The appearance of a natural dark matter candidate, the neutralino, is among the principal successes of minimal supergravity (mSUGRA) and its descendents. In lieu of a suitable ultraviolet completion, however, theories of gravity-mediated supersymmetry breaking such as mSUGRA suffer from arbitrary degrees of flavor violation. Though theories of gauge-mediated supersymmetry breaking are free from such prohibitive flavor violation, they typically lack natural neutralino dark matter candidates. Yet this conventional dichotomy breaks down when the hidden sector is strongly coupled; in models of gauge-mediated supersymmetry breaking, the neutralino may be the lightest supersymmetric particle if the fields of the hidden sector possess large anomalous dimensions. In fact, general models of so-called “sequestered” gauge mediation possess the full richness of neutralino dark matter found in mSUGRA without corresponding flavor problems. Here we explore generalized models of sequestered gauge mediation and the rich variety of neutralino dark matter they exhibit.

Methods are presented to define and compute source multipoles of dynamical horizons in numerical relativity codes, extending previous work in the isolated and dynamical horizon formalisms to allow for horizons that are not axisymmetric. These methods are then applied to a binary black hole merger simulation, providing evidence that the final remnant is a Kerr black hole, both through the (spatially) gauge-invariant recovery of the geometry of the apparent horizon, and through a detailed extraction of quasinormal ringing modes directly from the strong-field region.

The system of extended objects interacting with a black hole describes or mimics various gravitational phenomena. In this brief paper, we report the results of stability analysis of codimension-one Dirac-Nambu-Goto branes at rest at the equatorial plane of $d$-dimensional spherical black holes, including the Schwarzschild and Schwarzschild-(anti-)de Sitter black holes. For the Schwarzschild and Schwarzschild-anti-de Sitter backgrounds the stability of branes is shown analytically by means of a deformation technique. In contrast, for the Schwarzschild-de Sitter background we demonstrate with the help of numerics that the brane is unstable (only) against the $s$-wave sector of perturbations.

Numerical solutions for the integral curves of the velocity field (streamlines), the density contours, and the accretion rate of a steady-state flow of an ideal fluid with $p=K{n}^{\gamma }$ equation of state are presented. The streamlines and velocity fields associated with a black hole and a rigid sphere in a Reissner-Nordström–(anti) de Sitter spacetime are studied in some detail. For each case the fluid density is studied using contour lines. For $\gamma \ne 2$, we found that the studied properties of the fluid are more sensitive to variations of the electric charge and the cosmological constant. Also, the accretion rate was found to increase or decrease when the cosmological constant increases or decreases, respectively.

We consider the description of cosmological dynamics from the onset of inflation by a perfect fluid whose parameters must be consistent with the strength of the enhanced quantum loop effects that can arise during inflation. The source of these effects must be nonlocal and a simple incarnation of it is studied both analytically and numerically. The resulting evolution stops inflation in a calculable amount of time and leads to an oscillatory universe with a vanishing mean value for the curvature scalar and an oscillation frequency which we compute.

The possible existence of compact stars made of absolutely stable strange quark matter—referred to as strange stars—was pointed out by Witten almost a quarter of a century ago. One of the most amazing features of such objects concerns the possible existence of ultrastrong electric fields on their surfaces, which, for ordinary strange matter, is around ${10}^{18}\mathrm{V}/\mathrm{cm}$. If strange matter forms a color superconductor, as expected for such matter, the strength of the electric field may increase to values that exceed ${10}^{19}\mathrm{V}/\mathrm{cm}$. The energy density associated with such huge electric fields is on the same order of magnitude as the energy density of strange matter itself, which, as shown in this paper, alters the masses and radii of strange quark stars at the 15% and 5% levels, respectively. Such mass increases facilitate the interpretation of massive compact stars, with masses of around $2M_{\odot }$, as strange quark stars.

A grand unified model based on SU(5) and supersymmetry is presented. Pairs of superfields belonging to $\mathbf{15}$ and $\overline{\mathbf{15}}$ representations are newly introduced, two pairs with even and one pair with odd matter parity. Improper mass relations in the minimal model between charged leptons and $d$-type quarks are corrected. Neutrinos have nonvanishing masses, with large angles for generation mixings of the leptons being compatible with the small angles of the quarks. A new source for lepton-number generation in the early universe is provided.

We formulate nonrelativistic quantum chromodynamics (NRQCD) on a lattice which is boosted relative to the usual discretization frame. Moving NRQCD allows us to treat the momentum for the heavy quark arising from the frame choice exactly. We derive moving NRQCD through $\mathcal{O}(1/m^2,v_{\mathrm{rel}}^4)$, as accurate as the NRQCD action in present use, both in the continuum and on the lattice with $\mathcal{O}(a^4)$ improvements. We have carried out extensive tests of the formalism through calculations of two-point correlators for both heavy-heavy (bottomonium) and heavy-light ($B_s$) mesons in $2+1$ flavor lattice QCD and obtained nonperturbative determinations of energy shift and external momentum renormalization. Comparison to perturbation theory at $\mathcal{O}({\alpha }_s)$ is also made. The results demonstrate the effectiveness of moving NRQCD. In particular we show that the decay constants of heavy-light and heavy-heavy mesons can be calculated with small systematic errors up to much larger momenta than with standard NRQCD.

The quark-antiquark potential, and its associated zero point energy, can be extracted from lattice measurements of the Wilson loop. We discuss a unique prescription to renormalize the Wilson loop, for which the perturbative contribution to the zero point energy vanishes identically. A zero point energy can arise nonperturbatively, which we illustrate by considering effective string models. The nonperturbative contribution to the zero point energy vanishes in the Nambu model, but is nonzero when terms for extrinsic curvature are included. At one loop order, the nonperturbative contribution to the zero point energy is negative, regardless of the sign of the extrinsic curvature term.

In a previous paper, we showed that the decay rate of a muon is only slightly affected by the presence of a circularly polarized laser and we gave an analytic expression for the correction. In this paper, we present the analytical result for the case of a linearly polarized laser. Again the effect of the laser is small.

We analyze the influence of nuclear effects on the determination of the nucleon axial mass from nuclear cross sections. Our work is based on a formalism widely applied to describe electron-nucleus scattering data in the impulse approximation regime. The results of numerical calculations show that correlation effects, not taken into account by the relativistic Fermi gas model, sizably affect the $Q^2$ dependence of the cross section. However, their inclusion does not appear to explain the large values of the axial mass recently reported by the K2K and MiniBooNE Collaborations.

We consider how, for quasidegenerate neutrinos with tribimaximal mixing at a high-energy scale, the mixing angles are affected by radiative running from high- to low-energy scales in a supersymmetric theory. The limits on the high-energy scale that follow from consistency with the observed mixing are determined. We construct a model in which a non-Abelian discrete family symmetry leads to both a quasidegenerate neutrino-mass spectrum and to near tribimaximal mixing.

We examine various direct and indirect constraints on the lepton-specific two-Higgs-doublet model and scrutinize the property of the Higgs bosons in the allowed parameter space. We find that in the allowed parameter space the $CP$-odd Higgs boson $A$ is rather light ($m_A<30\mathrm{GeV}$ with 95% possibility), which is composed dominantly by the leptonic Higgs and decays dominantly into ${\tau }^{+}{\tau }^{-}$; while the standard-model-like Higgs boson $h$ (responsible largely for electroweak symmetry breaking) decays dominantly in the mode $h\to AA\to 4\tau$ with a large decay width, which will make the Higgs discovery more difficult at the LHC, whereas this scenario predicts a branching ratio $\mathrm{Br}(Z\to {\tau }^{+}{\tau }^{-}A)$ ranging from ${10}^{-5}$ to ${10}^{-4}$, which may be accessible at the GigaZ option of the International Linear Collider.

We present a search for associated production of the standard model Higgs boson and a $Z$ boson where the $Z$ boson decays to two leptons and the Higgs decays to a pair of $b$ quarks in $p\overline{p}$ collisions at the Fermilab Tevatron. We use event probabilities based on standard model matrix elements to construct a likelihood function of the Higgs content of the data sample. In a CDF data sample corresponding to an integrated luminosity of $2.7{\mathrm{fb}}^{-1}$ we see no evidence of a Higgs boson with a mass between $100\mathrm{GeV}/c^2$ and $150\mathrm{GeV}/c^2$. We set 95% confidence level upper limits on the cross section for $ZH$ production as a function of the Higgs boson mass $m_H$; the limit is 8.2 times the standard model prediction at $m_H=115\mathrm{GeV}/c^2$.

Based on the expectation that the constituent quark model may capture the right physics in the large $N$ limit, we point out that the orbital angular momentum of the quark-antiquark pair inside light mesons of low spins in the constituent quark model may provide a clue for the holographic dual string model of large $N$ QCD. Our discussion, relying on a few suggestive assumptions, leads to a necessity of world-sheet fermions in the bulk of dual strings that can incorporate intrinsic spins of fundamental QCD degrees of freedom. We also comment on the interesting issue of the size of mesons in holographic QCD.

The nonequilibrium dynamics of quantum fields is an initial-value problem, which can be described by Kadanoff-Baym equations. Typically, and, in particular, when numerical solutions are demanded, these Kadanoff-Baym equations are restricted to Gaussian initial states. However, physical initial states are non-Gaussian correlated initial states. In particular, renormalizability requires the initial state to feature $n$-point correlations that asymptotically agree with the vacuum correlations at short distances. In order to identify physical nonequilibrium initial states, it is therefore a precondition to describe the vacuum correlations of the interacting theory within the nonequilibrium framework. In this paper, Kadanoff-Baym equations for non-Gaussian correlated initial states describing vacuum and thermal equilibrium are derived from the 2PI effective action. A diagrammatic method for the explicit construction of vacuum and thermal initial correlations from the 2PI effective action is provided. We present numerical solutions of Kadanoff-Baym equations for a real scalar ${\Phi }^4$ quantum field theory, which take the thermal initial four-point correlation as the leading non-Gaussian correction into account. We find that this minimal non-Gaussian initial condition yields an approximation to the complete equilibrium initial state that is quantitatively and qualitatively significantly improved as compared to Gaussian initial states.

We continue to investigate the separability of massive field equations for spin-0 and spin-$1/2$ charged particles in the general, nonextremal, rotating, charged, Chong-Cvetič-Lü-Pope black holes with two independent angular momenta and a nonzero cosmological constant in minimal $D=5$ gauged supergravity theory. We show that the complex Klein-Gordon equation and the modified Dirac equation with the inclusion of an extra counterterm can be separated by variables into purely radial and purely angular parts in this general Einstein-Maxwell-Chern-Simons background spacetime. A second-order symmetry operator that commutes with the complex Laplacian operator is constructed from the separated solutions and expressed compactly in terms of a rank-2 Stäckel-Killing tensor which admits a simple diagonal form in the chosen pentad one-forms so that it can be understood as the square of a rank-3 totally antisymmetric tensor. A first-order symmetry operator that commutes with the modified Dirac operator is expressed in terms of a rank-3 generalized Killing-Yano tensor and its covariant derivative. The Hodge dual of this generalized Killing-Yano tensor is a generalized principal conformal Killing-Yano tensor of rank-2, which can generate a “tower” of generalized (conformal) Killing-Yano and Stäckel-Killing tensors that are responsible for the whole hidden symmetries of this general, rotating, charged, Kerr–anti-de Sitter black hole geometry. In addition, the first laws of black hole thermodynamics have been generalized to the case that the cosmological constant can be viewed as a thermodynamical variable.

We propose a simple extension of the minimal universal extra dimension model by introducing a small curvature. The model is formulated as a small anti–de Sitter curvature limit of the five-dimensional standard model (SM) in the Randall-Sundrum background geometry. While the lightest Kaluza-Klein (KK) particle can be thermal relic dark matter as usual in the universal extra dimension model, the KK parity is explicitly broken in the presence of the small curvature and the KK dark matter decays into the SM fermions with a long lifetime. Couplings of the KK dark matter with SM fermion pairs in the five-dimensional bulk are controlled by fermion bulk masses. By tuning bulk masses of quarks, we can suppress KK dark matter decay into quarks. With a suitable choice of bulk masses for leptons, KK dark matter decay into leptons can account for the cosmic-ray electron/positron excesses reported by the recent PAMELA and Fermi LAT satellite experiments.

We discuss the potential of the photon-induced two lepton final states at the LHC to explore the phenomenology of the Kaluza-Klein tower of gravitons in the scenarios of the Arkani-Hamed, Dimopoulos, and Dvali model and the Randall-Sundrum model. The sensitivity to model parameters can be improved compared to the present LEP or Tevatron sensitivity.