We propose a new approach to a physical analogy between general relativity and electromagnetism, based on tidal tensors of both theories. Using this approach we write a covariant form for the gravitational analogues of the Maxwell equations, which makes transparent both the similarities and key differences between the two interactions. The following realizations of the analogy are given. The first one matches linearized gravitational tidal tensors to exact electromagnetic tidal tensors in Minkowski spacetime. The second one matches exact magnetic gravitational tidal tensors for ultrastationary metrics to exact magnetic tidal tensors of electromagnetism in curved spaces. In the third we show that our approach leads to a two-step exact derivation of Papapetrou’s equation describing the force exerted on a spinning test particle. Analogous scalar invariants built from tidal tensors of both theories are also discussed.

Considering a massive or massless free spinor field propagating in a flat five-dimensional space with its fifth dimension compactified either on a strip or on a circle, we analyze the procedure of generation of the four-dimensional Kaluza-Klein spinor mass towers. Requiring the five-dimensional Dirac operator to be symmetric, the set of all the allowed boundary conditions is obtained. In the determination of the boundary conditions and in the Kaluza-Klein reduction equations, the SO(3,1) and parity invariances in the space-time subspace are carefully taken into account. The equations determining the mass towers are written in full generality. A few numerical examples are given.

In a previous paper we studied the collapse of a spherically symmetric dust distribution (marginally bound Lemaitre-Tolman-Bondi) in $d$-dimensional anti–de Sitter spacetime and obtained the condition for the formation of trapped surfaces. Here we extend the analysis by giving the canonical theory for the same and subsequently quantize the system by solving the Wheeler-DeWitt equation. We show that for the case of small dust perturbations around a black hole the wave functionals so obtained describe a flux of dust particles from the region near the horizon with a thermal spectrum at the Hawking temperature and discuss the nontrivial dependence of this temperature on the number of spacetime dimensions and the cosmological constant.

In this article, the stability of a general class of spherically symmetric thin-shell wormholes is studied under perturbations preserving the symmetry. For this purpose, the equation of state at the throat is linearized around the static solutions. The formalism presented here is applied to dilaton wormholes, and it is found that there is a smaller range of possible stable configurations for them than in the case of Reissner-Nordström wormholes with the same charge.

Hartle and Srednicki have suggested that standard quantum theory does not favor our typicality. Here an alternative version is proposed in which typicality is likely, Eventual Quantum Mechanics. This version allows one to calculate normalized probabilities for alternatives obeying what I call the principle of observational discrimination, that each possible complete observation or data set should uniquely distinguish one element from the set of alternatives.

We study non-Gaussianity, the spectral index of primordial scalar fluctuations, and tensor modes in models where fluctuations from the inflaton and the curvaton can both contribute to the present cosmic density fluctuations. Even though simple single-field inflation models generate only tiny non-Gaussianity, if we consider such a mixed scenario, large non-Gaussianity can be produced. Furthermore, we study the inflationary parameters such as the spectral index and the tensor-to-scalar ratio in this kind of models and discuss in what cases models predict the spectral index and tensor modes allowed by the current data while generating large non-Gaussianity, which may have many implications for model-buildings of the inflationary universe.

The current accelerated expansion of our universe could be due to an unknown energy component (dark energy) or a modification of general relativity (modified gravity). In the literature it has been proposed that combining the probes of the cosmic expansion history and growth history can distinguish between dark energy and modified gravity. In this work, without invoking nontrivial dark energy clustering, we show that the possible interaction between dark energy and dark matter could make the interacting dark model and the modified gravity model indistinguishable. An explicit example is also given. Therefore, it is required to seek some complementary probes beyond the ones of cosmic expansion history and growth history.

The high- and low-frequency descriptions of the predecoupling plasma are deduced from the Vlasov-Landau treatment generalized to curved space-times and in the presence of the relativistic fluctuations of the geometry. It is demonstrated that the interplay between one-fluid and two-fluid treatments is mandatory for a complete and reliable calculation of the polarization observables. The Einstein-Boltzmann hierarchy is generalized to handle the dispersive propagation of the electromagnetic disturbances in the predecoupling plasma. Given the improved physical and numerical framework, the polarization observables are computed within the magnetized $\Lambda \mathrm{CDM}$ paradigm ($\mathrm{m}\Lambda \mathrm{CDM}$). In particular, the Faraday-induced B-mode is consistently estimated by taking into account the effects of the magnetic fields on the initial conditions of the Boltzmann hierarchy, on the dynamical equations, and on the dispersion relations. The complete calculations of the angular power spectra constitute the first step for the derivation of magnetized maps of the CMB temperature and polarization which are here obtained for the first time and within the minimal $\mathrm{m}\Lambda \mathrm{CDM}$ model. The obtained results set the ground for direct experimental scrutiny of large-scale magnetism via the low- and high-frequency instruments of the Planck explorer satellite.

Fermions moving in a two-dimensional honeycomb lattice (graphene) have, at low energies, chiral symmetry. Generalizing this construction to four dimensions potentially provides fermions with chiral symmetry and only the minimal fermion doubling demanded by the Nielsen-Ninomiya no-go theorem. The practical usefulness of such fermions hinges on whether the action has a necessary set of discrete symmetries of the lattice. If this is the case, one avoids the generation of dimension three operators which require fine-tuning. We construct hyperdiamond lattice actions with enough symmetries to exclude such fine-tuning; however, they produce multiple doublings. Constraining the actions to exhibit minimal doubling breaks the requisite symmetry.

Prospects to search for a new massless neutral gauge boson, the paraphoton, in $e^{+}{e}^{-}$ collisions at center-of-mass energies of 0.5 and 1 TeV are studied. The paraphoton naturally appears in models with Abelian kinetic mixing. A possible realistic model-independent lowest order effective Lagrangian contains magnetic interactions of the paraphoton with the standard model fermion fields. These interactions are proportional to the fermion mass and grow with energy, with however very weak paraphoton couplings to ordinary matter. At the ILC, a potentially interesting process to search for the paraphoton is its radiation from top quarks, so that the event topology of interest is a pair of acoplanar top quarks decaying to jets and missing energy. By combining many discriminating features of signal and background events, efficient paraphoton event selection is achieved, allowing us to set limits for the top-paraphoton coupling. Arguments in favor of the missing energy as the paraphoton with spin 1 are discussed.

We show that the decay mode $B\to D\tau {\nu }_{\tau }$ is competitive with and complementary to $B\to \tau {\nu }_{\tau }$ in the search for charged-Higgs effects. Updating the relevant form factors, we find that the differential distribution in the decay chain $\overline{B}\to D{\overline{\nu }}_{\tau }{\tau }^{-}[\to {\pi }^{-}{\nu }_{\tau }]$ excellently discriminates between standard model and charged-Higgs contributions. By measuring the $D$ and ${\pi }^{-}$ energies and the angle between the $D$ and ${\pi }^{-}$ three-momenta, one can determine the effective charged-Higgs coupling including a possible $CP$-violating phase.

A simple supersymmetric SO(10) grand unified theory (GUT) in five dimensions is considered. The fifth dimension is compactified on the $S^1/(Z_2\times Z_2^{\prime })$ orbifold possessing two inequivalent fixed points. In our setup, all matter and Higgs multiplets reside on one brane (PS brane) where the original SO(10) gauge group is broken down to the Pati-Salam (PS) gauge group, $\mathrm{SU}(4{)}_c\times \mathrm{SU}(2{)}_L\times \mathrm{SU}(2{)}_R$, by the orbifold boundary condition, while only the SO(10) gauge multiplet resides in the bulk. The further breaking of the PS symmetry to the standard model gauge group is realized by Higgs multiplets on the PS brane as usual in four-dimensional models. Proton decay is fully suppressed. In our simple setup, the gauge coupling unification is realized after incorporating threshold corrections of Kaluza-Klein modes. When supersymmetry is assumed to be broken on the other brane, supersymmetry breaking is transmitted to the PS brane through the gaugino mediation with the bulk gauge multiplet.

The QCD sum rule approach is employed in order to study chiral properties of positive- and negative-parity nucleon resonances. It is pointed out that nucleons with an “exotic” chiral property, which can be represented by local five-quark operators, can be paired with a standard nucleon forming a single chiral multiplet. The sum rules of the five-quark operators, however, are shown not to couple strongly to chirally exotic nucleon resonances at the mass region of less than 2 GeV.

A comprehensive study is made for the magnetic moments of octet baryons in the method of QCD sum rules. A complete set of QCD sum rules is derived using the external-field method and generalized interpolating fields. For each member, three sum rules are constructed from three independent tensor structures. They are analyzed in conjunction with the corresponding mass sum rules. The performance of each of the sum rules is examined using the criteria of operator product expansion convergence and ground-state dominance, along with the role of the transitions in intermediate states. Individual contributions from the $u$, $d$, and $s$ quarks are isolated and their implications in the underlying dynamics are explored. Valid sum rules are identified and their predictions are obtained. The results are compared with experiment and previous calculations.

Data collected in run II of the Fermilab Tevatron are searched for indications of new electroweak scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with respect to the standard model prediction. A model-independent approach (Vista) considers the gross features of the data and is sensitive to new large cross section physics. A quasi-model-independent approach (Sleuth) searches for a significant excess of events with large summed transverse momentum and is particularly sensitive to new electroweak scale physics that appears predominantly in one final state. This global search for new physics in over 300 exclusive final states in $927{\mathrm{pb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ reveals no such significant indication of physics beyond the standard model.

We report determination of branching fractions for the decays $\psi (2S)\to h+J/\psi$, where $h=\mathrm{any}$, ${\pi }^{+}{\pi }^{-}$, ${\pi }^0{\pi }^0$, $\eta$, ${\pi }^0$, and $\gamma \gamma$ through ${\chi }_{c0,1,2}$. These measurements use 27M $\psi (2S)$ decays produced in $e^{+}{e}^{-}$ collision data collected with the CLEO detector. The resulting branching fractions and ratios thereof improve upon previously achieved precision in all cases, and in combination with other measurements permit determination of $\mathcal{B}({\chi }_{cJ}\to \gamma J/\psi )$ and $\mathcal{B}(\psi (2S)\to \mathrm{\text{light hadrons}})$.

Yukawa theory at vanishing temperature provides (one of the ingredients for) an effective description of the thermodynamics of a variety of cold and dense fermionic systems. We study the role of masses and the renormalization group flow in the calculation of the equation of state up to two loops within the $\overline{\mathrm{MS}}$ scheme. Two-loop integrals are computed analytically for arbitrary fermion and scalar masses, and expressed in terms of well-known special functions. The dependence of the renormalization group flow on the number of fermion flavors is also discussed.

We study a new class of scenarios with the gaugino mass unification at the weak scale. The unification conditions are generally classified and then, the mirage gauge mediation is explored where the low-energy mass spectrum is governed by a mirage of unified gauge coupling which is seen by low-energy observers. The gaugino masses have natural and stable low-scale unification. The mass parameters of scalar quarks and leptons are given by gauge couplings but exhibit no large mass hierarchy. They are nonuniversal even when mediated at the gauge coupling unification scale. In addition, the gravitino is rather heavy and not the lightest superparticle. These facts are in contrast to existing gauge and mirage mediation models. We also present several explicit models for dynamically realizing the TeV-scale unification.

In a recent paper [L. Boyle, M. Kesden, and S. Nissanke, Phys. Rev. Lett. 100, 151101 (2008)], we introduced a spin expansion that provides a simple yet powerful way to understand aspects of binary black hole merger. This approach relies on the symmetry properties of initial and final quantities like the black hole mass $m$, kick velocity $\mathbf{k}$, and spin vector $\mathbf{s}$, rather than a detailed understanding of the merger dynamics. In this paper, we expand on this proposal, examine how well its predictions agree with current simulations, and discuss several future directions that would make it an even more valuable tool. The spin expansion yields many new predictions, including several exact results that may be useful for testing numerical codes. Some of these predictions have already been confirmed, while others await future simulations. We explain how a relatively small number of simulations—10 equal-mass simulations, and 16 unequal-mass simulations—may be used to calibrate all of the coefficients in the spin expansion up to second order at the minimum computational cost. For a more general set of simulations of given covariance, we derive the minimum-variance unbiased estimators for the spin-expansion coefficients. We discuss how this calibration would be interesting and fruitful for general relativity and astrophysics. Finally, we sketch the extension to eccentric orbits.