In this short note, I present a generalization of a set of static $D$-dimensional ($D\ge 3$) Lifshitz black holes, which are solutions of the gravitational model obtained by amending the cosmological Einstein theory with the addition of only the curvature-scalar-squared term and that are described by two parameters, to a more general class of exact, analytic solutions that involves an additional parameter which now renders them stationary. In the special $D=3$ and the dynamical exponent $z=1$ cases, the parameters can be adjusted so that the solution becomes identical to the celebrated BTZ black hole metric.

We reconsider, from a novel perspective, how unitarity constrains the corrections to the ratio of shear viscosity $\eta$ to entropy density $s$. We start with higher-derivative extensions of Einstein gravity in asymptotically anti-de Sitter spacetimes. It is assumed that these theories are derived from string theory and thus have a unitary UV completion that is dual to a unitary, UV-complete boundary gauge theory. We then propose that the gravitational perturbations about a solution of the UV-complete theory are described by an effective theory whose linearized equations of motion have at most two time derivatives. Our proposal leads to a concrete prescription for the calculation of $\eta /s$ for theories of gravity with arbitrary higher-derivative corrections. The resulting ratio can take on values above or below $1/4\pi$ and is consistent with all the previous calculations, even though our reasoning is substantially different. For the purpose of calculating $\eta /s$, our proposal also leads to only two possible candidates for the effective two-derivative theory: Einstein and Gauss-Bonnet gravity. The distinction between the two is that Einstein gravity satisfies the equivalence principle, and so its graviton correlation functions are polarization-independent, whereas the Gauss-Bonnet theory has polarization-dependent correlation functions. We discuss the graviton three-point functions in this context and explain how these can provide additional information on the value of $\eta /s$.

We study vortexlike solutions in a generalized Born-Infeld model. The model is driven by two distinct parameters, one which deals with the Born-Infeld term, and the other, which controls the presence of high-order-power term in the covariant derivative of the Higgs field. We numerically solve the equations of motion and depict the main vortex features for several values of the two parameters of the model. The results indicate the presence of compact vortex, when the parameter responsible for the high-order power in the derivative increases to sufficiently large values.

We study the geometry of the event horizon of a spacetime in which a small compact object plunges into a large Schwarzschild black hole. We first use the Regge-Wheeler and Zerilli formalisms to calculate the metric perturbations induced by this small compact object, then find the new event horizon by propagating null geodesics near the unperturbed horizon. A caustic is shown to exist before the merger. Focusing on the geometry near the caustic, we show that it is determined predominantly by large-$l$ perturbations, which in turn have simple asymptotic forms near the point at which the particle plunges into the horizon. It is therefore possible to obtain an analytic characterization of the geometry that is independent of the details of the plunge. We compute the invariant length of the caustic. We further show that among the leading-order horizon area increase, half arises from generators that enter the horizon through the caustic, and the rest arises from area increase near the caustic, induced by the gravitational field of the compact object.

The similarity of the visible and dark matter abundances indicates that they may originate via the same mechanism. If both the dark and visible matter are charged under a generalized baryon number, then the asymmetry of the visible sector may be compensated by an asymmetry in the dark sector. We show how the separation of the baryonic and the -antibaryonic charge can originate in the vacuum, via the Affleck-Dine mechanism, due to the breaking of a symmetry orthogonal to the baryon number. Symmetry restoration in the current epoch guarantees the individual stability of the two sectors.

We consider a minimal scale-invariant extension of the standard model of particle physics combined with unimodular gravity formulated in [M. Shaposhnikov and D. Zenhausern, Phys. Lett. B 671, 187 (2009).]. This theory is able to describe not only an inflationary stage, related to the standard model Higgs field, but also a late period of dark-energy domination, associated with an almost massless dilaton. A number of parameters can be fixed by inflationary physics, allowing us to make specific predictions for any subsequent period. In particular, we derive a relation between the tilt of the primordial spectrum of scalar fluctuations, $n_s$, and the present value of the equation of state parameter of dark energy (DE), $w_{\mathrm{DE}}^0$. We find bounds for the scalar tilt, $n_s<0.97$, the associated running, $-0.0006<d\ln n_s/d\ln k\lesssim -0.00015$, and for the scalar-to-tensor ratio, $0.0009\lesssim r<0.0033$, which will be critically tested by the results of the Planck mission. For the equation of state of dark energy, the model predicts $w_{\mathrm{DE}}^0>-1$. The relation between $n_s$ and $w_{\mathrm{DE}}^0$ allows us to use the current observational bounds on $n_s$ to further constrain the dark-energy equation of state to $0<1+w_{\mathrm{DE}}^0<0.02$, which is to be confronted with future dark-energy surveys.

We show that the area-angular-momentum inequality $A\ge 8\pi |J|$ holds for axially symmetric closed outermost stably marginally trapped surfaces. These are horizon sections (in particular, apparent horizons) contained in otherwise generic non-necessarily axisymmetric black hole spacetimes, with a non-negative cosmological constant and whose matter content satisfies the dominant energy condition.

Resonant production of a light, narrow techni-rho, followed by the decay ${\rho }_T\to W^{\pm }+{\pi }_T(jj)$ has been proposed as an explanation of the $W+jj$ excess observed by CDF. If the ${\pi }_T$ decays to $\tau +{\nu }_{\tau }/{\tau }^{+}{\tau }^{-}$ rather than to jets, subsequent leptonic $\tau$ decay leads to ${\ell }^{+}{\ell }^{-}\nu \nu \overline{\nu }\overline{\nu }$, a final state that will be picked up by the standard model $W{W}^{(*)}\to {\ell }^{+}{\ell }^{-}+{\mathrm{E̸}}_T$ Higgs searches. We point out that, for the same range of technicolor parameters required to fit the CDF $W+jj$ excess, the correlated ${\ell }^{+}{\ell }^{-}+{\mathrm{E̸}}_T$ technicolor signal can have strength comparable to that of an intermediate-mass standard model Higgs boson, and therefore could be visible at the Tevatron or LHC.

When one splits spacetime into space plus time, the Weyl curvature tensor (vacuum Riemann tensor) gets split into two spatial, symmetric, and trace-free tensors: (i) the Weyl tensor’s so-called electric part or tidal field ${\mathcal{E}}_{jk}$, which raises tides on the Earth’s oceans and drives geodesic deviation (the relative acceleration of two freely falling test particles separated by a spatial vector ${\xi }^k$ is $\Delta a_j=-{\mathcal{E}}_{jk}{\xi }^k$), and (ii) the Weyl tensor’s so-called magnetic part or (as we call it) frame-drag field ${\mathcal{B}}_{jk}$, which drives differential frame dragging (the precessional angular velocity of a gyroscope at the tip of ${\xi }^k$, as measured using a local inertial frame at the tail of ${\xi }^k$, is $\Delta {\Omega }_j={\mathcal{B}}_{jk}{\xi }^k$). Being symmetric and trace-free, ${\mathcal{E}}_{jk}$ and ${\mathcal{B}}_{jk}$ each have three orthogonal eigenvector fields which can be depicted by their integral curves. We call the integral curves of ${\mathcal{E}}_{jk}$’s eigenvectors tidal tendex lines or simply tendex lines, we call each tendex line’s eigenvalue its tendicity, and we give the name tendex to a collection of tendex lines with large tendicity. The analogous quantities for ${\mathcal{B}}_{jk}$ are frame-drag vortex lines or simply vortex lines, their vorticities, and their vortexes. These concepts are powerful tools for visualizing spacetime curvature. We build up physical intuition into them by applying them to a variety of weak-gravity phenomena: a spinning, gravitating point particle, two such particles side-by-side, a plane gravitational wave, a point particle with a dynamical current-quadrupole moment or dynamical mass-quadrupole moment, and a slow-motion binary system made of nonspinning point particles. We show that a rotating current quadrupole has four rotating vortexes that sweep outward and backward like water streams from a rotating sprinkler. As they sweep, the vortexes acquire accompanying tendexes and thereby become outgoing current-quadrupole gravitational waves. We show similarly that a rotating mass quadrupole has four rotating, outward-and-backward sweeping tendexes that acquire accompanying vortexes as they sweep, and become outgoing mass-quadrupole gravitational waves. We show, further, that an oscillating current quadrupole ejects sequences of vortex loops that acquire accompanying tendex loops as they travel, and become current-quadrupole gravitational waves; and similarly for an oscillating mass quadrupole. And we show how a binary’s tendex lines transition, as one moves radially, from those of two static point particles in the deep near zone, to those of a single spherical body in the outer part of the near zone and inner part of the wave zone (where the binary’s mass monopole moment dominates), to those of a rotating quadrupole in the far wave zone (where the quadrupolar gravitational waves dominate). In Paper II we will use these vortex and tendex concepts to gain insight into the quasinormal modes of black holes, and in subsequent papers, by combining these concepts with numerical simulations, we will explore the nonlinear dynamics of curved spacetime around colliding black holes. We have published a brief overview of these applications in R. Owen et al., Phys. Rev. Lett. 106, 151101 (2011). We expect these vortex and tendex concepts to become powerful tools for general relativity research in a variety of topics.

The nonlinear gravitational-wave memory causes a time-varying but nonoscillatory correction to the gravitational-wave polarizations. It arises from gravitational-waves that are sourced by gravitational-waves. Previous considerations of the nonlinear memory effect have focused on quasicircular binaries. Here I consider the nonlinear memory from Newtonian orbits with arbitrary eccentricity. Expressions for the waveform polarizations and spin-weighted spherical-harmonic modes are derived for elliptic, hyperbolic, parabolic, and radial orbits. In the hyperbolic, parabolic, and radial cases the nonlinear memory provides a 2.5 post-Newtonian (PN) correction to the leading-order waveforms. This is in contrast to the elliptical and quasicircular cases, where the nonlinear memory corrects the waveform at leading (0PN) order. This difference in PN order arises from the fact that the memory builds up over a short “scattering” time scale in the hyperbolic case, as opposed to a much longer radiation-reaction time scale in the elliptical case. The nonlinear memory corrections presented here complete our knowledge of the leading-order (Peters-Mathews) waveforms for elliptical orbits. These calculations are also relevant for binaries with quasicircular orbits in the present epoch which had, in the past, large eccentricities. Because the nonlinear memory depends sensitively on the past evolution of a binary, I discuss the effect of this early-time eccentricity on the value of the late-time memory in nearly circularized binaries. I also discuss the observability of large “memory jumps” in a binary’s past that could arise from its formation in a capture process. Lastly, I provide estimates of the signal-to-noise ratio of the linear and nonlinear memories from hyperbolic and parabolic binaries.

We study an inflationary model driven by a single minimally coupled standard kinetic term scalar field with a step in its mass modeled by an Heaviside step function. We present an analytical approximation for the mode function of the curvature perturbation, obtain the power spectrum analytically and compare it with the numerical result. We show that, after the scale set by the step, the spectrum contains damped oscillations that are well described by our analytical approximation. We also compute the dominant contribution to the bispectrum in the equilateral and the squeezed limits and find new shapes. In the equilateral and squeezed limits the bispectrum oscillates and it has a linear growth envelope towards smaller scales. The bispectrum size can be large depending on the model parameters.

We describe a method to couple $Z^{\prime }$ gauge bosons to the standard model (SM), without charging the SM fields under the $U(1{)}^{\prime }$, but instead through effective higher-dimension operators. This method allows complete control over the tree-level couplings of the $Z^{\prime }$ and does not require altering the structure of any of the SM couplings, nor does it contain anomalies or require introduction of fields in nonstandard SM representations. Moreover, such interactions arise from simple renormalizable extensions of the SM—the addition of vectorlike matter that mixes with SM fermions when the $U(1{)}^{\prime }$ is broken. We apply effective $Z^{\prime }$ models as explanations of various recent anomalies: the D0 same-sign dimuon asymmetry, the CDF $W+\mathrm{di}\mathrm{\text{−}}\mathrm{jet}$ excess and the CDF top forward-backward asymmetry. In the case of the $W+\mathrm{di}\mathrm{\text{−}}\mathrm{jet}$ excess we also discuss several complementary analyses that may shed light on the nature of the discrepancy. We consider the possibility of non-Abelian groups, and discuss implications for the phenomenology of dark matter as well.

The resolution of Dyson-Schwinger equations leads to the freezing of the QCD running coupling (effective charge) in the infrared, which is best understood as a dynamical generation of a gluon mass function, giving rise to a momentum dependence which is free from infrared divergences. We calculate the interquark static potential for heavy mesons by assuming that it is given by a massive One Gluon Exchange interaction and compare with phenomenologyical fits inspired by lattice QCD. We apply these potential forms to the description of quarkonia and conclude that, even though some aspects of the confinement mechanism are absent in the Dyson-Schwinger formalism, the spectrum can be reasonably reproduced. We discuss possible explanations for this outcome.

In light of the recent measurements of the top quark forward-backward asymmetry at the Fermilab Tevatron experiment, which in some regions of the parameter space shows a discrepancy of $3\sigma$ compared to the standard model prediction, we analyze top quark pair production and asymmetry in the context of left-right models both at the Tevatron and Large Hadron Collider (LHC). We use the minimal manifest left-right model and an asymmetric left-right model where gauge couplings and flavor mixing in the right-handed sector are allowed to differ from those in the left-handed sector. We explore the consequences of including effects from $W_R$ and $Z_R$ gauge bosons, consistent with phenomenological constraints from meson mixing and new bounds from ATLAS and CMS, for the $t\overline{t}$ cross section, invariant mass distribution and forward-backward asymmetry at the Tevatron, and predict their values at the LHC. We show that, choosing parameter benchmarks for the model while preserving agreement with collider, electroweak precision, and flavor-violation data, the generic left-right model cannot account for the large deviations of the observed asymmetry at the Tevatron and also that it predicts very small charge asymmetries at the LHC.

We show that the double diffractive electroweak vector boson production in the $pp$ collisions at the LHC is an ideal probe of QCD based mechanisms of diffraction. Assuming the resolved Pomeron model with flavor symmetric parton distributions, the $W$ production asymmetry in rapidity equals exactly zero. In other approaches, like the soft color interaction model, in which soft gluon exchanges are responsible for diffraction, the asymmetry is nonzero and equal to that in the inclusive $W$ production. In the same way, the ratio of the $W$ to $Z$ boson production is independent of rapidity in the models with resolved Pomeron in contrast to the predictions of the soft color interaction model.

We construct a string sigma-model with a low-energy limit that describes the anti-de Sitter gravity and spin 3 massless fields in Vasiliev’s framelike formalism. The model is based on vertex operators generating vielbein and connection fields in the MacDowell-Mansouri–Stelle-West formulation of gravity. The structure of the vertex operators is based on the hidden symmetry generators in Ramond-Neveu-Schwarz superstring theory, realizing the isometry group of the anti-de Sitter space. The beta-function equations in the sigma-model lead to equations of motion in the MacDowell-Mansouri–Stelle-West gravity with a negative cosmological constant with the anti-de Sitter geometry being the vacuum solution. Generalizations for the higher spin fields are analyzed and equations of motion for spin 3 fields in $d=3$ in framelike formalism are obtained in the low-energy limit of string theory. These equations correspond to those of $sl(3,R)$ truncated Chern-Simons action based on higher spin algebra $hs(1,1)$.

We present analytical solutions of BPS domain walls in the Einstein-Maxwell flux landscape. We also remove the smeared-branes approximation and write down solutions with localized branes. In these solutions the domain walls induce strong (if not infinite) warping.

The CMS Collaboration has recently conducted a search for trijet resonances in multijet events at the LHC. Motivated in part by this analysis, we examine the phenomenology of exotic particles transforming under higher representations of $SU(3)$ color, focusing on those representations which intrinsically prohibit decays to fewer than three jets. We determine the LHC discovery reach for a particle transforming in a representation of this sort and discuss several additional theoretical and phenomenological constraints which apply to such a particle. Furthermore, we demonstrate that such a particle can provide a consistent explanation for a trijet excess (an invariant-mass peak of roughly 375 GeV) observed in the recent CMS study.

We investigate the Higgs boson production through gluon fusion and its decay into two photons at the LHC in the context of the minimal 3-3-1 model and its alternative version with exotic leptons. The diphoton Higgs decay channel presents an enhanced signal in this model compared to the standard model due to the presence of an extra singly charged vector boson and a doubly charged one. Prospects for the Higgs boson detection at 7 TeV center-of-mass energy with up to $10{\mathrm{fb}}^{-1}$ are presented. Our results suggest that a Higgs boson from these 3-3-1 models can potentially explain the small excess for $m_H\le 145\mathrm{GeV}$ observed at the LHC. Otherwise, if this excess reveals to be only a statistical fluctuation of the standard model backgrounds, severe constraints can be put on these models.

We combine recent progress in measuring the branching ratio of the decay $B\to X_d\gamma$ with the discovery that hadronic uncertainties in the $CP$-averaged branching ratio drop out to a large extent. Implications of these improvements on the size of possible new physics effects are investigated. We find the updated SM prediction for the CP-averaged branching ratio to be $⟨\mathrm{Br}[B\to X_d\gamma {]}_{E_{\gamma }>1.6\mathrm{GeV}}^{\mathrm{SM}}⟩={1.54}_{-0.31}^{+0.26}\times {10}^{-5}$, which should be compared with the experimental value of $⟨\mathrm{Br}[B\to X_d\gamma {]}_{E_{\gamma }>1.6\mathrm{GeV}}^{\exp }⟩=(1.41\pm 0.57)\times {10}^{-5}$. After performing a model independent analysis, we consider different new physics models: the Minimal Supersymmetric Standard Model with generic sources of flavor violation, the two Higgs doublet model of type III, and a model with right-handed charged currents. It is found that the constraints on the supersymmetry parameters ${\delta }_{13}^d$ have improved and that the absolute value of the right-handed quark mixing matrix element $|V_{td}^R|$ must be smaller than $1.5\times {10}^{-4}$.