Using a generalized Weyl formalism, we show how stationary, axisymmetric solutions of the four-dimensional vacuum Einstein equation can be turned into static, axisymmetric solutions of five-dimensional dilaton gravity coupled to a two-form gauge field. This procedure is then used to obtain new solutions of the latter theory describing pairs of extremal magnetic black holes with opposite charges, known as black diholes. These diholes are kept in static equilibrium by membranelike conical singularities stretching along two different directions. We also present solutions describing diholes suspended in a background magnetic field, and with unbalanced charges.

We look for physically realistic initial data in numerical relativity which are in agreement with post-Newtonian approximations. We propose a particular solution of the time-symmetric constraint equation, appropriate to two momentarily static black holes, in the form of a conformal decomposition of the spatial metric. This solution is isometric to the post-Newtonian (PN) metric up to the 2PN order. It represents a nonlinear deformation of the solution of Brill and Lindquist, i.e. an asymptotically flat region is connected to two asymptotically flat (in a certain weak sense) sheets that are the images of the two singularities through appropriate inversion transformations. The total Arnowitt-Deser-Misner mass M as well as the individual masses $m_1$ and $m_2$ (when they exist) are computed by surface integrals performed at infinity. Using second order perturbation theory on the Brill-Lindquist background, we prove that the binary’s interacting mass-energy $M-m_1-m_2$ is well defined at the 2PN order and in agreement with the known post-Newtonian result.

It has been shown that hybrid inflation may end with the formation of non-topological solitons of the inflaton field. As a first step towards a fully realistic picture of the post-inflation era and reheating in supersymmetric hybrid inflation models, we study the classical scalar field equations of a supersymmetric hybrid inflation model using a semianalytical ansatz for the spatial dependence of the fields. Using the minimal D-term inflation model as an example, the inflaton field is evolved using the full 1-loop effective potential from the slow-rolling era to the ${U\left(1\right)\mathrm{}}_{\mathrm{FI}}$ symmetry-breaking phase transition. Spatial perturbations of the inflaton corresponding to quantum fluctuations are introduced for the case where there is spatially coherent ${U\left(1\right)\mathrm{}}_{\mathrm{FI}}$ symmetry breaking. The maximal growth of the dominant perturbation is found to depend only on the ratio of superpotential coupling $\lambda$ to the gauge coupling g. The inflaton condensate fragments to non-topological solitons for $\lambda /g\gtrsim \mathrm{0.09.}$ The possible consequences of nontopological soliton formation in fully realistic supersymmetric hybrid inflation models are discussed.

We calculate parton and generalized parton distributions in Minkowski space using a scalar propagator with a pair of complex conjugate poles. Correct spectral and support properties are obtained only after careful analytic continuation from Euclidean space. Alternately the quark distribution function can be calculated from modified cutting rules, which put the intermediate state on its complex mass shells. Distribution functions agree with those resulting from the model’s Euclidean space double distribution which we calculate via nondiagonal matrix elements of twist-two operators. Thus one can use a wide class of analytic parametrizations of the quark propagator to connect Euclidean space Green functions to light-cone dominated amplitudes.

In a recent paper we pointed out that the mixing of the light neutrinos with heavy gauge singlet states could reconcile the Z-pole data from $e^{+}{e}^{-}$ colliders and the ${\nu }_{\mu }\left({\overline{\nu }}_{\mu }\right)$ scattering data from the NuTeV experiment at Fermilab. We further noted that the mixing angle required to fit the data is much larger than what would be expected from the conventional seesaw mechanism. In this paper, we show how such mixings can be arranged by a judicious choice of the neutrino mass texture. We also argue that by invoking the unification of the Dirac mass matrix for the up-type quarks and the neutrinos, the mass of the heavy states can naturally be expected to lie in the few TeV range. The model is strongly constrained by the lepton flavor changing process $\overrightarrow{\mu }e\gamma$ which requires lepton universality to be violated in the charged channel.

Domain wall networks on the surface of a soliton are studied in a simple theory. It consists of two complex scalar fields, in 3+1 dimensions, with a global $U\left(1\right)\mathrm{}\times Z_n$ symmetry, where $n>\mathrm{}2.\mathrm{}$ Solutions are computed numerically in which one of the fields forms a Q ball and the other field forms a network of domain walls localized on the surface of the Q ball. Examples are presented in which the domain walls lie along the edges of a spherical polyhedron, forming junctions at its vertices. It is explained why only a small restricted class of polyhedra can arise as domain wall networks.

We place new constraints on sources of ionizing and resonance radiation at the epoch of the recombination process using the recent cosmic microwave background temperature and polarization spectra coming from the Wilkinson Microwave Anisotropy Probe (WMAP). We find that non-standard recombination scenarios are still consistent with the current data. In light of this we study the impact that such models can have on the determination of several cosmological parameters. In particular, the constraints on curvature and baryon density appear to be weakly affected by a modified recombination scheme. However, it may affect the current WMAP constraints on inflationary parameters such as the spectral index $n_s$ and its running. Physically motivated models, such as those based on primordial black holes or super heavy dark matter decay, are able to provide a good fit to the current data. Future observations in both temperature and polarization will be needed to more stringently test these models.

Light $\mathrm{CP}$-violating Higgs bosons with a mass lower than 70 GeV might have escaped detection in direct searches at the CERN LEP collider. They may remain undetected in conventional search channels at the Fermilab Tevatron and CERN LHC. In this paper we show that exclusive diffractive reactions may be able to probe for the existence of these otherwise elusive Higgs particles. As a prototype example, we calculate diffractive production cross sections of the lightest Higgs boson within the framework of the minimal supersymmetric standard model with explicit $\mathrm{CP}$ violation. Our analysis shows that the challenging regions of parameter space corresponding to a light $\mathrm{CP}$-violating Higgs boson might be accessible at the LHC provided suitable proton tagging detectors are installed.

In warped supersymmetric grand unification, XY gauge particles appear near the TeV scale along with Kaluza-Klein towers of the standard model gauge fields. In spite of this exotic low-energy physics, the successful gauge coupling unification prediction of the minimal supersymmetric standard model (MSSM) is preserved and proton decay is naturally suppressed. In this paper we study in detail the low-lying mass spectrum of superparticles and grand unified particles in this theory, taking supersymmetry breaking to be localized to the TeV brane. The masses of the MSSM particles, Kaluza-Klein modes, and XY states are all determined by two parameters, one that fixes the strength of the supersymmetry breaking and the other that sets the scale of the infrared brane. A particularly interesting result is that for relatively strong supersymmetry breaking, the XY gauginos and the lowest Kaluza-Klein excitations of the MSSM gauginos may both lie within reach of the CERN Large Hadron Collider, providing the possibility that the underlying unified gauge symmetry and the enhanced $N=2\mathrm{}$ supersymmetry of the theory will both be revealed.

We compute the chromo-field distributions of static color dipoles in the fundamental and adjoint representation of ${SU(N}_c)$ in the loop-loop correlation model and find Casimir scaling in agreement with recent lattice results. Our model combines perturbative gluon exchange with the non-perturbative stochastic vacuum model which leads to confinement of the color charges in the dipole via a string of color fields. We compute the energy stored in the confining string and use low-energy theorems to show consistency with the static quark-antiquark potential. We generalize Meggiolaro’s analytic continuation from parton-parton to gauge-invariant dipole-dipole scattering and obtain a Euclidean approach to high-energy scattering that allows us in principle to calculate S-matrix elements directly in lattice simulations of QCD. We apply this approach and compute the S-matrix element for high-energy dipole-dipole scattering with the presented Euclidean loop-loop correlation model. The result confirms the analytic continuation of the gluon field strength correlator used in all earlier applications of the stochastic vacuum model to high-energy scattering.

The recent observation of $B_d^0\to {\pi }^0{\pi }^0$ and $B_d^0\to {\pi }^0{\pi }^0$ decay modes allows us to make a fresh isospin analysis of $\overrightarrow{B}\pi \pi$ transitions. We find that current experimental data can impose some model-independent constraints on the parameter space of direct $\mathrm{CP}$ violation in $B_d\to {\pi }^{+}{\pi }^{-}$ and $B_d\to {\pi }^0{\pi }^0.$ Furthermore, we establish a direct relationship between the weak phase $\alpha$ and the charge-averaged branching fractions and $\mathrm{CP}$-violating asymmetries of $\overrightarrow{B}\pi \pi$ decays.

The gravitational radiation-reaction force acting on perfect fluids at $3.5$ post-Newtonian order is cast into a form which is directly applicable to numerical simulations. Extensive use is made of metric-coefficient changes induced by functional coordinate transformations, of the continuity equation, as well as of the equations of motion. We also present an expression appropriate for numerical simulations of the radiation field causing the worked out reaction force.

I study the Feynman integrals needed to compute two-loop self-energy functions for general masses and external momenta. A convenient basis for these functions consists of the four integrals obtained at the end of Tarasov’s recurrence relation algorithm. The basis functions are modified here to include one-loop and two-loop counterterms to render them finite; this simplifies the presentation of results in practical applications. I find the derivatives of these basis functions with respect to all squared-mass arguments, the renormalization scale, and the external momentum invariant, and express the results algebraically in terms of the basis. This allows all necessary two-loop self-energy integrals to be efficiently computed numerically using the differential equation in the external momentum invariant. I also use the differential equations method to derive analytic forms for various special cases, including a four-propagator integral with three distinct nonzero masses.

We construct a little Higgs boson model using a simple global symmetry group $\mathrm{SU}\left(9\right)\mathrm{}$ spontaneously broken to $\mathrm{SU}\left(8\right).$ The electroweak interactions are extended to $\mathrm{SU}\left(3\right)\mathrm{}\times U\left(1\right)\mathrm{}$ and embedded in $\mathrm{SU}\left(9\right).$ At the electroweak scale, our model is a two-Higgs-boson doublet model. At the TeV scale, there are additional states, which are responsible for the cancellation of one loop quadratic divergences. We compute the effects of heavy states on the precision electroweak observables and find that the lower bounds on the masses of heavy gauge bosons and fermions are between 1 and 2 TeV.

We study the properties of the $\overrightarrow{B}\pi$ and $\overrightarrow{B}K$ transition form factors in partially quenched QCD by using the approach of partially quenched chiral perturbation theory combined with the static heavy quark limit. We show that the form factors change almost linearly when varying the value of the sea quark mass, whereas the dependence on the valence quark mass contains both the standard and chirally divergent (quenched) logarithms. A simple strategy for the chiral extrapolations in the lattice studies with $N_{\mathrm{sea}}=2\mathrm{}$ is suggested. It consists of the linear extrapolations from the realistically accessible quark masses, first in the sea and then in the valence quark mass. From the present approach, we estimate the uncertainty induced by such extrapolations to be within 5%.

We report on determinations of $|V_{\mathrm{ub}}|$ resulting from studies of the branching fraction and $q^2$ distributions in exclusive semileptonic B decays that proceed via the $\overrightarrow{b}u$ transition. Our data set consists of the $9.7\times {10}^6$ $B\overline{B}$ meson pairs collected at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance with the CLEO II detector. We measure $\mathcal{B}{(B}^0\to {\pi }^{-}{\mathcal{l}}^{+}\nu )=(1.33\mathrm{}\pm 0.18\pm 0.11\pm 0.01\pm 0.07)\times {10}^{-4}$ and $\mathcal{B}{(B}^0\to {\rho }^{-}{\mathcal{l}}^{+}\nu )=(2.17\mathrm{}\pm {0.34}_{-0.54}^{+0.47\mathrm{}}\pm 0.41\pm 0.01)\times {10}^{-4},$ where the errors are statistical, experimental systematic, systematic due to residual form-factor uncertainties in the signal, and systematic due to residual form-factor uncertainties in the cross-feed modes, respectively. We also find $\mathcal{B}{(B}^{+}\to \eta {\mathcal{l}}^{+}\nu )=(0.84\mathrm{}\pm 0.31\pm 0.16\pm 0.09)\times {10}^{-4},$ consistent with what is expected from the $\overrightarrow{B}\pi \mathcal{l}\nu$ mode and quark model symmetries. We extract $|V_{\mathrm{ub}}|$ using light-cone sum rules for $0<~q^2<16\mathrm{}{\mathrm{GeV}}^2$ and lattice QCD for $16{\mathrm{GeV}}^2<~q^2<q_{\max }^2.$ Combining both intervals yields $|V_{\mathrm{ub}}|=(3.24\mathrm{}\pm 0.22\pm {0.13}_{-0.39}^{+0.55\mathrm{}}\pm 0.09)\times {10}^{-3}$ for $\pi \mathcal{l}\nu ,$ and $|V_{\mathrm{ub}}|=(3.00\mathrm{}\pm {0.21}_{-0.35-0.38}^{+0.29+0.49\mathrm{}}\pm 0.28)\times {10}^{-3}$ for $\rho \mathcal{l}\nu ,$ where the errors are statistical, experimental systematic, theoretical, and ρlν form-factor shape, respectively. Our combined value from both decay modes is $|V_{\mathrm{ub}}|=(3.17\mathrm{}\pm {0.17}_{-0.17-0.39}^{+0.16+0.53\mathrm{}}\pm 0.03)\times {10}^{-3}.$

We investigate the flavor and quark-antiquark structure of the polarized nucleon by calculating the parton distribution functions of the nucleon sea using the meson cloud model. We find that the SU(2) flavor symmetry in the light antiquark sea and quark-antiquark symmetry in the strange quark sea are broken, i.e., $\Delta ū<\Delta \overline{d}$ and $\Delta s<\mathrm{}\Delta \overline{s}.$ The polarization of the strange sea is found to be positive, which is in contradiction with previous analyses. We predict a much larger quark-antiquark asymmetry in the polarized strange quark sea than that in the unpolarized strange quark sea. Our results for both the polarized light quark sea and the polarized strange quark sea are consistent with the recent HERMES data.

A framework based on an effective symmetry that is either $\mathrm{G}\mathrm{}\left(224\right)=\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L\times \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_R\times \mathrm{SU}{\mathrm{}\left(4\right)\mathrm{}}^c$ or SO(10) has been proposed (a few years ago) that successfully describes the masses and mixings of all fermions including neutrinos, with seven predictions, in good accord with the data. Baryogenesis via leptogenesis is considered within this framework by allowing for natural phases $(\sim 1/20–1/2)$ in the entries of the Dirac and Majorana mass matrices. It is shown that the framework leads quite naturally, for both thermal as well as nonthermal leptogenesis, to the desired magnitude for the baryon asymmetry. This result is obtained in full accord with the observed features of the atmospheric and solar neutrino oscillations, as well as with those of the quark and charged lepton masses and mixings, and the gravitino constraint. Hereby one obtains a unified description of fermion masses, neutrino oscillations and baryogenesis (via leptogenesis) within a single predictive framework.

Photodisintegration cross sections were measured for deuterium with Laser-Compton scattering $\gamma$ beams at seven energies near threshold. Combined with the preceding data, ${R\left(E\right)=N}_a\sigma v$ for the $p(n,\gamma )\mathrm{D}$ reaction is for the first time evaluated based on experimental data with 6% uncertainty in the energy region relevant to the big bang nucleosynthesis (BBN). The result confirms the theoretical evaluation on which the BBN in the precision era relies.

We present lattice results on the scalar $D_s$ meson and comment on the $D_{\mathrm{sJ}}^{+}\mathrm{}\left(2317\right)\mathrm{}$ state recently discovered by BaBar and confirmed by CLEO, in view of a series of theoretical claims and counterclaims. Lattice predictions in the static limit indicate larger masses than observed for a scalar quark model state. Finite c quark mass corrections seem to further enlarge this discrepancy, in support of a non-quark-antiquark-state interpretation of experiment.