The Weyl meson arises in theories with local scale invariance. It acts as a candidate for dark matter in a generalized standard model with local scale invariance. The Higgs particle is absent from the physical spectrum in this theory. We consider the quantization of this theory in detail, imposing suitable gauge-fixing conditions. We also consider a further generalization of this model which includes an additional real scalar field. In this theory a Higgs-like particle remains in the particle spectrum. Since this particle couples to the Weyl meson, it can lead to interesting phenomenology involving this vector field in particle colliders.

We present new exact solutions which presumably describe black holes in the background of a spatially flat, pressureless dark-matter– or dark matter plus dark energy ($\mathrm{DM}+\mathrm{DE}$)- or quintom-dominated Universe. These solutions generalize Lemaître-Tolman-Bondi metrics. For a dark-matter– or ($\mathrm{DM}+\mathrm{DE}$)-dominated universe, the area of the black hole apparent horizon (AH) decreases with the expansion of the Universe while that of the cosmic AH increases. However, for a quintom-dominated universe, the black hole AH first shrinks and then expands, while the cosmic AH first expands and then shrinks. A ($\mathrm{DM}+\mathrm{DE}$)-dominated universe containing a black hole will evolve to the Schwarzschild-de Sitter solution with both AHs approaching constant size. In a quintom-dominated universe, the black hole and cosmic AHs will coincide at a certain time, after which the singularity becomes naked, violating cosmic censorship.

The geometry of spinning codimension-two branes in anti–de Sitter (AdS) spacetime is analyzed in three and higher dimensions. The construction of nonextremal solutions is based on identifications in the covering of AdS space by isometries that have fixed points. The discussion focuses on the cases where the parameters of spinning states can be related to the velocity of a boosted static codimension-two brane. The resulting configuration describes a single spinning brane, or a set of intersecting branes, each one produced by an independent identification. The nature of the singularity is also examined, establishing that the AdS curvature acquires one in the form of a Dirac delta distribution. The stability of the branes is studied in the framework of Chern-Simons AdS supergravity. A class of branes, characterized by one free parameter, is shown to be stable when the Bogomol’nyi-Prasad-Sommerfeld (BPS) conditions are satisfied. In three dimensions, these stable branes are extremal, while in higher dimensions, the BPS branes are not the extremal ones.

Rotation of polarization in an external gravitational field is one of the effects of general relativity that can serve as a basis for its precision tests. A careful analysis of reference frames is crucial for a proper evaluation of this effect. We introduce an operationally-motivated local reference frame that allows for a particularly simple description. We present a solution of null geodesics in Kerr space-time that is organized around a new expansion parameter, allowing a better control of the series, and use it to calculate the resulting polarization rotation. While this rotation depends on the reference-frame convention, we demonstrate a gauge-independent geometric phase for closed paths in general space-times.

We construct explicitly all extremal instanton solutions to $\mathcal{N}=4$, $D=4$ supergravity truncated to one vector field (Einstein-Maxwell-dilaton-axion theory). These correspond to null geodesics of the target space of the sigma-model $G/H=Sp(4,\mathbb{R})/GL(2,\mathbb{R})$ obtained by compactification of four-dimensional Euclidean Einstein-Maxwell-dilaton-axion on a circle. They satisfy a no-force condition in terms of the asymptotic charges and part of them (corresponding to nilpotent orbits of the $Sp(4,\mathbb{R})$ U-duality) are presumably supersymmetric. The space of finite action solutions is found to be unexpectedly large and includes, besides the Euclidean versions of known Lorentzian solutions, a number of new asymptotically locally flat instantons endowed with electric, magnetic, dilaton and axion charges. We also describe new classes of charged asymptotically locally Euclidean instantons as well as some exceptional solutions. Our classification scheme is based on the algebraic classification of matrix generators according to their rank, according to the nature of the charge vectors, and according to the number of independent harmonic functions with unequal charges. Besides the nilpotent orbits of $G$, we find solutions which satisfy the asymptotic no-force condition, but are not supersymmetric. The renormalized on-shell action for instantons is calculated using the method of matched background subtraction.

We explore consequences of the idea that the cooling speed of white dwarfs can be interpreted in terms of axion emission. In this case, the Yukawa coupling to electrons has to be $g_{ae}\sim 1\times {10}^{-13}$, corresponding to an axion mass of a few meV. Axions then provide only a small fraction of the cosmic cold dark matter, whereas core-collapse supernovae release a large fraction of their energy in the form of axions. We estimate the diffuse supernova axion background in the Universe, consisting of 30 MeV-range axions with a radiation density comparable to the extragalactic background light. The diffuse supernova axion background would be challenging to detect. However, axions with white-dwarf-inspired parameters can be accessible in a next-generation axion helioscope.

The chiral $SU(3)$ Lagrangian with pseudoscalar and vector $D$ mesons and with the octet and decuplet baryons is considered. The leading two-body counter terms involving two baryon fields and two $D$ meson fields are constructed in the open-charm sector. There are 26 terms. A combined expansion in the inverse of the charm quark mass and in the inverse of the number of colors provides sum rules that reduce the number of free parameters down to 5 only. Our result shows the feasibility of a systematic computation of the open-charm baryon spectrum based on coupled-channel dynamics.

We study the charmonium spectrum including higher spin and gluonic excitations. We determine an upper limit on the mixing of the ${\eta }_c$ ground state with light pseudoscalar flavor-singlet mesons and investigate the mixing of charmonia near open charm thresholds with pairs of (excited) $D$ and $\overline{D}$ mesons. For charm and light valence quarks and $n_{\mathrm{F}}=2$ sea quarks, we employ the nonperturbatively improved Sheikholeslami-Wohlert (clover) action. Excited states are accessed using the variational technique, starting from a basis of suitably optimized operators. For some aspects of this study, the use of improved stochastic all-to-all propagators was essential.

We calculate the relativistic corrections of $J/\psi$, including electromagnetic corrections, to ${\chi }_{bJ}\to J/\psi J/\psi$ in the framework of nonrelativistic QCD factorization. The relativistic effects are found to increase the lower-order prediction for the decay width by about 10%, while the electromagnetism contribution is very small, about 0.2% for ${\chi }_{b0}$ and ${\chi }_{b2}$. The total branching ratios are predicted to be of order ${10}^{-5}$ for ${\chi }_{b0,b2}\to J/\psi J/\psi$, but ${10}^{-11}$ for ${\chi }_{b1}\to J/\psi J/\psi$, since there is only electromagnetism contribution in this channel. We predict it is possible to observe these reactions in LHC.

We find that, in the local V–A theory, the radiative corrections to pion $\beta$-decay involving the weak vector current, when evaluated in the current algebra (CA) formulation in which quarks are the fundamental underlying fields, show a small difference with the more elementary calculations based directly on the pion fields. We show that this difference arises from a specific short-distance effect that depends on the algebra satisfied by the weak and electromagnetic currents. On the other hand, we present a simple theoretical argument that concludes that this difference does not occur when the CA formulation is compared with the chiral perturbation theory ($\chi \mathrm{PT}$) approach. Comparisons with previous studies, and with a more recent calculation based on $\chi \mathrm{PT}$, are included. We also briefly review the important differences between the results in the local V–A theory and the standard model.

The gluon and ghost propagators in Landau gauge QCD are investigated using the Schwinger-Dyson equation approach. Working in Euclidean spacetime, we solve for these propagators using a selection of vertex inputs, initially for the ghost equation alone and then for both propagators simultaneously. The results are shown to be highly sensitive to the choices of vertices. We favor the infrared finite ghost solution from studying the ghost equation alone where we argue for a specific unique solution. In order to solve this simultaneously with the gluon using a dressed-one-loop truncation, we find that a nontrivial full ghost-gluon vertex is required in the vanishing gluon momentum limit. The self-consistent solutions we obtain correspond to having a masslike term in the gluon propagator dressing, in agreement with similar studies supporting the long-held proposal of Cornwall.

We report an analysis of charmless hadronic decays of charged $B$ mesons to the final state $K^{+}{\pi }^0{\pi }^0$, using a data sample of $(470.9\pm 2.8)\times {10}^6$ $B\overline{B}$ events collected with the BABAR detector at the ${\rm Y}(4S)$ resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and $CP$ asymmetry to be $\mathcal{B}(B^{+}\to K^{+}{\pi }^0{\pi }^0)=(16.2\pm 1.2\pm 1.5)\times {10}^{-6}$ and $A_{CP}(B^{+}\to K^{+}{\pi }^0{\pi }^0)=-0.06\pm 0.06\pm 0.04$, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the $B^{+}\to K^{*}(892{)}^{+}{\pi }^0$, $B^{+}\to f_0(980)K^{+}$, and $B^{+}\to {\chi }_{\mathrm{c}0}{K}^{+}$ quasi-two-body decays. We report the world’s best measurements of the branching fraction and $CP$ asymmetry of the $B^{+}\to K^{+}{\pi }^0{\pi }^0$ and $B^{+}\to K^{*}(892{)}^{+}{\pi }^0$ channels.

The processes ${\eta }_c^{\prime }\to {\rho }^0{\rho }^0$, $K^{*0}{\overline{K}}^{*0}$, and $\varphi \varphi$ are searched for using a sample of $1.06\times {10}^8$ ${\psi }^{\prime }$ events collected with the BESIII detector at the BEPCII collider. No signals are observed in any of the three final states. The upper limits on the decay branching fractions are determined to be $\mathcal{B}({\eta }_c^{\prime }\to {\rho }^0{\rho }^0)<3.1\times {10}^{-3}$, $\mathcal{B}({\eta }_c^{\prime }\to K^{*0}{\overline{K}}^{*0})<5.4\times {10}^{-3}$, and $\mathcal{B}({\eta }_c^{\prime }\to \varphi \varphi )<2.0\times {10}^{-3}$ at the 90% confidence level. The upper limits are lower than the existing theoretical predictions.

The linearized Einstein field equations with the renormalized stress tensor of a massless quantum scalar field as source are solved in the 4-dimensional spacetime near an infinite plane boundary. The motion of particles and light is investigated disclosing a variety of effects. For instance, it is shown that light rays initially parallel to the boundary do not bend. On the other hand, under the same initial conditions, particles will be affected by the presence of the quantum field, being accelerated toward the plane boundary or departing from it depending on the value of the curvature coupling parameter $\xi$. It is suggested that $\xi$ can be set by measuring the spectral deviation of a light ray travelling perpendicularly to the boundary.

The Hamiltonian formulation of scalar-tensor theories of gravity is derived from their Lagrangian formulation by Hamiltonian analysis. The Hamiltonian formalism marks off two sectors of the theories by the coupling parameter $\omega (\varphi )$. In the sector of $\omega (\varphi )=-\frac{3}{2}$, the feasible theories are restricted and a new primary constraint generating conformal transformations of spacetime is obtained, while in the other sector of $\omega (\varphi )\ne -\frac{3}{2}$, the canonical structure and constraint algebra of the theories are similar to those of general relativity coupled with a scalar field. By canonical transformations, we further obtain the connection-dynamical formalism of the scalar-tensor theories with real $su(2)$ connections as configuration variables in both sectors. This formalism enables us to extend the scheme of nonperturbative loop quantum gravity to the scalar-tensor theories. The quantum kinematical framework for the scalar-tensor theories is rigorously constructed. Both the Hamiltonian constraint operator and master constraint operator are well defined and proposed to represent quantum dynamics. Thus the loop quantum gravity method is also valid for general scalar-tensor theories.

The anti–de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Hořava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Hořava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Hořava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in $\lambda =1$ Hořava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter $ϵ$ close to unity. Sufficiently charged flat black holes for $ϵ$ close to unity, and sufficiently charged positively curved black holes with $ϵ$ close to zero, are also unstable. The implication to the Hořava-Lifshitz holographic superconductor is discussed.

In classical general relativity the Cauchy horizon within a two-horizon black hole is unstable via a phenomenon known as mass inflation, in which the mass parameter (and the spacetime curvature) of the black hole diverges at the Cauchy horizon. Here we study this effect for loop black holes—quantum gravitationally corrected black holes from loop quantum gravity—whose construction alleviates the $r=0$ singularity present in their classical counterparts. We use a simplified model of mass inflation, which makes use of the generalized Dray-’t Hooft relation, to conclude that the Cauchy horizon of loop black holes indeed results in a curvature singularity similar to that found in classical black holes. The Dray-’t Hooft relation is of particular utility in the loop black hole because it does not directly rely upon Einstein’s field equations. We elucidate some of the interesting and counterintuitive properties of the loop black hole, and corroborate our results using an alternate model of mass inflation due to Ori.

In anomaly-mediated supersymmetry breaking, superpartners in a hidden sector have masses that are proportional to couplings squared and so naturally freeze out with the desired dark matter relic density for a large range of masses. We present an extremely simple realization of this possibility, with WIMPless dark matter arising from a hidden sector that is supersymmetric QED with $N_F$ flavors. Dark matter is multicomponent, composed of hidden leptons and sleptons with masses anywhere from 10 GeV to 10 TeV, and hidden photons provide the thermal bath. The dark matter self-interacts through hidden sector Coulomb scatterings that are potentially observable. In addition, the hidden photon contribution to the number of relativistic degrees of freedom is in the range $\Delta N_{\mathrm{eff}}\sim 0–2$, and, if the hidden and visible sectors were initially in thermal contact, the model predicts $\Delta N_{\mathrm{eff}}\sim 0.2–0.4$. Data already taken by Planck may provide evidence of such deviations.

ATLAS and CMS have provided hints for the existence of a Higgs-like particle with mass of about 144 GeV with production cross section into standard decay channels which is about 50% that of the standard model Higgs boson. We show that this 50% suppression is exactly what the mirror matter model predicts when the two scalar mass eigenstates, each required to be maximal admixtures of a standard and mirror-Higgs boson, are separated in mass by more than their decay widths but less than the experimental resolution. We discuss prospects for the future confirmation of this interesting hint for nonstandard Higgs physics.

The BABAR Collaboration has recently reported products of branching fractions that include $B$ meson semileptonic decays into final states with charged and neutral $D_1(2420)$ and $D_2^{*}(2460)$, two narrow orbitally excited charmed mesons. We evaluate these branching fractions, together with those concerning $D_0^{*}(2400)$ and $D_1^{\prime }(2430)$ mesons, within the framework of a constituent quark model. The calculation is performed in two steps, one of which involves a semileptonic decay and the other is mediated by a strong process. Our results are in agreement with the experimental data. We also extend the study to semileptonic decays of $B_s$ into orbitally excited charmed-strange mesons, providing predictions to the possible measurements to be carried out at LHC.