We show that the commonly known conductor boundary conditions $E_{||}=B_{\perp }=0$ can be realized in two ways which we call “thick” and “thin” conductor. The thick conductor is the commonly known approach and includes a Neumann condition on the normal component $E_{\perp }$ of the electric field whereas for a thin conductor $E_{\perp }$ remains without boundary condition. Both types describe different physics already on the classical level where a thin conductor allows for an interaction between the normal components of currents on both sides. On quantum level different forces between a conductor and a single electron or a neutral atom result. For instance, the Casimir-Polder force for a thin conductor is by about 13% smaller than for a thick one.

I prove the uniqueness theorem for stationary self-gravitating nonlinear $\sigma$-models in five-dimensional spacetime. I show that the Myers-Perry vacuum Kerr spacetime is the only maximally extended, stationary, axisymmetric asymptotically flat solution having the regular rotating event horizon with a constant mapping.

We investigate AdS/CFT correspondence for two families of Einstein black holes in $d\ge 4$ dimensions, modeling the boundary conformal field theory by a free conformal scalar field and evaluating the boundary two-point function in the bulk geodesic approximation. For the $d\ge 4$ counterpart of the nonrotating Bãnados-Teitelboim-Zanelli hole and for its ${\mathbb{Z}}_2$ quotient, the boundary state is thermal in the expected sense, and its stress-energy reflects the properties of the bulk geometry and suggests a novel definition for the mass of the hole. For the generalized Schwarzschild-AdS hole with a flat horizon of topology ${\mathbb{R}}^{d-2}$, the boundary stress-energy has a thermal form with energy density proportional to the hole Arnowitt-Deser-Misner mass, but stress-energy corrections from compactified horizon dimensions cannot be consistently included at least for $d=5$.

Assuming that cosmological dark matter consists of weakly interacting massive particles, we use the recent precise measurement of cosmological parameters to predict the guaranteed rates of production of such particles in association with photons at electron-positron colliders. Our approach is based on general physical principles such as detailed balancing and soft/collinear factorization. It leads to predictions that are valid across a broad range of models containing WIMPs, including supersymmetry, universal extra dimensions, and many others. We also discuss the discovery prospects for the predicted experimental signatures.

Adding to the long standing “$\rho \pi$ puzzle” in ${\psi }^{\prime }$ and $J/\psi$ decays, recently BEijing Spectrometer (BES) reported $\mathcal{B}({\psi }^{\prime }\to K_S^0{K}_L^0)$ which is enhanced relative to the perturbative QCD (pQCD) “12% rule” expectation from $\mathcal{B}(J/\psi \to K_S^0{K}_L^0)$. If the enhancement is due to the mixing of the $S$- and $D$-wave charmonium states as in the $\rho \pi$ case, the newly measured $\mathcal{B}({\psi }^{\prime }\to K_S^0{K}_L^0)$ gives a constraint on $\mathcal{B}({\psi }^{\prime \prime }\to K_S^0{K}_L^0)$. It serves as a good test for the scenario of the $S$- and $D$-wave mixing in the ${\psi }^{\prime }$ and ${\psi }^{\prime \prime }$.

A general discussion is given of signals for broken Lorentz symmetry in short-baseline neutrino experiments. Among the effects that Lorentz violation can introduce are a dependence on energy differing from that of the usual massive-neutrino solution and a dependence on the direction of neutrino propagation. Using the published result of the Liquid Scintillator Neutrino Detector experiment, analysis of the effects of broken Lorentz symmetry yields an estimated nonzero value $(3\pm 1)\times {10}^{-19}\mathrm{G}\mathrm{e}\mathrm{V}$ for a combination of coefficients for Lorentz violation. This lies in the range expected for effects originating from the Planck scale in an underlying unified theory.

Boundary conditions on an extra dimensional interval can be chosen to break bulk gauge symmetries and to reduce the rank of the gauge group. We consider this mechanism in models with gauge trinification. We determine the boundary conditions necessary to break the trinified gauge group directly down to that of the standard model. Working in an effective theory for the gauge-symmetry-breaking parameters on a boundary, we examine the limit in which the grand-unified theory-breaking-sector is Higgsless and show how one may obtain the low-energy particle content of the minimal supersymmetric standard model. We find that gauge unification is preserved in this scenario, and that the differential gauge coupling running is logarithmic above the scale of compactification. We compare the phenomenology of our model to that of four dimensional “trinified” theories.

We investigate the role played by the fermionic determinant in the evaluation of the $CP$-violating neutron electric dipole moment (EDM) adopting the Instanton Liquid Model. Significant differences between quenched and unquenched calculations are found. In the case of unquenched simulations the neutron EDM decreases linearly with the quark mass and is expected to vanish in the chiral limit. On the contrary, within the quenched approximation, the neutron EDM increases as the quark mass decreases and is expected to diverge as $1/m^{N_f}$ in the chiral limit. We argue that such a qualitatively different behavior is a parameter-free, semiclassical prediction and occurs because the neutron EDM is sensitive to the topological structure of the vacuum. The present analysis suggests that quenched and unquenched lattice QCD simulations of the neutron EDM as well as of other observables governed by topology might show up important differences in the quark mass dependence for $m_q\lesssim {\Lambda }_{QCD}$.

We present three-loop next-to-next-to-next-to-leading order corrections to the heavy-to-heavy quark transitions in the limit of equal initial and final quark masses. In analogy with the previously found next-to-next-to-leading order corrections, the bulk of the result is due to the ${\beta }_0^2{\alpha }_s^3$ corrections. The remaining genuine three-loop effects for the semileptonic $b\to c$ decays are estimated to increase the decay amplitude by 0.2(2)%. The perturbative series for the heavy-heavy axial current converges very well.

It is argued that the single-spin asymmetry in the reaction ${\pi }^{-}p\to a_0^0(980)n\to (\eta {\pi }^0{)}_{S}n$ is extremely sensitive to the mixing of the $a_0^0(980)$ and $f_0(980)$ resonances. It is shown that at low momentum transfers (namely, in any one of the intervals $0\le -t\le 0.025,...,0.1{\mathrm{G}\mathrm{e}\mathrm{V}}^2$) the normalized asymmetry, which can take the values from $-1$ to 1, must undergo a jump in magnitude close to 1 in the $\eta {\pi }^0$ invariant mass region between 0.965 GeV and 1.01 GeV. The strong asymmetry jump is the straightforward manifestation of the $a_0^0(980)-f_0(980)$ mixing. For observing the jump, any very high quality $\eta {\pi }^0$ mass resolution is not required. The energy dependence of the polarization effect is expected to be rather weak. Therefore, it can be investigated at any high energy, for example, in the range from eight to 100 GeV.

Heavy-hadron chiral perturbation theory ($\mathrm{H}\mathrm{H}\chi \mathrm{P}\mathrm{T}$) is applied to the decays of the even-parity charmed strange mesons, $D_{s0}(2317)$ and $D_{s1}(2460)$. Heavy-quark spin-symmetry predicts the branching fractions for the three electromagnetic decays of these states to the ground states $D_s$ and $D_s^{*}$ in terms of a single parameter. The resulting predictions for two of the branching fractions are significantly higher than current upper limits from the CLEO experiment. Leading corrections to the branching ratios from chiral loop diagrams and spin-symmetry violating operators in the $\mathrm{H}\mathrm{H}\chi \mathrm{P}\mathrm{T}$ Lagrangian can naturally account for this discrepancy. Finally the proposal that the $D_{s0}(2317)$ ($D_{s1}(2460)$) is a hadronic bound state of a $D(D^{*})$ meson and a kaon is considered. Leading order predictions for electromagnetic branching ratios in this molecular scenario are in very poor agreement with existing data.

We analyze the structure of current-current correlators in coordinate space in the large $N_c$ limit when the corresponding spectral density takes the form of an infinite sum over hadron poles. The latter are computed in the QCD string model with quarks at the ends, including the lowest states, for all channels. The corresponding correlators demonstrate reasonable qualitative agreement with the lattice data without any additional fits. Different issues concerning the structure of the short-distance operator product expansion are discussed.

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at $\sqrt{s}=1800\mathrm{G}\mathrm{e}\mathrm{V}$ and $\sqrt{s}=630\mathrm{G}\mathrm{e}\mathrm{V}$ and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in $\eta -\varphi$ space are defined, at the same pseudorapidity, $\eta$, as the jet with the highest transverse energy ($E_T^{(1)}$), and at $\pm {90}^o$ in the azimuthal direction, $\varphi$. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of $E_T^{(1)}$ and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet $E_T^{(1)}$ over most of the measured range. This study was carried out using data from the CDF detector taken during Run 1 (1994-1995). The study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. The distribution of the sum of the track momenta in the two cones is also examined for five different $E_T^{(1)}$ bins. The HERWIG and PYTHIA Monte Carlo generators are reasonably successful in describing the data, but neither can describe completely all of the event properties.

We present a family of globally regular $\mathcal{N}=1$ vacua in the $\mathrm{D}=4$, $\mathcal{N}=4$ gauged supergravity of Gates and Zwiebach. These solutions are labeled by the ratio $\xi$ of the two gauge couplings, and for $\xi =0$ they reduce to the supergravity monopole previously used for constructing the gravity dual of $\mathcal{N}=1$ super Yang-Mills theory. For $\xi >0$ the solutions are asymptotically anti- de Sitter, but with an excess of the solid angle, and they reduce exactly to anti-de Sitter for $\xi =1$. Solutions with $\xi <0$ are topologically $R^1\times S^3$, and for $\xi =-2$ they become $R^1\times S^3$ geometrically. All solutions with $\xi \ne 0$ can be promoted to $\mathrm{D}=11$ to become vacua of M-theory.

The Kerr spinning particle has a remarkable analytical twistorial structure. Analyzing electromagnetic excitations of the Kerr circular string which are aligned to this structure, we obtain a simple stringy skeleton of the spinning particle which is formed by a topological coupling of the Kerr circular singular string and by an axial singular stringy system. We show that the chiral traveling waves, related to an orientifold world sheet of the axial stringy system, are described by the massive Dirac equation, so we argue that the axial string may play the part of a stringy carrier of wave function and play also a dominant role in the scattering processes. A key role of the third, complex Kerr string is discussed. We conjecture that it may be one more alternative to the Witten twistor string, and a relation to the spinor helicity formalism is also discussed.

We study the possibility that the baryon asymmetry of the Universe is generated in a minimal seesaw scenario where two right-handed Majorana neutrinos with degenerate masses are added to the standard model particle content. In the usual framework of thermal leptogenesis, a nonzero $CP$ asymmetry can be obtained through the mass splitting induced by the running of the heavy Majorana neutrino masses from their degeneracy scale down to the seesaw scale. Although, in the light of the present neutrino oscillation data, the produced baryon asymmetry turns out to be smaller than the experimental value, the present mechanism could be viable in simple extensions of the standard model.

We investigate static axially symmetric black hole solutions in a four-dimensional Einstein-Yang-Mills-SU(2) theory with a negative cosmological constant $\Lambda$. These solutions approach asymptotically the anti-de Sitter spacetime and possess a regular event horizon. A discussion of the main properties of the solutions and the differences with respect to the asymptotically flat case is presented. The mass of these configurations is computed by using a counterterm method. We note that the $\Lambda =-3$ configurations have a higher dimensional interpretation in context of $d=11$ supergravity. The existence of axially symmetric monopole and dyon solutions in a fixed Schwarzschild-anti-de Sitter background is also discussed. An exact solution of the Einstein-Yang-Mills equations is presented in the appendix.

The evolution of a nonaxisymmetric bar-mode perturbation of rapidly rotating stars due to a secular instability induced by gravitational wave emission is studied in post-Newtonian simulations taking into account gravitational radiation reaction. A polytropic equation of state with the polytropic index $n=1$ is adopted. The ratio of the rotational kinetic energy to the gravitational potential energy $T/|W|$ is chosen in the range between 0.2 and 0.26. Numerical simulations were performed until the perturbation grows to the nonlinear regime, and illustrate that the outcome after the secular instability sets in is an ellipsoidal star of a moderately large ellipticity $\gtrsim 0.7$. A rapidly rotating protoneutron star may form such an ellipsoid, which is a candidate for strong emitter of gravitational waves for ground-based laser interferometric detectors. A possibility that effects of magnetic fields neglected in this work may modify the growth of the secular instability is also mentioned.

While inflaton loops in the Euclidean vacuum generally have a negligible contribution to the power spectrum, loop effects can be substantially larger when the inflaton is in a nonthermal vacuum state. As an example, we show that in a truncated $\alpha$-vacuum these loop effects are enhanced by the ratio of the Planck scale to the Hubble scale during inflation. The details of the inflationary models determine whether the coupling constants suppress the loop corrections relative to the tree-level result.