For many quantum field theory computations in cosmology it is not possible to use the flat space trick of obtaining full, interacting states by evolving free states over infinite times. State wave functionals must be specified at finite times and, although the free states suffice to obtain the lowest order effects, higher order corrections necessarily involve changes of the initial state. Failing to correctly change the initial state can result in effective field equations which diverge on the initial value surface, or which contain tedious sums of terms that redshift like inverse powers of the scale factor. In this paper we verify a conjecture from 2004 that the lowest order initial state correction can indeed absorb the initial value divergences and all the redshifting terms of the two-loop expectation value (in free, Bunch-Davies vacuum) of the stress tensor of a massless, minimally coupled scalar with a quartic self-interaction on a nondynamical de Sitter background.

We investigate the abundance of large-scale hot and cold spots in the WMAP-5 temperature maps and find considerable discrepancies compared to Gaussian simulations based on the $\Lambda \mathrm{CDM}$ best-fit model. Too few spots are present in the reliably observed cosmic microwave background (CMB) region, i.e., outside the foreground-contaminated parts excluded by the KQ75 mask. Even simulated maps created from the original WMAP-5 estimated multipoles contain more spots than visible in the measured CMB maps. A strong suppression of the lowest multipoles would lead to better agreement. The lack of spots is reflected in a low mean temperature fluctuation on scales of several degrees (4°–8°), which is only shared by less than 1% (0.16%–0.62%) of Gaussian $\Lambda \mathrm{CDM}$ simulations. After removing the quadrupole, the probabilities change to 2.5%–8.0%. This shows the importance of the anomalously low quadrupole for the statistical significance of the missing spots. We also analyze a possible violation of Gaussianity or statistical isotropy (spots are distributed differently outside and inside the masked region).

It is usually thought that the quintessence as a fundamental scalar field was already present during the inflationary epoch. While there are various models in which the quintessence couples to other species, it is attractive to anticipate a coupling between the quintessence and the inflaton in the very early Universe as well. We consider such a coupling in the context of $k$-inflation. The coupling function and the potential of the quintessence are chosen to be of inverse power-law forms. We show such a coupling affects the speed of sound for the inflaton field as well as the power spectra of perturbations.

We address the problem of rationalizing the pattern of fermion masses and mixings by adding a non-Abelian flavor symmetry in a grand unified framework. With this purpose, we include an $A_4$ flavor symmetry into a unified renormalizable supersymmetric grand unified theory $SU(5)$ model. With the help of the “type II seesaw” mechanism we are able to obtain the pattern of observed neutrino mixings in a natural way, through the so-called tribimaximal matrix.

To get the total cross section of one interaction from its amplitude $\mathcal{M}$, one needs to integrate $|\mathcal{M}{|}^2$ over phase spaces of all outgoing particles. Starting from this paper, we will propose a new method to perform such integrations, which is inspired by the reduced phase space integration of one-loop unitarity cut developed in the last few years. The new method reduces one constrained three-dimension momentum space integration to a one-dimensional integration, plus one possible Feynman parameter integration. There is no need to specify a reference framework in our calculation, since every step is manifestly Lorentz invariant by the new method. The current paper is the first paper of a series for the new method. Here we have exclusively focused on massless particles in 4D. There is no need to carve out a complicated integration region in the phase space for this particular simple case because the integration region is always simply $[0,1]$.

We survey the low-energy supersymmetry phenomenology of a three-family Pati-Salam model constructed from intersecting $D6$-branes in Type IIA string theory on the ${\mathbf{T}}^{\mathbf{6}}/({\mathbb{Z}}_{\mathbf{2}}\times {\mathbb{Z}}_{\mathbf{2}})$ orientifold which possesses many of the phenomenological properties desired in string model building. In the model, there is no exotic matter in the low-energy spectrum, the correct mass hierarchies for quarks and leptons may be obtained, and the gauge couplings are automatically unified at the string scale. We calculate the supersymmetry breaking soft terms and the corresponding low-energy supersymmetry particle spectra for the model. We find the WMAP constrained dark-matter density can be generated in this model in the stau-neutralino and chargino-neutralino coannihilation regions, with expected final states at LHC consisting of low-energy leptons and $\mathcal{O}(\mathrm{GeV})$ neutrinos. Moreover, we expect final states in the supercritical string cosmology scenario to comprise high energy leptons and $\mathcal{O}(\mathrm{GeV})$ neutrinos.

Based on the data of BES and Belle, the production of $D\overline{D}$ in the $e^{+}{e}^{-}\to D\overline{D}$ scattering process is studied in this paper. We analyze the continuum and resonant contributions in the energy region from 3.7 to 4.4 GeV. In the ${\chi }^2$ fit to data, we obtain the resonance parameters of $\psi (3770)$, the branching ratio of $\psi (3770)\to D\overline{D}$ decay by confronting the data to the theoretical formula where both the contributions of the resonances, continuum and interference effects are included. We obtain the branching ratio of $\psi (3770)\to D\overline{D}$ decay is $97.2\%\pm 8.9\%$, as well as the branching ratio of $\psi (4040)$, $\psi (4160)\to D\overline{D}$ decays.

We investigate the vortex lattice solution in a $(2+1)$-dimensional holographic model of superconductors constructed from a charged scalar condensate. The solution is obtained perturbatively near the second-order phase transition and is a holographic realization of the Abrikosov lattice. Below a critical value of the magnetic field, the solution has a lower free energy than the normal state. Both the free-energy density and the superconducting current are expressed by nonlocal functions, but they reduce to the expressions in the Ginzburg-Landau theory at long wavelengths. As a result, a triangular lattice becomes the most favorable solution thermodynamically, as in the Ginzburg-Landau theory of type II superconductors.

We study the response of confining gauge theory to the external electric field by using holographic Yang-Mills theories in the large $N_c$ limit. Although the theories are in the confinement phase, we find a transition from the insulator to the conductor phase when the electric field exceeds its critical value. Then, the baryon number current is generated in the conductor phase. At the same time, in this phase, meson melting is observed through the quasinormal modes of the meson spectrum. Possible ideas are given for the string state corresponding to the melted mesons, and they lead to the idea that the source of this current may be identified with the quarks and antiquarks supplied by the melted mesons. We also discuss other possible carriers. Furthermore, from the analysis of the massless quark, chiral symmetry restoration is observed at the insulator-conductor transition point by studying a confining theory in which the chiral symmetry is broken.

In this work we study Podolsky electromagnetism in thermodynamic equilibrium. We show that a Podolsky mass-dependent modification to the Stefan-Boltzmann law is induced and we use experimental data to limit the possible values for this free parameter.

We consider a polymer quantization of a free massless scalar field in a homogenous and isotropic classical cosmological spacetime. This quantization method assumes that field translations are fundamentally discrete, and is related to but distinct from that used in loop quantum gravity. The semiclassical Friedmann equation yields a universe that is nonsingular and nonbouncing, without quantum gravity. The model has an early nearly de Sitter inflationary phase with sufficient expansion to resolve the horizon and entropy problems, and a built-in mechanism for a graceful exit from inflation.

The efficient placement of signal templates in source-parameter space is a crucial requisite for exhaustive matched-filtering searches of modeled gravitational-wave sources, as well as other searches based on more general detection statistics. Unfortunately, the current placement algorithms based on regular parameter-space meshes are difficult to generalize beyond simple signal models with few parameters. Various authors have suggested that a general, flexible, yet efficient alternative can be found in randomized placement strategies such as random placement and stochastic placement, which enhances random placement by selectively rejecting templates that are too close to others. In this article we explore several theoretical and practical issues in randomized placement: the size and performance of the resulting template banks; the very general, purely geometric effects of parameter-space boundaries; the use of quasirandom (self-avoiding) number sequences; most important, the implementation of these algorithms in curved signal manifolds with and without the use of a Riemannian signal metric, which may be difficult to obtain. Specifically, we show how the metric can be replaced with a discrete triangulation-based representation of local geometry. We argue that the broad class of randomized placement algorithms offers a promising answer to many search problems, but that the specific choice of a scheme and its implementation details will still need to be fine-tuned separately for each problem.

The WMAP haze is an excess in microwave emission coming from the center of the Milky Way galaxy. In the case of synchrotron emission models of the haze, we present tests for the source of radiating high-energy electrons/positrons. We explore several models in the case of a pulsar population or dark matter annihilation as the source. These morphological signatures of these models are small behind the WMAP Galactic mask, but are testable and constrain the source models. We show that detailed measurements of the morphology may distinguish between the pulsar and dark matter interpretations as well as differentiate among different pulsar models and dark matter profile models individually. Specifically, we find that a zero central density Galactic pulsar population model is in tension with the observed WMAP haze. The Planck Observatory’s greater sensitivity and expected smaller Galactic mask should potentially provide a robust signature of the WMAP haze as either a pulsar population or the dark matter.

We investigate a possibility to restrict various inflationary models with nonminimally coupled inflaton field $\varphi$ by future measurement of nonlinear parameter $f_{\mathrm{NL}}$ which characterizes the non-Gaussianity in the cosmic microwave background temperature fluctuation. These models are related to the minimally coupled inflationary models by conformal transformation. We show that the curvature perturbation is invariant under the conformal transformation up to the second order. By using this property we show that nonminimal coupling $f(\varphi )R$ does not produce large non-Gaussianity, and, in particular, the nonlinear parameter takes a narrow range $-0.022<f_{\mathrm{NL}}<-0.007$ in the case of $f(\varphi )=1+\xi {\varphi }^2/m_P^2$ with a wide range of parameter $\xi$.

We study gravitational waves generated by the cosmological magnetic fields induced via bubble collisions during the electroweak (EW) and QCD phase transitions. The magnetic field generation mechanisms considered here are based on the use of the fundamental EW minimal supersymmetric and QCD Lagrangians. The gravitational waves spectrum is computed using a magnetohydrodynamic turbulence model. We find that the gravitational wave spectrum amplitude generated by the EW phase transition peaks at a frequency of approximately 1–2 mHz, and is of the order of ${10}^{-20}–{10}^{-21}$; thus this signal is possibly detectable by the Laser Interferometer Space Antenna (LISA). The gravitational waves generated during the QCD phase transition, however, are outside the LISA sensitivity bands.

When the last electron-photon scattering takes place in a magnetized environment, the degree of circular polarization of the outgoing radiation depends upon the magnetic field strength. After deriving the scattering matrix of the process, the generalized radiative transfer equations are deduced in the presence of the relativistic fluctuations of the geometry and for all the four brightness perturbations. The new system of equations is solved under the assumption that the incident radiation is not polarized. The induced $V$-mode polarization is analyzed both analytically and numerically. The corresponding angular power spectra are calculated and compared with the measured (or purported) values of the linear polarizations (i.e. $E$ mode and $B$ mode) as they arise in the concordance model and in its neighboring extensions. Possible connections between the $V$-mode polarization of the cosmic microwave background and the topological properties of the magnetic flux lines prior to equality are outlined and briefly explored in analogy with the physics of magnetized sunspots.

We present results from numerical solution of Einstein’s equation in five dimensions describing evolution of rapidly rotating black holes. We show, for the first time, that the rapidly rotating black holes in higher dimensions are unstable against nonaxisymmetric deformation; for the five-dimensional case, the critical value of spin parameter for onset of the instability is $\approx 0.87$.