Gravitational waves emitted by binary systems in the inspiral phase carry a complicated structure, consisting in a superposition of different harmonics of the orbital frequency, the amplitude of each of them taking the form of a post-Newtonian series. In addition to that, spinning binaries experience spin-orbit and spin-spin couplings which induce a precession of the orbital angular momentum and of the individual spins. With one exception, previous analyses of the measurement accuracy of gravitational wave experiments for comparable-mass binary systems have neglected either spin-precession effects or subdominant harmonics and amplitude modulations. Here we give the first explicit description of how these effects combine to improve parameter estimation. We consider supermassive black hole binaries as expected to be observed with the planned space-based interferometer LISA, and study the measurement accuracy for several astrophysically interesting parameters obtainable taking into account the full 2PN waveform for spinning bodies, as well as spin-precession effects. We find that for binaries with a total mass in the range ${10}^5{M}_{\odot }<M<{10}^7{M}_{\odot }$ at a redshift of 1, a factor $\sim 1.5$ is in general gained in accuracy, with the notable exception of the determination of the individual masses in equal-mass systems, for which a factor $\sim 5$ can be gained. We also find, as could be expected, that using the full waveform helps increasing the upper mass limit for detection, which can be as high as $M={10}^8{M}_{\odot }$ at a redshift of 1, as well as the redshift limit where some information can be extracted from a system, which is roughly $z\gtrsim 10$ for $M\le {10}^7{M}_{\odot }$, 1.5–5 times higher than with the restricted waveform. We computed that the full waveform allows us to use supermassive black hole binaries as standard sirens up to a redshift of $z\approx 1.6$, about 0.4 larger than what previous studies allowed. We found that for lower unequal-mass binary systems, the measurement accuracy is not as drastically improved as for other systems. This suggests that for these systems, adding parameters such as eccentricity or alternative gravity parameters could be achieved without much loss in the accuracy.

We study the g-modes of fast rotating stratified neutron stars in the general relativistic Cowling approximation, where we neglect metric perturbations and where the background models take into account the buoyant force due to composition gradients. This is the first paper studying this problem in a general relativistic framework. In a recent paper [A. Passamonti, B. Haskell, N. Andersson, D. I. Jones, and I. Hawke, Mon. Not. R. Astron. Soc. 394, 730 (2009)], a similar study was performed within the Newtonian framework, where the authors presented results about the onset of CFS-unstable g-modes and the close connection between inertial and gravity modes for sufficiently high rotation rates and small composition gradients. This correlation arises from the interplay between the buoyant force which is the restoring force for g-modes and the Coriolis force which is responsible for the existence of inertial modes. In our relativistic treatment of the problem, we find an excellent qualitative agreement with respect to the Newtonian results.

We discuss the role of the proximity force approximation in deriving limits to the existence of Yukawian forces—predicted in the submillimeter range by many unification models—from Casimir force experiments using the sphere-plane geometry. Two forms of this approximation are discussed, the first used in most analyses of the residuals from the Casimir force experiments performed so far, and the second recently discussed in this context in R. Decca et al. [Phys. Rev. D 79, 124021 (2009)]. We show that the former form of the proximity force approximation overestimates the expected Yukawa force and that the relative deviation from the exact Yukawa force is of the same order of magnitude, in the realistic experimental settings, as the relative deviation expected between the exact Casimir force and the Casimir force evaluated in the proximity force approximation. This implies both a systematic shift making the actual limits to the Yukawa force weaker than claimed so far, and a degree of uncertainty in the $\alpha \mathrm{\text{−}}\lambda$ plane related to the handling of the various approximations used in the theory for both the Casimir and the Yukawa forces. We further argue that the recently discussed form for the proximity force approximation is equivalent, for a geometry made of a generic object interacting with an infinite planar slab, to the usual exact integration of any additive two-body interaction, without any need to invoke approximation schemes. If the planar slab is of finite size, an additional source of systematic error arises due to the breaking of the planar translational invariance of the system, and we finally discuss to what extent this may affect limits obtained on power-law and Yukawa forces.

Gaussianity and statistical isotropy of the Universe are modern cosmology’s minimal set of hypotheses. In this work we introduce a new statistical test to detect observational deviations from this minimal set. By defining the temperature correlation function over the whole celestial sphere, we are able to independently quantify both angular and planar dependence (modulations) of the CMB temperature power spectrum over different slices of this sphere. Given that planar dependence leads to further modulations of the usual angular power spectrum $C_{\ell }$, this test can potentially reveal richer structures in the morphology of the primordial temperature field. We have also constructed an unbiased estimator for this angular-planar power spectrum which naturally generalizes the estimator for the usual $C_{\ell }$’s. With the help of a chi-square analysis, we have used this estimator to search for observational deviations of statistical isotropy in WMAP’s 5 year release data set (ILC5), where we found only slight anomalies on the angular scales $\ell =7$ and $\ell =8$. Since this angular-planar statistic is model-independent, it is ideal to employ in searches of statistical anisotropy (e.g., contaminations from the galactic plane) and to characterize non-Gaussianities.

We investigate primordial non-Gaussianity and dark matter isocurvature fluctuations in the modulated reheating and the curvaton scenarios. In these scenarios, a large non-Gaussianity can be generated; on the other hand, depending on how dark matter is produced, too large isocurvature fluctuations can also arise, which is inconsistent with current observations. In this paper, we study this issue in a mixed scenario where the curvature fluctuations can also be produced from the inflaton fluctuations as well as those from a light scalar field such as the modulus and the curvaton. We show that primordial fluctuations can be highly non-Gaussian without conflicting with the current constraint on isocurvature fluctuations for such mixed scenarios. However, if the constraint on isocurvature fluctuations becomes severer as expected by the Planck satellite, $f_{\mathrm{NL}}$, a nonlinearity parameter for adiabatic fluctuations, should be very small as $f_{\mathrm{NL}}\lesssim 3$, which would give interesting implications for the generation mechanism of dark matter. Non-Gaussianity from isocurvature fluctuations is also discussed in these scenarios.

We consider power-law inflation with a Gauss-Bonnet correction inspired by string theory. We analyze the stability of cosmological perturbations and obtain the allowed parameter space. We find that for Gauss-Bonnet-dominated inflation ultraviolet instabilities of either scalar or tensor perturbations show up on small scales. The Gauss-Bonnet correction with a positive (or negative) coupling may lead to a reduction (or enhancement) of the tensor-to-scalar ratio in the potential-dominated case. We place tight constraints on the model parameters by making use of the WMAP 5-year data.

We examine a dark energy model where a scalar unparticle degree of freedom plays the role of quintessence. In particular, we study a model where the unparticle degree of freedom has a standard kinetic term and a simple mass potential, the evolution is slowly rolling and the field value is of the order of the unparticle energy scale (${\lambda }_u$). We study how the evolution of $w$ depends on the parameters $B$ (a function of unparticle scaling dimension $d_u$), the initial value of the field ${\varphi }_i$ (or equivalently, ${\lambda }_u$) and the present matter density ${\Omega }_{m0}$. We use observational data from type Ia supernovae, baryon acoustic oscillations and the cosmic microwave background to constrain the model parameters and find that these models are not ruled out by the observational data. From a theoretical point of view, unparticle dark energy model is very attractive, since unparticles (being bound states of fundamental fermions) are protected from radiative corrections. Further, coupling of unparticles to the standard model fields can be arbitrarily suppressed by raising the fundamental energy scale $M_F$, making the unparticle dark energy model free of most of the problems that plague conventional scalar field quintessence models.

We study stability conditions of the full Hamiltonian constraint equation describing the quantum dynamics of the diagonal Bianchi I model in the context of loop quantum cosmology. Our analysis has shown robust evidence of an instability in the explicit implementation of the difference equation, implying important consequences for the correspondence between the full loop quantum gravity theory and loop quantum cosmology. As a result, one may question the choice of the quantization approach, the model of lattice refinement, and/or the role of the ambiguity parameters; all these should, in principle, be dictated by the full loop quantum gravity theory.

The production of single and doubly charged Higgs bosons associated with standard model gauge boson $Z_L$ in $e^{+}{e}^{-}$ colliders is examined. The sensitivity of these processes on the littlest Higgs model parameters in the range of compatibility with electroweak precision observables is analyzed. The possibility of detecting lepton flavor violation processes is also discussed.

Lee-Wick partners to the standard model Higgs doublet may appear at a mass scale that is significantly lower than that of the remaining Lee-Wick partner states. The relevant effective theory is a two-Higgs doublet model in which one doublet has wrong-sign kinetic and mass terms. We determine bounds on this effective theory, including those from neutral $B$-meson mixing, $b\to X_s\gamma$, and $Z\to b\overline{b}$. The results differ from those of conventional two-Higgs doublet models and lead to meaningful constraints on the Lee-Wick Higgs sector.

Recently the Belle collaboration has measured a new decay channel for the charmed strange meson $D_{s_1}(2536{)}^{+}(D_{s_1}(2536{)}^{+}\to D^{+}{\pi }^{-}{K}^{+})$ together with an angular analysis of the $D_{s_1}(2536{)}^{+}\to D^{*+}{K}_S^0$ decay. We study this reaction in a constituent quark model which has been able to reproduce the hadronic phenomenology and the baryon-baryon interaction. The reported branching fractions and the properties of the $D_{s_1}(2536{)}^{+}$ state are nicely reproduced. Some consequences on the structure of the $P$-wave mesons are discussed.

We consider three-loop radiative-recoil corrections to hyperfine splitting in muonium due to insertions of a one-loop polarization operator in the muon factor. The contribution produced by electron polarization insertions is enhanced by the large logarithm of the electron-muon mass ratio. We obtained all single-logarithmic and nonlogarithmic radiative-recoil corrections of order ${\alpha }^3(m/M)E_F$ generated by the diagrams with electron and muon polarization insertions.

We measure the absolute branching fractions of $D_s$ semileptonic decays where the hadron in the final state is one of $\varphi$, $\eta$, ${\eta }^{\prime }$, $K_S^0$, $K^{\star 0}$, and $f_0$, using $2.8\times {10}^5$ $e^{+}{e}^{-}\to D_s{D}_s^{\star }$ decays collected in the CLEO-c detector at a center-of-mass energy close to 4170 MeV. We obtain $\mathcal{B}(D_s^{+}\to \varphi e^{+}{\nu }_e)=(2.29\pm 0.37\pm 0.11)\%$, $\mathcal{B}(D_s^{+}\to \eta e^{+}{\nu }_e)=(2.48\pm 0.29\pm 0.13)\%$, $\mathcal{B}(D_s^{+}\to {\eta }^{\prime }{e}^{+}{\nu }_e)=(0.91\pm 0.33\pm 0.05)\%$, where the first uncertainties are statistical and the second are systematic. We also obtain $\mathcal{B}(D_s^{+}\to K^0{e}^{+}{\nu }_e)=(0.37\pm 0.10\pm 0.02)\%$, and $\mathcal{B}(D_s^{+}\to K^{\star 0}{e}^{+}{\nu }_e)=(0.18\pm 0.07\pm 0.01)\%$, which are the first measurements of Cabibbo suppressed exclusive $D_s$ semileptonic decays, and, $\mathcal{B}(D_s^{+}\to f_0{e}^{+}{\nu }_e)\times \mathcal{B}(f_0\to {\pi }^{+}{\pi }^{-})=(0.13\pm 0.04\pm 0.01)\%$. This is the first absolute product branching fraction determination for a semileptonic decay including a scalar meson in the final state.

We present a measurement of the $D^0-{\overline{D}}^0$ mixing parameter $y_{CP}$ using a flavor-untagged sample of $D^0\to K_S^0{K}^{+}{K}^{-}$ decays. The measurement is based on a $673{\mathrm{fb}}^{-1}$ data sample recorded with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. Using a method based on measuring the mean decay time for different $K^{+}{K}^{-}$ invariant mass intervals, we find $y_{CP}=(+0.11\pm 0.61(\mathrm{stat}.)\pm 0.52(\mathrm{syst}.))\%$.

Using a sample of $2.59\times {10}^7$ $\psi (2S)$ decays collected by the CLEO-c detector, we present results of a search for the decay chain $\psi (2S)\to {\pi }^0{h}_c$, $h_c\to n({\pi }^{+}{\pi }^{-}){\pi }^0$, $n=1$, 2, 3. We observe no significant signals for $n=1$ and $n=3$ and set upper limits for the corresponding decay rates. First evidence for the decay $h_c\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}{\pi }^0$ is presented, and a product branching fraction of $B(\psi (2S)\to h_c{\pi }^0)\times B(h_c\to 2({\pi }^{+}{\pi }^{-}){\pi }^0)={1.88}_{-0.45-0.30}^{+0.48+0.47}\times {10}^{-5}$ is measured. This result implies that $h_c\to \mathrm{\text{hadrons}}$ and $h_c\to \gamma {\eta }_c$ have comparable rates, in agreement with expectations.

We consider a cosmology with a noncompact nonlinear sigma model. The target space is of de Sitter type and four scalar fields are introduced. The potential is absent but cosmological constant term $\Lambda$ is added. One of the scalar fields is time dependent and the remaining three fields have no time dependence but only spatial dependence. We show that a very simple ansatz for the scalar fields results in the accelerating universe with an exponential expansion at late times. It is pointed out that the presence of the energy density and pressure coming from the spatial variation of the three scalar fields plays an essential role in our analysis which includes $\Lambda =0$ as a special case and it discriminate from the standard $\Lambda$-dominated acceleration. We perform a stability analysis of the solutions and find that some solutions are classically stable and attractor. We also present a nonperturbative solution which asymptotically approaches an exponential acceleration and discuss possible cosmological implications in relation to dark energy. It turns out that the equation of state approaches asymptotically $\omega =-1$ both from above and below, but the crossing does not occur. It predicts present value of $\omega \sim -1\mp 0.07$, which is within the region allowed by the observational data. This solution also exhibits a power law expansion at early times, and the energy density of the scalar fields mimics that of the stiff matter.

The formalism for modeling multiple fermion generations in a warped extra dimension with a soft wall is presented. A bulk Higgs condensate is responsible for generating mass for the zero-mode fermions but leads to additional complexity from large mixing between different flavors. We extend existing single-generation analyses by considering new special cases in which analytical solutions can be derived. The general three-generation case is then treated using a simple numerical routine. Assuming anarchic 5D parameters, we find a fermion mass spectrum resembling the standard model quarks and leptons with highly degenerate couplings to Kaluza-Klein gauge bosons. This confirms that the soft-wall model has similar attractive features as that found in hard-wall models, providing a framework to generalize existing phenomenological analyses.

We explore the possibilities of constructing bulk spacetimes in five dimensions for warped braneworld models with a spatially flat Friedmann-Robertson-Walker line element on the 3-brane and with a time-dependent extra dimension. Our first step in this direction involves looking at the status of energy conditions when such a bulk line element is assumed. We check these conditions by analyzing the relevant inequalities—for specific functional forms (chosen to satisfy certain desirable features) of the warp factor—the cosmological scale factor, and the extra-dimensional scale factor. Subsequently, we aim to obtain solutions with different types of bulk matter sources. We begin with a general analysis of the solution space of nonsingular Randall-Sundrum–type bulk models with an exponential warp factor and a chosen equation of state. Thereafter, we focus on three specific bulk sources—the ordinary scalar field, the Brans-Dicke scalar, and the dilaton. In each case, we are able to solve the field equations and obtain desirable solutions, for which we once again check the viability of the energy conditions. We also show how one can place branes in the bulk using the junction conditions. The issue of resolution of the bulk singularities which appear in our solutions, using standard methods, is also presented briefly. In summary, we are able to demonstrate that it is indeed possible to construct viable bulk spacetimes for warped cosmological braneworlds with a time-varying extra dimension and with bulk matter satisfying the energy conditions.

We perform $N$-body simulations of theories with infinite-volume extra dimensions, such as the Dvali-Gabadadze-Porrati model and its higher-dimensional generalizations, where 4D gravity is mediated by massive gravitons. The longitudinal mode of these gravitons mediates an extra scalar force, which we model as a density-dependent modification to the Poisson equation. This enhances gravitational clustering, particularly on scales that have undergone mild nonlinear processing. While the standard nonlinear fitting algorithm of Smith et al. overestimates this power enhancement on nonlinear scales, we present a modified fitting formula that offers a remarkably good fit to our power spectra. Because of the uncertainty in galaxy bias, our results are consistent with precision power spectrum determinations from galaxy redshift surveys, even for graviton Compton wavelengths as small as 300 Mpc. Our model is sufficiently general that we expect it to capture the phenomenology of a wide class of related higher-dimensional gravity scenarios.