The effect of the massless gravitational scalar field assumed to couple directly to the Maxwell field on the solar-system experiments is estimated. We start with discussing the theoretical significance of this coupling. Rather disappointingly, however, we find that the scalar-field parameters never affect the observation in the limit of geometric optics, indicating a marked difference from the well-known contribution through the spacetime metric.

High-energy neutrinos are expected to be produced in a variety of astrophysical sources as well as in optically thick hidden sources. We explore the matter-induced oscillation effects on emitted neutrino fluxes of three different flavors from the latter class. We use the ratio of electron and tau induced showers to muon tracks, in upcoming neutrino telescopes, as the principal observable in our analysis. This ratio depends on the neutrino energy, density profile of the sources, and on the oscillation parameters. The largely unknown flux normalization drops out of our calculation and only affects the statistics. For the current knowledge of the oscillation parameters we find that the matter-induced effects are non-negligible and the enhancement of the ratio from its vacuum value takes place in an energy range where the neutrino telescopes are the most sensitive. Quantifying the effect would be useful to learn about the astrophysics of the sources as well as the oscillation parameters. If the neutrino telescopes mostly detect diffuse neutrinos without identifying their sources, then any deviation of the measured flux ratios from the vacuum expectation values would be most naturally explained by a large population of hidden sources for which matter-induced neutrino oscillation effects are important.

The relative sidereal variation in the arrival direction of primary cosmic ray nuclei of median energy 10 TeV was measured using downward, through-going muons detected with the Super-Kamiokande-I detector. The projection of the anisotropy map onto the right ascension axis has a first harmonic amplitude of $(6.64\pm 0.98\mathrm{stat}\pm 0.55\mathrm{syst})\times {10}^{-4}$ and a phase at maximum at ($33.2°\pm 8.2°\mathrm{stat}\pm 5.1°\mathrm{syst}$) right ascension. A sky map in equatorial coordinates indicates an excess region in the constellation of Taurus and a deficit region toward Virgo. The excess region is centered at $({\alpha }_T,{\delta }_T)=(75°\pm 7°,-5°\pm 9°)$ with a half-opening angle ${\chi }_T=(39\pm 7)°$; the excess flux is $(0.104\pm 0.020)\%$ above the isotropic expectation. The corresponding parameters for the deficit region are $({\alpha }_V,{\delta }_V)=(205°\pm 7°,5°\pm 10°)$, ${\chi }_V=(54\pm 7)°$, and $(-0.094\pm 0.014)\%$. The data do not allow us to rule out a pure dipole form for the anisotropy (allowed at 13% confidence level); they are better described by the excess and deficit cones described above. We explored the implications under the assumption that the true anisotropy is not distorted too much by the analysis filter so that it is well-described by the observed excess and deficit cones.

We work out and discuss the Minkowski version of fractional analytic perturbation theory for QCD observables, recently developed and presented by us for the Euclidean region. The original analytic approach to QCD, initiated by Shirkov and Solovtsov, is summarized and relations to other proposals to achieve an analytic strong coupling are pointed out. The developed framework is applied to the Higgs boson decay into a $b\overline{b}$ pair, using recent results for the massless correlator of two quark scalar currents in the $\overline{\mathrm{MS}}$ scheme. We present calculations for the decay width within the Minkowski version of fractional analytic perturbation theory including those non-power-series contributions that correspond to the $\mathcal{O}({\alpha }_s^3)$-terms, also taking into account evolution effects of the running coupling and the $b$-quark-mass renormalization. Comparisons with previous results within standard QCD perturbation theory are performed and the differences are pointed out. The interplay between effects originating from the analyticity requirement and the analytic continuation from the spacelike to the timelike region and those due to the evolution of the heavy-quark mass is addressed, highlighting the differences from the conventional QCD perturbation theory.

We discuss a minimal extension to the standard model in which there are two Higgs bosons and, in addition to the usual fermion content, two fermion doublets and one fermion singlet. The little hierarchy problem is solved by the vanishing of the one-loop corrections to the quadratic terms of the scalar potential. The electroweak ground state is therefore stable for values of the cut off up to 10 TeV. The Higgs boson mass can take values significantly larger than the current LEP bound and still be consistent with electroweak precision measurements.

We study the effects of dimension-six effective operators on the flavor violating production and decay of leptons at the International Linear Collider. Analytic expressions for the cross sections, decay widths, and asymmetries of all flavor changing processes will be presented, as well as an analysis of the feasibility of their observation at the ILC.

We present a class of composite Higgs models arising from a warped extra dimension that can satisfy all the electroweak precision tests in a significant portion of their parameter space. A custodial symmetry plays a crucial role in keeping the largest corrections to the electroweak observables below their experimental limits. In these models the heaviness of the top quark is not only essential to trigger the electroweak symmetry breaking, but it also implies that the lowest top resonance and its custodial partners, the custodians, are significantly lighter than the other resonances. These custodians are the trademark of these scenarios. They are exotic colored fermions of electromagnetic charges $5/3$, $2/3$, and $-1/3$, with masses predicted roughly in the range 500–1500 GeV. We discuss their production and detection at the CERN LHC.

We consider the constraints on string networks with junctions in which the strings may all be different, as may be found, for example, in a network of $(p,q)$ cosmic superstrings. We concentrate on three aspects of junction dynamics. First we consider the propagation of small-amplitude waves across a static three-string junction. Then, generalizing our earlier work, we determine the kinematic constraints on two colliding strings with different tensions. As before, the important conclusion is that strings do not always reconnect with a third string; they can pass straight through one another (or in the case of non-Abelian strings become stuck in an X configuration), the constraint depending on the angle at which the strings meet, on their relative velocity, and on the ratios of the string tensions. For example, if the two colliding strings have equal tensions, then for ultrarelativistic initial velocities they pass through one another. However, if their tensions are sufficiently different they can reconnect. Finally, we consider the global properties of junctions and strings in a network. Assuming that, in a network, the incoming waves at a junction are independently randomly distributed, we determine the root-mean-square (r.m.s.) velocities of strings and calculate the average speed at which a junction moves along each of the three strings from which it is formed. Our findings suggest that junction dynamics may be such as to preferentially remove the heavy strings from the network leaving a network of predominantly light strings. Furthermore the r.m.s. velocity of strings in a network with junctions is smaller than $1/\sqrt{2}$, the result for conventional Nambu-Goto strings without junctions in Minkowski space-time.

I consider the case of two interacting scalar fields, $\varphi$ and $\psi$, and use the path integral formalism in order to treat the first classically and the second quantum-mechanically. I derive the Feynman rules and the resulting equation of motion for the classical field which should be an improvement of the usual semiclassical procedure. As an application I use this method in order to enforce Gauss’s law as a classical equation in a non-Abelian gauge theory. I argue that the theory is renormalizable and equivalent to the usual Yang-Mills theory as far as the gauge field terms are concerned. There are additional terms in the effective action that depend on the Lagrange multiplier field $\lambda$ that is used to enforce the constraint. These terms and their relation to the confining properties of the theory are discussed.

Hot and/or dense, normal-conducting systems of relativistic fermions exhibit a particular collective excitation, the so-called plasmino. We compute the one-loop self-energy, the dispersion relation, and the spectral density for fermions interacting via attractive boson exchange. It is shown that plasminos also exist in superconductors.

There are reasons (which we enumerate) to think that an infinite extra dimension will harbor a black hole. In this case, brane-localized modes of gravity and gauge fields become quasilocalized, and light from a distant object can become extinct as it is lost to the black hole. In a concrete scenario, where the photon is localized by gravity, we find that the extinction rate for propagating photons is at least comparable to the correction to the real part of the frequency. That results, for example, in a stringent bound on renormalization of the speed of light.

We show that the open string worldsheet description of brane decay (discussing a specific example of a rolling tachyon background) can be related to a sequence of points of thermodynamic equilibrium of a grand canonical ensemble of point charges on a circle, the Dyson gas. Subsequent instants of time are related to neighboring values of the chemical potential or the average particle number $\overline{N}$. The free energy of the system decreases in the direction of larger $\overline{N}$ or later times, thus defining a thermodynamic arrow of time. Time evolution equations are mapped to differential equations relating thermal expectation values of certain observables at different points of thermal equilibrium. This suggests some lessons concerning emergence of time from an underlying microscopic structure in which the concept of time is absent.

We analyze the observational constraints on the model where a pseudo-Nambu-Goldstone boson (pNGB) plays the role of dark energy. The constraints are derived by using the latest Gold set of 182 type Ia supernovae and the CMB shift parameter. We allow for both the initial value of the scalar field and the present value of the energy density in the pNGB to vary. We find that—compared to previous analyses—the allowed portion of parameter space has shrunk around the region where the pNGB does not evolve significantly.

General-relativistic deflection of light by mass, dipole, and quadrupole moments of the gravitational field of a moving massive planet in the solar system is derived in the approximation of the linearized Einstein equations. All terms of order $1\mu \mathrm{as}$ are taken into account, parametrized, and classified in accordance with their physical origin. The monopolar light-ray deflection, modulated by the radial Doppler effect, is associated with the total mass and radial velocity of the gravitating body. It displaces the apparent positions of stars in the sky plane radially away from the origin of the celestial coordinates associated with the planet. The dipolar deflection of light is due to a translational mismatch of the center of mass of the planet and the origin of the planetary coordinates caused by the inaccuracy of planetary ephemeris. It can also originate from the difference between the null cone for light and that for gravity that is not allowed in general relativity but can exist in some of the alternative theories of gravity. The dipolar gravity field pulls the apparent position of a star in the plane of the sky in both radial and orthoradial directions with respect to the origin of the coordinates. The quadrupolar deflection of light is caused by the physical oblateness, $J_2$, of the planet, but in any practical experiment it will have an admixture of the translation-dependent quadrupole due to inaccuracy of planetary ephemeris. This leads to a bias in the estimated value of $J_2$ that should be minimized by applying an iterative data reduction method designed to disentangle the different multipole moments and to fit out the translation-dependent dipolar and quadrupolar components of light deflection. The method of microarcsecond interferometric astrometry has the potential of greatly improving the planetary ephemerides, getting unbiased measurements of planetary quadrupoles, and of thoroughly testing the null-cone structure of the gravitational field and the speed of its propagation in the near-zone of the solar system. We calculate the instantaneous patterns of the light-ray deflections caused by the monopole, the dipole, and the quadrupole moments, and derive equations describing apparent motion of the deflected position of the star in the sky plane as the impact parameter of the light ray with respect to the planet changes due to its orbital motion. We discuss the observational capabilities of the near-future optical (SIM) and radio (SKA) interferometers for detecting the Doppler modulation of the radial deflection, and the dipolar and quadrupolar light-ray bendings by Jupiter and Saturn.

We explore the collider signatures of the Higgs sectors in singlet extended minimal supersymmetric standard models. We find that even with reduced couplings due to singlet mixing, a significant portion of the parameter spaces have a discoverable Higgs via traditional decay modes or via invisible decays (directly to neutralinos or through cascade decays to neutralinos and neutrinos). For illustrative points in parameter space we give the likelihood of Higgs discovery. In cases where neither traditional nor invisible modes can discover the Higgs, the neutralino sector may provide evidence for the extended models.

We study the complete one-loop electroweak (EW) corrections to the processes of single charged Higgs boson production associated with a neutral Higgs boson $(h^0,H^0,A^0)$ and a gauge boson $W^{\pm }$ in the framework of the minimal supersymmetric standard model (MSSM). Numerical results at the $\mathrm{SPS}1{\mathrm{a}}^{\prime }$ benchmark point as proposed in the SPA project, are presented for demonstration. We find that for the process $e^{+}{e}^{-}\to h^0{H}^{\pm }{W}^{\mp }$ the EW relative correction can be either positive or negative and in the range of $-15\%\sim 20\%$ in our chosen parameter space. While for the processes $e^{+}{e}^{-}\to H^0(A^0)H^{\pm }{W}^{\mp }$ the corrections generally reduce the Born cross sections and the EW relative corrections are typically of order $-10\%\sim -20\%$.

We consider a modification of QCD in which conventional fundamental quarks are replaced by Weyl fermions in the adjoint representation of the color $\mathrm{SU}(N)$. In the case of two flavors the low-energy chiral Lagrangian is that of the Skyrme-Faddeev model. The latter supports topologically stable solitons with mass scaling as $N^2$. Topological stability is due to the existence of a nontrivial Hopf invariant in the Skyrme-Faddeev model. Our task is to identify, at the level of the fundamental theory, adjoint QCD, an underlying reason responsible for the stability of the corresponding hadrons. We argue that all “normal” mesons and baryons, with mass $\mathrm{O}(N^0)$, are characterized by $(-1{)}^Q(-1{)}^F=1$, where $Q$ is a conserved charge corresponding to the unbroken U(1) surviving in the process of the chiral symmetry breaking ($\mathrm{SU}(2)\to \mathrm{U}(1)$ for two adjoint flavors). Moreover, $F$ is the fermion number (defined mod 2 in the case at hand). We argue that there exist exotic hadrons with mass $\mathrm{O}(N^2)$ and $(-1{)}^Q(-1{)}^F=-1$. They are in one-to-one correspondence with the Hopf Skyrmions. The transition from nonexotic to exotic hadrons is due to a shift in $F$, namely $F\to F-\mathcal{H}$ where $\mathcal{H}$ is the Hopf invariant. To detect this phenomenon we have to extend the Skyrme-Faddeev model by introducing fermions.

We study the vacuum polarization effects associated with a massive fermionic field in a spacetime produced by a global monopole considering a nontrivial inner structure for it. In the general case of the spherically symmetric static core with finite support we evaluate the vacuum expectation values of the energy-momentum tensor and the fermionic condensate in the region outside the core. These quantities are presented as the sum of pointlike global monopole and core-induced contributions. The asymptotic behavior of the core-induced vacuum densities are investigated at large distances from the core, near the core, and for small values of the solid angle corresponding to strong gravitational fields. As an application of general results the flower-pot model for the monopole’s core is considered and the expectation values inside the core are evaluated.

BRST quantization of the one-dimensional constrained matrix model which describes two-dimensional Yang-Mills theory on the cylinder is performed. Classical and quantum BRST generators and BRST-invariant Hamiltonians are constructed. The evolution operator is expressed in terms of the BRST path integral. Advantages of the BRST quantization over the reduced phase space approach leading to the theory of $N$ free fermions are discussed.

The brane cosmology scenario is based on the idea that the Universe is a 3-brane embedded in a five-dimensional bulk. In this work, a general class of braneworld wormholes is explored with $R\ne 0$, where $R$ is the four dimensional Ricci scalar, and specific solutions are further analyzed. A fundamental ingredient of traversable wormholes is the violation of the null energy condition (NEC). However, it is the effective total stress-energy tensor that violates the latter, and in this work, the stress-energy tensor confined on the brane, threading the wormhole, is imposed to satisfy the NEC. It is also shown that in addition to the local high-energy bulk effects, nonlocal corrections from the Weyl curvature in the bulk may induce a NEC violating signature on the brane. Thus, braneworld gravity seems to provide a natural scenario for the existence of traversable wormholes.