The anomalous forward-backward asymmetry ($A_{\mathrm{FB}}$) in $t\overline{t}$ production at the Tevatron is in apparent contradiction with the $t\overline{t}$ charge asymmetry ($A_{\mathrm{C}}$) measurements at the LHC, which agree well with the standard model predictions. We argue that associated production of a state with $[u\overline{t}]$ flavor quantum numbers can lead to a sizable negative contribution to $A_{\mathrm{C}}$. Exchange of such a resonance in the $t$ channel would lead to positive contributions to $A_{\mathrm{FB}}$ and $A_{\mathrm{C}}$, as has been extensively discussed in the literature. Given the additional negative $A_{\mathrm{C}}$ contribution, both the Tevatron and LHC data can be naturally accommodated within this framework. A simple realization of this setup is the well known example of a $Z^{\prime }$ with flavor off-diagonal up-top couplings. We provide a detailed study of this model, demonstrating that it indeed reproduces the $t\overline{t}$ asymmetry data, and is compatible with other constraints, e.g., $t+\mathrm{\text{jet}}$ resonance searches, $t\overline{t}$ inclusive jet multiplicities, and atomic parity violation.

By introducing the contribution from dynamically generated gluon mass, we present a brand new parametrized form of QCD beta function to get an inferred limited running behavior of QCD coupling constant ${\alpha }_s$. This parametrized form is regarded as an essential factor to determine the scale dependencies of the proton spin constituents at the very low scale. In order to compare with experimental results directly, we work within the gauge-invariant framework to decompose the proton spin. Utilizing the updated next-to-next-leading-order evolution equations for angular momentum observables within a modified minimal subtraction scheme, we indicate that gluon contribution to proton spin cannot be ignored. Specifically, by assuming asymptotic limits of the total quark/gluon angular momentum valid, respectively, the scale dependencies of quark angular momentum $J^q$ and gluon angular momentum $J^g$ down to $Q^2\sim 1{\mathrm{GeV}}^2$ are presented, which are comparable with the preliminary analysis of deeply virtual Compton scattering experiments by HERMES and JLab. After solving scale dependencies of quark spin $\Delta {\Sigma }^q$, orbital angular momenta of quarks $L^q$ are given by subtraction, presenting a holistic picture of proton spin partition within up and down quarks at a low scale.

We consider a supersymmetric model where the neutrino mass matrix arises from bilinear and trilinear $R$-parity violation, both restricted by a $Z_3$ flavor symmetry. Assuming flavor-blind soft supersymmetry breaking conditions, corrected at low energies due to running effects, we obtain a neutrino mass matrix in agreement with oscillation data. In particular, a large ${\theta }_{13}$ angle can be easily accommodated. We also find a correlation between the reactor and atmospheric mixing angles. This leads in some scenarios to a clear deviation from ${\theta }_{23}=\pi /4$. The lightest supersymmetric particle decay, dominated by the trilinear couplings, provides a direct way to test the model at colliders.

We present measurements of the branching fractions of three-prong and five-prong $\tau$ decay modes using a sample of 430 million $\tau$ lepton pairs, corresponding to an integrated luminosity of $468{\mathrm{fb}}^{-1}$, collected with the BABAR detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ storage rings at SLAC National Accelerator Laboratory. The ${\tau }^{-}\to (3\pi {)}^{-}\eta {\nu }_{\tau }$, ${\tau }^{-}\to (3\pi {)}^{-}\omega {\nu }_{\tau }$, and ${\tau }^{-}\to {\pi }^{-}{f}_1(1285){\nu }_{\tau }$ branching fractions are presented, as well as a new limit on the branching fraction of the second-class current decay ${\tau }^{-}\to {\pi }^{-}{\eta }^{\prime }(958){\nu }_{\tau }$. We search for the decay mode ${\tau }^{-}\to K^{-}{\eta }^{\prime }(958){\nu }_{\tau }$ and for five-prong decay modes with kaons, and place the first upper limits on their branching fractions.

We show that the electromagnetic superconductivity of vacuum in strong magnetic field background is consistent with the Vafa-Witten theorem because the charged vector meson condensates lock relevant internal global symmetries of QCD with the electromagnetic gauge group.

We consider the Yang-Mills instanton equations on the four-dimensional manifold $S^2\times \Sigma$, where $\Sigma$ is a compact Riemann surface of genus $g>1$ or its covering space $H^2=\mathrm{SU}(1,1)/\mathrm{U}(1)$. Introducing a natural ansatz for the gauge potential, we reduce the instanton equations on $S^2\times \Sigma$ to vortex-type equations on the sphere $S^2$. It is shown that when the scalar curvature of the manifold $S^2\times \Sigma$ vanishes, the vortex-type equations are integrable, i.e., can be obtained as compatibility conditions of two linear equations (Lax pair), which are written down explicitly. Thus, the standard methods of integrable systems can be applied for constructing their solutions. However, even if the scalar curvature of $S^2\times \Sigma$ does not vanish, the vortex equations are well defined and have solutions for any values of the topological charge $N$. We show that any solution to the vortex equations on $S^2$ with a fixed topological charge $N$ corresponds to a Yang-Mills instanton on $S^2\times \Sigma$ of charge $(g-1)N$.

We clarify questions related to the convergence of the operator product expansion and conformal block decomposition in unitary conformal field theories (for any number of spacetime dimensions). In particular, we explain why these expansions are convergent in a finite region. We also show that the convergence is exponentially fast, in the sense that the operators of dimension above $\Delta$ contribute to correlation functions at most $\exp (-a\Delta )$. Here the constant $a>0$ depends on the positions of operator insertions and we compute it explicitly.

Based on the truncated Dyson-Schwinger equation for the fermion propagator, the Cornwall-Jackiw-Tomboulis effective potential near the critical point is investigated. We show that, at zero temperature, the system undergoes a continuous phase transition into the chiral symmetric phase at a critical number of fermion flavors, while undergoing a second-order phase transition at high temperature.

According to the black hole/qubit correspondence (BHQC) certain black hole entropy formulas in supergravity can be related to multipartite entanglement measures of quantum information. Here we show that the origin of this correspondence is a connection between Hitchin functionals used as action functionals for form theories of gravity related to topological strings and entanglement measures for systems with a small number of constituents. The basic idea acting as a unifying agent in these seemingly unrelated fields is stability connected to the mathematical notion of special prehomogeneous vector spaces associated to Freudenthal systems coming from simple Jordan algebras. It is shown that the nonlinear function featuring these functionals and defining Calabi-Yau and generalized Calabi-Yau structures is the Freudenthal dual, a concept introduced recently in connection with the BHQC. We propose to use the Hitchin invariant for three-forms in seven dimensions as an entanglement measure playing a basic role in classifying three-fermion systems with seven modes. The representative of the class of maximal tripartite entanglement is the three-form used as a calibration for compactification on manifolds with $G_2$ holonomy. The idea that entanglement measures are related to action functionals from which the usual correspondence of the BHQC follows at the tree level suggests that one can use the BHQC in a more general context.

An interesting feature of the Davies-Unruh effect is that a uniformly accelerated observer sees an isotropic thermal spectrum of particles even though there is a preferred direction in this context, determined by the direction of the acceleration $\mathbf{g}$. We investigate the thermal fluctuations in the Unruh bath by studying the Brownian motion of particles in the bath, especially as regards to isotropy. We find that the thermal fluctuations are anisotropic and induce different frictional drag forces on the Brownian particle depending on whether it has a drift velocity along the direction of acceleration $g$ or in a direction transverse to it. Using the fluctuation-dissipation theorem, we argue that this anisotropy arises due to quantum correlations in the fluctuations at large correlation time scales.

We study the convergence properties of our implementation of the moving punctures approach at very high resolutions for an equal-mass, nonspinning, black-hole binary. We find convergence of the Hamiltonian constraint on the horizons and the $L_2$ norm of the Hamiltonian constraint in the bulk for sixth- and eighth-order finite difference implementations. The momentum constraint is more sensitive, and its $L_2$ norm shows clear convergence for a system with consistent sixth-order finite differencing, while the momentum and Baumgarte-Shapiro-Shibata-Nakamura (BSSN) constraints on the horizons show convergence for both sixth- and eighth-order systems. We analyze the gravitational waveform error from the late inspiral, merger, and ringdown. We find that using several lower-order techniques for increasing the speed of numerical relativity simulations actually lead to apparently nonconvergent errors. Even when using standard high-accuracy techniques, rather than seeing clean convergence, where the waveform phase is a monotonic function of grid resolution, we find that the phase tends to oscillate with resolution, possibly due to stochastic errors induced by grid refinement boundaries. Our results seem to indicate that one can obtain gravitational waveform phases to within 0.05 rad. (and possibly as small as 0.015 rad), while the amplitude error can be reduced to 0.1%. We then compare with the waveforms obtained using the CCZ4 formalism. We find that the CCZ4 waveforms have larger truncation errors for a given resolution, but the Richardson extrapolation phase of the CCZ4 and BSSN waveforms agrees to within 0.01 rad, even during the ringdown.

We present a new numerical code to compute non-axisymmetric eigenmodes of rapidly rotating relativistic stars by adopting spatially conformally flat approximation of general relativity. The approximation suppresses the radiative degree of freedom of relativistic gravity and the field equations are cast into a set of elliptic equations. The code is tested against the low-order $f$ and $p$ modes of slowly rotating stars for which a good agreement is observed in frequencies computed by our new code and those computed by the full theory. Entire sequences of the low order counter-rotating $f$-modes are computed, which are susceptible to an instability driven by gravitational radiation.

We construct exact solutions, which represent regular charged rotating Kaluza-Klein multiblack holes in the five-dimensional pure Einstein-Maxwell theory. Quantization conditions between the mass, the angular momentum, and charges appear from the regularity condition of horizon. We also obtain multiblack string solutions by taking some limits in the solutions. We extend the black hole solutions to the five-dimensional Einstein-Maxwell-Chern-Simons theory with an arbitrary Chern-Simons coupling constant.

The weakly interacting massive particle (WIMP) often serves as a candidate for the cold dark matter. However, when produced nonthermally, it could behave like warm dark matter. In this paper, we study the properties of the $\gamma$-ray emission from annihilation of WIMP dark matter in the halo of our own Milky Way galaxy with high resolution $N$-body simulations of a Milky-Way-like dark matter halo, assuming a different nature of WIMPs. Due to the large free-streaming length in the scenario of warm WIMPs, the substructure content of the dark matter halo is significantly different from that of the cold WIMP counterpart, resulting in distinct predictions of the $\gamma$-ray signals from the dark matter annihilation. We illustrate these by comparing the predicted $\gamma$-ray signals from the warm WIMP annihilation to that of cold WIMPs. Pronounced differences from the subhalo sky map and statistical properties between two WIMP models are demonstrated. Due to the potentially enhanced cross section of the nonthermal production mechanism in the warm WIMP scenario, the Galactic center might be prior to the indirect detection of warm WIMPs to dwarf galaxies, which might be different from the cold dark matter scenario. As a specific example, we consider the nonthermally produced neutralino of the supersymmetric model and discuss the detectability of warm WIMPs with the Fermi $\gamma$-ray telescope.

We propose a cosmological model of a D3-brane universe on a compact and stable supergravity background of wrapped D7-branes in type IIB string theory, previously argued to be dual to pure $\mathcal{N}=1$ $SU(N)$ gauge theory in four dimensions. A model universe of order Planck size near the UV boundary dynamically flows toward the IR with constant total energy density and accelerating expansion, followed by smooth transition to decelerating expansion, and collides with the wrapped D7-branes at the IR boundary. The model addresses the horizon and flatness problems, with most of the expansion produced during the decelerating expansion phase. The inflationary scenario is used to generate sources of inhomogeneities in the cosmic microwave background radiation and seeds for large-scale structure formation from quantum fluctuations which exit the Hubble radius early during the accelerating expansion phase, and the model addresses the inhomogeneity problem with red tilt in the power spectrum. We propose that the kinetic energy of the model universe is converted to matter and radiation by the collision followed by the formation of baryons, stabilizing the model universe against gravitational force from the background at a finite distance from the IR boundary, with the wrapped D7-branes serving as sources of color. Friedmann evolution then takes over, with a positive cosmological constant term coming from the remaining potential energy density, which is interpreted as dark energy. The magnitude of the dark energy density is smaller than the total energy density during the flow by a ratio of the scale factor when the model universe appears in the UV to the scale factor at the moment of collision, and stays constant while the matter-radiation density falls during Friedmann expansion.

A Chern-Simons coupling of a new scalar field to electromagnetism may give rise to cosmological birefringence, a rotation of the linear polarization of electromagnetic waves as they propagate over cosmological distances. Prior work has sought this rotation, assuming the rotation angle to be uniform across the sky, by looking for the parity-violating $TB$ and $EB$ correlations that a uniform rotation produces in the cosmic microwave background temperature/polarization. However, if the scalar field that gives rise to cosmological birefringence has spatial fluctuations, then the rotation angle may vary across the sky. Here we search for direction-dependent cosmological birefringence in the WMAP-7 data. We report the first cosmic microwave background constraint on the rotation-angle power spectrum $C_L^{\alpha \alpha }$ for multipoles between $L=0$ and $L=512$. We also obtain a 68% confidence-level upper limit of $\sqrt{C_2^{\alpha \alpha }/(4\pi )}\lesssim 1°$ on the quadrupole of a scale-invariant rotation-angle power spectrum.

We present a specific prescription for the calculation of cosmological power spectra, exploited here at two-loop order in perturbation theory, based on the multipoint propagator expansion. In this approach, density and velocity power spectra are constructed from the regularized expressions of the propagators that reproduce both the resummed behavior in the high-$k$ limit and the standard perturbation theory results at low $k$. With the help of $N$-body simulations, we particularly focus on the density field, and show that such a construction gives robust and accurate predictions for both the density power spectrum and the correlation function at percent level in the weakly nonlinear regime. We then present an algorithm that allows accelerated evaluations of all the required diagrams by reducing the computational tasks to one-dimensional integrals. This is achieved by means of precomputed kernel sets defined for appropriately chosen fiducial models. The computational time for two-loop results is then reduced from a few minutes, with the direct method, to a few seconds with the fast one. The robustness and applicability of this method are tested against the power spectrum cosmic emulator from which a wide variety of cosmological models can be explored. The Fortran program with which direct and fast calculations of density power spectra can be done, RegPT, is publicly released as part of this paper.

According to cosmological inflation, the inhomogeneities in our Universe are of quantum-mechanical origin. This scenario is phenomenologically very appealing as it solves the puzzles of the standard hot big bang model and naturally explains why the spectrum of cosmological perturbations is almost scale invariant. It is also an ideal playground to discuss deep questions among which is the quantum measurement problem in a cosmological context. Although the large squeezing of the quantum state of the perturbations and the phenomenon of decoherence explain many aspects of the quantum-to-classical transition, it remains to understand how a specific outcome can be produced in the early Universe, in the absence of any observer. The continuous spontaneous localization (CSL) approach to quantum mechanics attempts to solve the quantum measurement question in a general context. In this framework, the wave function collapse is caused by adding new nonlinear and stochastic terms to the Schrödinger equation. In this paper, we apply this theory to inflation, which amounts to solving the CSL parametric oscillator case. We choose the wave function collapse to occur on an eigenstate of the Mukhanov-Sasaki variable and discuss the corresponding modified Schrödinger equation. Then, we compute the power spectrum of the perturbations and show that it acquires a universal shape with two branches, one which remains scale invariant and one with $n_{\mathrm{S}}=4$, a spectral index in obvious contradiction with the cosmic microwave background anisotropy observations. The requirement that the non-scale-invariant part be outside the observational window puts stringent constraints on the parameter controlling the deviations from ordinary quantum mechanics. Due to the absence of a CSL amplification mechanism in field theory, this also has the consequence that the collapse mechanism of the inflationary fluctuations is not efficient. Then, we determine the collapse time. On small scales the collapse is almost instantaneous, and we recover exactly the behavior of the CSL harmonic oscillator (a case for which we present new results), whereas, on large scales, we find that the collapse is delayed and can take several e-folds to happen. We conclude that recovering the observational successes of inflation and, at the same time, reaching a satisfactory resolution of the inflationary “macro-objectification” issue seems problematic in the framework considered here. This work also provides a complete solution to the CSL parametric oscillator system, a topic we suggest could play a very important role to further constrain the CSL parameters. Our results illustrate the remarkable power of inflation and cosmology to constrain new physics.

In this paper, we study non-Gaussianity generated by a single scalar field in slow-roll inflation in the framework of the nonrelativistic general covariant Hořava-Lifshitz theory of gravity with the projectability condition and an arbitrary coupling constant $\lambda$, where $\lambda$ characterizes the deviation of the theory from general relativity (GR) in the infrared. We find that the leading effect of self-interaction, contrary to the case of the minimal scenario of GR, is in general of the order ${\widehat{\alpha }}_n{ϵ}^{3/2}$, where $ϵ$ is a slow-roll parameter, and ${\widehat{\alpha }}_n(n=3,5)$ are the dimensionless coupling coefficients of the sixth-order operators of the Lifshitz scalar and have no contributions to power spectra and indices of both scalar and tensor. The bispectrum, comparing with the standard one given in GR, is enhanced and gives rise to a large value of the nonlinearity parameter $f_{\mathrm{NL}}$. We study how the modified dispersion relation with high order moment terms affects the evaluation of the mode function and in turn the bispectrum, and we show explicitly that the mode function takes various asymptotic forms during different periods of its evolution. In particular, we find that it is in general of superpositions of oscillatory functions, instead of plane waves like in the minimal scenario of GR. This results in a large enhancement of the folded shape in the bispectrum.

We study in a systematic way a generic nonderivative (massive) deformation of general relativity using the Hamiltonian formalism. The number of propagating degrees of freedom is analyzed in a nonperturbative and background independent way. We show that the condition of having only five propagating degrees of freedom can be cast in a set of differential equations for the deforming potential. Though the conditions are rather restrictive, many solutions can be found.