We consider a vectorial, confining $\mathrm{SU}(N)$ gauge theory with a variable number, $N_f$, of massless fermions transforming according to the fundamental representation. Using the Schwinger-Dyson and Bethe-Salpeter equations, we calculate the $S$ parameter in terms of the current-current correlation functions. We focus on values of $N_f$ such that the theory is in the crossover region between the regimes of walking behavior and QCD-like (nonwalking) behavior. Our calculations indicate that the contribution to $S$ from a given fermion decreases as one moves from the QCD-like to the walking regimes. The implications of this result for technicolor theories are discussed.

Recently, Diakonov and Petrov have suggested a formalism in the chiral quark soliton model allowing one to derive the 3-, 5-, 7-, …quark wave functions for the octet, decuplet, and antidecuplet. They have used this formalism and many strong approximations in order to estimate the exotic ${\Theta }^{+}$ width. The latter has been estimated to $\sim 4\mathrm{MeV}$. Besides they obtained that the 5-quark component of the nucleon is about 50% of its 3-quark component meaning that relativistic effects are not small. We have improved the technique by taking into account some relativistic corrections and considering the previously neglected 5-quark exchange diagrams. We also have computed all nucleon axial charges. It turns out that exchange diagrams affect very little Diakonov’s and Petrov’s results while relativistic corrections reduce the ${\Theta }^{+}$ width to $\sim 2\mathrm{MeV}$ and the 5- to 3-quark component of the nucleon ratio to 30%.

It has been recently conjectured by Selem and Wilczek [1] the existence of a $ss–[\overline{u}\overline{d}]$ meson due to strong correlations between the two light antiquarks. We make a detailed study of this system within a dynamical quark model which has proven to be successful in reproducing the most important features of low-energy hadron phenomenology. Our results, obtained within a parameter-free calculation, show that the antidiquark component of the $ss\overline{u}\overline{d}$ system indeed entails the stronger attraction, and drives its energy much lower than the $\overline{N}\Xi$ threshold, but still above the ${\overline{K}}^0{K}^{*-}$ or ${\overline{K}}^{*0}{K}^{-}$ thresholds. We have also studied the $cc\overline{u}\overline{d}$ and $bb\overline{u}\overline{d}$ systems. Exotic mesons are only expected to exist in the limit of large mass for the two-quark subsystem, $bb\overline{u}\overline{d}$, since the calculated mass is below the ${\overline{B}}^0{B}^{*-}$ or ${\overline{B}}^{*0}{B}^{-}$ thresholds.

The possibility of the resonance discovered in $J/\psi \to \gamma \omega \varphi$ by BESII as a candidate of $0^{++}$ $Q^2{\overline{Q}}^2$ state $f_0(1810)$ is investigated. Tests on the $Q^2{\overline{Q}}^2$ nature of $f_0(1810)$ are found: $f_0(1810)\to \omega \varphi$, $K^{*}{\overline{K}}^{*}$ are the two dominant decay channels and $f_0(1810)\to K\overline{K}$, $\eta \eta$, $\eta {\eta }^{\prime }$ are suppressed. The cross sections of $\gamma \gamma \to f_0(1810)\to \omega \varphi$, $K^{*}{\overline{K}}^{*}$ are estimated.

We study in detail the sensitivity of neutrino oscillation probabilities to the fundamental neutrino parameters and their possible determination through experiments. The first part of the paper is devoted to the broad theme of isolating regions in the neutrino (and antineutrino) energy and propagation length that are sensitive to the oscillation parameters. Such a study is relevant to neutrinos both from the Earth’s atmosphere or from a neutrino factory. For completeness we discuss the sensitivity, however small, to the parameters involved in a three-generation framework, and to the Earth matter density profile. We then study processes relevant to atmospheric neutrinos which are sensitive to and allow precision measurements of the mixing angle ${\theta }_{23}$ and mass-squared difference ${\delta }_{32}$ apart from the mixing angle ${\theta }_{13}$. Crucial to this analysis is charge identification; detectors having this capability can isolate these matter effects. In particular, we address the issue of using matter effects to determine whether the mixing angle ${\theta }_{23}$ is maximal, and, if not, to explore how well its octant can be determined. When realistic detector resolutions are included, we find that deviations of about 15% (20%) from a maximal value of ${sin}^2{\theta }_{23}=1/2$ can be measured at 95% (99%) C.L. provided ${\theta }_{13}$ is nonzero, ${sin}^2{\theta }_{13}\ge 0.015$, and the neutrino mass ordering is normal, with fairly large exposures of 1000 kton-years.

The weak nucleon axial-vector form factor for quasielastic interactions is determined using neutrino interaction data from the K2K Scintillating Fiber detector in the neutrino beam at KEK. More than 12 000 events are analyzed, of which half are charged-current quasielastic interactions ${\nu }_{\mu }n\to {\mu }^{-}p$ occurring primarily in oxygen nuclei. We use a relativistic Fermi gas model for oxygen and assume the form factor is approximately a dipole with one parameter, the axial-vector mass $M_A$, and fit to the shape of the distribution of the square of the momentum transfer from the nucleon to the nucleus. Our best fit result for $M_A=1.20\pm 0.12\mathrm{GeV}$. Furthermore, this analysis includes updated vector form factors from recent electron scattering experiments and a discussion of the effects of the nucleon momentum on the shape of the fitted distributions.

We discuss the effect of the supersymmetry breaking on the Mass Varying Neutrinos(MaVaNs) scenario. Especially, the effect mediated by the gravitational interaction between the hidden sector and the dark energy sector is studied. A model including a chiral superfield in the dark sector and the right-handed neutrino superfield is proposed. Evolutions of the neutrino mass and the equation of state parameter are presented in the model. It is remarked that only the mass of a sterile neutrino is variable in the case of the vanishing mixing between the left-handed and a sterile neutrino on cosmological time scale. The finite mixing makes the mass of the left-handed neutrino variable.

We present a new technique to extract information on the unitarity triangle from the study of $B\to K\pi \pi$ Dalitz plots. Using the sensitivity of Dalitz analyses to the absolute values and the phases of decay amplitudes and isospin symmetry, we obtain a new constraint on the elements of the CKM matrix. We discuss in detail the role of electroweak penguin contributions and outline future prospects.

Branching fraction and asymmetry measurements of charmless $B^{+}\to K^{*+}{h}_1^{+}{h}_2^{-}$ (where $h_{1,2}=K$, $\pi$) decays are presented, using a data sample of $232\times {10}^6$ ${\rm Y}(4S)\to B\overline{B}$ decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy $B$ factory. Using a maximum likelihood fit, the following branching fraction results were obtained: $\mathcal{B}(B^{+}\to K^{*+}{K}^{+}{K}^{-})=(36.2\pm 3.3\pm 3.6)\times {10}^{-6}$ and $\mathcal{B}(B^{+}\to K^{*+}{\pi }^{+}{\pi }^{-})=(75.3\pm 6.0\pm 8.1)\times {10}^{-6}$. Upper limits were set for $\mathcal{B}(B^{+}\to K^{*+}{\pi }^{+}{K}^{-})<11.8\times {10}^{-6}$ and $\mathcal{B}(B^{+}\to K^{*+}{K}^{+}{\pi }^{-})<6.1\times {10}^{-6}$ at 90% confidence level. The charge asymmetries for the decays $B^{+}\to K^{*+}{K}^{+}{K}^{-}$ and $B^{+}\to K^{*+}{\pi }^{+}{\pi }^{-}$ were measured to be ${\mathcal{A}}_{K^{*}KK}=0.11\pm 0.08\pm 0.03$ and ${\mathcal{A}}_{K^{*}\pi \pi }=0.07\pm 0.07\pm 0.04$, respectively. The first error quoted on branching fraction and asymmetry measurements is statistical and the second systematic.

We propose a unification scenario for supersymmetric intersecting brane models. The quarks and leptons are embedded into adjoint representations of $SO(32)$, which are obtained by type I string and broken by compactification on orbifolds. Its single unified gauge coupling can give rise to different gauge couplings below the unification scale, due to effects of magnetic fluxes. The crucial mechanism is brane recombination preserving supersymmetry.

We describe how the inclusion of the gluonic Polyakov loop incorporates large gauge invariance and drastically modifies finite temperature calculations in chiral quark models after color neutral states are singled out. This generates an effective theory of quarks and Polyakov loops as basic degrees of freedom. We find a strong suppression of finite temperature effects in hadronic observables triggered by approximate triality conservation (Polyakov cooling), so that while the center symmetry breaking is exponentially small with the constituent quark mass, chiral symmetry restoration is exponentially small with the pion mass. To illustrate the point we compute some low-energy observables at finite temperature and show that the finite temperature corrections to the low energy coefficients are $N_c$ suppressed due to color average of the Polyakov loop. Our analysis also shows how the phenomenology of chiral quark models at finite temperature can be made compatible with the expectations of chiral perturbation theory. The implications for the simultaneous center symmetry breaking/chiral symmetry restoration phase transition are discussed also.

We present an investigation of nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three-wave coupling coefficients and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfvén-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfvén wave frequency. The implication of our results to astrophysical dusty plasmas is discussed.

We construct approximate initial data for nonspinning black hole binary systems by asymptotically matching the 4-metrics of two tidally perturbed Schwarzschild solutions in isotropic coordinates to a resummed post-Newtonian 4-metric in ADMTT coordinates. The specific matching procedure used here closely follows the calculation in [N. Yunes, W. Tichy, B. J. Owen, and B. Bruegmann, gr-qc/0503011.], and is performed in the so-called buffer zone where both the post-Newtonian and the perturbed Schwarzschild approximations hold. The result is that both metrics agree in the buffer zone, up to the errors in the approximations. However, since isotropic coordinates are very similar to ADMTT coordinates, matching yields better results than in the previous calculation [N. Yunes, W. Tichy, B. J. Owen, and B. Bruegmann, gr-qc/0503011.], where harmonic coordinates were used for the post-Newtonian 4-metric. In particular, not only does matching improve in the buffer zone, but due to the similarity between ADMTT and isotropic coordinates the two metrics are also close to each other near the black hole horizons. With the help of a transition function we also obtain a global smooth 4-metric which has errors on the order of the error introduced by the more accurate of the two approximations we match. This global smoothed out 4-metric is obtained in ADMTT coordinates which are not horizon penetrating. In addition, we construct a further coordinate transformation that takes the 4-metric from global ADMTT coordinates to new coordinates which are similar to Kerr-Schild coordinates near each black hole, but which remain ADMTT further away from the black holes. These new coordinates are horizon penetrating and lead, for example, to a lapse which is everywhere positive on the $t=0$ slice. Such coordinates may be more useful in numerical simulations.

On the basis of the general principles of a gauge field theory, the gauge theory for the Poincaŕe-Weyl group is constructed. It is shown that tetrads are not true gauge fields, but represent functions of true gauge fields: Lorentzian, translational, and dilatational ones. The equations for gauge fields are obtained. Geometrical interpretation of the theory is developed demonstrating that as a result of localization of the Poincaré-Weyl group the space-time becomes a Weyl-Cartan space. The geometrical interpretation of a dilaton field as a component of the metric tensor of a tangent space in Weyl-Cartan geometry is also proposed.

The construction of initial data for black-hole binaries usually involves the choice of free parameters that define the spins of the black holes and essentially the eccentricity of the orbit. Such parameters must be chosen carefully to yield initial data with the desired physical properties. In this paper, we examine these choices in detail for the quasiequilibrium method coupled to apparent-horizon/quasiequilibrium boundary conditions. First, we compare two independent criteria for choosing the orbital frequency, the “Komar-mass condition” and the “effective-potential method,” and find excellent agreement. Second, we implement quasilocal measures of the spin of the individual holes, calibrate these with corotating binaries, and revisit the construction of nonspinning black-hole binaries. Higher-order effects, beyond those considered in earlier work, turn out to be important. Without those, supposedly nonspinning black holes have appreciable quasilocal spin; furthermore, the Komar-mass condition and effective-potential method agree only when these higher-order effects are taken into account. We compute a new sequence of quasicircular orbits for nonspinning black-hole binaries, and determine the innermost stable circular orbit of this sequence.

Weakly interacting massive particles (WIMPs) are part of the lepton-photon plasma in the early universe until kinetic decoupling, after which time the particles behave like a collisionless gas with nonzero temperature. The Boltzmann equation for WIMP-lepton collisions is reduced to a Fokker-Planck equation for the evolution of the WIMP distribution including scalar density perturbations. This equation and the Einstein and fluid equations for the plasma are solved numerically including the acoustic oscillations of the plasma before and during kinetic decoupling, the frictional damping occurring during kinetic decoupling, and the free-streaming damping occurring afterwards and throughout the radiation-dominated era. An excellent approximation reduces the solution to quadratures for the cold dark matter density and velocity perturbations. The subsequent evolution is followed through electron pair annihilation and the radiation-matter transition; analytic solutions are provided for both large and small scales. For a 100 GeV WIMP with bino-type interactions, kinetic decoupling occurs at a temperature $T_d=23\mathrm{MeV}$. The transfer function in the matter-dominated era leads to an abundance of small cold dark matter halos; with a smooth window function the Press-Schechter mass distribution is $dn/d\ln M\propto M^{-1/3}$ for $M<{10}^{-4}(T_d/10\mathrm{MeV}{)}^{-3}{\mathrm{M}}_{\odot }$.

Compact stars consisting of fermions with arbitrary masses and interaction strengths are studied by solving the structure equation of general relativity, the Tolman-Oppenheimer-Volkoff equations. Scaling solutions are derived for a free and an interacting Fermi gas and tested by numerical calculations. We demonstrate that there is a unique mass-radius relation for compact stars made of free fermions which is independent of the fermion mass. For sufficiently strong interactions, the maximum stable mass of compact stars and its radius are controlled by the parameter of the interaction, both increasing linearly with the interaction strength. The mass-radius relation for compact stars made of strongly interacting fermions shows that the radius remains approximately constant for a wide range of compact star masses.

The gauge-invariant three-gluon vertex obtained from the pinch technique is characterized by 13 nonzero form factors, which are given in complete generality for unbroken gauge theory at one loop. The results are given in $d$ dimensions using both dimensional regularization and dimensional reduction, including the effects of massless gluons and arbitrary representations of massive gauge bosons, fermions, and scalars. We find interesting relations between the functional forms of the contributions from gauge bosons, fermions, and scalars. These relations hold only for the gauge-invariant pinch-technique vertex and are $d$-dimensional incarnations of supersymmetric nonrenormalization theorems which include finite terms. The form factors are shown to simplify for $\mathcal{N}=1$, 2, and 4 supersymmetry in various dimensions. In four-dimensional nonsupersymmetric theories, eight of the form factors have the same functional form for massless gluons, quarks, and scalars, when written in a physically motivated tensor basis. For QCD, these include the tree-level tensor structure which has prefactor ${\beta }_0=(11N_c-2N_f)/3$, another tensor with prefactor $4N_c-N_f$, and six tensors with $N_c-N_f$. In perturbative calculations our results lead naturally to an effective coupling for the three-gluon vertex, $\tilde{\alpha }(k_1^2,k_2^2,k_3^2)$, which depends on three momenta and gives rise to an effective scale $Q_{\mathrm{eff}}^2(k_1^2,k_2^2,k_3^2)$ which governs the behavior of the vertex. The effects of nonzero internal masses $M$ are important and have a complicated threshold and pseudothreshold structure. A three-scale effective number of flavors $N_F(k_1^2/M^2,k_2^2/M^2,k_3^2/M^2)$ is defined. The results of this paper are an important part of a gauge-invariant dressed skeleton expansion and a related multiscale analytic renormalization scheme. In this approach the scale ambiguity problem is resolved since physical kinematic invariants determine the arguments of the couplings.

We study the (tree-level) weak radiative decays of $B$ mesons. We present a numerical estimate for the inclusive $b\to X_c\gamma (\gamma )$ modes based on the free-quark decay. We then review what is known for the $B\to D^{\star }\gamma$ modes in the framework of heavy quark effective theory and chiral perturbation theory. Finally, we extend these ideas to the double radiative decay modes $B\to D\gamma \gamma$. We find that the $b\to X_c\gamma \gamma$ rate is about an order of magnitude larger than the corresponding $b\to X_s\gamma \gamma$ rate. We also find the branching ratio for the $B\to D\gamma \gamma$ mode with most favorable CKM angles at the $\mathrm{\text{few}}\times {10}^{-8}$ level, comparable to predictions for $B\to K\gamma \gamma$.

We calculate production of quark-antiquark pairs in high energy proton-nucleus collisions both in the quasiclassical approximation of McLerran-Venugopalan model and including quantum small-$x$ evolution. The resulting production cross section is explicitly expressed in terms of Glauber-Mueller multiple rescatterings in the classical case and in terms of dipole-nucleus scattering amplitude in the quantum evolution case. We generalize the result of [K. Tuchin, Phys. Lett. B 593, 66 (2004).] beyond the aligned jet configurations. We expand on the earlier results of Blaizot, Gelis and Venugopalan [J. P. Blaizot, F. Gelis, and R. Venugopalan, Nucl. Phys. A743, 57 (2004).] by deriving quark production cross section including quantum evolution corrections in rapidity intervals both between the quarks and the target and between the quarks and the projectile.