We calculate the quasinormal modes of a nonsingular spherically symmetric black hole effective model with holonomy corrections. The model is based on quantum corrections inspired by loop quantum gravity. It is covariant and results in a spacetime that is regular everywhere with a parameter-dependent black bounce. Perturbations of these black holes due to massless scalar and electromagnetic fields have been previously calculated, and some intriguing results were observed. For some modes, the frequency versus minimum-radius parameter trajectories were found to spiral and self-intersect in the complex plane. In addition, the spectrum of overtones has real frequencies that oscillate with increasing overtone number and may even vanish for some overtones. We have calculated the quasinormal modes for all massless spin perturbations, including spin-$1/2$ and axial- and polar-gravitational. We find that the trajectory spirals are restricted to scalar perturbations and observe some interesting overtone behavior for gravitational perturbations. The amount of isospectrality violation in the gravitational quasinormal mode spectra is also examined.