A coarse-grained description for the formation and evaporation of a black hole is given within the framework of a unitary theory of quantum gravity preserving locality, without dropping the information that manifests as macroscopic properties of the state at late times. The resulting picture depends strongly on the reference frame one chooses to describe the process. In one description based on a reference frame in which the reference point stays outside the black hole horizon for sufficiently long time, a late black hole state becomes a superposition of black holes in different locations and with different spins, even if the back hole is formed from collapsing matter that had a well-defined classical configuration with no angular momentum. The information about the initial state is partly encoded in relative coefficients—especially phases—of the terms representing macroscopically different geometries. In another description in which the reference point enters into the black hole horizon at late times, an $S$-matrix description in the asymptotically Minkowski spacetime is not applicable, but it still allows for an “$S$-matrix” description in the full quantum gravitational Hilbert space including singularity states. Relations between different descriptions are given by unitary transformations acting on the full Hilbert space, and they in general involve superpositions of “distant” and “infalling” descriptions. Despite the intrinsically quantum mechanical nature of the black hole state, measurements performed by a classical physical observer are consistent with those implied by general relativity. In particular, the recently-considered firewall phenomenon can occur only for an exponentially fine-tuned (and intrinsically quantum mechanical) initial state, analogous to an entropy decreasing process in a system with large degrees of freedom.

Black hole candidates in X-ray binary systems and at the centers of galaxies are expected to be the Kerr black holes of general relativity, but the actual nature of these objects has yet to be verified. In this paper, we consider the possibility that they are exotic compact objects and we describe their exterior gravitational field with a subclass of the Manko-Novikov metrics, which are exact solutions of the vacuum Einstein’s equations and can describe the spacetime geometry around bodies with arbitrary mass-multipole moments. We point out that around a Manko-Novikov object there may exist many disconnected nonplunging regions at small radii, with no counterpart in the Kerr background, and that their existence may be tested. For instance, in the presence of an accretion disk, they may be filled by the accreting gas, forming a ring structure that might remind the one of the rings of Saturn. We suggest that the existence of these regions may have a clear observational signature in the waveform of the gravitational radiation emitted by an extreme-mass-ratio inspiral: in the last stage of the inspiral, the waveform would be the combination of “regular chirps,” produced when the small object orbits in one of the nonplunging regions, and “bursts,” which are released when the small object jumps from a nonplunging region to another one at smaller radii. Our conclusions are supported by some numerical calculations of trajectories in the geodesic approximation, in which a particle plunges from the innermost stable circular orbit and then seems to get trapped in the potential well at smaller radii.

Analysis of contributions from vectorlike leptonic supermultiplets to the Higgs diphoton decay rate and to the Higgs boson mass is given. Corrections arising from the exchange of the new leptons and their superpartners as well as their mirrors are computed analytically and numerically. We also study the correlation between the enhanced Higgs diphoton rate and the Higgs mass corrections. Specifically, we find two branches in the numerical analysis: on the lower branch the diphoton rate enhancement is flat, while on the upper branch it has a strong correlation with the Higgs mass enhancement. It is seen that a factor of 1.4–1.8 enhancement of the Higgs diphoton rate on the upper branch can be achieved, and a 4–10 GeV positive correction to the Higgs mass can also be obtained simultaneously. The effect of this extra contribution to the Higgs mass is to release the constraint on weak-scale supersymmetry, allowing its scale to be lower than in the theory without extra contributions. The vectorlike supermultiplets also have collider implications which could be testable at the LHC and at the ILC.

In this paper, we study the Cabibbo favored nonleptonic $D^0$ decays into $K^{-}{\pi }^{+}$ decays. First we show that, within the Standard Model (SM), the corresponding charge conjugation and parity ($CP$) asymmetry is strongly suppressed and out of the experimental range, even taking into account the large strong phases coming from final state interactions. We show also that although new physics models with extra sequential generation can enhance the $CP$ asymmetry by a few orders of magnitude, the resulting $CP$ asymmetry is still far from the experimental range. The most sensitive new physics models to this $CP$ asymmetry come from nonmanifest left-right models, where a $CP$ asymmetry up to 10% can be reached, and the general two-Higgs model extension of the SM, where a $CP$ asymmetry of order ${10}^{-2}$ can be obtained without being in contradiction with the experimental constraints on these models.

We review the known results on the bosonic spectrum in various Nambu-Jona-Lasinio models both in condensed matter physics and in relativistic quantum field theory including ${}^3\mathrm{He}\mathrm{\text{−}}\mathrm{B}$, ${}^3\mathrm{He}\mathrm{\text{−}}\mathrm{A}$, the thin films of superfluid ${}^3\mathrm{He}$, and QCD (Hadronic phase and the color-flavor locking phase). Next, we calculate the bosonic spectrum in the relativistic model of top quark condensation suggested in [Phys. Lett. B 221, 177 (1989)]. In all considered cases, the sum rule appears, which relates the masses (energy gaps) $M_{\mathrm{boson}}$ of the bosonic excitations in each channel with the mass (energy gap) of the condensed fermion $M_f$ as $\sum _{}^{}{M}_{\mathrm{boson}}^2=4M_f^2$. Previously, this relation was established by Nambu for ${}^3\mathrm{He}\mathrm{\text{−}}\mathrm{B}$ and for the $s$-wave superconductor. We generalize this relation to the wider class of models and call it the Nambu sum rule. We discuss the possibility to apply this sum rule to various models of top quark condensation. In some cases, this rule allows us to calculate the masses of extra Higgs bosons that are the Nambu partners of the 125 GeV Higgs.

The weakly interacting massive particle paradigm for dark matter is currently being probed via many different experiments. Direct detection, indirect detection and collider searches are all hoping to catch a glimpse of these elusive particles. Here, we examine the potential of the International Linear Collider (ILC) to shed light on the origin of dark matter. By using an effective field theory approach we are also able to compare the reach of the ILC with that of the other searches. We find that for low mass dark matter ($<10\mathrm{GeV}$), the ILC offers a unique opportunity to search for interacting massive particles beyond any other experiment. In addition, if dark matter happens to only couple to leptons or via a spin dependent interaction, the ILC can give an unrivalled window to these models. We improve on previous ILC studies by constructing a comprehensive list of effective theories that allows us to move beyond the nonrelativistic approximation.

We consider the prospects for direct dark matter detection in the case when the candidate particle couples to matter primarily through ordinary weak interactions. Existing experimental limits exclude the Dirac case by the very large coherent cross section and narrow down the possibilities to a Majorana particle with a purely axial coupling to the $Z$, while considerations based on relic abundance disfavor the case of spin $1/2$. We then focus on the new spin $3/2$ candidate with weak interactions. In the Majorana case, the particle can account for all of the dark matter for a range of masses between 70 and 160 GeV, depending on the strength of the Higgs couplings. The elementary spin-dependent cross section on the nucleon is calculated to be 17 fb and does not depend on the mass or any additional parameters. The amplitude at the nuclear level is of the purely isovector form. We make detailed predictions for differential and total rates of scattering on a variety of nuclear targets of interest to the current direct detection experiments. For heavy targets the annual modulation amplitude is predicted to be negative, which may help to determine the mass of the particle if and when data become available.

The D0 Collaboration has measured the like-sign dimuon charge asymmetry in $p\overline{p}$ collisions at the Fermilab Tevatron collider. The result is significantly different from the standard model expectation of $CP$ violation in mixing. In this paper we consider the possible causes of this asymmetry and identify one standard model source not considered before, namely, $CP$ violation in interference of decays of $B^0$ with and without mixing to flavor nonspecific states $f_i$, followed by the decay $f_i\to \mu X$. The discrepancy between the D0 measurement and the standard model expectation is reduced to less than 3 standard deviations.

We study hadronic molecules formed by a heavy meson and a nucleon, $DN$ and $D^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) systems. Respecting the heavy quark symmetry and chiral symmetry, we consider the $DN\mathrm{\text{−}}{D}^{*}N$ ($\overline{B}N\mathrm{\text{−}}{\overline{B}}^{*}N$) mixing induced by the one boson exchange potential including the tensor force. We find many bound and resonant states with $J^P=1/2^{\pm }$, $3/2^{\pm }$, $5/2^{\pm }$, and $7/2^{-}$ in isospin singlet channels, while we find only a few resonant states with $J^P=1/2^{-}$ in isospin triplet channels. The analysis of $DN$ and $D^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) molecules will be useful to study mass spectra of excited charmed (bottom) baryons with large angular momenta, when their masses are close to the $DN$ and $D^{*}N$ ($\overline{B}N$ and ${\overline{B}}^{*}N$) thresholds.

We present a determination of the $b$-quark mass accurate through $\mathcal{O}({\alpha }_s^2)$ in perturbation theory and including partial contributions at $\mathcal{O}({\alpha }_s^3)$. Nonperturbative input comes from the calculation of the ${\rm Y}$ and $B_s$ energies in lattice QCD, including the effect of $u$, $d$ and $s$ sea quarks. We use an improved NRQCD action for the $b$ quark. This is combined with the heavy quark energy shift in NRQCD determined using a mixed approach of high-$\beta$ simulation and automated lattice perturbation theory. Comparison with experiment enables the quark mass to be extracted: in the $\overline{\mathrm{MS}}$ scheme we find ${\overline{m}}_b({\overline{m}}_b)=4.166(43)\mathrm{GeV}$.

The physical meaning of the vorticity of the matter content in Gödel spacetime is analyzed in some detail. As we shall see, unlike the situation in general stationary axially symmetric spacetimes (Lewis-Papapetrou), the vorticity in Gödel spacetime is not associated to a circular flow of superenergy on the plane orthogonal to the vorticity vector. This fact might be at the origin of the strange behavior of gyroscopes in such spacetime. The analysis emerging from the tilted version of Gödel spacetime supports further this point of view. In order to tell apart the two situations (with and without circular flow of superenergy), we introduce two different definitions of vorticity, related to the presence (absence) of such a flow.

The hedgehog ansatz for spherically symmetric spacetimes in self-gravitating nonlinear sigma models and Skyrme models is revisited and its generalization for nonspherically symmetric spacetimes is proposed. The key idea behind our construction is that, even if the matter fields depend on the Killing coordinates in a nontrivial way, the corresponding energy-momentum tensor can still be compatible with spacetime symmetries. Our generalized hedgehog ansatz reduces the Skyrme equations to coupled differential equations for two scalar fields together with several constraint equations between them. Some particular field configurations satisfying those constraints are presented in several physically important spacetimes, including stationary and axisymmetric spacetimes. Incidentally, new exact solutions are obtained under the standard hedgehog ansatz, one of which represents a global monopole inside a black hole with the Skyrme effect.

As established in a prior work of the author, the linear simplicity constraints used in the construction of the so-called “new” spin-foam models mix three of the five sectors of Plebanski theory as well as two dynamical orientations, and this is the reason for multiple terms in the asymptotics of the Engle-Pereira-Rovelli-Livine vertex amplitude as calculated by Barrett et al. Specifically, the term equal to the usual exponential of $i$ times the Regge action corresponds to configurations either in sector ($\mathrm{II}+$) with positive orientation or sector ($\mathrm{II}-$) with negative orientation. The presence of the other terms beyond this cause problems in the semiclassical limit of the spin-foam model when considering multiple 4-simplices due to the fact that the different terms for different 4-simplices mix in the semiclassical limit, leading in general to a non-Regge action and hence non-Regge and nongravitational configurations persisting in the semiclassical limit. To correct this problem, we propose to modify the vertex so its asymptotics include only the one term of the form $e^{i{S}_{\mathrm{Regge}}}$. To do this, an explicit classical discrete condition is derived that isolates the desired gravitational sector corresponding to this one term. This condition is quantized and used to modify the vertex amplitude, yielding what we call the “proper Engle-Pereira-Rovelli-Livine vertex amplitude.” This vertex still depends only on standard $SU(2)$ spin-network data on the boundary, is $SU(2)$ gauge-invariant, and is linear in the boundary state, as required. In addition, the asymptotics now consist in the single desired term of the form $e^{i{S}_{\mathrm{Regge}}}$, and all degenerate configurations are exponentially suppressed. A natural generalization to the Lorentzian signature is also presented.

We investigate the contributions of quantum fields to black hole entropy by using a cutoff scale at which the theory is described with a Wilsonian effective action. For both free and interacting fields, the total black hole entropy can be partitioned into a contribution derived from the gravitational effective action and a contribution from quantum fluctuations below the cutoff scale. In general, the latter includes a quantum contribution to the Noether charge. We analyze whether it is appropriate to identify the rest with horizon entanglement entropy, and find several complications for this interpretation, which are especially problematic for interacting fields.

The ghost-free theory of massive gravity has exact solutions where the effective stress energy generated by the graviton mass term is a cosmological constant for any isotropic metric. Since they are exact, these solutions mimic a cosmological constant in the presence of any matter-induced isotropic metric perturbation. In the Stückelberg formulation, this stress energy is carried entirely by the spatial Stückelberg field. We show that any stress energy carried by fluctuations in the spatial field away from the exact solution always decays away in an expanding universe. However, the dynamics of the spatial Stückelberg field perturbation depend on the background temporal Stückelberg field, which is equivalent to the unitary gauge time coordinate. This dependence resolves an apparent conflict in the existing literature by showing that there is a special unitary time choice for which the field dynamics and energy density perturbations vanish identically. In general, the isotropic system has a single dynamical degree of freedom requiring two sets of initial data; however, only one of these initial data choices will affect the observable metric. Finally, we construct cosmological solutions with a well-defined perturbative initial value formulation and comment on alternate solutions that evolve to singularities.

We propose the use of modulated spectra of astronomical sources due to gravitational lensing to probe Ellis wormholes. The modulation factor due to gravitational lensing by the Ellis wormhole is calculated. Within the geometrical optics approximation, the normal point-mass lens and the Ellis wormhole are indistinguishable unless we know the source’s unlensed luminosity. This degeneracy is resolved with the significant wave effect in the low-frequency domain if we take the deviation from the geometrical optics into account. We can roughly estimate the upper bound for the number density of Ellis wormholes as $n\lesssim 4\times {10}^{-10}{\mathrm{AU}}^{-3}$ with throat radius $a\sim 1\mathrm{cm}$ from the existing femtolensing analysis for compact objects.

Using a numerical simulation of the classical dynamics of the plane wave and flat space matrix models of M theory, we study the thermalization, equilibrium thermodynamics, and fluctuations of these models as we vary the temperature and the size of the matrices, $N$. We present our numerical implementation in detail and several checks of its precision and consistency. We show evidence for thermalization by matching the time-averaged distributions of the matrix eigenvalues to the distributions of the appropriate traceless Gaussian unitary ensemble of random matrices. We study the autocorrelations and power spectra for various fluctuating observables and observe evidence of the expected chaotic dynamics as well as a hydrodynamic type limit at large $N$, including near-equilibrium dissipation processes. These configurations are holographically dual to black holes in the dual string theory or M theory, and we discuss how our results could be related to the corresponding supergravity black hole solutions.

Charged-particle motion in the spacetime of a weakly magnetized static nonrotating black hole is investigated. We study the conditions under which a charged particle originally revolving around the black hole in a circular orbit after being kicked by another particle or photon can escape to infinity. The escape velocity for particles at the innermost stable circular orbits is determined and the properties of particles moving with near-critical velocity are discussed. We show that in a general case such motion is chaotic.

We consider the evolution of primordial magnetic fields generated during cosmological, electroweak, or QCD phase transitions. We assume that the magnetic field generation can be described as an injection of magnetic energy to cosmological plasma at a given scale determined by the moment of magnetic field generation. A high Reynolds number ensures strong coupling between the magnetic field and fluid motions. The subsequent evolution of the magnetic field is governed by decaying hydromagnetic turbulence. Both our numerical simulations and a phenomenological description allow us to recover “universal” laws for the decay of magnetic energy and the growth of magnetic correlation length in the turbulent (low-viscosity) regime. In particular, we show that during the radiation-dominated epoch, the energy and correlation length of nonhelical magnetic fields scale as conformal time to the powers $-1/2$ and $+1/2$, respectively. For helical magnetic fields, the energy and correlation length scale as conformal time to the powers $-1/3$ and $+2/3$, respectively. The universal decay law of the magnetic field implies that the strength of the magnetic field generated during the QCD phase transition could reach $\sim {10}^{-9}\mathrm{G}$ with the present-day correlation length $\sim 50\mathrm{kpc}$. The fields generated at the electroweak phase transition could be as strong as $\sim {10}^{-10}\mathrm{G}$ with correlation lengths reaching $\sim 0.3\mathrm{kpc}$. These values of the magnetic fields are consistent with the lower bounds of the extragalactic magnetic fields.

We model the space-time of low-mass x-ray binaries with the Tomimatsu-Sato $\delta =2$ metric and study the properties of the orbital and the epicyclic frequencies. The numerical analysis shows that the properties of the characteristic frequencies of oscillation do not differ qualitatively from those of the Kerr black hole. Estimates for the angular momenta of the three stellar mass black hole candidates GRO $1655-40$, XTE $1550-564$, and GRS $1915+105$ are made with the application of the nonlinear resonance model. We find agreement between the predictions based on the $3:2$ nonlinear resonance model for a Tomimatsu-Sato $\delta =2$ background and the current estimates found in the literature.