In anomaly-mediated supersymmetry breaking models, superpartner masses are proportional to couplings squared. Their hidden sectors therefore naturally contain WIMPless dark matter, particles whose thermal relic abundance is guaranteed to be of the correct size, even though they are not weakly interacting massive particles. We study viable dark matter candidates in WIMPless anomaly-mediated supersymmetry breaking models with non-Abelian hidden sectors and highlight unusual possibilities that emerge in even the simplest models. In one example with a pure $SU(N)$ hidden sector, stable hidden gluinos freeze out with the correct relic density, but have an extremely low, but natural, confinement scale, providing a framework for self-interacting dark matter. In another simple scenario, hidden gluinos freeze out and decay to visible Winos with the correct relic density, and hidden glueballs may either be stable, providing a natural framework for mixed cold-hot dark matter, or may decay, yielding astrophysical signals. Last, we present a model with light hidden pions that may be tested with improved constraints on the number of nonrelativistic degrees of freedom. All of these scenarios are defined by a small number of parameters, are consistent with gauge coupling unification, preserve the beautiful connection between the weak scale and the observed dark matter relic density, and are natural, with relatively light visible superpartners. We conclude with comments on interesting future directions.

Recent results from CDF and D0 collaborations favor a large $CP$ asymmetry in $B_s^0-{\overline{B}}_s^0$ mixing, while the standard model prediction is very small. Such a large phase may imply sizable new physics effects in $B_s^0-{\overline{B}}_s^0$ mixing. We compute the gluino-mediated supersymmetry contributions to $B_s^0-{\overline{B}}_s^0$ mixing, $B_s\to K^{(*)-}{K}^{(*)+}$ and $B\to X_s\gamma$ decays in the frame of the mass insertion approximation. Combining the constraints of $\Delta M_s,\Delta {\Gamma }_s,{\varphi }_s^{J/\psi \varphi }$, $\mathcal{B}(B_s\to K^{-}{K}^{+})$ and $\mathcal{B}(B\to X_s\gamma )$, we find that the effects of the constrained LL and RR insertions in $B_s\to K^{(*)-}{K}^{(*)+}$ decays are small because of the absence of gluino mass enhancement. For $m_{\tilde{g}}^2/m_{\tilde{q}}^2=9$, the constrained LR insertion can provide sizable contributions to all observables of $B_s\to K^{(*)-}{K}^{(*)+}$ decays except ${\mathcal{A}}_{CP}^{\mathrm{dir}}(B_s\to K^{-}{K}^{+})$, and many observables are sensitive to the modulus and the phase of the LR insertion parameter. Near future experiments at Fermilab Tevatron and CERN LHC-b can test these predictions and shrink/reveal the mass insertion parameter spaces.

By use of a single-instanton approximation the twist-three light-cone distribution amplitudes of the pion as well as the $p$-wave mesons, i.e., $f_0(1370)$, $K_0^{*}(1430)$, and $a_0(1450)$, are investigated within the framework of QCD moment sum rules with the inclusion of instanton effects based on the valence quark model. The results show that there is much change on light-cone distribution amplitudes due to the isospin- and chirality-dependent instanton contribution compared with the instanton-free ones. We find that the instanton-involved twist-three light-cone distribution amplitudes are non-positive-definite within some range of the momentum fraction and that there are rapid changes at two ends of the momentum fraction. To guarantee the convergence of moments using the method in this work, a low instanton density should be adopted; for instance, $n_c=\frac{1}{2}{\mathrm{fm}}^{-4}$. Possible ingredients which might have an impact on the results are briefly discussed. These light-cone distribution amplitudes may be helpful to analyze exclusive heavy-flavored processes.

We compute the magnetic susceptibility of the quark condensate and the polarization of quarks at zero temperature and in a uniform magnetic background. Our theoretical framework consists of two chiral models that allow us to treat self-consistently the spontaneous breaking of chiral symmetry: the linear $\sigma$-model coupled to quarks, dubbed quark-meson model, and the Nambu-Jona-Lasinio model. We also perform analytic estimates of the same quantities within the renormalized quark-meson model, both in the regimes of weak and strong fields. Our numerical results are in agreement with the recent literature; moreover, we confirm previous attice findings, related to the saturation of the polarization at large fields.

We explore the possibility to construct higher-twist parton distributions in a nucleon at some low reference scale from convolution integrals of the light-cone wave functions (WFs). To this end we introduce simple models for the four-particle nucleon WFs involving three valence quarks and a gluon with total orbital momentum zero, and estimate their normalization (WF at the origin) using QCD sum rules. We demonstrate that these WFs provide one with a reasonable description of both polarized and unpolarized parton densities at large values of the Bjorken variable $x\ge 0.5$. Twist-three parton distributions are then constructed as convolution integrals of $qqqg$ and the usual three-quark WFs. The cases of the polarized structure function $g_2(x,Q^2)$ and single transverse spin asymmetries are considered in detail. We find that the so-called gluon pole contribution to twist-three distributions relevant for single spin asymmetry vanishes in this model, but is generated perturbatively at higher scales by the evolution, in the spirit of Glück-Reya-Vogt parton distributions.

In practice the asymmetry, which is defined based on the angular distribution of the final states in scattering or decay processes, can be utilized to scrutinize underlying dynamics in and/or beyond the standard model (BSM). As one of the possible BSM physics which might be discovered early at the LHC, extra neutral gauge bosons $Z^{\prime }$’s are theoretically well motivated. Once $Z^{\prime }$’s are discovered at the LHC, it is crucial to discriminate different $Z^{\prime }$’s in various BSM. In principle such a task can be accomplished by measuring the angular distribution of the final states which are produced via $Z^{\prime }$-mediated processes. In the real data analysis, asymmetry is always adopted. In the literature several asymmetries have been proposed at the LHC. Based on these works, we stepped further on to study how to optimize the asymmetries in the left-right model and the sequential standard model, as the examples of BSM. In this paper, we examined four kinds of asymmetries, namely, rapidity-dependent forward-backward asymmetry, oneside forward-backward asymmetry, central charge asymmetry, and edge charge asymmetry (see text for details), with ${\ell }^{+}{\ell }^{-}$ ($\ell =e$, $\mu$), $b\overline{b}$, and $t\overline{t}$ as the final states. In the calculations with $b\overline{b}$ and $t\overline{t}$ final states, the QCD-induced higher-order contributions to the asymmetric cross section were also included. For each kind of final state, we estimated the four kinds of asymmetries and especially the optimal cut usually associated with the definition of the asymmetry. Our numerical results indicated that the capacity to discriminate $Z^{\prime }$ models can be improved by imposing the optimal cuts.

If neutrino tribimaximal mixing is explained by a non-Abelian discrete symmetry such as $A_4$, $T_7$, $\Delta (27)$, etc., the charged-lepton Higgs sector has a $Z_3$ residual symmetry (lepton flavor triality), which may be observed directly in the decay chain $H^0\to {\psi }_2^0{\overline{\psi }}_2^0$, then ${\psi }_2^0({\overline{\psi }}_2^0)\to l_i^{+}{l}_j^{-}(i\ne j)$, where $H^0$ is a standard-model–like Higgs boson and ${\psi }_2^0$ is a scalar particle needed for realizing the original discrete symmetry. If kinematically allowed, this unusual and easily detectable decay is observable at the LHC with $1{\mathrm{fb}}^{-1}$ for $E_{\mathrm{cm}}=7\mathrm{TeV}$.

We investigate the resonant leptogenesis scenario in the minimal $B-L$ extended standard model with the $B-L$ symmetry breaking at the TeV scale. Through detailed analysis of the Boltzmann equations, we show how much the resultant baryon asymmetry via leptogenesis is enhanced or suppressed, depending on the model parameters, in particular, the neutrino Dirac-Yukawa couplings and the TeV scale Majorana masses of heavy degenerate neutrinos. In order to consider a realistic case, we impose a simple ansatz for the model parameters and analyze the neutrino oscillation parameters and the baryon asymmetry via leptogenesis as a function of only a single $CP$ phase. We find that for a fixed $CP$ phase all neutrino oscillation data and the observed baryon asymmetry of the present Universe can be simultaneously reproduced.

We construct two more supersymmetric $E_6$ grand unified models with three generations within the framework of ${\mathbb{Z}}_{12}$ asymmetric orbifold compactification of the heterotic string theory. Such an asymmetric orbifold is missing in the classification in the literature, which concludes that only one $E_6$ model is possible. In both of the new models, an adjoint Higgs field is obtained in virtue of the diagonal embedding method. This method mods out the three $E_6$ factors of an even self-dual momentum-lattice by a permutation symmetry. In order to realize the $(E_6{)}^3$ even self-dual lattice, we utilize the lattice engineering technique. Among the eight possible orbifold actions in our setup, two lead to new $E_6$ models. Though these models still share the unsatisfactory issues with the known one, our discovery raises hopes that excellent models that solve all the problems in the supersymmetric grand unified models will be found in this framework.

It has been recently proposed that a sterile neutrino ${\nu }_h$ of mass $m_h=40–80\mathrm{MeV}$, mixing $|U_{\mu h}{|}^2\approx {10}^{-3}–{10}^{-2}$, lifetime ${\tau }_h\le {10}^{-9}\mathrm{s}$, and a dominant decay mode ${\nu }_h\to \nu \gamma$ could be the origin of the experimental anomalies observed at LSND and MiniBooNE. Such a particle would be abundant inside air showers, as it can be produced in kaon decays. We use the $Z$-moment method to evaluate its atmospheric flux and the frequency of its decays inside neutrino telescopes. We show that ${\nu }_h$ would imply around ${10}^4$ contained showers of energy between 0.1 and 100 TeV per year inside a 0.03 $\mathrm{k}{\mathrm{m}}^3$ telescope like ANTARES or the DeepCore in IceCube, while the standard background is 100 times smaller. Therefore, although it may be challenging from an experimental point of view, a search there could confirm this heavy-neutrino possibility.

In considering alternative higher-order gravity theories, one is liable to be motivated in pursuing models consistent and inspired by several candidates of a fundamental theory of quantum gravity. Indeed, motivations from string/$\mathrm{M}$ theory predict that scalar field couplings with the Gauss-Bonnet invariant, $G$, are important in the appearance of nonsingular early time cosmologies. In this work, we discuss the viability of an interesting alternative gravitational theory, namely, modified Gauss-Bonnet gravity or $f(G)$ gravity. We consider specific realistic forms of $f(G)$ analyzed in the literature that account for the late-time cosmic acceleration and that have been found to cure the finite-time future singularities present in the dark energy models. We present the general inequalities imposed by the energy conditions and use the recent estimated values of the Hubble, deceleration, jerk and snap parameters to examine the viability of the above-mentioned forms of $f(G)$ imposed by the weak energy condition.

We discuss the high energy neutrino emission from gamma-ray bursts resulting from the earliest generation (“population III”) stars forming in the Universe, whose core collapses into a black hole. These gamma-ray bursts are expected to produce a highly relativistic, magnetically dominated jet, where protons can be accelerated to ultrahigh energies. These interact with the photons produced by the jet, leading to ultrahigh energy photomeson neutrinos as well as secondary leptons and photons. The photon luminosity and the shock properties, and thus the neutrino spectrum, depend on the mass of the black holes as well as on the density of the surrounding external gas. We calculate the individual source neutrino spectral fluxes and the expected diffuse neutrino flux for various source parameters and evolution scenarios. Both the individual and diffuse signals appear detectable in the 1–300 PeV range with current and planned neutrino detectors such as IceCube and ARIANNA, provided the black hole mass is in excess of 30–100 solar masses. This provides a possible test for the debated mass of the progenitor stellar objects, as well as a probe for the early cosmological environment and the formation rate of the earliest structures.

Prospects are investigated for the discovery of massive hypergluons using data from the early runs of the Large Hadron Collider. A center of mass energy of 7 TeV and an integrated luminosity of $1{\mathrm{fb}}^{-1}$ or $5{\mathrm{fb}}^{-1}$ are assumed. A phenomenological Lagrangian is adopted to evaluate the cross section of a pair of colored vector bosons (colorons, $\tilde{\rho }$) decaying into four colored scalar resonances (hyperpions, $\tilde{\pi }$), which then decay into eight gluons. The dominant eight-jet background from the production of $8g$, $7g1q$, $6g2q$, and $5g3q$ is included. We find an abundance of signal events and that realistic cuts reduce the background enough to establish a $5\sigma$ signal for the coloron mass of up to 733 GeV with $1{\mathrm{fb}}^{-1}$ or 833 GeV with $5{\mathrm{fb}}^{-1}$.

Theories of flavor violation beyond the standard model typically suppose that the new contributions must be small, for example, suppressed by Yukawa couplings, as in minimal flavor violation. We show that this need not be true, presenting a case for flavor violation which maximally mixes the first- and third-generation flavors. As an example, we realize this scenario via new right-handed gauge bosons, which couple predominantly to the combinations $(u,b{)}_R$ and $(t,d{)}_R$. We show that this new flavor violation could be responsible for several anomalies, focusing, in particular, on the $B_d$, $B_s$ systems, and the Tevatron top forward-backward asymmetry.

Local operators in the bulk of anti-de Sitter can be represented as smeared operators in the dual conformal field theory. We show how to construct these bulk observables by requiring that the bulk operators commute at spacelike separation. This extends our previous work by taking interactions into account. Large-$N$ factorization plays a key role in the construction. We show diagrammatically how this procedure is related to bulk Feynman diagrams.

Kerr/CFT correspondence exhibits many remarkable connections between the near-horizon Kerr black hole and a conformal field theory (CFT). Recently, Castro, Maloney, and Strominger showed that a hidden conformal symmetry exists in the solution space of a Kerr black hole. In this paper we investigate a rotating black hole with four independent $U(1)$ charges derived from string theory which is known as the four-dimensional Cvetic-Youm solution, and we prove that the same hidden conformal symmetry also holds. We obtain the exact black hole entropy using the temperatures derived. The entropy and absorption cross section agree with the previous results [M. Cvetic and F. Larsen, Nucl. Phys. B506, 107 (1997).] and [M. Cvetic and F. Larsen, J. High Energy Phys. 09 (2009) 088.]. In addition, we clarify a previous explanation on the temperatures of the Cvetic-Youm solution’s dual CFT. This work provides more robust derivation of the hidden conformal symmetry of Kerr-like black holes and as well as Kerr/CFT correspondence.

We consider phenomenological consequences of the RS2-$n$ model with an infinite extra dimension, namely, the production, in high-energy collisions, of a photon or $Z$ boson escaping from our brane in association with a photon remaining on the brane. This would show up as process $e^{+}{e}^{-}\to \gamma +$ nothing. We compare the signal with the standard model background coming from $e^{+}{e}^{-}\to \gamma \overline{\nu }\nu$. We also make a comparison with $e^{+}{e}^{-}\to \gamma +$ nothing in the Arkani-Hamed–Dimopoulos–Dvali model.

We analyze the relation between teleparallelism and local Lorentz invariance. We show that generic modifications of the teleparallel equivalent to general relativity will not respect local Lorentz symmetry. We clarify the reasons for this and explain why the situation is different in general relativity. We give a prescription for constructing teleparallel equivalents for known theories. We also explicitly consider a recently proposed class of generalized teleparallel theories, called $f(T)$ theories of gravity, and show why restoring local Lorentz symmetry in such theories cannot lead to sensible dynamics, even if one gives up teleparallelism.

The kinematics of loop gravity can be given a manifestly Lorentz-covariant formulation: the conventional $SU(2)$-spin-network Hilbert space can be mapped to a space $\mathcal{K}$ of $SL(2,\mathbb{C})$ functions, where Lorentz covariance is manifest. $\mathcal{K}$ can be described in terms of a certain subset of the projected spin networks studied by Livine, Alexandrov and Dupuis. It is formed by $SL(2,\mathbb{C})$ functions completely determined by their restriction on $SU(2)$. These are square-integrable in the $SU(2)$ scalar product, but not in the $SL(2,\mathbb{C})$ one. Thus, $SU(2)$-spin-network states can be represented by Lorentz-covariant $SL(2,\mathbb{C})$ functions, as two-component photons can be described in the Lorentz-covariant Gupta-Bleuler formalism. As shown by Wolfgang Wieland in a related paper, this manifestly Lorentz-covariant formulation can also be directly obtained from canonical quantization. We show that the spinfoam dynamics of loop quantum gravity is locally $SL(2,\mathbb{C})$-invariant in the bulk, and yields states that are precisely in $\mathcal{K}$ on the boundary. This clarifies how the $SL(2,\mathbb{C})$ spinfoam formalism yields an $SU(2)$ theory on the boundary. These structures define a tidy Lorentz-covariant formalism for loop gravity.

We discuss the behavior of massive modes near a horizon based on a study of the dispersion relation and wave packet simulations of the Klein-Gordon equation. We point out an apparent paradox between two (in principle equivalent) pictures of black-hole evaporation through Hawking radiation. In the picture in which the evaporation is due to the emission of positive-energy modes, one immediately obtains a threshold for the emission of massive particles. In the picture in which the evaporation is due to the absorption of negative-energy modes, such a threshold apparently does not exist. We resolve this paradox by tracing the evolution of the positive-energy massive modes with an energy below the threshold. These are seen to be emitted and move away from the black-hole horizon, but they bounce back at a “red horizon” and are reabsorbed by the black hole, thus compensating exactly for the difference between the two pictures. For astrophysical black holes, the consequences are curious but do not affect the terrestrial constraints on observing Hawking radiation. For analogue-gravity systems with massive modes, however, the consequences are crucial and rather surprising.