The chromopolarizability of a quarkonium state is a measure of the amplitude of the $E1\mathrm{\text{−}}E1$ chromoelectric interaction of the quarkonium with soft gluon fields and can be measured in the heavy quarkonium decays. Based on the chiral unitary approach, formulas with modification caused by the $S$ wave $\pi \pi$ final state interaction (FSI) for measuring the chromopolarizabilities are given. It is shown that the effect of the $S$ wave $\pi \pi$ FSI is very important in extracting chromopolarizabilities from the experimental data. The resultant values with the FSI are reduced to about $1/3$ of those determined without the FSI. The consequences of the FSI correction in the $J/\psi$-nucleon scattering near the threshold are also discussed. The estimated lower bound of the total cross section is reduced from about 17 mb to 2.9 mb, which agrees with the experimental data point and is compatible with the previously estimated values in the literature. In order to understand the interaction of heavy quarkonia with light hadrons at low energies better and to obtain the chromopolarizabilities of quarkonia accurately, more data should be accumulated. This can be done in the $J/\psi \to {\pi }^{+}{\pi }^{-}{l}^{+}{l}^{-}$ decay at BES-III and CLEO-c and in the ${\rm Y}\to {\pi }^{+}{\pi }^{-}{l}^{+}{l}^{-}$ decay at $B$ factories.

We investigate the branching ratios and $CP$ asymmetries of the $B\to \pi \pi$ processes measured in $B$ factory experiments. Fits to the experimental data of this process indicate a large ratio of color-suppressed ($C$) to color-allowed ($T$) tree contributions. We investigate whether the large $C/T$ can be explained within the QCD-based model computation with i) a large effect from the end point singularity or with ii) large final-state-interaction phase between two different isospin amplitudes. We show that the current experimental data do not exclude either possibility, but we may be able to distinguish these two effects in future measurements of direct $CP$ asymmetry of $B^0\to {\pi }^0{\pi }^0$.

Using data taken with the CLEO III detector at the Cornell Electron Storage Ring, we have investigated the direct photon spectrum in the decays ${\rm Y}(1\mathrm{S})\to \gamma gg$, ${\rm Y}(2\mathrm{S})\to \gamma gg$, ${\rm Y}(3\mathrm{S})\to \gamma gg$. The latter two of these are first measurements. Our analysis procedures differ from previous ones in the following ways: (a) background estimates (primarily from ${\pi }^0$ decays) are based on isospin symmetry rather than a determination of the ${\pi }^0$ spectrum, which permits measurement of the ${\rm Y}(2\mathrm{S})$ and ${\rm Y}(3\mathrm{S})$ direct photon spectra without explicit corrections for ${\pi }^0$ backgrounds from, e.g., ${\chi }_{bJ}$ states, (b) we estimate the branching fractions with a parametrized functional form (exponential) used for the background, and c) we use the high-statistics sample of ${\rm Y}(2\mathrm{S})\to \pi \pi {\rm Y}(1\mathrm{S})$ to obtain a tagged sample of ${\rm Y}(1\mathrm{S})\to \gamma +X$ events, for which there are no QED backgrounds. We determine values for the ratio of the inclusive direct photon decay rate to that of the dominant three-gluon decay ${\rm Y}\to ggg(R_{\gamma }=B(gg\gamma )/B(ggg))$ to be $R_{\gamma }(1\mathrm{S})=(2.70\pm 0.01\pm 0.13\pm 0.24)\%$, $R_{\gamma }(2\mathrm{S})=(3.18\pm 0.04\pm 0.22\pm 0.41)\%$, and $R_{\gamma }(3\mathrm{S})=(2.72\pm 0.06\pm 0.32\pm 0.37)\%$, where the errors shown are statistical, systematic, and theoretical model dependent, respectively. Given a value of $Q^2$, one can estimate a value for the strong coupling constant ${\alpha }_s(Q^2)$ from $R_{\gamma }$.

The most precise comparison between theory and experiment for the $B\to X_s{\ell }^{+}{\ell }^{-}$ rate is in the low $q^2$ region, but the hadronic uncertainties associated with an experimentally required cut on $m_X$ potentially spoil the search for new physics in these decays. We show that a 10%–30% reduction of $\mathrm{d}\Gamma (B\to X_s{\ell }^{+}{\ell }^{-})/\mathrm{d}{q}^2$ due to the $m_X$ cut can be accurately computed using the $B\to X_s\gamma$ shape function. The effect is universal for all short distance contributions in the limit $m_X^2\ll m_B^2$, and this universality is spoiled neither by realistic values of the $m_X$ cut nor by ${\alpha }_s$ corrections. Both the differential decay rate and forward-backward asymmetry with an $m_X$ cut are computed.

Starting from the Kadanoff-Baym relativistic transport equation and the multiple scattering expansion of the self-energy, we obtain the Boltzmann collision terms for any number of participating particles to all orders in perturbation theory within a quasiparticle approximation. This work completes a program initiated by Carrington and Mrówczyński and developed further by present authors and Weinstock in recent literature.

The general metric for conformally flat stationary cyclic symmetric noncircular spacetimes is explicitly derived. In spite of the complexity (due to the noncircular contributions) of the partial differential equations arising from the conformal flatness constraints, they allow for their complete integration in terms of elementary functions. A canonical coordinate representation of the search metric structure is given. Conditions for the existence of a rotation axis (axisymmetry) are established; these conditions coincide with those which restrict the studied noncircular class of spacetimes to be static. As a consequence, a previously known theorem by Collinson is just a part of a more general result: any conformally flat stationary cyclic symmetric spacetime (even a noncircular one) is additionally axisymmetric if and only if it is also static. Recent astrophysical motivations point in the direction of considering stationary noncircular configurations to describe magnetized neutron stars.

The periodic standing-wave approach to binary inspiral assumes rigid rotation of gravitational fields and hence helically symmetric solutions. To exploit the symmetry, numerical computations must solve for “helical scalars,” fields that are functions only of corotating coordinates, the labels on the helical Killing trajectories. Here we present the formalism for describing linearized general relativity in terms of helical scalars and we present solutions to the mixed partial differential equations of the linearized gravity problem (and to a toy nonlinear problem) using the adapted coordinates and numerical techniques previously developed for scalar periodic standing-wave computations. We argue that the formalism developed may suffice for periodic standing-wave computations for post-Minkowskian computations and for full general relativity.

We carry out numerical investigations of the dynamics and perturbations in the Nflation model of Dimopoulos et al. (2005). This model features large numbers of scalar fields with different masses, which can cooperate to drive inflation according to the assisted inflation mechanism. We extend previous work to include random initial conditions for the scalar fields, and explore the predictions for density perturbations and the tensor-to-scalar ratio. The tensor-to-scalar ratio depends only on the number of $e$-foldings and is independent of the number of fields, their masses, and their initial conditions. It therefore always has the same value as for a single massive field. By contrast, the scalar spectral index has significant dependence on model parameters. While normally multifield inflation models make predictions for observable quantities which depend also on the unknown field initial conditions, we find evidence of a “thermodynamic“ regime whereby the predicted spectral index becomes independent of initial conditions if there are enough fields. Only in parts of parameter space where the mass spectrum of the fields is extremely densely packed is the model capable of satisfying the tight observational constraints from WMAP3 observations.

Most analysis of cosmic microwave background spherical harmonic coefficients $a_{\ell m}$ has focused on estimating the power spectrum $C_{\ell }=⟨|a_{\ell m}{|}^2⟩$ rather than the coefficients themselves. We present a minimum-variance method for measuring $a_{\ell m}$ given anisotropic noise, incomplete sky coverage and foreground contamination, and apply it to the Wilkinson Microwave Anisotropy Probe (WMAP) data. Our method is shown to constitute lossless data compression in the sense that the widely used quadratic estimators of the power spectrum $C_{\ell }$ can be computed directly from our $a_{\ell m}$-estimators. As the Galactic cut is increased, the error bars $\Delta a_{\ell m}$ on low multipoles go from being dominated by foregrounds to being dominated by leakage from other multipoles, with the intervening minimum defining the optimal cut. Applying our method to the WMAP quadrupole and octopole as an illustration, we investigate the robustness of the previously reported “axis of evil” alignment to Galactic cut and foreground contamination.

The Dvali-Gabadadze-Porrati (DGP) braneworld model provides a simple alternative to the standard lambda cold dark matter cosmology, with the same number of parameters. There is no dark energy—the late universe self-accelerates due to an infrared modification of gravity. We compute the joint constraints on the DGP model from supernovae, the cosmic microwave background shift parameter, and the baryon oscillation peak in the Sloan Digital Sky Survey luminous red galaxy sample. Flat DGP models are within the joint 2 sigma contour, but the lambda cold dark matter model provides a significantly better fit to the data. These tests are based on the background dynamics of the DGP model, and we comment on further tests that involve structure formation.

We formulate statistical isotropy of CMB anisotropy maps in its most general form. We also present a fast and orientation independent statistical method to determine deviations from statistical isotropy in CMB polarization maps. The importance of having statistical tests of departures from SI for CMB polarization maps lies not only in interesting theoretical motivations but also in testing cleaned CMB polarization maps for observational artifacts such as residuals from polarized foreground emission. We propose a generalization of the bipolar power spectrum (BiPS) to polarization maps. Application to the observed CMB polarization maps will be soon possible after the release of WMAP 3 yr data. As a demonstration we show that for $E$-polarization this test can detect the breakdown of statistical isotropy due to polarized synchrotron foreground.

The article contains new results for spin-$3/2$ and -$1/2$ resonances. It specializes to the second resonance region, which includes the $P_{11}(1440)$, $D_{13}(1520)$ and $S_{11}(1535)$ resonances. New data on electroproduction enable us to determine the vector form factors accurately. Estimates for the axial couplings are obtained from decay rates of the resonances with the help of the partially conserved axial current (PCAC) hypothesis. We present cross sections to be compared with the running and future experiments. The article is self-contained and allows the reader to write simple programs for reproducing the cross sections and for obtaining additional differential cross sections.

We search for the production of doubly charmed baryons in $e^{+}{e}^{-}$ annihilations at or near a center-of-mass energy of 10.58 GeV, in a data sample with an integrated luminosity of $232{\mathrm{fb}}^{-1}$ recorded with the BABAR detector at the PEP-II storage ring at the Stanford Linear Accelerator Center. We search for ${\Xi }_{cc}^{+}$ baryons in the final states ${\Lambda }_c^{+}{K}^{-}{\pi }^{+}$ and ${\Xi }_c^0{\pi }^{+}$, and ${\Xi }_{cc}^{++}$ baryons in the final states ${\Lambda }_c^{+}{K}^{-}{\pi }^{+}{\pi }^{+}$ and ${\Xi }_c^0{\pi }^{+}{\pi }^{+}$. We find no evidence for the production of doubly charmed baryons.

A search has been made for the decays $B^{+}\to \varphi {\pi }^{+}$ and $B^0\to \varphi {\pi }^0$ in a data sample of approximately $232\times {10}^6$ $B\overline{B}$ pairs recorded at the ${\rm Y}(4S)$ resonance with the BABAR detector at the PEP-II $B$-meson Factory at SLAC. No significant signals have been observed, and therefore upper limits have been set on the branching fractions: $\mathcal{B}(B^{+}\to \varphi {\pi }^{+})<2.4\times {10}^{-7}$ and $\mathcal{B}(B^0\to \varphi {\pi }^0)<2.8\times {10}^{-7}$ at 90% probability.

We consider global monopoles as well as black holes with global monopole hair in an Einstein-Goldstone model with a cosmological constant in four spacetime dimensions. Similar to the $\Lambda =0$ case, the mass of these solutions defined in the standard way diverges. We use a boundary counterterm subtraction method to compute the mass and action of $\Lambda \ne 0$ configurations. The mass of the asymptotically de Sitter solutions computed in this way turns out to take positive values in a specific parameter range and, for a relaxed set of asymptotic boundary conditions, yields a counterexample to the maximal mass conjecture.

Lattice QCD with $N_f=2$ flavors of sea quark is used to explore the spectrum and decay of scalar mesons. We are able to determine the $b_1-a_0$ mass difference and this leads to the conclusion that the lightest nonsinglet scalar meson ($a_0$) has a mass of 1.01(4) GeV. We determine from the lattice the coupling strength to KK and $\pi \eta$. We compute the leptonic decay constant of the lightest nonsinglet scalar meson. We discuss the impact of these lattice results on the interpretation of the $a_0(980)$ state. We also discuss $K_0^{*}$ states.

The decay of the standard model Higgs boson into four leptons via a virtual $W$- or $Z$-boson pair is one of the most important decay modes in the Higgs-boson search at the Large Hadron Collider. We present the complete electroweak radiative corrections of $\mathcal{O}(\alpha )$ to these processes, including improvements beyond $\mathcal{O}(\alpha )$ originating from heavy-Higgs effects and final-state radiation. The intermediate $W$- and $Z$-boson resonances are described (without any expansion or on-shell approximation) by consistently employing complex mass parameters for the gauge bosons (complex-mass scheme). The corrections to partial decay widths typically amount to some percent and increase with growing Higgs mass $M_H$, reaching about 8% at $M_H\sim 500\mathrm{GeV}$. For not too large Higgs masses ($M_H\lesssim 400\mathrm{GeV}$) the corrections to the partial decay widths can be reproduced within $\lesssim 2\%$ by simple approximations. For angular distributions the corrections are somewhat larger and distort the shapes. For invariant-mass distributions of fermion pairs they can reach several tens of percent depending on the treatment of photon radiation. The discussed corrections have been implemented in a Monte Carlo event generator called Prophecy4f.

Complete one-loop parametrization of the linear sigma model is performed and the phase boundary between first order and crossover transition regions of the $m_{\pi }-m_K$-plane is determined using the optimized perturbation theory as a resummation tool of perturbative series. Away from the physical point the parameters of the model were determined by making use of chiral perturbation theory. Along the diagonal $m_{\pi }=m_K$ of the mass plane we estimate $m_{\pi }^c=110\pm 20\mathrm{MeV}$. The location of the tricritical point on the $m_{\pi }=0$ axis is estimated in the interval $m_K^{\mathrm{TCP}}\in (1700\hspace{0.17em}1850)\mathrm{MeV}$.

Small distortions in the observed shapes of distant galaxies, a cosmic shear due to gravitational lensing, can be used to simultaneously determine the distance-redshift relation, $r(z)$, and the density contrast growth factor, $g(z)$. Both of these functions are sensitive probes of the acceleration. Their simultaneous determination allows for a consistency test and provides sensitivity to physics beyond the standard dark energy paradigm.

We investigate the effect of hyperon matter including hyperon-hyperon interaction on bulk viscosity. Equations of state are constructed within the framework of a relativistic field theoretical model where baryon-baryon interaction is mediated by the exchange of scalar and vector mesons. Hyperon-hyperon interaction is also taken into account by the exchange of two strange mesons. This interaction results in a smaller maximum mass neutron star compared with the case without the interaction. The coefficient of bulk viscosity due to the nonleptonic weak process is determined by these equations of state. The interacting hyperon matter reduces the bulk viscosity coefficient in a neutron star interior compared with the no interaction case. The $r$-mode instability is more effectively suppressed in the hyperon-hyperon interaction case than in that without the interaction.