There is a striking suppression of the cross section for production of octet baryons in $e^{+}{e}^{-}$ annihilation, as the mass of the produced hadron increases. We present a simple parametrization for the fragmentation functions into octet baryons guided by two input models: the SU(3) flavor symmetry part is given by a quark-diquark model, and the baryon mass suppression part is inspired by the string model. We need only eight free parameters to describe the fragmentation functions for all octet baryons. These free parameters are determined by a fit to the experimental data of octet baryon production in $e^{+}{e}^{-}$ annihilation. Then we apply the obtained fragmentation functions to predict the cross section of the octet baryon production in charged lepton deep inelastic scattering and find consistency with the available experimental data. Furthermore, baryon production in pp collisions is suggested to be an ideal domain to check the predicted mass suppression.

We discuss the relation between leptogenesis and the Maki-Nakagawa-Sakata (MNS) phases in the class of seesaw models called light sequential dominance in which the right-handed neutrinos dominate sequentially, with the dominant right-handed neutrino being the lightest one. The heaviest right-handed neutrino then decouples, leaving effectively two right-handed neutrinos. Light sequential dominance is motivated by $\mathrm{SO}\left(10\right)\mathrm{}$ models which predict three right-handed neutrinos. With an approximate Yukawa texture zero in the 11 position there are only two seesaw phases which are simply related to the MNS phase measurable at a neutrino factory and the leptogenesis phase. The leptogenesis phase is predicted to be equal to the neutrinoless double beta decay phase.

We study the effects of instantons on the charged pion electromagnetic form factor at intermediate momenta. In the single instanton approximation (SIA), we predict the pion form factor in the kinematic region $Q^2=2\mathrm{}–10{\mathrm{GeV}}^2.$ By developing the calculation in a mixed time-momentum representation, it is possible to maximally reduce the model dependence and to calculate the form factor directly. We find the intriguing result that the SIA calculation coincides with the vector dominance monopole form, up to a surprisingly high momentum transfer $Q^2\sim 10{\mathrm{GeV}}^2.$ This suggests that vector dominance for the pion holds beyond low energy nuclear physics.

We propose an ansatz for the equations of motion of the noncommutative model of a tachyonic scalar field interacting with a gauge field, which allows one to find time-dependent solutions describing decaying solitons. These correspond to the collapse of lower dimensional branes obtained through tachyon condensation of unstable brane systems in string theory.

We calculate the gravitational radiation from a cusp of the chiral cosmic strings as a function of the current on the string in the limit of small values of the current. The smoothing of the cosmic string cusp due to the presence of the superconducting current on the string leads to different behavior of the gravitational radiation from the cusp as compared with the nonsuperconducting (ordinary) string. The difference between the gravitational energy radiation from the chiral cusp and the ordinary one is proportional to the value of the current on the string. It is shown that there is a high-frequency cutoff in the spectrum of the gravitational radiation from the chiral string. The frequency cutoff depends on the value of the string current. This effect is crucial for the detection of gravitation wave bursts from cosmic strings: the rather large current on the string would lower the amplitude of the incoming signal.

A formulation is developed for general relativistic ideal magnetohydrodynamics in stationary axisymmetric spacetimes. We reduce basic equations to a single second-order partial differential equation, the so-called Grad-Shafranov (GS) equation. Our formulation is most general in the sense that it is applicable even when a stationary axisymmetric spacetime is noncircular, that is, even when it is impossible to foliate a spacetime with two orthogonal families of two-surfaces. The GS equation for noncircular spacetimes is crucial for the study of relativistic stars with a toroidal magnetic field or meridional flow, such as magnetars, since the existence of a toroidal field or meridional flow violates the circularity of a spacetime. We also derive the wind equation in noncircular spacetimes, and discuss various limits of the GS equation.

We discuss the properties of a 4-dimensional Schwarzschild black hole in a spacetime where one of the spatial dimensions is compactified. As a result of the compactification the event horizon of the black hole is distorted. We use Weyl coordinates to obtain the solution describing such a distorted black hole. This solution is a special case of the Israel-Khan metric. We study the properties of the compactified Schwarzschild black hole, and develop an approximation which allows one to find the size, shape, surface gravity, and other characteristics of the distorted horizon with a very high accuracy in a simple analytical form. We also discuss the possible instabilities of a black hole in compactified space.

We discuss the spectrum of screening masses in a pure gauge theory near the deconfinement temperature from the point of view of the dimensionally reduced model describing the spontaneous breaking of the center symmetry. Universality arguments can be used to predict the values of the mass ratios in the scaling region of the deconfined phase when the transition is of second order. One such prediction is that the scalar sector of the screening spectrum in $\mathrm{SU}\left(2\right)\mathrm{}$ pure gauge theory contains a bound state of the fundamental excitation, corresponding through universality to the bound state found in the 3D Ising model and ${\phi }^4$ theory in the broken symmetry phase. A Monte Carlo evaluation of the screening masses in the gauge theory confirms the validity of the prediction. We briefly discuss the possibility of using similar arguments for first order deconfinement transitions and, in particular, for the physically relevant case of $\mathrm{SU}\left(3\right).$

The polynomiality condition, i.e., the property that Mellin moments of generalized parton distributions are even polynomials in the skewedness parameter $\xi ,$ is a demanding check of consistency for model approaches. We demonstrate that the helicity generalized parton distributions in the chiral quark-soliton model satisfy the polynomiality property. The proof contributes to the demonstration that the description of generalized parton distributions in the model is consistent.

In the frame of the Kerr-Schild approach, we consider the complex structure of Kerr geometry which is determined by a complex world line of a complex source. The real Kerr geometry is represented as a real slice of this complex structure. The Kerr geometry is generalized to the nonstationary case when the current geometry is determined by a retarded time and is defined by a retarded-time construction via a given complex world line of source. A general exact solution corresponding to arbitrary motion of a spinning source is obtained. The acceleration of the source is accompanied by a lightlike radiation along the principal null congruence. It generalizes to the rotating case, the known Kinnersley class of “photon rocket” solutions.

We consider a Brans-Dicke scalar field stabilized by a general power law potential with a power index n at a finite equilibrium value. Redshifting matter induces oscillations of the scalar field around its equilibrium due to the scalar field coupling to the trace of the energy momentum tensor. If the stabilizing potential is sufficiently steep these high frequency oscillations are consistent with observational and experimental constraints for arbitrary values of the Brans-Dicke parameter $\omega .$ We study analytically and numerically the equation of state of these high frequency oscillations in terms of the parameters $\omega$ and n and find the corresponding evolution of the universe scale factor. We find that the equation of state parameter can be negative and less than -1 but it is not related to the evolution of the scale factor in the usual way. Nevertheless, accelerating expansion is found for a certain parameter range. Our analysis applies also to oscillations of the size of extra dimensions (the radion field) around an equilibrium value. This duality between self-coupled Brans-Dicke and radion dynamics is applicable for $\omega =-1+1/D$ where D is the number of extra dimensions.

We show that the first year results of the Wilkinson Microwave Anisotropy Probe (WMAP) constrain very efficiently the energy density in relativistic particles in the Universe. We derive new bounds on additional relativistic degrees of freedom expressed in terms of an excess in the effective number of light neutrinos $\Delta N_{\mathrm{eff}}.$ Within the flat ΛCDM scenario, the allowed range is $\Delta N_{\mathrm{eff}}<6\mathrm{}$ (95% confidence level) using WMAP data only, or $-2.6<\mathrm{}\Delta N_{\mathrm{eff}}<4\mathrm{}$ with the prior $H_0=72\mathrm{}\pm 8\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}.$ When other cosmic microwave background and large scale structure experiments are taken into account, the window shrinks to $-1.6<\mathrm{}\Delta N_{\mathrm{eff}}<\mathrm{3.8.}\mathrm{}$ These results are in perfect agreement with the bounds from primordial nucleosynthesis. Nonminimal cosmological models with extra relativistic degrees of freedom are now severely restricted.

In a previous paper, we presented a new approach for measuring the non-Gaussianity of the cosmic microwave background (CMB) anisotropy pattern, based on the multivariate empirical distribution function of the spherical harmonics $a_{\mathcal{l}m}$ of a CMB map. The present paper builds upon the same ideas and proposes several improvements and extensions. More precisely, we exploit the additional information on the random phases of the $a_{\mathcal{l}m}$ to provide further tests based on the empirical distribution function. Also we take advantage of the effect of rotation on improving the power of our procedures. The suggested tests are implemented on physically motivated models of non-Gaussian fields; Monte Carlo simulations suggest that this approach may be very promising in the analysis of non-Gaussianity generated by nonstandard models of inflation. We address also some experimentally meaningful situations, such as the presence of instrumental noise and a galactic cut in the map.

We calculate the light-cone wave functions of mesons by solving their bound state problem in a coarse transverse lattice gauge theory using discrete light cone quantization. A large-$N_c$ approximation is made and the light-cone Hamiltonian expanded in massive dynamical fields at fixed lattice spacing. In contrast with earlier calculations, we include contributions from states containing many gluonic link fields between the quarks. The Hamiltonian is renormalized by a combination of covariance conditions on bound states and fitting the physical masses ${\mathcal{M}}_{\rho }$ and ${\mathcal{M}}_{\pi },$ decay constant $f_{\pi },$ and the string tension $\sqrt{\sigma }.$ Good covariance is obtained for the lightest $0^{-+}$ state, which we compare with the pion. Many observables can be deduced from its light-cone wave functions. After perturbative evolution, the quark valence structure function is found to be consistent with the experimental pion structure function deduced from Drell-Yan pi-nucleon data in the valence region $x>\mathrm{}\mathrm{0.5.}\mathrm{}$ In addition, the distribution amplitude is consistent with the experimental pion distribution deduced from the $\pi {\gamma }^{*}\gamma$ transition form factor and diffractive dissociation. A new observable we calculate is the probability for quark helicity correlation. We predict a 45% probability that the valence-quark helicities are aligned in the pion.

We propose a novel scenario for Affleck-Dine baryogenesis in the braneworld, considering the hybrid potential for the Affleck-Dine field. Destabilization of the flat direction is not due to the Hubble parameter but is induced by a trigger field. The moduli for the brane distance plays the role of the trigger field. Q balls are unstable in models with large extra dimensions.

We confirm earlier hints that the conventional phase diagram of the discrete chiral Gross-Neveu model in the large N limit is deficient at nonzero chemical potential. We present the corrected phase diagram constructed in mean field theory. It has three different phases, including a kink-antikink crystal phase. All transitions are second order. The driving mechanism for the new structure of baryonic matter in the Gross-Neveu model is an Overhauser type instability with gap formation at the Fermi surface.

We conduct an exhaustive search for solutions of type IIA and IIB supergravity with augmented supersymmetry. We find a two-parameter family of type IIB solutions preserving 28 supercharges, as well as several other type IIA and IIB families of solutions with 24 supercharges. Given the simplicity of the pp-wave solution, the algorithm described here represents a systematic way of classifying all such solutions with augmented supersymmetry. By T dualizing some of these solutions we obtain exact non-pp-wave supergravity solutions (with 8 or 16 supercharges), which can be interpreted as perturbations of the AdS-CFT correspondence with irrelevant operators.

The loop quantum cosmology of the closed isotropic model is studied with special emphasis on a comparison with traditional results obtained in the Wheeler-DeWitt approach. This includes the relation of the dynamical initial conditions to boundary conditions such as the no-boundary or the tunneling proposal and a discussion of inflation from quantum cosmology.

We investigate symmetry breaking patterns from replicated gauge groups which generate anomaly-free and family-dependent $U\left(1\right)\mathrm{}$ symmetries. We discuss the extent to which these symmetries can explain the observed hierarchies of fermion masses and mixings.