We discuss the effect of the time evolution of extra dimensions on CMB anisotropies and large-scale structure formation. We study the impact of scalar fields in a low-energy effective description of a general class of brane world models on the temperature anisotropy power spectrum. We show that when the coupling between these scalar fields and matter evolves over cosmological time scales, current observations of the CMB anisotropies can constrain primordial values of the fields in a manner complementary to local, late-time tests of gravity. We also present the effect of these fields on the polarization anisotropy spectra and the growth of large-scale structure, showing that future CMB observations will constrain theories of the Universe involving extra dimensions even further.

The DASI discovery of cosmic microwave background (CMB) polarization has opened a new chapter in cosmology. Most of the useful information about inflationary gravitational waves and reionization is on large angular scales where galactic foreground contamination is the worst, so a key challenge is to model, quantify, and remove polarized foregrounds. We use the POLAR experiment, COBE/DMR and radio surveys to provide the strongest limits to date on the TE cross-power spectrum of the CMB on large angular scales and to quantify the polarized synchrotron radiation, which is likely to be the most challenging polarized contaminant for the WMAP satellite. We find that the synchrotron E and B contributions are equal to within 10% from 408–820 MHz with a hint of E domination at higher frequencies. We quantify Faraday rotation and depolarization effects in the two-dimensional $(\mathcal{l},\nu )$ plane and show that they cause the synchrotron polarization percentage to drop both towards lower frequencies and towards lower multipoles.

We study the quark mass expansion of the axial-vector coupling constant $g_A$ of the nucleon. The aim is to explore the feasibility of chiral effective field theory methods for extrapolation of lattice QCD results—so far determined at relatively large quark masses corresponding to pion masses $m_{\pi }\gtrsim 0.6\mathrm{GeV}$—down to physical values of $m_{\pi }.$ We compare two versions of non-relativistic chiral effective field theory: One scheme restricted to pion and nucleon degrees of freedom only, and an alternative approach which incorporates explicit $\Delta \mathrm{}\left(1230\right)\mathrm{}$ resonance degrees of freedom. It turns out that, in order to approach the physical value of $g_A$ in a leading-one-loop calculation, the inclusion of the explicit $\Delta \mathrm{}\left(1230\right)\mathrm{}$ degrees of freedom is crucial. With information on important higher order couplings constrained from analyses of the $\pi \overrightarrow{N}\pi \pi N$ reaction, a chiral extrapolation function $g_A{(m}_{\pi })$ is obtained, which works well from the chiral limit across the physical point into the region of present lattice data. The resulting enhancement of $g_A{(m}_{\pi })$ near the physical pion mass is found to arise from an interplay between long- and short-distance physics.

We report on a lattice determination of the mass of the exotic $1^{-+}$ hybrid meson using an improved Kogut-Susskind action. Results from both quenched and dynamical quark simulations are presented. We also compare with earlier results using Wilson quarks at heavier quark masses. The results on lattices with three flavors of dynamical quarks show effects of sea quarks on the hybrid propagators which probably result from coupling to two meson states. We extrapolate the quenched results to the physical light quark mass to allow comparison with experimental candidates for the $1^{-+}$ hybrid meson. The lattice result remains somewhat heavier than the experimental result, although it may be consistent with the ${\pi }_1\mathrm{}\left(1600\right).$

We discuss the implications of recent experimental data for B decays into two pseudoscalar mesons, with an emphasis on those with $\eta$ and ${\eta }^{\prime }$ in the final states. Applying a U-spin argument, we show that tree and penguin amplitudes, both in $B^{+}\to {\pi }^{+}\eta$ and in $B^{+}\to {\pi }^{+}{\eta }^{\prime },$ are of comparable magnitudes. Nontrivial relative weak and strong phases between the tree-level amplitudes and penguin-loop amplitudes in the $B^{\pm }\to {\pi }^{\pm }\eta$ modes are extracted. We predict the possible values for the averaged branching ratio and CP asymmetry of the $B^{\pm }\to {\pi }^{\pm }{\eta }^{\prime }$ modes. We test the assumption of a singlet-penguin amplitude with the same weak and strong phases as the QCD penguin amplitude in explaining the large branching ratios of ${\eta }^{\prime }K$ modes, and show that it is consistent with current branching ratio and CP asymmetry data of the $B^{+}\to ({\pi }^0,\eta ,{\eta }^{\prime }{)K}^{+}$ modes. We also show that the strong phases of the singlet-penguin and tree-level amplitudes can be extracted with further input of electroweak penguin contributions and a sufficiently well-known branching ratio of the $\eta K^{+}$ mode. Using $\mathrm{SU}\left(3\right)\mathrm{}$ flavor symmetry, we also estimate required data samples to detect modes that have not yet been seen.

Matter density uncertainties can affect the measurements of the neutrino oscillation parameters at future neutrino factory experiments, such as the measurements of the mixing parameters ${\theta }_{13}$ and ${\delta }_{\mathrm{CP}}.$ We compare different matter density uncertainty models and discuss the possibility to include the matter density uncertainties in a complete statistical analysis. Furthermore, we systematically study in which measurements and where in the parameter space matter density uncertainties are most relevant. We illustrate this discussion with examples that show the effects as functions of different magnitudes of the matter density uncertainties. We find that matter density uncertainties are especially relevant for large ${\sin }^{2}2{\theta }_{13}\gtrsim {10}^{-3}.$ Within the KamLAND-allowed range, they are most relevant for the precision measurements of ${\sin }^{2}2{\theta }_{13}$ and ${\delta }_{\mathrm{CP}},$ but less relevant for “binary” measurements, such as for the sign of $\Delta m_{31}^2,$ the sensitivity to ${\sin }^{2}2{\theta }_{13},$ or the sensitivity to maximal $\mathrm{CP}$ violation. In addition, we demonstrate that knowing the matter density along a specific baseline better than to about $1\%$ precision means that all measurements will become almost independent of the matter density uncertainties.

We study the resummation of large QCD radiative corrections up to the next-to-leading logarithmic accuracy to the process $\gamma \overrightarrow{\gamma }b\overline{b};$ i.e., we resum logarithms of the type ${\alpha }_s^p{\ln }^{2p}{m}^2/s$ and ${\alpha }_s^p{\ln }^{2p-1}{m}^2/s$ $(m$ is the quark mass). The only source of all the logarithms to this accuracy is the off-shell Sudakov form factor included into the triangle topologies of the one-loop box diagram. We prove that any other configurations of diagrams to this accuracy either cancel in subgroups or develop a universal on-shell Sudakov exponent due to the final quark antiquark lines. We study the mechanism of cancellations between the different diagrams, which leads to the simple resummed results. We show the cancellation explicitly at three loops for the leading and at two loops for the next-to-leading logarithms. We also point out the general mechanism responsible for it, and discuss how it can be extended to higher orders.

We present a measurement of the mass difference ${m(D}_s^{+}\left)-{m(D}^{+}\right),$ where both the $D_s^{+}$ and $D^{+}$ are reconstructed in the $\phi {\pi }^{+}$ decay channel. This measurement uses 11.6 ${\mathrm{pb}}^{\mathrm{-}1}$ of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be ${m(D}_s^{+}\left)-{m(D}^{+}\right)=99.41\mathrm{}\pm 0.38\left(\mathrm{stat}\right)\pm 0.21\left(\mathrm{syst}\right)\mathrm{MeV}{/c}^2.$

Following the newly formulated notion of form invariance of the neutrino mass matrix, a complete model of leptons is constructed. It is based on a specific unitary $3\times 3$ matrix U in family space, such that $U^2$ is the simple discrete symmetry ${\nu }_e\to -{\nu }_e,$ ${\nu }_{\mu }\leftrightarrow {\nu }_{\tau }.$ Thus U also generates the cyclic group $Z_4.$ The charged-lepton mass matrix is nearly diagonal while the neutrino mass matrix is of a form suitable for explaining maximal (large) mixing in atmospheric (solar) neutrino oscillations in the context of three nearly degenerate neutrino masses. Observable lepton flavor violation is predicted. Quarks may be treated in the same way as charged leptons.

In this Brief Report we consider the coupling of a dark energy scalar such as quintessence to neutrinos and discuss its implications in studies on the neutrino mass limits from baryogenesis. During the evolution of the dark energy scalar, the neutrino masses vary; consequently the bounds on the neutrino masses we have here differ from those obtained before.

We investigate the electromagnetic radiation released during the high energy collision of a charged point particle with a four-dimensional Schwarzschild black hole. We show that the spectra is flat, and well described by a classical calculation. We also compare the total electromagnetic and gravitational energies emitted, and find that the former is suppressed in relation to the latter for very high energies. These results could apply to the astrophysical world in the case that charged stars and small charged black holes are out there colliding into large black holes, and to a very high energy collision experiment in a four-dimensional world. In this latter scenario the calculation is to be used for the moments just after black hole formation, when the collision of charged debris with the newly formed black hole is certainly expected. Since the calculation is four dimensional, it does not directly apply to TeV-scale gravity black holes, as these inhabit a world of six to eleven dimensions, although our results should qualitatively hold when extrapolated with some care to higher dimensions.

The density perturbations generated when the inflaton decay rate is perturbed by a light scalar field χ are studied. By explicitly solving the perturbation equations for the system of two scalar fields and radiation, we show that even in low energy-scale inflation nearly scale-invariant spectra of scalar perturbations with an amplitude set by observations are obtained through the conversion of χ fluctuations into adiabatic density perturbations. We demonstrate that the spectra depend on the average decay rate of the inflaton and on the inflaton fluctuations. We then apply this new mechanism to string cosmologies and generalized Einstein theories and discuss the conditions under which scale-invariant spectra are possible.

We study the so-called “sunset diagram,” which is one of two-loop self-energy diagrams, for scalar field theories at finite temperature. Explicit expressions for the real and imaginary parts of the thermal sunset diagram are obtained and they are numerically evaluated. This is done separately for the temperature independent and dependent parts of the diagram. For the former, the imaginary part is first found and the finite real part is then obtained through the imaginary part using a twice-subtracted dispersion relation. For the latter, we express it as a one-dimensional integral in terms of the bubble diagram, which is the one-loop subdiagram of the sunset diagram. As an application of our result, we study the effect of the diagram on the spectral function of the sigma meson at finite temperature in the linear sigma model, which was obtained at one-loop order previously. At high temperature where the decay $\overrightarrow{\sigma }\pi \pi$ is forbidden, the sigma meson acquires a finite width of the order of 10 MeV by the sunset diagram while its width vanishes within the one-loop calculation. At low temperature, the spectrum does not deviate much from that at one-loop order. Possible consequences with including other two-loop diagrams are discussed.

We examine the $\overrightarrow{B}\phi K$ decays within the framework of SUGRA models making use of the improved QCD factorization method of Beneke et al. which allows calculations of nonfactorizable contributions. All other experimental constraints $(\overrightarrow{B}{X}_s\gamma ,$ neutron and electron electric dipole moments, dark matter constraints, etc.) are imposed. We calculate the $\mathrm{CP}$ violating parameters $S_{\phi K_S},$ $C_{\phi K_S}$ and ${\mathcal{A}}_{\phi K^{\mp }}$ as well as the branching ratios (BRs) of $B^0$ and $B^{\pm },$ $\mathrm{Br}\left[\overrightarrow{B}\phi K\right].$ We find that, for the standard model (SM) and MSUGRA, it is not possible to account for the observed $2.7\sigma$ deviation between $S_{\phi K_S}$ and $S_{J/\psi K_S}.$ In general the BRs are also in $3\sigma$ disagreement with experiment, except in the parameter region where the weak annihilation terms dominate the decay (and hence where the theory is least reliable). Thus if future data confirm the current numbers, this would represent the first significant breakdown of both SM and MSUGRA. We show then that, adding a SUGRA nonuniversal cubic soft breaking left-right term mixing the second and third generations in either the down or up quark sector, all data can be accommodated for a wide range of parameters. The full $6\times 6$ quark mass matrices are used and the supersymmetric contributions calculated without approximation.

The matter and the pseudoscalar densities inside a hadron are calculated via gauge-invariant equal-time correlation functions. A comparison is made between the charge and the matter density distributions for the pion, the rho, the nucleon and the ${\Delta }^{+}$ within the quenched theory, and with two flavors of dynamical quarks.

In a continuation of an ongoing program, we use staggered chiral perturbation theory to calculate the one-loop chiral logarithms and analytic terms in the pseudoscalar meson leptonic decay constants $f_{{\pi }_5^{+}}$ and $f_{K_5^{+}}.$ We consider the partially quenched, “full QCD” (with three dynamical flavors), and quenched cases.

Using the measured spectrum shape for $\overrightarrow{B}\pi \mathcal{l}\nu ,$ the rate for $B^{+}\to {\pi }^{+}{\pi }^0,$ information on the Cabibbo-Kobayashi-Maskawa matrix element $|V_{\mathrm{ub}}|,$ and theoretical inputs from factorization and lattice gauge theory, we obtain an improved estimate of the “tree” contribution to $B^0\to {\pi }^{+}{\pi }^{-}.$ We find the branching ratio $\mathcal{B}{(B}^0\to {\pi }^{+}{\pi }^{-}\left){|}_{\mathrm{tree}}{=(5.25\mathrm{}}_{-0.50}^{+1.67\mathrm{}}\right)\times {10}^{-6}$ to be compared with the experimental value $\mathcal{B}{(B}^0\to {\pi }^{+}{\pi }^{-})=(4.55\mathrm{}\pm 0.44)\times {10}^{-6}.$ The fit implies $|V_{\mathrm{ub}}|=(3.62\mathrm{}\pm 0.34)\times {10}^{-3}.$ Implications for tree-penguin interference in $B^0\to {\pi }^{+}{\pi }^{-}$ and for other charmless B decays are discussed.

The decays $\overrightarrow{\omega }2{\pi }^{+}2{\pi }^{-}{\pi }^0$ and $\overrightarrow{\omega }{\pi }^{+}{\pi }^{-}3{\pi }^0$ are reconsidered in the hidden local symmetry approach (HLS) with added anomalous terms. The decay amplitudes are analyzed in detail, paying special attention to the Adler condition of the vanishing of the whole amplitude at a vanishing of momentum of any final pion. Combining the Okubo-Zweig-Iizuka rule applied to the five-pion final state with the Adler condition, we also calculate the $\overrightarrow{\phi }2{\pi }^{+}2{\pi }^{-}{\pi }^0$ and $\overrightarrow{\phi }{\pi }^{+}{\pi }^{-}3{\pi }^0$ decay amplitudes. The partial widths of the above decays are evaluated, and the excitation curves in $e^{+}{e}^{-}$ annihilation are obtained, assuming specific reasonable relations among the parameters characterizing the anomalous terms of the HLS Lagrangian. The evaluated branching ratios $B_{\overrightarrow{\phi }{\pi }^{+}{\pi }^{-}3{\pi }^0}\approx 2\times {10}^{-7}$ and $B_{\overrightarrow{\phi }2{\pi }^{+}2{\pi }^{-}{\pi }^0}\approx 7\times {10}^{-7}$ are such that, with the luminosity $L=500\mathrm{}{\mathrm{pb}}^{-1}$ attained at the $\mathrm{DA}\Phi \mathrm{NE}$ $\phi$ factory, one may already possess about 1685 events of the $\overrightarrow{\phi }5\pi$ decays.

We investigate the issue of charge neutrality of the $\mathrm{CFL}{K}^0$ phase of dense quark matter using the low energy effective theory of high density QCD. We show that the local electric and color charge neutrality of the ground state in a homogeneous color superconducting medium follows from its dynamics. We also consider the situation of a spatially inhomogeneous medium, such as may be found in a neutron star core. We find that spatial inhomogeneity results in the generation of electric fields, and positrons and/or electrons may be present in the ground state. We estimate the concentration of charged leptons in the ground state to be $n_e\sim {10}^2{\mathrm{cm}}^{-3}$ and consider their influence on the opacity of the medium with respect to the modified photons.

The weak-boson fusion process is expected to provide crucial information on Higgs boson couplings at the Large Hadron Collider at CERN. The achievable statistical accuracy demands comparison with next-to-leading order QCD calculations, which are presented here in the form of a fully flexible parton Monte Carlo program. QCD corrections are determined for jet distributions and are shown to be modest, of the order of 5%–10% in most cases, but reaching 30% occasionally. Remaining scale uncertainties range from the order of 5% or less for distributions to below $\pm 2\%$ for the Higgs boson cross section in typical weak-boson fusion search regions.