We predict the isospin asymmetry well as the branching ratio for the decay $B\to K^{*}\gamma$ within QCD factorization using new anti–de Sitter/quantum chromodynamics (AdS/QCD) holographic distribution amplitudes (DAs) for the $K^{*}$ meson. Our prediction for the branching ratio agrees with that obtained using standard QCD sum-rules (SR) DAs and with experiment. More interestingly, our prediction for the isospin asymmetry using the AdS/QCD DA does not suffer from the end-point divergence encountered when using the corresponding SR DA. We predict an isospin asymmetry of 3.2% in agreement with the most recent average measured value of $(5.2\pm 2.6)\%$ quoted by the Particle Data Group.

The deviation of the measured value of the muon anomalous magnetic moment from the standard model prediction can be completely explained by the mixing of the muon with extra vectorlike leptons, $L$ and $E$, near the electroweak scale. This mixing simultaneously contributes to the muon mass. We show that the correlation between contributions to the muon mass and muon $g-2$ is controlled by the mass of the neutrino originating from the doublet $L$. Positive correlation, simultaneously explaining both measured values, requires this mass below 200 GeV. The decay rate of the Higgs boson to muon pairs is modified and, in the region of the parameter space that can explain the muon anomalous magnetic moment within one standard deviation, it ranges from 0.5 to 24 times the standard model prediction. In the same scenario, $h\to \gamma \gamma$ can be enhanced or lowered by $\sim 50\%$ from the standard model prediction. The explanation of the muon $g-2$ anomaly and predictions for $h\to \gamma \gamma$ are not correlated since these are controlled by independent parameters. This scenario can be embedded in a model with three complete vectorlike families featuring gauge coupling unification, sufficiently stable proton, and the Higgs quartic coupling remaining positive all the way to the grand unification scale.

After the discovery of a Higgs-like particle at the LHC, the determination of its spin quantum numbers across different channels will be the next step in arriving at a more precise understanding of the new state and its role in electroweak symmetry breaking. Event shape observables have been shown to provide extremely sensitive observables for the discrimination of the scalar Higgs boson’s $\mathcal{C}\mathcal{P}$ quantum numbers as a consequence of the different radiation patterns of Higgs production via gluon fusion vs weak boson fusion in the $pp\to X+2j$ selection. We show that a similar strategy serves to constrain the spin quantum numbers of the discovered particle as a function of the involved couplings. We also discuss the prospects of applying a similar strategy to future discoveries of Higgs-like particles.

We show that Mannheim’s conformal gravity program, whose potential has a term proportional to $1/r$ and another term proportional to $r$, does not reduce to Newtonian gravity at short distances, unless one assumes undesirable singularities of the mass density of the proton. Therefore, despite the claim that it successfully explains galaxy rotation curves, unless one assumes the singularities, it seems to be falsified by numerous Cavendish-type experiments performed at laboratories on Earth whose work have not found any deviations from Newton’s theory. Moreover, it can be shown that as long as the total mass of the proton is positive, Mannheim’s conformal gravity program leads to negative linear potential, which is problematic from the point of view of fitting galaxy rotation curves, which necessarily requires positive linear potential.

We present a first order formulation for the fourth order action of the new massive dual gravity in four dimensions, from which the dual equivalence with the massive Curtright theory is established. This proposal is easily generalized to arbitrary dimension. Also, we obtain the dual actions for massless and massive Curtright fields in $D$ dimensions.

We obtain exact matrix elements of physical operators of the ($1+1$)-dimensional nonlinear sigma model of an $\mathrm{SU}(N)$-valued bare field, in the ’t Hooft limit $N\to \infty$. Specifically, all the form factors of the Noether current and the stress-energy-momentum tensor are found with an integrable bootstrap method. These form factors are used to find vacuum expectation values of products of these operators.

We investigate, in the case of a Reissner–Nordström black hole, the definitions of gravitational energy and gravitational pressure that naturally arise in the framework of the teleparallel equivalent of general relativity. In particular, we calculate the gravitational energy enclosed by the event horizon of the black hole, $E$, and the radial pressure over it, $p$. With these quantities, we then analyze the thermodynamic relation $dE+pdV$ (as $p$ turns out to be a density, and $dV$ is actually given by $dV=drd\theta d\varphi$, in spherical-type coordinates). We compare the latter with the standard first law of black hole dynamics. Also, by identifying $TdS=dE+pdV$, we comment on a possible modification of the standard, Bekenstein–Hawking entropy-area relation due to the gravitational energy and gravitational pressure of the black hole. The infinitesimal variations in question refer to the Penrose process for a Reissner–Nordström black hole.

We construct a loop-induced seesaw model in a TeV scale theory with gauged $U(1{)}_{B\mathrm{\text{−}}L}$ symmetry. Light neutrino masses are generated at two-loop level, and right-handed neutrinos also obtain their masses by a one-loop effect. Multicomponent dark matter (DM) particles are included in our model due to the remnant discrete symmetry after the $B\mathrm{\text{−}}L$ symmetry breaking and the ${\mathbb{Z}}_2$ parity which is originally imposed to the model. We investigate the multicomponent DM properties in which we have two fermionic DM particles with different mass scales, $\mathcal{O}(10)\mathrm{GeV}$ and $\mathcal{O}(100–1000)\mathrm{GeV}$. The former mass corresponds to the lightest right-handed neutrino mass induced by the loop effect, and the latter one to the Standard Model gauge singlet fermion. We show each of the DM annihilation processes and compare them to the observation of relic abundance, together with the constraints of lepton flavor violation and active neutrino masses. Moreover, we show that our model has some parameter region allowed by the direct detection result reported by XENON100, and it is possible to search the region by the future XENON experiment.

We derive bounds on nine dimension-six operators involving electroweak gauge bosons and the Higgs boson from precision electroweak data. Four of these operators contribute at tree level, and five contribute only at one loop. Using the full power of effective field theory, we show that the bounds on the five loop-level operators are much weaker than previously claimed, and thus much weaker than bounds from tree-level processes at high-energy colliders.

While the total orbital angular momentum (OAM) of a definite quark flavor in a longitudinally-polarized nucleon can be obtained through a sum rule involving twist-two generalized parton distribution (GPDs), its distribution as a function of parton momentum in light-front coordinates is more complicated to define and measure because it involves intrinsically twist-three effects. In this paper, we consider two different parton OAM distributions. The first is manifestly gauge invariant, and its moments are local operators and calculable in lattice QCD. We show that it can potentially be measured through twist-three GPDs. The second is the much debated canonical OAM distribution natural in free-field theory and light-cone gauge. We show the latter in light-cone gauge can also be related to twist-three GPDs as well as quantum phase-space Wigner distributions, both being measurable in high-energy experiments.

We present an analysis of the forward-backward asymmetry in the production of top quark pairs at the Tevatron collider. We use novel Monte Carlo methods for merging matrix elements and parton showers to combine next-to-leading-order QCD predictions for $t\overline{t}$ and $t\overline{t}+\mathrm{\text{jet}}$ production. Theoretical uncertainties are quantified in detail. We find agreement with experimental data on the transverse-momentum dependence of the asymmetry.

Proton-proton total and elastic cross sections are considered in the Dakhno-Nikonov eikonal model [L. G. Dakhno and V. A. Nikonov, Eur. Phys. J. A 8, 209 (1999)] at ultrahigh energies. The model takes into account the quark structure of hadrons and the gluon structure of the supercritical Pomeron that results in color screening. The Pomeron is considered as an input interaction term. The model gives a reasonably good description of the pre-LHC and LHC data for $pp$ collisions with a growth of the type ${ln}^{2}s$ for total and elastic cross sections and ($\tau ={\mathbf{q}}_{\perp }^2{ln}^{2}s$) scaling for diffractive scattering. We present parameters of the supercritical Pomeron and provide predictions for the energy region $\sqrt{s}\sim {10}^2–{10}^4\mathrm{TeV}$.

We compare the discovery potential of the LHC for lepton number violating (LNV) signals with the sensitivity of current and future double beta decay experiments, assuming $0\nu \beta \beta$ decay is dominated by heavy particle exchange. We consider charged scalar, leptoquark and diquark mechanisms of $0\nu \beta \beta$ decay, covering the $0\nu \beta \beta$ decay operators with both, the smallest and largest, possible rates. We demonstrate, if $0\nu \beta \beta$ decay were found with a half-life below ${10}^{26}–{10}^{27}\mathrm{\text{years}}$ a positive signal should show up at the LHC, except for some particular cases of the leptoquark mechanism, and vice versa, if the LHC does not find any hints for LNV, a “short-range” explanation for a finite $0\nu \beta \beta$ decay half-life will be ruled out in most cases. We argue, if a positive LNV signal were found at the LHC, it is possible to identify the dominant contribution to $0\nu \beta \beta$. Two different kinds of observables which could provide such “model discriminating” power are discussed: different invariant mass peaks and the charge asymmetry.

We investigate holographic fermions in general asymptotically scaling geometries with hyperscaling violation exponent $\theta$, which is a natural generalization of fermions in Lifshitz space-time. We prove that the retarded Green functions in this background satisfy the angle-resolved photoemission spectroscopy sum rules by introducing a dynamical source on a UV brane for zero density fermionic systems. The big difference from the Lifshitz case is that the mass of probe fermions decoupled from the UV theory and thus has no longer been restricted by the unitarity bound. We also study finite density fermions at finite temperature, with dynamical exponent $z=2$. We find that the dispersion relation is linear, but the logarithm of the spectral function is not linearly related to the logarithm of $k_{\perp }=k-k_F$, independent of charge $q$ and $\theta$. Furthermore, we show that, with the increasing of charge, new branches of Fermi surfaces emerge and tend to gather together to form a shell-like structure when the charge reaches some critical value beyond which a wide band pattern appears in the momentum-charge plane. However, all sharp peaks will be smoothed out when $\theta$ increases, no matter how much large the charge is.

We calculate the electron self-energy in a magnetized QED plasma to the leading perturbative order in the coupling constant and to the linear order in an external magnetic field. We find that the chiral asymmetry of the normal ground state of the system is characterized by two new Dirac structures. One of them is the familiar chiral shift previously discussed in the Nambu-Jona-Lasinio model. The other structure is new. It formally looks like that of the chiral chemical potential but is an odd function of the longitudinal component of the momentum, directed along the magnetic field. The origin of this new parity-even chiral structure is directly connected with the long-range character of the QED interaction. The form of the Fermi surface in the weak magnetic field is determined.

We apply the Callan-Harvey anomaly-inflow mechanism to the study of QCD (chromoelectric) flux tubes, quark (pair) creation, and the chiral magnetic effect, using new variables from the Cho-Faddeev-Niemi decomposition of the gauge potential. A phenomenological description of chromoelectric flux tubes is obtained by studying a gauged Nambu–Jona-Lasinio effective Lagrangian, derived from the original QCD Lagrangian. At the quantum level, quark condensates in the QCD vacuum may form a vortexlike structure in a chromoelectric flux tube. Quark zero modes trapped in the vortex are chiral and lead to a two-dimensional gauge anomaly. To cancel it, an effective Chern-Simons coupling is needed and, hence, a topological charge density term naturally appears.

We study gravitational collapse of a spherical fluid in nonrelativistic general covariant theory of the Hořava-Lifshitz gravity with the projectability condition and an arbitrary coupling constant $\lambda$, where $|\lambda -1|$ characterizes the deviation of the theory from general relativity in the infrared limit. The junction conditions across the surface of a collapsing star are derived under the (minimal) assumption that the junctions be mathematically meaningful in terms of distribution theory. When the collapsing star is made of a homogeneous and isotropic perfect fluid, and the external region is described by a stationary spacetime, the problem reduces to the matching of six independent conditions. If the perfect fluid is pressureless (a dust fluid), it is found that the matching is also possible. In particular, in the case $\lambda =1$, the external spacetime is described by the Sch–(anti–)de Sitter solution written in Painlevé-Gullstrand coordinates. In the case $\lambda \ne 1$, the external spacetime is static but not asymptotically flat. Our treatment can be easily generalized to other versions of Hořava-Lifshitz gravity or, more generally, to any theory of higher-order derivative gravity.

We obtain the effective gravitational equations on the codimension-2 and codimension-1 branes in the cascading gravity model. We then apply our formulation to the cosmological case and obtain the effective Friedmann equations on the codimension-2 brane, which are generically given in terms of integro-differential equations. Adopting an approximation for which the thickness of the codimension-2 brane is much smaller than the Hubble horizon, we study the Minkowski and de Sitter codimension-2 brane solutions. Studying the cosmological solutions shows that the cascading model exhibits the features necessary for degravitation of the cosmological constant. We also show that only the branch which does not have the smooth limit to the self-accelerating branch in the five-dimensional model in the absence of the bulk gravity can satisfy the null energy condition as the criterion of the stability. Note that our solutions are obtained in a different setup from that of the original cascading gravity model in the sense that the codimension-1 brane contains matter fields other than the pure tension.

We present a detailed analysis of the orbital circular motion of electrically neutral test particles on the equatorial plane of the Kerr-Newman spacetime. Many details of the motion in the cases of black hole and naked singularity sources are pointed out. We identify four different types of orbital regions, which depend on the properties of the orbital angular momentum, and define four different kinds of naked singularities, according to the values of the charge-to-mass ratio of the source. It is shown that the presence of a particular type of counterrotating test particle is sufficient to uniquely identify naked singularities. It is pointed out that the structure of the stability regions can be used to differentiate between black holes and naked singularities.

We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter–dark energy coupling parameter $\xi =-{0.49}_{-0.31}^{+0.19}$ at 68% C.L. Moreover if Planck data are fitted to a coupled dark energy scenario, the constraint on the Hubble constant is relaxed to $H_0={72.1}_{-2.3}^{+3.2}\mathrm{km}/\mathrm{s}/\mathrm{Mpc}$, solving the tension with the Hubble Space Telescope (HST) value. We show that a combined $\mathrm{\text{PLANCK}}+\mathrm{HST}$ analysis provides significant evidence for coupled dark energy finding a nonzero value for the coupling parameter $\xi$, with $-0.90<\xi <-0.22$ at 95% C.L. We also consider the combined constraints from the Planck data plus the baryon acoustic oscillation measurements of the 6dF Galaxy Survey, the Sloan Digital Sky Survey and the Baron Oscillation Spectroscopic Survey.