A particular form for the quantum indeterminacy of relative spacetime position of events is derived from the context of a holographic geometry with a minimum length at the Planck scale. The indeterminacy predicts fluctuations from a classically defined geometry in the form of “holographic noise” whose spatial character, absolute normalization, and spectrum are predicted with no parameters. The noise has a distinctive transverse spatial shear signature and a flat power spectral density given by the Planck time. An interferometer signal displays noise due to the uncertainty of relative positions of reflection events. The noise corresponds to an accumulation of phase offset with time that mimics a random walk of those optical elements that change the orientation of a wavefront. It only appears in measurements that compare transverse positions and does not appear at all in purely radial position measurements. A lower bound on holographic noise follows from a covariant upper bound on gravitational entropy. The predicted holographic noise spectrum is estimated to be comparable to measured noise in the currently operating interferometric gravitational-wave detector GEO600. Because of its transverse character, holographic noise is reduced relative to gravitational wave effects in other interferometer designs, such as the LIGO observatories, where beam power is much less in the beam splitter than in the arms.

We write a covariant transport equation for the phonon excitations of a relativistic superfluid valid at small temperatures. The hydrodynamical equations for this system are derived from the effective field theory associated to the superfluid phonons. We describe how to construct the kinetic theory for the phonon quasiparticles using a relativistic generalization of the analogue model of gravity developed by Unruh. This gravity analogy relies on the equivalence between the action of a phonon field moving in a superfluid background with that of a boson propagating in a given curved space-time. Exploiting this analogy we obtain continuity equations for the phonon current, entropy and energy-momentum tensor in a covariant form, valid in any reference frame. Our aim is to shed light on some aspects of transport phenomena of relativistic superfluidity. In particular, we are interested in the low temperature regime of the color flavor locked phase, which is a color superconducting and superfluid phase of high density QCD that may be realized in the core of neutron stars.

Microwave background temperature and polarization observations are a powerful way to constrain cosmological parameters if the likelihood function can be calculated accurately. The temperature and polarization fields are correlated, partial-sky coverage correlates power spectrum estimators at different $l$, and the likelihood function for a theory spectrum given a set of observed estimators is non-Gaussian. An accurate analysis must model all these properties. Most existing likelihood approximations are good enough for a temperature-only analysis, however they cannot reliably handle temperature-polarization correlations. We give a new general approximation applicable for correlated Gaussian fields observed on part of the sky. The approximation models the non-Gaussian form exactly in the ideal full-sky limit and is fast to evaluate using a precomputed covariance matrix and set of power spectrum estimators. We show with simulations that it is good enough to obtain correct results at $l\gtrsim 30$ where an exact calculation becomes impossible. We also show that some Gaussian approximations give reliable parameter constraints even though they do not capture the shape of the likelihood function at each $l$ accurately. Finally we test the approximations on simulations with realistically anisotropic noise and asymmetric foreground mask.

This paper is mainly devoted to applying the invariant, fast, Lyapunov indicator to clarify some doubt regarding the apparently conflicting results of chaos in spinning compact binaries at the second-order post-Newtonian approximation of general relativity from previous literatures. It is shown with a number of examples that no single physical parameter or initial condition can be described as responsible for causing chaos, but a complicated combination of all parameters and initial conditions is responsible. In other words, a universal rule for the dependence of chaos on each parameter or initial condition cannot be found in general. Chaos does not depend only on the mass ratio, and the maximal spins do not necessarily bring the strongest effect of chaos. Additionally, chaos does not always become drastic when the initial spin vectors are nearly perpendicular to the orbital plane, and the alignment of spins cannot trigger chaos by itself.

We investigate space- and timelike form factors for $\omega \to \pi {\gamma }^{*}$ and $K^{*}\to K{\gamma }^{*}$ decays using the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. The momentum dependent spacelike form factors are obtained in the $q^{+}=0$ frame and then analytically continued to the timelike region. Our prediction for the timelike form factor $F_{\omega \pi }(q^2)$ is in good agreement with the experimental data. We also find that the spacelike form factor $F_{K^{*\pm }{K}^{\pm }}(Q^2)$ for charged kaons encounters a zero because of the negative interference between the two currents to the quark and the antiquark.

Chiral symmetry is an essential concept in understanding QCD at low energy. We treat the chiral condensate, which measures the spontaneous breaking of chiral symmetry, as a free parameter to investigate the effect of partially restored chiral symmetry on the physical quantities in the framework of an AdS/QCD model. We observe an interesting scaling behavior among the nucleon mass, pion decay constant, and chiral condensate. We propose a phenomenological way to introduce the temperature dependence of a physical quantity in the AdS/QCD model with the thermal AdS metric.

Vertices are of central importance for constructing QCD bound states out of the individual constituents of the theory, i.e. quarks and gluons. In particular, the determination of three-point vertices is crucial in nonperturbative investigations of QCD. We use numerical simulations of lattice gauge theory to obtain results for the 3-point vertices in Landau-gauge SU(2) Yang-Mills theory in three and four space-time dimensions for various kinematic configurations. In all cases considered, the ghost-gluon vertex is found to be essentially tree-level-like, while the three-gluon vertex is suppressed at intermediate momenta. For the smallest physical momenta, reachable only in three dimensions, we find that some of the three-gluon-vertex tensor structures change sign.

The $B^{*}B\pi$ coupling is a fundamental parameter of chiral effective Lagrangian with heavy-light mesons and can constrain the chiral behavior of $f_B$, $B_B$, and the $B\to \pi l\nu$ form factor in the soft pion limit. We compute the $B^{*}B\pi$ coupling with the static heavy quark and the $O(a)$-improved Wilson light quark. Simulations are carried out with $n_f=2$ unquenched ${12}^3\times 24$ lattices at $\beta =1.80$ and ${16}^3\times 32$ lattices at $\beta =1.95$ generated by the CP-PACS collaboration. To improve the statistical accuracy, we employ the all-to-all propagator technique and the static quark action with smeared temporal link variables. These methods successfully work also on unquenched lattices, and determine the $B^{*}B\pi$ coupling with 1%–2% statistical accuracy on each lattice spacing.

An analysis of the neutrino oscillation physics capability of a low-energy neutrino factory is presented, including a first simulation of the detector efficiency and event energy threshold. The sensitivity of the physics reach to the presence of backgrounds is also studied. We consider a representative baseline of 1480 km, we use muons with 4.12 GeV energy and we exploit a very conservative estimate of the energy resolution of the detector. Our analysis suggests an impressive physics reach for this setup, which can eliminate degenerate solutions, for both large and small values of the mixing angle ${\theta }_{13}$, and can determine leptonic $CP$ violation and the neutrino mass hierarchy with extraordinary sensitivity.

We discuss the limits on the neutrino magnetic moment and hypothetical interactions with a hidden unparticle sector, coming from the first neutrino data release of the Borexino experiment. The observed spectrum in Borexino depends weakly on the solar model used in the analysis, since most of the signal comes from the monoenergetic ${}^7\mathrm{Be}$ neutrinos. This fact allows us to calibrate the $\nu -e$ scattering cross section through the spectral shape. In this way, we have derived a limit on the magnetic moment for the neutrinos coming from the Sun (in which a ${\nu }_{\mu }$ and ${\nu }_{\tau }$ component is present): ${\mu }_{\nu }\le 8.4\times {10}^{-11}{\mu }_B$ (90% CL) which is comparable with those obtained from low-energy reactor experiments. Moreover, we improve the previous upper limit on magnetic moment of the ${\nu }_{\tau }$ by 3 orders of magnitude and the limit on the coupling constant of the neutrino with a hidden unparticle sector.

We evaluate, analytically, a specific class of eighth order and tenth order QED contributions to the anomalous magnetic moment of the muon. They are generated by Feynman diagrams involving lowest order vacuum polarization insertions of leptons $l=e$, $\mu$, and $\tau$. The results are given in the form of analytic expansions in terms of the mass ratios $m_e/m_{\mu }$ and $m_{\mu }/m_{\tau }$. We compute as many terms as required by the error induced by the present experimental uncertainty on the lepton masses. We show how the Mellin-Barnes integral representation of Feynman parametric integrals allows for an easy analytic evaluation of as many terms as wanted in these expansions and how its underlying algebraic structure generalizes the standard renormalization group properties. We also discuss the generalization of this technique to the case where two independent mass ratios appear. Comparison with previous numerical and analytic evaluations made in the literature, whenever pertinent, are also made.

Assuming that the neutrino mass matrix is dominated by a term with the permutation symmetry $S_3$ it is possible to explain neutrino data only if the masses are quasidegenerate. A subdominant term with an approximate $\mu -\tau$ symmetry leads to an approximate tribimaximal form. Experimental consequences are discussed.

Using $281{\mathrm{pb}}^{-1}$ of data collected with the CLEO-c detector at the $\psi (3770)$ resonance, we have studied Cabibbo-suppressed decays of $D$ mesons to final states with two kaons. We present results for the absolute branching fractions of the modes $D^0\to K^{+}{K}^{-}$, $D^0\to K_S^0{K}_S^0$, and $D^{+}\to K^{+}{K}_S^0$. We measure $\mathcal{B}(D^0\to K^{+}{K}^{-})=(4.08\pm 0.08\pm 0.09)\times {10}^{-3}$, $\mathcal{B}(D^0\to K_S^0{K}_S^0)=(1.46\pm 0.32\pm 0.09)\times {10}^{-4}$, and $\mathcal{B}(D^{+}\to K^{+}{K}_S^0)=(3.14\pm 0.09\pm 0.08)\times {10}^{-3}$. We also determine the ratio $\mathcal{B}(D^0\to K^{+}{K}^{-})/\mathcal{B}(D^0\to {\pi }^{+}{\pi }^{-})=2.89\pm 0.05\pm 0.06$. For each measurement, the first uncertainty is statistical and the second uncertainty is systematic.

We provide a simple example of dilaton stabilization in the framework of heterotic string theory. It requires a gaugino condensate and an uplifting sector similar to the one postulated in type IIB string theory. Its signature is a hybrid mediation of supersymmetry breakdown with a variant of a mirage pattern for the soft breaking terms. The setup is suited for the discussion of heterotic minimal supersymmetric standard model candidates.

We consider scalar perturbations in the time dependent Hořava-Witten model in order to probe its stability. We show that during the nonsingular epoque the model evolves without instabilities until it encounters the curvature singularity where a big crunch is supposed to occur. We compute the frequencies of the scalar field oscillation during the stable period and show how the oscillations can be used to prove the presence of such a singularity.

Quantum graphity is a background-independent model for emergent macroscopic locality, spatial geometry and matter. The states of the system correspond to dynamical graphs on $N$ vertices. At high energy, the graph describing the system is highly connected and the physics is invariant under the full symmetric group acting on the vertices. We present evidence that the model also has a low-energy phase in which the graph describing the system breaks permutation symmetry and appears to be ordered, low dimensional and local. Consideration of the free energy associated with the dominant terms in the dynamics shows that this low-energy state is thermodynamically stable under local perturbations. The model can also give rise to an emergent U(1) gauge theory in the ground state by the string-net condensation mechanism of Levin and Wen. We also reformulate the model in graph-theoretic terms and compare its dynamics to some common graph processes.

We use metric formalism in $f(R)$ modified gravity to study the dynamics of various systems from the solar system to the cosmological scale. We assume an ansatz for the derivative of action as a function of distance and describe the Pioneer anomaly and the flat rotation curve of the spiral galaxies. Having the asymptotic behavior of action, we propose the action of $f(R)=(R+\Lambda )(1+\ln (R/R_c)/(R/R_0+2/\alpha ))$ where in galactic and solar system scales it can recover our desired form. The vacuum solution of this action also results in a positive late time acceleration for the Universe. We fix the parameters of this model, comparing with the Pioneer anomaly, rotation curve of spiral galaxies, and supernova type Ia gold sample data.

We extend the covariant, parametrized post-Friedmann treatment of cosmic acceleration from modified gravity to an arbitrary admixture of matter, radiation, relativistic components, and spatial curvature. This generalization facilitates the adaptation of Einstein-Boltzmann codes for solving cosmic microwave background and matter perturbations in the linear regime. We use such a code to study the effect of metric evolution on the cosmic microwave background through the integrated Sachs-Wolfe effect. We discuss the ability of modified gravity to alter the low multipole spectrum, including lowering the power in the quadrupole. From a principal component description of the primary metric ratio parameter, we obtain general constraints from the Wilkinson Microwave Anisotropy Probe on modified gravity models of the acceleration.

We study the stability of the isotropic vacuum Friedmann universe in gravity theories with higher-order curvature terms of the form $(R_{ab}{R}^{ab}{)}^n$ added to the Einstein-Hilbert Lagrangian of general relativity on approach to an initial cosmological singularity. Earlier, we had shown that, when $n=1$, a special isotropic vacuum solution exists which behaves like the radiation-dominated Friedmann universe and is stable to anisotropic and small inhomogeneous perturbations of scalar, vector, and tensor type. This is completely different to the situation that holds in general relativity, where an isotropic initial cosmological singularity is unstable in vacuum and under a wide range of nonvacuum conditions. We show that when $n\ne 1$, although a special isotropic vacuum solution found by Clifton and Barrow always exists, it is no longer stable when the initial singularity is approached. We find the particular stability conditions under the influence of tensor, vector, and scalar perturbations for general $n$ for both solution branches. On approach to the initial singularity, the isotropic vacuum solution with scale factor $a(t)=t^{P_{-}/3}$ is found to be stable to tensor perturbations for $0.5<n<1.1309$ and stable to vector perturbations for $0.861425<n\le 1$, but is unstable as $t\to 0$ otherwise. The solution with scale factor $a(t)=t^{P_{+}/3}$ is not relevant to the case of an initial singularity for $n>1$ and is unstable as $t\to 0$ for all $n$ for each type of perturbation.

We study second order gravitational effects of local inhomogeneities on the cosmic microwave background radiation in flat universes with matter and a cosmological constant $\Lambda$. We find that the general relativistic correction to the Newtonian approximation is negligible at second order provided that the size of the inhomogeneous region is sufficiently smaller than the horizon scale. For a spherically symmetric top-hat type quasilinear perturbation, the first order temperature fluctuation corresponding to the linear integrated Sachs-Wolfe effect is enhanced (suppressed) by the second order one for a compensated void (lump). As a function of redshift of the local inhomogeneity, the second order temperature fluctuations due to evolution of the gravitational potential have a peak before the matter-$\Lambda$ equality epoch for a fixed comoving size and a density contrast. The second order gravitational effects from local quasilinear inhomogeneities at a redshift $z\sim 1$ may significantly affect the cosmic microwave background.