Initial data for evolving black-hole binaries can be constructed via many techniques, and can represent a wide range of physical scenarios. However, because of the way that different schemes parametrize the physical aspects of a configuration, it is not always clear what a given set of initial data actually represents. This is especially important for quasiequilibrium data constructed using the conformal thin-sandwich approach. Most initial-data studies have focused on identifying data sets that represent binaries in quasicircular orbits. In this paper, we consider initial-data sets representing equal-mass black-hole binaries in eccentric orbits. We will show that effective-potential techniques can be used to calibrate initial data for black-hole binaries in eccentric orbits. We will also examine several different approaches, including post-Newtonian diagnostics, for measuring the eccentricity of an orbit. Finally, we propose the use of the “Komar-mass difference” as a useful, invariant means of parametrizing the eccentricity of relativistic orbits.

We present our numerical comparisons between the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation widely used in numerical relativity today and its adjusted versions using constraints. We performed three test beds: gauge-wave, linear wave, and Gowdy-wave tests, proposed by the Mexico workshop on the formulation problem of the Einstein equations. We tried three kinds of adjustments, which were previously proposed from the analysis of the constraint propagation equations, and investigated how they improve the accuracy and stability of evolutions. We observed that the signature of the proposed Lagrange multipliers are always right and the adjustments improve the convergence and stability of the simulations. When the original BSSN system already shows satisfactory good evolutions (e.g., linear wave test), the adjusted versions also coincide with those evolutions, while in some cases (e.g., gauge-wave or Gowdy-wave tests) the simulations using the adjusted systems last 10 times as long as those using the original BSSN equations. Our demonstrations imply a potential to construct a robust evolution system against constraint violations even in highly dynamical situations.

Recent numerical studies indicate that uncertainties in the treatment of baryonic physics can affect predictions for weak lensing shear power spectra at a level that is significant for several forthcoming surveys such as the Dark Energy Survey, the SuperNova/Acceleration Probe, and the Large Synoptic Survey Telescope. Correspondingly, we show that baryonic effects can significantly bias dark energy parameter measurements. Elimination of such potential biases by neglecting information in multipoles beyond several hundred leads to weaker parameter constraints by a factor of $\sim 2–3$ compared with using information out to multipoles of several thousand. Fortunately, the same numerical studies that explore the influence of baryons indicate that they primarily affect power spectra by altering halo structure through the relation between halo mass and mean effective halo concentration. We explore the ability of future weak lensing surveys to constrain both the internal structures of halos and the properties of the dark energy simultaneously as a first step toward self calibrating for the physics of baryons. In this approach, parameter biases are greatly reduced and no parameter constraint is degraded by more than $\sim 40\%$ in the case of the Large Synoptic Survey Telescope or 30% in the cases of the SuperNova/Acceleration Probe or the Dark Energy Survey. Modest prior knowledge of the halo concentration relation and its redshift evolution greatly improves even these forecasts. In addition, we find that these surveys can constrain effective halo concentrations themselves usefully with shear power spectra alone. In the most restrictive case of a power-law relation for halo concentration as a function of mass and redshift, the concentrations of halos of mass $m\sim {10}^{14}{h}^{-1}{\mathrm{M}}_{\odot }$ at $z\sim 0.2$ can be constrained to better than 10%. Our results suggest that inferring dark energy parameters through shear spectra can be made robust to baryonic physics and that this procedure may even provide useful constraints on galaxy formation models.

Strangelets arriving from the interstellar medium are an interesting target for experiments searching for evidence of this hypothetical state of hadronic matter. We entertain the possibility of a trapped strangelet population, quite analogous to ordinary nuclei and electron belts. For a population of strangelets to be trapped by the geomagnetic field, these incoming particles would have to fulfill certain conditions, namely, having magnetic rigidities above the geomagnetic cutoff and below a certain threshold for adiabatic motion to hold. We show in this work that, for fully ionized strangelets, there is a narrow window for stable trapping. An estimate of the stationary population is presented and the dominant loss mechanisms discussed. It is shown that the population would be substantially enhanced with respect to the interstellar medium flux (up to 2 orders of magnitude) due to quasistable trapping.

In this paper we study the properties of diquarks (composed of $u$ and/or $d$ quarks) in the Bethe-Salpeter (BS) formalism under the covariant instantaneous approximation. We calculate their BS wave functions and study their effective interaction with the pion. Using the effective coupling constant among the diquarks and the pion, in the heavy quark limit $m_Q\to \infty$, we calculate the decay widths of ${\Sigma }_Q^{(*)}$ ($Q=c$, $b$) in the BS formalism under the covariant instantaneous approximation and then give predictions of the decay widths $\Gamma ({\Sigma }_b^{(*)}\to {\Lambda }_b+\pi )$.

We present detailed analyses of the vacuum structure of the scalar potential in a supersymmetric mass varying neutrinos model. The observed dark energy density is identified with false vacuum energy and the dark energy scale of order $({10}^{-3}\mathrm{eV}{)}^4$ is understood by the gravitationally suppressed supersymmetry breaking scale, $F(\mathrm{TeV}{)}^2/M_{\mathrm{Pl}}$, in the model. The vacuum expectation values of sneutrinos should be tiny in order that the model works. Some decay processes of superparticles into an acceleron and sterile neutrino are also discussed in the model.

We consider decay processes of scalar-field condensation in the framework of well-established quantum field theory. We postulate that the quantum state corresponding to the scalar-field condensation is the so-called coherent state with discussing the validity of such a treatment. We show that, by using the unitarity relation of the scattering matrix, the decay rate of the coherent state is systematically calculated. We apply our procedure to derive explicit formulas of decay rates for two cases: (i) we study the case where the scalar condensation decays into a pair of scalar particles and show that our formalism reproduces the results obtained from the parametric-resonance analysis, and (ii) we also calculate the decay rate when the coherent state decays via anomaly.

Based on the permutation group formalism, we present a discrete symmetry algebra in QCD. The discrete algebra is hidden symmetry in QCD, which is manifest only on a space-manifold with nontrivial topology. Quark confinement in the presence of dynamical quarks is discussed in terms of the discrete symmetry algebra. It is shown that the quark deconfinement phase has ground-state degeneracy depending on the topology of the space, which gives a gauge-invariant distinction between the confinement and deconfinement phases. We also point out that new quantum numbers relating to the fractional quantum Hall effect exist in the deconfinement phase.

We consider orientifold field theories [i.e., $\mathrm{SU}(N)$ Yang-Mills theories with fermions in the two-index symmetric or antisymmetric representations] on $R_3\times S_1$ where the compact dimension can be either temporal or spatial. These theories are planar equivalent to supersymmetric Yang-Mills theory. The latter has $Z_N$ center symmetry. The famous Polyakov criterion establishing confinement-deconfinement phase transition as that from $Z_N$ symmetric to $Z_N$ broken phase applies. At the Lagrangian level the orientifold theories have at most a $Z_2$ center. We discuss how the full $Z_N$ center symmetry dynamically emerges in the orientifold theories in the limit $N\to \infty$. In the confining phase the manifestation of this enhancement is the existence of stable $k$ strings in the large-$N$ limit of the orientifold theories. These strings are identical to those of supersymmetric Yang-Mills theories. We argue that critical temperatures (and other features) of the confinement-deconfinement phase transition are the same in the orientifold daughters and their supersymmetric parent up to $1/N$ corrections. We also discuss the Abelian and non-Abelian confining regimes of four-dimensional QCD-like theories.

Creation of scalar massless particles in two-dimensional Minkowski space-time—as predicted by the dynamical Casimir effect—is studied for the case of a semitransparent mirror initially at rest, then accelerating for some finite time, along a trajectory that simulates a black hole collapse (defined by Walker and Carlitz and Willey), and finally moving with constant velocity. When the reflection and transmission coefficients are those in the model proposed by Barton, Calogeracos, and Nicolaevici [$r(\omega )=-i\alpha /(\omega +i\alpha )$ and $s(\omega )=\omega /(\omega +i\alpha )$, with $\alpha \ge 0$], the Bogoliubov coefficients on the backside of the mirror can be computed exactly. This allows us to prove that, when $\alpha$ is very large (as in the case of an ideal, perfectly reflecting mirror) a thermal emission of scalar massless particles obeying Bose-Einstein statistics is radiated from the mirror (a blackbody radiation), in accordance with results previously obtained in the literature. However, when $\alpha$ is finite (semitransparent mirror, a physically realistic situation) the striking result is obtained that the thermal emission of scalar massless particles obeys Fermi-Dirac statistics. We also show here that the reverse change of statistics takes place in a bidimensional fermionic model for massless particles, namely, that the Fermi-Dirac statistics for the completely reflecting situation will turn into the Bose-Einstein statistics for a partially reflecting, physical mirror.

For logarithmically divergent one-loop lattice Feynman integrals $I(p,a)$, subject to mild general conditions, we prove the following expected and crucial structural result: $I(p,a)=f(p)\log (aM)+g(p)+h(p,M)$ up to terms which vanish for lattice spacing $a\to 0$. Here $p$ denotes collectively the external momenta and $M$ is a mass scale which may be chosen arbitrarily. The $f(p)$ and $h(p,M)$ are shown to be universal and coincide with analogous quantities in the corresponding continuum integral when the latter is regularized either by momentum cutoff or dimensional regularization. The nonuniversal term $g(p)$ is shown to be a homogeneous polynomial in $p$ of the same degree as $f(p)$. This structure is essential for consistency between renormalized lattice and continuum formulations of QCD at one loop.

An analysis of some modified-gravity models, based on the study of pure Schwarzschild and of Schwarzschild–de Sitter black holes, and involving the use of the Noether charge method, is carried out. Corrections to the classical Einsteinian black hole entropy appear. It is shown explicitly how the condition of positive entropy can be used in order to constrain the viability of modified-gravity theories.

When we calculate gravitational waveforms from extreme-mass-ratio inspirals by metric perturbation, it is a common strategy to use the adiabatic approximation. Under that approximation, we first calculate the linear metric perturbation induced by geodesics orbiting a black hole, then we calculate the adiabatic evolution of the parameters of geodesics due to the radiation reaction effect through the calculation of the self-force. This procedure is considered to be reasonable, however, there is no direct proof that it can actually produce the correct waveform we would observe. In this paper, we study the formal expression of the second order metric perturbation and show that it can be expressed as the linear metric perturbation modulated by the adiabatic evolution of the geodesic. This evidence supports the assumption that the adiabatic approximation can produce the correct waveform, and that the adiabatic expansion we propose in Ref. [Y. Mino, Y. MinoY. Mino and R. PriceProg. Theor. Phys. 115, 43 (2006); Prog. Theor. Phys.113, 733 (2005); (unpublished).] is an appropriate perturbation expansion for studying the radiation reaction effect on the gravitational waveform.

Estimates of inflationary parameters from the CMB $B$-mode polarization spectrum on the largest scales depend on knowledge of the reionization history, especially at low tensor-to-scalar ratio. Assuming an incorrect reionization history in the analysis of such polarization data can strongly bias the inflationary parameters. One consequence is that the single-field slow-roll consistency relation between the tensor-to-scalar ratio and tensor tilt might be excluded with high significance even if this relation holds in reality. We explain the origin of the bias and present case studies with various tensor amplitudes and noise characteristics. A more model-independent approach can account for uncertainties about reionization, and we show that parametrizing the reionization history by a set of its principal components with respect to $E$-mode polarization removes the bias in inflationary parameter measurement with little degradation in precision.

We discuss cosmic microwave background constraints on the causal set theory of quantum gravity, which has made testable predictions about the nature of dark energy. We flesh out previously discussed heuristic constraints by showing how the power spectrum of causal set dark energy fluctuations can be found from the overlap volumes of past light cones of points in the universe. Using a modified Boltzmann code we put constraints on the single parameter of the theory that are somewhat stronger than previous ones. We conclude that causal set theory cannot explain late-time acceleration without radical alterations to general relativity.

We study the generation of primeval magnetic fields during inflation era in nonlinear theories of electrodynamics. Although the intensity of the produced fields strongly depends on characteristics of inflation and on the form of electromagnetic Lagrangian, our results do not exclude the possibility that these fields could be astrophysically interesting.

We analyze the effect of flavor changing neutral currents within 331 models. In particular, we concentrate on the so-called economical models, which have a minimal scalar sector. Taking into account the experimental measurements of observables related to neutral $K$ and $B$ meson mixing, we study the resulting bounds for angles and phases in the mixing matrix for the down quark sector, and the mass and mixing parameters related to the new $Z^{\prime }$ gauge boson.

Abelian mechanism of non-Abelian color confinement is observed in a gauge-independent way by high precision lattice Monte Carlo simulations in gluodynamics. An Abelian gauge field is extracted with no gauge fixing. Then we decompose the Abelian field into regular photon and singular monopole parts using the Hodge decomposition. We find that only the monopole part is responsible for the string tension. The investigation of the flux-tube profile then shows that an Abelian electric field defined in an arbitrary color direction is squeezed by the monopole supercurrent with the same color direction, and the quantitative features of flux squeezing are consistent with those observed previously after Abelian projections with gauge fixing. Non-Abelian color confinement is explained in the framework of the gauge-independent Abelian dual Meissner effect.

We consider a model of neutrino oscillations with three additional sterile neutrinos and a gauged $B\mathrm{\text{−}}L$ interaction. We find allowed values of the model parameters which can reconcile the results of the evidence for ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_e$ conversion seen at the LSND neutrino oscillation experiment with the null results of the MiniBooNE experiment. A portion of the low energy excess of ${\nu }_e$ events seen at MiniBooNE can arise naturally, and we make a quantitative prediction for the forthcoming antineutrino oscillation results at MiniBooNE.