We investigate the $a_0{K}^{+}{K}^{-}$ vertex in the framework of light cone QCD sum rules. We estimate the coupling constant $g_{a_0{K}^{+}{K}^{-}}$ which is an essential ingredient in the analysis of physical processes involving the $a_0\mathrm{}\left(980\right)\mathrm{}$ meson. Our result is somewhat larger than the previous determinations of this coupling constant.

Combining the QCD dipole model with the Good-Walker picture, we formulate the diffractive dissociation of a photon of virtuality $Q^2$ off a hadronic target, in the kinematical regime in which Q is close to the saturation scale and much smaller than the invariant mass of the diffracted system. We show how the formula obtained compares to the DESY HERA data and discuss what can be learned from such a phenomenology. In particular, we argue that the diffractive observables in these kinematics provide useful pieces of information on the saturation regime of QCD.

The leading-order process for the production of a Z boson and a heavy-quark jet at hadron colliders is $g\overrightarrow{Q}\mathrm{ZQ}$ $\mathrm{}(Q=c,b).$ We calculate this cross section at next-to-leading order at the Fermilab Tevatron and the CERN LHC, and compare it with other sources of ZQ events. This process is a background to new physics, and can be used to measure the heavy-quark distribution function.

We study model-independently the implications of nonstandard scalar and pseudoscalar interactions for the decays $\overrightarrow{b}s\gamma ,$ $\overrightarrow{b}sg,$ $\overrightarrow{b}s{\mathcal{l}}^{+}{\mathcal{l}}^{-}$ $(\mathcal{l}=e,\mu )$ and $B_s\to {\mu }^{+}{\mu }^{-}.$ We find sizable renormalization effects from scalar and pseudoscalar four-quark operators in the radiative decays and at $O\left({\alpha }_s\right)$ in hadronic b decays. Constraints on the Wilson coefficients of an extended operator basis are worked out. Further, the ratios $R_H=\mathcal{B}\left(\overrightarrow{B}H{\mu }^{+}{\mu }^{-}\right)/\mathcal{B}\left(\overrightarrow{B}{\mathrm{He}}^{+}{e}^{-}\right),$ for ${H=K}^{\left(*\right)}{,X}_s,$ and their correlations with the $B_s\to {\mu }^{+}{\mu }^{-}$ decay are investigated. We show that the standard model prediction for these ratios defined with the same cut on the dilepton mass for electron and muon modes, $R_H{=1+O(m}_{\mu }^2{/m}_b^2),$ has a much smaller theoretical uncertainty $(\lesssim 1\%)$ than the one for the individual branching fractions. The present experimental limit $R_K<~1.2$ puts constraints on scalar and pseudoscalar couplings, which are similar to the ones from current data on $\mathcal{B}{(B}_s\to {\mu }^{+}{\mu }^{-}).\mathrm{}$ We find that new physics corrections to $R_{K^{*}}$ and $R_{X_s}$ can reach 13% and 10%, respectively.

We show that in a quark model scheme the use of a screened potential, suggested by lattice QCD, instead of one infinitely rising with the interquark distance, provides a more adequate description of the high-energy baryon spectrum. In particular, an almost perfect parallelism between the predicted and observed number of states comes out, throwing new light on the so-called missing resonance problem.

We present a measurement of the branching fraction of the decay $B^{\pm }\to {\chi }_{c0\mathrm{}}{K}^{\pm }$ from a sample of $89\times {10}^6$ $B\overline{B}$ pairs collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B factory. The ${\chi }_{c0\mathrm{}}$ meson is reconstructed through its two-body decays to ${\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}.$ We measure $\mathcal{B}{(B}^{\pm }\overrightarrow{}{\chi }_{c0\mathrm{}}{K}^{\pm })\times \mathcal{B}({\chi }_{c0\mathrm{}}\overrightarrow{}{\pi }^{+}{\pi }^{-})=[{1.32}_{-0.27}^{+0.28\mathrm{}}\left(\mathrm{stat}\right)\pm 0.26\left(\mathrm{syst}\right)]\times {10}^{-6}$ and $\mathcal{B}{(B}^{\pm }\overrightarrow{}{\chi }_{c0\mathrm{}}{K}^{\pm })\times \mathcal{B}({\chi }_{c0\mathrm{}}\overrightarrow{}{K}^{+}{K}^{-})=[{1.49}_{-0.34}^{+0.36\mathrm{}}\left(\mathrm{stat}\right)\pm 0.22\left(\mathrm{syst}\right)]\times {10}^{-6}.$ Using the known values for the ${\chi }_{c0\mathrm{}}$ decays branching fractions, we combine these results to obtain $\mathcal{B}{(B}^{\pm }\to {\chi }_{c0\mathrm{}}{K}^{\pm })=(2.7\mathrm{}\pm 0.7)\times {10}^{-4}.$

The open-closed vertex in the maximally supersymmetric type IIB plane-wave light-cone string field theory is considered and an explicit solution for the bosonic part of the vertex is derived, valid for all values of the mass parameter μ. This vertex is of relevance to type IIB plane-wave orientifolds, as well type IIB plane-wave strings in the presence of D-branes and their gauge theory duals. Methods of complex analysis are used to develop a systematic procedure for obtaining the solution. This procedure is first applied to the vertex in flat space and then extended to the plane-wave case. The plane-wave solution for the vertex requires introducing certain “μ-deformed Gamma functions,” which are generalizations of the ordinary Gamma function. The behavior of the Neumann matrices is graphically illustrated and their large-μ asymptotics are analyzed.

We study the D-term contribution for anomalous $U\left(1\right)\mathrm{}$ symmetries in type I string models and derive a general formula for the D-term contribution, assuming that the dominant source of supersymmetry breaking is given by the F terms of the dilaton, (overall) moduli, or twisted moduli fields. On the basis of the formula, we also point out that there are several features different from the case of heterotic string models. The differences originate from the different forms of the Kähler potential between twisted moduli fields in type I string models and the dilaton field in heterotic string models.

We analyze the performance of a perturbation theory for nonlinear cosmological dynamics, based on the Lagrangian description of hydrodynamics. In our previous paper, we solved the hydrodynamic equations for a self-gravitating fluid with pressure, given by a polytropic equation of state, using a perturbation method. Then we obtained the first-order solutions in generic background universes and the second-order solutions for a wider range of polytrope exponents. Using these results, we describe density fields with a scale-free spectrum, SCDM, and LCDM models. Then we analyze the cross-correlation coefficient of the density field between N-body simulation and Lagrangian linear perturbation theory, and the probability distribution of the density fluctuations. From our analyses, for scale-free spectrum models, the case of the polytrope exponent 5/3 shows better performance than the Zel’dovich approximation and the truncated Zel’dovich approximation in the quasinonlinear regime. On the other hand, for SCDM and LCDM models, the improvement by including the effect of the velocity dispersion was small.

We calculate the unregularized monopole and dipole contributions to the self-force acting on a particle of small mass in a circular orbit around a Schwarzschild black hole. From a self-force point of view, these nonradiating modes are as important as the radiating modes with $l>~2.$ In fact, we demonstrate how the dipole self-force contributes to the dynamics even at the Newtonian level. The self-acceleration of a particle is an inherently gauge-dependent concept, but the Lorenz gauge is often preferred because of its hyperbolic wave operator. Our results are in the Lorenz gauge and are also obtained in closed form, except for the even-parity dipole case where we formulate and implement a numerical approach.

We solve the equations of motion numerically for real self-interacting scalar fields in the background of a Reissner-Nordström black hole and obtain a sequence of static axisymmetric solutions representing thick domain wall charged black hole systems. In the case of an extremal Reissner-Nordström black hole solution we find that there is a parameter depending on the black hole mass and the width of the domain wall which constitutes the upper limit for the expulsion to occur.

We give a full nonlinear numerical treatment of time-dependent 5D braneworld geometry, which is determined self-consistently by potentials for the scalar field in the bulk and at two orbifold branes, supplemented by boundary conditions at the branes. We describe the BRANECODE, an algorithm which we designed to solve the dynamical equations numerically. We apply the BRANECODE to braneworld models and find several novel phenomena of the brane dynamics. Starting with static warped geometry with de Sitter branes, we find numerically that this configuration is often unstable due to a tachyonic mass of the radion during inflation. If the model admits other static configurations with lower values of de Sitter curvature, this effect causes a violent restructuring towards them, flattening the branes, which appears as a lowering of the 4D effective cosmological constant. Braneworld dynamics can often lead to brane collisions. We find that, in the presence of the bulk scalar field, the 5D geometry between colliding branes approaches a universal, homogeneous, anisotropic strong gravity Kasner-like asymptotic, irrespective of the bulk or brane potentials. The Kasner indices of the brane directions are equal to each other but different from that of the extra dimension.

The possibility that the cosmic variance outliers present in the recently released Wilkinson Microwave Anisotropy Probe (WMAP) multipole moments are due to oscillations in the primordial power spectrum is investigated. Since the most important contribution to the WMAP likelihood originates from the outliers at a relatively small angular scale (around the first Doppler peak), special attention is paid to these in contrast with previous studies on the subject which have concentrated on the large scales outliers only (i.e., the quadrupole and octupole). As a physically motivated example, the case where the oscillations are of trans-Planckian origin is considered. It is shown that the presence of the oscillations causes an important drop in the WMAP ${\chi }^2$ of about 15. The F test reveals that such a drop has a probability less than 0.06% to occur by chance and can therefore be considered as statistically significant.

We use statistical inference theory to explore the constraints from future galaxy weak lensing (cosmic shear) surveys combined with the current CMB constraints on cosmological parameters, focusing particularly on the running of the spectral index of the primordial scalar power spectrum, ${\alpha }_s.$ Recent papers have drawn attention to the possibility of measuring ${\alpha }_s$ by combining the CMB with galaxy clustering and/or the Lyman-$\alpha$ forest. Weak lensing combined with the CMB provides an alternative probe of the primordial power spectrum. We run a series of simulations with variable runnings and compare them to semianalytic nonlinear mappings to test their validity for our calculations. We find that a “reference” cosmic shear survey with $f_{\mathrm{sky}}=0.01\mathrm{}$ and $6.6\times {10}^8$ galaxies per steradian can reduce the uncertainty on $n_s$ and ${\alpha }_s$ by roughly a factor of 2 relative to the CMB alone. We investigate the effect of shear calibration biases on lensing by including the calibration factor as a parameter, and show that for our reference survey, the precision of cosmological parameter determination is only slightly degraded even if the amplitude calibration is uncertain by as much as 5%. We conclude that in the near future weak lensing surveys can supplement the CMB observations to constrain the primordial power spectrum.

Planning is underway for several space-borne gravitational wave observatories to be built in the next 10 to 20 years. Realistic and efficient forward modeling will play a key role in the design and operation of these observatories. Space-borne interferometric gravitational wave detectors operate very differently from their ground-based counterparts. Complex orbital motion, virtual interferometry, and finite size effects complicate the description of space-based systems, while nonlinear control systems complicate the description of ground-based systems. Here we explore the forward modeling of space-based gravitational wave detectors and introduce an adiabatic approximation to the detector response that significantly extends the range of the standard low frequency approximation. The adiabatic approximation will aid in the development of data analysis techniques, and improve the modeling of astrophysical parameter extraction.

In supersymmetric theories with extra dimensions, the Higgs and matter fields can be part of the gauge multiplet, so that the Yukawa interactions can arise from the gauge interactions. This leads to the possibility of gauge-Yukawa coupling unification, $g_i{=y}_f,$ in the effective four-dimensional theory after the initial gauge symmetry and the supersymmetry are broken upon orbifold compactification. We consider gauge-Yukawa unified models based on a variety of four-dimensional symmetries, including $\mathrm{SO}\left(10\right),$ $\mathrm{SU}\left(5\right),$ Pati-Salam symmetry, trinification, and the standard model. Only in the case of Pati-Salam and the standard model symmetry, we obtain gauge-Yukawa unification. Partial gauge-Yukawa unification is also briefly discussed.

We study the bound states of the Kaluza-Klein (KK) excitations of quarks in certain models of universal extra dimensions. Such bound states may be detected at future lepton colliders in the cross section for the pair production of KK quarks near threshold. For typical values of model parameters, we find that “KK quarkonia” have widths in the 10–100 MeV range, and production cross sections of the order of a few picobarns for the lightest resonances. Two body decays of the constituent KK quarks lead to distinctive experimental signatures. We point out that such KK resonances may be discovered before any of the higher KK modes.

Supported by recent lattice results, we consider a scenario in which a $U\left(1\right)\mathrm{}$-breaking condensate survives across the chiral transition in QCD. This scenario has important consequences for the pseudoscalar-meson sector, which can be studied using an effective Lagrangian model. In particular, generalizing the results obtained in a previous paper (where the zero-temperature case was considered), we study the effects of this $U\left(1\right)\mathrm{}$ chiral condensate on the radiative decay ${\eta }^{\prime }\to \gamma \gamma$ at finite temperature.

We study ${\Theta }^{+}\mathrm{}\left(1540\right)\mathrm{}$ production in kaon-nucleon $\mathrm{}\left(\mathrm{KN}\right)\mathrm{}$ and nucleon-nucleon $\mathrm{}\left(\mathrm{NN}\right)\mathrm{}$ interactions by assuming that the ${\Theta }^{+}$ is an isosinglet with $J^P={\frac{1}{2}}^{+}.$ Possible t-channel diagrams with $K^{*}$ exchange are considered in both reactions as well as K exchange in NN reactions. The cross section for $n\overrightarrow{p}{\Lambda }^0{\Theta }^{+},$ which has not been considered in previous calculations, is found to be about a factor of 5 larger than that for $n\overrightarrow{p}{\Sigma }^0{\Theta }^{+}$ due to the large coupling of the $\mathrm{KN}\Lambda$ interaction. The cross sections are obtained by setting $g_{\mathrm{KN}\Theta }=1\mathrm{}$ and varying the ratio of $g_{K^{*}N\Theta }{/g}_{\mathrm{KN}\Theta }$ so that future experimental data can be used to estimate these couplings. We also find that the isospin relations hold for these reactions.