Radiative decays of the $1^3{D}_1$ orbital excitations of the $\rho ,\omega$ and $\phi$ to the scalars $f_0\mathrm{}\left(1370\right),f_0\mathrm{}\left(1500\right)\mathrm{}$ and $f_0\mathrm{}\left(1710\right)\mathrm{}$ are shown to provide a flavor filter, clarifying the extent of glueball mixing in the scalar states. A complementary approach to the latter is provided by the radiative decays of the scalar mesons to the ground-state vectors $\rho ,\omega$ and $\phi .$ Discrimination among different mixing scenarios is strong.

In this paper the stability of the hedgehog shape of the chiral soliton is studied for the octet baryon with the SU(3) chiral quark soliton model. The strangeness degrees of freedom are treated by a simplified bound-state approach, which omits the locality of the kaon wave function. The mean field approximation for the flavor rotation is applied to the model. The classical soliton changes shape according to the strangeness. The baryon appears as a rotational band of the combined system of the deformed soliton and the kaon.

We discuss the oscillations of atmospheric and solar neutrinos into sterile neutrinos in the 2+2 scheme. A zeroth order sum rule requires equal probabilities for oscillation into ${\nu }_s$ and ${\nu }_{\tau }$ in the solar+atmospheric data sample. Data do not favor this claim. Here we use scatter plots to assess the corrections of the zeroth order sum rule when (i) the $4\times 4$ neutrino mixing matrix assumes its full range of allowed values, and (ii) matter effects are included. We also introduce a related “product rule.” We find that the sum rule is significantly relaxed, due to both the inclusion of the small mixing angles (which provide a short-baseline contribution) and to matter effects. The product rule is also dramatically altered. The observed relaxation of the sum rule weakens the case against the 2+2 model and the sterile neutrino. To invalidate the 2+2 model, the daunting task of fitting global data with the small mixing angles included seems to be required.

Using the one-loop helicity amplitudes for low-energy $\nu \overrightarrow{\gamma }\nu \gamma$ and $\overline{\nu }\overrightarrow{\gamma }\overline{\nu }\gamma$ scattering in the standard model with massless neutrinos, we study the optical activity of a sea of neutrinos and antineutrinos. In particular, we estimate the values of the index of refraction and rotary power of this medium in the absence of dispersion.

We present and analyze QCD corrections to the baryon magnetic moments in terms of the one-, two-, and three-body operators which appear in the effective field theory developed in our recent papers. The main corrections are extended Thomas-type corrections associated with the confining interactions in the baryon. We investigate the contributions of low-lying angular excitations to the baryon magnetic moments quantitatively and show that they are completely negligible. When the QCD corrections are combined with the nonquark model contributions of the meson loops, we obtain a model which describes the baryon magnetic moments within a mean deviation of 0.04 ${\mu }_N.$ The nontrivial interplay of the two types of corrections to the quark-model magnetic moments is analyzed in detail, and explains why the quark model is so successful. In the course of these calculations, we parametrize the general spin structure of the $j={\frac{1}{2}}^{+}$ baryon wave functions in a form which clearly displays the symmetry properties and the internal angular momentum content of the wave functions, and allows us to use spin-trace methods to calculate the many spin matrix elements which appear in the expressions for the baryon magnetic moments. This representation may be useful elsewhere.

We propose to probe the top-color-assisted technicolor (TC2) model from the top-charm associated production at the CERN LHC, which is highly suppressed in the standard model. Because of the flavor-changing couplings of the top quark with the scalars (top-pions and top-Higgs-bosons) in the TC2 model, the top-charm associated production can occur via both the s-channel and t-channel parton processes by exchanging a scalar field at the LHC. We examine these processes through Monte Carlo simulation and find that they can reach the observable level at the LHC in quite a large part of the parameter space of the TC2 model.

In a recent paper we showed that a quintessence scalar field plus a dissipative matter fluid can drive late cosmic accelerated expansion and simultaneously solve the coincidence problem. In this Brief Report we extend this result to the cases when the scalar field is replaced either by a Chaplygin gas or a tachyonic fluid.

The correlator of a Wilson loop with a local operator in $\mathcal{N}=4\mathrm{}$ SYM theory can be represented by a string amplitude in ${\mathrm{AdS}}_5\times {\mathrm{S}}^5.$ This amplitude describes an overlap of the boundary state, which is associated with the loop, with the string mode, which is dual to the local operator. For chiral primary operators with a large R charge, the amplitude can be calculated by semiclassical techniques. We compare the semiclassical string amplitude to the SYM perturbation theory and find an exact agreement to the first two nonvanishing orders.

We show the existence of classical solutions of a system of D3-branes oriented at an arbitrary angle with respect to each other, in a six dimensional pp-wave background obtained from ${\mathrm{AdS}}_3\times {\mathrm{S}}^3\times {\mathrm{R}}^4,$ with a NS-NS and R-R three-form field strength. These D-brane bound states are shown to preserve $1/16$ of the supersymmetries. We also present more D-brane bound state solutions by applying T-duality symmetries. Finally, the probe analysis is discussed along with a brief outline of the open string construction.

We obtain explicit formulas for the Neumann coefficients and associated quantities that appear in the three-string vertex for type IIB string theory in a plane-wave background, for any value of the mass parameter $\mu .$ The derivation involves constructing the inverse of a certain infinite-dimensional matrix, in terms of which the Neumann coefficients previously had been written only implicitly. We derive asymptotic expansions for large $\mu$ and find unexpectedly simple results, which are valid to all orders in $1/\mu .$ Using BMN duality, these give predictions for certain gauge theory quantities to all orders in the modified ’t Hooft coupling ${\lambda }^{\prime }.$ A specific example is presented.

The gauge-invariant Chern-Simons-type Lorentz- and $\mathrm{CPT}$-breaking term is here reassessed and a spin-projector method is adopted to account for the breaking (vector) parameter. Issues such as causality, unitarity, spontaneous gauge-symmetry breaking, and vortex formation are investigated, and consistency conditions on the external vector are identified.

We investigate the helicity-dependent twist-two and twist-three generalized parton distributions in light-front Hamiltonian QCD for a massive dressed quark target. Working in the kinematical region $\xi <x<\mathrm{}1,$ we obtain the splitting functions for the evolutions of twist-two quark and gluon distributions in a straightforward way. For the twist-three distribution, we find that all contributions are proportional to the quark mass and thus the twist-three distribution is directly related to the chiral symmetry breaking dynamics in light-front QCD. We also show that the off-forward Wandzura-Wilczek (WW) relation is violated in perturbative QCD for a massive dressed quark. We calculate the quark mass correction to the WW relation in the off-forward case and show that it is related to $h_1\mathrm{}\left(x\right)\mathrm{}$ in the forward limit. We extract the “genuine twist-three” part of the matrix element in the forward case and verify the Burkhardt-Cottingham and Efremov-Leader-Teryaev sum rules.

Cosmic strings are considered in two types of gauged sigma models, which generalize the gravitating Abelian Higgs model. The two models differ by whether the U(1) kinetic term is of the Maxwell or Chern-Simons form. We obtain the self-duality conditions for a general two-dimensional target space defined in terms of field dependent “dielectric functions.” In particular, we analyze analytically and numerically the equations for the case of O(3) models (two-sphere as target space), and find cosmic string solutions of several kinds as well as gravitating vortices. We classify the solutions by their flux and topological charge. We note an interesting connection between the Maxwell and Chern-Simons type models, which is responsible for simple relations between the self-dual solutions of both types. There is however a significant difference between the two systems, in that only the Chern-Simons type sigma model gives rise to spinning cosmic vortices.

We present a novel class of theories where supersymmetry is only preserved in a partial (nonisolated) sector. The supersymmetric sector consists of CFT bound states that can coexist with fundamental states which do not respect supersymmetry. These theories arise from the four-dimensional (4D) holographic interpretation of 5D theories in a slice of AdS where supersymmetry is broken on the boundary. In particular, we consider the standard model where only the Higgs sector (and possibly the top quark) is supersymmetric. The Higgs boson mass parameter is then protected by supersymmetry, and consequently the electroweak scale is naturally smaller than the composite Higgs scale. This not only provides a solution to the hierarchy problem, but predicts a “little” hierarchy between the electroweak and new physics scale. Remarkably, the model only contains a single supersymmetric partner, the Higgsino (and possibly the top squark), and, as in the usual MSSM, predicts a light Higgs boson.

We have carefully analyzed the potential of future cosmic microwave background (CMB) and large scale structure (LSS) measurements to probe neutrino masses. We perform a Fisher matrix analysis on a nine-dimensional cosmological parameter space and find that data from the Planck CMB experiment combined with the Sloan Digital Sky Survey (SDSS) can measure a value for the sum of all three active neutrino mass eigenstates of 0.12 eV at 95% C.L. This is almost at the level of the 0.06 eV mass suggested by current neutrino oscillation data. A future galaxy survey with an order of magnitude larger survey volume than the SDSS would allow for a neutrino mass determination of 0.03–0.05 eV (95% C.L.).

We examine random matrix models of QCD which are capable of supporting both chiral and diquark condensation. A numerical study of the spectral densities near zero virtuality shows that the introduction of color in the interactions does not alter the one-body results imposed by chiral symmetry. A model with three colors has the spectral density predicted for the chiral ensemble with a Dyson index $\beta =2;$ a pseudoreal model with two colors exhibits the spectral density of the chiral ensemble with $\beta =1.\mathrm{}$

A charged scalar field is quantized in the background of a static $\left(d-2\right)$-brane which is a core of the magnetic flux lines in flat $\mathrm{}(d+1\mathrm{})\mathrm{}$-dimensional space-time. We find that the vector potential of the magnetic core induces the energy-momentum tensor in the vacuum. The tensor components are periodic functions of the brane flux and holomorphic functions of space dimension. The dependence on the distance from the brane and on the coupling to the space-time curvature scalar is comprehensively analyzed.

We present a general procedure for calculating one-loop “Casimir” energy densities for a scalar field coupled to a fixed potential in renormalized quantum field theory. We implement direct subtraction of counterterms computed precisely in dimensional regularization with a definite renormalization scheme. Our procedure allows us to test quantum field theory energy conditions in the presence of background potentials spherically symmetric in some dimensions and independent of others. We explicitly calculate the energy density for several examples. For a square barrier, we find that the energy is negative and divergent outside the barrier, but there is a compensating divergent positive contribution near the barrier on the inside. We also carry out calculations with exactly solvable ${\mathrm{sech}}^2$ potentials, which arise in the study of solitons and domain walls.

We study the physics of $\mathcal{N}=1\mathrm{}$ super Yang-Mills theory with the gauge group $\mathrm{U}\mathrm{}\left(N\right)\mathrm{}$ and one adjoint Higgs field, by using the recently derived exact effective superpotentials. Interesting phenomena occur for some special values of the Higgs potential couplings. We find critical points with massless glueballs and/or massless monopoles, confinement without a mass gap, and tensionless domain walls. We describe the transitions between regimes with different patterns of gauge symmetry breaking, or, in the matrix model language, between solutions with a different number of cuts. The standard large N expansion is singular near the critical points, with domain wall tensions scaling as a fractional power of N. We argue that the critical points are four-dimensional analogues of the Kazakov critical points that are commonly found in low dimensional matrix integrals. We define a double scaling limit that yields the exact tension of BPS two-branes in the resulting $\mathcal{N}=1,$ four-dimensional noncritical string theory. D-brane states can be deformed continuously into closed string solitonic states, and vice versa, along paths that go over regions where the string coupling is strong.

We describe lightlike boosts of the Kerr gravitational field transverse and parallel to the symmetry axis. In the transverse case the boosted field is that of an impulsive gravitational wave having a line singularity displaced relative to its position if the rotation of the source were removed. The parallel boost is insensitive to the rotation of the source. The literature contains a number of diverse results for lightlike boosts of the Kerr gravitational field. Our conclusions confirm the correctness of the limits calculated by Balasin and Nachbagauer [Class. Quantum Grav. 13, 731 (1996)]. To avoid any ambiguity our approach is centered on evaluating the lightlike boost of the Riemann tensor for the Kerr space-time with the metric playing a secondary role.