We carry out a comprehensive analysis of models for top $A_{\mathrm{FB}}$ at CDF in light of new top data arriving from the LHC. We begin with a careful Tevatron analysis, considering in general which sets of effective vertices give rise to a large forward-backward asymmetry while suppressing the contribution to the total $t\overline{t}$ cross-section. We show on general grounds that scalar models struggle to produce sufficient asymmetries consistent with CDF observations, while vector models can produce a large asymmetry with a less significant tension in the total cross-section and $t\overline{t}$ invariant mass distribution at the Tevatron. We examine the essential observables of these models for top physics at LHC7 with $1{\mathrm{fb}}^{-1}$ of data, including the total cross-section, invariant mass distribution and number of additional jets in $t\overline{t}$ events. In the case of $t$-channel mediators, the LHC total cross-section places a strong constraint on light mediators, while the Tevatron invariant mass distributions place strong constraints on heavy mediators that are able to produce the asymmetry. In particular, single mediator production at the LHC can contribute significantly to $t\overline{t}+\mathrm{\text{jets}}$ events and lead to a significant increase in the $t\overline{t}$ cross-section, as well as in the ratio of top pair events with extra jets to events with no extra jets. Heavy axigluons are becoming increasingly squeezed by LHC7 $t\overline{t}$ and dijet resonance searches. We conclude that LHC7 top analyses are rapidly closing the window for viable models of the CDF top $A_{\mathrm{FB}}$.

It has been realized for a long time that knowing the $\eta$ and ${\eta }^{\prime }$ wave functions in terms of quark and gluon components probes our understanding of nonperturbative QCD dynamics. Great effort has been given to this challenge, yet no clear picture has emerged even with the most recent KLOE data. We point out which measurements would be most helpful in arriving at a more definite conclusion. A better knowledge of these wave functions will significantly help to disentangle the weight of different decay subprocesses in semileptonic decays of $D^{+}$, $D_s^{+}$, and $B^{+}$ mesons. The resulting insights will be instrumental in treating even nonleptonic $B$ transitions involving $\eta$ and ${\eta }^{\prime }$ and their $CP$ asymmetries; thus they can sharpen the case for or against new physics intervening there.

We reanalyze the $W$-boson loop in the amplitude of the Higgs boson decay into two photons to show the absence of decoupling in the limit of massless $W$ bosons, $m_W\to 0$. The Higgs coupling to longitudinal polarizations survives in this limit and generates a nonvanishing contribution in the $H\to \gamma \gamma$ decay. This shows that the recent claim of decoupling by R. Gastmans, S. L. Wu, and T. T. Wu is incorrect, and the old calculations for the two-photon decay well known in the literature are valid.

We present a measurement of the relative branching fraction, $R_{f_0/\varphi }$, of $B_s^0\to J/\psi f_0(980)$, with $f_0(980)\to {\pi }^{+}{\pi }^{-}$, to the process $B_s^0\to J/\psi \varphi$, with $\varphi \to K^{+}{K}^{-}$. The $J/\psi f_0(980)$ final state corresponds to a $CP$-odd eigenstate of $B_s^0$ that could be of interest in future studies of $CP$ violation. Using $8{\mathrm{fb}}^{-1}$ of data recorded with the D0 detector at the Fermilab Tevatron Collider, we find $R_{f_0/\varphi }=0.275\pm 0.041(\mathrm{stat})\pm 0.061(\mathrm{syst})$.

We evaluate the partition function of three-dimensional theories of gravity in the quantum regime, where the anti–de Sitter (AdS) radius is Planck scale and the central charge is of order one. The contribution from the AdS vacuum sector can—with certain assumptions—be computed and equals the vacuum character of a minimal model conformal field theory. The torus partition function is given by a sum over geometries which is finite and computable. For generic values of Newton’s constant $G$ and the AdS radius $\ell$, the result has no Hilbert space interpretation, but in certain cases it agrees with the partition function of a known conformal field theory. For example, the partition function of pure Einstein gravity with $G=3\ell$ equals that of the Ising model, providing evidence that these theories are dual. We also present somewhat weaker evidence that the three-state and tricritical Potts models are dual to pure higher spin theories of gravity based on $SL(3)$ and $E_6$, respectively.

The bulk matter Randall-Sundrum (RS) model is a setup where standard model (SM) matter and gauge fields reside in the bulk of 5D warped spacetime while the Higgs field is confined on the IR brane. The wave functions of the 1st and 2nd generation matter particles are localized toward the UV brane and those of the 3rd generation toward the IR brane, so that the hierarchical structure of the Yukawa couplings arises geometrically without hierarchy in fundamental parameters. This paper discusses observing signals of this model in the case where the Kaluza-Klein scale is far above the collider scale, but the model is combined with the 5D minimal supersymmetric standard model (MSSM) and supersymmetric (SUSY) particles are in the reach of collider experiments. A general SUSY breaking mass spectrum consistent with the bulk matter RS model is considered: a SUSY breaking sector locates on the IR brane and its effects are mediated to 5D MSSM through a hybrid of gravity mediation, gaugino mediation, and gauge mediation. This paper argues that it is possible to observe the signals of the bulk matter RS model through rare decays of “almost SU(2) singlet mass eigenstates” that are induced by flavor-violating gravity mediation contributions to matter soft SUSY breaking terms.

We analyze the construction of conformal theories of gravity in the realm of teleparallel theories. We first present a family of conformal theories which are quadratic in the torsion tensor and are constructed out of the tetrad field and of a scalar field. For a particular value of a coupling constant, and in the gauge where the scalar field is restricted to assume a constant value, the theory reduces to the teleparallel equivalent of general relativity, and the tetrad field satisfies Einstein’s equations. A second family of theories is formulated out of the tetrad field only, and the theories are not equivalent to the usual Weyl Lagrangian. Therefore, the latter is not the unique genuinely geometrical construction that yields a conformally invariant action. The teleparallel framework allows more possibilities for conformal theories of gravity.

We develop a holographic model for thermalization following a quench near a quantum critical point with nontrivial dynamical critical exponent. The anti-de Sitter Vaidya null collapse geometry is generalized to asymptotically Lifshitz spacetime. Nonlocal observables such as two-point functions and entanglement entropy in this background then provide information about the length and time scales relevant to thermalization. The propagation of thermalization exhibits similar “horizon” behavior as has been seen previously in the conformal case and we give a heuristic argument for why it also appears here. Finally, analytic upper bounds are obtained for the thermalization rates of the nonlocal observables.

A cold relic axion condensate resulting from vacuum misalignment in the early Universe oscillates with a frequency $m$, where $m$ is the axion mass. We determine the properties of photons propagating in a simplified version of such a background where the sinusoidal variation is replaced by a square wave profile. We prove that previous results, which indicated that charged particles moving fast in such a background radiate (originally derived assuming that all momenta involved were much larger than $m$), hold for long wavelengths, too. We also analyze in detail how the introduction of a magnetic field changes the properties of photon propagation in such a medium. We briefly comment on possible astrophysical implications of these results.

A three-dimensional harmonic oscillator with spin noncommutativity in the phase space is considered. The system has a regular symplectic structure and by using supersymmetric quantum mechanics techniques, the ground state is calculated exactly. We find that this state is infinitely degenerate and it has explicit spontaneous broken symmetry. Analyzing the Heisenberg equations, we show that the total angular momentum is conserved.

Recently, the topic of Casimir repulsion has received a great deal of attention, largely because of the possibility of technological application. The general subject has a long history, going back to the self-repulsion of a conducting spherical shell and the repulsion between a perfect electric conductor and a perfect magnetic conductor. Recently, it has been observed that repulsion can be achieved between ordinary conducting bodies, provided sufficient anisotropy is present. For example, an anisotropic polarizable atom can be repelled near an aperture in a conducting plate. Here, we provide new examples of this effect, including the repulsion on such an atom moving on a trajectory nonintersecting a conducting cylinder; in contrast, such repulsion does not occur outside a sphere. Classically, repulsion does occur between a conducting ellipsoid placed in a uniform electric field and an electric dipole. The Casimir-Polder force between an anisotropic atom and an anisotropic dielectric semispace does not exhibit repulsion. The general systematics of repulsion are becoming clear.

We analyze a recent conjecture regarding the perturbative construction of nonlinear deformations of all classically duality-invariant theories, including $\mathcal{N}=8$ supergravity. Starting with an initial quartic deformation, we engineer a procedure that generates a particular nonlinear deformation (Born-Infeld) of the Maxwell theory. This procedure requires the introduction of an infinite number of modifications to a constraint which eliminates degrees of freedom consistent with the duality and field content of the system. We discuss the extension of this procedure to $\mathcal{N}=1$ and $\mathcal{N}=2$ supersymmetric theories, and comment on its potential to either construct new supergravity theories with nonlinear Born-Infeld type duality, or to constrain the finiteness of $\mathcal{N}=8$ supergravity.

We examine the structure of the event horizon for numerical simulations of two black holes that begin in a quasicircular orbit, inspiral, and finally merge. We find that the spatial cross section of the merged event horizon has spherical topology (to the limit of our resolution), despite the expectation that generic binary black hole mergers in the absence of symmetries should result in an event horizon that briefly has a toroidal cross section. Using insight gained from our numerical simulations, we investigate how the choice of time slicing affects both the spatial cross section of the event horizon and the locus of points at which generators of the event horizon cross. To ensure the robustness of our conclusions, our results are checked at multiple numerical resolutions. Three-dimensional visualization data for these resolutions are available for public access online. We find that the structure of the horizon generators in our simulations is consistent with expectations, and the lack of toroidal horizons in our simulations is due to our choice of time slicing.

Are giant flares or storms in soft-gamma repeaters viable sources of gravitational radiation? Few theoretical studies have been concerned with this problem, with the small number using either highly idealized models or assuming a magnetic field orders of magnitude beyond what is supported by observations. We perform nonlinear general-relativistic magnetohydrodynamic simulations of large-scale hydromagnetic instabilities in magnetar models, which mimic the magnetic field reconfiguration expected in magnetar flares. We utilize these models to find gravitational-wave emission over a wide range of energies, from ${10}^{40}$ to ${10}^{47}\mathrm{erg}$. This allows us to derive a systematic relationship between the surface field strength and the gravitational-wave strain. In particular, for typical magnetar fields of a few times ${10}^{15}\mathrm{G}$, we conclude that a direct observation of $f$-modes excited by global magnetic field reconfigurations is unlikely with present or near-future gravitational-wave observatories, though we also discuss the possibility that modes in a low-frequency band up to 100 Hz could be sufficiently excited to be relevant for observation.

We study the possibility of obtaining unbound energy $E_{c.m.}$ in the center-of-mass frame when two particles collide near the inner black hole horizon. We consider two different cases—when both particles move (i) in the same direction or (ii) in the opposite ones. We also discuss two different versions of the effect—whether an infinite energy can be released in the collision (strong version) or the energy $E_{c.m.}$ is finite but can be made as large as one likes (weak version). We demonstrate that the strong version of the effect is impossible in both cases (i) and (ii). In case (i) this is due to the fact that in the situation when $E_{c.m.}$ formally diverges on the horizon, one of particles passes through the bifurcation point where two horizons meet while the second particle does not, so collision does not occur. In case (ii), both particles hit different branches of the horizon. The weak version is possible in both cases, provided at least one of particles starts its motion inside the horizon along the direction of spatial symmetry from infinity.

We study four-dimensional quantum gravity formulated as a certain conformal field theory at the ultraviolet fixed point, whose dynamics is described by the combined system of Riegert-Wess-Zumino and Weyl actions. Background-free nature comes out as quantum diffeomorphism symmetry by quantizing the conformal factor of the metric field nonperturbatively. In this paper, Minkowski background $M^4$ is employed in practice. The generator of quantum diffeomorphism that forms conformal algebra is constructed. Using it, we study the composite scalar operator that becomes a good conformal field. We find that physical fields are described by such scalar fields with conformal dimension 4. Consequently, tensor fields outside the unitarity bound are excluded. Computations of quantum algebra on $M^4$ are carried out in the coordinate space using operator products of the fields. The nilpotent Becchi-Rouet-Stora-Tyupin operator is also constructed.

The detection of the type and level of primordial non-Gaussianity in the CMB data is essential to probe the physics of the early universe. Since one does not expect that a single statistical estimator can be sensitive to all possible forms of non-Gaussianity which may be present in the data, it is important to employ different statistical indicators to study non-Gaussianity of CMB. In recent works we have proposed two new large-angle non-Gaussianity indicators based on skewness and kurtosis of patches of CMB sky sphere, and used them to find significant deviations from Gaussianity in frequency bands and foreground-reduced CMB maps. Simulated CMB maps with assigned type and amplitude of primordial non-Gaussianity are important tools to determine the strength, sensitivity, and limitations of non-Gaussian estimators. Here we investigate whether and to what extent our non-Gaussian indicators have sensitivity to detect non-Gaussianity of local type, particularly with an amplitude within the 7 yr Wilkinson Microwave Anisotropy Probe (WMAP) bounds. We make a systematic study by employing our statistical tools to generate maps of skewness and kurtosis from several thousands of simulated maps equipped with non-Gaussianity of local type of various amplitudes. We show that our indicators can be used to detect large-angle local-type non-Gaussianity only for relatively large values of the nonlinear parameter $f_{\mathrm{NL}}^{\mathrm{local}}$. Thus, our indicators do not have enough sensitivity to detect deviation from Gaussianity with the nonlinear parameter within the 7 yr WMAP bounds. This result, along with the outcomes of frequency bands and foreground-reduced analyses, suggests that non-Gaussianity captured in the previous works by our indicators is not of primordial origin, although it might have a primordial component. We have also made a comparative study of non-Gaussianity of simulated maps and of the full-sky WMAP 7 yr foreground-reduced internal linear combination (ILC)-7 yr map. An outcome of this analysis is that the level of non-Gaussianity of the ILC-7 yr map is higher than that of the simulated maps for $f_{\mathrm{NL}}^{\mathrm{local}}$ within WMAP bounds. This provides quantitative indications on the suitability of the ILC-7 yr map as Gaussian reconstruction of the full-sky CMB.

We calculate the shape correlations between trispectra in various equilateral non-Gaussian models, including Dirac-Born-Infeld inflation, ghost inflation and Lifshitz scalars, using the full trispectrum as well as the reduced trispectrum. We find that most theoretical models are distinguishable from the shapes of primordial trispectra except for several exceptions where it is difficult to discriminate between the models, such as single field Dirac-Born-Infeld inflation and a Lifshitz scalar model. We introduce an estimator for the amplitude of the trispectrum, $g_{\mathrm{NL}}^{\mathrm{equil}}$ and relate it to model parameters in various models. Using constraints on $g_{\mathrm{NL}}^{\mathrm{equil}}$ from WMAP5, we give constraints on the model parameters.

We study nonperturbative quantization of the first order formulation of three-dimensional gravity with positive cosmological constant (de Sitter space being the prototype vacuum solution, whose Euclideanization gives the three sphere) on the background topology of lens space, which is a three sphere modulo a discrete group. Instead of the strategy followed by a recent work [A. Castro, N. Lashkari, and A. Maloney, Phys. Rev. D 83, 124027 (2011); A. Castro, N. Lashkari, and A. Maloney Phys. Rev. D 84, 089904(E) (2011)], which compares results in the second and first order formulations of gravity, we concentrate solely on the latter . We note, as a striking feature, that the quantization which relies heavily on the axiomatic of topological quantum field theory, can only be consistently carried by augmenting the conventional theory by an additional topological term coupled through a dimensionless parameter. More importantly the introduction of this additional parameter renders the theory finite.