We describe string production after angled brane inflation. First, we point out that there was a discrepancy in previous discussions. The expected tension of the cosmic string calculated from the four-dimensional effective Lagrangian did not match the one obtained in the brane analysis. In the previous analysis, the cosmic string is assumed to correspond to the lower-dimensional daughter brane, which wraps the same compactified space as the original mother brane. In this case, however, the tension of the daughter brane cannot depend on the angle $\left(\theta \right).\mathrm{}$ On the other hand, from the analysis of the effective Lagrangian for tachyon condensation, it is easy to see that the tension of the cosmic string must be proportional to $\theta ,$ when $\theta \ll 1.$ This is an obvious discrepancy that must be explained by consideration of the explicit brane dynamics. In this paper, we will solve this problem by introducing a simple idea. We calculate the tension of the string in the two cases, which matches precisely. The cosmological constraint for angled inflation is relaxed, because the expected tension of the cosmic string becomes smaller than the one obtained in previous arguments, by a factor of $\theta .$

We explore the use of Fabry-Pérot cavities as high-pass filters for squeezed light, and show that they can increase the sensitivity of interferometric gravitational-wave detectors without the need for long (kilometer scale) filter cavities. We derive the parameters for the filters, and analyze the performance of several possible cavity configurations in the context of a future gravitational-wave interferometer with squeezed light (vacuum) injected into the output port.

We report improved measurements of branching fractions for charmless hadronic two-body B meson decays containing an $\omega$ meson in the final state. The results are based on a data sample of $78{\mathrm{fb}}^{-1}$ collected on the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance by the Belle detector. We measure the branching fractions $\mathcal{B}{(B}^{+}\to \omega K^{+}{)=(6.5\mathrm{}}_{-1.2}^{+1.3\mathrm{}}\pm 0.6)\times {10}^{-6}$ and $\mathcal{B}{(B}^{+}\to \omega {\pi }^{+}{)=(5.7\mathrm{}}_{-1.3}^{+1.4\mathrm{}}\pm 0.6)\times {10}^{-6}.$ We give 90% confidence upper limits for $\mathcal{B}{(B}^0\to \omega K^0)<\mathrm{}7.6\mathrm{}\times {10}^{-6}$ and $\mathcal{B}{(B}^0\to \omega {\pi }^0)<\mathrm{}1.9\mathrm{}\times {10}^{-6}.$ We also obtain the partial rate asymmetries ${\mathcal{A}}_{\mathrm{CP}}{=0.06\mathrm{}}_{-0.18}^{+0.21\mathrm{}}\pm 0.01$ for $B^{\pm }\to \omega K^{\pm }$ and ${\mathcal{A}}_{\mathrm{CP}}{=0.50\mathrm{}}_{-0.20}^{+0.23\mathrm{}}\pm 0.02$ for $B^{\pm }\to \omega {\pi }^{\pm }.$

We evaluate the leading order amplitude for the deep exclusive electroproduction of an exotic hybrid meson in the Bjorken regime. We show that, contrarily to naive expectation, this amplitude factorizes at the twist 2 level and thus scales like usual meson electroproduction when the virtual photon and the hybrid meson are longitudinally polarized. Exotic hybrid mesons may thus be studied in electroproduction experiments at JLAB, HERA (HERMES) or CERN (Compass).

It has recently been shown that a non-Hermitian Hamiltonian H possessing an unbroken $\mathcal{PT}$ symmetry (i) has a real spectrum that is bounded below, and (ii) defines a unitary theory of quantum mechanics with positive norm. The proof of unitarity requires a linear operator $\mathcal{C},$ which was originally defined as a sum over the eigenfunctions of H. However, using this definition to calculate $\mathcal{C}$ is cumbersome in quantum mechanics and impossible in quantum field theory. An alternative method is devised here for calculating $\mathcal{C}$ directly in terms of the operator dynamical variables of the quantum theory. This method is general and applies to a variety of quantum mechanical systems having several degrees of freedom. More importantly, this method is used to calculate the $\mathcal{C}$ operator in quantum field theory. The $\mathcal{C}$ operator is a time-independent observable in $\mathcal{PT}$-symmetric quantum field theory.

We study the propagation of gravitational waves (GW’s) in a uniformly magnetized plasma at arbitrary angles to the magnetic field. No a priori assumptions are made about the temperature, and we consider both a plasma at rest and a plasma flowing out at ultrarelativistic velocities. In the $3+1$ orthonormal tetrad description, we find that all three fundamental low-frequency plasma wave modes are excited by the GW’s. Alfvén waves are excited by a × polarized GW, whereas the slow and fast magnetoacoustic modes couple to the + polarization. The slow mode, however, does not interact coherently with the GW. The most relevant wave mode is the fast magnetoacoustic mode which in a strongly magnetized plasma has a vanishingly small phase lag with respect to the GW allowing for coherent interaction over large length scales. When the background magnetic field is almost, but not entirely, parallel to the GW’s direction of propagation even the Alfvén waves grow to first order in the GW amplitude. Finally, we calculate the growth of the magnetoacoustic waves and the damping of the GW.

Recently we studied the effects of information carrying waves propagating through isotropic cosmologies. By information carrying we mean that the waves have an arbitrary dependence on a function. We found that the waves introduce shear and anisotropic stress into the universe. We then constructed explicit examples of pure gravity wave perturbations for which the presence of this anisotropic stress is essential and the null hypersurfaces playing the role of the histories of the wavefronts in the background space-time are shear free. Motivated by this result we now prove that these two properties are true for all information carrying waves in isotropic cosmologies.

We consider a Borel sum definition of all-orders perturbation theory for Minkowskian QCD observables such as the $R_{e^{+}{e}^{-}}$ ratio, and show that both this perturbative component and the additional nonperturbative all-orders operator product expansion (OPE) component can remain separately well-defined for all values of energy $\sqrt{s},$ with the perturbative component dominating as $\overrightarrow{s}\infty ,$ and with both components contributing as $\overrightarrow{s}0.$ In the infrared $\overrightarrow{s}0$ limit the perturbative correction to the parton model result for $R_{e^{+}{e}^{-}}$ has an all-orders perturbation theory component which smoothly freezes to the value $\mathcal{R}\mathrm{}\left(0\right)=2/b,$ where $b=\left(33\mathrm{}-{2N}_f\right)/6\mathrm{}$ is the first QCD beta-function coefficient, with $N_f$ flavors of massless quark. For freezing one requires $N_f<9.\mathrm{}$ The freezing behavior is manifested by the “contour-improved” or “analytic perturbation theory” (APT), in which an infinite subset of analytical continuation terms are resummed to all-orders. We show that for the Euclidean Adler-$D$ function, ${D(Q}^2),$ the perturbative component remains defined into the infrared if all the renormalon singularities are taken into account, but no analogue of the APT reorganization of perturbation theory is possible. We perform phenomenological comparisons of suitably smeared low-energy data for the $R_{e^{+}{e}^{-}}$ ratio, with the perturbative freezing predictions, and find good agreement.

We present a model of supersymmetric non-Abelian Chern-Simons theories in three dimensions with arbitrarily many supersymmetries, called ${\aleph }_0$-extended supersymmetry. The number of supersymmetries N equals the dimensionality of any non-Abelian gauge group G as $N=\dim G.\mathrm{}$ Due to the supersymmetry parameter in the adjoint representation of a local gauge group G, supersymmetry has to be local. The minimal coupling constant is to be quantized, when the homotopy mapping is nontrivial: ${\pi }_3\mathrm{}\left(G\right)=Z.$ Our results indicate that there is still a lot of freedom to be explored for Chern-Simons type theories in three dimensions, possibly related to M theory.

We present results from simulations using 2 flavors of $\mathcal{O}\mathrm{}\left(a\right)\mathrm{}$-improved Wilson quarks whose masses are about 1/3 of the physical strange quark mass. We present new data on the mass of the singlet pseudoscalar meson and evidence of the onset of chiral logarithms in the pion decay constant. The previously observed suppression of the topological susceptibility at lighter quark masses is confirmed. We report on the performance of the hybrid Monte Carlo algorithm at light quark masses.

We discuss the potentially important role played by preheating in certain variants of the curvaton mechanism in which isocurvature perturbations of a D-flat (and F-flat) direction become converted to curvature perturbations during reheating. We analyze the transition from inflation to reheating in some detail, including the dynamics of the coupled curvaton and inflation fields during this transition. We discover that preheating could be an important source of adiabaticity where the parametric resonance of the isocurvature components amplifies the superhorizon fluctuations by a significant amount. As an example of these effects we develop a particle physics motivated model which we recently introduced in which the D-flat direction is identified with the usual Higgs field. Our new results show that it is possible to achieve the correct curvature perturbations for initial values of the curvaton fields of the order of the weak scale. In this model we show that the prediction for the spectral index of the final curvature perturbation only depends on the mass of the curvaton during inflation, where consistency with current observational data requires the ratio of this mass to the Hubble constant to be $<~\mathrm{0.3.}$

The interaction region of hard exclusive hadron scattering can have a large transverse size due to endpoint contributions, where one parton carries most of the hadron momentum. The endpoint region is enhanced and can dominate in processes involving multiple scattering and quark helicity flip. The endpoint Fock states have perturbatively short lifetimes and scatter softly in the target. We give plausible arguments that endpoint contributions can explain the apparent absence of color transparency in fixed angle exclusive scattering and the dimensional scaling of transverse $\rho$ photoproduction at high momentum transfer, which requires quark helicity flip. We also present a quantitative estimate of Sudakov effects.

The Markov chain Monte Carlo methods offer practical procedures for detecting signals characterized by a large number of parameters and under conditions of low signal-to-noise ratio. We present a Metropolis-Hastings algorithm capable of inferring the spin and orientation parameters of a neutron star from its periodic gravitational wave signature seen by laser interferometric detectors.

Colladay and Kostelecký have proposed a framework for studying Lorentz and CPT violation in a natural extension of the standard model. Although numerous bounds exist on the Lorentz and CPT violating parameters in the gauge boson and fermion sectors, there are no published bounds on the parameters in the Higgs sector. We determine these bounds. The bounds on the CPT-even asymmetric coefficients arise from the one-loop contributions to the photon propagator, those from the CPT-even symmetric coefficients arise from the equivalent $c_{\mu \nu }$ coefficients in the fermion sector, and those from the CPT-odd coefficient arise from bounds on the vacuum expectation value of the Z boson.

In the preceding comment, Blankleider and Kvinikhidze criticize the form of the thermal propagator used previously by us and propose an alternate thermal propagator for the fermions in the light-front Schwinger model. We show that, within the standard light-front quantization used by us, the thermal propagator for the fermions is unique as presented in that paper.

In a recent paper by A. Das and X. Zhou [Phys. Rev. D 68, 065017 (2003)], it is claimed that explicit evaluation of the thermal photon self-energy in the Schwinger model gives off-shell thermal Green’s functions that are different in light-front and conventional quantizations. We show that the claimed difference originates from an erroneous simplification of the fermion propagator used in the light-front calculation.

We reiterate that there is no evidence that BL Lacs are sources of ultrahigh energy cosmic rays.

In a series of papers we have found statistically significant correlations between arrival directions of ultrahigh energy cosmic rays and BL Lacertae objects. Recently, our calculations were partly repeated by Evans, Ferrer, and Sarkar with different conclusions. We demonstrate that the criticism of Evans, Ferrer, and Sarkar is incorrect. We also present the details of our method.

We elaborate further on the possibility that the inflationary primordial power spectrum contains superimposed oscillations. We study various effects which could influence the calculation of the multipole moments in this case. We also present the theoretical predictions for two other cosmological observables, the matter power spectrum and the $\mathrm{EE}$ polarization channel.