The nonlinear instability of anti-de Sitter spacetime has recently been established with the striking result that generic initial data collapse to form black holes. This outcome suggests that confined matter might generically collapse, and that collapse could only be halted—at most—by nonlinear bound states. Here, we provide evidence that such a mechanism can operate even in asymptotically flat spacetimes by studying the evolution of the Einstein-Klein-Gordon system for a self-interacting scalar field. We show that (i) configurations which do not collapse promptly can do so after successive reflections off the potential barrier, but (ii) that at intermediate amplitudes and Compton wavelengths, collapse to black holes is replaced by the appearance of oscillating soliton stars, or “oscillatons.” Finally, (iii) for very small initial amplitudes, the field disperses away in a manner consistent with power-law tails of massive fields. Minkowski is stable against gravitational collapse. Our results provide one further piece to the rich phenomenology of gravitational collapse and show the important interplay between bound states, blueshift, dissipation and confinement effects.

It is shown that flavor mixing of the strange and light quarks allows for existence of a much larger baryonic chemical potential window for the formation of a stable dual chiral-wave state as compared to the well-known two-flavor case. In addition, strangeness catalyzes the occurrence of a new branch of nonhomogeneous solutions at moderate densities. This case study is addressed at zero temperature within the SU(3) flavor Nambu–Jona-Lasinio model with the ’t Hooft determinantal flavor mixing interaction. The modulation of the chiral condensates in the light quark sector is taken to be one dimensional, while strangeness is embedded as a homogeneous condensate in the spontaneously broken phase of chiral symmetry. A finite current quark mass for the strange quark is incorporated, while the up and down current masses are set to zero. In that case the modulation considered provides an exact analytic solution for the system. Despite the simplicity of the ansatz, the emerging phase diagram displays a very rich structure.

A ${\mathcal{G}}_{\mathcal{F}}=SU(3{)}_Q\times SU(3{)}_u\times SU(3{)}_d$ invariant scalar potential breaking spontaneously the quark flavor symmetry can explain the standard model flavor puzzle. The approximate alignment in flavor space of the vacuum expectation values of the up and down “Yukawa fields” is explained as a dynamical effect, and the observed quark mixing angles, the weak $CP$ violating phase, and hierarchical quark masses can be reproduced without introducing hierarchical parameters.

Many models of electroweak symmetry breaking predict new particles with masses at or just beyond LHC energies. Even if these particles are too massive to be produced on-shell at the LHC, it may be possible to see evidence of their existence through the use of integral dispersion relations (IDRs). Making use of Cauchy’s integral formula and the analyticity of the scattering amplitude, IDRs are sensitive in principle to changes in the cross section at arbitrarily large energies. We investigate some models of new physics. We find that a sudden, order-one increase in the cross section above new particle mass thresholds can be inferred well below the threshold energy. On the other hand, for two more physical models of particle production, we show that the reach in energy and the signal strength of the IDR technique is greatly reduced. The peak sensitivity for the IDR technique is shown to occur when the new particle masses are near the machine energy, an energy where direct production of new particles is kinematically disallowed, phase-space suppressed, or, if applicable, suppressed by the soft parton distribution functions. Thus, IDRs do extend the reach of the LHC, but only to a window around $M_{\chi }\sim \sqrt{s_{\mathrm{LHC}}}$.

This paper reports on a new procedure for the lattice spacing setting that takes advantage of the very precise determination of the strong coupling in the Taylor scheme. Although it can be applied for the physical scale setting with the experimental value of ${\mathrm{\Lambda }}_{\overline{\text{MS}}}$ as an input, the procedure is particularly appropriate for relative “calibrations.” The method is here applied for simulations with four degenerate light quarks in the sea and leads to prove that their physical scale is compatible with the same one for simulations with two light and two heavy flavors.

We report the results of a search for the $X(1835)$ state in the process $e^{+}{e}^{-}\to J/\psi X(1835)$ using a data sample of $672{\mathrm{fb}}^{-1}$ collected with the Belle detector at and near the $\mathrm{\Upsilon }(4S)$ resonance at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. No significant evidence is found for this process, and an upper limit is set on its cross section times the branching fraction: ${\sigma }_{\text{Born}}(e^{+}{e}^{-}\to J/\psi X(1835))·\mathcal{B}(X(1835)\to \ge 3\text{charged tracks})<1.3\mathrm{fb}$ at 90% confidence level.

We consider the decay rate for scalar fields in Kerr spacetime. We consider pure initial (azimuthal) multipoles ${\ell }^{\prime }$ with respect to the class that includes Boyer-Lindquist coordinates, and focus attention on the decay rate of the multipole $\ell$. We use an iterative method proposed by Gleiser, Price, and Pullin, and identify the mode-coupling mechanism through the iterations in powers of the square of the Kerr black hole’s specific angular momentum that gives rise to a decay rate formula recently proposed by Zenginoğlu, Khanna, and Burko. Modes $\ell$ may be excited through different channels, each leading to its own decay rate. The asymptotic decay rate of the mode $\ell$ is the slowest of the decay rate of the various channels. In some cases, more than one channel leads to the same decay rate, and then the amplitude of the mode is the sum of the amplitudes of the partial fields generated by the individual channels. We also show that one may identify the asymptotically dominant channel of mode excitations and obtain approximate results for the mode of interest by studying the dominant channel. The results of the dominant channel approximation approach the full-mode results at late times, and their difference approaches zero quadratically in inverse time.

By wrapping $D3$-branes over 3-cycles on a half-flat manifold, we construct an effective supersymmetric black hole in the $\mathcal{N}=2$ low-energy theory in four dimensions. Specifically, we find that the torsion cycles present in a half-flat compactification, corresponding to the mirror symmetric image of electric Neveu-Schwarz flux on a Calabi–Yau manifold, manifest in the half-flat black hole as quantum hair. We compute the electric and magnetic charges related to the quantum hair and also the mass contribution to the effective black hole. We find that by wrapping a number of $D3$-branes equal to the order of the discrete group associated to the torsional part of the half-flat homology, the effective charge and mass terms vanish. We compute the variation of entropy and the corresponding temperature associated with the loss of quantum hair. We also comment on the equivalence between canceling Freed–Witten anomaly and the assumption of self-duality for the 5-form field strength. Finally from a K-theoretical perspective, we compute the presence of discrete Ramond–Ramond charge of $D$-branes wrapping torsional cycles in a half-flat manifold.

By considering fluxes on D7 branes and explicitly computing their backreaction on the geometry with and without a black hole, we show how the UV divergence of the Klebanov-Strassler model can be regulated. Using the form of the metric and fluxes in the extremal and nonextremal limits, we compute the on-shell gravity action including the localized sources up to linear order in the perturbation parameter $\frac{g_s{M}^2}{N}$, $g_s{N}_f$, where $N$, $M$ and $N_f$ are units of D3, D5 and D7 charges in the dual gauge theory, respectively. Using the gravitational description, we show how the gauge theory undergoes a first-order Hawking-Page-like phase transition and compute the critical temperature $T_c$. Finally, we obtain the equation of state for the gauge theory by computing the thermodynamic state functions of the black hole and exhibit how black holes in a deformed cone geometry can lead to results that are qualitatively similar to lattice QCD simulations.

Information about the neutron-star equation of state is encoded in the waveform of a black hole-neutron star system through tidal interactions and the possible tidal disruption of the neutron star. During the inspiral this information depends on the tidal deformability $\mathrm{\Lambda }$ of the neutron star, and we find that the best-measured parameter during the merger and ringdown is consistent with $\mathrm{\Lambda }$ as well. We performed 134 simulations where we systematically varied the equation of state as well as the mass ratio, neutron star mass, and aligned spin of the black hole. Using these simulations we develop an analytic representation of the full inspiral-merger-ringdown waveform calibrated to these numerical waveforms; we use this analytic waveform and a Fisher matrix analysis to estimate the accuracy to which $\mathrm{\Lambda }$ can be measured with gravitational-wave detectors. We find that although the inspiral tidal signal is small, coherently combining this signal with the merger-ringdown matter effect improves the measurability of $\mathrm{\Lambda }$ by a factor of $\sim 3$ over using just the merger-ringdown matter effect alone. However, incorporating correlations between all the waveform parameters then decreases the measurability of $\mathrm{\Lambda }$ by a factor of $\sim 3$. The uncertainty in $\mathrm{\Lambda }$ increases with the mass ratio, but decreases as the black hole spin increases. Overall, a single Advanced LIGO detector can only marginally measure $\mathrm{\Lambda }$ for mass ratios $Q=2–5$, black hole spins $J_{\mathrm{BH}}/M_{\mathrm{BH}}^2=-0.5–0.75$, and neutron star masses $M_{\mathrm{NS}}=1.2M_{\odot }–1.45M_{\odot }$ at an optimally oriented distance of 100 Mpc. For the proposed Einstein Telescope, however, the uncertainty in $\mathrm{\Lambda }$ is an order of magnitude smaller.

The static forces between electric charges and currents are modified at the loop level by the presence of a plasma. While electric charges are screened, currents are not. The effective coupling constant at long distances is enhanced in both cases as compared to the vacuum, and by different amounts, a clear sign that Lorentz symmetry is broken. We investigate these effects quantitatively, first in a QED plasma and second using nonperturbative simulations of QCD with two light degenerate flavors of quarks.

Black hole lensing and gravitational waves are, respectively, closely dependent on the property of the lens and radiation source. In this paper, a universal relation between them is established for a rotating, asymptotically flat black hole acting simultaneously as a lens and a gravitational wave source. The relation only relies on the lens geometry and observable; it does not depend on the specific nature of the black hole. Therefore, the possible gravitational wave sources could be located with modern astronomical instruments from the side of the lensing without knowing the specific nature of the black hole lens. Moreover, the low bound of the gravitational wave frequency can also be well determined for a gravitational wave source.

While many aspects of general relativity have been tested, and general principles of quantum dynamics demand its quantization, there is no direct evidence for that. It has been argued that development of detectors sensitive to individual gravitons is unlikely, and perhaps impossible. We argue here, however, that measurement of polarization of the cosmic microwave background due to a long wavelength stochastic background of gravitational waves from inflation in the early Universe would firmly establish the quantization of gravity.

We study charged Dirac fermions on an ${\mathrm{AdS}}_2\times {\mathbb{R}}^2$ background with a nonzero magnetic field. Under certain boundary conditions, we show that the charged fermion can make the background unstable, resulting in spontaneous formation of a vortex lattice. We observe that an electric field emerges in the backreacted solution due to the vortex lattice constructed from spin polarized fermions. This electric field may be extended to the UV boundary which leads to a finite charge density. We also discuss corrections to the thermodynamic functions due to the lattice formation.

We investigate the quantum field aspects in flat spacetime for a uniformly accelerated observer moving in a thermal bath. In particular, we obtain an exact closed expression of the reduced density matrix for a uniformly accelerated observer with acceleration $a=2\pi T$ when the state of the quantum field is a thermal bath at temperature $T^{\prime }$. We find that the density matrix has a simple form with an effective partition function $Z$ being a product, $Z=Z_T{Z}_{T^{\prime }}$, of two thermal partition functions corresponding to temperatures $T$ and $T^{\prime }$ and hence is not thermal, even when $T=T^{\prime }$. We show that, even though the partition function has a product structure, the two thermal baths are, in fact, interacting systems; although in the high frequency limit ${\omega }_k\gg T$ and ${\omega }_k\gg T^{\prime }$, the interactions are found to become subdominant. We further demonstrate that the resulting spectrum of the Rindler particles can be interpreted in terms of spontaneous and stimulated emission due to the background thermal bath. The density matrix is also found to be symmetric in the acceleration temperature $T$ and the thermal bath temperature $T^{\prime }$ indicating that thermodynamic experiments alone cannot distinguish between the thermal effects due to $T$ and those due to $T^{\prime }$. The entanglement entropy associated with the reduced density matrix (with the background contribution of the Davies-Unruh bath removed) is shown to satisfy, in the ${\omega }_k\gg T^{\prime }$ limit, a first law of thermodynamics relation of the form $T\delta S=\delta E$, where $\delta E$ is the difference in the energies corresponding to the reduced density matrix and the background Davies-Unruh bath. The implications are discussed.

We study relevant cosmological topics in the framework of a certain vector-tensor theory of gravitation (hereafter VT). This theory is first compared with the so-called extended electromagnetism (EE). These theories have a notable resemblance and both explain the existence of a cosmological constant. It is shown that, in EE, a positive dark energy density requires a Lagrangian leading to quantum ghosts, whereas VT is free from these ghosts. On account of this fact, the remainder of the paper is devoted to study cosmology in the framework of VT. Initial conditions, at high redshift, are used to solve the evolution equations of all the VT scalar modes. In particular, a certain scalar mode characteristic of VT—which does not appear in general relativity (GR)—is chosen in such a way that it evolves separately. In other words, the scalar modes of the standard model based on GR do not affect the evolution of the VT characteristic mode; however, this scalar mode influences the evolution of the standard GR ones. Some well known suitable codes (cmbfast and cosmomc) have been modified to include our VT initial conditions and evolution equations, which are fully general. One of the resulting codes—based on standard statistical methods—has been used to fit VT predictions and observational evidence about both Ia supernovae and cosmic microwave background anisotropy. Seven free parameters are used in this fit. Six of them are often used in GR cosmology, and the seventh one is characteristic of VT. From the statistical analysis it follows that VT seems to be advantageous against GR in order to explain cosmological observational evidences.

We study the entropy relations of multihorizon black holes in higher dimensional (A)dS spacetime with maximal symmetries, including Einstein-Maxwell gravity and $f(R)$(-Maxwell) gravity. These additional equalities in thermodynamics are expected to be useful in understanding the origin of black hole entropy at the microscopic level. By revisiting the entropy product introduced by Cvetic et al., we see that in our case it has an unexpected behavior. It is shown that this electric charge $Q$ plays an important role in this entropy product. The entropy product of charged black holes only depends on the electric charge $Q$ and is mass independent. When $Q$ vanishes in the solution, it becomes mass dependent, even when including the effect of the unphysical “virtual” horizons. In this sense, the “universal relation” of this entropy product is destroyed. Then we introduce another kind of “universal” entropy relation, which only depends on the cosmological constant $\mathrm{\Lambda }$ and the background topology $k$ and does not depend on the conserved charges $Q$ or even the mass $M$.

We use a dynamical systems approach based on the method of orthonormal frames to study the dynamics of a nontilted Bianchi type IX cosmological model with a bulk and shear viscous fluid source. We begin by completing a detailed fixed-point analysis which give the local sinks, sources and saddles of the dynamical system. We then analyze the global dynamics by finding the $\alpha$-and $\omega$-limit sets which give an idea of the past and future asymptotic behavior of the system. The fixed points were found to be a flat Friedmann-LeMaître-Robertson-Walker (FLRW) solution, Bianchi type II solution, Kasner circle, Jacobs disc, Bianchi type $\mathrm{V}\mathrm{I}{\mathrm{I}}_0$ solutions, and several closed FLRW solutions in addition to the Einstein static universe solution. Each equilibrium point was described in both its expanding and contracting epochs. We conclude the paper with some numerical experiments that shed light on the global dynamics of the system along with its heteroclinic orbits. With respect to past asymptotic states, we were able to conclude that the Jacobs disc in the expanding epoch was a source of the system along with the flat FLRW solution in a contracting epoch. With respect to future asymptotic states, we were able to show that the flat FLRW solution in an expanding epoch along with the Jacobs disc in the contracting epoch were sinks of the system. We were also able to demonstrate a new result with respect to the Einstein static universe. Namely, we gave certain conditions on the parameter space such that the Einstein static universe has an associated stable subspace. We were, however, not able to conclusively say anything about whether a closed FLRW model could be a past or future asymptotic state of the model.

In this paper, a unified dark fluid with constant adiabatic sound speed is decomposed into cold dark matter interacting with vacuum energy. Based on a Markov-chain Monte Carlo method, we constrain this model by jointing the geometry and dynamical measurement. The geometry test includes cosmic microwave background radiation from Planck, baryon acoustic oscillation, and type-Ia supernovae; the dynamic measurement is $f{\sigma }_8(z)$ data points, which is obtained from the growth rate via redshift space distortion, and ${\sigma }_8(z)$ is the root-mean-square amplitude of the density contrast $\delta$ at the comoving $8h^{-1}\mathrm{Mpc}$ scale. The jointed constraint shows that $\alpha =0.000662_{-0.000662}^{+0.000173}$ and ${\alpha }_8=0.824_{-0.0166}^{+0.0128}$. The CMB and matter power spectra are both similar for the case of $\alpha =\text{mean}$ value and that of $\alpha =0$. However, the evolutionary curves of $f{\sigma }_8(z)$ are different. This means that, to some extent, the data points of the growth rate could break the degeneracy of the dark energy models.

Gravitational-wave observations in the near future may allow us to measure tidal deformabilities of neutron stars, which leads us to the understanding of physics at nuclear density. In principle, the gravitational waveform depends on various tidal parameters, which correlate strongly. Therefore, it would be useful if one can express such tidal parameters with a single parameter. Here, we report on universal relations among various $\ell$th (dimensionless) electric, magnetic, and shape tidal deformabilities in neutron stars and quark stars that do not depend sensitively on the equation of state. Such relations allow us to break the degeneracy among the tidal parameters. In this paper, we focus on gravitational waves from nonspinning neutron-star binary inspirals. We first derive the leading contribution of the $\ell$th electric and $\ell =2$ magnetic tidal deformabilities to the gravitational-wave phase, which enters at $2\ell +1$ and 6 post-Newtonian orders relative to the leading Newtonian one, respectively. We then calculate the useful number of gravitational-wave cycles and show that not only the $\ell =2$ but also $\ell =3$ electric tidal deformabilities are important for parameter estimation with third-generation gravitational-wave detectors such as LIGO III and Einstein Telescope. Although the correlation between the $\ell =2$ and $\ell =3$ electric tidal deformabilities deteriorate the measurement accuracy of the former deformability parameter, one can increase its measurement accuracy significantly by using the universal relation. We provide a fitting formula for the LIGO III noise curve in the appendixes.