We use chiral perturbation theory to study the extrapolations necessary to make physical predictions from lattice QCD data for the electromagnetic form factors of pseudoscalar mesons. We focus on the quark mass, momentum, lattice spacing, and volume dependence and apply our results to simulations employing mixed actions of Ginsparg-Wilson valence quarks and staggered sea quarks. To determine charge radii at quark masses on the lattices currently used, we find that all extrapolations except the one to infinite volume make significant contributions to the systematic error.

The $b\to dd\overline{s}$ transition gives extremely small branching ratios within the standard model, thus providing an appropriate ground for testing new physics. Using renormalization group technique we determine the Wilson coefficients and the mixing of the operators which contribute to the $b\to dd\overline{s}$ transition. We consider contributions to this decay mode from the supersymmetric standard model with and without $\mathcal{R}$ parity, as well as from a model with an additional neutral $Z^{\prime }$ gauge boson. Using Belle and BABAR upper bounds for the $B^{-}\to {\pi }^{-}{\pi }^{-}{K}^{+}$ branching ratio we constrain contributions of these new physics scenarios. Then we calculate branching ratios for two- and three-body nonleptonic $B^{-}$ meson decays driven by the $b\to dd\overline{s}$ transition, which might be experimentally accessible.

We study the effects of the minimal extension of the standard model including Lorentz violation on the Casimir force between two parallel conducting plates in the vacuum. We provide explicit solutions for the electromagnetic field using scalar field analogy, for both the cases in which the Lorentz violating terms come from the $CPT$-even or $CPT$-odd terms. We also calculate the effects of the Lorentz violating terms for a fermion field between two parallel conducting plates and analyze the modifications of the Casimir force due to the modifications of the Dirac equation. In all cases under consideration, the standard formulas for the Casimir force are modified by either multiplicative or additive correction factors, the latter case exhibiting different dependence on the distance between the plates.

In AdS/CFT duality, it is often argued that information behind the event horizon is encoded even in boundary correlators. However, its implication is not fully understood. We study a simple model which can be analyzed explicitly. The model is a two-dimensional scalar field propagating on the $s$-wave sector of the BTZ black hole formed by the gravitational collapse of a null dust. Inside the event horizon, we placed an artificial timelike singularity where one-parameter family of boundary conditions is permitted. We compute two-point correlators with two operators inserted on the boundary to see if the parameter can be extracted from the correlators. In a typical case, we give an explicit form of the boundary correlators of an initial vacuum state and show that the parameter can be read off from them. This does not immediately imply that the asymptotic observer can extract the information of the singularity since one cannot control the initial state in general. Thus, we also study whether the parameter can be read off from the correlators for a class of initial states.

An inhomogeneous Kaluza-Klein compactification of a higher dimensional spacetime may give rise to an effective 4D spacetime with distinct domains having different sizes of the extra dimensions. The domains are separated by domain walls generated by the extra dimensional scale factor. The scattering of electromagnetic and massive particle waves at such boundaries is examined here for models without warping or branes. We consider the limits corresponding to thin (thick) domain walls, i.e., limits where wavelengths are large (small) in comparison to wall thickness. We also obtain numerical solutions for a wall of arbitrary thickness and extract the reflection and transmission coefficients as functions of frequency. Results are obtained which qualitatively resemble those for electroweak domain walls and other ordinary domain walls for 4D theories.

Motivated by their gravitational wave driven instability, we investigate the influence of the crust on $r$-mode oscillations in a neutron star. Using a simplistic model of an elastic neutron star crust with constant shear modulus, we carry out an analytic calculation with the main objective of deriving an expression for the slippage between the core and the crust. Our analytic estimates support previous numerical results and provide useful insights into the details of the problem.

The Gerlach and Sengupta (GS) formalism of coordinate-invariant, first-order, spherical and nonspherical perturbations around an arbitrary spherical spacetime is generalized to higher orders, focusing on second-order perturbation theory. The GS harmonics are generalized to an arbitrary number of indices on the unit sphere and a formula is given for their products. The formalism is optimized for its implementation in a computer-algebra system, something that becomes essential in practice given the size and complexity of the equations. All evolution equations for the second-order perturbations, as well as the conservation equations for the energy-momentum tensor at this perturbation order, are given in covariant form, in Regge-Wheeler gauge.

We study static, spherically symmetric, Skyrme black holes in the context of the assumption that they can be viewed as bound states between ordinary bare black holes and solitons. This assumption and results stemming from the isolated horizons formalism lead to several conjectures about the static black hole solutions. These conjectures are tested against the Skyrme black hole solutions. It is shown that, while there is in general good agreement with the conjectures, a crucial aspect seems to violate one of the conjectures.

In addition to a smooth component of weakly interacting massive particle (WIMP) dark matter in galaxies, there may be streams of material; the effects of WIMP streams on direct detection experiments is examined in this paper. The contribution to the count rate due to the stream cuts off at some characteristic energy. Near this cutoff energy, the stream contribution to the annual modulation of recoils in the detector is comparable to that of the thermalized halo, even if the stream represents only a small portion ($\sim 5\%$ or less) of the local halo density. Consequently the total modulation may be quite different than would be expected for the standard halo model alone: it may not be cosinelike and can peak at a different date than expected. The effects of speed, direction, density, and velocity dispersion of a stream on the modulation are examined. We describe how the observation of a modulation can be used to determine these stream parameters. Alternatively, the presence of a dropoff in the recoil spectrum can be used to determine the WIMP mass if the stream speed is known. The annual modulation of the cutoff energy together with the annual modulation of the overall signal provide a “smoking gun” for WIMP detection.

We discuss how in supersymmetric models with $D$ and $F$-flat directions, a primordial monopole flux of order ${10}^{-16}–{10}^{-18}{\mathrm{cm}}^{-2}{\sec }^{-1}{\mathrm{sr}}^{-1}$ can coexist with the observed baryon asymmetry. A modified Affleck-Dine scenario yields the desired asymmetry if the monopoles are superheavy ($\sim {10}^{13}–{10}^{18}\mathrm{GeV}$). For lighter monopoles with masses $\sim {10}^9–{10}^{12}\mathrm{GeV}$, the baryon asymmetry can arise via TeV scale leptogenesis.

We calculate the branching ratio of ${\Lambda }_b\to \Lambda \gamma$ in the standard model using the PQCD method. The predicted branching ratio $B({\Lambda }_b\to \Lambda \gamma )$ is about $(4.3\sim 8.6)\times {10}^{-8}$, with reasonable parameter ranges in the heavy baryon distribution amplitude. This branching ratio is much smaller than those obtained in other hadronic model calculations. Future experimental data can provide important information on applicability of the PQCD method to heavy baryon radiative decay.

A consistent SU(6) extension of the Weinberg-Tomozawa meson-baryon chiral Lagrangian is constructed which incorporates vector meson and baryon decuplet degrees of freedom. The corresponding Bethe-Salpeter approximation predicts the existence of an isoscalar spin-parity $\frac{3^{-}}{2}$ $K^{*}N$ bound state (strangeness $+1$) with a mass around 1.7–1.8 GeV. It is the highest hypercharge state of an antidecuplet SU(3) representation and it is unstable through $K^{*}$ decay. The estimated width of this state (neglecting $d$-wave $KN$ decay) turns out to be small ($\Gamma \le 15\mathrm{MeV}$). Clear signals of this resonance would be found in reactions like $\gamma p\to {\overline{K}}^{0}p{K}^{+}{\pi }^{-}$ by looking at the three body $p{K}^{+}{\pi }^{-}$ invariant mass.

We discuss the possible impact of astrophysical neutrino flux measurements at neutrino telescopes on the neutrino oscillation program of reactor experiments and neutrino beams. We consider neutrino fluxes from neutron sources, muon damped sources, and pion sources, where we parametrize the input from these sources in terms of the flux ratio $R={\varphi }_{\mu }/({\varphi }_e+{\varphi }_{\tau })$ which can be extracted from the muon track to shower ratio in a neutrino telescope. While it is difficult to obtain any information from this ratio alone, we demonstrate that the dependence on the oscillation parameters is very complementary to the one of reactor experiments and neutrino beams. We find that, for large values of ${sin}^{2}2{\theta }_{13}$, a measurement of $R$ with a precision of about 20% or better may not only improve the measurement of the leptonic $CP$ phase, but also help the determination of the mass hierarchy. In some cases, early information on ${\delta }_{CP}$ may even be obtained from Double Chooz and an astrophysical flux alone without the help of superbeams. For small values of ${sin}^{2}2{\theta }_{13}$, we find that using the information from an astrophysical neutrino flux could eliminate the octant degeneracy better than reactor experiments and beams alone. Finally, we demonstrate that implementing an additional observable based on the electromagnetic to hadronic shower ratio at a neutrino telescope (such as at higher energies) could be especially beneficial for pion beam sources.

In this work, we calculate the leading order corrections to general relativity formulated on a canonical noncommutative spacetime. These corrections appear in the second order of the expansion in theta. First order corrections can only appear in the gravity-matter interactions. Some implications are briefly discussed.

We investigate the possible decay of protons in geodesic circular motion around neutral compact objects. Weak and strong decay rates and the associated emitted powers are calculated using a semiclassical approach. Our results are discussed with respect to distinct ones in the literature, which consider the decay of accelerated protons in electromagnetic fields. A number of consistency checks are presented along the paper.

Under the hypotheses of smoothness in the coupling constant, locality, Lorentz covariance, and Poincaré invariance of the deformations, combined with the preservation of the number of derivatives on each field, the consistent interactions between a single free massless tensor gauge field with the mixed symmetry of a two-column Young diagram of the type (3,1) and one Abelian vector field have been investigated. The computations are done with the help of the deformation theory based on a cohomological approach, in the context of the antifield-BRST formalism. The main result is that there exist nontrivial cross-couplings between these types of fields in five spatiotemporal dimensions, which break the PT invariance and allow for the deformation of the gauge transformations of the vector field, but not of the gauge algebra.

The action of Weyl scale invariant $p=2$ brane which breaks the target super-Weyl scale symmetry in the $N=1$, $D=4$ superspace down to the lower dimensional Weyl symmetry $W(1,2)$ is derived by the approach of nonlinear realization. The dual form action for the Weyl scale invariant supersymmetric D2 brane is also constructed. The interactions of localized matter fields on the brane with the Nambu-Goldstone fields associated with the breaking of the symmetries in the superspace and one spatial translation directions are obtained through the Cartan one-forms of the Coset structures. The covariant derivatives for the localized matter fields are also obtained by introducing Weyl gauge field as the compensating field corresponding to the local scale transformation on the brane world volume.

To investigate the nonperturbative, electric sector of a deconfined gauge theory at nonzero temperature, we consider a $SU(2)$ matrix model. We compute $\beta$-functions to one loop order for the simplest extension of the $O(4)$ nonlinear sigma model, which involves three coupling constants. Computing in the ultraviolet limit in $2+ϵ$ dimensions, we find that at least one coupling is not asymptotically free.

Bekenstein’s theory of relativistic gravity is conventionally written as a bimetric theory. The two metrics are related by a disformal transformation defined by a dynamical vector field and a scalar field. In this paper we show that the theory can be rewritten as vector-tensor theory akin to Einstein-Aether theories with noncanonical kinetic terms. We discuss some of the implications of this equivalence.