We use the QCD instanton vacuum model to discuss the emergence of the light scalar and vector mesons on the light front. We take into account both the instanton and anti-instanton single and molecular interactions on the light quarks, in the form of nonlocal effective interactions. Although the molecular induced interactions are suppressed by a power of the packing fraction, they are still sufficient to bind the vector mesons, while keeping most of the scalar spectrum relatively unchanged. We explicitly derive the light front distribution amplitudes and partonic functions for the scalar and vector mesons, and compare them after pertinent QCD evolution, to the available empirical and lattice measured counterparts. The Dirac electric form factors for both the pion and $\rho$ meson are derived, and shown to compare well with current data.

Based on $(27.12\pm 0.14)\times {10}^8\psi (2S)$ events collected by the BESIII detector, we search for the decay ${\eta }_c(2S)\to {\pi }^{+}{\pi }^{-}{\eta }_c$ via $\psi (2S)\to \gamma {\eta }_c(2S)$. No significant signal is observed, and the upper limit on the product branching fraction $\mathcal{B}(\psi (2S)\to \gamma {\eta }_c(2S))\times \mathcal{B}({\eta }_c(2S)\to {\pi }^{+}{\pi }^{-}{\eta }_c$) is determined to be $2.21\times {10}^{-5}$ at the 90% confidence level. In addition, the ${\eta }_c(2S)\to {\pi }^{+}{\pi }^{-}{K}_S^0{K}^{\pm }{\pi }^{\mp }$ decay is studied via $\psi (2S)\to \gamma {\eta }_c(2S)$ and is observed with a statistical significance of $10\sigma$ for the first time. The branching fraction of ${\eta }_c(2S)\to {\pi }^{+}{\pi }^{-}{K}_S^0{K}^{\pm }{\pi }^{\mp }$ is determined to be ($1.33\pm 0.11\pm 0.40\pm 0.95$)$\times {10}^{-2}$, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the quoted $\mathcal{B}(\psi (2S)\to \gamma {\eta }_c(2S))$.

By analyzing $(27.12\pm 0.14)\times {10}^8\psi (3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decay processes ${\chi }_{cJ}\to 3(K^{+}{K}^{-})$ ($J=0$, 1, 2) are observed for the first time with statistical significances of $8.2\sigma$, $8.1\sigma$, and $12.4\sigma$, respectively. The product branching fractions of $\psi (3686)\to \gamma {\chi }_{cJ}$, ${\chi }_{cJ}\to 3(K^{+}{K}^{-})$ are presented and the branching fractions of ${\chi }_{cJ}\to 3(K^{+}{K}^{-})$ decays are determined to be ${\mathcal{B}}_{{\chi }_{c0}\to 3(K^{+}{K}^{-})}=(10.7\pm 1.8\pm 1.1)\times {10}^{-6}$, ${\mathcal{B}}_{{\chi }_{c1}\to 3(K^{+}{K}^{-})}=(4.2\pm 0.9\pm 0.5)\times {10}^{-6}$, and ${\mathcal{B}}_{{\chi }_{c2}\to 3(K^{+}{K}^{-})}=(7.2\pm 1.1\pm 0.8)\times {10}^{-6}$, where the first uncertainties are statistical and the second are systematic.

We show that quantum fields confined to Lorentzian histories of freely falling networks in Minkowski spacetime probe entanglement properties of vacuum fluctuations that extend unrestricted across spacetime regions. Albeit instantaneous field configurations are localized on one-dimensional edges, angular momentum emerges on these network histories and establish the celebrated area scaling of entanglement entropy.

Recently, Comisso and Asenjo proposed a novel mechanism for harnessing energy from black holes through magnetic reconnection. Our study focuses on exploring the utilization of this mechanism on Konoplya-Rezzolla-Zhidenko (KRZ) parametrized black holes to assess the impact of deformation parameters on energy extraction. Among the various parameters, $\{{\delta }_1,{\delta }_2\}$ are identified as the most important factors affecting the physics under consideration. The influence of these two parameters on the ergoregion, circular geodesics in the equatorial plane, and energy extraction from the KRZ black holes through magnetic reconnection is carefully analyzed. Results indicate that deviations from the Kerr metric have a notable influence on the energy extraction process. Particularly, energy extraction is enhanced with more negative ${\delta }_1$ or more positive ${\delta }_2$ within the range constrained by current astronomical observations, resulting in significantly higher maximum power and efficiency compared to the Kerr model. Moreover, when ${\delta }_2$ is sufficiently negative, extracting energy through this mechanism becomes increasingly challenging, necessitating an exceptionally high black hole spin.

Low-mass galaxies in the local group are dominated by dark matter and comprise the well-studied “dwarf spheroidal” (dSph) class, with typical masses of ${10}^9–{10}^{10}{M}_{\odot }$ and also the equally numerous “ultrafaint dwarfs” (UFDs), discovered recently, that are distinctly smaller and denser with masses of only ${10}^7–{10}^8{M}_{\odot }$. This bimodality amongst low-mass galaxies contrasts with the scale-free continuity expected for galaxies formed under gravity, as in the standard cold dark matter model for heavy particles. Within each dwarf class we find the core radius $R_c$ is inversely related to velocity dispersion $\sigma$, quite the opposite of standard expectations, but indicative of dark matter in a Bose-Einstein state, where the uncertainty principle requires $R_c\times \sigma$ is fixed by Planck’s constant, $h$. The corresponding boson mass, $m_b=h/R_c\sigma$, differs by one order of magnitude between the UFD and dSph classes, with ${10}^{-21.4}\mathrm{eV}$ and ${10}^{-20.3}\mathrm{eV}$, respectively. The two-boson species is reinforced by parallel relations seen between the central density and radius of UFD and dSph dwarfs, respectively, each matching the steep prediction, ${\rho }_c\propto R_c^{-4}$, for soliton cores in the ground state. Furthermore, soliton cores accurately fit the stellar profiles of UFD and dSph dwarfs where prominent, dense cores appear surrounded by low-density halos, as predicted by our simulations. Multiple bosons may point to a string theory interpretation for dark matter, where a discrete mass spectrum of axions is generically predicted to span many decades in mass, offering a unifying “axiverse” interpretation for the observed “diversity” of dark matter dominated dwarf galaxies.

Wave turbulence is by nature a multiple timescale problem for which there is a natural asymptotic closure. The main result of this analytical theory is the kinetic equation that describes the longtime statistical behavior of such turbulence composed of a set of weakly nonlinear interacting waves. In the case of gravitational waves, it involves four-wave interactions and two invariants, energy, and wave action. Although the kinetic equation of gravitational wave turbulence has been published with the Hadad-Zakharov metric, along with their physical properties, the detailed derivation has not been shown. Following the seminal work of Newell [Rev. Geophys. 6, 1 (1968).] for gravity/surface waves, we present the multiple timescale method, rarely used to derive the kinetic equations, and clarify the underlying assumptions and methodology. This formalism is applied to a wave amplitude equation obtained using an Eulerian approach. It leads to a kinetic equation slightly different from the one originally published, with a wave equation obtained using a Hamiltonian approach; we verify, however, that the two formulations are fully compatible when the number of symmetries used is the same. We also show that the exact solutions (Kolmogorov-Zakharov spectra) exhibit the same power laws and cascade directions. Furthermore, the use of the multiple timescale method reveals that the system retains the memory of the initially condition up to a certain level (second order) of development in time.

TianQin is a proposed space-based gravitational-wave observatory mission that critically relies on the stability of an equilateral-triangle constellation. Comprising three satellites in high Earth orbits of a ${10}^5\mathrm{km}$ radius, this constellation’s geometric configuration is significantly affected by gravitational perturbations, primarily originating from the Moon and the Sun. In this paper, we present an analytical model to quantify the effects of lunisolar perturbations on the TianQin constellation, derived using Lagrange’s planetary equations. The model provides expressions for three kinematic indicators of the constellation: arm’s lengths, relative line-of-sight velocities, and breathing angles. Analysis of these indicators reveals that lunisolar perturbations can distort the constellation triangle, resulting in three distinct variations: linear drift, bias, and fluctuation. Furthermore, it is shown that these distortions can be optimized to display solely fluctuating behavior, under certain predefined conditions. These results can serve as the theoretical foundation for numerical simulations and offer insights for engineering a stable constellation in the future.

The three-body threshold effect, the distinctive and intriguing nonperturbative dynamics in the low-energy hadron-hadron scattering, has acquired compelling significance in the wake of the recent observation of the double-charm tetraquark $T_{cc}^{+}$. This dynamics is characterized by the emergence of singular points and branch cuts within the interaction potential, occurring when the on-shell condition of the mediated particle is satisfied. The presence of these potential singularities indicates that the system is no longer Hermitian and also poses intractable challenges in obtaining exact solutions for dynamical scattering amplitudes. In this work, we develop a complex scaled Lippmann-Schwinger equation as an operation of analytical continuation of the $T$ matrix to resolve this problem. Through a practical application to the $D{D}^{*}\to D{D}^{*}$ process, we reveal complicated cut structures of the three-body threshold dynamics in the complex plane, primarily stemming from the one-pion exchange. Notably, our methodology succeeds in reproducing the $T_{cc}^{+}$ structure, in alignment with the quasibound pole derived from the complex scaling method within the Schrödinger equation framework. More remarkably, after solving the on-shell $T$ matrix on the positive real axis of momentum plane, we find an extra new structure in the $D{D}^{*}$ mass spectrum, which arises from a right-hand cut at a physical pion mass and should be observable in lattice QCD simulations and future high-energy experiments.

To distinguish the low-lying vector beauty-charm meson, we systematically study the $B_c^{*}\to B_c+\gamma$, $B_c^{*}\to \ell +{\nu }_{\ell }$, and $B_c^{(*)}\to J/\psi +nh$ processes within effective theory by the helicity decomposition method. The significant difference of polarization asymmetry in $B_c^{(*)}\to J/\psi +nh$ indicates a general law in vector-to-vector and pseudoscalar-to-vector transition processes, which can be tested in current and future LHC experiments. In the end, we discuss the experiment search and discovery potential for the low-lying vector beauty-charm meson.

We construct a holographic dual theory of one-dimensional anisotropic Heisenberg spin chain, which includes two Chern-Simons gauge fields and a charged scalar field. Thermodynamic quantities of the spin chain at low temperatures, which are exactly calculated from the integrability, are completely reproduced by the dual theory on three-dimensional black hole backgrounds and the exact matching of the parameters between the dual theory and the spin chain is obtained. The holographic dual theory provides a new theoretical framework to analyze the quantum spin chain and one-dimensional quantum many-body systems.

We show that large scale oscillons, i.e., quasiperiodic, long-living particlelike solutions, may exist in massless theories, too. Their existence is explained using an effective (smeared) mass threshold which takes into account nonlinear (finite) perturbations.

We build upon recent work by Antonelli et al. [Gravitational spin-orbit coupling through third-subleading post-Newtonian order: From first-order self-force to arbitrary mass ratios, Phys. Rev. Lett. 125, 011103 (2020).] to obtain, within the effective-one-body formalism, and for an arbitrary choice of gauge, the third-subleading post-Newtonian (4.5PN) corrections to the spin-orbit conservative dynamics of spin-aligned binaries. This is then specialized to (i) the well-known Damour-Jaranowski-Schäfer (DJS) gauge, where the dependence on the angular momentum of the gyrogravitomagnetic functions $(G_S,G_{S_{*}})$ is removed and (ii) to an alternative gauge (called anti-DJS gauge, $\overline{\mathrm{DJS}}$) that is chosen so as to precisely reproduce the Hamiltonian of a spinning test particle at linear order in the particle spin and keep the full dependence on the radial and angular momentum in $(G_S,G_{S_{*}})$. We use these results to extend by one perturbative order, in post-Newtonian sense, the analytical knowledge of the periastron advance. After performing a suitable factorization and resummation of $(G_S,G_{S_{*}})$, the DJS and $\overline{\mathrm{DJS}}$ performances are compared via various gauge-invariant quantities at the effective-one-body last stable circular orbit. We eventually find some indications that the $\overline{\mathrm{DJS}}$ gauge might be advantageous in the description of the inspiral dynamics of circularized binaries.

Strong gravitational lensing produces multiple images of a gravitational wave (GW) signal, which can be observed by detectors as time-separated copies of the same event. It has been shown that under favorable circumstances, by combining information from a quadruply lensed GW with electromagnetic observations of lensed galaxies, it is possible to identify the host galaxy of a binary black hole coalescence. Comparing the luminosity distance obtained through electromagnetic means with the effective luminosity distance inferred from the lensed GW signal would then enable us to constrain alternative theories of gravity that allow for modified GW propagation. Here we analyze models including large extra spatial dimensions, a running Planck mass, and a model that captures propagation effects occurring in a variety of alternative theories to general relativity. We consider a plausible population of lenses and binary black holes and use Bayesian inference on simulated GW signals as seen in current detectors at design sensitivity, to arrive at a realistic assessment of the bounds that could be placed. We find that, due to the fact that the sources of lensed events will typically be at much larger redshifts, this method can improve over bounds from GW170817 and its electromagnetic counterpart by a factor of $\sim 5$ to $\mathcal{O}({10}^2)$, depending on the alternative gravity model.

Many articles have partially studied the configuration of eccentric orbital binary black hole (BBH) mergers. However, there is a scarcity of systematic and comprehensive research on the effect of eccentricity on BBH dynamics. Thanks to the rich and numerous numerical relativistic simulations of eccentric orbital BBH mergers from Rochester Institute of Technology catalog, this paper aims to investigate the impact of initial eccentricity $e_0$ on various dynamic quantities such as merger time $T_{\text{merger}}$, peak luminosity $L_{\mathrm{peak}}$ of gravitational waves, recoil velocity $V_f$, mass $M_f$, and spin ${\alpha }_f$ of merger remnants. We cover configurations of no spin, spin alignment, and spin precession, as well as a broad parameter space of mass ratio ranging from $1/32$ to 1 and initial eccentricity from 0 to 1. For nonspinning BBH with an initial coordinate separation of $11.3M$ ($M$ is the total mass of BBH), we make the first discovery of a ubiquitous oscillation in the relationship between dynamic quantities $L_{\mathrm{peak}}$, $V_f$, $M_f$, ${\alpha }_f$, and initial eccentricity $e_0$. Additionally, at $24.6M$, we observe the same oscillation phenomenon in the case of mass ratio $q=1$ but do not see it in other mass ratios, suggesting that this oscillation will be evident in numerical simulations with sufficiently dense initial eccentricity. By associating the integer numbers of the orbital cycle of $N_{\text{orbits}}$ with the peaks and valleys observed in the curves depicting the relationship between the dynamic quantities and the initial eccentricity, we reveal the significant oscillatory behavior attributed to orbital transitions. This discovery sheds light on the presence of additional orbital transitions in eccentric BBH mergers, extending beyond the widely recognized transition from inspiral to plunge. We perform an analysis to understand the different behaviors exhibited by the dynamic quantities and attribute them to variations in the calculation formulas. Furthermore, we demonstrate that finely adjusting the initial eccentricity can lead to the remnant black hole becoming a Schwarzschild black hole in the case of spin alignment. In a comprehensive analysis that surpasses previous studies by encompassing cases of no spin, spin alignment, and spin precession, we reveal consistent variations in the correlation between dynamic quantities and initial eccentricity, regardless of the presence of spin. This discovery underscores the universality of the impact of eccentricity on BBH dynamics and carries profound implications for astrophysical research.

We consider marginally trapped surfaces in a spherically symmetric spacetime evolving due to the presence of a perfect fluid in D-dimensions and look at the various definitions of the surface gravity for these marginally trapped surfaces. We show that using Einstein equations it is possible to simplify and obtain general formulas for the surface gravity in terms of invariant quantities defined at these marginally trapped surfaces like area radius, cosmological constant, and principal values of the energy-momentum tensor $\rho$, $p$. We then correlate these expressions of surface gravity to the cases of dynamical horizons and timelike tubes and find which proposals of surface gravity are causally sensitive as these surfaces undergo causal transitions from spacelike to timelike and vice versa.

Regularized Maxwell electrodynamics is a recently discovered theory of nonlinear electrodynamics, with a minimally regularized field strength of a point charge, that is very close to the Maxwell theory in many aspects. In this paper we investigate some of the optical properties of its black holes. Namely, we study geodesics, gravitational redshift, black hole shadow, as well as investigate the relationship between the behavior of (null geodesic) Lyapunov exponents and the existence of thermodynamic critical points in both canonical and grand-canonical ensembles.

Using effective field theory methods, we compute in detail the Lagrangian for the conservative dynamics of compact binary systems, for spinless constituents and in the gravitationally bound case, in massless scalar-tensor and Einstein-scalar-Gauss-Bonnet gravity to the second post-Newtonian (2PN) order. We employ the Kaluza-Klein parametrization of the metric, and demonstrate that, also in this case, a significant reduction in the number of diagrams is achieved. Still, to the 2PN accuracy, an additional 39 diagrams involving scalar interactions must be added to the pure general relativistic result. Diagrams involving the Gauss-Bonnet term at the formal 1PN order are computed and shown to scale as a 3PN correction when observational constraints are taken into account. We also investigate at which order the additional $\mathcal{O}(G^3)$ topologies contribute. Finally, the results derived in this paper provide an essential step toward the correct derivation of the conservative dynamics at the 3PN level in scalar-tensor and Einstein-scalar-Gauss-Bonnet theories.

Tetrahedral configurations of spacecraft on unperturbed heliocentric orbits allow for highly precise observations of small spatial changes in the gravitational field, especially those affecting the gravity gradient tensor (GGT). The resulting high sensitivity may be used to search for new physics that could manifest itself via deviations from general relativistic behavior yielding a nonvanishing trace of the GGT. We study the feasibility of recovering the trace[GGT] with the sensitivity of $\mathcal{O}({10}^{-24}{\mathrm{s}}^{-2})$—the level where some of the recently proposed cosmological models may have observable effects in the Solar System. Specifically, we consider how a set of local measurements provided by precision laser ranging (to measure the intersatellite ranges) and atom-wave interferometry (to correct for any local nongravitational disturbances) can be used for that purpose. We report on a preliminary study of such an experiment and on the precision that may be reached in measuring the trace[GGT], with the assumption of drag-compensated spacecraft by atom interferometer measurements. For that, we study the dynamical behavior of a tetrahedral formation established by four spacecraft placed on nearby elliptical orbits around the Sun. We develop analytical models for the relevant observables and study the conditions for setting up an optimal tetrahedral configuration. We formulate the observational equations to measure the trace[GGT] relying only on the observables that are available within the formation, such as those based on the laser ranging and the Sagnac interferometry. We demonstrate that the Sagnac observable is a mission-enabling capability that allows us to measure the angular frequency of the tetrahedral rotation with respect to an inertial reference frame with an accuracy that is much higher than that available from any other modern navigational techniques. We show that the quality of the science measurements is affected by the tetrahedron evolution, as its orientation and the shape change while the spacecraft follow their orbits. We present the preliminary mission and instrument requirements needed to measure the trace[GGT] to the required accuracy and thus demonstrate the feasibility of satisfying the stated science objective.

The merger phase of compact binary coalescences is the strongest gravity regime that can be observed. To test the validity of general relativity (GR) in strong gravitational fields, we propose a gravitational waveform parametrized for deviations from GR in the dynamical and nonlinear regime of gravity. Our fundamental idea is that perturbative modifications to a GR waveform can capture possible deviations in the merger phase that are difficult to model in a specific theory of gravity. One of notable points is that our waveform is physically consistent in the sense that the additional radiative losses of energy and angular momentum associated with beyond-GR modifications are included. Our prescription to ensure physical consistency in the whole coalescence process is expected to be applicable to any deviation from the standard model of compact binary coalescence, such as the extended models of gravity or the environmental effects of compact objects, as long as perturbative modifications are considered. Based on the Fisher analysis and the compatibility with Einstein-dilaton Gauss-Bonnet waveforms, we show that our parametrization is a physically consistent minimal one that captures the deviations in the nonlinear regime.