We conduct a descriptive analysis of the multipolar structure of gravitational-radiation waveforms from equal-mass aligned-spin mergers, following an approach first presented in the complementary context of nonspinning black holes of varying mass ratio [J. G. Baker et al., Phys. Rev. D 78, 044046 (2008).]. We find that, as with the nonspinning mergers, the dominant waveform mode phases evolve together in lock-step through inspiral and merger, supporting the previous waveform description in terms of an adiabatically rigid rotator driving gravitational-wave emission—an implicit rotating source. We further apply the late-time merger-ringdown model for the rotational frequency introduced in [J. G. Baker et al., Phys. Rev. D 78, 044046 (2008).], along with an improved amplitude model appropriate for the dominant (2, $\pm 2$) modes. This provides a quantitative description of the merger-ringdown waveforms, and suggests that the major features of these waveforms can be described with reference only to the intrinsic parameters associated with the state of the final black hole formed in the merger. We provide an explicit model for the merger-ringdown radiation, and demonstrate that this model agrees to fitting factors better than 95% with the original numerical waveforms for system masses above $\sim 150M_{\odot }$. This model may be directly applicable to gravitational-wave detection of intermediate-mass black-hole mergers.

We study the stability of static, hyperbolic Gauss-Bonnet black holes in ($4+1$)-dimensional anti-de Sitter (AdS) space-time against the formation of scalar hair. Close to extremality the black holes possess a near-horizon topology of ${\mathrm{AdS}}_2\times H^3$ such that within a certain range of the scalar field mass one would expect that they become unstable to the condensation of an uncharged scalar field. We confirm this numerically and observe that there exists a family of hairy black hole solutions labeled by the number of nodes of the scalar field function. We construct explicit examples of solutions with a scalar field that possesses zero nodes, one node, and two nodes, respectively, and show that the solutions with nodes persist in the limit of Einstein gravity, i.e. for vanishing Gauss-Bonnet coupling. We observe that the interval of the mass for which scalar field condensation appears decreases with increasing Gauss-Bonnet coupling and/or with increasing node number.

The thermal and expansion history of the Universe before big bang nucleosynthesis is unknown. We investigate the evolution of cosmological perturbations through the transition from an early matter era to radiation domination. We treat reheating as the perturbative decay of an oscillating scalar field into relativistic plasma and cold dark matter. After reheating, we find that subhorizon perturbations in the decay-produced dark matter density are significantly enhanced, while subhorizon radiation perturbations are instead suppressed. If dark matter originates in the radiation bath after reheating, this suppression may be the primary cutoff in the matter power spectrum. Conversely, for dark matter produced nonthermally from scalar decay, enhanced perturbations can drive structure formation during the cosmic dark ages and dramatically increase the abundance of compact substructures. For low reheat temperatures, we find that as much as 50% of all dark matter is in microhalos with $M\gtrsim 0.1M_{\oplus }$ at $z\simeq 100$, compared to a fraction of $\sim {10}^{-10}$ in the standard case. In this scenario, ultradense substructures may constitute a large fraction of dark matter in galaxies today.

We describe the meson-meson data for the ($I{J}^{PC}={00}^{++}$) wave at $280\le \sqrt{s}\le 1900\mathrm{MeV}$ in two approaches: (i) the $K$-matrix approach and (ii) the dispersion relation $D$-matrix method. With a good description of low-energy data (at $280\le \sqrt{s}\le 900\mathrm{MeV}$) as well as the data of two-meson transition amplitudes and antiproton-proton annihilation into three pseudoscalar meson states (at $450\le \sqrt{s}\le 1950\mathrm{MeV}$) we have found the positions of the resonance poles: (i) for the $\sigma$ meson pole: $M_{\sigma }=(390\pm 35)-i(235\pm 50)\mathrm{MeV}$; (ii) two poles for the $f_0(980)$, on the second sheet (under the $\pi \pi$ cut): $M_I=(1011\pm 5)-i(35\pm 5)\mathrm{MeV}$, and on the third sheet (under the $\pi \pi$ and $K\overline{K}$ cuts), $M_{II}=(1035\pm 50)-i(460\pm 50)\mathrm{MeV}$; for the $f_0(1370)$ meson, $M=(1285\pm 30)-i(160\pm 20)\mathrm{MeV}$; for the $f_0(1500)$ meson, $M=(1488\pm 4)-i(53\pm 5)\mathrm{MeV}$; for the $f_0(1790)$ meson, $M=(1775\pm 25)-i(140\pm 15)\mathrm{MeV}$; and for the broad state $f_0(1200–1600)$ $M=(1540\pm 120)-i(550\pm 70)\mathrm{MeV}$. Our estimation of the scalar-isoscalar scattering length obtained under different parameterizations and assumptions about the quality of low-energy $\pi \pi$ scattering data is $a_0^0=(0.215\pm 0.040)m_{\pi }^{-1}$. We also discuss the idea according to which the $\sigma$ meson could be a remnant of the confinement singularity, $1/s^2$, in a white channel.

We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with $p$-wave annihilation, for which the relative-velocity-weighted annihilation cross section is $\sigma v=a+b{v}^2$. We determine that this significantly increases the gamma-ray power if $b/a\gtrsim {10}^6$. The effect of $p$-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given $b/a$ is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong $p$-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly $p$-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong $p$ wave were to be observed, it would likely indicate nonthermal production of dark matter in the early Universe.

We compute the matrix elements of the electromagnetic operator $\overline{s}{F}_{\mu \nu }{\sigma }^{\mu \nu }d$ between kaon and pion states, using lattice QCD with maximally twisted-mass fermions and two flavors of dynamical quarks ($N_f=2$). The operator is renormalized nonperturbatively in the RI’/MOM scheme and our simulations cover pion masses as light as 270 MeV and three values of the lattice spacing from $\simeq 0.07$ up to $\simeq 0.1\mathrm{fm}$. At the physical point our result for the corresponding tensor form factor at zero-momentum transfer is $f_T^{K\pi }(0)=0.417({14}_{\mathrm{stat}})(5_{\mathrm{syst}})$, where the systematic error does not include the effect of quenching the strange and charm quarks. Our result differs significantly from the old quenched result $f_T^{K\pi }(0)=0.78(6)$ obtained by the ${\mathrm{SPQ}}_{\mathrm{cd}}\mathrm{R}$ Collaboration with pion masses above 500 MeV. We investigate the source of this difference and conclude that it is mainly related to the chiral extrapolation. We also study the tensor charge of the pion and obtain the value $f_T^{\pi \pi }(0)=0.195(8_{\mathrm{stat}})(6_{\mathrm{syst}})$ in good agreement with, but more accurate than the result $f_T^{\pi \pi }(0)=0.216(34)$ obtained by the QCDSF Collaboration using higher pion masses.

We perform a comprehensive analysis of target mass corrections to spin-averaged structure functions and asymmetries at next-to-leading order. Several different prescriptions for target mass corrections are considered, including the operator product expansion, and various approximations to it, collinear factorization, and $\xi$-scaling. We assess the impact of each of these on a number of observables, such as the neutron to proton $F_2$ structure function ratio, and parity-violating electron scattering asymmetries for protons and deuterons which are sensitive to $\gamma Z$ interference effects. The corrections from higher order radiative and nuclear effects on the parity-violating deuteron asymmetry are also quantified.

This article discusses the occurrence of one-loop amplitudes within a next-to-next-to-leading-order calculation. In a next-to-next-to-leading-order calculation, the one-loop amplitude enters squared and one would therefore naively expect that the $\mathcal{O}(\epsilon )$- and $\mathcal{O}({\epsilon }^2)$-terms of the one-loop amplitudes are required. I show that the calculation of these terms can be avoided if a method is known, which computes the $\mathcal{O}({\epsilon }^0)$-terms of the finite remainder function of the two-loop amplitude.

We discuss how ${\theta }_{13}\ne 0$ is accommodated in a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry $T_7$ in the context of a supersymmetric extension of the standard model with gauged $U(1{)}_{B-L}$. We predict a correlation between ${\theta }_{13}$ and ${\theta }_{23}$, as well as the effective neutrino mass $m_{ee}$ in neutrinoless double beta decay.

The light pseudoscalar particle, dubbed the axion, borne out of the Peccei-Quinn solution to the strong $CP$ problem in QCD remains elusive. One avenue of inferring its existence is through its coupling to electromagnetic radiation. So far, laboratory experiments have dedicated all efforts to detect the axion in the mass range ${10}^{-6}<m_a<{10}^{-3}\mathrm{eV}$ with a photon-axion coupling strength $g_{a\gamma \gamma }<{10}^{-10}{\mathrm{GeV}}^{-1}$, where the limits are derived from astrophysical considerations. In this study, we present a novel way of constraining $g_{a\gamma \gamma }$ by looking at the level of linear polarization in the radiation emerging from magnetic white dwarfs. We find that photon-axion oscillations in white dwarf magnetospheres can enhance the degree of linear polarization. Observing that most magnetic white dwarfs show only 5% linear polarization, we derive upper limits on $g_{a\gamma \gamma }$ for different axion masses.

The recent formulation of the relativistic Thomas-Fermi model within the Feynman-Metropolis-Teller theory for compressed atoms is applied to the study of general relativistic white dwarf equilibrium configurations. The equation of state, which takes into account the $\beta$-equilibrium, the nuclear and the Coulomb interactions between the nuclei and the surrounding electrons, is obtained as a function of the compression by considering each atom constrained in a Wigner-Seitz cell. The contribution of quantum statistics, weak, nuclear, and electromagnetic interactions is obtained by the determination of the chemical potential of the Wigner-Seitz cell. The further contribution of the general relativistic equilibrium of white dwarf matter is expressed by the simple formula $\sqrt{g_{00}}{\mu }_{\mathrm{ws}}=\mathrm{\text{constant}}$, which links the chemical potential of the Wigner-Seitz cell ${\mu }_{\mathrm{ws}}$ with the general relativistic gravitational potential $g_{00}$ at each point of the configuration. The configuration outside each Wigner-Seitz cell is strictly neutral and therefore no global electric field is necessary to warranty the equilibrium of the white dwarf. These equations modify the ones used by Chandrasekhar by taking into due account the Coulomb interaction between the nuclei and the electrons as well as inverse $\beta$ decay. They also generalize the work of Salpeter by considering a unified self-consistent approach to the Coulomb interaction in each Wigner-Seitz cell. The consequences on the numerical value of the Chandrasekhar-Landau mass limit as well as on the mass-radius relation of ${}^4\mathrm{He}$, ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$ and ${}^{56}\mathrm{Fe}$ white dwarfs are presented. All these effects should be taken into account in processes requiring a precision knowledge of the white dwarf parameters.

In this paper, we discuss massive gravity in Minkowski space via the gravitational Higgs mechanism, which provides a nonperturbative definition thereof. Using this nonperturbative definition, we address the issue of unitarity by studying the full nonlinear Hamiltonian for the relevant metric degrees of freedom. While perturbatively unitarity is not evident, we argue that no negative norm state is present in the full nonlinear theory.

Gravitational-wave searches for the merger of compact binaries use matched filtering as the method of detecting signals and estimating parameters. Such searches construct a fine mesh of filters covering a signal parameter space at high density. Previously it has been shown that singular-value decomposition can reduce the effective number of filters required to search the data. Here we study how the basis provided by the singular-value decomposition changes dimension as a function of template-bank density. We will demonstrate that it is sufficient to use the basis provided by the singular-value decomposition of a low-density bank to accurately reconstruct arbitrary points within the boundaries of the template bank. Since this technique is purely numerical, it may have applications to interpolating the space of numerical relativity waveforms.

Astrophysical fluids may acquire nonzero electrical charge because of strong irradiation or charge separation in a magnetic field. In this case, electromagnetic and gravitational forces may act together and produce new equilibrium configurations, which are different from the uncharged ones. Following our previous studies of charged test particles and uncharged perfect fluid tori encircling compact objects, we introduce here a simple test model of a charged perfect fluid torus in strong gravitational and electromagnetic fields. In contrast to ideal magnetohydrodynamic models, we consider here the opposite limit of negligible conductivity, where the charges are tied completely to the moving matter. This is an extreme limiting case which can provide a useful reference against which to compare subsequent more complicated astrophysically motivated calculations. To clearly demonstrate the features of our model, we construct three-dimensional axisymmetric charged toroidal configurations around Reissner-Nordström black holes and compare them with equivalent configurations of electrically neutral tori.

We consider theories which explain the flatness of the power spectrum of scalar perturbations in the Universe by conformal invariance, such as conformal rolling model and Galilean Genesis. We show that to the leading nonlinear order, perturbations in all models from this class behave in one and the same way, at least if the energy density of the relevant fields is small compared to the total energy density (spectator approximation). We then turn to the intrinsic non-Gaussianities in these models (as opposed to non-Gaussianities that may be generated during subsequent evolution). The intrinsic bispectrum vanishes, so we perform the complete calculation of the trispectrum and compare it with the trispectra of local forms in various limits. The most peculiar feature of our trispectrum is a (fairly mild) singularity in the limit where two momenta are equal in absolute value and opposite in direction (folded limit). Generically, the intrinsic non-Gaussianity can be of detectable size.

We present three-dimensional numerical simulations of turbulent combustion converting a neutron star into a quark star. Hadronic matter, described by a microphysical finite-temperature equation of state, is converted into strange quark matter. We assume this phase, represented by a bag-model equation of state, to be absolutely stable. Following the example of thermonuclear burning in white dwarfs leading to type Ia supernovae, we treat the conversion process as a potentially turbulent deflagration. Solving the nonrelativistic Euler equations using established numerical methods we conduct large eddy simulations including an elaborate subgrid scale model, while the propagation of the conversion front is modeled with a level-set method. Our results show that for large parts of the parameter space the conversion becomes turbulent and therefore significantly faster than in the laminar case. Despite assuming absolutely stable strange quark matter, in our hydrodynamic approximation an outer layer remains in the hadronic phase, because the conversion front stops when it reaches conditions under which the combustion is no longer exothermic.

A class of neutrino mass matrices with texture zeros realizable using the group $Z_3$ within the framework of type (I+II) seesaw mechanism naturally admits a nonzero ${\theta }_{13}$, and allows for deviations from maximal mixing. The phenomenology of this model is reexamined in the light of recent hints for nonzero ${\theta }_{13}$.

The properties of the thermal Abelian monopoles are studied in the deconfinement phase of the $SU(2)$ gluodynamics. To remove effects of Gribov copies, the simulated annealing algorithm is applied to fix the maximally Abelian gauge. To study the monopole profile, we complete the first computations of excess of the nonabelian action density as a function of the distance from the center of the thermal Abelian monopole. We have found that, starting from distances of around two lattice spacings, the chromoelectric and chromomagnetic action densities created by the monopole are equal to each other, from which we conclude that the monopole is a dyon. Furthermore, we find that the chromoelectric and chromomagnetic fields decrease exponentially with increasing distance. These findings were confirmed for different temperatures in the range $T/T_c\in (1.5,4.8)$.

We extract the running coupling based on Creutz ratios in SU(2) lattice gauge theory with two Dirac fermions in the adjoint representation. Depending on how the extrapolation to zero fermion mass is performed, either backward running or an absence of running is observed at strong bare coupling. This behavior is consistent with other findings which indicate that this theory has an infrared fixed point.

Considering the defects of the previous work for estimating the anomalous production rates of $e^{+}{e}^{-}\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$, ${\rm Y}(2S){\pi }^{+}{\pi }^{-}$ near the peak of the ${\rm Y}(5S)$ resonance at $\sqrt{s}=10.87\mathrm{GeV}$ [K. F. Chen et al. (Belle Collaboration), Phys. Rev. Lett. 100, 112001 (2008)], we suggest a new scenario where the contributions from the direct dipion transition and the final-state interactions interfere to result in not only the anomalously large production rates, but also line shapes of the differential widths consistent with experimental measurement when assuming the reactions are due to the dipion emission of ${\rm Y}(5S)$. At the end, we raise a new puzzle that the predicted differential width $d\Gamma ({\rm Y}(5S)\to {\rm Y}(2S){\pi }^{+}{\pi }^{-})/d\cos \theta$ has a discrepant trend from the data while other predictions are well in accord with the data. It should be further clarified by more accurate measurements carried by future experiments.