We use the recent Type Ia supernova, cosmic microwave background and large-scale structure data to shed light on the temporal evolution of the dark energy equation of state $w(z)$ out to redshift one. We constrain the most flexible parametrization of dark energy to date, and include the dark energy perturbations consistently throughout. Interpreting our results via the principal component analysis, we find no significant evidence for dynamical dark energy: the cosmological constant model is consistent with data everywhere between redshift zero and one at 95% C.L.

An analysis of electroweak corrections to the anomalous dipole moments of lepton from some special two-loop diagrams where a closed neutralino/chargino loop is inserted into relevant one-loop diagrams of the standard model is presented in the split supersymmetry scenarios. Considering the translational invariance of the inner loop momenta and the electromagnetic gauge invariance, we get all dimension-6 operators and their coefficients. After applying equations of motion to the external leptons, we obtain the anomalous dipole moments of lepton. The numerical results imply that there is parameter space where the contribution to the muon anomalous MDM from this sector is perhaps significant, and the contribution to the electron electric dipole moment from this sector is sizable enough to be observed in next-generation experiments.

Within the framework of a mathematically well-defined coupled-channel T-matrix model we have improved the existing multichannel pole-extraction procedure based on the numerical analytic continuation of the channel propagator, and for the first time we present the full set of pole parameters for already published amplitudes. Standard single-channel pole-extraction method (speed plot) was then applied to those amplitudes and resulting sets of T-matrix poles were inspected. The anomaly has been established that in some partial waves the pole values extracted using the standard single-channel methods differ not only from the values obtained using the analytic continuation method, but also change from one reaction to another. Inspired by this peculiarity, we have developed a new single-channel pole-extraction method based solely on the assumption of the partial wave analyticity. Since the speed plot turns out to be the lowest order term of the proposed method, the anomaly is understood and resolved.

We discuss the properties of ’t Hooft vertices in partially quenched and rooted versions of QCD in the continuum. These theories have a physical subspace, equivalent to ordinary QCD, that is contained within a larger space that includes many unphysical correlation functions. We find that the ’t Hooft vertices in the physical subspace have the expected form, despite the presence of unphysical ’t Hooft vertices appearing in correlation functions that have an excess of valence quarks (or ghost quarks). We also show that, due to the singular behavior of unphysical correlation functions as the massless limit is approached, order parameters for nonanomalous symmetries can be nonvanishing in finite volume if these symmetries act outside of the physical subspace. Using these results, we demonstrate that arguments recently given by Creutz—claiming to disprove the validity of rooted staggered QCD—are incorrect. In particular, the unphysical ’t Hooft vertices do not present an obstacle to the recovery of taste symmetry in the continuum limit.

The ${\tau }^{-}\to (\omega ,\varphi )P^{-}{\nu }_{\tau }$ decays, where $P^{-}={\pi }^{-}$ or $K^{-}$, are considered within a phenomenological model with dominance of meson intermediate states. We assume SU(3) flavor symmetry to fix some of the unknown strong interaction couplings. Our predictions for the ${\tau }^{-}\to \varphi ({\pi }^{-},K^{-}){\nu }_{\tau }$ branching fractions are in good agreement with recent measurements of the BABAR and BELLE Collaborations.

Using a sample of 1.8 million $D\overline{D}$ mesons collected at the $\psi (3770)$ with the CLEO-c detector, we study the semileptonic decays $D^0\to {\pi }^{-}{e}^{+}{\nu }_e$, $D^{+}\to {\pi }^0{e}^{+}{\nu }_e$, $D^0\to K^{-}{e}^{+}{\nu }_e$, and $D^{+}\to {\overline{K}}^0{e}^{+}{\nu }_e$. For the total branching fractions we find $\mathcal{B}(D^0\to {\pi }^{-}{e}^{+}{\nu }_e)=0.299(11)(9)\%$, $\mathcal{B}(D^{+}\to {\pi }^0{e}^{+}{\nu }_e)=0.373(22)(13)\%$, $\mathcal{B}(D^0\to K^{-}{e}^{+}{\nu }_e)=3.56(3)(9)\%$, and $\mathcal{B}(D^{+}\to {\overline{K}}^0{e}^{+}{\nu }_e)=8.53(13)(23)\%$, where the first error is statistical and the second systematic. In addition, form factors are studied through fits to the partial branching fractions obtained in five $q^2$ ranges. By combining our results with recent unquenched lattice calculations, we obtain $|V_{cd}|=0.217(9)(4)(23)$ and $|V_{cs}|=1.015(10)(11)(106)$, where the final error is theoretical.

In this paper we study the chiral symmetry breaking in the hard wall AdS/QCD model. We solve the equations of motion up to the second order at large momentum and obtain the first few terms in the expansion of the “left-right” correlator, which is the measure of symmetry breaking. We study the dependence on AdS radius to get the result as the series in ’t Hooft constant.

The spherically symmetric free radial oscillation in the first post-Newtonian approximation for a homogeneous and isotropic elastic sphere with a constant density is studied. Based on the Xu, Wu, and Soffel formalism, the relation of the oscillation frequency of the sphere with the radius, mass density, and elastic constants of the sphere is derived by using the successive approximation method.

We construct an explicit scenario whereby the same material driving inflation in the early universe can comprise dark matter in the present universe, using a simple quadratic potential. Following inflation and preheating, the density of inflaton/dark matter particles is reduced to the observed level by a period of thermal inflation, of a duration already invoked in the literature for other reasons. Within the context of the string landscape, one can further argue for a nonzero vacuum energy of this field, thus unifying inflation, dark matter, and dark energy into a single fundamental field.

We study orbifold compactifications of the type IIB superstring on ${\mathrm{AdS}}_5\times S^5/\Gamma$, where $\Gamma$ is the Abelian group $Z_8$, which can lead to non-supersymmetric three and four family models based on quartification. In particular, we focus on two models, one fully quartified model and one a model with two trinification families and one quartification family, which reduces to the standard model with a minimal leptonic color sector.

New data on the decays of the charmed particles $D^0$, $D^{+}$, and $D_s^{+}$ to pairs of light pseudoscalar mesons $P$ allow the testing of flavor symmetry and the extraction of key amplitudes. Information on relative strong phases is obtained. One sees evidence for the expected interference between Cabibbo-favored and doubly Cabibbo-suppressed decays in the differing patterns of $D^0\to K_{S,L}{\pi }^0$ and $D^{+}\to K_{S,L}{\pi }^{+}$ decays.

There have been many theoretical models constructed that aim to explain the neutrino masses and mixing patterns. While many of the models will be eliminated once more accurate determinations of the mixing parameters, especially ${sin}^{2}2{\theta }_{13}$, are obtained, charged lepton flavor violation experiments are able to differentiate even further among the models. In this paper, we investigate various rare lepton flavor violation processes, such as ${\ell }_i\to {\ell }_j+\gamma$ and $\mu -e$ conversion, in five predictive supersymmetric (SUSY) $SO(10)$ models and their allowed soft-SUSY breaking parameter space in the constrained minimal SUSY standard model. Utilizing the Wilkinson Microwave Anisotropy Probe dark matter constraints, we obtain lower bounds on the branching ratios of these rare processes and find that at least three of the five models we consider give rise to predictions for $\mu \to e+\gamma$ that will be tested by the MEG Collaboration at PSI. In addition, the next generation $\mu -e$ conversion experiment has sensitivity to the predictions of all five models, making it an even more robust way to test these models. While generic studies have emphasized the dependence of the branching ratios of these rare processes on the reactor neutrino angle ${\theta }_{13}$ and the mass of the heaviest right-handed neutrino $M_3$ we find very massive $M_3$ is more significant than large ${\theta }_{13}$ in leading to branching ratios near to the present upper limits.

Majorana features of neutrinos and SO(3) gauge symmetry of three families enable us to construct a gauge model of neutrino for understanding naturally the observed smallness of neutrino masses and the nearly tri-bimaximal neutrino mixing when combining together with the mechanism of approximate global U(1) family symmetry. The vacuum structure of SO(3) symmetry breaking is found to play an important role. The mixing angle ${\theta }_{13}$ and $CP$-violating phases governed by the vacuum of spontaneous symmetry breaking are in general nonzero and testable experimentally at the allowed sensitivity. The model predicts the existence of vectorlike SO(3) triplet charged leptons and vectorlike SO(3) triplet Majorana neutrinos as well as SO(3) tri-triplet Higgs bosons, some of them can be light and explored at the colliders LHC and ILC.

We consider thick brane configurations in a pure geometric Weyl integrable 5D space-time, a non-Riemannian generalization of Kaluza-Klein (KK) theory involving a geometric scalar field. Thus, the 5D theory describes gravity coupled to a self-interacting scalar field which gives rise to the structure of the thick branes. We continue the study of the properties of a previously found family of solutions which is smooth at the position of the brane but involves naked singularities in the fifth dimension. Analyzing their graviton spectrum, we find that a particularly interesting situation arises for a special case in which the 4D graviton is separated from the KK gravitons by a mass gap. The corresponding effective Schrödinger equation has a modified Pöschl-Teller potential and can be solved exactly. Apart from the massless 4D graviton, it contains one massive KK bound state, and the continuum spectrum of delocalized KK modes. We also discuss the mass hierarchy problem, and explicitly compute the corrections to Newton’s law in the thin brane limit.

We introduce and discuss the method of linear delta expansion for the calculation of effective potentials in superspace, by adopting the improved version of the super-Feynman rules. Calculations are carried out up to two loops and an expression for the optimized Kähler potential in the Wess-Zumino model is worked out.

The relation between two-time physics (2T-physics) and the ordinary one-time formulation of physics (1T-physics) is similar to the relation between a 3-dimensional object moving in a room and its multiple shadows moving on walls when projected from different perspectives. The multiple shadows as seen by observers stuck on the wall are analogous to the effects of the 2T-universe as experienced in ordinary 1T spacetime. In this paper we develop some of the quantitative aspects of this 2T to 1T relationship in the context of field theory. We discuss 2T field theory in $d+2$ dimensions and its shadows in the form of 1T field theories when the theory contains Klein-Gordon, Dirac and Yang-Mills fields, such as the standard model of particles and forces. We show that the shadow 1T field theories must have hidden relations among themselves. These relations take the form of dualities and hidden spacetime symmetries. A subset of the shadows are 1T field theories in different gravitational backgrounds (different space-times) such as the flat Minkowski spacetime, the Robertson-Walker expanding universe, ${\mathrm{AdS}}_{d-k}\times S^k$, and others, including singular ones. We explicitly construct the duality transformations among this conformally flat subset, and build the generators of their hidden $\mathrm{SO}(d,2)$ symmetry. The existence of such hidden relations among 1T field theories, which can be tested by both theory and experiment in 1T-physics, is part of the evidence for the underlying $d+2$ dimensional spacetime and the unifying 2T-physics structure.

A small mass $\mu$ in orbit about a much more massive black hole $m$ moves along a world line that deviates from a geodesic of the black hole geometry by $O(\mu /m)$. This deviation is said to be caused by the gravitational self-force of the metric perturbation $h_{ab}$ from $\mu$. For circular orbits about a nonrotating black hole we numerically calculate the $O(\mu /m)$ effects upon the orbital frequency and upon the rate of passage of proper time on the world line. These two effects are independent of the choice of gauge for $h_{ab}$ and are observable in principle. For distant orbits, our numerical results agree with a post-Newtonian analysis including terms of order $(v/c{)}^6$.

A model for a flat isotropic universe with a negative cosmological constant $\Lambda$ and a massless scalar field as sole matter content is studied within the framework of loop quantum cosmology. By application of the methods introduced for the model with $\Lambda =0$, the physical Hilbert space and the set of Dirac observables are constructed. As in that case, the scalar field plays here the role of an emergent time. The properties of the system are found to be similar to those of the $k=1$ Friedmann-Robertson-Walker (FRW) model: for small energy densities, the quantum dynamics reproduces the classical one, whereas, due to modifications at near-Planckian densities, the big bang and big crunch singularities are replaced by a quantum bounce connecting deterministically the large semiclassical epochs. Thus in loop quantum cosmology the evolution is qualitatively cyclic.

In gravity theories derived from a $f(R)$ Lagrangian, matter is usually supposed to be minimally coupled to the metric, which hence defines a “Jordan frame.” However, since the field equations are fourth order, gravity possesses an extra degree of freedom on top of the standard graviton, as is manifest from its equivalent description in the conformally related, Einstein, frame. We introduce explicitly this extra scalar degree of freedom in the action and couple it to matter, so that the original metric no longer defines a Jordan frame. This “detuning” puts $f(R)$ gravity into a wider class of scalar-tensor theories. We argue that a “chameleonlike” detuning tracing the background matter density may provide purely gravitational models which account for the present acceleration of the universe and evade local gravity constraints.

Based on the idea of the work by Wilczek and his collaborators, we consider the gravitational anomaly near a weakly isolated horizon. We find that there exists a universal choice of tortoise coordinate for any weakly isolated horizon. Under this coordinate, the leading behavior of a quite arbitrary scalar field near a horizon is a 2-dimensional chiral scalar field. This means we can extend the idea of Wilczek and his collaborators to more general cases and show the relation between gravitational anomaly and Hawking radiation is a universal property of a black hole horizon.