We investigate the isocurvaton model, in which the isocurvature perturbation plays a role in suppressing the curvature perturbation, and large non-Gaussianity and gravitational waves can be produced with no isocurvature perturbation for dark matter. We show that in the slow-roll noninteracting multifield theory, the isocurvaton mechanism cannot be realized. This result can also be generalized to most of the studied models with generalized kinetic terms. We also study the implications for the curvaton model. We show that there is a combined constraint for curvaton on non-Gaussianity, gravitational waves, and isocurvature perturbation. The technique used in this paper can also help to simplify some calculations in the mixed inflaton and curvaton models. We also investigate the possibility of producing large negative non-Gaussianity and nonlocal non-Gaussianity in the curvaton model.

We show that the thermodynamics of a system of strings at high energy densities under the ideal gas approximation has a formulation in terms of the Hamilton-Jacobi theory. The two parameters of the system, which have dimensions of energy density and number density, respectively, define a family of hypersurfaces of a codimension one, which can be described by the vanishing of a function $F$ that plays the role of a Hamiltonian.

In this paper, we investigate the phenomenological implications of boundary localized terms (BLTs) in the model of universal extra dimensions (UED). In particular, we study the electroweak Kaluza-Klein mass spectrum resulting from BLTs and their effect on electroweak symmetry breaking via the five-dimensional Higgs mechanism. We find that the addition of BLTs to massive five-dimensional fields induces a nontrivial extra-dimensional profile for the zero and nonzero Kaluza-Klein (KK) modes. Hence BLTs generically lead to a modification of standard model parameters and are therefore experimentally constrained, even at tree level. We study standard model constraints on three representative nonminimal UED models in detail and find that the constraints on BLTs are weak. On the contrary, nonzero BLTs have a major impact on the spectrum and couplings of nonzero KK modes. For example, there are regions of parameter space where the lightest Kaluza-Klein particle is either the Kaluza-Klein Higgs boson or the first KK mode of the $W^3$.

The influence of the Maxwell field on a static, asymptotically flat, and spherically-symmetric Gauss-Bonnet black hole is considered. Numerical computations suggest that if the charge increases beyond a critical value, the inner determinant singularity is replaced by an inner singular horizon.

We demonstrate numerically that an oscillation mode in $1+1$ dimensions (e.g., a breather or an oscillon) can decay into a kink-antikink pair by a sudden distortion of the evolution potential which occurs within a certain time or space domain. In particular, we consider the transition of a sine-Gordon potential into a ${\Phi }^4$ potential. The breather field configuration is assumed to initially evolve in a sine-Gordon potential with velocity $v$ and oscillation frequency $\omega$. We then consider two types of numerical experiments: (a) an abrupt transition of the potential to a ${\Phi }^4$ form at $t_0=0$ over the whole 1-dimensional lattice; and (b) the impact of the breather on a region $x>x_0=0$ where the potential has the ${\Phi }^4$ form which is different from the sine-Gordon form valid at $x<x_0=0$. We find that in both cases there is a region of parameters $(v,\omega )$ such that the breather decays to a kink-antikink pair. This region of parameters for kink-antikink formation is qualitatively similar with the parameter region where the energy of the breather exceeds the energy of the kink-antikink pair in the ${\Phi }^4$ potential. We demonstrate that the same mechanism for soliton formation is realized when using a Gaussian oscillator (oscillon) instead of a breather. We briefly discuss the implications of our results for realistic experiments as well as their extension to soliton formation in two and three space dimensions.

We apply the entropy formalism to the study of the near-horizon geometry of extremal black $p$-brane intersections in $D>5$-dimensional supergravities. The scalar flow towards the horizon is described in terms of an effective potential given by the superposition of the kinetic energies of all the forms under which the brane is charged. At the horizon active scalars get fixed to the minima of the effective potential and the entropy function is given in terms of $U$-duality invariants built entirely out of the black $p$-brane charges. The resulting entropy function reproduces the central charges of the dual boundary conformal field theory (CFT) and gives rise to a Bekenstein-Hawking-like area law. The results are illustrated in the case of black holes and black string intersections in $D=6,7,8$ supergravities where the effective potentials, attractor equations, moduli spaces, and entropy/central charges are worked out in full detail.

In conventional models of gauge-mediated supersymmetry breaking, the lightest supersymmetric particle is invariably the gravitino. However, if the supersymmetry-breaking sector is strongly coupled, conformal sequestering may raise the mass of the gravitino relative to the remaining soft supersymmetry-breaking masses. In this paper, we demonstrate that such conformal dynamics in gauge-mediated theories may give rise to satisfactory neutralino dark matter while simultaneously solving the flavor and $\mu /B\mu$ problems.

Relativistic current carrying strings moving axisymmetrically on the background of a Kerr black hole are studied. The boundaries and possible types of motion of a string with a given energy and current are found. Regions of parameters for which the string falls into the black hole, is trapped in a toroidal volume, or can escape to infinity, are identified, and representative trajectories are examined by numerical integration, illustrating various interesting behaviors. In particular, we find that a string can start out at rest near the equatorial plane and, after bouncing around, be ejected out along the axis, some of its internal (elastic or rotational kinetic) energy having been transformed into translational kinetic energy. The resulting velocity can be an order unity fraction of the speed of light. This process results from the presence of an outer tension barrier and an inner angular momentum barrier that are deformed by the gravitational field. We speculatively discuss the possible astrophysical significance of this mechanism as a means of launching a collimated jet of magnetohydrodynamics plasma flux tubes along the spin axis of a gravitating system fed by an accretion disk.

We investigate the consequences of the ambiguity of the minimal coupling procedure for Einstein-Cartan gravity with the Holst term and fermions. A new insight is provided into the nature and physical relevance of coupling procedures considered hitherto in the context of Ashtekar-Barbero-Immirzi formalism with fermions. The issue of physical effects of the Immirzi parameter in semiclassical theory is reinvestigated. We argue that the conclusive answer to the question of its measurability will not be possible until the more fundamental problem of nonuniqueness of gravity-induced fermion interaction in Einstein-Cartan theory is solved.

The analogy between electrodynamics and the translational gauge theory of gravity is employed in this paper to develop an ansatz for a nonlocal generalization of Einstein’s theory of gravitation. Working in the linear approximation, we show that the resulting nonlocal theory is equivalent to general relativity with “dark matter.” The nature of the predicted dark matter, which is the manifestation of the nonlocal character of gravity in our model, is briefly discussed. It is demonstrated that this approach can provide a basis for the Tohline-Kuhn treatment of the astrophysical evidence for dark matter.

By a combination of analytical and numerical techniques, we demonstrate the existence of spherical, asymptotically flat traversable wormholes supported by exotic matter whose stress tensor relative to the orthonormal frame of Killing observers takes the form of a perfect fluid possessing anisotropic pressures and subject to linear equations of state: $\tau =\lambda \rho c^2$, $P=\mu \rho c^2$. We show that there exists a four parameter family of asymptotically flat spherical wormholes parametrized by the area of the throat $A(0)$, the gradient $\Lambda (0)$ of the red shift factor evaluated on the throat as well as the values of $(\lambda ,\mu )$. The latter are subject to restrictions: $\lambda >1$ and $2\mu >\lambda$ or $\lambda <0$ and $2\mu <-|\lambda |$. For particular values of $(\lambda ,\mu )$, the stress tensor may be interpreted as representing a phantom configuration, while for other values represents exotic matter. All solutions have the property that the two asymptotically flat ends possess finite Arnowitt-Deser-Misner mass.

The standard cosmological model, which includes only Compton scattering photon interactions at energy scales near recombination, results in zero primordial circular polarization of the cosmic microwave background. In this paper we consider a particular renormalizable and gauge-invariant standard model extension coupling photons to an external vector field via a Chern-Simons term, which arises as a radiative correction if gravitational torsion couples to fermions. We compute the transport equations for polarized photons from a Boltzmann-like equation, showing that such a coupling will source circular polarization of the microwave background. For the particular coupling considered here, the circular polarization effect is always negligible compared to the rotation of the linear polarization orientation, also derived using the same formalism. We note the possibility that limits on microwave background circular polarization may probe other photon interactions and related fundamental effects such as violations of Lorentz invariance.

Recently Eisenstein and collaborators introduced a method to “reconstruct” the linear power spectrum from a nonlinearly evolved galaxy distribution in order to improve precision in measurements of baryon acoustic oscillations. We reformulate this method within the Lagrangian picture of structure formation, to better understand what such a method does, and what the resulting power spectra are. We show that reconstruction does not reproduce the linear density field, at second order. We however show that it does reduce the damping of the oscillations due to nonlinear structure formation, explaining the improvements seen in simulations. Our results suggest that the reconstructed power spectrum is potentially better modeled as the sum of three different power spectra, each dominating over different wavelength ranges and with different nonlinear damping terms. Finally, we also show that reconstruction reduces the mode-coupling term in the power spectrum, explaining why miscalibrations of the acoustic scale are reduced when one considers the reconstructed power spectrum.

We use Monte Carlo simulations to obtain an improved lattice measurement of the critical coupling constant $[\lambda /{\mu }^2{]}_{\mathrm{crit}}$ for the continuum $(1+1)$-dimensional $(\lambda /4){\varphi }^4$ theory. We find that the critical coupling constant depends logarithmically on the lattice coupling, resulting in a continuum value of $[\lambda /{\mu }^2{]}_{\mathrm{crit}}={10.8}_{-0.05}^{+0.10}$, in considerable disagreement with the previously reported $[\lambda /{\mu }^2{]}_{\mathrm{crit}}={10.26}_{-0.04}^{+0.08}$. Although this logarithmic behavior was not observed in earlier lattice studies, it is consistent with them, and expected analytically.

We explore the consequences of an electroweak symmetry breaking sector which exhibits approximately scale invariant dynamics, i.e., nontrivial fixed point behavior, as in unparticle models. One can think of an unparticle Higgs as a composite Higgs boson with a continuous mass distribution. We find it convenient to represent the unparticle Higgs in terms of a Källen-Lehmann spectral function, from which it is simple to verify the generation of gauge boson and fermion masses, and unitarization of $WW$ scattering. We show that a spectral function with broad support, which corresponds to approximate fixed point behavior over an extended range of energy, can lead to an effectively invisible Higgs particle, whose decays at CERN LEP or LHC could be obscured by background.

We study radiative decays of heavy $Q\overline{Q}$ states, both for $Q=c$ and $Q=b$, using an effective Lagrangian approach which exploits spin symmetry for such states. We use existing data on radiative quarkonium transitions to predict some unmeasured decay rates. We also discuss how these modes can be useful to understand the structure of $X(3872)$.

We reappraise the question of whether the standard model, and minimal flavor violating (MFV) models at large, can simultaneously describe the observed $CP$ violation in the $K$ and $B_d$ systems. We find that $CP$ violation in the $B_d$ system, measured most precisely through $(\sin 2\beta {)}_{J/\psi K_s}$, implies $|{ϵ}_K^{\mathrm{SM}}|=1.78(25)\times {10}^{-3}$ for the parameter ${ϵ}_K$, measuring indirect $CP$ violation in the $K$ system, to be compared with the experimental value $|{ϵ}_K^{\exp }|=2.23(1)\times {10}^{-3}$. To bring this prediction to $1\sigma$ agreement with experiment, we then explore the simplest new-physics possibility not involving new phases, namely, that of MFV scenarios with no new effective operators besides the standard model ones. We emphasize the crucial input and/or measurements to be improved in order to probe this case. In particular, we point out that this tension could be removed in this framework, with interesting signatures, e.g. correlated suppression patterns for rare $K$ decay branching ratios. On the other hand, MFV contributions from new operators appear, in the calculable case of the MSSM, to worsen the situation. We finally explore some well-motivated new-physics scenarios beyond MFV models, like those involving generic new contributions in $Z$ penguins.

In constructing collinear operators, which describe the production of energetic jets or energetic hadrons, important constraints are provided by reparametrization invariance (RPI). RPI encodes Lorentz invariance in a power expansion about a collinear direction, and connects the Wilson coefficients of operators at different orders in this expansion to all orders in ${\alpha }_s$. We construct reparametrization invariant collinear objects. The expansion of operators built from these objects provides an efficient way of deriving RPI relations and finding a minimal basis of operators, particularly when one has an observable with multiple collinear directions and/or soft particles. Complete basis of operators is constructed for pure glue currents at twist-4, and for operators with multiple collinear directions, including those appearing in $e^{+}{e}^{-}\to 3$ jets, and for $pp\to 2$ jets initiated via gluon fusion.

For Schwinger pair production with background electric fields varying only in time, it is shown that the quantum kinetic approach, based on the quantum Vlasov equation, and the quantum mechanical scattering approach are completely equivalent. This different perspective on the quantum kinetic approach suggests new approximation methods, which are tested in detail using a soluble pulselike field configuration, and may give useful insight for generalization to more general electric fields, varying in more than one dimension.

Recent PAMELA data showed that positron fraction has an excess above several GeV while the antiproton one does not. Moreover, ATIC data indicates that electron/positron flux has a bump from 300 GeV to 800 GeV. Both annihilating dark matter (DM) with a large boost factor and decaying DM with a life around ${10}^{26}s$ can account for the PAMELA and ATIC observations if their main final products are charged leptons ($e$, $\mu$, and $\tau$). In this work, we calculated the neutrino flux arising from $\mu$ and $\tau$ that originate from annihilating/decaying DM and estimated the final muon rate in neutrino telescopes, namely Antares and IceCube. Given the excellent angular resolution, Antares and IceCube are promising to discover the neutrino signals from the Galactic center and/or the large DM subhalo in the annihilating DM scenario, but very challenging in the decaying DM scenario.