We study the gravitational radiation from a rotating monopole-antimonopole pair connected by a string. While at not too high frequencies the emitted gravitational spectrum is described asymptotically by $P_n\propto n^{-1}$, the spectrum is exponentially suppressed in the high-frequency limit, $P_n\propto \exp (-n/n_{\mathrm{c}\mathrm{r}})$. Below $n_{\mathrm{c}\mathrm{r}}$, the emitted spectrum of gravitational waves is very similar to the case of an oscillating monopole pair connected by a string, and we argue, therefore, that the spectrum found holds approximately for any moving monopole-string system. As an application, we discuss the stochastic gravitational wave background generated by monopole-antimonopole pairs connected by strings in the early Universe and gravitational wave bursts emitted at present by monopole-string networks. We confirm that advanced gravitational wave detectors have the potential to detect a signal for string tensions as small as $G\mu \sim {10}^{-13}$.

In this paper we study a solution of heterotic string theory corresponding to a rotating Kerr-Taub-NUT spacetime. It has an exact CFT description as a heterotic coset model, and a Lagrangian formulation as a gauged WZNW model. It is a generalization of a recently discussed stringy Taub-NUT solution, and is interesting as another laboratory for studying the fate of closed timelike curves and cosmological singularities in string theory. We extend the computation of the exact metric and dilaton to this rotating case, and then discuss some properties of the metric, with particular emphasis on the curvature singularities.

Some brane models rely on a generalization of the Melvin magnetic universe including a complex scalar field among the sources. We argue that the geometric interpretation of Kip. S. Thorne of this geometry restricts the kind of potential a complex scalar field can display to keep the same asymptotic behavior. While a finite energy is not obtained for a Mexican hat potential in this interpretation, this is the case for a potential displaying a broken phase and an unbroken one. We use for technical simplicity and illustrative purposes an ad hoc potential which however shares some features with those obtained in some supergravity models. We construct a sixth dimensional cylindrically symmetric solution which has two asymptotic regions: the Melvin-like metric on one side and a flat space displaying a conical singularity on the other. The causal structure of the configuration is discussed. Unfortunately, gravity is not localized on the brane.

Improved Wentzel-Kramers-Brillouin (WKB)-type approximations are presented in order to study cosmological perturbations beyond the lowest order. Our methods are based on functions which approximate the true perturbation modes over the complete range of the independent (Langer) variable, from subhorizon to superhorizon scales, and include the region near the turning point. We employ both a perturbative Green’s function technique and an adiabatic (or semiclassical) expansion (for a linear turning point) in order to compute higher order corrections. Improved general expressions for the WKB scalar and tensor power spectra are derived for both techniques. We test our methods on the benchmark of power-law inflation, which allows comparison with exact expressions for the perturbations, and find that the next-to-leading order adiabatic expansion yields the amplitude of the power spectra with excellent accuracy, whereas the next-to-leading order with the perturbative Green’s function method does not improve the leading order result significantly. However, in more general cases, either or both methods may be useful.

Double-lepton polarization asymmetries in the $B\to {\ell }^{+}{\ell }^{-}\gamma$ decay are calculated using the most general, model independent form of the effective Hamiltonian including all possible forms of the interaction. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the averaged double-lepton polarization asymmetries at LHC is also discussed.

Hadron masses are calculated in quenched lattice QCD on a variety of lattices in order to probe the scaling behavior of the Fat-Link Irrelevant Clover (FLIC) fermion action, a fat-link clover fermion action in which the purely irrelevant operators of the fermion action are constructed using APE-smeared links. The scaling analysis indicates FLIC fermions provide a new form of nonperturbative $\mathcal{O}(a)$ improvement where near-continuum results are obtained at finite lattice spacing.

Generalized parton distributions (GPDs) are studied at the hadronic (nonperturbative) scale within different assumptions based on a relativistic constituent quark model. In particular, by means of a meson-cloud model we investigate the role of nonperturbative antiquark degrees of freedom and the valence-quark contribution. A QCD evolution of the obtained GPDs is used to add perturbative effects and to investigate the GPDs' sensitivity to the nonperturbative ingredients of the calculation at larger (experimental) scale.

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic $J^{PC}=1^{-+}$ hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e., as $1/Q^2$. This is due to the nonvanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy-momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next-to-leading order in ${\alpha }_S$ and we explore the consequences of fixing the renormalization scale ambiguity through the Brodsky-Lepage-Mackenzie (BLM) procedure. We study the particular case where the hybrid meson decays through a $\pi \eta$ meson pair. We discuss the $\pi \eta$ generalized distribution amplitude and then calculate the production amplitude for this process. We propose a forward-backward asymmetry in the production of $\pi$ and $\eta$ mesons as a signal for the hybrid meson production. We briefly comment on hybrid electroproduction at very high energy, in the diffractive limit where a QCD Odderon exchange mechanism should dominate. The conclusion of our study is that hard electroproduction is a promising way to study exotic hybrid mesons, in particular, at JLAB, HERA (HERMES), or CERN (Compass).

We calculate the $1P$ heavy-quarkonium fine splittings at next-to-leading order and discuss the impact of the calculation on the ${\chi }_b(1P)$ splittings.

We have measured several branching ratios for ${\psi }^{\prime }$ decay using the data collected by the FNAL E835 experiment during the year 2000, obtaining $\mathcal{B}({\psi }^{\prime }\to e^{+}{e}^{-})=0.0068\pm 0.0001\pm 0.0004$, $\mathcal{B}({\psi }^{\prime }\to J/\psi {\pi }^{+}{\pi }^{-})=0.292\pm 0.005\pm 0.018$, $\mathcal{B}({\psi }^{\prime }\to J/\psi {\pi }^0{\pi }^0)=0.167\pm 0.005\pm 0.014$, and $\mathcal{B}({\psi }^{\prime }\to J/\psi \eta )=0.028\pm 0.002\pm 0.002$. We also present a measurement of the dipion mass distribution in the decays ${\psi }^{\prime }\to J/\psi \pi \pi$.

M theory is considered in its low-energy limit on a $G_2$ manifold with nonvanishing flux. Using the Killing spinor equations for linear flux, an explicit set of first-order bosonic equations for supersymmetric solutions is found. These solutions describe a warped product of a domain wall in four-dimensional space-time and a deformed $G_2$ manifold. It is shown how these domain walls arise from the perspective of the associated four-dimensional $N=1$ effective supergravity theories. We also discuss the inclusion of membrane and M5-brane sources.

We analyze supersymmetric solutions of M-theory based an a seven-dimensional internal space with $\mathrm{S}\mathrm{U}(3)$ structure and a four-dimensional maximally symmetric space. The most general supersymmetry conditions are derived and we show that a nonvanishing cosmological constant requires the norms of the two internal spinors to differ. We find explicit local solutions with singlet flux and the space being a warped product of a circle, a nearly Kähler manifold and ${\mathrm{A}\mathrm{d}\mathrm{S}}_4$. The embedding of solutions into heterotic M-theory is also discussed.

Consistency of present day lattice QCD simulations with dynamical (“sea”) staggered fermions requires that the determinant of the staggered-fermion Dirac operator, $\mathrm{d}\mathrm{e}\mathrm{t}(D)$, be equal to ${\mathrm{d}\mathrm{e}\mathrm{t}}^4(D_{\mathrm{r}\mathrm{g}})\mathrm{d}\mathrm{e}\mathrm{t}(\mathcal{T})$ where $D_{\mathrm{r}\mathrm{g}}$ is a local one-flavor lattice Dirac operator, and $\mathcal{T}$ is a local operator containing only excitations with masses of the order of the cutoff. Using renormalization-group (RG) block transformations I show that, in the limit of infinitely many RG steps, the required decomposition exists for the free staggered operator in the “flavor representation.” The resulting one-flavor Dirac operator $D_{\mathrm{r}\mathrm{g}}$ satisfies the Ginsparg-Wilson relation in the massless case. I discuss the generalization of this result to the interacting theory.

We compute the electromagnetic form factors of the nucleon in quenched lattice QCD, using nonperturbatively improved Wilson fermions, and compare the results with phenomenology and chiral effective field theory.

The contribution of the quark self energy to the meson masses is studied in the framework of the relativistic flux tube model. The equivalence between this phenomenological model and the more QCD based rotating string Hamiltonian is used as a guide to perform the calculations. It is shown that the addition of the quark self energy to the relativistic flux tube model preserves the linearity of the Regge trajectories. But, following the definition taken for the constituent quark masses, the Regge slope is preserved or decreased. In this last case, experimental data can only by reproduced by using a string tension around $0.245{\mathrm{G}\mathrm{e}\mathrm{V}}^2$. Two procedures are also studied to treat the pure flux tube contribution as a perturbation of a spinless Salpeter Hamiltonian.

We present a formalism for the matter effects in the Earth on low energy neutrino fluxes which is both accurate and has all the advantages of a full analytic treatment. The oscillation probabilities are calculated up to the second order term in $ϵ(x)\equiv 2V(x)E/\Delta m^2$, where $V(x)$ is the neutrino potential at position $x$. We show the absence of large undamped phases which makes the expansion in $ϵ$ well behaved. An improved expansion is presented in terms of the variation of $V(x)$ around a suitable mean value which allows one to treat energies up to those relevant for supernova neutrinos. We discuss also the case of three-neutrino mixing.

We consider various processes of single top production at LHC in the theoretical framework of the MSSM and examine the role of the supersymmetric electroweak one-loop corrections in a special moderately light SUSY scenario, in an initial parton-pair c.m. high energy range where a logarithmic asymptotic expansion of Sudakov type can be used. We show that the electroweak virtual effects are systematically large, definitely beyond the relative 10% size, particularly for a final $t{H}^{-}$ pair where a special enhancement is present. We show then in a qualitative way the kind of precision tests of the model that would be obtainable from accurate measurements of the energy distributions of the various cross sections and of the top polarization asymmetries.

In this paper we present a model of Riemannian loop quantum cosmology with a self-adjoint quantum scalar constraint. The physical Hilbert space is constructed using refined algebraic quantization. When matter is included in the form of a cosmological constant, the model is exactly solvable and we show explicitly that the physical Hilbert space is separable, consisting of a single physical state. We extend the model to the Lorentzian sector and discuss important implications for standard loop quantum cosmology.

Lagrangian perturbation theory for cosmological fluid describes structure formation in the quasinonlinear stage well. We present a third-order perturbative equation for Lagrangian perturbation with pressure in both the longitudinal and transverse modes. Then we derive the perturbative solution for simplest case.

We show that Witten-Dijkgraaf-Verlinde-Verlinde equation underlies the construction of $N=4$ superconformal multi-particle mechanics in one dimension, including a $N=4$ superconformal Calogero model.