We use the three-year WMAP observations to determine the normalization of the matter power spectrum in inflationary cosmologies. In this context, the quantity of interest is not the normalization marginalized over all parameters, but rather the normalization as a function of the inflationary parameters $n_{\mathrm{S}}$ and $r$ with marginalization over the remaining cosmological parameters. We compute this normalization and provide an accurate fitting function. The statistical uncertainty in the normalization is 3%, roughly half that achieved by COBE. We use the $k-\ell$ relation for the standard cosmological model to identify the pivot scale for the WMAP normalization. We also quote the inflationary energy scale corresponding to the WMAP normalization.

We have observed atmospheric gamma rays from 30 GeV to 8 TeV, using emulsion chambers at balloon altitudes, accumulating the largest total exposure in this energy range to date, $S\Omega T\sim 6.66{\mathrm{m}}^2\mathrm{sr}\mathrm{day}$. At very high altitudes, with residual overburden only a few $\mathrm{g}{\mathrm{cm}}^{-2}$, atmospheric gamma rays are mainly produced by a single interaction of primary cosmic rays with overlying atmospheric nuclei. Thus, we can use these gamma rays to study the spectrum of primary cosmic rays and their products in the atmosphere. From the observed atmospheric gamma-ray spectrum, we deconvolved the primary cosmic-ray proton spectrum, assuming appropriate hadronic interaction models. Our deconvolved proton spectrum covers the energy range from 200 GeV to 50 TeV, which fills a gap in the currently available primary cosmic-ray proton spectra. We also estimated the atmospheric muon spectrum above 30 GeV at high altitude from our gamma-ray spectrum, almost without reference to the primary cosmic rays, and compared the estimated flux with direct muon observations below 20 GeV.

We investigate a simple braneworld model in which the universe contains only cold dark matter and a cosmological constant, but the effective dark energy is phantomlike because of extra-dimensional gravity effects. Modified gravity screens the cosmological constant $\Lambda$, allowing for a larger $\Lambda$. In practice, observations do not favor any significant screening. We use supernova data, the cosmic microwave background shift parameter, and the baryon oscillation peak in the galaxy distribution to constrain the model. We find the mean value of ${\Omega }_{\mathrm{m}}$ with 68% confidence limits, and an upper limit on ${\Omega }_{\Lambda }$ at the 68% confidence level. The best-fit model is very close to a standard LCDM model, but the LCDM model provides a better fit since it has one less parameter.

The new 3 year WMAP data seem to confirm the presence of nonstandard large scale features in the cosmic microwave anisotropy power spectrum. While these features may hint at uncorrected experimental systematics, it is also possible to generate, in a cosmological way, oscillations on large angular scales by introducing a sharp step in the inflaton potential. Using current cosmological data, we derive constraints on the position, magnitude and gradient of a possible step. We show that a step in the inflaton potential, while strongly constrained by current data, is still allowed and may provide an interesting explanation to the currently measured deviations from the standard featureless spectrum. Moreover, we show that inflationary oscillations in the primordial power spectrum can significantly bias parameter estimates from standard ruler methods involving measurements of baryon oscillations.

We revisit the idea of using varying couplings to probe the nature of dark energy, in particular, by reconstructing its equation of state. We show that for the class of models studied this method can be far superior to the standard methods (using type Ia supernovae or weak lensing). We also show that the simultaneous use of measurements of the fine-structure constant $\alpha$ and the electron-to-proton mass ratio $\mu$ allows a direct probe of grand unification scenarios. We present forecasts for the sensitivity of this method, both for the near future and for the next generation of spectrographs—for the latter we focus on the planned CODEX instrument for ESO’s Extremely Large Telescope (formerly known as OWL). A high-accuracy reconstruction of the equation of state may be possible all the way up to redshift $z\sim 4$.

The computation of the spectrum of primordial perturbations, generated by a scalar field during the superinflationary phase of loop quantum cosmology, is revisited. The calculation is performed for two different cases. The first considers the dynamics of a massless field and it is found that scale invariance can only be achieved under a severe fine-tuning. The second assumes that the field evolves with a constant ratio between kinetic and potential energy, i.e. in a scaling solution. In this case, near scale invariance is a generic feature of the theory if the field rolls in a steep self-interaction potential.

It is commonly believed that the local hidden variable theories (LHVTs) can be tested through measuring the Bell inequalities. This scheme, for the massive particle system, was originally set up for the entangled $K^0{\overline{K}}^0$ pair system from the $\varphi$ factory. In this paper we show that the $J/\Psi \to K^0{\overline{K}}^0$ process is even more realistic for this goal. We analyze the unique properties of $J/\Psi$ in the detection of basic quantum effects, and find that it is possible to use $J/\Psi$ decay as a test of LHVTs in the future $\tau$-charm factory. Our analyses and conclusions are generally also true for other heavy onium decays.

Recent experimental improvements on $K$-decay data allow for a precise extraction of the strangeness-changing scalar $K\pi$ form factor and the related strange scalar spectral function. On the basis of this scalar as well as the corresponding pseudoscalar spectral function, the strange quark mass is determined to be $m_s(2\mathrm{GeV})=92\pm 9\mathrm{MeV}$. Further taking into account chiral perturbation theory mass ratios, the light up and down quark masses turn out to be $m_u(2\mathrm{GeV})=2.7\pm 0.4\mathrm{MeV}$ as well as $m_d(2\mathrm{GeV})=4.8\pm 0.5\mathrm{MeV}$. As a by-product, we also find a value for the Cabibbo angle $|V_{us}|=0.2236(29)$ and the ratio of meson decay constants $F_K/F_{\pi }=1.203(16)$. Performing a global average of the strange mass by including extractions from other channels as well as lattice QCD results yields $m_s(2\mathrm{GeV})=94\pm 6\mathrm{MeV}$.

We present results for different observables measured in semileptonic and nonleptonic decays of the $B_c^{-}$ meson. The calculations have been done within the framework of a nonrelativistic constituent quark model. In order to check the sensitivity of all our results against the interquark interaction we use five different quark-quark potentials. We obtain form factors, decay widths, and asymmetry parameters for semileptonic $B_c^{-}\to c\overline{c}$ and $B_c^{-}\to \overline{B}$ decays. In the limit of infinite heavy quark mass, our model reproduces the constraints of heavy quark spin symmetry. For the actual heavy quark masses we find nonetheless large corrections to that limiting situation for some form factors. We also analyze exclusive nonleptonic two-meson decay channels within the factorization approximation.

We consider several neutrino mass models in an extra-dimensional setting on a quantitative level. All the models are set in a five-dimensional scenario, with the standard model (SM) particles living on a brane, while three additional SM gauge singlets live in the bulk of an extra dimension, which is compactified on a $S^1/Z_2$ orbifold. The spontaneous breaking of an additional, continuous $U(1)$ family symmetry is used to generate suitable neutrino mass matrices via single right-handed neutrino dominance through the corresponding five-dimensional extension of the seesaw mechanism. In this manner, possible problems of this combination for some models in four dimensions could be overcome. The considered models differ with respect to the charges under the family symmetry and the nature of the five-dimensional Majorana mass term.

We report a measurement of the $t\overline{t}$ production cross section using the CDF II detector at the Fermilab Tevatron. The analysis is performed using $311{\mathrm{pb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a $b$-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be ${\sigma }_{t\overline{t}}=7.5\pm 2.1(\mathrm{stat}.{)}_{-2.2}^{+3.3}(\mathrm{syst}.{)}_{-0.4}^{+0.5}(\mathrm{lumi}.)\mathrm{pb}$, which is consistent with the standard model prediction.

The transfer of polarization from a high-energy positron to a ${\Lambda }^0$ hyperon produced in semiinclusive deep-inelastic scattering has been measured. The data have been obtained by the HERMES experiment at DESY using the 27.6 GeV longitudinally polarized positron beam of the HERA collider and unpolarized gas targets internal to the positron (electron) storage ring. The longitudinal spin-transfer coefficient is found to be $D_{L{L}^{\prime }}^{\Lambda }=0.11\pm 0.10(\mathrm{stat})\pm 0.03(\mathrm{syst})$ at an average fractional energy carried by the ${\Lambda }^0$ hyperon $⟨z⟩=0.45$. The dependence of $D_{L{L}^{\prime }}^{\Lambda }$ on both the fractional energy $z$ and the fractional longitudinal momentum $x_F$ is presented.

We consider the general formulation of non-Abelian fluid dynamics based on symmetry considerations. We point out that, quite generally, this admits solitonic excitations which are the color analog of Skyrmions. Some general properties of the solitons are discussed.

We consider an approximation procedure to evaluate the finite-temperature one-loop fermionic density in the presence of a chiral background field which systematically incorporates effects from inhomogeneities in the chiral field through a derivative expansion. We apply the method to the case of a simple low-energy effective chiral model which is commonly used in the study of the chiral phase transition, the linear $\sigma$-model coupled to quarks. The modifications in the effective potential and their consequences for the bubble nucleation process are discussed.

We study theories with 16 supercharges and a discrete energy spectrum. One class of theories has symmetry group $SU(2|4)$. They arise as truncations of $\mathcal{N}=4$ super Yang-Mills theory. They include the plane-wave matrix model, $2+1$ super Yang-Mills theory on $R\times S^2$ and $\mathcal{N}=4$ super Yang-Mills theory on $R\times S^3/Z_k$. We explain how to obtain their gravity duals in a unified way. We explore the regions of the geometry that are relevant for the study of some $1/2$ BPS and near BPS states. This leads to a class of two dimensional (4,4) supersymmetric sigma models with nonzero $H$ flux, including a massive deformed WZW model. We show how to match some features of the string spectrum with the Yang-Mills theory. The other class of theories are also connected to $\mathcal{N}=4$ super Yang-Mills theory and arise by making some of the transverse scalars compact. Their vacua are characterized by a 2D Yang-Mills theory or 3D Chern-Simons theory. These theories realize peculiar super-Poincaré symmetry algebras in $2+1$ or $1+1$ dimensions with “noncentral” charges. We finally discuss gravity duals of $\mathcal{N}=4$ super Yang-Mills theory on ${\mathrm{AdS}}_3\times S^1$.

Utilizing the ADM equations, we derive a metric and reduced field equations describing a general, spherically symmetric perfect fluid. The metric describes both the interior perfect fluid region and exterior vacuum Schwarzschild spacetime in a single coordinate patch. The exterior spacetime is in generalized Painleve-Gullstrand coordinates which is an infinite class of coordinate systems. In the static limit the system reduces to a Tolman-Oppenheimer-Volkoff equation on the interior with the exterior in Schwarzschild coordinates. We show the coordinate transformation for the nonstatic cases to comoving coordinates, where the metric is seen to be a direct generalization of the Lemaitre-Tolman-Bondi spacetime to include pressures.

By Polnarev’s method we analytically calculate the polarization spectra of the cosmic microwave background radiation (CMB) generated by cosmic relic gravitational waves (RGW). In this analytic approach the physics involved in this generating process is more transparent. Consequently, the effects due to various elements of physics can be isolated easily. In solving the equation for evolution of RGW in the expanding universe, both the sudden transition and the WKB approximation for the scale factor during the radiation-matter transition have been taken. To describe more precisely the decoupling process, we have introduced an analytic expression for the visibility function, consisting of two pieces of half-Gaussian curves. We also include the damping on polarizations due to the photon diffusion up to the second order of the tight coupling. Analytic polarization spectra $C_l^{XX}$ have been obtained with the following several improvements over the previous results. 1. The approximate analytic result is quite close to the numerical one evaluated from the cmbfast code, especially, for the first three peaks of the spectrum that are observable. By using the analytic exact solution of RGW in the sudden transition approximation, we have demonstrated the dependence of $C_l^{XX}$ on the dark energy and the baryons. 2. Our analytic half-Gaussian approximation of the visibility function fits better than the usual Gaussian model, and its time integration yields an analytic damping factor, which is parameter-dependent. This improves the spectra by $\sim 30\%$ around the second and third peaks. 3. The second order of tight coupling reduces the overall amplitude of $C_l^{XX}$ by 58%, comparing with the tight-coupling limit. 4. The influences of inflation on RGW and on CMB polarization are explicitly demonstrated.

The sensitivity of current searches for gravitational-wave bursts is limited by non-Gaussian, nonstationary noise transients which are common in real detectors. Existing techniques for detecting gravitational-wave bursts assume the output of the detector network to be the sum of a stationary Gaussian noise process and a gravitational-wave signal. These techniques often fail in the presence of noise nonstationarities by incorrectly identifying such transients as possible gravitational-wave bursts. Furthermore, consistency tests currently used to try to eliminate these noise transients are not applicable to general networks of detectors with different orientations and noise spectra. In order to address this problem we introduce a fully coherent consistency test that is robust against noise nonstationarities and allows one to distinguish between gravitational-wave bursts and noise transients in general detector networks. This technique does not require any a priori knowledge of the putative burst waveform.

We propose a minimal type II seesaw model by introducing only one right-handed neutrino besides the $SU(2{)}_L$ triplet Higgs to the standard model. In the usual type II seesaw models with several right-handed neutrinos, the contributions of the right-handed neutrinos and the triplet Higgs to the $CP$ asymmetry, which stems from the decay of the lightest right-handed neutrino, are proportional to their respective contributions to the light neutrino mass matrix. However, in our minimal type II seesaw model, this $CP$ asymmetry is just given by the one-loop vertex correction involving the triplet Higgs, even though the contribution of the triplet Higgs does not dominate the light neutrino masses. For illustration, the Fritzsch-type lepton mass matrices are considered.

We analyze a minimal supersymmetric standard model (MSSM) taking a minimal flavor violation structure at the GUT scale. We evaluate the parameters at the electroweak scale taking into account the full flavor structure in the evolution of the renormalization group equations. We concentrate mainly on the decay $B_s\to {\mu }^{+}{\mu }^{-}$ and its correlations with other observables like $\mathrm{BR}(b\to s\gamma )$, $\mathrm{BR}(b\to s{l}^{+}{l}^{-})$, $\Delta M_{B_s}$ and the anomalous magnetic moment of the muon. We restrict our analysis to the regions in parameter space consistent with the dark matter constraints. We find that the $\mathrm{BR}(B_s\to {\mu }^{+}{\mu }^{-})$ can exceed the current experimental limit in the regions of parameter space which are allowed by all other constraints thus providing an additional bound on supersymmetric parameters. This holds even in the constrained MSSM. Assuming a hypothetical measurement of $\mathrm{BR}(B_s\to {\mu }^{+}{\mu }^{-})\simeq {10}^{-7}$, we analyze the predicted MSSM spectrum and flavor violating decay modes of supersymmetric particles which are found to be small.